Prognostic factors of acute calcium-channel blocker poisonings

Introduction

The incidence of acute calcium-channel blocker (CCB) poisonings is increasing. Our objectives were to describe the CCB-poisoned patients admitted to the ICU and to determine the prognostic factors.

Methods

Retrospective collection of clinical data in three ICU in 2000–2006; determination of plasma concentration using HPLC (REMEDI). Description (median, (25–75% percentiles)); comparisons using Mann–Whitney and chi-squared tests; multivariate analysis using a step-by-step logistic regression model.

Results

Eighty-four patients (47 males/36 females, 44 years (31–56); SAPS II, 15 (8–25)) were included. Verapamil (39/83), diltiazem (13/83), nifedipine (11/83), nicardipin (9/83), and amlopdipine (8/83) were involved. On admission, systolic blood pressure was 105 mmHg (86–118), heart rate 76/min (67–91), QRS duration 85 ms (80–110), and plasma lactate concentration 2.86 mmol/l (1.79–5.98). Poisoning features included shock (42/83), atrioventricular block (34/83), asystole (8/83), and/or ventricular arrhythmia (4/83). All patients received fluid replacement, 50/83 epinephrine infusion (maximal rate: 3.0 mg/hour (1.4–8.0)), and 27/83 norepinephrine (5.0 mg/hour (2.9–15.0)). Thirty-three out of 83 were mechanically ventilated. Treatments included calcium salts (22/83), glucagon (18/83), dobutamine (18./33), 8.4% sodium bicarbonate (16/83), isoprenaline (14/83), insulin + glucose (13/83), terlipressin (4/83), electrosystolic stimulation (2/83), and extracorporeal life support (5/83). Eleven patients (13%) died in the ICU. The plasma verapamil concentration was significantly different on admission regarding survival (800 versus 2,522 mg/l, P < 0.05). If excluding SAPS II from the model, multivariate analysis showed that QRS duration (>100 ms; OR, 5.3; 95% CI, 1.1–27.0) and maximal epinephrine rate (>5 mg/hour; OR, 27.6; 9%% CI, 5.3–144.7) were the only two predictive factors of death (P = 0.007). Shock was refractory if epinephrine + norepinephrine was ≥ 8 mg/hour with renal (creatinine > 150 μmol/l) or respiratory failure (PaO₂/FiO₂ > 150 mmHg) (sensitivity, 100%; specificity, 89%).

Conclusion

Despite optimal management in the ICU, the CCB poisoning mortality remains high (13%), encouraging development of extracorporeal life support and new antidotes.