Fire, smoke inhalation, and burns: goals of therapy and treatment

By Cristiano Antonino On Apr 8, 2023

The damages induced by smoke inhalation determine a dramatic worsening of the mortality of burn patients: in these cases the damages deriving from smoke inhalation add up to those from burns, often with lethal consequences

This article is dedicated to burn therapies, with particular reference to pulmonary and systemic damages in burnt subjects who have inhaled smoke, while dermatological lesions will be explored elsewhere.

Smoke inhalation and burns, the goals of therapy

The objectives of respiratory assistance in burn patients are to ensure:

airway patency,
effective ventilation,
adequate oxygenation,
maintaining acid-base balance,
maintaining cardiovascular stability,
prompt treatment of infections.

In some cases, performing an excartomy is essential to prevent any chest scar tissue from impeding chest movement.

The goals of skin burn treatment are:

removal of non-vital skin,
application of medicated bandages with topical antibiotics,
wound closure with temporary skin substitutes and transplantation of skin from healthy areas or cloned samples onto the burned area,
reduce fluid loss and risk of infection.

The subject must be given caloric amounts higher than the basal ones, in order to facilitate wound repair and avoid catapolism.

Treatment of burn patients with toxic smoke inhalation

Burn victims with minor lesions affecting the upper airways, or with signs of respiratory obstruction or, in any case, pulmonary involvement, must be closely monitored.

It is necessary to supply an oxygen supplement, through a nasal cannula, and to have the patient assume the high Fowler position, in order to reduce the work of breathing.

Bronchospasm is treated with aerosolized β-agonists (such as orciprenaline or albuterol).

If airway obstruction is anticipated, it should be secured with an appropriately sized endotracheal tube.

Early tracheostomy is generally not recommended in burn victims because this procedure is associated with a higher incidence of infection and increased mortality, although it may be necessary for long-term respiratory support.

Early intubation has been reported to precipitate transient pulmonary edema in some patients with inhalation injury.

Application of 5 or 10 cm H2O continuous positive airway pressure (CPAP) can help minimize early pulmonary edema, preserve lung volume, support oedematous airways, optimize ventilation/perfusion ratio, and reduce mortality early.

Systemic administration of cortisone for the treatment of edema is not recommended, in view of the increased risk of infections.

Treatment of comatose patients is directed towards severe hypoxia from smoke inhalation and CO poisoning and is based on the administration of oxygen

The dissociation and elimination of carboxyhemoglobin are accelerated by the administration of oxygen supplements.

Subjects who have inhaled smoke, but have only a slight increase in Hbco (less than 30%) and maintain normal cardiopulmonary function, should preferably be treated with the delivery of 100% oxygen through a tightly fitting face mask, such as “nonrebreathing” (which does not allow you to inhale the air you just exhaled again), with a flow of 15 litres/minute, keeping the reserve tank full.

Oxygen therapy should continue until Hbco levels fall below 10%.

Mask CPAP with 100% oxygen delivery may be appropriate therapy for patients with worsening hypoxemia and no or only mild thermal lesions of the face and upper airways.

Patients with refractory hypoxemia or aspiration injury associated with coma or cardiopulmonary instability require intubation and respiratory assistance with 100% oxygen and are promptly referred for hyperbaric oxygen therapy.

The latter treatment rapidly improves oxygen transport and accelerates the process of eliminating CO from the blood.

Patients who develop early pulmonary edema, ARDS, or pneumonia often require positive end-expiratory pressure (PEEP) respiratory support in the presence of ABGs indicative of respiratory failure (PaO2 less than 60 mmHg, and / or PaCO2 higher than 50 mmHg, with pH lower than 7.25).

PEEP is indicated if PaO2 falls below 60 mmHg and FiO2 demand exceeds 0.60.

Ventilatory assistance must often be prolonged, because burn patients generally have an accelerated metabolism, which requires an increase in respiratory minute volume to ensure the maintenance of homeostasis.

The equipment used must be capable of delivering a high volume/minute (up to 50 litres), while maintaining high peak airway pressures (up to 100 cm H2O) and an inspiration/expiration ratio (I:E) stable, even when blood pressure needs to be increased.

Refractory hypoxemia may respond to pressure-dependent, reverse-ratio ventilation.

Adequate lung hygiene is necessary to keep the airways clear of sputum.

Passive respiratory physiotherapy helps mobilize secretions and prevent airway obstruction and atelectasis.

Recent skin grafts do not tolerate chest percussion and vibration.

Therapeutic fibrobronchoscopy may be necessary to unblock the airways from the accumulation of thickened secretions.

Careful maintenance of fluid balance is necessary to minimize the risk of shock, renal failure, and pulmonary edema.

The restoration of the patient’s water balance, using the Parkland formula (4 ml of isotonic solution per kg for each percentage point of burned skin surface, for 24 hours) and basically maintaining the diuresis at values between 30 and 50 ml/hour and central venous pressure between 2 and 6 mmHg, helps preserve hemodynamic stability.

In patients with aspiration injury, capillary permeability increases, and pulmonary artery pressure monitoring is a useful guide to fluid replacement, in addition to urine output control.

It is necessary to monitor the electrolyte picture and the acid-base balance.

The hypermetabolic state of the burn patient requires a careful analysis of the nutritional balance, aimed at avoiding the catabolism of the muscle tissue.

Predictive formulas (such as those of Harris-Benedict and Curreri) have been used to estimate the intensity of metabolism in these patients.

Currently, portable analyzers are commercially available that allow serial indirect calorimetry measurements to be made, which have been shown to provide more accurate estimates of nutritional needs.

Patients with extensive burns (greater than 50% of the skin surface) are often prescribed diets whose caloric intake is 150% of their resting energy expenditure, to facilitate wound healing and prevent catabolism.

With the healing of burns, the nutritional intake is progressively reduced to 130% of the basal metabolic rate.

In circumferential chest burns, scar tissue can restrict chest wall motion

The escharotomy (surgical removal of the burned skin) is carried out by making two lateral incisions along the anterior axillary line, starting from two centimeters below the clavicle up to the ninth-tenth intercostal space, and two other transverse incisions stretched between the ends of the first, to define a square.

This intervention should improve the elasticity of the chest wall and prevent the compressive effect of the scar tissue retraction.

Treatment of the burn includes removal of non-vital skin, application of medicated dressings with topical antibiotics, wound closure with temporary skin substitutes, and grafting of skin from healthy areas or specimens onto the burned area. cloned.

This reduces fluid loss and the risk of infection.

Infections are most often due to coagulase-positive Staphylococcus aureus and gram-negative bacteria, such as Klebsiella, Enterobacter, Escherichia coli and Pseudomonas.

An adequate isolation technique, the pressurization of the environment, the filtration of the air, represent the cornerstones of the defense against infections.

The choice of antibiotic is based on the results of serial cultures of material from the wound, as well as blood, urine, and sputum samples.

Prophylactic antibiotics should not be administered to these patients, due to the ease with which resistant strains can be selected, responsible for infections refractory to therapy.

In subjects who remain immobilized for prolonged periods, heparin prophylaxis can help reduce the risk of pulmonary embolisms, and particular attention must be paid to preventing the development of pressure ulcers.

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