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Biomedical subjects

W B Murray

Publications and source records attributed to W B Murray.

At least 19 recordsLinked to original sources
PubMed1992

Standards of practice in anaesthesia--intra-operative monitoring.

Intra-operative monitoring practice during anaesthesia was studied in a randomised selection of hospitals in different categories. Questionnaires from 45 anaesthetists in 20 hospitals provided information on 973 cases. The study showed that in 11% of cases the patient was left at some stage during anaesthesia without the attention of a medical practitioner and that in 7% of cases no record was made of the anaesthetic or of the parameters monitored. Types of monitoring varied considerably between hospitals and often fell short of acceptable minimal standards. Pulse oximetry, which is considered essential, was used in only 53% of cases. One in 18 cases was associated with a peri-operative critical incident and in 7 cases a critical incident occurred where the monitoring was deemed to be inadequate. Pulse oximetry would have assisted the anaesthetist in 6 of these 7 cases. In 3% of cases the anaesthetist admitted to fatigue during the procedure. This study highlights deficits in anaesthetic practice and in available equipment, both of which require urgent attention.

Anesthesia↗
PubMed1992

Anaesthesia without tears.

Rectal induction of anaesthesia is a useful method but is not widely used in South Africa. We studied the onset of action and side-effects of 1% methohexitone administered rectally in a dose of 20 mg/kg to 110 preschool children. Ninety-one per cent were adequately sedated for inhalation induction by mask within 10 minutes, and all by 15 minutes, of drug administration. There was no evidence of significant cardiovascular or respiratory depression and only minor complications such as faecal soiling (11.8%) and hiccough (3.6%) were noted. The technique has been favourably received by parents, surgeons and nursing staff and has now become routine practice.

Anesthesia, Rectal↗
PubMed1992

Information yield from routine pre-operative chest radiography and electrocardiography.

Studies in First-World settings suggest that routine pre-operative investigations are of minimal usefulness. A retrospective study of 797 case records determined the yield of significant information from routine chest radiography and ECG in a provincial general hospital serving a broad socio-economic sector. The results were in agreement with those of other studies, viz. that routine investigation may be worthwhile only in older patients. Routine chest radiographs showed an overall positive yield of 6%; 17% in those over 60 years but only 2% in those under 60 years. Routine ECGs showed a positive yield of 7% overall; 7.4% in those older than 40 years and 4.5% in those under 40 years. Investigations indicated by history or physical examination had a significantly greater yield: 34% for chest radiography and 31% for ECGs. Positive results of indicated investigations were more evenly spread across the age groups. The pre-eminence of clinical skills in determining which patients require special investigations is reaffirmed.

Adolescent↗
PubMed1992

Oxygen masks.

Explore the source record for details and available documents.

Humans↗
PubMed1992

Early tracheal intubation with thiopentone in elective surgery.

We have studied tracheal intubating conditions within 30 s of administration of thiopentone in 24 patients and compared this with our usual method of tracheal intubation, which involves 3 min of manual ventilation in 29 patients. All patients received papaveretum 10 mg 3 min before induction and alcuronium at induction of anaesthesia. Satisfactory intubating conditions were observed in 83% of patients in both groups. There were no difficult or failed intubations and no patient had laryngospasm. The duration of laryngoscopy in the control group was 14.1 (SD 8.6) s (range 7-50 s), compared with 12.4 (3.1) s (range 6-20 s), in the early intubation group (ns). In the control group there was a significant decrease in systolic pressure before tracheal intubation and a significant increase in heart rate after intubation, compared with baseline values. The average systolic pressure in the early intubation group increased only minimally: from a pre-intubation value of 143.3 (21.2) mm Hg to 145.5 (25.1) mm Hg after intubation. Our results demonstrate that early tracheal intubation under thiopentone supplemented with an opioid and a non-depolarizing neuromuscular block is feasible, associated with minimal changes in arterial pressure and not accompanied by an increased incidence of side effects.

Adult↗
PubMed1992

Relative risk analysis of factors associated with difficult intubation in obstetric anesthesia.

Difficult tracheal intubation, often unexpected, has been identified as the commonest contributory factor to anesthetic-related maternal death. The ability to predict such cases preoperatively would be of great value. Preoperative airway assessment and potential risk factors for difficult tracheal intubation were recorded in 1,500 patients undergoing emergency and elective cesarean section under general anesthesia. Airway assessment using a modified Mallampati test recorded oropharyngeal structures visible upon maximal mouth opening. Potential risk factors documented were obesity; short neck; missing, protruding, or single maxillary incisors; receding mandible; facial edema; and swollen tongue. Subsequent to induction of anesthesia, the view at laryngoscopy and difficulty at intubation were graded. There was a significant (P less than 0.001) correlation between the oropharyngeal structures seen and both the veiw at laryngoscopy and difficulty at intubation. Univariate analysis demonstrated a significant association between difficult intubation and short neck (P less than 0.001), obesity (P less than 0.0001), missing maxillary incisors (P less than 0.02), protruding maxillary incisors (P less than 0.001), single maxillary incisor (P less than 0.0001), and receding mandible (P less than 0.003). Neither facial edema (P = 0.414) nor swollen tongue (P = 0.141) were found to be associated with difficult intubation. Multivariate analysis removed obesity and missing and single maxillary incisors as risk factors. Obesity was eliminated because of its strong association with short neck. The probability of experiencing a difficult intubation for various combinations of risk factors was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Invasive v. non-invasive blood pressure measurements--the influence of the pressure contour.

A reasonable correlation exists between invasive and non-invasive methods of measuring systemic blood pressure. However, there are frequent individual differences between these methods and these variations have often caused the validity of the non-invasive measurement to be questioned. The hypothesis that certain invasive systolic blood pressures may represent a pressure impulse rather than a flow-generating pressure was used to classify the invasive pulse pressure contour into various types, and the invasive pressure measurement was then correlated with the non-invasive. There was a significantly greater difference between these two methods of measuring systolic blood pressure in patients exhibiting prominent inotropic pressure pulse phenomena compared with patients without such phenomena. Since non-invasive monitors measure blood pressure by volume displacement or flow detection and invasive ones measure pressure impulses rather than flow, it was concluded that the pressure measured by the non-invasive monitor more accurately reflects the propulsive pressure-causing flow when inotropic pressure pulse phenomena are present.

Adult↗
PubMed1990

Control of astrocyte volume by intracellular and extracellular Ca2+.

Astrocytes from primary culture were exposed to conditions that affect intracellular and extracellular Ca2+ concentrations. Astrocyte cell volume was increased approximately 16% after a 30 min exposure to isoosmotic phosphate-buffered saline (PBS) containing the Ca2+ buffer EDTA. Cell volume returned to control values within 30 min of resuspension in normal PBS. Cellular calcium content was not affected by these treatments; however, the recovery of normal cell volume following EDTA exposure was inhibited by 0.1-1.0 mM quinine HCl in a dose-dependent fashion suggesting that a potassium channel controlled by the intracellular Ca2+ concentration is important in this volume response. Intracellular accumulation of an exogenous Ca2+ buffer, BAPTA, also produced cell swelling that persisted following resuspension in normal PBS. Lowering the extracellular Ca2+ concentration with EDTA enhanced the swelling of BAPTA-loaded cells. These data suggest that conditions leading to a decrease in free intracellular Ca2+ concentration may influence astrocyte volume by a mechanism similar to that described in other cell types.

Animals↗
PubMed1988

Obtunding the sympathetic response to intubation. Experience at 2 minutes after administration of the test agent in patients with cerebral aneurysms.

The sympathetic response to laryngoscopy and intubation was studied in 39 patients who were to undergo surgical clipping of a cerebral aneurysm. Intravascular radial artery pressure and ECG monitoring for ST-segment changes or dysrhythmias were used. Ward blood pressures were controlled on bed rest and labetalol. Induction of anaesthesia was with pentothal 4 mg/kg and suxamethonium 1 mg/kg intravenously. This was followed by one of the following intravenous agents by random choice: alfentanil 30 micrograms/kg, fentanyl 5 micrograms/kg, lignocaine 2 mg/kg, and lignocaine 10% spray 2 mg/kg to the larynx. ECG changes at laryngoscopy and intubation were minimal. Intubation produced an immediate increase in blood pressure and pulse rate, maximal at 30-60 seconds, falling rapidly towards normal within 2-3 minutes. Alfentanil was very effective in obtunding this response with stable cardiovascular parameters; fentanyl produced a more variable response; and intravenous lignocaine was less satisfactory. Lignocaine spray was ineffective.

Adult↗
PubMed1987

Prevention of post-tonsillectomy pain with analgesic doses of ketamine.

The prevention of postoperative pain in children who had undergone tonsillectomy was investigated in a double-blind trial. Ketamine (Ketalar; Parke-Davis) 0.5 mg/kg was given intravenously before the operation to 20 children and saline to a control group of 20 children. Premedication consisted of oral trimeprazine 4 mg/kg given 2 hours pre-operatively. The anaesthetic technique was standardised. There were no significant differences between the groups pre-or intra-operatively. Postoperatively there were significant differences in the measurement of pain but not in that of sedation. No hallucinations were encountered in those receiving ketamine. It is concluded that analgesic doses of ketamine are safe and effective.

Child↗
PubMed1987

Intramuscular buprenorphine compared with morphine for postoperative analgesia.

The postoperative analgesic efficacy of buprenorphine (Temgesic; R & C Pharmaceuticals) 0.004 mg/kg and morphine 0.15 mg/kg were compared in 60 patients, both agents given by intramuscular injection. According to patients, buprenorphine gave better analgesia. There was no difference in the number of analgesic injections the two groups received in the 24-hour postoperative period. Cardiovascular and respiratory systems were not depressed by either drug. Side-effects were not marked, nausea being the most common in both groups. Morphine had a greater effect on the mood of patients. Buprenorphine proved a satisfactory analgesic for postoperative use by intramuscular injection.

Adult↗
PubMed1987

Ketanserin and the cardiovascular response to intubation: a preliminary report.

Several methods of attenuating the adverse cardiovascular effects of laryngoscopy and intubation are available. The obtunding effect of ketanserin 0.5 mg kg-1 versus that of a placebo, given 5 min prior to intubation, was investigated in a randomized double-blind trial in a group of 40 patients. Blood pressure (systolic, mean and diastolic) and pulse rate were measured at 1-min intervals with an Accutor blood pressure apparatus for 5 min before and 5 min after the injection of ketanserin or placebo, as well as for 6 min after a standardized induction (thiopentone and suxamethonium), laryngoscopy and intubation. The patients who had received ketanserin had a statistically significant lower systolic blood pressure (1 and 4 min), as well as significantly lower mean and diastolic blood pressures at 1, 2, 3 and 4 min. There were no unexpected untoward side-effects. Further investigations are suggested using ketanserin as part of a multi-faceted pharmacological approach to decrease the adverse effects of laryngoscopy and intubation.

Adult↗
PubMed1986

Breath holding in divers and non-divers--a reappraisal.

The two phases of breath holding, the voluntary inactive and involuntary active phases, were identified by non-invasive methods using the induction plethysmograph. Eight trained divers and 7 non-diving control subjects familiar with respiratory apparatus were studied. During breath holding from normocapnia and total lung capacity it was not possible to distinguish between the two groups in respect of the pattern or duration of breath holding or alveolar gas tensions at the breakpoint. Divers could, however, hold their breath much longer after hyperventilation (165 +/- 40.0 and 121 +/- 31.4 seconds; P less than 0.01). This was associated with a longer second phase than occurred in non-divers (78.0 +/- 29.7 and 17.6 +/- 13.1 seconds; P less than 0.01) and more severe alveolar hypoxia (percentage oxygen 7.6 +/- 1.8 and 10.9 +/- 1.7%; P less than 0.01). It is concluded that these divers had a hyperventilation-dependent attenuated hypoxic ventilatory response. Subjects could also be identified who have either a very short (less than 10 seconds) or very long (greater than 45 seconds) second phase. They were considered to be at risk of developing underwater hypoxia and unexpected loss of consciousness. It is further suggested that analysis of the phases of breath holding holds promise as a screening test of both novice and experienced divers.

Carbon Dioxide↗