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Available in 12 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-12" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">12 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AD%D9%8A%D8%B2_%D9%87%D8%A7%D9%85%D8%AF" title="حيز هامد – Arabic" lang="ar" hreflang="ar" data-title="حيز هامد" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Dead_space" title="Dead space – Danish" lang="da" hreflang="da" data-title="Dead space" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Totraum_(Atmung)" title="Totraum (Atmung) – German" lang="de" hreflang="de" data-title="Totraum (Atmung)" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Espacio_muerto_(fisiolog%C3%ADa)" title="Espacio muerto (fisiología) – Spanish" lang="es" hreflang="es" data-title="Espacio muerto (fisiología)" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Espace_mort_respiratoire" title="Espace mort respiratoire – French" lang="fr" hreflang="fr" data-title="Espace mort respiratoire" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%87%D5%B6%D5%B9%D5%A1%D5%BC%D5%A1%D5%AF%D5%A1%D5%B6_%D5%B8%D6%82%D5%B2%D5%AB%D5%B6%D5%A5%D6%80%D5%AB_%D5%B4%D5%A5%D5%BC%D5%B5%D5%A1%D5%AC_%D5%BF%D5%A1%D6%80%D5%A1%D5%AE%D5%B8%D6%82%D5%A9%D5%B5%D5%B8%D6%82%D5%B6" title="Շնչառական ուղիների մեռյալ տարածություն – Armenian" lang="hy" hreflang="hy" data-title="Շնչառական ուղիների մեռյալ տարածություն" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A0%D7%A4%D7%97_%D7%9E%D7%AA" title="נפח מת – Hebrew" lang="he" hreflang="he" data-title="נפח מת" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E6%AD%BB%E8%85%94" title="死腔 – Japanese" lang="ja" hreflang="ja" data-title="死腔" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/D%C3%B8dt_luftrom_(fysiologi)" title="Dødt luftrom (fysiologi) – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Dødt luftrom (fysiologi)" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Espa%C3%A7o_morto" title="Espaço morto – Portuguese" lang="pt" hreflang="pt" data-title="Espaço morto" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9C%D1%80%D1%82%D0%B2%D0%B8_%D0%BF%D1%80%D0%BE%D1%81%D1%82%D0%BE%D1%80_(%D1%84%D0%B8%D0%B7%D0%B8%D0%BE%D0%BB%D0%BE%D0%B3%D0%B8%D1%98%D0%B0)" title="Мртви простор (физиологија) – Serbian" lang="sr" hreflang="sr" data-title="Мртви простор (физиологија)" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Dead_space_(anatomi)" title="Dead space (anatomi) – Swedish" lang="sv" hreflang="sv" data-title="Dead space 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<div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Inhaled air not part of gas exchange</div> <p class="mw-empty-elt"> </p> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox"><caption class="infobox-title">Blood gas, acid-base, and gas exchange terms</caption><tbody><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">P<sub>a</sub></var>O<sub>2</sub></th><td class="infobox-data">Arterial oxygen tension, or partial pressure</td></tr><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">P<sub>A</sub></var>O<sub>2</sub></th><td class="infobox-data">Alveolar oxygen tension, or partial pressure</td></tr><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">P<sub>a</sub></var>CO<sub>2</sub></th><td class="infobox-data">Arterial carbon dioxide tension, or partial pressure</td></tr><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">P<sub>A</sub></var>CO<sub>2</sub></th><td class="infobox-data">Alveolar carbon dioxide tension, or partial pressure</td></tr><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">P<sub>v</sub></var>O<sub>2</sub></th><td class="infobox-data">Oxygen tension of mixed venous blood</td></tr><tr><th scope="row" class="infobox-label"><i>P</i><sub>(<i>A</i>-<i>a</i>)</sub>O<sub>2</sub></th><td class="infobox-data">Alveolar-arterial oxygen tension difference. The term formerly used (<span class="nowrap">A-a D<style data-mw-deduplicate="TemplateStyles:r1123817410">.mw-parser-output .template-chem2-su{display:inline-block;font-size:80%;line-height:1;vertical-align:-0.35em}.mw-parser-output .template-chem2-su>span{display:block;text-align:left}.mw-parser-output sub.template-chem2-sub{font-size:80%;vertical-align:-0.35em}.mw-parser-output sup.template-chem2-sup{font-size:80%;vertical-align:0.65em}</style><span class="chemf nowrap">O<sub class="template-chem2-sub">2</sub></span></span>) is discouraged.</td></tr><tr><th scope="row" class="infobox-label"><i>P</i><sub>(<i>a</i>/<i>A</i>)</sub>O<sub>2</sub></th><td class="infobox-data">Alveolar-arterial tension ratio; <i>P<sub>a</sub></i>O<sub>2</sub>:<i>P<sub>A</sub></i>O<sub>2</sub> The term <i><a href="/w/index.php?title=Oxygen_exchange_index&action=edit&redlink=1" class="new" title="Oxygen exchange index (page does not exist)">oxygen exchange index</a></i> describes this ratio.</td></tr><tr><th scope="row" class="infobox-label"><i>C</i><sub>(<i>a</i>-<i>v</i>)</sub>O<sub>2</sub></th><td class="infobox-data">Arteriovenous oxygen content difference</td></tr><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">S<sub>a</sub></var>O<sub>2</sub></th><td class="infobox-data">Oxygen saturation of the hemoglobin of arterial blood</td></tr><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">S<sub>p</sub></var>O<sub>2</sub></th><td class="infobox-data">Oxygen saturation as measured by pulse oximetry</td></tr><tr><th scope="row" class="infobox-label"><var style="padding-right: 1px;">C<sub>a</sub></var>O<sub>2</sub></th><td class="infobox-data">Oxygen content of arterial blood</td></tr><tr><th scope="row" class="infobox-label">pH</th><td class="infobox-data">Symbol relating the hydrogen ion concentration or activity of a solution to that of a standard solution; approximately equal to the negative logarithm of the hydrogen ion concentration. pH is an indicator of the relative acidity or alkalinity of a solution</td></tr><tr><td colspan="2" class="infobox-navbar"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}</style><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Blood_gas,_acid-base,_%26_gas_exchange_terms" title="Template:Blood gas, acid-base, & gas exchange terms"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Blood_gas,_acid-base,_%26_gas_exchange_terms" title="Template talk:Blood gas, acid-base, & gas exchange terms"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Blood_gas,_acid-base,_%26_gas_exchange_terms" title="Special:EditPage/Template:Blood gas, acid-base, & gas exchange terms"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <p><b>Dead space</b> is the volume of air that is inhaled that does not take part in the gas exchange, because it either remains in the conducting airways or reaches alveoli that are <a href="/wiki/Ventilation/perfusion_ratio" title="Ventilation/perfusion ratio">not perfused or poorly perfused</a>. It means that not all the air in each <a href="/wiki/Breath" class="mw-redirect" title="Breath">breath</a> is available for the exchange of <a href="/wiki/Oxygen" title="Oxygen">oxygen</a> and <a href="/wiki/Carbon_dioxide" title="Carbon dioxide">carbon dioxide</a>. <a href="/wiki/Mammal" title="Mammal">Mammals</a> breathe in and out of their lungs, wasting that part of the inhalation which remains in the conducting airways where no gas exchange can occur. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Components">Components</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=1" title="Edit section: Components"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><i>Total dead space</i> (also known as <b>physiological dead space</b>) is the sum of the anatomical dead space and the alveolar dead space. </p><p>Benefits do accrue to a seemingly wasteful design for ventilation that includes dead space.<sup id="cite_ref-WestPhysiology_1-0" class="reference"><a href="#cite_note-WestPhysiology-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <ol><li>Carbon dioxide is retained, making a <a href="/wiki/Acid%E2%80%93base_homeostasis" title="Acid–base homeostasis">bicarbonate-buffered</a> blood and interstitium possible.</li> <li>Inspired air is brought to body temperature, increasing the affinity of <a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a> for <a href="/wiki/Oxygen" title="Oxygen">oxygen</a>, improving O<sub>2</sub> uptake.<sup id="cite_ref-Williams1996_2-0" class="reference"><a href="#cite_note-Williams1996-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li> <li>Particulate matter is trapped on the mucus that lines the conducting airways, allowing its removal by <a href="/wiki/Mucociliary_clearance" title="Mucociliary clearance">mucociliary transport</a>.</li> <li>Inspired air is humidified, improving the quality of airway mucus.<sup id="cite_ref-Williams1996_2-1" class="reference"><a href="#cite_note-Williams1996-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li></ol> <p>In humans, about a third of every resting breath has no change in O<sub>2</sub> and CO<sub>2</sub> levels. In adults, it is usually in the range of 150 mL.<sup id="cite_ref-wasted_3-0" class="reference"><a href="#cite_note-wasted-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>Dead space can be increased (and better envisioned) by breathing through a long tube, such as a <a href="/wiki/Snorkel_(swimming)" title="Snorkel (swimming)">snorkel</a>. Although one end of the snorkel is open to the air, when the wearer breathes in, they inhale a significant quantity of air that remained in the snorkel from the previous exhalation. Therefore, a snorkel increases the person's dead space by adding even more airway that does not participate in gas exchange. </p> <div class="mw-heading mw-heading3"><h3 id="Anatomical_dead_space">Anatomical dead space</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=2" title="Edit section: Anatomical dead space"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Anatomical dead space is the volume of the conducting airways (from the <a href="/wiki/Nose" title="Nose">nose</a>, <a href="/wiki/Mouth" title="Mouth">mouth</a> and <a href="/wiki/Vertebrate_trachea" class="mw-redirect" title="Vertebrate trachea">trachea</a> to the terminal bronchioles). These conduct gas to the <a href="/wiki/Pulmonary_alveolus" title="Pulmonary alveolus">alveoli</a> but no gas exchange occurs here. In healthy lungs where the alveolar dead space is small, <a href="/wiki/Fowler%27s_method" class="mw-redirect" title="Fowler's method">Fowler's method</a> accurately measures the anatomic dead space using a single breath <a href="/wiki/Nitrogen" title="Nitrogen">nitrogen</a> washout technique.<sup id="cite_ref-fowler1948_4-0" class="reference"><a href="#cite_note-fowler1948-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>The normal value for dead space volume (in mL) is approximately the lean mass of the body (in pounds), and averages about a third of the resting <a href="/wiki/Tidal_volume" title="Tidal volume">tidal volume</a> (450-500 mL). In Fowler's original study, the anatomic dead space was 156 ± 28 mL (n=45 males) or 26% of their tidal volume.<sup id="cite_ref-fowler1948_4-1" class="reference"><a href="#cite_note-fowler1948-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Despite the flexibility of the trachea and smaller conducting airways, their overall volume (i.e. the anatomic dead space) changes little with bronchoconstriction or when breathing hard during exercise.<sup id="cite_ref-fowler1948_4-2" class="reference"><a href="#cite_note-fowler1948-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>As birds have a longer and wider trachea than mammals the same size, they have a disproportionately large anatomic dead space, reducing the airway resistance. This adaptation does not impact gas exchange because birds flow air through their lungs - they do not breathe in and out like mammals.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Alveolar_dead_space">Alveolar dead space</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=3" title="Edit section: Alveolar dead space"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Alveolar dead space is defined as the difference between the physiologic dead space and the anatomic dead space. It is contributed to by all the terminal respiratory units that are over-ventilated relative to their perfusion. Therefore it includes, firstly those units that are ventilated but not perfused, and secondly those units which have a ventilation-perfusion ratio greater than one. </p><p>Alveolar dead space is negligible in healthy individuals, but it can increase dramatically in some <a href="/wiki/Lung_disease" class="mw-redirect" title="Lung disease">lung diseases</a> due to <a href="/wiki/Ventilation-perfusion_mismatch" class="mw-redirect" title="Ventilation-perfusion mismatch">ventilation-perfusion mismatch</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Calculating">Calculating</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=4" title="Edit section: Calculating"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Just as dead space wastes a fraction of the inhaled breath, dead space dilutes alveolar air during exhalation. By quantifying this dilution, it is possible to measure physiological dead space, employing the concept of <a href="/wiki/Mass_balance" title="Mass balance">mass balance</a>, as expressed by the <a href="/wiki/Bohr_equation" title="Bohr equation">Bohr equation</a>.<sup id="cite_ref-Bohr_8-0" class="reference"><a href="#cite_note-Bohr-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {V_{d}}{V_{t}}}={\frac {P_{a\,{\ce {CO2}}}-P_{e\,{\ce {CO2}}}}{P_{a\,{\ce {CO2}}}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <msub> <mi>V</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> <msub> <mi>V</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>t</mi> </mrow> </msub> </mfrac> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </mrow> </msub> <mo>−</mo> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>e</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </mrow> </msub> </mrow> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </mrow> </msub> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {V_{d}}{V_{t}}}={\frac {P_{a\,{\ce {CO2}}}-P_{e\,{\ce {CO2}}}}{P_{a\,{\ce {CO2}}}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/a069182e5ca1638350e4ae02e179ef9b488e5b34" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.838ex; width:22.511ex; height:6.843ex;" alt="{\displaystyle {\frac {V_{d}}{V_{t}}}={\frac {P_{a\,{\ce {CO2}}}-P_{e\,{\ce {CO2}}}}{P_{a\,{\ce {CO2}}}}}}"></span></dd></dl></dd> <dd>where <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{d}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>V</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle V_{d}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e4886218a3e61311802a3c9b49140ba9b1f5698c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.447ex; height:2.509ex;" alt="{\displaystyle V_{d}}"></span> is the dead space volume and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V_{t}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>V</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>t</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle V_{t}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0dd750c2c4872a9c271f0567dc733923b4a1c7eb" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.181ex; height:2.509ex;" alt="{\displaystyle V_{t}}"></span> is the tidal volume; <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle P_{a\,{\ce {CO2}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle P_{a\,{\ce {CO2}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3962abec04f1dd6ce38217f707e402244237d20a" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.171ex; width:6.278ex; height:3.009ex;" alt="{\displaystyle P_{a\,{\ce {CO2}}}}"></span> is the partial pressure of carbon dioxide in the arterial blood, and</dd> <dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle P_{e\,{\ce {CO2}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>e</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle P_{e\,{\ce {CO2}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/29bd5ec091658fb103cf02a193308aa3c71ad8ed" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.171ex; width:6.174ex; height:3.009ex;" alt="{\displaystyle P_{e\,{\ce {CO2}}}}"></span> is the partial pressure of carbon dioxide in the mixed expired (exhaled) air.</dd></dl></dd></dl> <div class="mw-heading mw-heading3"><h3 id="Physiological_dead_space">Physiological dead space</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=5" title="Edit section: Physiological dead space"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The Bohr equation is used to measure physiological dead space. Unfortunately, the concentration of carbon dioxide (CO<sub>2</sub>) in alveoli is required to use the equation but this is not a single value as the ventilation-perfusion ratio is different in different lung units both in health and in disease. In practice, the arterial partial pressure of CO<sub>2</sub> is used as an estimate of the average alveolar partial pressure of CO<sub>2</sub>, a modification introduced by Henrik Enghoff in 1938 (Enghoff H. Volumen inefficax. Bemerkungen zur Frage des schadlichen Raumes. Upsala Läkarefören Forhandl., 44:191-218, 1938). In effect, the single arterial pCO<sub>2</sub> value averages out the different pCO<sub>2</sub> values in the different alveoli, and so makes the Bohr equation useable. </p><p>The quantity of CO<sub>2</sub> exhaled from the healthy alveoli is diluted by the air in the conducting airways (anatomic dead space) and by gas from alveoli that are over-ventilated in relation to their perfusion. This dilution factor can be calculated once the mixed expired pCO<sub>2</sub> in the exhaled breath is determined (either by electronically monitoring the exhaled breath or by collecting the exhaled breath in a gas impermeant bag (a Douglas bag) and then measuring the pCO<sub>2</sub> of the mixed expired gas in the collection bag). Algebraically, this dilution factor will give us the physiological dead space as calculated by the Bohr equation: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {V_{\ce {physiological\,dead\,space}}}{V_{t}}}={\frac {P_{a\,{\ce {CO2}}}-P_{\ce {mixed\,expired\,CO2}}}{P_{a\,{\ce {CO2}}}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <msub> <mi>V</mi> <mrow class="MJX-TeXAtom-ORD"> <mtext>physiological</mtext> <mspace width="thinmathspace" /> <mtext>dead</mtext> <mspace width="thinmathspace" /> <mtext>space</mtext> </mrow> </msub> <msub> <mi>V</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>t</mi> </mrow> </msub> </mfrac> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </mrow> </msub> <mo>−</mo> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mtext>mixed</mtext> <mspace width="thinmathspace" /> <mtext>expired</mtext> <mspace width="thinmathspace" /> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </msub> </mrow> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msubsup> <mtext>CO</mtext> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mspace width="0pt" height="0pt" depth=".2em" /> </mrow> </msubsup> </mrow> </mrow> </msub> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {V_{\ce {physiological\,dead\,space}}}{V_{t}}}={\frac {P_{a\,{\ce {CO2}}}-P_{\ce {mixed\,expired\,CO2}}}{P_{a\,{\ce {CO2}}}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/26cf217ae796e505c1caf7fc292b53bae1cedefa" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.838ex; width:48.057ex; height:6.843ex;" alt="{\displaystyle {\frac {V_{\ce {physiological\,dead\,space}}}{V_{t}}}={\frac {P_{a\,{\ce {CO2}}}-P_{\ce {mixed\,expired\,CO2}}}{P_{a\,{\ce {CO2}}}}}}"></span></dd></dl> <div class="mw-heading mw-heading3"><h3 id="Alveolar_dead_space_2">Alveolar dead space</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=6" title="Edit section: Alveolar dead space"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The alveolar dead space is determined as the difference between the physiological dead space (measured using the Enghoff modification of the Bohr equation) and the anatomic dead space (measured using Fowler's single breath technique). </p><p>A clinical index of the size of the alveolar dead space is the difference between the arterial partial pressure of CO<sub>2</sub> and the end-tidal partial pressure of CO<sub>2</sub>. </p> <div class="mw-heading mw-heading3"><h3 id="Anatomic_dead_space">Anatomic dead space</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=7" title="Edit section: Anatomic dead space"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A different maneuver is employed in measuring anatomic dead space: the test subject breathes all the way out, inhales deeply from a 0% nitrogen gas mixture (usually 100% oxygen) and then breathes out into equipment that measures nitrogen and gas volume. This final exhalation occurs in three phases. The first phase (phase 1) has no nitrogen as that is gas that is 100% oxygen in the anatomic dead space. The nitrogen concentration then rapidly increases during the brief second phase (phase 2) and finally reaches a plateau in the third phase (phase 3). The <b>anatomic dead space</b> is equal to the volume exhaled during the first phase plus the volume up to the mid-point of the transition from phase 1 to phase 3. </p> <div class="mw-heading mw-heading2"><h2 id="Ventilated_patient">Ventilated patient</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=8" title="Edit section: Ventilated patient"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The depth and frequency of our breathing is determined by chemoreceptors and the brainstem, as modified by a number of subjective sensations. When mechanically <a href="/wiki/Medical_ventilator" class="mw-redirect" title="Medical ventilator">ventilated</a> using a mandatory mode, the patient breathes at a rate and tidal volume that is dictated by the machine. Because of dead space, taking deep breaths more slowly (e.g. ten 500 ml breaths per minute) is more effective than taking shallow breaths quickly (e.g. twenty 250 ml breaths per minute). Although the amount of gas per minute is the same (5 L/min), a large proportion of the shallow breaths is dead space, which does not help oxygen to get into the blood.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2023)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="Mechanical_dead_space">Mechanical dead space</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=9" title="Edit section: Mechanical dead space"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><b>Mechanical dead space</b> or <b>external dead space</b> is volume in the passages of a <a href="/wiki/Breathing_apparatus" title="Breathing apparatus">breathing apparatus</a> in which the <a href="/wiki/Breathing_gas" title="Breathing gas">breathing gas</a> flows in both directions as the user breathes in and out, causing the last exhaled gas to be immediately inhaled on the next breath, increasing the necessary tidal volume and respiratory effort to get the same amount of usable air or breathing gas, and increasing the accumulation of <a href="/wiki/Carbon_dioxide" title="Carbon dioxide">carbon dioxide</a> from shallow breaths. It is in effect an external extension of the physiological dead space.<sup id="cite_ref-Bryce_et_al_2020_10-0" class="reference"><a href="#cite_note-Bryce_et_al_2020-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>It can be reduced by: </p> <ul><li>Using separate intake and exhaust passages with one-way valves placed in each passage, usually between each passage and the mouthpiece. This limits the dead space to between the non return valves and the user's mouth or nose. Not all of the volume between the non-return valves is necessarily dead space, as exhaled gas in narrow ducting will not necessarily mix well with fresh gas from inhalation ducting, but exhaled gas beyond the exhaust non-return valves can reasonably be assumed to not mix with fresh gas if the valves function correctly. The total effective dead space can be minimized by keeping the volume of this external dead space as small as possible, but this should not unduly increase the work of breathing, which can become critical in breathing apparatus used at high ambient pressure.<sup id="cite_ref-Mitchell_et_al_2007_11-0" class="reference"><a href="#cite_note-Mitchell_et_al_2007-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></li> <li>With a <a href="/wiki/Full_face_mask" class="mw-redirect" title="Full face mask">full face mask</a> or <a href="/wiki/Diving_helmet#Lightweight_demand_helmets" title="Diving helmet">demand diving helmet</a>: <ul><li>Keeping the inside volume small</li> <li>Having a small internal <a href="/wiki/Orinasal_mask" title="Orinasal mask">orinasal mask</a> inside the main mask or helmet, which separates the external respiratory passage from the rest of the mask interior.</li> <li>In a few models of full face mask a mouthpiece like those used on diving regulators is fitted, which has the same function as an orinasal mask, but can further reduce the volume of the external dead space, at the cost of forcing mouth-breathing (and acting like a gag, preventing clear talking).</li></ul></li></ul> <div class="mw-heading mw-heading3"><h3 id="Effects">Effects</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=10" title="Edit section: Effects"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Dead space reduces the amount of fresh breathing gas which reaches the alveoli during each breath. This reduces the oxygen available for gas exchange, and the amount of carbon dioxide that can be removed. The buildup of carbon dioxide is usually the more noticeable effect unless the breathing gas is hypoxic as occurs at high altitude. The body can compensate to some extent by increasing the volume of inspired gas, but this also increases <a href="/wiki/Work_of_breathing" title="Work of breathing">work of breathing</a>, and is only effective when the ratio of dead space to tidal volume is reduced sufficiently to compensate for the additional carbon dioxide load due to the increased work of breathing. Continued buildup of carbon dioxide will lead to <a href="/wiki/Hypercapnia" title="Hypercapnia">hypercapnia</a> and <a href="/wiki/Respiratory_distress" class="mw-redirect" title="Respiratory distress">respiratory distress</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Changes_with_exercise">Changes with exercise</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=11" title="Edit section: Changes with exercise"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In healthy people, V<sub>d</sub> is about one-third of V<sub>t</sub> at rest and decreases with exercise to about one-fifth mainly due to an increase in V<sub>t</sub>, as anatomic dead space does not change much and alveolar dead space should be negligible or very small.<sup id="cite_ref-Balmain_et_al_2022_12-0" class="reference"><a href="#cite_note-Balmain_et_al_2022-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p><p>External dead space for a given breathing apparatus is usually fixed, and this volume must be added to tidal volume to provide equivalent effective ventilation at any given level of exertion. </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=12" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Bohr_equation" title="Bohr equation">Bohr equation</a> – Equation describing the amount of physiological dead space in a person's lungs</li> <li><a href="/wiki/Christian_Bohr" title="Christian Bohr">Christian Bohr</a> – Danish physician and professor of physiology</li> <li><a href="/wiki/Multiple_inert_gas_elimination_technique" title="Multiple inert gas elimination technique">Multiple inert gas elimination technique</a> – Medical technique</li> <li><a href="/wiki/Respiratory_system" title="Respiratory system">Respiratory system</a> – Biological system in animals and plants for gas exchange</li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=13" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-WestPhysiology-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-WestPhysiology_1-0">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFWest2011" class="citation book cs1">West JB (2011). <i>Respiratory physiology : the essentials</i> (9th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-60913-640-6" title="Special:BookSources/978-1-60913-640-6"><bdi>978-1-60913-640-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Respiratory+physiology+%3A+the+essentials&rft.place=Philadelphia&rft.edition=9th&rft.pub=Wolters+Kluwer+Health%2FLippincott+Williams+%26+Wilkins&rft.date=2011&rft.isbn=978-1-60913-640-6&rft.aulast=West&rft.aufirst=John+B.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADead+space+%28physiology%29" class="Z3988"></span></span> </li> <li id="cite_note-Williams1996-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-Williams1996_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Williams1996_2-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWilliamsRankin,_NSmith,_TGaller,_D1996" class="citation journal cs1">Williams R, Rankin, N, Smith, T, Galler, D, Seakins, P (November 1996). 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"Respiratory dead space." in <i>Handbook of Physiology. Section 3: Respiration.</i> Vol 1. Wallace O. Fenn and Hermann Rahn (eds). Washington: American Physiological Society.</li> <li>John B. West. 2011. <i>Respiratory Physiology: The Essentials.</i> Lippincott Williams & Wilkins; Ninth edition. <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1609136406" title="Special:BookSources/978-1609136406">978-1609136406</a>.</li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Dead_space_(physiology)&action=edit&section=15" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="http://oac.med.jhmi.edu/res_phys/Encyclopedia/DeadSpace/DeadSpace.HTML">The <i>Dead space</i> page on Johns Hopkins School of Medicine <i>Interactive Respiratory Physiology</i> website.</a></li></ul> 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href="/wiki/Template_talk:Breathing_apparatus" title="Template talk:Breathing apparatus"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Breathing_apparatus" title="Special:EditPage/Template:Breathing apparatus"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Breathing_apparatus" style="font-size:114%;margin:0 4em"><a href="/wiki/Breathing_apparatus" title="Breathing apparatus">Breathing apparatus</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="High_altitude_breathing_apparatus" style="font-size:114%;margin:0 4em"><a href="/wiki/High_altitude_breathing_apparatus" title="High altitude breathing apparatus">High altitude breathing apparatus</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aviation_breathing_apparatus" class="mw-redirect" title="Aviation breathing apparatus">Aviation breathing apparatus</a> <ul><li><a href="/wiki/Emergency_oxygen_system" title="Emergency oxygen system">Emergency oxygen system</a></li></ul></li> <li><a href="/wiki/Mountaineering_breathing_apparatus" class="mw-redirect" title="Mountaineering breathing apparatus">Mountaineering breathing apparatus</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Occupational_breathing_apparatus" style="font-size:114%;margin:0 4em">Occupational breathing apparatus</div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td class="navbox-abovebelow" colspan="2"><div id="Respirator"><a href="/wiki/Respirator" title="Respirator">Respirator</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Regulated by <a href="/wiki/NIOSH_air_filtration_rating#Table_of_TC/BM_Approval_Schedules" title="NIOSH air filtration rating">NIOSH</a> and others</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Gas_mask" title="Gas mask">Gas mask</a> <ul><li><a href="/wiki/Gas_mask_canister" class="mw-redirect" title="Gas mask canister">Canister</a></li></ul></li> <li><a href="/wiki/Supplied-air_respirator" title="Supplied-air respirator">Supplied-air respirator</a></li> <li><a href="/wiki/Self-contained_breathing_apparatus" title="Self-contained breathing apparatus">Self-contained breathing apparatus</a> <ul><li><a href="/wiki/Self-contained_self-rescue_device" title="Self-contained self-rescue device">Self-contained self-rescue device</a></li></ul></li> <li><a href="/wiki/Mechanical_filter_(respirator)" title="Mechanical filter (respirator)">Particulate respirator</a> <ul><li><a href="/wiki/N95_respirator" title="N95 respirator">N95 respirator</a></li> <li><a href="/wiki/Dust_mask" title="Dust mask">Dust mask</a></li> <li><a href="/wiki/Powered_air-purifying_respirator" title="Powered air-purifying respirator">Powered air-purifying respirator</a></li></ul></li> <li><a href="/wiki/Chemical_cartridge" title="Chemical cartridge">Chemical cartridge</a></li> <li>Facepieces <ul><li><a href="/wiki/Smoke_hood" title="Smoke hood">Smoke hood</a></li> <li><a href="/wiki/Elastomeric_respirator" title="Elastomeric respirator">Elastomeric respirator</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Regulations</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/NIOSH_air_filtration_rating" title="NIOSH air filtration rating">42 CFR 84 (United States)</a> <ul><li><a href="/wiki/NIOSH_air_filtration_rating#Chemical_cartridge_and_canister_classifications" title="NIOSH air filtration rating">ANSI K13.1-1973</a></li></ul></li> <li><a href="/wiki/European_respirator_standards" title="European respirator standards">EN 149/14683/143 (Europe)</a></li> <li><a href="/wiki/Mechanical_filter_(respirator)#Other_standards_(KN95_and_others)" title="Mechanical filter (respirator)">GB2626 (China), and others</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Medical_breathing_apparatus" style="font-size:114%;margin:0 4em"><a href="/wiki/Medical_breathing_apparatus" class="mw-redirect" title="Medical breathing apparatus">Medical breathing apparatus</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Anaesthetic_machine" title="Anaesthetic machine">Anaesthetic machine</a></li> <li><a href="/wiki/Bubble_CPAP" title="Bubble CPAP">Bubble CPAP</a></li> <li><a href="/wiki/Continuous_positive_airway_pressure" title="Continuous positive airway pressure">Continuous positive airway pressure</a></li> <li><a href="/wiki/Resuscitator" title="Resuscitator">Resuscitator</a> <ul><li><a href="/wiki/Bag_valve_mask" title="Bag valve mask">Bag valve mask</a></li> <li><a href="/wiki/Pocket_mask" title="Pocket mask">Pocket mask</a></li></ul></li> <li><a href="/wiki/Ventilator" title="Ventilator">Ventilator</a> <ul><li><a href="/wiki/Iron_lung" title="Iron lung">Iron lung</a></li> <li><a href="/wiki/Non-invasive_ventilation" title="Non-invasive ventilation">Non-invasive ventilation</a></li></ul></li> <li><a href="/wiki/Oxygen_therapy" title="Oxygen therapy">Oxygen therapy</a> <ul><li><a href="/wiki/Hyperbaric_medicine" title="Hyperbaric medicine">Hyperbaric medicine</a> <ul><li><a href="/wiki/Built-in_breathing_system" title="Built-in breathing system">Built-in breathing system</a></li></ul></li></ul></li> <li><a href="/wiki/Positive_airway_pressure" title="Positive airway pressure">Positive airway pressure</a></li> <li><a href="/wiki/Respiratory_gas_humidification" title="Respiratory gas humidification">Respiratory gas humidification</a></li> <li><a href="/wiki/Supplemental_oxygen" class="mw-redirect" title="Supplemental oxygen">Supplemental oxygen</a> <ul><li><a href="/wiki/Nasal_cannula" title="Nasal cannula">Nasal cannula</a> <ul><li><a href="/wiki/Reservoir_cannula" class="mw-redirect" title="Reservoir cannula">Reservoir cannula</a></li></ul></li> <li><a href="/wiki/Non-rebreather_mask" title="Non-rebreather mask">Non-rebreather mask</a></li> <li><a href="/wiki/Oxygen_hood" class="mw-redirect" title="Oxygen hood">Oxygen hood</a></li> <li><a href="/wiki/Oxygen_mask" title="Oxygen mask">Oxygen mask</a></li> <li><a href="/wiki/Oxygen_tent" title="Oxygen tent">Oxygen tent</a></li> <li><a href="/wiki/Partial_rebreather_mask" class="mw-redirect" title="Partial rebreather mask">Partial rebreather mask</a></li> <li><a href="/wiki/Simple_face_mask" title="Simple face mask">Simple face mask</a></li> <li><a href="/wiki/Venturi_mask" title="Venturi mask">Venturi mask</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Underwater_breathing_apparatus" style="font-size:114%;margin:0 4em"><a href="/wiki/Underwater_breathing_apparatus" title="Underwater breathing apparatus">Underwater breathing apparatus</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Open-circuit_scuba" class="mw-redirect" title="Open-circuit scuba">Open-circuit scuba</a></li> <li><a href="/wiki/Diving_helmet" title="Diving helmet">Diving helmet</a></li> <li><a href="/wiki/Diving_rebreather" title="Diving rebreather">Diving rebreather</a></li> <li><a href="/wiki/Full-face_diving_mask" title="Full-face diving mask">Full-face diving mask</a></li> <li><a href="/wiki/Surface-supplied_diving_equipment" title="Surface-supplied diving equipment">Surface-supplied diving equipment</a></li> <li><a href="/wiki/Snorkel_(swimming)" title="Snorkel (swimming)">Snorkel</a> <ul><li><a href="/wiki/Helicopter_escape_set" class="mw-redirect" title="Helicopter escape set">Helicopter escape set</a></li> <li><a href="/wiki/Submarine_escape_set" class="mw-redirect" title="Submarine escape set">Submarine escape set</a></li></ul></li> <li><a href="/wiki/Atmospheric_diving_suit" title="Atmospheric diving suit">Atmospheric diving suit</a></li> <li><a href="/wiki/Gas_extender" class="mw-redirect" title="Gas extender">Gas extender</a></li> <li><a href="/wiki/Helium_reclaim_system" class="mw-redirect" title="Helium reclaim system">Helium reclaim system</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible mw-collapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="User_respiratory_interface" style="font-size:114%;margin:0 4em"><a href="/wiki/User_respiratory_interface" class="mw-redirect" title="User respiratory interface">User respiratory interface</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>Breathing mask <ul><li><a href="/wiki/Full_facepiece" class="mw-redirect" title="Full facepiece">Full facepiece</a></li> <li><a href="/wiki/Half_mask" class="mw-redirect" title="Half mask">Half mask</a></li> <li><a href="/wiki/Orinasal_mask" title="Orinasal mask">orinasal mask</a></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks mw-collapsible uncollapsed navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="General" style="font-size:114%;margin:0 4em">General</div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Breathing_gas" title="Breathing gas">Breathing gas</a></li> <li><a href="/wiki/Breathing_performance_of_regulators" title="Breathing performance of regulators">Breathing performance of regulators</a></li> <li><a class="mw-selflink selflink">Dead space</a></li> <li><a href="/wiki/Emergency_gas_supply" class="mw-redirect" title="Emergency gas supply">Emergency gas supply</a></li> <li><a href="/wiki/Escape_breathing_apparatus" title="Escape breathing apparatus">Escape breathing apparatus</a></li> <li><a href="/wiki/Facepiece" class="mw-redirect" title="Facepiece">Facepiece</a></li> <li><a href="/wiki/Hazmat_suit" title="Hazmat suit">Hazmat suit</a></li> <li><a href="/wiki/Negative_pressure_breathing" class="mw-redirect" title="Negative pressure breathing">Negative pressure breathing</a></li> <li><a href="/wiki/Open_circuit_breathing_apparatus" class="mw-redirect" title="Open circuit breathing apparatus">Open circuit breathing apparatus</a></li> <li><a href="/wiki/Oxygen_concentrator" title="Oxygen concentrator">Oxygen concentrator</a></li> <li><a href="/wiki/Positive_pressure_breathing" class="mw-redirect" title="Positive pressure breathing">Positive pressure breathing</a></li> <li><a href="/wiki/Respiratory_protective_equipment" title="Respiratory protective equipment">Respiratory protective equipment</a></li> <li><a href="/wiki/Pressure_regulator" title="Pressure regulator">Pressure regulator</a> <ul><li><a href="/wiki/Constant_flow_regulator" class="mw-redirect" title="Constant flow regulator">Constant flow regulator</a></li> <li><a href="/wiki/Demand_valve" class="mw-redirect" title="Demand valve">Demand valve</a></li></ul></li> <li><a href="/wiki/Rebreather" title="Rebreather">Rebreather</a> <ul><li><a href="/wiki/Closed_circuit_rebreather" class="mw-redirect" title="Closed circuit rebreather">Closed circuit rebreather</a></li> <li><a href="/wiki/Counterlung" class="mw-redirect" title="Counterlung">Counterlung</a></li> <li><a href="/wiki/Oxygen_rebreather" class="mw-redirect" title="Oxygen rebreather">Oxygen rebreather</a></li> <li><a href="/wiki/Carbon_dioxide_scrubber" title="Carbon dioxide scrubber">Carbon dioxide scrubber</a></li> <li><a href="/wiki/Semi-closed_circuit" class="mw-redirect" title="Semi-closed circuit">Semi-closed circuit</a></li></ul></li> <li><a href="/wiki/Work_of_breathing" title="Work of breathing">Work of breathing</a></li> <li><a href="/wiki/Escape_respirator" class="mw-redirect" title="Escape respirator">Escape respirator</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="font-weight: bold;"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <b><a href="/wiki/Category:Breathing_apparatus" title="Category:Breathing apparatus">Category</a></b></li> <li><span class="noviewer" typeof="mw:File"><span title="Commons page"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span> <b><a href="https://commons.wikimedia.org/wiki/Category:Breathing_apparatus" class="extiw" title="commons:Category:Breathing apparatus">Commons</a></b></li> <li><span class="noviewer" typeof="mw:File"><span title="List-Class article"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/16px-Symbol_list_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/23px-Symbol_list_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/31px-Symbol_list_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <b><a href="/wiki/Glossary_of_breathing_apparatus_terminology" title="Glossary of breathing apparatus terminology">Glossary</a></b></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Respiratory_physiology" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Respiratory_physiology" title="Template:Respiratory physiology"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Respiratory_physiology" title="Template talk:Respiratory physiology"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Respiratory_physiology" title="Special:EditPage/Template:Respiratory physiology"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Respiratory_physiology" style="font-size:114%;margin:0 4em"><a href="/wiki/Respiratory_physiology" class="mw-redirect" title="Respiratory physiology">Respiratory physiology</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Respiration</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Breath" class="mw-redirect" title="Breath">breath</a> <ul><li><a href="/wiki/Inhalation" title="Inhalation">inhalation</a></li> <li><a href="/wiki/Exhalation" title="Exhalation">exhalation</a></li> <li><a href="/wiki/Obligate_nasal_breathing" title="Obligate nasal breathing">obligate nasal breathing</a></li></ul></li> <li><a href="/wiki/Respiratory_rate" title="Respiratory rate">respiratory rate</a></li> <li><a href="/wiki/Respirometer" title="Respirometer">respirometer</a></li> <li><a href="/wiki/Pulmonary_surfactant" title="Pulmonary surfactant">pulmonary surfactant</a></li> <li><a href="/wiki/Pulmonary_compliance" class="mw-redirect" title="Pulmonary compliance">compliance</a></li> <li><a href="/wiki/Elastic_recoil" title="Elastic recoil">elastic recoil</a></li> <li><a href="/wiki/Hysteresivity" title="Hysteresivity">hysteresivity</a></li> <li><a href="/wiki/Airway_resistance" title="Airway resistance">airway resistance</a></li> <li>bronchial <ul><li><a href="/wiki/Bronchial_hyperresponsiveness" title="Bronchial hyperresponsiveness">hyperresponsiveness</a></li> <li><a href="/wiki/Bronchoconstriction" title="Bronchoconstriction">constriction</a></li> <li><a href="/wiki/Bronchodilatation" title="Bronchodilatation">dilatation</a></li></ul></li> <li><a href="/wiki/Mechanical_ventilation" title="Mechanical ventilation">mechanical ventilation</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Control_of_ventilation" title="Control of ventilation">Control</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><i><a href="/wiki/Pons" title="Pons">pons</a></i> <ul><li><a href="/wiki/Pneumotaxic_center" class="mw-redirect" title="Pneumotaxic center">pneumotaxic center</a></li> <li><a href="/wiki/Apneustic_center" class="mw-redirect" title="Apneustic center">apneustic center</a></li></ul></li> <li><i><a href="/wiki/Medulla_oblongata" title="Medulla oblongata">medulla</a></i> <ul><li><a href="/wiki/Dorsal_respiratory_group" class="mw-redirect" title="Dorsal respiratory group">dorsal respiratory group</a></li> <li><a href="/wiki/Ventral_respiratory_group" class="mw-redirect" title="Ventral respiratory group">ventral respiratory group</a></li></ul></li> <li><i><a href="/wiki/Chemoreceptor" title="Chemoreceptor">chemoreceptors</a></i> <ul><li><a href="/wiki/Central_chemoreceptors" title="Central chemoreceptors">central</a></li> <li><a href="/wiki/Peripheral_chemoreceptors" title="Peripheral chemoreceptors">peripheral</a></li></ul></li> <li><a href="/wiki/Pulmonary_stretch_receptors" title="Pulmonary stretch receptors">pulmonary stretch receptors</a> <ul><li><a href="/wiki/Hering%E2%80%93Breuer_reflex" title="Hering–Breuer reflex">Hering–Breuer reflex</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Lung_volumes" title="Lung volumes">Lung volumes</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Vital_capacity" title="Vital capacity">VC</a></li> <li><a href="/wiki/Functional_residual_capacity" title="Functional residual capacity">FRC</a></li> <li><a href="/wiki/Tidal_volume" title="Tidal volume">Vt</a></li> <li><a class="mw-selflink selflink">dead space</a></li> <li><a href="/wiki/Closing_capacity" title="Closing capacity">CC</a></li> <li><a href="/wiki/Peak_expiratory_flow" title="Peak expiratory flow">PEF</a></li></ul> <dl><dt>calculations</dt> <dd></dd> <dd><a href="/wiki/Respiratory_minute_volume" class="mw-redirect" title="Respiratory minute volume">respiratory minute volume</a></dd> <dd><a href="/wiki/FEV1/FVC_ratio" title="FEV1/FVC ratio">FEV1/FVC ratio</a></dd></dl> <dl><dt><a href="/wiki/Lung_function_test" class="mw-redirect" title="Lung function test">Lung function tests</a></dt> <dd></dd> <dd><a href="/wiki/Spirometry" title="Spirometry">spirometry</a></dd> <dd><a href="/wiki/Body_plethysmography" class="mw-redirect" title="Body plethysmography">body plethysmography</a></dd> <dd><a href="/wiki/Peak_flow_meter" class="mw-redirect" title="Peak flow meter">peak flow meter</a></dd> <dd><a href="/wiki/Nitrogen_washout" title="Nitrogen washout">nitrogen washout</a></dd></dl> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Circulation</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Pulmonary_circulation" title="Pulmonary circulation">pulmonary circulation</a></li> <li><a href="/wiki/Hypoxic_pulmonary_vasoconstriction" title="Hypoxic pulmonary vasoconstriction">hypoxic pulmonary vasoconstriction</a></li> <li><a href="/wiki/Pulmonary_shunt" title="Pulmonary shunt">pulmonary shunt</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Interactions</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ventilation_(physiology)" class="mw-redirect" title="Ventilation (physiology)">ventilation (V)</a></li> <li><a href="/wiki/Perfusion" title="Perfusion">Perfusion</a> (Q) <ul><li><a href="/wiki/Ventilation/perfusion_ratio" title="Ventilation/perfusion ratio">Ventilation/perfusion ratio</a></li> <li><a href="/wiki/Ventilation/perfusion_scan" title="Ventilation/perfusion scan">V/Q scan</a></li></ul></li> <li><a href="/wiki/Zones_of_the_lung" title="Zones of the lung">zones of the lung</a></li> <li><a href="/wiki/Gas_exchange" title="Gas exchange">gas exchange</a></li> <li><a href="/wiki/Pulmonary_gas_pressures" title="Pulmonary gas pressures">pulmonary gas pressures</a></li> <li><a href="/wiki/Alveolar_gas_equation" title="Alveolar gas equation">alveolar gas equation</a></li> <li><a href="/wiki/Alveolar%E2%80%93arterial_gradient" title="Alveolar–arterial gradient">alveolar–arterial gradient</a></li> <li><a href="/wiki/Hemoglobin" title="Hemoglobin">hemoglobin</a></li> <li><a href="/wiki/Oxygen%E2%80%93hemoglobin_dissociation_curve" title="Oxygen–hemoglobin dissociation curve">oxygen–hemoglobin dissociation curve</a> (<a href="/wiki/Oxygen_saturation" title="Oxygen saturation">Oxygen saturation</a></li> <li><a href="/wiki/2,3-Bisphosphoglyceric_acid" title="2,3-Bisphosphoglyceric acid">2,3-BPG</a></li> <li><a href="/wiki/Bohr_effect" title="Bohr effect">Bohr effect</a></li> <li><a href="/wiki/Haldane_effect" title="Haldane effect">Haldane effect</a>)</li> <li><a href="/wiki/Carbonic_anhydrase" title="Carbonic anhydrase">carbonic anhydrase</a> (<a href="/wiki/Chloride_shift" title="Chloride shift">chloride shift</a>)</li> <li><a href="/wiki/Oxyhemoglobin" class="mw-redirect" title="Oxyhemoglobin">oxyhemoglobin</a></li> <li><a href="/wiki/Respiratory_quotient" title="Respiratory quotient">respiratory quotient</a></li> <li><a href="/wiki/Arterial_blood_gas" class="mw-redirect" title="Arterial blood gas">arterial blood gas</a></li> <li><a href="/wiki/Diffusion_capacity" class="mw-redirect" title="Diffusion capacity">diffusion capacity</a> (<a href="/wiki/DLCO" class="mw-redirect" title="DLCO">DLCO</a>)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Insufficiency</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Effects_of_high_altitude_on_humans" title="Effects of high altitude on humans">high altitude</a> <ul><li><a href="/wiki/Death_zone" title="Death zone">death zone</a></li></ul></li> <li><a href="/wiki/Oxygen_toxicity" title="Oxygen toxicity">oxygen toxicity</a></li> <li><a href="/wiki/Hypoxia_(medical)" class="mw-redirect" title="Hypoxia (medical)">hypoxia</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" 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