British journal of anaesthesia
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Ten patients were studied for each of the sizes 2, 3 and 4 laryngeal mask airways (LMA) in order to calculate the pressure exerted by the cuff upon the pharyngeal mucosa. Using a non-invasive method of comparing intracuff pressures recorded both in vitro and in vivo, the transmitted pharyngeal mucosal pressures were calculated over the clinical range of injection volumes. ⋯ The intracuff pressures recorded with the mask in situ at these normal injection volumes were in the range 103-251 mm Hg. The calculated transmitted mucosal pressures were substantial for all three sizes of cuff and potentially exceeded the capillary perfusion pressure of the adjacent pharyngeal mucosa, despite apparent pharyngeal accommodation to the mask.
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Case Reports
Use of esmolol in the postbypass management of hypertrophic obstructive cardiomyopathy.
In patients suffering from hypertrophic obstructive cardiomyopathy (HOCM), any catecholamine release during anaesthesia may aggravate the severity of the outflow tract obstruction and compromise cardiac output. In this event the situation may be improved by beta block. Esmolol, an ultra-short-acting beta-blocker (half-life 9 min) appears to be a suitable agent for this purpose. We describe its use in the perioperative management of a patient who underwent surgical correction of HOCM.
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The effect of thumb preload on adductor pollicis muscle compound action potential (ECAP) was assessed after supramaximal ulnar nerve stimulus during steady isoflurane anaesthesia in 20 ASA I-II patients without neuromuscular block. During thumb preload, the peak-to-peak amplitude of the ECAP increased by 0.9 mV, to 9.5 (SD 2.2) mV (P < 0.01), because of the increased height of the negative half-wave. ⋯ Without preload, the first dorsal interosseus muscle peak-to-peak amplitude was 13.0 (4.3) mV. Thus thumb preload may not be the solution to improved monitoring of neuromuscular block by ECAP.