Towards safer anaesthesia--implementing practice standards.
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Anesthesia↗
Biomedical subjects
W B Murray
Publications and source records attributed to W B Murray.
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↗
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↗
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↗
Where is the endotracheal tube?
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Humans↗
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↗
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↗
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↗
Occupational and spatial mobility of temporary Mexican migrants to the U.S.: a comparative analysis.
"U.S. job and spatial mobility are compared here for recent returnee migrants from two Mexican areas--Rio Grande, Zacatecas, in the interior; and Nueva Rosita-Muzquiz, Coahuila, near the U.S. border. Results suggest that the interior migrants fit a hierarchical migrant model: they move up the urban hierarchy from U.S. rural areas to towns and cities, experiencing substantial job mobility at first, but little after reaching the urban sector. Border migrants fit a shuttle migrant model: they return to the same job and place year after year, experiencing little or no spatial and occupational mobility, although they tend to hold somewhat higher status jobs."
Americas↗
Anaesthesia for microsurgery.
The data from a retrospective study of 32 anaesthetics administered for free-flap tissue operations are analysed. We suggest balanced analgesic-dominated general anaesthesia, supported wherever possible by continuous regional block. Special attention is paid to full control over the cardiovascular system and the haemodynamics, including the microcirculation and optimal rheological properties of the blood, as well as metabolic ability. Our results suggest that factors such as adequate infusion therapy guided by central venous pressure and urinary output and strict body temperature control, supplementary use of regional blocks and peri-operative use of dextran 40 (Rheomacrodex) can contribute significantly towards the overall success of free-flap surgery.
Adolescent↗
Should we pre-oxygenate?
The importance of routine pre-oxygenation before induction of anaesthesia was demonstrated in animals. The onset of dangerous levels of hypoxia after the administered of suxamethonium can be delayed considerably by the administration of pure oxygen for 5 minutes before induction. This allows time for an atraumatic and a panic-free intubation before controlled ventilation. After pre-oxygenation the volume of oxygen in the functional residual capacity of the lungs shows a sixfold increase. This is the principal oxygen store during apnoea.
Anesthesia↗
Implications of participant observation in medical studies.
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Anxiety↗