Abstract
Unanesthetized, chronically instrumented newborn and adult sheep were subjected to acute circulatory preload stress (rapid administration of 30 ml X kg-1 isotonic saline) and afterload stress (intravenous administration of 0.2 mg X kg-1 methoxamine). Variables of circulatory status and myocardial function were monitored continuously during experimental manipulations. Preload stress elevated arterial and venous pressures, reduced the preejection period (PEP) to left ventricular ejection time (LVET) ratio (PEP/LVET), and increased the rate of left ventricular pressure rise (dp/dt) to a comparable extent in newborn and adult subjects. Afterload stress increased arterial and venous pressures to a comparable extent in newborns and adults; the percent changes in PEP (25), LVET (16), PEP/LVET (12) and dp/dt (-21) in newborns were more pronounced than those in adults.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.