Hypotension and Shock Flashcards
Hypotension diagnostic criteria
SBP <90
DBP <60
● May not have any symptoms
● May still have signs/symptoms of hypotension with “normal” BP
● Treat the patient, not the number
Hypotension leads to:
- Reduced cardiac output
- Hypovolemia
- Reduced systemic vascular resistance
- Vascular obstruction
Nonpathologic Causes of Hypotension
Cardiovascular Fitness
Pregnancy
Prolonged bed rest
Alcohol
Presentation of Hypotension
Ranges from mild to severe
● Fatigue
● Dizziness
● Lightheadedness
● Headache
● Fading vision (resolves
with lying down)
● Nausea
● Tachycardia
● Syncope
● Confusion
● Pallor
● Diaphoresis
● Shock
● Seizures
Orthostatic Hypotension
A significant drop in blood pressure after rising from a seated or supine position
Normal blood pressure response to standing:
- Blood pools in lower extremities
- ↓ venous return to heart
- ↓ cardiac output and blood pressure
- Triggers ↑ sympathetic and ↓ parasympathetic stimulation
- ↑ sympathetic outflow raises peripheral vascular resistance, venous return,
and cardiac output - Blood pressure normalizes
Orthostatic Hypotension is caused by failure of _____
compensatory mechanisms
Risk Factors for Orthostatic Hypotension
Baroreflex dysfunction (neurogenic)
Volume depletion
Orthostatic Hypotension presentation
● Generalized weakness
● Dizziness/lightheadedness
● Visual blurring or darkening of the visual fields
● Fatigue
● Cognitive slowing
● Leg buckling
● Headache in suboccipital, posterior cervical, and
shoulder region
● Rarely MI or stroke
Orthostatic Hypotension diagnosis
● Detailed medication list, prescription and
nonprescription
● Recent medical history of potential volume loss
○ Vomiting, diarrhea, fluid restriction, fever?
● Medical history of congestive heart failure,
malignancy, diabetes, alcoholism?
● Neurologic history and examination
Taking Orthostatic blood pressure:
Compare blood pressure in supine and standing positions
1. Have the patient lie down for 5 minutes
2. Measure supine blood pressure and heart rate
3. Have the patient stand up
4. Measure standing blood pressure and heart rate at 1 and 3 minutes
Orthostatic Hypotension =
A reduction of 20 mmHg or more in systolic pressure
A reduction of 10 mmHg or more in diastolic pressure
T/F Heart rate should rise to compensate for postural reduction in blood pressure
T
If HR doesn’t increase, suspect ____
neurogenic orthostatic hypotension
Orthostatic Hypotension labs/diagnosis
● Labs (hematocrit, electrolytes, BUN,
creatinine, glucose, ferritin)
● EKG to r/o underlying heart disease
● Continuous BP monitoring (helpful for
immediate orthostatic hypotension)
● Tilt-table testing (helpful for delayed
orthostatic hypotension)
Orthostatic Hypotension treatment
No specific target BP. Goal is to prevent or reduce symptoms.
● Discontinue or reduce exacerbating
medications
● Increase salt and water intake
● Use compression socks and
abdominal binders
Modify daily activities and lifestyle
Lifestyle modifications for Orthostatic Hypotension
● Stand up slowly, in stages
● Avoid Valsalva-like maneuvers
● Avoid overheating (hot weather,
showers, saunas)
● Tense legs and contract abdominal
and buttock muscles while actively
standing
● Cross legs while standing
● Sleep w/ head of bed elevated
30-45 degrees
● Regular exercise to increase
cardiovascular fitness
Pharmacologic therapy for Orthostatic Hypotension
● Fludrocortisone (1st line)
○ Synthetic mineralocorticoid
○ Increase water and sodium
reabsorption
○ Increases intravascular volume
● Sympathomimetic agents
○ midodrine, droxidopa
● Atomoxetine
● 2nd line
○ Combo of medications
○ venlafaxine
○ pyridostigmine
○ erythropoietin
○ NSAIDs
Orthostatic Hypotension complications
● Falls
● Cardiovascular disease
● Congestive heart failure
● Atrial fibrillation
Vasovagal Hypotension
Neural reflex results in self-limited systemic hypotension characterized by bradycardia
and/or peripheral vasodilation/venodilation
Most common cause of syncope
Vasovagal Hypotension
Vasovagal Hypotension presentation
● Common prodrome: Nausea, pallor,
diaphoresis
○ Caused by increased vagal tone
● Lightheadedness
● A feeling of being warm or cold
● Palpitations
● Fatigue after recovery
Vasovagal Hypotension diagnosis
● In most cases, history and symptoms
are enough to establish diagnosis
● Physical exam usually normal
● BUT EVERYBODY GETS AN EKG
What history information do we need about Vasovagal Hypotension?
● Number, frequency, and duration of episodes
● Associated symptoms preceding syncope
● Patient position at the time of syncope
● Triggers or provocative factors
● Associated symptoms following syncope
● Witnessed signs
● Preexisting medical conditions, medications, and
family history
● Symptoms after recovery
Shock = ____
Hypoperfusion
1. Cardiogenic shock
2. Distributive shock
3. Hypovolemic shock
4. Obstructive shock
Shock S/S
● Pt may appear obtunded or
lethargic
● SBP<90
● Tachycardia
● Confusion
● Pallor
● Decreased urinary output
● Weak peripheral pulses
● Cool, moist extremities
● Metabolic acidosis
Shock diagnosis
● CBC, electrolytes, glucose, ABGs, coagulation panel,
lactic acid, type and cross-match, blood cultures, UA
● EKG
● Chest x ray
● Echocardiogram
Shock treatment
● Depends on the cause
● ABCs
● Fluid resuscitation
● Cardiac monitoring
● Monitor urine output
Cardiogenic Shock
● Heart is unable to maintain
adequate cardiac output
● Results in hypotension and
tissue hypoperfusion
Nearly 50% of patients do not survive
_____ most common of cardiogenic shock
Myocardial infarction
Causes of cardiogenic shock
● Refractory arrhythmias
● End-stage cardiomyopathies
○ Ischemic, valvular, hypertrophic,
restrictive, idiopathic
● Acute myocarditis
○ Infectious, toxic, rheumatologic,
idiopathic
● Stress cardiomyopathy
● Endocrine abnormalities
○ Hypothyroidism, pheochromocytoma
● Trauma
Cardiogenic Shock history info
● Chest pain (if ischemic cause)
● Dyspnea
● Orthopnea
● Fatigue
● Malaise
● Low appetite
● Any of the previously
mentioned conditions
Physical exam for Cardiogenic Shock
● Lung crackles (pulmonary edema)
● JVD
● Heart murmur
● Peripheral edema
Cardiogenic Shock labs
● Elevated cardiac enzymes if MI (CPK-MB, troponins)
● Elevated creatinine, ALT, AST if renal/hepatic
hypoperfusion
● Coagulation abnormalities if hepatic congestion or
hypoperfusion
● Anion gap acidosis, ↑Serum lactate, ↑BNP
EKG
● Evidence of old or new infarctions
● Arrhythmias
Echo use in Cardiogenic shock
● Very useful!
● Look for mechanical complications of
infarction
● Ventricle size/function
● Valve function
● Pericardial fluid/tamponade
CXR use in Cardiogenic shock
● Findings may or may not be present
● Cardiomegaly
● Pulmonary congestion
Coronary angiography use in cardiogenic shock
● Immediately if evidence of MI
● Identifies blockage and allows for
treatment planning
Cardiogenic Shock treatment
● Cardiac catheterization w/ revascularization if indicated. DO NOT DELAY
● Vasopressors/inotropes (Examples?)
● Mechanical circulatory support
○ Intra-aortic balloon pump, microaxial pump, ECMO
● Ventricular Assist Device
● Heart transplant
Determine cause first, then target treatment!
Distributive Shock
Reduction in systemic vascular resistance
results in inadequate cardiac output and
tissue hypoperfusion despite normal
circulatory volume.
Causes of Distributive Shock
● Septic shock
● Neurogenic shock
● Anaphylactic shock
● Endocrine shock
Physical exam of Distributive Shock
● Extremities initially warm before becoming cool
● Wide pulse pressure
● Abnormal heart sounds
● Lactic acidosis - septic
● Evidence of CNS injury - neurogenic
Septic shock =
sepsis + fluid unresponsive hypotension + serum lactate level > 2 mmol/L
+ need vasopressors to keep MAP > 65 mm Hg
Most common cause of distributive
shock
Sepsis
Distributive Shock - Septic treatment
● ABCs
● Fluid resuscitation
● Empiric antibiotics
○ Within the first hr
○ After cultures obtained
● Vasopressors
Distributive Shock - Other causes
Neurogenic shock
● Spinal cord injury
● Epidural or spinal anesthetic
Drug and toxin-induced shock
● Drug overdose
● Snake bites
Anaphylactic Shock
● IgE mediated
Endocrine shock
● Adrenal insufficiency
Hypovolemic Shock
Volume is too low!
● Loss of blood
○ Trauma
○ GI bleed
● Loss of fluids/electrolytes
○ Vomiting
○ Diarrhea
○ Other dehydration
Hypovolemic Shock treatment
● Stop the fluid loss
● Replace volume (fluids, blood transfusion)
Obstructive Shock
Pump failure due to
EXTRACARDIAC cause!
● Usually associated with poor
right ventricular output
● Pulmonary embolism,
cardiac tamponade, tension
pneumothorax, severe
vasoconstriction
Treatment of Obstructive Shock
Treatment = Remove the obstruction
Phenylephrine MOA
● Alpha-1 agonist
● Causes vasoconstriction
● Sympathomimetic
Phenylephrine indications
● Hypotension
● Shock
● Priapism
● Post-resuscitation stabilization
● PSVT conversion
● Nasal congestion (not IV form)
Phenylephrine contraindications
● Uncontrolled hypertension
● Ventricular tachycardia
● CAD
● Arrhythmias
● Bradycardia
Phenylephrine adverse effects
● Cardiac arrhythmias
● Severe hypertension
Vasopressin MOA
● Stimulates AVPR1 (V1) and AVPR2 (V2
receptors
● Causes vasoconstriction and antidiuresis
● Also causes smooth muscle contraction
in the GI tract
Vasopressin indications
● Shock (specifically septic and other
vasodilatory shocks)
● Central diabetes insipidus (off label)
Vasopressin pearls
● May cause reversible diabetes
insipidus after tx d/c, monitor
closely
Dobutamine MOA
● Stimulates beta-1 adrenergic receptors
● Chronotropic and inotropic effect
● Some vasodilation
Dobutamine Indications
● Shock (add if vasopressors don’t work)
● Acute decompensated heart failure
● Stress echocardiography
Dobutamine contraindications
● Hypertrophic
cardiomyopathy w/ outflow
obstruction
● HTN
Dopamine MOA
● Stimulates alpha and beta-1 adrenergic
and dopaminergic receptors
● Inotropic and chronotropic effects
● Renal/splanchnic vasodilation (low dose)
● High doses have pressor effects
Dopamine indications
● Hypotension, shock (not 1st line)
● Bradycardia (ACLS)
● Symptomatic AV block
Dopamine BBW
Black Box Warning: If
extravasation occurs, infiltrate
the area with diluted
phentolamine as soon as
possible to prevent necrosis
Epinephrine MOA
● Stimulates alpha and beta adrenergic receptors
● Sympathomimetic
● Cardiac stimulation, relaxation of bronchial
smooth muscle, vasoconstriction
Epinephrine Indications
● Hypotension, shock (septic, anaphylactic
especially)
● Symptomatic bradycardia or AV block (ACLS)
● Cardiac arrest (ACLS)
Epinephrine Contraindications
● No absolute contraindications
in life-threatening situation
Norepinephrine MOA
● Stimulates alpha and beta-1 adrenergic
receptors
● Inotropic effect and vasoconstriction
Norepinephrine indications
● Cardiogenic shock
● Septic and other vasodilatory shocks
● Fluid-resistant hypotension/shock
● Post-cardiac arrest shock
Midodrine MOA
● Stimulates alpha-1 adrenergic receptors
● Increases arteriolar and venous tone
● Raises standing, sitting, and supine
systolic and diastolic blood pressure
Midodrine Indications
● Orthostatic hypotension
● POTS
● Vasovagal syncope
● Prevention of hemodialysis-induced
hypotension
Midodrine adverse effects
● Severe bradycardia
● Visual field defect
● Erythema multiforme
● Severe supine HTN
Midodrine BBW
Black box warning: can cause
marked supine blood pressure
elevation; use in pts whose lives
are considerably impaired
despite standard clinical care…
