Evaluation of pulse pressure variation validity criteria in critically ill patients: a prospective observational multicentre point-prevalence study

Background. Respiratory variation in pulse pressure (DPP) is commonly used to predict the fluid responsiveness of critically ill patients. However, some researchers have demonstrated that this measurement has several limitations. The present study was designed to evaluate the proportion of patients satisfying criteria for valid application of Delta PP at a given time-point. Methods. A 1 day, prospective, observational, point-prevalence study was performed in 26 French intensive care units (ICUs). All patients hospitalized in the ICUs on the day of the study were included. The Delta PP validity criteria were recorded prospectively and defined as follows: (i) mechanical ventilation in the absence of spontaneous respiration; (ii) regular cardiac rhythm; (iii) tidal volume >= 8ml kg(-1) of ideal body weight; (iv) a heart rate/respiratory rate ratio >3.6; (v) total respiratory system compliance >= 30 ml cm H2O-1; and (vi) tricuspid annular peak systolic velocity >= 0.15 ms(-1). Results. The study included 311 patients with a Simplified Acute Physiology Score II of 41 (3943). Overall, onlysix (2%) patients satisfied all validity criteria. Of the 170 patients with anarterial line in place, only five (3%) satisfied the validity criteria. During the 24h preceding the study time-point, fluid responsiveness was assessed for 79 patients. Delta PP had been used to assess fluid responsiveness in 15 of these cases (19%). Conclusions. A very low percentage of patients satisfied all criteria for valid use of Delta PP in the evaluation of fluid responsiveness. Physicians must consider limitations to the validity of Delta PP before using this variable.