Surface cooling, which fails to reduce the core temperature rapidly, hastens death during severe hemorrhagic shock in pigs.

OBJECTIVE: To examine whether surface cooling (SC) would rapidly decrease the core temperatures and prolong the survival time during volume-controlled lethal hemorrhagic shock in pigs. METHOD: Twelve pigs were randomly assigned to the SC group (group 1, n = 6) or the no cooling control group (group 2, n = 6), after blood withdrawal of 30 mL/kg over 15 minutes, and maintained under spontaneous breathing by light anesthesia with 1.0% halothane. SC was performed by applying ethanol to the skin, blowing with an electric fan, and placing ice packs. Pigs were observed without fluid resuscitation until their death (apnea and no pulse). RESULTS: SC did not lower the rectal temperature (Tr) to 35 degrees C at any time point until death, except one pig; in that animal, Tr was decreased to 34 degrees C after 135 minutes from the start of SC. The survival time was 108 +/- 43 minutes in group 1 and 175 +/- 55 minutes in group 2 (p < 0.05, life table analysis). CONCLUSION: In lightly anesthetized pigs during hemorrhagic shock, SC without resuscitation did not rapidly reduce the core temperature and rather hastened death for reasons that remain to be explored.

Measurement of interleukin-6, interleukin-10, and tumor necrosis factor-alpha levels in tissues and plasma after thermal injury in mice.

BACKGROUND: Cytokines are important modulators of physiologic alterations after thermal injury. Indeed, an increase in the level of circulating cytokines has been documented after thermal injury. However, the mechanism of the increase has not been clarified. We determined cytokine levels in local tissue after thermal injury to identify the tissues responsible for the increase. METHODS: Female C57BL/6 mice each received a 20% full-thickness burn injury. Blood, burned skin, unburned skin, muscle underlying the burn, and muscle of the thigh, liver, spleen, and mesenteric lymph node were sampled at 1, 2, 4, 8, and 24 hours after injury. Uninjured control mice were treated similarly. The samples were cultured, and concentrations of tumor necrosis factor-alpha, interleukin-6 (IL-6), and IL-10 in the culture media were measured by using an enzyme-linked immunosorbent assay. RESULTS: IL-6 levels in unburned skin were significantly increased at 1 hour and decreased at 24 hours, compared with the control. IL-6 levels in muscle underlying the burn were significantly decreased at 8 hours. No elevation of plasma IL-6 levels was observed after injury. Neither tumor necrosis factor-alpha IL-10 was detected in any tissue. CONCLUSIONS: Results indicate that unburned skin may be a major source of IL-6 production after thermal injury and may contribute to the physiologic alterations occurring after such injury.

Effects of mild Trendelenburg on central hemodynamics and internal jugular vein velocity, cross-sectional area, and flow.

Despite widespread use of the Trendelenburg position, its autotransfusion effect remains controversial. Additionally, its adverse effect on cerebral circulation is not generally appreciated. The effects of a 10 degrees head-down tilt on central hemodynamics and flow through the internal jugular vein (IJV) were examined in ten healthy volunteers. Left ventricular end-diastolic volume (LVEDV) and cardiac output (CO) were calculated from two-dimensional echocardiograms. IJV velocity and cross-sectional area were determined by the pulsed Doppler system. Measurements were made with the subjects in the supine position and at 1 minute and 10 minutes after tilting. A significant increase (16%) in CO followed by the increase in LVEDV was observed at 1 minute after tilting, although these changes disappeared after 10 minutes of tilting. Mean arterial pressure at the heart level did not change during the maneuver. The IJV velocity decreased whereas the IJV cross-sectional area increased at 1 minute after tilting, but both factors returned to control level at 10 minutes after tilting. As a result, calculated IJV blood flow was unchanged throughout the period of tilt. Therefore, the mild trendelenburg position produces a transient autotransfusion effect in normovolemic patients. Our data also suggest that the Trendelenburg produces no adverse effect on cerebral circulation in patients with normal cerebral autoregulation.