Evaluating the Incidence of Cognitive Disorder Following Off-Pump Coronary Artery Bypasses Surgery and its Predisposing Factors

AUTHORS

Marjan Joudi 1 , Mehdi Fathi 2 , * , Hadi Harati 3 , Mitra Joudi 4 , Azra Izanloo 5 , Ali Rahdari 2 , Ghasem Soltani 2

1 Department of Surgery, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran

2 Deapartment of Anesthesia, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran

3 Department of Neurology, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran

4 Department of Psychiatry, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran

5 Department of Radiologic Technology, Faculty of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran

How to Cite: Joudi M, Fathi M, Harati H, Joudi M, Izanloo A, et al. Evaluating the Incidence of Cognitive Disorder Following Off-Pump Coronary Artery Bypasses Surgery and its Predisposing Factors, Anesth Pain Med. 2014 ; 4(4):e18545. doi: 10.5812/aapm.18545.

ARTICLE INFORMATION

Anesthesiology and Pain Medicine: 4 (4); e18545
Published Online: September 15, 2014
Article Type: Research Article
Received: February 24, 2014
Revised: March 30, 2014
Accepted: April 30, 2014
Crossmark

Crossmark

CHEKING

READ FULL TEXT
Abstract

Background: Cognitive disorder is a fluctuating cognitive destruction and a common problem for hospitalized patients, which leads to loss of consciousness. It is usually accompanied with increased mortality, prolonged hospital stay, and decreased rehabilitation.

Objectives: The purpose of this study was to determine risk factors associated with cognitive disorder after open-heart surgery.

Patients and Methods: In total, 171 patients who had undergone off-pump open-heart surgery and lacked any history of psychiatric disorders were enrolled. Samples were selected according to a purposive sampling method. The Mini-Mental State Examination questionnaire was used for these patients to assess the incidence of cognitive disorder 24 hours after the operation in ICU and to compare creatinine level, ESR, extubation time and patients’ age in the two groups, one with postoperative cognitive disorder and the other without it. Independent T-test was used to compare the two groups regarding any history of diseases such as diabetes, hypertension and hyperlipidemia, Chi square test was used.

Results: In total, 75% of patients had postoperative cognitive disorder. There was a significant association between the history of high blood pressure, C-reactive protein and preoperative creatinine levels in both cognitive disorder and control groups.

Conclusions: Given the significant prevalence of postoperative cognitive disorder and significant associatio n between the history of high blood pressure, C-reactive protein and preoperative creatinine and cognitive disorder, detection of patient’s clinical symptoms may improve diagnosis, treatment and prevention of this disorder.

Keywords

Off-Pump Coronary Artery Bypass Cognitive Disorder Delirium Risk Factors

Copyright © 2014, Iranian Society of Regional Anesthesia and Pain Medicine (ISRAPM). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

1. Background

Cognitive disorder is a fluctuating cognitive disorder commonly seen in hospitalized patients. Cognitive disorder is a type of cognitive disorder occurred in a short time characterized by features such as altered consciousness, reduced concentration and memory, impaired orientation, rapid incidence for several hours to several days, short period and notable fluctuations (mostly at night) (1). The incidence of cognitive disorder in hospitalized patients is accompanied with increased mortality (2-4), prolonged hospital stay (5, 6), increased hospitalization (7), impaired rehabilitation of patients, increased nursing measures (8), prolonged intubation (9), higher risk of falls (2), impaired cognitive functions (5), increased risk of dementia (6), inability to return to work (3), poor quality of life (10) and long-term care (11).

Mortality rate in patients who experienced an episode of cognitive disorder is 23-33% with an annual mortality rate of 50%. Mortality rate in patients who develop cognitive disorder during hospitalization is 20-75%; of whom 15% and 25% die within one and six months, respectively (12). The incidence of cognitive disorder varies in different wards, but the highest rate of cognitive disorder occurs after thoracotomy and cardiology surgeries, which may even reach 90% (4).There are different opinions about causes of cognitive disorders including metabolic encephalopathy, drug toxicity, hypoglycemia, preoperative hypoxemia, visual and hearing impairment, and the type and duration of anesthesia (6, 9). The main postoperative causes include surgical stress, postoperative pain, insomnia, pain control medications, electrolyte disturbances, fever and bleeding (13).

In major operations like heart surgery, considering the complex surgical procedure, the use of anesthetics and relaxants during and after the operation and postoperative complications may increase the incidence of cognitive disorders (14). Besides, postoperative pain may lead to sleep disturbance, increased metabolism, myocardial ischemia, anxiety and cognitive disorder (5). Therefore, it is necessary to identify the prevalence and risk factors associated with cognitive disorders in patients undergoing cardiac surgery and admitted in ICU. Identifying cognitive disorder risk factors may help early diagnosis and reduce complications.

2. Objectives

This study aimed to assess the incidence and risk factors of cognitive disorders in patients after open heart surgery (off pump CABG).

3. Patients and Methods

This descriptive study was performed on 171 patients undergoing elective surgery in Heart Center of Imam Reza Hospital in Mashhad for an 8-month period. The samples size was calculated using NCSS and PASS statistical software with minimum 80% for multiple logistic regression test, significance level of 5%, coefficient of determination of 80%, odds ratio of 2.91 and 0.28, and 0.531 probability of cognitive disorder incidence (15) among 170 patients. Furthermore, samples were selected according to a purposive sampling method. For all patients, echocardiography and carotid Dopplerecho were performed for all patients before the operation.The night before the operation, a psychologist visited patients. In addition, the Millon test was used to evaluate patients regarding any history of cognitive, mood and psychiatric disorders. Furthermore, patients were examined for any sign of psychological disorders.

Patients were ASA class of at least III and even IV. Exclusion criteria were emergency operations, redo operations, carotid stenosis more than 40%, preoperative creatinine >2, history of cognitive disorders, and late extubation >8 hours. Anesthesia was induced using 0.1 mg/kg midazolam, 10 μg/kg fentanyl, 1 mg/kg propofol, and 0.5 mg/kg Atracurium. Anesthesia was maintained during the operation using midazolam 5 mg/h, Atracurium 20 mg/h or propofol 50 μg/kg/min until the end of operation. After transferring to ICU, eligible patients were extubated 4 to 8 hours after the operation. Besides, patients' cognitive disorder score was recorded during the first 24 hours of ICU stay (calculated after extubation) using the Mini Mental State Examination (MMSE). All data entered SPSS software (version 21) and analyzed. To compare creatinine levels, ESR, extubation time and patients’ age in the two groups, one with postoperative cognitive disorder and the other without it, independent T-test was used, and to compare the two groups for any history of diseases such as diabetes, hypertension and hyperlipidemia, Chi square test was used.

4. Results

In this study, there were 171 patients in 64.04 ± 9.84 age group, of which 75% in the age range of 64.26 ± 9.04 had postoperative cognitive disorder. As shown in Table 1, T-test revealed that only preoperative creatinine levels in the two groups, those with and without cognitive disorder symptoms, were significantly different (P = 0.02); while, other factors such as ejection fraction (EF), erythrocyte sedimentation rate (ESR), age and extubation duration were not significantly different. As shown in Table 2, patients with and without postoperative cognitive disorder were significantly different regarding the history of high blood pressure and CRP; while, the two groups were not significantly different regarding the history of stroke, diabetes, and hyperlipidemia.

Table 1. Results of Independent T-test Comparing Age, Extubation Duration, EF and ESR a
VariableWithout Cognitive Disorder Group, n =42With Cognitive Disorder Group, n =129Total, n =171P Value
Cognitive disorder 63.97 ± 10.1464.26 ± 9.0464.04 ± 9.840.868
Creatininelevel1.11 ± 0.331.22 ± 0.351.13 ± 0.340.029
Extubation duration4.95 ± 2.485.42 ± 2.395.16 ± 2.430.236
Preoperative EF48.01 ± 11.3347.43 ± 8.9147.87 ± 10.760.468
ESR--44.69 ± 11.950.354

aData are presented as Mean ± SD

Table 2. Chi-Square Test Results Comparing History of Stroke, Hypertension, Diabetes, Dyslipidemia and Positive CRP in the Two Groups With and Without Postoperative Cognitive Disorder a
VariableWithout Cognitive Disorder Group, n = 42With Postoperative Cognitive Disorder, n = 129P ValueTotal, n =171
CVA2.37.10.1713.5
DM29.535.70.4431
HTN83.761.90.00378.4
HLP49.640.50.347.4
CRP+32800.04540

aData are presented as %.

5. Discussion

In total, 75% of patients had cognitive disorder after off-pump CABG; whereas, the incidence of this syndrome after open-heart surgery had been reported 20% to 45% in other studies (16-18). This was 47% in the study of Ganavati in Iran (19). This difference could be due to a variety of reasons such as study sample size, or using various diagnostic criteria to identify cognitive disorders. Moreover, this study was conducted on an aging population and since most studies introduce age as a risk factor associated with postoperative cognitive complications, older age may increase cognitive disorders (20-22). In the study performed by Miyazaki, high level of serum creatinine was found to be a predisposing factor in patients with cognitive disorder (23), which is confirmed by the present study as well.

In a large body of study, including Miyazaki (23) and Koster (15), it is suggested that history of stroke and high blood pressure can be predisposing factors for severe disorders such as cognitive disorder, whereas the present study suggested that two groups were not significantly different for the history of stroke. Moreover, high blood pressure in the group without cognitive disorder was higher than the groups with postoperative cognitive disorder, which could be due to insufficient sample size. A study conducted in China showed that diabetes could be considered as a risk factor for cognitive disorder (18). Consistent with this finding, in this study, history of diabetes in patients with postoperative cognitive disorder was more common than those without it.According to our results and other studies, main etiology factors for the development of cognitive disorder were hypertension, atherosclerosis(24) and history of drug abuse and senesces.

Overall, given the results of this study and the high incidence of cognitive disorders after open-heart surgery, especially among elderly, preoperative assessment of cognitive function of patients is of utmost importance. Furthermore, complications of cognitive disorder can be controlled in nonemergency surgeries by psychiatric consultation and identifying associated risk factors. Of course, more studies are needed to investigate the effect of these interventions on postoperative cognitive state of patients.

Acknowledgements

Footnote

References

  • 1.

    Trzepacz PT, Sclabassi RJ, Van Thiel DH. Delirium: a subcortical phenomenon? J Neuropsychiatry Clin Neurosci. 1989; 1(3) : 283 -90 [PubMed]

  • 2.

    George C, Nair JS, Ebenezer JA, Gangadharan A, Christudas A, Gnanaseelan LK, et al. Validation of the Intensive Care Delirium Screening Checklist in nonintubated intensive care unit patients in a resource-poor medical intensive care setting in South India. J Crit Care. 2011; 26(2) : 138 -43 [DOI][PubMed]

  • 3.

    Gandhi GY, Nuttall GA, Abel MD, Mullany CJ, Schaff HV, Williams BA, et al. Intraoperative hyperglycemia and perioperative outcomes in cardiac surgery patients. Mayo Clin Proc. 2005; 80(7) : 862 -6 [DOI][PubMed]

  • 4.

    Rezaee F. Translation of Kaplan and Sudock Synopsis of Psyhiatry Behavioral Science. 2007; : 405 -18

  • 5.

    Hall JB, Schweickert W, Kress JP. Role of analgesics, sedatives, neuromuscular blockers, and delirium. Crit Care Med. 2009; 37(10 Suppl) -21 [DOI][PubMed]

  • 6.

    Deiner S, Silverstein JH. Postoperative delirium and cognitive dysfunction. Br J Anaesth. 2009; 103 Suppl 1 -6 [DOI][PubMed]

  • 7.

    Akechi T, Ishiguro C, Okuyama T, Endo C, Sagawa R, Uchida M, et al. Delirium training program for nurses. Psychosomatics. 2010; 51(2) : 106 -11 [DOI][PubMed]

  • 8.

    Flagg B, Cox L, McDowell S, Mwose JM, Buelow JM. Nursing identification of delirium. Clin Nurse Spec. 2010; 24(5) : 260 -6 [DOI][PubMed]

  • 9.

    Pandharipande P, Jackson J, Ely EW. Delirium: acute cognitive dysfunction in the critically ill. Curr Opin Crit Care. 2005; 11(4) : 360 -8 [PubMed]

  • 10.

    Khan BA, Zawahiri M, Campbell NL, Fox GC, Weinstein EJ, Nazir A, et al. Delirium in hospitalized patients: implications of current evidence on clinical practice and future avenues for research--a systematic evidence review. J Hosp Med. 2012; 7(7) : 580 -9 [DOI][PubMed]

  • 11.

    Stransky M, Schmidt C, Ganslmeier P, Grossmann E, Haneya A, Moritz S, et al. Hypoactive delirium after cardiac surgery as an independent risk factor for prolonged mechanical ventilation. J Cardiothorac Vasc Anesth. 2011; 25(6) : 968 -74 [DOI][PubMed]

  • 12.

    Witlox J, Eurelings LS, de Jonghe JF, Kalisvaart KJ, Eikelenboom P, van Gool WA. Delirium in elderly patients and the risk of postdischarge mortality, institutionalization, and dementia: a meta-analysis. JAMA. 2010; 304(4) : 443 -51 [DOI][PubMed]

  • 13.

    Schmitt EM, Marcantonio ER, Alsop DC, Jones RN, Rogers SO, Jr, Fong TG, et al. Novel risk markers and long-term outcomes of delirium: the successful aging after elective surgery (SAGES) study design and methods. J Am Med Dir Assoc. 2012; 13(9) : 818 e1 -10 [DOI][PubMed]

  • 14.

    Maldonado JR, Wysong A, van der Starre PJ, Block T, Miller C, Reitz BA. Dexmedetomidine and the reduction of postoperative delirium after cardiac surgery. Psychosomatics. 2009; 50(3) : 206 -17 [DOI][PubMed]

  • 15.

    Koster S, Hensens AG, Schuurmans MJ, van der Palen J. Risk factors of delirium after cardiac surgery: a systematic review. Eur J Cardiovasc Nurs. 2011; 10(4) : 197 -204 [DOI][PubMed]

  • 16.

    Rolfson DB, McElhaney JE, Rockwood K, Finnegan BA, Entwistle LM, Wong JF, et al. Incidence and risk factors for delirium and other adverse outcomes in older adults after coronary artery bypass graft surgery. Can J Cardiol. 1999; 15(7) : 771 -6 [PubMed]

  • 17.

    Chaput AJ, Bryson GL. Postoperative delirium: risk factors and management: continuing professional development. Can J Anaesth. 2012; 59(3) : 304 -20 [DOI][PubMed]

  • 18.

    Mu DL, Wang DX, Li LH, Shan GJ, Su Y, Yu QJ, et al. [Postoperative delirium is associated with cognitive dysfunction one week after coronary artery bypass grafting surgery]. Beijing Da Xue Xue Bao. 2011; 43(2) : 242 -9 [PubMed]

  • 19.

    Ganavati A, Forooghi M, Esmaeili S, Hasantash SA, Blourain AA, Shahzamani M, et al. The Relation between Post Cardiac Surgery Delirium and Intraoperative Factors. Iran J Surg. 2009; 17(3)

  • 20.

    Kaplan HI, Sadock BJ. Kaplan and Sadock's Synopsis of Psychiatry. 2003;

  • 21.

    Clayer M, Bruckner J. Occult hypoxia after femoral neck fracture. Psychiatry Neural. 1990; 3(4) : 184 -91

  • 22.

    Rockwood K, Cosway S, Carver D, Jarrett P, Stadnyk K, Fisk J. The risk of dementia and death after delirium. Age Ageing. 1999; 28(6) : 551 -6 [PubMed]

  • 23.

    Miyazaki S, Yoshitani K, Miura N, Irie T, Inatomi Y, Ohnishi Y, et al. Risk factors of stroke and delirium after off-pump coronary artery bypass surgery. Interact Cardiovasc Thorac Surg. 2011; 12(3) : 379 -83 [DOI][PubMed]

  • 24.

    Sapryigina LV, Belova LA, Burtsev SV, Belova NV, Elistratova DS, Koroleva AG. The etiology of moderate cognitive disorders (MCD) in a working-age population according to epidemiological studies. J Neurol Sci. 2013; 333[DOI]

  • COMMENTS

    LEAVE A COMMENT HERE: