Selecting the Level of Positive End-expiratory Pressure for One-lung Ventilation: “By Formula” or “By Feel”?

Author: John Pfitzner, M.B.B.S., F.R.C.A.

Anesthesiology 12 2016, Vol.125, 1254-1255.

Blank et al  confirm that one-lung ventilation (OLV) is not without risk, but I have grave doubts about whether it is reasonable to conclude that “advances in our understanding of protective ventilation during OLV are likely to derive from well-designed randomized trials controlling for variables of inherent pathophysiologic significance.” The latter proviso, “controlling for variables of inherent pathophysiologic significance,” identifies the difficulties presented by the wide variety of respiratory pathophysiology seen in thoracic surgical patients, as has recently been pointed out in relation to another, unrelated issue of OLV.² 

Perhaps the quest for optimal protective ventilation should be directed more toward basic physiologic issues such as those identifiable in the now largely disregarded “art” of OLV. This particular “art” relied on three key aspects of two-handed manual ventilation with the adjustable “pressure relief valve” carefully adjusted to ensure that ventilation does not result in the standard adult 2-l reservoir bag progressively emptying or overfilling. First, judiciously applied manual ventilation enables the lung to be ventilated at the perceived optimal respiratory system dynamic compliance, as assessed by the ease with which gas is squeezed into it. (Incidentally, in the era before fiberoptic bronchoscopy was in clinical use for OLV, the clinical assessment of compliance [of both the ventilated lung and the “operated” lung] was invaluable for the optimal placement of a double-lumen tube.)