Extracranial contamination in the INVOS 5100C versus the FORE-SIGHT ELITE cerebral oximeter: a prospective observational crossover study in volunteers

• Published in: Canadian journal of anesthesia Vol. 63; no. 1; pp. 24 - 30
• Main Authors: Greenberg, Steven, Murphy, Glenn, Shear, Torin, Patel, Aashka, Simpson, Andrew, Szokol, Joseph, Avram, Michael J., Vender, Jeffery
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.01.2016; Springer Nature B.V
• Subjects: Adolescent; Adult; Anesthesiology; Brain - metabolism; Cardiology; Critical Care Medicine; Cross-Over Studies; Female; Healthy Volunteers; Humans; Intensive; Ischemia; Male; Medicine; Medicine & Public Health; Middle Aged; Oximetry - instrumentation; Oximetry - standards; Oxygen saturation; Pain Medicine; Pediatrics; Pneumology/Respiratory System; Prospective Studies; Reports of Original Investigations; Young Adult; United States > US; Chicago Illinois; Cuff Inflation; Cerebral Oximetry; Pneumatic Cuff; Cerebral Oxygen Saturation; Mean Arterial Pressure
• ISSN: 0832-610X; 1496-8975
• DOI: 10.1007/s12630-015-0451-7

Purpose Previous studies have found that most cerebral oximeters are subject to inaccuracies secondary to extracranial contamination of the cerebral oximetric signals. We hypothesized that the more advanced second-generation FORE-SIGHT ELITE cerebral oximeter would be significantly less affected by extracranial tissue hypoxemia than the more widely used first-generation INVOS™ 5100C monitor. Methods Twenty healthy volunteers aged 18-45 yr had the INVOS and FORE-SIGHT probes placed on their forehead in a random sequence while in the supine position. A pneumatic head cuff was then placed around each volunteer’s head just below both the oximeter and a concomitantly placed scalp forehead pulse oximeter probe. The subjects’ scalp cerebral oxygen saturation (SctO 2 ) values were measured and compared using the two different devices in sequence, both before and after scalp tissue ischemia was induced by the pneumatic cuff. Results Extracranial ischemia resulted in a significant reduction in SctO 2 values from baseline in both devices. The INVOS 5100C recorded a median [interquartile range] decrease in SctO 2 from baseline at five minutes of 15.1% [12.6 - 17.6], while that recorded by the FORESIGHT ELITE device was 8.6% [4.0 -12.3] at five minutes (median difference, 7.9%; 99% confidence interval, 1.9 to 16.5; P = 0.002). Conclusion Updated technological algorithms employed in the FORE-SIGHT ELITE cerebral oximeter may be responsible for less extracranial contamination than was observed in the previous-generation INVOS 5100C device. The impact that this extracranial contamination may have on the clinical use of these devices remains to be determined.