A prospective comparison of IMV and T-piece weaning from mechanical ventilation.

Two hundred (200) consecutive medical and surgical patients requiring mechanical ventilation were entered into a prospective randomized trial of weaning by either intermittent mandatory ventilation (IMV) or T-piece. Patients in these groups were of similar age and sex and had the same total ventilation time (TVT). The study design provided equal time for each weaning mode after specific criteria for oxygenation and ventilation were satisfied (PaO2 greater than 55 mm Hg on FIO2 less than 0.5; VE less than 12 L/min and two of the following four parameters: MVV greater than 2 VE, VT greater than 5 ml/kg, FVC greater than 10 ml/kg, NIF less than or equal to -20 cm H2O). Of the original 200 patients 165 were entered into the weaning phase; 35 patients were withdrawn prior to weaning due to the discretion of the attending physician or protocol error. Weaning time was not different between the IMV (5.3 +/- 1.2 h, mean +/- SEM) and T-piece groups (5.9 +/- 1.4 h, p = NS). Of the 165 patients, 155 (93 percent) were weaned successfully by protocol, 79 in the IMV and 76 in the T-piece group. Of 155 patients, 136 (88 percent) were weaned on the first attempt by protocol. Of the 19 who were not weaned, 11 were weaned successfully on the second and five on the third trial; three patients required three-day weans. We conclude that clinically stable patients who require short-term mechanical ventilation and meet standard bedside weaning criteria can be weaned efficiently by protocol using either IMV or T-piece techniques.

Effect of patient positioning on distribution of tetracycline in the pleural space during pleurodesis.

Thoracostomy tube drainage with tetracycline (TCN) instillation is an effective technique for management of recurrent, symptomatic, malignant pleural effusions. Although patient rotation through various positions after instillation of TCN has been advocated empirically, it has not been shown scientifically to be necessary and is often uncomfortable for the patient and time-consuming for personnel. Five patients with symptomatic, malignant pleural effusions were studied during pleurodesis using radiolabelled TCN. Scintigraphic imaging was done immediately after TCN instillation prior to patient rotation. Patients were rotated through six positions and multiple images were obtained at 30 and 120 minutes. Tetracycline dispersed throughout the pleural space within seconds. Patient positioning had no effect on the intrapleural distribution of TCN in four of the five patients. In one patient with loculated hydropneumothorax and trapped lung, rotation minimally improved distribution of TCN to the apex. Rotation during pleurodesis does not appear to be necessary in patients with a relatively normal pleural space. However, patient rotation enhances distribution of TCN when the lung is separated substantially from the chest wall, as with trapped lung. Possibly, in this situation the properties of fluid mechanics and capillary action no longer apply.

Protected transbronchial needle aspiration and protected specimen brush in the diagnosis of pneumonia.

Protected transbronchial needle aspiration (PTBNA) of pneumonic lung theoretically could bypass dislodged upper respiratory tract flora, a potential source of contamination of protected specimen brush (PSB) cultures. To evaluate the usefulness of PSB and PTBNA in establishing the etiology of pneumonia, we prospectively studied 20 patients with acute bacterial pneumonia not receiving antibiotics. After informed consent, patients had fiberoptic bronchoscopy under fluoroscopy to localize the pneumonia, and specimens were obtained by the PSB. The protective plug of a specially devised needle for PTBNA was pneumatically dislodged and aspiration was performed within the infiltrate under fluoroscopy. Quantitative cultures were plated immediately for aerobes, anaerobes, and Legionella. Greater than 4 X 10(3) organisms/brush or 1 X 10(4) organisms/ml needle aspirate were considered to be consistent with infection. The results using PSB and PTBNA were compared in 15 of 20 patients in whom a definitive diagnosis (positive blood or pleural fluid culture) or presumptive diagnosis (expectorated sputum culture, clinical characteristics, and response to specific therapy) was established. The PSB and PTBNA cultures on uninfected control subjects (n = 5) being bronchoscoped for other reasons were negative. The PSB and PTBNA were each diagnostic in 2 of the 5 patients with definitive diagnoses. In the group with a presumptive diagnosis (n = 10), PSB was diagnostic in 7 of 10 and PTBNA in 9 of 10. The overall (definitive plus presumptive) diagnostic yield was 60% for PSB and 73% for PTBNA. Multiple organisms were isolated in high concentrations in 53% of the patients. The most common organisms recovered in addition to the primary pathogen was alpha hemolytic streptococci.(ABSTRACT TRUNCATED AT 250 WORDS)

Post-extubation pulmonary edema following anesthesia induced by upper airway obstruction. Are certain patients at increased risk?

Pulmonary edema due to upper airway obstruction can be observed in a variety of clinical situations. The predominant mechanism is increased negative intrathoracic pressure, although hypoxia and cardiac and neurologic factors may contribute. Laryngospasm associated with intubation and general anesthesia is a common cause of pulmonary edema in children. However, only seven cases of pulmonary edema presumably due to laryngospasm have been reported in adolescents and adults. Five of the seven had other risk factors for upper airway obstruction, and in four, the diagnosis of "laryngospasm" could be explained by other factors. Patients with underlying risk factors for upper airway obstruction, such as a forme fruste of sleep apnea or nasopharyngeal abnormalities, appear to be at increased risk for the development of pulmonary edema in the setting of intubation and anesthesia. This form of pulmonary edema usually resolves rapidly without the need for aggressive therapy or invasive monitoring.