• Journal of critical care · Mar 1994

    Comparative Study

    The effect of adrenergic agonists on the systemic response to hemorrhage.

    • R W Samsel, T H Lewis, W M Sanders, L D Wood, and P T Schumacker.
    • Department of Medicine, University of Chicago, Illinois.
    • J Crit Care. 1994 Mar 1; 9 (1): 25-33.

    PurposeSystemic blood loss elicits a variety of reflex cardiovascular responses, which preserve cardiac output as possible and preserve arterial blood pressure when cardiac output decreases. When compensatory venoconstriction is exhausted, hemorrhage reduces oxygen delivery (QO2), and systemic vasoconstriction competes with local metabolic vasodilation to preserve tissue oxygen uptake (VO2). Through their effects on vascular tone and blood flow distribution, adrenergic agents might interfere with the physiological responses to reduced O2 delivery. This study was designed to determine the effects of dobutamine and norepinephrine on oxygen extraction and systemic vascular resistance during progressive hemorrhage.MethodsWe infused dobutamine or norepinephrine into anesthetized, ventilated dogs and measured the systemic vascular resistance, oxygen consumption, and oxygen extraction ratio as oxygen delivery (blood flow) was reduced by blood withdrawal. Four groups were compared: control (saline), dobutamine (10 micrograms/kg/min), high-dose norepinephrine (1.0 microgram/kg/min), and low-dose norepinephrine (0.1 microgram/kg/min).ResultsHigh-dose norepinephrine increased oxygen demand but did not alter extraction significantly at the critical point. Neither low-dose norepinephrine nor dobutamine affected oxygen extraction during hemorrhage. Dobutamine and norepinephrine both ablated the increase in systemic vascular resistance that accompanies hemorrhage. Low-dose norepinephrine was not different from control.ConclusionsNorepinephrine and dobutamine appear to block reflex vasoconstriction, and mechanistic explanations for this finding remain speculative. Despite inhibition of reflex vasoconstriction, neither dobutamine nor norepinephrine significantly impaired oxygen extraction during hemorrhage.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…