Anaesthesia and tracheobronchial stenting for central airway obstruction in adults.
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Airway Obstruction↗
Biomedical subjects
W R Casson
Publications and source records attributed to W R Casson.
Vecuronium induced neuromuscular blockade. The effect of increasing dose on speed of onset.
The speed of onset of neuromuscular blockade was measured for increasing doses of vecuronium. Onset times were found to be shorter with larger doses, up to a limit of ED95 X 3 (0.15 mg/kg). Thereafter, increasing the dose, even up to ED95 X 8 (0.4 mg/kg), did not appreciably shorten the time to full neuromuscular blockade. The clinical implications of, and pharmacokinetic basis for, these findings are discussed.
Adult↗
Profound atracurium induced neuromuscular blockade. A comparison of evoked reversal with edrophonium or neostigmine.
Speed of reversal of profound atracurium induced neuromuscular blockade following edrophonium (0.5 or 1.0 mg/kg) or neostigmine (0.04 or 0.08 mg/kg) was measured using the train-of-four pattern of nerve stimulation. In all patients adequate clinical reversal was present when the ratio of the strength of the fourth to the first twitch (T4 ratio) was 0.5. Both doses of edrophonium were associated with a significantly faster speed of reversal than the smaller dose of neostigmine (p less than 0.05 in both cases). However, the larger dose of neostigmine was associated with a reversal time approaching that of edrophonium. Possible explanations for these findings are discussed in terms of contemporary theories of neuromuscular pharmacology.
Adult↗
Cardiac rate and rhythm during anaesthesia for dental extraction. A comparison of halothane, enflurane and isoflurane.
Cardiac rate and rhythm were compared in 60 patients having dental extractions under conventional general anaesthesia using halothane, enflurane or isoflurane to supplement nitrous oxide in oxygen. The incidence of arrhythmia was higher in the halothane group when compared with both the enflurane (P less than 0.05) and the isoflurane (P less than 0.05) groups. Heart rates, measured at 1-min intervals, tended to be more rapid in the isoflurane group compared with the other two groups (P less than 0.001 in both instances), and patients anaesthetized with enflurane tended to have more rapid heart rates than those anaesthetized with halothane (P less than 0.001).
Adolescent↗
Factors affecting train-of-four fade.
The characteristics of the train-of-four response during neuromuscular blockade with two agents, atracurium and vecuronium, have been compared. During onset of blockade, at 75% depression of the initial twitch, atracurium was associated with significantly more fade than was vecuronium, and larger doses of atracurium were associated with less fade than smaller doses of the same agent. In addition, with both agents, the degree of fade at a given amount of initial twitch depression was significantly less during onset than during spontaneous offset of action. The degree of train-of-four fade bears no fixed relationship to depression of the initial twitch.
Adult↗
Delayed cardiac tamponade.
A case report of cardiac tamponade is described which did not manifest itself until the patient was allowed to breathe spontaneously. Changes in intrapericardial pressure during spontaneous and controlled ventilation are discussed.
Anesthesia, General↗
Verapamil potentiation of neuromuscular blockade: failure of reversal with neostigmine but prompt reversal with edrophonium.
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Anesthesia↗
Nifedipine and cardiopulmonary bypass. Post-bypass management after continuation or withdrawal of therapy.
The management of the period after hypothermic cardiopulmonary bypass has been compared in a group of patients maintained on nifedipine therapy, a group who had the drug withdrawn at least 24 hours prior to cardiac surgery, and a control group who had never received calcium antagonists. Patients in the drug withdrawal group were significantly more likely to need vasodilator intervention than the treated (p less than 0.001) or the control (p less than 0.05) groups. Although nifedipine withdrawal appeared to reduce the need for inotropic support, compared to treated (p less than 0.001) and control groups (p less than 0.005), this may be at the cost of increasing systemic vascular resistance. This observation, coupled with reports of a rebound phenomenon following abrupt withdrawal of calcium antagonist therapy, suggests that nifedipine should be continued up to the time of surgery.
Adult↗