REVIEW URRENT C OPINION
The state of affairs of neurologic monitoring by near-infrared spectroscopy in pediatric cardiac critical care Samira Neshat Vahid and Jose M. Panisello
Purpose of review The decreasing postoperative mortality in patients with congenital heart disease has enabled an increasing interest in preventing morbidity, especially from the central nervous system. Near-infrared spectroscopy, a noninvasive technology that provides an estimate of tissue oxygenation, has been introduced in the intensive care unit and has gained popularity over the last decade. This review aims to ascertain its ability to affect outcome. Recent findings Recent studies have started to incorporate cerebral near-infrared spectroscopy in the assessment, evolution, and outcomes of surgical patients with congenital heart disease. These studies often represent small singlecenter high-risk cohorts that are evaluated in a retrospective or an observational manner. Nevertheless, new data are starting to indicate that near-infrared spectroscopy may be helpful not only in the assessment of critical care parameters, such as cardiac output performance or likelihood of adverse events, but, most notably, in the long-term neurological outcome. Summary In addition to additional corroborative trials from different centers, a critical question that remains to be answered is whether targeting cerebral near-infrared spectroscopy values, as part of goal-directed therapy protocols, can help to improve outcome overall. Keywords congenital heart disease, near-infrared spectroscopy, regional cerebral oxygen saturation
INTRODUCTION Improvements in perioperative and postoperative management have had an immense positive impact on the outcomes of pediatric patients with congenital heart disease (CHD). Decreasing mortality in this population [1] is shifting the preoccupation from mortality to morbidity and, in particular, to the prevention of adverse neurological outcomes among survivors. Determining the neurodevelopmental abnormalities, behavioral deficits, and learning disabilities has become the primary focus of multiple reports [2–5]. Neonates born with CHD are a particularly concerning population because they may have an abnormal preoperative cerebral blood flow pattern [6], a higher incidence of brain abnormalities [7], and a higher perioperative mortality [1]. The risk of compromised cerebral perfusion causing irreversible neuronal damage during cardiopulmonary bypass (CPB) and/or deep hypothermic circulatory arrest (DHCA) has been recognized for a
long time, and a variety of techniques have been introduced to monitor the patient during surgery. It is important to emphasize that the risk of neuronal injury continues in the postoperative period, as the freshly repaired heart must maintain adequate endorgan perfusion. Several studies have reported that a proportion of these patients will develop low cardiac output syndrome (LCOS) [8,9], potentially compromising cerebral perfusion [10]. Therefore, real-time monitoring of cerebral hemodynamics would be essential to evaluate the performance of the brain intraoperatively and postoperatively. Section of Pediatric Critical Care Medicine, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA Correspondence to Jose M. Panisello, MD, Section of Critical Care Medicine, Department of Pediatrics, Yale University School of Medicine, 333 Cedar St, PO Box 208064, New Haven, CT 06520-8064, USA. Tel: +1 203 785 4651; e-mail: [email protected] Curr Opin Pediatr 2014, 26:299–303 DOI:10.1097/MOP.0000000000000098
1040-8703 ß 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
www.co-pediatrics.com
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Emergency and critical care medicine
KEY POINTS NIRS provides a noninvasive measure of cerebral tissue oxygenation.
literature dedicated to correlating NIRS with clinical evolution and more specifically, with later neurological performance.
NIRS correlates well with the superior vena cava saturations and lactic acidemia, adding flexibility to the monitoring choices in the intensive care setting.
CORRELATION OF NEAR-INFRARED SPECTROSCOPY WITH COMMON HEMODYNAMIC MEASURES
NIRS may help to identify patients at high risk for low cardiac output and adverse events.
Initial validation work revealed a high degree of correlation between cerebral NIRS values and cerebral venous saturation measured at jugular bulb level [14–17]. In the last few years, other common hemodynamic parameters have been examined, in particular the correlation with the central venous saturation (SvO2) measured in the superior vena cava (SVC) [17–20]. Ricci et al. [21] have extended the measurements to the postoperative period, studying retrospectively the correlation between rScO2 and SVC SvO2 in a relatively large cohort of 100 neonates with cyanotic and noncyanotic CHD undergoing cardiac surgery. They found a significant (P < 0.001) but only fair correlation (r ¼ 0.37), which improved over time with closer trends after the first 18 h (r ¼ 0.5, P < 0.001). Hansen et al. [22] evaluated retrospectively a cohort (n ¼ 32) of patients, previously palliated via a Norwood procedure, after their superior cavopulmonary anastomosis. They found a good correlation between the cerebral rScO2 and SvO2 measure at the SVC level (r ¼ 0.68, P < 0.001). In addition, both values were initially similarly depressed and increased in parallel during the 48 h included in the study period. SVC SvO2 includes venous return from regions other than the brain and, consequently, rScO2 will diverge in the absolute value but can provide a consistent, noninvasive and continuous trend with SvO2 that adds flexibility to the capabilities of monitoring these children. Chakravarti et al. [23] evaluated the relation of NIRS and lactate in a cohort of 23 children undergoing repair of congenital heart lesions in a prospective observational fashion. They found a strong inverse correlation between rScO2 (65%) and lactate (3.0 mmol/l) (r ¼ 0.74, P < 0.0001) that improved when the renal NIRS was included in the average (r ¼ 0.82, P < 0.0001). It should be noted that, in addition to the small sample size, the authors excluded single ventricle physiology and patients with residual intracardiac shunts, so care should be taken when extrapolating these results and, in particular, the 65% rScO2 cut-off point. Nevertheless, the ability to detect noninvasively a relative low lactate level would be particularly useful in guiding therapy in the ICU, especially if the changes in NIRS values precede the raising lactate.
Evaluating critical care patients, including the transition to spontaneous breathing, may be facilitated by NIRS. Emerging evidence indicates that good cerebral NIRS values correlates with better neurodevelopmental outcomes.
¨ bsis [11] in 1977, near-infrared Introduced by Jo spectroscopy (NIRS) is a noninvasive technique to monitor tissue oxygen saturation that has been gaining acceptance over the last two decades. NIRS devices are able to measure the concentration of a substance based on its ability to absorb light. Nearinfrared photons are capable of penetrating human tissues, including bone, to a depth of a few centimeters [12]. Because the absorbance spectrum for oxygenated hemoglobin differs from that of deoxygenated hemoglobin, using light of different wavelengths permits quantitation of the relative concentration of each in the tissues [13]. In practice, near-infrared light is applied by placing a calibrated sensor on the skin of the area of interest: in the case of the brain, the sensor is applied on the forehead area. NIRS does not discriminate between arterial and venous vascular beds. As the majority of the blood volume in the brain tissue is venous [14], the resulting value is predominantly an expression of the venous saturation or so-called ‘venous weighted saturation’. It provides an estimate of brain oxygen extraction and a measure of the regional cerebral oxygen saturation (rScO2). NIRS technology has been introduced in the operating room as a technique for monitoring brain perfusion. Over the last decade, it has been gaining acceptance in the pediatric cardiac intensive care community, even though the benefit of using this technology to achieve better outcomes is still questionable.
REVIEW OF THE CURRENT LITERATURE Classically, the research efforts were mainly focused on validating NIRS as a monitoring technique. In recent years, this field has seen an emergent body of 300
www.co-pediatrics.com
Volume 26 Number 3 June 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Near-infrared spectroscopy in pediatric cardiac critical care Neshat Vahid and Panisello
UTILIZATION OF NEAR-INFRARED SPECTROSCOPY IN THE EVALUATION OF CARDIAC CRITICAL CARE PATIENTS In more recent studies, NIRS has been integrated in the evaluation of patients in the ICU after cardiac surgery. Bronicki et al. [24 ] in a prospective observational study documented the effects of spontaneous respiration in a cohort of patients (n ¼ 23) after the surgical repair of the tetralogy of Fallot using multisite NIRS. They observed a significant rise in the rScO2 from 67.3 10.7 to 72.3 9.9% (P ¼ 0.0001) alongside a significant increase in mean central venous saturation. The authors interpret these results as an increase in cardiac output during spontaneous respiration with greater right ventricular output in response to increased venous return. The improved rScO2 could be an indication that, during positive pressure ventilation, the cerebral blood flow was limited beyond autoregulation mechanisms, requiring the brain to compensate by extracting more O2. In a previous retrospective study from the same group [25], they showed remarkably similar rScO2 results (68.5 8.4 to 74.2 7.9%, P < 0.0001). The consistent changes with cerebral NIRS in both trials seem to indicate that this noninvasive technique may be useful in assessing the transition to spontaneous breathing. Zulueta et al. [26] retrospectively studied the applicability of intraoperative cerebral rScO2 score (time in seconds below a 50% saturation threshold) for early detection of postoperative LCOS. They observed that a high proportion of patients with a significant intraoperative rScO2 desaturation score developed signs of low cardiac output postoperatively (68%, P ¼ 0.002). Hansen et al. [22] also showed a relation between low rScO2 (and SvO2) in the initial postoperative period and postoperative complications in patients undergoing superior cavopulmonary anastomosis (P < 0.001). In a study by Dabal et al. [27], it appears that renal NIRS and inferior vena cava desaturations precede rScO2 changes in the prediction of serious cardiovascular adverse events in patients after stage 1 Norwood palliation. In this cohort, the rScO2 also changed significantly 4 h after postoperative intensive care admission. These studies are starting to outline the capabilities of cerebral NIRS in assessing postoperative cardiac patients, hinting that it may also be predictive of short-term outcomes. &
NEAR-INFRARED SPECTROSCOPY AND NEUROLOGICAL OUTCOMES Several studies have attempted to correlate the neurological outcome with NIRS perfusion values commonly obtained during the main neonatal
surgical episode, generally from patients undergoing complex repairs under DHCA. Simons et al. [28] evaluated a cohort of 27 children at 2 years of age, who had undergone cardiac surgery before their first birthday; they used the third edition of Bayley Scales of Infant and Toddler Development (Bayley Scale III) and concluded that receptive communication was influenced by rScO2 nadir. Sood et al. [29 ], in a more recent study from the same group, extended the assessment to the postoperative period. This study evaluated the neurological outcome, also at 2 years of age, of a group of children who had undergone CPB using primarily DHCA in the first 2 months of life. No clinical decisions were made on the basis of NIRS data, and a significant number of these children had additional cardiac operations before their second birthday. Interestingly, the neurological sequelae associated with the postoperative episode appeared to affect primarily the cognitive communication, with an area under the curve (AUC) of 0.66 similarly evaluated by the Bayley Scale III, whereas the area most affected by the intraoperative time was, as in the previous study, the receptive communication (AUC, 0.53). In this newer study, it was the percentage decrease in rScO2 below the baseline, measured during induction of anesthesia, that was clinically relevant for the intraoperative period, while a postoperative nadir rScO2 of 56% correlated with worse cognitive outcome. The fact that receptive communication was consistently affected as a consequence of the intraoperative episode in both trials provides additional strength to the results of these studies. In addition, the concept that the postoperative clinical course may have distinct neurological consequences from the intraoperative episode is of significant importance, and it should be explored further. Hoffman et al. [30 ] studied the neurological outcome of a sequential cohort of patients who had undergone stage 1 palliation for hypoplastic left heart syndrome, who had NIRS as part of their postoperative monitoring. Hemodynamic and NIRS data had been prospectively recorded during the first 48 h, and the authors used a goaldirected therapy protocol that included maintaining rScO2 > 50%. Twenty-one patients completed the neurological assessment between 4 and 6 years of age. Overall, this cohort had a good neurological outcome, with only four patients showing deficits in the visual motor integration [VMI; one abnormal or 2 standard deviations (SD) and three low performances or 1 SD below mean]. Two of those four patients had embolic strokes after their first hospitalization that worsened their VMI performance. The other domains tested, cognition and language,
1040-8703 ß 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
&
&&
www.co-pediatrics.com
301
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Emergency and critical care medicine
were normal, and attention was above normal. The authors concluded that the predicted VMI was normal with an hourly rScO2 > 55%. In low-risk conditions, the VMI was normal until a breakpoint of less than 45%. The authors compared these results with their own previous published cohort managed without NIRS but with continuous SvO2 via a catheter placed in the SVC [31]. The SVC SvO2 was significantly higher (62.6% 7.88 versus 54.4% 7.85, P < 0.01), and the VMI in the abnormally low range (excluding the patients with late strokes) was significantly lower (P < 0.03) in the newer cohort. The conclusion that targeting rScO2 rather than SVC SvO2 may improve outcome is obviously tempting, but corroborating data are needed to form this conclusion; nevertheless, the standardization of the medical care between these cohorts from the same center and the prospective data collection add strength to this proposal.
DISCUSSION The monitoring capabilities in critical care have not changed significantly in the last three decades. NIRS brings the promise of unlocking vascular beds previously inaccessible to the intensivist. The cardiac population presents unique challenges, and realtime feedback from the cerebral circulation would be very helpful to assess the critical care management in these children. The possibilities of this technology are still evolving; Buckley et al. [32] combined the use of NIRS with diffuse correlation spectroscopy, extending the monitoring capabilities to cerebral blood flow. Drury et al. [33] used a multimodal approach, which included NIRS, magnetic resonance imaging, and amplitude-integrated electroencephalography to assess the impact of DHCA in patients undergoing arterial switch operation. These studies hint at the development of new and more detailed neuromonitoring in the management of cardiac patients in the ICU. One practical problem with NIRS measurements is that, unlike most other noninvasive monitors, the clinician does not have an objective way to verify its accuracy with a direct measurement. The studies correlating NIRS values with other well-known clinical parameters help to include this technology in the monitoring tapestry of these patients; the additional information adds monitoring flexibility and may reduce the need for invasive sampling. Nevertheless, one should be aware of its limitations, that is, absorbing/scattering of light by molecules other than hemoglobin, thickness of scalp and skull, and the small measurement site (commonly from the frontal cortex), which does not include deep brain tissue structures. 302
www.co-pediatrics.com
These limitations, together with the small retrospective or observational single-center design of most studies, lack of clear rScO2 ischemia threshold values, and unclear correlation with outcome measures, have raised concerns about the validity of NIRS as standard of care [34,35]. The recent published studies have started to address some of these questions, such as the relation between low cerebral NIRS values and postoperative LCOS or increased incidence of adverse events [21,25,26]. The consistent results in both trials by Bronicki et al. [23,24 ] indicate that cerebral NIRS may be useful in assessing the transition to spontaneous breathing, in particular in those patients with right ventricular diastolic dysfunction. More importantly, some studies have started to decipher the relation between NIRS and neurodevelopmental outcomes. Sood et al. [29 ] have not only shown this relation, but identified areas that relate specifically to the care delivered in the ICU. The recent pivotal study from Hoffman et al. [30 ] also showed a correlation between low rScO2 and adverse neurological outcomes in children receiving Norwood palliation. Their methodology allowed them to pose the intriguing possibility that NIRS, compared with more classical monitoring approaches, may have utility with additional neuroprotective strategies. The fact that the data from NIRS can be related to neurodevelopmental testing years later is a remarkable finding, when these children have endured multiple neurological risks over that period despite state-of-the art medical care. Finally, we need to question whether we can actively manipulate the NIRS values to improve outcomes. Most trials used NIRS as an observational monitor, and it was not included in the clinical decision making. Some data are emerging, such as the aforementioned study from Hoffmann et al. [30 ], with a goal-directed therapy protocol to actively manage rScO2. In a recent adult study, the investigators were able to improve rScO2 88% of the time using an established protocol [36]; therefore, there is the potential to test whether manipulation of rScO2 improves outcome. &
&
&&
&&
CONCLUSION NIRS provides a noninvasive measure of rScO2. Despite the small single-center sample size and lack of randomization, the recent studies have indicated a potential benefit in the utilization of NIRS in cardiac critical care. Clearly, more confirmatory studies are required to determine whether NIRS can be utilized to improve outcome with goaldirected therapy. Volume 26 Number 3 June 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Near-infrared spectroscopy in pediatric cardiac critical care Neshat Vahid and Panisello
Acknowledgements We would like to thank Dr George Lister for his thoughtful review and Dr Fariba Chalajour for her help editing this article. Conflicts of interest There are no conflicts of interest.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Kaltman JR, Andropoulos DB, Checchia PA, et al. Report of the pediatric heart network and national heart, lung, and blood institute working group on the perioperative management of congenital heart disease. Circulation 2010; 121:2766–2772. 2. Wernovsky G, Shillingford AJ, Gaynor JW. Central nervous system outcomes in children with complex congenital heart disease. Curr Opin Cardiol 2005; 20:94–99. 3. Creighton DE, Robertson CM, Sauve RS, et al. Neurocognitive, functional, and health outcomes at 5 years of age for children after complex cardiac surgery at 6 weeks of age or younger. Pediatrics 2007; 120:e478–e486. 4. Shillingford AJ, Glanzman MM, Ittenbach RF, et al. Inattention, hyperactivity, and school performance in a population of school-age children with complex congenital heart disease. Pediatrics 2008; 121:e759–e767. 5. Bird GL, Jeffries HE, Licht DJ, et al. Neurological complications associated with the treatment of patients with congenital cardiac disease: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease. Cardiol Young 2008; 18 (Suppl 2):234–239. 6. Licht DJ, Wang J, Silvestre DW, et al. Preoperative cerebral blood flow is diminished in neonates with severe congenital heart defects. J Thorac Cardiovasc Surg 2004; 128:841–849. 7. Miller SP, McQuillen PS, Hamrick S, et al. Abnormal brain development in newborns with congenital heart disease. N Engl J Med 2007; 357:1928– 1938. 8. Wernovsky G, Wypij D, Jonas RA, et al. Postoperative course and hemodynamic profile after the arterial switch operation in neonates and infants. A comparison of low-flow cardiopulmonary bypass and circulatory arrest. Circulation 1995; 92:2226–2235. 9. Hoffman TM, Wernovsky G, Atz AM, et al. Efficacy and safety of milrinone in preventing low cardiac output syndrome in infants and children after corrective surgery for congenital heart disease. Circulation 2003; 107: 996–1002. 10. Pesonen EJ, Peltola KI, Korpela RE, et al. Delayed impairment of cerebral oxygenation after deep hypothermic circulatory arrest in children. Ann Thorac Surg 1999; 67:1765–1770. 11. Jo¨bsis FF. Noninvasive, infrared monitoring of cerebral and myocardial oxygen sufficiency and circulatory parameters. Science 1977; 198:1264–1267. 12. Scheeren TW, Schober P, Schwarte LA. Monitoring tissue oxygenation by near infrared spectroscopy (NIRS): background and current applications. J Clin Monit Comput 2012; 26:279–287. 13. Pellicer A, Bravo Mdel C. Near-infrared spectroscopy: a methodology-focused review. Semin Fetal Neonatal Med 2011; 16:42–49. 14. Watzman HM, Kurth CD, Montenegro LM, et al. Arterial and venous contributions to near-infrared cerebral oximetry. Anesthesiology 2000; 93:947– 953. 15. Abdul-Khaliq H, Troitzsch D, Berger F, et al. Regional transcranial oximetry with near infrared spectroscopy (NIRS) in comparison with measuring oxygen saturation in the jugular bulb in infants and children for monitoring cerebral oxygenation. Biomed Tech (Berl) 2000; 45:328–332. 16. Nagdyman N, Fleck T, Schubert S, et al. Comparison between cerebral tissue oxygenation index measured by near-infrared spectroscopy and venous jugular bulb saturation in children. Intensive Care Med 2005; 31:846– 850. 17. Nagdyman N, Ewert P, Peters B, et al. Comparison of different near-infrared spectroscopic cerebral oxygenation indices with central venous and jugular venous oxygenation saturation in children. Paediatr Anaesth 2008; 18:160– 166.
18. Bhutta AT, Ford JW, Parker JG, et al. Noninvasive cerebral oximeter as a surrogate for mixed venous saturation in children. Pediatr Cardiol 2007; 28:34–41. 19. Ranucci M, Isgro G, De la Torre T, et al. Near-infrared spectroscopy correlates with continuous superior vena cava oxygen saturation in pediatric cardiac surgery patients. Paediatr Anaesth 2008; 18:1163–1169. 20. Tortoriello TA, Stayer SA, Mott AR, et al. A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patients. Paediatr Anaesth 2005; 15: 495–503. 21. Ricci Z, Garisto C, Favia I, et al. Cerebral NIRS as a marker of superior vena cava oxygen saturation in neonates with congenital heart disease. Paediatr Anaesth 2010; 20:1040–1045. 22. Hansen JH, Schlangen J, Armbrust S, et al. Monitoring of regional tissue oxygenation with near-infrared spectroscopy during the early postoperative course after superior cavopulmonary anastomosis. Eur J Cardiothorac Surg 2013; 43:e37–e43. 23. Chakravarti SB, Mittnacht AJ, Katz JC, et al. Multisite near-infrared spectroscopy predicts elevated blood lactate level in children after cardiac surgery. J Cardiothorac Vasc Anesth 2009; 23:663–667. 24. Bronicki RA, Checchia PA, Anas NG, et al. Cerebral and somatic oxygen & saturations after repair of tetralogy of Fallot: effects of extubation on regional blood flow. Ann Thorac Surg 2013; 95:682–686. Prospective observational study aiming to evaluate whether the loading of respiratory muscles after extubation in patients undergoing tetralogy of Fallot repair offsets the benefits gained by improving hemodynamics at the right ventricular level. The authors used NIRS to assess this short-term outcome and demonstrated the benefit of spontaneous breathing. It should be noted that NIRS was observational, and the results should not be interpreted as an early extubation trial. 25. Bronicki RA, Herrera M, Mink R, et al. Hemodynamics and cerebral oxygenation following repair of tetralogy of Fallot: the effects of converting from positive pressure ventilation to spontaneous breathing. Congenit Heart Dis 2010; 5:416–421. 26. Zulueta JL, Vida VL, Perisinotto E, et al. Role of intraoperative regional oxygen saturation using near infrared spectroscopy in the prediction of low output syndrome after pediatric heart surgery. J Card Surg 2013; 28:446–452. 27. Dabal RJ, Rhodes LA, Borasino S, et al. Inferior vena cava oxygen saturation monitoring after the Norwood procedure. Ann Thorac Surg 2013; 95:2114– 2120; discussion 2120–2121. 28. Simons J, Sood ED, Derby CD, et al. Predictive value of near-infrared spectroscopy on neurodevelopmental outcome after surgery for congenital heart disease in infancy. J Thorac Cardiovasc Surg 2012; 143:118–125. 29. Sood ED, Benzaquen JS, Davies RR, et al. Predictive value of perioperative & near-infrared spectroscopy for neurodevelopmental outcomes after cardiac surgery in infancy. J Thorac Cardiovasc Surg 2013; 145:438–445; e1; discussion 444–445. This study provides evidence for the first time that critical care may have distinct and separate neurological consequences from the intraoperative episode. It is also a good example of researchers following and extending previous work 30. Hoffman GM, Brosig CL, Mussatto KA, et al. Perioperative cerebral oxygen && saturation in neonates with hypoplastic left heart syndrome and childhood neurodevelopmental outcome. J Thorac Cardiovasc Surg 2013; 146:1153– 1164. One of the first studies to include NIRS targets in a goal-directed therapy protocol. The authors were able to correlate good cerebral NIRS values with superior neurological performance. Their methodology includes prospective and ongoing data collection that allows comparison between cohorts. In this manner, they were able to demonstrate superior results in both physiological and neurological outcomes using cerebral NIRS instead of continuous superior vena cava saturations. 31. Hoffman GM, Mussatto KA, Brosig CL, et al. Systemic venous oxygen saturation after the Norwood procedure and childhood neurodevelopmental outcome. J Thorac Cardiovasc Surg 2005; 130:1094–1100. 32. Buckley EM, Lynch JM, Goff DA, et al. Early postoperative changes in cerebral oxygen metabolism following neonatal cardiac surgery: effects of surgical duration. J Thorac Cardiovasc Surg 2013; 145:196–203. 33. Drury PP, Gunn AJ, Bennet L, et al. Deep hypothermic circulatory arrest during the arterial switch operation is associated with reduction in cerebral oxygen extraction but no increase in white matter injury. J Thorac Cardiovasc Surg 2013; 146:1327–1333. 34. Hirsch JC, Charpie JR, Ohye RG, et al. Near-infrared spectroscopy: what we know and what we need to know – a systematic review of the congenital heart disease literature. J Thorac Cardiovasc Surg 2009; 137:154–159. 35. Hirsch JC, Charpie JR, Ohye RG, et al. Near infrared spectroscopy (NIRS) should not be standard of care for postoperative management. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2010; 13:51–54. 36. Deschamps A, Lambert J, Couture P, et al. Reversal of decreases in cerebral saturation in high-risk cardiac surgery. J Cardiothorac Vasc Anesth 2013; 27:1260–1266.
1040-8703 ß 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
www.co-pediatrics.com
303
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
The state of affairs of neurologic monitoring by near-infrared spectroscopy in pediatric cardiac critical care Samira Neshat Vahid and Jose M. Panisello
Purpose of review The decreasing postoperative mortality in patients with congenital heart disease has enabled an increasing interest in preventing morbidity, especially from the central nervous system. Near-infrared spectroscopy, a noninvasive technology that provides an estimate of tissue oxygenation, has been introduced in the intensive care unit and has gained popularity over the last decade. This review aims to ascertain its ability to affect outcome. Recent findings Recent studies have started to incorporate cerebral near-infrared spectroscopy in the assessment, evolution, and outcomes of surgical patients with congenital heart disease. These studies often represent small singlecenter high-risk cohorts that are evaluated in a retrospective or an observational manner. Nevertheless, new data are starting to indicate that near-infrared spectroscopy may be helpful not only in the assessment of critical care parameters, such as cardiac output performance or likelihood of adverse events, but, most notably, in the long-term neurological outcome. Summary In addition to additional corroborative trials from different centers, a critical question that remains to be answered is whether targeting cerebral near-infrared spectroscopy values, as part of goal-directed therapy protocols, can help to improve outcome overall. Keywords congenital heart disease, near-infrared spectroscopy, regional cerebral oxygen saturation
INTRODUCTION Improvements in perioperative and postoperative management have had an immense positive impact on the outcomes of pediatric patients with congenital heart disease (CHD). Decreasing mortality in this population [1] is shifting the preoccupation from mortality to morbidity and, in particular, to the prevention of adverse neurological outcomes among survivors. Determining the neurodevelopmental abnormalities, behavioral deficits, and learning disabilities has become the primary focus of multiple reports [2–5]. Neonates born with CHD are a particularly concerning population because they may have an abnormal preoperative cerebral blood flow pattern [6], a higher incidence of brain abnormalities [7], and a higher perioperative mortality [1]. The risk of compromised cerebral perfusion causing irreversible neuronal damage during cardiopulmonary bypass (CPB) and/or deep hypothermic circulatory arrest (DHCA) has been recognized for a
long time, and a variety of techniques have been introduced to monitor the patient during surgery. It is important to emphasize that the risk of neuronal injury continues in the postoperative period, as the freshly repaired heart must maintain adequate endorgan perfusion. Several studies have reported that a proportion of these patients will develop low cardiac output syndrome (LCOS) [8,9], potentially compromising cerebral perfusion [10]. Therefore, real-time monitoring of cerebral hemodynamics would be essential to evaluate the performance of the brain intraoperatively and postoperatively. Section of Pediatric Critical Care Medicine, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA Correspondence to Jose M. Panisello, MD, Section of Critical Care Medicine, Department of Pediatrics, Yale University School of Medicine, 333 Cedar St, PO Box 208064, New Haven, CT 06520-8064, USA. Tel: +1 203 785 4651; e-mail: [email protected] Curr Opin Pediatr 2014, 26:299–303 DOI:10.1097/MOP.0000000000000098
1040-8703 ß 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
www.co-pediatrics.com
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Emergency and critical care medicine
KEY POINTS NIRS provides a noninvasive measure of cerebral tissue oxygenation.
literature dedicated to correlating NIRS with clinical evolution and more specifically, with later neurological performance.
NIRS correlates well with the superior vena cava saturations and lactic acidemia, adding flexibility to the monitoring choices in the intensive care setting.
CORRELATION OF NEAR-INFRARED SPECTROSCOPY WITH COMMON HEMODYNAMIC MEASURES
NIRS may help to identify patients at high risk for low cardiac output and adverse events.
Initial validation work revealed a high degree of correlation between cerebral NIRS values and cerebral venous saturation measured at jugular bulb level [14–17]. In the last few years, other common hemodynamic parameters have been examined, in particular the correlation with the central venous saturation (SvO2) measured in the superior vena cava (SVC) [17–20]. Ricci et al. [21] have extended the measurements to the postoperative period, studying retrospectively the correlation between rScO2 and SVC SvO2 in a relatively large cohort of 100 neonates with cyanotic and noncyanotic CHD undergoing cardiac surgery. They found a significant (P < 0.001) but only fair correlation (r ¼ 0.37), which improved over time with closer trends after the first 18 h (r ¼ 0.5, P < 0.001). Hansen et al. [22] evaluated retrospectively a cohort (n ¼ 32) of patients, previously palliated via a Norwood procedure, after their superior cavopulmonary anastomosis. They found a good correlation between the cerebral rScO2 and SvO2 measure at the SVC level (r ¼ 0.68, P < 0.001). In addition, both values were initially similarly depressed and increased in parallel during the 48 h included in the study period. SVC SvO2 includes venous return from regions other than the brain and, consequently, rScO2 will diverge in the absolute value but can provide a consistent, noninvasive and continuous trend with SvO2 that adds flexibility to the capabilities of monitoring these children. Chakravarti et al. [23] evaluated the relation of NIRS and lactate in a cohort of 23 children undergoing repair of congenital heart lesions in a prospective observational fashion. They found a strong inverse correlation between rScO2 (65%) and lactate (3.0 mmol/l) (r ¼ 0.74, P < 0.0001) that improved when the renal NIRS was included in the average (r ¼ 0.82, P < 0.0001). It should be noted that, in addition to the small sample size, the authors excluded single ventricle physiology and patients with residual intracardiac shunts, so care should be taken when extrapolating these results and, in particular, the 65% rScO2 cut-off point. Nevertheless, the ability to detect noninvasively a relative low lactate level would be particularly useful in guiding therapy in the ICU, especially if the changes in NIRS values precede the raising lactate.
Evaluating critical care patients, including the transition to spontaneous breathing, may be facilitated by NIRS. Emerging evidence indicates that good cerebral NIRS values correlates with better neurodevelopmental outcomes.
¨ bsis [11] in 1977, near-infrared Introduced by Jo spectroscopy (NIRS) is a noninvasive technique to monitor tissue oxygen saturation that has been gaining acceptance over the last two decades. NIRS devices are able to measure the concentration of a substance based on its ability to absorb light. Nearinfrared photons are capable of penetrating human tissues, including bone, to a depth of a few centimeters [12]. Because the absorbance spectrum for oxygenated hemoglobin differs from that of deoxygenated hemoglobin, using light of different wavelengths permits quantitation of the relative concentration of each in the tissues [13]. In practice, near-infrared light is applied by placing a calibrated sensor on the skin of the area of interest: in the case of the brain, the sensor is applied on the forehead area. NIRS does not discriminate between arterial and venous vascular beds. As the majority of the blood volume in the brain tissue is venous [14], the resulting value is predominantly an expression of the venous saturation or so-called ‘venous weighted saturation’. It provides an estimate of brain oxygen extraction and a measure of the regional cerebral oxygen saturation (rScO2). NIRS technology has been introduced in the operating room as a technique for monitoring brain perfusion. Over the last decade, it has been gaining acceptance in the pediatric cardiac intensive care community, even though the benefit of using this technology to achieve better outcomes is still questionable.
REVIEW OF THE CURRENT LITERATURE Classically, the research efforts were mainly focused on validating NIRS as a monitoring technique. In recent years, this field has seen an emergent body of 300
www.co-pediatrics.com
Volume 26 Number 3 June 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Near-infrared spectroscopy in pediatric cardiac critical care Neshat Vahid and Panisello
UTILIZATION OF NEAR-INFRARED SPECTROSCOPY IN THE EVALUATION OF CARDIAC CRITICAL CARE PATIENTS In more recent studies, NIRS has been integrated in the evaluation of patients in the ICU after cardiac surgery. Bronicki et al. [24 ] in a prospective observational study documented the effects of spontaneous respiration in a cohort of patients (n ¼ 23) after the surgical repair of the tetralogy of Fallot using multisite NIRS. They observed a significant rise in the rScO2 from 67.3 10.7 to 72.3 9.9% (P ¼ 0.0001) alongside a significant increase in mean central venous saturation. The authors interpret these results as an increase in cardiac output during spontaneous respiration with greater right ventricular output in response to increased venous return. The improved rScO2 could be an indication that, during positive pressure ventilation, the cerebral blood flow was limited beyond autoregulation mechanisms, requiring the brain to compensate by extracting more O2. In a previous retrospective study from the same group [25], they showed remarkably similar rScO2 results (68.5 8.4 to 74.2 7.9%, P < 0.0001). The consistent changes with cerebral NIRS in both trials seem to indicate that this noninvasive technique may be useful in assessing the transition to spontaneous breathing. Zulueta et al. [26] retrospectively studied the applicability of intraoperative cerebral rScO2 score (time in seconds below a 50% saturation threshold) for early detection of postoperative LCOS. They observed that a high proportion of patients with a significant intraoperative rScO2 desaturation score developed signs of low cardiac output postoperatively (68%, P ¼ 0.002). Hansen et al. [22] also showed a relation between low rScO2 (and SvO2) in the initial postoperative period and postoperative complications in patients undergoing superior cavopulmonary anastomosis (P < 0.001). In a study by Dabal et al. [27], it appears that renal NIRS and inferior vena cava desaturations precede rScO2 changes in the prediction of serious cardiovascular adverse events in patients after stage 1 Norwood palliation. In this cohort, the rScO2 also changed significantly 4 h after postoperative intensive care admission. These studies are starting to outline the capabilities of cerebral NIRS in assessing postoperative cardiac patients, hinting that it may also be predictive of short-term outcomes. &
NEAR-INFRARED SPECTROSCOPY AND NEUROLOGICAL OUTCOMES Several studies have attempted to correlate the neurological outcome with NIRS perfusion values commonly obtained during the main neonatal
surgical episode, generally from patients undergoing complex repairs under DHCA. Simons et al. [28] evaluated a cohort of 27 children at 2 years of age, who had undergone cardiac surgery before their first birthday; they used the third edition of Bayley Scales of Infant and Toddler Development (Bayley Scale III) and concluded that receptive communication was influenced by rScO2 nadir. Sood et al. [29 ], in a more recent study from the same group, extended the assessment to the postoperative period. This study evaluated the neurological outcome, also at 2 years of age, of a group of children who had undergone CPB using primarily DHCA in the first 2 months of life. No clinical decisions were made on the basis of NIRS data, and a significant number of these children had additional cardiac operations before their second birthday. Interestingly, the neurological sequelae associated with the postoperative episode appeared to affect primarily the cognitive communication, with an area under the curve (AUC) of 0.66 similarly evaluated by the Bayley Scale III, whereas the area most affected by the intraoperative time was, as in the previous study, the receptive communication (AUC, 0.53). In this newer study, it was the percentage decrease in rScO2 below the baseline, measured during induction of anesthesia, that was clinically relevant for the intraoperative period, while a postoperative nadir rScO2 of 56% correlated with worse cognitive outcome. The fact that receptive communication was consistently affected as a consequence of the intraoperative episode in both trials provides additional strength to the results of these studies. In addition, the concept that the postoperative clinical course may have distinct neurological consequences from the intraoperative episode is of significant importance, and it should be explored further. Hoffman et al. [30 ] studied the neurological outcome of a sequential cohort of patients who had undergone stage 1 palliation for hypoplastic left heart syndrome, who had NIRS as part of their postoperative monitoring. Hemodynamic and NIRS data had been prospectively recorded during the first 48 h, and the authors used a goaldirected therapy protocol that included maintaining rScO2 > 50%. Twenty-one patients completed the neurological assessment between 4 and 6 years of age. Overall, this cohort had a good neurological outcome, with only four patients showing deficits in the visual motor integration [VMI; one abnormal or 2 standard deviations (SD) and three low performances or 1 SD below mean]. Two of those four patients had embolic strokes after their first hospitalization that worsened their VMI performance. The other domains tested, cognition and language,
1040-8703 ß 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
&
&&
www.co-pediatrics.com
301
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Emergency and critical care medicine
were normal, and attention was above normal. The authors concluded that the predicted VMI was normal with an hourly rScO2 > 55%. In low-risk conditions, the VMI was normal until a breakpoint of less than 45%. The authors compared these results with their own previous published cohort managed without NIRS but with continuous SvO2 via a catheter placed in the SVC [31]. The SVC SvO2 was significantly higher (62.6% 7.88 versus 54.4% 7.85, P < 0.01), and the VMI in the abnormally low range (excluding the patients with late strokes) was significantly lower (P < 0.03) in the newer cohort. The conclusion that targeting rScO2 rather than SVC SvO2 may improve outcome is obviously tempting, but corroborating data are needed to form this conclusion; nevertheless, the standardization of the medical care between these cohorts from the same center and the prospective data collection add strength to this proposal.
DISCUSSION The monitoring capabilities in critical care have not changed significantly in the last three decades. NIRS brings the promise of unlocking vascular beds previously inaccessible to the intensivist. The cardiac population presents unique challenges, and realtime feedback from the cerebral circulation would be very helpful to assess the critical care management in these children. The possibilities of this technology are still evolving; Buckley et al. [32] combined the use of NIRS with diffuse correlation spectroscopy, extending the monitoring capabilities to cerebral blood flow. Drury et al. [33] used a multimodal approach, which included NIRS, magnetic resonance imaging, and amplitude-integrated electroencephalography to assess the impact of DHCA in patients undergoing arterial switch operation. These studies hint at the development of new and more detailed neuromonitoring in the management of cardiac patients in the ICU. One practical problem with NIRS measurements is that, unlike most other noninvasive monitors, the clinician does not have an objective way to verify its accuracy with a direct measurement. The studies correlating NIRS values with other well-known clinical parameters help to include this technology in the monitoring tapestry of these patients; the additional information adds monitoring flexibility and may reduce the need for invasive sampling. Nevertheless, one should be aware of its limitations, that is, absorbing/scattering of light by molecules other than hemoglobin, thickness of scalp and skull, and the small measurement site (commonly from the frontal cortex), which does not include deep brain tissue structures. 302
www.co-pediatrics.com
These limitations, together with the small retrospective or observational single-center design of most studies, lack of clear rScO2 ischemia threshold values, and unclear correlation with outcome measures, have raised concerns about the validity of NIRS as standard of care [34,35]. The recent published studies have started to address some of these questions, such as the relation between low cerebral NIRS values and postoperative LCOS or increased incidence of adverse events [21,25,26]. The consistent results in both trials by Bronicki et al. [23,24 ] indicate that cerebral NIRS may be useful in assessing the transition to spontaneous breathing, in particular in those patients with right ventricular diastolic dysfunction. More importantly, some studies have started to decipher the relation between NIRS and neurodevelopmental outcomes. Sood et al. [29 ] have not only shown this relation, but identified areas that relate specifically to the care delivered in the ICU. The recent pivotal study from Hoffman et al. [30 ] also showed a correlation between low rScO2 and adverse neurological outcomes in children receiving Norwood palliation. Their methodology allowed them to pose the intriguing possibility that NIRS, compared with more classical monitoring approaches, may have utility with additional neuroprotective strategies. The fact that the data from NIRS can be related to neurodevelopmental testing years later is a remarkable finding, when these children have endured multiple neurological risks over that period despite state-of-the art medical care. Finally, we need to question whether we can actively manipulate the NIRS values to improve outcomes. Most trials used NIRS as an observational monitor, and it was not included in the clinical decision making. Some data are emerging, such as the aforementioned study from Hoffmann et al. [30 ], with a goal-directed therapy protocol to actively manage rScO2. In a recent adult study, the investigators were able to improve rScO2 88% of the time using an established protocol [36]; therefore, there is the potential to test whether manipulation of rScO2 improves outcome. &
&
&&
&&
CONCLUSION NIRS provides a noninvasive measure of rScO2. Despite the small single-center sample size and lack of randomization, the recent studies have indicated a potential benefit in the utilization of NIRS in cardiac critical care. Clearly, more confirmatory studies are required to determine whether NIRS can be utilized to improve outcome with goaldirected therapy. Volume 26 Number 3 June 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Near-infrared spectroscopy in pediatric cardiac critical care Neshat Vahid and Panisello
Acknowledgements We would like to thank Dr George Lister for his thoughtful review and Dr Fariba Chalajour for her help editing this article. Conflicts of interest There are no conflicts of interest.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Kaltman JR, Andropoulos DB, Checchia PA, et al. Report of the pediatric heart network and national heart, lung, and blood institute working group on the perioperative management of congenital heart disease. Circulation 2010; 121:2766–2772. 2. Wernovsky G, Shillingford AJ, Gaynor JW. Central nervous system outcomes in children with complex congenital heart disease. Curr Opin Cardiol 2005; 20:94–99. 3. Creighton DE, Robertson CM, Sauve RS, et al. Neurocognitive, functional, and health outcomes at 5 years of age for children after complex cardiac surgery at 6 weeks of age or younger. Pediatrics 2007; 120:e478–e486. 4. Shillingford AJ, Glanzman MM, Ittenbach RF, et al. Inattention, hyperactivity, and school performance in a population of school-age children with complex congenital heart disease. Pediatrics 2008; 121:e759–e767. 5. Bird GL, Jeffries HE, Licht DJ, et al. Neurological complications associated with the treatment of patients with congenital cardiac disease: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease. Cardiol Young 2008; 18 (Suppl 2):234–239. 6. Licht DJ, Wang J, Silvestre DW, et al. Preoperative cerebral blood flow is diminished in neonates with severe congenital heart defects. J Thorac Cardiovasc Surg 2004; 128:841–849. 7. Miller SP, McQuillen PS, Hamrick S, et al. Abnormal brain development in newborns with congenital heart disease. N Engl J Med 2007; 357:1928– 1938. 8. Wernovsky G, Wypij D, Jonas RA, et al. Postoperative course and hemodynamic profile after the arterial switch operation in neonates and infants. A comparison of low-flow cardiopulmonary bypass and circulatory arrest. Circulation 1995; 92:2226–2235. 9. Hoffman TM, Wernovsky G, Atz AM, et al. Efficacy and safety of milrinone in preventing low cardiac output syndrome in infants and children after corrective surgery for congenital heart disease. Circulation 2003; 107: 996–1002. 10. Pesonen EJ, Peltola KI, Korpela RE, et al. Delayed impairment of cerebral oxygenation after deep hypothermic circulatory arrest in children. Ann Thorac Surg 1999; 67:1765–1770. 11. Jo¨bsis FF. Noninvasive, infrared monitoring of cerebral and myocardial oxygen sufficiency and circulatory parameters. Science 1977; 198:1264–1267. 12. Scheeren TW, Schober P, Schwarte LA. Monitoring tissue oxygenation by near infrared spectroscopy (NIRS): background and current applications. J Clin Monit Comput 2012; 26:279–287. 13. Pellicer A, Bravo Mdel C. Near-infrared spectroscopy: a methodology-focused review. Semin Fetal Neonatal Med 2011; 16:42–49. 14. Watzman HM, Kurth CD, Montenegro LM, et al. Arterial and venous contributions to near-infrared cerebral oximetry. Anesthesiology 2000; 93:947– 953. 15. Abdul-Khaliq H, Troitzsch D, Berger F, et al. Regional transcranial oximetry with near infrared spectroscopy (NIRS) in comparison with measuring oxygen saturation in the jugular bulb in infants and children for monitoring cerebral oxygenation. Biomed Tech (Berl) 2000; 45:328–332. 16. Nagdyman N, Fleck T, Schubert S, et al. Comparison between cerebral tissue oxygenation index measured by near-infrared spectroscopy and venous jugular bulb saturation in children. Intensive Care Med 2005; 31:846– 850. 17. Nagdyman N, Ewert P, Peters B, et al. Comparison of different near-infrared spectroscopic cerebral oxygenation indices with central venous and jugular venous oxygenation saturation in children. Paediatr Anaesth 2008; 18:160– 166.
18. Bhutta AT, Ford JW, Parker JG, et al. Noninvasive cerebral oximeter as a surrogate for mixed venous saturation in children. Pediatr Cardiol 2007; 28:34–41. 19. Ranucci M, Isgro G, De la Torre T, et al. Near-infrared spectroscopy correlates with continuous superior vena cava oxygen saturation in pediatric cardiac surgery patients. Paediatr Anaesth 2008; 18:1163–1169. 20. Tortoriello TA, Stayer SA, Mott AR, et al. A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patients. Paediatr Anaesth 2005; 15: 495–503. 21. Ricci Z, Garisto C, Favia I, et al. Cerebral NIRS as a marker of superior vena cava oxygen saturation in neonates with congenital heart disease. Paediatr Anaesth 2010; 20:1040–1045. 22. Hansen JH, Schlangen J, Armbrust S, et al. Monitoring of regional tissue oxygenation with near-infrared spectroscopy during the early postoperative course after superior cavopulmonary anastomosis. Eur J Cardiothorac Surg 2013; 43:e37–e43. 23. Chakravarti SB, Mittnacht AJ, Katz JC, et al. Multisite near-infrared spectroscopy predicts elevated blood lactate level in children after cardiac surgery. J Cardiothorac Vasc Anesth 2009; 23:663–667. 24. Bronicki RA, Checchia PA, Anas NG, et al. Cerebral and somatic oxygen & saturations after repair of tetralogy of Fallot: effects of extubation on regional blood flow. Ann Thorac Surg 2013; 95:682–686. Prospective observational study aiming to evaluate whether the loading of respiratory muscles after extubation in patients undergoing tetralogy of Fallot repair offsets the benefits gained by improving hemodynamics at the right ventricular level. The authors used NIRS to assess this short-term outcome and demonstrated the benefit of spontaneous breathing. It should be noted that NIRS was observational, and the results should not be interpreted as an early extubation trial. 25. Bronicki RA, Herrera M, Mink R, et al. Hemodynamics and cerebral oxygenation following repair of tetralogy of Fallot: the effects of converting from positive pressure ventilation to spontaneous breathing. Congenit Heart Dis 2010; 5:416–421. 26. Zulueta JL, Vida VL, Perisinotto E, et al. Role of intraoperative regional oxygen saturation using near infrared spectroscopy in the prediction of low output syndrome after pediatric heart surgery. J Card Surg 2013; 28:446–452. 27. Dabal RJ, Rhodes LA, Borasino S, et al. Inferior vena cava oxygen saturation monitoring after the Norwood procedure. Ann Thorac Surg 2013; 95:2114– 2120; discussion 2120–2121. 28. Simons J, Sood ED, Derby CD, et al. Predictive value of near-infrared spectroscopy on neurodevelopmental outcome after surgery for congenital heart disease in infancy. J Thorac Cardiovasc Surg 2012; 143:118–125. 29. Sood ED, Benzaquen JS, Davies RR, et al. Predictive value of perioperative & near-infrared spectroscopy for neurodevelopmental outcomes after cardiac surgery in infancy. J Thorac Cardiovasc Surg 2013; 145:438–445; e1; discussion 444–445. This study provides evidence for the first time that critical care may have distinct and separate neurological consequences from the intraoperative episode. It is also a good example of researchers following and extending previous work 30. Hoffman GM, Brosig CL, Mussatto KA, et al. Perioperative cerebral oxygen && saturation in neonates with hypoplastic left heart syndrome and childhood neurodevelopmental outcome. J Thorac Cardiovasc Surg 2013; 146:1153– 1164. One of the first studies to include NIRS targets in a goal-directed therapy protocol. The authors were able to correlate good cerebral NIRS values with superior neurological performance. Their methodology includes prospective and ongoing data collection that allows comparison between cohorts. In this manner, they were able to demonstrate superior results in both physiological and neurological outcomes using cerebral NIRS instead of continuous superior vena cava saturations. 31. Hoffman GM, Mussatto KA, Brosig CL, et al. Systemic venous oxygen saturation after the Norwood procedure and childhood neurodevelopmental outcome. J Thorac Cardiovasc Surg 2005; 130:1094–1100. 32. Buckley EM, Lynch JM, Goff DA, et al. Early postoperative changes in cerebral oxygen metabolism following neonatal cardiac surgery: effects of surgical duration. J Thorac Cardiovasc Surg 2013; 145:196–203. 33. Drury PP, Gunn AJ, Bennet L, et al. Deep hypothermic circulatory arrest during the arterial switch operation is associated with reduction in cerebral oxygen extraction but no increase in white matter injury. J Thorac Cardiovasc Surg 2013; 146:1327–1333. 34. Hirsch JC, Charpie JR, Ohye RG, et al. Near-infrared spectroscopy: what we know and what we need to know – a systematic review of the congenital heart disease literature. J Thorac Cardiovasc Surg 2009; 137:154–159. 35. Hirsch JC, Charpie JR, Ohye RG, et al. Near infrared spectroscopy (NIRS) should not be standard of care for postoperative management. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2010; 13:51–54. 36. Deschamps A, Lambert J, Couture P, et al. Reversal of decreases in cerebral saturation in high-risk cardiac surgery. J Cardiothorac Vasc Anesth 2013; 27:1260–1266.
1040-8703 ß 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
www.co-pediatrics.com
303
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
