Comparison of the Efficacy of 0.5% Bupivacaine, 0.5% Levobupivacaine, and 0.5% Hyperbaric Bupivacaine

111patients who underwent surgical intervention on the hip, thigh, and knee joints were included in the study.

Criteria for inclusion of patients in the study: indications for surgical intervention on the hip, thigh, and knee joints. Anesthesiological support was required; a written informed consent was obtained from patients to participate in the clinical trial and a written informed consent of the patient about the type of anesthesia and possible complications of regional anesthesia was available. After obtaining informed consent, patients were randomized into groups using a random number generator (numbers in envelopes). The random assignment sequence was created by an anesthesiologist not involved in the study.

Exclusion criteria: patient refusal to use the proposed type of anesthesia, age <18 years, body mass index not > 39, physical status according to ASA 1-3, history of allergic reactions to the drugs used, coagulopathy, infectious skin lesions in the injection area, neurological or neuromuscular diseases, severe liver disease or renal failure, inability to cooperate with the patient.

Spinal anesthesia was administered to the patients for anesthetic support of the surgical intervention. Patients were randomly allocated into three groups: in group 1 (1B) spinal anesthesia was performed with 3 ml of 0.5% bupivacaine(n=37); in group 2 (2L) spinal anesthesia was performed with 3 ml of 0.5% levobupivacaine (n=37); in group 3 (3H) 3 ml of 0.5% hyperbaric bupivacaine solution (n=37) was used for subarachnoid injection. The anesthesiologist, who was not involved in the study, prepared the anesthetic solution immediately before the injection.

Intrathecal injections were performed with a 24G or 25G "Pencil point" needle in the L3-L4 interval. Spinal puncture was performed while the patient was sitting on the table. Then the patient was placed on his back.

Solutions for spinal anesthesia were prepared by an anesthesiologist who was not involved in the anesthesia. Spinal anesthesia was performed by an anesthesiologist with many years of experience, who performs 10-15 spinal anesthesias per week.

The peripheral vein was catheterized on the operating table before anesthesia. SPO2, ECG, HR, thermometry, and nBP were monitored during anesthesia and surgery.

Surgery was allowed to start after 40 minutes if the upper level of the sensory block reached the Th10 segment.

The criterion for assessing the effectiveness of anesthesia was the need to switch to another type of anesthesia (criterion-no anesthesia), or the need for additional use of narcotic analgesics or local anesthesia during surgery (criterion-reporting of painful feelings during the operation).

The block was evaluated by an anesthesiologist who was not involved in the study. Sensory block quality was recorded on both sides along the midclavicular line, assessing changes in needle prick sensation. Skin sensitivity was assessed every 2 minutes for 40 minutes. The following scale was used to assess sensory block, where: "++" - complete sensory block (anesthesia); "+" - not complete sensory block, the patient could not differentiate the type of stimulus; "˗" - skin sensitivity preserved to the full extent.

The development of motor block was assessed using the Bromage scale (0-3) for 40 minutes. End of motor block was defined as the appearance of the first movements in the lower extremities (within 24 hours).

The duration of postoperative analgesia was assessed by interviewing the patient in the postoperative period (within 24 hours). The duration of analgesia was assessed in the postoperative period every 30 minutes. Pain sensations were assessed by visual analog scale (VAS) from 0 cm (no pain) to 10 cm (unbearable pain). The end of analgesia was considered the moment when the patient noted the onset of pain (1-2 points). If painful sensations appeared in the postoperative wound area (1-2 points),the investigators injected intramuscularly 2 %-1 ml of Promedol for postoperative analgesia. The duration of analgesia was assessed by an independent anesthesiologist, who was not involved in the study.

For the additional intraoperative analgesia criterion, the null hypothesis implies that the degree of success in the compared groups (for each local anesthetic) is the same ( p >0.05). If the null hypothesis should be rejected after a statistical test ( p < 0.05), it is concluded that one of the groups is superior to the others on this indicator. The sample size was calculated for a confidence level of 99% and statistical power of 99% and a type 1 error of 0.01 (taking into account the effectiveness of performing spinal anesthesia with bupivacaine 0.5% in orthopedics at our institution). The estimated sample size for each group was 7 patients. Considering previous studies in this area, where the sample size ranged from 29 to 40 patients, the investigators included an additional 30 patients in each group to increase validity (total 37 patients in each group).

Statistical processing of the obtained data was performed using Statistica 7.0 software. The data were presented as median and quartiles (25th% and 75th%) and also as mean and standard deviation. Differences between the groups were considered statistically significant at p<0.05. The primary endpoint was the need to switch to another type of anesthesia or the need for additional narcotic analgesics or local anesthesia either initially or during surgery. The frequencies of the binary feature in the two unrelated (independent) groups were compared by analysis of a contingency table (2×2). Classic Pearson's X2 test (Chi-square) was used; Fisher exact p test was applied in the presence of values of the phenomena of 5 and less. Differences between the groups were considered statistically significant at p<0.05. 95% CI for categorical data calculated using Wald's method.

Secondary endpoints: time of sensory and motor block development, duration of postoperative analgesia and motor block. The groups were compared using nonparametric Mann-Whitney test. Differences between the groups were considered statistically significant at p<0.05.