Utility Of Near Infrared Spectroscopy (nirs) Guided Tilt Table Testing.

Abstract

Syncope is transient loss of consciousness. Neurocardiogenic syncope is the most common cause of syncope. Confirmation of the diagnosis of syncope is based on the head-up tilt table test. Near-infrared spectroscopy (NIRS) is a monitor of regional oxygenation and is helpful in predicting cerebral and renal ischemia. PURPOSE: Determine if multi-site NIRS monitoring will reveal differential desaturation patterns in the brain and renal vascular beds during postural stresses. METHODS: All patients (7-21 years old) scheduled to undergo tilt table testing were recruited. NIRS measurements were obtained at the forehead and above the left paravertebral level at the T10 to L1space. Tissue saturations (rSO2) were recorded at rest, during tilt test and throughout recovery. All data routinely obtained during tilt table testing (i.e. HR, BP) were included in the research database. RESULTS: 20 patients were recruited. Average age of the group was 12.9 years. 7 patients had a positive tilt table test. Patients with syncope had rSO2 trends distinctly different form non-fainters. In these patients, cerebral rSO2 shows a sudden abrupt decrease from hypo perfusion, which was followed by various progressive clinical symptoms. Cerebral rSO2 trend was paralleled by a dramatic increase in renal rSO2. These rSO2 trends are progressive until patient is returned to supine position with normalization of rSO2 thereafter. CONCLUSION: Multi-site NIRS guided tilt table testing revealed dramatic desaturation patterns in the vascular beds during postural gravitational stresses that preceded physiologic symptoms. These patterns underlie the systemic oxygen consumption to flow-coupling dynamics observed during syncope.