Dose:  0.2 to 0.5 ml

Comments:  Dilute hydrochloric acid (0.1 N HCl) can be used to clear central venous catheter (CVC) obstruction. CVC obstruction may occur due to thrombosis, precipitation of calcium salts, or precipitation of medications. In the case of obstruction due to thrombosis, the treatment of choice to re-establish patency is urokinase. If a precipitate has formed from calcium-phosphate crystals use of 0.1 N hydrochloric acid has been used to restore patency of catheters. Shulman (JPEN 1988; 12:509) instilled between 0.2 to 1.0 ml of 0.1N HCl into obstructed catheters (due to medication or TPN precipitates). Catheter patency was restored in all four cases. In cases of complete occlusion, there was usually sufficient pliancy of the catheter to inject 0.2 ml of HCl using a 1 ml syringe (great care needs to be taken because administration with a 1 ml syringe can generate pressure great enough to rupture the catheter). The small syringe is able to generate a large amount of pressure causing a small amount of ballooning of the catheter. If the occlusion does not immediately resolve, the acid is allowed to remain in the catheter for one hour. It may take several hours for patency to be restored. If patency has not been restored by 24 hours, the catheter will need to be removed. Duffy (J Pediatr 1989; 114:1002) used doses of 0.2 to 0.5 ml to treat catheter occlusion in 19 patients. If no precipitate was recognized, urokinase was tried before HCl. Of the 19 episodes, eight cleared after a single instillation, two cleared after 2 instillations, and one required three instillations of the acid. Five cases only partially cleared, and three cases were not able to be cleared. If the precipitate was formed from a medication, one must decide whether decreasing the pH will improve solubility. If the medication is acidic, it is reasonable to try dilute HCl (J Intrav Nurs 1992; 15:36). The pH in this solution is 2. Take care to avoid contact with any skin surfaces.

Toxicity: In the reported cases by Duffy and Shulman reported above, there were no adverse effects noted with the use of the acid. Hydrochloric acid used in the concentrations and volumes suggested above should produce no metabolic side effects. For example, 9 ml of 0.1 N hydrochloric acid given to a 3 kg infant will change the serum bicarbonate level by only 1 mmol/l (Shulman. JPEN 1988; 12:509). Breaux (J Pediatr Surg 1987; 22:829) reported that 40% of the patients developed a febrile reaction following the use of HCl. Although there is some concern that an infusion of dilute hydrochloric acid can lead to catheter degradation, Shulman (JPEN 1995; 19:407) reported that an invitro study failed to show any adverse effects from daily infusions of 0.1 N HCl over an 8 week period.

Preparation: Available as 0.1 N hydrochloric acid.