Michelle Mertz

Under-resuscitation of near-lethal uncontrolled hemorrhage: effects on mortality and end-organ function at 72 hours.

Laboratory studies of uncontrolled hemorrhage demonstrate that under resuscitation (UR) improves short-term survival, but at the expense of tissue perfusion. The long-term effects of UR have not been studied. The purpose of this study was to evaluate survival and the incidence of end-organ injury (EOI), 3 days following moderate and severe UR of uncontrolled hemorrhage. Thirty-four swine (14-24 kg) were assigned to 4 groups: Groups I, II, and III were hemorrhaged to a pulse pressure = 5 mmHg in the presence of a 4-mm aortic tear: Group I (control; n = 6) was not resuscitated; Group II (n = 11) was severely under resuscitated (MAP [mean arterial pressure] = 40 mmHg) for 75 min; Group III (n = 9) was moderately under resuscitated (MAP = 60 mmHg) for 75 min. After 75 min, the aortotomy was repaired, and animals were resuscitated to baseline physiologic parameters. Group IV (sham; n = 8) was instrumented, but not hemorrhaged. Seventy-two-hour mortality was 100%, 36%, 22%, and 0% for Groups I through IV (P = .001 Fishers exact). Cardiac indices, serum bicarbonate, and systemic oxygen delivery were significantly lower in Group II as compared to Group III during the 75 min of UR (P < 0.05; repeated measures ANOVA). By 72 h, physiologic parameters in surviving animals had returned to baseline levels. Measures of kidney, liver, neurologic, and pulmonary function did not change from baseline. There was no histologic evidence of EOI. In this model, 75 min of UR did not result in EOI. There was a trend toward greater survival, and tissue perfusion was better preserved with moderate as compared to severe UR.

Effects of ethanol on brain lactate in experimental traumatic brain injury with hemorrhagic shock

OBJECTIVE Previous studies of traumatic brain injury (TBI) and hemorrhagic shock (HS) models, have shown cardiorespiratory depression in ethanol-treated animals. This study investigated the effects of ethanol (ET) on brain lactate concentrations and acidosis in a TBI/HS model. METHODS Anesthetized swine were instrumented and subjected to injury (INJ) consisting of fluid percussion TBI of 3 atm with concurrent 30 ml/kg graded hemorrhage over 30 min. Three groups were studied: Sham, INJ and INJ/ET. ET was given preinjury as a 2-g/kg i.v. bolus over 30 min, and an infusion of 0.4 g kg(-1) h(-1). Cardiorespiratory and cerebral physiologic data were monitored continuously for 150 min postinjury. Cerebral and renal blood flow was measured with colored microspheres. Brains were frozen in situ with liquid nitrogen. Lactate was measured with an enzymatic method. RESULTS ET levels at injury were 219+/-24 mg/dl. The INJ/ET group had increased mortality, impaired ventilation, and reduced renal blood flow. Brain (cortical) lactate levels were significantly higher and cerebral venous lactate concentrations were increased in the INJ/ET group during the postinjury period. Cerebral venous glucose was significantly higher in the INJ/ET group, and cerebral venous pH was significantly lower. CONCLUSION In this TBI/HS model, ethanol-induced increases in lactate concentrations in brain tissue and cerebral venous blood are associated with respiratory depression and reduced organ blood flow.

The Effect of a New Tissue-Adhesive Wound Dressing on the Healing of Traumatic Abrasions

Background: Octylcyanoacrylate is a new medical-grade adhesive with antimicrobial properties. It forms a thin, flexible, occlusive bandage. Objective: To determine the gross and histological effects of the spray bandage when treating abrasions. Methods: Abrasions were produced on the flanks of 18 albino guinea pigs and randomized to treatment with a control (Biobrane) or octylcyanoacrylate dressing. The wounds were assessed with digital photography using a previously validated method. Histopathological analysis was done on day 14. Results: There were no differences in the mean wound-healing ratios on days 1 (1.25 vs. 1.23, p = 0.61), 7 (1.15 vs. 1.13, p = 0.14) and 14 (1.03 vs. 1.02, p = 0.63) for tissue adhesive and Biobrane, respectively. There were no differences found on histopathological analysis either. Conclusions: This external spray bandage was well tolerated and did not show any signs of histotoxicity or adverse wound healing.