British journal of anaesthesia
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Respiratory failure following cardiopulmonary bypass (CPB) is a major complication after cardiac surgery. A vital capacity inflation of the lungs, performed before the end of CPB, may improve gas exchange, but the necessity to repeat it is unclear. Therefore, we studied 18 pigs undergoing hypothermic CPB. ⋯ From 3 to 6 h after CPB, there was no more improvement and more than 10% atelectasis remained at 6 h. In contrast, the two groups treated before termination of CPB with VCM showed only minor atelectasis and no abnormal changes in gas exchange directly after bypass or later. We conclude that the protective effect of VCM remained for 6 h after bypass, and there was no extra benefit on gas exchange by repeating the VCM.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of S(-)-bupivacaine with racemic (RS)-bupivacaine in supraclavicular brachial plexus block.
Bupivacaine is used widely as a local anaesthetic but has potential for severe cardiovascular and central nervous system (CNS) toxicity. It has an asymmetric carbon atom giving it a chiral centre, and the commercial preparation is a racemic mixture of its two enantiomers: dextro or R(+)-bupivacaine and levo or S(-)-bupivacaine. Preclinical studies have demonstrated reduced cardiotoxicity and CNS toxicity for S(-)-bupivacaine. ⋯ Duration of sensory block was prolonged with wide interpatient variation: 892 (SD 250) min, 1039 (317) min and 896 (284) min for 0.25% S(-)-bupivacaine, 0.5% S(-)-bupivacaine and 0.5% RS-bupivacaine, respectively. There were no differences in the overall success rate of the technique. We conclude that S(-)-bupivacaine was suitable for local anaesthetic use in brachial plexus block anaesthesia.
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Diaspirin cross-linked haemoglobin (DCLHb) is a new oxygen carrying blood substitute with vasoactive properties. Vasoactive properties may be mediated via high affinity binding of nitric oxide by the haem moiety. Using a rodent model of head injury combined with ischaemia, we studied the effects of DCLHb on cerebral blood flow (CBF) and intracranial pressure (ICP). ⋯ Mean arterial pressure (MAP), ICP, cerebral perfusion pressure (CPP) (CPP = MAP - ICP) and CBF were measured 4 h after injury in all animals. DCLHb significantly reduced ICP from mean 13 (SEM 2) to 3 (1) mm Hg (P < 0.001), increased CPP from 52 (8) to 95 (6) mm Hg (P < 0.001) and increased CBF from 21 (2) to 29 (2) ml 100 g-1 min-1 (P = 0.032). We conclude that DCLHb improved CPP without a reduction in CBF in a rodent model of post-traumatic brain swelling.
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Randomized Controlled Trial Clinical Trial
Interaction of a subanaesthetic concentration of isoflurane with midazolam: effects on responsiveness, learning and memory.
There are situations in which "light" anaesthesia combined with neuromuscular block is the only anaesthetic regimen that can be tolerated safely by the patient. Benzodiazepines have hypnotic and specific amnesic effects. Therefore, we have examined the interaction of midazolam with a subanaesthetic dose of isoflurane (0.2% end-expired concentration) in 28 healthy volunteers. ⋯ Recognition was also absent after administration of midazolam 0.06 mg kg-1 and at the 3-min and 15-min assessments after administration of midazolam 0.03 mg kg-1. Responsiveness was more frequent with midazolam 0.03 mg kg-1 than with 0.06 mg kg-1 and increased over time. We conclude that a larger dose of midazolam or isoflurane, or both, may be necessary to abolish responsiveness.
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Randomized Controlled Trial Clinical Trial
Gastro-oesophageal reflux with the laryngeal mask during day-case gynaecological laparoscopy.
We have evaluated if breathing spontaneously via a laryngeal mask airway is associated with a higher risk of gastro-oesophageal reflux compared with positive pressure ventilation via a laryngeal mask airway in 40 patients undergoing day-case gynaecological laparoscopy. Patients were allocated randomly to receive either positive pressure ventilation or breathe spontaneously via a laryngeal mask airway. Using continuous oesophageal pH monitoring, three patients in the ventilated group and one in the spontaneous breathing group had gastrooesophageal reflux (P = 0.29). We found no evidence to suggest that breathing spontaneously via a laryngeal mask airway increased the risk of gastro-oesophageal reflux compared with positive pressure ventilation in this group of patients.