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Annals of Cardiac Anaesthesia Annals of Cardiac Anaesthesia Annals of Cardiac Anaesthesia
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Table of Contents
INVITED COMMENTARY  
Year : 2013  |  Volume : 16  |  Issue : 2  |  Page : 107-108
Action is the foundational key to all success" (Pablo Picasso)


Department of Anesthesiology, The Mount Sinai Medical Center, Box 1010, One Gustave L. Levy Place, New York, NY, USA

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Date of Web Publication29-Mar-2013
 

How to cite this article:
Mittnacht AJ. Action is the foundational key to all success" (Pablo Picasso). Ann Card Anaesth 2013;16:107-8

How to cite this URL:
Mittnacht AJ. Action is the foundational key to all success" (Pablo Picasso). Ann Card Anaesth [serial online] 2013 [cited 2019 Jul 15];16:107-8. Available from: http://www.annals.in/text.asp?2013/16/2/107/109743


In this issue of Annals of Cardiac Anesthesia, Mohandas et al, [1] report on cerebral oximetry monitoring and neurological outcome in patients undergoing open heart surgery. There is good evidence that changes in cerebral oximetry can be linked to clinical events, [2] and prolonged periods of tissue oxygen desaturation have been shown to correlate reasonably well with commonly used outcome measures. [3] There are very few well-designed prospective studies; however, that succeed in finding a correlation between monitoring, intervention based on the monitored parameters, and outcome. [4] The authors should be congratulated on performing such a study, and providing us with further insight into this complex matter. One hundred patients undergoing open heart surgery were randomly assigned to either a control group with the cerebral oximetry values blinded to the anesthesiologist or an intervention group. In the latter group of patients, a drop in cerebral oximetry values below an intervention threshold prompted a correction plan. Based on an algorithm published by Denault et al, [5] attempts to correct low cerebral oximetry readings were made once regional cerebral oxygen saturation (rSO 2 ) decreased more than 15% from baseline, or below an absolute value of 50% for at least 1 min. The goal in the intervention group was to keep rSO 2 values above 80% of a baseline value, which was obtained prior to anesthesia induction. Neurocognitive testing was performed on all patients. Significantly more patients in the control group showed early neurocognitive impairment. Early post-operative neurocognitive decline was observed in 68% of the control group versus only 4% in the intervention group. Although these are impressive findings, a few questions remain unanswered. The authors only mention that the anesthesiologists and intensivists were blinded to the cerebral oximetry values during surgery and in the intensive care unit. Equally important would be if the patients themselves, the rest of the operative care team as well as the personnel performing neurocognitive testing were blinded to the group assignments. Furthermore, a truly blinded study is not possible in this clinical setting. Obviously, more attention will be paid to hemodynamics, and overall management in a patient assigned to the intervention group, and this will have a significant impact on the patient's outcome, independently of cerebral oximetry monitoring. The fact that the most common successful intervention correcting low rSO 2 values back to baseline values were related to blood pressure management supports recent reports about the use of cerebral oximetry in assessing cerebrovascular reactivity and autoregulation. [6] Real-time detection of lower limits of cerebral autoregulation requires more sophisticated monitoring methods that include combining cerebral oximetry with blood pressure and even transcranial Doppler derived cerebral blood flow. However, raising the blood pressure in patients with decreasing rSO 2 values may well be the intervention required in those patients whose autoregulation curves are shifted further to the right.

Many arguments can be brought up when criticizing a study that links monitoring to better patient outcome or for failure of a particular monitoring modality to show benefits. As for the pulmonary artery catheter (PAC), clinicians for almost two decades relied on the assumption that monitoring hemodynamics and oxygenation parameters must improve patient outcome. However, as history taught us, monitoring alone does not improve outcome and in the case of an invasive technique such as the PAC may actually be associated with risks. It is an effective treatment plan based on sound scientific evidence that will improve outcome, and monitoring can at the best help guide such treatment options. In the case of PAC monitoring, many of the diseases (e.g. multi-organ failure, pulmonary hypertension, Acute Respiratory Distress Syndrome ARDS) for which a PAC is (or was) commonly deployed, are too far advanced once clinical manifestations occur, have a grim prognosis and few treatment options shown to improve outcome are available. Not even to mention that the same treatment plan, even when based on appropriate monitoring, interpretation and statistical evidence of outcome benefit, will not necessarily result in improved outcome in every patient. Genetic polymorphism and variations in gene expression have recently been introduced to clinical medicine further complicating this issue. Administering clopidogrel to patients following coronary stent placement for example, will not result in the same outcome in all patients. [7] Two recent reviews and meta-analysis on the use of preemptive hemodynamic intervention showed that monitoring including early recognition of impaired tissue perfusion long before end-organ damage occurs may actually help reduce morbidity and mortality. [8],[9] Cerebral oximetry, being a venous weighted measure has been shown to correlate reasonably well with jugular bulb saturation, and a somewhat inconsistent and weaker correlation with central venous oxygen saturation has been described. Similar to a mixed venous oxygen saturation obtained from PAC monitoring, cerebral oximetry obtained tissue oxygen saturation is often considered to allow insight into the delicate balance between oxygen delivery and demand. Unlike the PAC, the technology is completely non-invasive; however, it must be recognized that some of the interventions available and recommended to correct low rSO 2 such as transfusion of red blood cells to raise a low hematocrit and oxygen carrying capacity are rather invasive and have been linked to poor outcome. It will require many more prospective, randomized studies before we can truly make conclusions about this promising technology. Let's hope we won't be disappointed. In the meantime, we should support studies such as the one by Mohandas et al., who are trying to make the connection between monitoring, intervention (action), and outcome (hopefully success).

 
   References Top

1.Mohandas BS, Jagadeesh AM, Vikram SB. Impact of monitoring cerebral oxygen saturation on the outcome of patients undergoing open heart surgery. Ann Card Anesth 2013;16;102-6.  Back to cited text no. 1
    
2.Vernick WJ, Oware A. Early diagnosis of superior vena cava obstruction facilitated by the use of cerebral oximetry. J Cardiothorac Vasc Anesth 2011;25:1101-3.  Back to cited text no. 2
    
3.McQuillen PS, Barkovich AJ, Hamrick SE, Perez M, Ward P, Glidden DV, et al. Temporal and anatomic risk profile of brain injury with neonatal repair of congenital heart defects. Stroke 2007;38:736-41.  Back to cited text no. 3
    
4.Murkin JM, Adams SJ, Novick RJ, Quantz M, Bainbridge D, Iglesias I, et al. Monitoring brain oxygen saturation during coronary bypass surgery: A randomized, prospective study. Anesth Analg 2007;104:51-8.  Back to cited text no. 4
    
5.Denault A, Deschamps A, Murkin JM. A proposed algorithm for the intraoperative use of cerebral near-infrared spectroscopy. Semin Cardiothorac Vasc Anesth 2007;11:274-81.  Back to cited text no. 5
    
6.Joshi B, Ono M, Brown C, Brady K, Easley RB, Yenokyan G, et al. Predicting the limits of cerebral autoregulation during cardiopulmonary bypass. Anesth Analg 2012;114:503-10.  Back to cited text no. 6
    
7.Al-Azzam SI, Alzoubi KH, Khabour OF, Nusair MB, Al-Hadidi H, Awidi A, et al. Influence of the paraoxonase-1 Q192R genetic variant on clopidogrel responsiveness and recurrent cardiovascular events: a systematic review and meta-analysis. Int J Clin Pharmacol Ther. 2013;51:179-86.  Back to cited text no. 7
    
8.Hamilton MA, Cecconi M, Rhodes A. A systematic review and meta-analysis on the use of preemptive hemodynamic intervention to improve postoperative outcomes in moderate and high-risk surgical patients. Anesth Analg 2011;112:1392-402.  Back to cited text no. 8
    
9.Gurgel ST, do Nascimento P Jr. Maintaining tissue perfusion in high-risk surgical patients: A systematic review of randomized clinical trials. Anesth Analg 2011;112:1384-91.  Back to cited text no. 9
    

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Correspondence Address:
Alexander J.C. Mittnacht
Department of Anesthesiology, The Mount Sinai Medical Center, Box 1010, One Gustave L. Levy Place, New York, NY
USA
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Source of Support: None, Conflict of Interest: None


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