Neurogenic Shock Flashcards
- This type of shock leads to the inability of the SNS to stimulate nerve impulses, which causes hemodynamic problems
- This leads to a decr in tissue perfusion where the cells that make up our organs & tissues don’t receive enough oxygen; hence, s/s of shock occur
- Is a type of distributive shock (like anaphylactic & septic), meaning that the vessels that deliver blood flow to the cells have an issue w/distributing that blood flow
- Here, it’s d/t massive vasodilation b/c the SNS has lost the ability to stimulate nerves that control vessel vasomotor tone (this is the ability to regulate the diameter of the vessels)
What can cause neurogenic shock?
- SCI’s located @ the cervical or upper thoracic locations (above T6)
- Rx’s that affect ANS & SNS
- Spinal anesthesia
Neurogenic shock is sometimes referred to as vasogenic shock
Pathophysiology of Neurogenic Shock/Pre-Briefing
- ANS controls the functions we cannot consciously control like our HR, digestion, rate of breathing, pupil response, etc
- Divided into SNS & PSNS
PSNS
- Known as the “rest & digest” system
- Helps us relax by decr our HR & allows us to digest food, among other functions
SNS
- “keep you alive or fight or flight” system
- Incr HR, BP, dilates pupils for better vision, etc
- Therefore, a HUGE role it plays is that it controls VASOMOTOR TONE > this means that the SNS regulates the diameter of our vessels
- It will cause our vessels to constrict or dilate as needed, depending on the signals it receives from the body
☆ PSNS & SNS are always balancing each other out to keep things regulated in our body
! If 1 system is not working (such as w/neurogenic shock… SNS is malfunctioning), the other system will be UNOPPOSED & in a sense take over, which is why many pts w/neurogenic shock have bradycardia
How does the SNS regulate the diameter of our vessels?
- The nerve fibers of the SNS branch out & hang out on the layers of the vessels
- When nerve signals are fired, it will cause the neurotransmitters epi & norepi to be released
- They will cause the vessel to constrict (narrow)
- H/e, if there’s a low lvl of nerve firing or NO firing, these neurotransmitters are NOT released, so the vessel just relaxes, or dilates
! This is the problem w/neurogenic shock → the nerves are not being stimulated, so they’re relaxed (! causes major problems)
Why?
- Dilated vessels affect the BP
- When vasomotor tone is lost, vessel dilation occurs & this lowers SVR, which causes a major decr in BP (hypotension)
- D/t the decr SVR & low BP, blood pooling will occur in the vessels
- This will DECREASE the amt of blood draining back to the heart (remember, there’s no pressure/resistance helping to push it back so it just hangs out away from the heart)
What does this leave the heart to pump?
Hardly anything @ all!
This will cause a DECREASE in tissue perfusion
In addition, this blood pooling will lead to a risk of DVT development & lower the body core temp (hypothermia)
Why hypothermia?
The blood is just sitting in the extremities cooling down & not returning to the core body to be warmed
These pts will have warm/dry extremities but a cold body
Why does this lead to a decr in tissue perfusion?
There’s venous pooling of blood & not much blood will be flowing back to the heart b/c there isn’t any resistance making it go back
This will decr preload (the amt the ventricle stretches @ the end of diastole/filling phase) & afterload (resistance the ventricles must overcome to pump blood out of the heart & is d/t the decr in SVR)
- When CO falls, so does the amt of blood that’s rich in O2 that flows to the cells that make up our tissues & organs
> If cells don’t receive enough O2, they start to die, & the pt starts to experience the classic s/s of shock
Also, hypothermia can occur d/t the body’s inability to regulate the body temp b/c of ____ dysfunction
This is further complicated by the peripheral vasodilation & pooling of blood in the extremities
hypothalamus
This will lead to heat loss b/c the blood isn’t returning back to the body to keep it warm (! extremities warm & dry BUT body cold) [poikilothermic - loses ability to regulate core body temp]
____ will occur too
HR is controlled by both the SNS & PSNS
Bradycardia
____ incr the HR & ____ works to decr the HR
SNS, PSNS
Therefore, they’re both balancing out the HR
If we lose the function of the SNS, the PSNS will be unopposed & bradycardia will occur
hypotension, bradycardia, hypothermia, warm/dry extremities but cold body
These s/s are slightly diff than the other types of shock, esp in the early stages of shock
Why?
Remember, during the early stages of shock in the other types of shock, the SNS kicks into gear to help “save” the body by causing vasoconstriction w/the release of norepi & epi
> This would incr the HR, BP (in hopes of incr CO), etc
H/e, in neurogenic shock, this doesn’t occur b/c the body has lost the ability to stimulate the SNS d/t this injury
! Neurogenic shock is diff from spinal shock b/c it causes hemodynamic changes w/hypotension & bradycardia r/t its injury
> Whereas spinal shock causes changes w/sensation, motor, & reflexes
Neurogenic Shock: Nursing Interventions & Treatments
Goal: manage pt ABCS (Airway, Breathing, Circulation, Spine)
★ Protect the spine: keep it immobilized (don’t want to cause any more damage and decr perfusion to the spine)
> e.g., cervical collar, log-rolling pt during transport, using a backboard
★ Maintain tissue perfusion: want MAP to be 85-90 mmHg; this helps maintain perfusion to organs, spec the spine
How?
✓ IV fluids: ____
Fills the dilated vessels, incr venous return of the heart which will incr cardiac preload & CO
crystalloids
- IVFs are used w/caution b/c the pt usually has a normal blood vol; therefore, monitor for fluid overload
e.g., dyspnea, crackles, swelling, incr CVP or PAWP
- If no response w/IVFs, then vasopressors may be used
✓ Vasopressors
Cause vasoconstriction (narrowing of vessels) which will incr SVR & incr BP & CO
Positive inotropes: ____ (vasoconstriction & incr HR)
dopamine
Bradycardia? ____
> blocks the parasympathetic effects on the heart
> if severe, the pt may need temp pacing
Atropine
- Rewarming devices for hypothermia: slowing w/rewarming & monitor body core temp
- Foley (some pts lose bladder function)… want u/o 30 cc/hr or higher… this tells us how well the kidneys are being perfused
- Prevent DVT (blood is pooling) - apply compression stockings, ROM exercises, anticoag’s per MD order
- Avoid crossing pt legs or placing pillow under pt’s knees b/c this further compromises circulation
