title: Impedance cardiography-derived hemodynamic responses during baroreceptor testing with amyl nitrite and phenylephrine: a validity and reliability study.
abstract: Baroreflex (BR) testing with phenylephrine (PE) and amyl nitrite (AN) provided an opportunity to evaluate the ability of impedance cardiography (IC) to track the rapid hemodynamic (HD) changes elicited by these drugs. The AN response was measured after inhalation and the PE response was measured after a bolus injection in 19 subjects on two occasions. High reliability was observed for all of the HD measures. Blood pressure (BP), peripheral resistance (PR), and preejection period (PEP) decreased significantly after administration of AN, whereas heart rate (HR) and cardiac output (Q) increased. BP and total PR increased significantly after administration of PE; HR and Q decreased and PEP did not change significantly. Stroke volume did not change significantly with either drug. The BR slope was reliably elicited with AN and PE. The IC and Finapres BP consistently detected short-term changes in HD responses to AN and PE. The pharmacological interventions demonstrated that IC measures followed the course predicted by the actions of the drugs. Change in PEP and dZ/dt reflected increased contractility. The BR sensitivity was also reproducible.
authors: Department of Psychiatry, University of California, San Diego 92093-0804, USA. melesen@ucsd.edu
authors: R A
authors: RA
authors: Nelesen
authors: R
authors: R
authors: Shaw
authors: M G
authors: MG
authors: Ziegler
authors: J E
authors: JE
authors: Dimsdale
mesh_terms: D000328:Adult; D000680:Amyl Nitrite / Q000494:pharmacology*; D002307:Cardiography, Impedance; D005006:Ethnicity; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine / Q000494:pharmacology*; D011311:Pressoreceptors / Q000187:drug effects*; D015203:Reproducibility of Results; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D000680:Amyl Nitrite