Ventilator-associated pneumonia in neuromuscular, tracheostomyzed patients

Lower-tract respiratory infections are common events in tracheostomyzed mechanically ventilated patients leading to a 10-fold increase in mortality rate particularly in those patients with severely compromized clinical conditions [1]. Our study aimed to assess epidemiology and risk factors for colonization of respiratory tract and development of ventilator-associated pneumonia (VAP) in home-living, tracheostomyzed and mechanically ventilated patients with neuromuscular disease. Design A retrospective study. Setting An ICU ambulatorial service for neuromuscular disease. Patients Data of 27 patients (20 male) that underwent a routine visit every 6 months, collected from 1995 until 2003, were analyzed. Thirteen had amyotrophic lateral sclerosis (ALS) and one spinal muscular atrophy (ALS-like group); seven had Duchenne's dystrophy (DMP), two congenital dystrophy, three metabolic dystrophy and one supranuclear progressive paralysis (DMP-like group). The median age was 54 years (interquartile range, 31–63). The median mechanical ventilation period (MVP) was 71 months (30–120). Thirteen patients had severe dysphagy and ineffective cough reflex, 12 of them were alimentated by percutaneous enteral gastrostomy and one by nasal-gastric tube, ALS-like patients were more frequently dysphagic than DMP-like patients (P < 0.01). Low respiratory tract infections (LRTI) were defined in the presence of cough or an abnormal increase of bronchial secretions, with or without fever that required antibiotic therapy; pneumonia was defined as LRTI with a new pulmonary infiltrate at thorax radiography [2]. Measurements and main results VAP incidence was 52 episodes for 100 patients per year of MVP. The median MVP was lower in dysphagic patients (33 months [20.75–70.50]) than in non-dysphagic patients (120 months [80–156]) (P < 0.01) and in ALS-like patients (33 months [24–73]) than in the DMP-like group of patients (96 months [69.5–144]). Dysphagic patients had an higher colonization incidence (Ci) (P = 0.01), LTRI incidence (LTRIi) (P = not significant), and VAP incidence (VAPi) (P = 0.02) than nondysphagic patients, per month of mechanical ventilation. ALS-like patients had a higher Ci and VAPi than DMP-like patients (P = not significant). Bivariate analysis shown a positive correlation between Ci and LTRIi and VAPi (P < 0.01 for both). MVP was negatively correlated with Ci (P < 0.01) and VAPi, although the P value was 0.06. Pseudomonas aeruginosa was the most isolated bacteria in colonization (48%), LTRI (45%) and VAP (52%) episodes. Conclusion VAP is a frequent event in our patients. Dysphagic patients, although alimentated by gastrostomy, are more frequently colonized and this enhances the risk to develop VAP more than in nondysphagic patients. Patients ventilated for a long period seem to develop a natural defence from colonization. The longer the MVP, the less the patient is prone to be colonized and, likely, to develop VAP. The risk of developing VAP is no different in ALS-like and DMP-like disease although the dysphagy prevalence differs. A bigger sample is needed to definitively prove this.