Articles: intubation.
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Rev Esp Anestesiol Reanim · Jul 1991
Comparative Study Clinical Trial Controlled Clinical Trial[Effect of an intravenous nitroglycerin bolus on the hemodynamic impact of laryngoscopy and intubation].
The aim of this study was to evaluate the effectiveness of intravenous administration of a single dose of nitroglycerin in lessening the hemodynamic effects induced during laryngoscopy and tracheal intubation. In an initial subset of 8 patients we verified that the hemodynamic changes after an intravenous dose of 2, 5, or 10 micrograms/kg of nitroglycerin were comparable. The study included 30 patients with a good clinical condition who were anesthetized with fentanyl, thiopental sodium and succinylcholine. ⋯ Increase in diastolic blood pressure was also lower in nitroglycerin treated patients but this difference was only present during laryngoscopy. There were no significant heart rate differences among the two groups of patients. It is concluded that a single intravenous dose of 2 micrograms/kg of nitroglycerin was able to lessen the increase in blood pressure induced by laryngoscopy and tracheal intubation without deleterious effects.
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We quantitatively compared the acoustic characteristics of passage of an endotracheal tube into the trachea with those of passage into the esophagus by analyzing the loudness and frequency (90% spectral edge frequency) of the sounds when auscultated at the suprasternal notch. We found that there was a significant difference (P less than 0.01) in maximum loudness between esophageal and tracheal intubations (0.15 +/- 0.05 and 0.25 +/- 0.06 V, respectively). However, there were no significant differences between the 90% spectral edge frequencies. We conclude that, without directly comparing the maximal acoustic amplitude of tracheal intubation with that of esophageal in each patient, one cannot distinguish between the two types of intubation by means of auscultation.
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The relationship between peak airway pressure, alveolar pressure and respiratory frequency was calculated for the range of compliances and airway resistances which might be encountered during mechanical ventilation of a 3-kg neonate. The pressure/flow relationships of 2.5, 3.0, 3.5 and 4-mm tracheal tubes were determined at a series of flows from 0.5 to 4 litres/minute. ⋯ Large differences between peak airway and alveolar pressures developed when frequency was increased or inspiratory time decreased; the differences were greatest with the smaller tubes. Shortening expiratory time by increasing the frequency or altering the inspiratory:expiratory ratio resulted in increased end-expiratory pressure because of incomplete emptying of the lung.
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Unexpected difficulty with tracheal intubation contributes to anaesthetic mortality. The laryngeal mask can almost always be placed satisfactorily and its position should facilitate blind intubation. A 6-mm cuffed tube will pass through both adult sizes of the mask and this study tested the feasibility of intubation through the mask. ⋯ Intubation via the laryngeal mask was attempted in 100 routine patients: of the first 50 (group 1, no cricoid pressure), 45 (90%) were successfully intubated. Maintenance of cricoid pressure throughout the manoeuvre (group 2) reduced the success rate significantly to 56% (p less than 0.05). Despite the possibility that cricoid pressure may have to be interrupted momentarily, the ease with which the technique can be learnt, and the immediate availability of the necessary apparatus suggest that it should be considered for inclusion in failed intubation drill.