Early Detection of Acute Chest Syndrome Through Electronic Recording and Analysis of Auscultatory Percussion

Abstract

Acute chest syndrome (ACS) is the leading cause of death among people with sickle cell disease. ACS is clinically defined and diagnosed by the presence of a new pulmonary infiltrate on chest imaging with accompanying fever and respiratory symptoms like hypoxia, tachypnea, and shortness of breath. However, the characteristic chest x-ray (CXR) findings necessary for a clinical diagnosis of ACS can be difficult to detect, as is determining which patient needs a CXR. This makes early detection difficult; but it is critical in order to limit ACS severity and subsequent fatalities. This research project looks to apply percussion and auscultation techniques that can provide an immediate diagnosis of acute pulmonary conditions by using an automated standard percussive input and electronic auscultation for computational analysis of the measured signal. Measurements on sickle cell patients having ACS, vaso-occlusive crisis (VOC), and regular clinic visits (healthy) were recorded and analyzed. Average intensity of sound transmission through the chest and lungs was determined in the ACS and healthy subject groups, revealing an average of 10-14 dB decrease in sound intensity in the ACS group compared to the healthy group. A random under-sampling boosted tree classification model identified with 94% accuracy the positive ACS and healthy observations. The analysis also revealed unique measurable changes in a small number of cases clinically classified as complicated VOC, which later developed into ACS. This suggests the developed approach may also have early predictive capability, identifying patients at risk for developing ACS prior to current clinical practice.

Keywords: Acoustic; acute chest syndrome; diagnosis; lung; machine learning; percussion; sickle cell disease; stethoscope.

FIGURE 1.

Sickle cell admit patient diagnosis pathway and EMR classification process.

FIGURE 2.

(a) Spectrogram of one of the six recording locations for the electronically recorded chirp signal transmission response from 0.1 kHz to 1 kHz over 14 seconds. (b) Average sound intensity with one standard error for the two groups: ACS (red) vs healthy (blue) at PBR. (c) Average sound intensities of subject group at PBL location, healthy (blue), ACS, (red), uncomplicated VOC (yellow), and PT 156 of unknown subject group (purple) with confounding clinical symptoms. (d) VOC in-patient potential clinical pathways. Red shaded box indicates a stage at which this system may be useful in the future.

FIGURE 3.

Potential findings in a positive CXR for ACS diagnosis. Blue shaded boxes suggest decreased sound transmission, green shaded boxes suggest no effect on sound transmission, and yellow shaded boxes suggest a mixed result with respect to sound transmission amplitude.

FIGURE 4.

Receiver Operating Characteristic (ROC) curve for the ACS class.