Clinical analysis of patients requiring long-term mechanical ventilation of over three months: Ventilator-associated pneumonia as a primary complication

Objective To evaluate the clinical features, etiology, and prognosis of patients who required long-term mechanical ventilation (LMV) of over three months for respiratory failure following underlying disease, and observation of their clinical course until death. Patients Thirty-seven patients (27 males, 10 females) treated in the internal and medical intensive care unit at Kawasaki Medical School Kawasaki Hospital over the 16-year period from April 1985 to March 2001 were retrospectively studied. Results Many of these patients were elderly males with respiratory disease such as pulmonary emphysema or old pulmonary tuberculosis, which had developed into acute respiratory failure resulting in respiratory tract infection and initiation of mechanical ventilation. The survival rates of one year, three years and five years after the start of mechanical ventilation were 60%, 30%, and 16%, retrospectively, and the prognoses were poor. Respiratory tract infection was the most common and serious complication. Specifically, ventilator-associated pneumonia (VAP) was a complication in 21 patients and also the main cause of death. VAP was observed 2.3 years after the initiation of mechanical ventilation with significant differences in the following risk factors being observed between VAP (+) and VAP (-) groups: chronic obstructive pulmonary disease, duration of mechanical ventilation, prior antibiotics, aspiration of gastric contents and use of histamine-type II receptor antagonist. The causative pathogens of VAP were Pseudomonas aeruginosa and Staphylococcus aureus, which were frequently isolated from tracheal aspirates. All patients with VAP caused by MRSA died shortly after contracting the infection. Conclusions This study has demonstrated that appropriate treatment for respiratory tract infections such as VAP and the prevention of nasocomial infection due to MRSA is of paramount importance for patients requiring long-term mechanical ventilation of over three months.