British journal of anaesthesia
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Comparative Study
Preoxygenation: a comparison of three different breathing systems.
An end-tidal expiratory oxygen concentration (FE'O2) greater than 0.90 is considered to be adequate for preoxygenation. This is generally achieved using a face mask, but this can be unsatisfactory in some patients. We compared preoxygenation in 30 healthy volunteers using a face mask, the NasOral system, which is a novel preoxygenation device, and a mouthpiece with a nose-clip. ⋯ The volunteers gave more positive ratings to the face mask and mouthpiece than to the modified NasOral system (P<0.001 and P<0.01). We conclude that the use of a mouthpiece can improve preoxygenation in some patients. The results obtained with the modified NasOral system do not justify its introduction into clinical practice.
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Patients with myasthenia gravis show sensitivity to non-depolarizing neuromuscular blocking drugs, but little is known about differences in this sensitivity between types of myasthenia. In 10 patients with ocular myasthenia gravis and 10 with generalized myasthenia gravis, twitch tension was monitored in the adductor pollicis muscle by supramaximal train-of-four stimulation of the ulnar nerve during anaesthesia with sevoflurane 2.5% and nitrous oxide 60%. After baseline measurement, an initial dose of vecuronium 10 microg kg(-1) was given. ⋯ Onset of block after the first dose of vecuronium was significantly slower in ocular than in generalized myasthenic patients (mean 300 vs 200 s; P<0.05). Doses required to attain a block of 90% or more were significantly higher in ocular than in generalized patients (median 20 vs 10 microg kg(-1); P<0.05). Clinicians should consider the type of disease according to the Osserman classification when using non-depolarizing neuromuscular. blocking drugs in patients with myasthenia gravis.
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We conducted a retrospective study of platelet count in 226 patients admitted for critical care over a 5-month period, to explore the incidence of thrombocytosis and its relation to admission category, duration of ICU stay and outcome. Our findings indicate that thrombocytosis is not rare in ICU patients. At least one platelet count greater than 450x10(9) litre(-1) was found in 21.7% of patients and was associated with lower ICU mortality (P=0.003), lower hospital mortality (P=0.006), but longer duration of ICU stay (P<0.0001). Thrombocytosis may serve as an independent predictor of favourable outcome in ICU patients.
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Diaphragm strength can be assessed from twitch gastric (TwPgas), twitch oesophageal (TwPoes), and twitch transdiaphragmatic pressure (TwPdi) in response to phrenic nerve stimulation. This requires the passage of balloon catheters, which may be difficult. Changes in pressure measured at the mouth during phrenic nerve stimulation avoid the need for balloon catheters. ⋯ Supine TwPet was related to TwPoes r2=0.84 and TwPdi r2=0.83 (P<0.01). The mean within occasion coefficient of variation while sitting was TwPet=13.3%, TwPoes=13.9%, TwPdi=11.2%, and supine TwPet=11.6%, TwPoes=14.6%, TwPdi=11.8%. We conclude that TwPet reflects TwPoes during diaphragmatic stimulation and is worthy of further study to establish its place as a guide to the presence of respiratory muscle strength and fatigue.
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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. ⋯ 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.