May 25, 2015
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Medical Student
Can anyone give explanations/mechanisms/pathophysiology for the following-

1. How narcotic overdose results in negative inotropic?

2. How sympathetic activity increases venous return?

3. How spinal anesthesia decreases venous return?

From- FA 2016,P.269 (cardiac physiology)

Thanks.
 

atomheart

2+ Year Member
May 5, 2016
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Resident [Any Field]
Narcotics: vasodilation through histamine release, suppression of adrenergic tone, increased psns activity to heart (possibly, different mechanism to decrease respiration or M2 activation)

Sns: that's all ANS physiology. CO = VR with Frank-starling mechanism, as well as venoconstriction

Spinal anesthesia: direct sympathetic block

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