Low‐dose bupivacaine: a comparison of hypobaric and near isobaric solutions for arthroscopic surgery of the knee

Abstract

SummaryThe results of studies on the effect of volume, concentration or total dose of local anaesthetic on the spread of spinal anaesthesia are inconclusive. Most support the assumption that the total dosage is more important than the volume. We compared low-dose bupivacaine (6 mg) in 0.5% and 0.18% solutions as sole anaesthetic to achieve predominantly unilateral spinal anaesthesia for knee arthroscopy. Sixty patients were randomly allocated to two groups to receive either 1.2 ml 0.5% bupivacaine (6 mg) (n ¼ 30) or 3.4 ml 0.18% hypobaric bupivacaine (6.1 mg) (n ¼ 30). Drugs were administered at the L 3-4 interspace with the patient in the lateral position. Patients remained in this position for 20 min before being turned supine for the operation. Spinal block was assessed by pinprick and modified Bromage scale and compared between the operated and nonoperated sides. No significant changes were found in the spread or duration of sensory or motor block (p > 0.05). The haemodynamic changes were also similar between the groups. The same pinprick level of analgesia, degree of motor block and duration of spinal anaesthesia was obtained with bupivacaine (6 mg) in low (1.2 ml) or high (3.4 ml) volumes. The ideal spinal anaesthesia for ambulatory surgery should provide good surgical anaesthesia with rapid recovery from sensory and motor block [1]. Lignocaine has been widely advocated for ambulatory anaesthesia but there are concerns about possible neurotoxicity. Recent editorials have questioned the use of hyperbaric 5% lignocaine for spinal anaesthesia [2][3][4]. In contrast, the frequency of radiating backache after bupivacaine has been reported as less than 1% [5,6]. There is increasing interest in the use of small doses of bupivacaine for spinal anaesthesia.There has been controversy concerning the relationship between volume, concentration and total dose of spinally administered drugs. Most of the studies suggest that the total dosage is more important than the volume [7][8][9]. In these studies, the doses of bupivacaine were fairly large. Sheskey et al. used 10, 15 and 20 mg doses [7] and Bengtsson et al. used bupivacaine 22.5 mg [8]. In the study of Cherng et al., plain bupivacaine 15 mg was diluted with cerebrospinal fluid (CSF) [9]. The effect of volume on spinal anaesthesia when a small dose (5-10 mg) of hypobaric bupivacaine is used has not been investigated.In a previous study, we achieved predominantly unilateral spinal anaesthesia with minimal sensory and motor block on the nonoperated side using a low dose of hypobaric 0.18% bupivacaine [10]. We have now compared low-dose bupivacaine (6 mg) in two volumes for predominantly unilateral spinal anaesthesia for day-case knee arthroscopy. Methods

Düşük Doz Spinal Anestezi ile Varis Operasyonu

“…Unilateral spinal anesthesia minimizes the hemodynamic effects of the local anesthetic drug (24)(25)(26). In our study, in group1, there were no hypotension and low HR and none of the patients required fluid load and vasopressor agent but in group 2, 3 patients required fluid load and vasopressor agent due to hypotension and low heart rate.…”

Ropivacaína para raquianestesia unilateral: hiperbárica ou hipobárica?

“…As the hemodynamic stability provided by unilateral spinal anesthesia does not necessitate over-hydration, another advantage of unilateral anesthesia is that unilateral sacral parasympathetic plexus blockage does not completely disturb the detrusor muscle function. In the present study, two patients in group Hypo and 7 patients in group Hyper complained of urinary retention and were catheterized once, micturating spontaneously 6,10 .…”

“…Kuusinami et al 10 and Casati et al 23 reported that the incidence of hypotension was lower with unilateral spinal anesthesia than with conventional spinal anesthesia. Pre-hydration is one of the factors that minimize hypotension following spinal anesthesia.…”

“…Therefore, the present study used equal concentrations of ropivacaine. Kuusiniemi et al 10 compared 6 mg of 0.5% isobaric bupivacaine and 6 mg of 0.5% hyperbaric bupivacaine in 8% dextrose for achieving unilateral spinal anesthesia; unilaterality was 83.3% in the hyperbaric group, whereas unilateral spinal block was 37% in the isobaric group. Kaya et al 11 reported that unilateral spinal anesthesia in their hyperbaric group was 80%.…”

Bupivacaína a 0,15% hipobárica para raquianestesia posterior (dorsal) versus bupivacaína a 0,5% hiperbárica para procedimentos cirúrgicos anorretais em regime ambulatorial

“…A dose de 7,5 mg bupivacaína hipobárica a 0,15% associada a fentanil tem um período de recuperação de 2,94 horas 9 , similar aos 2,96 obtidos com 6,1 mg de bupivacaína a 0,18% 26 . Diminuição da dose de bupivacaína a 0,15% hipobárica para 5 mg reduz o tempo de recuperação para 2,32 horas, representando diminuição de 20% 10 .…”