Shock Flashcards
What is shock?
An acute clinical syndrome initiated by ineffective perfusion and cellular hypoxia, resulting in severe dysfunction of organs vita to survival
What is hypovolaemic shock?
Reduced intravascular volume
- Haemorrhage
- Burns
- GI losses
- Dehydration
What is cardiogenic shock?
Intrinsic cardiac pump failure
- MI/ischaemia
- Arrhythmia
- Acute valve pathology
What is distributive shock?
Marked vasodilation that causes hypotension and malperfusion
- Systemic inflammatory response syndrome – sepsis, pancreatitis, trauma, burns
- Neurogenic – spinal cord injury
- Anaphylaxis
What is obstructive shock?
Failure of circulatory flow
- Tension pneumothorax
- Pericardiac tamponade
- Pulmonary embolism
What are the clinical manifestations of hypovolaemia?
• Haemodynamic changes
• Narrowing of pulse pressure but maintenance of systolic BP initially
• Effects of circulatory redistribution and signs of organ hypoperfusion:
o Skin
o Oliguria
o Cognitive changes
o Metabolic acidosis
What are the management principles of hypovolaemia?
- Restore tissue perfusion and oxygen delivery to cells as rapidly as possible
- ABC
- Administer O2
- Give IV fluids
- Treat the cause
- Resuscitation begins concurrently or ahead of the diagnostic process
- Aiming to prevent irreversible organ injury and failure
What are the thresholds for a blood transfusion?
Without ACS
- 70 g/L
Patients with ACS
- 80 g/L
What are the targets after transfusion?
Without ACS
- 70-90 g/L
Patients with ACS
- 80-100 g/L
In a non-urgent scenario, how long is a unit of RBCs transfused over?
90-120 minutes
When do you offer platelet transfusions in patients with a platelet count of <30 x 10^9?
WHO grade 2 bleeding
- Haematemesis
- Melaena
- Prolonged epistaxis
When do you offer platelet transfusions in patients with a platelet count of <100 x 10^9?
WHO grades 3+4
– Bleeding at critical sites
What blood samples do you take in a person who is haemorrhaging
o FBC o U+Es o LFTs o Calcium o PT o APTT o Fibrinogen o Crossmatch
What will a patient need for a major haemorrhage?
- Red cells 4 units
- FFP 4 units
- Platelets 1 dose
- Tranexamic acid
- Cryoprecipitate
When do you give cryoprecipitate?
- Severe bledding
AND - Fibrinogen <1.5g/L
What is the universal giver?
O -ve uncrossmatched blood
What do you aim for when managing an ongoing bleed?
o Fibrinogen >1.5g/L o PT ratio <1.5 o APTT ratio <1.5 o Hb 80-100g/L o Platelets >75 x 10^9/L o Lactate <2
When do you give thromboprophylaxis?
When the haemorrhage is under control as the patient is at risk of thrombosis
What is Transfusion associated acute lung injury (TRALI)?
Presents as acute respiratory distress syndrome (ARDS) either during or within 6hrs of transfusion
How can a massive blood transfusion cause hypocalcaemia?
Citrate (a solution which preserves blood products) binds with ionised calcium
How can a massive blood transfusion cause hypothermia?
o RBCs are stored at 4 degrees
o A decrease in temperature shifts the oxygen dissociation curve to the left, reducing tissue oxygen delivery at a time when it should be optimised
How can a massive blood transfusion cause dilutional coagulopathy?
o Packed RBCs do not contain coagulation factors or platelets
o Dilution of body’s own clotting factors
What is an immediate haemolytic reaction?
- Incompatibility between donor’s RBC antigens and recipients causing complement activation and intravascular haemolysis
- The most severe are ABO incompatibility
What is an delayed haemolytic reaction?
- Antibody reaction to minor RBC antigens (Rhesus)
