Comparison of the characteristics and outcome between patients suffering from out-of-hospital primary cardiac arrest and drowning victims with cardiac arrest: an analysis of variables based on the Utstein Style for Drowning

Introduction

In 2003, ILCOR published the Utstein Style for Drowning (UFSD) to improve the understanding of epidemiology, treatment and outcome prediction after drowning. Characteristics and outcome among patients with out-of-hospital primary cardiac arrest (OHPCA) compared with drowning victims with cardiac arrest (DCA) patients were described with application and evaluation of UFSD data for outcome analysis.

Methods

All patients with OHPCA and DCA from February 1998 to February 2007 were included in the research and analysis. Data on patients with OHPCA and DCA were collected prospectively using the Utstein method. Data on patients with DCA were then compared with data of patients with OHPCA.

Results

During the study period 788 cardiac arrests with resuscitation attempts were identified: 528 of them were OHPCA (67%) and 32 (4%) were DCA. The differences between patients with DCA and patients with OHPCA were: the patients with DCA were younger (46.5 ± 21.4 vs 62.5 ± 15.8 years; P = 0.01), they suffered a witnessed cardiac arrest less frequently (9/32 vs 343/528; P = 0.03), they were more often found in a non-shockable rhythm (29/3 vs 297/231; P < 0.0001), they had a prolonged ambulance response time (11 vs 6 min; P = 0.001), they had a relatively better (but not statistically significant) return of spontaneous circulation in the field (22/32 (65%) vs 301/528 (57%); P = 0.33) and more of them were admitted to hospital (19/32 (60%) vs 253/528 (48%); P = 0.27) and they also had a significantly higher survival rate – discharge from hospital (14/32 (44%) vs 116/528 (22%); P = 0.01). Patients with DCA had higher values of initial partial pressure of end-tidal carbon dioxide (petCO₂) (53.2 ± 16.8 vs 15.8 ± 8.3 mmHg; P < 0.0001) and average petCO₂ (43.5 ± 13.8 vs 23.5 ± 8.2; P = 0.002). These values of petCO₂ suggest asphyxial mechanism of cardiac arrest. The analysis showed that survived patients with DCA were younger, had more bystander cardiopulmonary resuscitation, shorter call–arrival interval, higher values of petCO₂ after 1 minute of cardiopulmonary resuscitation, higher average and final values of petCO₂, a lower value of initial serum K⁺ and more of them received vasopressin (P < 0.05) in comparison with DCA patients who did not survive.

Conclusion

Patients with DCA had a better survival rate (discharge from hospital) and higher initial and average petCO₂ values, and more of them had a nonshockable initial rhythm.