The Resting Volume and Compliance Characteristics of the Bronchial Cuff of Left Polyvinyl Chloride Double-Lumen Endobronchial Tubes

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Abstract

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. The smallest resting volumes were measured in the Rusch tubes and the large Mallinckrodt and Sheridan tubes. The largest resting volumes were measured in the smallest Mallinckrodt and the large Portex tubes. Mean bronchial cuff pressure at 3-mL volume, contrary to the cuff resting volume, varied proportionately with the tube size in the Mallinckrodt and Sheridan DLTs and varied inversely with the tube size in the Rusch and Portex DLTs. The compliance decreased significantly when the cuff was inflated inside tightly fitting canine bronchi. In conclusion, maintenance of the low-pressure characteristics of the bronchial cuff of PVC DLTs requires awareness of the specific resting volume for each tube size and brand to avoid inflating the cuff beyond that volume. If the tube is tightly fitting inside a bronchus, maintenance of the cuff low-pressure characteristics may require limiting cuff inflation to volumes smaller than the resting volume.

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