The effect of breath termination criterion on breathing patterns and the work of breathing during pressure support ventilation.

UNLABELLED: With pressure support ventilation (PSV), each PSV breath is flow-cycled, and the breath termination criterion (TC) is usually nonadjustable. When TC does not match the interaction between the patient's inspiratory-expiratory efforts to the opening and closing of the inspiratory and expiratory valves, patient-ventilator asynchrony may occur, and the work of breathing (WOB) may increase. Therefore, we studied the effect of TC on breathing patterns and WOB during PSV in eight patients with acute respiratory distress syndrome or acute lung injury. We studied five levels of TC during PSV-1%, 5%, 20%, 35%, and 45% of the peak inspiratory flow. With increasing levels of TC, the tidal volume decreased and respiratory frequency increased, along with a decrease in duty cycle. WOB markedly increased with increasing levels of TC from 0.31 +/- 0.12 J/L with TC 1% to 0.51 +/- 0.11 J/L with TC 45%. Premature termination with double breathing occurred in one patient with TC 35% and four patients with TC 45%. Delayed termination with a duty cycle of >0.5 occurred in two patients with TC 1%. In conclusion, the proper adjustment of TC improves patient-ventilator synchrony and decreases WOB during PSV. IMPLICATIONS: Although termination criterion (TC) is usually nonadjustable, it influences the effectiveness of pressure support ventilation for mechanical ventilation. The proper adjustment of TC is crucial to improve patient-ventilator synchrony and decrease work of breathing. TC 5% of the peak inspiratory flow may be the optimal value for patients with acute respiratory distress syndrome or acute lung injury.

[Unexpected difficult intubation caused by a laryngeal web].

We report a case of unexpected difficult intubation in an adult caused by a laryngeal web. A 43-year-old woman with uterine myoma was scheduled for abdominal hysterectomy. After induction of anesthesia, the vocal cords were seen clearly under laryngoscopy. Although intubation was attempted several times, a 6.5 mm internal diameter tracheal tube could not be passed below the level of the vocal cords because of resistance, and we used a laryngeal mask during anesthesia. Next morning after the operation, she developed dyspnea. Bronchoscopy revealed a very narrow airway below the level of vocal cords caused by a laryngeal web. Tracheostomy was performed. Two weeks later, tracheostomy was closed without any sequela.

[A case of severe bronchospasm under epidural anesthesia with fentanyl].

A case of severe bronchospasm under epidural anesthesia with fentanyl was described. The etiology of the bronchospasm may not have been related to sympathetic nervous blockade, histamine release, or anaphylaxis. In an asthmatic patient, it should be noted that epidural anesthesia with fentanyl could develop bronchospasm.

[Argatroban, a selective thrombin inhibitor, for anticoagulant therapy during and following vascular surgery].

We administered argatroban, a selective thrombin inhibitor, as an anti-coagulant during and following vascular surgery. Activated coagulation time was controlled easily by its continuous intravenous infusion. No abnormal bleeding tendency and thrombus formation in graft and blood vessel were observed. The activity of thrombin was inhibited under the infusion of argatroban. We conclude that argatroban is effective for anti-coagulant therapy during and following vascular surgery.

Use of diltiazem to control circulatory fluctuations during resection of a phaeochromocytoma.

This report describes the use of diltiazem to control circulatory fluctuations during anaesthesia in five patients undergoing resection of a phaeochromocytoma. Diltiazem was administered continuously i.v. before anaesthesia and during surgery until the draining vein from the tumour had been ligated. Arterial pressure and systemic vascular resistance decreased in association with the infusion of diltiazem. Heart rate was stable, and there was no ventricular tachyarrhythmia. Arterial pressure was controlled easily during the manipulation of the tumour, and there were no hypotensive episodes after the removal of the tumour.