Evaluation of Respiratory Acoustic Monitor in Children After Surgery

The respiratory acoustic monitor records three vital signs: Respiration rate recorded in breaths per minute, oxygen saturation recorded in percentage, and heart rate recorded in beats per minute.

The reliability and accuracy of the respiratory data collected by the RAM was examined by comparing to data collected clinically by the manual counting of the respiratory rate and by the respiratory rate measure by transthoracic impedance . The accuracy of RAM was examined when a staff member goes and register these measurements that occur simultaneously during the first minute of every 2 hour interval to a maximum of a 24 hour monitoring time.

To evaluate the presence of false alarms, bedside clinical monitoring was done every two hour during 5 to 15 minutes (random sample) recording the respiratory rates and evaluating the presence of alarms. If an alarm was activated during the bedside monitoring, it was verified by the investigator if the respiratory rate provided by the device was consistent with the clinical evaluation. False alarms were considered those alarms that are triggered by the device, but during simultaneous clinical evaluation it was verified that the number of breaths per minute were inaccurate. Therefore, the higher number of false alarms detected by one type of monitoring indicates that the device is less reliable detecting the respiratory rate.

The tolerance is defined as the ratio of the time the sensor stays in place divided by the total expected time of monitoring, expressed as a percentage. The tolerance to the transthoracic impedance pads was not evaluated during this study considering that this is the standard monitoring and that is usually tolerated during the total expected time of monitoring.