British journal of anaesthesia
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Comparative Study Clinical Trial Controlled Clinical Trial
Prediction of movement at laryngeal mask airway insertion: comparison of auditory evoked potential index, bispectral index, spectral edge frequency and median frequency.
We have studied 46 patients to compare the efficacy of the auditory evoked potential (AEP) index, bispectral index (BIS), 95% spectral edge frequency (SEF) and median frequency (MF) in predicting movement in response to insertion of the laryngeal mask airway (LMA). Anaesthesia was induced with target-controlled infusions of propofol and alfentanil. After loss of eyelash reflex and adequate jaw relaxation, the LMA was inserted without the assistance of a laryngoscope or neuromuscular blocker. ⋯ Only AEP index discriminated between movers and non-movers with a prediction probability of 0.872. BIS, SEF and MF could not predict movement at LMA insertion. AEP index was the most reliable predictor of movement in response to LMA insertion.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of four methods for assessing airway sealing pressure with the laryngeal mask airway in adult patients.
We have compared four tests for assessing airway sealing pressure with the laryngeal mask airway (LMA) to test the hypothesis that airway sealing pressure and inter-observer reliability differ between tests. We studied 80 paralysed, anaesthetized adult patients. Four different airway sealing pressure tests were performed in random order on each patient by two observers blinded to each other's measurements: test 1 involved detection of an audible noise; test 2 was detection of end-tidal carbon dioxide in the oral cavity; test 3 was observation of the aneroid manometer dial as the pressure increased to note the airway pressure at which the dial reached stability; and test 4 was detection of an audible noise by neck auscultation. ⋯ Inter-observer reliability of all tests was classed as excellent. The manometric stability test had a higher mean airway sealing pressure (P < 0.0001) and better inter-observer reliability (P < 0.0001) compared with the three other tests. We conclude that for clinical purposes all four tests are excellent, but that the manometric stability test may be more appropriate for researchers comparing airway sealing pressures.
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Randomized Controlled Trial Clinical Trial
Thrombelastogram reveals hypercoagulability after administration of gelatin solution.
We have compared the effects of gelatin, low molecular weight hydroxyethyl starch (HES) or albumin on tests of haemostasis and on the thrombelastogram in 42 ASA I patients undergoing total hip or knee replacement. Patients were allocated randomly to receive one of the three blood substitutes to obtain moderate intraoperative haemodilution. Blood loss and packed red cell infusion was the same in each group. ⋯ Platelets were slightly but significantly lower after HES. Haemodilution was comparable between groups. TEG showed a state of hypercoagulability in the gelatin group with a significant decrease in r, r + k and an increase in alpha angle.
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Comparative Study
Liability of laryngeal mask airway devices to thermal damage from KTP and Nd:YAG lasers.
We have compared the liability of four laryngeal mask airway (LMA) devices (standard, flexible, intubating and reusable) and a tracheal tube to thermal damage from KTP and Nd:YAG lasers at two power densities used commonly in airway surgery: 570 W cm-2 and 1140 W cm-2. Eighty-five airway devices were tested: 24 standard LMA (silicone-based), 12 flexible LMA (silicone-based, metal wires), 24 disposable LMA (PVC-based), one intubating LMA (silicone and steel-based) and 24 PVC-based tracheal tubes. Comparisons were made during laser strike to eight different targets: the unmarked and marked part of the airway device tube; the unmarked part of the airway device tube after application of blood; the cuff filled with air or methylene blue dye; the unmarked flexible LMA tube on or between the metal wires; and the epiglottic elevator bar of the intubating LMA. ⋯ Print markings, blood and the metal wires of the flexible LMA reduced the thermal resistance of the tube. Filling the cuff with methylene blue dye increased the thermal resistance of all airway devices. We conclude that the silicone-based LMA devices were more thermal resistant to KTP and Nd:YAG laser strike than PVC-based devices with the exception of the disposable LMA cuff and the intubating LMA tube.
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Case Reports
Epidural haematoma after removal of an epidural catheter in a patient receiving high-dose enoxaparin.
A patient developed an epidural haematoma 6 days after removal of an epidural catheter resulting in paraplegia and death. Insertion and removal of the epidural catheter during anticoagulation with prophylactic unfractionated heparin and subsequent administration of high-dose enoxaparin (Clexane), which commenced 3 days after catheter removal, were implicated.