Lung Recruitment During Chest Physiotherapy in Mechanically Ventilated Patients

Evaluation of Lung Recruitment During Chest Physiotherapy in Mechanically Ventilated Patients

In intensive care, respiratory physiotherapy is an integral part of the daily care of patients under invasive mechanical ventilation. Its goals are to improve the clearance of bronchial secretions to allow for the resolution of atelectasis and alveolar recruitment, thereby enhancing respiratory mechanics and gas exchange. The most widespread technique in France is external expiratory compression of the chest.

The effectiveness of this technique depends on the selection of patients (it seems to be more effective in patients with higher secretion levels) and on the practical implementation of the technique (favoring brief and vigorous compressions at the beginning of expiration). However, the effect of the artificial ventilator settings, particularly the ventilatory mode used during the respiratory physiotherapy session, has never been evaluated. The two most commonly used ventilatory modes worldwide are Volume Assist Control Ventilation (V-ACV) and pressure support ventilation (PSV). In this unit, respiratory physiotherapy under artificial ventilation is performed daily on patients with artificial ventilation with abundant secretions, regardless of the ventilatory mode.

It is hypothesized that the effectiveness of respiratory physiotherapy on recruitment depends on the ventilatory mode used during the session.

The primary objective is to compare pulmonary recruitment during respiratory physiotherapy in patients under invasive mechanical ventilation between sessions performed in V-ACV and PSV.

Secondary objectives are to compare the effects of respiratory physiotherapy between V-ACV mode and PSV mode on respiratory mechanics, gas exchange, the amount of drained secretions (weight and volume), the distribution of ventilation, and patient tolerance.

Method:

A cross-over study with a non-invasive physiological endpoint. The primary evaluation criterion is variations in end-expiratory lung volume (ΔEELV) measured 5 minutes before and 5 minutes after a standardized respiratory physiotherapy session in V-ACV or PSV.

The tool used to measure End Expiratory Lung Volume (EELV) is the additional module E-sCOVX of the CARESCAPE R860 ventilator. The procedure is automated and is based on a dilution method.

Secondary outcomes aim to evaluate regional lung ventilation distribution, respiratory mechanics, airway clearance, gas exchange, and patient tolerance.

Tools used to measure secondary evaluation criteria include Electrical Impedance Tomography (EIT) Pulmovista 500® (Dräger), a Pneumotachograph with a pressure transducer inserted in the ventilator circuit (MP150, Biopac Systems, Inc.), and a trap to collect mucus.

The intervention consists of a standardized session in a standardized position (supine at 35° of head elevation).

Each session is composed of 7 series of 3 Rib Cage Compressions (RCC) in a row during each expiration, applied to the thorax only. The interval between the series is about 10 respiratory cycles.

The 2 sessions are done on the same day. One session is performed in the morning, the other in the afternoon. One session is performed in V-ACV and the other in PSV. The order is randomized.

Conclusion:

The results of this study will help better understand the effects of RCC according to the ventilatory mode in patients under invasive mechanical ventilation with mucus excess.

Inclusion Criteria:

• Patient under assisted ventilation (in V-ACV or PSV) triggering all ventilator cycles
• Patient deemed " secretive ": requiring ≥ 2 tracheal aspirations every 3 hours
• Patient (or relative) who has given consent to participate in the research
• Patient covered by social security

Exclusion Criteria:

• Age under 18 years
• Legal guardian required
• Recent cardiac and/or thoracic and/or abdominal surgery (< 3 months)
• Rib fracture(s)
• Pneumothorax and/or presence of a chest drain
• Recent neurosurgery (< 3 months) and/or proven or suspected increased intracranial pressure (ICP)
• Hemodynamic instability defined as: noradrenaline ≥ 1mg/h, adrenaline ≥ 0.5 mg/h, dobutamine ≥ 5γ/kg/min.
• Respiratory instability defined as: PEEP > 10 cmH2O and/or PaO2/FiO2 < 150 mm Hg
• Pregnancy
• Hemoptysis
• Sever skin lesions (e.g., burns, Lyell's syndrome)
• Patient under foreign health insurance