Cardiac Surgery Subjects
Conditions
Keywords
PEEP Titration, Mechanical Ventilation, Coronary Artery Disease, Right Ventricular Impairment
Brief summary
The purpose of this single-center, prospective study is to evaluate the physiologic effect of changes in PEEP on biventricular mechanics and RV-pulmonary arterial (RV-PA) coupling in adult patients undergoing cardiac surgery.
Detailed description
Positive end-expiratory pressure (PEEP) is a critical modality of mechanical ventilation but has important and often underappreciated effects on biventricular mechanics. PEEP is frequently selected based primarily on respiratory mechanics and oxygenation targets; however, increasing intrathoracic pressure may reduce RV preload by elevating right atrial pressure, while increasing transpulmonary pressure may increase RV afterload by compressing intra-alveolar pulmonary vessels and redistributing pulmonary blood flow. This is important specifically in the context of cardiac surgery where right ventricular (RV) function plays a critical role in determining postoperative morbidity and mortality. Perioperative RV dysfunction has been consistently associated with adverse outcomes, including prolonged vasopressor and inotrope requirements, difficulty weaning from cardiopulmonary bypass, longer intensive care unit stays, and increased mortality. Right ventricular-pulmonary arterial (RV-PA) coupling provides a physiologically integrated assessment of RV performance by quantifying the relationship between RV contractility and afterload. Animal studies have shown that incremental PEEP increases can impair biventricular mechanics and precipitate RV-PA uncoupling. However, these physiologic effects have not been systematically characterized in the perioperative setting in the cardiac surgery population. This protocol seeks to address this knowledge gap by systematically evaluating biventricular mechanics and RV-PA coupling across varying PEEP levels in a controlled setting, using tools already employed in routine cardiac surgical care (pulmonary artery catheter and intraoperative TEE). The overarching goal of this proposal is to define how perioperative positive end-expiratory pressure alters biventricular mechanics and right ventricular-pulmonary arterial coupling, to inform physiologically guided, RV-protective ventilatory strategies during cardiac surgery.
Interventions
PROCEDUREEIT Guided PEEP Trial
Electrical impedance tomography (EIT) will be used to guide identification of "optimal PEEP" based on lung mechanics. After induction of anesthesia and initiation of controlled mechanical ventilation, EIT data will be collected during a brief standardized PEEP titration maneuver to assess lung recruitment and overdistension.
Sponsors
Beth Israel Deaconess Medical Center
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* 1\. Age ≥ 18 years * 2\. Scheduled to undergo cardiac surgery requiring general anesthesia * 3\. Planned use of intraoperative transesophageal echocardiography (TEE) as part of routine clinical care * 4\. Planned placement of a pulmonary artery catheter as part of clinical care (Pulmonary artery catheter placement will be performed solely based on clinical judgment by the treating anesthesia and surgical teams. At our institution, pulmonary artery catheters are routinely placed in cardiac surgery patients with clinical indications including: * preoperative pulmonary hypertension (e.g., estimated PCWP \>20 mmHg or elevated filling pressures on preoperative echocardiography), * right ventricular dysfunction or suspected RV failure (preoperative visual TTE assessment), * significant cardiopulmonary comorbidity, * or anticipated complex, prolonged, or high-acuity cardiac surgery. The research team will not influence decisions regarding catheter placement. Only patients already scheduled to receive a clinically indicated pulmonary artery catheter will be eligible for enrollment.) * 5\. Able and willing to provide written informed consent prior to surgery
Exclusion criteria
* 1\. Significant arrhythmia (e.g., atrial fibrillation with uncontrolled ventricular response or other rhythm disturbances) that would interfere with reliable pressure waveform or echocardiographic measurements. * 2\. Severe valvular disease where protocol-related PEEP changes may pose unacceptable hemodynamic risk, as determined by the clinical team. * 3\. Significant chronic lung disease or other pulmonary pathology where PEEP adjustments may be unsafe (e.g., severe COPD with dynamic hyperinflation, bullous lung disease), at the discretion of the anesthesia team. * 4\. Contraindication to changes in PEEP, including inability to tolerate the planned PEEP titration due to hemodynamic instability or clinician concern. * 5\. Any contraindication to TEE (if clinically required TEE is not performed or is contraindicated, the subject will not be eligible) * 6\. Investigator or clinical team discretion (e.g., safety concerns, inability to obtain reliable measurements, or conflict with other perioperative research protocols)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Right ventricle-pulmonary artery coupling (Ees/Ea) | During the standardized PEEP titration sequence after induction of anesthesia and before surgical intervention (approximately 20-25 minutes) | Right ventricle-pulmonary artery (RV-PA) coupling ratio (Ees/Ea) assessed using simultaneous transesophageal echocardiography and hemodynamic monitoring at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]) during a standardized stepwise PEEP titration sequence. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Right ventricular end-diastolic volume at predefined PEEP levels | During PEEP titration sequence (approximately 20-25 minutes after induction of anesthesia and prior to surgical incision) | Three-dimensional right ventricular end-diastolic volume (RVEDV) measured by transesophageal echocardiography at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Right ventricular end-systolic volume at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Three-dimensional right ventricular end-systolic volume (RVESV) assessed by three-dimensional transesophageal echocardiography at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Right ventricular stroke volume at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Right ventricular stroke volume derived from three-dimensional transesophageal echocardiography at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Right ventricular end-diastolic pressure at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Right ventricular end-diastolic pressure measured via pulmonary artery catheter at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Right ventricular end-systolic pressure at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Right ventricular end-systolic pressure estimated using waveform-based calculation methods from pulmonary artery catheter data at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Pulmonary artery systolic pressure at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Pulmonary artery systolic pressure measured via pulmonary artery catheter at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Mean pulmonary artery pressure at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Mean pulmonary artery pressure measured via pulmonary artery catheter at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Right ventricular end-systolic elastance at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Right ventricular end-systolic elastance (Ees) derived using single-beat pressure-volume analysis at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Effective arterial elastance at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Effective arterial elastance (Ea) derived from pressure-volume analysis at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Three-dimensional right ventricular ejection fraction | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Three-dimensional right ventricular ejection fraction (3D RVEF) assessed by transesophageal echocardiography at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]) during a standardized stepwise PEEP titration sequence. |
| Left ventricular ejection fraction at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Three-dimensional left ventricular ejection fraction (LVEF) assessed by transesophageal echocardiography at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
| Left ventricular stroke volume at predefined PEEP levels | During standardized PEEP titration sequence after induction of anesthesia and prior to surgical incision (approximately 20-25 minutes) | Left ventricular stroke volume derived from echocardiographic measurements at four predefined PEEP levels (optimal PEEP + 5 cmH₂O, optimal PEEP, optimal PEEP - 5 cmH₂O, and PEEP 0 cmH₂O \[baseline\]). |
Countries
United States
Outcome results
None listed