0458 Cranial Blood Flow. Arteriovenous Anastomoses (AVAs) Shunting in Obstructive Sleep Apnea

Abstract Introduction To analyze our data on the effect of CPAP on vascular shunt mechanisms involving intra and extra cranial blood flow. Methods Daytime testing. A) Intracranial rCBF (regional Cerebral Blood Flow, Xenon133 inhalation, hemispheric mean, ml/100 mg/minute). During rCBF for the integrity of the Xenon loaded spirometer EPAP was used. B) Extracranial face blood flow, infrared imaging, at baseline, post CPAP immediate, for temperature increase (vasodilation) or decrease (vasoconstriction). Temperature change of 0.5oC is significant. The protocols were in compliance with CARE and TISEM. Participants 12. Group 1: Intracranial. Seven (2 OSA patients, 5 nonapneic controls). Group 2: Extracranial. Five (3 OSA patients, 2 nonapneic controls). Results Group 1. Patient #1. PSG: 1) Pre-CPAP, 2) CPAP 10 cm 3) Post tracheostomy CPAP. AHI: 1) 83.3, 2) 98.25, 3) 0.00. SE%: 1) 70%, 2) 70%, 3) 74%. SaO2: 1) 56%. 2) 76%. 3) 90%. Pre tracheostomy EPAP 10 cm, rCBF flow increase of 4.35% Left and decrease of 0.62% Right hemisphere. Patient #2. PSG: AHI 48.5. SE 67%. SaO2 83%. CPAP 10 cm, PSG: AHI 0.00. SE 78%. SaO2 92%. EPAP 10 cm, rCBF increase 13.59% on Left. Increase 13.43% on Right hemisphere. In controls: 4 out of 5, EPAP increased rCBF by 21.43% left and increased 12.85% on the Right hemisphere. Group 2: Five (3 OSA patients on home CPAP and 2 non apneic controls). All given CPAP for 15 minutes. Patient #1. AHI moderate to severe. ETCO2: Baseline 37, CPAP 38 mm Hg. CPAP 12.5 cm caused face vasoconstriction. Patient # 2. AHI 63. ETCO2: Baseline 41 and during CPAP was 40. CPAP 15 cm caused face vasoconstriction. Control: Controls CPAP 10 cm caused face vasoconstriction. ETCO2 Baseline: 34 and during CPAP was 35. Conclusion In obstructive sleep apnea patients and controls: EPAP increased Intracranial blood flow. CPAP decreased external carotid/face blood flow/ vasoconstriction i.e., closing of AVAs- microvascular shunts. The term microcirculation applies to blood vessels smaller than 300 µm. Infrared technology images the effect of CPAP on extracranial/face blood flow in obstructive sleep apnea. This has clinical research applications. Support (if any) None.