Measurement Of Tissue Oxygen Saturation Research Articles

Examining the Hydration Status and Pulse/Oxygen Saturation of Underwater Hockey Players

Objectives: This study was planned to determine the hydration status and tissue oxygen saturation of underwater hockey players during exercise. Materials and Methods: Hydration status (fluid intake/loss amounts, repeatedly weight measurements) and tissue oxygen saturation measurements of 14 underwater hockey players were performed before and after the land/water training, separately. Hydration status was assessed by monitoring weight and urine specific gravity (USG) measurements, whereas tissue oxygen saturation was measured by using finger-type pulse oximeter. Results: The study was completed with14 elite players (age=19.4±6.2 years, female=4(29%), and male=10(71%)). The body fat percentage was calculated to be male:14.2±9.4%; female: 18.8±4.0%. The mean USG of athletes was determined to be 1020.1±5.6 g/cm3. During the water training, only 5 athletes consumed water (680±383.4 mL). All the athletes (except for 1 athlete [7.1%]) completed the training with loss of body fluid. Mean loss of water was 310±213.2 mL after land training and 723.1±501.9 mL after water training. Dehydration ratio was measured 0.97±0.64% after trainings. The first oxygen saturation was measured 96.1±1.6, that was decreased after water training (94.6±2.2; p=0.044, p=0.049). Pulse increased after water training in reverse proportion to oxygen saturation (p=0.004), but there was no difference between before and after land training (p=0.132). Conclusion: It was found that several Underwater hockey players began training dehydrated and loss of water continued since they didn’t consume enough water during training. Oxygen saturation significantly decreased after water training. Fluid consumption of underwater hockey players, especially during water training, should be monitored and adequate fluid consumption should be ensured.

Impact of Peripheral Angioplasty on Wound Oxygenation and Healing in Patients with Chronic Limb-Threatening Ischemia Measured by Near-Infrared Spectroscopy.

Managing chronic limb-threatening ischemia (CLTI) is challenging due to difficulties in assessing tissue oxygen saturation in ulcers. Near-infrared spectroscopy (NIRS) is a non-invasive method for measuring tissue oxygen saturation (StO2). This study evaluated the effects of endovascular treatment (EVT) on StO2 and wound healing in CLTI patients, comparing NIRS to standard ankle-brachial index (ABI) measurements. Using the Duesseldorf PTA Registry, 43 CLTI patients were analyzed: 27 underwent EVT, and 16 received conservative treatment. ABI assessed macrocirculation, while NIRS measured wound, wound area, and mean foot StO2 at baseline, post-EVT, and four-month follow-up. Wound severity was classified by wound area and wound, ischemia, and foot infection (WIfI) score. Wound StO2 increased significantly (median (interquartile range (IQR)), 38 (49.3) to 60 (34.5)%, p = 0.004), as did wound area StO2 (median (IQR), 70.9 (21.6) to 72.8 (18.3)%, p < 0.001), with no significant changes in the control group by four-month follow-up. Wound area decreased significantly after EVT (mean ± SD, 343.1 ± 267.8 to 178.1 ± 268.5 mm2, p = 0.01) but not in the control group. Changes in wound StO2, wound area StO2, and WIfI score correlated with wound area reduction, unlike ABI. This small exploratory study shows that NIRS-measured StO2 improvements after EVT correlate with reduced wound area and WIfI scores, highlighting NIRS as a potential enhancement for CLTI wound management in addition to ABI.

Application of Near Infrared Spectroscopy to Enhance Safety and Individualize Distraction of Severely Contracted Joints in Far-Advanced Dupuytren's Disease.

Background: Slow distraction of contracted joints is a well-established treatment in far-advanced stages of Dupuytren's disease (DD). To assess finger perfusion and avoid malperfusion, we studied near infrared spectroscopy (NIRS) to evaluate the maximum extent of distraction that would not harm microcirculation to the finger. This technique also allows an optimized treatment in accordance with sufficient blood perfusion during distraction. Methods: Eligible patients with stage IV finger contractures who needed treatment for Dupuytren's contracture were included and prospectively investigated. The operation was performed with local anaesthesia. First, the Dupuytren strand of the treated finger was dissected in the palm to allow distraction. Under X-ray control, the distraction device was applied. Then, slow distraction of the treated joint was performed to evaluate the finger perfusion. To assess perfusion of the treated finger, NIRS was used to measure tissue oxygen saturation. If impaired finger perfusion was detected, traction was reduced until sufficient oxygen levels and perfusion patterns were reestablished. Results: NIRS was performed after application of the distraction device in seven cases. We treated six male and one female patient (mean age 70 years, range 51-80 years). Rapid distraction resulted in malperfusion of the treated fingers. Using NIRS proved to render reliable and reproducible information on finger perfusion and oxygenation in all seven patients. Conclusions: Application of NIRS enhances safety in the treatment of far-advanced DD finger contractures with an external skeletal distraction device. It is non-invasive, reproducible, easy to use and allows for an individualized adapted distraction velocity.

Physiologic Determinants of Near-Infrared Spectroscopy-Derived Cerebral and Tissue Oxygen Saturation Measurements in Critically Ill Patients.

Near-infrared spectroscopy (NIRS) is a potentially valuable modality to monitor the adequacy of oxygen delivery to the brain and other tissues in critically ill patients, but little is known about the physiologic determinants of NIRS-derived tissue oxygen saturations. The purpose of this study was to assess the contribution of routinely measured physiologic parameters to tissue oxygen saturation measured by NIRS. An observational sub-study of patients enrolled in the Role of Active Deresuscitation After Resuscitation-2 (RADAR-2) randomized feasibility trial. Two ICUs in the United Kingdom. Patients were recruited for the RADAR-2 study, which compared a conservative approach to fluid therapy and deresuscitation with usual care. Those included in this sub-study underwent continuous NIRS monitoring of cerebral oxygen saturations (SctO2) and quadriceps muscle tissue saturations (SmtO2). Synchronized and continuous mean arterial pressure (MAP), heart rate (HR), and pulse oximetry (oxygen saturation, Spo2) measurements were recorded alongside NIRS data. Arterial Paco2, Pao2, and hemoglobin concentration were recorded 12 hourly. Linear mixed effect models were used to investigate the association between these physiologic variables and cerebral and muscle tissue oxygen saturations. Sixty-six patients were included in the analysis. Linear mixed models demonstrated that Paco2, Spo2, MAP, and HR were weakly associated with SctO2 but only explained 7.1% of the total variation. Spo2 and MAP were associated with SmtO2, but together only explained 0.8% of its total variation. The remaining variability was predominantly accounted for by between-subject differences. Our findings demonstrated that only a small proportion of variability in NIRS-derived cerebral and tissue oximetry measurements could be explained by routinely measured physiologic variables. We conclude that for NIRS to be a useful monitoring modality in critical care, considerable further research is required to understand physiologic determinants and prognostic significance.

Measuring tissue oxygen saturation in the orad intestinal segment during equine colic surgery may aid in predicting the occurrence of postoperative ileus.

To assess the histological injury and intestinal microperfusion measured by laser Doppler flowmetry and spectrophotometry (LDFS) of the small intestine orad to a strangulation during colic surgery. Horses with naturally occurring small intestinal strangulations undergoing colic surgery were included. In this prospective clinical trial, intestinal tissue oxygen saturation (tSO2) and tissue blood flow (tBF) were measured by LDFS orad to the strangulation following release of the strangulation (n = 18). The number of horses with postoperative reflux (POR) and the cases that survived until discharge were compared between groups using Fisher's exact test (P < .05). Intestinal biopsies were taken in cases that underwent intestinal resection or intraoperative euthanasia (n = 28). Measurements were compared between injured and noninjured segments with a Mann-Whitney U or t test. The tSO2 and tBF of the orad intestine were lower than previously reported in healthy horses. Horses with low tSO2 of < 35% were significantly more likely to suffer from POR (6/6 cases) compared to cases with tSO2 > 69% (1/6). The number of horses that survived were not statistically different between these groups (2/6 and 6/6). All horses with mucosal injury developed POR (6/6), which was significantly more likely compared to horses without mucosal injury (3/13). No significant difference in tSO2 or tBF could be found between the segments with and without histological injury. The results suggest that measuring tSO2 in the orad segment during colic surgery may aid in predicting postoperative issues.

Noninvasive estimation of skeletal muscle oxygen consumption rate and microvascular reactivity in chronic stroke survivors using near-infrared spectroscopy.

Understanding post-stroke changes in skeletal muscle oxidative metabolism and microvascular reactivity could help create therapeutic targets that optimize rehabilitative interventions. Due to disuse atrophy, we hypothesized that basal muscle oxygen consumption rate and microvascular endothelial function would be impaired in the tibialis anterior (TA) muscle of the affected leg of chronic stroke survivors compared with the nonaffected leg and versus matched controls. Fifteen chronic stroke survivors (10 females) and 15 matched controls (9 females) completed this study. A near-infrared spectroscopy oximeter measured tissue oxygen saturation (StO2) of the TA in both legs of stroke survivors and the dominant leg of controls. A cuff was placed around the thigh and inflated to 225 mmHg for 5 min while StO2 was continuously measured. The rate of change in StO2 was calculated during cuff occlusion and immediately post-cuff release. The rate of oxygen desaturation was similar between the legs of the stroke survivors (paretic -0.12 ± 0.04%·s-1 vs. nonparetic -0.16 ± 011%·s-1; P = 0.49), but the paretic leg had a reduced desaturation rate versus controls (-0.25 ± 0.18%·s-1; P = 0.007 vs. paretic leg). After cuff release, there was a greater oxygen resaturation rate in the nonparetic leg compared with the paretic leg (3.13 ± 2.08%·s-1 vs. 1.60 ± 1.11%·s-1, respectively; P = 0.01). The control leg had a similar resaturation rate versus the nonparetic leg (control = 3.41 ± 1.79%·s-1; P = 0.69) but was greater than the paretic leg (P = 0.003). The TA in the paretic leg had an impaired muscle oxygen consumption rate and reduced microvascular endothelial function compared with controls.NEW & NOTEWORTHY Secondary consequences of stroke are not well described. In this study, we show that basal muscle oxidative consumption and microvascular endothelial function are reduced in the paretic tibialis anterior muscle of chronic stroke survivors compared with matched controls using near-infrared spectroscopy and the vascular occlusion technique. There was a moderately strong correlation between microvascular endothelial function and paretic leg strength.

Intraoperative Near-infrared Spectroscopy Can Predict Skin Flap Necrosis.

The study aimed to validate the previously identified capacity of near-infrared spectroscopy (NIRS) to detect clinically relevant differences in tissue perfusion intraoperatively. Consecutive patients undergoing oncologic resection requiring flap reconstruction were analyzed. Clinicians were blinded to tissue oxygen saturation (StO2) measurements taken intraoperatively. Measurements were taken at (1) control areas not affected by the procedure, (2) areas at risk of necrosis based on distal location, and (3) areas of skin flap necrosis (SFN) identified during the follow-up period. Mean StO2 values were compared using a single-sample t test and analysis of variance (ANOVA) to determine differences in oxygenation. There were 102 patients included from April 2018 to May 2019. Reconstruction was undertaken following resection for breast cancer (46), melanoma (35), sarcoma (9), and other cutaneous malignancies (12). Breast reconstruction involved 38 alloplastic reconstructions and eight autologous free flaps. Other skin flap reconstruction involved 42 local/regional skin flaps, 13 pedicled flaps, and one free flap. Eighteen patients (17.6%) developed SFN. Mean intraoperative StO2 measurements for control areas, areas at risk, and areas of SFN were 74.8%, 70.9%, and 54.3%, respectively. StO2 values equal to or less than 60% were highly specific (96%) for SFN, whereas StO2 values above 85% were highly sensitive (96%) to rule out SFN. These results further support the use of NIRS to objectively assess variations in skin flap oxygenation and tissue perfusion that are correlated with the development of postoperative SFN.

Multispectral near-infrared spectroscopy study evaluating the effect of razor design on shaving-induced erythema.

While shaving-induced erythema is a common inflammatory skin issue, there is a lack of quantitative information on how well a shaving product performs in this regard. In this study, multispectral near-infrared spectroscopy (NIRS) imaging was used to quantitatively and qualitatively measure the extent of shaving-induced erythema. The research compares a safety razor and a cartridge razor to evaluate their impact on skin irritation. Fifty-nine healthy male volunteers without pre-existing skin conditions were enrolled. Basic demographics were recorded, and participants' faces or necks were imaged before shaving. Shaving was conducted on the right side of the face/neck with the safety razor and on the left side of the face/neck using the 3-blade cartridge razor. Images were captured immediately after shaving, at 5 and 10 min post-shaving. Tissue oxygen saturation (StO2) measurements demonstrated that the safety razor induced significantly less erythema than the cartridge razor. Immediately after shaving, 40.3% of skin shaved with the safety razor had erythema compared to 57.6% for the cartridge razor. At 5 min post-shaving, 36.5% of skin shaved with the safety razor had erythema, compared to 53.8% of cartridge razor. Multispectral NIRS revealed significant differences in shaving-induced erythema between safety and cartridge razors. Safety razors demonstrated a lower incidence of erythema, suggesting a potential advantage for individuals prone to skin irritation. This study contributes valuable insights into skin irritation and highlights the potential of multispectral NIRS in dermatology research.

Assessment of microcirculatory alteration by a vascular occlusion test using near-infrared spectroscopy in pediatric cardiac surgery: effect of cardiopulmonary bypass

ABSTRACT Objectives Cardiopulmonary bypass cause microcirculatory alterations. Near infrared spectroscopic measurement of tissue oxygen saturation and vascular occlusion test are novel technologies for assessing the microcirculatory function of peripheral tissue specifically in patients undergoing cardiac surgery with cardiopulmonary bypass.Our study aimed to evaluate dynamic microcirculatory function using the vascular occlusion testing during cardiac surgery in pediatric patients. Methods 120 pediatric patients were scheduled. Children had continuous regional oxygen saturation monitoring using near infrared spectroscopy and vascular occlusion test. Vascular occlusion test was performed five times; before induction (T1), after induction (T2), then during cardiopulmonary bypass with full flow (T3), after the termination of CPB (T4) and after sternum closure (T5). Results Basal value was the lowest at T3 and this value was significantly different among measurements (p < 0,01).Values for maximum and minimum tissue oxygen saturation were the lowest at T3 (83,4 and 52,9%).The occlusion slope varied significantly among measurements (p < 0,01).Reperfusion slopes were significantly different among measurements (p < 0,01) with a further progressive decrease in reperfusion slope with duration of cardiopulmonary bypass. Conclusion Microcirculatory function can assessed using VOT with forearm Near-infrared spectroscopy derived variables during cardiopulmonary bypass in pediatric cardiac surgery. Noninvasive assessment of microcirculatory perfusion during cardiopulmonary bypass can further help evaluate and improve circulatory support techniques. Trial Registration The research Project was registered at ClinicalTrials.gov (NCT06191913)

Preclinical multi-physiologic monitoring of immediate-early responses to diverse treatment strategies in breast cancer by optoacoustic imaging.

Optoacoustic imaging enables the measurement of tissue oxygen saturation (sO2) and blood perfusion while being utilized for detecting tumor microenvironments. Our aim was to employ multispectral optoacoustic tomography (MSOT) to assess immediate-early changes of hemoglobin level and sO2 within breast tumors during diverse treatments. Mouse breast cancer models were allocated into four groups: control, everolimus (EVE), paclitaxel (PTX), and photodynamic therapy (PDT). Hemoglobin was quantified daily, as well as sO2 and blood perfusion were verified by immunohistochemical (IHC) staining. MSOT showed a temporal window of enhanced oxygenation and improved perfusion in EVE and PTX groups, while sO2 consistently remained below baseline in PDT. The same results were obtained for the IHC. Therefore, MSOT can monitor tumor hypoxia and indirectly reflect blood perfusion in a non-invasive and non-labeled way, which has the potential to monitor breast cancer progression early and enable individualized treatment in clinical practice.

Comment on: Non-invasive measurement of intestinal tissue oxygen saturation for evaluation of reconstructed blood flow in rectal cancer surgery: HiSCO-09 study.

Comment on: Non-invasive measurement of intestinal tissue oxygen saturation for evaluation of reconstructed blood flow in rectal cancer surgery: HiSCO-09 study.

Author response to: Comment on: Non-invasive measurement of intestinal tissue oxygen saturation for evaluation of reconstructed blood flow in rectal cancer surgery: HiSCO-09 study.

Author response to: Comment on: Non-invasive measurement of intestinal tissue oxygen saturation for evaluation of reconstructed blood flow in rectal cancer surgery: HiSCO-09 study.

A novel imaging technology to assess tissue oxygen saturation and its correlation with indocyanine green in the gastric conduit during thoracic esophagectomy

BackgroundAnastomotic leakage in esophagectomy is a serious complication, and assessing blood perfusion in the conduit can help minimize this risk. Indocyanine green is the most widely used method to assess tissue blood flow; however, this technique has disadvantages. Evaluating tissue oxygen saturation in the gastric conduit during thoracic esophagectomy compared with indocyanine green blood perfusion assessment addresses these disadvantages and can be performed easily and repeatedly. MethodsThis was a prospective study of patients with esophageal cancer who underwent thoracic esophagectomy. Intraoperative tissue oxygen saturation and indocyanine green measurements were obtained to determine the anastomotic site and to compare the correlation between the 2 methods. Tissue oxygen saturation and indocyanine green values were obtained at the tip of the gastric conduit, the demarcation line indicating visible perfusion, and the end of the right gastroepiploic artery. ResultsFifty-seven patients were enrolled in this study; 3 developed anastomotic leakage, and all 3 underwent robotic thoracic surgery. The tissue oxygen saturation value decreased gradually toward the tip of the conduit, as did congestion, and was significantly decreased at the tip compared with the value at the demarcation line (P = .001). Mean tissue oxygen saturation differed significantly between the leakage and no-leakage groups at the anastomosis site (P = .04). We found a negative correlation between tissue oxygen saturation and indocyanine green values at the end of the right gastroepiploic artery (r = −0.361; P = .03). ConclusionTissue oxygen saturation imaging was useful in determining the anastomotic site and addressed the disadvantages associated with indocyanine green.

Oxygen Saturation or Tissue Oxygen Determinations on Skin Whose Viability is at Risk.

The triad of ischaemia, neuropathy, and infection are among the principal causes of lower extremity wounds that are commonly prevalent in patients with diabetic foot (DF) a condition in which peripheral arterial disease commonly co-exists. The prevalence of this condition is increasing globally and with it, the mounting costs of its management. One aspect of management is saving limbs and or digits, a crucial part of this process is assessing tissue viability of skin which is a focus of this review: there are other aspects which are well described in the literature. Amputations are offered to limit the damage resulting from acute/chronic ischaemia. Holstein measured skin perfusion pressure using a radioisotope clearance technique to describe critically ischaemic skin; he found 30 mm Hg as the threshold above which healing may reliably be expected. Recent advances in vascular surgery and related technology have informed evidence-based advice to revascularize and save limbs; in practice, this may leave a wound in the distal skin unhealed; managing these raises questions of tissue viability. Much effort has been made to manage, prevent and to better understand these lower extremity wounds using measurements of tissue oxygen, oxygen saturation and skin imaging. The measurement techniques and their relevant merits are examined in this article. Advances in wound management systems and protocols can also facilitate the repair processes, and those which can have a particular impact on restoring or maintaining tissue perfusion are also discussed in the article.

Determination of tissue oxygen saturation by diffuse reflectance spectroscopy.

Tissue oxygenation is a parameter that allows for determining the health status of human beings. In diabetic patients, it is particularly important to evaluate this parameter as an indicator of microcirculatory problems in the extremities. We aim to obtain tissue oxygen saturation from diffuse reflectance measurements. A computational algorithm to automate the methodology was implemented with the aim of establishing a medical diagnosis technique that is non-invasive and easy to apply and requires a short evaluation time. Tissue oxygen saturation measurements were performed on a group of volunteers to whom a vascular occlusion was applied. It was observed that, by increasing the applied pressure to the arm of each volunteer, the tissue oxygen saturation progressively decreased. The results indicate that the developed technique is an effective method for monitoring changes in blood hemodynamics in patients with some type of pathology in which tissue oxygenation is compromised. In addition, the expected behavior of tissue oxygen saturation during a vascular occlusion was obtained. A methodology to obtain tissue oxygen saturation from diffuse reflectance measurements was successfully developed. It meets the necessary characteristics to be considered a technique for obtaining because it can be applied in vivo and non-invasively and does not require a high computational cost; thus it is fast and capable of providing an objective and quantifiable evaluation.

Non-invasive measurement of intestinal tissue oxygen saturation for evaluation of reconstructed blood flow in rectal cancer surgery: HiSCO-09 study.

Non-invasive measurement of intestinal tissue oxygen saturation for evaluation of reconstructed blood flow in rectal cancer surgery: HiSCO-09 study.

Hemodynamics of the oral mucosa during cooling: A crossover clinical trial

ObjectiveOral cryotherapy is used to prevent the onset of oral mucositis, a common and debilitating adverse effect following cancer chemotherapy. A protective mechanism associated with oral cooling is thought to be mediated through reduced tissue microcirculation. The aim of the present study was to examine the underlying mechanism associated with oral mucosal cooling by measuring oral microcirculation and tissue oxygen saturation after cooling with ice chips (IC) and an intraoral cooling device (ICD). Study designIn a single-center randomized crossover study, 10 healthy volunteers were assigned (1:1) randomly to the order in which the two intraoral cooling procedures (IC/ICD) were to be commenced. On day 1, half of the study participants started with IC and then crossed over to intraoral cooling with the ICD on day 2, while the other half of the participants undertook the same two procedures in the reverse order. Total and functional capillary density (T/FCD) and tissue oxygen saturation (StO2) measurements were obtained at baseline and 30 min following oral cooling. ResultsFollowing 30 min of oral cooling, a statistically significant difference was found for FCD between IC and ICD (percentage points; +2 vs. −13; p < 0.05). A statistically significant decrease in StO2 was observed with both IC and ICD (%; 13 vs. 10) after 30 min of cooling as compared to baseline (p < 0.05). As for the participants’ preference the ICD was preferred over IC by 9 out of 10 participants (p = 0.021). ConclusionsBoth microcirculation parameters and tissue oxygen saturation are altered in conjunction with oral cooling, indicating their potential mechanistic contribution towards cryoprevention of oral mucositis.

Point-of-Care Tissue Oxygenation Assessment with SnapshotNIR for Alloplastic and Autologous Breast Reconstruction.

Patients receiving immediate alloplastic reconstruction after mastectomy or autologous reconstruction were enrolled. Preoperative, intraoperative, and postoperative images were taken of the flaps. StO2 and hemoglobin were measured at the following locations: superior and inferior breast, free flap skin paddle (when applicable), and un-operated control skin. Linear mixed effects model for repeated measurements was used to model measurements to estimate the area effect difference across time, time effect difference across area, and pairwise comparisons between two areas at each time point. Thirty-two breasts underwent alloplastic reconstruction; 38 breasts underwent autologous reconstruction. No enrollees developed skin necrosis. StO2 was highest after mastectomy and closure in alloplastic reconstructions. StO2 was observed to decline at follow-up in autologous reconstructions. Mean preoperative StO2 was highest in breasts that had previously undergone mastectomy and alloplastic reconstruction. The SnapshotNIR device detected normal spatial and temporal differences in tissue oxygenation over the operative course of alloplastic and autologous breast reconstruction. A multi-institutional, prospective clinical trial is needed to determine the sensitivity and specificity of this device for detecting skin flap necrosis.

Two-layered blood-lipid phantom and method to determine absorption and oxygenation employing changes in moments of DTOFs.

Near-infrared spectroscopy (NIRS) is an established technique for measuring tissue oxygen saturation (StO2), which is of high clinical value. For tissues that have layered structures, it is challenging but clinically relevant to obtain StO2 of the different layers, e.g. brain and scalp. For this aim, we present a new method of data analysis for time-domain NIRS (TD-NIRS) and a new two-layered blood-lipid phantom. The new analysis method enables accurate determination of even large changes of the absorption coefficient (Δµa) in multiple layers. By adding Δµa to the baseline µa, this method provides absolute µa and hence StO2 in multiple layers. The method utilizes (i) changes in statistical moments of the distributions of times of flight of photons (DTOFs), (ii) an analytical solution of the diffusion equation for an N-layered medium, (iii) and the Levenberg-Marquardt algorithm (LMA) to determine Δµa in multiple layers from the changes in moments. The method is suitable for NIRS tissue oximetry (relying on µa) as well as functional NIRS (fNIRS) applications (relying on Δµa). Experiments were conducted on a new phantom, which enabled us to simulate dynamic StO2 changes in two layers for the first time. Two separate compartments, which mimic superficial and deep layers, hold blood-lipid mixtures that can be deoxygenated (using yeast) and oxygenated (by bubbling oxygen) independently. Simultaneous NIRS measurements can be performed on the two-layered medium (variable superficial layer thickness, L), the deep (homogeneous), and/or the superficial (homogeneous). In two experiments involving ink, we increased the nominal µa in one of two compartments from 0.05 to 0.25 cm-1, L set to 14.5 mm. In three experiments involving blood (L set to 12, 15, or 17 mm), we used a protocol consisting of six deoxygenation cycles. A state-of-the-art multi-wavelength TD-NIRS system measured simultaneously on the two-layered medium, as well as on the deep compartment for a reference. The new method accurately determined µa (and hence StO2) in both compartments. The method is a significant progress in overcoming the contamination from the superficial layer, which is beneficial for NIRS and fNIRS applications, and may improve the determination of StO2 in the brain from measurements on the head. The advanced phantom may assist in the ongoing effort towards more realistic standardized performance tests in NIRS tissue oximetry. Data and MATLAB codes used in this study were made publicly available.

Cerebral Tissue Oxygen Saturation Measurements in Perinatal Asphyxia Cases Treated with Therapeutic Hypothermia.

Cerebral tissue oxygen saturation (CrSO2) measured with near-infrared spectroscopy (NIRS) technology has recently become the subject of several research studies. The aim of this study was to investigate the diagnostic value of CrSO2 measurements in perinatal asphyxia (PA) cases. The study included a patient group of 42 PA cases, who were to be applied with therapeutic hypothermia (TH), and a control group of 42 healthy term newborns. PA cases were determined as moderate or severe encephalopathy (Sarnat score stage II or III) in clinical evaluation. In both groups, left (CrSO2L) and right (CrSO2R) NIRS measurements were taken for 10 minutes on the scalp. The arithmetic mean value of measurements was calculated and compared. The mean measurements were CrSO2R 67.38 ± 9.39 and CrSO2L 66.73 ± 7.76 in the patient group, and CrSO2R 80.28 ± 8.04 and CrSO2L 79.14 ± 8.49 in the control group. The mean CrSO2R and CrSO2L measurements of the patient group were statistically significantly lower than those of the control group (p < 0.001). In the Pearson correlation analysis, a significant correlation was determined in the patient group between cord blood gas pH and CrSO2R (r: 0.539, p < 0.001) and CrSO2L (r: 0.54, p < 0.001). For a cutoff value of CrSO2L ≤ 72%, the positive predictive value was 80 and the negative predictive value was 84.6. For a cutoff value of CrSO2R ≤ 74%, the positive predictive value was 79.5 and the negative predictive value was 82.5. Low CrSO2 measurements obtained with the NIRS method in PA cases to be applied with TH together with cord blood gas parameters can be considered a helpful parameter in diagnosis.