Effect of recumbent position on lung volume and oxygenation during Acute
Respiratory Distress Syndrome.
J Dellamonica, N Lerolle, C Sargentini, S Hubert, G Beduneau, F Di Marco, A Mercat, JC M
Richard, JL Diehl, G Bernardin, L Brochard
Electronic supplemental Material
Additional Method:
Lung volume measurement suing the Multribreath nitrogen wash-in wash-out:
The technique has been described elsewhere [16, 20]. In summary, continuous
measurement of end-tidal O2 and CO2 during a 10% variation of FiO2 allows measurement of
nitrogen washout and washin and then the calculation of the aerated lung volume. Average
of both washout and washin data is performed automatically if the variation between the two
is less than 20% (as determined by manufacturer). FRC implies that it is measured without
PEEP (atmospheric pressure), and we thus used the term End Expiratory Lung Volume
(EELV) for this measurement. The mean of three EELV measured at each position was
considered [15]. EELV was expressed as normalized to the predicted body weight using the
formula for men: 50 + 0.91 × (height [cm] – 152.4), and for women: 45.5 + 0.91 × (height [cm]
– 152.4). Theoretical FRC seated and supine have been calculated using the Ibanez and
Raurich formula [21].
Additional discussion:
Hemodynamic
Mean arterial pressure increased during verticalization without heart rate modification (table
E1). All patients studied had an arterial line for blood pressure continuous monitoring and
arterial blood gas samples. Main hypothesis for these MAP variations is the miss-position of
the pressure captor without re-calibration in sitting position.
Table E1: Hemodynamic and pulmonary data during the four epochs studied.
Supine 1
Semi-recumbent
Seated
Supine 2
MAP (mmHg)
71 [66; 80]
80 [71; 88] *
84 [75; 93] *
75 [65; 81]
Heart rate (bpm)
94 [78; 105]
91 [80; 109]
90 [78; 109]
88[77; 100]
Strain
0.38 [0.27; 0.45]
0.33 [0.24; 0.39]* 0.31 [0.24; 0.40]* 0.33 [0.24; 0.46]
EELV/PBW (mL/kg) 16 [13; 22]
18 [15; 25] *
19 [15; 25] *
18 [13; 25]*
PaO2 (mmHg)
84 [78; 104]
97 [80; 110] *
102 [87; 110] *
90 [72; 114]
FiO2 (%)
60 [50; 80]
PaO2/FiO2
131 [116; 180]
159 [126; 199] *
160 [122; 210] *
143 [115; 194]
PaCO2 (mmHg)
39.0 [35.5; 47.0]
39.5 [35.0; 48.0]
40.0 [34.7; 48.2]
40.0 [35.5; 47.5]
SaO2 (%)
96.5 [96.0; 97.0]
97.0 [96.0; 98.0] * 98.0 [96.7; 98.0] * 97.0 [94.2; 98.0]
Cstat (mL/cmH2O)
36 [27; 45]
32 [25; 40] *
31 [24; 38] *
35 [29; 40]
* p<0.01 vs supine 1 was considered significant using Bonferoni correction if Friedman’s test
was p<0.05.
All patients had stable FiO2 during the study
Figure E1:
PaO2/FiO2 at the four epochs studied.
Panel A represents the whole population.
Panel B Blue boxes represent moderate & severe ARDS defined as PaO2/FiO2<200, red
boxes are milder patients.
Friedman’s non parametric test showed p<0.05 for All patients and Moderate and severe
ARDS allowing Wilcoxon paired test: * p<0.001 vs supine 1 (Bonferoni correction)
Panel A
Panel B