Abstract 19585: Tidal Volume and Minute Ventilation Measurement at High, Low, and Erratic Respiratory Rates by a Non-Invasive Respiratory Monitoring System
Introduction: Changes in minute ventilation (MV) & tidal volume (TV) signal the beginning of respiratory compromise which often precedes cardiopulmonary arrest. Currently, respiratory monitoring in non-intubated patients lacks objective & quantitative methodology for determining the adequacy of ventilation. A non-invasive, Respiratory Volume Measurement (RVM) system has been developed to measure MV, TV and respiratory rate (RR) continuously. Previous work has demonstrated clinically acceptable accuracy and precision of RVM monitoring across normal respiratory patterns and rates. Hypothesis: RVM monitoring accurately yields tidal volume & minute ventilation across abnormal breathing rates, and erratic patterns.
Methods: We studied 51 adult subjects (93 visits, 2252 tests) at low (4 - 6 bpm), normal (8 - 20 bpm), and high (30 - 40 bpm) respiratory rates and during erratic breathing. TV, RR and MV were measured simultaneously with an impedance-based RVM system (ExSpiron, Respiratory Motion, Inc., Waltham, MA) and a dry rolling seal spirometer (Morgan Scientific Inc., Haverhill, MA). Advanced data processing algorithms displayed a real time respiratory curve and calculated RVM measurements.
Results: Throughout the range of 4 bpm to 40 bpm and during erratic breathing, RVM measurements are highly-correlated with spirometer measurements, with an average MV and TV correlation coefficient of 0.96, 95% CI 0.93 to 0.99 (Fig 1). Across all subjects, median correlation coefficients ranged from 0.91 to 0.99.
Conclusions: High correlation (r = 0.96) between spirometric measurements and RVM signals concludes that the RVM system is capable of monitoring respiratory status during normal and erratic breathing, and at high and low breathing rates. As a passive, continuous, non-invasive system, RVM monitoring of non-intubated patients could provide earlier indications of respiratory decline potentially permitting interventions to prevent cardiopulmonary arrest.
- © 2012 by American Heart Association, Inc.