Validation of a novel respiratory rate monitor based on exhaled humidity.
BACKGROUND
Postoperative monitoring of ventilation is largely restricted to the measurement of haemoglobin-oxygen saturation and respiratory rate (RR) derived from the ECG. measurement is inadequate when used with supplemental oxygen and ECG-derived RR is subject to artifacts. A new monitor measures RR by quantifying the humidity of exhaled air (respiR8(®)).


METHODS
The accuracy of the system was tested using a breathing simulator. In healthy volunteers, the respiR8(®) monitor was compared with two other methods of measuring RR: capnometry and counting of thoracic breathing movements. The ability of the monitor to track changes in RR resulting from the infusion of 2.5 μg kg(-1) fentanyl was assessed and compared with RR measured from a validated flow measurement system. The RR in 50 postoperative patients measured with the respiR8(®) was compared with that derived from the ECG. RR values were compared by population-based Bland-Altman analyses.


RESULTS
The respiR8(®) monitor was accurate in the range required in clinical practice. There was a close agreement between RR from respiR8(®), capnometry, and manual counting of respiratory movements without bias (limits of agreement ±1 bpm). The respiR8(®) monitor was well able to accurately track RR changes from fentanyl. In postoperative patients, RR from respiR8(®) and ECG had a bias of 1.7 (5.7) bpm due to greater RR values observed from the ECG due to artifacts.


CONCLUSIONS
The respiR8(®) gives an accurate measurement of RR and is useful in postoperative care.
Department of Anesthesiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
M
M
Niesters
R
R
Mahajan
E
E
Olofsen
M
M
Boom
S
S
Garcia Del Valle
L
L
Aarts
A
A
Dahan
D000293:Adolescent; D000328:Adult; D018686:Anesthetics, Intravenous / Q000494:pharmacology; D001785:Blood Gas Monitoring, Transcutaneous; D004562:Electrocardiography; D045853:Exhalation; D005260:Female; D005283:Fentanyl / Q000494:pharmacology; D006801:Humans; D006813:Humidity; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000592:standards*; D011182:Postoperative Care / Q000295:instrumentation / Q000379:methods; D011183:Postoperative Complications / Q000175:diagnosis; D015203:Reproducibility of Results; D056152:Respiratory Rate; D012680:Sensitivity and Specificity; D055815:Young Adult
D018686:Anesthetics, Intravenous; D005283:Fentanyl