PURPOSE: An arterio-venous fistula (AVF) raises mixed venous oxygen content and might thereby lessen the adverse consequences of venous admixture (physiological shunt) in patients with chronic lung disease. We hypothesized that therapeutic creation of an AVF in patients with severe COPD would thereby enhance oxygen delivery and improve exercise performance.
METHODS: We recruited 12 patients (10 men, 2 women) with severe COPD. Mean (SD) age was 66 (6) years, postbronchodilator FEV1 21 (8) %, DLCO 39 (14) %. Baseline PaO2 was 58 (3) mmHg and PaCO2 44 (5) mmHg breathing room air (RA). Exercise performance was assessed by 6-minute walking distance (dw6), breathing RA then supplemental oxygen (O2), at baseline, 6 weeks and 12 weeks after creating an AVF. Fistulas were created surgically (or percutaneously using a novel implantable device) in the iliofemoral region. Their luminal diameters ranged from 3 to 5 mm.
RESULTS: At baseline, O2 increased mean dw6 by 62 m (P=0.02). In 5 subjects (responders) there was a clinically meaningful increase >54 m. After creating the AVF, mean dw6 for all patients (breathing RA) increased by 56 m at 6 weeks (P=0.04) and by 59 m (P=0.02) at 12 weeks. Responders increased dw6 by 129 m at 6 weeks (P=0.02) and 124 m at 12 weeks (P<0.01). Non-responders showed insignificant changes in dw6 after 6 weeks (3 m) and 12 weeks (13 m). An exercise response to O2 at baseline was clearly associated with an exercise response to the fistula (Fisher's Exact P=0.02).
CONCLUSION: Therapeutic creation of an AVF increased exercise performance in COPD, presumably by raising mixed venous oxygen content and lessening the adverse consequences of venous admixture. Improved exercise performance breathing supplemental O2 predicted which patients obtained this unique benefit.
CLINICAL IMPLICATIONS: This study reveals that exercise performance in severe COPD can be improved by a simple procedure. Furthermore, patients likely to benefit may be selected by their response to supplemental O2 and a similar improvement in functional exercise capacity may be anticipated with a fistula.
DISCLOSURE: Christopher Cooper, Consultant fee, speaker bureau, advisory committee, etc. Consulting fee from ROX Medical; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. Creation of an arterio-venous fistula is considered an experimental technique in patients with COPD. The percutaneous device used in some patients in not yet approved for this purpose.