Vasoconstrictor: An agent which causes narrowing of blood vessels.
Commonly used vasoconstrictor medications are dopamine, nor-adrenaline, adrenaline and vasopressin. These medications can be used to increased blood pressure when it is low. In this case they used as continuous infusion into the blood vessels, usually a major one known as central line. In this case it is a lifesaving medication.
Vasoconstrictors can also be used to reduce bleeding by injection around the site of bleeding so that blood vessels to the region contract and reduce blood flow to the region. Decrease in blood flow to the region can also decrease the outflow of deoxygenated blood from the region. This effect is used to prolong the action of local anaesthesia medication. For this vasoconstrictor medication like adrenaline is commonly added to local anaesthetic medication like lignocaine.
Downside of vasoconstrictors
Vasoconstrictors often stimulate the heart and increase the heart rate. This can be sometimes counterproductive as it increases the oxygen demand of the heart. Those persons with diseased blood vessels of the heart can develop chest pain in this scenario. They can also produce heart rhythm abnormalities. Prolonged infusion of vasoconstrictors can reduce blood flood to the limb extremities which can sometimes cause damage to the local tissue.