Clinical Trial: EPO2-A: Evaluation of Pre-Oxygenation in Morbid Obesity: Effect of Position and Positive Pressure Ventilation

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: EPO2-A: Evaluation of Different Pre-Oxygenation Condition in Morbid Obesity: Effect of Position and Positive Pressure Ventilation During General Anesthesia Induction

Brief Summary: The risk of complication associated with airway in obese patient is important. The result of pre-oxygenation gives the clinician a prolonged non-hypoxic apnea time. The relation between FRC and non-hypoxic apnea time has been correlated. However, the best condition to accomplish the pre-oxygenation in morbidly obese patient has yet to be described in the medical literature. A study previously done in our hospital (EPO2-PV) compared the effect of different positions and ventilation modes on the FRC in the laboratory. A significant difference has been established on the FRC between the inverse Trendelenburg position with positive pressure ventilation and the head up ("beach-chair") position without positive pressure. The current study, EPO2-A is designed to compared the two positions and ventilation modes during the induction of general anesthesia on morbidly obese and correlate the difference in FRC to difference in apnea time.

Detailed Summary:

Obesity prevalence in the population is increasing. Thus a growing number of obese patient need surgical interventions. These patients have a four time higher risk of suffering of serious complication in relation with their airway management compare with non-obese patients. This is explained by an increased incidence of difficulty with the ventilation and intubation of the obese. The time available for the clinician to manage the airway is define by the non hypoxic apnea time. This laps of time is dependent of the oxygen stocks of the patient, which are dependent of the functional residual capacity (FRC) and his oxygen consumption. For a non-obese patient, a normal pre-oxygenation of three minutes at 100% of oxygen allows a non hypoxic apnea time (oxygen saturation > 90%) of 8,9 minutes. However, for the morbidly obese, this time is cut to less than three minutes.

The major goal of the pre-oxygenation is to increase the alveolar partial pressure of oxygen available in the end-expiratory pulmonary volume. This can be done by replacing the nitrogen in the alveolus by oxygen and by increasing the pulmonary stocks, the FRC. It has been demonstrated that the FRC after the induction of anesthesia is cut by half for the obese. This reduction is explained by a diminished thoracic compliance and an increase of the dependent lung regions' atelectasis because of a more cephalic position of the diaphragm.

Various pre-oxygenation methods have been described to prolong the non hypoxic apnea time in the obese population. Some proposed pre-oxygenation strategies with the patient in the head up position (beach chair). It is a position derived from the ramped position described as the best to visualized the obese patients' glottis. Others proposed pre-oxygenation strategies with positive pressure ventilation, but only the supine position
Sponsor: Laval University

Current Primary Outcome: Non hypoxic apnea time [ Time Frame: After a 3 minutes pre-oxygenation period ]

Change of Non-hypoxic apnea time in obese patient during a General Anesthesia induction, as a result of different pre-oxygenation position and ventilation mode; 1-Beach Chair and No positive pressure ventilation, 2-Reverse Trendelenburg and positive pressure ventilation and PEEP


Original Primary Outcome: Same as current

Current Secondary Outcome:

  • Time to expired oxygen fraction > 0,9 [ Time Frame: During the pre-oxygenation period ]
    Evaluation of time needed to obtain an expired fraction of oxygen of > 0,9 in the two groups during the pre-oxygenation
  • Maximum expired fraction of oxygen obtained [ Time Frame: After 3 minutes of pre-oxygenation ]
    Evaluation of the maximum expired oxygen fraction obtained in the two groups
  • Minimum arterial saturation of oxygen obtained [ Time Frame: After the end of the Non-hypoxic apnea time ]
    Evaluation
  • Time to 97% saturation [ Time Frame: Evaluation of the time needed to the beginning of the ventilation to the moment where the saturation is 97% ]
  • Hemodynamic changes [ Time Frame: From the beginning of the pre-oxygenation to the end of the protocol ]
    Evaluation of the changes in vital signs during and after the pre-oxygenation phase in the two combinations of position and ventilation mode


Original Secondary Outcome: Same as current

Information By: Laval University

Dates:
Date Received: October 6, 2015
Date Started: September 2015
Date Completion:
Last Updated: October 18, 2016
Last Verified: October 2016