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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
PubMed1995

Low dose epidural lidocaine/sufentanil is effective for outpatient lithotripsy.

Lumbar epidural analgesia was administered to 60 ASA class 1 & 2 patients with 3 ml test dose of 1.5% lidocaine and bolus of 20 ml of 0.5% lidocaine containing 0.5 microgram/kg sufentanil. Bilateral decreased lumbar cold perception was accepted as evidence of analgesia despite persisting pinprick sensation in thoracic dermatomes. Oxygen saturation (SpO2), respiratory rate, cardiovascular parameters and leg muscle strength were monitored throughout and until 1 hour afterwards. Midazolam provided light sedation and atropine bradycardia control. Verbal communication was maintained. ESWL could start within 6-10 minutes of bolus, with analgesia adequate in 86% of patients, the rest being "rescued" with 5-10 ml 0.5% lidocaine or analgesic doses (20-30 mg IV) of ketamine. Leg weakness developed in 14%, with 1 patient fully paralyzed. All resolved within 1 hour. Topical urethral analgesia was used in males where cystoscopy preceded ESWL. Phenylephrine was required once for nild systolic hypotension, otherwise blood pressures were stable. Two of 4 patients experiencing pruritus needed naloxone relief. Itching appeared in skin recovering from sensory block while visceral analgesia persists. Excessive respiratory depression was not seen.

Adult↗
PubMed1995

A test to prevent subarachnoid and intravascular injections during epidural analgesia.

Not one of the present tests for the correct position of an epidural catheter can reliably detect intravascular, intrathecal and extra-epidural placement. A simple rapid test has therefore been developed. Following placement of the epidural catheter an initial aspiration test for cerebrospinal fluid and blood is performed. Air (1 ml) and then saline (2 ml) are injected through the epidural filter. The test involves 3 steps after removal of the filter: (i) the open end of the epidural catheter is lifted and the liquid meniscus present in the catheter is observed to drop rapidly; (ii) the open end of the epidural catheter is lowered and the liquid meniscus is again observed to fill the catheter with clear liquid and no blood; (iii) the presence of air in the catheter during backflow confirms the correct position in the epidural space relative to a position in the subarachnoid space. The combined steps were prospectively examined in 278 cases of surgery under epidural analgesia. The test reliably detected 5 cases of intravascular and 2 cases of subarachnoid placement. No cases of local anaesthetic toxicity or undiagnosed subarachnoid injection were noted. Not one of the 6 failures to establish epidural analgesia could be attributed to intravascular or intrathecal placement. The sensitivity, specificity and positive predictive value for correct epidural placement of the catheter were found to be 95.5%, 63.6% and 98.5% respectively. The time required to perform the test was less than 30 seconds in 92% of the cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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↗