[Relation between ultrasound-measured diaphragm movement and partial pressure of carbon dioxide in blood from patients with acute hypercapnic respiratory failure after the start of noninvasive ventilation in an emergency department].

Objectives: To evaluate the correlation between variations in ultrasound-measured diaphragm movement and changes in the arterial partial pressure of carbon dioxide (PCO2) after the start of noninvasive ventilation (NIV).

Material And Methods: RDescriptive study of a prospective case series comprised of nonconsecutive patients aged 18 years or older with hypercapnic respiratory failure who were placed on NIV in an emergency department. We recorded clinical data, blood gas measurements, and ultrasound measurements of diaphragm movement.

Results: Twenty-one patients with a mean (SD) age of 83 (13) years were studied; 11 (52.4%) were women. The mean (SD) range of diaphragm movement and PCO2 values at 4 moments were as follows: 1) at baseline: diaphragm movement, 13.90 (7.7) mm and PCO2, 71.75 (11.4) mm Hg; 2) after 15 minutes on NIV: diaphragm movement, 17.10 (9.1) mm; 3) at 1 hour: diaphragm movement, 22.40 (10.4) mm and PCO2, 63.45 (16.0) mm Hg; and 4) at 3 hours: diaphragm movement, 26.60 (19.5) mm and PCO2, 61.85 (13.0) mm Hg. We detected a statistically significant correlation between the difference in range of diaphragm movement at baseline and at 15 minutes and the decrease in PCO2 after 1 hour of NIV (r=-0.489, P=.035).

Conclusion: In patients with hypercapnic respiratory failure, the increase in range of diaphragm movement 15 minutes after starting NIV is associated with a decrease in PCO2 after 1 hour.