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Guidelines for Determining the Appropriateness of Double-Lumen Endobronchial Tube Size

2002; Lippincott Williams & Wilkins; Volume: 95; Issue: 2 Linguagem: Inglês

10.1097/00000539-200208000-00063

1526-7598

Jae-Hyon Bahk,

Esophageal and GI Pathology

To the Editor: When the bronchial cuff of a double-lumen endobronchial tube (DLT) is inflated using the standard underwater seal technique, testing for air leak is performed before and during bronchial cuff inflation by pressurizing the bronchial side to a peak airway pressure of 25–30 cmH2O while connecting the tracheal side to a 1-cm underwater seal (1–3). The DLT size has been considered appropriate for the individual patient if the following two criteria are met (2,3): 1) some air leak is detected when the bronchial cuff deflated, indicating that the tube was not tightly wedged in the bronchus; 2) airtight seal of the bronchus is obtained with less than the resting volume, because this cuff may lose its low-pressure characteristics if inflated to a volume larger than the resting volume (4). However, these guidelines do not cover all the possible situations, so I would like to add a few more to the above criteria. When the development of a wrinkle in the cuff creates a channel for gas to escape around the cuff, intracuff pressure must be increased in order to obliterate the wrinkle (5). Frequently, however, airtight seal could not be obtained despite inflating the DLT bronchial cuff to relatively large volumes that resulted in the very high intracuff pressure (6). If high intracuff pressures and persistent leak ensue with the injection of less than, but near the resting volume, it seems that the bronchial cuff cannot be molded to the bronchus. If some air leak is detected with the bronchial cuff deflated, but high intracuff pressure follows a small change in the cuff volume with persistent air leak, it appears that the DLT size is appropriate but relatively large for the bronchus, therefore the wrinkle on the cuff cannot be unfolded. In this case, based on the clinical requirement of watertight isolation, a decision to change for a smaller DLT may be made. To prevent ischemic bronchial injury and achieve as much airtight seal as possible, the intracuff pressure should be <44 cmH2O, at which the mucosal capillary perfusion was reported to decrease (7), and the cuff inflation volume should be less than the resting volume, regardless of whichever comes first. When air leak is not detected even with the bronchial cuff totally collapsed, there could be two explanations for this. One is that the DLT is tightly wedged into the bronchus, in which case the DLT should be changed for a smaller one, and the other is that the tube size is appropriate, but the frill-like folds, formed at the ends of the cuff, work as a barrier to leak. One way to differentiate between the two circumstances is to inject a small amount of air much less than the resting volume and check the intracuff pressure: when the intracuff pressure is lower than the pressure that decreases mucosal perfusion, the tube size should be determined to be adequate. Using all the above-mentioned criteria, the risk of bronchial injury or the erroneous judgments to change a DLT can be minimized. Jae-Hyon Bahk, MD