Mechanical ventilation (MV) is crucial in managing respiratory insufficiency. However, prolonged use can cause complications. Various strategies have been explored to optimize patient outcomes.

Patients receiving IMV face multiple challenges in clearing lung secretions, such as inadequate humidification, high oxygen fractions, use of sedatives/analgesics, basal lung disease, and mechanical interference with secretion elimination near the trachea. Airway suctioning may not be sufficient in clearing the airway of mechanically ventilated patients, especially if they are paralyzed or lack a preserved cough reflex. This can lead to secretion retention, which may cause hypoxemia, atelectasis, ventilator-associated pneumonia, and delay weaning from MV. Bronchial hygiene is believed to improve respiratory system compliance by increasing Cdyn and Cst.

Airway clearance techniques are commonly used in the treatment of patients with IMV to improve their pulmonary function through bronchial clearance, expansion of collapsed lung areas, and balancing of the ventilation/perfusion ratio. Physiotherapy methods including postural drainage, manual rib-cage compression (MRC), manual hyperinflation, positive end-expiratory pressure-zero end-expiratory pressure (PEEP-ZEEP) maneuver, and tracheal suctioning can alleviate atelectasis and improve bronchial hygiene.

Two effective techniques for improving lung function and gas exchange are Expiratory Rib Cage Compression (ERCC) and the PEEP-ZEEP maneuver. ERCC applies external pressure during expiration, and PEEP-ZEEP temporarily reduces Positive End-Expiratory Pressure (PEEP) to 0 cmH2O, followed by a rapid return to the original PEEP level during expiration. Both techniques help to mobilize and remove airway secretions, ultimately improving lung function and gas exchange.

Expiratory rib cage compression is a form of chest physiotherapy that involves squeezing the chest with the hands during expiration and releasing it at the end of expiration to aid in the mobilization of lung secretions, facilitate comfortable inspiration, and promote alveolar ventilation. The concept of manual chest compression was first explored in the 1950s, when Opie et al. proposed that local chest compression produces a "toothpaste" effect, which helps to expel the retained material through the bronchus. This phenomenon piqued the interest of other researchers, leading to a better understanding of the functioning of the mucous layer and the development of therapeutic strategies to improve it.

This technique increases forced expiratory volume by 30% and leads to the resting of the expiratory muscles. Most of all, the technique is quite safe, as it has been employed in some patients for more than 3 years with no complications. Therefore, this technique can be used before the patients' endotracheal suctioning interventions, and it is widely used with mechanically ventilated patients to prevent and/or to treat atelectasis. In addition, removing secretion is essential because accumulated secretions intervene in gas exchange and may delay recovery; coughing can be initiated voluntarily or by reflex.

The positive end-expiratory pressure-zero end-expiratory pressure maneuver considers that by raising PEEP to 15 cmH2O during five cycles, followed by an abrupt reduction of PEEP to 0 cmH2O, gas redistribution occurs through collateral ventilation. Subsequently, small airways are opened, and the adhered mucus is displaced. With the reduction of PEEP, the expiratory flow pattern is modified, causing the secretions located in smaller airways to be transported to the central airways.

While many studies have looked at the effects of rib cage compression (RCC) or the PEEP-ZEEP maneuver individually, there is a need for comparative studies that directly compare these two techniques. Understanding the different effects of these interventions on oxygenation, ventilation, and airway-secretion removal can help critical care nurses (CCNs) choose the most effective strategy for mechanically ventilated patients. Therefore, the purpose of this study is to compare the effects of RCC and the PEEP-ZEEP maneuver on oxygenation, ventilation, and airway-secretion removal in mechanically ventilated patients. By evaluating these outcomes, we can gain insights into the potential benefits and limitations of each technique, ultimately contributing to the optimization of respiratory support strategies in critically ill patients.

The findings of this study can have important implications for CCN clinical practice as they can inform CCNs about the efficacy and safety of RCC and the PEEP-ZEEP maneuver. Improving oxygenation, ventilation, and airway-secretion removal in mechanically ventilated patients can lead to enhanced patient outcomes, reduced complications, and potentially shorter durations of mechanical ventilation and intensive care unit stays.

Inclusion Criteria:

• Patients who are aged ≥18 years.
• Patients who have tracheal intubation and are likely to require MV for ≥72 hours.
• Patients who are hemodynamically stable: Heart rate (HR): ≥ 60 b or ≤100 b/min, mean arterial pressure (MAP) ≥ 90 mmHg, central venous pressure ≥ 3 or ≤ 8 cmH2O.

Exclusion Criteria:

• Patients with pneumothorax, rib fracture, and subcutaneous emphysema.
• Patients with traumatic brain injuries and spinal cord injuries.
• Patients with ARDS who require high PEEP levels (>10 cmH2O).
• Patients admitted with pneumonia.
• Pregnant patients.