Acute Haemorrhage, Shock and Burns Flashcards
Major Haemorrhage: definitions?
Life-threatening bleeding likely to need transfusion
Loss of one whole blood volume within a 24 hour period (70ml/kg)
50% total blood volume loss within 3 hours
150ml/minute of blood loss
FACTS:
- Patients are typically bleeding and shocked (eg: SBP < 90mmHg and HR > 110)
- Shock factor = HR/SBP (110/90 = 1.22; anything > 1 is abnormal)
What are some sources of bleeding?
“BLOOD ON THE FLOOR AND FOUR MORE”
Street/Scalp and external bleeding
Chest
Abdomen
Long bones (eg: femur)
Pelvis
Retroperitoneum
NB: Think about other sources such as AAA, GI bleeding, haematuria, PV bleeding and pos-op bleeding
Why can vital signs be misleading with regards to recognising bleeding?
Hypotension tends to be a late sign (esp among young patients)
Major haemorrhage can lead to bradycardia = the HR demonstrates a biphasic response to volume loss where initial vasoconstriction and tachycardia followed by what is thought to be a vagally-mediated bradycardia which is potentially reversible
Elderly patients: evidence suggests poor outcomes for elderly trauma patients with SBP < 110mmHg and HR > 90; also medications such as B-blockers can hinder the tachycardic response
[NB: basically elderly patients are less likely to show classic tachycardic signs]
Pregnancy: increased vascularity and cardiac output allows women to compensate for blood loss much better; therefore as much as 35% of blood loss needs to occur just to manifest clinical signs
What are some methods to control bleeding?
TURN OFF THE TAP:
a) External bleeding
- Specific to injuries
- Direct pressure
- Indirect pressure (eg: tourniquets, leg raising)
- Dressings (eg: celox dressings)
b) Internal bleeding
- Splinting
- Damage control laparotomy
- Clamshell thoracotomy
- Retrograde endovascular balloon occlusion of the aorta (REBOA)
c) Non-traumatic bleeding
- AAA = vascular surgery/interventional radiology
- UGIB = endoscopy/interventiona radiology/laparotomy
- LGIB = endoscopy/interventional radiology/laparotomy
- Haematuria = bladder irrigation/cystoscopy/interventional radiology
- Ruptured ectopic pregnancy = laparotomy/scopy
- Obstetric haemorrhage = uretonics, evacuation of products
- Epistaxis = cautery/anterior nasal packing/posterior nasal tamponade
REVERSE COAGULOPATHY:
a) Tranexamic acid (TXA)
- Dose is 1g given via IV route
- Fibrinolytic inhibitor which competitively inhibits plasminogen activation
- s/e of prothrombotic state risking PE/DVT
- TXA reduces death due to PPH in obstetric women the earlier the administration (WOMAN trial)
- TXA reduces the risk of death due to traumatic haemorrhage if given within 3 hours in trauma cases (TRAUMA trial)
- TXA did not prove benefit to patients with GI bleeding and therefor should not be given to GI bleeding patients (HALT-IT trial); perhaps due to fact that it is impossible to determine when the bleeding started
b) Reversals for DOACs
- Andexanet used for apixaban and rivaroxaban
- Praxbind used for dabigatran
[NB: very expensive!!]
c) Prothrombin complex concentrate
- Examples include PCC, Octaplex and Beriplex
- Can be used when specific reversal agents are unavailable or when no specific reversal is approved
d) Vitamin K for warfarin
- Given vitamin K (phytonadione) 1-10mg PO/IV if patient is on warfarin
e) Protamin Sulphate for heparin
- Made from salmon sperm
- However its known to cause allergic reactions in patients with fish allergy
f) Antiplatelets
- No specific reversals, best to just stop the drug (eg: aspirin and clopidogrel)
REPLACING BLOOD VOLUME:
- Replace like with like
- 1:1 ratio of RBC:FFP in major haemorrhage
- Check Hb levels; note that Hb concentrations need time to drop
Permissive hypotension: principles
PRINCIPLES OF PERMISSIVE HYPOTENSION:
- Allow SBP to fall low enough to avoid exsanguination but keep high enough to maintain perfusion
- Goal is to avoid disruption of an unstable clot by higher pressures and worsening of bleeding (“don’t pop the clot”)
- Avoids cyclic over-resuscitation that can lead to re-bleeding and paradoxically exacerbate hypotension despite increased fluid resuscitation and subsequent complications
- Low BP is not the target, it is a compromise pending emergency surgical intervention
- Haemorrhage control is the goal, once this achieved (e.g. haemostasis and surgery) normalisation of haemodynamics is appropriate
Injury to tissue caused by heat, friction, electricity, chemicals and radiation
A burn injury is characterised by a hyper-metabolic response with physiologic, catabolic and immune effects
Zone of coagulation:
- Occurs at the point of maximum damage
Zone of stasis
Zone of hyperaemia
ABCDE and burns
AIRWAY:
- Risk of compromise by generalised oedema as a systemic response from an increasing burn size and depth
- Risk of compromise from localised oedema as a result of direct thermal damage to the airway that can obstruct airflow
- Risk of smoke inhalation
- Signs include: hoarse voice, stridor, respiratory distress, carbonaceous sputum, singed facial/nasal hair, inflamed oropharynx, burnt face etc
BREATHING:
- Direct damage from toxic substances
- CO can quickly accumulate impairing oxygen carrying capacity
- Burnt tissues can cause a significant loss of elasticity in tissue fibres which can further compromise breathing
CIRCULATION:
- Burns > 15% total body surface area (TBSA) and > 10% in children can cause profound circulatory shock due to large fluid losses via tissue damage and from a systemic inflammatory response (therefore anything less than 15% TSBA in adults and 10% in children doesn’t need fluid resuscitation)
- Haemodynamic instability is rarely due to the burn alone and should prompt
DISABILITY and EXPOSURE:
- Note that burns patients are physiologically vulnerable to getting cold so minimise time spend doing secondary survey
Burns: how to estimate %TBSA?
LUND AND BWODER CHARTS:
USING PATIENT’S PALM:
RULE OF 9s:
MERSEY BURNS APP:
[NB: not all the burn area would necessarily be included in the %TBSA calculation]
Classification of burns?
Epidermal burn:
Superficial partial thickness burn:
Deep partial thickness burn:
Full thickness burn:
[NB: in reality, depth is often mixed]
Assessing the depth of a burn is necessary to determine what the patient needs immediately and what fluids might be needed
Burns: first-aid measures
REMOVE:
- Remove loose clothing and jewellery
- Do not remove anything that has melted or is adherent (because you might rip the skin off)
COOL:
- Irrigate and cool thermal burns with running tap water (15 degrees) for 20 minutes
- This can be beneficial for up to 3 hours post-insult
- Irrigate chemicals from skin/eyes immediately with warm running water for at least 15 minutes (might take longer); do not use ice/iced water as this can induce vasoconstriction which can lead to tissue hypoxia
COVER:
- Clean any wounds with normal saline
- Cover any area of skin loss with cling film
- Do not wrap cling film circumferentially around a limb as this can cause a constrictive eschar
- Do not use cling films on the face
- Cover chemical burns with a non-adherent dressing
- Tetanus status should be considered
Burns: measures in the ED
AIRWAY:
- Sit upright
- Involve senior anaesthetics and ENT review to consider intubation
BREATHING:
- High flow oxygen initially (note that peripheral oxygen saturations can be falsely elevated with raised CO levels)
- Discussion with burns centre if chest movements should be restricted
- VBG can test for CO levels
- Escharotomy can be a lifesaving procedure to restrict movement to allow chest expansion
CIRCULATION:
- Early IV/IO access with fluid resuscitation
- Evaluate area of circumferential burns in limbs and constantly re-evaluate
- Note that any deterioration in circulation to a limb might indicate ischaemia or compartment syndrome
- Creatine kinase is a good indicator to assess muscle breakdown
DISABILITY AND EXPOSURE:
- Maintain body temperature by both active and passive warming
ANALGESIA:
- Running under cold water
- Covering with cling film to reduce heat loss and infection
- Simple analgesia such as paracetamol and NSAIDs
- Moderate to strong analgesia such as opioids and ketamine
PARKLAND’S FORMULA:
- Adults with burns > 15% TBSA and children with > 10% TBSA need fluid resuscitation
Electrical burns
Deeper tissue damage might be more significant
Renal failure can occur
ECGs should be done
Under what circumstances should a patient be referred to specialist burn services?
All burns 2% TBSA or more in children or 3% in adults
All circumferential burns
All full-thickness burns
Any burns not healed within 2 weeks
Any burns to hands, feet, face, perineum or genitalia
Any chemical, electrical or friction burns
Cold injuries
Unwell/febrile child with a burn (due to toxic shock syndrome)
Any concerns about healing process
Toxic shock syndrome: clinical presentation?
Pyrexia
Rash
Diarrhoea and vomiting
Malaise
Anorexia
Tachycardia/tachypnoea/hypotension
Following onset of burn injury
