Tunneling Does Not Prevent Dislodgment of Epidural Catheters: A Randomized Trial.

BACKGROUND: Epidural analgesia is preferred in postoperative pain control, but dislodgment is a major factor for failure. Tunneling is well known to control displacement of catheters. In this study, we evaluated if we can depend on tunneling in preventing dislodgment of epidural catheters. AIMS: The aim is to study if tunneling is effective and safe in reducing the rate of epidural catheters' dislodgment. SETTING AND
DESIGN: The study was carried out at a single tertiary cancer center. The trial was parallel, simple randomized, controlled, and single blind. Allocation of treatments was generated using random number tables. SUBJECTS AND METHODS: Two hundred patients undergoing major surgeries were randomized. Epidural catheters were affixed to the skin through subcutaneous tunneling to a length of 5 cm or using standard adhesive tape without tunneling. Patients were on follow-up for 6 days postsurgery according to policy. STATISTICAL ANALYSIS USED: Categorical variables were analyzed by Chi-square and Fisher's exact test. Student t-test was used for continuous variables. RESULTS AND
CONCLUSION: A total of 200 patients were randomized, 92 patients received tunneled catheters and 108 received nontunneled catheters. Patients were between 20 and 85 years; 63% were male. The mean days of epidural analgesia were similar in both groups (2.7 compared to 2.5 days). About 7.6% of epidurals were dislodged in the tunneled group compared to 10.2% in the nontunneled group (P = 0.699). No differences were identified in the incidence of pain or adverse events between the groups. Tunneling did not improve the rates of dislodgment in epidural catheters. There were no safety concerns associated with tunneling epidural catheters.

INTRODUCTION

The proper relief of pain positively impacts the patient's physiologic and mental state.[12] Following major surgical procedures, the control of severe acute pain episodes is necessary to prevent the development of chronic pain.[3]

Epidural analgesia is preferred in postoperative pain control.[4] The duration of epidural analgesia is assumed to influence the efficacy of the analgesia and affect the postoperative outcome.[4] Dislodgment of the catheters remains a major cause in the failure of analgesia.[56] Tunneling is used to reduce catheter displacement.[789] It is also described to reduce the risk of catheter infection.[1011] Several tunneling techniques are discussed in the literature.[1213141516]

At our institution, we depend on medications and patient-controlled analgesia (PCA). PCA pumps are a shared resource with other departments. Therefore, epidural analgesia is routine practice for postoperative pain. Following major surgical procedures, dislodgment of epidural catheters is a primary factor in disrupting analgesia for our patients. The patient is switched to PCA, if available, or as needed pain medications. We proposed this study to evaluate if we can depend on tunneling to reduce catheter dislodgment and uninterrupted epidural analgesia.

SUBJECTS AND METHODS

Ethics

The procedures followed in the study were in accordance with the ethical standards of the Institutional Review Board (IRB) at the Center on Human Subject Research and with the Helsinki Declaration of 1975, as revised in 2013. The study was reviewed and approved by center's IRB.

As per the center's policy, patients had first to consent to anesthetic pain control through epidural insertion. Patients were then approached and informed of the study. Documented consent was a prerequisite to participate. All participants had to sign an informed consent form, approved by the IRB for the study.

Study objectives and endpoints

The study primary objective was to assess if 5 cm tunneling of epidural catheters will affect the incidence of epidural catheter dislodgment. Secondary objectives were to assess pain and incidence of adverse events.

The primary endpoint for the study was the number of dislodgments in each group. Secondary endpoints included facial pain scores (FPSs) and the number of adverse events in each group.

The catheter was considered to be dislodged if it was found loose, entirely outside the patient or leaking.

Study design and setup

The study was carried out at a single, tertiary cancer center. The study was a simple randomized, parallel-design trial. Participants were randomized into one of two groups as follows:

Group A – epidural catheter insertion and fixation by subcutaneous tunneling procedure

Group B – epidural catheter insertion and fixation by use of adhesive tape without tunneling.

The study team consisted of anesthesiologists and preanesthesia coordinators from the Department of Anesthesiology and Pain Management. Surgeries were carried out at the center's operating theaters.

Epidural insertion was carried out before surgery. During epidural insertion, most patients were in a sitting upright position and a few were allowed to assume a lateral position. The patients were awake with the intravenous line and monitors in place. The skin at the site of insertion was cleaned with chlorhexidine. A local anesthetic was used. The epidural space was identified by the loss of resistance technique.

The Portex® Epidural Minipacks System-1 (Smiths Medical, Dublin, Ohio, USA) was used in the study. The kit includes a clamp, 18G Tuohy needle, and a clear catheter with three lateral eyes. The epidural needle was used to horizontally tunnel the catheter for a length of 5 cm on either side of the insertion point.

Medications infused through the epidural catheter were a combination of morphine and bupivacaine, fentanyl and bupivacaine, or bupivacaine as the sole anesthetic. Fentanyl is administered at concentrations between 2 and 5 μg/ml. Bupivacaine is administered at concentrations between 0.25% and 0.125%.

The dressing of the epidural catheter in both groups consisted of transparent tape (Tegaderm™ Transparent Film Dressing, 3M, USA). Patients were followed for 6 days following the center's policy requirements.

Eligibility

To be enrolled and randomized, patients had to meet the eligibility criteria of the study. Patients were eligible if they were 18 years and older, were planned to undergo major surgeries (abdominal, thoracic, and orthopedic) at the center, provided consent to general anesthesia as well as pain control following the surgery through epidural catheter insertion, and their physical status have met the definition described by the American Society of Anesthesiologists (ASA) for physical status classes: ASA I and II. Those who were prone to coagulopathy were excluded from the study.

Sample size

Using a power of 95%, a 5% level of significance (α2), a rate of dislodgment of 15.38% (reported by the pain service in 2012), and with the assumption that tunneling will help reduce dislodgment to more than 50%, we estimated that 73 participants were required in each group. With consideration of exclusions or withdrawals, a total of 200 patients were required.

Randomization and allocation to treatment

A master randomization plan was generated for the study using random number tables. The randomization plan was kept with a nurse coordinator. Anesthetists were not aware of the randomization until the day of surgery. The randomization was provided in a closed paper slip indicating the patient identification and randomization group.

Patients were not made aware to their randomization to the mode of fixation employed. Between April 2015 and April 2016, 244 patients were evaluated for recruitment and 200 were randomized in total.

Data management

Data were collected as part of the “Daily Follow-up” Excel sheet used to record data on patients of the Acute Pain Service. Data collected included general patient demographic information, date of birth, weight, height, events such as dislodgment of catheters, resting and dynamic patient's FPS, patient's complaints about the incidence of uncontrolled pain, and type and number of adverse events.

Statistical analysis

Baseline characteristics, primary and secondary endpoints, were compared between the two groups using Chi-square and Fisher's exact test for statistical significance. The number of patients reporting uncontrolled pain and those with FPS (resting and dynamic) >4 were also compared in both groups. Data were reported in their absolute frequencies and as percentages. Comparison between the groups for the duration of epidural analgesia was carried out using Student's unpaired t-test. Statistical significance was determined at two-sided P ≤ 0.05. Analyses were performed in R version 3.5.0 and relevant packages.[17181920]

RESULTS

Two hundred and forty-four patients were considered for enrollment. Forty-four patients were excluded before randomization for different reasons including cancellation of surgery, switching the patients to PCA, or when epidural insertion was found unnecessary. Two hundred patients were enrolled, randomized, and completed the study. One hundred and eight were randomized into the nontunneled group while 92 were randomized into the tunneled group. The patient flow diagram in Figure 1 provides the details.

Figure 1

Patient flow diagram

Sixty-three percent of the patients were male and 37% were female. Patients were between the age of 20 and 85. Seventy-two percent (71.9%) of the patients were found to have a body mass index >24.9 at the time of epidural placement. Comorbidities consisted were mainly cardiac issues, hypertension, or diabetes. The majority of the surgeries performed (55%) involved the gastrointestinal tract. Most of the epidural insertions (94%) were carried out at the thoracic level. Additional details are provided in Table 1.

Table 1

Demographic characteristics of the study groups

The majority of the patients (96%) received a combination of fentanyl and bupivacaine for pain control [Table 2].

Table 2

Epidural administered anesthetics

The mean number of days for epidural analgesia was similar in both groups, in the tunneled group, it was 2.7 (range 1–4 days) compared to 2.5 (range 1–5) in the nontunneled group. The epidural catheters were found dislodged in 18 patients (7.6%) in the tunneled group compared to 11 patients (10.2%) in the nontunneled group. The difference in the number of dislodgments between the groups was assessed as statistically insignificant (P = 0.699). In the tunneled group, dislodged catheters were found loose, oozing from the insertion site or with a wet dressing. In the nontunneled group, the dislodged catheters were generally described as loose. Table 3 provides distribution of dislodgment in both groups.

Table 3

Incidence of epidural dislodgment

There was no difference in uncontrolled pain being reported in both groups (0.2823). Sixty-three patients reported such episodes (total of 111). Furthermore, the difference in the number of patients' FPS (at rest and dynamic >4) was also of no statistical significance (P = 1.00) [Table 4].

Table 4

Incidence of pain within 6 days, as reported by patients and where facial pain scores are reported to be >4

There were 69 reports of adverse events for a total of 49 patients. Adverse events included nausea, vomiting, itching, sedation, hypotension, motor block, and numbness. The difference in the number of adverse event reports in both groups was not significant. Similarly, the difference in the number of patients with adverse events in both groups was also considered not to be statistically significant (P = 0.46). Details are provided in Tables 5 and 6.

Table 5

Reports of adverse events within 6 days

Table 6

Patients with adverse events within 6 days

DISCUSSION

Acute pain episodes, frequently encountered in medicine, are a pronounced complication of postoperative care. The aim of postoperative pain management is to reduce and at best and eliminate pain with the least medications' side effects.[21] The American Pain Society's guidelines for the management of postoperative pain, established in 2016, recommend neuraxial analgesia for major thoracic and abdominal procedures.[22] Dislodgment remains to be a challenge for pain management practitioners. Philips et al. reported migration of 50% of epidural catheters from their original placement.[6] The method employed in fixing the epidural catheter to the patient's skin influences the success of epidural analgesia.[23]

Between 2012 and 2017, 2049 epidural catheters were inserted to control postoperative pain at the center. Dislodgment rates varied on monthly basis, ranging from 0% to 15.38%. The dislodgment rates in this study were reported to be within this range. In the tunneled group, dislodgment rates were reported to be lower than those in the nontunneled group but with no significant statistical difference (7.6% compared to 10.2%, P = 0.699).

Tunneling has been shown to lower inward and outward movement of epidural catheters.[8] In addition, tunneling is usually used to reduce the chance of bacterial contamination of epidural catheters.[9] Tunneled epidural catheters are described as effective and safe for pain relief in pediatric patients.[24]

Our findings were consistent with de Jong and Kansen, who have reported no difference in dislodgment rates between tunneling and no tunneling.[25] Bougher et al. stated that outward movement was not reduced with tunneling.[7] In 2016, Sharma et al. compared tunneling to fixation devices such as LOCKIT® and found that tunneling did not outperform them.[26] They supported the use of fixation devices, describing them as safe and comfortable.

In this study, tunneling was used for short-term postoperative analgesia. Epidural catheters were not placed for longer than 6 days as per the center's policy. The results of the study show that dislodgment rates did not improve by tunneling.

Tunneling is still an option for fixing catheters in lieu of fixation devices, which we perceive as expensive. Based on individual patient characteristics and available techniques, the anesthetist is free to choose the fixation method to employ. Chakraborty has suggested changes in tunneling technique to increase safety.[27] Kumar and Chambers have proposed that tunneling may be useful in obese patients, as sweat and friction may peel off the catheter. They have described different advantage and disadvantages to consider.[28]

Bomberg et al. has shown that tunneling was associated with reduced infection rates and described it to have the strongest effect against infections.[11] Similar results were discussed in pediatric patients. Tunneled caudal epidural catheters were recommended for the use in children for postoperative analgesia as they were without an increased risk of epidural infection.[10]

In our study, we focused on dislodgment, pain, and adverse effects. We had no reports of infected catheters. This is probably due to the short duration of the epidural analgesia. The chances of infection in epidural analgesia of postoperative pain is lower when compared to chronic epidural treatment.[29]

Episodes of uncontrolled pain were comparable. We did assume that if epidural analgesia went uninterrupted, we should have better outcomes for uncontrolled pain in the tunneled group. The level of pain was not affected.

Adverse events were generally limited in both groups. They were also consistent with what we usually experience in practice.

This study is not without its limitations. Additional data on pain control in both settings may have been appropriate for further comparison. The study depended on available data from charts and practice that may not be comprehensive. Feedback from anesthetists and staff about the method of fixation employed may offer additional insights on best practices. Feedback of the patient, although important, was not obtained.

We did not gather information about the tunneling procedure, and it was left to the discretion of the anesthetist. If there had been any variation in the procedure followed or a difference in skill, this study will not provide answers.

CONCLUSION

We hoped that tunneling will offer a decrease in the rate of dislodgment. However, we have no reason to disfavor the use of tunneling to fix epidural catheters in place. While considering what is appropriate for the patient, the anesthetist is free to choose the method to follow in fixing the catheter.

Financial support and sponsorship

This work was financially supported by King Hussein Cancer Center, only.

Conflicts of interest

There are no conflicts of interest.