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| {{Hypotension}} | | {{Hypotension}} |
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| | '''For patient information click [[{{PAGENAME}} (patient information)|here]]''' |
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| {{CMG}}; '''Associate Editor-In-Chief:''' {{CZ}} | | {{CMG}}; '''Associate Editor-In-Chief:''' {{CZ}} |
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| ==Overview== | | ==[[Hypotension overview|Overview]]== |
| '''Hypotension''' refers to an abnormally low [[blood pressure]]. This is best understood as a physiologic state, rather than a disease. It is often associated with [[Shock (medical)|shock]], though not necessarily indicative of it. Hypotension is not to be confused with [[hypertension]], which is [[high blood pressure]], the opposite of hypotension. Hypotension is a fairly rare problem, hypertension is a much more common problem. Hypotension is almost never a serious problem, although in some very rare cases it can be life threatening.
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| ==Normal physiology==
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| Blood pressure is continuously regulated by the [[autonomic nervous system]], using an elaborate network of [[sensory receptors|receptors]], [[nerve|nerves]], and [[hormone|hormones]] to balance the effects of the [[sympathetic nervous system]], which tends to raise blood pressure, and the [[parasympathetic nervous system]], which lowers it. The vast and rapid compensation abilities of the [[autonomic nervous system]] allow normal individuals to maintain an acceptable blood pressure over a wide range of activities and in many disease states.
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| ==Pathophysiology==
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| '''Reduced blood volume''', called [[hypovolemia]], is the most common mechanism producing hypotension. This can result from [[hemorrhage]], or blood loss; insufficient fluid intake, as in starvation; or excessive fluid losses from [[diarrhea]] or [[vomiting]]. Hypovolemia is often induced by excessive use of [[diuretic]]s. (Other medications can produce hypotension by different mechanisms.)
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| '''Decreased [[cardiac output]]''' despite normal blood volume, due to severe [[congestive heart failure]], large [[myocardial infarction]], or [[bradycardia]], often produces hypotension and can rapidly progress to [[cardiogenic shock]]. [[Arrhythmia]]s often result in hypotension by this mechanism. [[Beta blocker]]s can cause hypotension both by slowing the heart rate and by decreasing the pumping ability of the heart muscle.
| | ==[[Hypotension historical perspective|Historical Perspective]]== |
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| '''Excessive [[vasodilation]],''' or insufficient constriction of the resistance blood vessels (mostly [[arterioles]]), causes 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 [[dysautonomia]], an intrinsic abnormality in autonomic system functioning. Excessive vasodilation can also result from [[sepsis]], [[acidosis]], or medications, such as [[Glyceryl trinitrate (pharmacology)|nitrate preparations]], [[calcium channel blockers]], or [[ACE inhibitors]]. Many anesthetic agents and techniques, including [[spinal anesthesia]] and most [[Inhalational anaesthetic|inhalational agents]], produce significant vasodilation.
| | ==[[Hypotension pathophysiology|Pathophysiology]]== |
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| == Differential Diagnosis of Underlying Causes== | | ==[[Hypotension causes|Causes]]== |
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| In alphabetical order <ref>Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:92</ref> <ref>Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:204-205</ref>
| | ==[[Hypotension differential diagnosis|Differentiating Hypotension from other Diseases]]== |
| * [[Addison's Disease]]
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| * [[Adrenal insufficiency]]
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| * [[Adrenocortical insufficiency]]
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| * [[Adrenogenital syndrome]]
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| * [[Anaphylaxis]]
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| * [[Anemia]]
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| * [[Aortic Arch Syndrome]]
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| * Aortic Isthmus Stenosis
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| * [[Aortic Stenosis]]
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| * Autonomic failure
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| * [[Bartter's syndrome]]
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| * [[Cardiac valve]] defect
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| * [[Cardiogenic shock]]
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| * Carotid sinus syndrome
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| * [[Pericarditis|Constrictive pericarditis]]
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| * [[Dehydration]]
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| * [[Diabetes Insipidus]]
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| * Diabetic autonomic neuropathy
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| * [[Drug]]s
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| * During and after infections
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| * [[Dysrhythmias]]
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| * [[Ectopic Pregnancy]]
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| * Excessive fluid loss through dialysis
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| * [[Fatigue]]
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| * Fluid loss
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| * [[Guillain-Barre Syndrome]]
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| * [[Heart failure]]
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| * [[Heat]], [[Hypothermia]]
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| * [[Hemorrhage]] - [[Bleeding|bleeding]]
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| * Hemorrhagic shock
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| * [[Hepatitis]]
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| * [[Hyponatremia]]
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| * [[Hypothyroidism]]
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| * Idiopathic hypotension
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| * Insufficient fluid intake
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| * Internal bleeding
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| * Medications (hypotension secondary)
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| * Multiple cerebrovascular accidents (CVAs)
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| * [[Myocardial infarction]]
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| * [[Myocardial ischemia]]
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| * Neurogenic shock
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| * [[Orthostatic hypotension]]
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| * Overwhelming infection
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| * [[Paraplegia]]
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| * [[Parkinson's Disease]]
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| * [[Pericardial effusion]]
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| * [[Perimyocarditis]]
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| * Pituitary insufficiency
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| * [[Polyneuropathy]]
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| * [[Polyradiculitis]]
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| * Postprandial hypotension
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| * [[Pregnancy]]
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| * [[Pulmonary Embolism]]
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| * [[Septic shock]]
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| * [[Shy-Drager Syndrome]]
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| * Splenic rupture
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| * [[Syncope]], fainting
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| * [[Syringomyelia]]
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| * [[Tabes Dorsalis]]
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| * [[Trauma]]
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| * Vagal syncope
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| * [[Valsalva maneuver]]
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| * Volume depletion
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| ==Syndromes Related to Hypotension== | | ==[[Hypotension epidemiology and demographics|Epidemiology and Demographics]]== |
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| '''[[Orthostatic hypotension]]''', also called "postural hypotension", 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 the classes of blood pressure-lowering medications listed above, many psychiatric medications, in particular [[antidepressant|antidepressants]], can have this side effect. Simple blood pressure and heart rate measurements while lying, seated, and standing can confirm the presence of orthostatic hypotension.
| | ==[[Hypotension risk factors|Risk Factors]]== |
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| '''[[Neurocardiogenic syncope]]''' is a form of dysautonomia characterized by an inappropriate drop in blood pressure while in the upright position. Neurocardiogenic syncope is related to [[vasovagal syncope]] in that both occur as a result of increased activity of the [[vagus nerve]], the mainstay of the parasympathetic nervous system.
| | ==[[Hypotension natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
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| Another, but rarer form, is '''[[Postprandial]] [[hypotension]]''', which occurs 30–75 minutes after eating substantial meals. When a great deal of blood is diverted to the [[intestines]] to facilitate [[digestion]] and [[Digestion|absorption]], the body must increase [[cardiac output]] and peripheral [[vasoconstriction]] in order to maintain enough blood pressure to perfuse vital organs, such as the brain. It is believed that postprandial hypotension is caused by the [[autonomic nervous system]] not compensating appropriately, because of ageing or a specific disorder.
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| ==Diagnosis== | | ==Diagnosis== |
| ===Physical Examination===
| | [[Hypotension history and symptoms| History and Symptoms]] | [[Hypotension physical examination | Physical Examination]] | [[Hypotension laboratory findings|Laboratory Findings]] | [[Hypotension electrocardiogram|Electrocardiogram]] | [[Hypotension chest x ray|Chest X Ray]] | [[Hypotension CT|CT]] | [[Hypotension MRI|MRI]] | [[Hypotension echocardiography or ultrasound|Echocardiography or Ultrasound]] | [[Hypotension other imaging findings|Other Imaging Findings]] | [[Hypotension other diagnostic studies|Other Diagnostic Studies]] |
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| For most individuals, a healthy [[blood pressure]] lies from 90/50 mmHg to 135/90 mmHg. A small drop in blood pressure, even as little as 20 mmHg, can result in transient hypotension.
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| Evaluating [[neurocardiogenic syncope]] is done with a [[tilt table test]].
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| ===Symptoms===
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| The cardinal symptom of hypotension is [[lightheadedness]] or [[dizziness]].
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| If the blood pressure is sufficiently low, [[fainting]] and often [[seizure]]s will occur.
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| Hypotension, depending on one's own body chemistry and genetics, may often cause mild [[depression]], mostly in regard to taking other medications which do not fit one's personal unique needs. | |
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| Low blood pressure is often accompanied by:
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| (Most of these are related to causes rather than effects of hypotension.)
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| * [[Chest pain]]
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| * [[Shortness of breath]]
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| * [[Irregular heartbeat]]
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| * [[Fever]] higher than 101 °F (38.3 °C)
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| * [[Headache]]
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| * Stiff neck
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| * Severe [[upper back pain]]
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| * [[Cough]] with [[phlegm]]
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| * Prolonged [[diarrhea]] or [[vomiting]]
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| * [[Dysphagia|Inability to eat]] or drink
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| * [[Dysuria|Burning with urination]]
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| * Foul-smelling [[urine]]
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| * Adverse effect of [[medications]]
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| * Acute, life-threatening [[allergic reaction]]
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| * [[Dizziness]], or [[light-headedness]], particularly when suddenly standing up from sitting down
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| * [[Seizures]]
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| * [[Loss of consciousness]]
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| * Profound [[fatigue (physical)|fatigue]]
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| === Laboratory Findings ===
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| * [[Complete blood count]] ([[CBC]])
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| * [[Blood urea nitrogen]] ([[BUN]]) / [[creatinine]]
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| * [[Calcium]]
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| * [[Glucose]]
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| * [[Urinalysis]]
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| * [[Blood culture]]
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| * [[Cortisol]] level
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| === Electrocardiogram ===
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| * [[ECG]]
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| === Other Diagnostic Studies ===
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| * [[Swan-Ganz catheterization]]
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| ==Treatment== | | ==Treatment== |
| | | [[Hypotension medical therapy|Medical Therapy]] | [[Hypotension primary prevention|Primary Prevention]] | [[Hypotension secondary prevention|Secondary Prevention]] | [[Hypotension cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Hypotension future or investigational therapies|Future or Investigational Therapies]] |
| The treatment for hypotension depends on its cause. Asymptomatic hypotension in healthy people usually does not require treatment. Severe hypotension needs to be aggressively treated because reduced [[blood]] flow to critical organs including the [[brain]], [[heart]] and [[kidneys]] may cause organ failure and can ultimately lead to [[death]]. Treatment options include [[systemic]] [[vasoconstrictors]] and other drugs.
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| * Increase salt and water intake
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| * [[Caffeine]]
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| * Fluid replacement
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| * Remove harmful/offending medications
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| * Educate patient
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| === Acute Pharmacotherapies ===
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| * [[Fludrocortisone acetate]]
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| * [[Sympathomimetic agent]]s
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| * [[Nonsteriodal anti-inflammatory drug]]s ([[NSAID]]s)
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| * [[Erythropoietin]]
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| * IV [[hydrocortisone]]
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| ==References==
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| {{Reflist|2}}
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| {{Circulatory system pathology}} | | {{Circulatory system pathology}} |
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| [[Category:Intensive care medicine]] | | [[Category:Intensive care medicine]] |
| [[Category: Overview complete]] | | [[Category: Overview complete]] |
| [[Category: Signs and symptoms]] | | [[Category: Signs and Symptoms]] |
| [[Category: Physical examination]] | | [[Category: Physical examination]] |
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