Respiratory failure of acute organophosphate and carbamate poisoning

Respiratory failure (RF) developed in 43 (40.2 percent) of 107 patients with acute organophosphate or carbamate poisoning; 22 (51.2 percent) died. The 64 patients who did not develop RF survived. All cases of RF developed within 96 hours after poisoning: within 24 hours in 35 patients (acute onset) and between 24 and 96 hours in eight patients (subacute onset). Severity of poisoning was the primary determinating factor for RF. Cardiovascular collapse and pneumonia were also associated with RF. In 19 patients with cardiovascular collapse, 17 had acute onset of RF and two had subacute onset. In 28 patients with pneumonia, 17 developed acute onset of RF and eight developed subacute onset. No organophosphorus compound caused RF more frequently than another. The duration of ventilator support for subacute RF was significantly longer than for acute RF (287 +/- 186 vs 115 +/- 103 hours, p = 0.02). The use of pralidoxime did not reduce the incidence of RF. We found that severity of poisoning, cardiovascular collapse, and pneumonia were the predisposing factors to RF. The golden time for treatment of acute organophosphate or carbamate poisoning was the initial 96 hours. No RF occurred after this time. Aggressive treatment and prevention of the above three factors will reduce the incidence of RF, or in other words, reduce the mortality.