Inhalation injury and burn resuscitation

• Burns to the airway can swell silently and close it hours after the injury; if the airway is going to be lost, secure it early. ^{[4] [8]}
• Carbon monoxide and cyanide travel with the smoke and are the usual killers in an enclosed-space fire, so every fire victim needs oxygen and a systematic screen. ^{[4] [7]}
• Large burns leak enough fluid in the first day to cause hypovolaemic shock; replace it with a calculated crystalloid infusion titrated to urine output. ^{[5] [6]}
• Chemical and electrical burns look small on the skin yet injure deep structures; they all go to a burn centre. ^{[1] [6]}
• Escharotomy and specialist transfer are time-critical when a circumferential burn stops a limb or the chest from moving. ^{[6] [8]}

By the end of this page you should be able to:

1. Explain how an inhalation injury develops and list the clinical and objective clues that predict airway compromise. ^{[3] [4]}
2. Identify carbon monoxide and cyanide poisoning, state what each does and how each is treated. ^{[4] [7]}
3. Assess burn size and depth, and give the indications for burn centre referral. ^{[1] [8]}
4. Calculate and monitor fluid resuscitation with the Parkland and modified Brooke approaches, naming where guidelines disagree. ^{[2] [5]}
5. Recognise chemical and electrical burns, avoid their specific traps, and manage rhabdomyolysis and cardiac risk. ^{[6] [8]}
6. Describe when escharotomy is needed and how transfer is organised. ^{[6] [8]}

Thermal burns are the most common cause of burn injury and they dominate the emergency care picture. Burns are also classified by mechanism as thermal, chemical, electrical or radiation injuries, and by depth as superficial, superficial partial thickness, deep partial thickness and full thickness. ^[8] Only the deeper, partial and full thickness burns count toward the percentage of the body surface that needs fluid resuscitation. ^[6]

Inhalation injury is often stated as a diagnosis of suspicion rather than of proof. It may be present with minimal skin burns, particularly after an explosion or a fire in a closed space. ^{[3] [4]}

Burns are common worldwide. The World Health Organization estimates that about 163,000 people died in 2023 from exposure to fire, heat and hot substances, with roughly 52,100 deaths in the African region and 56,300 in South-East Asia, together about two thirds of the global total. ^[9] About 35,600 of those deaths were in children under 15 years, about 22% of the total. ^[9]

Inhalation injury doubles the risk of death from a major burn. An international expert panel put its prevalence at about 19.8% of hospitalised burn patients, with an associated overall mortality near 10.9%. ^[4] That same group improved on a classic finding of Shirani and colleagues: the presence of inhalation injury can raise the expected mortality of a major burn by roughly 20%, and by much more if pneumonia follows. ^[4]

In an enclosed-space fire, hidden poisoning is the rule rather than the exception. One educational simulation of house-fire patients reports that about 35% of fire victims have toxic levels of cyanide on arrival in the emergency department. ^[7] Carbon monoxide is equally common, though its carboxyhaemoglobin level often falls while the patient breathes air or oxygen before arrival. ^[6]

Thermal burns usually come from flames, hot liquids (scalds), steam or contact with hot solids. Scalds from hot drinks and hot water cause most childhood burns. Flame burns dominate in adults, particularly where households cook or heat with open fires. ^[9]

Inhalation injury arises when a fire burns in an enclosed or poorly ventilated space, because the victim breathes smoke and heat for long enough. Risk rises with loss of consciousness, confinement, an explosion or a fire involving synthetic materials. ^{[8] [4]} Accelerants increase danger because hot gases reach deeper into the lung. ^[4]

A burn centre should be consulted early. The American Burn Association places all chemical burns and all high-voltage (1,000 V or more) electrical burns, including lightning, in the immediately transfer group; low-voltage electrical burns also deserve consultation and follow-up for delayed problems. ^{[1] [6]}

Smoke damages the airway in layers and over time.

• Heat injures the upper airway. The glottis protects the lungs from direct thermal damage, so the lower airway is burned by steam or scalding liquid, not by dry heat. ^{[4] [6]}
• Chemicals in smoke (irritant acids, acrolein, nitrogen oxides) inflame and slough the bronchial mucosa, produce oedema and lead to sloughed mucous casts that block small airways. ^{[4] [6]}
• Particles carry heat and chemicals deep into the lung and stimulate reflex bronchospasm. ^[6]
• Systemic toxins, carbon monoxide and cyanide, do not need burns to be deadly: both act at the cellular level. ^{[6] [7]}

The upper airway can look nearly normal on arrival and then obstruct hours later as oedema develops. Fluid given to resuscitate a large burn further worsens that oedema. That is why a burn to the face or an enclosed-space fire, followed by a rapidly rising fluid requirement, pushes clinicians toward early intubation. ^{[3] [4]}

Take the story of the fire as carefully as the story of chest pain.

• Was the fire indoors, in a small space, or did the patient lose consciousness before rescue? ^[8]
• Were synthetic furnishings, plastics, textiles or electrical equipment involved (a source of hydrogen cyanide)? ^{[4] [7]}
• Is there facial burn, singed scalp or nasal hair, or soot in the nose or mouth? ^{[3] [8]}
• Is the voice hoarse, or is there cough with black sputum? ^{[3] [8]}
• Is there dyspnoea, stridor or use of accessory muscles? ^[8]

Look for the following upper airway and lower airway signs. ^{[3] [8]}

• Facial, scalp and neck burns, singed eyebrows or nasal hair.
• Soot, blisters or erythema in the mouth, nose and pharynx.
• Hoarseness, stridor, cough, wheeze, carbonaceous sputum.
• Altered consciousness or a GCS below normal.
• Chest-wall restriction from a circumferential burn of the trunk.

The decision to intubate must balance a secure airway against the harm of unnecessary ventilation. Airway obstruction and loss of protective reflexes are clear indications, as is acute respiratory failure. ^[2] Burn-specific triggers include: ^[2]

• Systemic inhalation injury, for example carbon monoxide poisoning.
• Extensive burns of more than 40% total body surface area.
• Signs of burns to the oropharynx, such as blistering of the mucosa, hoarseness or developing stridor.

Careful and continuous airway monitoring is essential when choosing deferred intubation. ^[2] The longest tube safely passable should be chosen: a standard cuffed tube of at least 8.0 mm internal diameter is rated appropriate, because smaller tubes impede bronchoscopic cleaning and increase resistance during ventilation. ^[4]

Carbon monoxide binds to haemoglobin with much greater affinity than oxygen and shifts the dissociation curve to the left, so tissue hypoxia occurs long before the arterial oxygen tension falls. ^{[6] [8]}

• Assume CO exposure in every burn from an enclosed space. ^[6]
• Diagnosis is historical plus a carboxyhaemoglobin (COHb) level; an arterial oxygen partial pressure alone is unreliable. ^{[6] [8]}
• Levels below 20% are often symptom-free; higher levels bring headache, nausea, then confusion, coma and death. ^[8]
• Treat with high-flow 100% oxygen. CO dissociates slowly in air but faster on high-flow oxygen; the expert panel rated 100% oxygen appropriate and noted insufficient evidence for hyperbaric oxygen. ^{[4] [6]} One review estimates roughly 40 minutes to 1 hour of 100% oxygen reverses CO poisoning. ^[6]
• ISBI recommends high-flow oxygen for at least 6 hours. ^[2]

Cyanide is produced by burning synthetic polymers (plastics, papers, textiles) and blocks cytochrome oxidase, forcing the cell into anaerobic metabolism and lactic acidosis. ^{[4] [7]} Oxygen saturation can stay normal while the patient deteriorates. ^[7]

• Suspect cyanide when there is an anion-gap metabolic acidosis with a markedly elevated lactate (8 mmol/L or higher), unexplained cardiac dysfunction, altered consciousness, seizures, or arrest in a fire victim. ^[4]
• About one third of fire victims have toxic cyanide levels on arrival (^[7]).
• Symptoms are non-specific: headache, nausea, shortness of breath, altered mental state. ^[7]
• Treat with high-flow oxygen, hydroxocobalamin and sodium thiosulphate; hydroxocobalamin is more effective in severe cases. ^{[4] [7]}
• An international RAND/UCLA expert panel regarded prompt hydroxocobalamin as appropriate when the lactate is 8 mmol/L or higher, even before laboratory confirmation. ^[4]
• A commonly taught dose is 5 g intravenously over about 15 minutes, with a second 5 g dose if needed. ^[7]

The combined picture is the point of the cross-check: carbon monoxide and cyanide often coexist, both give headache and confusion, and both need oxygen plus attention to the airway and tissue perfusion. ^{[4] [7]}

For the clinician at the bedside, the relevant differential is not a list of rashes but the cause of the life-threatening problem.

First-line (every suspected inhalation injury):

• Oxygen saturation and arterial blood gas with co-oximetry for carboxyhaemoglobin. ^{[4] [6]}
• Venous or arterial lactate. ^[4]
• Baseline creatinine and creatine kinase after electrical injury. ^[6]
• Chest radiograph. ^[4]

Confirmatory and staging:

• Fibreoptic nasendoscopy and bronchoscopy to confirm and grade injury, clear casts and guide ventilation. ^{[4] [2]}
• Carboxyhaemoglobin trends; COHb usually falls on oxygen. ^[6]
• Cyanide level: too slow for clinical use; treat on suspicion. ^[7]

Normal ranges to remember: a lactate below 2 mmol/L makes cyanide intoxication much less likely. ^[4] Carboxyhaemoglobin below 20% is often symptom-free. ^[8]

Burn injury severity for fluid and referral decisions uses two numbers: depth and total body surface area (TBSA).

• Depth: superficial (first degree, not counted), partial thickness, full thickness. ^[8]
• Size: rule of nines in adults (head 9%, each arm 9%, each leg 18%, front trunk 18%, back trunk 18%, perineum 1%), or the palmar method (the patient's whole palm about 1% TBSA). ^{[1] [8]}
• Use Lund-Browder in children. ^[8]

The Abbreviated Injury Score grades bronchoscopic inhalation injury as mild, moderate and severe; this supports prognosis and decisions such as lavage, where an expert panel rated lavage appropriate in moderate and severe disease. ^[4]

The panel criteria above come from a comparative review of nine guidelines: ABA, BBA, DGV, EBA, EAST, IAEM, ISBI, JSBI and MSF. ^[2] Common intubation triggers include acute respiratory failure, loss of protective reflexes, airway obstruction, inspiratory stridor and severe cognitive impairment, plus the burn-specific triggers above. ^{[2] [3]}

Important negatives: no prophylactic antibiotics or corticosteroids for inhalation injury. ^{[2] [4]}

The cross-check is simple and must be run in parallel with the airway assessment. In an enclosed fire, assume both toxins. Give high-flow 100% oxygen, take blood for COHb and lactate, and consider hydroxocobalamin early if there is acidosis or a lactate of 8 mmol/L or more. ^{[4] [6] [7]}

Hydroxocobalamin has the advantage of not interfering with oxygen carriage, unlike the nitrite antidotes. ^[7] Hyperbaric oxygen is not well supported by evidence; maximal normobaric oxygen is the practical first step. ^{[2] [4]}

Stop the burning process, strip off non-adherent clothing and jewellery, and cool small thermal burns with cool running water for about 20 minutes, keeping the rest of the patient warm to avoid hypothermia. ^{[9] [8]} For chemical burns, brush dry powder off before irrigation, then irrigate with abundant water for 20 to 30 minutes (longer for alkalis, with eye irrigation up to hours). ^{[8] [9]}

Replace the plasma that leaks through the burn wound, titrating to perfusion rather than to a fixed formula alone.

Threshold. Different guidelines disagree: EBA, ABA, DGV and ISBI start resuscitation at 20% TBSA or more, whereas UK (BBA), JSBI, IAEM and MSF start at 15% TBSA or more. ^{[2] [8]} As a practical teaching rule, resuscitate any adult with a partial or full thickness burn above 15% TBSA. ^{[2] [8] [1]}

Formula. Two common crystalloid regimens: ^{[5] [6]}

• Parkland: 4 mL × TBSA (%) × body weight (kg) of a crystalloid over 24 hours; one half in the first 8 hours and the remainder in the next 16 hours. ^[6]
• Modified Brooke: 2 mL × TBSA (%) × body weight (kg), again one half in the first 8 hours and the remainder in the next 16 hours. ^[6]

The consensus baseline ABA recommends a crystalloid-based resuscitation of 2 to 4 mL/kg/%TBSA over the first 24 hours, titrated to perfusion. ^[5] The older Baxter form of the Parkland formula used 3.5 to 4.5 mL/kg/%TBSA of lactated Ringer's. ^{[5] [6]}

Choice. Guidelines differ on the multiplier: ABA recommends 2 mL/kg/%TBSA, EBA/ISBI 2 to 4, DGV/JSBI 2 or 4, IAEM 4 and MSF 2, with an MSF initial bolus of 20 mL/kg. ^[2] Whichever formula is chosen, start with one formula and adjust to the patient rather than chasing a fixed number. ^[6] Fluid creep, where patients receive far more than the predicted volume, is a recognised hazard. ^[5]

Crystalloid. Use an isotonic balanced solution such as Hartmann's (lactated Ringer's). One guideline panel (DGV) prefers to avoid Ringer's lactate because of concerns about lactate metabolism and rebound alkalosis, which is worth knowing if your protocol follows that school. ^[2]

Monitoring. Urine output is the universal primary endpoint, but targets differ: ABA and IAEM aim for 0.5 to 1.0 mL/kg/h; EBA around 0.5; DGV and ISBI 0.3 to 0.5; MSF 1 to 2 mL/kg/h. ^[2] For adults with electrical injuries the target is about 1 mL/kg/h, because myoglobinuria demands a higher urine flow. ^[6] Combine urine output with heart rate, blood pressure or lactate (under 2 mmol/L) and base excess rather than relying on one number. ^{[2] [5]}

Isotonic crystalloid goes in first. A 5% albumin infusion is added as rescue between 12 and 24 hours for larger burns or when resuscitation is failing, and fresh frozen plasma or colloids remain debated; some units add them early, while ABA advises against plasma outside research. ^{[2] [6]} Over-resuscitation causes pulmonary oedema, abdominal compartment syndrome and extremity compartment syndrome. ^[6]

Chemical burns are deeper and more progressive than they first appear, most of all with alkalis. Immediate priorities: ^{[8] [9]}

• Remove the person from contact and remove contaminated clothing and jewellery.
• Brush dry powders off the skin before any water touches them. ^{[8] [9]}
• Irrigate with copious water for at least 20 to 30 minutes, longer for alkali burns and for hydrofluoric acid. ^[8]
• Alkali burns to the eye need continuous irrigation for the first 8 hours. ^[8]
• Hydrofluoric acid burns (1% TBSA or more) are referred to a burn centre because of systemic fluoride toxicity. ^[8]

All chemical injuries meet burn centre referral criteria. ^[1] Do not try to neutralise the chemical on the skin.

Electricity kills through the heart and the kidneys before the skin gives the warning. Keep a high index of suspicion because injury is usually far deeper than the entry and exit wounds suggest. ^{[6] [8]}

• Low-voltage injuries are under 1,000 V and high-voltage 1,000 V or more; lightning is treated as high voltage. ^{[6] [1]}
• Alternating current is more dangerous than direct current because tetanic contraction keeps the person in contact. ^[6]
• Cardiac effects: arrhythmias appear in the first hours; all electrical burn victims need an ECG on arrival, with 24 hours of monitoring for a high-voltage injury, loss of consciousness, an abnormal ECG or significant cardiac history. ^[6]
• Rhabdomyolysis: check creatine kinase and trend it for 24 to 48 hours; myoglobinuric dark urine needs urine output of at least 100 mL/hour with forced fluids and correction of acidosis. ^{[6] [8]}
• ECG, cardiac biomarkers when indicated, and CK on arrival form the core work-up; troponin and CK-MB have limited value except with chest pain, instability or ECG changes. ^[6]
• Electrical burns over a joint or high-voltage injuries may hide fractures and dislocations from tetanic contraction, so image focal pain or swelling. ^[6]

Full-thickness circumferential burns cannot stretch; the leathery eschar acts like a tourniquet on a limb or a rigid shell on the chest. ^{[6] [8]}

• Limb: falling pulses, increasing pain, pallor, paraesthesia, paralysis, poikilothermia or swelling signal vascular compromise; measure compartment pressures if the exam is unreliable, with intervention when the pressure exceeds 30 mmHg or the delta pressure is below 30 mmHg. ^{[6] [4]}
• Chest: full-thickness circumferential chest or abdominal burns impair ventilation and may need an escharotomy to allow lung expansion. ^{[6] [8]}
• An escharotomy is urgent but usually not required within the first six hours after injury. ^[8]
• Fasciotomy is rarely needed and is reserved for high-voltage electrical injury, crush or associated skeletal trauma where pressure builds beneath the fascia. ^[8]

Transfer is a decision by the receiving burn team, made early rather than late. Referral triggers from the American Burn Association include: ^[1]

• All patients with suspected inhalation injury. ^[1]
• Full thickness burns, or partial thickness 10% TBSA or more in adults.
• Deep partial or full thickness burns of the face, hands, feet, genitalia, perineum or over any joint.
• All chemical injuries and all high-voltage electrical injuries.
• Lightning injury.
• Pediatric burns (14 years or under, or under 30 kg). ^[1]
• Partial thickness 5% TBSA or more in patients under 16, and 10% or more in those 16 and older. ^[8]
• Poorly controlled pain, burns with comorbid disease or traumatic injuries, and patients with inhalation signs such as facial flash burns, singed hairs or smoke exposure when not yet a full gas exchange injury. ^[1]

The operational detail differs by system, but the principle is universal: time-critical problems (airway, shock, circumferential compromise) are treated where the patient lies, and specialist transport is arranged in parallel rather than after stabilisation is complete. ^[8]

• Airway obstruction from oedema, typically hours after injury. ^{[3] [8]}
• Pneumonia and acute respiratory distress syndrome after inhalation injury. ^[4]
• Fluid overload, pulmonary oedema and abdominal or limb compartment syndrome from over-resuscitation. ^[6]
• Renal injury from myoglobin, hypoperfusion and rhabdomyolysis in electrical burns. ^[6]
• Circumferential ischaemia requiring escharotomy. ^[6]
• Systemic cyanide and CO toxicity, cardiac arrhythmia and seizures. ^{[4] [6] [7]}

Prognosis worsens with larger TBSA, older age, inhalation injury and delayed care. ^[8] A major burn with inhalation injury carries a substantially higher death risk than the burn alone; pneumonia after injury raises it further. ^[4] Electrical burns can look trivial at presentation yet produce late deep injury, so admission and serial review are needed. ^[6]

Burns are preventable and prevention is local: safer cooking, guarded stoves, smoke alarms, secure hot water, regulation of fuel and electricity, and workplace safety. ^[9] WHO recommends immediate running-water cooling and avoiding application of ice, oils or household remedies. ^[9] Cooling for about 20 minutes, where it can be done safely, is the widely cited practical advice. ^[9]

• Children: use Lund-Browder for TBSA; their fluid maintenance needs must be added (for example with dextrose-saline). ^{[5] [8]}
• Pregnancy: resuscitate and stabilise the mother first; fetal perfusion follows maternal perfusion. ^[1]
• Older adults: lower thresholds for referral, higher comorbidity risk and smaller physiological reserve. ^[8]
• Electrical injuries in children are mostly low voltage from household sockets, but still deserve assessment. ^[6]

• Confirm inhalation risk without imaging: voice, stridor, soot and a fire in a small space are enough to act. ^{[2] [3]}
• The Parkland formula and urine output are available almost anywhere; titrate by the clock even if laboratory back-up is absent. ^[5]
• Hydroxocobalamin is specific antidote for cyanide, but may not be stocked. Give 100% oxygen and support, consult poison control, and arrange transfer. ^[7]
• Calculated fluids can be delivered by whatever crystalloid is available; aim for the perfusion targets rather than the exact brand. ^[5]
• Escharotomy can be performed with a sterile scalpel and no anaesthetic when circulation or ventilation is threatened. ^{[6] [8]}

Before declaring the assessment complete, run through these items on every major burn: ^[8]

• Airway and breathing (including carbon monoxide and cyanide) reassessed and, if intubated, tube size and position confirmed.
• TBSA and depth recorded twice, with the person estimating burnt and coding it.
• Inhalation signs sought and documented.
• Electrical and chemical etiology excluded or handled under the specific rules above.
• Escharotomy needs assessed for every circumferential burn.
• Referral to a burn centre started, not deferred.
• Fluid rate calculated, started and titrated to urine output, with a clear time zero (time of injury).
• Analgesia and prevention of hypothermia addressed.

• Inhalation injury is a clinical diagnosis of suspicion that can kill hours later; secure the airway early when it is going to be lost. ^{[3] [4]}
• Intubation triggers are practical and consistent across guidelines: loss of airway protection, obstruction, respiratory failure, stridor, or neck/chest burns threatening patency, plus inhalation signs, more than 40% TBSA, or oropharyngeal burn. ^[2]
• Universal 100% oxygen is the immediate treatment for combined smoke poisoning; add hydroxocobalamin when acidosis or lactate of 8 mmol/L or more is present. ^{[4] [7]}
• Carbon monoxide carboxyhaemoglobin falls on oxygen; low levels below 20% are often asymptomatic, but enclosed-space fires should raise suspicion regardless. ^[8]
• Alkali chemical burns are deep and progressive; irrigation with water for 20 to 30 minutes minimum is the core treatment, and never neutralise. ^{[8] [9]}
• Electrical burns are always deeper than they look; start ECG, CK trending and forced diuresis early. ^[6]
• Parkland gives 4 mL/kg/%TBSA over 24 hours, half in the first 8; modified Brooke gives 2 mL/kg/%TBSA. ^[6]
• Urine output is the universal endpoint, but target values differ (about 0.5 to 1.0 mL/kg/h, lower for DGV/ISBI, higher for MSF and for electrical injuries). ^{[2] [6]}
• Every circumferential burn needs a repeat perfusion check and, when indicated, escharotomy. ^[6]
• Chemical, electrical and inhalation injuries all belong in a burn centre. ^[1]

Burns; Acute respiratory distress syndrome; Hypoxaemia and respiratory failure; Cardiac arrest and life support; Rhabdomyolysis; Acute kidney injury; Cyanide and drug toxicity; Hyperbaric medicine; Tetanus prophylaxis; Wound care and dressings.