Prevalence and characterization of normotensive shock in intermediate-high risk acute pulmonary embolism patients
I Santos, S Leal, J C Pereira, F Albuquerque, A F Oliveira, J Brito, C Brizido, M S Almeida, P AdragaoAbstract
Background
Acute pulmonary embolism (PE) can be life-threatening, especially when in cardiogenic shock. While hemodynamic compromise imposes emergent pharmacologic or mechanical reperfusion in high-risk cases, patient selection for advanced therapies in intermediate-high risk PE presents greater challenges, as a subset of patients is known to present normotensive shock (NTS): a critical but underrecognized state of hemodynamic instability and systemic hypoperfusion, despite normal blood pressure. Early identification of NTS is essential, as timely recognition can influence management and significantly enhance clinical outcomes.
Purpose
To assess prevalence and characterize NTS in intermediate-high risk PE patients submitted to catheter-based therapies (CBT).
Methods
A retrospective, cross-sectional cohort study was conducted at a single tertiary center, including intermediate-high risk PE patients treated with CBT between 2020 and 2024, who had arterial and mixed venous blood gas samples pre-procedure. Data on demographics, clinical features, laboratory results, and invasive/noninvasive hemodynamics were analyzed using Chi-square, Mann-Whitney and T-tests. Patients were classified into NTS [CI < 2.2 L/min/m²] and non-shock groups based on pre-CBT invasive CI, with CO estimated using the indirect Fick method. The composite shock score from the FLASH registry was tested.
Results
Thirteen patients (23,1% male; mean age 61,8 years) were included, with 52,8% (n=7) classifying as in NTS. Baseline characteristics showed no significant differences, though the NTS group tended to have lower BMI and BSA. NTS patients required higher FiO2 (p=0.020) and showed trends toward lower SpO2 and P/F ratios. Other variables, including admission hemodynamics, lactate, creatinine, cardiac biomarkers, PESI score, and PE presentation (e.g. DVT or saddle PE), were similar between groups. Invasive hemodynamics pre-CBT revealed NTS patients had lower CO, CI, and SV (p<0.001), and higher total pulmonary vascular resistance (TPVR) (p=0.008). Pulmonary artery pressures were similar. NTS patients presented also higher shock index (p=0.049 and hemoglobin (p=0.005), and trends toward higher HR and lower SBP and SvO2. The FLASH composite shock score failed to identify NTS within this cohort. CBT technique and device selection were similar between groups.
Conclusion
In this cohort, NTS was found in about half of intermediate-high risk PE patients, superior to the prevalence described in literature. Formerly described predictors and composite scores failed to identify NTS reliably. Key hemodynamic differences, including elevated shock index, TPVR, and reduced CO and CI, highlight the importance of invasive hemodynamic monitoring for early detection of NTS. Future studies should focus on validating more sensitive tools and biomarkers to facilitate timely recognition and intervention in NTS.