Bedside assessment of right atrial pressure in critically ill septic patients using tissue Doppler ultrasonography.

PURPOSE: Right atrial pressure (RAP) is considered a surrogate for right ventricular filling pressure or cardiac preload. It is an important parameter for fluid management in patients with septic shock. It is commonly approximated by the central venous pressure (CVP) either invasively using a catheter placed in the superior vena cava or by bedside ultrasound, in which the size and respiratory variations of the inferior vena cava (IVC) are measured from the subcostal view. Doppler imaging of the tricuspid valve from the apical 4-chamber view has been proposed as an alternative approach for the estimation of RAP. The tricuspid E/Ea ratio is measured, where E is the peak velocity of the early diastolic tricuspid inflow and Ea is the peak velocity of the early diastolic relaxation of the lateral tricuspid annulus. We hypothesized that the tricuspid E/Ea ratio may represent an alternative to IVC metrics, using invasive CVP as the criterion standard, for the assessment of RAP in critically ill septic patients.

MATERIALS AND METHODS: A convenience sample of 30 septic patients, both mechanically ventilated and non-mechanically ventilated, was enrolled. Using a portable ultrasound system, maximum velocity of tricuspid E and Ea was measured from the apical 4-chamber view; and IVC diameter and degree of collapse were measured from the subcostal view. Decision tree induction was used to determine the performance of each model compared with invasive CVP.

RESULTS: Our results suggest that a tricuspid E/Ea ratio of greater than 4.7 can predict a CVP greater than 10 mm Hg in septic patients with sensitivity greater than 85% and specificity greater than 90%.

CONCLUSIONS: In this pilot study, Doppler imaging of the tricuspid valve provided a valuable alternative for noninvasive bedside estimation of RAP in septic patients.