Shock Flashcards
Define shock
- Inadequate tissue perfusion
- Leads to anaerobic metabolism (lactic acidosis)
- Eventually, end organ damage/failure
Oxygen delivery is a factor of:
- Lung function
- Hgb concentration
- Cardiac output (preload, afterload, contractility, HR)
What are most cases of shock associated with? What are the exceptions?
- Hypotension
- Exceptions: hypertensive emergencies, CO poisoning (may be normo or hypertensive)
PE to evaluate shock
- Airway
- Breathing (effort, rate, sounds, pulse ox, ABG)
- Circulation (BP, HR, MAP)
- Disability/Neuro status (GCS)
- Exposure (head to toe assessment)
Signs of end organ damage
- Confusion
- Decreased urine output
- CP or ischemic EKG changes
- Diffuse abd pain
- Generalized muscle pain
Define hypovolemic shock
More than 15% loss of intravascular volume causing hypotension that leads to decreased end-organ perfusion
What is the MC cause of shock?
Hypovolemia
Etiology of hypovolemic shock
- Fluid loss (vomiting, diarrhea, 3rd degree burns, DKA urine)
- Hemorrhagic (trauma, GI bleed)
- 3rd spacing (ascites 2/2 cirrhosis, cancer, pancreatitis)
Treatment of hypovolemic shock
- IVF (until MAP over 65)
- Transfusion (preferred if cause is hemorrhagic)
- Vasopressors (initiate if IVF cannot get MAP over 65)
When should vasopressors be avoided in treating hypovolemic shock?
If cause is hemorrhagic
Preferred vasopressor in treating hypovolemic shock
Norepi
What is the preferred volume expander if hypovolemic shock is caused by hemorrhage?
Blood transfusion
Define cardiogenic shock
Decreased cardiac output 2/2 abnormal cardiac function in the setting of NORMAL intravascular volume
Etiology of cardiogenic shock
- MI (50% of cases)
- Arrhythmias (tachy or brady)
- Mechanical (cardiomyopathy, ventricular septum or wall rupture)
Treatments of cardiogenic shock
- Norepi for hypotension
- Dobutamine for wet/cold HF
- Cath lab or CABG for MI
- Intra-aortic balloon pump (temporizing measure)
- Atropine and pacemaker for bradycardia
- Electrical cardioversion for AFib/VFib-tach
Define neurogenic shock
- Hypotension and bradycardia 2/2 sympathetic ganglion chain injury
- Sometimes considered a component of distributive shock (d/t significant vasodilation)
What type of injury MC causes hypotension and bradycardia (i.e. neurogenic shock)?
C-spine injuries
Etiology of neurogenic shock
- Trauma (MC)
- Improper location of regional anesthesia delivery
Key signs of neurogenic shock
- Bradycardia and hypotension in setting of trauma or injection
- Limbs are warm, rest of body is cold
- Neuro symptoms (urine retention, paralysis)
Treatment of neurogenic shock
- ABCDE and spine immobilization
- Treat or avoid hypothermia
- IVF, vasopressors, atropine
- IV steroids
- Neurosurgery/ortho consults
Define obstructive shock
- Decreased CO despite normal cardiac function
- Can be 2/2 obstructive decrease in preload OR increase in ventricle outflow resistance
Etiology of obstructive shock
- Tension PTX
- Pericardial tamponade
- Massive PE
- Aortic stenosis
- Pulm HTN
- Atrial myxoma
- HTN emergency
Treatment of obstructive shock
- Needle decompression for PTX/tamponade
- Thrombolytics/thrombectomy for massive PE
- NO inhalation for pulm HTN
- Valve replacement for AS
- Operative resection for atrial myxoma
- IV anti-HTNs for HTN emergency
Define hypertensive urgency
Asymptomatic severe HTN (SBP over 220 or DBP over 125)
Define hypertensive emergency
Severe HTN with signs of end organ damage (encephalopathy, nephropathy, aortic dissection, pulm edema, MI, etc)
Define malignant/accelerated HTN
Severe HTN involving retinopathy (papilledema)
Etiology of HTN urgency/emergency
- Noncompliance or med withdrawal (clonidine)
- RAS or chronic renal dz progression
- Thyroid storm
- Pheochromocytoma
- Cocaine
- Pregnancy
- CNS (head injury, ICB, CVA)
- Intra/postop
Treatment goal of HTN urgency
Mild BP reduction initially with a focus on long term control
Treatments of HTN urgency and what to monitor for each
- Captopril (30 min onset)
- Labetalol (monitor for bradycardia)
- Clonidine (potential for rebound HTN)
- Nifedipine (unpredictable response)
Treatment goal of HTN emergency (and exceptions to this)
BP reduction of 25% within 1 hour and then to 160/100 within 6 hours
*Exceptions: CVA (maintain SBP 160-165) and ICB (target SBP under 130 or 20% below pt’s baseline)
Treatments of HTN emergency
- Nicardipine IV (caution in CAD)
- Labetalol IV
- Nitro infusion
- Hydralazine IV (mostly for pregnancy related)
- Furosemide
Define distributive shock
Hypotension 2/2 decreased vascular resistance despite NORMAL circulatory volume
Etiology of distributive shock
- Sepsis
- Anaphylaxis
- Intoxication
- Acute adrenal insufficiency
- Neurogenic shock
How can pregnancy cause shock?
- Increases BV and CO due to increased HR and SV
- Decreases systemic resistance
- Net result: 5-10 mmHg decrease in MAP (either WNL or early signs of shock)
When is shock in pregnancy MC?
3rd trimester - when the pathophysiologic factors are most prominent
Explain hypotension in pregnancy
- Pregnancy causes increased BV and CO with decreased systemic resistance
- These changes could be normal OR early signs of shock
Etiology of shock in early pregnancy
Ruptured ectopic pregnancy
Etiology of shock in late pregnancy
- PE
- Amniotic fluid emboli
- Uterine rupture
- Postpartum hemorrhage
- Postpartum cardiomyopathy
- Septic shock
Reasons why intubation of a critically ill person can cause shock
- Vasodilation from induction meds
- Increased vagal tone from hypopharyngeal stimulation
- Decreased RV preload from positive pressure ventilation
Describe central venous catheter
Lengthy catheter passed through a vein to end up in thoracic portion of vena cava or RA of heart
Insertion locations of CVC
- Internal jugular vein
- Subclavian vein
- Femoral vein
Potential complications a/w CVC placement
- Hematoma
- PTX, hemothorax
- Air embolism
- Misguided or kinked catheter
- Wire migration
- Infection
Indications for CVC
- Provide vasopressors or other centrally administered meds
- Measure CVP
- Measure central venous O2 saturation (ScvO2)
- Inadequate peripheral venous access
What does CVP under 5 mmHg suggest?
Hypovolemia
What does CVP over 18 mmHg suggest?
Tamponade
Overload
Pulm HTN
Which site(s) are preferable for measuring ScvO2?
Internal jugular or subclavian
What does ScvO2 under 70% indicate?
Oxygen delivery is inadequate to meet oxygen uptake in the tissues
