Positive end-expiratory pressure during one-lung ventilation improves oxygenation in patients with low arterial oxygen tensions

Cardiopulmonary effects of positive end-expiratory pressure during one-lung ventilation in anesthetized dogs with a closed thoracic cavity

“…Consequently, augmentation of the calculated CaO 2 was extremely limited because PaO 2 is only a negligible component in the equation to calculate CaO 2 . In a study 37 in humans, the application of PEEP improved PaO 2 only in patients with a low PaO 2 (< 80 mm Hg) but not in patients with an initial PaO 2 > 80 mm Hg. 37 The proposed reason for this effect is that hypoxemic patients are more likely to have lung volumes below the FRC with increased PVR.…”

“…In a study 37 in humans, the application of PEEP improved PaO 2 only in patients with a low PaO 2 (< 80 mm Hg) but not in patients with an initial PaO 2 > 80 mm Hg. 37 The proposed reason for this effect is that hypoxemic patients are more likely to have lung volumes below the FRC with increased PVR. With the use of PEEP, lung volume approaches FRC, which results in a decrease of PVR and an increase of blood flow to the dependent lung.…”

Arterial oxygenation and one-lung anesthesia

“…These include HPV [20 ] that limits nonventilated lung shunt, administration of positive end-expiratory pressure (PEEP) to the dependent lung [21][22][23] and correct positioning of double lumen tubes [24]. A number of authors have demonstrated the benefit of dependent lung PEEP when titrated to restore functional residual capacity [21,22,25], whereas administration of predetermined [26] or excessive amounts of PEEP [22] does not always improve arterial oxygenation. Whereas the aforementioned are all important determinants of arterial oxygenation during OLA, this article will focus on the other, less frequently discussed, issues that appear in Equation 5.…”

“…Increasing alveolar ventilation using larger tidal volumes is theoretically attractive as it may also prevent small airway closure and the development of low ventilation perfusion units that result from the decrease in dependent lung volume during OLA [1]. The use of larger (15 ml/kg) [55] and smaller tidal volumes [56,57] during OLA have been linked with increases and decreases, respectively, in arterial oxygenation; however, utilizing larger tidal volumes has not universally resulted in statistically significant [4, [58][59][60] or clinically important [21,55] increases in arterial oxygenation. The reasons for this conflicting evidence include firstly that increases in lung volume lead to increases in pulmonary vascular resistance and diversion of blood flow toward the nonventilated lung [4, 21,25,[58][59][60].…”

The effect of positive end expiratory pressure on the respiratory profile during one‐lung ventilation for thoracotomy*

“…Interestingly, there appears to be an identifiable patient subgroup that would benefit from PEEP [13] -those with low arterial oxygen tensions during OLV.…”