Lung Function Abnormalities in Sickle Cell Anaemia

Correctly Establishing and Interpreting Oxygenation Status in Sickle Cell Disease

BACKGROUND

As hypoxemia and hypoxia are central elements of disease pathophysiology and disease-related morbidity and mortality in individuals affected by sickle cell disease (SCD), clinical management aims to optimize oxygenation.

CONTENT

Hypoxemia is primarily screened for with pulse oximetry. However, in SCD pulse oximetry can inaccurately reflect arterial saturation, posing the risk of undetected (occult) hypoxemia. Solely relying on pulse oximetry might therefore lead to misdiagnosis or mismanagement, with devastating effects on tissue oxygenation. The interpretation of oxygenation status is multifaceted, and "oxygen saturation" is often used as an umbrella term to refer to distinctly different measured quantities-estimated oxygen saturation (O2Sat), hemoglobin oxygen saturation (SO2) by either pulse oximetry or co-oximetry, and fractional oxyhemoglobin (FO2Hb). While in many clinical situations this ambiguous use is of little consequence, O2Sat, SO2, and FO2Hb cannot be used interchangeably in the setting of SCD, as dyshemoglobins, anemia, cardiopulmonary comorbidities, concomitant medications, and frequent transfusions need to be accounted for. This article describes the parameters that determine blood and tissue oxygen concentration, discusses laboratory method performance characteristics and the correct interpretation of currently available clinical laboratory testing, and reviews the literature on noninvasive vs invasive oxygenation measurements in SCD.

SUMMARY

By correctly establishing and interpreting oxygenation parameters, clinical and laboratory teams can ensure high-quality, equitable healthcare, counteracting systemic exacerbations of health disparities frequently experienced by individuals with SCD.

Disentangling the Coronavirus Disease 2019 Health Disparities in African Americans: Biological, Environmental, and Social Factors

The stark racial disparities related to the coronavirus disease 2019 (COVID-19) pandemic in the United States, wherein minority populations are disproportionately getting infected and succumbing to the disease, is of grave concern. It is critical to understand and address the underlying causes of these disparities that are complex and driven by interacting environmental, social and biological factors. In this article we focus on the African American community and examine how social and environmental determinants of health intersect with biological factors (comorbidities, underlying genetics, host immunity, vitamin D levels, epigenetics) to exacerbate risk for morbidity and mortality.

Predicted Reference Equations for Spirometry Indices as a Proxy from Anthropometry Measurements of Nigerian Children with Sickle Cell Anaemia Aged 5-12 Years

BACKGROUND

Significant morbidity and mortality in patients with sickle cell disease are accounted for by lung complications. To facilitate good respiratory care for children with sickle cell anaemia the generation of local predicted values is highly important.

OBJECTIVE

To determine the reference equations for spirometry indices estimation in children with sickle cell anaemia, which can be readily used as proxy when there is no easy accessibility to spirometer.

METHODS

A cross-sectional study with linear regression models developed to estimate reference values for spirometric indices in Nigerian children with sickle cell anaemia aged 5-12 years.

RESULTS

Age as independent variables for estimation of forced expiratory volume in 1 s (FEV1) was associated with lowest coefficient of determination (R2) and highest standard error. The coefficient of determination (R2) and standard error was highest and lowest, respectively, when arm span was used to determine peak expiratory flow rate (PEFR). Prediction models for PEFR and FEV1 gave the closest mean estimates that were 0.18 and 0.16 lower and higher than the actual mean PEFR and FEV1, respectively, but the differences was significant only in FEV1. On the contrary the prediction models for forced vital capacity (FVC) gave mean estimates that was 1.02 higher than the actual mean FVC, however, the finding was not significant.

CONCLUSION

Preferred proxy for spirometry indices in children with sickle cell anaemia may be arm span.