0502 Infrared Imaging of Face Blood Flow in Response to Continuous Positive Airway Pressure (CPAP) in Obstructive Sleep Apnea (OSA)

Abstract Introduction Face infrared images taken after CPAP demonstrates vasomotor response. Face blood vessels have baroreceptors. BRS (baroreceptor sensitivity) testing involves vasomotor reactivity (VMR) related changes. In 2022, it was reported that BRS [tested at ambient pressure (1 atm)] in OSA patients was not reduced during rest. We reviewed our data to see whether face VMR to CPAP (at 1 atm), while at rest was altered in sleep apnea patients using CPAP compared to controls. Methods The protocol was approved by the hospital committee for the protection of human subjects. Exclusion criteria: age < 18 years, pregnancy, head-injury, untreated hypertension/ cardiac disease, diabetes, COPD, hyperlipidemia, h/o drugs use, cannabis products, smoking/vaping, chemotherapy and untreated sleep disorder. AGA Model 782, AGEMA and FLIR A40 Cameras were used for daytime testing. Participants were awake/seated for imaging. Six Caucasians, ages 33-58 yrs (mean 45.5 yrs), three males and three females; four on CPAP treatment for OSA (moderate/severe) and two were non-sleep apnea controls. Before imaging, participants equilibrated for 20 minutes in a temperature, humidity, and air flow controlled and monitored laboratory. CPAP, tcpO2 and EtCO2 were monitored. CPAP 10-15 cm for 15 minutes. Pre-post CPAP images were done. Results A change in facial temperature of 0.5oC is clinically significant. Patients and controls both showed a face temperature decrease of 0.5oC or more, [i.e., CPAP closed extracranial face blood flow-AVAs shunts (vasoconstriction)] in both groups]. The pre-post CPAP temperature decrease was more in sleep apnea patients compared to control, indicating altered VMR in sleep apnea patients at rest. Conclusion Pre- and post-CPAP temperature differences reflected changes in the participants’ physiological vasomotor state. CPAP induced changes in the tcpO2 and EtCO2 were not enough to explain VMR changes. Clinically sleep apnea patients are symptomatic in ambient atmospheric pressure. Changing the airway pressure by 1 atm + CPAP pressure ameliorates the sleep apnea. CPAP 10 cm is roughly 1% (just under 1 percent) of 1 atm at sea level. This minimal pressure change resulted in vasoconstriction of AVAs and capillary recruitment. This was imaged by thermography. Infrared technology can image face (extracranial) VMR at rest in OSA. Support (if any) Nothing to disclose.