Nitroglycerin has a more profound venodilating than arteriolar effect. In the presence of hypovolemia, it may cause a decrease in venous return and CO; in these conditions, reflex tachycardia is common [ 27 ]. Nitroglycerin is indicated in severe hypertension associated with volume overload and pulmonary edema. Nitroglycerin as other vasodilators may increase pulmonary shunt and aggravate systemic hypoxemia by inhibiting pulmonary hypoxic vasoconstriction.
Low blood pressure can be caused by low blood volumehormonal changes, widening of blood vesselsmedicine side effectsanemiaheart problems or endocrine problems.
Reduced blood volume, hypovolemiais the most common cause of hypotension. This can result from hemorrhage ; insufficient fluid intake, as in starvation; or excessive fluid losses from diarrhea or vomiting.
Hypovolemia is often induced by excessive use of diuretics. Low blood pressure may also be attributed to heat stroke.
The body may have enough fluid but does not retain electrolytes. Absence of perspiration, light headedness and dark coloured urine are also indicators. Other medications can produce hypotension by different mechanisms. Chronic use of alpha blockers or beta blockers can lead to hypotension.
Beta blockers can cause hypotension both by slowing the heart rate and by decreasing the pumping ability of the heart muscle. Decreased cardiac output despite normal blood volume, due to severe congestive heart failurelarge myocardial infarctionheart valve problems, or extremely low heart rate bradycardiaoften produces hypotension and can rapidly progress to cardiogenic shock.
Arrhythmias often result in hypotension by this mechanism. Some heart conditions can lead to low blood pressure, including extremely low heart rate bradycardiaheart valve problems, heart attack and heart failure.
These conditions may cause low blood pressure because they prevent the body from being able to circulate enough blood. Excessive vasodilationor insufficient constriction of the resistance blood vessels mostly arteriolescauses hypotension.
This can be due to decreased sympathetic nervous system output or to increased parasympathetic activity occurring as a consequence of injury to the brain or spinal cord or of dysautonomiaan intrinsic abnormality in autonomic system functioning.
Excessive vasodilation can also result from sepsisacidosisor medications, such as nitrate preparationscalcium channel blockersor AT1 receptor antagonists Angiotensin II acts on AT1 receptors. Many anesthetic agents and techniques, including spinal anesthesia and most inhalational agentsproduce significant vasodilation.
Meditationyogaor other mental-physiological disciplines may reduce hypotensive effects.
An example is the theobromine in Theobroma cacaowhich lowers blood pressure  through its actions as both a vasodilator and a diuretic and has been used to treat high blood pressure.
It occurs after a change in body position, typically when a person stands up from either a seated or lying position.
It is usually transient and represents a delay in the normal compensatory ability of the autonomic nervous system.Hypertensive Emergencies Michael Jay Bresler, MD, FACEP Clinical Professor Division of Emergency Medicine Stanford University School of Medicine • No intracerebral vasodilation causing edema Hypertensive Emergencies Requiring Blood Pressure Reduction in the ED.
Auto-Regulation and Hypertensive Crisis. Emergency Cart This is also known as crash carts are found in all hospitals and emergency rooms and contain supplies and equipment necessary to treat life-threatening situations.
Emergency Cart is a wheeled cabinet or chest of drawers that contains all of the equipment necessary for emergency . A hypertensive emergency is severe hypertension with signs of damage to target organs (primarily the brain, cardiovascular system, and kidneys).
Diagnosis is by BP measurement, ECG, urinalysis, and serum BUN and creatinine measurements. Nitroglycerin is a vasodilator that affects veins more than arterioles.
It can be used to . [1,7] In contrast to shorter-acting vasodilators for hypertensive emergency, the enalaprilat dosage is not easily adjusted. Once a bolus dose is given, a longer time is needed before the clinical. Hypertensive emergencies, a subset of hypertensive crises, are characterized by acute, severe elevations in blood pressure, often greater than / mm Hg (typically with systolic blood pressure.
A hypertensive emergency is severe hypertension with signs of damage to target organs (primarily the brain, cardiovascular system, and kidneys). Diagnosis is by BP measurement, ECG, urinalysis, and serum BUN and creatinine measurements.