Prevalence of Exercise-induced Desaturation in Survivors of Severe COVID-19 Pneumonia and the Predictive Value of Lung Ultrasound: A Cross-sectional Study

Abstract

Introduction: Survivors of severe Coronavirus Disease-2019 (COVID-19) pneumonia may experience Exercise-Induced Desaturation (EID), which can remain undiagnosed at discharge, as most exhibit normal resting Arterial Blood Gases (ABGs). This undiagnosed condition may lead to unexpected hospital readmissions, causing additional burden to the health system. However, the prevalence of EID among this population, especially in developing countries, is not well documented. Aim: To estimate the prevalence of EID among survivors of severe COVID-19 pneumonia and to explore the predictive role of Lung Ultrasound Scan (LUS) in detecting EID. Materials and Methods: This hospital-based, observational, cross-sectional study was conducted at the Institute of Chest Diseases in Kozhikode, Kerala, India from October 2021 to September 2022. It involved 153 COVID-19 patients aged 18 years and above who had recovered from severe pneumonia, were otherwise fit for hospital discharge, and had normal resting ABGs. The study examined the prevalence of EID using the 6-Minute Walk Test (6MWT). Additionally, it investigated the predictive ability of a LUS for EID. A LUS was performed on all patients and scoring was conducted according to the established protocol. Results: The mean age of the study subjects was 53.50±14.13 years, with 119 (77.8%) being male. During the 6MWT, 96 patients (62.7%) showed significant desaturation. A total of 83 (95.4%) subjects in the desaturated group required Non-Invasive Ventilation (NIV) compared to 4 (4.6%) in the non-desaturated group (p<0.001). All 24 (100%) subjects in the desaturated group required Invasive Mechanical Ventilation (IMV), while none in the non-desaturated group did. The mean Length Of Stay (LOS) in the hospital was 35.50±13.35 days for the desaturated group, compared to 23.32±16.25 days for the non-desaturated group (p<0.001). The LUS score was significantly higher in the desaturated group (16.61±5.92) than in the non-desaturated group (5.54±4.62). The Receiver Operating Characteristic (ROC) curve for the LUS score indicated a cut-off value of 8.5 for identifying significant EID. Conclusion: Survivors of COVID-19 who recovered from Acute Respiratory Failure (ARF) and have normal resting ABGs may still have significant EID. A protocol-based LUS score can potentially identify individuals at risk for EID.

Keywords

• acute respiratory failure
• coronavirus disease-2019
• lung ultrasound scan score
• six-minute walk test