Shock Flashcards
What is stroke volume (SV)?
The amount of blood ejected from the left ventricle with each contraction
What is Cardiac Output (CO)?
The amount of blood ejected from the left ventricle in 1 minute
Stroke Volume X HR = CO
Preload
The amount of blood in the ventricle during diastole, which is prior to systole.
The amount of blood in venous return and refers to filling pressure.
Afterload
Systemic Vascular Resistance (SVR)
Blood volume ejected from the left ventricle during systole along with the peripheral (extremities) resistance experienced at the same time.
SVR also reflects pressure or workload in the heart.
Would an increased SVR increase or decrease cardiac workload?
Increase
Vasopressors with SVR
Vasopressors can increase SVR and cause fingers to fall off.
What can cause an increase in SVR with peripheral resistance?
It could be from an increased blood pressure or from the cold
What does high SVR do?
puts more pressure on the heart and more workload on the heart
Define Shock
A life threatening condition that develops when there is inadequate tissue perfusion to deliver oxygen and nutrients needed to maintain cellular function.
Shock Pathophysiology
Inadequate tissue perfusion results in tissue hypoxia which can lead to organ failure if not treated.
The nurse understands that which of these increase as the delivery of oxygen to the tissues falls below the tissues’ requirements? (Select all that apply.)
A. VO2
B. Oxygen debt
C. SvO2
D. Pa02
E. Preload
A and B
Oxygen delivery
The amount of oxygen delivered to the tissues.
Oxygen consumption (VO2)
Reflects the amount of oxygen extracted from the blood at the tissue level
Oxygen debt
The difference between normal VO2 and VO2 during the low-DO2 state.
Normal SvO2
60-75%
SvO2 value below normal
The tissues are extracting more oxygen than normal
What causes a low SvO2?
A decrease of DO2 which may be a decrease in oxygen, hemoglobin, or cardiac output.
Classifications of shock
Hypovolemic
Cardiogenic
Distributive
Obstructive
Hypovolemic shock
An intravascular content issue resulting from rapid fluid loss resulting in inadequate circulating volume.
Cardiogenic shock
Heart pump issue
Inadequate pumping ability of the heart muscle, most typically a result of acute MI
Distributive shock
Due to massive vasodilation caused by poor vascular tone.
Relative hypovolemia
Warm extremities
Obstructive Shock
Blockage
Caused by a mechanical barrier to ventricular filing or ventricle emptying causing decreased cardiac output.
The nurse understands that which patient is at risk of developing hypovolemic shock?
A. A patient with severe valvular disease
B. A patient receiving spinal anesthesia
C. A patient with severe diarrhea
D. A patient with a large pneumothorax
C
Types of distributive shock
Anaphylactic
Neurogenic
Early septic
Late septic
Neurogenic Shock causes
Brain injury
Spinal injury
Spinal anesthesia
Decreased sympathetic tone
Anaphylactic shock causes
Severe allergic reaction
Septic shock cause
Overwhelming systemic infection
Goal for all shock types
To restore circulating blood volume and increase tissue perfusion
Causes of Hypovolemic shock
Blood loss from:
Hemorrhage (can be postpartum)
Penetrating or blunt trauma
Severe GI bleeds
Penetrating: GSW/knife injuries
Blunt: damage to the liver, trauma to the thoracic cavity, ruptured aorta, long bone/femur fractures.
Severe Vomiting/diarrhea
Extensive burns
Surgery
Stages of shock
Initial
Compensatory
Progressive
Refractory
Causes of obstructive shock
Tension pneumothorax
Cardiac tamponade
Severe vascular disease
Initial stage of shock
Hypoxia
Decrease cardiac output
Subtle
Compensatory stage of shock
Increase in heart rate
Increase in blood pressure
Vasoconstriction
Hyper-dynamic VS due to working hard to keep a semi normal BP
Progressive shock stage
Failure of compensatory mechanisms to maintain BP and fluid volume
Refractory stage of shock
Cell death
Multisystem organ failure
Irreversible
Coma
What are the signs and symptoms of decreased cardiac output?
Weak pulses
Cool extremities
Organs start to have dysfunction
Decreased urine output
What happens in shock
An event occurs causing a shock state
Cells are deprived of oxygen and nutrients
Decrease cellular function resulting in cell death
Body responds through compensatory mechanisms
Most shock types cause decreased blood pressure and and increase in heart rate and respiratory rate
Distributive neurogenic shock causes bradycardia
How does neurogenic shock present?
With bradycardia due to activation of the parasympathetic nervous system
Other causes of hypovolemic shock
Diabetes insipidus
Excessive diuresis, urination
Signs and symptoms of hypovolemic shock
Hypotension, tachycardia, tachypnea, altered/decreased level of consciousness, anxiety/restlessness, decreased urine output, delayed capillary refill, pale/cool/clammy skin, decrease cardiac output, decreased central venous pressure (cvs), increased systemic valvular resistance (SVR)
What is CVP
Central Venous Pressure
Pressure in the right atrium measured with the use of a pulmonary artery catheter
SVR refers to…
Increased pressure in the extremities which put pressure back in the heart and then decreases cardiac output
4 likens of a Pulmonary Artery Catheter
Proximal (CVP)
Distal (pulmonary artery wedge pressure)
Thermistor (measure temp)
Inflator (port used to inflate the balloon within the end of the pulmonary catheter)
Hypovolemic Shock Labs
CBC, HMG/HCT, Lactate and BMP
Occult Blood (GI bleed)
Lactate levels
Increased lactate levels indicates the body is in anaerobic metabolism due to tissue hypoperfusion.
Body is not receiving enough oxygen
Hypovolemic Shock Diagnostics
Labs
CT scan
Endoscopic- EGD and Colonoscopy
Hemodynamic monitoring
Decreased BP
Hypovolemic Shock Nursing interventions
Identify and treat cause
Volume replacement before IV Vasopressors meds
Monitor- VS, oxygenation, labs
Promote venous return- elevate legs 10-12”, head slightly elevated, no transdelenburg positioning
Why does volume replacement come before Vasopressors?
You need to refill the vascular system before “squeezing” it with Vasopressors.
Why is transdelenburg contraindicated?
Increased the workload on the heart
Increased ICP
Increases pressure in the legs
Cardiogenic Shock
Pump issue- inadequate tissue perfusion due to impairment of ventricular contraction
Cardiogenic Shock most often due to
Inadequate systole (contracting)
Usually adequate volume with inadequate ventricular contraction
