Normal Variation in Blood Pressure with Respiration

Physiological Mechanisms of Respiratory BP Variation

During inspiration, there is a normal decrease in intrathoracic pressure that slightly reduces pulmonary arterial pressure relative to atmospheric pressure, according to the American College of Cardiology, resulting in increased pulmonary blood flow 1, 2
This inspiratory decrease in intrathoracic pressure increases venous return to the right heart, resulting in an increase in pulmonary blood flow, as stated by the American College of Cardiology 2
With passive exhalation, intrathoracic pressure approaches atmospheric pressure, reversing these effects, as noted by the American College of Cardiology 2

To reduce variability in clinical measurements, pressures should be consistently measured over 2 to 3 respiratory cycles at end-exhalation when intrathoracic pressure is closest to atmospheric, as recommended by the American College of Cardiology 1, 2
Respiratory effects on blood pressure become accentuated during assisted ventilation, in patients with lung disease, and during exercise, hyperventilation, or Valsalva maneuver, according to the American College of Cardiology 2
For accurate blood pressure measurement, patients should avoid exercise, caffeine, alcohol, and smoking within 30 minutes prior to measurement, be positioned with both feet on the floor and arm supported at heart level, rest for at least 5 minutes before measurements, and have an appropriately sized cuff, as recommended by the Mayo Clinic 3

Exaggerated respiratory blood pressure variations may occur in cardiac tamponade, as noted by the American College of Cardiology 2
Exaggerated respiratory blood pressure variations may also occur in positive pressure ventilation, according to the American College of Cardiology 2