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The resting volume of a low-pressure, high-volume cuff is an important factor that determines the cuff compliance, because it is the maximum volume that maintains the low-pressure characteristics of the cuff. Modern polyvinyl chloride (PVC) double-lumen tubes (DLT) are designed with a low-pressure bronchial cuff to minimize the risk of bronchial damage. Maintenance of the low-pressure characteristics of this cuff, however, requires knowledge of how its resting volume and compliance vary between different DLT sizes and brands, and how the compliance changes when the cuff is inflated inside different-sized bronchi. We, therefore, measured the bronchial cuff pressure-volume relationship for each of the adult sizes, 35 Fr, 37 Fr, 39 Fr, and 41 Fr, of the Mallinckrodt, Sheridan, Rusch, and Portex left DLTs. The compliance of each cuff was characterized by: 1) the cuff resting volume, defined as the smallest cuff volume beyond which a 0.5-mL increase in volume resulted in more than 10 mm Hg increase in cuff pressure; and 2) the cuff pressure at 3-mL volume. Measurements were repeated for sizes 35 Fr and 41 Fr left Mallinckrodt DLTs with the bronchial cuff lying inside two canine left main-stem bronchi measuring 11 mm and 13 mm in diameter. The bronchial cuff resting volume ranged from 1.5 to 5.0 mL in different sizes and brands of DLTs, which could be explained by differences in cuff size between different manufacturers and between different DLT sizes of the same manufacturer.(ABSTRACT TRUNCATED AT 250 WORDS)

Correct inflation of the cuff of any breathing tube is important; overinflation can damage the mucosa of the tracheobronchial tree and underinflation will cause a leak. Three different techniques to determine cuff seal/leak during inflation of the bronchial cuff of left double-lumen endobronchial tubes (DLT) were each evaluated in 10 patients. DLT size was chosen from a formula based on the patient's height and sex. In the first technique, designated the positive pressure technique of bronchial cuff inflation (PPT), the bronchial side of the DLT is pressurized during connection of the tracheal side to a beaker of water. Air bubbles will appear in the beaker in the absence of bronchial seal. The second technique, designated the CO2 analysis technique of bronchial cuff inflation (CAT), is based on analysis of CO2 content of gas sampled from the tracheal side of the DLT during ventilation of its bronchial side. When the bronchus is sealed, the normal CO2 waveform changes to a flat line. In the third technique, designated the negative pressure technique of bronchial cuff inflation (NPT), suction is applied to the tracheal side of the DLT. The absence of bronchial seal will result in collapse of the reservoir bag within a breathing system connected to the bronchial side of the tube. The bronchial sealing volumes were 1.1 +/- 0.9 mL, 0.9 +/- 0.7 mL, and 0.3 +/- 0.4 mL (mean +/- SD) when measured with the PPT, CAT, and NPT, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)