Table 1.
Characteristics of intensive care units (ICUs) and patients by ICU staffing model.
| Characteristic* | ICU model | p value | |
| Open | Closed | ||
| ICUs (N) | |||
| Total number | 10 | 13 | |
| Patients/ICU, mean (range) | 28 (5 to 82) | 37 (1 to 97) | 0.42 |
| Academic | 5 | 9 | 0.42 |
| Hospital volume of mechanically ventilated patients† | 0.07 | ||
| Median | 336 | 578 | |
| Interquartile range | 265 to 500 | 421 to 1720 | |
| Patients | |||
| Total number | 277 | 482 | |
| Age, years | 66 (15) | 57 (18) | <0.001 |
| Female | 43% | 37% | 0.09 |
| Race | 0.55 | ||
| White | 73% | 71% | 0.03 |
| Black | 5% | 10% | |
| Asian | 4% | 5% | |
| Hispanic | 1% | 2% | |
| Other or unknown | 17% | 12% | |
| APACHE III score | 90 (29) | 87 (30) | 0.34 |
| PaO2 to FiO2 ratio | 147 (63) | 149 (67) | 0.63 |
| Day 1 tidal volume (cc/Kg PBW)|| | 11.2 (2.5) | 10.0 (2.2) | <0.001 |
| ALI risk factor | <0.001 | ||
| Sepsis | 83% | 68% | |
| Trauma | 0% | 11% | |
| Other | 17% | 21% | |
| >50% alveolar opacity in three or more quadrants on chest X-ray | 43% | 32% | <0.01 |
| Postoperative admission | 22% | 22% | 0.86 |
| Pulmonary consultant involved in care | 76% | 81% | 0.08 |
* represents mean (standard deviation) unless otherwise noted. Percentages may not add to 100% due to rounding.
† excludes patients (n = 52) cared for in the federal hospital in King County
||Data missing for 12 (4%) of patients in open ICUs and 32 (7%) of patients in closed ICUs.
ALI = acute lung injury; APACHE = Acute Physiology Assessment and Chronic Health Evaluation; FiO2 = fraction of inspired oxygen; PaO2 = partial pressure of arterial oxygen; PBW = predicted body weight or measured body weight if height not recorded.