Related Experiment Video
Updated: Aug 15, 2026

Quantitative Autonomic Testing
Published on: July 19, 2011
Abstract:
To return to the patient's syncopal episode, it is clearer now that he probably did have a vasovagal reaction. An hour had elapsed since administration of morphine, making that etiology unlikely. The patient showed no evidence of heart block or acute ischemia. While nitrate induced hypotension may have contributed to his faint, that would not have explained his bradycardia. Worth noting is the fact that he developed nausea and lost consciousness as an arterial puncture was about to be performed. Had he been asked, the patient might have recalled other incidents of vasovagal fainting. A combination of factors may cause a brief syncopal episode in the ICU. Sorting out the causes of vasovagal syncope may be difficult if not impossible, and a syncopal episode may set a chain of events into motion that further complicates the situation. The patient with an acute, especially inferior MI who received intravenous medications is particularly prone to vagal-like reactions. Patients with nausea or extreme anxiety should be watched carefully and their symptoms treated.
Related Concept Videos
Disorders of the Autonomic Nervous System
Raynaud's disease, also known as Raynaud's phenomenon, is a...
Vascular Spasm
Imbalances in Cardiac Output
CHF can occur due to the failure of either side of the heart. Left-side failure leads to pulmonary congestion—the right side continues to send blood...
Blood Pressure Imbalances and Circulatory Shock
Blood Pressure: Hypertension and Hypotension
Normal blood pressure is 120/80 mm Hg. Elevated blood pressure is 120-129/under 80 mm Hg. Hypertension, warranting treatment at 130/80 mm Hg, is often asymptomatic and can lead to severe cardiovascular events, aneurysms, peripheral arterial disease, chronic renal disease, or cardiac...
Pathophysiology of Vomiting
Dysrhythmias II: Classification of Tachyarrhythmias

