CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 6, November/December 2022 298 AFRICA All patients were operated on by median sternotomy. Grafts for bypass (saphenous vein and internal mammary artery) were prepared. Systemic heparinisation was ensured by administrating 300 IU/kg heparin in a fashion where the activated clotting time would be higher than 450 seconds. CPB was initiated by inserting an arterial cannula through the ascending aorta and a two-stage venous cannula through the right atrium. In all patients, a non-pulsatile roller pump and membrane oxygenator were used for CPB. Surgical procedures were established in moderate systemic hypothermia (28–30ºC). CPB was maintained with a flow rate of 2.2 to 2.5 l/min/m2; the mean perfusion pressure was set between 50 and 80 mmHg, and haematocrit values between 20 and 25%. Myocardial protection was done via antegrade hypothermic and hyperpotasaemic blood cardioplegia. In all patients, the left internal mammary artery was used as the primary graft for revascularisation of the left anterior descending artery and the saphenous vein graft was used for revascularisation of the other coronary arteries. All proximal anastomoses were done onto the ascending aorta under side clamp, on a beating heart. All patients were taken to the ICU intubated. The patients who had spontaneous respiration and whose orientation and co-operation returned to normal were extubated provided that their haemodynamic and respiratory functions were stable. Meanwhile, respiratory functions were frequently assessed spirometrically and with arterial blood gas analysis. In addition, electrolyte imbalances, arterial oxygen and lactic acid values were monitored closely and periodically via arterial blood gas analysis. For pain management, 1 g of intravenous paracetamol was routinely administered to all patients in the postoperative ICU, unless additional medication was required. If so, 50 mg of intravenous dexketoprofen was also administered. All patients with manifestations of agitation were assessed by a psychiatrist and neurologist. Diagnosis of delirium was made by these clinics. Haloperidol (0.5–5 mg/day, intramuscular) was initiated as the first-line treatment to the patients in whom a diagnosis of postoperative deliriumwas made. Dexmedetomidine hydrochloride infusion treatment was initiated in patients with agitation, as a loading dose at a rate of 1 µg/kg/h. When agitation and other symptoms were regressed, a 0.5-µg/kg/h maintenance dose was started. Dexmedetomidine hydrochloride infusion was administered to all patients for 48 hours. Provided that the patients were haemodynamically stable following the treatment and verbal communication was achieved, they were transferred to the in-patient room for further follow up. Statistical analysis Statistical analysis was performed using the SPSS version 22.0 software (SPSS Inc, Chicago, Illinois, USA). Normally distributed data are expressed as mean ± standard deviation, while abnormally distributed data are expressed as median (minimum–maximum). The data obtained by dividing are given as percentages. Among the data measured, the normality of the distribution was evaluated by histogram or Kolmogorov–Smirnov test, whereas the homogeneity of the distribution was evaluated with Levene’s test for equality of variance. The difference between the groups was evaluated with the Student’s t-test in normal and homogeneous distribution, and with the Mann–Whitney U-test in abnormal and homogeneous distribution. Parametric or non-parametric Pearson’s chi-squared or Fisher’s exact tests were used to analyse the differences between the groups. Spearman’s correlation coefficient was used to analyse the correlations between quantitative variables. Forward stepwise multivariate logistic regression models were created to identify the independent predictors of postoperative delirium. The multivariate models were constructed by forward selection of independent variables with two different Wald p-values required for inclusion. Variables with a p-value of < 0.10 in univariate analyses were included in the multivariate model. A p-value of < 0.05 was considered statistically significant. As pre-operative and postoperative laboratory parameters were highly correlated, pre-operative and postoperative parameters were entered into the multivariable regression model separately. The sensitivity and specificity of the independent risk factors to predict postoperative delirium were determined by receiver operating curve (ROC) analysis. For a p-value of < 0.05 among the groups, the difference was accepted as significant. Table 1. The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) Features and descriptions Absent Present 1. Acute onset or fluctuating course A. Is there evidence of an acute change in mental status from the baseline? B. Or, did the (abnormal) behaviour fluctuate during the past 24 hours, that is, tend to come and go or increase and decrease in severity as evidenced by fluctuations on the Richmond Agitation Sedation scale (RASS) or the Glasgow Coma scale? 2. Inattention Did the patient have difficulty focusing attention as evidenced by a score of less than eight correct answers on either the visual or auditory components of the Attention Screening Examination (ASE)? 3. Disorganised thinking Is there evidence of disorganised or incoherent thinking as evidenced by incorrect answers to three or more of the four questions and inability to follow the commands? Questions • Will a stone float on water? • Are there fish in the sea? • Does 1 pound weigh more than 2 pounds? • Can you use a hammer to pound a nail? Commands • Are you having unclear thinking? • Hold up this many fingers. (Examiner holds two fingers in front of the patient.) • Now do the same thing with the other hand (without holding the two fingers in front of the patient.) If the patient is already extubated from the ventilator, determine whether the patient’s thinking is disorganised or incoherent, such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject. 4. Altered level of consciousness Is the patient’s level of consciousness anything other than alert, such as being vigilant or lethargic or in a stupor or coma? Alert: Spontaneously fully aware of environment and interacts appropriately. Vigilant: Hyperalert. Lethargic: Drowsy but easily aroused, unaware of some elements in the environment or not. Spontaneously interacting with the interviewer; becomes fully aware and appropriately interactive when prodded minimally. Stupor: Difficult to arouse, unaware of some or all elements in the environment or not spontaneously interacting with the interviewer; becomes incompletely aware when prodded strongly; can be aroused only by vigorous and repeated stimuli and as soon as the stimulus ceases, stuporous subject lapses back into unresponsive state. Coma: Unarousable, unaware of all elements in the environment with no spontaneous interaction or awareness of the interviewer so that the interview is impossible even with maximal prodding. Overall CAM-ICU assessment (features 1 and 2 and either feature 3 or 4): Yes____ No____
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