Arterial carbon dioxide tension has a non-linear association with survival after out-of-hospital cardiac arrest: A multicentre observational study

Nicole Mckenzie; Judith Finn; Geoffrey Dobb; Paul Bailey; Glenn Arendts; Antonio Celenza; Daniel Fatovich; Ian Jenkins; Stephen Ball; Janet Bray; Kwok M Ho

doi:10.1016/j.resuscitation.2021.01.035

Arterial carbon dioxide tension has a non-linear association with survival after out-of-hospital cardiac arrest: A multicentre observational study

Resuscitation. 2021 May:162:82-90. doi: 10.1016/j.resuscitation.2021.01.035. Epub 2021 Feb 8.

Authors

Nicole Mckenzie¹, Judith Finn², Geoffrey Dobb³, Paul Bailey⁴, Glenn Arendts⁵, Antonio Celenza⁶, Daniel Fatovich⁷, Ian Jenkins⁸, Stephen Ball⁴, Janet Bray⁹, Kwok M Ho¹⁰

Affiliations

¹ Prehospital, Resuscitation and Emergency Care Research Unit (PRECRU), Curtin University, Bentley, WA, Australia; Intensive Care Unit, Royal Perth Hospital, Perth, WA, Australia. Electronic address: nicole.mckenzie@curtin.edu.au.
² Prehospital, Resuscitation and Emergency Care Research Unit (PRECRU), Curtin University, Bentley, WA, Australia; St John Western Australia, Belmont, WA, Australia; Medical School, University of Western Australia, Crawley, WA, Australia; School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia.
³ Intensive Care Unit, Royal Perth Hospital, Perth, WA, Australia; Medical School, University of Western Australia, Crawley, WA, Australia.
⁴ Prehospital, Resuscitation and Emergency Care Research Unit (PRECRU), Curtin University, Bentley, WA, Australia; St John Western Australia, Belmont, WA, Australia.
⁵ Medical School, University of Western Australia, Crawley, WA, Australia; Fiona Stanley Hospital, Murdoch, WA, Australia.
⁶ Medical School, University of Western Australia, Crawley, WA, Australia; Sir Charles Gairdner Hospital, Nedlands, WA, Australia.
⁷ Prehospital, Resuscitation and Emergency Care Research Unit (PRECRU), Curtin University, Bentley, WA, Australia; Medical School, University of Western Australia, Crawley, WA, Australia; Emergency Medicine, Royal Perth Hospital, Perth, WA, Australia.
⁸ Fremantle Hospital, Fremantle, WA, Australia.
⁹ School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia.
¹⁰ Prehospital, Resuscitation and Emergency Care Research Unit (PRECRU), Curtin University, Bentley, WA, Australia; Intensive Care Unit, Royal Perth Hospital, Perth, WA, Australia; Medical School, University of Western Australia, Crawley, WA, Australia; School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia.

PMID: 33571603
DOI: 10.1016/j.resuscitation.2021.01.035

Abstract

Purpose: International guidelines recommend targeting normocapnia in mechanically ventilated out-of-hospital cardiac arrest (OHCA) survivors, but the optimal arterial carbon dioxide (PaCO₂) target remains controversial. We hypothesised that the relationship between PaCO₂ and survival is non-linear, and targeting an intermediate level of PaCO₂ compared to a low or high PaCO₂ in the first 24-h of ICU admission is associated with an improved survival to hospital discharge (STHD) and at 12-months.

Methods: We conducted a retrospective multi-centre cohort study of adults with non-traumatic OHCA requiring admission to one of four tertiary hospital intensive care units for mechanical ventilation. A four-knot restricted cubic spline function was used to allow non-linearity between the mean PaCO₂ within the first 24 h of ICU admission after OHCA and survival, and optimal PaCO₂ cut-points were identified from the spline curve to generate corresponding odds ratios.

Results: We analysed 3769 PaCO₂ results within the first 24-h of ICU admission, from 493 patients. PaCO₂ and survival had an inverted U-shape association; normocapnia was associated with significantly improved STHD compared to either hypocapnia (<35 mmHg) (adjusted odds ratio [aOR] 0.45, 95% confidence interval [CI] 0.24-0.83) or hypercapnia (>45 mmHg) (aOR 0.45, 95% CI 0.24-0.84). Of the twelve predictors assessed, PaCO₂ was the third most important predictor, and explained >11% of the variability in survival. The survival benefits of normocapnia extended to 12-months.

Conclusions: Normocapnia within the first 24-h of intensive care admission after OHCA was associated with an improved survival compared to patients with hypocapnia or hypercapnia.

Keywords: Arterial carbon dioxide tension; Neurological outcome; Out-of-hospital cardiac arrest; Post-resuscitation care; Survival.

Publication types

Multicenter Study
Observational Study
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Carbon Dioxide*
Cohort Studies
Humans
Hypercapnia
Out-of-Hospital Cardiac Arrest* / therapy
Retrospective Studies

Substances

Carbon Dioxide