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Biomedical subjects

T W Feeley

Publications and source records attributed to T W Feeley.

5 recordsLinked to original sources

Pancuronium bromide.

Pancuronium bromide is a nondepolarizing muscle relaxant approved to induce skeletal muscle relaxation during anesthesia and to facilitate the management of patients undergoing mechanical ventilation. The use of pancuronium bromide during surgery led to the appreciation that it has advantages over drugs previously used for muscle relaxation. Patients in whom pancuronium bromide is of value are (1) hypoxemic patients resisting mechanical ventilation and so cardiovascularly unstable that use of sedatives is precluded, (2) patients with bronchospasm unresponsive to conventional therapy, (3) patients with severe tetanus or poisoning where muscle spasm prohibits adequate ventilation, (4) patients with status epilepticus unable to maintain their own ventilation, (5) shivering patients in whom metabolic demands for oxygen should be reduced, and (6) patients requiring tracheal intubation in whom succinylcholine administration is contraindicated. Without concomitant sedation, use of pancuronium bromide is associated with psychological risks. Other risks are undetected ventilator disconnection, tachyarrythmias, prolonged paralysis and drug interactions.

Animals

Positive end-expiratory pressure in weaning patients from controlled ventilation. A prospective randomised trial.

Twenty-five patients in acute respiratory failure were randomised to receive either 5 cm of positive end-expiratory pressure (P.E.E.P.) or no-P.E.E.P. while weaning from controlled ventilation. The use of P.E.E.P. resulted in a significant reduction in the increase in alveolar-arterial oxygen tension gradient (AaDO21) which occurred in the group of patients who were converted from controlled ventilation to spontaneous ventilation without P.E.E.P. Patients who weaned without P.E.E.P. had a mean increase in AaDO21 of 102+/-35 mm Hg S.E. while those who weaned with P.E.E.P. had a mean increase of only 10+/-22 mm Hg (P less than 0-03). The use of P.E.E.P. was also associated with a significant improvement in the vital capacity and the maximum inspiratory force. Patients who weaned with P.E.E.P. had an increase in vital capacity of 258+/-108 ml (P less than 0-05) and an increase in inspiratory force of -15+/-5 cm H2O (P less than 0-01), while patients who weaned without P.E.E.P. did not have significant changes in these measurements. The use of P.E.E.P. during weaning may be helpful in patients who fail to wean because of the development of hypoxaemia due to rapid alveolar collapse, since P.E.E.P. appears to minimise the increase in intrapulmonary right-to-left shunt which normally occurs during weaning from controlled ventilation.

Acute Disease

Aerosol polymyxin and pneumonia in seriously ill patients.

Pneumonia caused by Pseudomonas aeruginosa occurs frequently in critically ill patients and is associated with a mortality rate of 70 per cent. An aerosol of polymyxin B was administered (2.5 mg per kilogram per day) to the upper airways of 292 patients in a respiratory-surgical intensive-care unit during a seven-month period, in an attempt to prevent Ps. aeruginosa pneumonia. Although only one of the patients studied acquired pneumonia due to Ps. aeruginosa, 10 others acquired pneumonia caused by a polymysinx-resistant organism. Seven pneumonias were caused by organisms not frequently pathogenic to man (flavobacteria, serratia and Streptococcus faecalis). The mortality rate for acquired pneumonia in this study, 64 per cent, is greater than that in previous studies in which either no polymyxin or cyclic polymyxin therapy was used. Continuous use of polymyxin B aerosol appears to be a dangerous form of therapy.

Aerosols

The hazards of bulk oxygen delivery systems.

Many hospitals throughout the world obtain oxygen from a supply of bulk liquid oxygen which is delivered throughout the hospital via pipelines. An incident in which, through a series of malfunctions, dangerously high pressure developed in the hospital oxygen pipeline is described. The oxygen delivery systen described lacked a relief valve to vent excessive pressures. In North America such a relief valve is required on all oxygen delivery systems. An alarm system is also required which detects rises in pipeline pressures. Regulations in the U.K. do not provide for pressure-relief valves on liquid oxygen pipeline systems. In the U.K. there is also no regulation on alarms to warn of high pipeline pressures. High-pressure accidents are a real threat to patients and hospital staff unless proper safeguards are built into oxygen delivery systems.

Accident Prevention