Impact of mild hypercapnia on left ventricular global longitudinal strain in comatose adults resuscitated after out-of-hospital cardiac arrest: A single-centre, pre-planned exploratory, cohort sub-study of the mild hypercapnia versus normocapnia after out-of-hospital cardiac arrest (TAME) randomised trial

Vinodh B Nanjayya; Alistair Nichol; Lloyd Roberts; Trent Hartshorne; Matthew Hung; Judit Orosz; Li H Tan; Aidan Burrell; Josh Ihle; David Kaye; Alisa M Higgins; Glenn Eastwood; D Jamie Cooper

doi:10.1002/ajum.12419

Impact of mild hypercapnia on left ventricular global longitudinal strain in comatose adults resuscitated after out-of-hospital cardiac arrest: A single-centre, pre-planned exploratory, cohort sub-study of the mild hypercapnia versus normocapnia after out-of-hospital cardiac arrest (TAME) randomised trial

Australas J Ultrasound Med. 2025 Jun 24;28(3):e12419. doi: 10.1002/ajum.12419. eCollection 2025 Aug.

Authors

Vinodh B Nanjayya^{1

2}, Alistair Nichol^{1

2}, Lloyd Roberts^{1

2}, Trent Hartshorne^{1

2}, Matthew Hung^{1

2}, Judit Orosz^{1

2}, Li H Tan^{1

2}, Aidan Burrell^{1

2}, Josh Ihle^{1

2}, David Kaye³, Alisa M Higgins², Glenn Eastwood⁴, D Jamie Cooper^{1

2}

Affiliations

¹ Department of Intensive Care and Hyperbaric Medicine Alfred Hospital Melbourne Victoria Australia.
² Australian and New Zealand Intensive Care Research Centre Monash University Melbourne Victoria Australia.
³ Department of Cardiology Alfred Hospital Melbourne Victoria Australia.
⁴ Department of Intensive Care Austin Hospital Heidelberg Victoria Australia.

PMID: 40575075
PMCID: PMC12188021 (available on 2026-06-24)
DOI: 10.1002/ajum.12419

Abstract

Introduction: The effect of hypercapnia on cardiac function in adults resuscitated after cardiac arrest is not well understood. We investigated the effects of mild hypercapnia (PaCO₂ 50-55 mmHg) compared to normocapnia (PaCO₂ 35-45 mmHg) on left ventricular (LV) systolic function using global longitudinal strain (GLS) in resuscitated out-of-hospital cardiac arrest (OHCA) patients.

Methods: We performed a pre-planned single-centre, prospective, exploratory sub-study of the Targeted Therapeutic Mild Hypercapnia After Resuscitated Cardiac Arrest (TAME) trial. Two transthoracic echocardiograms were performed in mild hypercapnia and normocapnia groups - first, within 24 h during intervention and second, 24-72 h after return of spontaneous circulation. The GLS was compared between and within the groups.

Results: We studied 13 TAME patients-six in the mild hypercapnia and seven in the normocapnia group. The GLS was low in both groups during and after the intervention period. During hypercapnia, the mild hypercapnia group had worse median GLS compared to the normocapnia group [-10.2% (Q1-Q3: -11.5 to -8) vs. -14.2% (Q1-Q3: -15.2 to -11.2), P = 0.046]. The median GLS did not improve significantly after restoring normocapnia in the mild hypercapnia group [-10.2% (Q1-Q3: -11.5 to -8) to -11.6% (Q1-Q3: -12.1 to -7.8); P = 0.63]. Repeated measures mixed-effects regression showed no significant worsening of GLS due to hypercapnia [-2.7% (95% CI: -0.7 to 6.03), P = 0.12].

Conclusion: In this exploratory sub-study, adults resuscitated after OHCA had persistent LV dysfunction even after the cessation of mild hypercapnia. Mild hypercapnia did not significantly impair LV systolic function, although mild persistent LV systolic dysfunction cannot be ruled out in this small study.

Keywords: TAME cardiac arrest trial; echocardiography; global longitudinal strain; normocapnia; out‐of‐hospital cardiac arrest; post‐cardiac arrest care; targeted mild hypercapnia.