Comparison of the characteristics and outcome among patients suffering from out-of-hospital primary cardiac arrest and drowning victims in cardiac arrest

BACKGROUND In 2003, the International Liaison Committee on Resuscitation (ILCOR) published the Recommended Guidelines for Uniform Reporting of Data from Drowning: the "Utstein style" ("Utstein Style for Drowning," USFD) to improve the understanding of epidemiology, treatment, and outcome prediction after drowning. AIMS The aim of this study was to compare the characteristics and outcome between patients suffering from out-of-hospital primary cardiac arrest (OHPCA) and drowning victims in cardiac arrest (DCA) by analysis of variables based on the USFD. METHODS All cases of OHPCA and DCA from February 1998 to February 2007 were included in the research and analysis. Data on OHPCA and DCA patients were collected using the Utstein method. Data on DCA patients were then compared with data of OHPCA patients. 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 DCA and OHPCA patients were: the DCA patients were younger (46.5 +/- 21.4 vs 62.5 +/- 15.8; p = 0.01), suffered a witnessed cardiac arrest less frequently (9/32 vs 343/528; p = 0.03), were more often found in a nonshockable rhythm (29/32 vs 297/528; p < 0.0001), had a prolonged ambulance response time (11 vs 6 min; p = 0.001), had a relatively better (but not statistically significant) return of spontaneous circulation (ROSC) in the field [22/32 (65%) vs 301/528 (57%); p = 0.33], more of them were admitted to hospital [19/32 (60%) vs 253/528 (48%); p = 0.27], and also had a significantly higher survival rate (discharge from hospital) [14/32 (44%) vs 116/528 (22%); p = 0.01]. DCA patients had higher values of initial PETCO(2) (53.2 +/- 16.8 vs 15.8 +/- 8.3 mmHg; p < 0.0001) and average PETCO(2) (43.5 +/- 13.8 vs 23.5 +/- 8.2; p = 0.002). These values of PETCO(2) suggest an asphyxial mechanism of cardiac arrest. The analysis showed that DCA patients who survived were younger, had more bystander cardiopulmonary resuscitation (CPR), shorter call-arrival interval, higher values of PETCO(2) after 1 min of CPR, higher average and final values of PETCO(2), 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 DCA patients had a better survival rate (discharge from hospital), higher initial and average PETCO(2) values, and more of them had nonshockable initial rhythm. Survival (discharge from hospital) in DCA patients is associated with the PETCO(2) values, initial serum K+ values, administration of vasopressin, and ambulance response time.