British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Lansoprazole in the prophylaxis of acid aspiration during elective surgery.
We have assessed the efficacy of a single dose of lansoprazole in increasing the pH and decreasing the volume of gastric residue at induction of anaesthesia in adult patients undergoing elective orthopaedic surgery. We studied 66 ASAI-II patients, allocated to one of three groups to receive either placebo (group 1), lansoprazole 30 mg (group 2) or lansoprazole 60 mg (group 3), 8-12 h before induction of anaesthesia. ⋯ Patients who received lansoprazole had a significantly higher pH than the placebo group (P < 0.01) but there was no difference between the two lansoprazole groups. The volume of gastric residue was significantly smaller (P < 0.01) in both lansoprazole groups compared with the placebo group: 28% of those in group 3 had a pH of gastric residue < 2.5 and volume > 25 ml compared with 30% in group 2 and 63% in group 1, respectively.
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Because hypocapnia is routine during general anaesthesia for intracranial procedures, we have compared, in 13 healthy volunteers, the effect of normocapnia (PE'CO2 5.3 kPa) and hypocapnia (PE'CO2 3.3 kPa) on mean blood flow velocity in the middle cerebral artery (Vmca) during normoventilation and hyperventilation with air and with 50% nitrous oxide in oxygen. After replacement of air with 50% nitrous oxide in oxygen, there was an increase in mean Vmca during normoventilation (air: mean 68.23 (SD 16.98) cm s-1 vs nitrous oxide in oxygen: 90.69 (20.41) cm s-1; P < 0.01), whereas during hyperventilation mean Vmca values were similar regardless of the inhaled gas mixture (air: 43.46 (9.97) cm s-1 vs nitrous oxide in oxygen: 41.69 (8.08) cm s-1. Our data suggest that the nitrous oxide-induced increase in mean Vmca can be blocked by hyperventilation.
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We have developed a computer program that estimates venous admixture (intra-pulmonary shunt) from four measurements: haemoglobin concentration, end-tidal carbon dioxide tension (PE'CO2), fractional inspired oxygen concentration (FIO2) and pulse oximetry (SpO2). The formula was tested on patients in an intensive therapy unit by using it to estimate shunt while it was measured simultaneously by a standard, invasive method. ⋯ The limits of agreement were then +/- 16% shunt overall (+/- 13% within patients). When SaO2 was used instead of SpO2, the limits were +/- 11% (+/- 8% within patients).
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Infraorbital nerve block in neonates is not well described although it has been suggested that bilateral infraorbital nerve block is the local analgesic technique of choice for early repair of cleft lip. The purpose of this study was to determine the location of the infraorbital nerve in neonatal cadavers and to identify clinically useful landmarks. Thirty infraorbital nerves were identified in 15 neonatal cadavers with a mean weight of 2.85 (SD 0.32) kg (range 2.45-3.5 kg) via an upper buccal sulcus incision. ⋯ A line drawn from the angle of the mouth to the midpoint of the palpebral fissure measured 30.6 (1.9) mm (left) and 30.7 (1.8) mm (right). The nerve was situated approximately halfway along this line at a point 15.5 (1.5) mm (left) and 15.2 (1.4) mm (right) from the angle of the mouth. These measurements were used to perform bilateral infraorbital nerve blocks in four neonates undergoing cleft lip surgery under general anaesthesia, thereby providing analgesia with minimal risk of respiratory depression.