Risk Factors Identified for Pneumonia Following Heart Surgery

A new study has confirmed that ventilator-associated pneumonia (VAP) is the main cause of nosocomial infections in patients undergoing major heart surgery (MHS), and has also identified the main risk factors.

Researchers from the Hospital General Universitario Gregorio Marañón (HGGM; Madrid, Spain) and 25 other institutions that form part of the European Study Group on Nosocomial Infections (ESGNI; Madrid, Spain) and the European Workgroup of Cardiothoracic Intensivists (EWCI), conducted a prospective study of 971 patients in eight European countries undergoing MHS who developed suspicion of VAP. The researchers found that 4.4% acquired some form of nosocomial infection, and that VAP accounted for almost half of these (2.1%). The microorganisms responsible for VAP were identified as Enterobacteriaceae (45%), Pseudomonas aeruginosa (20%), methicillin-resistant Staphylococcus aureus (MRSA, 10%) and a range of other microorganisms.

The researchers also found that, apart from the amount of time spent on mechanical ventilation, other risk factors for the development of VAP included transfusion requirements, ascending aorta surgery, and the need for reintervention for hemorrhage or cardiac tamponade in the immediate postoperative period. The investigators recommended that anticipative or preemptive antimicrobial therapy should be explored as one of the few potential interventions to avoid VAP in patients remaining under mechanical ventilation for more than 48 hours. The study was published on May 1, 2009, in the open access journal Critical Care, a publication of BioMed Central.

"The crude mortality rate of patients with VAP in our study was found to be 35%; this is significantly more than the mortality rate of 2.3% seen in patients who avoided VAP," said lead author Javier Hortal, M.D., of the department of anesthesia at HGGM. "The overall mortality rate for VAP in patients undergoing MHS may be as high as 16-57%, but many critically ill patients with VAP die because of their underlying disease rather than of pneumonia, which makes analysis difficult."

VAP is a subtype of hospital-acquired pneumonia (HAP), which occurs in people who are on mechanical ventilation that results from an infection which floods the alveoli in the lungs. VAP is distinguished from other kinds of infectious pneumonia because of the different types of microorganisms responsible, antibiotics used to treat, methods of diagnosis, ultimate prognosis, and effective preventive measures.

Related Links:
Hospital General Universitario Gregorio Marañón
European Study Group on Nosocomial Infections