Anaesthesia
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Randomized Controlled Trial Comparative Study
A randomised crossover comparison of manikin ventilation through Soft Seal(®) , i-gel™ and AuraOnce™ supraglottic airway devices by surf lifeguards.
Forty surf lifeguards attempted to ventilate a manikin through one out of three supraglottic airways inserted in random order: the Portex® Soft Seal®; the Intersurgical® i-gel™; and the Ambu® AuraOnce™. We recorded the time to ventilate and the proportion of inflations that were successful, without and then with concurrent chest compressions. The mean (SD) time to ventilate with the Soft Seal, i-gel and AuraOnce was 35.2 (7.2)s, 15.6 (3.3)s and 35.1 (8.5) s, respectively, p < 0.0001. ⋯ The mean (SD) tidal volumes through the Soft Seal, i-gel and AuraOnce were 0.65 (0.14) l, 0.50 (0.16) l and 0.39 (0.19) l, respectively. Most lifeguards (85%) preferred the i-gel. Ventilation through supraglottic airway devices may be considered for resuscitation by surf lifeguards.
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Observational Study
A prospective observational study of stroke volume responsiveness to a passive leg raise manoeuvre in healthy non-starved volunteers as assessed by transthoracic echocardiography.
Current guidelines for intra-operative fluid management recommend the use of increments in stroke volume following intravenous fluid bolus administration as a guide to subsequent fluid therapy. To study the physiological premise of this paradigm, we tested the hypothesis that healthy, non-starved volunteers would develop an increment in their stroke volume following a passive leg raise manoeuvre. Subjects were positioned supine and stroke volume was measured by transthoracic echocardiography at baseline, 30 s, 1 min, 3 min and 5 min after passive leg raise manoeuvre to 45°. ⋯ Of the 11 volunteers evaluated, five (45%) had stroke volume increases of greater than 10%. Mean (SD) maximum percentage change in cardiac index was 14.8 (9.7)% (p = 0.004). A wide variation in baseline stroke volume and response to the passive leg raise manoeuvre was seen, suggesting greater heterogeneity in the normal population than current clinical guidelines recognise.