Also called a wound or diffusion catheter, a soaker catheter is a cheap, easy and effective tool to improve patient comfort after amputation, excision of large skin and subcutaneous masses and mastectomy.
You can purchase a commercial soaker catheter, or you can make one for a fraction of the cost in a few minutes, during surgery. To avoid increasing anesthesia time, you can also make one preoperatively … assuming you have ethylene oxide sterilization available. The main drawback is that one catheter may not have the appropriate length for a particular patient.
Ideally, several catheters would be made ahead of time. Let’s go over the six easy steps to make your own soaker catheter.
Most patients can use a 5F red rubber catheter. Measure the length of your incision and add 2-4 inches at the proximal end of the catheter. Cut off the end of the red rubber at the appropriate length. The premade opening is much too big for our purpose.
2. Pinch and heat
The next step is to seal the cut end. Burning the tip of the red rubber catheter with a lighter will not work: It will melt or burn it without getting sealed. The better way is to clamp the end with a hemostat. Using a lighter, an assistant can heat the instrument near its tip to seal the catheter edges caught between the jaws.
Using an empty 6 ml syringe, inject air into the catheter to confirm an airtight seal.
4. Poke holes
Place the catheter on a small stack of gauze squares and use a 25 G needle to puncture it through and through every few millimeters. It is important to stagger the holes along the catheter. In other words, each time you poke the needle through, turn the catheter 90 degrees before poking again.
5. Test again
Using part of the total volume to be administered, test the catheter by attaching the syringe and injecting bupivacaine or lidocaine until tiny fluid pearls form along the length of the catheter.
Feed the sealed end of the catheter through a stab incision in the skin, a few centimeters away from the surgical incision. Implant along the incision, in the appropriate tissue plane. Make sure that the needle holes are not exposed outside the skin. Close the incision normally. Place an injection cap on the catheter and secure its proximal end with a purse-string and Chinese finger-trap suture.
There are two options to administer local anesthetic drugs through the soaker catheter: intermittent or continuous. Because of its longer duration of action (four to six hours), 0.5 percent bupivacaine can be given in boluses at 1-2 mg/kg every 6 hours. If you have a syringe pump, a 2 percent lidocaine constant rate infusion can be administered at 1-2 mg/kg/hour.
You can buy a commercial soaker catheter … or you can make one for well under $2. You will need:
* 5 French red rubber catheter
* 22 G needle
* 25 G needle
* injection cap.
* suture material
Depending on the patient and the procedure, the soaker can be removed after a few hours or a few days. In one study,* catheters were left in place for an average of 36 hours.
The skin suture is cut, and the catheter is gently pulled out of the wound. No skin suture is necessary. The stab incision will quickly heal by second intention.
Complications are rare. They include disconnection of the catheter, self-trauma, ascending infection, seroma or hematoma formation and lidocaine overdose. All can be prevented with careful planning and monitoring. Decrease drug doses by 50 percent in pediatric, geriatric and liver disease patients.
While a soaker catheter can’t replace systemic pain management, it can increase patient comfort and decrease the dosage of other pain medications. It is an easy and cheap modality you can include in your multimodal analgesia protocols. Try it on your next amputation patient.
*A. Abelson et al. “Use of wound soaker catheters for the administration of local anesthetic for post-operative analgesia: 56 cases.” Vet Anaesth Analg. 2009, Vol. 36, N. 6, p. 597-602.
Katie Kegerise, a certified veterinary technician in Reading, Pa., contributed to this article.