Near-infrared spectroscopy: exposing the dark (venous) side of the circulation

Association of Immediate Postoperative Hemodynamic and Laboratory Values in Predicting Norwood Admission Outcomes

The primary objective of this study was to determine whether or not hemodynamic parameters and laboratory values at the time of admission to the pediatric cardiac intensive care unit after the Norwood operation were associated with a composite outcome of either need for extracorporeal membrane oxygenation or inpatient mortality. This was a single-center retrospective study of infants with functionally univentricular hearts admitted to intensive care after the Norwood procedure from January 2011 to January 2020. Data were obtained at a single point (after a Norwood procedure) and then compared between two subsets of patients based on the presence or not of the composite outcome of interest. In univariate and multiple regression analyses, a series of receiver operator curves were generated to assess the relationship between the variables of interest and the composite outcome. Eight (7.6%) experienced the composite outcome out of a total of 104 patients. Those who experienced the composite endpoint had significantly higher oxygen extraction ratio (0.43 vs. 0.31, p = 0.01), lower systemic blood flow (2.5 L/min versus 3.1 L/min, p = 0.01), and higher systemic vascular resistance (20.2 indexed woods units versus 14.8 indexed woods units, p = 0.01). Those with systemic blood flow of less than 2.5 L/min/m2 had a 17% risk of experiencing the composite endpoint AUC = 0.79. Those with systemic vascular resistance of greater than 19 indexed woods units had a 22% risk of experiencing the composite endpoint AUC 0.80. Systemic blood flow and systemic vascular resistance are independently associated with this composite outcome.

Factors associated with renal oxygen extraction in mechanically ventilated children after the Norwood operation: insights from high fidelity haemodynamic data

BACKGROUND

Maintaining the adequacy of systemic oxygen delivery is of utmost importance, particularly in critically ill children. Renal oxygen extraction can be utilised as metric of the balance between systemic oxygen delivery and oxygen consumption. The primary aim of this study was to determine what clinical factors are associated with renal oxygen extraction in children after Norwood procedure.

METHODS

Mechanically ventilated children who underwent Norwood procedure from 1 September, 2022 to 1 March, 2023 were identified as these patients had data collected and stored with high fidelity by the T3 software. Data regarding haemodynamic values, fluid balance, and airway pressure were collected and analysed using Bayesian regression to determine the association of the individual metrics with renal oxygen extraction.

RESULTS

A total of 27,270 datapoints were included in the final analyses. The resulting top two models explained had nearly 80% probability of being true and explained over 90% of the variance in renal oxygen extraction. The coefficients for each variable retained in the best were -1.70 for milrinone, -19.05 for epinephrine, 0.129 for mean airway pressure, -0.063 for mean arterial pressure, 0.111 for central venous pressure, 0.093 for arterial saturation, 0.006 for heart rate, -0.025 for respiratory rate, 0.366 for systemic vascular resistance, and -0.032 for systemic blood flow.

CONCLUSION

Increased milrinone, epinephrine, mean arterial pressure, and systemic blood flow were associated with decreased (improved) renal oxygen extraction, while increased mean airway pressure, central venous pressure, arterial saturation, and systemic vascular resistance were associated with increased (worsened) renal oxygen extraction.

Renal tissue oxygenation and development of AKI in preterm neonates born < 32 weeks' gestational age in the first week of age

OBJECTIVE

To evaluate the relationship between regional renal saturation of oxygen (RrSO2) changes and serum creatinine (SCr) during the first eight days of age for preterm neonates born < 32 weeks' gestational age.

DESIGN

Post-hoc analysis of multicenter prospectively measured neonatal RrSO2 values collected during the first 8 days of age in neonates born at < 32 weeks' gestation. Acute kidney injury (AKI) was defined by the neonatal modified Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Variables were compared between groups of neonates with and with AKI.

RESULTS

One hundred nine neonates were included and 561 SCr values were obtained. Eight participants developed AKI by SCr criteria. A 10-percentage point increase in mean %RrSO2 was associated with a 40% decrease in risk of AKI (95%CI: 9.6-61%; p = 0.016).

CONCLUSIONS

Increases in mean %RrSO2 in neonates born at < 32 weeks' GA were associated with a decreased risk of AKI. These findings support the design of further prospective trials utilizing RrSO2 monitoring to evaluate new therapies or clinical protocols to prevent and treat neonatal AKI.

Nurses' perceptions and use of near infrared spectroscopy in paediatric cardiac intensive care

BACKGROUND

Near-infrared spectroscopy (NIRS) is a non-invasive technology that estimates regional oxygen saturation. Literature demonstrates that NIRS can provide valuable data for clinical staff. However, little research has addressed the nursing care and management of NIRS in the critical care environment.

AIMS

To assess nurses' perception around the use of NIRS and current NIRS practice within paediatric cardiac intensive care unit (PCICUs).

STUDY DESIGN

A 53-item cross-sectional electronic survey was developed to assess indications for NIRS, critical value thresholds and interventions, barriers to use, policies and procedures, and nursing perceptions. Descriptive statistics were used to summarize and aggregate data.

RESULTS

Among the 28 responding sites (63.6% response rate), usage of NIRS was variable and patient-dependent. Most nurses reported using NIRS in patients with unstable physiology such as post-operative single ventricle (n = 25, 89.3%) and concern for shock (n = 21, 75.0%). Critically low cerebral values varied among respondents from less than 40 (n = 3, 10.7%) to less than 60 (n = 4, 14.3%), with lower critical values permitted for single ventricle physiology: less than 40 (n = 8, 28.6%) to less than 50 (n = 6, 21.4%). Reported barriers to using NIRS included skin breakdown (n = 9, 32.1%), lack of consistency in decision-making among physicians (n = 13, 46.4%), and not using NIRS data when developing a plan of care (n = 11, 39.3%). Most (n = 24, 85.7%) nurses reported that NIRS provided valuable information and was perceived to be beneficial for patients.

CONCLUSIONS

NIRS monitoring is a common technology in the care of complex congenital heart disease patients. Most nurses valued this technology, but inconsistencies and practicalities around its use in guiding patient management were found to be problematic.

RELEVANCE TO CLINICAL PRACTICE

NIRS is commonly used in the PCICU and although nurses perceived NIRS to be useful for their practice, the variability in the interpretation of values and inconsistent protocols and decision-making by physicians was challenging.

Effect of retropneumoperitoneum on cerebral and renal oxygen saturation during retroperitoneal robotic-assisted laparoscopic pyeloplasty (R-RALP) in a pediatric population: Preliminary results of a prospective observational study using a dedicated anesthetic protocol and Near-InfraRed Spectroscopy

BACKGROUND

Retroperitoneal robotic-assisted laparoscopic pyeloplasty (R-RALP) for ureteropelvic junction obstruction (UPJO) has gained growing acceptance among pediatric urologists, and is increasingly performed as day-case surgery, involving smaller children and infants. However, retroperitoneal CO2 insufflation may cause hemodynamic derangements, respiratory changes, and hypercapnia, whose consequences are poorly investigated. We, therefore, decided to prospectively study its effect on regional tissue perfusion and oxygenation in a cohort of pediatric patients undergoing R-RALP, using a dedicated anesthetic protocol and cerebral and renal Near InfraRed Spectroscopy (NIRS).

MATERIAL AND METHODS

Between January 2021 and September 2022, a cohort of 21 consecutive children [12 males (9 females), mean age of 7.1 ± 3.8 years and mean body weight of 25.7 ± 12.3 kg] underwent their first elective pyeloplasty for UPJO by R-RALP. The surgical procedure followed a previously described standardized technique and a dedicated anesthetic protocol. In conjunction with the minimal expected standard monitoring, cerebral and renal NIRS were added. Standard monitoring parameters and NIRS values were recorded at preset points throughout the procedures.

RESULTS

Standard monitoring and NIRS measurements during R-RALP were not adversely affected by CO2 insufflation, pending a significant increase in respiratory rate, aimed to avoid hypercapnia, while keeping the ventilation pressure within the safety range, preventing lung injury.

CONCLUSIONS

R-RALP, using a constant retroperitoneal CO2 insufflation pressure of 12 mmHg with a 5 L.min-1 flow, does not adversely affect respiratory and hemodynamics parameters, pending the implementation of a specifically designed anesthetic protocol aimed to prevent hypercapnia, the most threatening effect of retroperitoneal CO2 insufflation.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03274050.

Propofol and thiopental for intravenous induction in neonates: Study protocol for a dose-finding trial

BACKGROUND

Propofol and thiopental are commonly used induction agents in neonatal anesthesia. Even though both hypnotics have been used off-label for many years, pharmacological knowledge regarding these agents is scarce in neonates. The significant variability in neonates' body composition, organ function, and maturation makes pharmacological studies highly relevant albeit challenging. As a result, there is currently limited data about the anesthetic induction dose of thiopental and propofol in neonates. In addition, a knowledge gap exists concerning the pharmacodynamics of induction doses.

OBJECTIVE

To determine the median effective anesthetic induction dose of propofol and thiopental in neonatal patients of different gestational and postnatal ages and evaluate the pharmacodynamics of the anesthesia induction doses on the neonatal systemic and cerebral hemodynamics.

METHODS

This is a single-center, prospective, open-label, interventional, dose-finding study, including neonatal patients from birth up to 28 postnatal days undergoing general anesthesia for surgical or diagnostic procedures. The patients will be stratified according to their gestational and postnatal age and allocated to one of the two trial arms: anesthesia induction with propofol or anesthesia induction with thiopental. We will use Dixon's up-and-down method to estimate the median effective anesthesia induction dose of both agents in neonates of different gestational and postnatal ages. In addition, we will study the relationship between anesthesia induction doses and changes in systemic and cerebral hemodynamics.

DISCUSSION

Alterations in the systemic and cerebral regional hemodynamics secondary to anesthesia induction may be harmful in neonates, especially premature and critically ill newborns, due to their immature organ systems, reduced physiological reserves, and impaired cerebral autoregulation. Perfusion homeostasis is considered one of the significant and modifiable determinants of anesthesia-related neurocognitive outcomes. Therefore, dose-finding and safety pharmacological studies of the anesthetic induction agents in neonates are urgently needed and acknowledged as a high priority by the European Medicine Agency. Estimating adequate induction doses to ensure optimal depth of anesthesia while avoiding systemic and cerebral hemodynamic disturbances will help ensure safe anesthesia and potentially improve anesthesia-related outcomes in this group of patients.

TRIAL REGISTRATION

EudraCT (EudraCT Identifier: 2019-001534-34), 05.07.2022.

Evaluation of renal oxygenation by near-infrared spectroscopy during endoscopic injection of bulking agents in children with vesicoureteral reflux

BACKGROUND

Near infrared spectroscopy (NIRS) is the measuring of regional tissue oxygenation (rSO2) by interpreting oxyhemoglobin and deoxyhemoglobin signals that come back by transmitting near infrared light to tissues. The effect of endourological interventions on renal perfusion in children is largely unknown.

AIMS

To evaluate the effects of endoscopic injection of bulking agents (EIBA) for vesicoureteral reflux (VUR) on renal oxygenation (RO) using renal NIRS monitoring, which shows renal perfusion and oxygenation changes.

STUDY DESIGN

Case-control study.

METHODS

Group I had bilateral inguinal surgery, Group II cystoscopy, and Group III, EIBA for VUR with 30 patients in each group. During the operation, vital signs, peripheral oxygen saturation, end-tidal carbon dioxide, and renal regional oxygen saturation index (rSO2) values by bilateral renal NIRS monitoring were recorded. NIRS values before induction (T0) to postoperative (Tend) were determined. A 20% or more reduction in renal rSO2 (%20↓rSO2) was considered significant. Group III was also evaluated as subgroup III-A (not having "%20↓rSO2") and subgroup III-B ("%20↓rSO2").

RESULTS

The rSO2 decrease was observed in the first 5 min for both sides in group III. The most significant drop was at T30 for the right kidney and a significant decrease in rSO2, 20% or more, was observed in 6 renal units of 4 patients having higher SFU grading and renal scar in group III.

CONCLUSION

EIBA may transitionally impair renal oxygenation. Higher SFU grading and renal scar may increase the risk of renal hypoxia during EIBA.

Use of combined cerebral and somatic renal near infrared spectroscopy during noncardiac surgery in children: a proposed algorithm

Cerebral near infrared spectroscopy (NIRS) monitoring has been extensively applied in neonatology and in cardiac surgery, becoming a standard in many pediatric cardiac centers. However, compensatory physiological mechanisms favor cerebral perfusion to the detriment of peripheral tissue oxygenation. Therefore, simultaneous measurement of cerebral and somatic oxygen saturation has been advocated to ease the differential diagnosis between central and peripheral sources of hypoperfusion, which may go undetected by standard monitoring and not mirrored by cerebral NIRS alone. A clinical algorithm already exists in cardiac surgery, aimed to correct intraoperative cerebral oxygen desaturations. A similar algorithm still lacks in noncardiac pediatric surgery. The goal of this paper is to propose a clinical algorithm for the combined use of cerebral and somatic NIRS monitoring during anesthesia in the pediatric population undergoing noncardiac surgery. A panel of experienced pediatric anesthetists developed the algorithm that is based on the clinical experience and intraoperative observations. It aims to lessen the current variability in interpreting NIRS measurement. Multisite NIRS monitoring was achieved applying one pediatric sensor to the forehead for cerebral tissue perfusion reading and a second one to the decumbent lumbar region for recording somatic renal tissue perfusion. The algorithm describes a sequence of acts aimed to identify the putative cause of intraoperative organ tissue desaturation and suggests clinical interventions expected to restore adequate tissue perfusion. It is composed of two arms: the main arm includes patients with an observed decrease in cerebral perfusion (CrO2), the second one includes those with a stable CrSO2 with declining RrSO2. Described also are five clinical cases of infants and neonates in whom pathological alterations of organ perfusion were detected using intraoperative multisite NIRS monitoring, portrayed in the accompanying figures (Annex).

Monitoring renal oxygenation status by near-infrared spectroscopy during ureterorenoscopy in children

BACKGROUND

: Near-infrared spectroscopy (NIRS) monitoring demonstrates renal blood flow, perfusion, and oxygenation changes. This study aimed to evaluate the effects of pediatric endourological interventions (PEI) on regional oxygen saturation value (rSO2) usingrenal NIRS monitoring.

METHODS

Patients having bilateral inguinal surgery (group I), cystoscopy (group II), and ureterorenoscopy (group III), 20 patients in each group, were included in the study. NIRS values before induction (T0) and at 5 min (T5), 10 min (T10), 15 min (T15), 20 min (T20), 25 min (T25), 30 min (T30) of the surgical procedure, and at the postextubation (Tend) were determined. The amount of irrigation fluid was recorded in groups II and III. The ureterorenoscopy group was also evaluated as two subgroups, as group III-R with patients having a "20%↓rSO2" and as group III-NoR, not having a "20%↓rSO2".

RESULTS

The mean total volume of irrigation was higher in group III, but the difference was not significant between the subgroups III-R and III-NoR. Renal rSO2 decreased significantly in T25, T30, and T-end values in group III. "20%↓rSO2" was seen in 1 patient in group II and 7 patients in group III. In the subgroups III-R, all patients had an obstructive pathology and significant preoperative hydronephrosis with a mean renal pelvis AP diameter of 21.1 ± 16.4 mm.

DISCUSSION

Although rSO2 significantly improves postoperatively, our data may suggest that congenital and acquired obstructive pathologies with hydronephrosis, prolonged operative time with continuous irrigation, and instrument movement in a narrow lumen may increase intrarenal pressure and the risk of renal hypoxia in endourological interventions. Preoperative evaluation of kidney functions and a meticulously well-planned intervention can prevent possible complications.

Near-infrared spectroscopy in the medical management of infants

Near-infrared spectroscopy (NIRS) is a technology that is easy to use and can provide helpful information about organ oxygenation and perfusion by measuring regional tissue oxygen saturation (rSO2) with near-infrared light. The sensors can be placed in different anatomical locations to monitor rSO2 levels in several organs. While NIRS is not without limitations, this equipment is now becoming increasingly integrated into modern healthcare practice with the goal of achieving better outcomes for patients. It can be particularly applicable in the monitoring of pediatric patients because of their size, and especially so in infant patients. Infants are ideal for NIRS monitoring as nearly all of their vital organs lie near the skin surface which near-infrared light penetrates through. In addition, infants are a difficult population to evaluate with traditional invasive monitoring techniques that normally rely on the use of larger catheters and maintaining vascular access. Pediatric clinicians can observe rSO2 values in order to gain insight about tissue perfusion, oxygenation, and the metabolic status of their patients. In this way, NIRS can be used in a non-invasive manner to either continuously or periodically check rSO2. Because of these attributes and capabilities, NIRS can be used in various pediatric inpatient settings and on a variety of patients who require monitoring. The primary objective of this review is to provide pediatric clinicians with a general understanding of how NIRS works, to discuss how it currently is being studied and employed, and how NIRS could be increasingly used in the near future, all with a focus on infant management.

The Effect of Aminophylline on Urine Output and Fluid Balance after a Single Dose in Children Admitted to the Pediatric Cardiac Intensive Care Unit

The purpose of this retrospective study was to investigate the effects of a single dose of aminophylline on urine output and fluid balance in children admitted to the cardiac intensive care unit. A retrospective study was performed to compare variables of interest before and 24 hours after aminophylline administration in children under the age of 18 years who were admitted to the cardiac intensive care unit at our institution from January 2011 onwards. Variables of interest included age, weight, aminophylline dose, concurrently administered diuretics, specific hemodynamic parameters, and blood urea nitrogen and creatinine levels. Variables such as urine output and fluid balance were measured through a binary endpoint. Data were compared in a paired fashion and continuous variables were compared through paired t-tests. Analyses were conducted using SPSS Version 23.0. A total of 14 patients were included in the study. There was no significant change in hemodynamic parameters or creatinine levels before and after intravenous aminophylline administration of 5 mg/kg. There was a significant difference in urine output, fluid balance, and blood urea nitrogen levels from the baseline value. Concurrent usage of diuretics did not show significant association with a difference in urine output or fluid balance from baseline. No significant adverse reactions were noted 24 hours after administration of aminophylline. Use of aminophylline dosed at 5 mg/kg is safe and leads to improvement in urine output and fluid balance without negatively impacting systemic oxygen delivery or renal filtration function.

Recent advancements in pediatric cardiopulmonary bypass technology for better outcomes of pediatric cardiac surgery

Background

Pediatric cardiac surgery is in itself very enigmatic and individualized. Presently, there has been a slew of new developments aimed primarily toward pediatric cardiopulmonary bypass for safer, patient-centered pediatric cardiac surgery. Still, lot of technological challenges need to be resolved, and their safer application in pediatric and neonate patients requires further refinement.

Main body of the abstract

Considering various significant yet unresolved issues of pediatric cardiac bypass, an exhaustive literature search was done on various internet databases with standard keywords. There are various new recent improvements; as the first oxygenator explicitly designed for neonatal patients; pediatric oxygenators with low prime volumes and surface areas that allow flows up to 2 L/min; pediatric oxygenators with integrated arterial filters; and miniature ultrafiltration devices that allow for high rates of ultrafiltrate removal. These advancements can significantly reduce cardiopulmonary bypass circuit surface areas and prime volumes. These advancements could reduce or eliminate the requirement for homologous red blood cells during or after surgery with reduction or eliminate bypass-related hemodilution, and inflammation. Because of the immaturity of the neonatal hemostatic system, conventional coagulation tests alone are insufficient to guide neonatal hemostatic therapy. Myocardial preservation techniques, safe temperature with duration are still debatable and yet to be fully explored.

Short conclusion

This review is based on Standards for Quality Improvement Reporting Excellence guidelines to provide a framework for reporting new knowledge to find better management strategy for pediatric cardiac cases.

The Influence of Age on Cerebral Tissue Oxygenation in Vasovagal Syncope and Orthostatic Hypotension

Age-related physiological impairment increases susceptibility to syncope. We tested the hypotheses that cerebral oxygenation during orthostatic provocation, as well as the level at which syncope occurs, differs according to age. Non-invasive hemodynamic monitoring and cerebral oximetry were applied during a head-up tilt test in 139 patients with vasovagal syncope (mean (SD) 45, (17) years, 60%-female); 121 patients with orthostatic hypotension (61.4 (19.2) years, 49.6%-female); and 82 patients with a negative head-up tilt test (45 (18) years, 61%-female). Group differences in cerebral tissue oxygenation levels and systolic blood pressure were assessed in supine at 3 and 10 min of orthostatic provocation, 30 s before (i.e., presyncopal phase) and during syncope in age groups of <30, 30−60, and >60 years. During the head-up tilt test, cerebral tissue oxygenation at the presyncopal phase decreased with age, both in patients with vasovagal syncope (<30 years: 66.9 ± 6.2, 30−60: 64.5 ± 6.1, >60: 62.2 ± 5.8%; p = 0.009) and orthostatic hypotension (<30: 67.4 ± 4.4, 30−60: 61.6 ± 6.2, >60: 57.5 ± 3.9; p < 0.001). Mean systolic blood pressure at the presyncopal phase did not differ according to age. Cerebral oxygenation prior to syncope in older individuals with vasovagal syncope and orthostatic hypotension is lower compared with younger individuals independently of systolic blood pressure. This suggests that the level of cerebral oxygenation at which syncope is elected is lower in older individuals.

[Monitoring of gastrointestinal dysfunction by near-infrared spectroscopy in children with sepsis: a prospective study]

OBJECTIVES

To investigate the incidence and mortality of gastrointestinal dysfunction in children with sepsis, the application of near-infrared spectroscopy (NIRS) in monitoring mesenteric regional tissue oxygen saturation (rSO2), and the association between rSO2 and gastrointestinal dysfunction.

METHODS

In this prospective study, 79 children with sepsis in the pediatric intensive care unit (sepsis group) and 40 children who underwent physical examination in the Department of Child Healthcare (healthy control group) from January to December, 2021 were enrolled as subjects. The related medical data were collected, including general information on admission and at discharge, treatment during hospitalization, and laboratory examination results. NIRS was used to measure mesenteric rSO2. Clinical characteristics were compared between the patients with and without gastrointestinal dysfunction.

RESULTS

For the 79 children with sepsis, the incidence rate of gastrointestinal dysfunction was 49% (39/79), and the mortality rate of the children with gastrointestinal dysfunction was 26% (10/39). The children with gastrointestinal dysfunction had a longer duration of mechanical ventilation and a higher 28-day mortality rate (P<0.05). The children with gastrointestinal dysfunction had a significantly lower median rSO2 (64%) than the children without gastrointestinal dysfunction (72%) and the healthy control group (78%) (P<0.05).

CONCLUSIONS

There are high incidence and mortality rates of gastrointestinal dysfunction in children with sepsis, and the reduction in rSO2 may be associated with the development of gastrointestinal dysfunction.

Renal Oxygen Saturation as an Early Indicator of Shock in Children

Background

Shock is a life-threatening syndrome in which tissue perfusion and oxygen delivery are inadequate. Near-infrared spectroscopy (NIRS) has been suggested as a noninvasive tool for monitoring and detecting the state of inadequate tissue perfusion. Renal and mesenteric oximetry show decreased cardiac output earlier than systemic or global parameters of tissue oxygenation or cerebral oximetry. However, until now there has been no study on the validity of regional renal oxygen saturation (rRSO₂) by NIRS for diagnosing shock in children.

Purpose

To analyze the validity of rRSO₂ by NIRS to diagnose shock in children.

Patients and Methods

This cross-sectional study was conducted in critically ill children (aged 1 month–18 years) who were admitted to the pediatric intensive care unit (PICU), from September to November 2020, consecutively. Patients were classified into two groups: shock and non-shock. The diagnosis of shock is based on clinical criteria (tachycardia, sign of hypoperfusion and decrease systolic blood pressure <P5 according to age). Measurement of rRSO₂ by NIRS was performed by the doctor in charge when the patient came to PICU. The baseline rRSO₂ value (%) made a receiver operating characteristic (ROC) curve and was used to find the optimal cut-off value and calculated sensitivity and specificity.

Results

We enrolled 20 critically ill patients. The baseline rRSO₂ in the shock (n=10) and non-shock (n=10) groups were, 44.00±4.95 vs 78.70±4.52 (p 0.003). The optimal cutoff value of the baseline rRSO₂ to predict shock is less than 58.5% with area under the curve (AUC) value is 94.4% (95% CI of 84.4–100%), p 0.001, sensitivity 90% and specificity 90% in critically ill children.

Conclusion

The rRSO₂ value by NIRS can differentiate between shock and non-shock in critically ill patients accurately.

Effects of Arterial Carbon Dioxide Tension on Cerebral and Somatic Regional Tissue Oxygenation and Blood Flow in Neonates After the Norwood Procedure With Deep Hypothermic Cardiopulmonary Bypass

Neonates undergoing the Norwood procedure for hypoplastic left heart syndrome are at higher risk of impaired systemic oxygen delivery with resultant brain, kidney, and intestinal ischemic injury, shock, and death. Complex developmental, anatomic, and treatment-related influences on cerebral and renal-somatic circulations make individualized treatment strategies physiologically attractive. Monitoring cerebral and renal circulations with near infrared spectroscopy can help drive rational therapeutic interventions. The primary aim of this study was to describe the differential effects of carbon dioxide tension on cerebral and renal circulations in neonates after the Norwood procedure. Using a prospectively-maintained database of postoperative physiologic and hemodynamic parameters, we analyzed the relationship between postoperative arterial carbon dioxide tension and tissue oxygen saturation and arteriovenous saturation difference in cerebral and renal regions, applying univariate and multivariate multilevel mixed regression techniques. Results were available from 7,644 h of data in 178 patients. Increases in arterial carbon dioxide tension were associated with increased cerebral and decreased renal oxygen saturation. Differential changes in arteriovenous saturation difference explained these effects. The cerebral circulation showed more carbon dioxide sensitivity in the early postoperative period, while sensitivity in the renal circulation increased over time. Multivariate models supported the univariate findings and defined complex time-dependent interactions presented graphically. The cerebral and renal circulations may compete for blood flow with critical limitations of cardiac output. The cerebral and renal-somatic beds have different circulatory control mechanisms that can be manipulated to change the distribution of cardiac output by altering the arterial carbon dioxide tension. Monitoring cerebral and renal circulations with near infrared spectroscopy can provide rational physiologic targets for individualized treatment.

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.

Renal Oxygenation (rSO2) Population Parameter Estimates in Premature Infants Routinely Monitored With Near-Infrared Spectroscopy

BACKGROUND

Currently, reference ranges for renal oxygenation measured by near-infrared spectroscopy (NIRS) in preterm infants beyond the first days of life are lacking, especially those born prior to 29 weeks' gestation. Population estimates of renal oxygenation (rSO2) levels among preterm infants over time have yet to be established, leading to reluctance in clinical application.

PURPOSE

To characterize the distribution and estimate population parameters for renal oxygenation measured by NIRS during the first 14 days of life among preterm infants.

METHODS

We prospectively observed rSO2 trends of 37 infants before 34 weeks' gestation and 1800-g or less birth weight for the first 14 days of life. Analyses included distribution fit tests, ordinary least squares (OLS) regression, and t tests.

RESULTS

Average daily rSO2 variation steadily increased with 42% difference through the first 14 days of life. For all infants, renal rSO2 means peaked during the first 3 days of life and plateaued around 7 days. Daily rSO2 slopes were significantly lower among males and infants 29 weeks' or less gestation.

IMPLICATIONS FOR PRACTICE

Renal rSO2 during the first 14 days of life reflects normal extrauterine transition reaching stabilization around 7 days of life. Gestational age, birth weight, and gender may predict the early trajectory of rSO2 patterns. Population estimates provide parameters for renal rSO2 that may indicate early-onset tissue hypoxia when acute or significant drops from baseline occur.

IMPLICATIONS FOR RESEARCH

We present a framework to guide future research using renal NIRS technology in preterm infants to determine deviations from expected trends that may precede renal injury.

Fluid management, electrolytes imbalance and renal management in neonates with neonatal encephalopathy treated with hypothermia

Kidney dysfunction and acute kidney injury (AKI) frequently accompanies neonatal encephalopathy and contributes to neonatal morbidity and mortality. While there are currently no proven therapies for the treatment of AKI, understanding the pathophysiology along with early recognition and treatment of alterations in fluid, electrolyte and metabolic homeostasis that accompany AKI offer opportunity to reduce associated morbidity. Promising new tests and technologies, including urine and serum biomarkers and renal near-infrared spectroscopy offer opportunities to improve diagnosis and monitoring of neonates at risk for kidney injury. Furthermore, recent advances in neonatal kidney supportive therapies such as hemofiltration and hemodialysis may further improve outcomes in this population. This chapter provides an overview of disorders of fluid balance, electrolyte homeostasis and kidney function associated with neonatal encephalopathy and therapeutic hypothermia. Recommendations for fluid and electrolyte management based upon published literature and authors' opinions are provided.

Cerebral Oxygenation by Near-Infrared Spectroscopy in Infants Undergoing Thoracoscopic Lung Resection

Background: Thoracoscopic resection is the standard of care for congenital lung malformations (CLMs) in infants. However, there is rising concern that capnothorax may affect cerebral perfusion and oxygenation, carrying potential long-term effects on neurodevelopmental behavior. The aim of our study was to investigate, using near-infrared spectroscopy (NIRS), the regional cerebral oxygenation (CrSO₂) in infants undergoing thoracoscopic lung resection; the secondary aim was to assess the relationship between rSO₂ and standard monitoring. Methods: In this retrospective study, we reviewed all infants (<1 year old, ASA II) who underwent thoracoscopic CLM resection in double-lung ventilation under fixed capnothorax parameters (5 mmHg of pressure, 1 L/minute flow), standardized anesthetic protocol, standard monitoring, and multisite NIRS in our center. We focused our attention on 8 anesthetic and surgical maneuvers, potentially affecting tissue oxygen saturation. Results: Ten infants met the inclusion criteria. At surgery, median age was 5.5 (4-7) months, median weight 7.2 (6.6-8) kg, median operative time 110 (55-180) minutes, and median capnothorax duration 79 (34-168) minutes. No conversion to open surgery occurred. CrSO₂ values remained within clinically accepted values during thoracoscopy, beside a CrSO₂ drop >20% of basal value in 1 patient, during capnothorax induction. Renal NIRS added very little to standard monitoring, which appeared generally inadequate to consistently appraise end-organ perfusion. ETCO₂ best correlated with CrSO₂ variations, suggesting to be able to realistically predict them. Conclusions: The thoracoscopic treatment of CLMs under the given conditions appears well tolerated in infants, pending the continuous adjustment of ventilator settings by an experienced anesthetist, confident with NIRS technology.

Hydroyxurea improves cerebral oxygen saturation in children with sickle cell anemia

Neurologic complications are common in patients with sickle cell anemia (SCA), but conventional tools such as MRI and transcranial Doppler ultrasonography (TCD) do not fully assess cerebrovascular pathology. Cerebral tissue oximetry measures mixed oxygen saturation in the frontal lobes (S_CT O₂ ) and provides early prognostic information about tissue at risk of ischemic injury. Untreated patients with SCA have significantly lower S_CT O₂ than healthy controls that declines with age. Hydroxyurea is effective in preventing many SCA-related complications, but the degree to which it preserves normal neurophysiology is unclear. We analyzed participants enrolled in the Therapeutic Response Evaluation and Adherence Trial (TREAT, NCT02286154), which enrolled participants initiating hydroxyurea using individualized dosing (new cohort) and those previously taking hydroxyurea (old cohort) and was designed to monitor the long-term benefits of hydroxyurea. Cerebral oximetry was performed at baseline and annually. For the new cohort (median starting age = 12 months, n = 55), mean baseline S_CT O₂ was normal before starting hydroxyurea (mean 65%, 95% CI 58-72%) and significantly increased after 2 years (mean 72%, 95% CI 65-79%, p < .001). The S_CT O₂ for patients receiving long-term hydroxyurea (median age = 9.6 years) was normal at study entry (mean 66%, 95% CI 58-74%) and remained stable across 2 years. Both cohorts had significantly higher S_CT O₂ than published data from predominantly untreated SCA patients. Cerebral oximetry is a non-invasive method to assess cerebrovascular pathology that complements conventional imaging. Our results indicate that hydroxyurea suggests protection against neurophysiologic changes seen in untreated SCA.

Oxygen saturation (SpO2) targeting for newborn infants at delivery: Are we reaching for an impossible unknown?

For more than 200 years, pure oxygen was given ad libitum to newborn infants requiring resuscitation. Due to oxidative stress and injury concerns, a paradigm shift towards using "less" oxygen, including air (21% oxygen) instead of pure (100%) oxygen, occurred about twenty years ago. A decade later, clinicians were advised to adjust fractional inspired oxygen (FiO₂) to target oxygen saturations (SpO₂) that were derived from spontaneously breathing, healthy, mature infants. Whether these recommendations are achievable, beneficial, harmful or redundant is uncertain. The underlying pathology leading to resuscitation varies between infants and may considerably alter an infant's response to supplemental oxygen. In this review, we summarize available evidence for the use of SpO₂ monitoring at delivery for newborn infants, elucidate existing knowledge and service gaps, and suggest future research recommendations that will lead to the safest clinical strategies for this standard and important practice.

The Use of Near-Infrared Spectroscopy and/or Transcranial Doppler as Non-Invasive Markers of Cerebral Perfusion in Adult Sepsis Patients With Delirium: A Systematic Review

Background:

Several studies have previously reported the presence of altered cerebral perfusion during sepsis. However, the role of non-invasive neuromonitoring, and the impact of altered cerebral perfusion, in sepsis patients with delirium remains unclear.

Methods:

We performed a systematic review of studies that used near-infrared spectroscopy (NIRS) and/or transcranial Doppler (TCD) to assess adults (≥18 years) with sepsis and delirium. From study inception to July 28, 2020, we searched the following databases: Ovid MedLine, Embase, Cochrane Library, and Web of Science.

Results:

Of 1546 articles identified, 10 met our inclusion criteria. Although NIRS-derived regional cerebral oxygenation was consistently lower, this difference was only statistically significant in one study. TCD-derived cerebral blood flow velocity was inconsistent across studies. Importantly, both impaired cerebral autoregulation during sepsis and increased cerebrovascular resistance were associated with delirium during sepsis. However, the heterogeneity in NIRS and TCD devices, duration of recording (from 10 seconds to 72 hours), and delirium assessment methods (e.g., electronic medical records, confusion assessment method for the intensive care unit), precluded meta-analysis.

Conclusion:

The available literature demonstrates that cerebral perfusion disturbances may be associated with delirium in sepsis. However, future investigations will require consistent definitions of delirium, delirium assessment training, harmonized NIRS and TCD assessments (e.g., consistent measurement site and length of recording), as well as the quantification of secondary and tertiary variables (i.e., Cox, Mxa, MAP_OPT), in order to fully assess the relationship between cerebral perfusion and delirium in patients with sepsis.

Association between the variability of cerebral oxygen saturation during cardiopulmonary bypass and delayed postoperative neurocognitive recovery in cardiac valve surgical patients: A pilot study

AIMS OF THE STUDY

The association between regional cerebral oxygen saturation (rSO2) and postoperative cognitive decline is controversial. In this study, we investigated the association between the real variability of regional cerebral oxygen saturation during cardiopulmonary bypass (CPB) and postoperative delayed neurocognitive recovery in patients undergoing heart valve surgery.

METHODS USED TO CONDUCT THE STUDY

A total of 71 patients who underwent cardiac valve surgery were enrolled in this study. Patients were assessed for cognitive function using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment Scale (MOCA) on the day before surgery and the 7th day after surgery. The real variability of regional cerebral oxygen saturation (rSO2), real variability of the brain bispectral index of EEG (BIS), real variability of mean arterial pressure (MAP) and body temperature were monitored during CPB. Patients were divided into two groups according to neural cognitive function scores to explore the relationship between postoperative delayed neurocognitive recovery and the real variability of cerebral oxygen saturation, BIS, MAP, and body temperature during CPB.

RESULTS OF THE STUDY

Twenty-seven patients were diagnosed with postoperative delayed neurocognitive recovery. The occurrence of postoperative delayed neurocognitive recovery after surgery was closely related to the large variability of rSO2 during the rewarming phase of CPB (P < .05). Logistic analysis showed that preoperative arrhythmia, a lower level of serum albumin after surgery and greater rSO2 variability during the rewarming phase were risk factors for postoperative delayed neurocognitive recovery (P < .05). In this study, there was no correlation between postoperative delayed neurocognitive recovery and BIS, MAP or body temperature variability (P > .05).

CONCLUSIONS DRAWN FROM THE STUDY AND CLINICAL IMPLICATIONS

The real variability of rSO2 during the CPB rewarming phase was related to postoperative delayed neurocognitive recovery in patients who underwent cardiac surgery.

Impaired cerebral oxygenation in heart failure patients at rest and during head-up tilt testing

Aims

Heart failure (HF) confers potentially negative effects on the brain and autonomic nervous system. The measurement cerebral tissue oxygen saturation (SctO₂) may aid in understanding such effects. We aimed to investigate if compensated HF affects SctO₂ at rest and during orthostatic challenge.

Methods and results

Non‐invasive haemodynamic monitoring and near‐infrared spectroscopy were applied during head‐up tilt (HUT) in 61 HF patients [mean (SD) 71 (11) years, 82% male, New York Heart Association (NYHA) class I–III] and 60 controls [60 (12) years, 42% male). Group differences in continuous variables were compared using Student's t‐test. Associations between HF and SctO₂ were studied using multivariable linear regression models adjusted for age, sex, diabetes, smoking, systolic blood pressure (SBP), and heart rate in supine position and after 10 min of HUT.

Mean SctO₂ was lower in HF patients compared with controls both in the supine position (67 vs. 71%; P < 0.001) and after 10 min of HUT (64 vs. 69%; P < 0.001). The HUT‐induced SctO₂ decrease was greater in HF patients compared with controls (P = 0.026). SBP did not change in neither HF patients nor controls during HUT, whereas diastolic blood pressure and heart rate increased in both groups. HF was associated with lower SctO₂ in supine (B = −2.5%, P = 0.023) and after 10 min of HUT (B = −2.6%, P = 0.007) after multivariable adjustments.

Conclusions

Cerebral tissue oxygenation is lower in HF patients both at rest and during orthostasis compared with subjects without HF. Future studies should test if the lower cerebral oxygenation associates with negative prognosis and with impaired cognitive function.

Monitoring of cerebral oximetry in patients with postural orthostatic tachycardia syndrome

AIMS 

Postural orthostatic tachycardia syndrome (POTS) is a disorder of unknown aetiology characterized by orthostatic intolerance and tachycardia with diverse other symptoms, including neurocognitive deficits. Cerebral oximetry non-invasively measures cerebral tissue saturation (SctO2) and has been shown to be informative in syncope evaluation. We aimed to assess SctO2 in POTS patients and those with normal response to orthostatic provocation, relative to haemodynamic parameters and symptoms.

METHODS AND RESULTS 

Thirty-four patients with POTS (29.1 ± 9.5 years; 26 females) and 34 age-/sex-matched controls with normal head-up tilt tests (HUTs) were included. SctO2 at rest and during HUT were compared between POTS and controls. The relation between SctO2, systolic blood pressure (SBP), and heart rate (HR) during HUT was linearly assessed. SctO2 values were related to dizziness or syncope during HUT. The minimum SctO2-value during HUT was lower (65.4 ± 5.6 vs. 68.2 ± 4.2%, P = 0.023) and changes in SctO2 from supine to minimum HUT value were more pronounced in POTS patients (-5.7 ± 2.9% vs. -4.3 ± 2.1%, P = 0.028). Decrease in SBP from supine to minimum HUT value (P = 0.004) and increase in HR from supine to HUT value at 3 min (P = 0.022) correlated with more pronounced SctO2 decrease in POTS but not controls. SctO2 did not predict syncope or dizziness during HUT.

CONCLUSION 

Postural orthostatic tachycardia syndrome patients have lower cerebral tissue saturation during orthostatic provocation compared with those subjects having normal haemodynamic response to tilt. Orthostatic decrease in cerebral saturation only weakly correlates with HR increase and does not predict vasovagal reflex in POTS. Other hitherto unknown factors may affect cerebral tissue saturation in POTS.

Excess cerebral oxygen delivery follows return of spontaneous circulation in near-term asphyxiated lambs

Hypoxic-ischaemia renders the neonatal brain susceptible to early secondary injury from oxidative stress and impaired autoregulation. We aimed to describe cerebral oxygen kinetics and haemodynamics immediately following return of spontaneous circulation (ROSC) and evaluate non-invasive parameters to facilitate bedside monitoring. Near-term sheep fetuses [139 ± 2 (SD) days gestation, n = 16] were instrumented to measure carotid artery (CA) flow, pressure, right brachial arterial and jugular venous saturation (SaO2 and SvO2, respectively). Cerebral oxygenation (crSO2) was measured using near-infrared spectroscopy (NIRS). Following induction of severe asphyxia, lambs received cardiopulmonary resuscitation using 100% oxygen until ROSC, with oxygen subsequently weaned according to saturation nomograms as per current guidelines. We found that oxygen consumption did not rise following ROSC, but oxygen delivery was markedly elevated until 15 min after ROSC. CrSO2 and heart rate each correlated with oxygen delivery. SaO2 remained > 90% and was less useful for identifying trends in oxygen delivery. CrSO2 correlated inversely with cerebral fractional oxygen extraction. In conclusion, ROSC from perinatal asphyxia is characterised by excess oxygen delivery that is driven by rapid increases in cerebrovascular pressure, flow, and oxygen saturation, and may be monitored non-invasively. Further work to describe and limit injury mediated by oxygen toxicity following ROSC is warranted.

Near-Infrared Spectroscopy to Assess Cerebral Autoregulation and Optimal Mean Arterial Pressure in Patients With Hypoxic-Ischemic Brain Injury: A Prospective Multicenter Feasibility Study

Supplemental Digital Content is available in the text.

We provide preliminary multicenter data to suggest that recruitment and collection of physiologic data necessary to quantify cerebral autoregulation and individualized blood pressure targets are feasible in postcardiac arrest patients. We evaluated the feasibility of a multicenter protocol to enroll patients across centers, as well as collect continuous recording (≥ 80% of monitoring time) of regional cerebral oxygenation and mean arterial pressure, which is required to quantify cerebral autoregulation, using the cerebral oximetry index, and individualized optimal mean arterial pressure thresholds. Additionally, we conducted an exploratory analysis to assess if an increased percentage of monitoring time where mean arterial pressure was greater than or equal to 5 mm Hg below optimal mean arterial pressure, percentage of monitoring time with dysfunctional cerebral autoregulation (i.e., cerebral oximetry index ≥ 0.3), and time to return of spontaneous circulation were associated with an unfavorable neurologic outcome (i.e., 6-mo Cerebral Performance Category score ≥ 3).

Influence of altitude on cerebral and splanchnic oxygen saturation in critically ill children during air ambulance transport

Objective

The aim of the current study was to investigate how cerebral and splanchnic oxygen saturation (rSO₂-C and rSO₂-A) in critically ill children transported in air ambulance was affected by flight with cabin pressurization corresponding to ≥ 5000 feet. A second aim was to investigate any differences between cyanotic and non-cyanotic children in relation to cerebral and splanchnic oxygen saturation during flight ≥ 5000 feet. The variability of the cerebral and splanchnic Near Infrared Spectroscopy (NIRS) sensors was evaluated.

Design

NIRS was used to measure rSO₂-C and rSO₂-A during transport of critically ill children in air ambulance. rSO₂ data was collected and stored by the NIRS monitor and extracted and analyzed off-line after the transport. Prior to evaluation of the NIRS signals all zero and floor-effect values were removed.

Setting

The Pediatric Intensive Care Unit (PICU) at Astrid Lindgren Children’s Hospital, Karolinska University Hospital in Stockholm, Sweden.

Patients

In total, 44 critically ill children scheduled for inter-hospital transport by a specialized pediatric transport team were included in the study between January 2014 and January 2019 (convenience sampling).

Intervention

No interventions were conducted.

Measurements

All study patients were monitored with a cerebral NIRS-sensor placed over the forehead and an abdominal NIRS-sensor placed in the infra-umbilical area for cerebral and splanchnic regional oxygen saturation monitoring, rSO₂-C and rSO₂-A, respectively.

Main results

Complete rSO₂-C and rSO₂-A data was obtained in 39 patients. Median age was 12 days. Cyanotic congenital heart malformations were present in 9 patients (23%). In 22 patients (56%) rSO₂-C decreased at altitude ≥ 5000 feet and in 24 patients (61%) rSO₂-A decreased at altitude ≥ 5000 feet compared to baseline (p<0.0001). In 25 patients (64%) the rSO₂-C/rSO₂-A ratio was greater at altitude ≥ 5000 feet than at baseline. A ratio ≥ 1 was seen in 77% of patients at altitude ≥ 5000 feet compared to in 67% of patients at baseline.

Conclusion

Both cerebral and splanchnic oxygen saturation decreased at altitude ≥ 5000 feet compared to baseline. In most patients, both cyanotic and non-cyanotic, cerebral oxygen saturation was preserved more than splanchnic oxygen saturation.

The central nervous system and heart failure

The view that chronic heart failure was exclusively a disease of the heart dominated the cardiovascular literature until relatively recently. However, over the last 40 years it has increasingly come to be seen as a multisystem disease. Aside from changes in the sympathetic and parasympathetic nervous systems and the renin-angiotensin-aldosterone system, adaptations to the lungs, muscles and gastrointestinal tract have been clearly documented. It is clear that the brain and CNS are also affected in patients with heart failure, although this is often under recognized. The purpose of this review is to summarize the changes in the structure and biochemical function of the CNS in patients with chronic heart failure and to discuss their potential importance.

[Near-infrared spectroscopy : Technique, development, current use and perspectives]

Near-infrared spectroscopy (NIRS) has been available in research and clinical practice for more than four decades. Recently, there have been numerous publications and substantial developments in the field. This article describes the clinical application of NIRS in relation to current guidelines, with a focus on pediatric and cardiac anesthesia. It discusses technical and physiological principles, pitfalls in clinical use and presents (patho)physiological influencing factors and derived variables, such as fractional oxygen extraction (FOE) and the cerebral oxygen index (COx). Recommendations for the interpretation of NIRS values in connection with influencing factors, such as oxygen transport capacity, gas exchange and circulation as well as an algorithm for cardiac anesthesia are presented. Limitations of the method and the lack of comparability of values from different devices as well as generally accepted standard values are explained. Technical differences and advantages compared to pulse oxymetry and transcranial Doppler sonography are illuminated. Finally, the prognostic significance and requirements for future clinical studies are discussed.

Evaluation of renal oxygenization in laparoscopic pediatric surgery by near infrared spectroscopy

PURPOSE

Increased intraabdominal pressure IAP may reduce renal blood flow (RBF). The study aims to evaluate the pneumoperitoneum effect on RBF by comparing renal regional oxygen saturation index (rSrO2) measured by near-infrared spectroscopy (NIRS) in pediatric patients having laparotomy and laparoscopy.

METHODS

Of 58 patients having laparoscopy and laparotomy, 18 were excluded due to renal pathologies, combined open surgical procedures, and administration of inotropic drugs. Hemodynamic parameters and rSrO2 were recorded in laparoscopy (n = 20) and laparotomy (n = 20) groups before induction and with 5 min intervals up to 60 min and at post-extubation.

RESULTS

Decrease in right renal rSrO2 at 45th and 60th min and 30th, 45th and 60th min in left were significant in the laparoscopy group compared to laparotomy group. In the laparoscopy group, reductions at T25, T30, T45, and T60 were significant in both renal rSrO2. Renal rSO2 increased to normal with desufflation.

CONCLUSION

IAP with pneumoperitoneum may lead to renal hypoxia in children. Renal rSO2 returns to normal with desufflation. Renal NIRS monitorization might be needed in patients with renal parenchymal and vascular pathologies, solitary kidney, and multiorgan pathologies that may affect renal oxygenation.

Changes in peripheral muscle oxygenation measured with near-infrared spectroscopy in preterm neonates within the first 24 h after birth

BACKGROUND

Near-infrared spectroscopy (NIRS) combined with venous occlusions enables peripheral-muscle oxygenation and perfusion monitoring.

OBJECTIVE

The aim of the present exploratory observational study was to evaluate peripheral-muscle oxygenation and perfusion during the first 24 h after birth in stable preterm neonates.

APPROACH

Secondary outcome parameters of prospective observational studies were analysed. Preterm neonates with peripheral-muscle NIRS measurements combined with venous occlusion on the first day after birth were included. Neonates without circulatory support and without signs of infection/inflammation were included. Neonates were stratified in four groups according to their measurement time-point (6 h-periods) and matched 2:1 for gestational age ±1 week. For each group haemoglobin flow (Hbflow), oxygen-delivery (DO2), oxygen-consumption (VO2), fractional-oxygen-extraction (FOE), tissue-oxygenation-index (TOI) and mixed-venous-oxygenation (SvO2) were calculated. Neonates with measurements during the first 6-hour time period were compared to neonates with measurements of the following time periods.

MAIN RESULTS

40 preterm neonates (gestational age (median(IQR)): 33.5(32.5-34.1)weeks) measured during the first 6 h period after birth were compared to 20 preterm neonates measured in each of the following 6 h periods (period two: 33.7(33.1-34.3)weeks; period three: 34.1(33.2-34.6)weeks; period four: 33.8(32.6-34.6)weeks). Hbflow, DO2 and SvO2 were significantly higher in the second and third 6 h time period compared to the first 6 h period. VO2 did not change significantly during the first day after birth. FOE was significantly lower in the second, third and fourth time period compared to the first 6 h period. TOI showed a non-significant trend towards higher values in the third period compared to the first 6 h period.

SIGNIFICANCE

In preterm neonates Hbflow, DO2, SvO2 increased, FOE decreased and TOI showed a trend towards increase during the first day after birth, whereas VO2 did not change. Changes of peripheral-muscle oxygenation during the first day after birth in stable preterm neonates are different to already published changes thereafter.

Effect of End-Tidal Carbon Dioxide on Cerebral Dynamics in Infants With Ventricular Septal Defect: A Comparison Between Sevoflurane and Intravenous Anesthetics

OBJECTIVES

The primary aim was to compare the changes in regional cerebral oxygen saturation (rSO₂) and cerebral blood flow velocity (CBFV) during sevoflurane and intravenous anesthesia when the end-tidal carbon dioxide partial pressure (P_ETCO₂) changed in infants undergoing ventricular septal defect (VSD) repair.

DESIGN

Prospective, observational study.

SETTING

Tertiary care hospital.

PARTICIPANTS

Patients younger than 6 months with VSDs.

INTERVENTIONS

End-tidal carbon dioxide was increased by decreasing tidal volume or respiratory rate.

MEASUREMENTS AND MAIN RESULTS

The infants were randomly assigned to receive either sevoflurane (SA group) or midazolam-sufentanil based intravenous anesthesia (IA group). P_ETCO₂ levels of 30 mmHg (T1), 35 mmHg (T2), 40 mmHg (T3), or 45 mmHg (T4) were obtained by adjusting the tidal volume and respiratory rate. There were no significant intergroup differences in rSO_2. In the SA group, as P_ETCO₂ increased from T1 to T4, rSO₂ increased significantly from 68.8% ± 5.9% to 76.4% ± 6.0% (p < 0.001). CBFV increased linearly, whereas the pulsatility index and resistance index decreased linearly from T1 to T4 (p < 0.001). In the IA group, rSO₂ showed a significant increase from 68.6% ± 4.6% to 76.1% ± 6.2% with the change in P_ETCO₂ from T1 to T4 (p < 0.001). CBFV increased linearly, whereas the pulsatility index and resistance index decreased linearly from T1 to T4 (p < 0.001).

CONCLUSION

Cerebrovascular response to different P_ETCO₂ levels was preserved and similar during clinically relevant doses of sevoflurane anesthesia and midazolam-sufentanil based intravenous anesthesia in infants younger than 6 months old undergoing VSD repair.

Effects of relative low minute ventilation on cerebral haemodynamics in infants undergoing ventricular septal defect repair

BACKGROUND

Ventilation-associated changes in blood carbon dioxide levels are associated with various physiological changes in infants undergoing surgery. Studies on the effects of mechanical ventilation on cerebral haemodynamics especially for infants with CHD are scarce.

AIM

This study was done to compare the changes in regional cerebral oxygen saturation and cerebral blood flow velocity when the end-tidal carbon dioxide partial pressure changed during different minute ventilation settings in infants undergoing ventricular septal defect repair.

METHODS

A total of 67 patients less than 1 year old with ventricular septal defect were enrolled, and 65 patients (age: 6.7 ± 3.4 months, weight: 6.4 ± 1.5 kg) were studied. After anaesthesia induction and endotracheal intubation, the same mechanical ventilation mode (The fraction of inspired oxygen was 50%, and the inspiratory-to-expiratory ratio was 1:1.5.) was adopted. The end-tidal carbon dioxide partial pressure of 30 mmHg (T1), 35 mmHg (T2), 40 mmHg (T3), or 45 mmHg (T4) were obtained, respectively, by adjusting tidal volume and respiratory rate. Minute ventilation per kilogram was calculated by the formula: minute ventilation per kilogram = tidal volume * respiratory rate/kg. Regional cerebral oxygen saturation was monitored by real-time near-infrared spectroscopy. Cerebral blood flow velocity (systolic flow velocity, end-diastolic flow velocity, and mean flow velocity), pulsatility index, and resistance index were measured intermittently by transcranial Doppler. Systolic pressure, diastolic pressure, stroke volume index, and cardiac index were recorded using the pressure recording analytical method.

RESULTS

As the end-tidal carbon dioxide partial pressure increased from 30 to 45 mmHg, regional cerebral oxygen saturation increased significantly from 69 ± 5% to 79 ± 4% (p < 0.001). Cerebral blood flow velocity (systolic flow velocity, end-diastolic flow velocity, and mean flow velocity) increased linearly, while pulsatility index and resistance index decreased linearly from T1 (systolic flow velocity, 84 ± 19 cm/second; end-diastolic flow velocity, 14 ± 4 cm/second; mean flow velocity, 36 ± 10 cm/second; pulsatility index, 2.13 ± 0.59; resistance index, 0.84 ± 0.12) to T4 (systolic flow velocity, 113 ± 22 cm/second; end-diastolic flow velocity, 31 ± 6 cm/second; mean flow velocity, 58 ± 11 cm/second; pulsatility index, 1.44 ± 0.34; resistance index, 0.72 ± 0.07) (p < 0.001). There were significant differences in changes of systolic flow velocity, end-diastolic flow velocity, mean flow velocity, pulsatility index, and resistance index as the end-tidal carbon dioxide partial pressure increased from 30 to 45 mmHg between subgroups of infants ≤6 and infants >6 months, while the changes of regional cerebral oxygen saturation between subgroups were not statistically different. Regional cerebral oxygen saturation and cerebral blood flow velocity (systolic flow velocity, end-diastolic flow velocity, and mean flow velocity) were negatively correlated with minute ventilation per kilogram (r = -0.538, r = -0.379, r = -0.504, r = -0.505, p < 0.001). Pulsatility index and resistance index were positively related to minute ventilation per kilogram (r = 0.464, r = 0.439, p < 0.001). The diastolic pressure was significantly reduced from T1 (41 ± 7 mmHg) to T4 (37 ± 6 mmHg) (p < 0.001). There were no significant differences in systolic pressure, stroke volume index, and cardiac index with the change of end-tidal carbon dioxide partial pressure from T1 to T4 (p = 0.063, p = 0.382, p = 0.165, p > 0.05).

CONCLUSION

A relative low minute ventilation strategy increases regional cerebral oxygen saturation and cerebral blood flow, which may improve cerebral oxygenation and brain perfusion in infants undergoing ventricular septal defect repair.

Acute Kidney Injury and Renal Regional Oxygen Saturation During Pediatric Liver Transplantation

Background

Kidney injury is a complication among children undergoing liver transplantation (pLTx). Cystatin C serum concentration seems to be superior to creatinine-based determination of kidney injury in adults and children. Near-infrared spectroscopy (NIRS) technology provides non-invasive and real-time measurement of renal tissue oxygenation. Here, we compared renal tissue oximetry (rSrO₂) with conventional diagnostic criteria cystatin C and creatinine concentration in children undergoing pLTx.

Material/Methods

rSrO₂ was measured intraoperatively in children undergoing pLTx over the left kidney, and was statistically compared with pre- and postoperative serum creatinine and cystatin C concentrations.

Results

rSrO₂ was affected by hemoglobin concentration, bilirubin concentration, and FiO₂. Statistical analysis demonstrated that rSrO₂ was significantly reduced in children with preoperative pathologic increased cystatin C concentrations compared to children without (63.7±4.3 vs. 53.4±4.9, p<0.05). We did not detect a significant difference in rSrO₂ between children who developed postoperative renal impairment, either determined by increased postoperative cystatin C concentration, creatinine concentration, or the pRIFLE criteria. Intraoperative increase or decrease in rSrO₂ did not predict the development of postoperative kidney injury.

Conclusions

In children with liver failure undergoing pLTx, a preoperative decrease in rSrO₂ indicates compromised renal function. However, intraoperative rSrO₂ is not predictive of postoperative kidney injury.

Near-Infrared-Based Cerebral Oximetry for Prediction of Severe Acute Kidney Injury in Critically Ill Children After Cardiac Surgery

Supplemental Digital Content is available in the text.

Cerebral oximetry by near-infrared spectroscopy is used frequently in critically ill children but guidelines on its use for decision making in the PICU are lacking. We investigated cerebral near-infrared spectroscopy oximetry in its ability to predict severe acute kidney injury after pediatric cardiac surgery and assessed its additional predictive value to routinely collected data.

Cerebral Oximetry in Syncope and Syndromes of Orthostatic Intolerance

Cerebral autoregulation is crucial for maintaining cerebral blood flow and perfusion. In recent years, the importance of cerebral oxygenation in syncope and orthostatic intolerance (OI) has received increased attention. Cerebral tissue oxygenation can be measured by using near-infrared spectroscopy (NIRS), which determines the ratio of oxygenated hemoglobin to total hemoglobin in cerebral tissue. NIRS is non-invasive technology using near-infrared light, which displays real-time cerebral tissue oxygenation. Normal values of cerebral tissue oxygenation in healthy subjects are 60 to 80%. Head-up tilt test (HUT) offers the opportunity to observe the haemodynamic changes precipitating syncope and is, today, the standard method for the evaluation of syncope and orthostatic intolerance syndromes. In previous studies where NIRS was applied during HUT, a significant decrease in cerebral tissue oxygenation both prior to and during loss-of-consciousness in vasovagal syncope (VVS) has been observed. Interestingly, cerebral tissue oxygenation appears to decrease even before haemodynamic changes can be observed. Apart from VVS, cerebral tissue oxygenation decreases during orthostatic provocation in patients with orthostatic hypotension (OH) and postural orthostatic tachycardia syndrome (POTS), in the latter even in the absence of hypotension. Importantly, decline of cerebral tissue oxygenation in VVS and POTS during HUT may not correlate with hemodynamic changes. In this mini review, we summarize the current knowledge of the application of cerebral oximetry in syncope and orthostatic intolerance syndromes, discuss its likely value as a clinical diagnostic tool and also emphasize its potential in the understanding of the relevant pathophysiology.

A practical approach to cerebral near-infrared spectroscopy (NIRS) directed hemodynamic management in noncardiac pediatric anesthesia

Safeguarding cerebral function is of major importance during pediatric anesthesia. Premature, ex-premature, and full-term neonates can be vulnerable to physiological changes that occur during anesthesia and surgery. Data from studies performed during pediatric cardiac surgery and in neonatal/pediatric intensive care units have shown the benefits of near-infrared spectroscopy (NIRS) monitoring of regional cerebral oxygenation (c-rSO₂ ). However, NIRS monitoring is seldom used during noncardiac pediatric anesthesia. Despite compelling evidence that blood pressure does not reflect end-organ perfusion, it is still regarded as the most important determinant of cerebral perfusion and the most relevant hemodynamic management target parameter by most (pediatric) anesthetists. The principle of NIRS monitoring is not self-explanatory and sometimes seems even counterintuitive, which may explain why many anesthesiologists are reserved regarding its use. The first part of this paper is dedicated to a clinical introduction to NIRS monitoring. Despite scientific efforts, it has not yet been possible to define individual lower limit c-rSO₂ values and it is unlikely this will succeed in the near future. Nonetheless, published treatment algorithms usually specify c-rSO₂ values which may be associated with cerebral hypoxia. Our treatment guideline for maintaining sufficient cerebral oxygenation differs fundamentally from all previously published approaches. We define a baseline c-rSO₂ value, registered in the awake child prior to anesthesia induction, as the lowest acceptable limit during anesthesia and surgery. The cerebral rSO₂ is the single target parameter, while blood pressure, heart rate, P_a CO₂ , and SaO₂ are major parameters that determine the c-rSO2. Cerebral NIRS monitoring, interpreted together with its continuously available contributing parameters, may help avoid potentially harmful episodes of cerebral desaturation in anesthetized pediatric patients.

Regional tissue oxygenation monitoring in the neonatal intensive care unit: evidence for clinical strategies and future directions

Near-infrared spectroscopy (NIRS)-based monitoring of regional tissue oxygenation (rSO₂) is becoming more commonplace in the neonatal intensive care unit (NICU). While increasing evidence supports rSO₂ monitoring, actual standards for applying this noninvasive bedside technique continue to evolve. This review highlights the current strengths and pitfalls surrounding practical NIRS-based monitoring in the neonatal population. The physiologic background of rSO₂ monitoring is discussed, with attention to understanding oxygen delivery/consumption mismatch and its effects on tissue oxygen extraction. The bedside utility of both cerebral and peripheral rSO₂ monitoring in the NICU is then explored from two perspectives: (1) disease/event-specific "responsive" monitoring and (2) "routine," continuous monitoring. Recent evidence incorporating both monitoring approaches is summarized with emphasis on practical applicability in the NICU. Finally, a future paradigm for a broad-based NIRS monitoring strategy is presented, with attention towards improving personalization of neonatal care and ultimately enhancing long-term outcomes.

The physiological determinants of near-infrared spectroscopy-derived regional cerebral oxygenation in critically ill adults

Background

To maintain adequate oxygen delivery to tissue, resuscitation of critically ill patients is guided by assessing surrogate markers of perfusion. As there is no direct indicator of cerebral perfusion used in routine critical care, identifying an accurate strategy to monitor brain perfusion is paramount. Near-infrared spectroscopy (NIRS) is a non-invasive technique to quantify regional cerebral oxygenation (rSO₂) that has been used for decades during cardiac surgery which has led to targeted algorithms to optimize rSO₂ being developed. However, these targeted algorithms do not exist during critical care, as the physiological determinants of rSO₂ during critical illness remain poorly understood.

Materials and methods

This prospective observational study was an exploratory analysis of a nested cohort of patients within the CONFOCAL study (NCT02344043) who received high-fidelity vital sign monitoring. Adult patients (≥ 18 years) admitted < 24 h to a medical/surgical intensive care unit were eligible if they had shock and/or required mechanical ventilation. Patients underwent rSO₂ monitoring with the FORESIGHT oximeter for 24 h, vital signs were concurrently recorded, and clinically ordered arterial blood gas samples and hemoglobin concentration were also documented. Simultaneous multiple linear regression was performed using all available predictors, followed by model selection using the corrected Akaike information criterion (AICc).

Results

Our simultaneous multivariate model included age, heart rate, arterial oxygen saturation, mean arterial pressure, pH, partial pressure of oxygen, partial pressure of carbon dioxide (PaCO₂), and hemoglobin concentration. This model accounted for a significant proportion of variance in rSO₂ (R² = 0.58, p < 0.01) and was significantly associated with PaCO₂ (p < 0.05) and hemoglobin concentration (p < 0.01). Our selected regression model using AICc accounted for a significant proportion of variance in rSO₂ (R² = 0.54, p < 0.01) and was significantly related to age (p < 0.05), PaCO₂ (p < 0.01), hemoglobin (p < 0.01), and heart rate (p < 0.05).

Conclusions

Known and established physiological determinants of oxygen delivery accounted for a significant proportion of the rSO₂ signal, which provides evidence that NIRS is a viable modality to assess cerebral oxygenation in critically ill adults. Further elucidation of the determinants of rSO₂ has the potential to develop a NIRS-guided resuscitation algorithm during critical illness.

Trial registration

This trial is registered on clinicaltrials.gov (Identifier: NCT02344043), retrospectively registered January 8, 2015.

Electronic supplementary material

The online version of this article (10.1186/s40635-019-0247-0) contains supplementary material, which is available to authorized users.

Near-infrared Spectroscopy in Transport With a Patient in Multi-factorial Shock

A 14-year-old male with a history of repaired truncus arteriosus presented to an outside hospital emergency room in respiratory distress. The triage report to the transport referral center included the following vital signs: temperature of 36.6°C, respiratory rate (RR) of 26 breaths/min, heart rate (HR) of 144 beats/min, and blood pressure (BP) of 113/52 mm Hg with peripheral capillary oxygen saturation (SpO₂) of 95% on 4 L via an OxyMask (SouthMedic, Barrie, Ontario, Canada). Additional information indicated severe right ventricle to pulmonary artery conduit stenosis; anuria for 2 days; and cool, mottled extremities. The transport team was dispatched via helicopter. The vital signs upon arrival were as follows: temperature of 36.5°C, HR of 153 beats/min, RR of 48 breaths/min, BP of 81/52, mean arterial pressure of 62, and SpO₂ of 96% on 8 L via an OxyMask. Physical assessment revealed the patient was alert and oriented, tachypneic, tachycardic, and displaying poor perfusion. An epinephrine drip was initiated while the patient was being prepared for transport. Near-infrared spectroscopy (NIRS) was initiated with cerebral NIRS of 71% and renal NIRS of 39%. The epinephrine drip was escalated, and norepinephrine was initiated and titrated up for continued poor perfusion and low renal NIRS. Vitals at the transfer of care at the receiving facility were HR of 142 beats/min, BP of 91/51 mm Hg, RR of 56 breaths/min, SpO₂ of 99%, and cerebral NIRS of 75% and renal NIRS of 53%. The patient required mechanical circulatory support shortly after admission. NIRS monitoring was used to help measure perfusion and reassess interventions made during transport.

Recent achievements and future developments in neonatal cardiopulmonary bypass

A primary goal of improving neonatal cardiopulmonary bypass has been making the circuit smaller and reduce the blood contacting surfaces. As bypass circuit size has decreased, bloodless surgery has become possible even in neonates. Since transfusion guidelines are difficult to construct based on existing literature, these technical advances should be taken advantage of in conjunction with an individualized transfusion scheme, based on monitoring of oxygen availability to the tissues. For the majority of neonatal heart operations, several centers have shifted toward normothermic bypass even for complex neonatal surgeries, in order to avoid the adverse effects of hypothermia. Deep hypothermic circulatory arrest is no longer a necessity but an option, and selective antegrade cerebral perfusion has become common practice; however, technical uncertainties with regard to this technique have to be addressed, based on reliable neurologic monitoring. Maintenance of patient-specific heparin concentrations during bypass is another key goal, since neonates have lower baseline antithrombin concentrations and, therefore, a higher risk for inadequate thrombin inhibition and postoperative bleeding. Due to the immaturity of their hemostatic system, the standard coagulation tests alone are inappropriate to guide hemostatic therapy in neonates. The use of indirect heparin concentration assays and global viscoelastic assays in the operating room is likely to represent the optimal strategy, and requires validation in neonates. Monitoring of global and regional indexes of oxygen availability and consumption on bypass have become possible; however, their use in neonates still has outstanding technical issues which should be addressed and hence needs further validation. Due to the immaturity of the neonatal myocardium, single-shot cold cardioplegia solutions are thought to confer the best myocardial protection; their superiority when compared to more conventional modalities, however, remains to be demonstrated.

Monitoring of cerebral oximetry during head-up tilt test in adults with history of syncope and orthostatic intolerance

Aims

We applied near-infrared-spectroscopy (NIRS) to measure absolute frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients investigated for unexplained syncope.

Methods and results

Synchronized non-invasive beat-to-beat haemodynamic monitoring, ECG, SctO2 (NIRS; normal range: 60-80%), and peripheral oxygen saturation (left hand, SpO2) were applied during HUT in a random sample of patients with unexplained syncope. Tracings of 54 patients (mean-age: 55 ± 19 years, 39% male) with negative HUT, vasovagal syncope (VVS), or orthostatic hypotension (OH) were analysed. In 44 patients HUT was diagnostic, in 10 HUT was negative. Thirty-one experienced VVS. Of these, 6 had spontaneous and 25 nitroglycerin-induced syncope. Thirteen patients had orthostatic hypotension (OH). Although there was no significant change in mean-arterial pressure from baseline to 1 min before syncope or end of passive HUT phase (-1.4 ± 13.9 mmHg; P = 0.45), there was a significant fall in SctO2 during the same period (-3.2 ± 3.2%; P ≤ 0.001). Among patients who experienced syncope, a decrease in SctO2 from 71 ± 5% at baseline to 53 ± 9% (P < 0.001) at syncope was observed. During HUT, there was a significant difference in delta SctO2 between spontaneous VVS (-4.5 ± 3.0%) and negative HUT (-1.3 ± 1.9%; P  = 0.021), but not between spontaneous VVS and OH (-5.4 ± 4.2%; P = 0.65). In spontaneous VVS, progressive decrease of SctO2 was independent of mean arterial pressure decrease (P  = 0.22).

Conclusions

Progressive decrease in cerebral tissue oxygenation independent of mean-arterial pressure may precede spontaneous vasovagal reflex during tilt. Patients experience syncope when SctO2 falls below 60%. These data confirm clinical utility of absolute cerebral oximetry monitoring for syncope investigation. We applied NIRS to measure frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients with unexplained syncope. In 44 of 54 patients, HUT was diagnostic. In patients with syncope, a significant SctO2-decrease was observed. Different patterns of SctO2 can be detected.