Risk Factors for Postoperative Delirium After Cardiac Surgery at the Clinical Center of Montenegro

Introduction Delirium is one of the oldest forms of mental
disorders known in medical history, then characterized as an...


Introduction
Introduction Delirium is one of the oldest forms of mental disorders known in medical history, then characterized as an "acute confusion condition." In everyday use, nowadays, it means drowsiness, disorientation and the presence of hallucinations.
However, in medical terminology, there are many other symptoms, including a sudden loss of the ability to focus attention, and even occasional drowsiness and severe agitation and irritability. In the countries of the European Union, cardiovascular mortality was 42% and in Montenegro in 2008 it was 54%. In Montenegro, in the last six years, there is a growing trend in the number of patients with cardiovascular diseases and their presence as a group in total deaths [1]. High participation of cardiovascular and malignant diseases in the structure of mortality reflects the present risky behavior in the population, such as smoking, alcoholism, improper diet, insufficient physical activity, but also the effect of environmental risk factors: air pollution, unhealthy diet, poor socio-economic living conditions etc. [2][3][4][5][6]. Postoperative delirium in the Intensive Care Unit (ICU) is a common complication after cardiac surgery and is associated with increased morbidity and mortality. However, in medical terminology, there are many other symptoms, including a sudden loss of the ability to focus attention, and even occasional drowsiness and severe agitation and irritability.
The definition of delirium is that it is a state of acute weakening of attention-focus, perception, power of comprehension that leads to various forms of semi-consciousness; that it is a syndrome caused by organ damage (by disease or chemically) and causes disruption (destruction) of neurons of the cerebellar cortex [7]. Delirium is not a disease, but a clinical syndrome of the underlying disease or a syndrome of emerging problems in the cognitive sphere; it is simply the most common symptomatic manifestation of early brain or mental dysfunction (caused by any reason) [8]. After surgery in the ICU, and after extubation, cardiac surgery patients in a number of cases enter a state of mental confusion and disorientation in time, space, towards themselves and towards others [9]. The incidence of delirium in the surgical intensive care unit is higher than 30%.
In intubated patients, the incidence of delirium increases to 80% [10]. The incidence of delirium in septic patients ranges from a very wide range of 9% to 71%. Patients on mechanical ventilation who developed delirium have a significantly higher 6-month mortality compared with patients on mechanical ventilation who did not develop delirium [11]. Patients who agreed to participate in the study. Criteria for excluding patients from the study:

2.
Patients who did not agree to participate in the study.

Research Methods
The study is retrospective, descriptive and clinical.

Discussion
The pathophysiology and etiology of delirium is unknown, and the onset of delirium in each individual patient is caused by the interaction of predisposing and other factors. The probability of developing delirium increases in proportion to the number of existing risk factors [12]. In addition to older age, pre-existing cognitive impairment is the most commonly confirmed independent risk factor for delirium in the literature. In our study, patients who developed delirium after heart surgery were statistically significantly older [13]. The prevalence and incidence of delirium in surgical patients is high. In cardiac surgery patients, delirium occurs in 23% to 32% of cases [14][15][16][17]. Delirium was diagnosed in 55% of patients, 70 years and older, who underwent heart surgery, which does not correlate with our research [18]. (Luders et al.) In 2012, in one of the studies, they predicted postoperative delirium after heart surgery, placing the aspect of the research on the age structure of the patients on whom the research was performed [19]. The incidence of delirium in selected works shows that the occurrence of delirium in cardiac surgery ranges from 3% to 52%.
The incidence is higher in hospitalized elderly patients by 25% [20].
Anesthesia, in itself, does not directly affect the onset of delirium after heart surgery, but inadequate oxygen supply to the brain, hydroelectrolyte imbalance, and patient awareness during surgery may contribute to this phenomenon. Delirium is a very common disorder in hospitalized elderly patients, with a prevalence of 10% to 30% and an incidence during hospitalization of 4% to 30%.
The greatest contribution to the development of delirium from the examined variables is given by prolonged intubation, followed by heart rhythm disorders and the length of hospitalization. A patient who had, compared to a patient who did not have prolonged intubation, is 22.13 times more likely to get delirium. Patients who develop a heart rhythm disorder are almost 5 times more likely to develop delirium [21][22][23]. The authors believe that prior to the study, psychological assessment and psychiatric examination of patients were not included, and therefore psychiatric family history cannot be considered as a predictor that may influence the occurrence of delirium after surgery [24,25]. The age of the patient may be a key etiological factor for delirium. Comparative studies have shown that the incidence of postoperative delirium in patients> 65 years of age is 4-10 times higher than in the younger population and 3 times higher in patients> 75 years of age than in patients> 65 years of age [26]. It is evident that the frequency and prevalence of delirium in elderly patients is higher than in other age groups. In general, the incidence of delirium is assumed to be 25% in hospitalized elderly patients [27]. Research has shown that the effect of prevention to prevent delirium is very limited. Further studies on the prevention of delirium in patients with cardiac surgery are needed [28]. Delirium is easily underestimated in clinical practice. Taking into account all risk factors and potential complications, importance is given to improving the general health of patients, thus reducing the frequency and severity of delirium after heart surgery [29,30].

Conclusion
We proved that age is a predictor of delirium in patients in the cardiac surgery department. Longer duration of extracorporeal circulation is a predictor of postoperative delirium after cardiac surgery. We concluded that patients who had delirium after cardiac surgery also had prolonged hospitalization. Statistically significantly longer hospitalization in the ICU preceded the occurrence of delirium. Prevalence of postoperative complications such as: heart rhythm disorder, prolonged intubation are significant predictors of delirium in our study, while re-surgery and polytransfusion have no statistically significant effect on the occurrence of delirium. In this paper, the working hypothesis that the length of hospitalization in the ICU affects the occurrence of delirium is confirmed, we also proved that longer hospitalization after cardiac surgery, affects the occurrence of delirium.