Influence of moderate alcohol intake on thiopental anesthesia.

The relationship between alcohol intake over the week preceding anesthesia and various anesthetic parameters was examined in 119 women scheduled for termination of pregnancy under thiopental-nitrous oxide anesthesia. In terms of pure alcohol, the weekly intake was 1.03 +/- 1.09 ml.kg-1 (mean +/- s.d.), range 0-5.93, i.e. below average consumption in Denmark. Alcohol intake was negatively correlated with anesthetic sleeping time (P less than 0.01). Time and quality of anesthesia induction and frequency of anesthetic complications were not significantly correlated with the use of alcohol. Preanesthetic anxiety was not significantly correlated with any of the above data. Induction time and postoperative awareness were positively and sleeping time negatively correlated with age (P less than 0.05). The results indicate cross-tolerance between alcohol and thiopental, even when the regular intake of the former is low, and increasing thiopental requirements with increasing age.

Contribution of local blood flow regulation mechanisms to the maintenance of arterial pressure in upright position during epidural blockade.

The contribution of local blood flow regulation mechanisms to the maintenance of arterial pressure in upright position was studied in 5 normal subjects. Central sympathetic blockade was induced by epidural anesthesia. Blood flow in anterior tibial muscle in both legs and in brachioradial muscle in one arm was measured by the local 133Xe washout technique. Arterial blood pressure was recorded directly from the radial artery. Slow head-up tilt (about 30 degrees) caused a decrease in blood flow of about 36% in the dependent legs and in arm remaining at heart level. Arterial pressure decreased by about 10%. Blockade of the local sympathetic veno-arteriolar "axon reflex" in one leg by injection of phentolamine into the common femoral artery caused a vasodilatation in the ipsilateral muscle, while muscle blood flow did not change in the other leg or arm. Within 20 s after the injection of phentolamine arterial pressure decreased by about 7%. This cannot be explained by a "systemic" effect because injection of phentolamine into the femoral vein did not effect arterial pressure within the first 40 s. Vasoconstriction due to blood-borne factors is ruled out since preventing the increase in vascular transmural pressure in the leg by inducing counterpressure locally, abolished the vasoconstriction. Thus, the results suggest that the local veno-arteriolar "axon reflex" together with myogenic mechanisms contribute to the maintenance of arterial pressure in the upright position.

Effect of spinal sympathetic blockade upon postural changes of blood flow in human peripheral tissues.

The effect of head-up tilt upon subcutaneous and skeletal muscle blood flow in the crus was studied before and during epidural blockade in 10 subjects. Relative changes in blood flow were estimated by the local 133Xe washout technique. In subcutaneous tissue head-up tilt induced a decrease in blood flow of about 40% and there was no difference in the vascular response to head-up tilt before and during epidural blockade. In skeletal muscle tissue essentially the same was found as head-up tilt decreased blood flow by about 26% the response being uninfluenced by epidural blockade. In 3 patients local nervous blockade was induced by Lidocaine in 133Xe labelled subcutaneous tissue on one side. During epidural blockade and tilt blood flow increased by 12% whereas blood flow decreased by 30% on the control side. Thus epidural blockade had no influence on the vasoconstrictor response in subcutaneous tissue and skeletal muscle to head-up tilt whereas local blockade was able to prevent the response. Local mechanisms including the local veno-arteriolar reflex appear to play an important role for the observed maintenance of arterial blood pressure in the tilted position during central sympathetic blockade.

Anaesthesia for colonoscopy. An examination of the anaesthesia as an element of risk at colonoscopy.

The importance of anaesthesia as an element of risk at colonoscopy has been examined retrospectively over a 10-year period from 1975 to 1984. The colonoscopic examinations were made by surgical gastroenterologists and anaesthesiologists working in cooperation. In 1242 cases the patients received diazepam/fentanyl anaesthesia during the colonoscopy (Group I) and in 126 cases they received general anaesthesia (Group II). The incidence of perforations of the large bowel in Group I was 0.8% (95% confidence limits: 0.4-1.5%) and in Group II 0.0% (95% confidence limits: 0.0-2.9%). Statistically the difference is not significant (P = 0.38). The groups were comparable with a view to the patients' age, weight, the duration of the colonoscopy and the number of times that polypectomy had been performed. All anaesthesia was administered by staff qualified by training and experience to administer anaesthesia, and did not cause any complications. However, four patients had vasovagal reflexes due to manipulation of the colonoscope. The dosing in the patients in Group I averaged: diazepam as premedication 9.2 mg, intravenous diazepam 12.4 mg, intravenous fentanyl 0.14 mg, and the duration of the colonoscopy was 36.5 min. The medication and the duration of the colonoscopy did not vary significantly in the patients with perforation of the large bowel. Our conclusion is that diazepam/fentanyl anaesthesia, administered by experienced staff, is harmless, and that general anaesthesia for colonoscopy did not involve an increased risk of perforation of the large bowel.

Immediate and long-term mental recovery from general versus epidural anesthesia in elderly patients.

The postoperative course of mental performance during the first week and at 3 months after operation was studied in 30 patients above the age of 60, undergoing total hip replacement arthroplasty. The patients were randomly allocated to receive either general anesthesia, epidural analgesia, or general anesthesia plus epidural analgesia. The surgically induced increase in plasma cortisol and glucose was inhibited in the two groups receiving epidural analgesia. Mental performance was studied with psychological methods. An equal degree of postoperative impairment of mental performance of 3-4 days' duration was found in all groups. Three months after surgery, mental function had improved slightly and to the same extent in all groups. We conclude that the after surgery, mental function had improved slightly and to the same extent in all groups. We conclude that the transient mental impairment occurring within the first postoperative week is caused by factors other than general anesthetic agents and the endocrine-metabolic response to surgery.

Induction and recovery characteristics of propofol, thiopental and etomidate.

Propofol, thiopental and etomidate, with 20 patients in each group, were compared for anesthesia of short duration in women undergoing termination of pregnancy, with respect to: 1: pain on injection (equally often after propofol and etomidate, but more rarely after thiopental); 2: apnea following induction (no difference); 3: involuntary muscular movements more frequent after etomidate); 4: blood pressure (larger drop after propofol); 5: heart rate (greater increase after thiopental); 6: time to eye opening on command (longer after propofol); 7: Steward score on eye opening (no difference); 8: coin counting after 15, 30 and 60 min (performance better after propofol at 15 and 30 min, producing even shorter times than preoperatively at 60 min); 9: reaction time after 15, 30 and 60 min (performance better after propofol, producing even shorter times than preoperatively at 60 min. It is concluded that the faster recovery gives propofol an advantage over thiopental and etomidate in outpatient anesthesia.

Comparison of induction with and first hour of recovery from brief propofol and methohexital anesthesia.

Anesthesia and recovery during the first hour after propofol and methohexital anesthesia for termination of pregnancy, lasting about 12 min, were compared, the latter in a double-blind manner by means of psychomotor tests (coin counting and continuous auditory reaction time). Muscle movements and hiccups were seen significantly more frequently during methohexital inductions. No differences were seen regarding pain at the site of injection or apnea between the groups. At 15 min after the last dose of anesthetic, recovery after methohexital was ahead of that after propofol, but after 1 h, psychomotor performance was better in the propofol group. Side-effects during recovery were few, and incidences did not differ significantly. Although the difference in reaction time test was significant, it was hardly large enough to be of any clinical importance. Both drugs are useful for brief outpatient anesthesia, but smoother induction gives propofol an edge over methohexital.