European journal of anaesthesiology
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Randomized Controlled Trial Clinical Trial
The tracheal tube with a high-volume, low-pressure cuff at various airway inflation pressures.
When the tracheal tube with a high-volume, low-pressure cuff is used, the pressure exerted by the cuff on the tracheal wall is similar to the intracuff pressure, and the pressure is claimed to be lower than the capillary perfusion pressure; however, it is not known if this is the case when a high airway pressure is required. In a randomized, cross-over design, we studied 61 patients (31 men) and measured the intracuff pressures of the tracheal tube at various airway pressures. ⋯ Intracuff pressures [median (range)] at airway pressures of 10, 15, 20, 25 and 30 cm H2O were 8 (0-20), 15 (4-20), 22 (6-32), 26 (11-52) and 31 (16-54) cm H2O, respectively, for men and 6 (0-20), 11 (0-20), 15 (0-24), 21 (0-32) and 25 (1-41) cm H2O, respectively, for women. Therefore, we conclude that the pressure exerted by the cuff of the tracheal tube on the tracheal wall is unlikely to exceed the capillary perfusion pressure (arbitrarily defined as 25 mmHg or 34 cm H2O) when the airway pressure is 25 cm H2O or less, but it may exceed the capillary perfusion pressure when the airway pressure is greater than 25 cm H2O.
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Clinical Trial Controlled Clinical Trial
Accelographic and mechanical post-tetanic count and train-of-four ratio assessed at the great toe.
We examined post-tetanic count (PTC) and train-of-four (TOF) ratios at the great toe assessed accelographically or mechanically and compared these with post-tetanic count and train-of-four ratios evaluated mechanically at the thumb in 24 patients who were given vecuronium. An acceleration transducer was attached to the right great toe, a force transducer to the left great toe and another force transducer to the thumb of the left hand. In the PTC group (n = 12) and TOF group (n = 12), post-tetanic count and train-of-four ratios were simultaneously recorded using the two great toes and the thumb of the left hand respectively. ⋯ In conclusion, the mechanical post-tetanic count at the great toe is lower than the mechanical post-tetanic count at the thumb. In contrast, mechanical train-of-four ratios at the great toe are greater than the mechanical train-of-four at the thumb. Nevertheless, as the mechanical train-of-four ratios at the great toe became comparable with the mechanical train-of-four ratios at the thumb, mechanical assessment of the train-of-four ratio at the great toe may be useful for the evaluation of residual neuromuscular block.
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Conventional evaluation of cardiovascular volume status by filling pressures is unreliable in critically ill patients. Measurements of left ventricular end diastolic area index by transoesophageal echocardiography and of intrathoracic blood volume index by dye indicator dilution are new approaches to this problem. In this study, different indices of cardiovascular volume status were analysed to define their relation during the pronounced haemodynamic changes associated with systemic inflammation after cardiopulmonary bypass. ⋯ Absolute values of all variables varied widely, with the only significant correlation found between CVP and PCWP. Changes in CVP and PCWP did not correlate with changes in left ventricular end diastolic area index or intrathoracic blood volume index. Provided simultaneous baseline measurements are available and a supranormal intrathoracic blood volume index compensates for the haemodynamic changes in systemic inflammation, left ventricular end diastolic area index and intrathoracic blood volume index may substitute for each other during the evaluation of cardiovascular volume status in patients with stable cardiac function.