Clinical Trial: Evaluation of the Risk of Hyperoxia-induced Hypercapnia in Obese Cardiac Surgery Patients

Study Status: Not yet recruiting
Recruit Status: Not yet recruiting
Study Type: Interventional

Official Title: Evaluation of the Risk of Hyperoxia-induced Hypercapnia in Obese Patients in a Cardiac Surgery Postoperative Setting

Brief Summary: This study aims to evaluate the risk of hyperoxia-induced hypercapnia in post-op obese cardiac surgery patients. It will compare two oxygenation modes in terms of their effect on the arterial partial pressure of carbon dioxide (PaCO2) : manual titration of oxygen delivery for a peripheral oxygen saturation (SpO2) target of > 95 % versus automatic titration by a closed-loop system for a SpO2 target of 90%. 15 post-op obese cardiac surgery patients will be recruited and each will receive both interventions (cross-over design). The main outcome will be the PaCO2, which will be compared after each study period. The research hypothesis is that the usual SpO2 target of > 95 % is associated with a greater PaCO2 compared with a lesser SpO2 target of 90%.

Detailed Summary:

This study aims to evaluate the risk of hyperoxia-induced hypercapnia in post-op obese cardiac surgery patients.

The investigators will compare two oxygenation modes in terms of their effect on PaCO2 : a SpO2 target of > 95 % achieved with manual titration (usual practice) and a more conservative SpO2 target of 90 % achieved with automatic titration by a closed-loop system (FreeO2).

The choice of a SpO2 target of 90 % is consistent with recent guidelines issued by the British Thoracic Society and the Thoracic Society of Australia and New Zealand, which both recommend a SpO2 target of 88-92 % for morbidly obese patients (BMI > 40 kg/m2).

FreeO2 is a closed-loop oxygen delivery system which adjusts the oxygen flow according to the patient's real-time SpO2 and a target programed by the physician. The system also records data on heart rate, respiratory rate and SpO2. Its safety and efficacy have been tested in healthy subjects as well as in patients suffering from COPD or acute respiratory distress in the emergency room, with promising results.

The research hypothesis is that the usual SpO2 target of > 95 % is associated with a greater PaCO2 compared with a lesser SpO2 target of 90%.

15 obese patients will be recruited at the Institut universitaire de cardiologie et de pneumologie de Québec. A written consent from the patient will be obtained the day before the surgery. The protocol has been submitted to and approved by the establishment's ethics committee.

The study will compare the effect of two different oxygenation modes on the patients' PaCO2 immediately after extubation :

Same as current

Current Secondary Outcome:

  • Change in pH [ Time Frame: At 30 minutes (first intervention) and at 1h (second intervention) ]
  • Change in PaO2 [ Time Frame: At 30 minutes (first intervention) and at 1h (second intervention) ]
  • Change in percentage of time spent in hypoxemia (SpO2 < 88%) [ Time Frame: After the first 30 minutes (first intervention) and between 30 min and 1h (second intervention) ]
  • Change in percentage of time spent in severe hypoxemia (SpO2 < 85 %) [ Time Frame: After the first 30 minutes (first intervention) and between 30 min and 1h (second intervention) ]
  • Change in percentage of time spent in hyperoxemia (SpO2 > 96 %) [ Time Frame: After the first 30 minutes (first intervention) and between 30 min and 1h (second intervention) ]
  • Change in respiratory rate (manual, monitor, FreeO2) [ Time Frame: At 0, 10, 20, 30, 40, 50 and 60 minutes ]
  • Change in heart rate [ Time Frame: At 0, 10, 20, 30, 40, 50 and 60 minutes ]
  • Change in arterial blood pressure [ Time Frame: At 0, 10, 20, 30, 40, 50 and 60 minutes ]
  • Change in pulmonary artery pressure [ Time Frame: At 0, 10, 20, 30, 40, 50 and 60 minutes ]
  • Change in amine level [ Time Frame: At 0, 10, 20, 30, 40, 50 and 60 minutes ]
  • Change in body temperature [ Time Frame: At 0, 30, 60 minutes ]


Original Secondary Outcome: Same as current

Information By: Laval University

Dates:
Date Received: September 25, 2016
Date Started: September 2016
Date Completion: September 2017
Last Updated: September 26, 2016
Last Verified: September 2016