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Absence of positional change in pulmonary diffusing capacity in systemic sclerosis.
The American Journal of Medicine
|August 1, 1983
Summary
Systemic sclerosis patients show impaired pulmonary vascular function. Their lungs struggle to recruit or distend blood vessels, indicated by a lack of change in carbon monoxide diffusion capacity when changing positions.
Area of Science:
- Pulmonary Medicine
- Rheumatology
- Cardiovascular Physiology
Background:
- Systemic sclerosis (SSc) often presents with pulmonary abnormalities.
- Pulmonary vascular involvement is a recognized complication of SSc.
- The ability of the pulmonary vascular bed to recruit or distend in SSc is not well understood.
Purpose of the Study:
- To investigate the hypothesis that SSc patients have impaired pulmonary vascular recruitment/distensibility.
- To assess the postural change in carbon monoxide diffusing capacity (DLCO) in SSc patients.
Main Methods:
- Measured DLCO changes with postural shifts (sitting to supine) in 11 SSc patients.
- Compared results with age-, smoking-, and sex-matched rheumatoid arthritis (RA) patients and healthy controls.
- Utilized regression analyses to explore relationships between DLCO changes and other physiological parameters.
Main Results:
- Healthy subjects and RA patients showed significant DLCO increases (9.4% and 8.4%, respectively) when moving from sitting to supine.
- SSc patients exhibited no significant DLCO increase, irrespective of baseline pulmonary function.
- DLCO change correlated negatively with age in healthy subjects and positively with forced vital capacity in both SSc and RA patients.
Conclusions:
- SSc patients possess a nondistensible pulmonary capillary bed.
- The absence of a positional DLCO change is a subtle yet significant indicator of pulmonary vascular involvement in SSc.