Answer:3: decreased filling of the right side of the heart
Explanation:
Pneumothorax occurs when the parietal or visceral pleura is breached or punctured, this leads to exposure of the pleural space to positive atmospheric pressure.
Normally, the pressure in the pleural space is negative compared to atmospheric pressure. This is required to maintain the inflation of lung. A breach to the pleura causes air to enter the pleural space thereby leading to lung collapse.
With an increased breath, there is an increase positive pressure in the pleural space, the air that entered the chest cavity is trapped and cannot be expelled. This leads to lung collapse and the heart, great vessels, and the trachea moves to the unaffected side(mediastinal shift).
The increased positive pressure decreases venous return to the heart (filling of the right side of the heart), causing decreased cardiac output and impairment of circulation round the body.
