# Nocturnal hemoglobin desaturation in chronically transfused adults with sickle cell disease: a retrospective study

## TL;DR

This study finds that many adults with sickle cell disease who receive regular blood transfusions experience nighttime drops in blood oxygen levels, which may indicate more severe disease activity.

## Contribution

The study identifies nocturnal hemoglobin desaturation as a common and clinically relevant complication in chronically transfused sickle cell disease patients.

## Key findings

- 36.6% of chronically transfused adults with SCD experienced nocturnal hemoglobin desaturation.
- NHD was associated with higher reticulocyte and white blood cell counts, suggesting increased disease activity.
- Older age at starting transfusions correlated with longer NHD duration, while cerebrovascular events correlated with shorter duration.

## Abstract

High-risk SCD may be managed with chronic red blood cell exchange transfusions. We examined the prevalence of sleep-associated hypoxemia (≥5 minutes at SpO2 ≤88%) or nocturnal Hb desaturation (NHD) in chronically transfused adults with SCD. Of 41 identified participants, 15 (36.6%) had tested positive for NHD at some point prior to enrollment. The median duration of desaturation (SpO2 ≤88%) in those that tested positive was 88.3 minutes (IQR 27.9-226.0 minutes). Participants with and without NHD were compared using non-parametric statistical tests. Compared to participants without NHD, those with NHD had higher absolute reticulocyte counts (P = .018) and white blood counts (P = .05) and tended to be older. They had more anemia (P = .11) and higher lactate dehydrogenase levels (P = .072). Older age at initiation of chronic red blood cell transfusions associated the strongest with a longer duration of NHD (ρ = 0.4253, P = .0067), while prior history of cerebrovascular events associated with a shorter duration of NHD (P = .0315). Our results demonstrate that NHD is common in adults being treated with red blood cell exchange for high-risk SCD and associates with laboratory evidence of increased disease activity. Increased awareness of this complication and appropriate screening may provide an additional simple, low-cost, and physiologically relevant treatment intervention, that is oxygen therapy.