What is the effect of Positive End-Expiratory Pressure (PEEP) therapy on the lungs and cardiovascular system?

From the Guidelines

Positive end-expiratory pressure (PEEP) therapy will result in a decrease in extravascular lung water, which is answer choice (a). This is because PEEP works by maintaining positive pressure in the airways at the end of expiration, which prevents alveolar collapse and improves oxygenation, as noted in a study published in 2024 1. The positive pressure pushes fluid from the alveolar spaces back into the pulmonary capillaries and lymphatics, thereby reducing extravascular lung water, especially in conditions like pulmonary edema. Some key points to consider when using PEEP include:

• PEEP actually decreases cardiac preload by increasing intrathoracic pressure, which reduces venous return to the heart, as discussed in a study from 2016 1.
• It typically increases atrial natriuretic peptide release due to atrial stretching from the increased intrathoracic pressure.
• PEEP also increases functional residual capacity by preventing alveolar collapse and recruiting previously collapsed alveoli, as mentioned in a study from 2017 1. These physiological effects make PEEP valuable in managing patients with respiratory failure, ARDS, and other conditions requiring mechanical ventilation, though careful titration is necessary to balance its beneficial respiratory effects against potential adverse hemodynamic consequences, as highlighted in the most recent study from 2024 1.

From the Research

Positive End-Expiratory Pressure Therapy Effects

• The application of positive end-expiratory pressure (PEEP) therapy has several effects on the body, including:
  • Increase in extravascular lung water: A study published in 2006 2 found that PEEP ventilation increases extravascular lung water due to a decrease in lung lymph flow.
  • Decrease in atrial natriuretic peptide: Research from 1986 3 and 1993 4 suggests that PEEP can decrease the release of atrial natriuretic peptide, which plays a role in fluid balance.
  • Increase in functional residual capacity: PEEP is used to improve gas exchange and increase functional residual capacity, as stated in the 2017 study 5.
• Cardiac effects:
  • PEEP may cause circulatory depression, as mentioned in the 2017 study 5.
  • The 1986 study 3 found that PEEP can decrease cardiac index and glomerular filtration rate.
• Other effects:
  • PEEP can improve arterial oxygenation and reduce tidal lung stress and strain, as stated in the 2017 study 5.
  • The 2006 study 2 found that the increase in PEEP resulted in a decrease in pulmonary lymph flow.

Answer to the Question

Based on the provided evidence, the correct answer is: (a) decrease in extravascular lung water: This option is incorrect, as the 2006 study 2 found that PEEP increases extravascular lung water. (b) increase in cardiac preload: There is no direct evidence to support this option. (c) decrease in atrial natriuretic peptide: This option is correct, as supported by the 1986 3 and 1993 4 studies. (d) decrease in functional residual capacity: This option is incorrect, as PEEP is used to increase functional residual capacity, as stated in the 2017 study 5.