Delirium after coronary artery bypass surgery

Delirium and depression in cardiac surgery: A comprehensive review of risk factors, pathophysiology, and management

BACKGROUND

Mental health and wellbeing continue to gain more attention as they are inextricably associated with clinical outcomes, particularly quality of life. Many medical ailments and major surgeries affect patients' mental health, including depression and delirium.

AIMS

The objective of this manuscript was to comprehensively review and critically examine the literature pertaining to cardiac surgery, depression, and delirium.

METHODS

This is a narrative review article. We performed our search analysis by using the following key words: "Cardiac Surgery", "Depression", "Delirium", "Clinical outcomes", and "Mental Health". Search analysis was done on MedLine PubMed, accessing indexed peer-reviewed publications.

RESULTS

Cardiac Surgery is a life-altering intervention indicated to improve morbidity and mortality in patients with cardiovascular diseases. Psychiatric conditions before and after cardiac surgery worsen patient prognosis and increase mortality rate. Specifically, preoperative depression increases postoperative depression and is associated with impaired functional status, slow physical recovery, and an increased readmission rate.

DISCUSSION

Although the exact pathophysiology between depression and cardiovascular disease (CVD) is unknown, several pathways have been implicated. Unmanaged depression can also lead to other psychological conditions such as delirium. Like depression, the exact association between delirium and CVD is not well understood, but believed to be multifactorial.

CONCLUSION

Herein, we provide a comprehensive review of the links between depression, delirium, and cardiovascular surgery. We critically examine the current data that pertains to the pathophysiology of these debilitating mental health issues in the context of cardiac surgery. Finally, we summarize the various treatment options available for managing depression and delirium in the cardiac surgery patient population.

Evaluation and Treatment of Agitation in the Intensive Care Unit

Agitation in the intensive care unit (ICU) patient is a complication of severe medical illness that requires prompt attention and treatment. The first step in managing an agitated ICU patient is a thorough investigation for factors that may cause or predispose to the agitated state. This entails detailed review of the history and available laboratory data as well as examination of the patient's physical and mental status. Important factors that may contribute to the development of agitation include (1) the presence of delirium or psychosis; (2) the type of ICU setting (e.g., coronary, surgical, respiratory, or medical); (3) a history of psychiatric disorder; (4) a history of central nervous system disorder; and (5) patients' personalities, which affect their reactions to illness and its treatment. The treatment of agitation is then based on its identified causes. The principles of treatment include (1) correction of metabolic and systemic abnormalities, (2) elimination of drug toxicity, (3) treatment of drug withdrawal, (4) maximization of the patient's comfort, and (5) use of neuroleptic medication. Medically oriented psychiatric consultants can help to organize the evaluation and management of the agitated patient and can assist staff members in dealing with their emotional reactions to difficult management problems.

Treatment of delirium following cardiac surgery

Postoperative delirium is a common medical complication following cardiac surgery. This paper will outline the treatment options for delirium with a focus on prophylactic use of risperidone before cardiac surgery.

Panvascular inflammation and mechanisms of injury in perioperative CNS outcomes

In this review, the evidence for inflammatory processes as being of fundamental importance in end-organ dysfunction- specifically stroke and neurocognitive impairment in patients undergoing cardiac surgery-will be reviewed. The risk of central nervous system (CNS) impairment following an off-pump cardiac surgery will be contrasted with that of patients undergoing percutaneous coronary intervention (PCI) or medical management, and the role of progression of underlying cerebrovascular disease and, in particular, panvascular inflammation as an accompaniment to unstable angina with attendant risk of stroke will be explored. In addition, the various roles of preoperative comorbidities, aortic atheroma, and the use of selective avoidance of aortic instrumentation as well as carotid endarterectomy as risk modification strategies will be evaluated. Finally, a summary of recommendations for strategies to decrease risk of perioperative CNS impairment will be presented.

Delirium in the postoperative cardiac patient: a review

BACKGROUND AND AIM OF REVIEW: Cardiac surgery is increasingly common and relatively safe, but there are frequent reports of neuropsychiatric sequelae occurring in the postoperative period. One of the most common neuropsychiatric presentations of cardiac surgery is delirium, also called postcardiotomy delirium (PCD). Despite the vast numbers of cardiac surgeries performed today, there is a paucity of data on risk factors and management options of PCD available to the clinician. This review aims to summarize available information, increase clinicians' awareness of PCD and suggest effective management of this illness.

METHODS

Our literature search was completed using the databases Medline and CINAHL; it was limited to human and English language studies from 1964 to the present. Search terms included "delirium," "agitation," "postoperative," "cardiac," "neuropsychiatric," "neuroleptics," "psychosis," "surgery," "treatment," "postcardiotomy," and "pharmacotherapy."

RESULTS

Our review of the literature revealed several risk factors for PCD, as well as various options for its pharmacological management.

CONCLUSIONS

A multifactorial model should be applied when considering risk stratification for and prevention of delirium postoperatively. Pharmacologically, conventional antipsychotic agents, such as haloperidol, have long been used to manage delirium. In light of haloperidol's side effects, particularly those applicable to the cardiac patient, further research is required into the role of second generation antipsychotics. These agents are common in clinical use, and may be the preferred medications.

Coronary artery bypass grafting (CABG) and cognitive decline: a review

Coronary artery bypass grafting (CABG) is a worldwide used myocardial revascularization procedure, which despite the modern advantages still has a spectrum of complications. The relatively old age of the patients who undergo CABG and their widespread atherosclerotic disease are possible reasons for vascular sequels particularly those leading to neurological dysfunction. Immediate, early and late cognitive decline is a known- and well-defined outcome of CABG. Whereas a lot of data was collected through the last years regarding to neuropsychological dysfunction after CABG, nevertheless etiology and mechanisms of this phenomenon remain unresolved and they are probably multifactorial. Meticulously preoperative assessment of those patients with a potential risk of adverse neurocognitive outcomes can help clinicians to select the mode of revascularization and to better counsel patients about the risks and benefits of surgery versus more conservative kinds of treatment.

Depression with irritability in patients undergoing coronary artery bypass graft surgery: the cardiologist's role

The purpose of this study was to investigate the determinants and maintenance factors of depression in patients undergoing coronary artery bypass graft (CABG) surgery. Fifty CABG candidates were selected randomly for evaluation before and after surgery. Depressive disorders occurred in 22.0% of the patients preoperatively and 21% postoperatively. Irritability as a symptom was more prevalent in depressed than nondepressed patients preoperatively (P=.04) and postoperatively (P=.006). Although depression was the most prevalent diagnosis in the patients' psychiatric histories and evaluations, benzodiazepines were prescribed more frequently than antidepressants (70% vs 3%). Cardiologists should consider that the irritability in some patients undergoing CABG may obscure the diagnosis of depression. The correct recognition of depression is essential to reduce inappropriate benzodiazepine prescription and to apply appropriate treatment.

Neurobehavioural sequelae of cardiopulmonary bypass

The development of coronary artery bypass grafting (CABG) and its effect on angina is the product of a series of technical and scientific advances. Despite these advances, however, adverse neurobehavioural outcomes continue to occur. Stroke is the most serious complication of CABG, but studies that have identified demographic and medical risk factors available before surgery are an important advance. Short-term cognitive deficits are common after CABG, but may not be specific to this procedure. However, deficits in some cognitive areas such as visuoconstruction persist over time, and may reflect parieto-occipital watershed area injury secondary to hypoperfusion or embolic factors. Risk factors for cognitive decline may be time dependent, with short-term studies identifying factors that differ from those of long-term studies. Patients with depression before surgery are likely to have persistent depression afterwards. However, depression does not account for the cognitive decline after CABG. Since CABG is increasingly done in older patients with more comorbidity, the challenge is to identify patients at risk of adverse neurocognitive outcomes and to protect them by modification of the surgical procedure or by effective medical therapy.

Cerebral dysfunction after coronary artery bypass grafting done with mild or moderate hypothermia

OBJECTIVE

Ninety-nine patients undergoing elective coronary artery bypass grafting were enrolled in a prospective, randomized study to evaluate the incidence of cerebral dysfunction after "mild" or "moderate" hypothermia during cardiopulmonary bypass.

METHODS

Patients were evaluated before and after operation before hospital discharge and in some cases at follow-up at least 6 weeks later with a complete neurologic examination (85 patients) and a battery of standard neuropsychometric tests (86 patients).

RESULTS

Postoperative changes detected by neurologic examination consisted of the appearance of new primitive reflexes in both groups. No statistically significant differences in incidence were found. The neuropsychometric performances of the two groups were statistically similar by either event-rate or group-rate analysis.

CONCLUSIONS

There is no detectable difference in postoperative cerebral dysfunction in patients undergoing coronary artery bypass grafting who are supported by cardiopulmonary bypass with either mild or moderate hypothermia.

A randomized trial comparing safety and efficacy of OKT3 and a monoclonal anti-interleukin-2 receptor antibody (BT563) in the prevention of acute rejection after heart transplantation

In a prospective randomized trial, BT563, a murine IgG, anti-interleukin-2 receptor antibody, was compared with OKT3 for use as an early rejection prophylaxis after heart transplantation. Patients received either BT563 (n=31) or OKT3 (n=29) during the first 7 days after transplantation; cyclosporine was started on day 3. Median follow-up was 34 months. A cytokine release syndrome occurred in the majority of patients of the OKT3-treated group but in none of the BT563 recipients. The mean duration of electrical stimulation of the heart in the BT563 group was longer than in the OKT3 group (5.1 vs. 2.1 days). In both groups, one patient required insertion of a permanent pacemaker. Freedom from acute rejection at 3 months was not significantly different between the two groups (BT563: 5/29, 17%; OKT3: 6/29, 21%). In the BT563 group, however, rejection tended to occur earlier after transplantation. There was no difference in the overall incidence of rejection. The incidence of infectious complications was evenly distributed in both groups. Malignancies occurred in two patients, both in the OKT3 group. In conclusion, the use of this anti-interleukin-2 receptor monoclonal antibody in heart transplant recipients is safe and devoid of the side effects that accompany the use of OKT3. OKT3 and BT563 result in a similar freedom from rejection at 3 and 12 months after heart transplantation.

Delirium after cardiac surgery: a critical review

Numerous articles have been published investigating the incidence of and risk factors for delirium after cardiac surgery. Smith and Dimsdale reviewed the literature on postcardiotomy delirium in 1987 using a meta-analysis of 44 research studies. However, doubts about their methods and results caused the authors to re-examine the literature using these 44 references as well as computerized literature searches to gather research and review papers from medical journals. Delirium after cardiac surgery appeared to be ill-defined in most of these studies. The methods and instruments used to assess delirium proved to be very different, and the patient samples were rather heterogeneous. Therefore, in most cases, the results are not comparable. Only a small number of the studies that were examined fit the criteria for statistical meta-analysis. On the basis of our analysis, a tentative conclusion may be drawn that the incidence of postcardiotomy delirium has declined slightly and that no strong risk factors have yet been identified.

Nitrous oxide and cerebrospinal fluid markers of ischaemia following cardiopulmonary bypass

Twenty patients with good ventricular function undergoing coronary artery bypass surgery were studied to determine whether the pre-bypass use of nitrous oxide resulted in any differences in cerebrospinal fluid markers indicative of cerebral ischaemia. All patients were anaesthetised with diazepam, fentanyl and pancuronium, after which ten patients received 50-60% nitrous oxide in oxygen until commencement of bypass, and the remaining patients 100% oxygen. Because of the known effect of nitrous oxide in expanding gaseous bubbles, any neurological dysfunction of gaseous microembolic origin may be worsened in the presence of nitrous oxide. Patients were lumbar punctured 24 hours after cardiopulmonary bypass and cerebrospinal fluid analysed for the following markers of central nervous system ischaemia: creatine kinase, lactate, total protein, noradrenaline, adrenaline and adenylate kinase. There was a statistically significant difference in cerebrospinal fluid lactate between the two groups. There were no statistically significant differences in the other cerebrospinal fluid markers of ischaemia.

[Delirium following heart surgery with extracorporeal circulation: clinical aspects and observations in a specialized center]

Delirium following heart surgery with extra-corporeal circulation recently has been the subject of several studies that show a syndrome with variable diagnostic criteria and incidence which tend to confuse the entity. The diagnostic criteria proposed by the recent DSM-III of the American Psychiatric Association allow a better circumscription of the syndrome but exclude a group of patients manifesting visual hallucinations, sometimes paranoid features and cognitive functions that are less disturbed. Heller's and Kornfeld's less rigid criteria, on the other hand, have the disadvantage of including functional psychotic states that can arise after surgery without a true delirium with organic brain syndrome. We suggest the use of standard criteria that could include only delirium following cardiac surgery with E.C.C. and subdivision of the patients following the kind of surgery. In a retrospective study of the last four years at the Montreal Heart Institute, our clinical observations show an incidence of delirium after heart surgery with E.C.C. of 3%. a finding much lower than that reported in other centres which show an incidence between 13 and 67%. The more important factors found, were the kind of surgery (valve replacement more than coronary bypass), the age of the patients, and the degree of sickness after surgery during the stay in the intensive care unit. Those risk factors were also found in other recent studies. We describe the clinical syndrome and discuss its etiology in reviewing the more common risk factors before, during and after surgery. We underline the importance of the quality of the relationship with the patient before and after surgery in discussing prevention and treatment.

[Delirium after surgery with extra-corporeal circulation]

The recent literature still reports a high incidence of delirium in patients operated with extracorporeal circulation. This syndrome is found more often in patients over 50 years and in patients with a previous history of delirium, alcoholism, drug addiction or cerebral damage and is more frequent after valvular than after coronary surgery. It is also often observed in patients who present major post-operative complications. Attention and concentration capacity are characteristically modified (diminished most of the time) with or without faulty perception (hallucinations), sleep alterations, incoherent language, apathy or agitation. Disorientation and memory troubles are common. Delirium appears within a few hours or a few days of the surgery, its evolution is fluctuant and generally benign. A retrospective study at the Montreal Heart Institute showed an incidence of 2.98 per cent (84 cases/2811 open heart surgery cases) over the last four years. The mean age of these patients was 57.5 years (versus 50.4 for patients without delirium). Major post-operative complications were found in 37 (44 per cent) of these 84 patients. The incidence was lower (1.45 per cent) in coronary than in valvular (4.6 per cent) surgery cases. Several explanations are presented to explain this low incidence.