ESTIMATING CEREBRAL BLOOD-FLOW IN NEWBORN-INFANTS - COMPARISON OF NEAR-INFRARED SPECTROSCOPY AND XE-133 CLEARANCE

A new method of measuring cerebral blood flow (CBF) in newborn infants by means of near infrared spectroscopy (CBFnirs) was compared with the i.v. Xe-133 clearance technique (CBFxe). Forty CBFnirs measurements were obtained during 19 Xe-133 measurements in 16 infants; 79 other CBFnirs data sets were discarded because the assumptions for their use were not fulfilled. The test-retest variation of repeated near infrared-measurements during each Xe-133 clearance was 17.5%. CBFnirs was closely related to CBFxe (r2 = 0.84, p < 0.0001), with a slope of 0.75 (SEM = 0.064) and a intercept of 1.58 mL/100 g/min (SEM = 0.51). The difference between the measurements obtained by the two methods (CBFnirs - CBFxe) was negative in the high range of CBF, whereas the difference was close to zero in the low range. We conclude that CBF measured with near infrared spectroscopy was in good agreement with the CBF measured with the Xe-133 method. The near infrared spectroscopy method has the advantage of being noninvasive, and it does not involve ionizing radiation. Because of methodologic constraints, however, it may underestimate CBF in the high range of flow, and it may have limitations of application in clinical research.