Shock & Syncope - Cardio (Clin Med III - Exam #1)

stage 5

which stage of shock: microvascular and organ damage are now irreversible (untreatable)

maintaining central perfusion by temporizing physiologic derangements - maintaining mean arterial pressure (fluids/vasopressors/inotropes) and oxygen saturation

identifying and correcting the underlying cause

what is the management principles for shock?

increase

β1 receptors ___ heart rate, conduction velocity & contractility

vascular smooth muscle

β2 receptors relaxes ___

vasovagal, situational (micturition, defecating, cough...), psychiatric illnesses, medications, exercise, neuralgias, carotid sinus syncope

name some neurocardiogenic causes of syncope

shock

a physiologic state characterized by a significant reduction of systemic tissue perfusion

acute MI (massive)

what is the most common cause of the heart stopping suddenly?

revascularize the coronary arteries to bring blood supply back to the heart - stent placement, bypass surgery

generally, how do you reverse an acute MI?

lactic acid - acidosis,

in anaerobic metabolism, because in shock there is tissue hypoxia, what lab value goes up? what does this lead to?

delivery; consumption

shock is the imbalance between oxygen ___ and oxygen ___

cellular effects

which type of effect - ion pump dysfunction, intracellular edema, etc

systemic effects

which type of effect - serum pH, endothelial dysfunction, inflammatory cascades

t

t/f: shock is initially reversible but rapidly irreversible (cell death -> end organ damage -> multi-system failure -> death)

mean arterial pressure; cardiac output; systemic vascular resistance

tissue perfusion dependent on ___, determined by ___ and ___

cardiac output (CO)

volume of blood pumped by the heart in 1 min; SV (stroke volume) x HR (heart rate)

pre-load, after-load, myocardial contractility

what are some contributors to cardiac output?

f (inadequate)

t/f: a "normal" cardiac output may be adequate for oxygen delivery under stress

systemic vascular resistance (SVR)

resistance to flow that must be overcome to push blood thru the circulatory system.

vessel length, blood viscosity, vessel diameter (R = (length x viscosity) / (diameter)4, vascular smooth muscle tone, vasodilators, vasoconstrictors)

what are some contributors to systemic vascular resistance?

hypovolemic shock

which type of shock: decrease preload due to intravascular volume loss. systemic vascular resistance increases to compensate for low cardiac output.

internal or external bleeding (hemorrhagic shock)

what is hypovolemic shock most commonly caused by?

cardiogenic shock

which type of shock: cardiac pump failure. systemic vascular resistance increases to compensate for low cardiac output.

distributive shock

which type of shock: severely reduced systemic vascular resistance. cardiac output increased to compensate for low systemic vascular resistance.

septic (most common), anaphylactic, neurologic & endocrinologic causes

what is distributive shock caused by?

tachycardia, oliguria, changes in mental status/anxiety, cool/clammy skin, tachypnea (due to metabolic acidosis), hypotension

what are cardinal findings of shock?

tachycardia

increase in heart rate to compensate for decreased systemic vascular resistance or decreased stroke volume. may be absent in patients on beta blockers, etc...

oliguria

shunting of renal blood flow. intravascular volume depletion. orthostatic hypotension. poor skin turgor. dry mucous membranes

changes in mental status/anxiety

agitation/anxiety, confusion/delerium, obtundation /coma

cool, clammy skin

vasoconstriction to redirect blood from periphery to central organs. mottling and cyanosis are late signs. not all patients (distributive because of vasodilation)

tachypnea

anaerobic metabolism due to tissue hypoxia. decreased clearance of lactate. Kussmaul respirations are suggestive.

hypotension

absolute or relative decrease. late finding

anticipation

what is stage 1 of shock?

stage 1

which stage of shock: the disease has started but remains local. regardless, you should already suspect that shock could appear if the underlying disease is left undiagnosed and untreated. You should already be diagnosing and treating the underlying condition. parameters are stable and within normal limits. There is usually enough time to diagnose and treat the underlying condition. This is the best time because here you can prevent shock altogether…!

pre-shock

what is stage 2 of shock?

stage 2

which stage of shock: the disease is now systemic. parameters drift, slip and slide... and start hugging the upper or lower limit of their normal range..., but there is no shock yet! the absence of shock is due to the fact that compensatory mechanisms are at play. if left untreated, our patient is now destined to slide into the next stage. in fact, illness diagnosis and treatment should be fast and aggressive... right now...!.

compensated shock

what is stage 3 of shock?

stage 3

which stage of shock: compensated shock can start with low normal blood pressure. many practitioners fail to recognize the early part of this stage: "he/she does not look right"... and "I don't know what is going on", "and the blood pressure is not too bad”? the proof that a patient is in shock with normal blood pressure is the appearance of metabolic acidosis due to some organ hypoperfusion. the reason for normotension (or even hypertension in some cases) is that blood pressure is maintained initially thanks to marked activation of many compensatory mechanisms (including the sympathetic nervous system). However, because organs suffer from inadequate perfusion, it is already a state of shock.

decompensated shock

what is stage 4 of shock?

stage 4

which stage of shock: now everybody calls this "SHOCK" because hypotension is always present at this stage. normotension can only be restored with intravenous fluid (if indicated) and/or vasopressors. If you have not diagnosed the cause of shock by now, it will be very difficult to treat your patient. the reason? --- organs now suffer MODS/MODFS and acidosis is becoming rapidly more and more severe.

end organ dysfunction

what is stage 5 of shock?

hemorrhage, fluid loss

what are 2 causes of hypovolemic shock?

hemorrhagic hypovolemic shock

trauma, GI Bleed, peripartum hemorrhage, ruptured aneurysm, etc. also reduces oxygen carrying capacity, further worsening shock state.

fluid-loss hypovolemic shock

diarrhea, vomiting, heat stroke, burns, "third-spacing"; Intracellular (2/3 of total body water) Extracellular (1/3 total body water) - interstitial fluid (bathes cells), intravascular fluid (plasma), transcellular fluid ("3rd space") (ex: CSF, ocular fluid, synovial fluid...)

intravascularly dehydrated

patients often ___ as fluid collects in 3rd spaces (ascites, pleural effusions).

cardiogenic

which type of shock: sustained hypotension with inadequate tissue perfusion in spite of adequate left ventricular filling pressure (pre-load)

- Cardiomyopathies (75%) - myocardial infarction, non-ischemic cardiomyopathies - viral myocarditis, takotsubo, cardiotoxicity, myxedema

- Arrhythmias - bradycardia (heart block), tachycardia (atrial or venticular tachycardias)

- Mechanical Abnormalities, valvular defects - Regurg or Stenotic, ventricular septal defects, tumors/myxomas, free wall aneurysm rupture, hypertrophic cardiomyopathy, aortic dissection, endocarditis

- Extracardiac abnormalities (obstructive) - cardiac tamponade, constrictive pericarditis, tension pneumothorax, pulmonary embolism, abdominal compartment syndrome

name some causes of cardiogenic shock

- Septic

- Anaphylaxis

- Neurogenic / Spinal trauma

- Toxic shock syndrome

- Adrenal insufficiency

name some causes of distributive shock

ABG/Lactate, Chem8, CBC, LFTs, coagulation factors, toxicology screen, cultures

name some labs to order if you suspect shock

BP, chest x-ray (check for pulmonary edema), abdominal XR, CT scans?, ECG (LVH, BBB, acute ischemia, pericarditis), echocardiogram, coronary catheterization

name some diagnostic tests if you suspect shock

pulmonary capillary wedge pressure (wedge) (PCWP)

indirect measurement of left atrial pressure

1. replete volume (fluids)

2. enhance systemic vascular resistance (vasopressors)

3. enhance contractility (inotropes)

how do you maintain central perfusion for shock patients?

β1 receptors

the most important adrenergic receptor in heart

norepinephrine

β1 receptors primarily binds ___

arrhythmias

excess stimulation of β1 receptors leads to ___

β2 receptors

some in heart but more in vasculature and similar cardiac effects

epinephrine; norepinephrine

β2 receptors have a higher binding affinity for ___ & less for ___

α receptors

located on arteries

epinephrine; norepinephrine

α receptors constrict with ___ and ___

increase

α receptors ___ blood pressure & flow back to heart

dopamine; norepinephrine

___ or ___ are generally considered the vasopressor of choice in cardiogenic shock

dobutamine

___ can be added to vasopressor if reduced cardiac output as it increases contractility

epinephrine

___ is vasopressor of choice in anaphylactic shock

norepinephrine

___ is vasopressor of choice for persistent hypotension in septic shock

volume repletion - crystalloid and/or colloid solutions, blood products if indicated.

continue as long as the patient remains volume responsive. most commonly determined by clinical response to fluid bolus. newer parameters for volume responsiveness include IVC variation, pulse-pressure variability, etc...

in general, what is the treatment for hypovolemic shock?

crystalloids

normal saline & Ringer's lactate

colloids

stay in intravascular space longer. higher molecular weight that increases plasma oncotoc pressure (albumin, starches, dextrans, gelatins...)

vasopressor treatment; invasive monitoring

in hypovolemic shock, rapid & appropriate restoration of vascular volume decreases need for ___& ___!

reperfusion!

in general, what is the treatment for cardiogenic shock, such as an acute MI/STEMI?

ventricular support - Intra-Aortic Balloon Pump, Left Ventricular Assist, Left Ventricular Assist and Right Ventricular Assist

what are more specific treatment options for cardiogenic shock?

early recognition, fluid resuscitation (large volumes & usually > 2L), early administration of antibiotics, source control (abscess drainage, surgery), vasopressors

what is the treatment for distributive shock, such as sepsis?

stress-dose steroids

what treatment would you use for refractory distributive shock (sepsis)?

presyncope

lightheadedness from impaired blood flow to the brain

syncope

a sudden loss of consciousness with loss of postural tone with spontaneous recovery not requiring cardioversion

vertigo

a sense of imbalance ("room spinning")

ataxia

lack of muscle control during movements

vertigo, ataxia, seizures

mostly a careful H&P to exclude cardiac causes (acute ischemia, aortic stenosis...) or neurologic causes, what would be some neurologic finds be?

symptoms preceding episode, events during unconsciousness, symptoms and time of regaining orientation after episode

a history is critical as most spells of episodic lost of consciousness occur outside medical observation; may need help of witness. what are some answers that you want to know?

vasovagal

what is the most common neurocardiogenic cause of syncope?

neurocardiogenic, decreased cardiac output, orthostatic hypotension, arrhythmias, medications, cardiovascular syncope, neuropsychiatric syncope, unknown

in general, name some causes of syncope

neurocardiogenic syncope

sudden lightheadedness or lost of consciousness as result of autonomic reflexes, more common in younger patients (teens-3rd decade)

parasympathetic; sympathetic; dilation; sinus; AV node; blood pressure

in neurocardiogenic syncope, heightened ___ output from direct stimulation (micturition, defecation...) or as reflex in response to ___ stimulation (seeing blood, abrupt cessation of exercise...) results in arterial ___ & inhibition of ___ and ___ activity→ transient drop in ___

avoid triggers, wear compression stockings, maintain adequate hydration and salt intake, lay down with feet elevated while performing hand exercises may abort episode.

name some general prevention/treatment options for neurocardiogenic syncope

fludrocortisone, paroxetine, midodrine

name some medications that can be used for neurocardiogenic syncope

cerebral hypoperfusion

what happens when orthostatic hypotension occurs in an upright patient?

>20; >10; supine

in orthostatic hypotension, ___ mm Hg drop in systolic BP or ___ mm Hg in diastolic BP upon arising from ___ position.

sleep or meals; from blood loss/hypovolemia, vasodilators, diuretics and adrenergic blocking agents

when is orthostatic hypotension common after? other causes?

elderly, diabetics and others with autonomic neuropathy

what patient populations is orthostatic hypotension commmon?

recheck after patient supine for 5-10 mins

when should you recheck blood pressure in orthostatic hypotension?

adequate salt and water intake, elevate head of bead and rise slowly, avoid hypotensive drugs

what is the treatment for orthostatic hypotension?

bradyarrhythmias, tachyarrhythmias

name some types of arrhythmias

bradyarrhythmias

due to dysfunction in SA node, AV node or purkinje system

beta blockers; calcium channel blcers

sinus brady and sinus arrest may be due to meds, especially ___ and ___ (they cause 1st degree AV block)

tachyarrhythmias

atrial and ventricular arrhythmias

meds that cause blood vessels to stay dilated: vasodilators - nitrates, ACEIs, CCBs, α-blockers, hydralazine; beta blockers, diuretics, psychoactive meds - phenothiazines, anxiolytics, barbiturates; many others - insulin, marijuana, digitalis, ETOH, cocaine

what type of medications cause syncope? examples?

aortic stenosis, acute myocardial infarction, hypertrophic cardiomyopathy, subclavian steal syndrome

name some causes of cardiovascular syncope

subclavian steal syndrome

subclavian artery stenosis→ retrograde blood flow from vertebral artery to one arm→ cerebral hypoperfusion; check BP in both arms (>20mm Hg difference)

neuropsychiatric syncope

type of syncope that usually younger patients with multiple episodes and complaints (ex: dizziness, lightheadedness, numbness, ...)

panic disorder, somatization disorder

name two reasons for neuropsychiatric syncope

hyperventilation

panic disorder that causes syncope is due to ___

somatization disorder

multiple physical symptoms without physical cause, feel symptoms are real & not "created" or "faked."