You would think that the deep incisions from open heart surgery and the large wound it leaves, including cutting into chest bones etc. would be the biggest problem facing patients’ post heart surgery. Not so, says new research presented at the American Heart Association’s Scientific Sessions 2011. In fact, its pneumonia that is the biggest problem following heart surgery.

The study also showed that most infections occur about two weeks after surgery, not one week as physicians previously thought.

Michael A. Acker, M.D., the study’s lead researcher and professor and chief of cardiovascular surgery at the University of Pennsylvania Medical Center in Philadelphia, Pa. confirmed the unexpected results :

“It’s not what we
expected to find.”

Researchers analyzed more than 5,100 patients in a heart surgery registry. Patients, average age 64 years, were treated at nine U.S. academic medical centers and one Canadian center. The median time to major infection was 14 days after heart surgeries. Forty-three percent of all major infections occurred after hospital discharge.

Acker continues :

“Half of these patients had no evidence of infection before they were discharged from the hospital … Then they had to return because of the new infection. One implication is that patients must be followed more closely after discharge.”

The study, did not include any patients who were infected before surgery and researchers found 761 infections in total : 300 were classified as major infections (occurring in 6 percent of patients) and 461 were minor (in 8.1 percent of patients). Of the major infections:

  • Pneumonia, infection of the lungs, occurred in 2.4 percent of all patients.
  • C. difficile colitis, an intestinal infection, occurred in 1.0 percent.
  • Bloodstream infections occurred in 1.1 percent.
  • Deep-incision surgical site infections occurred in 0.5 percent.
  • Minor infections included urinary tract and superficial incision site infections.

The majority of procedures performed were isolated coronary artery bypass graft and aortic and mitral valve surgeries. Seventy-four percent were elective surgeries and 26 percent were non-elective or emergency surgeries.

A number of risk factors were seen to increase the possibility of developing infection, including congestive heart failure, hypertension, chronic lung disease, corticosteroid use prior to surgery, and length of cardiopulmonary bypass time.

Acker said :

“In the next level of analysis, the focus will be on differences in care, from the types of dressings, the types of antibiotics, and the types of surgical preparations, to show what processes of care are associated with decreased incidence of infections …The registry will allow us to modify our best practices to manage post-operative infections.”

Co-authors are Michael Argenziano, M.D.; John D. Puskas, M.D., M.Sc.; T. Bruce Ferguson, M.D.; Annetine C. Gelijns, Ph.D.; Keith Horvath, M.D.; Marissa A. Miller, DVM, MPH; Stacey Welsh, R.N.; Ellen Moquete, R.N.; Kevin N. Su, B.S. Alan Weinberg, M.S.; Alan J. Moskowitz, M.D.; Patrick T. O’Gara, M.D. and Eugene H. Blackstone, M.D.

The National Heart, Lung, and Blood Institute, National Institute of Neurological Disorders and Stroke and Canadian Institutes of Health Research funded the study.

In related news, researchers from a Milwaukee hospital treated patients’ skin with a special antibacterial solution the night before and the morning of the procedure and had far fewer infections. They also included a strict three-minute drying time for the surgical skin preparation. These steps decreased implant infection rates from 1 percent to 0.24 percent at a year following the implant placement, and impressive 75% reduction.

Written by Rupert Shepherd