Cerebral tissue oxygen saturation calculated using low frequency haemoglobin oscillations measured by near infrared spectroscopy in adult ventilated patients.

Oxy- (HbO2) and deoxy- (HHb) haemoglobin signals measured by near infrared (NIR) spectroscopy over the human frontal lobes frequently contain respiratory and low frequency oscillations (LFOs). It has been suggested previously that venous oxygen saturation (SvO2) can be calculated from these respiratory oscillations. In this paper, we investigated the use of a Fourier transform based algorithm to calculate an oxygen saturation measure known as S(osc)O2 which may be a close estimate of the underlying SvO2. S(osc)O2 was calculated using three different frequency ranges, (1) respiratory oscillations only, (2) LFOs only, and (3) both respiratory oscillations and LFOs. At each frequency range S(osc)O2 was calculated using either (1) the modified Beer-Lambert law (MBL) or (2) spatially resolved spectroscopy (SRS). In total six different measurements of S(osc)O2 were investigated here. Experiments were performed in six adult ventilated patients with traumatic brain injury. The patients' inspired oxygen fraction (FiO2) was raised in two hyperoxic phases. The calculated S(osc)O2 values were compared with other cerebral oxygenation measures including an intraparenchymal catheter based brain tissue oxygen tension (PbrO2) and the NIR based tissue oxygenation index (TOI). It was found that the S(osc)O2 calculated using the combined respiratory and LFO frequency range and the SRS method resulted in the highest detection rates of hyperoxic changes. This measure of S(osc)O2 may provide a viable, continuous, non invasive, bedside measure of cerebral venous oxygen saturation.

[1]  A. Villringer,et al.  Spontaneous Low Frequency Oscillations of Cerebral Hemodynamics and Metabolism in Human Adults , 2000, NeuroImage.

[2]  D T Delpy,et al.  Measurement of cerebral venous saturation in adults using near infrared spectroscopy. , 1997, Advances in experimental medicine and biology.

[3]  D T Delpy,et al.  Influence of Respiration and Changes in Expiratory Pressure on Cerebral Haemoglobin Concentration Measured by near Infrared Spectroscopy , 1996, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[4]  H. Nilsson,et al.  Vasomotion: mechanisms and physiological importance. , 2003, Molecular interventions.

[5]  A. Gupta,et al.  The role of tissue oxygen monitoring in patients with acute brain injury. , 2006, British journal of anaesthesia.

[6]  C. W. Yoxall,et al.  The Measurement of Peripheral Venous Oxyhemoglobin Saturation in Newborn Infants by Near Infrared Spectroscopy with Venous Occlusion , 1996, Pediatric Research.

[7]  Martin Wolf,et al.  Cyclical fluctuations in blood pressure, heart rate and cerebral blood volume in preterm infants , 1999, Brain and Development.

[8]  S. Nicolson,et al.  Arterial and Venous Contributions to Near-infrared Cerebral Oximetry , 2000, Anesthesiology.

[9]  L. Nilsson,et al.  Macrocirculation is not the sole determinant of respiratory induced variations in the reflection mode photoplethysmographic signal. , 2003, Physiological measurement.

[10]  D. Boas,et al.  Near-infrared spiroximetry: noninvasive measurements of venous saturation in piglets and human subjects. , 2002, Journal of applied physiology.

[11]  D. Delpy,et al.  Oscillations in Cerebral Haemodynamics , 1999 .

[12]  P. Niederer,et al.  Continuous noninvasive measurement of cerebral arterial and venous oxygen saturation at the bedside in mechanically ventilated neonates. , 1997, Critical care medicine.

[13]  D. Delpy,et al.  Oscillations in cerebral haemodynamics. Implications for functional activation studies. , 1999, Advances in experimental medicine and biology.

[14]  J. Michael.  Textbook of Medical Physiology , 2005 .

[15]  L. Skov,et al.  Estimation of Cerebral Venous Saturation in Newborn Infants by Near Infrared Spectroscopy , 1993, Pediatric Research.

[16]  Naoki Tanaka,et al.  Quantitative evaluation of interrelations between spontaneous low-frequency oscillations in cerebral hemodynamics and systemic cardiovascular dynamics , 2006, NeuroImage.

[17]  Yukio Kobayashi,et al.  Tissue oxygenation monitor using NIR spatially resolved spectroscopy , 1999, Photonics West - Biomedical Optics.

[18]  P. Smielewski,et al.  Evaluation of a Near-Infrared Spectrometer (NIRO 300) for the Detection of Intracranial Oxygenation Changes in the Adult Head , 2001, Stroke.

[19]  D. Delpy,et al.  Investigation of Cerebral Haemodynamics by Near-infrared Spectroscopy in Young Healthy Volunteers Reveals Posture-dependent Spontaneous Oscillations , 2004 .

[20]  A. Guyton,et al.  Textbook of Medical Physiology , 1961 .