Low blood pressure can be caused by low blood volume, hormonal changes, widening of blood vessels, medicine side effects, severe dehydration, anemia, vitamin B12 and folic acid deficiencies, anaphylaxis, heart problems or endocrine problems. Reduced blood volume, hypovolemia, is the most common cause of<unk> . This can result from hemorrhage; insufficient fluid intake, as in starvation; or excessive fluid losses from diarrhea or vomiting. Hypovolemia can be induced by excessive use of diuretics. Low blood pressure may also be attributed to heat stroke which can be indicated by absence of perspiration, light headedness and dark colored urine. Other medications can produce<unk>  by different mechanisms. Chronic use of alpha blockers or beta blockers can lead to<unk> . Beta blockers can cause<unk>  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 failure, large myocardial infarction, heart valve problems, or extremely low heart rate (bradycardia), often produces<unk>  and can rapidly progress to cardiogenic<unk> ock. Arrhythmias often result in<unk>  by this mechanism. Excessive vasodilation, or insufficient constriction of the blood vessels (mostly arterioles), causes<unk> . 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. Dysautonomia, an intrinsic abnormality in autonomic system functioning, can also lead to<unk> . Excessive vasodilation can also result from sepsis, acidosis, or medications, such as nitrate preparations, calcium channel blockers, or AT1 receptor antagonists (Angiotensin II acts on AT1 receptors). Many anesthetic agents and techniques, including spinal anesthesia and most inhalational agents, produce significant vasodilation. Meditation, yoga, or other mental-physiological disciplines may produce hypotensive effects. Lower blood pressure is a side effect of certain herbal medicines, which can also interact with several medications. An example is the theobromine in Theobroma cacao, which lowers blood pressure through its actions as both a vasodilator and a diuretic, and has been used to treat high blood pressure. Syndromes Orthostatic<unk>  Orthostatic<unk> , also called postural<unk> , is a common form of low 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. It is commonly seen in hypovolemia and as a result of various medications. In addition to blood pressure-lowering medications, many psychiatric medications, in particular antidepressants, can have this side effect. Simple blood pressure and heart rate measurements while lying, seated, and standing (with a two-minute delay in between each position change) can confirm the presence of orthostatic<unk> . Taking these measurements is known as orthostatic vitals. Orthostatic<unk>  is indicated if there is a drop of 20 mmHg in systolic pressure (and a 10 mmHg drop in diastolic pressure in some facilities) and a 20 beats per minute increase in heart rate. Vasovagal syncope Vasovagal syncope is a form of dysautonomia characterized by an inappropriate drop in blood pressure while in the upright position. Vasovagal syncope occurs as a result of increased activity of the vagus nerve, the mainstay of the parasympathetic nervous system. Patients will feel sudden, unprovoked lightheadedness, sweating, changes in vision, and finally a loss of consciousness. Consciousness will often return rapidly once patient is lying down and the blood pressure returns to normal. Other Another, but rarer form, is postprandial<unk> , a drastic decline in blood pressure that occurs 30 to 75 minutes after eating substantial meals. When a great deal of blood is diverted to the intestines (a kind of "splanchnic blood pooling") to facilitate digestion and absorption, the body must increase cardiac output and peripheral vasoconstriction to maintain enough blood pressure to perfuse vital organs, such as the brain. Postprandial<unk>  is believed to be caused by the autonomic nervous system not compensating appropriately, because of aging or a specific disorder.<unk>  is a feature of Flammer syndrome, which is characterized by cold hands and feet and predisposes to normal tension glaucoma.<unk>  can be a symptom of relative energy deficiency in sport, sometimes known as the female athlete triad, although it can also affect men.
Hypotension
Bradypnea
Bradycardia
Apnea
Hypopnea
Sedation
Hypsarrhythmia
Somnolence