Correspondence
Declaration of interest None declared. E. Base* M. Dworschak K. Skhirtladze-Dworschak A. Lassnigg Vienna, Austria *E-mail: [email protected] 1 Skhirtladze K, Base EM, Lassnigg A, et al. Comparison of the effect of albumin 5%, hydroxyethyl starch 130/0.4 6%, and Ringer’s lactate on blood loss and coagulation after surgery. Br J Anaesth 2014; 112: 255–64 2 Base EM, Standl T, Lassnigg A, et al. Efficacy and safety of hydroxyethyl starch 6% 130/0.4 in a balanced electrolyte solution (Volulyte) during cardiac surgery. J Cardiothorac Vasc Anesth 2011; 25: 407–14 3 Lassnigg A, Schmid ER, Hiesmayr M, et al. Impact of minimal increases in serum creatinine on outcome in patients after cardiothoracic surgery: do we have to revise current definitions of acute renal failure? Crit Care Med 2008; 36: 1129–37 4 Van Der Linden P, James M, Mythen M, Weiskopf RB. Safety of modern starches used during surgery. Anesth Analg 2013; 116: 35 –48 5 Kasper SM, Meinert P, Kampe S, et al. Large-dose hydroxyethyl starch 130/0.4 does not increase blood loss and transfusion requirements
in coronary artery bypass surgery compared with hydroxyethyl starch 200/0.5 at recommended doses. Anesthesiology 2003; 99: 42 – 7 6 Lee JS, Ahn SW, Song JW, Shim JK, Yoo KJ, Kwak YL. Effect of hydroxyethyl starch 130/0.4 on blood loss and coagulation in patients with recent exposure to dual antiplatelet therapy undergoing off-pump coronary artery bypass graft surgery. Circ J 2011; 75: 2397– 402 7 Van der Linden PJ, De Hert SG, Deraedt D, et al. Hydroxyethyl starch 130/0.4 versus modified fluid gelatin for volume expansion in cardiac surgery patients: the effects on perioperative bleeding and transfusion needs. Anesth Analg 2005; 101: 629– 34 8 Enriquez LJ, Shore-Lesserson L. Point-of-care coagulation testing and transfusion algorithms. Br J Anaesth 2009; 103(Suppl 1): i14– 22
doi:10.1093/bja/aeu470
Depth of anaesthesia optimisation and postoperative cognitive dysfunction Editor—We were very interested to read the excellent review in the March issue of the British Journal of Anaesthesia entitled ‘Perioperative cognitive trajectory in adults’.1 However, we feel that the overall impression that anaesthetists may gain from reading this review will be that anaesthesia is an unimportant component in the production of postoperative cognitive dysfunction (POCD). While pre-existing trajectories of cognitive decline are undoubtedly important in predicting a patient’s fate from anaesthesia and surgery in this regard, we think it would be wrong to suggest that ‘any old anaesthetic’ will do, particularly for our elderly population. We agree with the authors that when anaesthesia is optimised and surgery is successful, patients may not suffer significant, long-term cognitive decline and may indeed expect to have some degree of cognitive improvement. However, how do we know that anaesthesia is optimised in a particular patient unless we measure overall oxygen delivery, and in particular what is going on in the brain?2 The authors allude to this possibility when they mention a randomised controlled trial (RCT) carried out in our own unit using cerebral oxygenation and ‘depth of anaesthesia’ or, better, degree of cortical suppression optimised to a range where neurotoxicity would be minimised and neural protection maximised.3 However, one of the largest proof-of-concept RCTs investigating depth of anaesthesia monitoring and POCD was not mentioned. This was the Cognitive Dysfunction after Anaesthesia (CODA) trial from Hong Kong, where more than 900 elderly patients were randomised to an intervention that maintained the bispectral index (BIS) in the 40 –60 range vs a control group where anaesthesia was administered as usual.4 The important point about this trial is that the investigators were able to maintain an average BIS (Covidien, USA) of 53 in the intervention group vs 36 in the control group. This not only resulted in a significant decrease in POCD, but also in postoperative delirium, which we acknowledge is a cause of significant postoperative morbidity. Interestingly, another even larger RCT using BIS from Berlin showed a reduction in postoperative delirium but not POCD. This was possibly due to the fact that the overall average BIS
343
Downloaded from http://bja.oxfordjournals.org/ at Rudolph Matas Medical Library on January 22, 2015
resulting in a higher transfusion rate in each of these two groups. Therefore, our study is well in line with others demonstrating no increased blood loss with the use of hydroxyethyl starches but increased transfusion rates in patients treated with starches when compared with electrolyte solutions.4 It is correct that fluid administration in our trial did not follow a goal directed therapy protocol. It rather relied on the subjective treatment options of experienced staff anaesthesiologists. The decision to not consider a goal directed therapy protocol for patient management was based on two reasons: first, changes in preload, afterload and contractility occur rapidly particularly when going off bypass. This greatly impedes the applicability of a strict goal directed protocol. Secondly, at present, there is no consensus on a clinically robust haemodynamic or metabolic variable that clearly defines adequate volume therapy during frequently changing haemodynamic conditions. This may also be the reason why other researchers refrained from using a strict goal directed fluid regimen, too.5 – 7 One can argue whether thromboelastography is the ideal foundation to guide transfusion of fresh frozen plasma and platelets. Nevertheless, it is frequently employed in cardiac surgery as a simple point-of-care test that provides important information on blood coagulation. Moreover, transfusion algorithms based on thromboelastography have been shown to reduce both transfusion requirements and blood loss in cardiac surgery.8 Logistic reasons have not specifically been mentioned in our article. They comprise the usual obstacles we face in our daily work like: ICU beds not being available for recruited patients, changes in the booking of enrolled patients, and availability of staff involved in the study.
BJA
BJA
Correspondence
level was the same in both the control and intervention groups.5 The above mentioned proof-of-concept trials demonstrate that optimal intraoperative management of patients not only have an important role in reducing the incidence of POCD, particularly in elderly patients, but also may lead to an improvement in outcome generally following major surgery.6 It would be very unfortunate if such an excellent review left anaesthetists feeling that POCD was not really much of a problem and even if it was, there was nothing they could do about it. As our population ages, we can no longer be complacent about how our intraoperative management may affect postoperative outcome, and not only in POCD.
David Green has received monitoring equipment, travelling expenses, and honoraria from Covidien. D. Green* C. Ballard G. Kunst London, UK *E-mail: [email protected]
1 Nadelson MR, Sanders RD, Avidan MS. Perioperative cognitive trajectory in adults. Br J Anaesth 2014; 112: 440– 51 2 Bidd H, Tann A, Green DW. Using bispectral index and cerebral oximetry to guide hemodynamic therapy in high-risk surgical patients. Perioper Med 2013; 2: 1–9 3 Ballard C, Jones E, Gauge N, et al. Optimised anaesthesia to reduce post operative cognitive decline (POCD) in older patients undergoing elective surgery, a randomised controlled trial. PLoS One 2012; 7: e37410 4 Chan MT, Cheng BC, Lee TM, Gin T. BIS-guided anesthesia decreases postoperative delirium and cognitive decline. J Neurosurg Anesthesiol 2013; 25: 33– 42 5 Radtke FM, Franck M, Lendner J, Kruger S, Wernecke KD, Spies CD. Monitoring depth of anaesthesia in a randomized trial decreases the rate of postoperative delirium but not postoperative cognitive dysfunction. Br J Anaesth 2013; 110(Suppl. 1): i98–105 6 Green D, Bidd H, Rashid H. Multimodal intraoperative monitoring: an observational case series in high risk patients undergoing major peripheral vascular surgery. Int J Surg 2014; 12: 231– 6
doi:10.1093/bja/aeu471
Neurotoxicity of general anaesthesia is hypothetical Reply from the authors Editor—We thank Drs Green, Ballard, and Kunst for their interest in our review article and for their letter. We agree that one of the impressions which anaesthetists may gain from reading our review is that the choice of anaesthetic technique is unlikely to be a major component in the production of postoperative cognitive decline, and moreover, that the
344
Downloaded from http://bja.oxfordjournals.org/ at Rudolph Matas Medical Library on January 22, 2015
Declaration of interest
evidence for persistent cognitive decline attributable to either surgery or anaesthesia remains inconclusive and controversial.1 We certainly did not mean to suggest that ‘any old anaesthetic’ is acceptable for vulnerable older patients, who might be at risk for such complications as covert stroke, myocardial infarction, and acute tubular necrosis. Minimizing perioperative stress and preventing physiological perturbation is very likely to promote improved postoperative outcomes.2 However, it is not even established that regional anaesthesia is associated with improved cognitive outcomes compared with general anaesthesia,3 let alone that in the absence of physiological derangement slightly lighter general anaesthesia is superior in this regard to deeper anaesthesia. The notion that an isolated general anaesthetic is neurotoxic in older adults is currently speculative.4 Notably, a recent seminal 280 patient randomized controlled trial by Sauer and colleagues5 found that at 7.5 yr follow-up, patients who had undergone off-pump coronary artery bypass surgery had similar or even better cognitive performance than patients who had undergone percutaneous coronary intervention. In his editorial contextualizing this trial, Selnes6 stated, ‘This study by Sauer and associates adds to a long list of previous studies that by now have convincingly demonstrated that surgical interventions for coronary artery disease are not associated with a higher risk of late cognitive decline or Alzheimer’s disease than medical or nonsurgical interventions.’ The control group in this trial had neither heart surgery nor general anaesthesia, yet faired no better cognitively in the long term than those who were exposed to major surgery and lengthy general anaesthesia. The proof-of-concept CODA trial7 and the trial conducted by Ballard and colleagues8 are certainly important and give pause for thought. The same is true for studies by Radtke and colleagues9 and Sieber and colleagues,10 which, like the CODA trial, found decreased postoperative delirium with lighter general anaesthesia. But all these studies are preliminary; they are hypothesis generating and require independent replication. The scientific literature is replete with initial positive trials that impacted the standard of care but were not replicated in subsequent studies.11 Although the CODA trial found an increase in delirium in the deep anaesthesia group, there was, surprisingly, also a non-significant decrease in postoperative mortality in the deep anaesthesia group.7 The nested, randomized controlled trial by Ballard and colleagues8 included only 81 patients (with 73 contributing to the data analysis), and could therefore not provide a precise estimate regarding a reduction in postoperative cognitive decline with bispectral index- and cerebral oximetry-guided anaesthesia. We agree with Drs Green, Ballard, and Kunst that anaesthetists should not be complacent regarding the impact of perioperative management on postoperative outcomes, especially in relation to older, more vulnerable surgical patients. However, we also hope that the positive message in our article resonates with the readership of the British Journal of Anaesthesia; when surgery treats pain, decreases inflammation, and improves quality of life, postoperative cognitive improvement is a possible and desirable outcome.
Declaration of interest None declared. E. Base* M. Dworschak K. Skhirtladze-Dworschak A. Lassnigg Vienna, Austria *E-mail: [email protected] 1 Skhirtladze K, Base EM, Lassnigg A, et al. Comparison of the effect of albumin 5%, hydroxyethyl starch 130/0.4 6%, and Ringer’s lactate on blood loss and coagulation after surgery. Br J Anaesth 2014; 112: 255–64 2 Base EM, Standl T, Lassnigg A, et al. Efficacy and safety of hydroxyethyl starch 6% 130/0.4 in a balanced electrolyte solution (Volulyte) during cardiac surgery. J Cardiothorac Vasc Anesth 2011; 25: 407–14 3 Lassnigg A, Schmid ER, Hiesmayr M, et al. Impact of minimal increases in serum creatinine on outcome in patients after cardiothoracic surgery: do we have to revise current definitions of acute renal failure? Crit Care Med 2008; 36: 1129–37 4 Van Der Linden P, James M, Mythen M, Weiskopf RB. Safety of modern starches used during surgery. Anesth Analg 2013; 116: 35 –48 5 Kasper SM, Meinert P, Kampe S, et al. Large-dose hydroxyethyl starch 130/0.4 does not increase blood loss and transfusion requirements
in coronary artery bypass surgery compared with hydroxyethyl starch 200/0.5 at recommended doses. Anesthesiology 2003; 99: 42 – 7 6 Lee JS, Ahn SW, Song JW, Shim JK, Yoo KJ, Kwak YL. Effect of hydroxyethyl starch 130/0.4 on blood loss and coagulation in patients with recent exposure to dual antiplatelet therapy undergoing off-pump coronary artery bypass graft surgery. Circ J 2011; 75: 2397– 402 7 Van der Linden PJ, De Hert SG, Deraedt D, et al. Hydroxyethyl starch 130/0.4 versus modified fluid gelatin for volume expansion in cardiac surgery patients: the effects on perioperative bleeding and transfusion needs. Anesth Analg 2005; 101: 629– 34 8 Enriquez LJ, Shore-Lesserson L. Point-of-care coagulation testing and transfusion algorithms. Br J Anaesth 2009; 103(Suppl 1): i14– 22
doi:10.1093/bja/aeu470
Depth of anaesthesia optimisation and postoperative cognitive dysfunction Editor—We were very interested to read the excellent review in the March issue of the British Journal of Anaesthesia entitled ‘Perioperative cognitive trajectory in adults’.1 However, we feel that the overall impression that anaesthetists may gain from reading this review will be that anaesthesia is an unimportant component in the production of postoperative cognitive dysfunction (POCD). While pre-existing trajectories of cognitive decline are undoubtedly important in predicting a patient’s fate from anaesthesia and surgery in this regard, we think it would be wrong to suggest that ‘any old anaesthetic’ will do, particularly for our elderly population. We agree with the authors that when anaesthesia is optimised and surgery is successful, patients may not suffer significant, long-term cognitive decline and may indeed expect to have some degree of cognitive improvement. However, how do we know that anaesthesia is optimised in a particular patient unless we measure overall oxygen delivery, and in particular what is going on in the brain?2 The authors allude to this possibility when they mention a randomised controlled trial (RCT) carried out in our own unit using cerebral oxygenation and ‘depth of anaesthesia’ or, better, degree of cortical suppression optimised to a range where neurotoxicity would be minimised and neural protection maximised.3 However, one of the largest proof-of-concept RCTs investigating depth of anaesthesia monitoring and POCD was not mentioned. This was the Cognitive Dysfunction after Anaesthesia (CODA) trial from Hong Kong, where more than 900 elderly patients were randomised to an intervention that maintained the bispectral index (BIS) in the 40 –60 range vs a control group where anaesthesia was administered as usual.4 The important point about this trial is that the investigators were able to maintain an average BIS (Covidien, USA) of 53 in the intervention group vs 36 in the control group. This not only resulted in a significant decrease in POCD, but also in postoperative delirium, which we acknowledge is a cause of significant postoperative morbidity. Interestingly, another even larger RCT using BIS from Berlin showed a reduction in postoperative delirium but not POCD. This was possibly due to the fact that the overall average BIS
343
Downloaded from http://bja.oxfordjournals.org/ at Rudolph Matas Medical Library on January 22, 2015
resulting in a higher transfusion rate in each of these two groups. Therefore, our study is well in line with others demonstrating no increased blood loss with the use of hydroxyethyl starches but increased transfusion rates in patients treated with starches when compared with electrolyte solutions.4 It is correct that fluid administration in our trial did not follow a goal directed therapy protocol. It rather relied on the subjective treatment options of experienced staff anaesthesiologists. The decision to not consider a goal directed therapy protocol for patient management was based on two reasons: first, changes in preload, afterload and contractility occur rapidly particularly when going off bypass. This greatly impedes the applicability of a strict goal directed protocol. Secondly, at present, there is no consensus on a clinically robust haemodynamic or metabolic variable that clearly defines adequate volume therapy during frequently changing haemodynamic conditions. This may also be the reason why other researchers refrained from using a strict goal directed fluid regimen, too.5 – 7 One can argue whether thromboelastography is the ideal foundation to guide transfusion of fresh frozen plasma and platelets. Nevertheless, it is frequently employed in cardiac surgery as a simple point-of-care test that provides important information on blood coagulation. Moreover, transfusion algorithms based on thromboelastography have been shown to reduce both transfusion requirements and blood loss in cardiac surgery.8 Logistic reasons have not specifically been mentioned in our article. They comprise the usual obstacles we face in our daily work like: ICU beds not being available for recruited patients, changes in the booking of enrolled patients, and availability of staff involved in the study.
BJA
BJA
Correspondence
level was the same in both the control and intervention groups.5 The above mentioned proof-of-concept trials demonstrate that optimal intraoperative management of patients not only have an important role in reducing the incidence of POCD, particularly in elderly patients, but also may lead to an improvement in outcome generally following major surgery.6 It would be very unfortunate if such an excellent review left anaesthetists feeling that POCD was not really much of a problem and even if it was, there was nothing they could do about it. As our population ages, we can no longer be complacent about how our intraoperative management may affect postoperative outcome, and not only in POCD.
David Green has received monitoring equipment, travelling expenses, and honoraria from Covidien. D. Green* C. Ballard G. Kunst London, UK *E-mail: [email protected]
1 Nadelson MR, Sanders RD, Avidan MS. Perioperative cognitive trajectory in adults. Br J Anaesth 2014; 112: 440– 51 2 Bidd H, Tann A, Green DW. Using bispectral index and cerebral oximetry to guide hemodynamic therapy in high-risk surgical patients. Perioper Med 2013; 2: 1–9 3 Ballard C, Jones E, Gauge N, et al. Optimised anaesthesia to reduce post operative cognitive decline (POCD) in older patients undergoing elective surgery, a randomised controlled trial. PLoS One 2012; 7: e37410 4 Chan MT, Cheng BC, Lee TM, Gin T. BIS-guided anesthesia decreases postoperative delirium and cognitive decline. J Neurosurg Anesthesiol 2013; 25: 33– 42 5 Radtke FM, Franck M, Lendner J, Kruger S, Wernecke KD, Spies CD. Monitoring depth of anaesthesia in a randomized trial decreases the rate of postoperative delirium but not postoperative cognitive dysfunction. Br J Anaesth 2013; 110(Suppl. 1): i98–105 6 Green D, Bidd H, Rashid H. Multimodal intraoperative monitoring: an observational case series in high risk patients undergoing major peripheral vascular surgery. Int J Surg 2014; 12: 231– 6
doi:10.1093/bja/aeu471
Neurotoxicity of general anaesthesia is hypothetical Reply from the authors Editor—We thank Drs Green, Ballard, and Kunst for their interest in our review article and for their letter. We agree that one of the impressions which anaesthetists may gain from reading our review is that the choice of anaesthetic technique is unlikely to be a major component in the production of postoperative cognitive decline, and moreover, that the
344
Downloaded from http://bja.oxfordjournals.org/ at Rudolph Matas Medical Library on January 22, 2015
Declaration of interest
evidence for persistent cognitive decline attributable to either surgery or anaesthesia remains inconclusive and controversial.1 We certainly did not mean to suggest that ‘any old anaesthetic’ is acceptable for vulnerable older patients, who might be at risk for such complications as covert stroke, myocardial infarction, and acute tubular necrosis. Minimizing perioperative stress and preventing physiological perturbation is very likely to promote improved postoperative outcomes.2 However, it is not even established that regional anaesthesia is associated with improved cognitive outcomes compared with general anaesthesia,3 let alone that in the absence of physiological derangement slightly lighter general anaesthesia is superior in this regard to deeper anaesthesia. The notion that an isolated general anaesthetic is neurotoxic in older adults is currently speculative.4 Notably, a recent seminal 280 patient randomized controlled trial by Sauer and colleagues5 found that at 7.5 yr follow-up, patients who had undergone off-pump coronary artery bypass surgery had similar or even better cognitive performance than patients who had undergone percutaneous coronary intervention. In his editorial contextualizing this trial, Selnes6 stated, ‘This study by Sauer and associates adds to a long list of previous studies that by now have convincingly demonstrated that surgical interventions for coronary artery disease are not associated with a higher risk of late cognitive decline or Alzheimer’s disease than medical or nonsurgical interventions.’ The control group in this trial had neither heart surgery nor general anaesthesia, yet faired no better cognitively in the long term than those who were exposed to major surgery and lengthy general anaesthesia. The proof-of-concept CODA trial7 and the trial conducted by Ballard and colleagues8 are certainly important and give pause for thought. The same is true for studies by Radtke and colleagues9 and Sieber and colleagues,10 which, like the CODA trial, found decreased postoperative delirium with lighter general anaesthesia. But all these studies are preliminary; they are hypothesis generating and require independent replication. The scientific literature is replete with initial positive trials that impacted the standard of care but were not replicated in subsequent studies.11 Although the CODA trial found an increase in delirium in the deep anaesthesia group, there was, surprisingly, also a non-significant decrease in postoperative mortality in the deep anaesthesia group.7 The nested, randomized controlled trial by Ballard and colleagues8 included only 81 patients (with 73 contributing to the data analysis), and could therefore not provide a precise estimate regarding a reduction in postoperative cognitive decline with bispectral index- and cerebral oximetry-guided anaesthesia. We agree with Drs Green, Ballard, and Kunst that anaesthetists should not be complacent regarding the impact of perioperative management on postoperative outcomes, especially in relation to older, more vulnerable surgical patients. However, we also hope that the positive message in our article resonates with the readership of the British Journal of Anaesthesia; when surgery treats pain, decreases inflammation, and improves quality of life, postoperative cognitive improvement is a possible and desirable outcome.
