Dropping a cranial bone flap; rigid sterilization containers; tourniquet cuffs; OR air exchanges

AORN Journal,  June, 2007  by Victoria Steelman,  Joan Blanchard,  Bonnie Denholm,  Ramona Conner

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QUESTION: Our neurosurgeon wanted to reimplant a cranial bone flap that felt on the floor during a craniotomy. Is this practice safe, and, if so, what is the best way to decontaminate a dropped cranial bone flap?

ANSWER: Dropping a cranial bone flap on the floor is an uncommon event, but, unfortunately, it does occur. In a survey of neurosurgeons, 66% (33 of 50) acknowledged that this had happened in their practice. (1) The high-risk times appear to be when the flap is being elevated, when it is being transferred between the operative field and the sterile table, and when it is being prepared on the sterile table for reimplantation.

Clearly, prevention is the best strategy. Experienced perioperative neurosurgery nurses offered these suggestions to minimize the risk of dropping a bone flap:

* Have an assistant hold the flap during removal.

* Hold the flap with a dry surgical sponge.

* Wrap the flap in a sponge or bag and clamp it to an instrument tray.

* Stand very close to the sterile table when handling the flap.

* Hold the flap with a dry sponge inside a basin when drilling holes.

AORN does not have a recommended practice for decontaminating dropped cranial bone flaps. Likewise, the American Association of Tissue Banks and the American Academy of Neurological Surgeons do not have recommendations for this issue; however, perioperative nurses should be prepared to respond in the event that a cranial bone flap is dropped.

Unlike an instrument or allograft tissue that can and should be replaced, a cranial bone flap specifically fits an individual patient's skull. Allograft tissue is not an option, and a synthetic replacement may not be readily available.

If a custom-made, synthetic prosthesis is manufactured, a second surgery for cranioplasty is necessary. Most neurosurgeons surveyed (ie, 83%) opted for decontaminating the bone flap and reimplanting it during the same surgical procedure. (1) This usually did not result in a postoperative surgical site infection when adequate antibiotic coverage was administered postoperatively. (1)

The issue of whether or not to decontaminate a dropped bone flap or perform a second procedure is complex. The hospital may have a policy to address the situation; however, most facilities leave the decision to the operating surgeon. He or she must weigh the risks and benefits to the patient. Leaving the patient without protection for the brain poses a risk of further injury, and a second surgery poses additional risks. Yet, options for decontamination have not been adequately validated and may increase the risk of surgical site infection. If the decision is made to reimplant the bone flap, steps should be carefully planned and implemented to minimize the risk to the patient and to quickly identify and treat complications.

Cleansing. First, the bone flap should be thoroughly cleaned to remove surface contaminants. Rinsing with saline has very limited effectiveness (ie, 90% of contaminated tissue samples were found to remain infective). (2) A pulse lavage system used during orthopedic procedures for compound fractures has been found to be much more effective. This method removes soil and organisms that may be difficult to kill or eliminate with surface treatment. Pulse lavage alone was found to eliminate the infectivity of 70% of contaminated bone. (2) A separate sterile field should be used and care exercised to avoid splashing on the primary sterile field.

After the surface has been cleaned, further treatment should be used to minimize the residual microbial contamination. The two preferred options for this additional decontamination are

* processing the bone flap in a steam sterilizer or

* soaking the bone flap in antibiotics.

Steam processing and antibiotic soaks both have limitations. First, steam sterilizers are validated for processing surgical instruments, not tissue. There is no validation that steam under pressure will not devitalize the bone, and extended cycles may increase this risk. In one European study, however, this method was found to effectively eliminate infectivity of the surface of artificially contaminated cranial bone flaps. (3) There is no need to penetrate the bone with steam, because the inside of the bone is not the area contaminated.

Soaking in antibiotics alone does not eliminate infectivity of a contaminated bone flap. After soaking in cefuroxime (ie, 1 mg/1 mL) for 60 minutes, 65% of contaminated bone samples remained infective.: After soaking in rifampicin (ie, 0.4 mg/mL) for 60 minutes, 35% of samples remained contaminated. (2) The effectiveness of pulse lavage followed by an antibiotic soak has not been studied, but it is likely more effective than an antibiotic soak alone.

Using antibiotics is preferable to using antiseptics. Antiseptics are intended for topical rather than internal use and have significant limitations.

* Hydrogen peroxide is not effective at all. (3)

* Povidone iodine is neutralized by organic material (4) Soaking in povidone iodine has been found to be partially effective in decontaminating for Staphylococcus epidermis after 10 minutes. (5) This organism, however, is not the predominant flora typically involved in this type of situation.