ACUTE HAEMORRHAGE Flashcards
Calculate cardiac output?
BP/systemic vascular resistance
HR x stroke volume
What are the 3 main pathophysiologies behind shock?
Cardiogenic - decreased CO e.g. MI, PE, tamponade
Systemic vascular - increased systemic vascular resistance e.g. sepsis, anaphylaxis, spinal shock
Reduced stroke volume caused by fluid loss e.g. haemorrhage, D&V
How can we use the JVP to work out the cause of shock?
If it’s high with bibasal creptiattions and pt is cold = likely carcinogenic
If low with postural hypotension and cold = likely hypovolaemia
If low with a bounding pulse and warm = likely septic
What is the definition of shock clinically?
Persistently low BP systolic <90 (or a reduction in 30mmHg if hypertensive usually) AND altered end-organ function e.g. oliguria or confusion
How does haemorrhage present?
Pallor
Tachycardia
Clammy
Hypotension - this is actually a late sign of shock!
May be obvious source of bleeding
May have cullens sign of gray turner sign
What is cullens sign and what can it indicate?
a physical exam finding of ecchymoses, or bruising, around the umbilicus.
Caused by intrabdominal haemorrhage - most commonly pancreatitis
What is grey turners sign and what can it indicate?
ecchymosis or discoloration of the flank
A sign of intra- or retroperitoneal haemorrhage. Most commonly pancreatitis
Outline the response of the heart rate in shock?
Biphasic response to volume loss - initial vasoconstriction and tachycardia followed by a bradycardia
(This is why absence of tachycardia does not exclude a life threatening haemorrhage)
Examinations you should do if you suspect a haemorrhage?
Inspect pt for obvious sources of bleeding
Assess abdomen and flanks
Do a PR
Assess long bones and pelvis
Class 1 haemorrhage signs?
Blood loss <750ml or <15%
HR <100
Normotensive
RR 14-20
Urine output >30ml/hr
Class 2 haemorrhage signs?
Blood loss 750-1500ml or 15-30%
HR 100-120
Normotensive
RR 20-30
Urine output 20-30ml/hr
Class 3 haemorrhage signs?
Blood loss 1500-2000ml or 30-40%
HR 120-140
Decreased BP
RR 30-40
Urine output 5-20ml/hr
Class 4 haemorrhage signs?
Blood loss >2000ml or >40%
HR >140
Decreased BP
RR >40
Urine output <5ml/hr
Which groups of pt should you have a very low threshold for suspecting life-threatening haemorrhage?
Pregnant
Trauma cases
Recent surgical procedures
GI bleeds
?ruptured AAA
Pt on anticoagulants, who have hypertension or liver failure
What are the common causes of life threatening bleeds?
Scalp and external causes
Abdomen
Pelvis
Chest
Long bones
Retroperitoneal space
What is the “lethal triad” in acute haemorrhage in trauma patients?
Coagulopathy
Hyperthermia
Acidosis
These 3 things are irreversible and have a grave prognosis as the latter 2 both synergistically affect coagulopathy
Outline how each aspect of the lethal triad impact prognosis in acute haemorrhage?
Hypothermia - impairs platelet function and enzymatic function in the clotting cascade
Acidosis - impairs clotting
Coagulopathy - impaired ability of the coagulation system to synthesize blood clots
What can cause hypothermia in trauma patients?
Haemorrhagic shock
TBI
Alcohol intoxication impairing the ability to regulate core temperature
Extremes of age
Prolonged exposure to environment
Those with severe burns
With medical conditions such as diabetes and thyroid disease
What causes acidosis in trauma patient as?
Poor perfusion to tissues causing lactic acidosis - due to anaemia from acute blood loss, peripheral vasoconstriction in response to hypothermia and blood loss etc
Excessive resuscitation using unbalanced Crystalloids solutions can also cause acidosis
A pt may also have respiratory acidosis due to hypoventilation e.g. resp depression narcotic use, TBI, flail chest, COPD
How do we prevent hypothermia in trauma pts?
Limit exposure
Remove wet clothing
Using warming blankets
Use warm fluids and blood products
Keep room warm
How do we prevent acidosis in trauma patients?
Haemostatic resuscitation and limit crstalloid infusions as much as possible!
Monitor and maximise oxygenation to avoid additional respiratory acidosis
Treat causes of hypoventilation to prevent respiratory acidosis
Measure lactate
How do we manage/prevent a coagulopathy in trauma patients?
Limit use of crystalloids or unbalanced blood products which could cause a dilutional coagulopathy
Identify high-risk patients with a baseline coagulopathy due to meds or pre-existing medical conditions
Administer TXA to prevent clot breakdown
Investigtaions for haemorrhage secondary to trauma?
Establish IV access with 2 wide bore cannulas
Bloods - FBC, U&Es, LFTs, Coag study, ABG/VBG, group and save, emergency cross-match
CT angiography
Pan-CT
FAST USS
What is the gold standard investigation for finding the source of a bleed in acute haemorrhage?
CT angiography
When is FAST ultrasound used in trauma cases?
When suspecting trauma that could cause hemoperitoneum and hemopericardium
Good when CT is not possible immediately
What is a group & save?
Determines the patient’s blood group is.e. ABO and RhD and screens the blood for any atypical antibodies
The process takes around 40 minutes and no blood is issued.
What is a crossmatch?
When you physically mix the patient’s blood with the donors blood to check for immune reactions
This process taes about 40 minutes but on top of a G&S which must be done before!
When would you do group & save and when would you do a crossmatch?
Group & save for when blood loss is not anticipated by blood may be required if greater blood loss than anticipated. Usually patients undergoing planned surgeries that may require transfusion, ideally have samples for group and save taken at preadmission clinics.
Cross match is done when blood loss is anticipated
Definition of major haemorrhage?
The loss of 1 blood volume (70ml/kg) in 24 hours
OR
The loss of 50% of the circulating blood within 3 hours
OR
The loss of blood at a rate >150ml/min
Normal blood volume in adults?
70ml/kg
Principles of haemorrhage control?
Involve specialities early on
Control the bleed:
Direct pressure, tourniquet, pelvic binder etc
Reversal of any anticoagyulkants
Give tranexamic acid
Replace lost blood volume:
Replace with 1:1 ratio of units of plasma:red cells
Use the permissive hypotension approach
Avoid the lethal triad of hypothermia - keep pt warm, maximise oxygenation and treat hypoventilation, avoid unbalanced blood products and Crystalloids
What is the permissive hypotension approach?
Maintaining a blood pressure lower than physiologic levels in a patient that has suffered from hemorrhagic blood loss.
Aim for systolic 80-90
This is to maintain adequate vasoconstriction, organ perfusion, and prevent an undesired coagulopathy during initial fluid resuscitation
What is the minimal volume normotensive approach?
A method that looks at the mean arterial pressure and has a target MAP of 65mmHg.
If MAP falls below this then fluids/blood is given and if MAP rises above this the fentanyl can be givento drop the MAP again.
The aim is to prevent major haemorrhage whilst also maintains adequate perfusion
Why do we no longer do the traditional fluid resuscitation with 1-2L of crystalloids fluids in trauma pt with ?acute haemorrhage?
This can cause a dilutional coagulopathy, impaired oxygen delivery due to dilutional anaemia, hypothermia, worsening metabolic acidosis and clot dislodgement. It can also cause further haemorrhage from elevated blood pressure
Why can improper administration of crystalloids cause hyperchloremic metabolic acidosis?
As normal saline has a higher concentration of Cl- than blood
What are packed red cells stored in?
Sodium citrate, an anticoagulant solution, which functions by binding calcium
Whats the threshold for giving packed red cells?
Hb of 70 or 80 in ACS
How fast must packed red cells be transfused?
Must be completed within 4 hours from the time the unit is removed from the blood bank
How much will 1 unit of red cells increase the Hb by?
By 10g/L on average
Whats the target Hb when giving packed red cells?
70-90
80-100 if ACS
What is in fresh frozen plasma?
It contains all of the clotting factors
What is the thawing time for FFP?
20 minutes