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T Gin

Publications and source records attributed to T Gin.

At least 73 records · Page 4Linked to original sources
PubMed1994

Decreased minimum alveolar concentration of isoflurane in pregnant humans.

BACKGROUND: Minimum alveolar concentration (MAC) is decreased in pregnant animals, but this change has not been demonstrated in humans, probably because of ethical considerations. It is less problematic to determine MAC in pregnant women undergoing termination of pregnancy, however, and therefore we compared the MAC of isoflurane in these women with the MAC in matched nonpregnant women. METHODS: Patients underwent inhalational induction of anesthesia with isoflurane and tracheal intubation. MAC was determined in each patient by testing the response to a 10-s, 50-Hz, 80-mA transcutaneous tetanic electrical stimulus to the ulnar nerve at varying concentrations of isoflurane. The end-tidal concentration of isoflurane was kept constant for 10 min before each stimulus and the concentration of isoflurane ultimately varied in steps of 0.05% until we obtained a sequence of three alternate responses (move, not move, move) or (not move, move, not move). MAC for each patient was taken as the mean of the two concentrations just permitting and just preventing movement. MAC for the group was taken as the median of the individual MAC values. A blood sample was taken immediately before induction of anesthesia for measurement of progesterone concentrations. Data were compared between groups by the Mann-Whitney test. RESULTS: The median (range) MAC for isoflurane in the pregnant group, 0.775% (0.675-0.825), was less than that in the nonpregnant group, 1.075% (1.025-1.175) (P < 0.001). The median (range) plasma progesterone concentration in the pregnant group, 63.4 (0.8-106) nM, was greater than that in the nonpregnant group, 8.4 (0.7-66) nM (P < 0.02). CONCLUSIONS: The MAC of isoflurane was reduced by 28% in pregnant women at 8-12 weeks' gestation compared with that of nonpregnant controls.

Anesthesia, Inhalation↗
PubMed1994

Midazolam and flumazenil pharmacokinetics and pharmacodynamics following simultaneous administration to human volunteers.

Resedation after antagonism of midazolam sedation with flumazenil may occur because some individuals have rapid elimination of flumazenil but slow elimination of midazolam. To determine whether there are parallel or divergent rates of elimination of the two drugs between individuals, the pharmacokinetic profiles of midazolam and flumazenil were studied simultaneously in 12 adult male volunteers. Free drug concentration data for the two drugs were incorporated into a receptor occupancy model and psychomotor testing was performed and correlated with receptor occupancy. Variation was found between individuals in the pharmacokinetics of the two drugs. There were significant correlations between Cltot (P < 0.01) but not in t1/2 alpha, t1/2 beta, Vc, or VDss. In individuals, midazolam elimination half-life ranged from less than half that of flumazenil to more than three times that of flumazenil. There was a relatively poor, although statistically significant linear correlation found between calculated receptor occupancy and critical flicker fusion frequency, r = 0.50, P < 0.01, and linear analogue scales of sedation r = 0.56, P < 0.005; and anxiolysis, r = 0.54, P < 0.005. There is divergence in the disposition and elimination of midazolam and flumazenil in some individuals. A benzodiazepine receptor occupancy model is useful for predicting the consequent differences in clinical effect when the drugs are given together.

Adult↗
PubMed1994

Recent advances in the understanding and management of postoperative nausea and vomiting.

Postoperative nausea and vomiting (PONV) is a common distressing complication of surgery and anaesthesia. The multifactorial aetiology of PONV gives rise to an incidence that varies widely among different patient groups. PONV is unpleasant for the patient, may be associated with medical complications and can increase hospital costs. One cannot usually modify the patient or surgical factors associated with an increase in PONV, but the choice of anaesthetic technique can alter the incidence of PONV. Current research is concentrated on a new class of drugs, the serotonin (5-HT3) receptor antagonists. This review summarizes the experience with these drugs and other recent advances in PONV.

Antiemetics↗
PubMed1994

Propofol during pregnancy.

Propofol has been used for the induction and maintenance of general anesthesia during pregnancy although this is not an indication approved by Zeneca Pharmaceuticals. Compared with thiopentone, propofol reduces the cardiovascular response to laryngoscopy and tracheal intubation. Maternal recovery from anesthesia may be marginally quicker. Neonatal outcome is satisfactory although one group of researchers has consistently preferred thiopentone to propofol. Compared with inhalational agents, infusions of propofol do not offer any significant advantages for the maintenance of anesthesia and the risk of neonatal depression is potentially greater. Although propofol has no major advantages to justify it replacing thiopentone for the induction of anesthesia in pregnancy, propofol does give satisfactory results and should be available as an alternative.

Anesthesia, Intravenous↗
PubMed1993

Severe pulmonary oedema after venous air embolism.

We present a 59-yr-old Chinese male patient who developed acute pulmonary oedema and cardiovascular collapse following multiple episodes of venous air emboli while in the sitting position for removal of a cervical meningioma. The severity of the pulmonary oedema and cardiovascular disturbance were surprising. Postoperative ventilation and inotropic support were required and five litres of plasma were needed to replace the fluid lost as pulmonary oedema. We discuss the differential diagnosis of the pulmonary changes and review current ideas on the pathogenesis for pulmonary oedema following venous air embolism.

Carbon Dioxide↗
PubMed1993

Gastric pH and volume after oral fluids in the postpartum patient.

The aim of this study was to investigate the relationship between preoperative oral fluids and gastric pH and volume in women undergoing sterilization between one and five days postpartum. Fifty postpartum patients received 150 ml water approximately two to three hours before surgery while 50 postpartum and 50 non-pregnant women were fasted from midnight. After induction of anaesthesia, gastric contents were aspirated using a Salem sump tube and the gastric pH and volume were measured. There were no differences in intragastric pH and volume, median (range), among the postpartum fasted group, 1.19 (0.74-4.57), 22 (1-78) ml, postpartum water group 1.18 (0.70-6.4), 25.5 (3-66) ml and the non-pregnant group 1.27 (0.51-6.63), 25 (3-69) ml. There was no correlation between postpartum interval, 60 (12-120) hr, and intragastric pH or volume. It is concluded that oral water may be given safely two to three hours preoperatively to patients more than one day postpartum. Intragastric volume and acidity were not increased and the findings in postpartum patients were similar to those found in non-pregnant patients.

Adult↗
PubMed1993

Effect of respiratory acidosis and alkalosis on plasma catecholamine concentrations in anaesthetized man.

1. Plasma concentrations of noradrenaline and adrenaline were measured in 11 anaesthetized patients during normocapnia, hypocapnia and hypercapnia. Hypocapnia was produced by deliberate hyperventilation and hypercapnia by adding carbon dioxide to the inspired gas mixture. 2. With a median (range) arterial partial pressure of carbon dioxide of 4.7 (4.2-5.2) kPa, the median (range) plasma concentration of noradrenaline was 0.41 (0.12-0.94) nmol/l and of adrenaline was 0.15 (0.05-0.31) nmol/l. 3. With an arterial partial pressure of carbon dioxide of 2.6 (2.2-3.3) kPa, there was no change in the plasma concentration of noradrenaline [0.37 (0.12-0.86) nmol/l] or that of adrenaline [0.16 (0.05-0.32) nmol/l]. 4. However, with an arterial partial pressure of carbon dioxide of 10.4 (7.6-13.2) kPa, there were significant increases in the plasma concentrations of both noradrenaline [1.13 (0.79-2.05) nmol/l, P < 0.01] and adrenaline [0.67 (0.20-2.92) nmol/l, P < 0.05]. 5. This is the first demonstration in man that respiratory acidosis causes an increase in plasma concentrations of catecholamines.

Adult↗
PubMed1993

Plasma catecholamines and neonatal condition after induction of anaesthesia with propofol or thiopentone at caesarean section.

Increased maternal sympathetic nervous system activity may decrease placental perfusion and cause adverse neonatal effects. We have studied the catecholamine response and neonatal outcome in Chinese patients with uncomplicated, singleton pregnancies undergoing Caesarean section. Anaesthesia was induced with thiopentone 4 mg kg-1 (n = 32) or propofol 2 mg kg-1 (n = 30) followed by suxamethonium. Laryngoscopy was performed after 1 min and tracheal intubation completed by 2 min. Anaesthesia was continued with atracurium, nitrous oxide and isoflurane. Maternal venous blood samples were taken at 0, 1, 2, 3, 4 min and at delivery for assay of catecholamines. The increase from baseline values in mean arterial pressure after tracheal intubation was greater in the thiopentone group (29 (SD 15) mm Hg) compared with the propofol group (18 (14) mm Hg) (P < 0.01). The concentrations of noradrenaline and adrenaline increased in both groups after tracheal intubation. Maximum noradrenaline concentrations were greater in the thiopentone group (413 (177) pg ml-1) compared with the propofol group (333 (108) pg ml-1) (P < 0.05), but there were no differences between groups in adrenaline concentrations. Neonatal Apgar scores, neurobehavioural testing and umbilical catecholamine, blood-gas tension and oxygen content analysis were similar between groups. Propofol attenuated the hypertensive and catecholamine response associated with laryngoscopy and tracheal intubation but there was no improvement in neonatal outcome.

Adult↗
PubMed1993

Haemodynamic changes in patients undergoing laparoscopic cholecystectomy: measurement by transthoracic electrical bioimpedance.

Using transthoracic electrical bioimpedance with the BoMed NCCOM3-R7, we measured cardiovascular changes in 16 ASA I and II Chinese patients undergoing laparoscopic cholecystectomy. The peritoneal cavity was insufflated with carbon dioxide to a pressure up to 15 mm Hg. Tidal volume, minute volume and end-tidal carbon dioxide partial pressure were kept constant. Insufflation resulted in a mean (SD) 13 (14)% decrease in stroke index (SI) (P < 0.01), but the effect on cardiac index (CI) was more variable (mean 7 (17)% decrease, range 36% decrease to 22% increase (P = 0.07)). Mean arterial pressure increased by 55 (29)% (P < 0.001) and systemic vascular resistance index increased by 63 (33)% (P < 0.001), with the maximum effect occurring 10-15 min after the commencement of insufflation. Multiple regression analysis showed a greater decrease in SI in patients with a small body mass index and large intraperitoneal pressure (P = 0.01), while a greater decrease in CI was found in patients with a small body mass index and younger age (P = 0.001). Three patients had a further reduction in CI during surgery, with one patient having a 48% decrease compared with pre-induction values. Deflation of the peritoneum resulted in an increase in both CI (25 (26)%) and (22 (29)%) (P < 0.01) to values which were not different from pre-induction data. Arterial blood-gas analysis showed decreases in pH and base excess after 1 h of insufflation (P < 0.01).

Adult↗
PubMed1993

Comparison of 0.125% bupivacaine with 0.125% bupivacaine and clonidine as extradural analgesia in the first stage of labour.

We have studied 42 healthy parturients with singleton vertex pregnancies, who were in the first stage of labour and requesting extradural analgesia. They were allocated randomly in a double-blind fashion to receive either 0.125% bupivacaine plain or 0.125% bupivacaine with clonidine 120 micrograms. Efficacy of analgesia was evaluated using linear visual analogue scoring (VAS), sensory block was assessed using bilateral pinprick in the mid-clavicular line and sedation scored on a five-point scale. Maternal and fetal cardiovascular variables were measured every 2 min for 20 min, at 30 min and subsequently at 15-min intervals. The reduction in VAS was greater at all times in the bupivacaine-clonidine group (P < 0.01). The median (range) duration of analgesia was greater in the bupivacaine-clonidine group (114.5 (30-243) min) compared with the bupivacaine group (53 (30-100) min) (P < 0.001). Analgesia was associated with a reduction in arterial pressure in both groups, but there were no between-group differences. Maternal heart rate was less than baseline values at 30-90 min in the bupivacaine-clonidine group only. Sedation was greater in the bupivacaine-clonidine group, especially from 15 to 45 min (P < 0.01). There were no differences in fetal heart rate, mode of delivery or Apgar scores between the two groups.

Adolescent↗
PubMed1993

Suxamethonium myalgia: an ethnic comparison with and without pancuronium pretreatment.

The incidence of myalgia after suxamethonium was determined in 200 fit military male dental patients of European, Chinese and Nepalese descent. Half received pancuronium 1 mg and the other half received saline pretreatment on a randomised double-blind basis. The percentage incidence of postsuxamethonium myalgia after saline or pancuronium was found to be: Europeans 26%, 13%; Chinese 13%, 7%; Nepalese 20%, 14%. Although pancuronium reduced the incidence of myalgia by about 50% overall, these values were not significantly different from each other. The recovery of spontaneous ventilation following suxamethonium was quicker in the Europeans than in the Asians (p < 0.05). Pancuronium pretreatment also delayed the recovery of spontaneous ventilation and recovery from neuromuscular block (p < 0.05) but this was independent of ethnicity. The Europeans recovered from anaesthesia more quickly than the Asians. It was concluded that ethnicity affected recovery from suxamethonium and from anaesthesia but was not of clinical relevance to the incidence of myalgia in male Asians and Europeans.

Adolescent↗
PubMed1993

Subcutaneous emphysema, pneumomediastinum and pneumothorax complicating laparoscopic vagotomy. Report of two cases.

Two patients developed subcutaneous emphysema and pneumomediastinum during laparoscopic vagotomy. One of the patients also had a pneumothorax which produced a sudden increase in end-tidal carbon dioxide concentration preceding arterial oxygen desaturation. The pneumothorax was drained with an intercostal cannula. The patient required a twofold increase in minute ventilation to maintain normocarbia, probably because of the additional absorption of carbon dioxide through the pleural cavity. Despite the presence of a peritoneo-pleural communication, surgery was successfully completed. We believe that gas under tension in the peritoneal cavity dissected along tissue planes around the oesophagus opened up during surgery. Thus pneumomediastinum, subcutaneous emphysema and pneumothorax are definite risks associated with this new procedure.

Adult↗
PubMed1993

Anaesthesia for laparoscopic general surgery.

Laparoscopic surgery minimises postoperative morbidity. Patient benefits include reduction in postoperative pain, better cosmetic result and quicker return to normal activities. Hospital stay is shortened resulting in a reduction in overall medical cost. The intraoperative requirements of laparoscopic surgery however can lead to serious physiological changes and complications. While there is a low but definite perioperative mortality rate associated with minor gynaecologic laparoscopic procedures, laparoscopic general surgical procedures are performed on older patients and patients with acute surgical conditions and are likely to be associated with a higher incidence of perioperative complications. The major problems during laparoscopic surgery are related to the cardiopulmonary effects of pneumoperitoneum, systemic carbon dioxide absorption, extraperitoneal gas insufflation, venous gas embolism and unintentional injuries to intra-abdominal structures. An appraisal of the potential problems is essential for optimal anaesthetic care of patients undergoing laparoscopic surgery. Appropriate anaesthetic techniques and monitoring facilitate surgery and allow early detection and reduction of complications. The need for rapid recovery and short hospital stay impose additional demands on the anaesthetist for skillful practice.

Anesthesia, General↗
PubMed1993

Analgesia after caesarean section with intramuscular ketorolac or pethidine.

We compared, in a double-blind randomised study, intramuscular ketorolac 30 mg (n = 49) and intramuscular pethidine 75 mg (n = 51) for analgesia after elective caesarean section under general anaesthesia. Anaesthesia was induced with thiopentone and suxamethonium and maintained with atracurium, nitrous oxide and isoflurane. Intravenous fentanyl 100 micrograms was given after delivery of the neonate. In the recovery ward, patients who requested analgesia were allocated randomly to receive ketorolac 30 mg or pethidine 75 mg intramuscularly. Analgesia was assessed at intervals up to six hours, using a visual analogue scale and a four-point verbal scale, while duration of analgesia was taken as the time until the patient requested additional analgesia. There was no difference in the duration of analgesia between groups (Mann-Whitney test P = 0.27, Mantel-Haentszel test P = 0.17). Twenty-six patients in the ketorolac group and 17 patients in the pethidine group requested further analgesia by 90 minutes. However, four patients in the ketorolac group and six patients in the pethidine group requested no further analgesia within 24 hours. Pain VAS and overall assessment of analgesia was similar between groups, although more side-effects (nausea, dizziness) were noted in the pethidine group. Ketorolac 30 mg and pethidine 75 mg provided similar but variable quality of analgesia after caesarean section.

Adult↗