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Am J Kidney Dis. 2011 Jan;57(1):113-22. doi: 10.1053/j.ajkd.2010.06.026. Epub 2010 Sep 25.

Effects of modality change and transplant on peak oxygen uptake in patients with kidney failure.

Author information

1
University of Minnesota, Minneapolis, 55455, USA. tpainter@umn.edu

Abstract

BACKGROUND:

Exercise capacity as measured by peak oxygen uptake (Vo₂(peak)) is low in hemodialysis patients. The present study assesses determinants of VO₂(peak) in patients with chronic kidney failure who either changed kidney replacement modality to frequent hemodialysis therapy or received a kidney transplant.

STUDY DESIGN:

Cohort study with assessment at baseline and 6 months after modality change.

SETTING & PARTICIPANTS:

Participants included nondiabetic individuals receiving conventional hemodialysis who: (1) remained on conventional hemodialysis therapy (n = 13), (2) changed to short daily hemodialysis therapy (n = 10), or (3) received a transplant (n = 5) and (4) individuals who underwent a pre-emptive transplant (n = 15). Additionally, 34 healthy controls were assessed at baseline only.

PREDICTOR:

Modality change.

MEASUREMENT & OUTCOMES:

Exercise capacity, assessed using the physiologic components of the Fick equation (Vo₂ = cardiac output × a-vo₂(dif), where a-vo₂(dif) is arterial to venous oxygen difference) was determined using measurement of Vo₂(peak) and cardiac output during symptom-limited exercise testing. Analysis of covariance was used to compare differences in changes in Vo₂(peak), cardiac output, heart rate, stroke volume, and a-vo₂(dif) at peak exercise between participants who remained on hemodialysis therapy and those who underwent transplant.

RESULTS:

Transplant was the only modality change associated with a significant change in Vo₂(peak), occurring as a result of increased peak cardiac output and reflecting increased heart rate without a change in peak a-vo₂(dif) despite increased hemoglobin levels. There were no differences in participants who changed to daily hemodialysis therapy compared with those who remained on conventional hemodialysis therapy.

LIMITATIONS:

Small nonrandomized study.

CONCLUSIONS:

Vo₂(peak) increases significantly after kidney transplant, but not with daily hemodialysis; this improvement reflects increased peak cardiac output through increased peak heart rate. Despite statistical significance, the increase in Vo₂(peak) was not clinically significant, suggesting the need for interventions such as exercise training to increase Vo₂(peak) in all patients regardless of treatment modality.

Comment in

PMID:
20870330
PMCID:
PMC3010466
DOI:
10.1053/j.ajkd.2010.06.026
[Indexed for MEDLINE]
Free PMC Article
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