Sickle cell anaemia: exchange transfusions increased exercise tolerance.

Clinical bottom line (level 5)

  1. Patients with sickle cell anaemia and low levels of HbA, who were given partial exchange blood transfusions had an increased exercise capacity.
  2. The clinical relevance of such a finding is unknown.
Miller et al: Blood 1980; 56 (6): 1127-1131
Expires May 2004

The study

Inception cohort study with unblinded, unobjective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.
Setting: clinical centre, USA

19 patients (aged ?, ?% male) sickle cell anaemia, chosen not to reflect the severity of the disease

Excluded if
  • veins not accessible
  • unable to perform exercise test without undue discomfort


    • Note:
  • Patients underwent exercise tolerance tests. Exercise tolerance was measured by submaximal exercise tolerance (i.e. the level at which lactate was produced by the muscle).
  • None of the patients had been on a transfusion program or transfused in the previous six weeks.


    • Control Group: (n = 9, 9 analysed): normal controls, unmatched for age and sex
    Experimental Group: (n = 10, 10 analysed): partial exchange transfusion performed, where 5-6 units of packed red blood cells were used to replace patient's whole blood. Patient's plasma was extracted from the donation and returned.

    100% followed for 3 days

    The evidence

    Outcome Control Group
    (SD)    		 Experimental Group
    (SD)    		 Mean Difference
    (95% CI)
    anaerobic threshold (watts) 68.2
    (26.2)     		114
    (28.6)     		46
    (19 to 72)
    work performed at heart rate 170 (watts) 128
    (39.5)     		187
    (48.4)     		59
    (16 to 102)

  • It is unlikely that exercise capacity increased due to a rise in haemoglobin. Haemoglobin rose, on average, by 1.44 g/dl, but fell in two of ten patients.
  • The control group of normal subjects had an anaerobic threshold of 131 watts.
  • HbA was 9% pre-transfusion and 55% post-transfusion.
  • There was no comparison made with simple transfusion.

    • Citation

    1. Miller DM, Winslow RM, Klein HG, et al: Improved exercise performance after exchange transfusion in subjects with sickle cell anemia. Blood 1980; 56 (6): 1127-1131
    Contributor: Nick Shenker and Clare Wotton, May 2000
    Reviewer:

    Clinical Question.
    Patient sickle cell anaemia
    Intervention or Exposure partial exchange blood transfusions
    Outcome exercise tolerance