Administering bupivacaine in the caudal space (with or without morphine) provides sufficient postoperative analgaesia to patients with ankylosing spondylitis (AS) who undergo total hip arthroplasty, according to results of a prospective study presented at the 2015 Annual Meeting of the Canadian Anesthesiologists’ Society (CAS).
Patients with AS present a challenge to anaesthesiologists, in that they have fusion of the bones in the spine, requiring an alternative site to insert epidural catheters, such as the caudal space – specifically, the sacrococcygeal membrane, explained principal investigator Mahesh Kumar Arora MD, All India Institute of Medical Sciences, New Delhi, India, speaking here on June 20.
“These are patients whose spines are ankylosed, they are not able to move their joints, and they cannot breathe properly,” said Dr. Arora. “They are patients who are difficult to intubate in terms of general anesthesia.”
Dr. Arora and colleagues recruited patients with AS aged 18 through 60 years who were to undergo total hip replacement surgery. After induction of general anaesthesia, a caudal epidural catheter was placed in a lateral position. The investigators administered epidural 0.125% bupivacaine in a total of 15 patients and the same dose of bupivacaine as well as 50 mcg/kg morphine in another 15 patients.
The team used nonionised dye to verify the position of the epidural catheter. “There is challenge in making sure the catheter goes to the right place,” Dr. Arora noted.
The researchers found Visual Analogue Scores to be similar between the 2 study arms after surgery, with no difference between patients who received bupivacaine alone or bupivacaine with morphine. The use of intraoperative and postoperative fentanyl was also similar between the 2 arms (P = .887 and P = .82, respectively).
Urinary retention occurred in patients after surgery in both study arms, but there was not a statistically significant difference in its incidence between the 2 groups.
Dr. Arora plans to conduct another study using the caudal epidural block, and will use ultrasonography to ensure appropriate insertion of epidural catheters.