Effect of posture on lung volume: airway closure and gas exchange in hemidiaphragmatic paralysis.

Abstract

The effects of posture on lung volume, airway closure, and gas exchange were studied in eight patients with hemidiaphragmatic paralysis. The mean vital capacity in the sitting position was 81% of predicted normal, and in the supine posture fell by a further 19% in right-sided but only 10% in left-sided paralysis. The mean arterial oxygen tension was less than predicted in the sitting posture and fell significantly on lying. Single breath gas transfer factor was normal in all cases whereas the diffusion coefficient was greater than predicted in the sitting posture and rose even further on lying. Closing volume showed no positional change but closing volume as a percentage of vital capacity was higher in the supine position. Regional airways closure was expressed as the relationship expiratory reserve volume minus closing volume. Negative values were found in only two of the subjects in the sitting position but seven had negative values supine, indicating significant airway closure during tidal breathing in this position.

Nocturnal Hypoxia in Unilateral Diaphragmatic Paralysis

“…The reduction in VC observed in our patients without concomitant lung disease is similar to those reported by Lisboa et al [4] and greater than those reported by Clague and Hall [3]. The decrease in lung volumes ob served by Gould et al [9] in acute UDP induced by phrenic nerve blockade (14% for VC) was also less than that measured in most of our patients.…”

“…Laroche et al [14] demonstrated that the mean maximum increment in transcutaneous C 0 2 was within normal limits. Clague and Hall [3] have shown that the closing volume (CV) as a percentage of VC tended to be less than predicted in patients with UDP. Because of the reduction in expiratory reserve volume (ERV), the relationship ERV/CV was much less than predicted, being negative in several patients in the supine position.…”

“…There are reduc tions in ventilation and perfusion of the lower lobe on the affected side leading to some mismatching and widening of alveolar-arterial oxygen difference and mild hypoxemia. These findings deteriorate in the su pine position [1][2][3]. Arterial oxygen tension is signifi cantly below normal in the supine position but often in the normal range in the sitting position.…”

Efficacy of intra-operative unilateral diaphragm plication for patients undergoing unilateral phrenicotomy during extended surgery

“…A diaphragm paralysis due to phrenicotomy causes decreases in tidal volume and in dynamic lung compliance, and an increase in the work of breathing due to paradoxical movements of the paralysed diaphragm [5][6][7], which may lead to increases in postoperative morbidity and motility. Diaphragm plication is an acceptable treatment for paediatric patients with life-threatening unilateral diaphragm paralysis [8][9][10], while benefits have also been reported in adult patients with chronic unilateral diaphragm paralysis [1,11].…”

To Sink the Lifted: Selection, Technique, and Result of Laparoscopic Diaphragmatic Plication for Paralysis or Eventration

“…In healthy individuals, a decrease in FVC of up to 20% may be observed in the supine position when compared with upright values 19 ; in symptomatic patients with diaphragmatic paralysis, supine FVC may decrease by 20 to 50% when compared with upright values. [19][20][21][22] The main value of PFTs in the evaluation of symptomatic patients with hemidiaphragmatic elevation is to provide an objective evaluation of the response to surgery; however, changes in PFT values are variable, are not critical for patient selection, and do not always correlate well with clinical improvement.…”