Effects of airway pressure on contrast enhancement and diameter of the pulmonary artery in healthy dogs as determined by use of computed tomography angiography.

OBJECTIVE

To evaluate effects of airway pressure on contrast enhancement and diameter of the pulmonary artery and determine the optimal airway pressure for pulmonary CT angiography in dogs.

ANIMALS

8 healthy Beagles.

PROCEDURES

Thoracic CT was performed at end-expiration (0 cm HO) and 2 positive-pressure end-inspirations (10 and 20 cm HO). Attenuation curves of enhancement for the sinus of the pulmonary trunk artery were obtained by use of a bolus technique. Contrast medium (300 mg of I/kg) was administered IV, and CT imaging began at the time of peak enhancement. At each pressure, time to peak enhancement, ratio of blood flow from the caudal vena cava to the right side of the heart (K), and enhancement characteristics and diameter changes of the pulmonary artery were evaluated.

RESULTS

All dogs had a significant delay for time to peak enhancement in the sinus of the pulmonary trunk artery as airway pressure increased. The K progressively increased as airway pressure increased, and there was low contrast enhancement and increased pulmonary artery filling defects at 20 cm HO. All pulmonary arteries had marked increases in diameter as pressure increased. Arterial distensibility in the gravity-dependent cranial lung region was greater than that in the gravity-independent caudal lung region at the 2 positive-pressure end-inspirations.

CONCLUSIONS AND CLINICAL RELEVANCE

Airway pressure affected time to peak enhancement, K, contrast enhancement, and pulmonary artery diameter. Results suggested that 10 cm HO could be an optimal pressure for evaluation of the pulmonary artery of dogs by use of CT angiography. ( 2019;80;756-763).