Use of pulse oximeter plethysmograph waveform to monitor patients with acute exacerbation of obstructive airway diseases

Abstract Background Acute exacerbation of obstructive airway diseases is the most frequent acute clinical scenario in ER in chest hospitals. There are limited objective and continuous real-time measures of acute exacerbation severity to guide treatment. Pulse oximeter plethysmograph wave is an objective bedside measure of change in blood volume beneath the probe and was found to correlate well with pulsus paradoxus which is one of the signs of respiratory distress. Objective To assess using pulse oximeter plethysmograph to monitor severity and response to therapy in patients with acute exacerbation of obstructive airway diseases. Patients and methods This study was a prospective cross-sectional study conducted on 100 patients, 45 patients with bronchial asthma exacerbation and 55 patients with COPD exacerbation, who attended the 23 July Chest Hospital ER from January 2023 to September 2023. Baseline variation (BLV) of pulse oximeter waveform of these patients was assessed qualitatively (visually) and quantitatively (maximum distance from baseline in mm) during the course of management in ER, and results correlated with severity indices and outcome. Results On ER admission, BLV was 3–13 mm with a median IQR 5 (4–7 mm) in 100 patients. There was a significant correlation between quantitative BLV and other signs of exacerbation severity (heart rate, respiratory rate, pulsus paradoxus and AAIRS for asthma, and Borg score for COPD). Forty patients improved under treatment and were discharged home, while 60 patients showed no improvement and required admission to hospital. Changes in BLV correlated well with the response to therapy and outcome in all patients. BLVs were recognizable by visual assessment as well. Conclusion BLV of plethysmograph wave is a reliable simple, non-invasive, and real-time tool in assessing severity and response to treatment of acute exacerbation of obstructive air way diseases. It is thus useful in monitoring and triaging these patients in ER and critical care settings.