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Severe nocturnal and postexercise hypoxia in children and adolescents with sickle cell disease
Isabelle Halphen1, Caroline Elie2, Valentine Brousse3
1Pediatric Emergency Department, Hospital Necker, APHP, Paris, France.
Insights
Hypoxia is common in children with sickle cell disease (SCD), affecting 36% during the day and 50% at night. This study highlights the prevalence of nocturnal and postexercise hypoxia in pediatric SCD patients.
Area of Science:
- Pediatric Hematology
- Cardiopulmonary Medicine
- Sickle Cell Disease Research
Background:
- Hypoxia is a recognized complication in pediatric sickle cell disease (SCD).
- The association between hypoxia and clinical manifestations like painful crises and acute chest syndrome in SCD is inconsistent.
- Understanding the prevalence and risk factors of hypoxia is crucial for managing SCD in children.
Purpose of the Study:
- To determine the prevalence of daytime, nocturnal, and postexercise hypoxia in children with SCD.
- To identify potential risk factors associated with hypoxia in this population.
- To explore the relationship between hypoxia and other clinical parameters in pediatric SCD.
Main Methods:
- Conducted pulse oximetry (SpO2) measurements during daytime, nighttime, and after exercise in 39 children with SCD.
- Defined hypoxia based on SpO2 thresholds for daytime (<96%), nocturnal (≤93% or >10% sleep time with SpO2<90%), and postexercise (≥3% decrease after 6-minute walk test).
- Analyzed correlations between hypoxia and clinical factors including anemia severity, HbF levels, liver enzymes, sex, tricuspid regurgitation velocity, and 6-minute walk test performance.
Main Results:
- 36% of patients exhibited daytime hypoxia, 50% nocturnal hypoxia, and 44.7% postexercise hypoxia.
- Nocturnal and postexercise hypoxia were prevalent even in patients with normal daytime SpO2 (35% and 42%, respectively).
- Hypoxia was associated with greater anemia severity, lower HbF levels, and higher aspartate aminotransferase levels. Males predominated in postexercise hypoxia. Tricuspid regurgitation velocity was linked to anemia. 6-minute walk test distance correlated negatively with LDH and history of acute chest syndrome.
Conclusions:
- Severe nocturnal and postexercise hypoxia are common in children with SCD.
- These hypoxic episodes can occur even in children with normal daytime oxygen saturation.
- Hypoxia in pediatric SCD is linked to specific clinical and laboratory findings, emphasizing the need for comprehensive monitoring.
Abstract:
Hypoxia is a common feature in children with sickle cell disease (SCD) that is inconsistently associated with painful crises and acute chest syndrome. To assess the prevalence and risk factors of hypoxia, we recorded daytime, nocturnal, and postexercise pulse oximetry (SpO2) values in 39 SCD patients with a median age of 10.8 years. Median daytime SpO2 was 97% (range, 89%-100%), and 36% of patients had daytime hypoxia defined as SpO2<96%. Median nocturnal SpO2 was 94.7% (range, 87.7%-99.5%), 50% of patients had nocturnal hypoxia defined as SpO2≤93%, and 11(37%) patients spent more than 10% of their total sleep time with SpO2<90%. Median postexercise SpO2 was 94% (range, 72%-100%) and 44.7% of patients had postexercise hypoxia defined as an SpO2 decrease ≥3% after a 6-minute walk test. Among patients with normal daytime SpO2, 35% had nocturnal and 42% postexercise hypoxia. Compared to 9 patients without daytime, nocturnal, or postexercise hypoxia, 25 patients with hypoxia under at least one of these three conditions had greater anemia severity (P = 0.01), lower HbF levels (P = 0.04), and higher aspartate aminotransferase levels (P = 0.03). Males predominated among patients with postexercise hypoxia (P = 0.004). Hypoxia correlated neither with painful crises nor with acute chest syndrome. Of 32 evaluable patients, 6 (18.8%) had a tricuspid regurgitation velocity ≥2.6 m/s, and this feature was associated with anemia (P = 0.044). Median percentage of the predicted distance covered during a 6-minute walk test was 86% [46-120]; the distance was negatively associated with LDH (P = 0.044) and with a past history of acute chest syndrome (P = 0.009). In conclusion, severe episodes of nocturnal and postexercise hypoxia are common in children with SCD, even those with normal daytime SpO2.
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