Preoperative care of burn patients
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My talk on burns from the 2013 Updates in Anesthesia Course
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Preoperative care of burn patients
- 1. DEPARTMENT OF SURGERY Preoperative care of the burn patient Amalia Cochran, MD, FACS, FCCM Associate Professor, University of Utah Department of Surgery Burn Center at the University of Utah
- 3. DEPARTMENT OF SURGERY Objectives • At the completion of this talk, learners will be able to: – Recognize unique challenges in burn anesthetic management – Respond to major preoperative considerations in burn patients – Describe special pharmacologic considerations in burn care
- 4. DEPARTMENT OF SURGERY Why anesthesia and burns? • Highly-developed, specialized skill sets – Airway management – Pulmonary care – Fluid and electrolyte management – Vascular access – Pharmacologic support of circulation
- 5. DEPARTMENT OF SURGERY Challenges in Burn Anesthetic Management • Compromised airway • Positioning • Pulmonary • Edema insufficiency • Dysrhythmias • Altered mental status • Impaired temperature • Associated injuries regulation • Difficult vascular • Altered drug access responses • Rapid blood loss • Renal insufficiency • Impaired tissue • Immunosuppression perfusion • Infection/sepsis
- 6. DEPARTMENT OF SURGERY Major Preoperative Considerations
- 8. DEPARTMENT OF SURGERY Burn Depth, Burn Extent, Burn Mechanism BURN CHARACTERISTICS
- 9. DEPARTMENT OF SURGERY First Degree Burns • Only damage is to epidermis • Red, hyperemic • Uncomfortable • DOES NOT COUNT FOR BURN SIZE CALCULATIONS
- 10. DEPARTMENT OF SURGERY Superficial Partial-Thickness Burns • “Superficial 2nd degree” • Epidermis and papillary (superficial) dermis are damaged • Blistering • Moist, pink, blanch with pressure • Quite painful
- 11. DEPARTMENT OF SURGERY Deep Partial-Thickness Burns • “Deep 2 degree” nd • Epidermis, papillary dermis, various depths of reticular dermis • Pink-white, somewhat dry appearance • Less painful, but more slow to heal
- 12. DEPARTMENT OF SURGERY Full-Thickness Burns • “3rd degree” • Extends to subcutaneous tissues • Does not heal spontaneously* • Appear charred with thrombosed vessels • Little or no pain • High infection potential
- 13. DEPARTMENT OF SURGERY Estimating Burn Size
- 14. DEPARTMENT OF SURGERY Flash and Flame burn • 50% of US burns • Flash burns – More superficial – Cover more area – More airway risk • Flame burns – Deeper into dermis – Increased risk of inhalation injury/ CO
- 15. DEPARTMENT OF SURGERY Scald burn • 2nd most common • Mosaic of partial and full thickness • Immersion scalds common in “high risk” groups • Association with NAT in children
- 16. DEPARTMENT OF SURGERY High-Voltage electrical burn • 5-7% of burn admissions • Most common cause of amputations in burns • Arrhythmias • Renal damage • Concomitant trauma • Compartment syndrome
- 17. DEPARTMENT OF SURGERY Chemical burn • 3% of burns; 30% of burn deaths • Denaturation of proteins • Irrigation for 30 minutes to 2 hours – Risk of hypothermia • “Traditional” ABCs • Acid-base imbalance
- 18. DEPARTMENT OF SURGERY AIRWAY CONSIDERATIONS
- 19. DEPARTMENT OF SURGERY Why inhalation injury matters • Independent risk factor for mortality • Increased fluid requirements during resuscitation – Up to 50% higher • Medium-term consequences: – Impaired gas exchange – Pneumonia – ARDS/ SIRS/ MSOF
- 20. DEPARTMENT OF SURGERY Signs and Symptoms- Inhalation Injury • Hoarseness • Wheezing • Lacrimation/ • Stridor Conjunctivitis • Bronchorrhea • Brassy cough • Dyspnea • Carbonaceous • Anxiety sputum • Disorientation • Facial burns • Obtundation/ Coma • Singed nasal hairs
- 21. DEPARTMENT OF SURGERY Initial management • 100% humidified O2 • Determine if the patient’s airway is at risk – Progressive edema? – Smoke inhalation injury? • Intubation is NEVER the wrong answer if concerned about airway safety!
- 22. DEPARTMENT OF SURGERY Airway Obstruction • Result of direct thermal injury • Coupled with edema from resuscitation of large burn • Puts airway at VERY high risk – Can easily be lost if not intubated early
- 23. DEPARTMENT OF SURGERY Smoke Inhalation injury • Gold standard for diagnosis: Fiberopticbroncoscopy • Usually minimal initial physiologic and anatomic manifestations • 3-4 days later- impaired oxygenation, decreased compliance
- 24. DEPARTMENT OF SURGERY Treatment of Inhalation Injury • Tracheal intubation and mechanical ventilation • Aggressive pulmonary toilet • Percussive ventilation • RT protocols to mobilize debris and secretions • Lung protective ventilation strategies
- 25. DEPARTMENT OF SURGERY Carbon monoxide poisoning • Impaired oxygen binding and oxygen carrying capacity – Decreased O2 delivery due to curve shift • Clinical features: Headache, nausea, altered mental status • Pulse oximetry is normal – Requires carboxyhemoglobin level • Best treatment: 100% O2 – Evidence does not support hyperbaric
- 26. DEPARTMENT OF SURGERY Burn Shock RESUSCITATION
- 27. DEPARTMENT OF SURGERY Burn Shock • Complex process of circulatory and microcirculatory dysfunction • Not entirely remedied by fluid resuscitation • Result of tissue damage, hypovolemia, and inflammatory mediators
- 28. DEPARTMENT OF SURGERY Massive edema formation interstitial pressure microvascular permeability capillary hydrostatic pressure intravascular oncotic pressure (relative) interstitial oncotic pressure
- 29. DEPARTMENT OF SURGERY Early CV pathophysiology of burns • Decreased cardiac output • Increased SVR – Secondary impact of tissue/ organ ischemia • Myocardial dysfunction (commonly)
- 30. DEPARTMENT OF SURGERY Who gets formally resuscitated? • Any burn ≥ 10-15% TBSA – 2nd or 3rd degree only • All electrical, chemical, inhalation injuries • All multiple traumas • Extremes of age • When in doubt- start fluid resuscitation
- 31. DEPARTMENT OF SURGERY Factors that increase fluid requirements • Delay to resuscitation • Smoke inhalation injury • High voltage electrical injury • Increased 3rd degree/ full-thickness • Associated soft tissue injuries – Burn/ trauma • Methamphetamines
- 32. DEPARTMENT OF SURGERY Parkland Calculation for Resuscitation 4 mLx Body weight (Kg) x %TBSA = 24 hour fluid requirements with Lactated Ringers 1/2 in the first 8 hours 1/2 over the next 16 hours Adjust according to urine output
- 33. DEPARTMENT OF SURGERY Sample Calculation • 4 mLx 90 kg x 17%= 6120 mL of LR • 3060 mL in 1st 8 hours (383 mL/hr) • 1530 mL for next 16 hours (191 mL/ hr) • Remember- these estimates are a starting point!
- 34. DEPARTMENT OF SURGERY Monitoring Resuscitation • If the patient is not making enough urine, he’s not getting enough fluid! – Increase the fluid rate, usually by 10% – PLEASE don’t give diuretics! • Goals: Adults: 30-50 mL/hr Children: 1 mL/kg/hr Myoglobinuria/hemoglobinuria: Goal is twice normal urine output • If the patient is making excessive urine, LR rate may be reduced
- 35. DEPARTMENT OF SURGERY Metabolic derangements and burns
- 36. DEPARTMENT OF SURGERY Metabolic response to major burn
- 37. DEPARTMENT OF SURGERY CV pathophysiology of hypermetabolism • Chronic inflammatory state • Hyperdynamic circulation • Hypotension • Tachycardia • Decreased SVR • Increased cardiac output
- 38. DEPARTMENT OF SURGERY BURN THERMOREGULATION
- 39. DEPARTMENT OF SURGERY Poikilothermia • Loss of cutaneous vasoconstriction • Evaporative temperature loss • Magnified by ablative effects of general anesthesia
- 40. DEPARTMENT OF SURGERY ALTERATIONS IN DRUG METABOLISM
- 41. DEPARTMENT OF SURGERY Acute/ Resuscitation Phase • Decreased renal and hepatic blood flow => decreased clearance of many agents • Decreased CO => increased alveolar accumulation – May augment inhaled anesthetic agent effects
- 42. DEPARTMENT OF SURGERY Hyperdynamic phase • Increased renal and hepatic blood flow => increased clearance of many agents • Decreased albumin – Increased unbound fraction of acidic or neutral drugs (diazepam) • Increased α-acid glycoprotein – Decreased unbound fraction of basic drugs (propofol)
- 43. DEPARTMENT OF SURGERY Hyperdynamic phase • Increased Vd • May also have losses directly from wounds • ?Impairment of hepatic enzymes – May result in decreased clearance even with increased blood flow
- 44. DEPARTMENT OF SURGERY Summary of drug metabolism • Altered pharmacodynamics and pharmacokinetics – Clearance may be increased or decreased • Use of serum drug levels may be helpful – Antibiotics – Enoxaparin
- 45. DEPARTMENT OF SURGERY Take-home message?
- 46. DEPARTMENT OF SURGERY Burn patients are challenging! • Difficulties in airway management and vascular access • Progression from shock to hypermetabolism during first 48 hours post-injury • Requirement for a full team approach to care
- 47. DEPARTMENT OF SURGERY Thank you!
Notas do Editor
- In first-degree burns, the only damage is to the epidermis. These burns are red and painful, and blanch when pressure is applied to them.If you have ever had a simple sunburn that did not blister, you’ve had a first degree burn.Most importantly, first degree burn is not included in burn size calculations because it does not have a significant physiologic impact.
- Superficial partial-thickness burns are also described as superficial 2nd degree burns.In these injuries, the epidermis and the superficial layers of the dermis are damaged.These burns result in blistering and the blisters are often quite large and filled with lots of fluid.When the blisters are unroofed, or debrided, the underlying tissue is pink and moist and blanches in response to pressure.These burns tend to be quite painful when they are open to air. They typically heal without any difficulty or significant scarring within 10 days to 2 weeks.
- Deep partial-thickness burns are also described as deep 2nd degree burns.In these injuries, the epidermis, the papillary dermis, and various depths of the reticular dermis are damaged.These burns often result in bubbling up of the epidermis, but the blisters rarely contain much fluid.When the detached epidermis is removed, the underlying tissue pink to white and appears somewhat dry, particularly as compared to superficial partial-thickness burns.However, dermal elements like hair follicles are still visible in the wound base.These burns are relatively less painful, certainly less so than superficial burns. Many deep partial-thickness burns heal without skin grafting within three weeks. Those that are left longer than three weeks are at significant risk of hypertrophic scar formation, and grafting is recommended in that patient population because of cosmetic and functional concerns.
- Third degree, or full-thickness, burns extend through the dermis into subcutaneous tissues.Unless they are very small, these burns will not heal spontaneously. Excision and skin grafting is standard in these patients.The initial full-thickness burn wound appears charred with thrombosed vessels beneath the leathery skin that remains in place.These patients have little or no pain in the area of the burn wound, but may have pain proximal to the injury site.These burns have the greatest potential for infection and must be monitored carefully; early excision and grafting helps to minimize this risk.
- The “rule of nines” has traditionally been used to estimate burn size in a quick and relatively easy fashion. It must be remembered that the entire extremity or body area must have a second or third degree injury in order to be designated with the full percentage for that area.Also, it is important to note that infants require different estimation than adult patients do. Their heads are relatively large and their legs relatively smaller, and this impact calculation of their total body surface area involvement.For smaller burns, the patient’s palm, including fingers, can be used to approximate 1% TBSA.
- Many signs and symptoms of smoke inhalation injury have been identified. Unfortunately, many of these are nonspecific. Hoarseness has been shown to be the most specific predictor of presence of inhalation injury.
- Not all patients require formal burn resuscitation with IV fluids.Those who should be resuscitation include those with more than 10-15% total body surface area, or TBSA.All patients with electrical, chemical, and inhalation injury should be formally resuscitated, as should multiple traumas. The very young and the very old benefit from early initiation of fluid therapy when it is needed.Most importantly, if you question the need for formal fluid resuscitation, it should occur.
- Any resuscitation formula is only a starting point. All burn injuries are different and the inflammatory response that affects the patient’s response to resuscitation is highly variable. This table lists features associated with increased volumes of fluid required by burn victims.
- The Parkland formula is the most widely used formula for burn resuscitation, and is calculated as 4 mL times the patient’s weight in kilograms times their 2nd and 3rd degree TBSA injury.This calculation provides the 24 hour fluid requirements with lactated ringers, with half of that amount being administered in the first 8 hours and the remainder over the next 16 hours.It cannot be stressed adequately that the Parkland formula is a starting point for resuscitation and that many patients require more or less fluid than calculated. Patients who are being resuscitated per the Parkland formula should have their IV infusions adjusted according to their urine output.
- This slide provides a typical Lund and Browder diagram and burn size calculation as performed at the University of Utah Burn Center.Patient Smokey the Bear sustained a 17% TBSA 2nd degree injury from a flame burn when he was fighting a forest fire.Since Smokey weighs 90 kg, his fluid calculation per Parkland formula is 6120 mL of LR in the first 24 hours post-injury.He should receive half of that, or 3060 mL, in the first 8 hours; that calculates to a rate of 383 mL per hour.He should receive the other half, or 1530 mL, in the next 16 hours; that calculates to a rate of 191 mL per hour.And, again, it is important to remember that these estimates are a starting point and that the LR infusion should be titrated based upon urine output. I would recommend that Mr. Bear have a Foley catheter placed so that his urine output can be monitored on an hourly basis with his formal resuscitation.
- If your patient isn’t making enough urine, the patient is not getting enough fluid. Oliguria is an indication to increase the fluid rate, not to provide diuretics in an attempt to improve urine output.Target urine output is 30 to 50 mL per hour in adults and 1 mL per Kg per hour in children. If patient has myoglobinuria or hemoglobinuria, as can happen with electrical injuries or crush injuries, their goal is twice the normal target output.In addition, if the patient is making urine in excess of target, their infusion of lactated ringers can be reduced.