The need to better understand the physiology of lung collapse during one-lung ventilation

Excerpt

In their challenging study conducted on 39 patients undergoing one-lung ventilation (OLV), Moreault et al. have succeeded in “highlighting the need to better understand the physiology of lung collapse during OLV”.1 My letter addresses but one of the many thought-provoking volume and airway pressure findings: following the initiation of OLV and before pleural opening, the volume of “gaseous influx” into the non-ventilated lung from a measuring ambient air reservoir was greater when it occurred via the narrow-bore internal channel of a bronchial blocker (BB) than via the wide lumen of a double lumen endotracheal tube (DL-ETT) (contrary to one of the researchers’ two hypotheses).1 This totally unexpected finding could conceivably be a consequence of the “tidal gas movement” that will have been occurring via the DL-ETT lumen,2 but not to any meaningful degree via the long narrow-bore internal channel of the BB. “Paradoxical ventilation” occurs in association with the “tidal gas movement” and has been shown (as a single picture “saying a thousand words”) to be necessarily associated with an influx of ambient nitrogen into the non-ventilated lung.3 This could well have resulted in an earlier initiation of hypoxic pulmonary vasoconstriction in the non-ventilated lung in the studies with the wide-bore DL-ETT, with a consequent reduction in pulmonary blood flow that resulted in a lesser ongoing “gaseous influx” than might otherwise have occurred. …