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Biomedical subjects

P T Chui

Publications and source records attributed to P T Chui.

36 records · Page 2Linked to original sources
PubMed1995

Severe hyperventilation and respiratory alkalosis during pressure-support ventilation: report of a hazard.

A 53-year-old woman with a flaccid quadriparesis developed severe hyperventilation and respiratory alkalosis during pressure-support ventilation. A gas leak in the ventilator system caused a loss of positive end-expiratory pressure and autocycling of the ventilator. Large ventilator breaths were then delivered because a high level of pressure support was set in a patient with low respiratory impedance. The complication is rare and its occurrence requires a combination of patient and equipment factors. Awareness of the responsible factors will promote detection and prevention of the hazard.

Alkalosis, Respiratory↗
PubMed1995

Pressure support ventilation during isoflurane anaesthesia.

We have studied the respiratory effects of 5 and 10 cmH2O pressure support ventilation during anaesthesia with 1.5% end-tidal concentration of isoflurane in nine healthy, spontaneously breathing, adult patients. Some of the patients demonstrated an irregular respiratory pattern with periods of apnoea and we therefore went on to study a further seven patients with a continuous 500 s recording of airflow. Pressure support ventilation augmented mean (SD) tidal volume from 212 (56) ml to 360 (88) ml at 5 cmH2O and to 509 (108) ml at 10 cmH2O (n = 16, p < 0.05). Mean (SD) respiratory rate decreased from 26 (6) min-1 to 22 (6) min-1 at 5 cmH2O and 17 (5) min-1 at 10 cmH2O pressure support (n = 16, p < 0.05). Mean (SD) inspiratory work of breathing decreased from 1.77 (0.70) J. min-1 to 0.31 (0.36) J.min-1 at 5 cmH2O and 0.16 (0.26) J.min-1 at 10 cmH2O pressure support ventilation (n = 9, p < 0.05). Analysis of the respiratory rhythm in the second group of seven patients revealed an oscillating respiratory pattern in four patients at 5 cmH2O and six of the seven patients at 10 cmH2O pressure support ventilation. The metabolic advantage of the decreased work of breathing during pressure support ventilation during anaesthesia is unlikely to balance the disadvantage of an oscillating respiratory rhythm.

Adolescent↗
PubMed1995

A comparison between ketorolac and diclofenac in laparoscopic sterilization.

We compared ketorolac and diclofenac for the prevention and treatment of post-operative pain in patients undergoing laparoscopic sterilization. Fifty ASA I or II women were allocated randomly to receive either diclofenac 75 mg or ketorolac 30 mg intramuscularly 30-90 min before general anaesthesia. Pain scores were assessed half-hourly in the recovery room and then at 2 h and 4 h in the ward. In the recovery room, pain was treated with a second dose of the study drug, followed by parenteral pethidine if necessary. Four patients in the diclofenac group and five patients in the ketorolac group requested no analgesics after surgery. Fifteen patients from each group had satisfactory analgesia after the second dose of study drug. Pain scores were similar between groups at all times. The median (range) initial pain score in the recovery room was 5 (0-9.5) in the diclofenac group and 5 (1-9) in the ketorolac group. Pain at the injection site was more common after diclofenac than ketorolac (12 vs. 3, P < 0.05). In conclusion, both intramuscular diclofenac and ketorolac were relatively ineffective in controlling the pain after laparoscopic sterilization. The drugs were equally well tolerated, but more patients complained of pain at the injection site after diclofenac.

Adult↗
PubMed1994

Anaesthesia for three-stage thoracoscopic oesophagectomy: an initial experience.

We report our experience in the anaesthetic management of five patients undergoing three-stage thoracoscopic oesophagectomy. One patient required conversion to open thoracotomy because of extensive pleural adhesions. The other four patients, aged between 68 and 78, were all chronic smokers with mid-oesophageal squamous cell carcinoma. The duration of thoracoscopic surgery (and obligatory one-lung ventilation) ranged from 2.5 to 4 hours with total surgical time ranging from 7.5 to 9.5 hours. Anaesthetic considerations included the use of one-lung ventilation to provide surgical access, the cardiorespiratory effects of capnothorax, difficulties in assessing surgical blood loss during thoracoscopic dissection, crowding in the operating room with limitation of access to the patient and the risk of intraoperative dislodgement of the endobronchial tube. Postoperative pulmonary complications were not decreased in our patients despite the avoidance of thoracotomy. The thoracoscopic technique might contribute to pulmonary complications because of prolonged thoracoscopic dissection and unintentional pulmonary injuries. The concept of minimally invasive surgery needs further evaluation when the technique is applied in extensive procedures such as oesophagectomy.

Aged↗
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↗
PubMed1992

Systemic absorption of glycine irrigation solution during endometrial ablation by transcervical endometrial resection.

OBJECTIVE: To study systemic absorption of glycine irrigation solution and its consequences during transcervical endometrial resection (TCER). DESIGN, SETTING, PATIENTS: A prospective study of 20 consecutive female patients who underwent elective TCER in a teaching hospital. METHOD: During the operation, patients were monitored with electrocardiography, automated oscillotonometry, pulse oximetry, capnography and a central venous pressure recorder. Plasma sodium and potassium levels were measured at 15-minute intervals. Blood haemoglobin concentration, serum osmolality, and plasma sodium, potassium and glycine concentrations were measured before and after surgery. RESULTS: Plasma glycine concentration increased in all patients after TCER. The highest concentration recorded was 5575 mumol/L. The increase correlated only with the maximum intraoperative decrease in plasma sodium, which was 7 mmol/L in two patients whose plasma glycine level increased by 3001 mumol/L and 5335 mumol/L. CONCLUSION: Systemic absorption of glycine irrigation solution occurred in all patients during TCER. Serial measurement of plasma sodium was necessary to detect this complication. A decrease in plasma sodium level by 7 mmol/L or more during surgery would indicate fluid absorption that could cause severe hyperglycinaemia and other potential complications.

Absorption↗
PubMed1992

Anaesthesia for a patient undergoing transthoracic endoscopic vagotomy.

We describe the anaesthetic management of a patient who underwent transthoracic endoscopic vagotomy. One-lung ventilation was necessary to provide adequate surgical access. Potential intraoperative problems involved arterial oxygen saturation during one-lung ventilation, unequal intrathoracic pressures causing mediastinal displacement and inadvertent myocardial injury by surgical instruments and diathermy. The management of these problems and the benefits of endoscopic surgery to the patient are discussed.

Anesthesia, General↗
PubMed1992

Hypnotic and anaesthetic interactions between midazolam, propofol and alfentanil.

We have examined interactions between midazolam, propofol and alfentanil using two end-points of light sedation (hypnosis) and anaesthesia. Quantal dose-response curves were determined in 400 female patients for the drugs individually and in combination. At the hypnotic end-point, interactions were analysed by fitting the data to a mathematical model where the response depended on the doses of the three drugs with additional terms included to describe non-additive interactions of the various combinations of the three drugs. There were significant interactions for hypnosis; the decrease in expected ED50 for the various combinations were: midazolam-propofol = 37%, midazolam-alfentanil = 46%, propofol-alfentanil = 20%, midazolam-propofol-alfentanil = 42%. Whilst all responses to the two-drug combinations were synergistic, the three-drug combination led to a response that was less than that expected from the effects of the individual agents and their two drug interactions. For anaesthesia, dose-related effects could not be demonstrated for midazolam or alfentanil when used alone. The decrease in ED50 of propofol in the presence of the other compounds was propofol-midazolam = 52%, propofol-alfentanil = 73%, propofol-midazolam-alfentanil = 82%. When comparing the different combinations, the responses varied markedly at each end-point assessed and could not be predicted from the responses of the individual agents.

Adolescent↗
PubMed1992

A double-blind randomised trial comparing postoperative analgesia after perioperative loading doses of methadone or morphine.

This double-blind randomised study compared postoperative analgesia after a loading regimen of methadone or morphine in thirty women undergoing abdominal hysterectomy. Methadone or morphine, 0.25 mg.kg-1, was given intravenously at induction of anaesthesia with further increments in the recovery room for analgesia if required. The mean (SD) total doses of methadone and morphine required were 0.43 (0.13) mg.kg-1 and 0.45 (0.15) mg.kg-1 respectively. Patients in the methadone group had lower pain scores in the subsequent 48 hours (P less than 0.001) and required less supplementary intramuscular opioids (P less than 0.001). Ten patients in the methadone group did not request any further opioid analgesics while all patients in the morphine group made at least two requests for opioids. The overall postoperative course was remembered as less painful by patients in the methadone group (P less than 0.001). There was no significant respiratory depression or excessive sedation in either group.

Adult↗
PubMed1991

Propofol and midazolam act synergistically in combination.

We have studied interactions between i.v. propofol and midazolam for induction of anaesthesia in 200 unpremedicated female patients undergoing elective gynaecological surgery. Using end-points of "hypnosis" (loss of response to verbal command) and "anaesthesia" (loss of response to a 5-s transcutaneous tetanic stimulus), we determined dose-response curves for propofol and midazolam alone and in combination. For hypnosis, synergistic interaction was found (P less than 0.01), the combination having 1.44 times the potency of the individual agents. Although midazolam failed to produce anaesthesia in the dose range used, the dose of propofol required to produce anaesthesia was reduced by 52% in the presence of midazolam (P less than 0.01). The reduction in arterial pressure at induction was the same for the combination as for the individual agents. The cause of the synergism was not clear, but may have been interaction at CNS GABAA receptors.

Adolescent↗
PubMedDate not supplied

Thoracic paravertebral block for management of pain associated with multiple fractured ribs in patients with concomitant lumbar spinal trauma.

BACKGROUND AND OBJECTIVES: The need for continual neurological assessment in patients with lumbar spinal injury poses a challenge for effective management of pain associated with multiple fractured ribs. Two cases are presented to illustrate the benefits of using thoracic paravertebral block to control the pain of multiple fractured ribs without compromising the ongoing neurological assessment. CASE REPORT: Thoracic paravertebral block was used in 2 patients with concomitant multiple fractured ribs and lumbar spinal injury. Case 2 also had a head injury and there was moderate coagulopathy. The thoracic paravertebral catheter was placed in the upper thoracic region and radiological imaging was used to delineate spread before the injection of relatively small volumes (10 to 15 mL) of local anesthetic. In case 1, the thoracic paravertebral block produced ipsilateral segmental thoracic anesthesia, providing excellent pain relief for the fractured ribs. It also spared the lumbar and sacral nerve roots, preserving neurological function in the lower extremities and bladder sensation. In case 2, effective analgesia without systemic sedation and opioids resulted in the patient regaining consciousness, which allowed continuous assessment of central and peripheral neurological function. CONCLUSION: Thoracic paravertebral block is an option for managing pain associated with multiple fractured ribs in the presence of concomitant lumbar spinal injury requiring continual neurological assessment.

Amides↗