LETTER Long live dynamic parameters!

In a recent article about pulse pressure variation (PPV), after 4 pages of physiologic explanations, Dr Sondergaard finally concluded that ‘the subject is an exceptional dem-onstration of physiology but hardly guides the manage-ment of critically ill patients ’ [1]. If I agree with the first part of this statement (I and others spent years dissecting the complex physiology behind PPV), I strongly disagree with the second part of the sentence for three reasons, which are not opinions but facts. First, PPV and stroke volume variation (SVV) are increas-ingly used to guide fluid therapy both in the operating theater and in ICUs. This was confirmed by published peer-reviewed surveys, showing that the use of dynamic parame-ters increased from 1 % in 1998 [2] to 45 % in 2012 [3]. If dynamic parameters were not clinically useful one can doubt Second, PPV and SVV are today displayed on al-most all bedside and hemodynamic monitors, next to other vital signs such as the heart rate, blood pres-sure and arterial oxygen saturation. If medical device industry has financial interests in doing this, it is not fool enough to make research and development in-vestments on something caregivers do not value in their clinical practice. Third, at least 10 randomized controlled trials have demonstrated that hemodynamic strategies based on PPV or SVV monitoring allow a significant reduction in post-surgical complications and hospital length of stay (Table 1). So dynamic parameters are well alive and useful for improving patient outcome. Long live dynamic ili e p i