The Use of Pulmonary Hyperinflation With the Mechanical Ventilator in Cardiac Patients

Mechanical ventilation (MV) is used to reduce work and reverse or prevent fatigue of the respiratory muscles, decrease oxygen consumption and maintain gas exchange. In addition to the benefits given to patients undergoing MV, there is a high risk of accumulating bronchial secretions, related to pathology and / or therapeutic intervention. Pulmonary hyperinflation is widespread in patients in intensive care centers (ICUs) as a bronchial hygiene therapy, being used in 40% of 64 Australian ICUs as demonstrated by Dennis et al., Through contact with physical therapists. Mechanical hyperinflation associated with tracheal aspiration is able to increase the amount of secretion aspirated when compared to isolated aspiration in patients undergoing mechanical ventilation.

To evaluate whether the use of the pulmonary hyperinflation maneuver in the mechanical ventilator is hemodynamically stable through the collection in two moments of the heart rate (HR), mean arterial pressure (MAP), peripheral saturation (SpO2), respiratory rate (RF) variables that will be analyzed from the postoperative unit's multiparametric monitor.

Evaluate the change in respiratory mechanics through collection in two moments after the mechanical hyperinflation technique through dynamic compliance (Cdyn), tidal air volume (VAC), peak pressure (Ppico). The population will consist of patients from the Post-Operative Unit (UPO), unit intensive care (UCI) and emergency room, from the Institute of Cardiology, of both sexes, over 18 years old, mechanically ventilated more than 48 hours and the sample consisting of 50 individuals. These will be submitted to the use of the pulmonary hyperinflation maneuver in the mechanical ventilator.

This is a randomized crossover clinical trial in which the individuals selected for the study will be randomized to receive isolated tracheal aspiration (Control Group) and pulmonary hyperinflation through the mechanical ventilator associated with tracheal aspiration (Intervention Group). Randomization will be performed through the randomization.com website by a 1: 1 crossed block, allocating the patient to one of the groups and, after 24 hours, another technique will be performed. In addition, a control aspiration will be performed 2 hours before both techniques.

For basal aspiration, the patient will be placed in the supine position with the head elevated at 30º, will be submitted to a single aspiration with a size 12 probe (Mark Med), with a vacuum adjusted to -40cmH2O of pressure, with basic asepsis care being maintained for performing the technique35.

In the control group, patients will be ventilated for 1 minute with 100% inspired oxygen (FiO2), followed by three aspirations for 15 seconds and with an interval of 30 seconds.

In the participants of the intervention group, the calculation of the ideal tidal volume for each patient will be performed, after which they will be positioned in the supine position, the head elevated to 30º in assisted pressure-controlled ventilation mode, increasing 10 cmH2O in inspiratory pressure and, in assisted ventilation mode. controlled by volume, we will increase 50% of the tidal volume for a period of 10 minutes, observing the Ppeak that cannot exceed 40 cmH2O and the drive pressure that cannot exceed 15 cmH2O in both ventilation modes, and then a new aspiration will be performed. in the same way as the control group. The hemodynamics data will be taken from the multiparametric monitor of the hospitalization units (philips) and the respiratory mechanics data will be collected from the mechanical ventilator screen (Servo S; Drager; Newport), before and after the techniques. The volume of secretion will be stored in the collection flask (Water Seal 120 ml) and weighed using a high precision scale, discounting the weight of the collection flask.

The Informed Consent Form (ICF) will be signed by the responsible family member, containing information and explanations about the present study and the researcher will be available to explain doubts and questions at the time and afterwards through the telephone present at the ICF. All procedures will be performed under the supervision of the physiotherapist at the hospital. It is understood that this research may offer a minimal risk to volunteers, according to resolution 466/12 of the National Health Council, since they may have some discomfort and / or their hemodynamic situation altered by the application of the aforementioned physical therapy technique. As a counterpart, in case the predicted risk occurs, the subjects will receive all the necessary care from the researcher, together with the unit's physiotherapist and medical team, if necessary. The benefits to the subjects refer to the possibility of improving their respiratory function and bronchial hygiene.