Elastic behavior of the transplanted lung. Exponential analysis of static pressure-volume relationships.
We compared indices of muscle strength, parameters of mechanical lung function, and static pressure-volume curves in 12 heart-lung transplant (HLT) recipients to determine whether observed restrictive ventilatory defects represented abnormal elastic behavior of the transplanted lungs. Pressure-volume curves were analyzed using an exponential equation to generate the shape constant K, which describes the nonlinear behavior of pressure-volume relationships over a substantial range. For the group, K was 91% predicted, implying that there was not a diffuse abnormality of elastic properties of the transplanted lungs despite a mean TLC of 80% predicted. However, the mean maximal transpulmonary pressure (PLmax) was significantly low at 23.4 cm H2O (61% predicted) possibly related to the effects of surgery on thoracic cage mobility, but also in keeping with a reduction in power and efficiency of the thoracic musculature. The ability to achieve predicted TLC post-HLT was related to the preservation of optimal inspiratory force as TLC (% predicted) was highly correlated with maximal inspiratory pressure (PImax) (% predicted) (r = 0.83) (p less than 0.001). The ratio (TLC post-HLT)/(TLC pre-HLT) was 1.00 +/- 0.18 (r = 0.82) (p less than 0.005), suggesting donor organs were well matched to recipient chest cavities, but also emphasizing that the recipients had a low TLC prior to HLT. We conclude that the presence of a stable restrictive defect post-HLT is determined primarily by the volumetric constraints of the recipient chest cavity and within these constraints by the strength and efficiency of the thoracic musculature rather than a diffuse intrinsic abnormality of pulmonary elastic properties as a consequence of the transplantation process.
Glanville
A R
AR
Department of Medicine, Stanford University School of Medicine, California.
Theodore
J
J
Harvey
J
J
Robin
E D
ED
D000293:Adolescent; D000328:Adult; D001989:Bronchiolitis Obliterans / Q000503:physiopathology; D005260:Female; D016027:Heart Transplantation; D006801:Humans; D008168:Lung / Q000502:physiology*; D008170:Lung Compliance; D016040:Lung Transplantation; D008297:Male; D008433:Mathematics; D009132:Muscles / Q000502:physiology; D012129:Respiratory Function Tests; D013909:Thorax / Q000502:physiology