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

Abdominal near-infrared spectroscopy in preterm infants: a comparison of splanchnic oxygen saturation measurements at two abdominal locations

BACKGROUND

Splanchnic tissue oxygenation monitoring has been performed at both the liver and the infra-umbilical regions. It is unknown whether these measurements could be substituted one for the other when interpreting splanchnic oxygenation since they have not been measured simultaneously before.

AIMS

To evaluate the feasibility and safety of liver and infra-umbilical near-infrared spectroscopy (NIRS) monitoring in preterm infants with suspected necrotizing enterocolitis (NEC) and to assess the correlation and agreement between NIRS measurements performed simultaneously at the two abdominal locations.

STUDY DESIGN AND SUBJECTS

This study was part of a prospective observational cohort study. Preterm infants who were suspected of NEC or who had been diagnosed with NEC were included.

OUTCOME MEASURES

Liver oxygen saturation and infra-umbilical oxygen saturation were monitored simultaneously and continuously for 48h by NIRS.

RESULTS

NIRS monitoring was performed in 20 out of 24 infants for the entire 48-hour study period. No adverse effects were observed. Values of liver and infra-umbilical oxygen saturation correlated weakly (Spearman's rho=0.244, P<.001). On the Bland-Altman plot liver oxygen saturation was higher than infra-umbilical oxygen saturation (mean difference 6.6%, SD 22.5%).

CONCLUSIONS

Using NIRS as method for monitoring oxygen saturation simultaneously in both the liver and infra-umbilical regions is safe and feasible. Additionally, we demonstrated that values of liver and infra-umbilical oxygen saturation cannot be randomly substituted one for the other for the purpose of assessing splanchnic oxygenation.

Cerebral oximetry in cardiac anesthesia

Cerebral oximetry based on near-infrared spectroscopy (NIRS) is increasingly used during the perioperative period of cardiovascular operations. It is a noninvasive technology that can monitor the regional oxygen saturation of the frontal cortex. Current literature indicates that it can stratify patients preoperatively according their risk. Intraoperatively, it provides continuous information about brain oxygenation and allows the use of brain as sentinel organ indexing overall organ perfusion and injury. This review focuses on the clinical validity and applicability of this monitor for cardiac surgical patients.

Splanchnic oxygen saturation immediately after weaning from cardiopulmonary bypass can predict early postoperative outcomes in children undergoing congenital heart surgery

This study compared the abilities of cerebral, renal, and splanchnic regional oxygen saturation (rSO2) immediately after weaning from cardiopulmonary bypass (CPB) to predict early postoperative outcomes for children undergoing congenital heart surgery. The study enrolled 73 children (ages 0.1-72 months) undergoing corrective or palliative cardiac surgery requiring CPB. Laboratory and hemodynamic variables were analyzed at the time of successful weaning from CPB. Using near-infrared spectroscopy, cerebral, renal, and splanchnic rSO2 values were obtained simultaneously. Early postoperative outcome measures included the maximum vasoactive inotropic score (VIS(max)) during the first 36 postoperative hours, the duration of mechanical ventilation, and the postoperative hospital length of stay. In the univariate analysis, cerebral, renal, and splanchnic rSO2 values correlated significantly with early postoperative outcomes. However, splanchnic rSO2 was the only independent factor predicting VIS(max) (β = -0.302, P = 0.021), duration of mechanical ventilation (β = -0.390, P = 0.002), and postoperative hospital length of stay (β = -0.340, P = 0.001) by multivariate analyses. Splanchnic rSO2 had a larger receiver operating characteristic area under the curve (AUC) for determining high VIS(max), prolonged mechanical ventilation, and longer postoperative hospital stay (AUC 0.775, 0.792, and 0.776, respectively) than cerebral (AUC 0.630, 0.638, and 0.632, respectively) and renal (AUC 0.703, 0.716, and 0.715, respectively) rSO2. After weaning from CPB, splanchnic rSO2 may be superior to rSO2 measured from brain and kidney in predicting an increased requirement for vasoactive inotropic support, a prolonged mechanical ventilation, and a longer postoperative hospital stay for children.

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

The safety of anesthesia has improved greatly in the past three decades. Standard perioperative monitoring, including pulse oximetry, has practically eliminated unrecognized arterial hypoxia as a cause for perioperative injury. However, most anesthesia-related cardiac arrests in children are now cardiovascular in origin, and standard monitoring is unable to detect many circulatory abnormalities. Near-infrared spectroscopy provides noninvasive continuous access to the venous side of regional circulations that can approximate organ-specific and global measures to facilitate the detection of circulatory abnormalities and drive goal-directed interventions to reduce end-organ ischemic injury.

Temporary atrial pacing for cardiac output after pediatric cardiac surgery

Pediatric cardiothoracic surgery is often associated with low cardiac output in the postoperative period. This study sought to determine whether increasing heart rate via temporary atrial pacing is beneficial in augmenting cardiac output. Patients younger than 18 years who underwent cardiothoracic surgery and had no perioperative arrhythmias were eligible for the study. Patients not paced postoperatively were atrial paced at a rate of 15 % above the intrinsic sinus rate (not to exceed 170 beats per minute, less for older patients) for 15 min. Patients paced for cardiac output postoperatively had their pacemakers paused for 15 min. Markers of cardiac output were measured before and after the intervention. Of the 60 patients who consented to participate, 30 completed the study. Failure to complete the study was due to tachycardia (n = 13), lack of pacing wires (n = 7), junctional rhythm (n = 4), advanced atrioventricular block (n = 3), and other cause (n = 3). Three patients were paced at baseline. There was no change in arteriovenous oxygen saturation difference, mean arterial blood pressure, central venous pressure, toe temperature, or lactate with atrial pacing. Atrial pacing was associated with a decrease in head and flank near-infrared spectroscopy (p = 0.01 and <0.01 respectively). Secondary analysis found an inverse relationship between mean arterial pressure response to pacing and bypass time. Temporary atrial pacing does not improve cardiac output after pediatric cardiac surgery and may be deleterious. Future research may identify subsets of patients who benefit from this strategy. Practitioners considering this strategy should carefully evaluate each patient's response to atrial pacing before its implementation.

Urinary biomarkers and renal near-infrared spectroscopy predict intensive care unit outcomes after cardiac surgery in infants younger than 6 months of age

OBJECTIVE

To assess the ability of urinary acute kidney injury biomarkers and renal near-infrared spectroscopy (NIRS) to predict outcomes in infants after surgery for congenital heart disease.

METHODS

Urinary levels of neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), and cystatin C were measured preoperatively and postoperatively in 49 infants younger than 6 months of age. Renal NIRS was monitored for the first 24 hours after surgery. A composite poor outcome was defined as death, the need for renal replacement therapy, prolonged time to first extubation, or prolonged intensive care unit length of stay.

RESULTS

Forty-two (86%) patients had acute kidney injury as indicated by at least Acute Kidney Injury Network/Kidney Disease: Improving Global Outcomes (AKIN/KDIGO) stage 1 criteria, and 17 (35%) patients had poor outcomes, including 3 deaths. With the exception of KIM-1, all biomarkers demonstrated significant increases within 24 hours postoperatively among patients with poor outcomes. Low levels of NGAL and IL-18 demonstrated high negative predictive values (91%) within 2 hours postoperatively. Poor outcome infants had greater cumulative time with NIRS saturations less than 50% (60 vs 1.5 minutes; P = .02) in the first 24 hours.

CONCLUSIONS

Within the first 24 hours after cardiopulmonary bypass, infants at increased risk for poor outcomes demonstrated elevated urinary NGAL, IL-18, and cystatin C and increased time with low NIRS saturations. These findings suggest that urinary biomarkers and renal NIRS may differentiate patients with good versus poor outcomes in the early postoperative period, which could assist clinicians when counseling families and inform the development of future clinical trials.

Near-infrared spectroscopy monitoring to predict postoperative renal insufficiency following repair of congenital heart disease

BACKGROUND

Infants undergoing repair or palliation of congenital heart disease are at risk of renal insufficiency. Development of renal insufficiency increases mortality. This project seeks to determine whether intra- and postoperative renal near-infrared spectroscopy (NIRS) monitoring can reliably predict renal insufficiency after cardiac surgery in infants.

METHODS

In this prospective, observational cohort study 48 patients undergoing repair or palliation of congenital heart disease in the first 6 months of life were studied intraoperatively and on postoperative day 1 and 2. The NIRS mean and nadir were recorded for the 3 time periods, as were urine output, fluid balance, and serum creatinine. Renal insufficiency was defined as rise in creatinine ≥40% from baseline or oliguria for >4 hours. Near-infrared spectroscopy data were compared to creatinine increase, oliguria, and fluid balance on postoperative day 0, 1, and 2 by regression analysis.

RESULTS

Mean renal regional saturation on postoperative day 1 has a strong correlation with increase in creatinine (P < .001 and R (2) = .6). Mean renal saturation less than 80% predicts renal insufficiency with a sensitivity of 100% and a specificity of 75% (P < .001).

CONCLUSION

Monitoring of intra- and postoperative renal regional saturation may provide an early, noninvasive marker of renal insufficiency after cardiac surgery in infants. This would be clinically significant if interventions to improve renal regional saturation prevent renal insufficiency.

Inferior vena cava oxygen saturation monitoring after the Norwood procedure

BACKGROUND

Superior vena cava oxygen saturation monitoring in the early postoperative period after the Norwood procedure (NP) has been associated with improved survival and decreased adverse events (AE). There is no data describing inferior vena cava saturation (Sivo2) monitoring after NP. We sought to investigate the utility of intermittent Sivo2 monitoring after NP and to assess the correlation of Sivo2 with renal near-infrared spectroscopy (rNIRS). We hypothesized failure to achieve Sivo2 greater than 45% within the first 4 hours after NP is predictive of AE, and that rNIRS correlates with Sivo2.

METHODS

A retrospective study of 26 consecutive NP patients who received postoperative management with Sivo2 monitoring according to a strict protocol was conducted. Primary outcome was AE, defined as cardiopulmonary resuscitation, extracorporeal membrane oxygenation, death before discharge, or residual surgical defects.

RESULTS

Ten (38%) patients had one or more AE; mortality was 23%. On admission to the cardiac intensive care unit, patients with AE had lower Sivo2 (45% ± 9.4% versus 62% ± 12.0%; p < 0.001) and lower rNIRS (56 ± 6.5 versus 77 ± 7.2; p < 0.001). At 4 hours, 90% of AE patients had an Sivo2 less than 45% versus 6% of non-AE patients. Both Sivo2 and rNIRS were highly predictive of AE: the area under the receiver-operating characteristic curve was greater than 0.86 and 0.95, respectively. Two hours after admission, an Sivo2 less than 45% predicted AE with a specificity of 93%, a sensitivity of 70%, and a positive predictive value of 82%. The Sivo2 was strongly correlated with rNIRS (r = 0.81).

CONCLUSIONS

Intermittent Sivo2 can be used to guide early postoperative NP management; rNIRS is an accurate continuous, noninvasive surrogate for Sivo2. An Sivo2 of less than 45% in the first 4 hours after the NP is predictive of AE.

A prospective assessment of renal oxygenation in children undergoing laparoscopy using near-infrared spectroscopy

BACKGROUND

This study was designed to determine whether a decrease in renal oxygenation occurs during CO2 pneumoperitoneum in children with normal renal function undergoing laparoscopy.

METHODS

Near infrared spectroscopy (NIRS) probes were applied to both the lateral flank (T10-L2) and lateral cerebral area of all patients with normal renal function undergoing a laparoscopic procedure. Information was recorded in 5-s intervals for 15-min before, during, and for 15-min after pneumoperitoneum insufflation and desufflation. Simultaneously, additional hemodynamic parameters (arterial saturation, mean arterial pressure, end tidal CO2, and urine output) were recorded every 5-min. Pneumoperitoneum pressures used were: 0-1 month old, <6 mmHg; 2-12 months old, <8 mmHg; 1-2 years old, <10 mmHg, and 2-8 years old, <12 mmHg. The lowest possible pressure was used to obtain adequate vision.

RESULTS

Twenty-nine patients were enrolled in the study. Renal regional oxygen saturation (rSO2) did not decrease significantly between baseline (preinsufflation), insufflation, and desufflation of the pneumoperitoneum (p = 0.343). Meta-analysis of this data demonstrated a pooled weighted difference of -1.4 (-3.5 to 0.54), confirming no significant change. A significant increase in cerebral rSO2 occurred during the insufflation period of the CO2 pneumoperitoneum (p = 0.001). Heart rate (F = 11.05; p < 0.001) and mean arterial pressure (MAP) (F = 19.2; p < 0.001) also increased significantly during the laparoscopy. No significant correlation was identified between fluid input and urine output during the laparoscopy (r = 0.012; p = 0.953).

CONCLUSIONS

Renal hypoxia does not occur during laparoscopic surgery in children if the minimum age-appropriate intra-abdominal pressures are used. Alternative causes must account for the oliguria and anuria demonstrated in children undergoing laparoscopy.

Anesthetic Considerations in Infants With Hypoplastic Left Heart Syndrome

Hypoplasia of the left ventricle is a congenital cardiac lesion that is almost universally fatal if left untreated. Six decades of improved diagnostic modalities, greater understanding of single ventricle physiology, and earlier surgical and palliative options have given many of these patients an opportunity of surviving well into adulthood. This review will summarize these advances and focus on the anesthetic implications of this challenging disease from diagnosis to beyond the first palliative surgery.

Does treatment of patent ductus arteriosus with cyclooxygenase inhibitors affect neonatal regional tissue oxygenation?

The effect of patent ductus arteriosus (PDA) treatment with cyclooxygenase (COX) inhibitors (indomethacin [INDO] and ibuprofen [IBU]) on regional oxygenation requires further clarification. The authors hypothesized that both INDO and IBU reduce regional tissue oxygenation in preterm neonates with PDA but that the risk is not uniform for different tissues and other factors may contribute. Regional cerebral (rSO(2-C)), renal (rSO(2-R)), and mesenteric (rSO(2-M)) tissue oxygenation measured by near-infrared spectroscopy and peripheral arterial oxygen saturation measured by pulse oximetry were recorded simultaneously before, during, and after treatment with the first dose of INDO or IBU in very preterm-born infants with PDA. Tissue-specific fractional oxygen extraction (FOE) was calculated using the rSO(2-C), rSO(2-R), rSO(2-M), and corresponding SpO(2) measurements. The findings showed a significant reduction in rSO(2-C), rSO(2-R), and rSO(2-M) and an increase in regional FOE after treatment with COX inhibitors in approximately one third of the 38 enrolled infants, which were associated with increased baseline regional tissue oxygen saturation (p < 0.01). However, the infants with posttreatment reduction of tissue oxygenation had significantly lower baseline rSO(2-C) (66.7 ± 8.1 vs 69.7 ± 8.1 %), rSO(2-R) (55.2 ± 10.8 vs 62.7 ± 11.8 %) and especially rSO(2-M) (37.8 ± 11.4 vs 46.7 ± 16.0 %) than the neonates with unchanged or increased tissue oxygenation. The two groups did not differ in terms of the risk for posttreatment reduction in regional tissue oxygenation with respect to either INDO or IBU treatment and their respective blood levels. Treatment of PDA with either INDO or IBU is associated with a 30-40 % risk for a reduction in regional tissue oxygenation, which is more pronounced in mesenteric tissue than in cerebral or renal tissue. Despite the inconsistency, reduction of regional tissue oxygenation in preterm infants with PDA is more likely associated with the administration of INDO than with the administration of IBU.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

New technologies in pediatric anesthesia

This article reviews potential pediatric applications of 3 new technologies. (1) Pulse oximetry-based hemoglobin determination: Hemoglobin determination using spectrophotometric methods recently has been introduced in adults with varied success. This non-invasive and continuous technology may avoid venipuncture and unnecessary transfusion in children undergoing surgery with major blood loss, premature infants undergoing unexpected and complicated emergency surgery, and children with chronic illness. (2) Continuous cardiac output monitoring: In adults, advanced hemodynamic monitoring such as continuous cardiac output monitoring has been associated with better surgical outcomes. Although it remains unknown whether similar results are applicable to children, current technology enables the monitoring of cardiac output non-invasively and continuously in pediatric patients. It may be important to integrate the data about cardiac output with other information to facilitate therapeutic interventions. (3) Anesthesia information management systems: Although perioperative electronic anesthesia information management systems are gaining popularity in operating rooms, their potential functions may not be fully appreciated. With advances in information technology, anesthesia information management systems may facilitate bedside clinical decisions, administrative needs, and research in the perioperative setting.

Change in regional (somatic) near-infrared spectroscopy is not a useful indicator of clinically detectable low cardiac output in children after surgery for congenital heart defects

OBJECTIVE

Near-infrared spectroscopy correlation with low cardiac output has not been validated. Our objective was to determine role of splanchnic and/or renal oxygenation monitoring using near-infrared spectroscopy for detection of low cardiac output in children after surgery for congenital heart defects.

DESIGN

Prospective observational study.

SETTING

Pediatric intensive care unit of a tertiary care teaching hospital.

PATIENTS

Children admitted to the pediatric intensive care unit after surgery for congenital heart defects.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We hypothesized that splanchnic and/or renal hypoxemia detected by near-infrared spectroscopy is a marker of low cardiac output after pediatric cardiac surgery. Patients admitted after cardiac surgery to the pediatric intensive care unit over a 10-month period underwent serial splanchnic and renal near-infrared spectroscopy measurements until extubation. Baseline near-infrared spectroscopy values were recorded in the first postoperative hour. A near-infrared spectroscopy event was a priori defined as ≥20% drop in splanchnic and/or renal oxygen saturation from baseline during any hour of the study. Low cardiac output was defined as metabolic acidosis (pH <7.25, lactate >2 mmol/L, or base excess ≤-5), oliguria (urine output <1 mL/kg/hr), or escalation of inotropic support. Receiver operating characteristic analysis was performed using near-infrared spectroscopy event as a diagnostic test for low cardiac output. Twenty children were enrolled: median age was 5 months; median Risk Adjustment for Congenital Heart Surgery category was 3 (1-6); median bypass and cross-clamp times were 120 mins (45-300 mins) and 88 mins (17-157 mins), respectively. Thirty-one episodes of low cardiac output and 273 near-infrared spectroscopy events were observed in 17 patients. The sensitivity and specificity of a near-infrared spectroscopy event as an indicator of low cardiac output were 48% (30%-66%) and 67% (64%-70%), respectively. On receiver operating characteristic analysis, neither splanchnic nor renal near-infrared spectroscopy event had a significant area under the curve for prediction of low cardiac output (area under the curve: splanchnic 0.45 [95% confidence interval 0.30-0.60], renal 0.51 [95% confidence interval 0.37-0.65]).

CONCLUSIONS

Splanchnic and/or renal hypoxemia as detected by near-infrared spectroscopy may not be an accurate indicator of low cardiac output after surgery for congenital heart defects.

Monitoring tissue oxygenation by near infrared spectroscopy (NIRS): background and current applications

Conventional cardiovascular monitoring may not detect tissue hypoxia, and conventional cardiovascular support aiming at global hemodynamics may not restore tissue oxygenation. NIRS offers non-invasive online monitoring of tissue oxygenation in a wide range of clinical scenarios. NIRS monitoring is commonly used to measure cerebral oxygenation (rSO(2)), e.g. during cardiac surgery. In this review, we will show that tissue hypoxia occurs frequently in the perioperative setting, particularly in cardiac surgery. Therefore, measuring and obtaining adequate tissue oxygenation may prevent (postoperative) complications and may thus be cost-effective. NIRS monitoring may also be used to detect tissue hypoxia in (prehospital) emergency settings, where it has prognostic significance and enables monitoring of therapeutic interventions, particularly in patients with trauma. However, optimal therapeutic agents and strategies for augmenting tissue oxygenation have yet to be determined.

Measurement of gastric-to-end-tidal carbon dioxide difference in neonates requiring intensive care

OBJECTIVE

Gastric-arterial partial CO(2) pressure gap (P(g-)(a)CO(2) gap) measured by gastric tonometry may detect the disturbance of splanchnic perfusion. As in the neonatal age it is very difficult to follow up the circulatory condition with frequent acid-base examinations, we wanted to compare the P(g-)(a)CO(2) gap with an alternative gap of P(g)CO(2) - end-tidal carbon dioxide (P(g)(-)(ET)CO(2) gap).

METHODS

A prospective study was performed on ventilated neonates requiring intensive therapy (n = 44, weight: 1813 ± 977 g). P(ET)CO(2) and P(g)CO(2) were measured with a side stream capnograph. We applied a newly developed gastric tonometric probe. Patients were divided into two groups: Group 1 of patients in stable condition (n = 35) and Group 2 of patients with severe condition (i.e. Clinical Risk Index for Babies [CRIB] score higher than 10; n = 9). For main statistical analysis a mixed model repeated measurements ANOVA, Bland-Altman analysis were applied.

RESULTS

P(g)(-)(ET)CO(2) gap was higher than P(g-)(a)CO(2) gap (11.40 ± 7.79 versus 3.63 ± 7.98 mmHg, p < 0.01). Both gaps were higher in Group 2 (8.71 ± 10.89 and 18.27 ± 10.49 versus 2.53 ± 6.78 and 9.92 ± 6.22 mmHg, p < 0.01 and p < 0.05). Bland-Altman analysis of the two gaps showed an acceptable correspondence.

CONCLUSIONS

P(g)(-)(ET)CO(2) gap may be used as a method for continuous estimation of splanchnic perfusion and a prognostic index also in critically ill neonates. However, the P(g-)(a)CO(2) gap should not be abandoned.

Hypoplastic left heart syndrome: current considerations and expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Understanding near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) is a noninvasive technique that monitors regional tissue oxygenation reflecting perfusion status. Near-infrared spectroscopy has the ability to continuously and simultaneously monitor tissue perfusion in different organ systems at the bedside without interrupting routine care. Research has demonstrated its benefit in monitoring cerebral, intestinal, and renal perfusion to detect potential ischemic episodes. Near-infrared spectroscopy can augment current physiologic monitoring to increase awareness of abnormal perfusion status in the preterm population and potentially reduce risks associated with many diseases that may lead to ischemic injury. This article provides an overview describing NIRS technology and function, its current use in neonatology, and pertinent research findings illustrating its benefit in the neonatal population. Near-infrared spectroscopy may evolve into an important diagnostic and prognostic tool for neonatal treatment and outcome.

Perioperative management of the pediatric cardiac transplantation patient

OPINION STATEMENT

The major diagnoses carried by children undergoing cardiac transplantation worldwide are congenital heart defects, cardiomyopathies, and retransplantation. The leading diagnosis in infancy is congenital heart disease, whereas cardiomyopathy predominates in older children. In view of this wide spectrum of diagnoses, the perioperative management of these children requires medical, interventional, and surgical expertise in treatment of complex congenital heart defects, end-stage heart failure, and cardiac transplantation. According to the Pediatric Heart Transplantation Survey database, the majority of children listed for cardiac transplantation eventually require higher levels of cardiac support before transplantation. The team caring for these children should be prepared to escalate support in a timely fashion in order to avoid end-organ dysfunction or a catastrophic event that will remove the patient from the cardiac transplantation list. The first step is advanced hemodynamic monitoring in a specialized pediatric cardiac intensive care unit and initiation of inotropic support. Further escalation of care should be based on careful analysis of the hemodynamic profile, end-organ function, and biochemical markers of perfusion and myocardial stress. A patient who continues to deteriorate in spite of inotropic support requires positive pressure ventilation, and if deterioration continues, mechanical circulatory support is initiated. Cardiac transplantation is a challenging operation, and even more so in children with complex congenital heart defects. The abnormal cardiovascular anatomy requires planning and anticipation of possible pitfalls as hypoplasia of the aortic arch, abnormal pulmonary arteries, and abnormal systemic and pulmonary venous connections. The time required to remove adhesions in children with prior cardiac operations increases the ischemic time of the graft and the risk of primary graft dysfunction. Assessment of pulmonary vascular resistance in children with congenital heart defects is problematic, and even children with a normal transpulmonary gradient and pulmonary vascular resistance are at increased risk of postoperative pulmonary hypertension and right ventricular graft failure. The postoperative course is directly linked to the patient's preoperative physical condition and perioperative course. The induction of immunosuppression and the use of plasmapheresis in children with a positive cross-match may lead to further hemodynamic compromise. If severe primary graft dysfunction evolves, early initiation of extracorporeal membranous oxygenator is indicated to avoid irreversible end-organ dysfunction.

Mesentric oxygen saturations in premature twins with and without necrotizing enterocolitis

OBJECTIVE

To report the use of near-infrared spectroscopic monitoring to recognize mesenteric oxygen desaturations in a preterm neonate with necrotizing enterocolitis as well as the demonstration of reassuring mesenteric tissue perfusion in a twin sibling with an uncomplicated course.

DESIGN

Case report.

SETTING

Neonatal intensive care unit in a tertiary care children's hospital.

PATIENTS

A 12-day-old growth-restricted preterm female twin with necrotizing enterocolitis and her twin who did not develop disease.

INTERVENTIONS

In the twin with symptoms of necrotizing enterocolitis, reduction in the mesenteric saturations was recorded in the injured bowel tissue as later confirmed during surgery. After resection of the ischemic bowel, mesenteric saturations returned to values comparable to those measured in the healthy twin. Reduced saturations were not observed in the asymptomatic twin.

CONCLUSIONS

The use of optical oximetry to monitor mesenteric tissue saturation may provide a measure of bowel perfusion that could enhance clinical management in at-risk preterm neonates.

Near-infrared spectroscopy as a hemodynamic monitor in critical illness

BACKGROUND

Near-infrared spectroscopy has moved from a research tool to a widely used clinical monitor in the critically ill pediatric patient over the last decade. The physiological and clinical evidence supporting this technology in practice is reviewed here.

METHODOLOGY

A search of MEDLINE and PubMed was conducted to find validation studies, controlled trials, and other reports of near-infrared spectroscopy use in children and adults in the clinical setting. Guidelines published by the American Heart Association, the American Academy of Pediatrics, and the International Liaison Committee on Resuscitation were reviewed including further review of references cited.

RESULTS

The biophysical properties of near-infrared spectroscopy devices allow measurement of capillary-venous oxyhemoglobin saturation in tissues a few centimeters beneath the surface sensor with validated accuracy in neonates, infants, and small patients. The biologic basis for the relationship of capillary-venous oxyhemoglobin saturation to cerebral injury has been described in animal and human studies. Normal ranges for cerebral and somatic capillary-venous oxyhemoglobin saturation have been described for normal newborns and infants and children with congenital heart disease and other disease states. The capillary-venous oxyhemoglobin saturation from both cerebral and somatic regions has been used to estimate mixed venous saturation and to predict biochemical shock, multiorgan dysfunction, and mortality in different populations. The relationship of cerebral capillary-venous oxyhemoglobin saturation to neuroimaging and functional assessment of outcome is limited but ongoing. Although there are numerous conflicting reports in small populations, expert opinion would suggest that special use may exist for near-infrared spectroscopy in patients with complex circulatory anatomy, with extremes of physiology, and in whom extended noninvasive monitoring is useful.

CONCLUSIONS

Class II, level B evidence supports the conclusion that near-infrared spectroscopy offers a favorable risk-benefit profile and can be effective and beneficial as a hemodynamic monitor for the care of critically patients.

Regional tissue oxygenation in preterm born infants in association with echocardiographically significant patent ductus arteriosus

OBJECTIVE

To analyze the levels of regional tissue oxygenation in preterm infants in association with echocardiographically significant patent ductus arteriosus (PDA).

STUDY DESIGN

Preterm infants with gestational age less than 32 week were enrolled before the first dose of the pharmacological treatment for the PDA. Non-invasive near-infrared spectroscopy (NIRS) technology was utilized to measure cerebral (rSO(2)-C), renal (rSO(2)-R) and mesenteric (rSO(2-M)) tissue oxygenation for approximately 60 min. Regional fractional oxygen extraction (FOE) was calculated using simultaneously measured arterial saturation (SaO(2)). We analyzed regional tissue oxygenation and oxygen extraction, hemodynamic parameters, and demographic and clinical information in association with the size of the PDA (moderate vs large).

RESULT

Among the 38 enrolled infants, the majority were diagnosed with a large (63.2%, n=24) and the rest with a moderate-sized PDA. Infants with large and moderate PDA were comparable in terms of gestational age, study age and weight, mode of delivery and hemodynamic parameters. A significantly higher proportion of infants with a moderate PDA were mechanically ventilated as compared with those with a large PDA. We found no significant differences in the rSO(2)-C and rSO(2)-R, irrespective of the type of respiratory support. However, in infants with a large PDA on continuous nasal positive airway pressure (NCPAP), the rSO(2)-M was lower and mesenteric FOE was higher than that in mechanically ventilated neonates with a large PDA, and in those with moderate PDA irrespective of the type of respiratory support.

CONCLUSION

The PDA size did not affect cerebral and renal tissue oxygenation, but the mesenteric tissue oxygenation was decreased in infants with a large PDA on NCPAP.

Perioperative management of low birth weight infants for open-heart surgery

Infants of birth weight ≤2500 g are termed low birth weight (LBW). These children often have considerable morbidity from prematurity and intra-uterine growth restriction. Additionally, LBW infants have increased risk for cardiac and noncardiac congenital anomalies and may require surgery. Primary rather than palliative surgical repair of cardiac lesions has been preferred in recent years. However, LBW remains a risk factor for increased mortality and morbidity after open-heart surgery (OHS). There is a paucity of information about the anesthetic challenges presented by LBW infants undergoing OHS. This review summarizes the perioperative issues of relevance to anesthesiologists who manage these high-risk patients. Emphasis is placed on management concerns that are unique to LBW infants. Retrospective data from the authors' institution are provided for those aspects of anesthetic care that lack published studies. Successful outcome often requires substantial hospital resources and collaborative multi-disciplinary effort.

Computed tomography scan measurement of abdominal wall thickness for application of near-infrared spectroscopy probes to monitor regional oxygen saturation index of gastrointestinal and renal circulations in children

OBJECTIVES

To measure abdominal wall thickness to determine the depth at which the renal vascular bed and mesenteric vascular bed are located, and to determine the appropriate site for placement of near-infrared spectroscopy probes for accurate monitoring regional oxygen saturation index in children.

DESIGN

Abdominal computerized tomography scans in children were used to measure the abdominal wall thickness and to ascertain the location of kidneys.

SETTING

Tertiary care children's hospital.

SUBJECTS

Children 0-18 yrs of age; n = 38.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The main mass of the kidneys is located between vertebral levels T12 and L2 on both sides. The left kidney is located about a half-vertebral length higher than the right kidney. Posterior abdominal wall thickness ranged from 6.6 to 115.8 mm (median, 22.1 mm). Posterolateral abdominal wall thickness ranged from 6.7 to 114.5 mm (median, 19.6 mm). Anterior abdominal wall thickness in the supraumbilical level ranged from 3.5 to 62.9 mm (median, 16.0 mm). All abdominal wall thicknesses correlated better with weight of the subjects than their age.

CONCLUSION

Abdominal wall thickness potentially exceeds the sampling depth of currently used near-infrared spectroscopy probes above a certain body size. Application of current near-infrared spectroscopy probes and design of future probes should consider patient size variations in the pediatric population.

[Diagnosis and management of acute mesenteric ischemia]

The prevalence of significant splanchnic arterial stenoses is increasing, but remains mostly asymptomatic due to abundant collateral circulation. Acute insufficiency of mesenteric arterial blood flow accounts for 60 to 70% of cases of mesenteric ischemia and results mostly from a superior mesenteric embolus. Despite major advances have been achieved in understanding the pathogenic mechanisms of bowel ischemia, its prognosis remains dismal with mortality rates about 60%. The diagnosis of acute mesenteric ischemia depends upon a high clinical suspicion, especially in patients with known risk factors. Rapid diagnosis is essential to prevent intestinal infarction. However, early signs and symptoms of mesenteric ischemia are non specific, and definitive diagnosis often requires radiologic examinations. Early and liberal implementation of angiography has been the major advance over the past 30 years which allowed increasing diagnostic accuracy of acute mesenteric ischemia. CT and MR-based angiographic techniques have emerged as alternatives less invasive and more accurate to analyse splanchnic vessels and evaluate bowel infarction. The goal of treatment of patients with acute mesenteric ischemia is to restore intestinal oxygenation as quickly as possible after initial management that includes rapid hemodynamic monitoring and support. Surgery should not be delayed in patients suspected of having intestinal necrosis.

Correlations between hemodynamic, oxygenation and tissue perfusion parameters during asphyxial cardiac arrest and resuscitation in a pediatric animal model

AIM

To analyze the correlations between hemodynamic, oxygenation and tissue perfusion values in an infant animal model of asphyctic cardiac arrest (ACA).

METHODS

A prospective observational animal study was performed in seventy one, two month-old piglets. CA was induced by removal of mechanical ventilation and was followed by advanced life support after at least 10 min. Correlations between hemodynamic [heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), stroke volume index (SVI) and intrathoracic blood index (ITBI) measured by PiCCO method], blood gas values (arterial and central venous saturation), and tissue perfusion values [intramucosal gastric pH (pHi), and tissue oxygenation (cerebral and renal saturation)] were analyzed during asphyxia, resuscitation and after return of spontaneous circulation (ROSC).

RESULTS

Among global hemodynamic parameters, the only moderate significant correlation observed was between CI and ITBI (r = .551). Among tissue oxygenation/perfusion values, a moderate to good significant correlation (r = .460-.763) between arterial oxygen saturation, central venous, renal and cerebral oxygen saturation was observed. Lactic acid, potassium (K) and pHi were correlated (r = .561-.639), but no correlation was found between them and tissue oxygenation parameters. Global hemodynamic parameters (CI, HR, MAP) did not correlate with renal and cerebral saturations and tissue perfusion parameters.

CONCLUSIONS

During ACA and after ROSC global hemodynamic parameters do not correlate with oxygenation and tissue perfusion values. Additional studies which assess the potential usefulness of tissue oxygenation/perfusion parameters during cardiac arrest and ROSC are needed.

Objective assessment of cardiac output in infants after cardiac surgery

An accurate measurement of cardiac performance in infants after cardiopulmonary bypass has long been considered to be an important part of postoperative management. To be useful in clinical decision making, such measurements should ideally be reproducible, non invasive and accurately reflect tissue perfusion and oxygen delivery. Historically, we have relied on intermittent measurements of cardiac output using indicator dilution methods; and more recently, technologies that use pulse contour analysis, bio-impedance, or Doppler methodology. These all have the same shortcoming, that they provide a number that the information as to whether it provides adequate tissue perfusion. There is increasing emphasis being placed on the measurement of oxygen delivery either by mixed venous oxygen saturation and serum lactate, which are important markers of the adequacy of organ perfusion; and relating this to outcome, the development of organ dysfunction and length of ICU stay.

Hemodynamic, respiratory, and perfusion parameters during asphyxia, resuscitation, and post-resuscitation in a pediatric model of cardiac arrest

PURPOSE

To analyze the evolution of hemodynamic, respiratory, and tissue perfusion parameters in an infant animal model of asphyxial cardiac arrest (CA).

METHODS

This was a secondary analysis of a prospective observational study conducted at a laboratory research department of a university hospital. Seventy-one, 2-month-old piglets were studied. CA was induced by removal of mechanical ventilation. Cardiopulmonary resuscitation (CPR) was performed by means of manual external chest compressions, mechanical ventilation, epinephrine and/or terlipressin intravenous administration.

RESULTS

The evolution of hemodynamic (heart rate, blood pressure, cardiac index), respiratory (end-tidal CO(2), blood gas analysis), and tissue perfusion (intramucosal gastric pH, central, cerebral, and renal hemoglobin saturation) parameters was analyzed during three periods: asphyxia, CPR, and after return of spontaneous circulation (ROSC). During asphyxia, a severe arterial and tissue hypoxia with hypercapnia and lactic acidosis quickly developed. Bradycardia, hypotension, and increasing of systemic vascular resistances and pulmonary arterial pressure were also observed. During CPR, arterial, cerebral, and tissue oxygenation were low in spite of ventilation with oxygen 100%. After ROSC a rapid restoration of hemodynamic and respiratory parameters was observed. However, 30 min after ROSC, lactic acidosis and low intramucosal gastric pH persisted.

CONCLUSIONS

Asphyxia leads to sudden hypoxia and hypercapnia with tissue hypoxia and progressive bradycardia. Standard CPR is not able to maintain an adequate tissue oxygenation during CPR in this animal model. When ROSC is achieved, a rapid restoration of the normal values of general hemodynamic and respiratory parameters is observed, although lactic acidosis and splanchnic hypoperfusion persist in time.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Near infrared spectroscopy (NIRS) should not be standard of care for postoperative management

Neurologic dysfunction is a problem in patients with congenital heart disease. Near infrared spectroscopy (NIRS) may provide a real-time window into cerebral oxygenation. Enthusiasm for NIRS has increased in hopes of reducing neurologic dysfunction. However, potential gains need to be evaluated relative to cost and potential detriment of intervention before routine implementation. Responding to data in ways that seem intuitively beneficial can be risky when the long-term impact is unknown. Many centers, and even entire countries, have adopted NIRS as standard of care. Available data suggest that multimodality monitoring, including NIRS, may be a useful adjunct. However, the current literature on the use of NIRS alone does not demonstrate improvement in neurologic outcome. Data correlating NIRS findings with indirect measures of neurologic outcome or mortality are limited. Although NIRS has promise for measuring regional tissue oxygen saturation, the lack of data demonstrating improved outcomes limits the support for wide-spread implementation.

Cerebral and somatic near-infrared spectroscopy in normal newborns

PURPOSE

Near-infrared spectroscopy has been used increasingly in the pediatric population as a continuous, noninvasive indicator of trends in organ perfusion and oxygenation. We studied healthy newborn babies to establish normal values during rest and feeding.

METHODS

Forty-four term newborns were recruited. Near-infrared spectroscopy probes were placed on the forehead and over the right kidney to record cerebral (rSO(2)C) and renal-somatic (rSO(2)R) regional oxyhemoglobin saturation. Readings were collected continuously for 2 to 8 hours, spanning 1 to 3 feeding episodes.

RESULTS

Data were available on 26 patients, with an average age of 44 +/- 28 hours. The overall average rSO(2)C was 77.9% +/- 8.5%, rSO(2)R was 86.8% +/- 8.1%, and DeltarSO(2)RC (somatic-cerebral rSO(2) difference) was 8.9% +/- 9.4%. During feeding, rSO(2)C was minimally decreased (78.6% +/- 8.4% versus 78.0% +/- 9.0%, P = .023), rSO(2)R did not change (87.0% +/- 8.1% versus 87.3% +/- 8.0%, P = .31), and DeltarSO(2)RC was minimally increased (8.5% +/- 9.5% versus 9.2% +/- 9.1%, P = .014). Over the first 120 hours after birth, average rSO(2)C decreased (P < .01), and rSO(2)R remained relatively unchanged.

CONCLUSIONS

Clinical utility of near-infrared spectroscopy was partly limited by lack of normative data. These data demonstrate that regional oxygen extraction is greater across cerebral than across renal-somatic beds in normal newborns. Healthy newborns do not have clinically significant changes in organ oxygenation with feeding.

Near infrared spectroscopy in children at high risk of low perfusion

PURPOSE OF REVIEW

Tissue oximetry has been suggested as a noninvasive tool to continuously monitor and detect states of low body perfusion. This review summarizes recent developments and available data on the use of near infrared spectroscopy (NIRS) in children at risk for low perfusion.

RECENT FINDINGS

During states of low cardiac output, cerebral blood flow and thus cerebral NIRS may be better preserved than in somatic tissue sites. Consequently, sites other than the frontal cerebral cortex have been investigated for a possible correlation with invasive measures of systemic perfusion and oxygenation (e.g. abdomen, flank, and muscle). The abdominal site seems preferable to the flank site NIRS (kidney region) application. In order to increase the sensitivity, specificity, and positive predictive value of tissue oximetry to detect systemic hypoperfusion, multisite NIRS such as a combination of cerebral and somatic site NIRS has been suggested. NIRS has also been used to assess systemic perfusion in patients undergoing first-stage palliation for hypoplastic left heart syndrome.

SUMMARY

Despite shortcomings in the ability of NIRS technology to accurately reflect validated and directly measured parameters of systemic oxygen delivery and blood flow, NIRS can certainly assist in the detection of low-flow states (low cardiac output). Large, randomized, prospective studies with well defined outcome parameters are still missing and warranted in order to clearly define the role of NIRS in children at risk for low perfusion.

Correlation between muscle oxygenation and compartment pressures in acute compartment syndrome of the leg

BACKGROUND

Near-infrared spectroscopy estimates soft-tissue oxygenation approximately 2 to 3 cm below the skin. The purpose of the present study was to evaluate muscle oxygenation in the setting of an acute compartment syndrome of the leg and to determine if near-infrared spectroscopy is capable of detecting perfusion deficits.

METHODS

Fourteen patients with unilateral lower extremity trauma were enrolled after the diagnosis of an acute compartment syndrome was made clinically and confirmed with intracompartmental pressure measurements. Lower extremity muscle compartments were evaluated with near-infrared spectroscopy, and near-infrared spectroscopy values of the uninjured, contralateral leg of each patient were used as internal reference values. The compartment perfusion gradient was calculated as the diastolic blood pressure minus the intracompartmental pressure.

RESULTS

Intracompartmental pressures ranged from 21 to 176 mm Hg (mean, 79 mm Hg) and exceeded 30 mm Hg in all compartments but two (both in the same patient). Thirty-eight compartments had a perfusion gradient of < or = 10 mm Hg (indicating ischemia). Among ischemic compartments, near-infrared spectroscopy values in the anterior, lateral, deep posterior, and superficial posterior compartments of the injured limbs were decreased by an average 10.1%, 10.1%, 9.4%, and 16.3% in comparison with the corresponding compartments of the uninjured leg. Differences in near-infrared spectroscopy values (the near-infrared spectroscopy value for the injured leg minus the near-infrared spectroscopy value for the uninjured leg) were positively correlated with compartment perfusion gradient within each compartment (r = 0.82, 0.65, 0.67, and 0.62, for the anterior, lateral, deep posterior, and superficial posterior compartments, respectively; p < 0.05 for all).

CONCLUSIONS

Normalized near-infrared spectroscopy values decrease significantly with decreasing lower limb perfusion pressures. Near-infrared spectroscopy may be capable of differentiating between injured patients with and without an acute compartment syndrome.

Near-infrared spectroscopy as an index of brain and tissue oxygenation

Continuous real-time monitoring of the adequacy of cerebral perfusion can provide important therapeutic information in a variety of clinical settings. The current clinical availability of several non-invasive near-infrared spectroscopy (NIRS)-based cerebral oximetry devices represents a potentially important development for the detection of cerebral ischaemia. In addition, a number of preliminary studies have reported on the application of cerebral oximetry sensors to other tissue beds including splanchnic, renal, and spinal cord. This review provides a synopsis of the mode of operation, current limitations and confounders, clinical applications, and potential future uses of such NIRS devices.

Pro: NIRS is "standard of care" for postoperative management

Successful postoperative management depends on early detection and correction of circulatory insufficiency. Global cardiac output and oxygen delivery must be adequate and distributed appropriately to meet metabolic demands to prevent the development of multi-organ dysfunction, morbidity, and death. Decreased cardiac output during the postoperative period is common, but circulatory assessment using standard monitoring provides inadequate information to reliably detect low cardiac output syndrome or effectively guide therapy. Goal-directed therapy using invasive estimates of global oxygen supply-demand balance (SvO2) has been shown to improve survival among patients in shock states. Near infrared spectroscopy (NIRS) is a noninvasive assessment of regional oxygen supply-demand balance. Multiple prospective observational studies have shown that NIRS-derived measures of systemic oxygen balance correlate with global circulatory measures, including SvO2 and biochemical indicators of shock. Additionally, NIRS has been shown in multiple prospective observational studies to identify circulatory inadequacy in specific organ systems, such as the brain, kidney, and gut. NIRS provides continuous, non-invasive measures that are suitable targets for goal-directed therapy to treat deficiencies in global and regional perfusion and should be standard of care.

Near-infrared spectroscopy in lower extremity trauma

BACKGROUND

Near-infrared spectroscopy measures the percentage of hemoglobin oxygen saturation in the microcirculation of tissue up to 3 cm below the skin. The purpose of this study was to describe the measurable response of normal tissue oxygenation in the leg after acute trauma with use of this technique.

METHODS

Twenty-six patients with acute unilateral tibial fractures and twenty-five uninjured volunteer control subjects were enrolled. Near-infrared spectroscopy measurements were obtained for both legs in all four compartments: anterior, lateral, deep posterior, and superficial posterior. The twenty-six injured legs were compared with twenty-five uninjured legs (randomly selected) of the volunteer control group, with the contralateral limb in each patient serving as an internal control.

RESULTS

The mean tissue oxygenation for each compartment in the injured legs was 69% (anterior), 70% (lateral), 74% (deep posterior), and 70% (superficial posterior). In the control (uninjured) legs, the average tissue oxygenation percentage in each compartment was 54%, 55%, 60%, and 57%, respectively. Repeated-measures analysis revealed that near-infrared spectroscopy values averaged 15.4 percentage points (95% confidence interval, 12.2 to 18.6 percentage points) higher for injured legs than for uninjured legs, controlling for the value of the contralateral limb (p < 0.0001).

CONCLUSIONS

Tibial fracture produces a predictable increase in tissue oxygenation as measured by near-infrared spectroscopy. The corresponding compartment of the contralateral leg can provide strong utility as an internal control value when evaluating the hyperemic response to injury.

Splanchnic tissue oxygenation, but not brain tissue oxygenation, increases after feeds in stable preterm neonates tolerating full bolus orogastric feeding

OBJECTIVE

The objective of this prospective, observational study was to test the hypothesis that tissue oxygenation in the splanchnic bed compared with tissue oxygenation in the cerebral circulation changes after feeding in preterm neonates who are tolerating full bolus orogastric feeds.

STUDY DESIGN

Clinically stable premature neonates with postmenstrual age between 32 and 35(6/7) weeks who were tolerating full bolus feedings were studied before feeding and 1 h after feeding using near-infrared spectroscopy. The ratio of oxygenated to reduced hemoglobin (tissue oxygenation index, TOI) in the splanchnic circulation bed was divided by the TOI in the cerebral circulation, thereby yielding the cerebro-splanchnic oxygenation ratio (CSOR). We compared TOI and CSOR before and after feeding. As the changes in TOI and CSOR had non-Gaussian distribution, nonparametric statistics were used.

RESULT

Among 32 infants, CSOR increased significantly after feeding (median difference 0.08; range -0.48, +0.58; P=0.011), whereas pulse oximetry did not change significantly (P=0.600). The change in CSOR with feeding was associated with a significant increase in splanchnic TOI (preprandial median 43.8, range 25.2-68.4 vs postprandial 47.5, range 25.8-70.8; P=0.013), without any significant change in brain TOI (preprandial median 64.9, range 44.5-75.4 vs postprandial 58.9, range 42.2-72.3; P=0.153).

CONCLUSION

This study indicates that CSOR and splanchnic TOI, but not brain TOI, increase significantly after feeding in stable preterm infants who are tolerating full orogastric feeds.

Searching for the Holy Grail: a review of markers of tissue perfusion in pediatric critical care

Goal-directed therapy has become the key to resuscitating critically ill patients since 2001. However, the ideal marker to guide pediatric resuscitation has remained elusive.The ideal marker is specific, sensitive, easy to use, safe, validated, and cost-effective. Lactate and base deficit are validated prognosticators, but both are affected by confounding conditions and resuscitative efforts. Mixed venous oximetry has been successfully used for guiding therapy but requires a pulmonary artery catheter for measurement. Central venous oximetry, on the other hand, can be more easily measured and is now the standard of care in goal-directed therapy for adult septic shock. Pediatric literature related to central venous oximetry is still in relative infancy, but seems promising. Sublingual capnometry may also prove to be useful, but no pediatric research has been published related to this device. Finally, near-infrared spectroscopy monitoring may be useful in highlighting changes in patient conditions, but its use in goal-directed therapy is limited by the wide interpatient variability. In summary, the search for the ideal marker of tissue perfusion continues, but there is promise on the horizon.