Nitric oxide production is enhanced in patients with heat stroke

Abstract

Objective: To determine whether nitric oxide (NO) production is increased in heat stroke (HS) patients.

Design: A prospective analysis of nitrite and nitrate (NO2*/NO3) levels in ten HS patients was performed at the HS center in Makkah, Saudi Arabia.

Methods: Plasma (NO2*/NO3) levels were determined spectrophotometrically before cooling (0 time), and at 6, 12, and 24 h post-cooling.

Results: The mean level of NO in the ten HS victims before cooling was significantly higher than in eight control patients (35.6+/-37.0 vs. 3.0+/-4.2 micromol/l; p<0.01). The levels were higher in non-survivors than in survivors. NO also correlated positively with the Acute Physiology and Chronic Health Evaluation II score (r = 0.72, p<0.018). There was no correlation between the NO level before cooling and blood pressure, rectal temperature, or cooling time.

Conclusion: HS is associated with excessive NO production, the magnitude of which is proportional to the severity of illness. NO may be an important mediator and integral part of the pathophysiological processes resulting in HS and may be a central factor linking the neurological and cardiovascular abnormalities observed in HS.