Addition of positive end-expiratory pressure (PEEP) during anesthesia can cause a drop in blood pressure primarily due to:

Addition of positive end-expiratory pressure (PEEP) during anesthesia can cause a drop in blood pressure primarily due to:

• A. Tension pneumothorax
• B. Decreased venous return to the heart
• C. Increased afterload on the right ventricle
• D. Increased afterload on the left ventricle

Answer: (B)

PEEP raises intrathoracic pressure, which reduces venous return to the right heart. That lowers preload, leading to decreased stroke volume and cardiac output, and thus a drop in blood pressure. This preload-reduction effect is the dominant reason for hypotension with PEEP, especially at higher levels or in patients who are volume-depleted. While PEEP can influence afterload and venous pressures to some extent, these changes are generally less important than the fall in venous return.

PEEP raises intrathoracic pressure, which reduces venous return to the right heart. That lowers preload, leading to decreased stroke volume and cardiac output, and thus a drop in blood pressure. This preload-reduction effect is the dominant reason for hypotension with PEEP, especially at higher levels or in patients who are volume-depleted. While PEEP can influence afterload and venous pressures to some extent, these changes are generally less important than the fall in venous return.