Elsevier

Resuscitation

Volume 83, Issue 12, December 2012, Pages 1456-1461
Resuscitation

Clinical paper
Hyperoxia, hypocapnia and hypercapnia as outcome factors after cardiac arrest in children

https://doi.org/10.1016/j.resuscitation.2012.07.019Get rights and content

Abstract

Purpose

Arterial hyperoxia after resuscitation has been associated with increased mortality in adults. The aim of this study was to test the hypothesis that post-resuscitation hyperoxia and hypocapnia are associated with increased mortality after resuscitation in pediatric patients.

Methods

We performed a prospective observational multicenter hospital-based study including 223 children aged between 1 month and 18 years who achieved return of spontaneous circulation after in-hospital cardiac arrest and for whom arterial blood gas analysis data were available.

Results

After return of spontaneous circulation, 8.5% of patients had hyperoxia (defined as PaO2 > 300 mmHg) and 26.5% hypoxia (defined as PaO2 < 60 mmHg). No statistical differences in mortality were observed when patients with hyperoxia (52.6%), hypoxia (42.4%), or normoxia (40.7%) (p = 0.61). Hypocapnia (defined as PaCO2 < 30 mmHg) was observed in 13.5% of patients and hypercapnia (defined as PaCO2 > 50 mmHg) in 27.6%. Patients with hypercapnia or hypocapnia had significantly higher mortality (59.0% and 50.0%, respectively) than patients with normocapnia (33.1%) (p = 0.002). At 24 h after return of spontaneous circulation, neither PaO2 nor PaCO2 values were associated with mortality. Multiple logistic regression analysis showed that hypercapnia (OR, 3.27; 95% CI, 1.62–6.61; p = 0.001) and hypocapnia (OR, 2.71; 95% CI, 1.04–7.05; p = 0.04) after return of spontaneous circulation were significant mortality factors.

Conclusions

In children resuscitated from cardiac arrest, hyperoxemia after return of spontaneous circulation or 24 h later was not associated with mortality. On the other hand, hypercapnia and hypocapnia were associated with higher mortality than normocapnia.

Introduction

Current rates of return of spontaneous circulation (ROSC) after in-hospital cardiac arrest (CA) range from 50% to 73%; however, final survival is significantly lower.1, 2, 3, 4, 5, 6, 7 Consequently, stabilisation interventions after initially successful resuscitation must be improved in order to reverse post-CA syndrome.

Post-CA syndrome is the result of the prolonged period of systemic ischaemia during CA and the subsequent reperfusion response that occurs after resuscitation and ROSC.8, 9

Previous studies in animals have shown that excessive oxygen during the reperfusion period increases neuronal damage through production of free radicals and mitochondrial injury.10 Once ROSC is achieved, ventilation with the minimum fraction of inspired oxygen (FiO2) required to maintain adequate oxygen saturation of arterial blood (around 94%) may facilitate survival and favourable neurological outcome.11, 12, 13, 14, 15, 16 Several clinical studies of adult patients admitted to the intensive care unit after CA have analysed the influence of arterial hyperoxia on mortality and suggest that it significantly increases the mortality.17, 18, 19 However, data on the potential influence of hyperoxia on the outcome of CA and resuscitation in children are lacking.

Conversely, hyperventilation is thought to worsen outcome after ROSC, because it diminishes cerebral blood flow and increases brain ischaemia20, 21, 22; nevertheless, no clinical data have been published regarding the eventual influence of hypocapnia or hypercapnia on survival after CA.

We describe the incidence of hyperoxia, hypocapnia, and hypercapnia after ROSC and the outcome of children who suffered in-hospital CA. Our main objective was to test the hypothesis that hyperoxia and hypocapnia after ROSC are associated with increased mortality in paediatric in-hospital CA.

Section snippets

Methods

The study population comprised patients from an ongoing multicentre study aged 1 month to 18 years who suffered in-hospital CA and achieved ROSC between December 2007 and 2009. The inclusion criterion was to have had at least an arterial blood gas analysis performed at ROSC and 24 h after CA. The study was approved by the local institutional review boards. CA was defined as the absence of a palpable central pulse, unresponsiveness, apnoea and severe bradycardia of less than 60 bpm with poor

Results

Of a total of 543 in-hospital CA episodes registered, 386 (71%) achieved ROSC. The study sample comprised the 223 patients in whom arterial blood gas data after ROSC were available. The baseline characteristics of patients are described in Table 1. We found that 46.5% of patients were younger than 1 year and 59% weighed less than 10 kg. CA occurred in the paediatric intensive care unit in 64% of cases. Out of the 223 patients, 19 were classified as hyperoxic (8.5%) and 59 as hypoxic (26.5%) (

Discussion

Resuscitation from CA does not end after ROSC. Post-ROSC care has significant potential to prevent the early mortality caused by haemodynamic instability and further injury at the cellular level. The objectives of resuscitation include optimisation of cardiopulmonary function and systemic perfusion, identification of the precipitating causes of the arrest, institution of measures to prevent recurrence of CA and administration of therapies that might facilitate long-term survival.

Conclusions

Most children who suffer in-hospital CA, although resuscitated with 100% FiO2, are not exposed to arterial hyperoxia immediately after ROSC or 24 h later. Arterial hyperoxia at these time points was not associated with mortality in children. Ventilation during CPR and after ROSC achieves normal PaCO2 values in most paediatric patients. Hypercapnia after ROSC is more frequent than hypocapnia and both could be associated with higher mortality.

Although targeting normal PaO2 and PaCO2 could be

Conflicts of interest statement

None of the authors has declared a conflict of interest.

Sources of funding

The study was supported in part by grant RT02377 from the Science and Technology for Development Program (CYTED) and by grant PI081167 from the Spanish Health Institute Carlos III.

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  • Cited by (0)

    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.2012.07.019.

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    See Appendix A.

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