Assessing Current Peripheral Nerve Block Catheter Fixation and Dressing Strategies: An Equivalence Study

Generally speaking, the goals of affixing and dressing a peripheral nerve block (PNB) catheter include preservation of the position and integrity of the catheter, the integrity of the skin, and avoidance of infection. In order to accomplish this, nerve block catheters at Boston Children's Hospital (BCH) are affixed to a patient's skin and dressed in a number of ways, usually based on provider preference.

Just as care providers routinely employ several combinations of tape, occlusive dressings and skin preparations to secure and protect intravenous catheters (all thought to be standard-of-care based on their frequency of use), so do the members of the regional service dress PNB catheters with various combinations of catheter anchors, Dermabond, Mastisol, and Tegaderms. The exact combinations are based on physician preference and/or habit, though all dressing schemes generally employ at minimum a standard catheter anchor (provided by the catheter manufacturer) and a Tegaderm, frequently with the addition of either Mastisol or Dermabond or both in combination. The four possible combinations in current use are:

1. Catheter anchor and Tegaderm only; 2. catheter anchor, Mastisol and Tegaderm; 3. catheter anchor, Dermabond and Tegaderm; 4. catheter anchor, Mastisol, Dermabond and Tegaderm

As no formal record is kept of dressing type and/or components, there is no accurate way of quantifying the frequencies of these dressing types being employed much less whether certain dressing strategies historically have been more effective than others maintaining the integrity of the catheter and surrounding skin.

These variations in routine practice suggest that there is not agreement about the benefits of adding either Mastisol or Dermabond (or both) to a dressing scheme, especially given their potential liabilities which include skin irritation (Mastisol, anecdotal at BCH), expense (Dermabond, approximately $20/use) and time (a couple of minutes drying time for each of these added elements).

Mastisol is a waterproof, clear liquid adhesive that has largely replaced tincture of benzoin as part of occlusive dressings (for nerve block catheters, IVs, arterial and central lines) as it is reported to have a significantly lower risk for skin irritation (1). As such, Mastisol has essentially become a standard of care for skin fixation and dressing of numerous catheter types. Papers in both the adult and pediatric regional anesthesia literature cite the use of Mastisol as a routine component of catheter fixation and dressing as well (2-4). However, there is little data in the literature evaluating the efficaciousness of Mastisol insofar as reducing catheter leakage or dislodgement and hence justifying its continued use as a part of catheter dressings. One study on healthy adults demonstrated differential forces required to dislodge a taped IV catheter with or without Mastisol (64 ± 1 vs. 46 ± 2 Newtons) however there is no data about catheter dislodgement rates over time in a clinical setting (5). One case report in the pediatric literature proposes a theoretical benefit of Mastisol use insofar as preventing regional anesthesia catheter dislodgement, but it too provides no clinical data (6).

Dermabond is a cyanoacrylate tissue adhesive that forms a strong bond across apposed wound edges, allowing normal healing to occur below and serving as a barrier to bacterial infiltration of the wound. It has been marketed to replace sutures that are 5-0 or smaller in diameter for incisional or laceration repair. This adhesive has been shown to save time during wound repair, to provide a flexible water-resistant protective coating and to eliminate the need for suture removal. Like Mastisol, Dermabond has become a commonplace addition to PNB catheter dressings for securement and puncture/insertion site closure both at BCH and nationally. And again, like Mastisol, there is little available data regarding whether Dermabond use as a part of the dressing scheme makes any difference insofar as catheter dislodgment or prevention of infection. A case series of three patients has been reported as recently as 2003 that described inclusion of Dermabond as a technique offering a simple, alternative method to secure a catheter for a prolonged period of time yet offered no qualitative or quantitative outcomes data (7). Other, more invasive, methods to fasten catheters have been advocated as well, such as suturing, retrograde subcutaneous tunneling (8), and cutaneous sutures (9).

Providers at BCH and elsewhere do not so much disagree as to what is the correct dressing for a nerve block catheter might be as they simply do not have relevant data to guide their decision-making. The physicians at BCH and at other institutions are using that method they believe is best by incorporating their own personal experiences as well as those of other clinicians. All agree that the primary goals, or benefits, of a good dressing system would be effective catheter stabilization, prevention of catheter occlusion or leakage, keeping the site clean and dry, and avoidance of infection. To-date, however, nerve block catheter dressings have not been studied in any rigorous way that might evaluate the various techniques for such outcomes.

There is scant literature available on this topic generally, despite a dressing's presumed importance in maintaining the appropriate position of the nerve block catheter and tip for maximal efficacy. The literature, if it can be called that, is largely comprised of numerous YouTube videos describing dressing and securing methodologies for nerve catheters (10); however none have been reported as having been evaluated in any rigorous prospective or retrospective analysis. (Reference to this general category of YouTube videos is made here as they essentially are a source of, and reflect, the standard of care and as such indicate the relative lack of rigorous evaluation of catheter securing techniques currently available).

Therefore the investigators wish to study whether the addition of Mastisol, Dermabond or both to PNB catheter dressings here at BCH has any influence on outcomes such as catheter dislodgment or function, skin integrity, and avoidance of infection. As such, the investigators propose a prospective, randomized study of equivalence of dressing type with the hypothesis that there is no more than a 10% difference in the rate of catheter dislodgement (the primary endpoint) between the 4 commonly used dressing schemes for PNB catheters at BCH.