UMEM Educational Pearls

Title: Mild Hypercapnia or Normocapnia after Out-of-Hospital Cardiac Arrest

Posted: 8/8/2023 by William Teeter, MD
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Targeted Therapeutic Mild Hypercapnia after Resuscitated Cardiac Arrest (TAME)

Current guidelines recommend normocapnia for out-of-hospital cardiac arrest (OHCA), the TAME Study asked is mild hypercapnia better?

Smaller previous studies have shown some benefits for hypercapnia including some improved outcomes:
- Increased likelihood of discharge home and better 12 month neurologic outcomes
The TAME study enrolled adults with OHCA with presumed cardiac or unknown cause within 3 hours of ROSC who were unconcious
Unwitnessed, asystolic, hypothermic, pregnant, or ICH patients were excluded.
- ECMO and Severe COPD patients on home O2 also excluded
Randomization to either 24 hours of PaCO2:
- Intervention arm: 50-55 mmHg
- Control: 35-45 mmHg
Strong design with strong methodology, adequate power, and good protocol adherence (>65% of measurements in group limitations)
Protocol violations in 8% of hypercapnia and 3% of normocapnia groups
Missing primary outcome data in 7% of patients.
Note: concurrent TTM trial (TTM2) was allowed to cross-enroll. Addressed with adequate statistical methodology

Primary outcome (Favorable neurological outcome (GOSE ≥ 5)
- 43.5% (mild hypercapnia) vs 44.6% (normocapnia)
  - ARR 0.98 (95% CI 0.87 to 1.11)
Secondary outcomes: no differences

Conclusion: "In patients with coma who were resuscitated after out-of-hospital cardiac arrest, targeted mild hypercapnia did not lead to better neurologic outcomes at 6 months than targeted normocapnia."

References

https://www.nejm.org/doi/full/10.1056/NEJMoa2214552

https://clinicaltrials.gov/study/NCT03114033

https://www.thebottomline.org.uk/blog/ebm/tame/