Picture of a small area of opening 2 weeks after placement of the intrathecal drug delivery system in a patient with chronic nonmalignant pain. System was explanted as small purulent drainage was elicited; this picture is taken after initiation of intravenous antibiotic therapy upon presentation to the pain clinic and direct admission to the hospital. Image from personal library
Case reports describe conditions mimicking postoperative wound infection, including one case of an acute exacerbation of hereditary coproporphyria after intrathecal pump insertion . In this case, symptoms developed rapidly within hours after pump placement, unusual for acute wound infection.
Four categories of complications with intrathecal pump insertion have been described: mechanical, related to medication, catheter, or procedure . Procedure-related causes are the most common. They cause impaired wound infection and impair healing. The subcuticular closure technique may contribute to complications. The scar is more aesthetic, but the closure may not provide adequate prolonged approximation of skin edges under continuous tension from the underlying pump. In a population with impaired wound healing, securing the ends of the subcuticular suture may offer additional wound integrity.
If infection is suspected, wound cultures are obtained to guide antibiotic therapy, before incision, drainage, and washout. The wound is evaluated for possible deep fascial layer involvement, which may ultimately require pump removal. The workup should include CBC with differential, C-reactive protein, and erythrocyte sedimentation rate. Baseline values obtained before pump implantation can be compared to values when infection is suspected. Abdominal computed tomography (CT) with contrast evaluates for fluid collections, abscess, or free air.
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Patients with malignancy may be malnourished and cachectic, making pump size and site selection critical in preventing wound dehiscence. The pump should not be placed over bony structures including the iliac crest or rib cage to prevent wound dehiscence and infection. A pump site over clothing friction points, such as a waistband, is not recommended because contact with the surgical wound may reduce wound healing. For surgical preparation, chlorhexidine is superior to iodine in preventing surgical site infection [7, 8]. Administering perioperative antibiotics within 1 h of skin incision minimizes infection. So does proper skin decontamination and preparation with an antiseptic agent and sterile draping . For patients with penicillin allergy not listed as anaphylaxis, studies have shown less adverse reaction with cefazolin than clindamycin . Specific surgical techniques may also reduce risk. Placing the surgical incision relative to the pocket so that it does not cross suture lines over the implanted device, using monofilament in place of braided suture, using antibacterial over a non-antibacterial suture, minimizing dead space within the surgical sites, and obtaining optimal hemostasis can prevent wound dehiscence and infection [10, 11]. A sufficiently large pocket must be created to minimize tension around the device. Rectus sheath implantation for patients with thin body habitus can be considered . Minimizing operative time may be the single most important step taken to prevent postoperative wound infection .
36.5.2 Treating Pump Pocket Infection
If deep pocket infection is diagnosed, pump removal may be necessary to control and treat the infection . In some cases, the pump has been salvaged with intra-reservoir antibiotic, repetitive local application of antibiotic-impregnated collagen fleece, and using rectus abdominis muscle flap and split-thickness skin graft to treat infection in a case of skin breakdown [6, 13, 14]. Timely diagnosis and treatment reduce the risk of superficial infections from penetrating deeper tissue or the pump pocket, necessitating vigilance in the postoperative period. With clear instructions for care of the incision as well as frequent follow-up visits, the healing process can be closely monitored.
Cancer patients with underlying nutritional deficiencies or infectious conditions may be at increased risk. All infections should be treated before device implantation, and nutritional status should be optimized. Obtaining albumin, prealbumin, total protein, absolute leukocyte count, and transferrin levels preoperatively may help guide nutritional status .
Targeted drug delivery via implantable devices relieves pain and improves quality of life for cancer patients. The impairments to healing from malignancy and chemotherapy should not deter practitioners from such intervention. The increased risk for impaired wound healing or infection should be assessed by the clinician and discussed with the patient. Consistent and continuous patient education, vigilant clinician monitoring, commitment to surgical best practices, and, when necessary, the expertise of wound care consultants give cancer patients access to pain relief via implantable devices.
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