Perineuronal morphine in intercostal block.

In a double-blind, randomised study the potential benefits of combining low-dose morphine with bupivacaine for intercostal nerve blocks for analgesia after biliary surgery were investigated. There was no significant improvement in pain scores or consumption of supplementary analgesics when morphine was added to bupivacaine. This investigation supports the findings of other workers who showed that perineural morphine was ineffective for postoperative pain relief.

Reported anaesthetic complications during an 11-year period. A retrospective study.

Retrospectively 120 anaesthetic complications with potential medicolegal consequences were reviewed. Seven deaths occurred. Eighty percent of the complications were potentially avoidable. Of the complications 4.4% resulted in major morbidity and 82.3% in intermediate morbidity. Dental injuries were reported with an annual frequency of six. The use of pulse oximetry and/or capnography could possibly have prevented 18% of all complications apart from dental injuries. Ten cases were reported to the National Swedish Board of Health and Welfare; four cases resulted in disciplinary consequences. The influence of human factors on the development of complications is stressed.

Anaesthesia for cardioversion--clinical experiences with propofol and thiopentone.

A 1-year population of anaesthesias for cardioversion of supraventricular tachyarrhythmias was studied. Propofol and thiopentone were used alternately for every other procedure, and the anaesthetic-, and monitoring procedures were prospectively standardized. Twenty-one thiopentone- and 23 propofol-anaesthetized patients, who had been subjected to elective cardioversions of atrial fibrillation were compared, particularly regarding possible differences in the energy requirements for cardioversion and in the time intervals to initial awakening. There were no significant differences between the two drugs in the maximum systolic blood pressure drop, in the total mean energy requirements per kg bodyweight, or in the distribution of the number of patients over the various energy levels needed for restoration of sinus rhythm. Somewhat unexpectedly, however, the mean time interval to initial awakening was significantly longer in the propofol-anaesthetized group. Apart from this minor drawback, propofol proved to be as useful an anaesthetic agent as thiopentone for the cardioversion procedure, and may be considered as an alternative drug in selected cases.

Premedication with intramuscular dixyrazine: (Esucos). A controlled double-blind comparison with morphine-scopolamine and placebo.

Ninety patients scheduled for general or orthopaedic surgical procedures were randomly assigned to receive one of three i.m. premedications: dixyrazine 0.5 mg kg-1; morphine 0.15 mg kg-1 and scopolamine 0.0065 mg kg-1; or placebo. The premedication was administered and evaluated in a double-blind fashion. The patients were anaesthetized with thiopentone, fentanyl, pancuronium, and ventilated with nitrous oxide in oxygen. The three premedications had no noticeable anxiolytic effect. Although there was no difference in the frequency of observed postoperative nausea and vomiting between the three groups, premedication with dixyrazine nonetheless reduced the patients' experience of postoperative nausea as well as their need for postoperative antiemetics. Although patients in the two treatment groups were significantly more sedated immediately before induction of anaesthesia than patients receiving placebo, the degree of postoperative sedation was similar in all three groups. Morphine-scopolamine caused more postoperative dizziness than dixyrazine and placebo. Lack of recall was produced by both morphine-scopolamine and dixyrazine. It is concluded that premedication with dixyrazine is a useful alternative, especially in patients who have previously experienced postoperative nausea and vomiting.

Propofol vs thiopentone as anaesthetic agents for short operative procedures.

In a randomized open study, 120 healthy female patients were included. For short gynaecological procedures they were anaesthetized with either propofol 2.5 mg X kg-1 (n = 60) or thiopentone 5 mg X kg-1 (n = 60) in combination with nitrous oxide/oxygen (67%/33%). Supplementary doses of propofol (10-20 mg) or thiopentone (25-50 mg) were given when necessary during the procedure. Induction characteristics for propofol and thiopentone 1 min after start of induction were similar. Propofol seemed to have a more depressant effect than thiopentone on the circulatory response to anaesthesia. Recovery times from the end of the operative procedure until the patients opened their eyes on command and were orientated were shorter in the propofol patients compared to the thiopentone patients. In the propofol group, patients recalled discomfort on injection more often than patients anaesthetized with thiopentone. Otherwise, the side-effects were similar in both groups. We conclude that propofol is similar to thiopentone in its anaesthetic qualities during induction and maintenance of short anaesthetic procedures. Propofol was associated with a more rapid emergence from anaesthesia than thiopentone.

Estimation of human fetal-placental unit metabolic rate by application of the Bohr principle.

The Bohr Principle via continuous indirect calorimetry was used to estimate human fetal-placental unit metabolic rate in 12 normal women undergoing elective caesarean section under continuous lumbar epidural anaesthesia. Maternal oxygen consumption decreased after umbilical cord clamping and after placental removal. Fetal-placental unit oxygen consumption was 10.7 +/- 1.3 ml/min per kg (mean +/- SEM). Fetal oxygen consumption was 6.8 +/- 1.4 ml/min per kg. Placental oxygen consumption was 37 +/- 12 ml/min per kg. Fetal-placental unit carbon dioxide production was 9.2 +/- 1.2 ml/min per kg. These mean values agree favourably with measurements of uterine and fetal metabolism from other mammalian species. Maternal minute ventilation decreased with removal of the fetal-placental unit, and this decrease was found to be linearly related to the fetal-placental unit carbon dioxide production.

Minute ventilation and oxygen consumption during labor with epidural analgesia.

Oxygen consumption (VO2) and minute ventilation (VE) were measured between and during uterine contractions in the first stage of labor before and after lumbar epidural analgesia (LEA) in 11 women who served as their own controls. VO2 and VE between contractions were essentially unchanged by LEA to a T10 or higher sensory level. Before LEA, both VO2 and VE were increased significantly during contractions by 63% and 74% respectively, whereas following LEA there was no significant increase in VO2 or VE during contractions. In the second stage of labor, VO2 and VE were measured in seven patients electing to have no analgesia or sedation and in 10 patients having complete pain relief produced by LEA. Measurements were obtained 5-10 min before delivery. During contractions with pushing, VO2 and VE were decreased by 25% and 31%, respectively, in patients having LEA as compared with patients having no analgesia or sedation. These results suggest that the increase in VO2 and VE are due primarily to pain associated with uterine contractions and that LEA decreased the work of breathing and the oxygen consumption of the parturient in both the first and second stages of labor.

Intraoperative fluid management influences carbon dioxide production and respiratory quotient.

The authors studied the effects of glucose-containing versus nonglucose-containing solutions for intraoperative fluid management on CO2 production and respiratory quotient (RQ) during the first postoperative hour. Three groups of patients were studied. Patients in Group 1 received normal saline during the operation and first postoperative hour; patients in Groups 2 and 3 received 5% glucose in half normal saline during the operation. This solution was continued through the postoperative period for patients in Group 2, while patients in Group 3 were given normal saline postoperatively. All patients received 500-1000 ml during the first hour and 500 ml/h thereafter. During the first postoperative hour, CO2 production and O2 consumption were measured every 15 min. RQ was significantly higher in Group 2 (0.93 +/- 0.01) than in Group 1 (0.77 +/- 0.01) (means +/- SEM, P less than 0.05). CO2 production was about 20% higher in Group 2 than in Group 1. There were no differences in O2 consumption between Groups 1 and 2. In Group 3, RQ decreased significantly (from 0.97 +/- 0.04 to 0.87 +/- 0.03) during the first postoperative hour but remained higher than in Group 1. The authors conclude that intraoperative administration of glucose-containing solutions increases RQ postoperatively; this effect can be reversed partially by changing to glucose-free solutions in the postanesthetic period.

Reduction of the cerebral protective effect of hypothermia by oligemic hypotension during hypoxia in the rat.

The effect of arterial hypotension on cerebral cortical tissue levels of adenosine triphosphate (ATP), phosphocreatine (PGr), lactate, and reduced nicotinamide adenine dinucleotide (NADH) was studied in male Wistar rats with unilateral carotid ligation exposed to arterial by hypoxia (PaO2 25 torr) for 20 min. while the body temperature was maintained at 32 degrees C and 27 degrees C. Brain metabolite levels were normal in normotensive hypothermic animals exposed to hypoxia, but reduction in arterial pressure to 75 torr caused a significant (p less than 0.05) decrease in ATP and PCr values and a significant increase in lactate and NADH levels. These changes were comparable to those of normothermic normotensive, hypoxic animals. Furthermore, there was no significant differences in the brain metabolite levels between the two hypotensive hypoxic groups. These results indicate that arterial hypotension severely alters the cerebral protective effect of hypothermia against injury caused by hypoxia, and that further reduction in body temperature (from 32 degrees C to 27 degrees C) will not prevent the harmful effect of hypoxia upon the brain in hypotensive rats.

Effect of high vs. low arterial blood oxygen content on cerebral energy metabolite levels during hypoxia with normothermia and hypothermia in the rat.

The effects of different levels of arterial blood oxygen content (CaO2) on brain tissue adenosine triphosphate (ATP), phosphocreatine (PCr), lactate, and reduced nicotinamide adenine dinucleotide (NADH) were studied during cerebral hypoxia in normothermic and hypothermic male Wistar rats with unilateral carotid ligation. Animals were exposed to hypoxia (PaO2 19--26 torr) for 25 min, and brain tissue metabolite values measured microfluorometrically were compared with those of normothermic normoxic controls. CaO2 was 4.0 +/- 0.2 ml/dl (mean +/- SEM) at PaO2 26 torr in normothermic animals. CaO2 was increased to 8.2 +/- 0.3 ml/dl at PaO2 26 torr by means of bicarbonate infusion producing a leftward shift of the oxyhemoglobin-dissociation curve in one normothermic hypoxic group. In all normothermic hypoxic groups ATP and PCr decreased and lactate and NADH increased significantly compared with control values. There was no significant difference in brain tissue metabolite values among these groups despite an increase in CaO2 by twofold in one group. Hypothermia (32 C) resulted in CaO2 8.4 +/- 0.2 ml/dl at PaO2 26 torr. This was decreased to 4.0 +/- 0.2 ml/dl by decreasing PaO2 to 19 torr in another group at the same temperature. ATP and PCr were well preserved in both groups despite the difference in CaO2s. Although the lactate and NADH levels were increased in the hypothermic group with CaO2 4.0 +/- 0.2 ml/dl, they were significantly lower than those values in normothermic hypoxic groups. These results indicate that the increase in CaO2 produced by hypothermia is not a major determinant in hypothermic protection during cerebral hypoxia.

Additive effects of hypothermia and phenobarbitol upon cerebral oxygen consumption in the rat.

The quantitative effects of a combination of hypothermia and phenobarbital on cerebral oxygen uptake (CMRo2) was studied in rats, curarized and artificially ventilated with 70% nitrous oxide in oxygen. Cerebral blood flow (CBF) was measured with a modification of the KETY & SCHMIDT (1948) technique, using 133xenon as a tracer. Arteriovenous difference in oxygen content over the brain was measured and CMRo2 was calculated. Four groups were studied. Group 1 was a control group. The three experimental groups were injected with phenobarbital intraperitoneally: Group 2 with 50 mg/kg body weight; Group 3 with 150 mg/kg; and Group 4 with 50 mg/kg of phenobarbital, and, in addition, body temperature was lowered to 32 degrees C in this group. CMRo2 in groups 2, 3 and 4 was reduced by 22, 37 and 43%, respectively, compared to Group 1. The changes in CBF were of the same magnitude. In a previous study we have found that CMRo2 decreases by 5% per 1 degree C decrease in body temperature. The value for CMRo2 in Group 4 is close to the value obtained if the effect of 50 mg/kg body weight of phenobarbital on CMRo2 is added to the effect of a temperature reduction of 5 degrees C. It is concluded that the effects of barbiturates and hypothermia on CMRo2 are additive.

Myocardial protection during heart surgery. An experimental evaluation of normothermic and hypothermic cardioplegia.

Heart surgery with hypothermic cardioplegia during normothermic bypass is sometimes complicated by rewarming of the myocardium caused by collateral flow of arterial blood. This problem is particularly evident in surgery of congenital malformations. The present work is a comparative study in dogs on 3 methods of avoiding the rewarming problem. In the first group, the heart was kept cold and the warm blood was drained off from the left atrium. In the second group, total body hypothermia to the level desired was used and in the third group, normothermic cardioplegia was induced (Cardioplegin) in normothermic animals. In the two latter groups, the undesired temperature gradient between heart and body was eliminated. Evaluation of the differences was made by means of ventricular function determinations. Local, hypothermic cardioplegia showed the best postoperative function (69%) followed by the total body cooling which was fully acceptable (41%). Normothermic cardioplegia after the same duration of arrest showed a too low myocardial performance (20%).

Circulatory and metabolic effects in the brain induced by amphetamine sulphate.

Cerebral circulatory and metabolic effects of amphetamine sulphate (0.25-25 mg.kg-1 i.v. or 5-10 mg.kg-1 i.p.) were studied in anesthetized, paralyzed and artifically ventilated rats. Cerebral blood flow (CBF) was measured with a modification of the Kety and Schmidt (1948) technique, and oxygen consumption (CMRO2) was calculated from CBF and arteriovenous differences in oxygen content. Regional CBF was evaluated from the uptake of 14C-ethanol. Cortical metabolites were analysed following freezing of tissue in situ. Amphetamine administration gave rise to a marked increase in CBF that was doubled following 0.25 mg.kg-1 and increased 4-fold following 15 mg.kg-1. However, such excessive increases in flow were confined to frontoparietal cortical regions, while other cortical or subcortical areas showed more moderate hyperemia. The increase in CBF was unrelated to changes in arterial PCO2, blood pressure, or tissue lactate content. CMRO2 increased by 30% to 95% depending on dose and rat strain used. At all doses employed, amphetamine gave rise to glycogenolysis in cerebral cortex but, in animals studied within the first 30 min after 5 mg.kg-1, or less, the only other changes were increases in glucose-6-phosphate and alpha-ketoglutarate concentrations. When the dose was increased to 15 mg.kg-1, there were moderate increased in lactate concentration and lactate/pyruvate ratio. Sixty min after 5 mg.kg-1 there were increases in tissue concentrations of pyruvate, citric acid cycle intermediates and alanine, as well.