Table 1.
Respiratory mechanics using three different PEEP titration strategies during supine and prone positioning
| PEEPARDSNetwork | PEEPEstat,RS | PEEPPtpexp | p values | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Supine | Prone | Supine | Prone | Supine | Prone | Positioning effect | PEEP strategy effect | Positioning and PEEP strategy interaction | |
| RR (breaths/min) | 22.3 ± 1.9 | 22.3 ± 1.9 | 22.3 ± 1.9 | 22.3 ± 1.9 | 22.3 ± 1.9 | 22.3 ± 1.9 | 1.000 | 1.000 | 1.000 |
| VT (mL/kg PBW) | 6.2 ± 0.3 | 6.2 ± 0.3 | 6.2 ± 0.3 | 6.2 ± 0.3 | 6.2 ± 0.3 | 6.2 ± 0.3 | 1.000 | 1.000 | 1.000 |
| Ppeak,RS (cm H2O) | 23.3 ± 5.1 | 23.5 ± 4.5 | 25.0 ± 5.1 | 23.3 ± 4.5* | 30.6 ± 8.8 | 27.2 ± 8.8* | < 0.001 | < 0.001 | < 0.001 |
| Pmean,RS (cm H2O) | 13.5 ± 2.9 | 13.5 ± 2.7 | 15.8 ± 4.0 | 13.6 ± 3.4* | 20.5 ± 6.1 | 16.5 ± 6.5* | < 0.001 | < 0.001 | < 0.001 |
| Pesinsp (cm H2O) | 14.2 ± 3.5 | 11.4 ± 3.7* | 14.8 ± 4.4 | 11.4 ± 4.6* | 17.1 ± 5.7 | 13.0 ± 6.0* | < 0.001 | < 0.001 | 0.007 |
| Pesexp (cm H2O) | 11.3 ± 3.1 | 7.7 ± 3.2* | 12.1 ± 4.0 | 7.9 ± 4.0* | 13.4 ± 5.4 | 9.4 ± 5.4* | < 0.001 | < 0.001 | 0.572 |
| ∆Pes (cm H2O) | 2.9 ± 1.6 | 3.6 ± 1.9* | 2.7 ± 1.5 | 3.5 ± 1.9* | 3.0 ± 1.8 | 3.5 ± 2.0* | < 0.001 | 0.141 | 0.339 |
| Estat,RS (cm H2O/L) | 21.3 ± 6.5 | 21.7 ± 6.0 | 19.5 ± 5.8 | 20.8 ± 5.2* | 20.7 ± 8.0 | 22.1 ± 6.4* | 0.032 | 0.023 | 0.255 |
| Estat,CW (cm H2O/L) | 7.1 ± 4.2 | 9.0 ± 5.0* | 6.6 ± 4.2 | 8.6 ± 4.9* | 7.3 ± 4.8 | 8.8 ± 5.2* | < 0.001 | 0.132 | 0.397 |
| Estat,L (cm H2O/L) | 14.0 ± 5.5 | 13.0 ± 5.3 | 12.8 ± 4.8 | 12.6 ± 5.4 | 13.4 ± 6.9 | 13.9 ± 6.8 | 0.565 | 0.093 | 0.087 |
| Mechanical power (J/min) | 17.5 ± 5.7 | 17.6 ± 5.5 | 19.2 ± 5.9 | 17.5 ± 5.8* | 24.4 ± 9.8 | 21.0 ± 9.6* | < 0.001 | < 0.001 | < 0.001 |
| IAP (cm H2O) | 8.3 ± 2.8 | 11.1 ± 3.0* | 8.7 ± 2.9 | 11.1 ± 3.5* | 9.9 ± 3.5 | 12.1 ± 3.8* | < 0.001 | < 0.001 | 0.238 |
| VD/VT (%) | 28.5 ± 10.9 | 25.2 ± 9.0* | 27.6 ± 10.8 | 24.7 ± 9.5* | 28.4 ± 10.5 | 25.8 ± 9.5* | < 0.001 | 0.224 | 0.739 |
| Ventilatory rate | 2.09 ± 0.5 | 2.11 ± 0.5 | 2.12 ± 0.5 | 2.13 ± 0.5 | 2.13 ± 0.5 | 2.14 ± 0.5 | 0.308 | 0.176 | 0.345 |
| EELV (mL) | 1630 ± 552 | 1972 ± 693* | 1920 ± 556 | 1993 ± 627 | 2140 ± 615 | 2108 ± 736 | 0.011 | < 0.001 | < 0.001 |
Values are means ± standard deviation of 40 patients with moderate to severe ARDS. Two-way repeated measures ANOVA was used to compare the effects of different PEEP titration strategies on respiratory mechanics during supine and prone positioning (p < 0.05)
Bold numbers represent statistically significant differences between groups
∆Pes difference between esophageal pressure at plateau airway pressure and positive end-expiratory pressure, EELV end-expiratory lung volume, Estat,CW static elastance of the chest wall, Estat,L static elastance of the lung, Estat,RS static elastance of the respiratory system, IAP intraabdominal pressure, PBW predicted body weight, PEEP positive end-expiratory pressure, PEEPARDSNetwork PEEP titrated according to the ARDS Network lower PEEP table, PEEPEstat,RS PEEP titrated according to the lowest elastance of the respiratory system, PEEPPtpexp PEEP titrated according to end-expiratory transpulmonary pressure, Pesexp esophageal pressure at positive end-expiratory pressure, Pesinsp esophageal pressure at plateau airway pressure, Pmean,RS mean airway pressure of the respiratory system, Ppeak,RS peak airway pressure of the respiratory system, RR respiratory rate, VD/VT ratio of physiologic dead space to tidal volume, VT tidal volume
*Significant differences at each PEEP titration strategy between supine and prone positioning