Effect of Transpulmonary Pressure Guided Ventilation on Intraoperative Right Heart Function

Summary

The purpose of this clinical trial is to determine whether different types of ventilator settings during surgery change the relationship between the pressures in the lungs and the function of the heart.

In this study, patients will be randomly assigned (like flipping a coin) to receive either standard or individualized (research) lung protective ventilator settings.

Before surgery, patients will be given an 8-item verbal questionnaire about any respiratory symptoms. After patients are asleep for surgery, an ultrasound probe will be inserted into the esophagus (food pipe) and stomach to examine the heart and lungs and take ultrasound pictures. The ultrasound probe is then removed. Next, a small balloon catheter (a narrow tube smaller in diameter than a pencil lead) will be placed in the esophagus, where it will be used to measure the pressures in the chest and lungs.

For patients who are assigned to standard ventilator settings, the ventilator settings and pressures during surgery will be recorded.

For patients assigned to individualized (research) ventilator settings, the pressures from the balloon catheter will be used to adjust the ventilator settings every 30 minutes during surgery.

A second ultrasound pictures of the heart and lungs will be obtained at the point at which the patient is placed into the Trendelenburg position. At the end of surgery and before the patient is awake, the balloon catheter will be removed, the ultrasound probe will be inserted, a third set of ultrasound pictures of the heart and lungs will be obtained, and the ultrasound probe then removed.

Patients will be telephoned 30 days after surgery to ask about their recovery. The 8-item respiratory symptom questionnaire will be repeated at this time.

Conditions

• Obesity
• Surgery
• Anesthesia
• Echocardiography, Transesophageal
• Mechanical Ventilation

Interventions

OTHER

Individualized lung-protective ventilation

Lung-protective ventilator settings will be individualized based on the patient's transpulmonary pressures (TPP), as measured by esophageal manometry. The ventilator will be set to volume-controlled ventilation with a tidal volume of 6 mL/kg of ideal body weight, inspired oxygen fraction of 30%, inspiratory pause of 30%, inspiration-to-expiration ratio of 1:2, PEEP of 5 cm H2O, and flow of 3 L/min). The respiratory rate will be set to 12 breaths/min in the beginning then adjusted (within 10-20 breaths/ min) to maintain EtCO2 between 35 to 45 mm Hg. The set PEEP will be then increased by 2 cm H2O every 2 minutes (up to a max of 30 cm H2O) to identify and maintain the lowest driving pressure, maximum compliance, and positive TPP. These steps will be performed every 30 minutes after intubation, and after instillation of the pneumoperitoneum, and after steep Trendelenburg positioning. These individualized PEEP settings will be maintained until the pneumoperitoneum is released.

OTHER

Standard lung-protective ventilation

Ventilator settings will be adjusted to standard lung-protective settings according to the anesthesiologist's clinical judgement for the patient, their comorbodities, and the surgical procedure.

Sponsors & Collaborators

• University of Vermont Medical Center

  lead OTHER

Principal Investigators

• William G Tharp, MD PhD · University of Vermont Medical Center

Study Design

Allocation

RANDOMIZED

Purpose

DIAGNOSTIC

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2023-01-30

Primary Completion

2025-10-15

Completion

2026-03-15

Countries

• United States

Study Locations