Changes in regional tissue oxygen saturation values during the first week of life in stable preterm infants.

OBJECTIVES: Near infrared spectroscopy (NIRS) is a non-invasive method for monitoring regional tissue oxygen saturation (rSO2). The purpose of this study is to investigate the changes that occur in cerebral, splanchnic, and renal rSO2 and fractional tissue oxygen extraction (FTOE) in stable preterm infants in the first week of life. METHODS: Prospective observational study of infants born 30-34 weeks gestation at NYU Langone Health between November 2017 and November 2018. Cerebral, renal, and splanchnic rSO2 were monitored from 12 to 72 h of life, and at seven days. Subjects were divided into gestational age (GA) cohorts. Average rSO2, splanchnic cerebral oxygen ratio (SCOR), FTOE, and regional intra-subject variability was calculated at each location at five different time intervals: 0-12 h, 12-24 h, 24-48 h, 48-72 h, and one week of life. RESULTS: Twenty subjects were enrolled. The average cerebral rSO2 ranged from 76.8 to 92.8 %, renal rSO2 from 65.1 to 91.1 %, and splanchnic rSO2 from 36.1 to 76.3 %. The SCOR ranged from 0.45 to 0.94. The strongest correlation between the GA cohorts was in the cerebral region (R2=0.94) and weakest correlation was in the splanchnic region (R2=0.81). The FTOE increased in all three locations over time. Intra-subject variability was lowest in the cerebral region (1.3 % (±1.9)). CONCLUSIONS: The cerebral region showed the strongest correlation between GA cohorts and lowest intra-subject variability, making it the most suitable for clinical use when monitoring for tissue hypoxia. Further studies are needed to further examine rSO2 in preterm infants.

Cognitive Function Deterioration After Cardiopulmonary Bypass: Can Intraoperative Optimal Cerebral Regional Tissue Oxygen Saturation Predict Postoperative Cognitive Function?

OBJECTIVE: Cognitive impairment is a common neurologic complication after cardiac surgery with cardiopulmonary bypass (CPB). This study evaluated postoperative cognitive function to determine predictors of cognitive dysfunction, including intraoperative cerebral regional tissue oxygen saturation (rSO2). DESIGN: A prospective observational cohort study. SETTING: At a single academic tertiary-care center. PARTICIPANTS: A total of 60 adults undergoing cardiac surgery with CPB from January to August 2021. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: All patients underwent Mini-Mental State Examination (MMSE) and quantified electroencephalography (qEEG) 1 day before cardiac surgery, 7 days postoperatively (POD7), and POD60. Intraoperative cerebral rSO2 was monitored continuously. For MMSE, no significant decrease in MMSE score was found on POD7 versus preoperatively (p = 0.09), but POD60 scores showed significant improvement compared with both preoperative (p = 0.02) and POD7 scores (p < 0.001). On qEEG, relative theta power on POD7 was increased versus preoperatively (p < 0.001), but it was decreased on POD60 (POD7 versus POD60, p < 0.001), and was close to preoperative data (p > 0.99). Baseline rSO2 was an independent factor for postoperative MMSE. Both baseline and mean rSO2 showed a significant influence in postoperative relative theta activity, whereas mean rSO2 was the only predictor for the theta-gamma ratio (p = 0.04). CONCLUSIONS: The MMSE in patients undergoing CPB declined at POD7 and recovered by POD60. Lower baseline rSO2 indicated a higher potential for MMSE decline at POD60. Inferior intraoperative mean rSO2 was related to higher postoperative relative theta activity and theta-gamma ratio, implying subclinical or further cognitive impairment.

Regional oxygen saturation measured by two different oximetry monitors in infants and children undergoing living donor liver transplantation with bilirubin measurements: A prospective observational study.

BACKGROUND: Tissue oximetry devices use wavelengths in the 680-870 nm range to separate between oxygenated/deoxygenated hemoglobin. Conjugated bilirubin has an absorption peak at 730 nm. AIMS: We hypothesized that ForeSight Elite using 5 wavelengths reduces interference from bilirubin and shows higher regional tissue oxygen saturation (rSO2 ) than INVOS 5100C incorporating 2 wavelengths. METHODS: Infants and children undergoing living donor liver transplantation were included between March 2019 and September 2020. Cerebral and somatic rSO2 were measured, and real-time simultaneous data were collected. Additionally, measurements were collected at (1) baseline, (2) beginning of dissection phase, (3) beginning of anhepatic phase, (4) reperfusion phase, and (5) skin closure. Bilirubin level was available at baseline and at reperfusion. Hyperbilirubinemia was defined as bilirubin level ≥1.0 mg/dl. RESULTS: Thirty-three patients with median age of 27 months and median weight of 12 kg were included. Baseline bilirubin levels were higher compared to values at reperfusion (p = .021). A linear mixed effects model considering bilirubin as fixed and patient as random effect showed that there was a statistically significant difference in cerebral rSO2 readings in function of time (p = .031), device (p < .001), and bilirubin concentrations (p = .007) but not for hemoglobin (p = .347), SpO2 (p = .882), and arterial partial pressure of CO2 (Pa CO2 ) (p = .146). The model showed that there was a statistically significant difference in somatic rSO2 readings in function of device (p < .001) and bilirubin concentrations (p = .023) but not for time (p = .074), hemoglobin (p = .954), SpO2 (p = .108), and Pa CO2 (p = .775). Bland-Altman plot analyzing cerebral and somatic rSO2 between both devices showed respectively a mean absolute bias and 95% limits of agreement of 21.73% (-10.21 to 53.67) and 19.52% (-29.51 to 68.54). CONCLUSIONS: Oximetry devices emitting light at >2 wavelengths may overcome interference from hyperbilirubinemia providing higher rSO2 readings.

Evaluation of the blood flow in reconstructed gastric tube and its relation to anastomosis leakage.

OBJECTIVES: Anastomotic leakage in esophageal cancer surgery may be reduced by evaluating the blood flow to the reconstructed organ, but quantitative evaluation of arterial and venous blood flow is difficult. This study aimed to quantitatively assess blood flow using a new technique, as well as determine the relationship between the blood flow in the gastric tube and anastomotic leakage using near-infrared spectroscopy. METHODS: This single-center, observational study included 50 patients aged 51-82 years who underwent radical esophagectomy with gastric tube reconstruction for esophageal cancer between June 2022 and January 2023. Regional tissue oxygen saturation was measured at the antrum (point X), the anastomotic point (point Z), and the midpoint between points X and Z (point Y) before and after gastric tube formation. These three points of oxygen saturation were investigated in relation to anastomotic leakage. RESULTS: When comparing the presence of leakage to its absence, regional tissue oxygen saturation at points X and Z after gastric tube formation was significantly lower (X: p = 0.03, Z: p = 0.02), with the decreasing rate significantly higher at point Z (p = 0.01). There was no significant difference in the decreasing rate of regional tissue oxygen saturation between points X and Y (X: p = 0.052, Y: p = 0.83). CONCLUSION: Regional tissue oxygen saturation levels may be useful for measuring blood flow and could be a predictor of anastomotic leakage.

Cerebral and peripheral regional oxygen saturation during postnatal transition in preterm neonates.

OBJECTIVE: To evaluate peripheral regional oxygen saturation (rpSO2) and cerebral regional oxygen saturation (rcSO2) during the immediate postnatal transition in late preterm infants with and without the need for respiratory support. STUDY DESIGN: This was a prospective observational study using near-infrared spectroscopy to evaluate changes in rpSO2 and rcSO2. These variables were measured during the first 15 minutes of life after elective cesarean delivery. Peripheral oxygen saturation (SpO2) and heart rate were measured continuously by pulse oximetry, and cerebral fractional tissue oxygen extraction (cFTOE) was calculated. Two groups were compared based on their need for respiratory support: a respiratory support group and a normal transition group. Positive-pressure ventilation was delivered with a T-piece resuscitator, and oxygen was adjusted based on SpO2 values. A Florian respiratory function monitor was used to record the ventilation variables. RESULTS: There were 21 infants in the normal transition group and 21 infants in the respiratory support group. Changes in heart rate over time were similar in the 2 groups. SpO2, rcSO2, and rpSO2 values were consistently higher in the normal transition group. In the respiratory support group, cFTOE values remained significantly elevated for a longer period. CONCLUSION: This systematic analysis of rpSO2, rcSO2, and cFTOE in late preterm infants found significantly lower oxygen saturation values in infants who received respiratory support compared with a normal transition group. We hypothesize that the elevated cFTOE values in the respiratory support group represent compensation for lower oxygen delivery.

Reference ranges for regional cerebral tissue oxygen saturation and fractional oxygen extraction in neonates during immediate transition after birth.

OBJECTIVE: To define reference ranges for regional cerebral tissue oxygen saturation (crSO2) and regional cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 minutes after birth in neonates requiring no medical support. STUDY DESIGN: The crSO2 was measured using near infrared spectroscopy (Invos 5100 cerebral/somatic oximeter monitor; Somanetics Corp, Troy, Michigan) during the first 15 minutes after birth for term and preterm neonates. The near infrared spectroscopy sensor was placed on the left forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry, and cFTOE was calculated. Neonates were excluded if they required any medical support. RESULTS: A total of 381 neonates were included: 82 term neonates after vaginal delivery, 272 term neonates after cesarean delivery, and 27 preterm neonates after cesarean delivery. In all neonates, median (10th-90th percentiles) crSO2 was 41% (23-64) at 2 minutes, 68% (45-85) at 5 minutes, 79% (65-90) at 10 minutes, and 77% (63-89) at 15 minutes of age. In all neonates, median (10th-90th percentiles) cFTOE was 33% (11-70) at 2 minutes, 21% (6-45) at 5 minutes, 15% (5-31) at 10 minutes, and 18% (7-34) at 15 minutes of age. CONCLUSION: We report reference ranges of crSO2 and cFTOE in neonates requiring no medical support during transition immediately after birth. The use of cerebral oxygenation monitoring and use of these reference ranges in neonates during transition may help to guide oxygen delivery and avoid cerebral hypo-oxygenation and hyperoxygenation.

Real-Time Assessment of Tissue Oxygen Saturation Using a Novel Oximeter During Revascularization for Acute Limb Ischemia: A Case Report.

Emergency surgery was performed to treat acute lower limb ischemia caused by heart thromboembolism and concomitant popliteal artery aneurysm. Using a near-infrared spectroscopy oximeter, regional tissue oxygen saturation (rSO2) was monitored to assess the tissue perfusion pre-, intra-, and postoperatively. rSO2 values did not increase sufficiently following thromboembolectomy of the superficial femoral artery, but they dramatically recovered after additional popliteal-anterior tibial bypass surgery. The affected limb was successfully salvaged. rSO2 monitoring was easily measured intraoperatively, which might be beneficial in evaluating tissue perfusion in patients with acute limb ischemia.

Near-Infrared Spectroscopy to Guide and Understand Effects of Red Blood Cell Transfusion.

This review is a summary of available evidence regarding the use of near-infrared spectroscopy (NIRS) to help better guide and understand the effects of red blood cell (RBC) transfusion in neonatal patients. We review recent literature demonstrating the changes that take place in regional tissue oxygen saturation (rSO2) resulting from RBC transfusion. We also discuss in detail if any correlation exists between rSO2 and hemoglobin values in neonates. Finally, we review studies that have evaluated the use of NIRS as a transfusion guide during neonatal intensive care.

The diagnostic value of pulmonary near-infrared spectroscopy in the early distinction of neonatal pneumonia from transient tachypnea of the newborn.

AIM: Pulmonary near-infrared spectroscopy (NIRS) is a new and promising tool for diagnosis of neonatal respiratory diseases (RD). The study aimed to determine the role of pulmonary regional oxygen saturation (pRSO2 ) values obtained by NIRS in the early distinction of neonatal pneumonia (NP) from transient tachypnea of the newborn (TTN). METHODS: This prospective, observational, double-blind study was conducted in neonatal intensive care unit (NICU) between 2020 and 2021. Late preterm and term newborns hospitalized in the NICU due to the diagnosis of TTN and NP were included. Cerebral RSO2 and pRSO2 values were measured during the 1st, 24th, 48th, and 72nd hours of hospitalization, using NIRS. RESULTS: Of the eligible 40 infants, 65% (n: 26) were diagnosed as TTN and 35% (n: 16) as NP. The pRSO2 values were significantly higher in the TTN group than the NP group for both apexes (75.3 ± 8.7 vs. 69 ± 5.4, p: .018, respectively) and lateral lung (77.8 ± 6 vs. 72.7 ± 6.2, p: .016, respectively) in the 1st hour of hospitalization. There were significant differences in pRSO2 apex and pRSO2 lateral values between the 1st and 24th hours of hospitalization and the 24th and 48th hours in the NP group (p2 : .001 for both). The optimal pRSO2 apex cut-off value was >72% to predict the diagnosis of NP with a sensitivity of 78.6% and a specificity of 69.2%. CONCLUSION: Pulmonary NIRS may be considered as a feasible and promising diagnostic tool in late preterm and term infants with RD. It may also be helpful for the early differentiation of NP from TTN and the courses of these diseases.

Significant Correlation between Regional Tissue Oxygen Saturation and Vital Signs of Critically Ill Infants.

BACKGROUND: Near-infrared spectroscopy (NIRS) has been used to non-invasively measure specific tissue oxygen saturation (StO2) continuously. Cerebral autoregulation status can be derived from NIRS and arterial blood pressure. The relationship of both cerebral and somatic StO2, fractional tissue oxygen extraction (FTOE), and cerebro-splanchnic oxygenation ratio (CSOR) with measured vital sign parameters for Neonatal Intensive Care Unit (NICU) patients has not been well studied. OBJECTIVE: The aims of this study are to determine if significant relationships of brain and somatic StO2, brain and somatic FTOE, and CSOR parameters with vital signs for neonates exist and assess relationship between pressure passivity index, cerebral autoregulation, and mean blood pressure (MBP). DESIGN/METHODS: Neonates weighing < 5 kg, preferentially with an arterial catheter, were enrolled in the study. FORE-SIGHT Elite (CASMedical Systems, Inc., Branford, CT, USA) cerebral and somatic NIRS sensors were placed over the abdominal right upper quadrant and right frontal-temporal area of the forehead for 24 h. Vital signs including arterial MBP were recorded simultaneously from the patients' bedside monitor. Data were averaged into 60 s windows and analyzed using linear regression. Results were stratified by gestational age (GA), birth weight (BW), and presence of brain abnormality. RESULTS: Data were obtained from 27 subjects (GA 22.2-42 weeks). Two subjects did not have an arterial line, thus they were not included in the MBP measurements. There were ~28,000-31,000 paired data points per comparison. Significant positive and negative correlations (p value < 0.0001) were noted between NIRS parameters and vital signs. When stratified by BW, there was a positive correlation between brain StO2 (StO2B) and MBP in the <1,500 g BW group (r = 0.193) and a negative correlation in >1,500 g group (r = 0.057). Brain and somatic FTOE in <1,500 g BW revealed a negative correlation with MBP (r = 0.172 and r = 0.086, respectively). In patients with an abnormal brain scan, a positive correlation was noted between StO2B and MBP (r = 0.354), and a negative correlation was noted between FTOE-B and MBP (r = 0.305). Generated pressure passive index plots suggested good cerebral autoregulation at low normal MBP ranges for lower weight and GA subjects. CONCLUSION: There is a significant correlation between cerebral and somatic StO2 and FTOE with measured vital sign parameters in NICU patients.

Near-infrared spectroscopy to assess microvascular dysfunction: A prospective pilot study in cardiac surgery patients.

PURPOSE: The diagnosis of microvascular dysfunction remains challenging after cardiac surgery. We hypothesized that peripheral near-infrared spectroscopy (NIRS) monitoring in combination with a vascular occlusion test could reliably assess postoperative microvascular dysfunction in that setting. MATERIALS AND METHODS: Twenty-two patients undergoing cardiac surgery with cardiopulmonary bypass and 10 healthy volunteers were prospectively investigated. Relevant NIRS parameters (regional tissue oxygen saturation, desaturation, and resaturation rates) were recorded the day before surgery (D-1), at the arrival in the intensive care unit (postoperative day [POD] 0) and on POD 1 and POD 2. RESULTS: No difference in NIRS parameters was found at baseline between healthy volunteers and cardiac surgical patients. Absolute values of regional tissue oxygen saturation significantly increased at POD 0 and POD 1 when compared with D-1: 78% (75%-81%) and 75% (73%-78%) vs 68% (64%-72%), P < .001. No statistical difference was evidenced within the postoperative period in desaturation and resaturation rates compared with D-1: desaturation rate, 0.11% · s(-1) (0.08-0.14) and 0.15% · s(-1) (0.08-0.22) vs 0.14% · s(-1) (0.10-0.17), P = .233, and resaturation rate, 0.76% · s(-1) (0.41-1.11) and 0.77% · s(-1) (0.53-1.02) vs 0.79% · s(-1) (0.61-0.97), P = .453. The use of postoperative norepinephrine infusion did not change the results. CONCLUSIONS: Peripheral NIRS monitoring in combination with a vascular occlusion test failed to assess cardiopulmonary bypass-induced microvascular dysfunction.

Is there a competition for oxygen availability between respiratory and limb muscles?

If a competition between the oxygen demands of limb and respiratory muscles happens, hypoxia may favor redistribution of blood flow from peripheral to respiratory muscles during heavy exercise. This hypothesis was tested in eighteen lowlanders and 27 highlanders at 4350m altitude. During an incremental exercise, the regional tissue oxygen saturation (rSO2) and tissue hemoglobin concentration ([Hbt]) of the intercostal muscles and vastus medialis were monitored simultaneously by NIRS. The intercostal and vastus medialis rSO2 values were lower at altitude than at sea level (-10%, p<0.001) and decreased similarly during incremental exercise (p<0.001) while [Hbt] values increased. At maximal exercise, the intercostal rSO2 was lower than the vastus medialis rSO2 in lowlanders (-7%, p<0.001). In highlanders the time patterns were similar but intercostal rSO2 was less decreased at exercise (p<0.05). Maximal exercise performed in hypoxia did not alter the kinetics of rSO2 and [Hbt] in peripheral muscles. These findings do not favor the hypothesis of blood flow redistribution.