Table 2.
Lung Tissue and Gas Distribution With 5 and 45 cm H2O of Airway Pressure
| Variable | Quantitative Analysis of Lung CT | P | |
|---|---|---|---|
| Airway pressure, cm H2O | 5 | 45 | … |
| No. | 20 | 20 | … |
| Total lung | |||
| Tissue, g | 1,336 (1,112-1,586) | 1,439 (1,157-1,575) | .062 |
| Gas, mL | 950 (577-1,230) | 2,905 (2,410-3,345) | < .001 |
| Non-aerated | |||
| Tissue, g | 555 (404-742) | 197 (115-307) | < .001 |
| Gas, mL | 3 (0-10) | 0 (0-2) | .008 |
| Poorly aerated | |||
| Tissue, g | 502 (364-601) | 378 (313-498) | .011 |
| Gas, mL | 192 (160-256) | 199 (164-274) | .852 |
| Normally aerated | |||
| Tissue, g | 255 (156-382) | 777 (598-882) | < .001 |
| Gas, mL | 658 (356-922) | 2,288 (1,474-2,484) | < .001 |
| Over-aerated | |||
| Tissue, g | 3 (0-7) | 31 (18-45) | < .001 |
| Gas, mL | 46 (6-131) | 476 (217-766) | < .001 |
Twenty patients underwent a lung CT at 5 and 45 cm H2O of airway pressure. Herein we compare the distribution of tissue and gas in their whole lungs and in their four compartments at these two airway pressures. Data are reported as median (Q1-Q3). P value refers to the Wilcoxon signed rank-sum test. If the nonaerated compartment had a density > 0 HU (ie, higher than the density of water), the gas volume was considered zero.