Blood pH is a useful indicator for initiation of therapeutic hypothermia in the early phase of resuscitation after comatose cardiac arrest: a retrospective study.

BACKGROUND: Therapeutic hypothermia (TH) is one of the key treatments after cardiac arrest (CA). Selection of post-CA patients for TH remains problematic, as there are no clinically validated tools to determine who might benefit from the therapy.

OBJECTIVE: The aim of this study was to investigate retrospectively whether laboratory findings or other patient data obtained during the early phase of hospital admission could be correlated with neurological outcome after TH in comatose survivors of CA.

METHODS: Medical charts of witnessed CA patients admitted between June 2003 and July 2009 who were treated with TH were reviewed retrospectively. The subjects were grouped based on their cerebral performance category (CPC) 6 months after CA, as either good recovery (GR) for CPC 1-2 or non-good recovery (non-GR) for CPC 3-5. The following well-known determinants of outcome obtained during the early phase of hospital admission were evaluated: age, gender, body mass index, cardiac origin, presence of ventricular fibrillation (VF), time from collapse to cardiopulmonary resuscitation, time from collapse to return of spontaneous circulation, body temperature, arterial blood gases, and blood test results.

RESULTS: We analyzed a total of 50 (25 GR and 25 non-GR) patients. Multivariate logistic analysis showed that initial heart rhythm and pH levels were significantly higher in the GR group than in the non-GR group (ventricular tachycardia/VF rate: p = 0.055, 95% confidence interval [CI] 0.768-84.272, odds ratio [OR] 8.047; pH: 7.155 ± 0.139 vs. 6.895 ± 0.100, respectively, p < 0.001, 95% CI 1.838-25.827; OR 6.89).

CONCLUSION: These results imply that in addition to initial heart rhythm, pH level may be a good candidate for neurological outcome predictor even though previous research has found no correlation between initial pH value and neurological outcome.