It is well known that almost 50% of critically ill patients do not respond to fluid resuscitaiton. For those that do not respond, indiscriminate fluid administration may be harmful.
There is increasing emphasis on the use of dynamic markers of fluid responsiveness, namely passive leg raise (PLR), pulse pressure variation, respirophasic changes in the IVC, and many others.
ETCO2 can also be used to assess fluid responsiveness in mechanically ventilated patients with no spontaneous respiratory effort.
An increase in ETCO2 of at least 5% with a PLR has been shown to outperform arterial pulse pressure as a measure of fluid responsiveness.
