Burns and Shock Flashcards
What is distributive shock
-Damaged tissue releases permeability factors→ neutrophils release more permeability factors and cytokines
- If large body surface area affected (i.e. 15-20% TBSA burns) → more permeability factors → can diffuse into bloodstream to become systemic
Even areas unaffected by the burn injury have leaky capillaries
-Protein leaks into the interstitial space reducing colloid osmotic pressure → less reabsorption of fluid at venous end
-Volume is not lost, just redistributed within interstitium around body → causes blood volume and then BP to fall leading to shock
Blood becomes hypercoagulable as RBC count is still the same in lower blood volume
What is hypovolaemic shock
- Fluid is lost from exposed tissues and skin via evaporation
- Normally skin is a barrier to help retain fluid
- Loss of fluid can cause hypovolaemia
- Can add to problem of distributive shock in burns injuries
What is cardiogenic shock
- Massive drop in blood volume → reduced venous return → reduced preload → reduced heart contractility
- Cytokines released as part of inflammatory response can also get into the blood and become systemic → some cytokines e.g. TNF-alpha, reduce cardiac contractility
- Cardiac stress leads to cardiogenic shock
What are the examination and observations/trend results for:
- Trauma/bleeding
- Dehydration/poor intake
- Vomiting and diarrhoea
- Sepsis
EXAMINATION | OBS & TRENDS |
Signs of fluid loss
SBP < 100mmHg
Cool peripheries
HR > 90bpm
CRT > 2 secs
RR >20 breaths per min
45 degree leg raise +ve
NEWS = 5 or more
What are examples of volume loss and volume shift?
- Volume loss
- trauma/bleeding
- dehydration/poor intake
- vomiting and diarrhoea
- Volume shift
- sepsis
- anaphylaxis
- neurogenic
What is the Parkland Formula
2 - 4 ml x actual body weight (kg) x %TBSA burned
Used to work out fluid requirements in burn patients.
What type of burn is the Parkland Formula not used for
Doesn’t include epidermal (first degree) burns
How is the fluid given to the patient after calculated with the Parkland Formula
- From the time the burn was sustained, give 1/2 of fluid requirement in first 8 hours
- Give other 1/2 in subsequent 16 hours
- This is fluid given in addition to maintenance fluid
Why is it important to not give too much fluid
- Leaky capillaries means lots of fluid can still get into interstitium leading to excess oedema in tissues
- Increased risk of compartment syndrome → where oedema compresses vessels in muscle compartments, leading to ischaemia within that compartment
- Ultimately it is important to always use end points for patients to tailor their fluid treatment.
What is the rule of nines for TBSA for burns
Pretty much everything is 9%
Each leg is 18%, with front being 9% and back being 9%
Each arm is 9%, with front being 4.5% and back being 4.5%
Front of abdomen is 9%
Front of chest is 9%
Upper back is 9%
Lower back is 9%
Genitals is 1%
How do the resus fluids differ from each other
Different types of fluid distribute differently across intravascular, interstitial and intracellular fluid.
How does Dextrose distribute across the body’s tissues?
Assuming the glucose transporter is passive, glucose is distributed across all fluid compartments until equilibrium is reached
- It aligns with the 1/3 and 2/3 split of fluid across interstitial fluid and intravascular fluid
- This means dextrose is not very good for dehydration as it doesn’t really bulk up blood volume
How does Saline distributed across the body’s tissues?
- Cells have lots of sodium transporters to prevent cell swelling and lysis and cellular dysfunction
- Cells actively pump sodium out if there’s excess
- This means very little of sodium gets into cells and sodium is pumped out with fluid following via osmosis.
- Saline gets split with 3/4 in intersitital fluid and 1/4 intravascularly.
How is Ringers Lactate distributed across body tissues
Increase in intracellular volume
- as it contains Ca and K
so osmolarity is lower than in cells
so a bit of fluid will enter cells
Lactate helps to correct acidosis as it can be used to make bicarbonate
How does saline and Hartmann’s compare in terms of
- Intracellular volume
- Extracellular volume
- Acidosis
- Coagulation
- Fluid balance
Intracellular:
Saline- no increase
Hartmann’s- mild increase
Extracellular- both increase
Saline- Hyperchloremic Metabolic Acidosis
Hartmann’s- lactate corrects acidosis
Saline- associated with HYPOcoagulopathy
Hartmann’s- clumping of RBC if infused alongside blood products
Saline- Unbalanced fluid (high CL-)
Hartmann’s- Balanced fluid (Ca, Cl, K)
What does an epidermal burn mean
Epidermal → only involves the epidermis
What is a superficial partial burn and does this require surgery
Superficial partial thickness burn:
Upper dermis damaged but the vascular plexus and most adnexal structures remain intact
- does not often require surgery
What is a deep partial burn and does this require surgery
Deep partial thickness burn:
Extends into deep dermis affecting vascular plexus but not all of dermis is destroyed. Only deep adnexal structures are intact
- often require surgery to replace skin or remove dead skin
What is a Full thickness burn and does this require surgery
Full thickness burn → has extended through entire thickness of dermis and no dermal tissue remains
What is a Fourth degree burn and does this require
Fourth degree → extends to bone, skin is waxy and completely damaged, loses sensation
After resus, what other aspects of care need to be considered
- Admission to a specialist burns centre?
- Burns require MDT management
- Need to think of size, depth and location of burn
- > 10% TBSA could be enough for burn centres to admit patients as higher percentage suggests more cardiovascular involvement
- Full or deep thickness burns require surgical intervention
- Burns on the face, groin or hands and circumferential burns which could limit function need specialist treatment
- Ongoing fluid resuscitation
- Supportive care
- Tetanus immunisation → patients with burns at high risk due to large exposed wound
- Surgery → required for deeper burns e.g. skin grafts, fasciotomy
- VTE prophylaxis → due to immobility
- Pain and anxiety → managed with analgesic, anaesthetics, psychological support
What are some psychological impacts of major burns ?
- Flashbacks → vividly remembering a past time or incident
- Dissociation → mental process of disconnecting from one’s thoughts, feelings, memories and sense of identity
- Avoidance → maladaptive form of coping in which a person changes their behaviours to avoid thinking about, feeling or doing difficult things
- Insomnia → sleep disorder where trouble falling and/or staying asleep
- Hyperarousal → increased responsiveness to simuli with various physiological and psychological symptoms
- Hypoarousal → decreased responsiveness
What are some examples of psychological support that can be offered
Some support that could be offered includes CBT, psychoanalytic therapy, support networks, pharmacological treatments of insomnia etc.
How does Saline cause Acidosis
- Saline can start to dilute blood bicarbonate significantly which normally buffers blood so have to be careful of acidosis in patients with too much saline intake
What is the most common mechanism of injury requiring admissions and most common cause of major burns
- most common mechanism of injury requiring admissions = scalds
- most common cause of major burns = flame injuries
What is the Baux score
main scoring system used to predict mortality and length of hospitalisation in adult burns injury
What are the risk factors for burns
- worldwide risk factors for burn injury:
- low socioeconomic status
- overcrowding
- cooking with kerosene
- generalised poor health
- poor safety practices
- injuries more common in patients w/pre-existing psychiatric diagnoses, substance use problems and extremes of age
- children = accidental and non-accidental
- older and frail individuals with pre-existing medical conditions can present as collapse
What is the first aid process for a burn
burn should be managed under cool or tepid running water for 20 min even up to 4hrs after injury sustained
Stop burning process, cool burn and cover in non-adherent dressing e.g. clingfilm
rest of patient must be warmed to prevent hypothermia
What are the layers of the skin
5 layers of epidermis
2 layers of dermis
subcutaneous fat
connective tissue
muscle
What are the functions of the epidermis
immune function
barrier to entry
sensation and pain
prevent fluid loss
social and psychological
What are the functions of the dermis
Regulation of temperature
- sweating
- dermal vascular plexus
- piloerection
skin durability and flexibility
What is a first degree burn and how easily treated is it
First degree → epidermal/superficial partial thickness
- has good blood supply + sufficient regenerating epidermal cells
- with proper Rx can heath w/o scarring in 1-2 weeks
What are second and third degree burns and how easily treated are they
Second degree → deep partial thickness
Third degree → full thickness
- deep partial thickness and full thickness have lost dermal vascular plexus and cells to heal
- generally Rx inc. excision and skin grafting
What is a fourth degree burn
burn that affects tissue deeper than dermis, fat and muscle - muscle injury can lead to compartment syndrome and rhabdomyolysis
What factors affect the amount of tissue damage caused from a burn
Can be burn related or patient related:
- burn related factors inc. aetiology, temp, duration of exposure e.g. wet heat causes greater damage than dry heat
- patient related factors inc. skin thickness, age, if first aid was given
What are the three zones of tissue injury for local effects
zone of coagulation = dead tissue as result of direct injury
zone of stasis = hypoperfusion due to vasoconstriction in response to injury, vulnerable to ischaemia, infection and necrosis
zone of hyperaemia = dead tissue prompts release of inflammatory mediators, act locally to cause vasodilation leading to increased vascular permeability and oedema
What is the first aid process for a chemical burn
Same as for the other burns, with an added step:
patient should be removed from exposure and all contaminated clothing removed, irrigate with running water or sterile fluids
- acid 45 mins, alkali 1 hr irrigation
When would you suspect hydrogen cyanide poisoning
If inhalation injury, cardiovascular instability and increasing blood lactate levels not responding to treatment
- specific antidote - hydroxycobalamin - should be given
How many cannulas are necessary for IV fluid resus
2 large bore cannulas are necessary
Why do you need to look for the cause of reduced GCS in burns
- reduced GCS at presentation in major burns not caused by burn itself
- must search for cause and appropriate management, could be
- poisoning by inhaled toxins e.g. CO, hydrogen cyanide
- overdose
- trauma inc. head injury
- medical comorbidities leading to collapse
What is an Escharotomy
Escharotomies are surgical incisions through non-compliant full thickness burn, which restricts ventilation on chest and abdomen or causes sig. reduced perfusion in circumferential burns to limbs
What is needed for an escharotomy
Escharotomies to produce decompression should be performed as soon as needed for ventilation or perfusion
- incision longitudinal from unburned skin to unburned skin if possible, deep enough to reach subcutaneous fat and release eschar
- need anaesthesia, diathermy to keep blood loss minimal, and prophylactic antibiotics
When are fasciotomies most indicated
Involves cutting through subcut tissues and fascial layers around muscle compartments
most commonly indicated in high-voltage electrical burns where tissue necrosis of muscle causes compartment syndrome.
How do you examine corneal damage from a burn
examined with fluorescein stain
How do you asses rhabdomyolysis
Electrical burns
Measure CK level
What are the benefits of early wound excision
shown to decrease blood loss, burn wound sepsis and length of stay
What is the next step in surgical management after the skin has been excised
once burned tissue is excised, wound closure must be achieved to decrease fluid loss, prevent further wound desiccation and infection and reduce hypermetabolism
- temp covering with allograft (skin from organ donors) or synthetic skin subsitutes - permanent with autologous split skin grafts = gold standard for burn wounds
What is a hypermetabolic response
Hyperdynamic circulatory, physiological, catabolic and immune system responses
How does acute hypermetabolic response occur
marked and sustained increase in catecholamines, glucocorticoid, glucagons and dopamine secretion initiate cascade
What are some some examples for what occurs in hypermetabolic response
- massive protein and lipid catabolism
- total body protein loss
- muscle wasting
- peripheral insulin resistance
- increased energy expenditure
- increased body temp
- increased infection risks
- stimulated synthesis of acute phase proteins in liver and intestinal mucosa
