Shock Flashcards
Oxygen delivery is dependent on what 2 factors
- Cardiac Output
- Oxygen Content in blood
Cardiac output is dependent on what 2 things
HR + SV
SV is dependent on what 3 things
Preload
Contractility
Afterload
Oxygen content in blood is dependent on what 2 things
Oxygen saturation
HgB
Define shock
“Widespread abnormal cellular metabolism that occurs when gas exchange with oxygenation and tissue perfusion needs are not met sufficiently to maintain cell function”
Shock affects _____ body systems
all
Shock is an imbalance in ____________ for ___________
Supply and demand
O2 and nutrients
Shock is ___________ leading to decreased tissue perfusion
Circulatory insufficiency
In shock, cells revert to ___________
Anaerobic metabolism
Describe aerobic vs anaerobic metabolism
- Aerobic
* Efficient production of ATP
* ATP (energy) maintains normal cellular metabolic function - Anaerobic
* Inefficient ATP production
* Lactate is by-product metabolic acidosis
* Cellular dysfunction cell death
4 Stages of shock
- Initial
- Compensatory
- Progressive
4, Refractory (irreversible)
Initial stage of shock
- Some anaerobic metabolism; overall metabolism still aerobic
- baseline MAP decreased by <10 mmHg
- No obvious clinical signs of shock
Compensatory stage of shock
- Compensatory mechanisms triggered: SNS, RAAS
- Vital organ function not disrupted
- Reversible! – if cause is treated
Progressive stage of shock
- Compensatory mechanisms ongoing, but not sufficient to perfuse vital organs
- Anaerobic metabolism =
- Rising lactic acid (>2)
- K+ (cell death releasing intracellular products)
- Low pH
- Severe hypotension and hypoxemia ischemia
Refractory stage of shock
- Extensive damage to vital organs; continues despite interventions
- Massive release of toxic metabolites and enzymes > vicious cycle > MODS
- Liver, heart, brain, and kidney functions lost
- Death imminent
Compensated vs Decompensated Shock and what BP changes do we see?
Compensated Shock: Stage 1 and 2 (normal/elevated BP)
Decompensated Shock: Stage 3 and 4 (decreased BP)
Describe the initial systemic compensatory mechanisms that occur with shock and what do we see with our pulse pressure
Compensation = SNS and RAAS systems
- SNS System: Baroreceptors in carotid and aortic bodies activate SNS in response to decreased BP
* Vasoconstriction while blood to vital organs maintained - RAAS System: Kidney’s sense decreased perfusion… activate RAAS
As a result - Narrowing Pulse Pressure:
- Difference between SBP and DBP
- Vasoconstriction (without substantial additional fluids) causes increased DBP, with little change in SBP
How well compensation happens depends on what 4 things?
- Extent of injury
- Age
- General state of health
- Amount of blood/volume loss
Respiratory Compensation that occurs with shock
- Respiratory rate increases to try to bring in more oxygen to send to the tissues, as well as to blow of C02 (to compensate for rising lactic acidosis)
- Smooth muscle relaxation (SNS activation) to increase air flow = increase oxygen exchange = decreased CO2
Renal Compensation that occurs with shock
- Renal hypoperfusion activation of RAAS
- Increase Na+ and water reabsorption (lower urinary output: <30ml/hr) = try increase CO
> Hypoxia to kidneys puts them at risk for AKI/kidney failure
Vascular Compensation that occurs with shock
- Vessel constriction, allowing increased blood flow to vital organs
> Cool, pale skin = Alpha receptors produce peripheral vasoconstriction to shunt blood to more vital organs
> Cap refill >2 seconds
GI Compensation that occurs with shock
- Blood shunted away from splanchnic circulation (GI tract, spleen, liver, pancreas) = Allow more blood flow to more vital organs (i.e. heart, brain lungs)
- Decreased intestinal peristalsis = bowel sounds
Why does diaphoresis occur as compensatory mechanism with shock?
release heat as a by-product of metabolism (high metabolic rate/demand)
What hepatic compensatory mechanisms occur with shock?
increased glycolysis, gluconeogenesis, mobilization of free fatty acids (increase availability of glucose for energy due to increased metabolic rate – patients can be hyperglycemic)
does not help - oxygen problem not glucose
What CNS compensatory mechanisms occur with shock?
- Thirst d/t stimulation of brain in response to decreased blood volume
- Decreased LOC, restlessness, agitation (from cerebral hypoxia) - occurs when autoregulation fails
2 Hallmarks of Progressive Stage of Shock
- Decreased Cellular Perfusion + Altered Capillary Permeability
- Anasarca: full body edema because of vasodilation and increased permeability of vasculature throughout the body
> Fluid leakage affects solid organs and peripheral tissues
> Decrease blood flow to pulmonary capillaries
What respiratory changes are seen as a result of the progressive stage of shock
Fluid moves into alveoli
* Edema
* V/Q Mismatch
* Tachypnea
* Crackles
* Increased work of breathing
* Low Oxygenation
What myocardial changes are seen as a result of the progressive stage of shock?
Myocardial Dysfunction results in (what happens when heart is ischemic… loss of fxns)
* Dysrhythmias
* Ischemia/Infarction
What GI changes are seen as a result of the progressive stage of shock?
Mucosal Barrier of GI system becomes Ischemic (what happens when GI is ischemic… loss of fxns)
* Ulcers
* Bleeding
* Risk for translocation of bacteria
* Decreased ability to absorb nutrients
What hepatic changes are seen as result of the progressive stage of shock?
Liver fails to metabolize drugs and waste (what happens when liver is ischemic… loss of fxns)
* Jaundice
* Elevated enzymes
* Loss of immune function
* Risk for DIC = bleedings
> Increased waste products always lead to increased vasodilation (inflammatory response)
What occurs in the irreversible stage of shock?
- Ischemia and necrosis is profound
- Lost all blood volume to third spaces due to increased permeability and dilation of vessels
Cues of irreversible stage of shock
- Rapid loss of consciousness
- Nonpalpable pulse
- Cold, dusky extremities
- Slow, shallow resps; unmeasurable Sp02
- Profound hypotension
- Bradycardia
- Coagulopathies
- Signs of multiple organs failing (MODS)
- Worsening metabolic acidosis (increasing lactate)