Phrenic nerve conduction studies in acute organophosphate poisoning.
Phrenic nerve conduction studies were performed within 48 h of admission and subsequently in 29 patients (14 of whom required mechanical ventilation) with acute organophosphate (OP) poisoning. The mean (+/-SD) amplitude of the diaphragmatic compound muscle action potential (CMAP) in patients requiring mechanical ventilation (119.09 +/- 173.85 microV) was significantly lower than in those not requiring mechanical ventilation (461.63 +/- 138.69 microV) (P < 0.0001). Diaphragmatic CMAP amplitudes in ventilated patients increased with time during the course of hospitalization and were normal in 5 (36%) patients and only mildly reduced in another 6 (43%) patients prior to discontinuation of mechanical ventilation, which was undertaken 4-18 days (mean 7 +/- 3 days) after poisoning. Eleven patients (79%) were successfully weaned from mechanical ventilation at the first attempt. In the 3 (21%) remaining patients, mechanical ventilation had to be reestablished because of weaning failure. The mean (+/-SD) diaphragmatic CMAP amplitude, prior to discontinuation of ventilatory assistance, was 242.6 +/- 94.1 microV in these 3 patients. After ventilatory discontinuation, it fell to 95.5 +/- 105.8 microV. Thus, reduced diaphragmatic CMAP amplitudes correlate with the need for mechanical ventilation in acute OP poisoning.
Singh
G
G
Department of Medicine, Dayanand Medical College, Ludhiana, Punjab, India. dr_gagan@hotmail.com
Sidhu
U P
UP
Mahajan
R
R
Avasthi
G
G
Whig
J
J
D000200:Action Potentials; D000328:Adult; D004558:Electric Stimulation; D004568:Electrodiagnosis; D005260:Female; D006801:Humans; D007306:Insecticides / Q000506:poisoning*; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009431:Neural Conduction; D009943:Organophosphorus Compounds; D010791:Phrenic Nerve / Q000503:physiopathology*; D011041:Poisoning / Q000175:diagnosis / Q000503:physiopathology*; D012121:Respiration, Artificial; D013997:Time Factors
D007306:Insecticides; D009943:Organophosphorus Compounds