Burn wound management, infection control, and inhalation injury

Question 1

What are the zones of injury in a burn wound?

Answer 1

Zone of coagulation

Zone of stasis - edema, where inflammatory mediators are released, may progress.

Zone of hyperaemia - vasodilation

Question 2

What occurs in zone of stasis?

Answer 2

• inflammation
• procoagulation/anti-fibrinolysis

Question 3

What causes conversion of a wound? occurs in zone of stasis

and

What is the difference between conversion and progression

Answer 3

Conversion occurs due to an insult such as

• infection
• hypoperfusion (over resuscitation, underresuscitation)
• edema
• Progression is the timely development of the wound, but cannot be altered, not avoidable
• conversion is the change due to an additional insult and is avoidable.

Question 4

What is your initial management of a burn injury

Answer 4

• ABC (life threatening)
• Escharotomy (limb threatening)
• Hx: mechanism, comorbidities
• PE: inhalational injury / burn depth estimation
• Determination: Severity of injury and need fo rtrasnfer/triage
• Irrigation and debridement of wounds
• burn wound dressing and infection control
• treatment planning: non-op vs op

Question 5

What are 3 principles functions of burn dressings?

Answer 5

• Protective - barrier to microorganisms
• Metabolic - prevents heat evaporation, cold stress
• Comfort - prevents air currents, absorbs secretions

Question 6

List skin substitutes

Answer 6

Temporary

• Biologic: allograft, xenograft, amnion
• Synthetic: Biobrane, trasncyte

Permanent

• Biologic: Autograft, cultured epidermal cell autograft
• Synthetic: Alloderm, Integra

Question 7

What are optimal properties of a skin substitute?

Answer 7

• Protective: against heat/vapor loss, barrier to microrganisms
• Comfort: decrease pain
• non-immunogenic, non-toxic
• able to resist shear forces
• promotes healing and prepares wound bed for autograft (temporary substitutes)

Question 8

What are operative indications for Excision and Grafting

Answer 8

• Full thickness burns { larger than 1cm2 in non-critical areas}
• deep partial burns which would take longer than 2-3wks to heal

Question 9

What are reasons for early E&G?

Answer 9

• improved survival, decrease LOS in hospital
• for hand and foot, less resulting disability

Question 10

How do you reduce intra-operative blood loss?

Answer 10

• Tumescent solution (1:1 000 000 - 1:500 000 epinephrine)
• Topical epinephrine (1:30 000)
• tourniquet
• staged operations (minimize operative time)

Question 11

Describe how you would do escharotimies to all critical areas:

• chest/abdo
• neck
• Upper extremity
• Interossei
• Palm
• Digits/toes
• Leg

Answer 11

In general - beyond the margin of the burn, through to the hypodermis

• chest/abdo
  
  • from clavicle, along anterior axillary line, trasnverse across costal margin
• neck
  
  • from mastoid to sternal notch, along anterior border of SCM
• Upper extremity
  
  • arm in anatomic position
  • medial and lateral arm, anterior to medial epicondyle
• Interossei
  
  • longitudinal incision over 2nd and 4th MC
• Palm
  
  • along palm crease and at wrist cross ulnar to avoid palmar cut br
• Digits/toes
  
  • posterior to mid lateral line on non-tactile surface of each digit
• Leg
  
  • midlateral and midmedial incisioncs

Question 12

What are risk factors for burn wound infection? and which microorganisms are likely to be responsible?

Answer 12

RISK FACTORS

• Large burn
  
  • burn immunosuppression, hypermetabolism/malnutrition, ileus with altered gut permeability, loss of skin barrier, catheterization
• Dessicated wounds
• Pre-burn co-morbidities
• Age >60 or <16

ORGANISMS

• Early (within 24hr) endogenous Gr+
• Late (within 3-7days ) exogenous Gr-
• Delayed burn closure : yeast, fungi, drug resistant bugs

Question 13

How do you diasnoe and treat a burn wound infection

Answer 13

• Dx: quantitative cultures and signs of infection
• Tx
  • prevention: aseptic techqnieu w dressing change
  • debriding dressing

Question 14

How do you treatv pneumonia associated w burn injury/II?

Answer 14

• targeted abx Tx
• chest physio
• coughing
• turning
• pulmonary toileting

Question 15

How do you manage blood stream/catheter infection

Answer 15

• cleanse site and dress with antmicrobial dressing
• avoid line in burn wound
• change line q3-7days if suspected infection (not prophylactic)

Question 16

What is inhalational injury

Answer 16

Def; injury to airway and lungs secondary to thermal energy and inhalation of toxins. MANIFESTS 4-12HRS POST BURN.

3 FACTORS:

• INHALATION OF PRODUCTS OF COMBUSTION
• INHALATION OF CO
• DIRECT THERMAL INJURY TO UADT

Increased mortality by 30-40%

Question 17

Describe pathogenesis of II in each of the airway locations:

• tracheobronchial mucosa
• alveoli
• pulmonary vasculature

Answer 17

• Tracheobronchial mucosa
  
  • vasodilation, increased permeability, edema, trasnudation of fluid into lungs
  • sloughing of mucosa, obstruction
  • decreased ciliary motility
  • PBD3 -> atelectasis and infection
• Alveoli
  
  • decerased surfactant, collapse, pulomnary edema
• Pulmonary vasculature
  
  • vascoconstriciton due to TXA2

Question 18

Describe the products in smoke (combustion products) that are responsible for II in lower tracts

Answer 18

• Ammonia, chloride, sulfur dioxide (furniture/clothing)
• Hydrogen chloride (wall/flooring)
• Cyanide (upholstery, nylon)
• aldehyde, formaldehyde (wall paper, acrylic, cotton)

Question 19

How do you diagnose and treat cyanide poisoning

Answer 19

• Dx: resistant metabolic acidosis, lactate>10, low A-V stauration, high CN level (above 0.1mg/L, >1mg/L lethal)
• symptoms, lethargy, N/V, HA

TREATMENT

• Sodium thiosulphate IV - binds CN and becomes thiocynaide, excreted in urine via osmotic duresis
• Hydroxycobalamin - chelates CN, renal excretion. 2.5G
• Sodium nitrate - Met-Hb former by conversion oxyHb to MetHb which binds CN

Question 20

What are 3 effects of CO, signs and symptoms of CO inhalation, 1/2 life of CO and treatment

Answer 20

3 EFFECTS of CO

• high affinity for Hb than O2, displaces O2 from Hb molecule
• shift Hb-O2 curve to the left reducing O2 offloading at the tissue level
• inhibit p450 cytochrome, preventing aerobic metbaolism and shifting to anaerobic metabolism

Signs and symptoms

• HA, hallucinations, cherry red lips coma
• normal sat on pulse oximetry BUT low SaO2 (hypoxemia) on lab value
• Based on carboxyhemoglobin % (level)
  
  • 0-5: normal
  • 15-20: HA, confusion
  • 25-40: nausea, visual changes
  • 40-60: halluciantion, coma
  • >60: 50% mortality

TREATMENT

• 100% O2 or HBO
  
  • T1/2 of CO: 5-6hr on RA, 45min on 100% O2, 27mins in HBO at 3atm

Question 21

How do you manage a patient with suspected II due to direct thermal damage

Answer 21

• Hx: LOC, enclosed, space, >10mins exposure
• PE: singed ahirs, erythema of airway/oral cavity, sout, stridor, voice hoarseness, conjunctivitis
• Labs
  
  • Carboxyhemoglobin level >10% significant
  • CN level >0.1mg/L significant
  • ABG (PaO2< SaO2)
  • Metabolic acidosis
• Investigations
  
  • Bronchoscopy : edema, erythema of vocal cords, hypopharyn, tracea, ulceration of airway mucosa, sout/char in airway
• TREATMENT
  
  • supportive:
  • Endotracheal intubation for 100% O2
  • no barotrauma (VT ?8cc/kg?)
  • HFOV (rescue for ARDS)
  • Pulmonary Toileting (chest physio, percussion/vibration/therpautic bronch, postural drainage)
  • NAC, nebulized heparin (dissolves casts)
  • aerosolized hypertonic saline (to draw out edema)
  • Other
    
    • change from supine to prone
    • NO (as rescue to vasodilate)
    • no steroids (deleterious)
    • aggresssive treatment of pneumonia

Question 22

How do you diagnose ARDS

Answer 22

• bilateral opacities consistent w pulmonary edema
  
  • but no other etiology to explain (pleural effusion, cardiac failure, fluid overload)
• Impaired oxygenation
  
  • Defined by Hypoxemia (PaO2/FiO2)
  • mild ARDS: PaO2/FiO2 between 200-300mmHg and has PEEP or CPAP on vent
  • moderate ARDS: PaO2/FiO2 between 100-200mmHg and has PEEP >5cm H20
  • severe ARDS: PaO2/FiO2 <100mmHg, less than 200 and has PEEP >5cm H20
• Symptoms begin wihtin 1wk of insult or with new or worsening symptoms within a week

Question 23

What are causes of Hypoxia

Answer 23

• Hypoxemia (low PaO2)
  
  • V/Q mismatch
  • hypoventilation
  • impaired diffusion
  • pulmonary shunt
• Low O2 content in Blod (diffused+bound)
  
  • low Hb content
  • low PaO2
  • CO poisoning
  • Methemoglobenemia
  • rightward shift in HbO2 curve
• Low Cardiac Output
  
  • Arrhtymia, depression
  • high Periphral/pulmonary vascular resistance
  • low coronary perfusion

Question 24

What are options for burn wound dressings and their MOA

Answer 24

• Flamazine (SSD - silver sulfadiazine
  
  • 1% cream silvernitrate + sodium sulfadiazine
  • MOA: inhibits DNA replication, cytochrome 3a/b activation and alters CM. ALso inhibits folic acid
• Silver nitrate
  
  • 0.5% solution of Ag granules
  • MOA: as above - blocks DNA, Cyt 3a/b/CM
• Sulfamylon (mafenide acetate)
  
  • 11% cream, 5% solution
  • MOA: unclear
• Acticoat
  
  • nylon/polyester sheet coated in silver crytals within polyethylene mesh
  • MOA: slow release of Ag ions when wet - as above w DNA/Cyt/CM
• Aquacel Ag
  
  • methycellulose + ionic silver
  • MOA: adheres to wound and separates with healing. same as DNA/cyt 3a/b/CM

Question 25

What is the eschar penetration, spectrum coverage, adv and disadv and S/Es of each of the 5 burn wound dressings?

Answer 25

* Eschar Penetration: **Best \>** intermediate\> _Poor_ * _​_**Sulfamylon \>** SSD\> Acticoat\>aquacel Ag\> _Silver nitrate_ * Spectrum * all broad spectrum * EXCEPT - sulfamylon has no fungal/MRSAactivity * EXCEPT - SSD has reports of resistant pseudomonas and enterobactericeae * Advantages * PAINLESS: Flamazine, Silver nitrate. Others painful * Low frequency of change: acticoat q5d, aquacel q14d * Cartialge penetration - Sulfamylon * Disadvantage * Not for superficial wounds: flamazine, silver nitrate - inhibit fibroblast and keratinocytes * Need clean wound base: Aquacel Ag Side EFFECTS * SSD Systemic effect: leukopenia/neutropenia transient, methemoglobunuria, crystalluria, sulfa allergic rxn * SSD local effect: rash due to sulfa * Silver nitrate: Systemic effect: methemoglobenemia * Silver nitrate local effect: staining * Sulfamylon systemic effect: CA inhibitor - hyperventilation, hyperchloremic metabolic acidosis, osmotic diuresis * Sulfamylon Local: rash

Question 26

Describe the advantages and disadvantages biologic skin substitutes

Answer 26

* Cultured Epithelial autografts * can be placed onto of allograft dermis/integra/trasncyte * risk of hypertrophic scarring/pigment * cultured autologous skin * can be expanded in culture then seeded on HA * Xenograft * no vascularization * decreased evaporative loss, early lysis * Amnion * no vascularization * poor evaporative control, early lysis * Allograft * stimulates angiogenesis, reepitheliazatio and vascularization * suppreses bacterial growth * rjected in 7-14days * Acellular dermal allograft * may be left permanent - lyophilized/glycosylized/acellular, NO REJECTION * need stsg or CEA

Question 27

List 5 options for synthetic skin substittute

Answer 27

* BIObrane * INtegra * Trasncryte * Dermagraft * Apligraf *

Question 28

What is biobrane, indications

Answer 28

Synthetic skin substitute with top laye rof silicone and bottom layer of porcine type 1 collagen and nylon * semipermeable * protects against evaporative losses, reduced pain/dressing changes, impermeable to bacteria INDICATIONS * superficial partial dermal burn * temporary coverage for excised burn * temporary coverage for widely meshed autograft * TEN

Question 29

What is integra and indications

Answer 29

Synthetic skin substitute bilayered with top silisone an dbottom bovine collage matrix qith shark choidrointin 6 sulfate * permanent dermal replacement * gradually replaced over 3-6wks * requires an ultrathin STSG INDICATIONS * FT or deep partial thikness burns * need for reharvesting donor sites * chronic/surgical wounds

Question 30

What is transcyte and indications

Answer 30

* Def; synthetic skin substitute silicone + allogeneic human neonatal fibroblasts and bottom layer porcine collage on nylon * similar to biobrane in terms of mechanism \>removal as burn heals, indications *

Question 31

What is dermagraft

Answer 31

POlyglactic (vicryl)mesh with allogeneic neonatal fibroblasts * permanent dermal template (like interga) * requires overlying ultrathin STSG * take not as good as interga *

Question 32

What is apligraf

Answer 32

Synthetic skin substitute dermal bovine collagen + living neonatal fibroblast and epidermal layer of neonatal keratinocytes Indications - widely meshed autografts to accelrate healing at interstices, chronic venous ulcers, diabetic ulcers