The effect of body position on pulmonary ventilation and respiratory gas exchange

O'Reilly, Liam (2018). The effect of body position on pulmonary ventilation and respiratory gas exchange. University of Birmingham. M.Sc.

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Abstract

This study looked at the potential use of supine gas transfer measurements using carbon monoxide and nitric oxide, and positional structured light plethysmography (SLP), in detecting the location and severity of emphysematous destruction within the lungs.

Healthy normal subjects (n=95) were compared to those with Alpha-1 antitrypsin deficiency (A1AD) (n=64), a genetic condition known to cause emphysema. There were statistically significant differences observed in the A1AD group when tested in the supine position, with decreases seen in TL\(_{NO}\), VAeff, and TL\(_{NO}\)/TL\(_{CO}\) of 10%, 10% and 4.1% respectively. There was a significant increase in K\(_{CO}\) for both the healthy controls and A1AD group of 12.6% and 6.2% respectively. There was no significant change in K\(_{NO}\) from seated to supine in any study group. Disease severity had a significant impact on transfer measurements whilst in the supine position. A1AD subjects with airflow obstruction (OBA1) showed significant changes to TL\(_{CO}\) (- 12.6%) compared to non-obstructive A1AD subjects (NOA1) (-4.0%). All subject groups showed statistically significant postural changes for K\(_{CO}\) and TL\(_{NO}\) showed significant postural changes for both groups of A1AD subjects. K\(_{NO}\) showed no significant changes between postures for any of the three cohorts.

Measurements using SLP showed that all subject groups demonstrate asynchronous, abdominally dominant breathing movements whilst supine. There was a significant decrease in ribcage contribution (RCC%) and upper ribcage contribution (URCC%) in healthy controls (- 35.8%), NOA1 (-32.7%), and OBA1 (-26.0%).

These findings validate current understanding of gas transfer measurements in healthy controls and emysematous disease and measurements using Nitric Oxide/Carbon Monoxide and SLP measurements provide additional insight into patients disease location and severity and therefore, would be of value to be used as part of patient’s clinical investigations.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):