Graded dosage of local anesthetic for spinal anesthesia during orthopedic and trauma surgeries on the lower extremities

Abstract

Background. The development of a clear algorithm of a local anesthetic dosage for spinal anesthesia during surgeries on the lower extremities is an urgent issue, even after a century of using this method of analgesia. The aim of our study is to improve the efficiency and safety of spinal anesthesia during lower extremity surgery in orthopedic and trauma patients by developing a local anesthetic dosage algorithm. Materials and methods. The conducted study is based on the analysis of the bilateral spinal anesthesia methods in 75 patients with degree I–II ASA operational risk during orthopedic and trauma surgeries on the lower extremities who were divided into 3 study groups. Spinal anesthesia was performed using 0.5% bupivacaine, with the anesthetic dosage algorithm developed according to the patients’ height (group III) and the standard recommended dosage (group I, patients of short height, and group II, patients’ height > 180 cm). Results. When studying the hemodynamic indicators, the heart rate before surgery was as follows: in the first group, 73 ± 8 bpm, in the second group, 78 ± 6 bpm, in the third group, 79.32 ± 14.47 bpm. Thirty minutes after the injection of the anesthetic, the heart rate in the group 1 was 68 ± 5 bpm, and three hours after, it was 71 ± 9 bpm. In the group 2, the heart rate of patients 30 minutes after the injection of the anesthetic was 79 ± 7 bpm, three hours after, it was 84 ± 9 bpm. In the group 3, the heart rate of patients 30 minutes after the administration of the anesthetic was 71.56 ± 14.14 bpm, three hours after the injection, it was 71.280 ± 9.002 bpm. Data on systolic blood pressure before surgery was started were as follows: in the first group, 139.6 ± 12.3 mmHg, in the second group, 136.0 ± 9.6 mmHg, in the third group, 138.40 ± 16.18 mmHg. During the surgical intervention, blood pressure indicators in the group 1 were: 30 minutes after the introduction of the anesthetic — 113.0 ± 7.1 mmHg, 3 hours after — 122 ± 14 mmHg; in the second group: 30 minutes after the injection of the anesthetic — 138.0 ± 10.2 mmHg, 3 hours after — 141.0 ± 12.5 mmHg; in the third group: 30 minutes after the administration of the anesthetic — 102.48 ± 13.47 mmHg, 3 hours after the introduction — 118.2 ± 10.0 mmHg. The average duration of the sensory block in the group 1 was 182.5 ± 17.2 min, of the motor block — 130.0 ± 24.8 min; in patients of the group 2, the sensory block lasted 70.6 ± 13.1 min, and the motor block 23.3 ± 6.7 min; in the group 3, the duration of sensory block was 252.20 ± 74.32 min and of the motor block — 198.2 ± 59.0 min. Conclusions. 1. The use of small doses of hyperbaric bupivacaine does not affect hemodynamic parameters but reduces the quality and duration of anesthesia in tall patients. 2. The frequency of complications during spinal anesthesia does not increase with an increase in the volume of local anesthetic in tall patients. 3. Selection of graded dose allows for more predictable and qualitative application of spinal anesthesia during orthopedic and trauma surgeries.