One-lung ventilation physiology and the hypoxaemia management algorithm

Also known as OLV hypoxaemia · One-lung ventilation algorithm · Double-lumen tube hypoxaemia

OLV shunt physiology, hypoxic pulmonary vasoconstriction, DLT versus bronchial blocker principles, lung-protective OLV settings, and the stepwise hypoxaemia algorithm for fellowship exams.

high7 referencesUpdated 26 July 20268 min readVerification in progress

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10 MCQs

The one-line answer

One-lung ventilation creates an obligatory true shunt through the non-ventilated lung, moderated by hypoxic pulmonary vasoconstriction. Licker describes HPV redirecting blood from the upper non-ventilated hypoxic lung to the dependent ventilated lung, limiting shunt and optimising V/Q to attenuate the PaO2 fall.^[1] Treat hypoxaemia in local-protocol order: raise FiO2 to 1.0, do a fibreoptic position check, suction, apply PEEP to the ventilated lung (Abe: PaO2 rose after 4 cm PEEP during propofol OLV^[2]), CPAP to the non-ventilated lung (Maroof: CPAP 5–10 cmH2O to the non-ventilated lung raised SaO2 above 90% in all 10 patients who had failed 100% oxygen to that lung^[6]), recruit, revert to intermittent two-lung ventilation if critical, and consider propofol to spare HPV (Abe: shunt fell after conversion from volatiles to propofol^[2]; Pruszkowski: BIS-titrated sevoflurane vs propofol had similar PaO2^[3]).

Meet the patient

A 68-year-old is in the lateral position for a right upper lobectomy. Five minutes after you isolate the lung, the saturation falls to 87 percent. The surgeon is asking for the field. Your registrar reaches for the volatile dial to deepen.^[1]

The two questions every OLV crisis hangs on: is the tube still where you put it, and have you told the surgeon? Most hypoxaemia is malposition or secretions, and climbing volatile to deepen a hypoxic patient is the wrong first move.^[1]

References7Show

[1]Licker M, Hagerman A, Jeleff A, Schorer R, Ellenberger C The hypoxic pulmonary vasoconstriction: From physiology to clinical application in thoracic surgery. Saudi Journal of Anaesthesia, 2021.PMID 34764832
[2]Abe K, Shimizu T, Takashina M, Shiozaki H, Yoshiya I The effects of propofol, isoflurane, and sevoflurane on oxygenation and shunt fraction during one-lung ventilation. Anesthesia and Analgesia, 1998.PMID 9806702
[3]Pruszkowski O, Dalibon N, Moutafis M, Jugan E, Law-Koune JD, Laloë PA Effects of propofol vs sevoflurane on arterial oxygenation during one-lung ventilation. British Journal of Anaesthesia, 2007.PMID 17347180
[4]El Tahan MR, Pasin L, Marczin N, Landoni G Impact of Low Tidal Volumes During One-Lung Ventilation. A Meta-Analysis of Randomized Controlled Trials. Journal of Cardiothoracic and Vascular Anesthesia, 2017.PMID 28843606
[5]Brodsky JB, Macario A, Mark JB Tracheal diameter predicts double-lumen tube size: a method for selecting left double-lumen tubes. Anesthesia and Analgesia, 1996.PMID 8615510
[6]Maroof M, Khan RM, Bhatti TH CPAP with air and oxygen to non-ventilated lung improves oxygenation during one lung anaesthesia. Journal of the Pakistan Medical Association, 1995.PMID 7602743
[7]Sentürk M, Layer M, Pembeci K, Toker A, Akpir K, Wiedemann K [A comparison of the effects of 50 % oxygen combined with CPAP to the non-ventilated lung vs. 100 % oxygen on oxygenation during one-lung ventilation]. Anasthesiologie, Intensivmedizin, Notfallmedizin, Schmerztherapie : AINS, 2004.PMID 15197670