Mean airway pressure

There are several equations aimed at determining the real mean airway pressure.

In ventilation with a square flow waveform this equation can be used:

$\backslash bar\{P\}\_\{aw\}=0.5\backslash times(PIP\; -\; PEEP)\; \backslash times\; (T\_I/T\_\{tot\})+PEEP$

where:

• $\backslash bar\{P\}\_\{aw\}$ = mean airway pressure
• $PIP$= peak inspiratory pressure
• $PEEP$= peak end expiratory pressure
• $T\_I$= inspiratory time
• $T\_\{tot\}$= cycle time

During pressure control ventilation this variant of the equation can be used:

$\backslash bar\{P\}\_\{aw\}=\; (PIP\; -\; PEEP)\; \backslash times\; (T\_I/T\_\{tot\})+PEEP$

where:

• $\backslash bar\{P\}\_\{aw\}$ = mean airway pressure
• $PIP$= peak inspiratory pressure
• $PEEP$= peak end expiratory pressure
• $T\_I$= inspiratory time
• $T\_\{tot\}$= cycle time

File:Airway pressure release ventilation figure 2007.jpg

In airway pressure release ventilation (APRV) a variation of the previous equation must be used for the variables:

:$\backslash bar\{P\}\_\{aw\}\; =\; \backslash frac\{(P\_\{high\}\; \backslash times\; T\_\{high\})\backslash ,\; +\; (P\_\{low\}\; \backslash times\; T\_\{low\})\}\; \{T\_\{high\}\; +\; T\_\{low\}\}$

:where:

:* $\backslash bar\{P\}\_\{aw\}$= mean airway pressure

:* $\{P\}\_\{high\}$= peak inspiratory pressure (PIP)

:* $\{P\}\_\{low\}$= peak end expiratory pressure

:* $\{T\}\_\{high\}$= time spent at $\{P\}\_\{high\}$

:* $\{T\}\_\{low\}$= time spent at $\{P\}\_\{low\}${{Cite journal |last=Daoud |first=Ehab G. |date=2007 |title=Airway pressure release ventilation |journal=Annals of Thoracic Medicine |volume=2 |issue=4 |pages=176–179 |doi=10.4103/1817-1737.36556 |issn=1817-1737 |pmc=2732103 |pmid=19727373 |doi-access=free }}

:$M\_\{PAW\}\; =\; \backslash frac\{f\; \backslash times\; T\_i\}\{60\}\; \backslash times\; (P\_\{IP\}\; -\; PEEP)\; +\; PEEP$

:$M\_\{PAW\}\; =\; \backslash frac\{F\_1\}\{F\_1+F\_E\}\; \backslash times\; P\_\{IP\}\; +\; \backslash left(1\; -\; \backslash frac\{F\_1\}\{F\_1+F\_E\}\backslash right)\; \backslash times\; PEEP$

:$M\_\{PAW\}\; =\; \backslash frac\{(R)(T\_i)(P\_I)+[60-(R)(T\_i)](PEEP)\}\{60\}$

:$M\_\{PAW\}\; =\; \backslash frac\{f\; \backslash times\; T\_i\}\{60\}\; \backslash times\; (P\_\{IP\}\; -\; PEEP)\; +\; PEEP${{cite book|author=David W. Chang|title=Respiratory care calculations|url=https://books.google.com/books?id=uzjh0nOWtRYC&pg=PA251|access-date=30 March 2012|year=1999|publisher=Cengage Learning|isbn=978-0-7668-0517-0|pages=251–}}

:$M\_\{PAW\}\; =\; \backslash frac\{(T\_i\; \backslash times\; P\_\{IP\})\; +\; (T\_e\; \backslash times\; PEEP)\}\{T\_i+T\_e\}$

Mean airway pressure has been shown to have a similar correlation as plateau pressure to mortality.{{Cite journal |last1=Sahetya |first1=Sarina |last2=Wu |first2=David |last3=Brooks |first3=Morgan |date=May 2020 |title=Mean Airway Pressure As a Predictor of 90-Day Mortality in Mechanically Ventilated Patients |journal=Critical Care Medicine |volume=48 |issue=5 |pages=688–695 |doi=10.1097/CCM.0000000000004268|pmid=32079893 |pmc=8273919 }}

MAP is closely associated with mean alveolar pressure and shows the stresses exerted on the lung parenchyma on mechanical ventilation.{{Cite journal |last1=Su |first1=Longxiang |last2=Pan |first2=Pan |last3=Liu |first3=Dawei |last4=Long |first4=Yun |date=2021-10-01 |title=Mean airway pressure has the potential to become the core pressure indicator of mechanical ventilation: Raising to the front from behind the clinical scenes |journal=Journal of Intensive Medicine |language=en |volume=1 |issue=2 |pages=96–98 |doi=10.1016/j.jointm.2021.04.002 |pmid=36788801 |pmc=9923962 |s2cid=236575021 |issn=2667-100X|doi-access=free }}

In high frequency oscillatory ventilation, it has been suggested to set the mean airway pressure six above the lower inflection point on the lungs P-V curve.{{Cite journal |last1=Goddon |first1=Sven |last2=Fujino |first2=Yuji |last3=Hromi |first3=Jonathan M. |last4=Kacmarek |first4=Robert M. |date=May 2001 |title=Optimal Mean Airway Pressure during High-frequency Oscillation: Predicted by the Pressure–Volume Curve |journal=Anesthesiology |volume=94 |issue=5 |pages=862–869 |doi=10.1097/00000542-200105000-00026 |pmid=11388539 |s2cid=9604584 |issn=0003-3022|doi-access=free }}

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• Mechanical ventilation
• Modes of ventilation
• Mean systemic pressure

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