Abstract: SA-PO448

Near-Infrared Spectroscopy Measured Muscle Haemoglobin O2 Saturation Kinetics and Physical Performance in CKD

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 306 CKD: Cognitive Dysfunction, Depression, Quality of Life

Authors

  • Wilkinson, Thomas James, University of Leicester, Leicester, United Kingdom
  • White, Alice em, University of Leicester, Leicester, United Kingdom
  • Nixon, Daniel, University of Leicester, Leicester, United Kingdom
  • Gould, Douglas W., University of Leicester, Leicester, United Kingdom
  • Watson, Emma L., University of Leicester, Leicester, United Kingdom
  • Smith, Alice C., John Walls Renal Unit, Leicester General Hospital, Leicester, United Kingdom
Background

CKD patients have poor exercise capacity. A possible factor may be an imbalance in muscle oxygen (O2) supply and utilisation, moderated by mitochondrial and endothelial dysfunction. Near-infrared spectroscopy (NIRS) can be used to measure in vivo muscle oxidative metabolism. Using NIRS we investigated gastrocnemius skeletal muscle O2 kinetics in non-dialysis CKD patients during exercise.

Methods

30 patients (59±16 yrs; 11 female; eGFR: 54±26 mL/min/kg/1.73m2) completed the incremental shuttle walk test. NIRS measured light attenuation in the near-infrared spectrum and determined chromophores, primarily % of oxygenated haemoglobin present in the muscle (SMO2%). SMO2% was assessed before, during, and after (recovery) exercise. Resting cardiac parameters were assessed, along with habitual physical activity (PA). Patients were divided into aerobic capacity tertiles to determine SMO2% differences.

Results

From baseline, SMO2% declined by 12±7% during exercise before rapidly recovering upon cessation (Fig 1). Controlled for age, sex and eGFR, patients with higher aerobic capacity took 258 (56-461) secs (55%) longer (P=.016) to reach minimum SMO2%, and recovered 49 (2-96) secs (75%) quicker (P=.040) than those with lower aerobic capacity. Better SMO2% kinetics were associated with higher stroke volume and PA levels, and lower peripheral resistance.

Conclusion

Superior SMO2% kinetics (i.e. slower deoxygenation rate, quicker recovery) are associated with greater exercise capacity, better vasculature, and higher PA in CKD. The dysfunctional kinetics observed may indicate endothelial dysfunction and an inability of mitochondria to efficiently carry out oxidative phosphorylation. Accordingly, NIRS is a low-cost and non-invasive means to evaluate O2 kinetics and could be a useful tool to measure oxidative metabolism mechanisms in CKD.

Funding

  • Private Foundation Support