Once Daily High-Dose Gentamicin to Prevent Infection in Open Fractures of the Tibial Shaft: A Preliminary Investigation

George V. Russell, Jr., MD, Chantaé King, Carmen G. May, RN, BSN, MSN, Albert W. Pearsall IV, MD

Disclosures

South Med J. 2001;94(12) 

In This Article

Materials and Methods

Between May 1, 1995, and May 31, 1999, 52 patients between the ages of 18 and 65 with an operatively treated Gustilo type II or III open tibial shaft fracture were identified using a prospectively gathered trauma registry. Three patients who had primary amputation and 2 who had delayed amputation were excluded from the study. Fifteen patients who received cefazolin only, 4 who received broad spectrum antibiotics, 2 who received twice daily gentamicin, and 2 others with incomplete antibiotic records were also excluded from the study. The remaining 24 patients received a cephalosporin and a once daily gentamicin dose of 5 mg/kg. Of these 24 patients, four were lost to follow-up, and four had follow-up for less than 3 months and were excluded from the study, leaving 16 patients for review (Table). There were 3 type II, 6 type IIIA, 5 type IIIB, and 2 type IIIC open fractures. There were 15 men and 1 woman, with an average age of 35 years (range, 28 to 65 years). The average Injury Severity Score10 was 16 (range, 9 to 34). Fractures resulted from crushing injury in 2 patients, gunshot wound in 2, motorcycle accident in 3, pedestrian-car accident in 6, and motor vehicle accident in 3. Follow-up averaged 15 months (range, 3 to 42 months).

Patients were initially assessed and stabilized in the emergency room by the trauma surgery service, which then consulted orthopaedic surgery. A Betadine dampened sponge was placed over the open wound, and the lower extremity was splinted to minimize soft tissue damage. Attempts were made to obtain radiographs before splint application. Intravenous cefazolin (1 g) was administered on arrival to the emergency room. Gentamicin (5 mg/kg) was given if the patient had normal BUN and creatine levels, no history of either renal disease or granulocytopenia, and was not pregnant. After clearance by the trauma surgery service, patients were taken to the operating room for irrigation, debridement, and fracture stabilization.

Wound debridement was done in a meticulous fashion. The open wound was extended proximally and distally approximately 5 cm to facilitate visualization and wound debridement. After initial debridement, the wound was irrigated with 9,000 mL of pulsed lavage (Stryker, Kalamazoo, Mich). Inspection of the open wound was repeated after the irrigation, and debridement was continued as indicated by wound contamination. At completion of debridement, fractures were stabilized using a 4.5 mm plate, 2 reamed nails, 4 external fixators, and 9 unreamed nails. All but one patient, who had a primary wound closure, were returned to the operating room every 48 hours for repeat irrigation and debridement until the wound was clean, at which time the wound was closed. Additional wound closure techniques consisted of 9 delayed primary closures, 4 rotational tissue transfers, and 2 free tissue transfers. Intravenous administration of antibiotics was continued for 48 hours after the definitive wound closure, except in rotational and free tissue transfers, for which antibiotics were continued until drains were removed.

Monitoring for gentamicin serum levels consisted of gentamicin trough determination 30 minutes before the third dose. For patients with an elevated gentamicin trough level, the dosage was decreased, and the trough measurement was repeated before the subsequent third dose. Gentamicin-associated nephrotoxicity was assessed by serologic monitoring of renal function consisting of BUN and creatinine levels examined every 2 days. Each patient who was responsive was queried about prodromal signs of ototoxicity (hearing loss, tinnitus, and dizziness). Audiograms were not obtained.

After discharge from the hospital, patients were examined 2 weeks postoperatively and every 4 to 6 weeks thereafter until fracture union. Further follow-up was arranged on an independent basis. Signs and symptoms of infection were carefully sought. Superficial infections were defined as infections superficial to bone not requiring surgical intervention.[3] Deep infections were defined as those that communicated with the site of the fracture, necessitating operative irrigation and debridement.[3] Serologic examinations of renal function were not done. Audiograms were not done, but patients were asked about possible prodromal signs of ototoxicity during return clinic examinations.

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