In critically ill septic shock patients, assessments of hemodynamic function, fluid status and improvement of clinical status are challenging. As a consequence of critical illness and large volume administration of crystalloids as recommended by Early Goal-Directed Therapy, comes the potential of acute (respiratory distress/failure) and long-term sequelae (ARDS, prolonged endotracheal intubation, anasarca, bedsores, poor IV access, increased resource utilization).
The FALLS-protocol, developed by Daniel Lichtenstein introduces novel clinical parameters useful in the assessment of fluid status dynamically. It aims to define the critical point when fluid administration is becoming deleterious to the patient (lung saturation), and we must start considering the use of vasopressors as well as the potential for respiratory failure.
Review: Lung Ultrasound basics
Utilizing a decision tree that obligates several simple cognitive and sonographic steps in the evaluation of shock, the true protocol begins when septic shock remains the most likely etiology and resuscitation has already been initiated. By evaluating the lung parenchyma at the Blue Points, we begin with the A-profile in healthy patients. Patients with fluid overload however demonstrate a B-profile (lung rockets emanating from the pleural line) indicative of interstitial edema. In combination with vital signs, as we are administering fluids, we can evaluate the profile in either intervals of time or fluid aliquots. At any of these intervals, if the patient remains hypotensive but has an A profile, we can feel confident that we can continue to administer fluids with little risk for respiratory compromise. However, if the profile transitions to B-profile, we must consider vasopressors and advanced airway management.
Fluid administration is often guided by clinical judgment, with no clearly defined end point other than a normalized blood pressure. However, blood pressures can be corrected by vasopressors and are often given as a last ditch effort. With the current emphasis on sepsis management in the US, EDs are coming under scrutiny for our role. Although the FALLS-protocol still requires exhaustive study, it has the potential to allow a more finessed management of acute circulatory failure.
Lichtenstein, D. (2010) Wholebody Ultrasonography in the Critically Ill. London: Springer-Verlag Berlin Heidelberg
Fluid Administration limited by lung sonography: the place of lung ultrasound in assessment of acute circulatory failure (The FALLS-protocol). Expert Rev Respir Med. 2012 Apr;6(2):155-62.