In patients undergoing cesarean delivery who are receiving a combined spinal epidural (CSE), a study has found that delivering epidural saline using a low-pressure gravity technique leads to fewer complications than relying solely on an epidural catheter.
The investigators Shaul Cohen, MD, Antonio Chiricolo, MD, and their colleagues from the Rutgers-Robert Wood Johnson University Hospital, in New Brunswick, N.J., tested whether giving cesarean delivery patients 10 mL of epidural saline via a low-pressure method, after the spinal and before the epidural is given, would result in fewer epidural blood vessel punctures and paresthesias and better-quality sedation than traditional CSE.
For this prospective, randomized, double-blind study, 229 women having elective cesarean delivery were placed in one of two groups: those receiving epidural saline by gravity and CSE and those receiving only CSE.
The study was presented at the 2014 annual meeting of the Society for Ambulatory Anesthesia (abstract 30).
In CSE, the physician injects spinal solution through the spinal needle, which is traced through a larger epidural needle. The spinal needle is withdrawn while the epidural needle remains in place, although there is a risk for epidural blood vessel punctures and paresthesias. In rare cases, catheters can enter the subarachnoid space and lead to a total spinal, with loss of consciousness and respiratory arrest.
“We think the saline helps by lubricating the structures in the epidural space,” said Dr. Chiricolo, thus creating a pathway that allows the catheter to advance.
Patients were randomly assigned to two groups. In the first group of 115 patients, a catheter was inserted immediately after the spinal solution, which was delivered with a Pencan needle (B. Braun Medical) through the epidural needle. In the second group of 114 patients, each patient was given 10 mL of saline by gravity after the spinal solution was injected and before a closed-end catheter (B. Braun Medical) was inserted epidurally.
The investigators used a CSE kit, which contained an Espocan epidural needle (B. Braun Medical) along with a Pencan spinal needle. The Tuohy needle in these kits has a hole at the tip that allows the spinal needle to slide through to pierce the dura.
While lying on their sides, all patients were given injections of 10 mg ropivacaine, a local anesthetic, along with 100 mcg of epinephrine and 25 mcg of fentanyl at roughly the same location in the spine. Additional doses of local anesthesia (5-20 mL of 0.75% ropivacaine—an isobaric solution—with 5 mcg/mL epinephrine and 5 mcg fentanyl) were injected into the epidural catheter if spinal anesthesia was deemed unsatisfactory.
After the procedure, the investigators collected patient data, asked the anesthesiologists how many attempts were required to pass the catheter, and observed whether there was frank blood in the cerebrospinal fluid or catheter.
The data collectors tested patients’ motor abilities using a 5-point Bromage test, with 1 meaning the patient lacked foot movement and 5 meaning the patient could achieve total hip and knee flexion. The highest level of motor block from either leg was recorded and used in later analyses.
Epidural catheters caused blood vessel punctures in 19 patients in the first group, those who received CSE alone, and in six patients in the second group, those given epidural saline and CSE. In the first group, 74 patients had paresthesia, compared with 46 patients in the second group.
After their procedures, the patients were given lidocaine with epinephrine via the epidural catheter, which was connected to a portable Abbott Pain Management Provider to relieve postsurgical pain. Seventeen patients in the first group required additional nitrous oxide or fentanyl for pain relief, whereas three patients in the second group needed medication for additional pain relief.
Physicians were unable to pierce the dura with a spinal needle and failed to achieve spinal blocks in 17 patients in the first group and 23 patients in the second group—a failure rate of 14.8% and 20.2%, respectively.
Art Saus, MD, assistant professor of anesthesiology at Louisiana State University Health Center, in Shreveport, commented that he found the failure rate to be “awfully high” for physicians using a CSE kit. “Failure to put the needle into the dura would be very uncommon.”
Dr. Saus felt that although the authors reduced complications in patients undergoing cesarean delivery using the gravity technique, their methodology raised too many questions to be able to determine the study’s value.
A disproportionate number of patients may have been heavy—setting a spinal block in an obese patient is typically more difficult—or perhaps less experienced residents may have been handling the epidurals, Dr. Saus said. Knowing the body weight of each patient, and whether there were equal numbers of heavy and light women in each group, would have made the data stronger, he said.
Whatever the causes, the study authors lost 15% to 20% of their subjects in each group because of this high failure rate, a fact that Dr. Saus felt left the study underpowered.
The patient groups showed no differences in levels of itching, sedation, hypotension, time to pain or overall satisfaction. The time to incision was nearly equal, at 32.7 minutes for the first group and 32.6 minutes for the second group.
In a later phone survey, the investigators found that all of the epidurals were successful for postoperative pain management for two to three days. They found no differences in shortness of breath or muscle weakness between the groups.
The authors believed their results could be easily replicated. Dr. Chiricolo said future studies might evaluate the same patient population using a hyperbaric solution for the spinal block instead of an isobaric solution, to see how results might differ.