Isobaric Ropivacaine 15 mg Versus Hyperbaric Bupivacaine 12.5 mg for Spinal Anesthesia in Geriatric Patients Undergoing Total Knee Arthroplasty - Abstract
Background: We conducted this study to reach up to a safer and effective spinal anesthetic drug for use in high risk geriatric patients undergoing major lower limb surgery by comparing intrathecal isobaric ropivacaine with the commonly used intrathecal hyperbaric bupivacaine in such group of patients.
Methods: Fifty two geriatric patients ASA grade II–III undergoing elective total knee arthroplasty (TKA) surgery under spinal anesthesia were randomized into two groups. Group I including patients who received 12.5 mg (2.5 ml) of hyperbaric bupivacaine 0.5% and group II including patients who received 15 mg (3ml) of isobaric ropivacaine 0.5%. The extent and duration of sensory and motor block and hemodynamics including heart rate (HR), non invasive mean arterial blood pressure (MAP) and respiratory depression were recorded.
Results: Successful block has been attained in all patients in both groups. There were significant statistical difference between the two groups as regards onset time to T10 (group I 7 ± 1.85 min ; group II 10.3 ± 1.34 min; P < 0.001), time to maximal sensory level (group I 21.27 ± 9.37 min; group II 26.5 ± 7.21 min; P < 0.028) , median maximum sensory extent (group I T6 ; group II T8; P < 0.031), duration of T10 anesthesia (group I 93 ± 10.37 min ; group II 60 ± 10.92 min; P < 0.001) and onset time to maximal motor block (group I 8.5 ± 1.2 min; group II 12.8 ± 1.6 min; P < 0.001). The total duration of both sensory block (group I 180 ± 20 min vs. group II 150 ± 25 min; P < 0.001) and motor block (group I 160 ± 10.92 min vs. group II 130 ± 13.61 min; P < 0.001) were shorter in the ropivacaine group significantly but sufficient for surgery. In addition, ropivacaine caused less hemodynamic complications such as hypotension, bradycardia and respiratory depression than did bupivacaine.
Conclusion: Isobaric ropivacaine 15 mg can be used to provide a reliable spinal anesthesia for geriatric patients undergoing total knee replacement surgery that is comparable to that of the commonly used hyperbaric bupivacaine 12.5 mg as regards the efficacy of the block with a shorter recovery profile and less hemodynamic derangement.
The study was registered on www.clinicaltrials.gov, Registration ID: NCT02764723, Registered June 6, 2016.