Near-Infrared Cerebral Oximetry to Predict Outcome After Pediatric Cardiac Surgery: A Prospective Observational Study

Association of Preoperative Oxygen Saturation and McGoon Ratio With Early Prognosis of Tetralogy of Fallot: A Propensity Score-Matched Analysis

AIM

Tetralogy of Fallot (TOF) is the most common cyanotic heart disease. This study aimed to demonstrate the effects of preoperative oxygen saturation on the early prognosis of TOF and identify risk factors associated with early complications.

METHOD

A cohort of 1,138 patients who were diagnosed and underwent one-stage surgical repair in this hospital were retrospectively included in this study. The cohort was divided into three groups according to preoperative oxygen saturation: group 1 (≤75%, n=275), group 2 (75%-85%, n=339), and group 3 (≥85, n=524).

RESULTS

There were 16 early deaths (16 of 1,138) and no late deaths in this study. The total mortality rate was 1.41%, which was not significantly different among the three groups. Major adverse events (MAE)-including death, extracorporeal membrane oxygenation assistance, delayed sternal closure, and re-operation during hospitalisation-were reported in 11.81% of patients in group 1, 7.93% in group 2, and 5.61% in group 3 (p=0.008). Multivariable risk analysis showed that atrial septal defect fenestration (p=0.002), aortic cross-clamp time (p=0.027), and McGoon ratio (p=0.046) were associated with MAE. By propensity score matching, the lower McGoon ratio was significantly related to MAE.

CONCLUSIONS

The surgical outcomes were acceptable, with low mortality and MAE rates. The McGoon ratio, not oxygen saturation, presented as a determining factor of MAE.

Regional Cerebral Oxygen Saturation and Estimated Oxygen Extraction Ratio as Predictive Markers of Major Adverse Events in Infants with Congenital Heart Disease

Regional cerebral oxygen saturation (ScO2) determined by near-infrared spectroscopy, monitoring both arterial and venous blood oxygenation of the brain, could reflect the balance between oxygen delivery and consumption. The aim of this study was to determine the predictabilities of ScO2 and estimated oxygen extraction ratio (eO2ER) with outcomes in infants with congenital heart disease (CHD). This study was a two-center, retrospective study of patients at 12 months of age or younger with CHD who underwent cardiac surgery. The primary outcome was a composite of one or more major adverse events (MAEs) after surgery: death from any cause, circulatory collapse that needed cardiopulmonary resuscitation, and requirement for extracorporeal membrane oxygenation. Based on the assumptions of arterial to venous blood ratio, eO2ER was calculated. A total of 647 cases were included in this study. MAEs occurred in 16 patients (2.5%). There were significant differences in post-bypass ScO2 [46.61 (40.90, 52.05) vs. 58.52 (51.52, 66.08), p < 0.001] and post-bypass eO2ER [0.66 (0.60, 0.78) vs. 0.52 (0.43, 0.61), p < 0.001] between patients with MAEs and patients without MAEs. Area under the receiver operating curve (AUROC) of post-bypass ScO2 was 0.818 (95% confidence interval: 0.747-0.889), AUROC of post-bypass eO2ER was 0.783 (0.697-0.870) and AUROC of post-bypass maximum serum lactate level was 0.635 (0.525-0.746). Both ScO2 and eO2ER, especially after weaning off bypass, are acceptable predictive markers for predicting MAEs after cardiac surgery in infants.(227 words).

Correlation of Near-Infrared Spectroscopy (NIRS) with Invasive Arterial Pressure Monitoring during Aortic Coarctation Surgery in Pediatric Patients

Aortic coarctation surgery in pediatric patients requires the placement of two arterial cannulas to monitor pressure gradients and surgical correction adequacy. Near-infrared spectroscopy (NIRS) monitoring provides insight into regional blood flow. This study aimed to investigate the correlation between NIRS values and invasive arterial pressures, exploring NIRS monitoring as a potential substitute for arterial cannulation. In a cohort of 21 consecutive pediatric patients undergoing aortic coarctation surgery, recordings of NIRS and invasive arterial pressure values were evaluated at various time intervals. Pearson correlation evaluated the relationship between NIRS values and invasively measured arterial pressures. Moderate to strong correlations were observed between the mean arterial pressure (MAP) of the upper and lower arteries and cerebral (rSO2-C) and somatic (rSO2-S) NIRS values 5 min after cross-clamp placement (r = 0.621, p = 0.003; r = 0.757, p < 0.001). Strong correlations were found 15 min after cross-clamp placement (r = 0.828, p = 0.002; r = 0.783, p = 0.004). Before transfer to the ICU, a strong correlation existed between the upper artery MAP and rSO2-C (r = 0.730, p < 0.001), but there was no correlation between the lower artery MAP and rSO2-S. These findings are promising, but further studies are required to validate it as a reliable substitute for invasive pressure monitoring in this patient population.

Update in Pediatric Neurocritical Care: What a Neurologist Caring for Critically Ill Children Needs to Know

Currently nearly one-quarter of admissions to pediatric intensive care units (PICUs) worldwide are for neurocritical care diagnoses that are associated with significant morbidity and mortality. Pediatric neurocritical care is a rapidly evolving field with unique challenges due to not only age-related responses to primary neurologic insults and their treatments but also the rarity of pediatric neurocritical care conditions at any given institution. The structure of pediatric neurocritical care services therefore is most commonly a collaborative model where critical care medicine physicians coordinate care and are supported by a multidisciplinary team of pediatric subspecialists, including neurologists. While pediatric neurocritical care lies at the intersection between critical care and the neurosciences, this narrative review focuses on the most common clinical scenarios encountered by pediatric neurologists as consultants in the PICU and synthesizes the recent evidence, best practices, and ongoing research in these cases. We provide an in-depth review of (1) the evaluation and management of abnormal movements (seizures/status epilepticus and status dystonicus); (2) acute weakness and paralysis (focusing on pediatric stroke and select pediatric neuroimmune conditions); (3) neuromonitoring modalities using a pathophysiology-driven approach; (4) neuroprotective strategies for which there is evidence (e.g., pediatric severe traumatic brain injury, post-cardiac arrest care, and ischemic stroke and hemorrhagic stroke); and (5) best practices for neuroprognostication in pediatric traumatic brain injury, cardiac arrest, and disorders of consciousness, with highlights of the 2023 updates on Brain Death/Death by Neurological Criteria. Our review of the current state of pediatric neurocritical care from the viewpoint of what a pediatric neurologist in the PICU needs to know is intended to improve knowledge for providers at the bedside with the goal of better patient care and outcomes.

Effect of Optimizing Regional Cerebral Oxygen Saturation during Infant Cardiac Surgery on the Incidence of Postoperative Delirium: A Retrospective Study

PURPOSE

To investigate the effect of optimizing regional cerebral oxygen saturation (rScO2) on the incidence of postoperative delirium and surgical outcome in infants with congenital heart disease.

METHODS

Sixty-one infants experienced desaturation in rScO2 of 10% from baseline for more than 30 seconds during surgery between January 2020 and January 2022. Among them, 32 cases (Group A) received the corresponding treatment in the process of desaturation and 29 cases (Group B) were observed without receiving any treatment. General information, cerebral oxygen saturation, the incidence of postoperative delirium, and other relevant clinical data were collected.

RESULTS

The duration and severity of intraoperative rScO2 desaturation in Group A were significantly lower than those in Group B. The incidence of postoperative delirium in Group A was significantly lower than that in Group B. There was no significant difference in the positive screening score for delirium between the two groups. Binary logistic regression analysis showed that the aortic cross-clamp time, mechanical ventilation duration, and severity of intraoperative rScO2 desaturation were significantly correlated with the occurrence of postoperative delirium.

CONCLUSION

Aggressive rScO2 desaturation treatment is associated with a lower incidence of postoperative delirium and improved surgical outcomes.

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.

Changes in Cerebral Regional Oxygen Saturation Variability in Neonates Undergoing Cardiac Surgery: A Prospective Cohort Study

Near-infrared spectroscopy is routinely used in the monitoring of cerebral regional oxygen saturation (crSO2) in neonates following congenital heart surgery. Decreased postoperative crSO2 variability in these patients is associated with worse clinical outcomes, including neurodevelopmental outcomes. We sought to explore changes in crSO2 variability between the preoperative and postoperative periods and associations with short-term clinical outcomes in neonates undergoing cardiac surgery. We performed a prospective cohort study of neonates undergoing cardiac surgery with cardiopulmonary bypass between November 2019 and May 2021. We calculated crSO2 variability using averaged 1 min of crSO2 values for a minimum of 12 h before, and the first 48 h following surgery. 37 neonates (median age at start of monitoring 4 days (interquartile range 2-5 days)) were included in our study. We observed a 30% decrease in crSO2 variability between the preoperative and postoperative monitoring periods (p < 0.001). Preoperative crSO2 variability increased by 9% (p = 0.009) for each additional postnatal day. There were no associations between the degree of decrease in crSO2 variability postoperatively and class of cardiac lesion (e.g., aortic arch obstruction, single ventricle physiology) or short-term postoperative clinical outcomes. There was a significant decrease in postoperative crSO2 variability following neonatal cardiac surgery as compared to the preoperative period, likely influenced by several factors. The impact of interventions on crSO2 variability and resultant influence on long-term outcomes, such as neurodevelopmental outcomes, requires further exploration.

Early post-operative neurodevelopment and visual assessment in neonates with congenital heart disease undergoing cardiac surgery

OBJECTIVE

Assessment of neurobehavior and visual function of newborns with congenital heart disease during the post-operative period to identify infants at risk of neurodevelopmental and visual impairment.

STUDY DESIGN

Prospective study that included 45 newborns who underwent cardiac surgery. Newborn Behavioral Observations test (NBO) and "ML Battery of Optotypes" were used for assessment.

RESULTS

The median NBO global score was 2.4 [2.1-2.6]. Total days of oral morphine [p = 0.005] and total days of sedation [p = 0.009] were strongly related to abnormal evaluations. Time of cerebral regional oxygen saturation (CrSO2) under 40% during surgery and increased lactate were related to abnormal motor evaluation. Only 14.5% of patients presented pathological results in visual evaluation.

CONCLUSIONS

We have demonstrated alterations in attention, autonomic, motor, and oral motor function. Duration of sedative medication, time of CrSO2 under 40% during surgery, and increased lactate are the most important risk factors. No significant visual impairment was detected.

Absolute Versus Relative Near-Infrared Spectroscopy in Pediatric Cardiac Patients

OBJECTIVES

Near-infrared spectroscopy (NIRS) has been increasingly accepted as a noninvasive marker of regional tissue oxygenation despite concerns of imprecision and wide limits of agreement (LOA) with invasive oximetry. New generation absolute monitors may have improved accuracy compared with trend monitors. We sought to compare the concordance with invasive venous oximetry of a new generation absolute NIRS-oximeter (FORESIGHT ELITE; CASMED, Branford, CT) with a modern widely used trend monitor (INVOS 5100C; Medtronic, Minneapolis, MN).

DESIGN

Prospective single-center study.

SETTING

Tertiary pediatric heart center.

PATIENTS

Children undergoing elective cardiac catheterization under general anesthesia. Time-paired venous oximetry samples (jugular and renal) were compared with NIRS-derived oximetry by two monitors using regression and Bland-Altman analysis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We enrolled 36 children (19 female, 10 cyanotic) with median age 4.1 years (25-75%, 2.5-7.8 yr) and weight 16.7 kg (12.3-29.1 kg). The absolute difference between NIRS-derived and invasive jugular oximetry was less than 10% in 67% of occasions for both monitors. Correlation was fair (Spearman rs = 0.40; p = 0.001) for the FORESIGHT ELITE and poor ( rs = 0.06; p = 0.71) for the INVOS 5100C. Bias and LOA were +6.7% (+22%, -9%) versus +1.3% (LOA = +24%, -21%), respectively. The absolute difference between NIRS-derived and invasive renal oximetry was less than 10% in 80% of occasions with moderate correlation ( rs = 0.57; p < 0.001) for the FORESIGHT ELITE and in 61% of occasions with moderate correlation ( rs = 0.58; p < 0.001) for the INVOS 5100C; bias and LOA were +3.6% (+19%, -12%) and -1.4 % (+27%, -30%), respectively. NIRS correlation with renal venous oximetry was worse for cyanotic versus noncyanotic patients ( p = 0.02).

CONCLUSIONS

Concordance and LOA of NIRS-derived oximetry with invasive venous oximetry in the cerebral and renal vascular beds was suboptimal for clinical decision-making. Cyanosis adversely affected NIRS performance in the renal site.

Development and External Validation of a Machine Learning Model for the Early Prediction of Doses of Harmful Intracranial Pressure in Patients with Severe Traumatic Brain Injury

Treatment and prevention of elevated intracranial pressure (ICP) is crucial in patients with severe traumatic brain injury (TBI). Elevated ICP is associated with secondary brain injury, and both intensity and duration of an episode of intracranial hypertension, often referred to as "ICP dose," are associated with worse outcomes. Prediction of such harmful episodes of ICP dose could allow for a more proactive and preventive management of TBI, with potential implications on patients' outcomes. The goal of this study was to develop and validate a machine-learning (ML) model to predict potentially harmful ICP doses in patients with severe TBI. The prediction target was defined based on previous studies and included a broad range of doses of elevated ICP that have been associated with poor long-term neurological outcomes. The ML models were used, with minute-by-minute ICP and mean arterial blood pressure signals as inputs. Harmful ICP episodes were predicted with a 30 min forewarning. Models were developed in a multi-center dataset of 290 adult patients with severe TBI and externally validated on 264 patients from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) dataset. The external validation of the prediction model on the CENTER-TBI dataset demonstrated good discrimination and calibration (area under the curve: 0.94, accuracy: 0.89, precision: 0.87, sensitivity: 0.78, specificity: 0.94, calibration-in-the-large: 0.03, calibration slope: 0.93). The proposed prediction model provides accurate and timely predictions of harmful doses of ICP on the development and external validation dataset. A future interventional study is needed to assess whether early intervention on the basis of ICP dose predictions will result in improved outcomes.

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.

Pediatric Neurocritical Care

Brain injury in children is a major public health problem, causing substantial morbidity and mortality. Cause of pediatric brain injury varies widely and can be from a primary neurologic cause or as a sequela of multisystem illness. This review discusses the emerging field of pediatric neurocritical care (PNCC), including current techniques of imaging, treatment, and monitoring. Future directions of PNCC include further expansion of evidence-based practice guidelines and establishment of multidisciplinary PNCC services within institutions.

Postoperative Cerebral Oxygen Saturation in Children After Congenital Cardiac Surgery and Long-Term Total Intelligence Quotient: A Prospective Observational Study

OBJECTIVES

During the early postoperative period, children with congenital heart disease can suffer from inadequate cerebral perfusion, with possible long-term neurocognitive consequences. Cerebral tissue oxygen saturation can be monitored noninvasively with near-infrared spectroscopy. In this prospective study, we hypothesized that reduced cerebral tissue oxygen saturation and increased intensity and duration of desaturation (defined as cerebral tissue oxygen saturation < 65%) during the early postoperative period, independently increase the probability of reduced total intelligence quotient, 2 years after admission to a PICU.

DESIGN

Single-center, prospective study, performed between 2012 and 2015.

SETTING

The PICU of the University Hospitals Leuven, Belgium.

PATIENTS

The study included pediatric patients after surgery for congenital heart disease admitted to the PICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Postoperative cerebral perfusion was characterized with the mean cerebral tissue oxygen saturation and dose of desaturation of the first 12 and 24 hours of cerebral tissue oxygen saturation monitoring. The independent association of postoperative mean cerebral tissue oxygen saturation and dose of desaturation with total intelligence quotient at 2-year follow-up was evaluated with a Bayesian linear regression model adjusted for known confounders. According to a noninformative prior, reduced mean cerebral tissue oxygen saturation during the first 12 hours of monitoring results in a loss of intelligence quotient points at 2 years, with a 90% probability (posterior β estimates [80% credible interval], 0.23 [0.04-0.41]). Similarly, increased dose of cerebral tissue oxygen saturation desaturation would result in a loss of intelligence quotient points at 2 years with a 90% probability (posterior β estimates [80% credible interval], -0.009 [-0.016 to -0.001]).

CONCLUSIONS

Increased dose of cerebral tissue oxygen saturation desaturation and reduced mean cerebral tissue oxygen saturation during the early postoperative period independently increase the probability of having a lower total intelligence quotient, 2 years after PICU admission.

Cerebral regional oxygen saturation variability in neonates following cardiac surgery

BACKGROUND

Reduced cerebral regional oxygen saturation (crSO₂) variability in neonates, as measured by near-infrared spectroscopy, following cardiac surgery with deep hypothermic circulatory arrest (DHCA) is associated with poor neurodevelopmental outcomes. We sought to evaluate the variability of crSO₂ in a cohort of neonates following cardiac surgery with brief or no exposure to DHCA.

METHODS

Variability of averaged 1-min crSO₂ values was calculated for the first 48 h following cardiac surgery in consecutive neonates over a 30-month period. Neonates requiring aortic arch repair underwent antegrade cerebral perfusion with either brief or no exposure to DHCA.

RESULTS

There were 115 neonates included in the study. Reduced crSO₂ variability was observed in neonates with aortic arch obstruction (p = 0.02) and non-survivors (p = 0.02). Post hoc analysis demonstrated that the reduction in crSO₂ variability was not as marked as in previously studied neonates with aortic arch obstruction who received DHCA alone (p < 0.001).

CONCLUSIONS

Neonates with aortic arch obstruction have reduced crSO₂ variability following cardiac surgery. The reduction in crSO₂ variability observed in aortic arch obstruction is likely influenced by a number of factors, including perioperative perfusion technique. The impact of interventions on crSO₂ variability and resultant influence on neurodevelopmental outcomes requires further study.

IMPACT

Neonates with aortic arch obstruction have reduced crSO₂ variability following cardiac surgery, which has been associated with poor neurodevelopmental outcomes, and is likely influenced by a number of factors, including perioperative perfusion technique. The contribution of perioperative perfusion technique to crSO₂ variability following neonatal cardiac surgery is significant. Monitoring of crSO₂ variability may provide insights into the adequacy of cerebral perfusion in neonates following cardiac surgery.

Cerebral oxygenation during pediatric congenital cardiac surgery and its association with outcome: a retrospective observational study

PURPOSE

Non-invasive cerebral oxygen saturation (ScO2) monitoring is an established tool in the intraoperative phase of pediatric congenital cardiac surgery (CCS). This study investigated the association between ScO2 and postoperative outcome by investigating both baseline ScO2 values and intraoperative desaturations from baseline.

METHODS

All CCS procedures performed in the period 2010-2017 in our institution in which ScO2 was monitored were included in this historical cohort study. Baseline ScO2 was determined after tracheal intubation, before surgical incision. Subgroups were based on cardiac pathology and degree of intracardiac shunting. Poor outcome was defined based on length of stay (LOS) in the intensive care unit (ICU)/hospital, duration of mechanical ventilation (MV), and 30-day mortality. Intraoperatively, ScO2 total time below baseline (TBBL) and ScO2 time-weighted average (TWA) were calculated.

RESULTS

Data from 565 patients were analyzed. Baseline ScO2 was significantly associated with LOS in ICU (odds ratio [OR] per percentage decrease in baseline ScO2, 0.95; 95% confidence interval [CI], 0.93 to 0.97; P < 0.001), with LOS in hospital (OR, 0.93; 95% CI, 0.91 to 0.96; P < 0.001), with MV duration (OR, 0.92; 95% CI, 0.90 to 0.95; P < 0.001) and with 30-day mortality (OR, 0.94; 95% CI, 0.91 to 0.98; P = 0.007). Cerebral oxygen saturation TWA had no associations, while ScO2 TBBL had only a small association with LOS in ICU (OR, 1.02; 95% CI, 1.01 to 1.03; P < 0.001), MV duration (OR,1.02; 95% CI, 1.01 to 1.03; P = 0.002), and LOS in hospital (OR, 1.02; 95% CI, 1.01 to 1.04; P < 0.001).

CONCLUSION

In pediatric patients undergoing cardiac surgery, low baseline ScO2 values measured after tracheal intubation were associated with several adverse postoperative outcomes. In contrast, the severity of actual intraoperative cerebral desaturation was not associated with postoperative outcomes. Baseline ScO2 measured after tracheal intubation may help identify patients at increased perioperative risk.

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.

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.

Neuromonitoring in paediatric anaesthesia

PURPOSE OF REVIEW

There has been a steady advance in neuromonitoring during anaesthesia. Inevitably much of the research is first done in adults and later in children. This review will focus on the recent paediatric publications (2017-2019) in two areas of neuromonitoring - measuring anaesthesia effect and cerebral perfusion and oxygenation.

RECENT FINDINGS

For EEG-derived depth monitors, the main recent advances have been in better understanding their performance in infants. For the first time, large multichannel EEG studies on infants have focused on understanding the basic principles of how anaesthesia impacts on the EEG of the developing brain in a way different to the older brain. Nociception monitors are beginning to be studied in children. In the area of optical neuromonitoring, studies show that cerebral desaturation during both general and spinal anaesthesia in infants is uncommon in neonates and infants. Further work emphasizes the importance of CO2 levels on cerebral oxygenation, and demonstrates impaired cerebral autoregulation in premature infants undergoing laparotomies.

SUMMARY

The impact of anaesthesia on the EEG of small infants has some gross similarities to older children but there are fundamental differences, which mandate separate calibration of anaesthesia depth monitors. The role of nociception monitors in children has yet to be defined. Cerebral oxygenation monitoring during paediatric anaesthesia is improving our understanding of cerebral perfusion in this period, but as with almost all monitoring, evidence that its use improves outcome is not yet available.