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Biomedical subjects

G M Hall

Publications and source records attributed to G M Hall.

At least 109 records · Page 6Linked to original sources
PubMed1991

Delayed recovery of muscle pH after short duration, high intensity exercise in malignant hyperthermia susceptible subjects.

Six subjects susceptible to malignant hyperthermia (MHS) and seven control subjects exercised for 4 min at 120% of their calculated maximal oxygen uptake on a bicycle ergometer. Mean (SEM) muscle pH, measured with a needle-tipped electrode in the vastus lateralis muscle, decreased from a resting value of 7.16 (0.04) to 6.78 (0.04) after exercise in the control group, and from 7.15 (0.05) to 6.56 (0.05) in the MHS group (P less than 0.01 compared with control group). A further decrease in muscle pH to 6.68 (0.06) by 5 min after exercise occurred in the control group, followed by incomplete recovery to 7.06 (0.04) 30 min after exercise. In the MHS group, however, muscle pH decreased to 6.45 (0.05) 5 min after exercise before recovering slowly to only 6.64 (0.07) after 30 min (P less than 0.01 compared with control group). There was no difference in muscle temperature, venous pH or venous lactate concentrations between the two groups. The results show that there is abnormal recovery of muscle pH after short-duration, high-intensity exercise in MHS subjects.

Adult↗
PubMed1991

Midazolam modifies pancreatic and anterior pituitary hormone secretion during upper abdominal surgery.

We have investigated the effects of midazolam on circulating concentrations of pituitary and pancreatic hormones in eight healthy patients during cholecystectomy and compared the changes with those in a control group of eight patients. Anaesthesia was induced either with midazolam 0.42 mg kg-1 i.v. followed by an infusion of midazolam 0.125 mg kg-1 for 1 h, or with a sleep dose of thiopentone. All patients received vecuronium, and the lungs were ventilated with 0.5-1.0% halothane and 70% nitrous oxide in oxygen. The use of midazolam was associated with a significant decrease (P less than 0.05) in secretion of cortisol and insulin during surgery. Serum growth hormone secretion was augmented, but this did not reach statistical significance. There was little difference in the concentrations of circulating metabolites between the two groups, except for a significant decrease in blood glucose (P less than 0.05) in the midazolam group after 60 min. There were no marked differences in cardiovascular variables between the two groups of patients.

Adult↗
PubMed1991

A comparison of patient rewarming devices after cardiac surgery.

Three regimens for rewarming patients after cardiac surgery involving hypothermic cardiopulmonary bypass were studied in 30 patients. The control group (n = 10) received no active rewarming, the oesophageal group (n = 10) was warmed centrally using an oesophageal heat exchanger and the radiant group (n = 10) was warmed peripherally with an overhead radiant heater. There were no statistically significant differences between the groups apart from the higher mean skin temperatures in the peripheral group.

Body Temperature↗
PubMed1991

Plasma catecholamine response to cataract surgery: a comparison between general and local anaesthesia.

We studied the plasma catecholamine, plasma glucose and cardiovascular responses to cataract surgery in 20 elderly patients allocated randomly to receive either general anaesthesia or local anaesthesia by retrobulbar block. Local anaesthesia prevented the increase in plasma noradrenaline, adrenaline and glucose concentrations found in those patients who received general anaesthesia and also improved cardiovascular stability. The results show the beneficial effects of local anaesthesia in preventing the hormonal, metabolic and cardiovascular changes found when cataract surgery is conducted under general anaesthesia.

Aged↗
PubMed1991

Effects of epidural diamorphine on the somatosensory evoked potential to posterior tibial nerve stimulation.

We have studied the effects of the epidural administration of diamorphine 0.1 mg/kg at the L3-4 interspace on somatosensory evoked potentials in the cervical epidural space before corrective surgery for idiopathic adolescent scoliosis. A further eight patients in whom anaesthesia was maintained with a propofol infusion acted as a control group. Epidural diamorphine had no effect on the latency or amplitude of the evoked potentials. We conclude that epidural diamorphine is a suitable technique to use in scoliosis surgery because of its lack of effect on neurophysiological variables, although the potential respiratory problems need investigation.

Adult↗
PubMed1990

The hormonal responses to repetitive brief maximal exercise in humans.

The responses of nine men and nine women to brief repetitive maximal exercise have been studied. The exercise involved a 6-s sprint on a non-motorised treadmill repeated 10 times with 30 s recovery between each sprint. The total work done during the ten sprints was 37,693 +/- 3,956 J by the men and 26,555 +/- 4,589 J by the women (M greater than F, P less than 0.01). This difference in performance was not associated with higher blood lactate concentrations in the men (13.96 +/- 1.70 mmol.l-1) than the women (13.09 +/- 3.04 mmol.l-1). An 18-fold increase in plasma adrenaline (AD) occurred with the peak concentration observed after five sprints. The peak AD concentration in the men was larger than that seen in the women (9.2 +/- 7.3 and 3.7 +/- 2.4 nmol.l-1 respectively, P less than 0.05). The maximum noradrenaline (NA) concentration occurred after ten sprints in the men (31.6 +/- 10.9 nmol.l-1) and after five sprints in the women (27.4 +/- 20.8 nmol.l-1). Plasma cardiodilatin (CDN) and atrial natriuretic peptide (ANP) concentrations were elevated in response to the exercise. The peak ANP concentration occurred immediately post-exercise and the response of the women (10.8 +/- 4.5 pmol.l-1) was greater than that of the men (5.1 +/- 2.6 pmol.l-1, P less than 0.05). The peak CDN concentrations were 163 +/- 61 pmol.l-1 for the women and 135 +/- 61 pmol.l-1 for the men. No increases in calcitonin gene related peptide (CGRP) were detected in response to the exercise. These results indicate differences between men and women in performance and hormonal responses. There was no evidence for a role of CGRP in the control of the cardiovascular system after brief intermittent maximal exercise.

Adult↗
PubMed1990

Monoarthritis of the ankle in diabetes mellitus without neuropathy: a report of three cases.

Diabetes mellitus is associated with several non articular rheumatic conditions and is a cause of Charcot's arthropathy. We report three cases of long-standing insulin-dependent diabetics who developed an inflammatory monoarthritis of the ankle. There was no evidence of a peripheral neuropathy or sepsis. They were all seronegative for rheumatoid factor. In two the synovitis persisted; in the third there was a gradual resolution. This type of inflammatory synovitis has not been previously described in diabetes. It developed after a mean duration of diabetes of 34.3 years (range 18-52 years). We suggest that it may be associated with microvascular changes in diabetes, possibly involving hypoxic reperfusion.

Aged↗
PubMed1990

Continuous intramuscular pH measurement during the recovery from brief, maximal exercise in man.

Muscle pH and temperature were measured before, and continuously for 30 min after, a 30-s maximal sprint exercise in ten subjects. These measurements were made with a needle-tipped pH electrode and a thermocouple placed in vastus lateralis. Venous blood samples were collected for pH, lactate and catecholamine estimations and measurements were also made of the arterial blood pressure and heart rate. The muscle and venous pH decreased from 7.17 +/- 0.01 (mean +/- SEM) and 7.39 +/- 0.01 to 6.57 +/- 0.04 and 7.04 +/- 0.03, respectively, in response to the exercise. No significant recovery occurred in either pH measurement for 10 min, after which muscle pH increased to 7.03 +/- 0.03 and venous pH to 7.29 +/- 0.01 by 30 min. Muscle temperature increased by 2.1 degrees C with exercise and also failed to return to pre-exercise values by 30 min. Blood lactate concentration increased from 0.75 +/- 0.04 mmol l-1 before exercise to a peak value of 15.76 +/- 0.35 mmol l-1 5 min after completion of the exercise, and then declined slowly to 10.30 +/- 0.61 mmol l-1 by 30 min. Arterial blood pressure increased transiently with exercise but recovered rapidly, whereas the exercise-induced tachycardia was sustained throughout the recovery period. The recovery from the metabolic and cardiovascular responses to maximal sprint exercise in man is incomplete 30 min after cessation of the exercise.

Adult↗
PubMed1990

Local analgesia prevents the cortisol and glycaemic responses to cataract surgery.

We studied the metabolic and hormonal responses to cataract surgery in 18 elderly patients, allocated randomly to receive either general anaesthesia or local analgesia by means of a retrobulbar block. Local analgesia prevented the increases in circulating cortisol and glucose concentrations found in those patients who received general anaesthesia. The results show that complete afferent sensory block of the operative site inhibited endocrine and metabolic responses to ophthalmic surgery.

Aged↗
PubMed1990

Hormonal responses to cardiac surgery: effects of sufentanil, somatostatin and ganglion block.

We have investigated the effect of the addition of somatostatin and trimetaphan to sufentanil 20 micrograms kg-1 on the hormonal responses to cardiac surgery and compared the changes with a control group receiving sufentanil and sodium nitroprusside. Eighteen patients undergoing elective valve replacement surgery were studied. Patients who received somatostatin and trimetaphan in addition to sufentanil had significantly smaller serum growth hormone and plasma glucagon concentrations compared with those who received sufentanil and sodium nitroprusside. The cortisol response to surgery was inhibited in both groups. There were no significant differences in catecholamine concentrations between the two groups. There was no effect of the additional inhibition of glucagon and growth hormone on circulating concentrations of glucose and lactate, but plasma concentrations of non-esterified fatty acids increased significantly. Thus the addition of somatostatin increased the suppression of the hormonal response to cardiac surgery by sufentanil.

Aged↗
PubMed1990

Site of action of fentanyl in inhibiting the pituitary-adrenal response to surgery in man.

To determine the site of action of fentanyl in attenuating the pituitary-adrenal response to surgery, we have measured serum concentrations of cortisol and growth hormone during and after a standardized surgical procedure in two groups of patients. One group received fentanyl 15 micrograms kg-1 i.v. immediately before the start of surgery; a second group received fentanyl 15 micrograms kg-1 i.v. together with corticotrophin releasing factor 100 micrograms i.v., growth hormone releasing hormone 100 micrograms i.v. and arginine vasopressin 10 units i.m. The concomitant administration of the releasing factors with the opioid resulted in a significantly greater serum concentration of cortisol 30, 60, 120 and 240 min after surgery commenced, compared with the group which received fentanyl alone. Similarly, the growth hormone response in the combined group was significantly greater than in the fentanyl-alone group 30 min after the start of surgery. We conclude that the inhibitory effect of fentanyl on surgically-induced secretion of pituitary hormone was mediated directly or indirectly via the hypothalamus.

Arginine Vasopressin↗
PubMed1990

Effects of 2% lignocaine on somatosensory evoked potentials recorded in the extradural space.

We have studied the effects of extradural administration of 2% lignocaine at the L3-4 interspace on somatosensory evoked potentials recorded in the cervical extradural space before corrective surgery for idiopathic adolescent scoliosis. Eight patients in whom the equivalent volume of 0.9% sodium chloride solution was administered into the lumbar extradural space acted as a control group. Lignocaine 2% resulted in a decrease in overall amplitude, but its main effect was a significant decrease in the amplitude of the second and third peaks, suggesting an action on the dorsal columns of the spinal cord. A significant increase in latency was found in both the lignocaine and sodium chloride groups. We conclude that the use of extradural 2% lignocaine in patients undergoing scoliosis surgery may interfere with the intraoperative monitoring of somatosensory evoked potentials.

Adolescent↗
PubMed1989

Effects of halothane on somatosensory evoked potentials recorded in the extradural space.

We studied the effects of supplementing anaesthesia with halothane (up to 1.5%, inspired) on the somatosensory evoked potential recorded in the extradural space of six patients before corrective surgery for idiopathic adolescent scoliosis. A further six patients in whom anaesthesia was supplemented with thiopentone acted as a control group. Halothane 1.5% resulted in a significant decrease in overall amplitude (P less than 0.05) from the left leg only. Halothane had no significant effect on overall amplitude, first peak amplitude, second peak amplitude and first peak latency. We conclude that halothane is unlikely to alter the interpretation of somatosensory evoked potentials recorded extradurally during scoliosis surgery. A possible unilateral effect of halothane on the concave side in idiopathic adolescent scoliosis needs further investigation.

Adolescent↗
PubMed1989

Hormonal and metabolic responses to cholecystectomy: comparison of extradural somatostatin and diamorphine.

We have studied the metabolic and hormonal responses to surgery, and the pain scores and analgesic requirements in 24 patients undergoing cholecystectomy, allocated randomly to three groups to receive either general anaesthesia alone, or general anaesthesia with extradural diamorphine 0.1 mg kg-1, or general anaesthesia with extradural somatostatin to a total dose of somatostatin 3 mg. The only significant effect of extradural diamorphine was a decrease in the glucose response to surgery. Somatostatin 3 mg by the extradural route caused a significant increase in the concentration of circulating somatostatin which resulted in a significant decrease in plasma growth hormone and insulin after 60 min of surgery, together with an increase in plasma glycerol concentration. Patients in the diamorphine group required significantly less i.v. analgesia in the postoperative period than the other two groups. Intraoperative somatostatin failed to provide any postoperative analgesia.

Adult↗
PubMed1989

Effects of halothane on motor evoked potential recorded in the extradural space.

We studied the effects of supplementing nitrous oxide-oxygen anaesthesia with halothane (1 MAC end-tidal concentration) on the motor evoked potential recorded in the extradural space of eight patients before corrective surgery for idiopathic adolescent scoliosis. The motor cortex was stimulated electrically through the scalp. An additional eight patients in whom anaesthesia was supplemented with an infusion of propofol acted as a control group. Halothane had no significant effect on the amplitude or latency of the motor evoked potential. We conclude that halothane is unlikely to alter the interpretation of motor evoked potentials recorded extradurally during scoliosis surgery.

Adolescent↗