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Clinically-significant hematomas are a strong predictor of device-related infections following surgery for cardiac device implantation, a study found.

Among patients getting a pacemaker or implantable cardioverter-defibrillator, the 1-year rate of device-related infection -- pocket infection, endocarditis, or bloodstream infections -- requiring hospitalization was 2.4%, , of McGill University Health Centre in Montreal, and colleagues reported online in the Journal of the American College of Cardiology.

Disproportionately than in those without (11% versus 1.5%). Those hematomas were the only independent predictor of infection, with a hazard ratio 7.7 (95% confidence interval 2.9-20.5).

The BRUISE CONTROL trial previously found that pocket hematomas were less common among those continued on warfarin (Coumadin) than bridged with heparin for the implantation and were associated with worsened quality of life and pain. Now, with the results of extended follow-up, "the clinical importance of trying to avoid clinically significant hematoma is even clearer," the investigators wrote.

"Many physicians use intravenous, oral, or both forms of antibiotics after the implantation procedure to reduce infection," according to , of Washington University in St. Louis, and , of the University of Washington in Seattle.

Citing previous literature, however, they noted that "patients who developed an infection were actually more likely to have had antibiotics continued after their procedure," which is why quality improvement measures to reduce hematomas and infection "begin with the clinical fundamentals of avoiding dissection into muscle fibers followed by careful inspection and irrigation to identify bleeding vessels prior to closure of the incision," they wrote in accompanying editorial.

Researchers included 659 patients in the BRUISE CONTROL INFECTION long-term follow-up study. All received warfarin or heparin treatment at the time of surgery.

Notably, antibiotic use upon development of hematoma was not tied with a lower risk of infection (P=0.18).

"A possible explanation is poor antibiotic penetration into the extravascular space of the pocket," Essebag and colleagues wrote.

As to the link between hematomas and infection, they suggested that the tension from hematomas may cause "a breach in the wound allowing for post-operative contamination." The authors added that "it has been shown that up to 48% of intraoperative pocket cultures will grow bacteria, most commonly Staph species found in skin flora."

"An accompanying hematoma then provides a fertile environment for sustained microorganism colonization," they wrote.

Essebag's group could not rule out that the infections they studied occurred "as a result of secondary seeding from a distant entry site," although they did employ an adjudication committee to evaluate each case. Another limitation to the investigation was the possibly inadequate sample size and follow-up time.

Furthermore, Essebag's study "did not address additional interventions that could affect hematoma formation and/or an infection requiring hospitalization. Use of intrapocket prohemostatic agents, pressure dressings, and sandbags was reported, but not standardized," according to Gleva and Poole.

What's more, the pair added, there was no investigation of whether several proposed patient factors -- such as use of immune modulating therapy, chronic kidney disease, elevated blood glucose levels, number of prior device procedures, use of a temporary pacing wire, and presence of a preoperative fever -- were linked to the infection rates seen in the study.

Finally, the editorialists pointed out that patients are increasingly using factor Xa inhibitors, which have been "reported to have in vitro anti-inflammatory properties that theoretically could affect the development of infection."

"Whether or not hematoma or infection rates are similar in these patients compared with those taking warfarin is unknown," Gleva and Poole wrote.

Two trials that could help fill in the answers, the editorialists noted, are (conventional pre-op antibiotics versus addition of antibiotic pocket wash and 2 days of post-op antibiotics) and (using an "antimicrobial envelope" comprised of an antibiotic-eluting resorbable polypropylene mesh sleeve for cardiac resynchronization therapy devices).