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Biomedical subjects

M C Newton

Publications and source records attributed to M C Newton.

11 recordsLinked to original sources

Successful defibrillation in the prone position.

Early defibrillation provides the greatest chance of survival after ventricular fibrillation. Conventional cardiopulmonary resuscitation and defibrillation requires the patient to be in the supine position. Electrical treatment of arrhythmias such as atrial fibrillation by means of a defibrillator back paddle in patients receiving prone ventilation in intensive care has been described. We report a case in which electrical defibrillation was successfully performed in the prone position in a patient undergoing complex spinal surgery. We suggest that, if defibrillation were required in ventilated patients positioned prone, defibrillation should be attempted in the prone position, as turning the patient supine would consume valuable minutes and reduce the chances of successful defibrillation.

Adult↗

Metabolic and hormonal responses to induced hypotension for middle ear surgery.

We have investigated in 30 patients the metabolic and hormonal responses to middle ear surgery using induced hypotension to a mean arterial pressure of 55 mm Hg. A standardized anaesthetic technique of propranolol, thiopentone-vecuronium-isoflurane was used in all patients and hypotension induced with sodium nitroprusside, trimetaphan camsylate or additional isoflurane. All patients showed a classic stress response with an increase in circulating blood glucose, cortisol and growth hormone concentrations. Blood lactate and plasma uric acid concentrations changed little during operation, suggesting that tissue oxygenation was adequate. However, the former declined after operation, possibly as a result of the concomitant use of propranolol. There were no significant differences between the three hypotensive techniques in their effects on the hormonal and metabolic response, although the increase in blood glucose concentration in the trimetaphan group was obtunded. We conclude that induced hypotension for middle ear surgery induced an endocrine and metabolic response of small magnitude and short duration.

Adult↗

Fibrodysplasia ossificans progressiva.

A 14-yr-old boy with fibrodysplasia ossificans progressiva (FOP) presented for surgery for bilateral division of his ossified masseter muscles. Patients with FOP may present problems to the anaesthetist, including difficulties with tracheal intubation, restrictive pulmonary disease and abnormalities of cardiac conduction. With our patient sedated the trachea was intubated using a fibrescope and anaesthesia was induced and maintained with nitrous oxide and enflurane in oxygen. Ventilation was controlled throughout surgery and recovery was uneventful.

Adolescent↗

Continuous epidural infusion of 0.075% bupivacaine for pain relief in labour. A comparison with intermittent top-ups of 0.5% bupivacaine.

Seventy-three women who requested epidural analgesia during labour were randomly allocated in a prospective study to receive either a continuous epidural infusion of 0.075% bupivacaine at a rate of 12-18 ml/hour (38 mothers) or intermittent top-ups of 0.5% bupivacaine (35 mothers). Both groups received an initial dose of 6-8 ml bupivacaine 0.5%. Patients were asked to score their pain using a 10-cm linear scale prior to insertion of the epidural, 30 minutes after its insertion and hourly thereafter. The quality of analgesia in the continuous infusion group was significantly better than in the intermittent top-up group (p less than 0.025). There was no significant difference in the total dose of bupivacaine given to the two groups.

Adolescent↗

Airway resuscitation packs for nurses: a recommendation for their withdrawal.

Approximately one third of our hospitals appear to issue airway resuscitation packs (ARPs) to nurses responsible for the care of postanaesthetic and comatose patients. These packs contain instruments intended for use in overcoming airway obstruction. One hundred and eight nurses replied to a questionnaire designed to identify their knowledge of the instruments. The results indicate that nurses entrusted with ARPs were almost totally unfamiliar with the instruments and their application. The authors recommend the universal withdrawal of ARPs and suggest that nurses and doctors are taught to recognise airway obstruction and to manage it with simple manoeuvres not involving instrumentation.

Airway Obstruction↗

Evaluating candidates for ventricular aneurysmectomy.

Forty consecutive patients having left ventricular (LV) aneurysmectomy were evaluated for surgical risk predictors and were then followed up after operation. Factors evaluated included age, time since last myocardial infarction, NYHA classification, principal indication for surgery, LV end diastolic pressure, LV "A" wave size, number of coronary systems with greater than 70% stenosis, number of coronary bypass grafts, location of aneurysm, and ejection fraction of the nonaneurysmal or "contractile segment," determined by a modification of the method of Watson et al (MCSEF). There was 100% follow-up. There were four perioperative deaths and two late deaths. Operative mortality was 3.4% in patients with MCSEF greater than or equal to 45% and 37.5% in patients with MCSEF less than 45% (P less than .05). None of the other factors evaluated significantly affected mortality independent of MCSEF. Survivors had a mean follow-up of 22 months with a mean improvement in symptoms of 1.6 NYHA class (from 3.3 to 1.7). Forty-four percent have returned to their previous occupations. It is concluded that: (1) the MCSEF is of prime importance in evaluating risk for LV aneurysmectomy; (2) for patients with MCSEF greater than or equal to 45%, LV aneurysmectomy is a low-risk procedure; and (3) LV aneurysmectomy results in sustained relief of symptoms in most patients.

Heart Aneurysm↗

Single coronary artery with a fistula to the main pulmonary artery in a patient with tetralogy of Fallot.

The presence of a single coronary artery arising in the anterior cusp and terminating in a large fistula to the main pulmonary artery was noted during the preoperative evaluation of a patient with tetralogy of Fallot. Recognition of this rare association dictated the use of a valved conduit to avoid injury to the left anterior descending coronary as it crossed the right ventricular outflow tract and permitted abolition of intracardiac shunting by ligation of the fistula. It is postulated that the increasing arterial saturation noted in this patient prior to intracardiac repair may have been related in part to progressive augmentation in flow through the coronary fistula to the main pulmonary artery.

Adult↗