Shock Flashcards
Define shock
severe imbalance between oxygen supply and demand leading to inadequate cellular energy production
(oxygen consumption > delivery)
what are the 4 functional classifications of circulatory shock?
- hypovolemic
- distributive
- obstructive
- cardiogenic
oxygen delivery = CO x ________
arterial content of oxygen
cardiac output is affected by heart rate and stroke volume.
arterial content of oxygen is affected by the oxygen saturation (SaO2) and arterial partial pressure of oxygen (PaO2)
what are the potential consequences of shock?
Na/K ATPase dysfunction
cellular necrosis
acidemia
endothelial dysfunction
activation of inflammatory and coagulation cascades
MODS
death
how does hypovolemia cause shock?
hypovolemia is characterized by decreased intravascular volume, which decreases preload and thus decreases cardiac output which affects oxygen delivery.
what are causes of hypovolemic shock?
- hemorrhage (internal or external)
- severe dehydration (GI, renal)
- 3rd space fluid loss
- severe burns
what is the pathophysiology of distributive shock?
Maldistribution of fluid from changes in the vascular tone and increased vascular permeability –> RELATIVE hypovolemia –> decreased systemic vascular resistance
what are the 4 causes of distributive shock?
- anaphylactic shock (histamine-induced vasodilation)
- septic shock (cytokine-mediated endothelial dysfunction)
- neurogenic shock (umbalanced sympathetic and parasympathetic tones)
- pheochromocytoma or extreme fear (release of catecholamines)
what is the pathophysiology of obstructive shock?
compression of the heart or great vessels that interferes with venous return leading to decreased diastolic filling and preload, and thus decreased cardiac output.
what are some causes of obstructive shock? (5 here)
- GDV
- obstruction of vena cava
- tension pneumothorax
- cardiac tamponade from pericardial effusion
- positive pressure ventilation
what is the pathophysiology of cardiogenic shock?
decrease in forward flow from heart due to “pump failure” which leads to primary decrease in cardiac output.
what are causes of cardiogenic shock?
- systolic failure (DCM)
- diastolic failure (HCM)
- AV valve degeneration or defects (regurg)
- brady or tachy arrythmias
what is the pathophysiology of hypoxic shock?
decreased arterial oxygen content leading to decreased tissue oxygen delivery
what are 3 causes of hypoxic shock?
- severe pulmonary disease
- anemia
- dyshemoglobinemias (smoke inhalation, carbon monoxide, methemoglobinemia)
what is the pathophysiology of metabolic shock?
derranged cellular metabolism leading to inappropriate oxygen tissue use.
what are 2 causes of metabolic shock?
- severe hypoglycemia
- mitochondrial dysfunction
The baroreceptor reflex is one of the body’s compensatory mechanisms during shock. What does this reflex cause to compensate during shock?
increases heart rate
increases contractility
causes peripheral vasoconstriction
The chemoreceptors in the cardioregulatory center of the medulla oblongata and carotid body sense changes in pH, CO2, H+, and O2. What compensatory changes do these chemoreceptors cause in the face of shock?
increase respiratory rate and tidal volume
what compensatory changes does RAAS activation cause in the face of shock?
increase angiotensin II which leads to peripheral vasoconstriction and renal Na absorption
what compensatory changes does ADH cause in the face of shock?
increase angiotensin II which leads to increase renal water reabsorption
T/F: shock is a clinical diagnosis that can be made even if only one perfusion parameter abnormality is present
true
what are the perfusion parameters that we assess in order to determine if a patient is in shock or not?
- heart rate
- pulse quality
- MM color
- CRT
- body temp
- mentation
what is the hallmark of decompensated shock?
hypotension
what is the hallmark of anaphylactic and septic shock?
initial vasodilation instead of vasoconstriction
you will see tachycardia, CRT < 1 second, red-injected mucous membranes, elevated temp, and bounding pulses.
Describe how cats can exhibit different signs of shock than dogs typically would
unpredictable HR changes (bradycardic = shock)
RARELY manifest signs of vasodilation (injected MM, rapid CRT, etc.)
the lungs are their shock organ (GI is dogs shock organ)
typically hypothermic
what are clinical exam findings that clue you into thinking your patient have cardiogenic shock?
heart murmur
respiratory distress
coughing
jugular venous distention
ascites
pleural or pericardial effusion
pulmonary crackles
arrythmias
syncope
what are diagnostics you can run in addition to you examination in order to determine what type of shock your patient is in?
point of care tests that are quick
- PCV/TS
- blood glucose
- lactate
- blood pressure
- ECG
- POCUS
- acid-base and electrolyte panel
once the pt is more stable, then you can perform things like CBC/Chem/UA, chest and abdominal xrays and/or ultrasound, echocardiogram, fluid analysis, cultures, etc.
what is the GENERAL treatment for shock?
the goal is to restore oxygen delivery to the tissues
1. flow by oxygen
2. obtain IV access
3. IV fluid bolus (UNLESS CARDIOGENIC THEN NO FLUIDS)
what fluids are appropriate for patients in shock?
isotonic crystalloid bolus (5-20 mL/kg IV over 10-20 min) and repeat as needed for up to 60-90 mL (cats less)
also could do: hypertonic saline, colloids, whole blood (based on patient and their type of shock)
what are additional treatments that you should perform in patients with obstructive (distributive) shock?
- relieve the pressure –gastric trocarization (GDV), thoracocentesis, pericardiocentesis
what are additional treatments to do in patients with septic shock?
vasopressors (norepinpehrine) and broad spectrum antibiotics
what are are additional treatments to give a patient in anaphylactic shock?
vasopressors (epi)
anti-histamines
How do you treat cardiogenic shock?
- oxygen
- minimize stress
- correct underlying cause (CHF –> diuretics +/- thoracocentesis; systolic dysfunction –> positive inotropes dobutaine or pimobendan; life-threatening arrhythmias –> lidocaine, atropine, vs others)
what is the monitoring protocol for patients being treated for shock?
reassess every 5-10 minutes
once normal perfusion parameters, de-escalate monitoring and therapy.
