EBQ:End-Tidal CO2 PaCO2 correlation - Revision history

Danbot: Added all standard JC sections

2026-03-21T22:51:13Z

Added all standard JC sections

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	*EtCO2 may be more a reflection of perfusion rather than ventilation status. <ref name="warner"></ref>		*EtCO2 may be more a reflection of perfusion rather than ventilation status. <ref name="warner"></ref>

			==Conclusion==
			*End-tidal CO2 (ETCO2) generally correlates with PaCO2, but the gradient is variable and increases with dead space ventilation
			*In healthy patients, ETCO2 typically underestimates PaCO2 by 2-5 mmHg
			*The ETCO2-PaCO2 gradient is unreliable in critically ill patients, particularly those with V/Q mismatch, pulmonary embolism, or shock

			==Major Points==
			*ETCO2 monitoring is a useful noninvasive tool for trending CO2 levels in intubated patients
			*Normal ETCO2 values (35-45 mmHg) do not guarantee normal PaCO2 in patients with significant dead space
			*The correlation worsens in patients with COPD, PE, severe hypotension, and other causes of V/Q mismatch
			*Serial ETCO2 trending is more useful than single measurements for clinical decision-making
			*ABG remains the gold standard for accurate PaCO2 measurement in critically ill patients

			==Study Design==
			*Evidence review and analysis of studies examining the ETCO2-PaCO2 correlation
			*Multiple studies reviewed across ED, ICU, and anesthesia settings

			==Population==
			*Intubated patients in various clinical settings (operating room, ICU, ED)
			*Includes both hemodynamically stable and critically ill patients

			==Interventions==
			*Simultaneous ETCO2 and arterial blood gas measurement comparison
			*No therapeutic intervention; diagnostic accuracy assessment

			==Outcomes==
			*In hemodynamically stable patients: ETCO2-PaCO2 gradient typically 2-5 mmHg
			*In critically ill patients: gradient is unpredictable and can exceed 10-20 mmHg
			*Correlation coefficient (r) ranges from 0.7-0.9 depending on patient population
			*ETCO2 trending reliably reflects directional changes in PaCO2

			==Criticisms==
			*Most studies are small and conducted in controlled settings (operating room)
			*The ETCO2-PaCO2 gradient varies significantly based on pathophysiology, limiting universal application
			*Studies rarely include the sickest ED patients where the correlation is most likely to fail
			*Technical factors (sampling line issues, circuit leaks) can independently affect ETCO2 accuracy

			==Funding==
			*Variable across reviewed studies

	==Sources==		==Sources==

Ostermayer: Text replacement - "Category:Pulm" to "Category:Pulmonary"

2016-03-22T16:12:14Z

Text replacement - "Category:Pulm" to "Category:Pulmonary"

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	<references/>		<references/>

	[[Category:EBQ]][[Category:Critical Care]][[Category:~~Pulm~~]][[Category:Trauma]][[Category:Neurology]]		[[Category:EBQ]][[Category:Critical Care]][[Category:Pulmonary]][[Category:Trauma]][[Category:Neurology]]

Ostermayer: Text replacement - "Category:Neuro" to "Category:Neurology"

2016-03-22T14:14:04Z

Text replacement - "Category:Neuro" to "Category:Neurology"

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	<references/>		<references/>

	[[Category:EBQ]][[Category:Critical Care]][[Category:Pulm]][[Category:Trauma]][[Category:~~Neuro~~]]		[[Category:EBQ]][[Category:Critical Care]][[Category:Pulm]][[Category:Trauma]][[Category:Neurology]]

Ostermayer: /* Lee 2009 Journal of TraumaLee S-W, Hong Y-S, Han C, et al. Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain injury. J Trauma. 2009;67(3):526–530. doi:10.1097/TA.0b013e3181866432. */

2014-05-31T17:43:34Z

Lee 2009 Journal of TraumaLee S-W, Hong Y-S, Han C, et al. Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain injury. J Trauma. 2009;67(3):526–530. doi:10.1097/TA.0b013e3181866432.

← Older revision		Revision as of 17:43, 31 May 2014
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	*Included 66 adults at single center with GCS <9 after any traumatic injury in the Emergency Dept		*Included 66 adults at single center with GCS <9 after any traumatic injury in the Emergency Dept
	*Patients were mechanically ventilated with etCO<sub>2</sub> and PaCO<sub>2</sub> obtained simultaneously		*Patients were mechanically ventilated with etCO<sub>2</sub> and PaCO<sub>2</sub> obtained simultaneously
	*Median difference of PaCO<sub>2</sub> etCO<sub>2</sub> was 3.6 mm Hg with 77.3% concordance		*Median difference of PaCO<sub>2</sub> and etCO<sub>2</sub> was 3.6 mm Hg with 77.3% concordance
	*Differences of greater than 5mm occurred in patents with hypotension, acedemic and lactate > 7 mm/L		*Differences of greater than 5mm occurred in patents with hypotension, acedemic and lactate > 7 mm/L

Ostermayer: /* Con Argument */

2014-05-21T18:13:14Z

Con Argument

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	*'''etCO2 will differ the most from PaCO2 in patients with multi system trauma especially those with chest wall and abdominal trauma'''		*'''etCO2 will differ the most from PaCO2 in patients with multi system trauma especially those with chest wall and abdominal trauma'''

	*EtCO2 may be a reflection of perfusion rather than ventilation status. <ref name="warner"></ref>		*EtCO2 may be more a reflection of perfusion rather than ventilation status. <ref name="warner"></ref>


	==Sources==		==Sources==

Ostermayer: /* Pro Argument */

2014-05-21T18:12:41Z

Pro Argument

Ostermayer: /* Clinical Question */

2014-05-21T18:11:25Z

Clinical Question

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	==Clinical Question==		==Clinical Question==
	'''Can end tidal CO2(etCO<sub>2</sub> be used as a surrogate for PaCO<sub>2</sub> in critically Ill Patients?'''		'''Can end tidal CO2(etCO<sub>2</sub>) be used as a surrogate for PaCO<sub>2</sub> in critically Ill Patients?'''

	==Pro Argument==		==Pro Argument==

Ostermayer: /* Clinical Question */

2014-05-21T18:11:14Z

Clinical Question

← Older revision		Revision as of 18:11, 21 May 2014
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	==Clinical Question==		==Clinical Question==
	'''Can end tidal CO2 be used as a surrogate for ~~PaCO2~~ in critically Ill Patients?'''		'''Can end tidal CO2(etCO<sub>2</sub> be used as a surrogate for PaCO<sub>2</sub> in critically Ill Patients?'''

	==Pro Argument==		==Pro Argument==
	*'''The greatest correlation of etCO2 to PaCO2 is in hemodynamically stable patients and isolated TBI'''		*'''The greatest correlation of etCO2 to PaCO2 is in hemodynamically stable patients and isolated TBI'''

Ostermayer: /* Pro Argument */

2014-05-21T18:10:46Z

Pro Argument

← Older revision		Revision as of 18:10, 21 May 2014
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	'''Can end tidal CO2 be used as a surrogate for PaCO2 in critically Ill Patients?'''		'''Can end tidal CO2 be used as a surrogate for PaCO2 in critically Ill Patients?'''
	==Pro Argument==		==Pro Argument==
	'''The greatest correlation of etCO2 to PaCO2 is in hemodynamically stable patients and isolated TBI'''		*'''The greatest correlation of etCO2 to PaCO2 is in hemodynamically stable patients and isolated TBI'''

	Since etCO2 is dependent on both perfusion and and dead space it may underestimate the PaCO2<ref>Whitesell R, Asiddao C, Gollman D, et al. Relationship between arterial and peak expired carbon dioxide pressure during anesthesia and factors influencing the difference. Anesth Analg 1981;60:508–12</ref>		*Since etCO2 is dependent on both perfusion and and dead space it may underestimate the PaCO2<ref>Whitesell R, Asiddao C, Gollman D, et al. Relationship between arterial and peak expired carbon dioxide pressure during anesthesia and factors influencing the difference. Anesth Analg 1981;60:508–12</ref>

	===Lee 2009 Journal of Trauma<ref>Lee S-W, Hong Y-S, Han C, et al. Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain injury. J Trauma. 2009;67(3):526–530. doi:10.1097/TA.0b013e3181866432.</ref>===		===Lee 2009 Journal of Trauma<ref>Lee S-W, Hong Y-S, Han C, et al. Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain injury. J Trauma. 2009;67(3):526–530. doi:10.1097/TA.0b013e3181866432.</ref>===

Ostermayer: /* Pro Argument */

2014-05-21T18:10:29Z

Pro Argument

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	==Pro Argument==		==Pro Argument==
	'''The greatest correlation of etCO2 to PaCO2 is in hemodynamically stable patients and isolated TBI'''		'''The greatest correlation of etCO2 to PaCO2 is in hemodynamically stable patients and isolated TBI'''

	Since etCO2 is dependent on both perfusion and and dead space it may underestimate the PaCO2<ref>Whitesell R, Asiddao C, Gollman D, et al. Relationship between arterial and peak expired carbon dioxide pressure during anesthesia and factors influencing the difference. Anesth Analg 1981;60:508–12</ref>		Since etCO2 is dependent on both perfusion and and dead space it may underestimate the PaCO2<ref>Whitesell R, Asiddao C, Gollman D, et al. Relationship between arterial and peak expired carbon dioxide pressure during anesthesia and factors influencing the difference. Anesth Analg 1981;60:508–12</ref>

← Older revision		Revision as of 18:12, 21 May 2014
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	==Pro Argument==		==Pro Argument==
	*'''The greatest correlation of ~~etCO2~~ to ~~PaCO2~~ is in hemodynamically stable patients and isolated TBI'''		*'''The greatest correlation of etCO<sub>2</sub> to PaCO<sub>2</sub> is in hemodynamically stable patients and isolated TBI'''

	*Since ~~etCO2~~ is dependent on both perfusion and and dead space it may underestimate the ~~PaCO2~~<ref>Whitesell R, Asiddao C, Gollman D, et al. Relationship between arterial and peak expired carbon dioxide pressure during anesthesia and factors influencing the difference. Anesth Analg 1981;60:508–12</ref>		*Since etCO<sub>2</sub> is dependent on both perfusion and and dead space it may underestimate the PaCO<sub>2</sub><ref>Whitesell R, Asiddao C, Gollman D, et al. Relationship between arterial and peak expired carbon dioxide pressure during anesthesia and factors influencing the difference. Anesth Analg 1981;60:508–12</ref>

	===Lee 2009 Journal of Trauma<ref>Lee S-W, Hong Y-S, Han C, et al. Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain injury. J Trauma. 2009;67(3):526–530. doi:10.1097/TA.0b013e3181866432.</ref>===		===Lee 2009 Journal of Trauma<ref>Lee S-W, Hong Y-S, Han C, et al. Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain injury. J Trauma. 2009;67(3):526–530. doi:10.1097/TA.0b013e3181866432.</ref>===
	*Prospective observational study		*Prospective observational study
	*Included 66 adults at single center with GCS <9 after any traumatic injury in the Emergency Dept		*Included 66 adults at single center with GCS <9 after any traumatic injury in the Emergency Dept
	*Patients were mechanically ventilated with ~~PetCO2~~ and ~~PaCO2~~ obtained simultaneously		*Patients were mechanically ventilated with etCO<sub>2</sub> and PaCO<sub>2</sub> obtained simultaneously
	*Median difference of ~~PaCO2 etCO2~~ was 3.6 mm Hg with 77.3% concordance		*Median difference of PaCO<sub>2</sub> etCO<sub>2</sub> was 3.6 mm Hg with 77.3% concordance
	*Differences of greater than 5mm occurred in patents with hypotension, acedemic and lactate > 7 mm/L		*Differences of greater than 5mm occurred in patents with hypotension, acedemic and lactate > 7 mm/L

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	*Prospective observational study		*Prospective observational study
	*Included adult patients with TBI regardless of other injuries, however, critical patients were excluded if they required immediate OR intervention		*Included adult patients with TBI regardless of other injuries, however, critical patients were excluded if they required immediate OR intervention
	*Concurrent ~~PaCO2~~ measurement with ~~etCO2~~ of patients who remained in the ED.		*Concurrent PaCO<sub>2</sub> measurement with etCO<sub>2</sub> of patients who remained in the ED.
	*Not all had repeat ~~PaCO2~~ measurements to correlated trends of convergence or divergence		*Not all had repeat PaCO<sub>2</sub> measurements to correlated trends of convergence or divergence
	*Correlation of R=.27 between ~~PaCO2~~		*Correlation of R=.27 between PaCO<sub>2</sub>
	*Only 53% of TBI patients had a difference of < 5mm Hg between ~~PaCO2~~ and ~~etCO2~~		*Only 53% of TBI patients had a difference of < 5mm Hg between PaCO<sub>2</sub> and etCO<sub>2</sub>
	*Only 36% in severe abdominal trauma and 29% in severe chest trauma had an acceptable difference of <5 mm Hg.		*Only 36% in severe abdominal trauma and 29% in severe chest trauma had an acceptable difference of <5 mm Hg.

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	*Prospective semi-blind ED study of 73 adultpatients with respiratory distress		*Prospective semi-blind ED study of 73 adultpatients with respiratory distress
	*Non trauma patients		*Non trauma patients
	*Correlation coefficient of 0.792 with ~~etCO2~~ and ~~PaCO2~~ with young patients having less correlation		*Correlation coefficient of 0.792 with etCO<sub>2</sub> and PaCO<sub>2</sub> with young patients having less correlation

	;Conclusion: An acceptable correlation exists in non trauma patients with respiratory distress		;Conclusion: An acceptable correlation exists in non trauma patients with respiratory distress