The Influence of Xylazine and Clonidine on Lung Ultrasound-Induced Pulmonary Capillary Hemorrhage in Spontaneously Hypertensive Rats.

Induction of pulmonary capillary hemorrhage (PCH) by lung ultrasound (LUS) depends not only on physical exposure parameters but also on physiologic conditions and drug treatment. We studied the influence of xylazine and clonidine on LUS-induced PCH in spontaneously hypertensive and normotensive rats using diagnostic B-mode ultrasound at 7.3 MHz. Using ketamine anesthesia, rats receiving saline, xylazine, or clonidine treatment were tested with different pulse peak rarefactional pressure amplitudes in 5 min exposures. Results with xylazine or clonidine in spontaneously hypertensive rats were not significantly different at the three exposure pulse peak rarefactional pressure amplitudes, and thresholds were lower (2.2 MPa) than with saline (2.6 MPa). Variations in LUS PCH were not correlated with mean systemic blood pressure. Similar to previous findings for dexmedetomidine, the clinical drug clonidine tended to increase susceptibility to LUS PCH.