Hemodynamic Changes and Intravascular Hydration State in Heat Stroke

Abstract

Acute and serial hemodynamic measurements in 13 pilgrims (average age, 55.2 ± SD 9.3 years) suffering from heat stroke (average rectal temperature, 41.3 ± 1.0°C) revealed a hyperdynamic circulation pattern and a low total peripheral resistance. Five patients had pulmonary edema with an average cardiac index of 5.29 ± SD 0.56 L/min/m 2 , which was slightly higher than the average cardiac index in the group of eight patients without pulmonary edema, 4.76 ± SD 0.6 L/min/m 2 . This higher cardiac index was believed to be due to iatrogenic fluid overload which was hard to accommodate intravascularly with the cooling process raising the peripheral vascular resistance, decreasing the venous capacitance, and redistributing the blood from the dilated circulatory bed in the skin to the central circulation. Our data highlight the fact that there is no major intravascular dehydration in heat stroke. The treatment of choice is cooling. The entire process of "supporting the cardiovascular system" should take into consideration avoidance of fluid overload by rapid intravenous fluid administration. Gradual hydration, allowing time for intracellular compartment repletion after cooling, is more appropriate.

Nitric oxide production is enhanced in patients with heat stroke

“…Similar hemodynamic alterations have been demonstrated in HS victims [4,20,21]. Most of these effects have been attributed to the activation of soluble guanylate cyclase resulting in the formation of cGMP.…”

Cooling and hemodynamic management in heatstroke: practical recommendations

“…Various target temperatures ranging from 37°C to 40.1°C for safe discontinuation of cooling were used. Five observational studies met the criteria for the assessment of hemodynamic management [ 31 , 34 , 37 - 39 ]. The total number of patients reported in these 19 publications was 556, and these were subjected to further analysis (Tables 2 , 3 , 4 , 5 , 6 ).…”

“…Studies in animal experiments suggest that secondary splanchnic vasodilation mediated by local production of nitric oxide results in cardiovascular collapse and hyperthermia [ 44 , 45 ]. In contrast, the hemodynamic alterations that follow heatstroke have not been completely elucidated [ 31 , 34 , 37 - 39 ].…”

“…The search strategy used for this review yielded five studies on the hemodynamic alterations in heatstroke with monitored response to therapy [ 31 , 34 , 37 - 39 ]. Table 6 presents a summary of data on hemodynamic monitoring and support in heatstroke.…”

“…By means of right heart catheterization, the hemodynamic profile of 30 elderly patients suffering from classic heatstroke was investigated in three studies [ 31 , 37 , 38 ] (Table 5 ). Twenty-three (76.6%) of the patients exhibited a hyperdynamic profile, and 6 (20%) a hypodynamic profile.…”