The effect of lateral positions on gas exchange in patients with unilateral lung disease during mechanical ventilation

Abstract

Positional changes have long been known to have a gravitational effect on the distribution of pulmonary blood flow. The effect of body position, supine, right and left lateral decubitus, on gas exchange were evaluated in 10 patients with predominantly unilateral lung disease. All patients were treated with mechanical ventilation and PEEP. Arterial blood gases, measured after 15 min in each of the three positions, showed that lying on the side of the "normal" lung resulted in a higher arterial pO2 (mean: 144 mmHg) than lying on that of the "damaged" lung (mean: 86 mmHg). The delta AapO2 values were 334 to 391 mmHg. Both differences were statistically significant (p less than 0.005). No significant changes mean arterial carbon dioxide tensions were noted.

A comparative study of supine lying, side lying and prone positioning on oxygen saturation, in mechanically ventilated patients, in acute respiratory failure

“…PO2 increases when the sick lung is up and PO2 decreases when sick lung is down. 7 This may be because positional changes have a gravitational effect on the distribution of pulmonary blood flow. Rivara studied 8 patients with unilateral interstitial pattern improvement in oxygenation which occurred when good lung was down is associated with changes in pattern of V/Q distribution, decrease in right to left intra pulmonary shunt.…”

“…Supine is the least helpful position for lung function. 7 For ventilated patients the lateral position increases FRC and enhances gas exchange compared with supine. 8 The prone position is useful for some severely hypoxic patients.…”

Evaluation of lung infiltration score to predict postural hypoxemia in ventilated acute respiratory distress syndrome patients and the lateralization of skin pressure sore

“…[4] Although asymmetry of the two-lung disease is not clear in these studies, we too did not Þ nd signiÞ cant changes in oxygenation in patients of bilateral lung inÞ ltrates till the LIS difference in the two lungs reached ≥3. It was noteworthy that the pulse oximetry did not change signiÞ cantly, probably due to upper ceiling of 100% saturation, but PaO 2 improved signiÞ cantly during better lungdown position.…”

“…[1][2][3] Hypoxemia (decreased arterial blood oxygen level) is reported during lateral positioning of patients with unilateral lung disease. [4][5][6][7] Acute respiratory distress syndrome (ARDS) is the most common pathology of respiratory failure in intensive care unit (ICU) requiring mechanical ventilation. The syndrome is characterized by refractory hypoxemia with bilateral diffuse inÞ ltrates in lungs on chest x-ray.…”

“…[8] Although radiographically and by deÞ nition, ARDS is a bilateral lung disease, blood oxygenation (PaO 2 ) in 5 of the 6 studied patients differed during lateral positioning, suggesting asymmetric lung involvement. [9] Since variable effects on oxygenation during lateral positioning of patients have been reported, [4,[10][11][12][13] the effects of lateral positioning of ARDS patients are unclear. After extensive literature search, we did not find a method to quantify or predict the asymmetry of the lung disease.…”