A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patients

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

PURPOSE

To evaluate whether regional cerebral oxygenation (rSO(2)) by near-infrared spectroscopy correlates with central venous (SvO(2)) or internal jugular (SjO(2)) oxygen saturation, and whether changes over time (Delta) in rSO(2) (DeltarSO(2)) predict changes in SvO(2) (DeltaSvO(2)) and SjO(2) (DeltaSjO(2)).

METHODS

The rSO(2) values were measured using the INVOS 5100 cerebral oximeter in children undergoing interventional cardiac catheterization and were compared with the oxygen saturation of analysed central venous and internal jugular blood samples. Changes over time (Delta) were calculated as the difference between the values before and after catheter intervention for rSO(2).(DeltarSO(2)), SvO(2).(DeltaSvO(2)) and SjO(2).(DeltaSjO(2)). Simple regression and Bland-Altman analysis were performed. Data are presented as median (range).

RESULTS

Sixty patients aged 4.3 (0.2-16.0) years were investigated. A closer correlation was found between rSO(2) and SvO(2) (r=0.728, P<0.0001) than between rSO(2) and SjO(2) (r=0.665, P<0.0001). The bias between rSO(2) and SvO(2).(SjO(2)) was 0.17% (-0.60%), with limits of agreement from -15.5% to 15. 9% (-18.6-17.4%). The sensitivity/specificity for DeltarSO(2) to indicate a fall in SvO(2) or in SjO(2) was 70.3%/65.2% and 68.6%/60.0%, respectively.

CONCLUSION

Neither absolute values nor changes in rSO(2) using the INVOS 5100 allowed reliable estimation of SvO(2) or SjO(2) and their trends.

[Care of the critically ill child with heart disease in Spain]

INTRODUCTION

The objective of the present study is to present the organization of the resources of paediatric cardiac critical care in Spain.

PATIENTS AND METHODS

Data were collected through questionnaires sent by e-mail to Spanish PICUs.

RESULTS

22 PICUs were enrolled. The median number of beds were 9.5 (4-18 beds). Total cardiac admissions represented a 20 % of total PICUs admissions per year, firstly for congenital heart defects, and secondly for respiratory problems. Cardiac surgical activities were carried out in 16 centres, centralized in PICU in 10 cases. Mechanical support of the myocardium was performed in 7 PICUs. A total of 10 participating PICUs considered echocardiograph training necessary and also an increase in the amount of activity for better results.

CONCLUSIONS

Paediatric cardiac critical care involves a significant use of resources, including PICUs with no surgical activity. This study is useful for detecting common problems and for improving clinical care.

Cerebral Oximetry Monitoring with Near Infrared Spectroscopy Detects Alterations in Oxygenation Before Pulse Oximetry

Background: The monitoring of oxygenation may be imperative to ensure patient safety and optimal outcome. We anecdotally noted that monitoring cerebral oxygenation (rSO2) using near infrared spectroscopy may provide an earlier warning of changes in oxygenation than pulse oximetry. Methods: Patients scheduled for airway laser surgery requiring intermittent periods of apnea were monitored with both a cerebral oximeter and a pulse oximeter. Following inhalational induction and endotracheal intubation, anesthesia was maintained with propofol. After 3 minutes of ventilation with 100% oxygen, the endotracheal tube was removed and laser surgery performed on the airway during apnea. The time for a 5% and a 10% decrease in the cerebral oximeter and the pulse oximeter was noted. Results: The study cohort included 10 infants and children ranging in age from 1 month to 7 years. The time for a 5% decrease of the rSO2 was 94 + 8 seconds versus 146 + 49 seconds for a 5% decrease of the SaO 2 (P < .0001). During all 42 episodes of apnea, the rSO2 decreased by 5% before the SaO2 had decreased by 5%. When the SaO2 had decreased by 5% (down to 95% from the starting value of 100%), the rSO2 had decreased by 16 + 4%. The time for a 10% decrease of the rSO2 was 138 + 29 seconds versus 189 + 64 seconds for a 10% decrease of the SaO2 (P = .0009). In all 42 cases, the rSO2 decreased by 10% before the SaO2. Conclusions: Cerebral oxygenation monitoring using near infrared spectroscopy detects changes in oxygenation earlier than standard pulse oximetry.

Repair of sinus venosus defect in a patient with untreated vein of Galen aneurysmal malformation

The vein of Galen aneurysmal malformation (VGAM) is a rare cerebral arteriovenous shunt, which may be associated with a congenital cardiac defect. Embolisation of the VGAM may be undertaken in the neonatal period if necessary, but is safer in infancy. Recent advances in neuroradiology have changed the prognosis for this group with many patients achieving survival with normal development. This case report describes a patient with a sinus venosus defect (SVD) and a VGAM and considers both the optimal timing of treatment of the two malformations and the conduct of anaesthesia for open repair of the SVD in the presence of an untreated VGAM.

Near Infrared Spectroscopy (NIRS) in Children

Near infrared spectroscopy (NIRS) is a noninvasive method for the in vivo monitoring of tissue oxygenation. Originally used predominantly to assess cerebral oxygenation, NIRS has gained widespread popularity in many clinical settings in all age groups. Changes in regional tissue oxygenation as detected by NIRS may reflect the delicate balance between oxygen delivery and consumption in more than one organ system. However, more studies are required to establish the ability of NIRS monitoring to improve patient outcome. This review provides a comprehensive description of NIRS in children.

Correlation of abdominal site near-infrared spectroscopy with gastric tonometry in infants following surgery for congenital heart disease

OBJECTIVE

Splanchnic oximetry, as measured by near-infrared spectroscopy (NIRS), correlates with gastric tonometry as a means of assessing regional (splanchnic) oxygenation and perfusion.

DESIGN

Prospective, data-gathering study.

SETTING

Pediatric cardiac intensive care unit in a tertiary care children's hospital.

SUBJECTS

Neonates and infants with congenital heart disease who underwent catheter intervention or surgical repair requiring cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twenty neonates and infants were studied within 48 hrs of surgery. We measured somatic saturation (rSO2) via NIRS sensors placed over the anterior abdomen (splanchnic bed) and dorsal lateral flank (renal bed). Somatic rSO2 readings were paired with simultaneous points of intramucosal gastric pH (pHi), measured by tonometry. The rSO2 readings were paired with serum lactate and measurements of systemic mixed venous saturation (SVO2). There was strong correlation between the abdominal rSO2 and pHi (r = .79; p < .0001) as well as between abdominal rSO2 and SVO2 (r = .89; p < .0001). There was also significant negative correlation between the abdominal rSO2 and serum lactate (r = .77; p < .0001). Correlations between the dorsal lateral (renal) rSO2 measurements and serum lactate and SVO2 were also significant but not as strong.

CONCLUSIONS

Abdominal site rSO2, measured in infants with either single or biventricular physiology, exhibits a strong correlation with gastric pHi as well as with serum lactate and SVO2. The results indicate that rSO2 measurements over the anterior abdominal wall correlate more strongly than flank rSO2 with regard to systemic indices of oxygenation and perfusion. This study suggests that the NIRS monitor is a valid modality to obtain an easy, immediate, and noninvasive measurement of splanchnic rSO2 in infants following cardiac surgery for congenital heart disease.

Clinical evaluation of time-resolved spectroscopy by measuring cerebral hemodynamics during cardiopulmonary bypass surgery

We developed a three-wavelength time-resolved spectroscopy (TRS) system, which allows quantitative measurement of hemodynamics within relatively large living tissue. We clinically evaluated this TRS system by monitoring cerebral circulation during cardiopulmonary bypass surgery. Oxyhemoglobin, deoxyhemoglobin, total hemoglobin and oxygen saturation (SO(2)) were determined by TRS on the left forehead attached with an optode spacing of 4 cm. We also simultaneously monitored jugular venous oxygen saturation (SjvO(2)) and arterial blood hematocrit (Hct) using conventional methods. The validity and usefulness of the TRS system were assessed by comparing parameters obtained with the TRS and conventional methods. Although the changes in SO(2) were lower than those in SjvO(2), SO(2) obtained by TRS paralleled the fluctuations in SjvO(2), and a good correlation between these values was observed. The only exceptions occurred during the perfusion period. Moreover, there was a good correlation between tHb and Hct values (r(2)=0.63). We concluded that time-resolved spectroscopy reflected the conditions of cerebral hemodynamics of patients during surgical operations.

Factors influencing neurologic outcome after neonatal cardiopulmonary bypass: what we can and cannot control

Advances in cardiopulmonary bypass and surgical techniques have led to progress in the early repair of congenital heart defects in children. However, as increasing numbers survive their initial cardiac operation, an awareness is emerging that significant early and late neurologic morbidities continue to complicate otherwise successful operative repairs. Adverse neurologic outcomes after neonatal cardiac surgery are multifactorial and relate to both fixed and modifiable mechanisms. The purpose of this review is to (1) review mechanisms of brain injury after neonatal cardiopulmonary bypass, (2) examine risk factors, and (3) speculate on how investigations may improve our understanding of neurologic injury.

Neurologic monitoring on cardiopulmonary bypass: what are we obligated to do?

Improving survival from congenital cardiac repairs using cardiopulmonary bypass has appropriately shifted focus to neurologic outcomes. Hypoxic-ischemic mechanisms are the major cause of neurologic injury in neonatal cardiac surgery, and modifications of techniques of cardiopulmonary bypass can affect organ oxygen delivery and the propensity to injury both during and after surgery. Through successive refinements in the techniques of cardiopulmonary bypass, the risk factors for hypoxic-ischemic injury have been reduced, but not eliminated. The application of specific monitoring to enhance detection of hypoxic conditions associated with neurologic injury would both allow intervention on individual patients and drive refinements in strategies to further reduce risk. Specific neurologic monitoring techniques that can be used during cardiopulmonary bypass include near-infrared spectroscopy, transcranial Doppler ultrasonography, and electroencephalographic techniques. Of these, only near-infrared spectroscopy provides a continuous quantitative signal of the physiologic variable most related to injury and most amenable to intervention. This review will advocate wide adoption of near-infrared spectroscopy monitoring throughout the perioperative period, to enhance detection of hypoxic conditions and to drive patient-specific interventions.

Cerebral Near-Infrared Spectroscopy in Adult Patients After Cardiac Surgery Is Not Useful for Monitoring Absolute Values But May Reflect Trends in Venous Oxygenation Under Clinical Conditions

OBJECTIVE

Cerebral near-infrared spectroscopy (NIRS) was evaluated for use in monitoring global oxygenation in adult patients after cardiac surgery.

DESIGN

Prospective, randomized clinical monitoring study.

SETTING

Intensive care unit for cardiac surgery; university hospital.

PARTICIPANTS

The study included 35 patients scheduled for cardiac surgery with insertion of a pulmonary artery catheter; patients with known cerebral-vascular perfusion disturbances were excluded.

INTERVENTIONS

Noninvasive cerebral NIRS oxygen saturation (rSO(2)) and conventional intensive care monitoring parameters were assessed.

MEASUREMENTS AND MAIN RESULTS

Simple regression analysis was used to assess the correlation of rSO(2) to hemodynamic parameters. There was fair-to-moderate intersubject correlation to hemoglobin concentration (r = 0.45, p < 0.0001) and mixed venous oxygen saturation (SmvO(2)) (r = 0.33, p < 0.0001). Sensitivity and specificity of rSO(2) to detect substantial (>or=1 standard deviation) changes in mixed venous oxygen saturation were 94% and 81%, respectively.

CONCLUSIONS

Cerebral NIRS in adult patients might not be the tool to replace mixed venous oxygen monitoring. Further work has to be done to assess its potential to reflect intraindividual trends.

Cerebral Oxygen Saturation Does Not Normalize Until After Stage 2 Single Ventricle Palliation

BACKGROUND

In an effort to optimize neurologic outcome, cerebral oxygen saturation (SCO2) is often measured intraoperatively and postoperatively. We hypothesized that SCO2 would be related to stage of palliation in children with single ventricle congenital heart disease.

METHODS

Cerebral oxygen saturation was continuously recorded intraoperatively in 34 infants and children undergoing palliative surgery on cardiopulmonary bypass for single ventricle congenital heart defects and in a control group of 12 neonates with ductus-dependent circulation undergoing complete repair. Saturations were correlated with the patient's stage and outcome.

RESULTS

Baseline SCO2 was 61% in single ventricle neonates (group P1, n = 10), 55% in neonates undergoing repair (group R), 42% in infants undergoing stage 2 palliation (group P2, n = 6), and 70% in children undergoing Fontan (group P3, n = 14). Baseline was lowest (41%) in infants undergoing interstage operations (group I, n = 4). After bypass, there was a significant improvement in SCO2 to 53% in group P2 infants (p = 0.04); there were no significant changes in the other groups. By the end of the operation, there was a significant decrease in SCO2 to 48% in group P1 (p = 0.001), with other groups unchanged from baseline. There were five perioperative deaths. Cerebral oxygen saturation at the conclusion of surgery was lower in children who died (38% versus 61%, p = 0.01).

CONCLUSIONS

In children with single ventricle physiology, SCO2 decreases after initial palliation, remains low before second-stage palliation, but is normal before and after the Fontan. This has implications for perioperative mortality, neurologic injury, and potentially for interim mortality. Low postoperative SCO2 predicts perioperative mortality.

Regional and central venous oxygen saturation monitoring following pediatric cardiac surgery: concordance and association with clinical variables

OBJECTIVE

To compare changes in regional cerebral or flank oxygen saturation measured by near-infrared spectroscopy with changes in central venous oxygen saturation (ScvO2) and to determine clinical variables associated with these changes.

DESIGN

Prospective observational cohort study.

SETTING

University tertiary care center, pediatric cardiac intensive care unit.

PATIENTS

Seventy postoperative congenital cardiac surgical patients (median age 0.3 yrs; interquartile range 0.02-0.46 yrs).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured temporally correlated regional oxygen saturation (rSO2) with hematologic (hematocrit), biochemical (arterial blood gas, ScvO2, and lactate) and physiologic (temperature, heart rate, mean blood pressure, and pulse oximetry) variables in the first postoperative day. Cerebral and flank rSO2 were strongly correlated with ScvO2, in both cyanotic or acyanotic patients and single- or two-ventricle physiology with and without aortic arch obstruction (all p < .001). However, individual values had wide limits of agreement on Bland-Altman analysis. The correlations of change in these measurements were weaker but still significant (all p < .0001), again with wide limits of agreement. Similar direction of change in cerebral rSO2 and ScvO2 was present 64% (95% confidence interval, 55-73%) of the time. Change in arterial pressure of carbon dioxide (delta PaCO2) was associated with cerebral delta rSO2 (delta PaCO2 beta = 0.35, p < .0001) but not flank delta rSO2 or delta ScvO2. A pattern of relative cerebral desaturation (flank rSO2 > cerebral rSO2) was noted in a majority of patients (81%) with two-site monitoring regardless of bypass method or age.

CONCLUSIONS

Neither individual values nor changes in rSO2 are interchangeable measures of ScvO2 in postoperative pediatric cardiac patients. The unique relationship between changes in PaCO2 and cerebral rSO2 supports the hypothesis that cerebral near-infrared spectroscopy monitors regional cerebral oxygenation. Clinical application of this monitor must include recognition of the clinical variables that affect regional brain oxygenation.

Cerebral near infrared spectroscopy is a reliable marker of systemic perfusion in awake single ventricle children

Clinical assessment of systemic perfusion in single ventricle patients with parallel circulation can be difficult in the outpatient setting. Near infrared spectroscopy (NIRS) is a noninvasive measure of cerebral oximetry. We measured vital signs, pulse oximetry, and NIRS in 20 single ventricle patients with parallel circulation prior to routine cardiac catheterization. These variables were evaluated to determine the best noninvasive predictor of the superior vena cava saturation (SVC(sat)) as a marker for the adequacy of systemic oxygen delivery. The mean age was 6.7 months [standard deviation (SD), 8.6] and mean weight was 6.5 kg (SD, 2.2). Diagnoses were hypoplastic left heart syndrome (8), tricuspid or pulmonary atresia (10), and double-outlet right ventricle variants (2), all prior to cavo pulmonary anastomoses or complete repairs. Stepwise multiple regression analysis generated a model in which only NIRS was a significant independent predictor of SVC(sat) (p = 0.009). These results support the conclusion that NIRS can be a useful tool to evaluate awake single ventricle patients in the outpatient setting.

Noninvasive cerebral oximeter as a surrogate for mixed venous saturation in children

We evaluated the relationship between regional cerebral oxygen saturation (rSO(2)) measured by near-infrared spectroscopy (NIRS) cerebral oximeter with superior vena cava (SVC), inferior vena cava (IVC), right atrium (RA), and pulmonary artery (PA) saturation measured on room air and 100% inspired oxygen administered via a non-rebreather mask (NRB) in children. Twenty nine pediatric post-orthotopic heart transplant patients undergoing an annual myocardial biopsy were studied. We found a statistically significant correlation between rSO(2) and SVC saturations at room air and 100% inspired oxygen concentration via NRB (r = 0.67, p = 0.0002 on room air; r = 0.44, p = 0.02 on NRB), RA saturation (r = 0.56, p = 0.002; r = 0.56, p = 0.002), and PA saturation (r = 0.67, p < 0.001; r = 0.4, p = 0.03). A significant correlation also existed between rSO(2) and measured cardiac index (r = 0.45, p = 0.01) and hemoglobin levels (r = 0.41, p = 0.02). The concordance correlations were fair to moderate. Bias and precision of rSO(2) compared to PA saturations on room air were -0.8 and 13.9%, and they were 2.1 and 15.6% on NRB. A stepwise linear regression analysis showed that rSO(2) saturations were the best predictor of PA saturations on both room air (p = 0.0001) and NRB (p = 0.012). In children with biventricular anatomy, rSO(2) readings do correlate with mixed venous saturation.

Anesthesia and postoperative analgesia in pediatric patients undergoing cardiac surgery

Pediatric cardiac anesthesiologists care for patients ranging from premature infants weighing <2 kg to adults requiring surgical intervention for congenital heart disease. Along with their cardiac pathophysiologies, many of these patients also have other co-existing diseases that can affect their anesthetic management. Recent advances in monitoring include non-invasive neuromonitors, such as near-infrared spectroscopy and trans-cranial Doppler, which are assuming increasing importance in intraoperative management, particularly during cardiopulmonary bypass. A variety of anesthetic techniques, including regional anesthesia, can be used to facilitate early extubation in older infants and children with stable postoperative hemodynamics. In addition to regional anesthesia, other modalities for the management of postoperative pain include opioid infusions in critically ill children and the use of patient- or nurse-controlled analgesia pumps. Multiple pain assessment tools are available for children of varying ages and developmental levels to assist in providing appropriate postoperative pain management.

Anästhesiologische Aspekte in der Neu- und Frühgeborenenchirurgie

The physiology of the preterm and term neonate is characterized by a high metabolic rate, limited pulmonary, cardiac and thermoregulatory reserve and decreased renal function. Multisystem immaturity creates important developmental differences in drug administration and response when compared to older children. Specific monitoring techniques are required because the neonate is not physically accessible to the anesthetist during the operation. This contribution reviews the specific pathophysiological characteristics of the newborn with relevance to anesthesia and also provides robust guidelines for the anesthetic management of the most frequent non-cardiac procedures which need surgery during the neonatal period. Consideration will also be given to the anesthetic management of very low birth-weight infants with anesthetic key issues such as avoiding hyperoxia, keeping hemodynamic parameters as stable as possible and preventing hypothermia.

MR susceptometry for measuring global brain oxygen extraction

Monitoring of oxygen saturation in jugular venous blood gives an estimate of the balance of global oxygen delivery and cerebral oxygen consumption. We present a noninvasive approach to measure oxygen saturation in vivo in the internal jugular vein using MR susceptometry by exploiting the characteristic susceptibility of deoxyhemoglobin, and demonstrate the feasibility of performing such measurements in a group of subjects. We assessed the sensitivity of the method for detecting small changes in oxygen saturation by monitoring the variations observed during breath-holding and hypoventilation experiments. Unlike alternative methods, the susceptometric technique does not require calibration.

Near-infrared spectroscopy in the fetus and neonate

Near-infrared spectroscopy allows for real-time, noninvasive measurement of cerebral hemodynamics and oxygenation at the bed-side. This article describes animal and clinical research using near-infrared spectroscopy to study cerebral hemodynamic function in the fetus, neonate, and child.

Mesenteric oxyhemoglobin desaturation improves with patent ductus arteriosus ligation

Near-infrared spectroscopy was used to monitor cerebral and mesenteric regional oximetry in a preterm neonate undergoing surgical ligation of a patent ductus arteriosus. This patient initially demonstrated severe mesenteric oxyhemoglobin desaturation, which improved immediately following ductal ligation.

Near-infrared spectroscopy in the detection of regional tissue oxygenation during hypoxic events in preterm infants undergoing critical care

OBJECTIVES

To determine whether pulse oximetry-detected episodes of desaturation are associated with impairment of cerebral and somatic (renal) tissue oxygenation in mechanically ventilated preterm neonates.

DESIGN

Observational cross-sectional study.

SETTING

Neonatal intensive care unit of a university-affiliated children's hospital.

PATIENTS

Ten mechanically ventilated preterm (gestational age 24-32 wks) infants.

INTERVENTIONS

In addition to the traditional monitoring of hemodynamic variables that included pulse oximetry (Sao2), near-infrared spectroscopy (NIRS) was used to evaluate the cerebral and somatic (renal) tissue oxygen saturation (rSO2C and rSO2R, respectively).

MEASUREMENTS AND MAIN RESULTS

A total of 40 rSO2C and rSO2R measurements were simultaneously recorded: 20 during hypoxic events when the Sao2 was </=80% for >/=4 secs (cases) and generally ranged between 70% and 80%, and 20 measurements when the Sao2 was >/=85% (paired controls). Additionally, the fractional oxygen extraction (FOE) from the cerebral (FOEC) and renal (FOER) tissue was calculated. All the measurements were made under steady conditions during a 2-hr period. The rSO2C, rSO2R, FOEC, and FOER among the cases (Sao2 </= 80%) and controls (Sao2 >/= 85%) were compared using the paired Student's t-test. Both rSO2C and rSO2R during the desaturation episodes were lower than in the controls (51.6 +/- 6.3% vs. 66.2 +/- 10.2%, p < .0001 and 61.1 +/- 6.8% vs. 80.1 +/- 10.0%, p < .0001, respectively). The FOEC during the hypoxic episodes was comparable with control levels but increased in renal tissue. However, during two of the desaturation episodes (10%), the rSO2C and FOEC levels (which were <44% and >0.47, respectively) may reflect compromised tissue oxygen supply.

CONCLUSIONS

In the majority of mechanically ventilated preterm neonates, the reduction in cerebral and renal tissue oxygenation associated with short periods of decreased arterial saturation to 70-80% does not significantly compromise oxygen utilization in the cerebral tissue but increases oxygen extraction in the renal tissue, which might cause ischemic tissue injury following a further reduction in oxygen delivery.

Detection of Lower Torso Ischemia by Near-Infrared Spectroscopy During Cardiopulmonary Bypass in a 6.8-Kg Infant With Complex Aortic Anatomy

Neonates and small infants with congenital heart disease and complex cardiac and vascular anatomy are particularly prone to episodes of complete or incomplete regional ischemia during cardiopulmonary bypass. These episodes may result either from inhomogeneous distribution of arterial blood flow via the aortic cannula or from impaired drainage of blood via the venous cannulae. However, techniques for continuous routine monitoring of regional perfusion in neonates or small infants undergoing cardiopulmonary bypass are extremely limited. Over recent years, transcranial near-infrared spectroscopy has become established as a useful technique for the non-invasive monitoring of cerebral oxygenation. Here we present a case in which simultaneous near-infrared spectroscopic monitoring of the oxygenation status in the brain and the right upper thigh revealed lower torso ischemia due to accidental cross-clamping of a hypoplastic descending aorta which would otherwise have been unnoticed. This shows that parallel near-infrared spectroscopy of the brain and the lower extremities may represent a novel non-invasive monitoring technique to ensure adequate cerebral and extracerebral perfusion during cardiopulmonary bypass.