Abstract
The relationship between hemoglobin dexoygenation and sickling is well known. However, the relationship between hypoxia and severity of disease in sickle cell patients has not been well established. Recently, nocturnal hypoxemia has been associated with higher incidence of CNS events including strokes, and elevated TCDs. We present our case series on 13 patients(12 SS, 1 SC) with sickle cell disease (SCD) who have nocturnal hypoxia. Approximately 75 patients were screened at the University of Michigan Sickle Cell clinic for nocturnal hypoxia either by symptoms of obstructive sleep apnea or by longitudinal baseline clinic 02 saturations (02 Sat <92%). Of the 13 hypoxic pts, median baseline O2 Sat 90%(n=13, mean 90) and the median nocturnal O2sat (Nctnl 02 sat) 84%(n=13, mean 80%) with 10/13 with moderate-severe nocturnal hypoxia (O2sats<85%)based on sleep studies. Multiple adverse events noted in the cohort were pulmonary hypertension (PHTN TRJV>2.5, n=9, median 2.74/mean 2.74,) frequent pain episodes(>3visits to ER or hospitalizations/year, n=7, with 5 pts >5/year ), recurrent acute chest syndrome( ≥ 3 episodes, n= 10), CNS events (n=3 silent infarcts, vascular stenosis), priapism( (n=4, among 6 males ). Also reported were possible causes of the underlying hypoxia including obstructive sleep apnea(OSA)(n=7 of 11 pts), asthma(n= 10 of 13 pts), and chronic lung disease( n=8). In conclusion, the persistence of nocturnal hypoxia in pediatric sickle cell disease could possibly contribute to the development of severe complications of sickle cell disease. Treatment of underlying hypoxia (ie nighttime oxygen, maximize asthma treatment, T&A for OSA)may help prevent complications and lead to the improvement clinical symptoms. Further, chronic nocturnal hypoxia may complicate pulmonary disease and accelerated the development of PHTN. More studies are needed to clarify the mechanism of hypoxia in SCD.
Table I. Clinical &Demographic Data of 13 SCD Patients with Nocturnal Hypoxia. Age:(6–22y/o, mean 15) Sex: M=6 F=7 Clinical: Total Mild Mod Sev. Genotype: SS=12, SC=1 Mean Range Nctnl Hypoxia(<%) 13 3 5(<85) 5(<80) Baseline O2 Sat(%) 90 +3.0 86–97 Obstr Sleep Apnea 7 3 3 1 Nctnl 02 sat (%) 80+8.4 59–87 Pulm HTN 9 4 4 1 Total #Apneic Events(11) 65.6+80 6–256 Rest. Lung Ds. 8 2 5 1 Obstr. Apneic Events(7) 27+68.5 0–221 # of Episodes <3 3–4 >4 Hypopneic Events(9) 32.5+38 0–132 ACS 2 5 5 TRJet Velocity 2.74+.42 2–3.5 Severe Pain Crises/yr 1 2 5
Nocturnal Hypoxemia Rather Than Obstructive Sleep Apnea Is Associated With Decreased Red Blood Cell Deformability and Enhanced Hemolysis in Patients With Sickle Cell Disease
