Respiratory burns: a correlation of clinical and laboratory results

Pediatric inhalation injury

Smoke inhalation injury can cause severe physiologic perturbations. In pediatric patients, these perturbations cause profound changes in cardiac and pulmonary physiology. In this review, we examine the pathology, early management options, ventilator strategy, and long-term outcomes in pediatric patients who have suffered a smoke inhalation injury.

Fire and smoke injuries

The successful management of burns and related injuries requires a comprehensive team approach at a designated burn center. This team should consist of burn surgeons, burn nurses, respiratory therapists, physical therapists, occupational therapists, clinical nutritionists, social workers, chaplains, and other clinical consultants. This article focuses specifically on the management of thermal burns and inhalational injuries, with an emphasis on assessment, resuscitation, and critical care management. It also discusses special considerations related to burned trauma patients.

Acute lung injury, acute respiratory distress syndrome and inhalation injury: an overview

Acute Lung Injury (ALI) and the Acute Respiratory Distress Syndrome (ARDS) are severe respiratory diseases that have a very poor prognosis and have numerous causes. Despite a great deal of research and investigation since the initial description of ARDS 30 years ago many questions about the pathogenesis, treatment and outcome of the disease remain unanswered. Although there is evidence to suggest that outcome of ALI and ARDS is improving, the reasons why are unknown and there is not yet a well developed treatment for these diseases. Inhalation injury resulting from exposure to pyrolysis and combustion atmospheres is among the causes of ALI/ARDS. Little is known of the mechanisms of fire related inhalation injury that results in the development of ALI/ARDS. There is a paucity of information about fire atmosphere exposure response relationships for smoke-induced inhalation injury. Although there is considerable information about the pulmonary toxicity of many of the more common constituents of fire atmospheres, little is known about the pulmonary toxicity of mixtures of these constituents. Fire related pulmonary health risks are of particular concern to the Navy due to the limited opportunity to escape the inhalation hazards posed by shipboard fires. Consequently the Naval Medical Research Institute Detachment (Toxicology) has undertaken a research program to develop research models of combustion atmosphere induced ALI/ARDS which can be exploited to systematically address some of the questions surrounding fire related ALI/ARDS. ALI/ARDS has been the topic of a vast amount of research, numerous symposia, working groups and their published proceedings, book chapters, and books. Less information is available regarding experimental models of smoke induced lung damage, however the literature on the subject is extensive. Consequently this article is intended to provide the reader with a primer or cursory "overview" of ALI and ARDS from a toxicological perspective and should not be considered comprehensive.

Detection of acute inhalation injury in fire victims by means of technetium-99m DTPA radioaerosol inhalation lung scintigraphy

Mortality and morbidity in fire victims are largely a function of injury due to heat and smoke. While the degree and area of burn together constitute a reliable numerical measure of cutaneous injury due to heat, as yet no satisfactory measure of inhalation injury has been developed. In this study, we employed technetium-99m diethylene triamine penta-acetic acid (DTPA) radioaerosol lung scintigraphy (inhalation scan) to evaluate acute inhalation injury in fire victims. Ten normal controls and 17 survivors from a fire accident were enrolled in the study. All patients suffered from respiratory symptoms (dyspnoea and/or cough with sputum). 99mTc-DTPA aerosol inhalation lung scintigraphy was performed in all subjects, using a commercial lung aerosol delivery unit. The degree of lung damage was presented as the clearance rate (k; %/min) calculated from the time-activity curve over the right lungs. In addition, the distribution pattern of the radioactivity in the lungs was evaluated and classified into two groups: homogeneous distribution and inhomogeneous distribution. A plain chest radiograph (CxR) and pulmonary function test (PFT) were performed in the same group of patients. The results showed that 6/17 (35.3%) patients had inhomogeneous distribution of radioactivity in their inhalation scans, and 11/17 (64.7%) had homogeneous scans. Five of the six patients with inhomogeneous scans were admitted for further management, and all patients with homogeneous scans were discharged from the emergency department and needed no further intensive care. The clearance rates of the right lung were 0.73%+/-0.13%/min for normal controls and 1.54%+/-0.58%/min for fire victims. The difference was significant, with a P value of less than 0.01. Using a cut-off value of 0.9%/min (all normal subjects were below 0. 9%/min), 14 (82.4%) patients had abnormal clearance rates of 99mTc-DTPA from the lung. In contrast, only three (17.6%) patients had abnormal CxR and three (17.6%) had abnormal PFTs. We conclude that (1) conventional CxR and PFT are not good modalities for evaluating inhalation injury in fire victims because of their low sensitivity, and (2) 99mTc-DTPA radioaerosol inhalation scintigraphy can provide an objective evaluation of inhalation injury during a fire accident and may be useful in therapeutic decision-making and disease monitoring.

Early effects of smoke inhalation on alveolar macrophage functions

Alveolar macrophage (AM) dysfunctions have been implicated in the pathogenesis of smoke inhalation lung injury. We investigated the early (within 70 min) effects of smoke inhalation on AM. The cells were recovered by bronchoalveolar lavage from rabbits ventilated with cotton smoke for 5 min followed by O2/room air for 60 min (smoke-exposed) or with room air in place of smoke (control). Smoke injury caused arterial blood carboxyhaemoglobin levels to increase 11-fold and reduced arterial blood PO2 (measured approximately 1 h postinjury) by 25 per cent. Scanning electron micrographs revealed denudation of plasmalemmal pseudopods in smoke-exposed AM. Smoke exposure suppressed both AM adherence to plastic and phagocytosis of opsonized bacteria. Basal superoxide (O2-) production was elevated in smoke-exposed AM, compared with controls, whereas PMA-stimulated O2- production was unaffected. Smoke-exposed AM had reduced basal secretion of tumour necrosis factor-alpha (TNF-alpha), but displayed a greater TNF response to stimulation with LPS than did control cells. LPS-stimulated TNF-alpha releases from control and smoke-exposed AM were suppressed by phosphodiesterase inhibitors pentoxifylline and theophylline, and were enhanced by the lipoxygenase inhibitor, MK886. The early responses of AM to smoke inhalation lung injury are consistent with activation of O2- production and priming of TNF-alpha release, concurrent with a functional down regulation of phagocytosis.

Diagnosis and treatment of smoke inhalation

Inhalation remains the most frequent and serious comorbid event that occurs in thermally injured patients. A thorough understanding of the pathophysiology enables individualization of therapy and appropriate triage of patients. We summarize our current knowledge of the pathophysiology, diagnosis, and treatment of inhalation injury, with a focus on newer treatment strategies that are evolving secondary to laboratory research.

Protection by cysteine esters against chemically induced pulmonary oedema

Perfluoroisobutene (PFIB) is a hydrophobic reactive gas produced by the pyrolysis of polytetrafluoroethane which induces pulmonary oedema similar to that induced by phosgene when inhaled. When a lethal dose is inhaled by Porton strain rats total non-protein thiol (NPSH) and glutathione (GSH) in the lung are reduced by between 30 and 49%, respectively. If the endogenous levels of thiols in the lung are reduced by pretreatment with buthionine sulfoximine (BSO) 16 hr before exposure to PFIB, the rats become more susceptible to the effects of the gas. The effect of BSO pretreatment on toxicity was prevented by pretreatment 30 min before exposure, with 5 mmol/kg N-acetylcysteine (NAc). NAc increased the levels of cysteine (CySH) in the lung by 150% and GSH was unaffected. Similarly pretreatment with 3 mmol/kg CySH also protected against toxicity and raised CySH levels by 100%. A series of cysteine esters and cystine dimethyl ester (CDME) have been synthesised which selectively raise lung levels of CySH in the rat lungs after intraperitoneal (i.p.) injection. The methyl ester and CDME raised lung levels of CySH by 4000 and 2000%, respectively, 10 min after i.p. injection whilst GSH levels remained unchanged. Cysteine isopropyl ester raised lung levels of CySH by 10,600% but liver levels by only 1400%. All esters except the t-butyl ester (CTBE) also raised maximal plasma levels of NPSH by up to 500%; however, when NAc was injected plasma levels increased by over 1500%. Rats treated with these esters at 3 mmol/kg and with NAc at 5 mmol/kg were protected against lethal doses of PFIB in all cases except when CTBE was used. It appears that these cysteine esters may distribute preferentially into the lung, unlike NAc. The selective enhancement of pulmonary CySH levels may provide a method for the protection of lungs against inhaled reactive toxicants by increasing intracellular CySH. Levels of CySH may also be raised in epithelial lining fluid thus reducing access of gaseous toxicants to pulmonary tissue.

Influence of glottic mechanism on pulmonary function after acute lung injury

We measured arterial gas tensions, respiratory timing, and intratracheal pressure in 12 rabbits to investigate the consequences of translaryngeal intubation with normal and subsequently injured lungs. Data were collected before, during, and after intubation. Intubation in normal rabbits precipitated no untoward effects on gas exchange or respiratory phase timing. However, there was significant elevation of subglottic pressure during expiration following extubation. Central venous injection of oleic acid (0.08 ml/kg) induced an acute lung injury that after 24 h was characterized by reduced PaO2 and dynamic lung-thorax compliance and tachypnea. Intubation in animals with acute lung injury was associated with a significant decline in arterial oxygenation, tachypnea, and increased PCO2. Expiratory tracheal pressure and expiratory time were greater and PaCO2 and respiratory rate were lower following extubation. We conclude that translaryngeal intubation following acute lung injury exacerbates already compromised pulmonary function by preventing a compensatory expiratory braking maneuver by the glottic apparatus.

Managing smoke inhalation injuries

Inhalation injuries most often occur with cutaneous burns, and the likelihood of an inhalation injury increases incrementally with age of the patient and size of the burn. Damage to the pulmonary parenchymal tissue manifests as increased capillary permeability leading to excessive lung fluid formation and increasing hypoxia. An inhalation injury may be diagnosed using observation of indirect criteria in conjunction with fiberoptic bronchoscopy, xenon 133 radiospirometry, and/or measurement of extravascular lung water. Initially, carbon monoxide poisoning threatens the patient's oxygenation capacity. High-flow oxygen therapy reduces the half-life of carbon monoxide to an acceptable period. The patient proceeds through three stages: pulmonary insufficiency, pulmonary edema, and bronchopneumonia. Treatment is directed toward supporting oxygenation using endotracheal intubation with mechanical ventilation, humidification of inspired air, early mobilization, chest physiotherapy, antibiotics for documented infection, and adequate systemic hydration.

Airway complications from free-basing cocaine

The majority of the deaths due to fires result from smoke inhalation, hypoxia, and systemic toxicity. Lower airway injury from chemical byproducts carried in the smoke is less frequent and thermal injury to the lower airways is a rare occurrence. We report a case of severe thermal injury to the conducting airways due to either inhalational injury or to intratracheal ignition of the ether vehicle used in free-basing cocaine resulting in severe reactive airways disease and tracheal stenosis requiring reconstructive surgery.

Management of patients with glottic and subglottic stenosis resulting from thermal burns

A series of 11 laryngeal burn patients is reviewed. Various methods of laryngeal burn management are detailed, including steroid usage, laser therapy, and reconstruction with local flaps, grafts, and stents.

Inhalation injuries

Inhalation injuries occur in approximately one-third of all major burns and account for a significant number of deaths in those burn patients each year. Victims die as a result of carbon monoxide poisoning, hypoxia, and smoke inhalation. These deaths can occur without thermal wounds as well as with burn injuries. There are three distinct problems with inhalation injuries: thermal burns of the upper airway, carbon monoxide poisoning, and smoke inhalation. Each has different symptoms and signs, different treatment, and different prognosis. Thermal burns occurring in the upper airway are usually manifested within 48 hours of injury. Diagnosis is made by direct visualization of the upper airway, looking for signs of thermal injury. Admission for observation with humidified oxygen, attentive pulmonary toilet, bronchodilators as needed, and prophylactic endotracheal intubation as indicated are the mainstays of treatment. Resolution of the injury usually occurs within days. Carbon monoxide poisoning, the most common cause of death in inhalation injury, is a result of combustion. Symptoms and signs correlate with blood levels, but arterial blood gases are used to determine the degree of carbon monoxide intoxication. Treatment is based on the principle that carbon monoxide dissociation occurs much faster if the patient is placed on 100% oxygen. Occasionally the patient's symptoms may persist or get worse despite adequate treatment. Smoke inhalation significantly damages normal respiratory physiology, resulting in injury progressing from acute pulmonary insufficiency to pulmonary edema to bronchopneumonia, depending on the severity of exposure. Diagnosis is based on history, but clinical findings, arterial blood gases, and fiberoptic bronchoscopy are helpful. Treatment is supportive with careful attention paid to fluid resuscitation in the patient with burns.(ABSTRACT TRUNCATED AT 250 WORDS)

Smoke inhalation

An attempt has been made to review the characteristics of fire and smoke and the epidemiology of smoke inhalation to identify some of the many variables which interact to control the severity of the injury. An experimental model appropriate to study the pulmonary injury of smoke victims who survive to enter the health care system is described. Experiments which define how smoke damages the lung are reviewed in an effort to explain why the smoke-damaged lung is vulnerable to additional stress and why those with an injured lung and a burn have such a high mortality rate.

Induction of bronchial hyperresponsiveness following smoke inhalation injury

We report two subjects without previous evidence of asthma in whom wheeze, breathlessness and bronchial hyperresponsiveness occurred following an acute smoke inhalation injury.

Inhalation injury in burned patients: effects and treatment

Pulmonary pathology in major thermal injury is found in 30-80 per cent of burn fatalities. The incidence and mortality from inhalation injury increases both with age and increasing burn size. Toxic smoke inhalation injury, characterized by increased lung microvascular permeability, is attenuated by increasing cardiac output to normal levels, indicating that fluid restriction after inhalation injury may lead to excessive lung fluid formation and hypoxia. Fluid administration of approximately 2 ml/kg/% area burned above the calculated resuscitation volume is required following an inhalation injury to provide adequate support for the systemic circulation and maintain cardiac output at normal levels. This additional volume does not contribute to the development of pulmonary oedema, but may decrease its formation by increasing shear forces thus reducing polymorphonuclear leucocyte deposition in the pulmonary microcirculation. Nasotracheal intubation is preferred when airway integrity is compromised by inhalation injury. The advantages are non-operative placement, ease of discontinuation, minimal bacterial contamination and leaving neck burns undisturbed. The administration of the appropriate antibiotics for documented infection is recommended, while steroids have been shown to be of no benefit.

The plain chest radiograph after acute smoke inhalation

Serial chest radiographs of 45 patients from a major fire disaster were assessed for the effects of smoke inhalation injury. Thirty-three had abnormal chest radiographs on admission. Bronchial wall thickening was present in a total of 29 patients, subglottic oedema in 13, pulmonary oedema in seven, and patchy consolidation in three. Seven patients developed pulmonary oedema following initial exposure. This was the cause of death in two patients. Serial chest radiographs were useful in monitoring this very severe complication. Bronchial wall thickening and subglottic oedema were common early findings and thus may herald more serious subsequent respiratory embarrassment. Subglottic oedema is a previously undescribed finding. It not only indicates damage to the upper airways but may also indicate damage to the lung parenchyma. It may also make endotracheal intubation difficult. Therefore, the initial chest radiograph is an important predictor of significant smoke inhalation injuries enabling selection of patients likely to need ventilatory support.

Blood gas studies in dogs with severe steam inhalation injury

The dynamic changes in blood gases in 34 dogs suffering severe steam inhalation injury were studied during the first 14 days post-burn to determine the effects of inhalation injury on lung function. Nineteen dogs received only severe steam inhalation injury, while 15 other dogs received both 30 per cent total body surface area (TBSA) deep burns and steam inhalation injury. The results showed marked reductions of PaO2, PaCO2, AB, SBE, T-CO2, SB, BBp, pHNR and SatO2 (P less than 0.05 approximately 0.01), whereas the P(A-a)O2 increased (P less than 0.05 approximately 0.01) within week 1 post-burn in both groups. These data suggest that the injured animals were suffering from hypoxaemia and respiratory alkalosis induced by disturbance of the gas-exchange function of the lungs. There was also metabolic acidosis, which was closely related to high fever, excessive catabolism, and particularly to hypoxaemia in week 1 post-burn. If the animals survived through the critical period (1-7 days post-burn), most of the abnormal gas parameters then gradually returned to the pre-burn levels. It is clear, therefore, that blood gas monitoring in patients with inhalation injury is not only of diagnostic importance but also of prognostic value.

Pulmonary injury in burned patients

Inhalation injury has emerged as the number one cause of fatality in the burn patient. Fiberoptic bronchoscopy and 133Xe scanning complement traditional clinical signs of inhalation injury and have led to discovery of a higher incidence of these injuries among patients with burns. Patients with inhalation injury typically demonstrate three stages: acute pulmonary insufficiency, pulmonary edema, and bronchopneumonia, all of which carry at least 50 per cent mortality rates. The major early pathophysiologic changes in the lungs of burned patients are related to upper-airway obstruction and lower-airway permeability edema. Treatment consists of intubation for signs of respiratory distress, pulmonary toilet, humidification of inspired air, and antibiotics for documented infection.

Mortality probability in victims of fire trauma: revised equation to include inhalation injury

There are no clear guidelines on the early diagnosis of injury due to inhalation of smoke. A clinical scoring system in the form of a previously prepared questionnaire may be used in the accident and emergency department by staff who are inexperienced in the management of inhalation injury. By quantifying injury due to smoke inhalation, its contribution to mortality in a large group of fire victims was established and a revised mortality probability equation derived using age, percentage surface area of the burn, and extent of inhalation injury. This mortality probability equation may be used to divide patients into risk categories for early intensive care management and allows the comparison of mortality data between accident and emergency units receiving varying numbers of patients with injuries due to burns and smoke inhalation.

Treatment of burns in children

Decreases in mortality from major thermal injury over the last 20 years have been due to advances in resuscitation, control of infection, support of the hypermetabolic response, and early closure of the burn wound. Of these advances in burn care, early wound closure has progressed the most in the last five years. The restoration of the protective functions of the skin is of primary importance to the recovery of the burn patient. Biologic dressings (pigskin, amnion, human skin allograft) when applied to fully debrided, relatively uncontaminated wounds have been shown to adhere to the wound surface, reduce the wound colony counts, limit fluid and protein loss, reduce pain, and increase the rate of epithelialization over that obtained with application of topical antimicrobial agents.

Respiratory injury in the burned patient. The role of flexible bronchoscopy

The purpose of the study was to investigate the role of flexible bronchoscopy in the management of patients admitted to a busy Regional burns unit, with particular reference to possible smoke inhalation injury. The basic procedure employed was that used in routine bronchoscopy for the diagnosis of bronchial carcinoma, with modification of the premedication required in view of the shorter duration of the technique and the lack of a requirement for bronchial biopsy. We have found the procedure easy to perform, well tolerated by the patients and not associated with any complications. It provides additional information not otherwise available, which can influence the subsequent management of the patient. An experienced bronchoscopist and additional personnel skilled in resuscitation techniques are required. It should be performed in patients with clear evidence of smoke inhalation injury and in particular with facial burns in order to visualise the extent of airway injury, remove debris and give some indication of the likelihood of subsequent complications such as acute upper airways obstruction.

Inhalation injury caused by the products of combustion

Inhalation injury results from a type of chemical burn (tracheobronchitis) of the respiratory tract. When this injury occurs in patients with serious cutaneous burns the mortality is exceedingly high- 48% to 86%. The injury can be divided into three types according to the level at which the damage occurs; upper airway, major airway and terminal airway. The early signs and symptoms may be complicated by carbon monoxide poisoning. The patient's condition usually follows a staged progression that is proportional to the extent and severity of the tracheobronchitis. Indirect laryngoscopy, bronchoscopy, scintiscanning of the lung with xenon 133 and serial analysis of arterial blood gases are useful diagnostic techniques. Treatment must be expeditious, and it depends on the severity of the injury. The prophylactic use of antibiotics and steroids is contraindicated.

Management of burns of the head and neck

Burns of the head and neck with or without respiratory tract injury remain a serious and complex problem. Care of patients with this injury requires astute frequent clinical examinations, repeated laryngoscopy or flexible bronchoscopy, and serial laboratory investigations. Superb monitoring and care by the entire burn team with frequent dialogue among the individuals with specialized knowledge, mature clinical judgement in regard to therapy, the long-term follow-up help burn victims survive the injury and achieve the best possible functional ability and cosmetic appearance. There are no simple answers or rote decisions in the management of these injuries. The challenge requires the most innovative and creative care coupled with large amounts of hard work. Many of the recent advances in the management of burns of the head and neck have permitted these patients to survive and have helped them to return as functioning members of society.

Fire deaths in the Glasgow area: I General considerations and pathology

A study of fire deaths, in operation in the Glasgow area since 1976, has been aimed at elucidating the role of smoke and toxic gases in fire fatalities, especially where these occurred in buildings. During the first 3 years of the project, 199 cases were examined of which 182 were eligible for inclusion in the study. This paper reports the major pathological features of these cases and gives details of the epidemiological and demographic statistics. Most of the fatalities (79 per cent) occurred in dwellings. While the old and young members of the community were shown to be particularly vulnerable, male and female casualties were approximately equal in number. The peak periods for fire deaths were at weekends and in the winter months. Burn injuries were present in 83 per cent of cases included in the study, and in 66 per cent these would have been sufficient to cause death, although it was difficult to distinguish between premortem and postmortem burns. Fatal levels of carbon monoxide were present in 52 per cent of the fatalities, and in these cases death was attributed to the inhalation of fire gases. Soot deposition in the respiratory tract as a result of smoke inhalation was observed in 91 per cent of the cases and further injury to the respiratory tract was present in 84 per cent of the cases. Evidence of significant haemolysis was present in 48 per cent of the fatalities. Chronic disease processes were also observed in many fatalities, including lung disease (16 per cent), cardiovascular disease (29 per cent) and liver disease (32 per cent). These rates reflect the high levels of incidence of these diseases in the Glasgow area.

Postburn respiratory injuries in children

Respiratory tract injury is a leading cause of mortality, morbidity, and prolonged hospitalization in fire casualties. Direct insults include inhalation of superheated gas, steam, smoke, or toxic fumes. Indirect injury may result from interference with the mechanics of respiration. Pulmonary injuries result from sepsis, fluid overload, endogenous reactive substances, and "shock lung," and also occur secondary to metabolic disturbances resulting from hypoxia.

Respiratory effects of a single, moderately acute, smoke inhalation episode

Twenty-three hospital employees who suffered ill effects of smoke inhalation were pulmonary-function tested within 72 hours, after ten weeks, and again after 45 weeks of exposure. Four nonexposed control subjects were selected for comparison of data.Exposed persons commonly had restrictive lung disease which may have resulted from stimulation of irritant receptors in bronchi and/or interstitial edema of chemical injury at the level of the ventilation-perfusion unit. Airways obstruction was infrequent, despite the possibility of inhalation of di-isocyanates, an intermediary product of burning polyurethane foam that may cause chemical asthma. Eye and constitutional symptoms were also frequent.Clinical recovery was as a rule rapid and complete (within a week), but physiologic recovery was protracted (over 45 weeks in some cases). Most surprisingly, cigarette smoking and/or presence of cardiopulmonary disease did not contribute to morbidity.

Pulmonary burns in children

Basic concepts have evolved from a 15-yr experience in the management of 101 children with inhalation injuries. Progression through three distinct clinical stages--bronchospasm (1--12 hr post-burn), pulmonary edema (6--72 hr), and bronchopneumonia (after 60 hr)--was often noted. Success in outcome appeared to depend upon treatment that conformed to the pathophysiologic state present, a pulmonary toilet being both thorough and aseptic, tracheotomy being reserved for true glottic or supraglottic airway obstructions, the sharp division of strangulating or suffocating constrictions caused by cervical or thoracic eschars, use of ventilators primarily to maintain arterial pO2 above 60 mm Hg and to reverse otherwise intractable pulmonary edema, corticosteroids being administered as a single intravenous bolus and only for overt bronchospasm, and parenteral antibiotic therapy being based upon sputum smears and cultures for established pneumonia alone, never as prophylaxis.

Acute chlorine gas exposure

The heavy use of chlorine gas in industry and water purification poses the constant threat of mass gas exposure. In a recent experience with a chlorine gas disaster involving over 100 patients, 64, including six subsequently requiring admission, were treated in the main emergency unit facility. The remainder were triaged to a safe area away from the emergency unit with instructions for symptomatic treatment. Injuries were limited to four organ systems: pulmonary, gastrointestinal, ophthalmic, and cutaneous. Current treatment methods are compared with those in the literature and a protocol for management provided.

Respiratory tract burns after aspiration of hot coffee

We present the fingings in a patient with acute thermal burn to the upper and lower airway who developed mucosal edema followed by patchy areas of granuloma-like lesions in the trachea and bronchi. A four-month follow-up showed resolution of the gross lesions, but functional alterations remained. This patient illustrates the necessity for repeated direct observation and functional evaluation of the lower airway folllowing thermal injury, which can be a life-threatening disorder.

Inhalation injury

It is suggested that in patients exposed to the danger of smoke inhalation injury, whether or not they are also burned, the first requirement is extreme vigilance since the manifestations of inhalation injury are usually considerably delayed. Secondly, if evidence of this respiratory syndrome appears, steroids should be administered forthwith in substantial doses. Thirdly, where exposure to inhalation injury is known to have been severe, steroids should be used immediately, without awaiting development of respiratory distress.

The respiratory injury in burns. An account of the management

The management of three patients suffering from respiratory complications of burns is described. The pathogenesis and treatment of pulmonary inhalational injury is reviewed and methods of monitoring respiratory function are discussed.

The pathophysiology of smoke inhalation injury

The consequences of near-lethal smoke inhalation in dogs were studied for a 72-hour period following injury. Progressive hypoxemia and decrease in compliance developed. Severe respiratory distress and frank pulmonary edema were not encountered. Respiratory insufficiecy was related more to alterations in ventilation perfusion ratios than to alveolar destruction. These data were related to clinical observations made by others. No deterioration of lung function was seen with crystalloid overload imposed upon smoke inhalation. The presence of bacterial infection in dogs surviving beyond 24 hours appears pathogenically significant.

Sepsis, resuscitated hemorrhagic shock and "shock lung:" An experimental correlation

Dogs were submitted to hermorrhagic shock, resuscitated shock and resuscitated shock plus a pulmonary bacterial insult. Pulmonary familure was absent in dogs submitted only to shock or to shock and its resuscitation. The addition of usually sub-lethal amounts of micro-organisms to the shock-resuscitated lung caused rapid death from pulmonary failure. Pulmonary failure was demonstrated by increased lung weight, hypoxemia, decreased compliance and a hemorrhagic destruction of lung tissue. These findings strongly support recent concepts of an infective genesis of "shock lung" in man.