British journal of anaesthesia
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Randomized Controlled Trial
Cricoid pressure prevents placement of the laryngeal tube and laryngeal tube-suction II.
The laryngeal tube has a potential role in patients with a difficult airway, but cricoid pressure is required if the patient is at risk of aspiration. The effect of cricoid pressure on insertion of these devices is unknown. ⋯ Continuous cricoid pressure prevents correct placement of the laryngeal tube and the laryngeal tube-suction II such that placement and ventilation via these devices are ineffective. The effect of cricoid pressure on ventilation via these devices, after correct placement, remains unknown.
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Information is lacking concerning optimal infusion rates of crystalloid during resuscitation from acute haemorrhage. In this study, a mathematical model was used to predict infusion volume of crystalloid needed to restore and maintain blood volume after acute haemorrhage. ⋯ Bolus crystalloid infusion exceeding 80 ml kg(-1) h(-1) may not increase effectiveness of fluid resuscitation. Crystalloid resuscitation for more than 2 h may be detrimental in view of an excessive net fluid retention.
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Experimental evidence from a murine model of traumatic brain injury (TBI) suggests that hypothermia followed by fast rewarming may damage cerebral microcirculation. The effects of hypothermia and subsequent rewarming on cerebral vasoreactivity in human TBI are unknown. ⋯ After moderate hypothermia, rewarming exceeding the 37 degrees C threshold is associated with a significant increase in average PRx, indicating temperature-dependent hyperaemic derangement of cerebrovascular reactivity.
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The delay between changes in end-expired sevoflurane concentrations and bispectral index (BIS) may be characterized by a 'rate constant' (ke0). A smaller ke0 reflects a longer delay. Values for ke0 vary substantially among studies. The question arises how ke0 depends on experimental conditions, including ventilation and apparatus. ⋯ Published ke0s (0.22-0.53 min(-1)), including our own for sevoflurane-depressed spontaneous ventilation (0.48 min(-1)), are in the ranges dictated by investigation-specific conditions.