After obtaining the approval of the Clinical Trials Ethics Committee of Muğla Sıtkı Koçman University Training and Research Hospital and written informed consents from each patient, a screening was performed to evaluate anxiety levels in the participating patients. The study included patients from both sexes within an age range of 18 to 65 years, and at American Society of Anesthesiology (ASA) physical status I–II who were scheduled for elective laparoscopic cholecystectomy. Patients on psychotropic medication due to a psychiatric disease, patients with a neurological disorder, pregnant and breastfeeding women, patients with uncontrolled hypertension, metabolic disease or hematological disorders, patients with hypercholesterolemia and those who received medication for a chronic condition within the past two months, and patients with a chronic cardiac, respiratory or renal disease were excluded. The study was conducted in accordance with the principles of the Declaration of Helsinki.
The Beck Anxiety Inventory (BAI) was administered to the participating patients one day before surgery to evaluate the level of anxiety. Based on the scores from the BAI, 40 patients with an anxiety score of <8 were assigned to the non-anxious group (Group NA) and 40 patients with an anxiety score of ³8 were assigned to the anxious group (Group A). The MPV in the complete blood count test performed one day prior to surgery was recorded. All patients entering the operation room routinely underwent electrocardiography, non-invasive blood pressure measurement, peripheral oxygen saturation (spO2) measurement, and entropy monitoring (GE entropy sensor, GE Healthcare, Finland). Vascular access was attained on the dorsum of the left hand using an 18-gauge intravenous catheter and a physiological saline was initiated at a rate of 15 mlkg-1h-1. Anesthesia was induced through the administration of propofol 1% at a dose of 3 mg kg-1 within three min using an infuser. The pain from the propofol infusion was rated as described elsewhere (0, none; 1, mild; 2, moderate; 3, severe) by an anesthesiologist who was blind to the study groups and treatments (9). The mean time to achieve an entropy value below 60 (T1) was recorded and a remifentanil infusion was initiated for two min at a rate of 1 µg/kg-1/min-1. Rocuronium 0.6 mg/kg was administered for neuromuscular blockage and the Evans scores of the patients after intubation were recorded.
For the maintenance of anesthesia, intravenous propofol was continued at a rate of 3 to 7 mg/kg-1/h-1 and the remifentanil infusion was continued at a rate of 0.1 µg/kg-1/min-1 to maintain the target entropy value of between 40 and 60. The remifentanil infusion rate was increased to 0.3 µg/kg-1/min-1, if the entropy value was above 60 with a propofol infusion rate of 7 mg/kg-1/h-1. Mechanical ventilation was continued with 3 L fresh gas flow containing 40% O2 and 60% air. All patients were administered intravenous dexketoprofen 50 mg and tramadol 1 mg/kg-1 for preemptive analgesia. The total intraoperative propofol consumption within the first 30 min was recorded. The remifentanil infusion was ceased 10 min before completion of surgery, and the propofol infusion was ceased after suture placement. The time from the end of anesthesia to eye opening was recorded (T2). Along with these measurements, the mean arterial pressure (MAP), heart rate (HR), end-tidal carbon dioxide (etCO2), and spO2 were recorded before induction, before intubation, and at 5, 10, 30, 45, and 60 min after intubation.
Previous studies in the literature were taken into consideration while estimating the sample size (10,11). It was hypothesized that a 20% difference in the preoperative MPV of patients with low and high anxiety scores would be of clinical significance. The minimum number of patients in each group was calculated as 34 considering an alpha (two-tailed) of 0.05 and a power of 0.80.
Statistical analysis was performed using the SPSS version 15.0 software (SPSS Inc., Chicago, IL, USA). The relationship between MPV and preoperative anxiety scores was evaluated using the Pearson’s correlation coefficient. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the relationship between the BAI scores and MPV and propofol consumption at 30 min. A p value of less than 0.05 was considered statistically significant.