ANESTHESIA and BURNS

Speaker: DR. Rajesh Choudhuri, PGT

Moderator: Dr. Biswajit Sutradhar, Asst. Prof.

DEPARTMENT OF ANAESTHESIOLOGY

AGMC & GBP HOSPITAL, AGARTALA

Introduction• Burns : are tissue injuries resulting from direct contact with

flames, hot liquids, gases, caustic chemicals; electricity; or radiation.• 3rd largest cause of accidental death 50% of adults <45 yr. survive 75% burns.

high risk groups for severe burn injuries:• The very young• The very old• The very careless

Anatomy & Physiology of the Skin • Largest body organ: 15% of body weight ,It is not a passive organ.• Protects underlying tissues from injury• Temperature regulation• Acts as water tight seal, keeping body fluids in• Sensory organ

• Two layers: Epidermis and Dermis

• Epidermis• Outer cells are dead• Act as protection and tight seal

• only the epidermis is capable of true regeneration

Types of Burns•Thermal (heat) burns•Chemical burns•Electrical burns•Inhalational burns

Thermal (heat) burns classification• Superficial Burn/1st Degree Burn:

• Erythema ,pain at burn site , involves only epidermis,absence of blisters , heals within 3 to 6 days• Example – sunburn

• Partial-Thickness Burn/ 2nd Degree Burn:• Entire epidermal layer , part of underlying dermis• Mottled and red, painful, swelling and blisters• Healing in 10 to 21 days• Not enough to interfere with regeneration of the epithelium

Thermal (heat) burns classification• Full-Thickness Burn/ 3rd Degree Burn:

• Destruction of all epidermal and dermal elements• Burn into subcutaneous fat or deeper• Skin is charred and leathery (woody)• Generally not painful (nerve endings are dead)

• Fourth-degree• Full-thickness,Extending into muscle,

tendons or bones.• Black and dry,No pain.• Eschar formation.

Estimation of Burned Area

Electrical Burns1.Burns are caused by heat generated by electrical energy as it passes through the

body.

2. Electrical burns result in internal tissue damage.

3. Cutaneous burns cause muscle and soft tissue damage that may be extensive, particularly in high-voltage electric injuries .

4. The voltage, type of current, contact site, and duration of contact are important to identify.

5. Alternating current is more dangerous than direct current because it is associated with cardiopulmonary arrest, ventricular fibrillation, tetenic muscle contrations, and long bone or vertebral fractures.

6. Subcutaneous (Fourth Degree).

Chemical burn

• Most acids produce a coagulation necrosis by denaturing proteins, forming eschar that limits the penetration of the acid.

• Bases typically produce a more severe injury known as liquefaction necrosis.

• Damage continues until the substance is removed or neutralized

Inhalational injury• Its results from the airway inflammatory response to inhalation of the products of

incomplete combustion and is the leading cause of death (up to 77%) in burn patients .

•Effects of of Acute Smoke Inhalation Injury Impairment of mucociliary function infection Mucus hypersecretionTissue inflammation with tracheobronchiolitis, bronchitis, laryngitis, pneumonitis Epithelial sloughingBiochemical alteration with surfactant inactivation Increases vascular permeability and lung edema BronchiconstrictionInitially large airway obstruction late small and large airways Carbon Monoxide (CO) poising

Signs of Carboxyhaemoglobinaemia

COHb levels Symptoms

0-10% Minimal (normal level in heavy smokers)

10-20% Nausea, headache

20-30% Drowsiness, lethargy

30-40% Confusion, agitation

40 -50% Coma, respiratory depression

>50% Death

Carbon Monoxide (CO) poising treatment• Administration of 100% oxygen will shorten the half-life of COHb

from 4 h in room air to less than 1 h

• Mild poisoning (COHb<20%) --- 100% non-rebreathing mask until level falls <5%

• Moderate poisoning (COHb 20 – 40%) without cardiac or neurologic dysfunction --- monitoring of acid-base status and 100% oxygen until level falls <5%

• Severe poisoning (COHb>40%) or with cardiac or neurologic symptoms--- hyperbaric oxygen therapy

• Admission is required for all with level >25% or with cardiac and neurologic symptoms.

Initial management • History: time, extent and mechanism of burn , age and weight of the patient, brief medical history.

• Airway assessment: may require ET intubation and mechanical ventilation in case of acute inhalational injury, upper airway oedema, chest wall restriction, CO poisoning.

• Breathing: administer 100% humidified oxygen via a non-re breathing mask.

• Circulation: establish two large bore IV cannula and commence fluid resuscitation.

• Assess neurological status.

• Analgesia: IV opiods .

• Formally assess burn area and re-evaluate fluid requirement.

• Monitoring: vital signs, urine output.

• Investigations: ABG, COHb, U & E, FBC, Clotting screen, cross-match, cross-match blood, ECG, CXR.

• Secondary survey to exclude other injuries.

• Burn dressing, IV antibiotics.

Fluid regimen for burn patients• Proceed with regimen if > 15% burns in adults or > 10% in children.

• PARKLAND FORMULA: Requirement in first 24 hours ( ml)= BW ×% Burn ×4 ml. Fluid given as R/L alone, 50 % within first 8 hr, 25% in second 8 hr, 25 % in last 8 hr.

Colloids administered only after first 24 hr, 5 % dextrose is required at 1-2 ml/kg/hr after first 24 hr.

• Brooke formula: 1.5 mL of R/L per kg per % TBSA burn per 24 hours

plus 0.5 mL of colloid per kg per % TBSA burn per 24 hours plus 2,000 mL of 5% dextrose in water per 24 hours Half the calculated fluid deficit is administered during the first 8 hours postburn and the remainder is administered over the next 16 hours.

• Daily maintenance fluid after 24th hour: “ 4-2-1” rule.

Special considerations during resuscitation• Central venous access is usually required with burns > 20% BSA.

• A high index of suspicion for airway burns should be maintained in all cases and prophylactic tracheal intubation is often justified, particularly in children and if inter hospital transfer is required.

• Indication for ICU admission include: potential airway problems, burns involving > 20 % BSA and the presence of other injuries.

• Volume replacement titrated to achieve a urine output of 0.5-1 ml/kg/hr in aduits and 1.0-1.5 ml/ kg/hr in children.

• bladder pressure monitoring ( to detect intra abdominal hypertension ) for all patients with major burns of > 30% BSA.

Challenges in Burn anaesthetic management

Compromised airway.

Pulmonary insufficiency.

Altered mental status.

Associated injuries.

Difficult vascular access.

Rapid blood loss.

Impaired tissue perfusion.

Positioning.

• Edema.

• Dysarhythmias.

• Impaired temperature regulation.

• Altered drug responses.

• Renal insufficiency.

• Immunosuppression.

• Infection/ sepsis.

Anesthetic Management• Preop Meds Provide adequate

analgesia Fluids• Establish Adequate Vascular Access

Consider Invasive Monitoring• Airway Management Consider

Alternatives to Direct LaryngoscopyAwake FOB RSI• 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 increased circulating catecholamines. Induction with Propofol/ Thiopental (if adequate volume resuscitation)Etomidate/ ketamine( if volume depleted)

• Muscle Relaxants Avoid Succinylcholine after 24th postburn and for at least 1 year. Anticipate resistance to nondepolarizing muscle relaxants• Postoperative Anticipate increased

analgesic requirements