Near-infrared Oximetry Research Articles

Evaluation of revascularization efficiency using near-infrared oximetry in patients with diabetic foot syndrome

To evaluate prognostic significance of tissue oximetry in healing of trophic defects in patients with diabetic foot syndrome (DFS) after endovascular revascularization. In 42 patients with DFS, tissue oximetry was performed in angiosome projection with the FORE-SIGHT MC-2000 (CASMED) device before and the next day after revascularization of lower limb arteries. The 1st group included 30 patients with wound healing throughout 3 months, the 2nd group included 12 patients with amputation or no healing of trophic defects. Direct revascularization was more common in the 1st group (p=0.001). On the day after intervention, oxygen saturation (StO2) increased in all angiosomes in both groups (p<0.05). StO2 increment differed significantly between groups in all angiosomes except for point I (p<0.05). According to ROC analysis, StO2 increment by 4.5% in absolute values and 7.9% in percentage leads to trophic defect healing within 3 months (sensitivity and specificity were 76.7% and 66.7% for absolute values, 80% and 58.3% for percentage, respectively). Evaluation of StO2 in target angiosome may be valuable to predict trophic defect healing after endovascular surgery.

Voxel-based measurement sensitivity of spatially resolved near-infrared spectroscopy in layered tissues.

We quantitatively investigated the measurement sensitivity of spatially resolved spectroscopy (SRS) across six tissue models: cerebral tissue, a small animal brain, the forehead of a fetus, an adult brain, forearm muscle, and thigh muscle. The optical path length in the voxel of the model was analyzed using Monte Carlo simulations. It was found that the measurement sensitivity can be represented as the product of the change in the absorption coefficient and the difference in optical path length in two states with different source-detector distances. The results clarified the sensitivity ratio between the surface layer and the deep layer at each source-detector distance for each model and identified changes in the deep measurement area when one of the detectors was close to the light source. A comparison was made with the results from continuous-wave spectroscopy. The study also identified measurement challenges that arise when the surface layer is inhomogeneous. Findings on the measurement sensitivity of SRS at each voxel and in each layer can support the correct interpretation of measured values when near-infrared oximetry or functional near-infrared spectroscopy is used to investigate different tissue structures.

Near Infrared Brain and Muscle Oximetry: From the Discovery to Current Applications

In the early 1960s, Norris introduced near infrared (NIR) spectroscopy (700–2500 nm) as an analytical technique for agricultural products. In 1977, Jöbsis founded in vivo medical NIR spectroscopy, reporting that the relatively high degree of transparency of brain tissue in the NIR spectral window (700–1000 nm) enables safe real-time non-invasive detection of regional haemoglobin oxygenation using trans-illumination spectroscopy. In order to place current medical NIR spectroscopy in its proper perspective, this review provides a snapshot of the roots of the discovery and the early years of medical NIR spectroscopy research and development. Starting in 1992, the opportunity of measuring quantitatively, by different NIR spectroscopy techniques, regional oxy-haemoglobin saturation by NIR oximetry, it is possible to monitor brain/muscle reserve capacity following tissue oxygen extraction in different pathophysiological conditions. This review reports the status of the current commercial oximeters (including wireless instrumentation) and their main clinical and physiological applications. In the last decade, NIR spectroscopy brain oximetry has obtained significant clinical relevance as suggested by the more than 10,000 instruments sold and the high number of related scientific publications. The most relevant clinical application is represented by the evaluation of cerebral oxy-haemoglobin saturation during adult cardiac surgery and cardiopulmonary bypass. Many commercial oximeters are presently available. However, their relatively poor precision and the lack of standardisation amongst the different instruments suggest that further technological advances are required before NIR spectroscopy oximetry can be adopted more widely under the “guidelines” of regulatory authorities.

Medical near Infrared Spectroscopy 35 Years after the Discovery

Optical methods using visible and near infrared (NIR) light are a powerful tool for understanding human health and improving disease detection and treatment. The medical applications of optical methods are very old but as optical technologies advance, old medical applications evolve and new ones emerge. The main advantages of the optical methods are: non-invasive, no side-effects, good temporal and spatial resolution, real-time functional information, cost effective and portable. Optical methods rely on different types of interactions between visible or NIR light and biological tissue to provide structural, biochemical, physiological and morphological information. There are two main tissue optical properties which characterise light–tissue interactions and determine therapeutic or diagnostic outcome: absorption coefficient and reduced scattering coefficient. The penetration depth of visible and NIR light in tissue ranges from microns to centimetres depending on wavelength, source/detector separation, light delivery/collection geometry etc. The major tissue absorbers include: haemoglobin, lipids, melanin, water and proteins. Oxygenated and de-oxygenated haemoglobin (O2Hb; HHb) preferentially absorb visible and NIR light of different wavelengths, as evidenced by the more reddish colour of oxygenated blood and the more bluish hue of deoxygenated blood. O2Hb and HHb have distinct spectra, therefore optical measurements can provide information on tissue oxygenation, oxygen consumption and blood haemodynamics. Absorption and/or fluorescence NIR spectroscopy is utilised in different techniques with different resolution and penetration depth, such as conventional microscopy, confocal/multi-photon microscopy, optical coherence tomography (OCT), photodynamic therapy, “in vivo” molecular imaging and medical diffuse NIR optical spectroscopy/imaging. The main applications of medical NIR diffuse optical spectroscopy/imaging are: pulse oximetry, brain/muscle oximetry, functional brain cortex mapping and optical mammography. NIR light was utilised for the first time in pulse oximetry by Takuo Aoyagi in 1972. Pulse oximetry, an extremely simplistic version of reflectance spectroscopy, measures continuously arterial O2Hb saturation in the index finger or in other vascular districts and is considered the most significant technological advance ever made in monitoring the safety of patients during anaesthesia and critical care. Another step in expanding the usefulness of using NIR light in the medical field is represented by the discovery of medical NIR diffuse spectroscopy. Frans Jobsis is considered the founder of “in vivo” medical NIR spectroscopy. In 1977, he reported that the relatively high degree of transparency of brain tissue in part of the NIR range (700–1000 nm; the “optical window”) enables real-time non-invasive detection of regional haemoglobin oxygenation using trans-illumination spectroscopy.1 Starting in 1992 the opportunity of measuring quantitatively, by different NIR spectroscopy techniques, regional O2Hb saturation by NIR oximetry made it possible to monitor brain/muscle reserve capacity following tissue oxygen M. Ferrari, K.H. Norris and M.G. Sowa, J. Near Infrared Spectrosc. 20, vii–ix (2012)

Low Renal Oximetry Correlates With Acute Kidney Injury After Infant Cardiac Surgery

Acute kidney injury (AKI) is a frequent complication after cardiopulmonary bypass surgery during infancy. Standard methods for evaluating renal function are not particularly sensitive nor are proximate indicators of renal dysfunction that allow intervention in real time. Near-infrared spectroscopy (NIRS) is a newer noninvasive technology that continuously evaluates regional oximetry and may correlate with renal injury and adverse outcomes after cardiac surgery in infants. This prospective observational study enrolled 40 infants (age, <12 months) undergoing biventricular repair. Continuous renal oximetry data were collected for the first 48 postoperative hours and correlated with postoperative course, standard laboratory data, and the occurrence of acute renal injury. Subjects with low renal oximetry (below 50% for >2 h) had significantly higher postoperative peak creatinine levels by 48 h (0.8 ± 0.4 vs. 0.52 ± 0.2; p = 0.003) and a higher incidence of AKI (50 vs. 3.1%; p = 0.003) than those with normal renal oximetry. These subjects also required more ventilator days and greater vasoactive support, and they had elevated lactate levels. Prolonged low renal near-infrared oximetry appears to correlate with renal dysfunction, decreased systemic oxygen delivery, and the overall postoperative course in infants with congenital heart disease undergoing biventricular repair.

Total aortic arch replacement under intermittent pressure-augmented retrograde cerebral perfusion

Kitahori, Kawata, Takamoto et al. described the effectiveness of a novel protocol for retrograde cerebral perfusion that included intermittent pressure augmentation for brain protection in a canine model. Based on their report, we applied this novel technique clinically. Although the duration of circulatory arrest with retrograde cerebral perfusion was long, the patient recovered consciousness soon after the operation and had no neurological deficit. Near-infrared oximetry showed recovery of intracranial blood oxygen saturation every time the pressure was augmented.

Clinical Application of Intermittent Pressure-Augmented Retrograde Cerebral Perfusion

Brain protection is important during aortic arch surgery, especially in patients with cerebral ischemia. We clinically applied the effectiveness of a novel protocol of retrograde cerebral perfusion with intermittent pressure augmentation for brain protection in a canine model, as described in a previous report. Although, in our patient the brachiocephalic artery and left subclavian artery were occluded as a result of aortitis, there was a history of right cerebral infarction, recovery of consciousness, and no neurologic sequelae. Near-infrared oximetry showed recovery of intracranial blood oxygen saturation every time the pressure was augmented.

Near-infrared oximetry of three post-rigor skeletal muscles for following myoglobin redox forms

We investigated the response of frequency-domain multidistance (FDMD) near-infrared (NIR) tissue oximetry for detecting absolute amounts of myoglobin (Mb) redox forms and their relationship to meat colour stability. Four packaging formats were used to create different blends of Mb redox forms and meat colours during display. Changes in surface colour and subsurface pigment forms during simulated display time (0, 2, 4, and 10 d at 2 °C) were evaluated using surface reflecto-spectrophotometry (both L∗ a∗ b∗ and specific wavelengths) and FDMD NIR tissue oximetry. Data for both methods of direct measurement of oxymyoglobin and deoxymyoglobin were strongly related and accounted for 86–94% of the display variation in meat colour. Indirect estimates of metmyoglobin ranged from r 2 = 59–85%. It appears that NIR tissue oximetry has potential as a noninvasive, rapid method for the assessment of meat colour traits and may help improve our understanding of meat colour chemistry in post-rigor skeletal muscle.

Rebuttal from Van Lieshout and Secher

POINT-COUNTERPOINTRebuttal from Van Lieshout and SecherPublished Online:01 Oct 2008https://doi.org/10.1152/japplphysiol.90597.2008bMoreSectionsPDF (37 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Neither the “neurovascular unit” (4) nor sympathetic activity to the brain vessels are recorded in humans and we have to rely on indirect evidence to evaluate the importance of sympathetic modulation of cerebral blood flow (CBF), e.g., during treatment of patients with a low blood pressure. Cerebral autoregulation describes that CBF stays relatively stable within a mean arterial pressure (MAP) of ∼60–150 mmHg, while a lower pressure reduces CBF and a high MAP increases CBF (6). Thus hypotension may challenge CBF as soon as MAP decreases below the lower limit of cerebral autoregulation. As illustrated (9), the central blood volume and, therefore, cardiac output (CO) adversely influence the lower limit of cerebral autoregulation and maybe in contrast to Strandgaard and Sigurdsson (7), we consider that in situations where central blood volume is critically reduced, CBF is not being prioritized. Under those conditions cerebral perfusion declines to about one-half the normal value and cerebral oxygenation is lowered by more than 10% with development of (pre)syncopal symptoms, while a Bezold-Jarish-like reflex concurrently increases muscle blood flow and oxygenation (5, 8) as first described by Barcroft et al. (1).Accordingly, when there is a need to pharmacologically elevate a low blood pressure, is it then sufficient to increase MAP or should CO also be elevated? As CO is, in general, not taken into account when regulation of CBF is described (6), it may be considered to be sufficient to increase MAP with the administration of an α-adrenergic agonist like phenylephrine. On the other hand, if the cerebral vessels were significantly innervated by α-adrenergic receptors, the effects of α-receptor activation restoring MAP would be considered not being limited to the peripheral vasculature but also to encompass the brain.What we find is that administration of phenylephrine, when used to treat arterial hypotension, not only reduces CO, but also cerebral perfusion and oxygenation even when administered to a normal subject, elevating MAP to beyond what is considered the upper limit of cerebral autoregulation. Thus phenylephrine elicits cerebral vasoconstriction, illustrating a potential influence for the sympathetic nervous system in the regulation of CBF (3). Therefore phenylephrine is not the drug of choice for treatment of a hypotensive patient if the aim is to secure CBF.Sympathetic activity to the cerebral circulation affecting CBF under certain circumstances cannot be ignored and the strategy for treatment of hypotension should include the normalization of CO in so-called individualized goal-directed volume therapy (2) to efficiently enhance CBF and cerebral oxygenation.REFERENCES1 Barcroft H, Edholm OG, McMichael J, Sharpey-Schafer EP. Posthaemorrhagic fainting study by cardiac output and forearm flow. Lancet 243: 489–491, 1944.Crossref | Google Scholar2 Bundgaard-Nielsen M, Holte K, Secher NH, Kehlet H. Monitoring of perioperative fluid administration by individualized goal-directed therapy. Acta Anaesthesiol Scand 51: 331–340, 2007.Crossref | ISI | Google Scholar3 Cassaglia PA, Griffiths RI, Walker AM. Sympathetic nerve activity in the superior cervical ganglia increases in response to imposed increases in arterial pressure. Am J Physiol Regul Integr Comp Physiol 294: R1255–R1261, 2008.Link | ISI | Google Scholar4 Hamel E. Perivascular nerves and the regulation of cerebrovascular tone. J Appl Physiol 100: 1059–1064, 2006.Link | ISI | Google Scholar5 Madsen PL, Secher NH. Near-infrared oximetry of the brain. Prog Neurobiol 58: 541–560, 1999.Crossref | PubMed | ISI | Google Scholar6 Poulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev 2: 161–192, 1990.PubMed | Google Scholar7 Strandgaard S, Sigurdsson ST. Counterpoint: Sympathetic activity does not influence cerebral blood flow. J Appl Physiol; doi:10.1152/japplphysiol.90597.2008aLink | ISI | Google Scholar8 Van Lieshout JJ, Wieling W, Karemaker JM, Secher NH. Syncope, cerebral perfusion, oxygenation. J Appl Physiol 94: 833–848, 2003.Link | ISI | Google Scholar Download PDF Previous Back to Top Next FiguresReferencesRelatedInformation More from this issue > Volume 105Issue 4October 2008Pages 1367-1367 Copyright & PermissionsCopyright © 2008 the American Physiological Societyhttps://doi.org/10.1152/japplphysiol.90597.2008bHistory Published online 1 October 2008 Published in print 1 October 2008 Metrics

The Application of Near-infrared Oximetry to Cerebral Monitoring During Aneurysm Embolization: A Comparison With Intraprocedural Angiography

Near-infrared spectroscopy (NIRS) has been used to monitor regional cerebral oxygen saturation (rSO2) in patients at risk of cerebral desaturation during surgical and neurointerventional procedures. However, the quantitative capabilities of the method have been questioned, as has its validation compared with jugular bulb oximetry. Here, we compare NIRS data acquired during coil embolization procedures with incidence of vasospasm as detected from angiography. Thirty-two subarachnoid hemorrhage patients underwent embolization. Bilateral SomaSensor strips (Invos 4100, Somanetics) were affixed to the forehead at constant anatomic positions, avoiding frontal sinuses and scalp hair. Mean arterial pressure, SaO2, end-tidal pCO2, temperature and Hb were held within a narrow range during the procedure. Ipsilateral angiography was performed every 10 to 15 minutes. An independent neuroradiologist classified any vasospasm in the parent vessel as mild (25% baseline), moderate (50%), severe (75%), or total (100%). Of all, 15/32 (46.9%) patients developed spasm; in 2 it was severe or total. There was no significant association between World Federation of Neurological Surgeons grade and baseline rSO2 signal (either ipsilateral or contralateral to the side of the aneurysm) (P=0.598). There was no significant association between side of aneurysm and baseline rSO2 signal (P=0.243). However, episodes of angiographic spasm were strongly associated with reduction in trend ipsilateral NIRS signal (P<0.001); furthermore, the degree of spasm (especially more than 75% vessel diameter reduction) was associated with a greater reduction in same-side NIRS signal (P<0.001) (2-level random effects regression model, Stata 8.2, Stata Corp, TX). NIRS may have a useful role to play in the detection of cerebral desaturation secondary to vasospasm during neuroendovascular procedures.

Correlation between near-infrared spectroscopy and magnetic resonance imaging of rat brain oxygenation modulation

We measure the tissue oxygen and haemoglobin concentrations in the rat brain during modulation of inhaled oxygen concentration (FiO2), using non-invasive frequency domain near-infrared oximetry. The rise in oxygenated haemoglobin concentration and the decline in deoxygenated haemoglobin concentration are demonstrated in correspondence with the modulation of FiO2, which is changed from 20% to 100% in increments of 20%. Furthermore, the tissue oxygenation saturation also shows the corresponding trend and changes ranging from approximately 70% to 90%. The relative changes in deoxygenated haemoglobin concentration are compared to the blood-oxygenation-level-dependent (BOLD) MRI signal recorded during a similar FiO2 protocol. A linear relationship with high correlation coefficient between the relative changes in the BOLD MRI signal and the NIRS signal is observed.

Interference of Cerebral Near-Infrared Oximetry in Patients with Icterus

UNLABELLED Near-infrared spectrophotometry assesses cerebral oxygen saturation (ScO(2)) based on the absorption spectra of oxygenated and deoxygenated hemoglobin and the translucency of biological tissue in the near-infrared band. In patients with icterus, however, bilirubin can potentially hinder cerebral oximetry. In 48 patients undergoing orthotopic liver transplantation, we related total plasma bilirubin to ScO(2) as determined from spectrophotometry with wavelengths of 733 and 809 nm. Before surgery, ScO(2) was 59% (15%-78%) (median with range) and bilirubin was 71 (6-619) micromol/L with a negative correlation (r = -0.72; P < 0.05). The 95% prediction interval included the lowest measurable ScO(2) of 15% at a bilirubin level of 370 micromol/L. During reperfusion of the grafted liver, the ScO(2) increased by 7% (-8% to 17%) (P < 0.05), and bilirubin did not influence this increase. In one patient, the ScO(2) remained below 15% despite a decrease in bilirubin from 619 to 125 micromol/L, suggesting that tissue pigmentation deposits also absorb light. In conclusion, bilirubin dampens the spectrophotometry-determined cerebral oxygen saturation at 733 and 809 nm. A bilirubin level of 370 micromol/L, tissue pigment deposits, or both, may render determination of cerebral oxygen saturation impossible. Even at high bilirubin values, changes in cerebral perfusion may be visible. IMPLICATIONS In 48 patients undergoing liver transplantation, the interference of icterus on cerebral oximetry by near-infrared light was investigated. Bilirubin absorbed the near-infrared light and lowered the measured cerebral oxygen saturation. Even at high bilirubin values, changes in cerebral oxygenation, as seen during reperfusion of the grafted liver, may be visible.