Clinical Trial: Ventilation During Cardiopulmonary Bypass (CPB) for Cardiac Surgery

Study Status: Suspended
Recruit Status: Suspended
Study Type: Observational

Official Title: Ventilation During Cardiopulmonary Bypass (CPB) for Cardiac Surgery - Effect on Pulmonary Atelectasis Post-operatively, a Pilot Study

Brief Summary:

During most types of heart surgery cardiopulmonary bypass (CPB) is used. CPB enables blood to be directed away from the heart and the lungs and pumped through the body while the heart is not beating. Surgery on the heart easier when it is not beating and bloodless area. Generally during CPB the lungs do not need to be ventilated, as no blood is flowing through the lungs and the body received oxygen from a machine (oxygenator) attached to the CPB pump.

In this study we are investigating the difference in lung collapse after heart surgery in patient who did have their lungs ventilated during CPB, compared to patients who did not have their lungs ventilated during CPB. We will use lung ultrasound scans to determine the degree of lung collapse at various time periods before and after the heart surgery. We will also investigate if ventilation during CPB will affect: a.) the rate of lung infection or pneumonia after the operation b.) the time it takes for a patient to have the breathing tube removed in the intensive care unit after the operation c.) the time for a patient to be discharged home from the hospital d.) the concentration of oxygen in the blood after the operation.


Detailed Summary:

Objective and Hypothesis:

To determine if continued mechanical ventilation (low tidal volume ventilation) during cardiopulmonary bypass (CPB) in adult patients undergoing elective cardiac surgery will reduce the degree of pulmonary atelectasis post-operatively, when compared to controls not ventilated during CPB.

The degree of pulmonary atelectasis will be assessed and quantified using non-invasive lung ultrasound (LUS) imaging.

We will conduct a preliminary observational study (pilot study) to assess the feasibility of this study. The pilot will be conducted on 40 patients, all of whom will be non-ventilated during CPB. The specific feasibility questions we would like to determine are: 1) the degree of atelectasis that can be demonstrated by LUS on patients that are not ventilated while on CPB, 2) the time needed to complete a LUS in the operating room (OR) and in the intensive care unit (ICU) and whether this will be efficient and possible given the busy operating room schedule, 3) to help determine the optimal time to scan patients to show the maximal degree of atelectasis, and 4) to help estimate the number of patients we will need to show a difference in atelectasis in the definitive study.

Primary hypothesis: low tidal volume ventilation during CPB for adult cardiac surgery reduces the amount of pulmonary atelectasis compared to controls not ventilated during CPB.

Background:

Respiratory dysfunction after cardiac surgery is relatively common, with an incidence anywhere from 2- 25% quoted in the literature. Pulmonary complications are a significant factor in morbidity and mortality of post-surgical patients, and therefore
Sponsor: McMaster University

Current Primary Outcome: Feasibility [ Time Frame: 3 months ]

To assess feasibility of LUS investigation in pre-operative and post-operative patients (time required to complete study in operating room and ICU, practicality of performing LUS in a busy environment). The LUS investigations are reported to be a fast and reliable investigation. However, few data are available about its use in a perioperative setting.


Original Primary Outcome: Same as current

Current Secondary Outcome:

  • Assess the evolution of LUS [ Time Frame: 3 months ]
    To assess the evolution of LUS during the perioperative period. Anesthesiology induction and mechanical ventilation are recognized to induce modifications in lung ventilation and aeration. Despite this, it is unclear that LUS will be able to detect these variations. Further, the optimal timing to evaluate the LUS is not known. The optimal time for LUS assessment measurement needs to take into consideration lung ventilation parameters and also practical realization in the operating room.
  • Determine sample size for future Randomized Control Trial [ Time Frame: 3 months ]
    To allow us to determine sample size for future randomized controlled trials. As a matter of fact, the distribution of this parameter (LUS) is not well described for perioperative patients. In order to evaluate the potential effect of lung ventilation during CPB, we first need to get an accurate estimation of LUS in the control (unventilated) population. This data will allow us to clearly define the hypothesis to test with regard to the expected treatment effect of lung ventilation during CPB.


Original Secondary Outcome: Same as current

Information By: McMaster University

Dates:
Date Received: February 21, 2014
Date Started: June 2014
Date Completion: August 2016
Last Updated: November 10, 2014
Last Verified: November 2014