Effects of Ethanol Locks on Burst Pressure for Small Caliber Nonpower Injectable Peripherally Inserted Central Catheters

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To the Editor: In our previous work in which patients were consented for the use of ethanol lock therapy (ELT) for catheter salvage, we found the practice to be safe and effective in a wide range of polyurethane catheters (PURs) in the PICU (1). Within that series, we identified that two of eight small caliber, 2.6-Fr nonpower injectable peripherally inserted central catheters (PICCs) failed prematurely after ethanol exposure. It was unclear if the PICC failure was related to ethanol exposure or other factors. Ethanol exposure testing has not been performed by the manufacturer in these catheters and is considered off-label use. In this small bench study, we assessed the burst pressure of 2.6-Fr PICCs following various times of ethanol exposure to determine if ELT contributed to compromise the PUR PICC material. Double lumen 2.6-Fr polyurethane PICCs (Vascu-PICC; Medcomp, Harleysville, PA) were cut into 5 cm long segments. A solution of 95% ethanol was diluted with sterile water for injection to achieve a final concentration of 70% ethanol (Belle Chemical, Billings, MT). Each catheter segment was submerged in either water for 24 hours or 70% ethanol for 0.5, 1, 2, 24, 48, or 84 hours. After each PICC segment was removed from the solution the larger lumen was cannulated with a 25G blood collection butterfly catheter (BD Vacutainer Franklin Lakes, NJ) and secured in place with 0 silk braided suture (Ethicon Johnson & Johnson, New Brunswick, NJ). The prepared PICC segment was flushed with saline then clamped distally with a hemostat. The clamped PICC was then submersed in 5 cm of water. To assess the burst pressure of the catheters, an Arduino Uno R3 microcontroller (Monza, Italy) was used to record pressure data from a harsh media pressure sensor (NPR-101; Amphenol, St. Mary’s, PA) in series with the clamped PICC segment. Each PICC segment was manually flushed until burst was achieved. The burst pressure was recorded as the maximum pressure before segment rupture. A minimum of five PICC segments were tested under each dwell time. A total of 37 PICC segments were included in the analyses (seven segments for the water bath and five segments for each of the times bathed in the 70% ethanol solution). The PICC segments exposed to water had a median burst pressure of 195 pounds per square inch (PSI) (interquartile range, 192–215 PSI). There was a decrease in burst pressure within 30 minutes of dwell in the ethanol solution, which persisted through the 84-minute dwell time period (Fig. 1; Kruskal-Wallis p = 0.0002, Cuzick’s nonparametric test of trend p = 0.007).Figure 1.: Boxplot of burst pressure of 5-cm catheter lengths of various dwell times in 70% ethanol solution. PSI = pounds per square inch.For the Medcomp 2.6-Fr double lumen PICCs, which are nonpower injectable, immersion in ethanol significantly decreases catheter strength. This was evident in catheter segments exposed to 70% ethanol for times as short as 30 minutes. Ethanol locks exhibit favorable outcomes when used for central line-associated bloodstream infection (CLABSI) prevention and catheter salvage therapy in active CLABSIs (2–4). Recent data suggest that larger 4- and 5-Fr PUR catheters, specifically those developed for power injection, exposed to ethanol demonstrate no appreciable change to their integrity (5). The use of ethanol has been increasingly used in PUR catheters in the clinical setting in response to this promising data, although few studies assess smaller PUR catheters frequently used in pediatric populations (6). Even though ethanol locks play a crucial role in CLABSI prevention and catheter salvage therapies, the use of ELT in Medcomp 2.6-Fr nonpower injectable PICC may be inadvisable as even 30 minutes of exposure lead to a significant drop in burst pressure. There may be an overestimation of this effect due to submersion of our catheter samples in ethanol (as opposed to intraluminal ethanol installation), and burst pressures all remained above manufacturer recommendations for infusions or bolus injections regardless of ethanol exposure time (14.5–17.4 PSI [7]). Despite these limitations and considerations, we find the results important to report. Further testing is required to assess whether ELT exposure results in reduced burst pressure in both smaller size (1.9-Fr) nonpower injectable PUR catheters as well as larger power-injectable PICCs, all of which are used in the care of pediatric patients. While PUR catheters of all sizes may display reduced burst pressures following exposure to ethanol, our prior study suggests that the smallest catheters may be most vulnerable to clinically relevant failure.

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