Serial invasive hemodynamics and clinical characteristics of patients with shock with and without invasive mechanical ventilation
Authors: Padilla Lopez M , Sionis A , Schimmer H , Numemacher K , Howe W , Fraser K , Bianco L , Cheever S , Loon-Wan K , Baneras J , Keller N , Katz J , Bangalore S , Tavazzi G , Alviar C L 
Published: May 2024

Abstract

Funding Acknowledgements
None.

Background
Invasive mechanical ventilation (IMV) is commonly used in the Cardiac Intensive Care Unit (CICU) in patients with cardiogenic shock (CS). IMV causes hemodynamic changes that may impact outcomes based upon a patient’s profile. Our aim is to characterize the clinical profile and detailed serial hemodynamic parameters in the first 24-hours according to the use of IMV in patients with shock admitted to the CICU.

Methods
Retrospective analysis of consecutive patients with shock admitted to the CICU at Bellevue Hospital, undergoing pulmonary artery catheter (PAC) placement within the first 24 hours of admission, from February 2022 to June 2023. Clinical characteristics, as well as specific hemodynamic parameters collected and curated at times 0, 6, 12, 18 and 24 hours were from PAC placement compared between patients with and without IMV.

Results
A total of 101 patients were included (95% with cardiogenic shock), 59 receiving IMV (age 64 ± 15, 24% women) and 42 non-intubated (61 ± 13, 33% women). Non-intubated patients had higher prevalence of hypertension, prior coronary artery disease and heart failure with reduced ejection fraction (HFrEF), while acute coronary syndromes (44%) and cardiac arrest (12%) were more common causes of admission in patients undergoing IMV. Mixed shock predominated in IMV patients (51 vs 17%, p &lt;0.001), whereas cardiogenic shock (CS) was more common in non-intubated patients (83 vs 41%, p &lt;0.01). Patients with acute myocardial infarction CS (AMI-CS) were more likely to undergo IMV, while patients with heart failure CS (HF-CS) were more likely to be non-intubated. Patients undergoing IMV were more likely to have mechanical circulatory support (MCS) and ventricular dilatation compared to non-intubated patients (LVEDD 5.7 cm vs 4.9 cm, p 0.002). Patients undergoing IMV had a higher incidence of severe shock compared to the non-intubated group (31% vs 19% SCAI Shock D), higher lactate levels and greater use of vasoactive drugs (figure 1A). Patients undergoing IMV had significant improvements in cardiac power output (CPO), diastolic blood pressure and systemic vascular resistance (SVR) (figure 1B). Shock severity by SCAI SHOCK classification had a more notable improvement at 24 hours in patients with IMV compared to non-intubated patients (figure 1C), with a non-statistically significant improvement in lactate clearance in the first 24 hours (Figure 1D).

Conclusions
IMV in patients with CS is more commonly seen in patients with AMI-CS and among those with higher baseline shock severity and greater use of vasoactive medications. IMV is associated with significant improvements in shock severity, CPO and SVR at 24 hours when compared to patients with shock who are not intubated, which could be related to higher use of vasopressors. Further investigations are warranted to understand the impact of IMV on outcomes of patients with CS and how they might vary according to hemodynamic profile.