Acute Crit Care.  2023 May;38(2):190-199. 10.4266/acc.2022.01438.

Prognostic significance of respiratory quotient in patients undergoing extracorporeal cardiopulmonary resuscitation in Korea

• Lee YI
• Ko RE
• Na SJ
• Ryu JA
• Cho YH
• Yang JH
• Chung CR
• Suh GY

• KMID: 2543638
• DOI: http://doi.org/10.4266/acc.2022.01438

Abstract

Background
Respiratory quotient (RQ) may be used as a tissue hypoxia marker in various clinical settings but its prognostic significance in patients undergoing extracorporeal cardiopulmonary resuscitation (ECPR) is not known. Methods: Medical records of adult patients admitted to the intensive care units after ECPR in whom RQ could be calculated from May 2004 to April 2020 were retrospectively reviewed. Patients were divided into good neurologic outcome and poor neurologic outcome groups. Prognostic significance of RQ was compared to other clinical characteristics and markers of tissue hypoxia. Results: During the study period, 155 patients were eligible for analysis. Of them, 90 (58.1%) had a poor neurologic outcome. The group with poor neurologic outcome had a higher incidence of out-of-hospital cardiac arrest (25.6% vs. 9.2%, P=0.010) and longer cardiopulmonary resuscitation to pump-on time (33.0 vs. 25.2 minutes, P=0.001) than the group with good neurologic outcome. For tissue hypoxia markers, the group with poor neurologic outcome had higher RQ (2.2 vs. 1.7, P=0.021) and lactate levels (8.2 vs. 5.4 mmol/L, P=0.004) than the group with good neurologic outcome. On multivariable analysis, age, cardiopulmonary resuscitation to pump-on time, and lactate levels above 7.1 mmol/L were significant predictors for a poor neurologic outcome but not RQ. Conclusions: In patients who received ECPR, RQ was not independently associated with poor neurologic outcome.

Keyword

extracorporeal cardiopulmonary resuscitation; extracorporeal membrane oxygenation; lactic acid; respiratory quotient

Figure

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  Figure 1. Study flow diagram. ECPR: extracorporeal cardiopulmonary resuscitation; ECMO: extracorporeal membrane oxygenation; RQ: respiratory quotient.

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  Figure 2. The distribution of patients according to the respiratory quotient. The number of patients according to the respiratory quotient (RQ).

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  Figure 3. Receiver operating characteristics curves of hypoxia parameters. Values are presented as median (interquartile range). RQ: respiratory quotient; ΔpCO2: venous-arterial difference in CO2 tension.

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