Anesthesiology

Low-dose ondansetron with dexamethasone more effectively decreases vomiting after strabismus surgery in children than does high-dose ondansetron.

Splinter WM. Rhine EJ.
Department of Anaesthesia, University of Ottawa, Ontario, Canada. Splinter@CHEO.on.ca
BACKGROUND: Ondansetron and dexamethasone have been observed to decrease the incidence of vomiting by children after general anesthesia. This study compared the effect of high-dose (150 microg/kg) ondansetron with low-dose (50 microg/kg) ondansetron plus 150 microg/kg dexamethasone on the incidence of vomiting after strabismus in children. METHODS: This study had a double-blind, blocked, stratified, randomized design. With parental consent and Hospital Ethics Committee approval, healthy children aged 2-14 yr who were undergoing elective strabismus surgery were studied. Anesthesia was induced intravenously with propofol or by inhalation with halothane and nitrous oxide. Patients in the high-dose group were given placebo plus 150 microg/kg (maximum dose, 8 mg) of ondansetron intravenously, whereas patients in the low-dose group were given 150 microg/kg dexamethasone (maximum dose, 8 mg) and 50 microg/kg ondansetron intravenously in a double-blind manner. Anesthesia was maintained with halothane and nitrous oxide. All incidences of vomiting occurring as long as 24 h after anesthesia were recorded. RESULTS: Three of the 200 patients enrolled in the study were excluded from data analysis. The groups were similar with respect to demographic data and potential confounding variables. Patients vomited from 0-12 times. The low-dose ondansetron plus dexamethasone group had a lower incidence of vomiting, 9% (95% CI = 4-17%) versus 28% (95% CI = 20-38%; P < 0.001). Only 1% of the patients in the low-dose ondansetron plus dexamethasone group vomited while in the hospital. CONCLUSIONS: Low-dose ondansetron plus dexamethasone is an effective prophylactic antiemetic combination for children undergoing strabismus surgery.

Absence of biochemical evidence for renal and hepatic dysfunction after 8 hours of 1.25 minimum alveolar concentration sevoflurane anesthesia in volunteers.

Year 1998
Ebert TJ. Frink EJ Jr. Kharasch ED.
Department of Anesthesiology, VA Medical Center, Milwaukee, Wisconsin 53295, USA. tjebert@mcw.edu
BACKGROUND: Sevoflurane is degraded by carbon dioxide absorbents to a difluorovinyl ether (compound A) that can cause renal and hepatic injury in rats. The present study applied sensitive markers of renal and hepatic function to determine the safety of prolonged (8 h), high concentration (3% end-tidal) sevoflurane anesthesia in human volunteers. METHODS: Thirteen healthy male volunteers provided informed consent to undergo 8 h of 1.25 minimum alveolar concentration sevoflurane anesthesia delivered with a fresh gas flow of 2 l/min. Glucose, protein, albumin, N-acetyl-beta-D-glucosaminidase (NAG), and alpha- and pi-glutathione-S-transferase (GST) levels were analyzed in urine collected at 24 h before and for 3 days after sevoflurane anesthesia. Daily blood samples were analyzed for creatinine, blood urea nitrogen (BUN), alanine aminotransferase, alkaline phosphatase, and bilirubin concentrations. Circuit compound A and plasma fluoride concentrations were measured. RESULTS: During anesthesia, average and maximum inspired compound A concentrations were 27 +/- 7 and 34 +/- 6 (mean +/- SD) and median mean blood pressure, esophageal temperature, and end-tidal carbon dioxide levels were 63 mmHg, 36.8 degrees C, and 32 mmHg, respectively. The average serum inorganic fluoride concentration 2 h after anesthesia was 66.2 +/- 14.7 microM. Results of tests of hepatic function and renal function (BUN, creatinine concentration) were unchanged after anesthesia. Glucose, protein, albumin, and NAG excretion were not significantly increased after anesthesia. Urine concentrations of alpha-GST and pi-GST were increased on day 1 after anesthesia and alpha-GST was increased on day 2 after anesthesia but returned to normal afterward. CONCLUSIONS: Prolonged (8 h), high concentration (3%) sevoflurane anesthesia administered to volunteers in a fresh gas flow of 2 l/min does not result in clinically significant changes in biochemical markers of renal or hepatic dysfunction.

Metabolic changes during recovery in normothermic versus hypothermic patients undergoing surgery and receiving general anesthesia and epidural local anesthetic agents.

Year 1998
Motamed S. Klubien K. Edwardes M. Mazza L. Carli F.
Department of Anesthesia, McGill University, Montreal, Quebec, Canada.
BACKGROUND: Mild hypothermia is accompanied by metabolic changes. Epidural local anesthetic agents attenuate the surgical stress response, but it is not known whether they modulate thermal stress. METHODS: Thirty patients undergoing colorectal surgery, performed by one surgical team, received epidural 0.5% bupivacaine to achieve T3-S5 sensory block. They were then assigned randomly to two groups of 15 patients each. The control or unwarmed group was left to cool during surgery, whereas active warming was used in the warmed group. General anesthesia was induced by thiopentone, vecuronium, fentanyl, nitrous oxide in oxygen, and enflurane. At the end of surgery, both groups received epidural 0.25% bupivacaine to maintain a T5-L3 sensory block. Aural canal (core) and skin surface (15 sites) temperatures; oxygen consumption; pain visual analogue score; and concentrations of epinephrine, norepinephrine, glucose, cortisol, lactate, and free fatty acids in plasma were measured before epidural blockade, 30 min after epidural blockade, at the end of surgery, and for 4 h after surgery. Patients and those measuring the outcomes were unaware of group allocation. RESULTS: Core and mean skin temperatures decreased significantly in the control group (P < 0.001) but not in the warmed group. Catecholamine concentrations in plasma decreased significantly after epidural block, and although concentration of epinephrine in plasma increased from baseline sharply in the control group at the end of surgery (P = 0.004), it decreased in the warmed group (P = 0.007). During recovery, there was no difference between the two groups for norepinephrine concentrations in plasma, body weight-adjusted oxygen consumption, pain visual analogue score, and metabolites. CONCLUSIONS: The postoperative metabolic changes obtained with epidural block were similar except for an attenuated concentration of epinephrine in normothermic patients compared with those who were mildly hypothermic.