Patient demographics
| Control (N=56) | VA-LRTI (N=52) | ||
| Age, years | Median (IQR) | 59 (47–67) | 59 (42–68) |
| Male | N (%) | 41 (73.2) | 31 (59.6) |
| Days on ICU* | Median (IQR) | 9 (5–13) | 7 (5–10) |
| Admission type | Medical—N (%) | 32 (57.1) | 18 (34.6) |
| Emergency surgical—N (%) | 15 (26.8) | 16 (30.8) | |
| Planned surgical—N (%) | 8 (14.3) | 18 (34.6) | |
| Unscored—N (%) | 1 (1.8) | 0 0 | |
| Trauma | N (%) | 13 (23.2) | 20 (38.5) |
| Neurosurgery | N (%) | 11 (19.6) | 16 (30.8) |
| COPD | N (%) | 6 (10.7) | 8 (15.4) |
| ARDS | N (%) | 4 (7.1) | 0 (0) |
| CPIS | Median (IQR) | 5 (4–6) | 7 (5.8–7) |
| APACHE II | Median (IQR) | 20 (15–23) | 17 (11–22) |
| Temperature, °C | Median (IQR) | 38 (37–39) | 38 (37–38) |
| WCC, 109/L | Median (IQR) | 15 (10–21) | 13 (12–18) |
| PaO2/FiO2, mm Hg | Median (IQR) | 232 (156–270) | 240 (171–284) |
| Pmax, cmH2O | Median (IQR) | 20 (16–25) | 21 (16–24) |
| PEEP, cmH2O | Median (IQR) | 8 (5–10) | 7.5 (5–10) |
| Tidal volume, mL | Median (IQR) | 476 (417–550) | 487 (411–602) |
| Confirmed VA-LRTI | VAP—N (%) | 41 (79) | |
| VAT—N (%) | 11 (21) | ||
| Culture results† | N (%) | ||
| Acinetobacter pittii | 1 (1.9) | ||
| Enterobacter cloacae | 2 (3.8) | ||
| Escherichia coli | 3 (5.8) | ||
| Haemophilus influenzae | 5 (9.6) | ||
| Klebsiella spp | 6 (11.5) | ||
| Pseudomonas aeruginosa | 9 (17.3) | ||
| Serratia marcescens | 2 (3.8) | ||
| Staphylococcus aureus‡ | 15 (28.8) | ||
| Stenothrophomas maltophilia | 2 (3.8) | ||
| Other | 7 (13.4) | ||
| ICU LOS, days | Median (IQR) | 22 (14–33) | 21 (15–32) |
| Hospital LOS, days | Median (IQR) | 31 (15–44) | 30 (19–57) |
| ICU mortality | N (%) | 17 (30.4) | 9 (17.3) |
Continuous variables are expressed as median (25th–75th percentile); categorical variables as number of patients (percentage).
*Days on ICU until VA-LRTI suspicion.
†Potentially >1 cultured pathogen per patient.
‡All methicillin sensitive.
APACHE, Acute Physiology and Chronic Health Evaluation; ARDS, acute respiratory distress syndrome; CPIS, Clinical Pulmonary Infection Score; FiO2, inspired fraction of oxygen ratio; ICU, intensive care unit; LOS, length of stay; PEEP, positive end-expiratory pressure; Pmax, maximum airway pressure; VA-LRTI, ventilator-associated lower respiratory tract infection; VAP, ventilator-associated pneumonia; VAT, ventilator-associated tracheobronchitis; WCC, white cell count.