Question

Which of the following are physiological effects of positive end-expiratory pressure (PEEP) used in the treatment of ARDS?

1) Increases functional residual capacity
2) Prevents collapse of unstable alveoli
3) Improves arterial oxygenation
4) Opens collapsed alveoli
5) Improves carbon dioxide retention

Answer 1

Positive end-expiratory pressure (PEEP) helps treat ARDS by increasing functional residual capacity, preventing alveolar collapse, and improving arterial oxygenation, among other benefits. It does not, however, improve carbon dioxide retention.

Step-by-step explanation:

The physiological effects of positive end-expiratory pressure (PEEP) in the treatment of Acute Respiratory Distress Syndrome (ARDS) include several important mechanisms. These are:

1. Increases functional residual capacity (FRC) - the residual volume of air left in the lungs after a passive exhalation is increased, which helps to oxygenate blood more effectively.
2. Prevents collapse of unstable alveoli - by maintaining a positive pressure in the airways during expiration, it prevents the alveoli from collapsing, facilitating gas exchange.
3. Improves arterial oxygenation - by keeping alveoli open, there is an improvement in arterial oxygen levels.
4. Opens collapsed alveoli - PEEP can aid in the recruitment process of reopening airways that are closed, helping to enhance lung function.
5. PEEP does not improve carbon dioxide retention; rather, effort is often to improve its elimination.

By increasing lung volume and reducing the surface tension within the alveoli through the role of pulmonary surfactant, PEEP ensures better lung compliance and reduced resistance to airflow, thus supporting the treatment and management of ARDS.