01.08.2010  Research  Ausgabe 4/2010 Open Access
Bedside quantification of deadspace fraction using routine clinical data in patients with acute lung injury: secondary analysis of two prospective trials
 Zeitschrift:
 Critical Care > Ausgabe 4/2010
Electronic supplementary material
Competing interests
Authors' contributions
Introduction
Materials and methods
Statistical analysis
Results
Mayo n= 109  ARDSnet n= 1,896  

Age in years, median (IQR)  62 (5072)  50 (3864) 
Female gender, n (%)  56 (51.4)  845 (44.6) 
Predicted hospital death, median (IQR)  0.43 (0.190.70)  0.31 (0.140.58) 
PaO2/FiO2 day 1, median (IQR)  118 (82.5164)  145 (108195) 
PaO2/FiO2 day 3, median (IQR)  175 (117, 241)  155 (114.5207) 
Tidal volume (ml) day 1, median (IQR)  420 (360500)  420 (350500) 
PEEP (mmH_{2}0) day 1, median (IQR)  8 (512)  10 (814) 
Estimated deadspace (%) day 1, median (IQR)  72.5 (6478.7)  66.3 (57.573.6) 
Estimated deadspace (%) day 3, median (IQR)  70.8 (61.276.3)  68.2 (59.675.1) 
Hospital mortality n (%)  37 (34)  560 (29.5) 
Duration of mechanical ventilation median (IQR) (days)  6 (311)  10.5 (619) 
Mortality  Odds ratio  95% CI  

Day 1
 
(Per 0.05 increment of dead space fraction)
 
Univariate analysis
 
VdVt  1.33  1.09  1.69 
Multivariate analysis  
Base model (Shock + APACHE III predicted mortality), n= 108  1.28  1.04  1.64 
Base model + PaO_{2}/FiO_{2}, n = 108  1.26  1.08  1.61 
Base model + OI, n = 107  1.25  1.02  1.61 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 108  1.26  1.08  1.64 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 107  1.29  1.02  1.69 
Base model + Vt, n = 108  1.32  1.05  1.70 
Day 3
 
(Per 0.05 increment of dead space fraction)
 
Univariate analysis
 
VdVt  1.47  1.18  1.90 
Multivariate analysis  
Base Model (Shock + APACHE III predicted mortality), n = 108  1.43  1.13  1.87 
Base model + PaO_{2}/FiO_{2}, n = 108  1.35  1.05  1.78 
Base model + OI, n = 85  1.43  1.03  2.11 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 108  1.35  1.05  1.79 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 85  1.43  1.03  2.12 
Base model + Vt, n = 108  1.47  1.14  1.96 
Mortality  Odds ratio  95% CI  

Day 1
 
(Per 0.05 increment of dead space fraction)
 
Univariate analysis
 
VdVt  1.11  1.06  1.16 
Multivariate analysis  
Base Model (Shock + APACHE III predicted mortality), n = 1616  1.09  1.04  1.14 
Base model + PaO_{2}/FiO_{2}, n = 1,610  1.07  1.03  1.13 
Base model + OI, n = 1,492  1.08  1.03  1.14 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 1,610  1.08  1.03  1.14 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 1,492  1.09  1.04  1.15 
Base model + Vt, n = 1,616  1.10  1.06  1.16 
Day 3
 
(Per 0.05 increment of dead space fraction)
 
Univariate analysis
 
VdVt  1.18  1.12  1.24 
Multivariate analysis  
Base Model (Shock + APACHE III predicted mortality), n = 1,369  1.14  1.09  1.21 
Base model + PaO_{2}/FiO_{2}, n = 1,369  1.12  1.06  1.18 
Base model + OI, n = 1,241  1.10  1.04  1.17 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 1,367  1.10  1.04  1.16 
Base model + PaO_{2}/FiO_{2} + PEEP, n = 1,241  1.10  1.04  1.17 
Base model + Vt, n = 1,283  1.16  1.10  1.23 
Discussion
Conclusions
Key messages

Vd/Vt has important prognostic significance in patients with ALI and ARDS, but is not routinely measured in clinical practice.

In mechanically ventilated patients with ALI and ARDS, Vd/Vt can be estimated from routinely available clinical data (arterial blood gas analysis and minute ventilation).

Elevated estimated Vd/Vt portends a poor prognosis in patients with ALI and ARDS.