Reverse-FALLS Protocol Reduces Pulmonary Congestion in CPE Patients

Cardiogenic pulmonary edema (CPE) is a serious condition associated with impaired gas exchange and acute respiratory failure, carrying high mortality. Diuretics are considered the cornerstone of CPE treatment, with furosemide doses requiring individualization based on patient status and response. Lung ultrasonography has emerged as a reliable bedside tool for diagnosing and monitoring pulmonary congestion. By assessing extravascular lung water and inferior vena cava (IVC) size, clinicians can obtain objective data to guide diuretic therapy for safe and effective treatment of pulmonary edema. However, data on structured ultrasound protocols, such as the Reverse-FALLS protocol, for guiding and monitoring diuretic therapy in the emergency department are limited.^1,2,3

CPE typically arises from acute decompensated heart failure, where increased hydrostatic pressure in the pulmonary capillaries leads to fluid extravasation into the interstitial and alveolar spaces. This fluid accumulation impairs oxygen diffusion and reduces lung compliance, resulting in dyspnea, hypoxemia, and increased work of breathing. Early and effective management is crucial to prevent progression to severe respiratory distress and multi-organ dysfunction. While diuretics are fundamental, their optimal dosing and timing remain a challenge, often relying on subjective clinical assessments. Over-diuresis can lead to acute kidney injury and electrolyte imbalances, while under-diuresis can prolong hospital stays and worsen outcomes. Therefore, objective, real-time monitoring tools are essential to optimize diuretic therapy and improve patient safety and efficacy.

The Reverse-FALLS Protocol Study

A prospective, single-center observational study was conducted between April 1 and June 30, 2023, in an emergency department to evaluate the Reverse-FALLS protocol.¹ Adult patients diagnosed with acute CPE were included. Bedside lung ultrasonography and IVC measurements were performed using the Reverse-FALLS protocol both before and after intravenous loop diuretic therapy. The study recorded the number of B-lines in four lung regions and changes in IVC diameter. The primary outcome was the change in B-line counts following diuretic treatment. Secondary outcomes included IVC diameter changes and clinical outcomes.¹

The study specifically included patients presenting with acute symptoms consistent with CPE, such as acute dyspnea, orthopnea, and radiographic evidence of pulmonary congestion, in conjunction with elevated cardiac biomarkers. Exclusion criteria typically involved conditions that could confound ultrasound findings, such as severe chronic lung disease, pneumothorax, or significant pleural effusions unrelated to CPE. The Reverse-FALLS protocol involved a standardized approach to lung ultrasound, systematically scanning four predefined lung regions: right upper, right lower, left upper, and left lower. B-lines, which are vertical hyperechoic artifacts extending from the pleural line to the edge of the screen, indicate interstitial and alveolar fluid. The number of B-lines was semi-quantitatively assessed in each region. IVC diameter was measured in both inspiration and expiration to assess volume status and fluid responsiveness. Intravenous loop diuretics, primarily furosemide, were administered according to standard emergency department protocols, with doses individualized based on patient weight, renal function, and prior diuretic use. The interval between ultrasound assessments was chosen to allow sufficient time for diuretic action and observable changes in pulmonary congestion.

A total of 40 patients were included in the study, with a mean age of 73.7 ± 12.7 years; 65% of the participants were female. Following diuretic therapy, 82.5% of patients demonstrated a significant reduction in B-lines on lung ultrasonography. B-line counts decreased significantly in all lung regions: right upper (P=.005), right lower (P=.013), left upper (P<.001), and left lower (P<.001). The mean interval between ultrasound assessments was 6.2 ± 3.4 hours. Changes in IVC diameter were not statistically significant (P=.061). Higher brain natriuretic peptide levels were significantly associated with worse clinical outcomes (P=.021).¹

The study concluded that bedside lung ultrasonography using the Reverse-FALLS protocol effectively demonstrated a reduction in pulmonary congestion following diuretic therapy in patients with CPE. Monitoring B-line changes may allow individualized diuretic management without significant intravascular volume depletion, thereby supporting the clinical utility of ultrasound-guided treatment in the emergency department.¹

Despite the positive findings, the study had several limitations. Its single-center, observational design limits the generalizability of the results. The relatively small sample size of 40 patients may not fully capture the heterogeneity of the CPE patient population. The study did not include a control group receiving standard care without ultrasound guidance, making it difficult to definitively attribute improved outcomes solely to the Reverse-FALLS protocol. Furthermore, the assessment of B-lines, while standardized, still carries a degree of operator dependency, and inter-observer variability was not explicitly reported. The lack of significant change in IVC diameter, despite a reduction in B-lines, suggests that IVC measurements alone may not be sufficient to guide diuretic therapy in all CPE patients, or that the timing of IVC measurements relative to diuretic administration may need further optimization. Future multicenter, randomized controlled trials with larger cohorts are necessary to validate these findings and establish the Reverse-FALLS protocol as a standard of care for guiding diuretic therapy in CPE.