Postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a decline in cognitive function (especially in memory and executive functions) that may last from 1–12 months after surgery, or longer.[1] In some cases, this disorder may persist for several years after major surgery.[2] POCD is distinct from emergence delirium. Its causes are under investigation and occurs commonly in older patients and those with pre-existing cognitive impairment.[2]

The causes of POCD are not understood. It does not appear to be caused by lack of oxygen or impaired blood flow to the brain[3] and is equally likely under regional and general anesthesia.[2][4] It may be mediated by the body's inflammatory response to surgery.[5][6]

Causes

The body's inflammatory response to surgery likely plays an important role, at least in elderly patients. Various research initiatives during recent years have evaluated whether actions taken before, during and after surgery can lessen the possible deleterious effects of inflammation. For example, anti-inflammatory agents can be given before surgery. During surgery, inflammation can be modulated by temperature control, use of regional rather than general anesthesia or the use of beta blockers. After surgery, optimal pain management and infection control is important.[7] Several studies have shown variable-significance positive effects when a multidisciplinary, multifactorial approach to elderly patient is followed during pre, peri and post-operative care.[5][6]

A Cochrane review explored whether inhalation anaesthetics or intravenous anaesthetics were more likely to cause POCD when used in the elderly for non-cardiac surgery. Seven studies (869 participants) included in the review led to the conclusion that fewer people experienced POCD with total intravenous anaesthesia (TIVA) compared to inhalational anaesthesia. The conclusions, however, rated "low" on GRADE scoring (confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect). [8]

Assessment

Cognitive tests are given prior to operations to establish a baseline. The same tests are again given post-operatively to determine the extent and duration of the decline for POCD. "A project examining adults 55 and older who have major non-cardiac surgeries is finding that 'upward of 30 percent of patients is testing significantly worse than their baseline 3 months later'".[1]

Epidemiology

POCD is common after cardiac surgery, and recent studies have now verified that POCD also exists after major non-cardiac surgery, although at a lower incidence. The risk of POCD increases with age, and the type of surgery is also important because there is a very low incidence associated with minor surgery.[4] POCD is common in adult patients of all ages at hospital discharge after major noncardiac surgery, but only the elderly (aged 60 years or older) are at significant risk for long-term cognitive problems. Patients with POCD are at an increased risk of death in the first year after surgery.[9] Research interest has increased since early 2000, especially as more elderly patients are able to undergo successful minor and major surgeries.[10]

POCD has been studied through various institutions since the inception of the IPOCDS-I study centred in Eindhoven, Netherlands and Copenhagen, Denmark. This study found no causal relationship between cerebral hypoxia and low blood pressure and POCD. Age, duration of anaesthesia, introperative complications, and postoperative infections were found to be associated with POCD.[3]

  • POCD is just as likely to occur after operations under regional anesthesia as under general anesthesia.[2][4]
  • More likely after major operations than minor operations.[9][11][12]
  • More likely after heart operations than other types of surgery.[9][12]
  • More likely in aged than in younger patients.[9][11][12]
  • More likely in older patients with high alcohol intake/abuse.[13]
  • People with higher preoperative ASA physical status scores are more likely to develop POCD.[9][12]
  • People with lower educational level are more likely to develop POCD than those with a higher educational level.[2][9][12]
  • People with prior history of a stroke, even though there is complete functional recovery, are more likely to develop POCD.[9][12]
  • More likely in the elderly with pre-existing declining mental functions, termed mild cognitive impairment (MCI).[14] MCI is a transitional zone between normal mental function and evident Alzheimer's disease or other forms of dementia. It is insidious, and seldom recognized, except in retrospect after affected persons are evidently demented.
  • Delirium[15] and severe worsening of mental function is very likely in those with clinically evident Alzheimer's disease or other forms of dementia, as well as those with a history of delirium after previous operations.[16]

Footnotes
  1. Kaiser Health News (2018) https://www.washingtonpost.com/national/health-science/what-we-know-and-dont-know-about-memory-loss-after-surgery/2018/04/12/0b7e32da-3e32-11e8-955b-7d2e19b79966_story.html
  2. Newman, SD; Stygall, J; Hirani, S; Shaefi, S; Maze, M (2007). "Postoperative cognitive dysfunction after noncardiac surgery: a systematic review". Anesthesiology. 106 (3): 572–90. doi:10.1097/00000542-200703000-00023. PMID 17325517.
  3. Moller, JT; Cluitmans, P; Rasmussen, LS; Houx, P; Rasmussen, H; Canet, J; Rabbitt, P; Jolles, J; Larsen, K; Hanning, CD; Langeron, O; Johnson, T; Lauven, PM; Kristensen, PA; Biedler, A; Van Beem, H; Fraidakis, O; Silverstein, JH; Beneken, JEW; Gravenstein, JS (1998). "Long-term postoperative cognitive dysfunction in the elderly: ISPOCD1 study". The Lancet. 351 (9106): 857–61. doi:10.1016/S0140-6736(97)07382-0. PMID 9525362. Archived from the original on 2011-07-18. Retrieved 2013-09-11.
  4. Rasmussen, LS (2006). "Postoperative cognitive dysfunction: incidence and prevention". Best Practice & Research Clinical Anaesthesiology. 20 (2): 315–30. doi:10.1016/j.bpa.2005.10.011. PMID 16850780.
  5. Stenvall, M; Berggren, M; Lundström, M; Gustafson, Y; Olofsson, B (2011). "A multidisciplinary intervention program improved the outcome after hip fracture for people with dementia—subgroup analyses of a randomized controlled trial". Archives of Gerontology and Geriatrics. 54 (3): e284–9. doi:10.1016/j.archger.2011.08.013. PMID 21930310.
  6. Handoll, HHG; Cameron, ID; Mak, JCS; Finnegan, TP (2009). Cameron, ID (ed.). "Multidisciplinary rehabilitation for older people with hip fractures" (PDF). Cochrane Database of Systematic Reviews (4): CD007125. doi:10.1002/14651858.CD007125.pub2. PMID 19821396.
  7. ScienceDaily (2004-10-29). "Elderly experience long-term cognitive decline after surgery". Durham, North Carolina: Duke University Medical Center. Retrieved 2013-09-08.
  8. Miller, David; Lewis, Sharon R; Pritchard, Michael W; Schofield-Robinson, Oliver J; Shelton, Cliff L; Alderson, Phil; Smith, Andrew F (2018). "Intravenous versus inhalational maintenance of anaesthesia for postoperative cognitive outcomes in elderly people undergoing non-cardiac surgery (Review)". Cochrane Database of Systematic Reviews. 8 (8): CD012317. doi:10.1002/14651858.CD012317.pub2. PMC 6513211. PMID 30129968.
  9. Newfield, P (2009). "Postoperative cognitive dysfunction". F1000 Medicine Reports. 1 (14): 14. doi:10.3410/M1-14. PMC 2920713. PMID 20948768.
  10. McDonagh, DL; Mathew, JP; White, WD; Phillips-Bute, B; Laskowitz, DT; Podgoreanu, MV; Newman, MF; Neurologic Outcome Research, Group (2010). "Cognitive function after major noncardiac surgery, apolipoprotein E4 genotype, and biomarkers of brain injury". Anesthesiology. 112 (4): 852–9. doi:10.1097/ALN.0b013e3181d31fd7. PMC 2933423. PMID 20216394.
  11. Neubauer, RA; Golden, C (2005). "Can postoperative cognitive dysfunction be prevented?" (PDF). Journal of American Physicians and Surgeons. 10 (1): 22.
  12. Monk, TG; Weldon, BC; Garvan, CW; Dede, DE; Van Der Aa, MT; Heilman, KM; Gravenstein, JS (2008). "Predictors of cognitive dysfunction after major noncardiac surgery". Anesthesiology. 108 (1): 18–30. doi:10.1097/01.anes.0000296071.19434.1e. PMID 18156878.
  13. Hudetz, JA; Iqbal, Z; Gandhi, SD; Patterson, KM; Hyde, TF; Reddy, DM; Hudetz, AG; Warltier, DC (2007). "Postoperative cognitive dysfunction in older patients with a history of alcohol abuse". Anesthesiology. 106 (3): 423–30. CiteSeerX 10.1.1.599.9529. doi:10.1097/00000542-200703000-00005. PMID 17325499.
  14. Tully, P; Baune, B; Baker, R (2013). "Cognitive impairment before and six months after cardiac surgery increase mortality risk at median 11 year follow-up: a cohort study". International Journal of Cardiology. 168 (3): 2796–802. doi:10.1016/j.ijcard.2013.03.123. PMID 23623665.
  15. Huang, J (2013). "Overview of delirium and dementia". The Merck manual for healthcare professionals. Whitehouse Station, New Jersey: Merck Sharp & Dohme Corporation, Inc.
  16. Meagher, DJ (2001). "Delirium: optimising management". BMJ. 322 (7279): 144–9. doi:10.1136/bmj.322.7279.144. PMC 1119415. PMID 11159573.

Further reading
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