Elsevier

Resuscitation

Volume 84, Issue 6, June 2013, Pages 798-804
Resuscitation

Clinical paper
Haemodynamic variables and functional outcome in hypothermic patients following out-of-hospital cardiac arrest

https://doi.org/10.1016/j.resuscitation.2012.10.012Get rights and content

Abstract

Aim of the study

To evaluate the association between haemodynamic variables during the first 24 h after intensive care unit (ICU) admission and neurological outcome in out-of-hospital cardiac arrest (OHCA) victims undergoing therapeutic hypothermia.

Methods

In a multi-disciplinary ICU, records were reviewed for comatose OHCA patients undergoing therapeutic hypothermia. The hourly variable time integral of haemodynamic variables during the first 24 h after admission was calculated. Neurologic outcome was assessed at day 28 and graded as favourable or adverse based on the Cerebral Performance Category of 1–2 and 3–5. Bi- and multivariate regression models adjusted for confounding variables were used to evaluate the association between haemodynamic variables and functional outcome.

Results

67/134 patients (50%) were classified as having favourable outcome. Patients with adverse outcome had a higher mean heart rate (73 [62–86] vs. 66 [60–78] bpm; p = 0.04) and received noradrenaline more frequently (n = 17 [25.4%] vs. n = 9 [6%]; p = 0.02) and at a higher dosage (128 [56–1004] vs. 13 [2–162] μg h−1; p = 0.03) than patients with favourable outcome. The mean perfusion pressure (mean arterial blood pressure minus central venous blood pressure) (OR = 1.001, 95% CI  = 1–1.003; p = 0.04) and cardiac index time integral (OR = 1.055, 95% CI = 1.003–1.109; p = 0.04) were independently associated with adverse outcome at day 28.

Conclusion

Mean perfusion pressure and cardiac index during the first 24 h after ICU admission were weakly associated with neurological outcome in an OHCA population undergoing therapeutic hypothermia. Further studies need to elucidate whether norepinephrine-induced increases in perfusion pressure and cardiac index may contribute to adverse neurologic outcome following OHCA.

Introduction

Outcome of patients experiencing cardiac arrest is dismal and favourable neurological recovery can only be achieved in a minority.1, 2 Although timely institution of effective cardiopulmonary resuscitation is crucial for survival,3 therapeutic interventions implemented after return of spontaneous circulation (e.g. therapeutic hypothermia) can reduce mortality and improve functional neurologic outcome as well.4, 5, 6

The impact of haemodynamic management during and after therapeutic hypothermia on cerebral outcome is not known. Cerebral perfusion may critically depend on systemic blood flow and arterial blood pressure during the post-cardiac arrest period.7 On the other hand, over-aggressive modulation of haemodynamic function with the use of catecholamines may bear relevant risks. Cerebral hyperperfusion due to arterial hypertension or elevated systemic blood flow could facilitate brain swelling and intracranial hypertension. Liberal use of catecholamines is associated with adverse cardiac side effects and may be detrimental to the heart in the early post-resuscitation period.8 In the immediate phase following return of spontaneous circulation arterial hypotension has been associated with increased mortality,9 whereas arterial hypertension has been suggested to have protective effects.7 We found previously no association between functional outcome after resuscitation and haemodynamic variables during the first 24 h of intensive care in patients who were not treated with therapeutic hypothermia.10 Since hypothermia has diverse cardiovascular and metabolic effects,11 data from normothermic post-cardiac arrest patients cannot be extrapolated to those treated with hypothermia.

In this retrospective cohort study, we evaluated whether there is an association between haemodynamic variables collected during the first 24 h after intensive care unit (ICU) admission and neurological outcome in comatose out-of-hospital cardiac arrest (OHCA) victims subjected to therapeutic hypothermia.

Section snippets

Methods

This study was performed in a 36-bed multi-disciplinary ICU in a university hospital. Medical records from April 1, 2007 until December 30, 2010 were reviewed for comatose patients admitted after resuscitation from OHCA treated with mild hypothermia. Cardiac arrest was defined as circulatory collapse without a palpable carotid or femoral pulse resulting in the need for mechanical cardiopulmonary resuscitation with chest compressions and ventilation. Coma was defined as a Glasgow Coma scale < 9, 30

Results

During the study period, 260 patients were admitted to the ICU after cardiac arrest. Hundred and thirty four of them fulfilled the inclusion criteria and were included in this analysis (Electronic supplementary material-Fig. 2). Reasons for exclusion were: in-hospital cardiac arrest (n = 10), no induction of therapeutic hypothermia (n = 116). Sixty-seven (50%) of study patients were classified as having favourable outcome according to the cerebral performance category at day 28 after cardiac

Discussion

In this retrospective analysis of 134 OHCA patients treated with therapeutic hypothermia, adverse neurological outcome at day 28 was associated with higher mean perfusion pressure and cardiac index. While no threshold limit critical for neurological outcome was detected for cardiac index, drops below a mean perfusion pressure of 80 mmHg appeared to be associated with adverse functional outcome. Furthermore, patients with adverse outcome received more often noradrenaline at higher dosages than

Conclusion

Mean perfusion pressure and cardiac index during the first 24 h after ICU admission were weakly associated with neurological outcome in an OHCA population undergoing therapeutic hypothermia. Further studies need to elucidate whether norepinephrine-induced increases in perfusion pressure and cardiac index may contribute to adverse neurologic outcome following OHCA.

Conflict of interest statement

No author has a conflict of interest in regards of drugs or techniques described in this manuscript.

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    A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.10.012.

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    Both authors contributed equally to this manuscript.

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