Anaesthesia
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Six patients undergoing paravertebral blocks for chronically painful conditions of the chest wall were thermographically imaged so that the extent of cutaneous vasodilatation and hence sympathetic block could be correlated with the distribution of the somatic block. All blocks were performed by a single experienced operator, with a single percutaneous entry, using 15 ml of 0.5% bupivacaine at a mean level of T9-10 (range T7-8--T10-11), with radiological confirmation of correct needle placement. There was a mean distribution of the somatic block of five dermatomes (range 1-8), as evidenced by loss of pinprick sensation, with upper and lower limits of T6 and L3. ⋯ No significant postural changes in blood pressures were seen, although there was a small but significant decrease in supine heart rate (p = 0.05). This study demonstrates that a large unilateral somatic and sympathetic block is obtainable with a single thoracic percutaneous paravertebral injection. It challenges the suggestions that this method of analgesia is ineffective and hazardous, that a sympathetic component is a rare accompaniment and that the lumbar nerve roots are spared.
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Randomized Controlled Trial Comparative Study Clinical Trial
Changes in intra-ocular pressure during general anaesthesia. A comparison of spontaneous breathing through a laryngeal mask with positive pressure ventilation through a tracheal tube.
Changes in-intra-ocular pressure during spontaneous ventilation with a laryngeal mask were compared with controlled ventilation using a tracheal tube in 40 patients undergoing intra-ocular surgery under general anaesthesia. Intra-ocular pressure was measured before induction, after establishing the airway, at the end of the operation and after removal of the airway device. Anaesthesia was induced with propofol and maintained with enflurane and nitrous oxide in oxygen. ⋯ At the end of surgery, intra-ocular pressure (mmHg) was 11.2 and 8.6 during spontaneous or controlled ventilation respectively. One min after removal of the device, mean intra-ocular pressure (mmHg) in the tracheal tube group (16.0) was slightly higher than baseline (15.3) and was significantly higher than the laryngeal mask group (10.9) (p < 0.01). Spontaneous ventilation with a laryngeal mask is an acceptable alternative to controlled ventilation with tracheal intubation in elective intra-ocular surgery.