Interact CardioVasc Thorac Surg 2009;9:318-322. doi:10.1510/icvts.2009.206367
© 2009 European Association of Cardio-Thoracic Surgery
Best evidence topic - Cardiopulmonary bypass |
Does use of intra-operative cerebral regional oxygen saturation monitoring during cardiac surgery lead to improved clinical outcomes?
Hunaid A. Vohra,
Amit Modi and
Sunil K. Ohri*
Department of Cardiac Surgery, Wessex Cardiothoracic Centre, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD, UK
Received 28 February 2009;
received in revised form 23 April 2009;
accepted 29 April 2009
*Corresponding author. Tel.: +44 2380 777222; fax: +44 2380 798508.
E-mail address: sunil{at}ohri.co.uk (S.K. Ohri).
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Abstract
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A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the use of cerebral regional oxygen saturation (rSO2) monitoring during cardiac surgery can lead to improved clinical outcomes. Altogether 488 papers were found using the reported search, of which eight presented the best evidence to answer the clinical question. The author, year, journal, country of study, study type, patient group studied, relevant outcomes, results and study weaknesses were tabulated. Four prospective and another four retrospective studies involving adult and paediatric patients undergoing various cardiac surgical procedures were selected. These have demonstrated that prolonged intra-operative cerebral desaturations are associated with adverse neurological outcomes and prolonged hospital stay. Further, interventions carried out by thoughtful use of the cerebral oximeter are associated with significant reduction in neurologic injury, major organ morbidity and mortality (MOMM) and duration of hospital stay. Some studies have indicated decreased ventilation and intensive care unit (ICU) stay times as well. Clinical benefit and the lack of use-associated risk of injury at a modest expense support the use of this device routinely in patients undergoing cardiac surgery.
Key Words: Cerebral monitoring; Spectroscopy; Heart surgery; Outcome; Evidence-based medicine
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1. Introduction
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A best evidence topic was constructed according to a structured protocol. This protocol is fully described in the ICVTS [1].
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2. Clinical scenario
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A 73-year-old gentleman underwent tissue aortic valve replacement plus coronary artery bypass grafting (CABG) for severe aortic stenosis and single-vessel coronary artery disease at your centre. You were unable to extubate him in the early postoperative period in spite of haemodynamic stability. A CT-scan was performed that revealed ischaemic cerebral injury. Preoperative work-up did not demonstrate carotid stenosis, left-sided thrombi or a patent foramen ovale. Review of the operative notes revealed uncomplicated aortic cannulation and use of continuous carbon-dioxide gas flooding of the operative field for the time of aortic cross-clamp. You are aware of the INVOS® system that continuously monitors changes in the regional oxygen saturation (rSO2) of the blood in the brain, but no neuromonitoring is routinely done for cardiac surgical procedures at your centre. As a part of risk management, you want to make an effort to try and prevent this from happening again. Therefore, you resolve to search the literature to find the evidence.
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3. Three-part question
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In [patients undergoing cardiac surgery], does [intraoperative regional cerebral oxygenation monitoring] lead to improved [clinical outcomes]?
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4. Search strategy
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Medline 1950 to January 2009 using the OVID interface. (exp Cardiac Surgical Procedures/OR exp Thoracic Surgery/OR heart surgery.mp./OR cardiac surgery.mp.) AND (exp Brain Injuries/exp Spectroscopy, Near-Infrared/OR exp Oxygen/OR exp Oximetry/OR exp Monitoring, Intraoperative/) AND (outcome.mp.)
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5. Search outcome
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Four hundred and eighty-eight papers were found, of which eight were included in the BET analysis reported below. The relevant papers are presented in Table 1.
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6. Comments
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Eight clinical studies involving 250 paediatric and 3316 adult patients were found suitable. The studies looked at the clinical outcomes with rSO2 cerebral monitoring including a wide range of cardiac surgical procedures.
In a retrospective study by Austin et al. [2], 250 paediatric patients underwent neurophysiologic monitoring with electroencephalography (EEG), transcranial Doppler of middle cerebral artery and transcranial cerebral oximetry during repair of congenital cardiac defects. Patients were divided into three groups depending on whether a change was observed during monitoring and intervention was done or not. They report that the neurophysiologic monitoring algorithm can help to improve neurologic outcome in a cost-effective manner. The benefit of neurophysiologic monitoring was a significant reduction in neurologic sequelae and interventions led to earlier discharge from the hospital. However, monitoring was done using three modalities in each patient and so, the results of the study cannot be attributed to regional cerebral oximetry alone. Olsson and Thelin [3] reviewed 46 patients having aortic arch surgery with selective antegrade cerebral perfusion (SACP) and bilateral regional cerebral oximetry. In some cases, when rSO2 decreased suddenly because of technical errors such as cannula dislodgement or arterial line compromise, prompt counter-measures were employed. They observed that intra-operative blood gas measurements and mean arterial pressure showed no relation to neurologic outcome. Regional cerebral oximetry detected clinically important cerebral desaturations that helped to predict perioperative neurologic outcomes. The sensitivity and specificity of lower baseline rSO2 to predict a stroke was 83% and 94%, respectively. They further mention that standard intra-operative monitoring correlates poorly with cerebral rSO2 and cannot replace its use. Yao and colleagues [4] performed a prospective observational study comprising of 101 on-pump cardiac surgery patients with an aim to identify the relationship between rSO2 neuropsychological dysfunction after cardiac surgery. All clinicians were blinded and no interventions were made based on these observations. They deduced that intra-operative cerebral oxygen desaturation is significantly associated with early postoperative neuro-psychological dysfunction in patients undergoing cardiac surgery with cardiopulmonary bypass. Edmonds [5] reviewed 332 patients who underwent isolated CABG surgery with neuromonitoring including continuous EEG, transcranial ultrasound Doppler and regional cerebral oximetry. A standardised intervention technique was utilised to achieve near baseline values in all patients. Neurologic outcomes were compared to the expected incidence in patients without neuromonitoring in the landmark multicentre study by Roach et al. [6]. Roach and colleagues had demonstrated that adverse cerebral outcomes occurred in 6.1% of patients having elective CABG without neuromonitoring and had reported a necessity for improved cerebral surveillance during cardiac surgery. The demographics of the patient population were similar in both groups and the incidence of neurologic incidence was significantly reduced in the neuromonitoring group. Although multimodality monitoring was used in this study, the most common physiologic imbalance observed was regional cerebral hypoxia in 43% patients. Transcranial Doppler and focal EEG changes were detected in 16% and 1% patients only. Hong et al. [7] conducted a prospective observational study and reported significantly longer postoperative hospitalization with cerebral desaturation in patients undergoing valvular heart surgery. However, no significant correlation was found between development of early postoperative cognitive dysfunction and decrease in intra-operative cerebral rSO2.
A large series of patients underwent cardiac surgery and were retrospectively reviewed by Goldman and colleagues [8]. The patients were divided into two groups depending on whether they had intra-operative rSO2 monitoring with necessary intervention or no monitoring at all. They demonstrated a significantly lower incidence of permanent stroke and postoperative ventilation time in the group of patients with optimised cerebral oxygen delivery using cerebral oximetry monitoring. Murkin et al. [9] assessed perioperative major organ morbidity and mortality (MOMM) in 200 myocardial revascularization patients, 100 of whom had been randomly assigned to receive regional cerebral oximetry monitoring. They report that therapeutic efforts to avoid cerebral desaturation as assessed with rSO2 is associated with significantly fewer incidences of major organ dysfunction, shorter length of stay in the intensive care unit (ICU) and a trend to fewer patients having prolonged hospitalization, in patients undergoing CABG with cardiopulmonary bypass. Slater et al. [10] evaluated postoperative outcomes on 240 randomised patients undergoing primary CABG and observed that prolonged intra-operative cerebral desaturation is significantly associated with an increased risk of cognitive decline, as well as increased length of hospital stay. They concluded that intra-operative management of cerebral desaturation may result in decreased postoperative cognitive decline and less frequent prolonged length of hospital stay after CABG.
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7. Clinical bottom line
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These studies demonstrate the reliability of intra-operative rSO2 monitoring in determining adverse neurological outcomes after cardiac surgery. Further, interventions carried out by thoughtful use of the cerebral oximeter are associated with significant reductions in neurologic injury, MOMM and duration of hospital stay. Some studies have indicated decreased ventilation and ICU stay times as well.
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References
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- Dunning J, Prendergast B, Mackway-Jones K. Towards evidence-based medicine in cardiothoracic surgery: best BETS. Interact CardioVasc Thorac Surg 2003;2:405–409.[Abstract/Free Full Text]
- Austin EH 3rd, Edmonds HL Jr, Auden SM, Seremet V, Niznik G, Sehic A, Sowell MK, Cheppo CD, Corlett KM. Benefit of neurophysiologic monitoring for pediatric cardiac surgery. J Thorac Cardiovasc Surg 1997;114:707–715; 717.[Abstract/Free Full Text]
- Olsson C, Thelin S. Regional cerebral saturation monitoring with near-infrared spectroscopy during selective antegrade cerebral perfusion: diagnostic performance and relationship to postoperative stroke. J Thorac Cardiovasc Surg 2006;131:371–379.[Abstract/Free Full Text]
- Yao FS, Tseng CC, Ho CY, Levin SK, Illner P. Cerebral oxygen desaturation is associated with early postoperative neuropsychological dysfunction in patients undergoing cardiac surgery. J Cardiothorac Vasc Anesth 2004;18:552–558.[CrossRef][Medline]
- Edmonds HL Jr. Protective effect of neuromonitoring during cardiac surgery. Ann NY Acad Sci 2005;1053:12–19.[CrossRef][Medline]
- Roach GW, Kanchuger M, Mangano CM, Newman M, Nussmeier N, Wolman R, Aggarwal A, Marschall K, Graham SH, Ley C. Adverse cerebral outcomes after coronary bypass surgery. Multicenter Study of Perioperative Ischemia Research Group and the Ischemia Research and Education Foundation Investigators. N Engl J Med 1996;335:1857–1863.[Abstract/Free Full Text]
- Hong SW, Shim JK, Choi YS, Kim DH, Chang BC, Kwak YL. Prediction of cognitive dysfunction and patients' outcome following valvular heart surgery and the role of cerebral oximetry. Eur J Cardiothorac Surg 2008;33:560–565.[Abstract/Free Full Text]
- Goldman S, Sutter F, Ferdinand F, Trace C. Optimizing intraoperative cerebral oxygen delivery using non-invasive cerebral oximetry decreases the incidence of stroke for cardiac surgical patients. Heart Surg Forum 2004;7:E376–E381.[Medline]
- Murkin JM, Adams SJ, Novick RJ, Quantz M, Bainbridge D, Iglesias I, Cleland A, Schaefer B, Irwin B, Fox S. Monitoring brain oxygen saturation during coronary bypass surgery: a randomized, prospective study. Anesth Analg 2007;104:51–58.[Abstract/Free Full Text]
- Slater JP, Guarino T, Stack J, Vinod K, Bustami RT, Brown JM 3rd, Rodriguez AL, Magovern CJ, Zaubler T, Freundlich K, Parr GV. Cerebral oxygen desaturation predicts cognitive decline and longer hospital stay after cardiac surgery. Ann Thorac Surg 2009;87:36–44.[Abstract/Free Full Text]
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Abstract
1. Introduction