Prearrest signs of shock and respiratory insufficiency in out-of-hospital cardiac arrests witnessed by crew of the emergency medical service

Aim

The objective of this study is to determine whether prearrest shock and respiratory insufficiency influence outcome in patients with emergency medical service–witnessed out-of-hospital cardiac arrest.

Methods

Analysis of data from a cardiac arrest database and data from the ambulance charts was performed. For the purpose of the study, shock was defined as prearrest heart rate below 40 or above 140/min, systolic blood pressure as below 90 mm Hg, and respiratory insufficiency as respiratory rate above 36 or oxygen saturation below 90%. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

Results

Of a total of 303 patients, 81% had prearrest shock or respiratory insufficiency. Mortality was higher in these patients indicated by fewer with return of spontaneous circulation (43% vs 75%, P < .001), and lower survival to hospital admission (31% vs 71%, P < .001) and to discharge (13% vs 59%, P < .001). Independent predictors of mortality were age (OR, 1.04; CI, 1.0-1.06), initial rhythm other than ventricular fibrillation or ventricular tachycardia (OR, 32.9; CI, 10.9-99.0), and respiratory insufficiency (OR, 4.2; CI, 1.4-12.5).

Conclusions

Shock and respiratory depression are common among patients with out-of-hospital cardiac arrest witnessed by the emergency medical service, and these patients have a high mortality when compared with patients without shock or respiratory failure.