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8/12/2019 AANII_Metzenbacher

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Anesthesia

for

Burns & Thermal Injuries

Brad Metzenbacher

Jeremy Orwin


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Thermal Injury


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Overview

Anatomy & Physiology

Pathophysiology

Pharmacology Anesthetic Technique & Management

Management of Complications


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Anatomy & Physiology


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Anatomy & Physiology of the Skin


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Functions of the Skin

Largest organ of body

Sensory organ

Thermoregulation

Prevents the loss of body fluids

Protective barrier against microorganisms


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Structures of the Airway


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Pathophysiology


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Types of Thermal Injuries

Thermal Flame

Steam

Scald

Electrical

Chemical

Inhalation


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Thermal Injuries

1stDegree

2ndDegree

3rdDegree

4thDegree

Frostbite


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Structure of the Skin


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Classification of Burn Depth

First-Degree

Firstdegree Superficial (sunburn)

Erythema, pain,

absence of blisters Consists of epidermal

damage alone

Heals within 3 to 6days


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Second-Degree

Second-degree Involves:

Entire epidermal layer

Part of underlyingdermis

Mottled and red,painful, swelling andblisters

Healing in 10 to 21days


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Second-Degree

Superficial partial-thickness:

Usually quite painful

Erythemetous with blebs and bullae Even air motion across skin hurts

Deep partial-thickness: Sensation impaired to a variable degree


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Second-Degree


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Third-Degree

Third-degree (Full thickness) Destruction of all epidermal and dermal

elements

Burn into subcutaneous fat or deeper

Skin is charred and leathery (woody)

Pearly-white sheen / waxy

Generally not painful (nerve endings are

dead)


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Third-Degree


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Fourth-Degree

Fourth-degree

Full-thickness

Extending into muscle, tendons orbones

Typically involves appendage

Black and dry No pain


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Electrical Burns

Similar to thermal burns

True extent of the damage is often hidden Entry / exit wound

bestworst conductors = nerve, blood, muscle, skin, tendon, fat, bone

Clinical Findings Hyperkalemia

Acidosis

Myoglobinuria is common Maintain high u/o to avoid renal damage

Peripheral neuropathies or spinal cord deficits Cataract formation

Cardiac dysrhythmias up to 48opost injury


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Chemical Burns

Caused by strong acid or alkaline solution Damage continues until the substance is removed or

neutralized

May take time to take effect & may continue to penetrate 24-

48hrs Full-thickness burns appear superficial

Flush with copious amounts of water

Specific Antidotes;

Hydrofluoric Acid10% Calcium Gluconate Phenolspolyethylene glycol & methylated spirits

Phosphorus1% copper sulfate identifies residual

phosphorus


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Inhalation Burns

Smoke inhalation

Heat inhalation injury

Asphyxiation

Carbon monoxide

(CO) poisoning

Toxic gas inhalation


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Carbon Monoxide Poisoning

CO combines w/ HgbCarboxyhemoglobin (COHb)

200 xs more affinity for Hgb

Direct myocardial depression

S & S Headache, irritibility

Respiratory failure, myocardial ischemia

Seizures, coma, death

Treatment = 100% O2(reduces CO half-life from 4hrs to 40min)

SpO2will read falsely high

ABGs must have co-oximetry to determine true O2saturation


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Frostbite

Local freezing of tissue Ice formation in the extracellular space

Appears waxy / white

Extent of damage may be hidden for days to weeks

Numbness & Pain (upon thawing) Upon thawing

Severe hyperemia, edema, blistering

RBC & Platelet dumping = circulatory stasis /

ischemia (gangrene) Treatment

Rapid re-warming decreases extent of the damage Emersion in warm water


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Stages of Thermal Injuries

1stStageEdema

2ndStageDiuresis


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1stStage: Edema

First 24 hours

Fluid leak: vascular space interstitial

space osmotic pressure

capillary permeability

Vasoactive substances released

interstitial edema and intravascularhypovolemia occurs


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1stStage Cont

Burns >30% BSA cause capillary changes inboth burned and non-burned tissue Burned tissue edema

Direct thermal injury to endothelial cellsand burn tissue osmolarity

Non-burn tissue edema Severe hypoproteinemia

Small wound

Edema greatest 8-12 hrs post injury

Large wound Edema greatest 18-24 hrs post injury


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2ndStage: Diuresis

24-36 hours after burn, fluid and electrolytes begin toremobilize back into intravascular space

Capillary seal reestablishes

Diuresis occurs due to GFR in response to intravascular volume

May see hypernatremia and hypokalemia

Cardiac output may 200-300% normal

O2 consumption


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Impact on Systems

Immune System Alters immune cells ability to function

killing power of neutrophils

Macrophages and lymphocytes do not work well

Hematologic System Destruction of RBCs

Hemoglobinuria

Hgb level viscosity WBC level

Coagulation altered


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Impact on Systems

Cellular Response

tissue oxygen tension

Na and H2O shift into cell intracellular swelling

Possible cell death K+ level intravascularly

O2level

Anaerobic metabolism begins

Lactic acid levels

Metabolic acidosis occurs


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Impact on Systems

Endocrine System

Massive release of catecholamines, glucagon, ACTH,

ADH, Renin, Angiotensin, & Aldosterone

Hyperglycemia

Neurological System

cerebral perfusion

Cerebral edema occurs from Na shifts Carbon monoxide or associated head injury may

cause neuro changes


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Impact on Systems

GI System

Slow peristalsis and possible ileus

HCL acid secretion from stress response

Narcotics for pain management further slowperistalsis

Hepatic System

Decreased hepatic synthesis

Decreased metabolic function


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Impact on Systems

Renal System

RBF & GFR

Activation of RAS

Release of ADH retain water & Na

lose of K, Ca, & Mg

ARF

Acute Tubular Necrosis 2ohemoglobinuria &myoglobinuria d/t hemolysis & tissue necrosis

Maintain high u/o (2ml/kg/hr) w/ fluids / osmotic diuretics


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Impact on Systems

CV System (first 24 hrs) Activation of CNS system and catecholamine release:

Tachycardia

Vasoconstriction

During early phase: Classic S/S of compensated shock

Dramatic decrease in cardiac output

Volume loss and decreased venous return:

preload cardiac filling pressure

CVP and PCWP

After 24hrs = increased blood flow to tissues, HTN


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Impact on Systems

Respiratory System

Upper airway injury

Involves all of airway to level of true vocal cords

Initially due to inflammation from heat of inspired smoke

Exacerbated by accumulation of excess interstitial fluid

Major airway injuries

Involves trachea and bronchi

Parenchymal injury

Involves entire respiratory tract down to,

and including, alveolar membrane

Commonly lethal within first few hours after injury

due to profound bronchospasms and hypoxia


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Impact on Systems

Respiratory System Cont 0-24hrs

Edema

Obstruction

Carbon Monoxide Poisoning

2-5 Days

May develop ARDS

Signs & Symptoms Stridor / Hoarseness / Facial burns / Singed nasal hairs /

Carbonaceous sputum / Impaired level of consciousness

S/S of deteriorating ABGs & increasing respiratory distress


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Estimation of Burned Area


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Rule of 9s

Head and neck9%

Each arm..9%

Each leg..18%

Anterior trunk..18%

Posterior trunk18%

Perineum...1%


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Lund and Browder

Designed

for children

Larger heads

Adjustmentsbased on growth


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Pharmacology


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Induction Medications

Hemodynamics Medication

Stable Propofol / STP

Questionable Ketamine

Unstable Etomidate

Remembermedications may be more potent and have a prolonged effect inthe burn patient.


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Muscle Relaxants

Anectinesafe in the 1st24hrs (afterwhich

hyperkalemia may be a problem up to a

year or the burn is healed)

Non-depolarizersburn patients tend to

be resistant to the effects of non-

depolarizing muscle relaxants May need 2-5 xs the normal dose!!!


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Anesthetic Technique &

Management


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Preoperative Evaluation & Testing

Initial evaluation of the burn patient

Time of the injury*

Type (electrical / chemical), depth, & extent of

burnAirway / pulmonary damage

Age, allergies, medications

Associated trauma

Co-existing medical conditions

Anesthetic history


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Preoperative Testing

Diagnostic Testing

ABG(w/ co-oximetry)acid-base balance

Electrolytesimbalances (hyperkalemia)

Serial Hctongoing blood loss orerythrocyte destruction / volume status

Coagulation Profilerule out a bleedingdiathesis

Urine Myoglobin(electrical injuries orpigmented u/o)

CXR


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Anesthetic Technique & Management

Preop Meds

Provide adequate analgesia

Fluids

Establish Adequate Vascular Access

Consider Invasive Monitoring

Airway Management

Consider Alternatives to Direct Laryngoscopy

Awake FOB


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Ventilation Increased minute ventilation

increased metabolic rate

Fluids & BloodAnticipate rapid, large blood loss

Evaluate coagulation status

Temperature Regulation Increase ambient temperature Warm IV fluids


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Anesthetic Drugs Include opioids

Consider effects of increased circulating

catecholamines Muscle Relaxants

Avoid Anectine

Anticipate resistance to nondepolarizingmuscle relaxants

Postoperative

Anticipate increased analgesic requirements


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Management of

Complications


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General Concerns

Compromised Airway

Hypovolemia

Compromised Vascular Access

Interaction of Anesthetic Agents

Pain


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Thermal Injuries

General Management Stop the burning

Supportive care

Oxygen (intubation) Fluid replacement

Electrolyte management

Escharotomies / Fasciotomies

Wear isolation materials with patient contact

Do NOTinstitute broad spectrum antibiotics


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Inhalation Injury

Supportive Care

Maintain oxygenation

Manage bronchospasms

Fluid replacement

Pulmonary toilet

Intubation / tracheostomy

Low volume, high PEEP


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Fluid Resuscitation

Parkland formula

4cc X weight X % burn

volume in first 8 hours

Second over last 16

hours Brooke formula

2cc X weight X % burn

volume in first 8 hours

Second over last 16

hours

Daily maintenance fluids


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Common Operations

Decompression procedures escharotomies & fasciotomies

Burn excision & skin grafting

Reconstruction operations

Supportive procedures tracheostomy, gastrostomy, vascular access


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Escharotomy

A surgical incision of the eschar and

superficial fascia in order to permit the cut

edges to separate and restore blood flow

to unburned tissue distal to the eschar. Circumferential burns (impede ventilation)

Compartment syndrome (impede perfusion)

Can be performed at the bedside / ED.


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Fasciotomy

The fascia is thin connective tissue covering, orseparating, the muscles and internal organs ofthe body.

Usually done by a surgeon under general orregional anesthesia.

An incision is made in the skin, and a small areaof fascia is removed where it will best relievepressure. Then the incision is closed.


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ReviewAnesthetic Management

Preop Meds Provide adequate analgesia

Fluids

Establish Adequate VascularAccess Consider Invasive Monitoring

Airway Management Consider Alternatives to Direct

Laryngoscopy Awake FOB

Ventilation Increased minute ventilation

increased metabolic rate

Fluids & Blood Anticipate rapid, large blood

loss

Parkland Formula

Temperature Regulation Increase ambient temperature

Warm IV fluids

Anesthetic Drugs Include opioids

Consider effects of increasedcirculating catecholamines

Muscle Relaxants Avoid Anectine

Anticipate resistance tonondepolarizing musclerelaxants

Postoperative Anticipate increased analgesic

requirements


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Case Presentation

30 y/o male coming back to O.R. the day following initial

injury for debridement of 2ndand 3rddegree burns of

chest, arms, and face. HistoryPatient was outdoors lighting barbeque. Coals were not lighting as

anticipated so patient was spraying them with lighter fluid.

Flames flashed back up stream of lighter fluid and in a panic the patient sprayed

himself.

He has been maintaining his own airway, however you notice that he is having

stridor and oxygen saturations have slowly decreased over last 4 hours.

Additional medical history includemild hypertension - for which patient was on

metoprolol 100 mg daily, borderline diabetes, obesity125 kg, daily ETOH

consumption of a 6 pack of beer.


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Case Presentation

Anesthetic considerations

Health concerns

Potential problems

Fluid replacement

Areas burned


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Case Presentation

Anesthetic concerns New respiratory concernhow should we

manage this?

Awake FOB What drugs should we usepotential

problems? No succsconsider Roc/Nimbex at 2-5xs normal

dose

Avoid Desmore irritating to airway

Possibly use TIVA techniquedrugs?


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Case Presentation

Health issues

Fluid replacement

Parkland formula4 mL x 125 kg x 45% burned

22,500 mLs replace 1sthalf over 8 hours, 2ndhalf overnext 16 hours

Comorbidities

Hypertension

Diabetes Etoh consumption


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Questions?


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Questions for quiz

1. What is the percentage of burned area for a 7 y/o with burns on the left side of the body, front and back?A) 34%

B) 43%

C) 29%

D) 51%

2. How much fluid should you give the first 8 hours to a 70 kg person burned over 25% of their body?

A) 3000 mL

B) 4000 mL

C) 7000 mLD) 3500 mL

3. Which relaxant should be avoided 24 hours following burn injury and why?

Succinocholine, severe hyperkalemia

4. What are the four types of burns a patient can receive?

Thermal, Chemical, Electrical, Inhalation

5. What is the major concern with anyone with facial burns?

Damage to airway structures creating a difficult intubation scenario

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