[Anesthesia with sevoflurane vs propofol in elective extracavity surgery]. / Anestesia con sevoflurano vs propofol nella chirurgia d'elezione extracavitaria.

OBJECTIVE: To compare the cardiovascular effects and recovery characteristics of sevoflurane and propofol anesthesia in 80 ASA I and II patients undergoing elective extracavity surgery expected to last at least one hour. DESIGN: A prospective randomized clinical trial. METHODS: After meperidine and atropine premedication, the patients were randomly allocated into two groups: in the sevoflurane group thiopentone was administered for induction of anesthesia and sevoflurane for maintenance; the propofol group received propofol either for induction of anesthesia or maintenance. All patients received N2O, vecuronium, artificial ventilation and fentanyl as needed. Vital parameters were monitored during anesthesia and two hours later. Recovery times were recorded after anesthesia. Statistical analysis was performed with SAS (Statistical Analysis System). RESULTS: In the sevoflurane group, heart rate and diastolic pressure were slightly higher than in the propofol group. Recovery time was faster after sevoflurane anesthesia.

[Anesthesia with isoflurane in air and with isoflurane and nitrous oxide]. / Anestesia con isoflurano in aria e con isoflurano e protossido di azoto.

BACKGROUND: The aim of this study is to control the depth, the quality of recovery of total inhalation isoflurane anesthesia with or without nitrous oxide. DESIGN: Controlled comparative study was carried out on 51 patients, aged 40-54 yr, ASA 1, undergoing saphenectomy, in an University Clinic. METHODS: Induction: thiopental (3.5 mg kg), atracurium (0.6 mg kg) i.v. Patients were randomly assigned to: group 1 (26 patients), 5% isoflurane in air, by mask; group 2 (25 patients), 3% isoflurane and 60% N2O, by mask. Maintenance: group 1, 2% isoflurane in air; group 2, 1.2% isoflurane and 60% N2O. During anesthesia, consciousness and analgesia level were monitored by EEG Compressed Spectral Array, and clinical signs of pain by Evans' test; arousal time evaluation by "Time to correct response test". The subjective impressions, eventual dreams and recalls were collected using a standard set of questions one hour after the end of anesthesia and 24 hours later. One hour before anesthesia and two hours after the end of surgical procedures, a psychomotor performance recovery evaluation was performed using Zazzo's "deux barrages" test. DATA ANALYSIS: Student's "t" test. RESULTS: Adequate anesthetic depth was documented in all patients. Recovery time was statistically longer in isoflurane group (group 1 16.7 sd 2.2 minutes vs 10.3 sd 1.9 minutes group 2, p < 0.01). No patient reported recalls relative to anesthetic period. Two hours after recovery no significant differences in psychomotor performance tests were recorded. CONCLUSIONS: Isoflurane anesthesia in air, in adequate concentrations, provides a sufficient level of analgesia, hypnosis, amnesia, without clinical side effects.

[Effect of dopexamine in splanchnic perfusion during surgery of the abdominal aorta]. / Effetti della dopexamina nella perfusione splancnica in corso di intervento sull'aorta addominale.

Abdominal aortic surgery has significant effects on cardiac and splanchnic perfusion. The purpose of this study was to examine the effects of dopexamine, an inodilator drug, on hemodynamic and splanchnic perfusion with measurement of gastric intramucosal pH, by the method of gastric tonometry, during abdominal aneurysm resection. Twenty-five patients undergoing excision of an aortic abdominal aneurysm were randomly divided into two groups. During aortic cross-clamping Group II patients received dopexamine infusion, at a dose of 1 microgram/kg/m, and at a dose of 0.5 micrograms/kg/m from declamping to the end of the surgery. Whereas Group I patients did not receive a dopexamine infusion. During aortic cross-clamping the intramucosal pH value decreased in Group I patients, but did not change in Group II patients. Heart rate, cardiac index, and mixed venous oxygen saturation increased significantly during dopexamine infusion, whereas systemic vascular resistance was reduced. During aortic cross-clamping dopexamine was a useful agent in improving splanchnic blood flow, cardiac index venous saturation. Also, since the drug produces dose related hemodynamic changes of rapid onset and reversibility, it is possible to interrupt the infusion before aortic declamping to avoid the decrease in the intramucosal pH value.

Anesthetic induction with thiopental: its effect on scalp topography of median nerve somatosensory evoked potentials.

The effects on median nerve somatosensory evoked potentials (SEPs) of analgesic doses of fentanyl, meperidine or morphine and of sodium thiopental (STP) anesthesia (4 mg/kg) were tested in 36 surgical patients. We also explored changes in SEP components as a function of their scalp location. Before and after medication, responses were recorded from the scalp overlying the parietal cortex (ipsi- and contralateral to the stimulated arm) and the precentral (contralateral) cortex. None of the three opiates affected SEP latencies or amplitudes. The barbiturate increased the amplitudes of subcortical and early cortical components (N18, N20, P22, P25), whose latencies, however, were not significantly modified. The effect of STP on later SEP cortical components depended on their scalp topography: parietal N33 and P45 underwent significant changes in both latency and amplitude, whereas precentral N30 showed a significant amplitude increase only. Thiopental anesthesia produces clearer short-latency SEP recordings, from both parietal (components N20-P25) and precentral (P22, N30) areas.

Liver function following hypovolemic hypotension in rats anaesthetized with halothane or enflurane.

Rats which had approximately 25-30% of their calculated blood volume removed were exposed to halothane (1%) or enflurane (2%) in 33% oxygen for 30 min. Hepatic function was evaluated by determining, at various time intervals, serum activities of glutamic-oxalacetic and glutamic-pyruvic transaminase, acid phosphatase and gamma-glutamyl-transpeptidase. In this model serum enzyme activities and animal mortality were significantly increased when hypovolemic hypotension was induced during halothane anaesthesia. The same events did not occur in bleeding animals anaesthetized with enflurane. The marked disparity in hepatic dysfunction and mortality between halothane and enflurane-anaesthetized rats during hypovolemic hypotension may be explained by the more pronounced decrease of oxygen available for the liver and production of reductive toxic intermediates in animals exposed to halothane.

Stimulation of drug-metabolizing enzymes by nitrous oxide in the rat.

Wistar male rats were subchronically (150 h continuously) or chronically (5 h daily for 15 days) exposed to a 50% nitrous oxide/oxygen mixture. As an index of enzyme induction liver N-demethylase and benzo(a)pyrene-hydroxylase activities, serum gamma-glutamyltranspeptidase activity, urinary d-glucaric acid and pentobarbital sleeping time were evaluated in comparison with a control group. No effect was observed after subchronic exposure to the anaesthetic gas. Chronic exposure, on the contrary, decreased pentobarbital sleeping time, increased urinary d-glucaric acid, liver N-demethylase and serum gamma-glutamyltranspeptidase activities. No increase of liver benzo(a)pyrene-hydroxylase was observed. Chronic nitrous oxide exposure under appropriate conditions can modify some enzymes, metabolizing drugs and xenobiotic compounds.

Analgesic interaction between nitrous oxide and delta-9-tetrahydrocannabinol in the rat.

The analgesic activities of a 75:25% nitrous oxide-oxygen mixture administered for 15 min, of delta-9-tetrahydrocannabinol (THC) 10 mg kg-1 i.p., and of a combination of both, were evaluated in the rat by tail-flick and hot-plate tests. The nitrous oxide-oxygen mixture produced a significant increase in the pain threshold. The analgesic activity of THC was similar in extent but of longer duration than that of nitrous oxide. The cannabinoid also induced some locomotor and behavioural modifications. When both THC and the nitrous oxide-oxygen mixture were administered, a significant potentiation of the analgesic response was produced, without modification of the locomotor and behavioural responses that were induced by THC alone. Such mixtures may prove of value in the control of chronic pain in man.

Analgesic effect of aprotinin in the rat and its inhibition by naloxone.

Experiments were performed on rats using two analgesimetric tests (tail-flick; hot-plate) before and after injection i.v. of graded doses of aprotinin (12.5, 25.0 and 50 KIU g-1). A dose-related analgesic effect was noted with both tests. Prior administration of naloxone 0.001 mg g-1 i.p. inhibited the analgesic action.