Highly sensitive monitoring of chest wall dynamics and acoustics provides diverse valuable information for evaluating ventilation and diagnosing pneumothorax.
Current practice of monitoring lung ventilation in neonatal intensive care units, utilizing endotracheal tube pressure and flow, end-tidal CO2, arterial O2 saturation from pulse oximetry, and hemodynamic indexes, fails to account for asymmetric pathologies and to allow for early detection of deteriorating ventilation. This study investigated the utility of bilateral measurements of chest wall dynamics and sounds, in providing early detection of changes in the mechanics and distribution of lung ventilation. Nine healthy New Zealand rabbits were ventilated at a constant pressure, while miniature accelerometers were attached to each side of the chest. Slowly progressing pneumothorax was induced by injecting 1 ml/min air into the pleural space on either side of the chest. The end of the experiment (tPTX) was defined when arterial O2 saturation from pulse oximetry dropped <90% or when vigorous spontaneous breathing began, since it represents the time of clinical detection using common methods. Consistent and significant changes were observed in 15 of the chest dynamics parameters. The most meaningful temporal changes were noted for features extracted from subsonic dynamics (<10 Hz), e.g., tidal amplitude, energy, and autoregressive poles. Features from the high-frequency band (10-200 Hz), e.g., energy and entropy, exhibited smaller but significant changes. At 70% tPTX, identification of asymmetric ventilation was attained for all animals. Side identification of the pneumothorax was achieved at 50% tPTX, within a 95% confidence interval. Diagnosis was, on average, 34.1 ± 18.8 min before tPTX. In conclusion, bilateral monitoring of the chest dynamics and acoustics provide novel information that is sensitive to asymmetric changes in ventilation, enabling early detection and localization of pneumothorax.
Faculty of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa, Israel;
Jimy
J
Pesin
Faculty of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa, Israel;
Anna
A
Faingersh
Faculty of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa, Israel; Department of Neonatology, Carmel Medical Center, and Faculty of Medicine, Technion, Haifa, Israel.
Dan
D
Waisman
Faculty of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa, Israel; amir@bm.technion.ac.il.
Amir
A
Landesberg
D000162:Acoustics; D000818:Animals; D001158:Arteries / Q000378:metabolism / Q000503:physiopathology; D002245:Carbon Dioxide / Q000378:metabolism; D007442:Intubation, Intratracheal / Q000379:methods; D008168:Lung / Q000503:physiopathology; D008991:Monitoring, Physiologic / Q000379:methods; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000378:metabolism; D011030:Pneumothorax / Q000378:metabolism / Q000503:physiopathology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D011817:Rabbits; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology*; D035441:Thoracic Wall / Q000503:physiopathology*
D002245:Carbon Dioxide; D010100:Oxygen
asymmetric ventilation; chest wall dynamics; early detection; lung function