Shock Flashcards
What is the definition of shock?
Inadequate organ perfusion and tissue oxygenation due to imbalance between oxygen delivery and tissue demand
What determines tissue perfusion?
Mean arterial pressure
MAP= systemic VR x CO
CO= HR x SV
What are the factors which can affect SV? Why is this important to consider in terms of shock?
Preload= degree of ventricular filling
Contractiltiy
After load- measure of lead against which heart working
SV influxes CO which then affects MAP which determines tissue perfusion
What are the 4 main categories causing shock?
Cardiogenic
Obstructive
Distributive
Hypovolaemic
What is cardiogenic shock and what can cause this kind of shock?
Ventricular pump failure= decreased SV= decreased CO= decreased MAP= decreased tissue perfusion
MI
Acute valve dysfunction
Arrhythmia
What is mechanical/obstructive shock? What can cause this type of shock?
Impaired ventricular filling or obstruction of outflow i.e. factors decreasing SV= decreased CO
PE= blocking pulmonary vessels which leads to increased afterload of the heart
Cardiac tamponade= impairs ventricular filling
What is distributive shock? What can cause this form of shock?
Reduced system VR with normal cardiac function
Sepsis
Anaphylaxis
Spinal trauma
I.e. all cause systemic vasodilation
What is hypovolaemic shock and what causes it?
Loss of circulating volume with normal cardiac function
Trauma GI bleed Pancreatitis= 3rd space fluid loss i.e. fluid moves into interstitial space Burns Diarrhoea
What is 3rd space loss and what kind of shock can this cause?
Too much fluid moves from intravascular space to interstitial space which leads to decreased circulating volume== decreased CO
Hypovolaemic shock
How does reduced tissue perfusion result in cell death?
Decreased perfusion= cell hypoxia
Cell switches to anaerobic metabolism
Lactic acid accumulates which induces a metabolic acidosis
Acidosis causes cell membrane pumps to dysfunction causing influx of sodium and water into cells
Results in Intracellular oedema== cell death
What are the 3 major compensatory mechanisms the body uses to combat shock?
Increase CO
-SNS stimulated= increased HR, SV and systemic VR (vasocontriction)
Redistributing blood
- vasoconstriction
- ADH and renin= decreased urine output
Increased O2 delivary to cells
-SNS stimulates bronchodilation, increased resp and tidal volume
What are key things to examine in patient suspected of shock?
A= airway
B= RR + O2 sats + CX percussion/auscultation/expansion +trachea
-note: abnormal RR can be first sign of problem
C= BP + HR
D= blood sugars + GCS
E= urine output
Peripheral signs:
- cold
- clammy
- mottled skin= sign of hypoperfusion
What are the specific signs for cardiogenic shock?
Raised JVP
Pulmonary oedema
Murmurs
Arrhythmias
What are the specific signs of obstructive shock?
Raised JVP
Muffled heart sounds i.e. in cardiac tamponade when the fluid surrounds the heart
Pulsus paradoxus= fall in px BP of >10mmHg during inspiration
What signs can help to distinguish between septic and anaphylactic causes of distributive shock?
Septic:
- warm peripheries
- pyrexia/hypothermia
Anaphylactic:
- bronchospasm
- angioedema
- rash
What are specific signs of hypovolaemia shock?
Bleeding
Pulsation abdominal mass= AAA
Burns
What are the key investigations for patient suspected of shock? What is the importance of each of these investigations?
FBC
- Hb for bleeding
- WCC= infection
Clotting profile
- if patient bleeding
- deseminated intravascular coagulation can occur in shock
Renal function
Liver functon
Amylase= if pancreatitis suspected
Toxicology= investigates possible overdose
ABG= shows signs of switch anaerobic resp which occurs in hypoperfusion
- metabolic acidosis
- increased lactate
Infection screen i.e. sepsis screen
- blood cultures
- urinalysis
When and why would you use a ECG for a suspected shock patient?
If you suspected cardiogenic shock
MI
PE
Cardiac tamponade= small voltage complexes on ECG
Why is it important to do a CXR in a patient suspected of shock?
Signs of lung infection
Pulmonary oedema
Globular heart in cardiac tamponade
Why is an echo down for suspected shock patients?
Acute valvular regurgitation PE Cardiac tamponade Hypovolaemia Wall defects in MI
What are the different stages of the emergency treatment of shock following the ABCD regimen?
A
- maintain airway
- airway protection if GCS<8
B
- high flow oxygen via 15L non-rebreathe mask
- sit up if risk of pulmonary oedema
C
- large bore IV access x2
- control of haemorrhage
- fluid resuscitation i.e. “replace like for like” (blood/crystalloid/colloids)
- possible vasoconstrictors once intravascular volume optimised
- consider urinary catheterisation
D
- check glucose
- monitor GCS
What are the possible further stages of management once the patient has received emergency treatment?
Regular obs and urine output
Treat the CAUSE
Analgesia
Organ support
