Key result
Patients with COPD had significantly lower leg blood flow during small muscle mass exercise compared to healthy controls (1.82 vs. 2.36 l/min; P<0.05).
Why the study?
Does moderate to severe COPD impair leg blood flow during small muscle mass exercise compared to healthy controls?
Observational (n=18)
Does moderate to severe COPD impair leg blood flow during small muscle mass exercise compared to healthy controls?
Absolute Event Rate: 1.82% vs 2.36%
p-value: p=<0.05
Patients with COPD have impaired leg muscle blood flow during small muscle mass exercise, potentially driven by altered vasoactive compound profiles including increased endothelin-1 and impaired prostacyclin formation.
May indicate impaired leg perfusion in COPD during exercise; hypothesis-generating for vascular mechanisms, needs prospective confirmation.
Skeletal muscle blood flow is regulated to match the oxygen demand and dysregulation could contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). We measured leg hemodynamics and metabolites from vasoactive compounds in muscle interstitial fluid and plasma at rest, during one-legged knee-extensor exercise, and during arterial infusions of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively. Ten patients with moderate to severe COPD and eight age- and sex-matched healthy controls were studied. During knee-extensor exercise (10 W), leg blood flow was lower in the patients compared with the controls (1.82 ± 0.11 vs. 2.36 ± 0.14 l/min, respectively; P < 0.05), which compromised leg oxygen delivery (372 ± 26 vs. 453 ± 32 ml O 2 /min, respectively; P < 0.05). At rest, plasma endothelin-1 (vasoconstrictor) was higher in the patients with COPD ( P < 0.05) and also tended to be higher during exercise ( P = 0.07), whereas the formation of interstitial prostacyclin (vasodilator) was only increased in the controls. There was no difference between groups in the nitrite/nitrate levels (vasodilator) in plasma or interstitial fluid during exercise. Moreover, patients and controls showed similar vasodilatory capacity in response to both endothelium-independent (SNP) and endothelium-dependent (ACh) stimulation. The results suggest that leg muscle blood flow is impaired during small muscle mass exercise in patients with COPD possibly due to impaired formation of prostacyclin and increased levels of endothelin-1. NEW & NOTEWORTHY This study demonstrates that chronic obstructive pulmonary disease (COPD) is associated with a reduced blood flow to skeletal muscle during small muscle mass exercise. In contrast to healthy individuals, interstitial prostacyclin levels did not increase during exercise and plasma endothelin-1 levels were higher in the patients with COPD.
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Iepsen et al. (2017) conducted an observational in Chronic obstructive pulmonary disease (COPD) (n=18). Moderate to severe COPD vs. Age- and sex-matched healthy controls was evaluated on Leg blood flow during knee-extensor exercise (10 W) (p=<0.05). Patients with COPD had significantly lower leg blood flow during small muscle mass exercise compared to healthy controls (1.82 vs. 2.36 l/min; P<0.05).
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