Biomedical subjects
P M Brodrick
Publications and source records attributed to P M Brodrick.
Gas exchange parameters in radiotherapy patients during breathing of 2%, 3.5% and 5% carbogen gas mixtures.
The gas mixture carbogen may be breathed by patients to enhance the oxygenation level and therefore the radiosensitivity of tumours. However, owing to the high CO2 content, its inhalation is associated with patient intolerance. Our aim was to determine a suitable carbon dioxide and oxygen gas mixture with similar enhancement of arterial oxygenation to 5% carbogen and with improved patient tolerance. 14 patients entered the study; of those 14, 8 were able to tolerate 2%, 3.5% and 5% carbogen mixtures as well as a control gas for sufficient time to allow successful arterial blood gas sampling. Gas exchange parameters were measured using a carbon dioxide monitor and a blood gas analyser. Arterial carbon dioxide tension ranged from 2.9 kPa to 6.82 kPa whilst breathing the carbogen mixtures, and arterial oxygen tension increased at least three-fold from basal values. There were no significant changes in the respiratory rate, heart rate and blood pH. The results suggest that 2% CO2 in O2 enhances arterial oxygen levels to a similar extent as 3.5% and 5% CO2 and that it is well tolerated.
The laryngeal mask airway. A study of 100 patients during spontaneous breathing.
A prototype size 3 laryngeal mask was used in 100 patients by 18 anaesthetists with no previous experience of its use. A clear and unobstructed airway was obtained in 98% of patients, without requiring support of the jaw, thus leaving the anaesthetists' hands entirely free. The patency of the airway did not deteriorate during the course of the anaesthetic. In 10 patients there was obstruction of the airway at the first attempt to place it without the introducer and this obstruction appeared to be as a result of downfolding of the epiglottis. Subsequent attempts at passage were successful in all 10 patients. The seal between the mask and the larynx was adequate for artificial ventilation of the patients, but the mean leak pressure was 1.7 kPa.
The antigravity suit in neurosurgery. Cardiovascular responses in seated neurosurgical patients.
The haemodynamic responses associated with inflation of the antigravity suit (G suit, aviation type) to 8.0 kPa were studied in a series of 40 patients who underwent neurosurgical operations in the sitting position. The study showed statistically significant increases in systolic arterial pressure (p less than 0.005) and mean central venous pressure (p less than 0.001) with inflation of the suit. The systolic arterial and mean central venous pressures remained significantly elevated immediately before deflation of the suit at the end of the operation (p less than 0.001 and p less than 0.005 respectively). The addition of 0.8-1.0 kPa positive end expiratory pressure during suit inflation was also investigated. A further increase in central venous pressure occurred but this did not achieve statistical significance.
Anesthesia for trans-sternal thymectomy in myasthenia gravis.
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Suxamethonium in myasthenia gravis.
The effects of suxamethonium 1.0 and 0.5 mg/kg were studied in myasthenic patients. Resistance was not encountered at the 1.0 mg/kg dose but was seen at the lower dose. A non-depolarising type of block developed in patients in both groups. However, recovery from the non-depolarising block was not prolonged beyond the requirements of surgery. The neurophysiological basis for, and clinical implications of these findings are discussed.
A new device for the inflation of the antigravity suit.
The 'Schuco' orthopaedic tourniquet inflator can be simply converted into a suitable device for inflating an antigravity suit (G-suit). The antigravity suit may be used on neurosurgical patients undergoing procedures in the sitting position to help prevent hypotension and air embolism. The availability of this device may encourage the more widespread use of an antigravity suit in neuro-anaesthetic practice.