Myocardial Doppler velocities as a marker of prognosis in the ICU - Authors Reply
David John Sturgess, The University of Queensland
26 November 2007
Dear Editor,
We thank Drs Poelaert and Roosens for their commentary [1] regarding our recently published manuscript [2]. In response to this commentary, we must clarify a number of points:
First, we feel that the commentary may have overemphasized our findings with regard to outcome prediction. The primary aims of our study were to assess the distribution of values of tissue Doppler imaging (TDI) in critically ill patients and to examine the relationship between TDI and other echocardiographic indices of left ventricular preload. Our study incorporated a secondary aim of exploring associations between echocardiographic variables, particularly E/E’ (peak early diastolic transmitral velocity to peak early diastolic mitral annular velocity ratio), and mortality. This was undertaken with the intention of hypothesis generation and sample size calculation with a view to future prospective evaluation. Because of the potential limitations of analyzing retrospective data, we have been cautious not to overstate the observed relationship between left ventricular end systolic volume and mortality.
Second, the commentary notes the finding of only a weak relationship between pulmonary artery occlusion pressure and E/E’. However, we did not report such data. Comparisons between PAOP and E/E’ in critically ill patients have been published previously by other investigators [3, 4].
Third, as detailed in our manuscript, the lack of association between echocardiographic indices of preload might have been expected. However, there are no previously published data describing this. This important new finding contributes to our understanding of echocardiography in critical care.
Fourth, we agree that the influence of changes in ventricular loading upon E’ in critically ill patients remains incompletely defined. Comprehensive evaluation of diastolic function, and its impact upon ventricular filling, is challenging in critical care settings [5]. In this regard, we welcome data that contributes to our understanding of safe, non-invasive bedside techniques, such as TDI.
To restate our study’s findings: we observed a wide range of TDI values in a critically ill cohort. Diastolic dysfunction, as evidenced by TDI, was common. E/E’ did not strongly correlate with other static echocardiographic indices of preload. Further evaluation of echocardiographic variables, particularly increased LVESV, for risk stratification in the critically ill appears warranted.
Authors:
Dr David J Sturgess
Professor Bala Venkatesh
References
1. Poelaert J, Roosens C: Myocardial Doppler velocities as a marker of prognosis in the ICU. Crit Care 2007, 11:167.
2. Sturgess DJ, Marwick TH, Joyce CJ, Jones M, Venkatesh B: Tissue Doppler in critical illness: a retrospective cohort study. Crit Care 2007, 11:R97.
3. Bouhemad B, Nicolas-Robin A, Benois A, Lemaire S, Goarin JP, Rouby JJ: Echocardiographic Doppler assessment of pulmonary capillary wedge pressure in surgical patients with postoperative circulatory shock and acute lung injury. Anesthesiology 2003, 98:1091-1100.
4. Combes A, Arnoult F, Trouillet JL: Tissue Doppler imaging estimation of pulmonary artery occlusion pressure in ICU patients. Intensive Care Med 2004, 30:75-81.
5. Sturgess DJ, Marwick TH, Venkatesh B: Diastolic (Dys)Function in Sepsis. In: Yearbook of Intensive Care and Emergency Medicine. Edited by Vincent JL. Berlin Heidelberg: Springer-Verlag; 2007: 444-454.
Critical Care
Myocardial Doppler velocities as a marker of prognosis in the ICU - Authors Reply
26 November 2007
Dear Editor,
We thank Drs Poelaert and Roosens for their commentary [1] regarding our recently published manuscript [2]. In response to this commentary, we must clarify a number of points:
First, we feel that the commentary may have overemphasized our findings with regard to outcome prediction. The primary aims of our study were to assess the distribution of values of tissue Doppler imaging (TDI) in critically ill patients and to examine the relationship between TDI and other echocardiographic indices of left ventricular preload. Our study incorporated a secondary aim of exploring associations between echocardiographic variables, particularly E/E’ (peak early diastolic transmitral velocity to peak early diastolic mitral annular velocity ratio), and mortality. This was undertaken with the intention of hypothesis generation and sample size calculation with a view to future prospective evaluation. Because of the potential limitations of analyzing retrospective data, we have been cautious not to overstate the observed relationship between left ventricular end systolic volume and mortality.
Second, the commentary notes the finding of only a weak relationship between pulmonary artery occlusion pressure and E/E’. However, we did not report such data. Comparisons between PAOP and E/E’ in critically ill patients have been published previously by other investigators [3, 4].
Third, as detailed in our manuscript, the lack of association between echocardiographic indices of preload might have been expected. However, there are no previously published data describing this. This important new finding contributes to our understanding of echocardiography in critical care.
Fourth, we agree that the influence of changes in ventricular loading upon E’ in critically ill patients remains incompletely defined. Comprehensive evaluation of diastolic function, and its impact upon ventricular filling, is challenging in critical care settings [5]. In this regard, we welcome data that contributes to our understanding of safe, non-invasive bedside techniques, such as TDI.
To restate our study’s findings: we observed a wide range of TDI values in a critically ill cohort. Diastolic dysfunction, as evidenced by TDI, was common. E/E’ did not strongly correlate with other static echocardiographic indices of preload. Further evaluation of echocardiographic variables, particularly increased LVESV, for risk stratification in the critically ill appears warranted.
Authors:
Dr David J Sturgess
Professor Bala Venkatesh
References
1. Poelaert J, Roosens C: Myocardial Doppler velocities as a marker of prognosis in the ICU. Crit Care 2007, 11:167.
2. Sturgess DJ, Marwick TH, Joyce CJ, Jones M, Venkatesh B: Tissue Doppler in critical illness: a retrospective cohort study. Crit Care 2007, 11:R97.
3. Bouhemad B, Nicolas-Robin A, Benois A, Lemaire S, Goarin JP, Rouby JJ: Echocardiographic Doppler assessment of pulmonary capillary wedge pressure in surgical patients with postoperative circulatory shock and acute lung injury. Anesthesiology 2003, 98:1091-1100.
4. Combes A, Arnoult F, Trouillet JL: Tissue Doppler imaging estimation of pulmonary artery occlusion pressure in ICU patients. Intensive Care Med 2004, 30:75-81.
5. Sturgess DJ, Marwick TH, Venkatesh B: Diastolic (Dys)Function in Sepsis. In: Yearbook of Intensive Care and Emergency Medicine. Edited by Vincent JL. Berlin Heidelberg: Springer-Verlag; 2007: 444-454.
Competing interests
The authors have no competing interests.