Comparison between Position Change after Low-Dose Spinal Anesthesia and Higher dose with Sitting Position in Elderly...

Large numbers of patients are presenting for surgeries with aging-related pre-existing conditions that make them at higher risks of adverse outcomes. Hemodynamic instability due to high sympathetic nerve block largely limits the use of conventional dose spinal anesthesia in high risk elderly patients.

We aimed to compare the hemodynamic stability and the block characteristics in low dose spinal anesthesia (5 mg) with immediate position change into supine position versus higher dose of spinal anesthesia (10 mg) with maintaining patient position in sitting position for 3 minutes after the block in elderly high risk population.

This study was a prospective randomized controlled double-blinded clinical study.

This study was carried on 70 patients of American Society of Anesthesiologists physical status classes I, II, and III aged 50 years old and above, who were scheduled for elective knee and below knee orthopedic surgeries expected to last for 40-60 minutes under spinal anesthesia. Patients were randomly allocated into two groups: group (A) Sitting group n= 35 patients that received 10 mg hyperbaric bupivacaine 0.5% in 2 mL volume intrathecal at level lumbar (L_4-5) in sitting position and remained in this position for 3 minutes before turning supine. And, group (B) Supine group n = 35 patients received 5 mg (low dose) intrathecal hyperbaric bupivacaine in 2 mL volume (1 mL hyperbaric bupivacaine 0.5% diluted with 1 ml sterile distilled water) at L_4-5 in sitting position then turned supine immediately. The injection will be in the midline over 30 seconds by 25 gauge(G) Quincke needle. We measured the changes of mean arterial blood pressure, heart rate, O₂ saturation and the incidence of hypotension and bradycardia intraoperatively as a primary outcome. Also, we measured the characteristics and the duration of the sensory and motor blocks, the duration required till return of bladder function and the satisfaction levels of both the patients and the surgeons as secondary outcomes.

Student's t-test and Chi-square test were used for analysis.

As regards hemodynamics, mean arterial blood pressure and heart rate were significantly lower in group A compared to group B; P-value <0.05, during the intraoperative period, while MABP and HR were significantly decreasing in group A during the initial intraoperative period at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min and 35 min, but in group B these parameters were statistically insignificant throughout the whole procedure P-value >0.05. As regards oxygen saturation, there were no significant differences between both groups or within the same group during the whole intraoperative period. Comparing sensory and motor blocks, sensory block was significantly higher and motor block was significantly dense in group A compared to group B during the first intraoperative period at 5 min, 10 min, 15 min, 20 min and 25 minutes. The recovery times from sensory and motor blocks were significantly longer in group A compared to group B (P-value <0.001). Also, the void recovery time was significantly longer in group A (129.29 ± 5.87 min) compared to group B (114.77 ± 8.24 min). In group B, patient satisfaction was significantly better (25 excellent/ 10 good) compared to group A (10 excellent/25 good). Also, surgeon satisfaction was statistically significantly better in group B (23 excellent/12 good) compared to group A (14 excellent/21 good). As regards side effects, in group A, 3 patients had to receive ephedrine due to significant reduction in MABP while no patients in group B had significant hypotension or bradycardia throughout the intra operative period.

We concluded that the use of small dose of heavy bupivacaine 0.5% (5 mg) with immediate patient position changing to supine position provided good spinal block characteristics in elderly population without any hemodynamic side effects, also with better patient and surgeon satisfaction levels compared to higher doses of heavy bupivacaine (10 mg) even if we maintained patient position in the sitting position for 3 min after the block.