Regional Brain Oxygen Saturation Research Articles

Regional Brain Oxygen Saturation: There is also Life Beyond the Brain.

Some procedures, such as cardiovascular surgery, may compromise brain perfusion and require careful management to preserve the integrity of the central nervous system. In this setting, regional cerebral oxygen saturation [rSO2] emerges as an alternative, minimally invasive, monitoring system. The mechanism by which regional oxygen is measured is based on the refraction and absorption of a signal with a specific wavelength. Diagnostic and therapeutic algorithms for these settings would allow for a more rational use of goal-directed therapies that reduce morbidity and mortality in these patients.

Incidence of hyperoxia and factors associated with cerebral oxygenation during cardiopulmonary resuscitation

BackgroundHigh oxygen levels may worsen cardiac arrest reperfusion injury. We determined the incidence of hyperoxia during and immediately after successful cardiopulmonary resuscitation and identified factors associated with intra-arrest cerebral oxygenation measured with near-infrared spectroscopy (NIRS). MethodsA prospective observational study of out-of-hospital cardiac arrest patients treated by a physician-staffed helicopter unit. Collected data included intra-arrest brain regional oxygen saturation (rSO2) with NIRS, invasive blood pressures, end-tidal CO2 (etCO2) and arterial blood gas samples. Moderate and severe hyperoxia were defined as arterial oxygen partial pressure (paO2) 20.0–39.9 and ≥40 kPa, respectively. Intra-arrest factors correlated with the NIRS value, rSO2, were assessed with the Spearman’s correlation test. ResultsOf 80 recruited patients, 73 (91%) patients had rSO2 recorded during CPR, and 46 had an intra-arrest paO2 analysed. ROSC was achieved in 28 patients, of whom 20 had paO2 analysed. Moderate hyperoxia was seen in one patient during CPR and in four patients (20%, 95% CI 7–42%) after ROSC. None had severe hyperoxia during CPR, and one patient (5%, 95% 0–25%) immediately after ROSC. The rSO2 during CPR was correlated with intra-arrest systolic (r = 0.28, p < 0.001) and diastolic blood pressure (p = 0.32, p < 0.001) but not with paO2 (r = 0.13, p = 0.41), paCO2 (r = 0.18, p = 0.22) or etCO2 (r = 0.008, p = 0.9). ConclusionHyperoxia during or immediately after CPR is rare in patients treated by physician-staffed helicopter units. Cerebral oxygenation during CPR appears more dependent, albeit weakly, on hemodynamics than arterial oxygen concentration.

Effects of Temperature and Position Change on Neonatal Brain Regional Oxygen Saturation in Tub Bathing: A Prospective Study.

IntroductionA major goal in neonatal medicine is to reduce stress as much as possible in routine care. Bathing is one of the important routine cares for neonates, but it makes a big environmental change for them. We aimed to examine whether water temperature, room temperature, and position changes in tub bathing serve as noxious stimuli to neonates.MethodsThis prospective trial was performed in full-term and non-low-birth-weight neonates admitted to the hospital between July 2020 and March 2021. Those with underlying diseases, fetal distress, infection, and other medical conditions were excluded. Measurements were taken during the neonates’ first tub bath since birth, which was performed by a trained nurse. Changes in regional oxygen saturation (rSO2), determined using near-infrared spectroscopy, and water and room temperature, were examined at five different time points: upon entering the bath, head washing, position change, exiting the bath, and during the 3 min after bathing.ResultsIn total, 17 neonates were analyzed. No changes in rSO2 due to head washing or position change were observed; however, rSO2 significantly decreased upon entering (78.5 ± 4.1% vs. 75.7 ± 4.1%, p < 0.001) and exiting the bath (75.8 ± 5.7% vs. 74.4 ± 5.4%, p < 0.04). The rate change in rSO2 upon entering the bath showed a significant inverse correlation with water temperature (r = − 0.53, p < 0.03), and there were no significant correlations between rSO2 and water or room temperature upon exiting the bath. There was no change in body skin temperature before and after bathing, but rSO2 gradually decreased during the 3 min after bathing.ConclusionsNeonates may perceive certain temperatures during bathing as noxious stimuli. Therefore, methods to minimize stress associated with bathing should be implemented to reduce the difference between water temperature and room temperature during bathing.Trial registrationThis trial has been registered at UMIN repository with the trial number UMIN000041045 (https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000046500). The date of the final dataset was April 01, 2021.

Impaired Right Ventricular Performance Is Associated with Adverse Outcome after Hypoxic Ischemic Encephalopathy.

Rationale: Asphyxiated neonates with hypoxic ischemic encephalopathy (HIE) are at risk of myocardial dysfunction; however, echocardiography studies are limited and little is known about the relationship between hemodynamics and brain injury.Objectives: To analyze the association between severity of myocardial dysfunction and adverse outcome as defined by the composite of death and/or abnormal magnetic resonance imaging.Methods: Neonates with HIE undergoing therapeutic hypothermia were enrolled. Participants underwent echocardiography at 24 hours, 72 hours (before rewarming), and 96 hours (after rewarming). Cerebral hemodynamics were monitored by near-infrared spectroscopy and middle cerebral artery Doppler.Measurements and Main Results: Fifty-three patients with a mean gestation and birthweight of 38.8 ± 2.0 weeks and 3.33 ± 0.6 kg, respectively, were recruited. Thirteen patients (25%) had mild encephalopathy, 27 (50%) had moderate encephalopathy, and 13 (25%) had severe encephalopathy. Eighteen patients (34%) had an adverse outcome. Severity of cardiovascular illness (P < 0.001) and severity of neurologic insult (P = 0.02) were higher in neonates with adverse outcome. Right ventricle (RV) systolic performance at 24 hours was substantially lower than published normative data in all groups. At 24 hours, lower tricuspid annular plane systolic excursion (P = 0.004) and RV fractional area change (P < 0.001), but not pulmonary hypertension, were independently associated with adverse outcome on logistic regression. High brain regional oxygen saturation (P = 0.007) and low middle cerebral artery resistive index (P = 0.04) were associated with RV dysfunction on post hoc analysis.Conclusions: RV dysfunction is associated with the risk of adverse outcome in asphyxiated patients with HIE undergoing hypothermia. Echocardiography may be a valuable diagnostic and prognostic tool in this vulnerable population.

Quantitative evaluation using single-photon emission computed tomography with acetazolamide is reliable for preoperative evaluation before cardiac surgery in severe carotid intracranial artery stenotic and/or occlusive disease: a case report

BackgroundSevere carotid and intracranial artery stenosis disease (CIAD) is major risk for perioperative stroke in coronary artery bypass grafting. Then, preoperative risk assessment is quite important.Case presentationA 58-years old Japanese woman with bilateral carotid stenosis and bilateral middle cerebral artery occlusion was suffered from worsening effort angina due to severe three coronary vessel disease. Magnetic resonance imaging angiography demonstrated severe carotid and intracranial vessel stenosis. Selective carotid/cerebral angiography also showed severe stenosis and delayed filling of the right internal carotid artery and moderate stenosis of the left internal carotid artery, with occlusion of the bilateral middle cerebral arteries. However, quantitative evaluation with brain perfusion, single-photon emission computed tomography (SPECT) with acetazolamide showed depleted cerebral perfusion volume and vascular responses, particularly in the left middle cerebral artery area. However, both sides of MCA reserve cerebral blood flow was maintained at > 34 ml/100 g/min. So, we finally considered that her cerebral perfusion reserve was maintained a certain level and could tolerate open heart surgery. Then, she underwent off-pump coronary artery grafting. Before sternotomy, prophylactic intra-aortic balloon pump support was used to minimize possible perioperative stroke. As a result, hemodynamic status and brain regional oxygen saturation were stable throughout the operation, and recovered uneventfully.ConclusionsPreoperative quantitative evaluation using brain perfusion SPECT with acetazolamide is useful in assessing hemodynamic cerebrovascular risk in patients with severe obstructive CIAD. Off pump coronary artery bypass grafting with intra aortic balloon pump assist is a good option for prevention of cerebrovascular morbidity in ischemic heart disease with severe CIAD.

Brain regional oxygen saturation monitoring by emergency medical stuff for goal-directed resuscitation

Brain regional oxygen saturation monitoring by emergency medical stuff for goal-directed resuscitation

Cerebral Near-Infrared Spectroscopy: A Potential Approach for Thrombectomy Monitoring.

Regional brain oxygen saturation (rSO2) changes, assessed by cerebral near-infrared spectroscopy, are likely influenced by cerebral hemodynamic fluctuations induced by thrombectomy of acute proximal occlusion. We studied the correlations between rSO2 and baseline magnetic resonance imaging perfusion parameters and the relationship between rSO2 changes, recanalization, and clinical outcome. Seventeen acute ischemic stroke patients, treated with mechanical thrombectomy, were monitored using bilateral near-infrared spectroscopy before, during, and continuously for 24 hours after the procedure. All patients had baseline brain magnetic resonance imaging with perfusion weighted imaging. rSO2 was only correlated with baseline Tmax (ρ=-0.42; P<0.05) and mean transit time (ρ=-0.45; P<0.05) within forehead explored areas. Before thrombectomy, an interhemispheric rSO2 difference was noted, and this diminished over time when recanalization had occurred (median [interquartile range], -8 [-12 to -5] to 3 [-3 to 7]; P=0.01). rSO2 changes were not correlated with clinical outcome. rSO2 was merely correlated with baseline Tmax and mean transit time magnetic resonance imaging perfusion parameters. Multiple sites recording beyond frontal pole explored areas may provide more relevant correlation with hemodynamic parameters.

Keep Ventilating the Lungs While the Heart is Still Ejecting on Femoro-femoral Cardiopulmonary Bypass

Femoro-femoral cardiopulmonary bypass (CPB) followed by deep hypothermic circulatory arrest is one of the modalities used for ascending aortic pseudoaneurysm repair to achieve cardiac unloading and to avoid severe hemorrhage due to the risk of rupture during the sternal entry. However, due to the limited size of the cannulas, it can be challenging to achieve total cardiopulmonary support. Therefore, despite the achievement of total cardiopulmonary support, the heart may still be able to eject antegrade blood flow that meets the retrograde blood flow from the arterial side of the CPB. The point where the blood flow meets in the aorta is called the watershed area. If the antegrade blood flow is large due to a left ventricular ejection, the watershed area will be located in the descending aorta. Therefore, if ventilation is stopped, deoxygenated blood will be ejected to the cerebral circulation. Cerebral near-infrared spectroscopy (NIRS) may be used as a noninvasive and continuous measurement of regional brain oxygen saturation (rSO2). This case demonstrates that cerebral desaturation due to discontinued mechanical ventilation, when the heart was still ejecting during the initial phase of femoro-femoral CPB, immediately was detected by a pronounced drop bilaterally: In the left frontal lobe, rSO2 fell from 56% to 21%, and in the right frontal lobe it fell from 47% to 25%. The authors recommend monitoring cerebral saturation using NIRS in the case of femoro-femoral CPB.

Comprehensive pre- and in-hospital near-infrared-spectroscopy can predict outcome parameters in patients after out-of-hospital cardiac arrest – A feasibility study

Background: The increase of regional brain oxygen saturation (rSO2) levels measured with Near-infrared-Spectroscopy during advanced life support in patients with out-of hospital cardiac arrest (OHCA) is associated with a higher likelihood of Return of Spontaneous Circulation (ROSC) and can predict neurological outcome.

Abstract 14016: Severity Assessment of Brain Damage With rSO2 monitoring for Extracorporeal Cardiopulmonary Resuscitation After Out-of-hospital Cardiac Arrest

Introduction: Decisions regarding extracorporeal cardiopulmonary resuscitation (E-CPR) for patients after out-of-hospital cardiac arrest (OHCA) are difficult to make. Hypothesis: We hypothesized that regional brain oxygen saturation (rSO2) value monitoring in the emergency room was useful for speculating on brain damage severity for prognostication for E-CPR after OHCA. Methods: The J-POP registry is a prospective multicenter cohort study to test whether rSO2 predicts neurological outcomes after nontraumatic OHCA. We measured rSO2 values in OHCA patients immediately after hospital arrival with a near-infrared spectrometer placed on the forehead. The primary endpoint was neurological outcome (cerebral performance category: 1, 2) 90 days after OHCA. Results: We consecutively enrolled 1,921 OHCA patients. After 90 days, 79 (4%) patients had good neurological outcomes and a median lower rSO2 level of 15% (95% confidence interval (CI): 15-20%). Receiver operating curve analysis indicated an optimal rSO2 cutoff point was about 40% for predicting good neurological outcome (area under curve = 0.91 [95% CI: 0.90 - 0.92], P &lt; 0.01). Compared to patients without return of spontaneous circulation (ROSC) upon arrival at the hospital, those with ROSC had significantly higher rSO2 levels (56% [95% CI: 39-65%] vs. 15% [95% CI: 15-17%], respectively; P &lt; 0.01). In patients without ROSC upon arrival at the hospital (n=1773), the percentage of patients with a good 90-day neurological outcome increased significantly in proportion to their rSO2 levels upon arrival at the hospital (P &lt; 0.01, Figure). In patients with E-CPR (n=121), the percentage of patients with a good 90-day neurological outcome increased significantly if their rSO2 levels upon arrival at the hospital was &gt;40% (5/16, 31% vs 6/105, 6%, P &lt; 0.01). Conclusions: rSO2 value monitoring in the emergency room was useful for speculating on brain damage severity for prognostication for E-CPR after OHCA.

Characteristics of regional cerebral oxygen saturation levels in patients with out-of-hospital cardiac arrest with or without return of spontaneous circulation: A prospective observational multicentre study

AimOur study aimed at filling the fundamental knowledge gap on the characteristics of regional brain oxygen saturation (rSO2) levels in out-of-hospital cardiac arrest (OHCA) patients with or without return of spontaneous circulation (ROSC) upon arrival at the hospital for estimating the quality of cardiopulmonary resuscitation and neurological prognostication in these patients. MethodsWe enrolled 1921 OHCA patients from the Japan – Prediction of Neurological Outcomes in Patients Post-cardiac Arrest Registry and measured their rSO2 immediately upon arrival at the hospital by near-infrared spectroscopy using two independent forehead probes (right and left). We also assessed the percentage of patients with a good neurological outcome (defined as cerebral performance categories 1 or 2) 90 days post cardiac arrest. ResultsAfter 90 days, 79 (4%) patients had good neurological outcomes and a median lower rSO2 level of 15% (15–20%). Compared to patients without ROSC upon arrival at the hospital, those with ROSC had significantly higher rSO2 levels (56% [39–65%] vs. 15% [15–17%], respectively; P<0.01), and significantly correlated right- and left-sided regional brain oxygen saturation levels (R=0.94 vs. 0.66, respectively). In both groups, the percentage of patients with a good 90-day neurological outcome increased significantly in proportion to their rSO2 levels upon arrival at the hospital (P<0.01). ConclusionOur data indicate that measuring rSO2 levels might be effective for both monitoring the quality of resuscitation and neurological prognostication in patients with OHCA.

Relationship between intraoperative regional cerebral oxygen saturation trends and cognitive decline after total knee replacement: a post-hoc analysis

BackgroundBilateral regional brain oxygen saturation (rSO2) trends, reflecting intraoperative brain oxygen imbalance, could warn of brain dysfunction. Various types of cognitive impairment, such as memory decline, alterations in executive function or subjective complaints, have been described three months after surgery. Our aim was to explore the potential utility of rSO2 values as a warning sign for the development of different types of decline in postoperative psychological function.MethodsObservational post-hoc analysis of data for the patient sample (n = 125) of a previously conducted clinical trial in patients over the age of 65 years undergoing total knee replacement under spinal anesthesia. Demographic, hemodynamic and bilateral rSO2 intraoperative values were recorded. An absolute rSO2 value of <50% or a reduction of >20% or >25% below baseline were chosen as relevant cutoffs. Composite function test scores were created from baseline to three months for each patient and adjusted for the mean (SD) score changes for a control group (n = 55). Tests were used to assess visual-motor coordination and executive function (VM-EF) (Wechsler Digit Symbol-Coding and Visual Reproduction, Trail Making Test) and memory (Auditory Verbal Learning, Wechsler Memory Scale); scales were used to assess psychological symptoms.ResultsWe observed no differences in baseline rSO2 values; rSO2 decreased significantly in all patients during surgery (P < 0.0001). Seventy-five patients (60%) had no sign of cognitive decline or psychological symptoms. Twenty-one patients (16.8%) had memory decline, 3 (2.4%) had VM-EF decline, and 33 (26.4%) had psychological symptoms. Left and right rSO2 values were asymmetric in patients who had memory decline (mean [SD] left-right ratio of 95.03 [8.51] vs 101.29 [6.7] for patients with no changes, P = 0.0012). The mean right-left difference in rSO2 was also significant in these patients (-2.87% [4.73%], lower on the right, P = 0.0034).ConclusionsDetection of a trend to asymmetry in rSO2 values can warn of possible postoperative onset of memory decline. Psychological symptoms and memory decline were common three months after knee replacement in our patients over the age of 65 years.

Cerebral Oximetry: The New Brain Monitor for Cardiac Arrest?

Can a noninvasive, real-time indicator of cerebral perfusion — regional brain oxygen saturation (rSO2) — predict neurological outcomes in patients

Noninvasive regional cerebral oxygen saturation for neurological prognostication of patients with out-of-hospital cardiac arrest: A prospective multicenter observational study

AimTo investigate the association between regional brain oxygen saturation (rSO2) at hospital arrival and neurological outcomes at 90 days in patients with out-of-hospital cardiac arrest (OHCA). MethodsThe Japan-Prediction of neurological Outcomes in patients post cardiac arrest (J-POP) registry is a prospective, multicenter, cohort study to test whether rSO2 predicts neurological outcomes after OHCA. We measured rSO2 in OHCA patients immediately after hospital arrival using a near-infrared spectrometer placed on the forehead with non-blinded fashion. The primary endpoint was “neurological outcomes” at 90 days after OHCA. ResultsEMS providers are not permitted to terminate CPR in the field in Japan, and so most patients with OHCA who are treated by EMS personnel are transported to emergency hospitals. Among 1017 OHCA patients, 672 patients including 52 comatose patients with pulses detectable (8%) and 620 cardiac arrest patients (92%) at hospital arrival were enrolled prospectively and consecutively. Twenty-nine patients with good neurological outcome had a significantly higher value of rSO2 at hospital arrival than 643 patients with poor neurological outcome (mean [±SD] 55.6±20.8% vs. 19.7±11.0%, p<0.001). Receiver operating curve analysis indicated an optimal rSO2 cutoff point of >42% for predicting good neurological outcome, with sensitivity 0.79 (95% confidence interval [CI], 0.60–0.92), specificity 0.95 (95% CI, 0.93–0.96), positive predictive value, 0.41 (95% CI, 0.28–0.55), negative predictive value, 0.99 (95% CI, 0.98–1.00), and area under the curve 0.90 (95% CI, 0.88–0.92). ConclusionThe rSO2 at hospital arrival can predict good neurological outcome at 90 days after OHCA.

BOLD MRI in the brain of fetal sheep at 3T during experimental hypoxia

To calculate regional fetal brain oxygen saturation (sO2) during hypoxia in sheep. Eight pregnant ewes were examined at a 3T MR-scanner using blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) to measure signal intensity changes of the fetal brain during a control period and a period of induced hypoxia. Regions of interest were placed in the fetal cerebrum to assess ΔR2* from GRE signal intensity plateaus (S(control), S(hypoxia)) and the relation between ΔR2* and ΔpO2 was analyzed. A probe was placed surgically in the fetal brain to directly measure local pO2 as a reference standard. Baseline and hypoxic pO2 values were recorded and compared (ΔpO2). Mean fetal brain pO2 decreased from 14.3 mmHg (95% confidence interval [CI]: 10-19) to 3.4 mmHg (95% CI: 2-5) during hypoxia (mean ΔpO2 = 10.9 mmHg and ΔR2* = -5s(-1)). A significant correlation between ΔR2* and ΔpO2 was noted (r = 0.93, P < 0.001), and conversion of pO2 into sO2 resulted in a linear regression coefficient of (-0.14 ± 0.01)s(-1)/% (r(2) = 0.91). Measured fetal brain BOLD-MRI was compared and converted to pO2, followed by calculation of cerebral sO2.

Sex-related differences of cerebral circumstances and clinical outcomes in patients with out-of-hospital cardiopulmonary arrest

Purpose: This study was conducted to examine the sex-related differences of cerebral circumstances and clinical outcomes in patients with out-of-hospital cardiopulmonary arrest (OHCA). Methods: The Japan-Prediction of neurological Outcomes in patients Post cardiac arrest (J-POP) registry is a prospective, multicenter, cohort study to test whether regional cerebral oxygen saturation (rSO2) predicts neurological outcomes after non-traumatic OHCA. We measured rSO2 in OHCA patients immediately after hospital arrival using a near-infrared spectrometer placed on the forehead. Results: Since Japanese emergency medical service providers are not permitted to terminate resuscitation in the field, most patients with OHCA are transported to emergency hospitals. During the 15 months of the study, 1327 consecutive patients were studied, 39% of whom were women. Women were significantly older than men (mean age, 74.7±16 vs. 69.1±16 years; p <0.0001), with lower percentages of witnessed arrests (44.2% vs. 56.3%, p<0.0001), and out-of hospital defibrillation (7.8% vs. 20.2%, p<0.0001). Women had lower regional brain oxygen saturation (rSO2) at hospital arrival, lower chance of return of spontaneous circulation at hospital arrival (ROSC) and good neurological outcomes at 30 days. Furthermore in patients without ROSC at hospital arrival, women had also lower rSO2 at hospital arrival and poor neurological outcomes at 30 days (See Figure). ![Figure][1] rSO2 at hospital arrival and prognosis Conclusions: Different from many of previous reports, women had significantly worse cerebral circumstances at hospital arrival and worse neurological prognosis after OHCA in this study. Additional studies are required to validate these observations for other potential genetic factors and potential discrepancies with other reports. [1]: pending:yes

Cerebral Oximetry and Cardiac Arrest

Cerebral oximetry is a Food and Drug Administration-approved technology that allows monitoring of brain oxygen saturation in accessible superficial brain cortex regions, which are amongst the most vulnerable in regard to ischemic or hypoxic injury. Since most oxygen in the area of interest is located in the venous compartment, the determined regional brain oxygen saturation approximately reflects the local balance between oxygen delivery and oxygen consumption. Major systemic alterations in blood oxygen content and oxygen delivery will be accompanied by corresponding changes in regional brain saturation. This systematic review, which is based on a Medline search, focuses on the characteristic changes in regional cerebral oxygen saturation that occur, when global oxygen supply to the brain ceases. It further highlights the potential application of cerebral oximetry in the management of cardiac arrest victims, the predictability of clinical outcome after global cerebral ischemia, and it also indicates possible potentials for the management of cerebral reperfusion after having instituted return of spontaneous circulation.

Monitoring brain oxygen saturation during awake off-pump coronary artery bypass

To evaluate the changes in cerebral blood flow during awake off-pump coronary artery bypass grafting and compare with the changes during off-pump coronary artery bypass grafting under general anesthesia, using continuous monitoring of regional cerebral oxygen saturation. The study population comprised 3 groups of patients who had undergone off-pump coronary artery bypass grafting with thoracic epidural anesthesia, general anesthesia, or a combination of the two. Regional brain oxygen saturation, determined with a near-infrared oxygen monitor, and mean arterial pressure during surgery were calculated and compared among the 3 groups. Patients who had undergone awake off-pump coronary artery bypass grafting with thoracic epidural anesthesia had a significantly higher cerebrovascular impairment ratio, and the EuroSCORE was high. No significant differences were observed among the 3 groups in terms of the relationship between mean arterial pressure during surgery and regional brain oxygen saturation. It is suggested that there were no differences in cerebral blood flow and mean arterial pressure changes among the 3 groups. Awake off-pump coronary artery bypass grafting is a safe surgical technique for patients with history of cerebral infarction or impaired cerebral blood flow. Awake off-pump coronary artery bypass grafting is a less invasive procedure that allows efficient management of intraoperative cerebral blood flow, and can be equally effective as a percutaneous coronary intervention.

Future uncertainties in the development of clinical cerebral oximetry

Since the first report in 1954 outlining the in vivo use of a double-beam spectrophotometer to measure the absorption of near-infrared light by various light absorbing pigments (or chromophores) involved in the mitochondrial respiratory chain (Chance, 1954), substantive advancements have been made in the use of near-infrared spectroscopy (NIRS) to monitor the oxidative state of various human tissues. Indeed, when Chance first reported the measurement of cytochrome c oxidase in yeast cells (Chance, 1954), he likely had little inclination that this would one day lead to the development of the modern day cerebral oximeter, an increasingly utilized monitor aimed at optimizing patient outcomes in a range of surgical settings. However, it was almost 25 years later that Jobsis published a series of investigations in animals (and in human volunteers) demonstrating that blood flow related changes in brain oxygenation could be monitored non-invasively. These studies established that NIRS could be used to monitor regional brain oxygen saturation (rSO2) in a potentially clinically useful manner (Jobsis, 1977). However, as is the case with many clinical developments, it took decades of further advancements before the first cerebral oximeter was approved by the United States Food and Drug Administration (Widman, 1997). Indeed, now more than 20 years since its first approval (and 60 years after the seminal work by Chance), we are arguably at a cross roads in the further development and understanding of how to use cerebral oximetry in clinical practice. Although substantial potential exists for NIRS-associated advancements in patient monitoring (and related improvements in outcome) in a wide variety of clinical situations, there are a number of uncertainties that could prevent these devices from reaching their full potential.

Regional venous oxygen saturation versus mixed venous saturation after paediatric cardiac surgery

Central venous oxygen saturation (ScvO2) remains the gold standard surrogate for tissue oxygen extraction in paediatric cardiac surgery. Near-infrared spectroscopy (NIRS) has been developed as a non-invasive diagnostic tool for regional oxygen saturation. The aim was to compare regional oxygen saturation measured by NIRS with ScvO2 in postoperative paediatric cardiac patients. In this prospective study, we included newborns and infants younger than 45 days undergoing heart surgery. We recorded continuous ScvO2 and NIRS regional saturation placed on the forehead (B) and right flank (S) for 48 h postoperatively. A Bland-Altman's analysis was used to assess the agreement between these measurements. A total of 23 patients were included with a median age of 12 days (2-46) and median weight of 3.1 kg (2.3-4.47). The mean difference (MD) ScvO2- B NIRS was 10.45% with limits of agreement (LOA) -17.23 to 38.13% and ScvO2- S NIRS MD 7.16% with LOA: -25.51 to 39.84%. The single ventricle ScvO2- S NIRS subgroup had MD within ± 5%; however, wide LOA was observed. The remaining subgroups showed MD nearly above ± 5%, with wide LOA. The regional oxygen saturation of brain and kidney did not match ScvO2 as estimation of global tissue perfusion. Nevertheless, NIRS may still provide information regarding regional circulation that may help in the management of neonatal cardiac surgery patients.