Anaesthesia
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Randomized Controlled Trial
Pre-operative vitamin B infusion and prevention of nitrous oxide-induced homocysteine increase.
Nitrous oxide inactivates vitamin B(12) with detrimental consequences for folate and methionine metabolism, detectable by an increase in total plasma homocysteine. We hypothesised that a pre-operative vitamin B(12) and folate infusion prevents nitrous oxide-induced homocysteine increase. Sixty-three healthy patients having elective surgery were randomly allocated to receive either B-vitamin plus nitrous oxide; placebo plus nitrous oxide or placebo plus air. ⋯ After intravenous B-vitamin infusion, plasma vitamin B(12) and folate concentrations increased 35-fold and 12-fold, respectively, on the first postoperative measurement. Patients who received B-vitamins developed a similar increase (18%) in homocysteine after nitrous oxide (1.9 micromolxl(-1); 95% CI 0.2-3.6 micromolxl(-1)) as those who did not (22%; 2.7 micromolxl(-1); 95% CI 0.6-4.8 micromolxl(-1)). Patients not receiving nitrous oxide had no homocysteine change (0.5 micromolxl(-1); 95% CI -0.8-1.9 micromolxl(-1)), indicating that pre-operative intravenous B-vitamins may not prevent nitrous oxide-induced hyperhomocysteinaemia.
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Randomized Controlled Trial Comparative Study
Tracheal intubation following training with the GlideScope compared to direct laryngoscopy.
Tracheal intubation using direct laryngoscopy has a high failure rate when performed by untrained medical personnel. This study compares tracheal intubation following direct laryngoscopy by inexperienced medical students when initially trained by using either the GlideScope, a video assisted laryngoscope, or a rigid (Macintosh) laryngoscope. Forty-two medical students with no previous experience in tracheal intubation were randomly divided into two equal groups to receive training with the GlideScope or with direct laryngoscopy. ⋯ The rates of successful intubation were significantly higher in the Glidescope group after the first (48%), second (62%), and third (81%) intubations compared with the Macintosh group (14%, 14% and 33%; p = 0.043, 0.004 and 0.004, respectively). The mean (SD) times for the first, second, and third successful tracheal intubations were significantly shorter in the Glidescope group (59.3 (4.4) s, 56.6 (7.1) s and 50.1 (4.0) s) than the Macintosh group (70.7 (7.5) s, 73.7 (7.3) s and 67.6 (2.0) s; p = 0.006, 0.003 and 0.0001, respectively). Training with a video-assisted device such as the GlideScope improves the success rate and time for tracheal intubation in patients with normal airways when this is performed by inexperienced individuals following a short training programme.
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Review Case Reports
Severe hypotension related to cell salvaged blood transfusion in obstetrics.
Intra-operative blood cell salvage has recently been adopted for use in women at risk of significant haemorrhage during caesarean section. It has also been advocated for use in those patients who refuse allogenic blood transfusion. ⋯ On starting the cell-salvaged blood transfusion, the blood pressure was noted to fall and this was temporally related to the transfusion of the cell-salvaged blood. We review the recent literature and case reports on hypotension related to cell-salvaged blood transfusion.
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Randomized Controlled Trial Comparative Study
Comparison of Flexiblade and Macintosh laryngoscopes: cervical extension angles during orotracheal intubation.
The Flexiblade(TM) is a new laryngoscope with a flexible blade, a handle and a lever, allowing gradual flexion over the distal half of the blade. In this study, we aimed to compare cervical vertebral movements during tracheal intubation with the Flexiblade and Macintosh laryngoscope in 32 patients undergoing elective surgery requiring general anaesthesia (n = 16 per group). Fluoroscopic images of cervical movement were captured before, during and after intubation and evaluated by a radiologist. ⋯ C2-C3 cervical movement was similar in both groups (p = 0.81). No significant differences were noted in success rates for intubation, oxygen saturation levels, haemodynamic variables or intubation-related injury. The decreased extension angle between C1-C2 during Flexiblade laryngoscopy compared with Macintosh laryngoscopy may be an advantage where neurological damage with cervical movement is a concern.
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Unanticipated difficulties during tracheal intubation and failure to intubate are among the leading causes of anaesthesia-related morbidity and mortality. Using the technique of video laryngoscopy, the alignment of the oral and pharyngeal axes to facilitate tracheal intubation is unnecessary. In this study we evaluated the McGrath Series 5 videolaryngoscope for tracheal intubation in 61 patients who exhibited Cormack and Lehane grade 3 or 4 laryngoscopies with a Macintosh laryngoscope. ⋯ Laryngoscopy was improved by one grade in 10%, by two grades in 80% and by three grades in 10% of cases (p < 0.0001). The success rate for intubation was 95% with the McGrath. These results suggest that the McGrath videolaryngoscope can be used with a high success rate to facilitate tracheal intubation in difficult intubation situations.