In this randomized double-blinded clinical trial, patients between 20 and 65 years old, American Society of Anesthesiologist (ASA) grade I and II of either gender undergoing elective lower limb surgeries at Rasoul-e-Akram Hospital in 2017 were recruited. If the patients were addict and very obese, had uncontrolled hypertension or diabetes mellitus, renal or hepatic failure, cardiac block or dysrythmia, coagulopathies, neurologic disorders, hypersensitivity to any of the study drugs and known contra indications to spinal anesthesia, they would be excluded. The study was reviewed and approved by the Iran University of Medical Science Ethics Committee and written informed consent was obtained from all subjects before inclusion in the study.
The study sample size was calculated by using the results of Yektash et al.(2014) and through the following formula. Considering α = 0.05, power of 90% was calculated 29 per each group. Given that "g" is the number of group, then the total sample size was 82 by using the following formula: n' = n * √ (g − 1) for each group as there was possibility that some patients do not complete the study; 10% drop-out rate, we included 30 patients for each group.[13,14]
Using Block Randomization, according to sample size, the patients were enrolled into the study (Figure 1).
The patients were randomly allocated to bupivacaine (Marcaine spinal 0.5% heavy Astrazeneca, Cenexi, France) and normal saline (BN), bupivacaine and dexmedetomidine (Precedex, Hospira co., USA) (BD) and bupivacaine and fentanyl (Caspian Darou, Rasht, Iran) (BF). The patients received 2.5 ml intrathecal hyperbaric bupivacaine with 0.5 ml normal saline (BN) or 5 micrograms dexmedetomidine (BD) or 25 micrograms fentanyl (BF). All medications were prepared in 3 ml syringes. The patients and physician evaluating the outcome of the treatments were blinded to the group allocation.
All the patients were kept for 8 h fasting prior to surgery. Preloading completed with Ringer lactate solution (5 ml/kg body weight). Standard monitoring including noninvasive blood pressure (NIBP), ECG, heart rate and pulse oximetry performed. All patients received supplemental oxygen via mask (5 l/min). Under proper aseptic conditions, spinal anesthesia was given at the level of L4-L5 interspace in sitting position using a midline or paramedian approach by a 25G Quincke spinal needle. The anesthetic medication is injected at a rate of approximately 2 ml/sec; and then all patients were made supine.
Blood pressure, heart rate and pulse oximetry were performed every minute in the first 10 min and then every five minutes for one hour. We recorded systolic and diastolic blood pressure and heart rate before regional anesthesia and in the 5, 10, 15, 30, 45 and 60 min after anesthesia. All data were recorded in a data sheet specified to each patient.
As we needed anesthetic effects, both sensory and motor status were assessed prior to the spinal injection, then every 2 min after injection until reaching the highest sensory level and Bromage scale reaching to Bromage 3. After surgery, assessment performed every 10 min until the time to regression of 2 sensory levels, then every 20 min until the regression time to the dermatome S1 and motor scale to Bromage 0.
The motor dermatome level was assessed according to the Bromage scale:
Bromage 0 (none): Free movement of legs and feet.
Bromage I (Partial): Just able to flex knees with free movement of feet.
Bromage II (Almost complete): Unable to flex knees, but with free movement of feet.
Bromage III (Complete): Unable to move legs or feet.
Severity of pain 6 h after surgery was measured by Numeric Rating Scale (NRS). The patients were asked to rate their pain from a scale of 0 = no pain to 10 = the worst possible pain. In case of any side effects it was recorded.
Hypotension was defined as decrease in systolic blood pressure (SBP) more than 30% of baseline or SBP < 90 mmHg. If hypotension occurred, 10 mg ephedrine would be administered. Bradycardia was defined as heart rate (HR) below 50 pulses per minute and if occurred, 0.6 mg atropine would be administered.
All data were analyzed using SPSS24 (version 24; SPSS Inc., Chicago, IL). The results are expressed as Mean ± standard deviation or percentage. The nominal categorical data between study groups were compared by using the chi-squared test or Fisher's exact test as appropriate. One-way ANOVA and repeated measure of ANOVA were used to evaluate the changes in the variables during the study period. p-values of less than 0.05 were considered statistically significant.
BMC Anesthesiol. 2018;18(62) © 2018 BioMed Central, Ltd.