Histopathological effects on epidural tissue of bolus or continuous infusions through an epidural catheter in ewes.

This study was performed to evaluate the histopathological effects of epidural drug injection given either by intermittent bolus or continuous infusion through a catheter on epidural tissue. Fourteen ewes received intermittent bolus injections of morphine with bupivacaine, or a bolus of the same drugs followed by continuous infusion for 5 days. After 5 days, histopathological examination of the epidural space revealed mild to moderate inflammatory changes, and focal fibrosis surrounding the catheter in all ewes. The similarity of the inflammatory reaction in the control and drug treated groups seems to indicate that neither intermittent bolus or continuous infusion after a bolus dose caused histopathological changes in the epidural space beyond that caused by the catheter itself.

The effect of propofol and alfentanil on the increase in intraocular pressure due to succinylcholine and intubation.

PURPOSE: The aim of this study was to evaluate the effects of propofol and alfentanil on the increase in intraocular pressure (IOP) due to succinylcholine and intubation, in comparison with thiopental sodium and vecuronium bromide. METHODS: Forty patients aged 20-50 years, scheduled for elective surgery requiring endotracheal intubation, were assigned to four groups of ten. General anesthesia was induced with 2.5 mg/kg propofol in Group I, 2.5 mg/kg propofol and 10 microg/kg alfentanil in Group II and 5 mg/kg thiopental in Groups III and IV; muscle relaxation was obtained with either 1.5 mg/kg succinylcholine (Group I, II and III) or 0.1 mg/kg vecuronium bromide (Group IV). In all patients mean arterial pressure, heart rate, oxygen saturation and IOP were recorded before (baseline) and after induction, after the muscle relaxant and after endotracheal intubation. RESULTS: Compared with their baseline values in Group I IOP decreased significantly after propofol (p<0.01) and increased significantly after intubation (p<0.01). In Group II IOP decreased significantly after propofol and alfentanyl (p<0.001), remained low after succinylcholine (p<0.01) and did not change after intubation. In Group III IOP decreased significantly after thiopental (p<0.001) and increased significantly after intubation (p<0.001). In Group IV it decreased significantly after thiopental (p<0.001), remained low after vecuronium (p<0.001) and increased significantly after intubation (p<0.05). CONCLUSIONS: In all Groups, IOP did not increase significantly after succinylcholine, but only anesthesia induced with propofol and alfentanil prevented the increase in IOP due to intubation.

The in vitro effects of isoflurane, sevoflurane, and propofol on platelet aggregation.

UNLABELLED: We studied the in vitro effects of sevoflurane, isoflurane, and propofol anesthesia on platelet function. Thirty patients undergoing minor surgical procedures were divided into three groups (n = 10 each). Induction of anesthesia was achieved by using 5 mg/kg thiopental i.v., and 0.1 mg/kg vecuronium i.v. was used for muscle relaxation. Anesthesia maintenance was provided by sevoflurane in the first, isoflurane in the second, and propofol infusion in the third group with 70% N2O in O2. Hemoglobin, hematocrit, thrombocyte count, prothrombin time, activated partial thromboplastin time, international normalized ratio, arterial pH, von Willebrand factor, viscosity, platelet aggregation, and bleeding time were measured 1 h pre-, intra-, and postanesthesia. There was no difference among the platelet aggregation ratios of the pre-, intra-, and postoperative periods in the isoflurane group. The aggregation ratios in the sevoflurane and propofol groups were significantly reduced at intraoperative periods compared with preoperative values. Diminished aggregation values were also found 1 h postoperatively compared with the control values in the sevoflurane and propofol groups. We conclude that, in patients with a bleeding tendency during the intra- and early postoperative period, isoflurane may be preferred as a general anesthetic. IMPLICATIONS: In our study, using vacuum-operated tubes, we demonstrated that sevoflurane and propofol had a significant inhibitory effect on intraoperative and early postoperative platelet aggregation, whereas isoflurane had no effect. Therefore, isoflurane may be preferred as a general anesthetic in patients with a clinically relevant bleeding tendency.

Effect of chronic halothane exposure on lipid peroxidation, osmotic fragility and morphology of rat erythrocytes.

Effect of chronic halothane exposure on hepatic and erythrocyte lipid peroxidation and erythrocyte osmotic fragility and morphology were determined in rats exposed to 0.4% halothane, 8 h per day for 40 days. Hepatic lipid peroxidation was increased in the halothane-treated group compared to controls. Lipid peroxidation was not increased by halothane exposure in erythrocytes without hydrogen peroxide, but after peroxide supplementation lipid peroxidation increased more in the erythrocytes of halothane-exposed rats than in control rats. We have observed significant morphological changes in erythrocytes from halothane-treated rats. In addition, erythrocytes of halothane-treated rats were more fragile in saline solutions compared to those of controls. Our results suggest that chronic halothane exposure is not only hepatotoxic but also affects erythrocyte membrane structure and stability.