British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Influence of patient position on withdrawal forces during removal of lumbar extradural catheters.
We have investigated the force required to remove lumbar extradural catheters from 88 parturients to determine the effects of patient positioning at removal, relative to the position at insertion. Parturients were allocated randomly to one of four groups: LS (lateral insertion, sitting withdrawal), LL (lateral insertion, flexed lateral withdrawal), SL (sitting insertion, lateral withdrawal) or SS (sitting insertion, sitting withdrawal). ⋯ We found that the withdrawal force was influenced by the relationship between the position at removal and that at insertion, and we recommend that for ease of removal, patients should be placed in the same position as they were at the time of insertion. Compared with all other groups, the withdrawal force in patients in group LS was significantly greater (P < 0.05).
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Clinical Trial
Sternomental distance as the sole predictor of difficult laryngoscopy in obstetric anaesthesia.
Sternomental distance and view at laryngoscopy were documented in 523 parturients undergoing elective or emergency Caesarean section under general anaesthesia. Eighteen (3.5%) had a grade III or IV laryngoscopic view (Cormack and Lehane's classification) and were classified as potentially difficult tracheal intubations. There was a significant difference between sternomental distance in those patients with a grade III or IV laryngoscopic view compared with those with a grade I or II (13.17 (SD 1.54) cm vs 14.3 (1.49) cm; P = 0.0013). ⋯ A sternomental distance of 13.5 cm or less had a sensitivity, specificity, positive and negative predictive values of 66.7%, 71.1%, 7.6% and 98.4%, respectively. While there was no association between sternomental distance and age, weight, height or body mass index (BMI), there was a significant association between grade of laryngoscopy (III and IV) and older (P = 0.049) and heavier (P = 0.0495) mothers. The results suggest that while sternomental distance on its own may not be an adequate sole predictor of subsequent difficult laryngoscopy the measurement should be incorporated into a series of quick and simple preoperative tests.
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We studied 10 patients during the first night after upper abdominal surgery to assess the effect of airway obstruction on chest wall mechanics, by recording nasal gas flow and carbon dioxide concentration, rib cage and abdominal dimensions, abdominal muscle activity, and oesophageal and gastric pressures. The mean duration of study of each subject was 5.8 h, and 5.2 h were analysed. The median proportion of time spent breathing with normal mechanics was 29% (interquartile values 0-57%). ⋯ This occurred for 34 (0-52)% of the time. Both patterns were associated with evidence of increased activation of the abdominal muscles during expiration, changing the relationship of abdominal and pleural pressure changes and chest wall movements. Such changes have been interpreted previously as evidence of diaphragm dysfunction.