Metabolic effects of anaesthesia: effect of thiopentone-nitrous oxide anaesthesia on human growth hormone and insulin levels in plasma

Cardiovascular, biochemical, and hormonal responses to intravenous sedation with local analgesia versus general anesthesia in patients undergoing oral surgery

The effects of intravenous conscious sedation and general anesthesia on a number of stress variables were compared in healthy patients undergoing oral surgery. In the intravenous sedation group only the levels of plasma growth hormone and prolactin rose significantly. In the general anesthesia group significant rises were seen in heart rate; systolic blood pressure; mean arterial pressure; levels of plasma adrenaline, adrenocorticotropic hormone, cortisol, and prolactin; and levels of blood glucose, all indicative of a stress response. This study demonstrates that oral surgery under intravenous conscious sedation with local analgesia is associated with less patient stress than is oral surgery under general anesthesia.

[Development of blood sugar and insulinemia in the first 12 postoperative hours. Effects of glucose and insulin intake]

Serum levels of glucose and insulin are studied during 12 hours in the early post-operative period after intra-abdominal surgery. Five groups of non diabetic patients are perfused with incremental doses of glucose, G. I: no glucose, G. II: 8,33 g . h-1 of glucose during 6 hours, G. III: 16,66 g . h-1 of glucose during 6 hours, G. IV: 16,66 g . h-1 of glucose with 20 mu insulin; G. V: 16,66 g . h-1 of glucose with 40 mu insulin. In all groups a significant rise in serum levels of glucose is observed (10,5-15,6 mmol . l-1). At the same time serum level of insulin remains unchanged except when insulin is infused. However exogenous insulin is unable to prevent the serum level of glucose to rise post-operatively.

Intravenous glucose tolerance test during anaesthesia in dogs: insulin response and glucose clearance

To evaluate the insulin response and the rates of disappearance of glucose from plasma during high spinal analgesia and various types of general anaesthesia, a series of intravenous glucose tolerance tests was performed in six dogs. Plasma glucose and insulin levels were measured during the intravenous glucose tolerance tests. Insulinogenic indices were calculated. The values obtained during anaesthesia were compared to those obtained during an unanaesthetized state. The insulinogenic index was increased significantly during high spinal analgesia and thiopentone infusion. Halothane and enflurane anaesthesia decreased the insulinogenic index significantly while Innovar-nitrous oxide also decreased it, but not significantly. These findings suggest that insulin secretion in response to hyperglycaemia is stimulated by spinal analgesia and thiopentone anaesthesia, depressed by halothane and enflurane anaesthesia and unchanged during neuroleptanesthesia. A diuresis was observed in the thiopentone anaesthetic and spinal analgesic groups as compared to the other general anaesthetic groups. Urinary losses of insulin and glucose paralleled urinary output; yet the greatest mean urinary loss of glucose did not exceed 4.5 per cent of the load of glucose administered. Accordingly, 95 per cent of the administered glucose remained within the body, presumably available for utilization.

Effect of anaesthesia and surgery on endocrine function in elderly patients

The effect of halothane-nitrous oxide anaesthesia and abdominal surgery on endocrine function was investigated in 18 elderly patients whose ages ranged from 65 to 77 (mean 69 years). Cortisol levels in plasma increased significantly during anaesthesia and surgery, and the increases were slightly higher than those in young adults. Plasma aldosterone increased and insulin levels did not change during the procedures, and these levels were lower than in younger adults. The endocrine responses in elderly patients were similar in magnitude to those in young adults. Therefore it appears that no special hormonal treatment is necessary for elderly patients undergoing routine surgical procedures.

Brain blood flow and metabolism after global ischemia and post-insult thiopental therapy in monkeys

We measured total and regional cerebral blood flow (CBF, rCBF) and cerebral metabolic rate (CMR) of oxygen (O2), glucose (G), and lactate (L) levels for 4 h after 16 min global brain ischemia in rhesus monkeys with and without post-insult thiopental therapy. Eleven monkeys weighing 4-5 kg anesthetized with 1 percent halothane, 66 percent nitrous oxide and 33 percent oxygen, were subjected to 16 min global brain ischemia by a combination of trimethaphan hypotension (to a mean arterial pressure of 50 torr) and a high pressure (1500 torr) neck tourniquet. Post-ischemia, 7 monkeys were untreated (controls) and 4 received thiopental 90 mg/kg infused intravenously over 60 min, beginning at 5 min post-ischemia. Total CBF and rCBF were measured by continuous monitoring of cerebral venous (torcula) and parietal-occipital (external scintillation) 133Xe activity, respectively, after intra-innominate artery injection of 500 micronCi 133Xe in saline. In control monkeys, hyperemia in rCBF, but not in total CBF was observed at 6-7 min post-ischemia, whereas both total CBF and rCBF increased in thiopental treated monkeys. The hyperemia in thiopental treated monkeys coincided with an increase in CMRG without a proportional increase in CMRO2 or lactate levels. Indeed, CMRO2 was depressed in the first 30 min post-ischemia. At 30 min post-ischemia, CMRO2 rose to twofold greater than pre-ischemia in control monkeys, but only to pre-ischemic levels in thiopental treated monkeys. The data suggest that thiopental therapy improves distribution of brain blood flow and brain glucose uptake early post-ischemia and depresses CMRO2 later post-ischemia.

Effect of isoflurane anaesthesia and surgery on carbohydrate metabolism and plasma cortisol levels in man

The present study was undertaken to investigate in nine male surgical patients the effects of isoflurane anaesthesia alone on the carbohydrate metabolism by determining plasma growth hormone (GH), insulin, blood glucose, and cortisol, and to compare them with the effects of anaesthesia associated with surgical operations. Determination of plasma GH, insulin, cortisol, and blood glucose were made simultaneously before induction of isoflurane anaesthesia, after maintenance of anaesthesia for 15 minutes and 30 minutes and during and after conclusion of the operation. Plasma GH concentrations showed a significant elevation during isoflurane anaesthesia, and maintained a similar high level one hour after the start of the operation. An insignificant elevation in plasma insulin level and significant increases in blood glucose were noted during anaesthesia and operation. Plasma cortisol levels increased insignificantly during anaesthesia, but increased markedly during operation. Our observations would suggest that the increased blood level of GH and elevated blood cortisol play a part in the increase of blood glucose during isoflurane anaesthesia and surgical operations in man.