Exploratory study to evaluate respiratory rate using a thermal imaging camera

Background: Respiratory rate is a vital physiological measurement used in the immediate assessment of unwell children and adults. Convenient electronic devices exist for measurement of pulse, blood pressure, oxygen saturation and temperature. Although devices which measure respiratory rate exist, none has entered everyday clinical practice for acute assessment of children and adults. An accurate and practical device which has no physical contact with the patient is important to ensure readings are not affected by distress caused by the assessment method. Objective: To evaluate the use of a thermal imaging method to monitor respiratory rate in children and adults. Methods: Facial thermal images of adult volunteers and children undergoing elective polysomnography were included. Respiration was recorded for at least two minutes with the camera positioned one metre from the subject's face. Values obtained using the thermal imaging camera were compared with those obtained from contact methods such as nasal thermistor, respiratory inductance plethysmography, nasal airflow and End Tidal Carbon Dioxide (CO2). Results: A total of 61 subjects, including 41 adults (age range 27 to 46 years) and 20 children (age range 0.5 to 18 years) were enrolled. The correlation between respiratory rate measured using thermal imaging and the contact method was r=0.94. Sequential refinements to the thermal imaging algorithms resulted in the ability to perform real-time measurements and an improvement of the correlation to r=0.995. Conclusion: This exploratory study shows that thermal imaging derived respiratory rates in children and adults correlate closely with the best performing standard method. With further refinements, this method could be implemented in both acute and chronic care in children and adults.