Blood, 1 February 2003, Vol. 101, No. 3, pp. 787-787
Sleep tight, keep the oxygen right
The search for clinical and laboratory findings that predict
the severity of sickle cell disease has been, in some ways, overly successful. Studies have associated future adverse events with unusually severe anemia, low fetal hemoglobin (HbF) levels, high white
cell counts, and early complications. Determining which of these
factors is most closely linked to outcome becomes increasingly important for the development of effective therapy.
In this issue, Hargrave and colleagues (page 846) have added nocturnal
hypoxemia to the list of causative, and potentially treatable, factors.
Extending their previous work that demonstrated a relationship between
nocturnal hypoxemia and central nervous system complications in sickle
cell disease, the investigators now show a remarkable link between
nocturnal hypoxemia and painful crises. In 95 children and adolescents,
a variety of measures of nocturnal hypoxemia are significantly
associated with the number of inpatient days for management of pain.
Mean oxygen saturation during sleep emerges as the key predictor of
painful crises after adjusting for such factors as total hemoglobin
level, HbF level, and white cell count. For each increase of one unit
in the mean nocturnal oxygen saturation between 85% and 100%, the
number of inpatient days for pain falls by 0.83. The study also
provides an important note of caution for those who favor surgical
solutions. Tonsillectomy and adenoidectomy did not reduce the frequency
of crises in patients with upper airway obstruction unrelated to recurrent infections.
For many decades, sickle cell disease represented the classic gap
between an understanding of the pathophysiology of a disease and the
development of effective treatment. Investigators have closed this gap
as chronic transfusion therapy, prophylactic penicillin, HbF
enhancers, bone marrow transplantation, membrane-active agents, and
hemorheological drugs have entered clinical trials or clinical practice. An important outgrowth of these developments is the need to
determine which approach has a sufficiently broad therapeutic impact to
prevent many of the major complications of sickle cell disease and,
therefore, to improve the overall quality and length of life of
affected patients. Hargrave et al are presently taking the crucial next
step to determine whether the overnight administration of oxygen is
beneficial and deserves a place in the rapidly developing armamentarium
of new treatments for sickle cell disease.
Alan R. Cohen
Children's Hospital of
Philadelphia
