Electrolyte abnormalities and laboratory findings in patients with out-of-hospital cardiac arrest who have kidney disease.

PURPOSES: Although electrolyte abnormalities have been generally considered the major cause of out-of-hospital cardiac arrest (OHCA) in patients with kidney disease (KD), this association has never been prospectively validated. METHODS: A prospective, observational study was conducted in a tertiary university hospital between January 2008 and December 2009. The study sample consisted of consecutively admitted patients with nontraumatic OHCA. Based on the estimated glomerular filtration rate (eGFR, unit: milliliters per minute per 1.73 m(2)), the enrollees were divided into 3 groups: group A (normal kidney function or mild KD; eGFR, 60.0), group B (moderate KD; eGFR between 15.0 and 59.9), and group C (severe KD; eGFR<15.0 or on dialysis). The laboratory findings of the groups were compared. Two-tailed P values less than .005 were considered significant. RESULTS: Two hundred thirty-four enrollees (137 were male) were divided into 3 groups: group A (n = 51; 21.8%), group B (n = 128; 54.7%), and group C (n = 55; 23.5%). Compared with the other 2 groups, group C presented significantly higher serum potassium and magnesium and lower pH and hemoglobin level (all P < .005). After stratifications of the significant variables, a post hoc analysis revealed that group C presented significantly higher incidences of hypermagnesemia (Mg >2.5 mmol/L) and severe hyperkalemia (K >6.5 mmol/L) (both P < .005) than the other 2 groups. The odds ratios of the incidence of severe hyperkalemia in group C was 3.37 (95% confidence intervals, 1.46-7.77) compared with group A (50.9% vs 23.5%, P < .005). CONCLUSIONS: Severe hyperkalemia is common in patients with OHCA who have severe KD and should be considered during resuscitation for these patients.

Prognostic values of blood ammonia and partial pressure of ammonia on hospital arrival in out-of-hospital cardiac arrests.

PURPOSES: Outcome prediction for out-of-hospital cardiac arrest (OHCA) is of medical, ethical, and socioeconomic importance. We hypothesized that blood ammonia may reflect tissue hypoxia in OHCA patients and conducted this study to evaluate the prognostic value of ammonia for the return of spontaneous circulation (ROSC). METHODS: This prospective, observational study was conducted in a tertiary university hospital between January 2008 and December 2008. The subjects consisted of OHCA patients who were sent to the emergency department (ED). The primary outcome was ROSC. The prognostic values were calculated for ammonia levels and the partial pressure of ammonia (pNH(3)), and the results were depicted as a receiver operating characteristics curve with an area under the curve. RESULTS: Among 119 patients enrolled in this study, 28 patients (23.5%) achieved ROSC. Ammonia levels and pNH(3) in the non-ROSC group were significantly higher than those in the ROSC group (167.0 µmol/L vs 80.0 µmol/L, P < .05; 2.61 × 10(-5) vs 1.67 × 10(-5) mm Hg, P < .05, respectively). The predictive capacity of area under the curve for ammonia and pNH(3) for non-ROSC was 0.85 (95% confidence interval, 0.75-0.95) and 0.73 (95% confidence interval, 0.61-0.84), respectively. The multivariate analysis confirmed that ammonia and pNH(3) are independent predictors of non-ROSC. The prognostic value of ammonia was better than that of pNH(3). The cutoff level for ammonia of 84 µmol/L was 94.5% sensitive and 75.0% specific for predicting non-ROSC with a diagnostic accuracy of 89.9%. CONCLUSIONS: Hyperammonemia on ED arrival is independently predictive of non-ROSC for OHCA patients. The findings may offer useful information for clinical management.

Use of automated external defibrillators in patients with traumatic out-of-hospital cardiac arrest.

BACKGROUND: Because out-of-hospital cardiac arrests (OHCAs) due to a major trauma rarely present with shockable rhythms, the potential benefits of using automated external defibrillators (AEDs) at the scene of traumatic OHCAs have not been examined. METHODS: We conducted an observational, retrospective cohort study using an Utstein-style analysis in Tainan city, Taiwan. The enrollees were adult patients with traumatic OHCAs accessed by emergency medical technicians (EMTs) from January 1, 2004 to December 31, 2010. The exposure was the use or non-use of AEDs at the scene, as determined by the clinical judgment of the EMTs. The primary outcome evaluated was a sustained (≥2h) return of spontaneous circulation (ROSC), and the secondary outcomes were prehospital ROSC, overall ROSC, survival to hospital admission, survival at one month and favorable neurologic status at one month. RESULTS: A total of 424 patients (313 males) were enrolled, of whom 280 had AEDs applied, and 144 did not. Only 25 (5.9%) patients had received bystander cardiopulmonary resuscitation (CPR), and merely 21 (7.5%) patients in the AED group presented with shockable rhythms. Compared to the non-AED group, the primary and secondary outcomes of the AED group were not significantly different, except for a significantly lower prehospital ROSC rate (1.1% vs. 4.9%, p<0.05). Multivariate analysis showed no significant interactions between the use of AEDs and other key variables. Use of the AED was not associated with sustained ROSC (OR 1.33; 95% CI 0.75-2.38, p=0.33). CONCLUSIONS: In a community with a low prevalence of shockable rhythms and administration of bystander CPR in patients with traumatic OHCA, we found no significant differences in the sustained ROSC between the AED and the non-AED groups. Considering scene safety and the possible interruption of CPR, we do not encourage the routine use of AEDs at the scene of traumatic OHCAs.