Archived Comments for:
Respiratory and haemodynamic changes during decremental open lung positive end-expiratory pressure titration in patients with acute respiratory distress syndrome
Respiratory and hemodynamic during decremental open lung positive end-exspiratory pressure titration in patients with acute respiratory distress syndrome
GEORG AUZINGER, Liver Intensive Care Unit King's College Hospital London UK
7 May 2009
I read with interest Dr Gernoth's et co-workers study on respiratory and hemodynamic changes during recruitment manouvers and decremental open lung positive end-exspiratory pressure titration in ARDS. The authors have to be congratulated for this very well conducted trial, however I would like to make a few remarks regarding the echocardiographic measurements obtained. Firstly it appears as if endsystolic apical transgastric short axis views were printed in figure 5 rather than midpapillary views. This becomes especially evident when using the centimeter marks of the depth scale. The endsystolic anterior to posterior diameter on all 3 images appears to be in the range of 1.5-2cm unlike the values given in Table 4. IVC and SVC diameters were measured in the bicaval view. Given the difficulty of measuring the largest vessel diameter accuratly in a longitudinal view the preferred route of measuring SVC diameter should have been the midesophageal ascending aortic short axis view. The authors further state that venous return was maintained during recruitment and following open lung PEEP. This was based on the fact that vena cava diameters did not change significantly during intervention compared to baseline. Apart from technical concerns as mentioned previously, any change in venous return is probably better reflected by the fractional change of maximum and minimum SVC and IVC diameter during the respiratory cycle at the various time points. Taking the levels for the SVC diameter in Table 4 percentage change increased from 32 to 36, 38% respectively, which could be interpreted as increase in preload dependence due to decrease in venous return. An alternative explanation in the context of RV diameter increase would be increase in RV afterload leading to increased SVC and IVC diameter variation of course.
Critical Care
Respiratory and hemodynamic during decremental open lung positive end-exspiratory pressure titration in patients with acute respiratory distress syndrome
7 May 2009
I read with interest Dr Gernoth's et co-workers study on respiratory and hemodynamic changes during recruitment manouvers and decremental open lung positive end-exspiratory pressure titration in ARDS.
The authors have to be congratulated for this very well conducted trial, however I would like to make a few remarks regarding the echocardiographic measurements obtained.
Firstly it appears as if endsystolic apical transgastric short axis views were printed in figure 5 rather than midpapillary views. This becomes especially evident when using the centimeter marks of the depth scale. The endsystolic anterior to posterior diameter on all 3 images appears to be in the range of 1.5-2cm unlike the values given in Table 4.
IVC and SVC diameters were measured in the bicaval view. Given the difficulty of measuring the largest vessel diameter accuratly in a longitudinal view the preferred route of measuring SVC diameter should have been the midesophageal ascending aortic short axis view.
The authors further state that venous return was maintained during recruitment and following open lung PEEP. This was based on the fact that vena cava diameters did not change significantly during intervention compared to baseline. Apart from technical concerns as mentioned previously, any change in venous return is probably better reflected by the fractional change of maximum and minimum SVC and IVC diameter during the respiratory cycle at the various time points. Taking the levels for the SVC diameter in Table 4 percentage change increased from 32 to 36, 38% respectively, which could be interpreted as increase in preload dependence due to decrease in venous return. An alternative explanation in the context of RV diameter increase would be increase in RV afterload leading to increased SVC and IVC diameter variation of course.
Competing interests
I declare no competing interests.