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Wiley Online Library : Anaesthesia
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The height of the cricothyroid membrane on computed tomography scans in trauma patients

2. May 2017 - 8:40
Summary

Emergency cricothyrotomy is a common feature in all difficult airway algorithms. It is the final step following a ‘can't intubate, can't oxygenate’ scenario. It is rarely performed and has a significant failure rate. There is variation in the reported size of the cricothyroid membrane, especially across population groups. Procedural failure may result from attempting to pass a device with too large an external diameter through the cricothyroid membrane. We aimed to determine the maximum height of the cricothyroid membrane in a UK trauma population. Electronic callipers were used to measure the maximum height of the cricothyroid membrane on 482 reformatted trauma computed tomography scans, 377 (78.2%) of which were in male patients. The mean (SD) height of the cricothyroid membrane, as independently measured by two radiologists, was 7.89 (2.21) mm and 7.88 (2.22) mm in male patients, and 6.00 (1.76) mm and 5.92 (1.71) mm in female patients. The presence of concurrent tracheal intubation or cervical spine immobilisation was found not to have a significant effect on cricothyroid membrane height. The cricothyroid membrane height in the study population was much smaller than that previously reported. Practitioners encountering patients who may require an emergency surgical airway should be aware of these data. Rescue airway equipment with variety of external diameters should be immediately available.

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A randomised controlled trial of placebo, droperidol or ondansetron to prevent nausea and vomiting after tonsillectomy in children receiving dexamethasone

27. April 2017 - 18:41
Summary

We tested whether prophylactic droperidol and ondansetron, in combination with a moderate dose of dexamethasone, were equally effective in reducing nausea and vomiting after tonsillectomy in children and that both were superior to saline with dexamethasone. We randomly allocated 300 children to intravenous saline, droperidol 10 μg.kg−1 or ondansetron 150 μg.kg−1, after induction of anaesthesia and the administration of intravenous dexamethasone 250 μg.kg−1. The rates (95%CI) of nausea or vomiting within 24 postoperative hours were: 42/91 after saline, 46% (36%–57%); 43/87 after droperidol, 49% (39%–60%); reduced to 18/84 by ondansetron, 21% (13%–32%), p < 0.001. There were no differences in the rates of side-effects between groups. We conclude that ondansetron is more effective than saline in preventing nausea or vomiting after paediatric tonsillectomy when given with a moderate dose of dexamethasone, whereas droperidol was not.

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A randomised controlled trial of propofol vs. thiopentone and desflurane for fatigue after laparoscopic cholecystectomy

26. April 2017 - 6:42
Summary

Fatigue may delay functional recovery after day surgery and may be more common after propofol anaesthesia. We randomly allocated 123 participants scheduled for ambulatory laparoscopic cholecystectomy to induction and maintenance of general anaesthesia with propofol or thiopentone and desflurane. Postoperative fatigue was unaffected by the allocated anaesthetic. The combined mean (SD) Identity-Consequences Fatigue Scale of 34.3 (15.1) before surgery increased in the first postoperative week: to 60.4 (21.1) on day 1, p < 0.001; to 51.1 (17.2) on day 2, p < 0.001; and to 37.5 (16.3) on day 6, p = 0.028. The mean (SD) fatigue reduced at one postoperative month to 22.4 (12.6), 35% less than the combined pre-operative level, p < 0.001. Rates of nausea, vomiting and rescue antie-mesis during the first week after propofol, compared with thiopentone and desflurane, were: 23/63 vs. 32/60, p = 0.27; 8/63 vs. 9/60, p = 0.71; and 12/63 vs. 28/60, p = 0.001, respectively. There were no differences in postoperative pain. In conclusion, fatigue after scheduled laparoscopic cholecystectomy was unaffected by anaesthesia with propofol vs. thiopentone and desflurane.

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Lifebox pulse oximeter implementation in Malawi: evaluation of educational outcomes and impact on oxygen desaturation episodes during anaesthesia

25. April 2017 - 3:05
Summary

Pulse oximetry is an essential monitor for safe anaesthesia but is often not available in low-income countries. The aim of this study was to determine whether the introduction of pulse oximetry with training was feasible and could reduce the incidence of oxygen desaturation during anaesthesia in a low-income country. Pulse oximeters were donated, with training, to 83 non-physician anaesthetists in Malawi. Knowledge was tested immediately before and after training and at follow-up. Providers were asked to record the lowest peripheral oxygen saturation (SpO2) for the first 100 cases anaesthetised after training. The primary clinical outcome was the proportion of cases with an oxygen desaturation event (SpO2 < 90%). Seventy-seven of 83 (93%) participants completed all pre- and post-training tests. Pulse oximetry knowledge improved after training from a median (IQR [range]) score of 39 (37–42 [28–48]) to 44 (42–46 [35–50]) and this knowledge was maintained for 8 months (p < 0.001). Oxygen saturation data and provider responses were recorded for 4772 cases. The proportion of oxygen desaturation episodes decreased from 17.2% to 6.5%, representing a 36% reduction in the odds of an oxygen desaturation event in the second 50 cases compared with the first 50 (OR 0.64, 95%CI 0.50–0.82, p < 0.001). We conclude that donation of pulse oximeters, with training, in Malawi was feasible, improved knowledge and reduced the incidence of oxygen desaturation events.

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A case series of vital signs-controlled, patient-assisted intravenous analgesia (VPIA) using remifentanil for labour and delivery

18. April 2017 - 9:55
Summary

Intravenous remifentanil patient-controlled analgesia can be used during labour as an alternative to epidural analgesia. Adverse effects of opioids, including hypoxia and bradycardia, may lead to maternal morbidity and mortality. We devised an interactive feedback system based on a clinical proportional algorithm, to continuously monitor for adverse effects to enhance safety and better titrate analgesia. This vital signs-controlled, patient-assisted intravenous analgesia with remifentanil used a prototype delivery system linked to a pulse oximeter that evaluated maternal oxygen saturation and heart rate continuously. With this system, we detected oxygen saturation < 95% for more than 60 s in 15 of 29 subjects (52%); and heart rate < 60 min−1 for more than 60 s in 7 of 29 subjects (24%) during use. The system automatically responded appropriately by reducing the dosages and temporarily halting remifentanil administration, thus averting further hypoxia and bradycardia.

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