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

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

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,...

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Bibliographic Details
Main Authors: McKenzie, Nicole, Finn, Judith, Dobb, G., Bailey, P., Arendts, G., Celenza, A., Fatovich, D., Jenkins, I., Ball, Stephen, Bray, Janet, Ho, K.M.
Format: Journal Article
Language:English
Published: ELSEVIER IRELAND LTD 2021
Subjects:
Science & Technology
Life Sciences & Biomedicine
Critical Care Medicine
Emergency Medicine
General & Internal Medicine
Arterial carbon dioxide tension
Out-of-hospital cardiac arrest
Post-resuscitation care
Survival
Neurological outcome
INTENSIVE-CARE-UNIT
BLOOD GAS TENSIONS
BRAIN-INJURY
RESUSCITATION
GUIDELINES
MORTALITY
OXYGEN
TRIAL
Adult
Carbon Dioxide
Cohort Studies
Humans
Hypercapnia
Out-of-Hospital Cardiac Arrest
Retrospective Studies
Online Access:http://purl.org/au-research/grants/nhmrc/1029983
http://hdl.handle.net/20.500.11937/93463
Description
Summary: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.

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