Regional cerebral oxygenation by NIRS does not correlate with central or jugular venous oxygen saturation during interventional catheterisation in children

Noninvasive tracking of mixed venous oxygen saturation via near-infrared spectroscopy cerebral oximetry: a retrospective observational study

Although previous studies have shown correlation between regional cerebral oxygen saturation (rScO2) and mixed venous oxygen saturation (SvO2), there is a lack of pragmatic information on the clinical applicability of these findings, such as tracking ability. We retrospectively analyzed continuous intraoperative recordings of rScO2 and SvO2 obtained from a pulmonary artery catheter and either of two near-infrared spectroscopy (NIRS) devices (INVOS 5100C, Medtronic; O3, Masimo) during off-pump cardiopulmonary bypass (OPCAB) surgery in adult patients. The ability of rScO2 to track SvO2 was quantitatively evaluated with 5 min interval changes transformed into relative values. The analysis included 176 h of data acquired from 48 subjects (26 and 22 subjects for INVOS and O3 dataset, respectively). The area under ROC of the left-rScO2 for detecting change of SvO2 ≥ 10% in INVOS and O3 datasets were 0.919 (95% CI 0.903-0.936) and 0.852 (95% CI 0.818-0.885). The concordance rates between the interval changes of left-rScO2 and SvO2 in INVOS and O3 datasets were 90.6% and 91.9% with 10% exclusion zone. rScO2 can serve as a noninvasive tool for detecting changes in SvO2 levels, a critical hemodynamic measurement.

Comparing near-infrared spectroscopy-measured cerebral oxygen saturation and corresponding venous oxygen saturations in children with congenital heart disease: a systematic review and meta-analysis

BACKGROUND

Near-infrared spectroscopy (NIRS) is a non-invasive approach that measures cerebral regional oxygen saturation (rScO₂). In this study, we evaluated the evidence on the validity of NIRS and the interchangeability between NIRS and common invasive approaches by exploring the correlation and consistency and comparing the mean and standard deviation between the NIRS rScO₂ and jugular bulb venous oxygen saturation (SjvO₂) as well as central venous oxygen saturation (ScvO₂) in the perioperative period of children with congenital heart disease (CHD).

METHODS

We searched electronic bibliographic databases (PubMed, The Cochrane Library and Embase) and screened the studies that met the inclusion criteria. We included cross-sectional studies of CHD pediatric patients in the perioperative period receiving both tests for NIRS rScO₂ and SjvO₂ or NIRS rScO₂ and ScvO₂. Methodological quality assessment and heterogeneity analyses were performed. We qualitatively summarized the results of Bland-Altman's analysis. Meta-regression, subgroup analyses, and sensitivity analyses were carried out to explore the causes of heterogeneity.

RESULTS

There was no significant difference in Cohen's d between rScO₂ and ScvO₂ or between rScO₂ and SjvO₂ (Cohen's d =0.06, 95% CI: -0.16 to 0.28; Cohen's d =0.03, 95% CI: -0.25 to 0.31, respectively) and notable heterogeneity existed (I²=76.0%, P<0.001; I²=73.6%, P<0.001, respectively). A positive linear correlation was present between rScO₂ and ScvO₂ or between rScO₂ and SjvO₂ (r=0.58, 95% CI: 0.54 to 0.63; r=0.60, 95% CI: 0.54 to 0.66, respectively) and the heterogeneity was not significant (I²=36.7%, P=0.065; I²=12.7%, P=0.328, respectively). In most studies, the 95% limits of agreements of Bland-Altman's analysis were large. No evidence of publication bias was observed.

CONCLUSIONS

The rScO₂ measured by NIRS reflected the SjvO₂ and ScvO₂ monitored by invasive measurements in the perioperative period of children with CHD to some extent. However, wide limits of agreements between rScO₂ and SjvO₂ as well as ScvO₂ indicated that NIRS and SjvO₂ as well as ScvO₂ are not interchangeable. Whether NIRS plays a prominent role in monitoring cerebral oxygen saturation in children with CHD needs further research.

Correlation of Near-Infrared Spectroscopy Oximetry and Corresponding Venous Oxygen Saturations in Children with Congenital Heart Disease

Invasive and non-invasive monitoring allow for early detection of hemodynamic compromise, facilitating timely intervention and avoidance of further decline. While venous oximetry is useful for assessing the adequacy of systemic oxygen delivery (DO₂), it is most often intermittent, invasive, and costly. Near-infrared spectroscopy (NIRS) oximetry allows for the non-invasive estimation of the adequacy of DO₂. We assessed the correlation between cerebral NIRS oximetry and superior vena cava (SVC) and jugular venous (JV) oxygen saturations and between renal NIRS oximetry and inferior vena cava (IVC) oxygen saturations. Systematic review of the literature was conducted to identify studies with data regarding near-infrared spectroscopy and venous saturation. The PubMed, EMBASE, Medline, and Cochrane databases were queried using the following terms in isolation and various combinations: "congenital heart disease," "near infrared spectroscopy," "venous saturation," and "pediatric." Pediatric studies in which simultaneous NIRS oximetry and corresponding venous oxygen saturations were simultaneously collected after cardiac surgery or catheterization were identified. Data were pooled from these studies to analyze the correlation between NIRS oximetry and the corresponding venous oxygen saturations. A total of 16 studies with 613 patients were included in the final analyses. Data were present to compare cerebral and renal NIRS oximetry with corresponding venous oxygen saturation. Cerebral NIRS and SVC and JV oxygen saturations and renal NIRS and IVC oxygen saturations demonstrated strong degrees of correlation (r-value 0.70 for each). However, cerebral NIRS and IVC oxygen saturation had a week degree of correlation (r-value of 0.38). Pooled analyses demonstrate that cerebral NIRS oximetry correlates strongly with SVC or JV oxygen saturation while renal NIRS oximetry correlates strongly with IVC oxygen saturations. A weak correlation was noted between cerebral NIRS oximetry and IVC oxygen saturations.

Clinical and Technical Limitations of Cerebral and Somatic Near-Infrared Spectroscopy as an Oxygenation Monitor

Cerebral and somatic near-infrared spectroscopy monitors are commonly used to detect tissue oxygenation in various circumstances. This form of monitoring is based on tissue infrared absorption and can be influenced by several physiological and non-physiological factors that can induce error in the interpretation. This narrative review explores those clinical and technical limitations and proposes solutions and alternatives in order to avoid some of those pitfalls.

Checklists to guide the supportive and critical care of tuberculous meningitis

The assessment and management of tuberculous meningitis (TBM) is often complex, yet no standardised approach exists, and evidence for the clinical care of patients, including those with critical illness, is limited. The roles of proformas and checklists are increasing in medicine; proformas provide a framework for a thorough approach to patient care, whereas checklists offer a priority-based approach that may be applied to deteriorating patients in time-critical situations. We aimed to develop a comprehensive assessment proforma and an accompanying 'priorities' checklist for patients with TBM, with the overriding goal being to improve patient outcomes. The proforma outlines what should be asked, checked, or tested at initial evaluation and daily inpatient review to assist supportive clinical care for patients, with an adapted list for patients in critical care. It is accompanied by a supporting document describing why these points are relevant to TBM. Our priorities checklist offers a useful and easy reminder of important issues to review during a time-critical period of acute patient deterioration. The benefit of these documents to patient outcomes would require investigation; however, we hope they will promote standardisation of patient assessment and care, particularly of critically unwell individuals, in whom morbidity and mortality remains unacceptably high.

Checklists to guide the supportive and critical care of tuberculous meningitis

The assessment and management of tuberculous meningitis (TBM) is often complex, yet no standardised approach exists, and evidence for the clinical care of patients, including those with critical illness, is limited. The roles of proformas and checklists are increasing in medicine; proformas provide a framework for a thorough approach to patient care, whereas checklists offer a priority-based approach that may be applied to deteriorating patients in time-critical situations. We aimed to develop a comprehensive assessment proforma and an accompanying 'priorities' checklist for patients with TBM, with the overriding goal being to improve patient outcomes. The proforma outlines what should be asked, checked, or tested at initial evaluation and daily inpatient review to assist supportive clinical care for patients, with an adapted list for patients in critical care. It is accompanied by a supporting document describing why these points are relevant to TBM. Our priorities checklist offers a useful and easy reminder of important issues to review during a time-critical period of acute patient deterioration. The benefit of these documents to patient outcomes would require investigation; however, we hope they will promote standardisation of patient assessment and care, particularly of critically unwell individuals, in whom morbidity and mortality remains unacceptably high.

Criteria for Critical Care Infants and Children: PICU Admission, Discharge, and Triage Practice Statement and Levels of Care Guidance

OBJECTIVES

To update the American Academy of Pediatrics and Society of Critical Care Medicine's 2004 Guidelines and levels of care for PICU.

DESIGN

A task force was appointed by the American College of Critical Care Medicine to follow a standardized and systematic review of the literature using an evidence-based approach. The 2004 Admission, Discharge and Triage Guidelines served as the starting point, and searches in Medline (Ovid), Embase (Ovid), and PubMed resulted in 329 articles published from 2004 to 2016. Only 21 pediatric studies evaluating outcomes related to pediatric level of care, specialized PICU, patient volume, or personnel. Of these, 13 studies were large retrospective registry data analyses, six small single-center studies, and two multicenter survey analyses. Limited high-quality evidence was found, and therefore, a modified Delphi process was used. Liaisons from the American Academy of Pediatrics were included in the panel representing critical care, surgical, and hospital medicine expertise for the development of this practice guidance. The title was amended to "practice statement" and "guidance" because Grading of Recommendations, Assessment, Development, and Evaluation methodology was not possible in this administrative work and to align with requirements put forth by the American Academy of Pediatrics.

METHODS

The panel consisted of two groups: a voting group and a writing group. The panel used an iterative collaborative approach to formulate statements on the basis of the literature review and common practice of the pediatric critical care bedside experts and administrators on the task force. Statements were then formulated and presented via an online anonymous voting tool to a voting group using a three-cycle interactive forecasting Delphi method. With each cycle of voting, statements were refined on the basis of votes received and on comments. Voting was conducted between the months of January 2017 and March 2017. The consensus was deemed achieved once 80% or higher scores from the voting group were recorded on any given statement or where there was consensus upon review of comments provided by voters. The Voting Panel was required to vote in all three forecasting events for the final evaluation of the data and inclusion in this work. The writing panel developed admission recommendations by level of care on the basis of voting results.

RESULTS

The panel voted on 30 statements, five of which were multicomponent statements addressing characteristics specific to PICU level of care including team structure, technology, education and training, academic pursuits, and indications for transfer to tertiary or quaternary PICU. Of the remaining 25 statements, 17 reached consensus cutoff score. Following a review of the Delphi results and consensus, the recommendations were written.

CONCLUSIONS

This practice statement and level of care guidance manuscript addresses important specifications for each PICU level of care, including the team structure and resources, technology and equipment, education and training, quality metrics, admission and discharge criteria, and indications for transfer to a higher level of care. The sparse high-quality evidence led the panel to use a modified Delphi process to seek expert opinion to develop consensus-based recommendations where gaps in the evidence exist. Despite this limitation, the members of the Task Force believe that these recommendations will provide guidance to practitioners in making informed decisions regarding pediatric admission or transfer to the appropriate level of care to achieve best outcomes.

Aspects on the Physiological and Biochemical Foundations of Neurocritical Care

Neurocritical care (NCC) is a branch of intensive care medicine characterized by specific physiological and biochemical monitoring techniques necessary for identifying cerebral adverse events and for evaluating specific therapies. Information is primarily obtained from physiological variables related to intracranial pressure (ICP) and cerebral blood flow (CBF) and from physiological and biochemical variables related to cerebral energy metabolism. Non-surgical therapies developed for treating increased ICP are based on knowledge regarding transport of water across the intact and injured blood-brain barrier (BBB) and the regulation of CBF. Brain volume is strictly controlled as the BBB permeability to crystalloids is very low restricting net transport of water across the capillary wall. Cerebral pressure autoregulation prevents changes in intracranial blood volume and intracapillary hydrostatic pressure at variations in arterial blood pressure. Information regarding cerebral oxidative metabolism is obtained from measurements of brain tissue oxygen tension (PbtO2) and biochemical data obtained from intracerebral microdialysis. As interstitial lactate/pyruvate (LP) ratio instantaneously reflects shifts in intracellular cytoplasmatic redox state, it is an important indicator of compromised cerebral oxidative metabolism. The combined information obtained from PbtO2, LP ratio, and the pattern of biochemical variables reveals whether impaired oxidative metabolism is due to insufficient perfusion (ischemia) or mitochondrial dysfunction. Intracerebral microdialysis and PbtO2 give information from a very small volume of tissue. Accordingly, clinical interpretation of the data must be based on information of the probe location in relation to focal brain damage. Attempts to evaluate global cerebral energy state from microdialysis of intraventricular fluid and from the LP ratio of the draining venous blood have recently been presented. To be of clinical relevance, the information from all monitoring techniques should be presented bedside online. Accordingly, in the future, the chemical variables obtained from microdialysis will probably be analyzed by biochemical sensors.

Brain monitoring in children

Applying scalp sensors in the operating theater, intensive care, or resuscitation scenarios to detect and monitor brain function is achievable, practical, and affordable. The modalities are complex and the output of the monitor needs careful interpretation. The monitor may have technical problems, and a single reading must be considered with caution. These monitors may have a use for monitoring trends in specific situations, but evidence does not support their widespread use. Nevertheless, research should continue to investigate their role. Future techniques and treatments may show that these monitors can monitor brain function and prevent harm.

Cerebral oxygenation during laparoscopic surgery: jugular bulb versus regional cerebral oxygen saturation

PURPOSE

We hypothesized that regional cerebral oxygen saturation (rSO2) could replace jugular bulb oxygen saturation (SjvO2) in the steep Trendelenburg position under pneumoperitoneum. Therefore, we evaluated the relationship between SjvO2 and rSO2 during laparoscopic surgery.

MATERIALS AND METHODS

After induction of anesthesia, mechanical ventilation was controlled to increase PaCO2 from 35 to 45 mm Hg in the supine position, and the changes in SjvO2 and rSO2 were measured. Then, after establishment of pneumoperitoneum and Trendelenburg position, ventilation was controlled to maintain a PaCO2 at 35 mm Hg and the CO2 step and measurements were repeated. The changes in SjvO2 (rSO2) -CO2 reactivity were compared in the supine position and Trendelenburg-pneumoperitoneum condition, respectively.

RESULTS

There was little correlation between SjvO2 and rSO2 in the supine position (concordance correlation coefficient=0.2819). Bland-Altman plots showed a mean bias of 8.4% with a limit of agreement of 21.6% and -4.7%. SjvO2 and rSO2 were not correlated during Trendelenburg-pneumoperitoneum condition (concordance correlation coefficient=0.3657). Bland-Altman plots showed a mean bias of 10.6% with a limit of agreement of 23.6% and -2.4%. The SjvO2-CO2 reactivity was higher than rSO2-CO2 reactivity in the supine position and Trendelenburg- pneumoperitoneum condition, respectively (0.9 ± 1.1 vs. 0.4 ± 1.2% mm Hg(-1), p=0.04; 1.7 ± 1.3 vs. 0.5 ± 1.1% mm Hg(-1), p<0.001).

CONCLUSION

There is little correlation between SjvO2 and rSO2 in the supine position and Trendelenburg-pneumoperitoneum condition during laparoscopic surgery.

Calibration of a prototype NIRS oximeter against two commercial devices on a blood-lipid phantom

In a blood-lipid liquid phantom the prototype near-infrared spectroscopy oximeter OxyPrem was calibrated against the INVOS® 5100c adult sensor in respect to values of regional tissue oxygen haemoglobin saturation (rStO2) for possible inclusion in the randomised clinical trial - SafeBoosC. In addition different commercial NIRS oximeters were compared on changing haemoglobin oxygen saturation and compared against co-oximetry. The best calibration was achieved with a simple offset and a linear scaling of the OxyPrem rStO2 values. The INVOS adult and pediatric sensor gave systematically different values, while the difference between the NIRO® 300 and the two INVOS sensors were magnitude dependent. The co-oximetry proved unreliable on such low haemoglobin and high Intralipid levels.

Monitoring of regional tissue oxygenation with near-infrared spectroscopy during the early postoperative course after superior cavopulmonary anastomosis

OBJECTIVES

Near-infrared spectroscopy (NIRS) offers continuous non-invasive monitoring of regional tissue oxygenation. We evaluated NIRS monitoring during the postoperative course after superior cavopulmonary anastomosis in patients with hypoplastic left heart syndrome and anatomically related malformations.

METHODS

Cerebral (cSO(2)) and somatic (sSO(2)) tissue oxygenations were recorded for 48 h and compared with routine measures of intensive care monitoring. Changes in parameters in the case of postoperative complications were evaluated.

RESULTS

Data were obtained from 32 patients. Median age at operation was 2.9 (1.5-10.0) months and weight was 5.3 ± 1.0 kg. Postoperative complications occurred in 7 patients (pulmonary artery thrombus n = 4, pneumothorax n = 1, cardiopulmonary resuscitation n = 1 and low-cardiac output n = 1). cSO(2) was 44 ± 14% at the end of the operation and reached its minimum of 40 ± 11% 2 h later (P = 0.018). Overall, cSO(2) was depressed early after surgery and increased from a mean of 42 ± 11% during the first 4 postoperative hours to 57 ± 8% in the last 4 h of the study period (P < 0.001). The sSO(2) decreased from 77 ± 11% during the early postoperative course to 68 ± 9% within the later course (P < 0.001). The cSO(2) correlated with the arterial partial pressure of oxygen (pO(2), r = 0.364, P < 0.001), with the arterial oxygen saturation (SaO(2), r = 0.547, P < 0.001) and with the central venous oxygen saturation providing the strongest correlation (SvO(2), r = 0.686, P < 0.001). Analysis of agreement between cSO(2) and SvO(2) measurements revealed a mean bias of 0.97 with limits of agreement between 19.8 and -17.9%. Inclusion of both cSO(2) and sSO(2) into a linear regression model slightly improved the prediction of SvO(2) from NIRS values (r = 0.706, P < 0.001). The mean values of cSO(2), sSO(2), SaO(2) and SvO(2) during the early postoperative period were lower in patients with complications (cSO(2): 45 ± 9 vs 29 ± 5%, P < 0.001; sSO(2): 80 ± 11 vs 70 ± 6%, P = 0.004; SaO(2): 76 ± 8 vs 66 ± 6%, P = 0.004; SvO(2): 48 ± 14 vs 32 ± 6%, P < 0.001).

CONCLUSIONS

NIRS technology allows inferring the global oxygenation from continuous non-invasive measurements of regional tissue oxygenation. The cSO(2) is lowered in the early postoperative course. Lower cSO(2) values in the early postoperative course may be predictive of postoperative complications.

Non-invasive estimation of jugular venous oxygen saturation: a comparison between near infrared spectroscopy and transcutaneous venous oximetry

The ability of practitioners to assess the adequacy of global oxygen delivery is dependent on an accurate measurement of central venous saturation. Traditional techniques require the placement of invasive central venous access devices. This study aimed to compare two non-invasive technologies for the estimation of regional venous saturation (reflectance plethysmography and near infrared spectroscopy [NIRS]), using venous blood gas analysis as gold standard. Forty patients undergoing cardiac surgery were recruited in two groups. In the first group a reflectance pulse oximeter probe was placed on the skin overlying the internal jugular vein. In the second group, a Somanetics INVOS oximeter patch was placed on the skin overlying the internal jugular vein and overlying the ipsilateral cerebral hemisphere. Central venous catheters were placed in all patients. Oxygen saturation estimates from both groups were compared with measured saturation from venous blood. Twenty patients participated in each group.Data were analyzed by the limits of agreement technique suggested by Bland and Altman and by linear regression analysis. In the reflectance plethysmography group, the mean bias was 4.27% and the limits of agreement were 58.3 to -49.8% (r(2) = 0.00, p = 0.98). In the NIRS group the mean biases were 10.8% and 2.0% for the sensors attached over the cerebral hemisphere and over the internal jugular vein, respectively, and the limits of agreement were 33.1 to -11.4 and 19.5 to -15.5% (r(2) = 0.22, 0.28;p = 0.04, 0.03) for the cerebral hemisphere and internal jugular sites, respectively. While transcutaneous regional oximetry and NIRS have both been used to estimate venous and tissue oxygen saturation non-invasively, the correlation between estimates of ScvO(2) and SxvO(2) were statistically significant for near infrared spectroscopy, but not for transcutaneous regional oximetry. Placement of cerebral oximetry patches directly over the internal jugular vein (as opposed to on the forehead) appeared to approximate internal jugular venous saturation better (lower mean bias and tighter limits of agreement), which suggests this modality may with refinement offer the practitioner additional clinically useful information regarding global cerebral oxygen supply and demand matching.

Resuscitation and extracorporeal life support during cardiopulmonary resuscitation following the Norwood (Stage 1) operation

The success of extracorporeal support in providing cardiopulmonary support for a variety of patients has led to use of Extracorporeal Life Support, also known as ECLS, as a rescue for patients failing conventional resuscitation. The use of Extracorporeal Life Support in circumstances of cardiac arrest has come to be termed "Extracorporeal Life Support during Cardiopulmonary Resuscitation" or "ECPR". Although Extracorporeal Life Support during Cardiopulmonary Resuscitation was originally described in patients following repair of congenital cardiac defects who suffered a sudden arrest, it has now been used in a variety of circumstances for patients both with and without primary cardiac disease. Multiple centres have reported successful use of Extracorporeal Life Support during Cardiopulmonary Resuscitation in adults and children. However, because of the cost, the complexity of the technique, and the resources required, Extracorporeal Life Support during Cardiopulmonary Resuscitation is not offered in all centres for paediatric patients with refractory cardiac arrest. The increasing success and availability of Extracorporeal Life Support during Cardiopulmonary Resuscitation in post-operative cardiac patients, coupled with the fact that patients undergoing the Norwood (Stage 1) operation can have rapid, unpredictable cardiac deterioration and arrest, has led to a steady increase in the use of Extracorporeal Life Support during Cardiopulmonary Resuscitation in this population. For Extracorporeal Life Support during Cardiopulmonary Resuscitation to be most successful, it must be deployed rapidly while the patient is undergoing excellent cardiopulmonary resuscitation. Early activation of the team that will perform cannulation could possibly shorten the duration of cardiopulmonary resuscitation and might improve survival and outcome. More research needs to be done to refine the populations and circumstances that offer the best outcome with Extracorporeal Life Support during Cardiopulmonary Resuscitation, to evaluate the ratios of cost to benefit, and establish the long-term neurodevelopmental outcomes in survivors.

Cerebral Oxygenation Monitoring: A Strategy to Detect IVH and PVL

Premature infants are at risk for intraventricular hemorrhage (IVH) and periventricular leukomalacia (PVL) theorized to be a result from fluctuations in cerebral blood flow. Monitoring cerebral oxygenation offers a method to observe changes in cerebral blood flow that may be beneficial for detecting and preventing IVH and PVL. This article explains the potential for cerebral oxygenation monitoring in detecting IVH and PVL using cerebral oximetry, reviews current knowledge known about cerebral oxygenation, and describes current challenges for cerebral oxygenation to be the next neuroprotective vital sign.

Effect of olprinone, a phosphodiesterase III inhibitor, on balance of cerebral oxygen supply and demand during cardiopulmonary bypass

Neuropsychological dysfunction with cardiopulmonary bypass (CPB) may be facilitated by inadequate cerebral oxygen balance during CPB. Olprinone, a phosphodiesterase III inhibitor, augments cerebral blood flow by a direct vasodilator effect on cerebral arteries. We conducted the present randomized study in patients undergoing cardiac surgery with CPB to investigate whether olprinone improved the balance of cerebral oxygen supply and demand during the rewarming period of CPB. After anesthesia, a 5.5 F fiberoptic oximeter catheter was inserted into the right jugular bulb retrogradely for monitoring the jugular venous oxyhemoglobin saturation (SjO2), and a probe of transcranial near-infrared spectroscopy was placed over the forehead for monitoring the bilateral regional cerebral oxygen saturation (rSO2). Patients were randomly assigned to 3 groups, and olprinone was administered at 0, 0.2, or 0.4 μg·kg(-1)·min(-1) after establishment of hypothermic CPB. Olprinone significantly prevented the reduction of the SjO2 at 5 and 10 minutes after the start of rewarming, although it did not alter rSO2. Furthermore, there was a minor reduction of the bilateral rSO2 at low doses of olprinone (0.2 μg·kg(-1)·min(-1)). We conclude that olprinone prevents the decrease of the SjO2 at the rewarming period and improves the balance of cerebral oxygen supply and demand during the rewarming period of CPB. In addition, a future extended study may be required to elucidate the effect of low dose of olprinone.

Cerebral NIRS as a marker of superior vena cava oxygen saturation in neonates with congenital heart disease

OBJECTIVES

To investigate the correlation between cerebral near-infrared spectroscopy (NIRS) (rSO2c) and superior vena cava venous oxygen saturation (ScvO2) in newborn patients with congenital heart disease (CHD).

BACKGROUND

NIRS is a noninvasive method to monitor hemoglobin oxygen saturation using nonpulsatile oximetry.

METHODS

We retrospectively analyzed perioperative data from 100 newborn patients who underwent cardiac surgery for CHD. rSO2c, ScvO2 from 24 h before to 72 h after surgery were recorded.

RESULTS

rSO2c had a fair correlation with ScvO2 (r 0.37; P <0.001). The relationship between rSO2c and ScvO2 did not change when analyzed between patients with cyanotic or acyanotic CHD. During the preoperative period, rSO2c levels overestimated ScvO2; in the first 18 postoperative hours, rSO2c underestimated ScvO2; after that period, they showed very close trends. Hypocapnia caused rSO2c to underestimate ScvO2; in normocapnic patients, rSO2c-ScvO2 average differences were close to zero; in hypercapnic neonates, rSO2c tended to overestimate ScvO2. The best performance of rSO2c as a surrogate of ScvO2 was found in the venous saturation ranges from 40% to 60% (r 0.3, P: 0.03).

CONCLUSIONS

rSO2c in newborn patients with cyanotic and acyanotic CHD provides a continuous noninvasive information with a fair correlation with ScvO2%: some predictable variables (i.e., time from surgery, carbon dioxide, and venous saturation levels), should guide the operators to adjust rSO2c values in terms of ScvO2. Serial measures of ScvO2 seem recommended to tailor rSO2c information on actual venous saturation percentage.

Methods of monitoring brain oxygenation

INTRODUCTION

Posttraumatic brain ischemia or hypoxia is a major potential cause of secondary injury that may lead to poor outcome. Avoidance, or amelioration, of this secondary injury depends on early diagnosis and intervention before permanent injury occurs. However, tools to monitor brain oxygenation continuously in the neuro-intensive care unit have been lacking.

DISCUSSION

In recent times, methods of monitoring aspects of brain oxygenation continuously by the bedside have been evaluated in several experimental and clinical series and are potentially changing the way we manage head-injured patients. These monitors have the potential to alert the clinician to possible secondary injury and enable intervention, help interpret pathophysiological changes (e.g., hyperemia causing raised intracranial pressure), monitor interventions (e.g., hyperventilation for increased intracranial pressure), and prognosticate. This review focuses on jugular venous saturation, brain tissue oxygen tension, and near-infrared spectroscopy as practical methods that may have an important role in managing patients with brain injury, with a particular focus on the available evidence in children. However, to use these monitors effectively and to understand the studies in which these monitors are employed, it is important for the clinician to appreciate the technical characteristics of each monitor, as well as respective strengths and limitations of each. It is equally important that the clinician understands relevant aspects of brain oxygen physiology and head trauma pathophysiology to enable correct interpretation of the monitored data and therefore to direct an appropriate therapeutic response that is likely to benefit, not harm, the patient.

Advances in near-infrared spectroscopy to study the brain of the preterm and term neonate

This article reviews tissue oximetry and imaging to study the preterm and newborn infant brain by near-infrared spectroscopy. These two technologies are now advanced; nearly 100 reports on their use in newborn infants have been published, and commercial instruments are available. The precision of oximetry, however, is a limitation for its clinical use of assessing cerebral oxygenation. Imaging of brain function needs very well defined protocols for sensory stimulation as well as signal analysis to provide meaningful results.