These were evaluated in 60 patients, who have been scheduled for elective surgical procedure, under a monitored anesthesia care. After an approval from the Institutional Review Board, written informed consent was obtained from all participating 75 patients who were scheduled for local breast biopsy, using PCS during the MAC, and who met the enrollment criteria. All patients were adult outpatients aged between 20 and 50 years, American Society of Anesthesiologists (ASA) classification I or II and scheduled for sequential breast biopsy surgery under the MAC. Preoperative exclusion criteria were pregnancy, kidney or hepatic disease, chronic medication with analgesic or sedative drug, history of alcohol or drug abuse and patients who could not understand the concept of PCS. Patients had fasted at least 8 hours before the operation, and did not receive any preoperative sedative drugs.
The patients were allocated to one of the three groups, which used a computer-generated sequence of random numbers. The patients respectively received an infusion of total 16 ml solution that contained 10 ml of 1% propofol + 5 ml of saline + 1 ml of 2% lidocaine (group P), 10 ml of 1% propofol + 25 ug/ml of remifentanil + 1 ml of 2% lidocaine (group PR25), 10 ml of 1% propofol + 50 ug/ml of remifentanil + 1 ml of 2% lidocaine (group PR50). PCS was delivered using a patient-controlled analgesia pump (Perfusor fm™, B. Braun, Germany) with 1 min lockout time. One milliliter of solution was delivered over 10 sec. The study pharmacist mixed all the medications immediately before the start of a breast biopsy surgery. In the propofol group, the solution contained 6.25 mg of propofol per milliliter. In the Remifentanil-Propofol group, the solution contained, respectively, 7.81 ug (group PR25), 15.6 ug (group PR50) of remifentanil and 6.25 mg propofol per milliliter.
The PCS medications were delivered by an infusion line, which was attached to the IV skin insertion site. All patients were provided with instructions on the use of the PCS system in the preoperative area.
Preoperatively, standardized psychological tests were performed by the patient. We used 10 visual analog scales (VAS) to determine the pretreatment level of anxiety (0 = calm to 10 = extremely anxious). A digit symbol substitution test (DSST) was used to assess the baseline level of cognitive function. The sedation level was also assessed by the investigator, using the observer's assessment of alertness/sedation (OAA/S) scale, with 1 = wide-awake and alert to 5 = asleep and/or unarousable, after completing the preoperative pain VAS, DSST, and OAA/S assessments. Deep sedation's evaluation is when OAA/S score change from 3 to 2 (responds only after mild prodding or shaking).
Before administration of the local anesthetic, and immediately after pump connection to a 22-gauge peripheral i.v. cannula, the patient was encouraged to make the first demand by pressing the hand-held triggering device, and in addition, to make a demand in the event of any discomfort or anxiety.
On arriving at the operating room, standard monitoring, including electrocardiography, non-invasive arterial pressure, respiration rate and peripheral pulse oximetry, was recorded. Oxygen was administered via nasal cannula at 3 L/min. Ephedrine 5 mg was administered when systolic blood pressure (SBP) decreased below 90 mmHg or 70% of the preoperative value. Atropine 0.5 mg was injected to the patients when the heart rate (HR) fell below 40 beats/min. SBP, HR, respiratory rate (RR), and peripheral oxygen saturation (SpO2) were recorded at each time point, as follows; B = preoperative baseline, PCS 5 = 5 min after PCS start, Inc = just after incision, OP15 = 15 min after incision, OPend = the end of surgery, R0 = just after arrival at recovery room, R15 = 15 min after at recovery room, and R30 = 30 min after arrival at recovery. Moreover, the incidence of adverse events, including hypertension (SBP > 160 mmHg), hypotension (SBP < 80 mmHg), bradycardia (HR < 50 beats/min), respiratory depression (RR < 10 breaths/min), and oxygen desaturation (SpO2 < 93%), were evaluated.
At the end of the surgery, the total amount of propofol and remifentanil administered was noted from the PCS display, as the A/D ratio (%) were the number of self-administration attempts of the study drugs (demand), and the number of successful attempts (apply). Before discharge, from the day surgery unit, patients were asked their opinion of the sedation and its effect by using a 4 - point rating scale (1 = highly satisfactory, 2 = satisfactory, 3 = somewhat satisfactory, 4 = unsatisfactory) [6
Statistical analyses were performed, using GraphPad Prism (GraphPad Software, USA, 5.0). One-way ANOVA was used for the comparison among the groups in the following parameters: age, weight, height, ASA status, duration of sedation, operation time, volume of regimen requirements and A/D ratio. The overall significance of the results was examined, using a two-way analysis of variance, and a Bonferroni post-hoc test was used for multiple comparisons. The Fisher's exact test was used to determine the incidence of adverse events. The results are expressed as the mean ± SD or absolute number. P value of < 0.05 was considered to be statistically significant.