Oxygen uptake during activities of daily life in patients treated with a left ventricular assist device

Introduction: Oxygen consumption during activities of daily life (ADL) is not described in recipients of left ventricular assist device (LVAD). We aimed to investigate the relation between oxygen consumption during predefined ADLs and measures of functional capacity (FC) in stable-phase LVAD recipients.

Methods: LVADs and controls were matched on gender, age, BMI, smoking status, and ethnicity. VO₂ was measured using mobile equipment (K5, Cosmed, Rome, Italy) while putting on vest and LVAD equipment(1), folding towels(2), putting on socks and shoes(3), putting bottles in a cupboard(4), making a bed(5), walking on stairs without(6) and with extra weight(7), and sweeping the floor(8). Submaximal FC was tested by means of 6 minute walk test (6MWT) and peak oxygen uptake (pVO₂) to test maximal FC.

Results: Fifteen LVAD patients and 16 controls were included; Patients were 61 ± 10years, all males with BMI 28 ± 5kg/m² and implanted with Heartmate 3 (DT: 60%). PVO₂ was 14.9 ± 2.2 ml/kg/min in patients and 39.6 ± 7.7 in controls (p < 0.001). Oxygen consumption expressed as percent of pVO₂ for each task in patients vs controls was (%): ADL1: 41 ± 5 vs 21 ± 4, ADL2: 41 ± 6 vs 22 ± 5 %, ADL3: 50 ± 16 vs 24 ± 5%, ADL4: 45 ± 12 vs 22 ± 4, ADL5: 50 ± 8 vs 23 ± 4, ADL6: 66 ± 10 vs 30 ± 4, ADL7: 65 ± 10 vs 31 ± 5, ADL8: 75 ± 10 vs 39 ± 12, (p < 0.001 for all). During 6MWT LVAD patients used 96% ± 8 % of their pVO₂.

Conclusion: Recipients of durable LVADs perform daily life activities at oxygen uptake levels much closer to their peak cardiopulmonary reserve than matched healthy controls.