Lack of correlation between central venous minus arterial PCO2 to arterial minus central venous O2 content ratio and respiratory quotient in patients with septic shock: A prospective observational study

IF 2.7 4区医学 Q2 CRITICAL CARE MEDICINE

Medicina Intensiva Pub Date : 2025-01-01 DOI:10.1016/j.medin.2024.05.016

Facundo J. Gutierrez , Mario O. Pozo , Matías Mugno , Sebastián P. Chapela , Natalia Llobera , María J. Reberendo , Gastón E. Murias , Paolo N. Rubatto Birri , Vanina S. Kanoore Edul , Arnaldo Dubin

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引用次数: 0

Abstract

Objective

Central venous-arterial PCO₂ to arterial-central venous O₂ content ratio (P_cv-aCO₂/C_a-cvO₂) is commonly used as a surrogate for respiratory quotient (RQ) and tissue oxygenation. Although P_cv-aCO₂/C_a-cvO₂ might be associated with hyperlactatemia and outcome, neither the interchangeability with RQ nor the correlation with conclusive variables of anaerobic metabolism has never been demonstrated in septic shock. Our goal was to compare P_cv-aCO₂/C_a-cvO₂ and RQ in patients with septic shock.

Design

Prospective, observational study.

Setting

Two adult ICUs.

Patients

Forty-seven patients with septic shock on mechanical ventilation with stable respiratory settings and vasopressor dose after initial resuscitation.

Interventions

None.

Main variables of interest

We measured arterial and central venous gases, Hb, and O₂Hb. P_cv-aCO₂/C_a-cvO₂ and the ratio of central venous-arterial CO₂ content to arterial-central venous O₂ content (C_cv-aCO₂/C_a-cvO₂) were calculated. RQ was determined by indirect calorimetry.

Results

P_cv-aCO₂/C_a-cvO₂ and C_cv-aCO₂/C_a-cvO₂ were not correlated with RQ (R² = 0.01, P = 0.50 and R² = 0.01, P = 0.58, respectively), showing large bias and wide 95 % limits of agreement with RQ (1.09, -1.10−3.27 and 0.42, -1.53−2.37). A multiple linear regression model showed Hb, and central venous PCO₂ and O₂Hb, but not RQ, as P_cv-aCO₂/C_a-cvO₂ determinants (R² = 0.36, P = 0.0007).

Conclusions

In patients with septic shock, P_cv-aCO₂/C_a-cvO₂ did not correlate with RQ and was mainly determined by factors that modify the dissociation of CO₂ from Hb. P_cv-aCO₂/C_a-cvO₂ seems to be a poor surrogate for RQ; therefore, its values should be interpreted with caution.

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来源期刊

Medicina Intensiva CRITICAL CARE MEDICINE-

CiteScore

2.70

自引率

20.00%

发文量

146

审稿时长

33 days

期刊介绍： Medicina Intensiva is the journal of the Spanish Society of Intensive Care Medicine and Coronary Units (SEMICYUC) and of Pan American and Iberian Federation of Societies of Intensive and Critical Care Medicine. Medicina Intensiva has become the reference publication in Spanish in its field. The journal mainly publishes Original Articles, Reviews, Clinical Notes, Consensus Documents, Images, and other information relevant to the specialty. All works go through a rigorous selection process. The journal accepts submissions of articles in English and in Spanish languages. The journal follows the publication requirements of the International Committee of Medical Journal Editors (ICMJE) and the Committee on Publication Ethics (COPE).