Inhalation injuries

An Introduction to Burn Care: The Sequel

GENERAL PURPOSE

To review burn care, with an emphasis on burn-specific issues and treatment.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will:1. Select the appropriate treatment guidelines for patients who have burn injuries.2. Identify common complications of major burns.3. Choose the recommended pharmacologic approaches to burn care.

Predictors and Impact of Pneumonia on Adverse Outcomes in Inhalation Injury Patients

Inhalation injury (II) is the third mortality prognostic factor for burn injury following age and burn size. II can lead to pulmonary complications such as pneumonia and acute respiratory distress syndrome (ARDS); all of which have been hypothesized to increase morbidity and mortality in II. Herein, we aimed to identify variables associated with the risk of developing pneumonia and to determine the impact of pneumonia on selected II outcomes. De-identified data from the Prospective Inhalation Study titled Inhalation Injury Scoring System to Predict Inhalation Injury Severity (ISIS) were used. II was confirmed by fiberoptic bronchoscopy. Demographics, injury, and hospital course information were recorded. P < .05 was considered significant. One hundred subjects were included. On univariate analysis, pneumonia was associated with burn severity, race, and receipt of colloid during the first 24 hours. Patients who developed pneumonia spent more time on a ventilator, had longer hospitalizations (LOS) and were more likely to need a tracheostomy. On multivariate analysis, total number of ventilator days was associated with pneumonia (Odd ratio (OR) = 1.122 [1.048-1.200], P = .001). Both pneumonia and receipt of colloid were predictive of increased ventilator days (OR = 2.545 [1.363-4.753], P < .001 and OR = 2.809 [1.548-5.098], P < .001, respectively). Pneumonia was not an independent predictor of LOS, ARDS, or mortality. Pneumonia remains a high-risk complication associated with two times more ventilator days in II. Future research should focus on prevention of pneumonia and the relationship between colloid fluids and pneumonia and early ventilator liberation in II patients.

Acute respiratory failure and burn patient outcomes

PURPOSE OF REVIEW

Advances in the care of inhalational injuries have not kept pace with advances that have been seen in the treatment of cutaneous burns. There is not yet a standard of care for best outcomes for airway management of patients with known or suspected inhalational injuries. Clinicians must decide if to intubate the patient, and if so, whether to intubate early or late in their presentation. Unnecessary intubation affects morbidity and mortality. This review will summarize literature that highlights present practices in the treatment of patients with inhalation injuries.

RECENT FINDINGS

There have been promising investigations into biomarkers that can be used to quantify a patient's risk and better target therapies. Grading systems serve to better stratify the burn victim's prognosis and then direct their care. Special ventilator modes can assist in ventilating burn patients with inhalation injuries that experience difficulties in oxygenating.

SUMMARY

Inhalational injuries are a significant source of morbidity and mortality in thermally injured patients. Treatment modalities, such as modified ventilator settings, alteration in fluid resuscitation, and a standardized grading system may improve morbidity and mortality.

Assessing Hyperbaric Oxygen for Carbon Monoxide Poisoning in Trauma Patients: A Call for Representation in Future Studies

Although carbon monoxide (CO) poisoning presents infrequently, it is a consequential and serious component of burn-related injuries, especially those injured via structure fire. A multitude of retrospective reviews and prospective trials have attempted to establish evidence demonstrating the ideal modality for oxygen administration in CO-poisoned patients; however, a consensus recommendation has not been reached. Given that half of fire-related patients succumb to CO poisoning, this is an imperative area of research.

Laryngotracheal stenosis in burn patients requiring mechanical ventilation

Objective

To identify the incidence of laryngotracheal stenosis (LTS) in burn patients requiring mechanical ventilation at a regional academic burn center.

Methods

A retrospective review of all burn patients requiring endotracheal intubation or tracheostomy for airway management between 2003 and 2009 was performed. A group of trauma patients requiring similar airway instrumentation during the same period of time was used as a control.

Results

None of the trauma patients and 2 of the burn patients developed LTS. Both presented with stridor and were diagnosed within 2–5 weeks after extubation. One patient underwent successful carbon dioxide laser radial incision and dilation and continues to do well. The other patient failed endoscopic treatment and required T-tube placement. The incidence of LTS in burn patients requiring mechanical ventilation was 2.98% overall and 4.76% among those with inhalational injury.

Conclusions

Patients become symptomatic within weeks of the initial injury. Treatment is challenging and multiple surgical procedures are often required. A larger study is necessary to determine if the incidence is higher among burn patients.

Acute clinical manifestations in toxic smoke inhalation victims: systematic review of observational studies

Abstract Introduction: Lung injuries from toxic smoke inhalation are the main causes of death in fire victims; however, information regarding the acute effects on the respiratory system after smoke inhalation and its constituents in closed environments are still scarce in literature. Objective: To investigate the acute clinical manifestations observed in victims of smoke inhalation during enclosed-space fires by means of systematic review. Methods: A systematic search was conducted in the following databases: MEDLINE (via PubMed), Lilacs, Scopus and Web of Science. There were no appliedrestrictions in terms of thepublication date. In addition, a manual search was performed on the references of published studies. Observational studies assessing the prevalence of acute clinical manifestations in victims of toxic smoke inhalation in closed environments were included. Results: Of the 4,603 articles identified, eight were included, comprising a total of 233 patients. The signs and symptoms were identified and ranked according to frequency. Dyspnea (58.80%, six studies), carbonaceous sputum (54.51%, four studies), hoarseness (39.91%, three studies), wheezing (34.33%, five studies) and sore throat (33.90%, two studies) were the most frequent acute clinical manifestations of smoke inhalation. Besides these, chest pain and pulmonary edema were observed, respectively in 13.30%, 5.15% of the studies. Conclusion: The results suggest that dyspnea, carbonaceous sputum, hoarseness, wheezing and sore throat were the most frequent acute clinical manifestations in victims of smoke inhalation. Further studies of a higher level of evidence and greater methodological rigor are required.

Defining the criteria for intubation of the patient with thermal burns

OBJECTIVES

Recent studies demonstrate that burn patients are undergoing unnecessary intubations. We sought to determine the clinical criteria that predict intubations with benefit.

METHODS

This was a retrospective review of intubated adults admitted to our center with thermal burns 2008-2013. Criteria for intubation were defined as traditional criteria (suspected smoke inhalation, oropharynx soot, hoarseness, dysphagia, singed facial hair, oral edema, oral burn, non-full thickness facial burns), or ABA criteria as defined by the 2011 ABA guidelines (full thickness facial burns, stridor, respiratory distress, swelling on laryngoscopy, upper airway trauma, altered mentation, hypoxia/hypercarbia, hemodynamic instability). Patients with <26days free from mechanical ventilation (ventilator-free days (VFD)) out of 28, were deemed indicated long-term intubations. Those with ≥26 VFD were deemed unnecessary short-term intubations.

RESULTS

Of 218 patients, 151 had long-term and 67 had short-term intubations. Long-term intubation was strongly associated with ABA criteria (77.5%) compared to traditional criteria (22.5%) (p<0.001). Sensitivity of ABA criteria for long-term intubation was 77% and specificity 46%. Traditional criteria associated with long-term intubation included suspected smoke inhalation (OR 2.45 [95% CI, 1.18-5.11]), and singed facial hair (OR 2.53 [95% CI, 1.25-5.09]). The addition of these to ABA criteria created the Denver criteria, which exhibited an increased sensitivity for long-term intubations (95%), but decreased specificity (24%).

CONCLUSIONS

Intubation should be considered for patients displaying the Denver criteria, which includes full thickness facial burns, stridor, respiratory distress, swelling on laryngoscopy, upper airway trauma, altered mentation, hypoxia/hypercarbia, hemodynamic instability, suspected smoke inhalation, and singed facial hair. Patients lacking these criteria should not be intubated.

Inhalation injury caused by cornstarch dust explosion in intubated patients-A single center experience

BACKGROUND

Around 10%-20% of burned patients have inhalation injuries, and the severity of these injuries is correlated with mortality. Fiberoptic bronchoscopy is an important tool for the early diagnosis of inhalation injury. This study investigated correlations between the severity of inhalation injury and outcomes of patients involved in a cornstarch dust explosion in northern Taiwan in 2015.

METHODS

Patients with burns who were intubated after the explosion were enrolled. Their medical records were reviewed, and data including patient characteristics, percentage of total body surface area (%TBSA) burned, severity of the inhalation injury, mechanical ventilation settings, and outcomes were collected and analyzed.

RESULTS

Twenty patients underwent fiberoptic bronchoscopy during the first 24h to evaluate an inhalation injury. Their mean age was 22.4±5.5 years and the mean %TBSA burned was 55.7±19.4%. Fourteen patients had a grade 1 inhalation injury and six had a grade 2 injury. There was a higher %TBSA burned in the grade 1 group than in the grade 2 group, although the difference did not reach statistical significance (60.0±20.3% versus 45.5±13.5%, p=0.129). Compared to the grade 2 group, the grade 1 group had a significantly higher white blood cell count (29.4±9.3 versus 18.6±4.6, p=0.015) and frequency of facial burns (85.7% versus 33.3%, p=0.037). The overall intensive care unit mortality rate was 10% (n=2), with no significant intergroup difference (grade 1, 14.3% versus grade 2, 0%, p=0.192).

CONCLUSION

Although the explosion resulted in a high rate of inhalation injuries in critically ill patients, there was no significant correlation between mortality and the severity of the inhalation injuries.

Indications of early intubation for patients with inhalation injury

Aim

For patients with inhalation injury, the indications for early intubation are diverse. The purpose of this study was to identify the most reliable symptoms, physical findings, and medical examinations with which to determine the indications for early intubation in patients with inhalation injury.

Methods

We retrospectively collected patient data from medical records. Collected data included age, sex, burn size, symptoms, physical findings, carboxyhemoglobin levels (COHb), and bronchial wall thickness (BWT) determined from chest computed tomography images. We analyzed the relationships between these findings and the early intubation. We performed fiberoptic bronchoscopy in all patients, and analyzed the relationships between bronchoscopic severity and other findings.

Results

Of the 205 patients, 80 patients were diagnosed as having inhalation injury, and 34 patients were intubated. Burn size, facial burns, neck burns, use of accessory respiratory muscles, and COHb seemed to be related with intubation, whereas singed nasal hair was not. If the patients suffered ≥27% total body surface area burn and BWT ≥3.5 mm, the positive predictive value for early intubation was 1.00. If the patients suffered smaller cutaneous burn without neck burn, and their COHb <4.0%, the negative predictive value for early intubation was 0.97. Fiberoptic bronchoscopy findings from above the glottis were mainly related with patients’ symptoms. Findings from below the glottis were mainly related with BWT and COHb.

Conclusions

Patients’ symptoms, especially use of accessory respiratory muscles, are reliable, and BWT and COHb are also useful tools, for determining the indication for early intubation.

Pneumologie

Die Pneumologie und Beatmungsmedizin gehört zur Basis der Intensivmedizin. Die Abklärung der Dyspnoe, das Management des Asthma bronchiale, der akuten COPD-Exazerbation und des akuten Lungenversagens (ARDS) bilden die Säulen dieses Kapitels. Im Rahmen der bettseitigen Abklärung der Dyspnoe gewinnt die Lungen- bzw. Thoraxsonographie zunehmend an Bedeutung.

Incidence of ventilator associated pneumonia in burn patients with inhalation injury treated with high frequency percussive ventilation versus volume control ventilation: A systematic review

BACKGROUND

Pneumonia increases mortality in burn patients with inhalation injuries. We evaluated whether the use of High Frequency Percussive Ventilation (HFPV) in burn patients with inhalation injuries can decrease rates of Ventilator Associated Pneumonia (VAP) compared to Volume Control Ventilation (VCV).

METHODS

Data were gathered from PubMed, EMBASE, Web of Science, reference lists, and hand search. For unpublished data we searched ClinicalTrials.gov and RePORTER. We included observational and Randomized Controlled Trials (RCTs) that compared rates of VAP with the use of HFPV and VCV in adult burn patients with inhalation injury. Two reviewers independently extracted data from the retrieved studies and assessed them for eligibility, methodology, and quality.

RESULTS

281 abstracts were reviewed, of which 4 studies (540 patients) were included. Two were observational and two were RCTs. All studies had moderate risk of bias. One study had low external validity while others had moderate external validity. The two observational studies found non-concordant results. One study found a 24% statistically significant reduction in the rates of VAP while the other found no difference. The two RCTs had small sample sizes. There was no significant difference in VAP rates between HFPV and VCV. The VCV arms of the four studies were heterogeneous. Only one study used low tidal volumes, whereas the rest used high tidal volumes in the VCV arm.

CONCLUSION

Evidence about decreased incidence of VAP in burn patients with inhalation injuries who are on HFPV compared to those on VCV is inconclusive. Although enhanced airway clearance by HFPV was thought to play a role in decreasing VAP in this population, high tidal volume in the VCV arms could be a confounding factor that should be eliminated in future studies before a firm conclusion can be reached. More RCTs comparing HFPV to low tidal volume VCV are needed.

Tracheobronchial polyps following thermal inhalation injury

The early pulmonary consequences of inhalation injury are well documented; however, little is known about delayed pulmonary complications following thermal inhalation injury. Although thermal injury below the vocal cords is rare because of effective heat dissipation in the upper airway, inflammatory endobronchial polyps have previously been reported as a delayed complication associated with inhalation injury. We report an extraordinary case of tracheobronchial polyps in patients with smoke inhalation injury. This report shows the delayed development and natural course of tracheobronchial polyps following thermal injury.

[Dermal and inhalation poisoning. Rare guests in our intensive care units?]

Patients with dermal and inhalation poisoning are uncommon in intensive care treatment. We describe the diagnostics and specific toxicological treatment of patients with hydrofluoric acid burns. For inhalation poisoning, we focus on smoke inhalation, especially the management of cyanide and carbon monoxide poisoning. Special attention is given to the use of hyperbaric oxygenation for the treatment of carbon monoxide poisoning.

Tongue protrusion as an indicator of vital burning

In the forensic assessment of burned bodies, the question of whether the victim was exposed to the fire before or after death is of crucial importance. Several external signs have been used in the past to indicate heat exposure prior to the death of the victim but these did not include tongue protrusion. The internal signs of heat exposure are generally regarded as much more important than those observed externally. No one factor has been found to be totally reliable. This study found a statistically significant dependence between tongue protrusion and presence of soot in the respiratory tract and stomach, the latter being a good indicator of vital burning. The results of this study confirm that tongue protrusion can be used as an additional indicator of vital burning.

Ventilator-associated pneumonia in burn patients: a cause or consequence of critical illness?

Infectious complications are a constant threat to thermally injured patients during hospitalizations and are a predominant cause of death. Most of the infections that develop in burn patients are nosocomial and of a pulmonary etiology. The bacteria that cause ventilator associated pneumonia (VAP) take advantage of the fact that uniquely among intensive care unit patients endotracheal intubation allows them a 'free' passage to the sterile lower airways; however, the combination of severe thermal injury (systemic immunosuppression) and inhalation injury (local immunosuppression and tissue injury) create an ideal environment for development of VAP. Thus, strategies directed at preventing and treating VAP in burn patients must address not only rapid extubation and VAP prevention bundles known to work in other intensive care unit populations, but therapies directed to more rapid wound healing and restoration of pulmonary patency.

Intermediate filament carbonylation during acute acrolein toxicity in A549 lung cells: functional consequences, chaperone redistribution, and protection by bisulfite

Extensive protein carbonylation accompanies cellular exposure to acrolein, a ubiquitous smoke constituent implicated in life-threatening pulmonary edema in fire victims, a condition involving rapid erosion of the "watertight" properties of respiratory epithelium. Since the identities of lung epithelial proteins that sustain carbonylation by acrolein are unknown, we sought to identify significant targets in subcellular fractions from A549 cells after 30 min exposure to either subtoxic or acutely toxic acrolein concentrations (60 or 360 fmol acrolein/cell). The lower concentration mainly modified cytosolic proteins while the higher concentration also damaged nuclear, membrane, and cytoskeletal proteins. The multifunctional intermediate filament proteins vimentin, keratin-18, keratin-7 and keratin-8, were conspicuous targets. Consistent with their mechanical functions, a loss of cellular adhesive strength accompanied adduction of the two most abundant intermediate filaments in A549 cells, keratins-8 and -18. Acrolein also elicited redistribution of several chaperones (Hsp40, -70, -90, and -110) to intermediate filament fractions, suggesting chaperone-mediated autophagy contributes to the triage of acrolein-adducted proteins. The carbonyl scavenger bisulfite suppressed acrolein toxicity, intermediate filament adduction, vimentin cross-linking, Hsp90 redistribution, and loss of cellular adhesive strength, while also suppressing vimentin hyperphosphorylation. These novel observations identify intermediate filaments as key targets for the reactive smoke constituent acrolein.

Toxicity of smoke extracts towards A549 lung cells: role of acrolein and suppression by carbonyl scavengers

The noxious 3-carbon electrophile acrolein forms on combustion of diverse organic matter including synthetic polymers such as polyethylene. While known to play a key role in smoke inhalation injury (SII), the molecular basis for the pulmonary toxicity of high dose acrolein-containing smoke is unclear. As a result, drug interventions in SII are poorly directed against pathogenetic smoke toxicants such as acrolein. The first aim of this study was to confirm a role for acrolein in the acute toxicity of smoke extracts towards A549 lung cells by monitoring adduction of known acrolein targets and the expression of acrolein-inducible genes. A second aim was to evaluate carbonyl scavengers for their abilities to protect cell targets and block smoke extract toxicity. Extracts were prepared by bubbling smoke released by smouldering polyethylene through a buffered saline-trap. Acrolein levels in the extracts were estimated via HPLC after derivatisation with 2,4-dinitrophenylhydrazine. Extracts were highly toxic towards A549 cells, eliciting greater ATP depletion than an equivalent concentration of acrolein alone. The toxicity was accompanied by pronounced carbonylation of several cytoskeletal targets, namely vimentin and keratins-7, -8 and -18. Western blotting revealed that polyethylene combustion products also upregulated several acrolein-responsive protein markers, including GADD45beta, NQO1, HMOX, Hsp70, Nur77 and Egr1. Several carbonyl scavengers (bisulfite, d-penicillamine, hydralazine and 1-hydrazinoisoquinoline) strongly attenuated smoke extract toxicity, with bisulfite suppressing both the adduction and cross-linking of intermediate filament targets. Bisulfite also suppressed the cytotoxicity of smoke extracts when detected using real-time monitoring of cellular impedance. These findings confirm a key role for acrolein in smoke cytotoxicity and suggest drugs that block acrolein toxicity deserve further investigation as possible interventions against SII.

Early and late complications among 15 victims exposed to indoor fire and smoke inhalation

AIM

To evaluate early and late complications among victims exposed to indoor fire and smoke inhalation.

METHOD

An observational, descriptive and prospective longitudinal study of 15 victims of smoke inhalation admitted to the intensive care unit.

RESULTS

Although without significant burns, 13 of the victims were unconscious, with airway injury, abnormal temperature and hypokalaemia, and underwent mechanical ventilation. Initial carbon monoxide concentration averaged 20.4+/-8.3%, dropping to 3.9+/-3.3% 4h later. On the 1st day, two victims recovered and were transferred, and another two died. Creatine kinase levels (2594+/-2455 U/l) correlated with duration of intensive care. Of the remaining 11 patients, 10 had early pneumonia. Steroid treatment was initiated for four patients receiving prolonged mechanical ventilation, because of persistent fever and dry cough without evidence of infection.

CONCLUSIONS

Mortality and systemic involvement were related to burn of the upper airway and contact with combustion products. Initial creatine kinase levels emerged as a prognostic marker of injury severity. Bronchoscopy was useful in grading airway injury and obtaining bronchoalveolar culture. Corticosteroids were effective, after the acute phase, in treating non-infectious pulmonary complications.

Management of burn wounds in the emergency department

This article makes some introductory comments on the histology of the skin and the pathophysiology of burn injury as these topics pertain to the estimation of the depth of the burn injury. The definition of a major burn and the salient points of its treatment are covered. In addition, some general comments are made about several special injuries for which burn center referral usually is sought. Finally, guidance is given in the selection and treatment of patients who have burns that may be treated on an outpatient basis.

Heavy smoking and liver

Smoking causes a variety of adverse effects on organs that have no direct contact with the smoke itself such as the liver. It induces three major adverse effects on the liver: direct or indirect toxic effects, immunological effects and oncogenic effects. Smoking yields chemical substances with cytotoxic potential which increase necro-inflammation and fibrosis. In addition, smoking increases the production of pro-inflammatory cytokines (IL-1, IL-6 and TNF- alpha) that would be involved in liver cell injury. It contributes to the development of secondary polycythemia and in turn to increased red cell mass and turnover which might be a contributing factor to secondary iron overload disease promoting oxidative stress of hepatocytes. Increased red cell mass and turnover are associated with increased purine catabolism which promotes excessive production of uric acid. Smoking affects both cell-mediated and humoral immune responses by blocking lymphocyte proliferation and inducing apoptosis of lymphocytes. Smoking also increases serum and hepatic iron which induce oxidative stress and lipid peroxidation that lead to activation of stellate cells and development of fibrosis. Smoking yields chemicals with oncogenic potential that increase the risk of hepatocellular carcinoma (HCC) in patients with viral hepatitis and are independent of viral infection as well. Tobacco smoking has been associated with suppression of p53 (tumour suppressor gene). In addition, smoking causes suppression of T-cell responses and is associated with decreased surveillance for tumour cells. Moreover, it has been reported that heavy smoking affects the sustained virological response to interferon (IFN) therapy in hepatitis C patients which can be improved by repeated phlebotomy. Smoker's syndrome is a clinico-pathological condition where patients complain of episodes of facial flushing, warmth of the palms and soles of feet, throbbing headache, fullness in the head, dizziness, lethargy, prickling sensation, pruritus and arthralgia.

Lesão por inalação de fumaça

A lesão inalatória é hoje a principal causa de morte nos pacientes queimados, motivo pelo qual se justifica o grande número de estudos publicados sobre o assunto. Os mecanismos envolvidos na gênese da lesão inalatória envolvem tanto os fatores de ação local quanto os de ação sistêmica, o que acaba por aumentar muito as repercussões da lesão. Atualmente, buscam-se ferramentas que permitam o diagnóstico cada vez mais precoce da lesão inalatória e ainda estratégias de tratamento que minimizem as conseqüências da lesão já instalada. Esta revisão aborda os mecanismos fisiopatológicos, os métodos diagnósticos e as estratégias de tratamento dos pacientes vítimas de lesão inalatória. Ressalta ainda as perspectivas terapêuticas em desenvolvimento.

Fiber-optic bronchoscopic classification of inhalation injury: prediction of acute lung injury

BACKGROUND

Fiber-optic bronchoscopy is widely used for the early diagnosis of inhalation injury. However, there is no current bronchoscopic classification of inhalation injury for the prediction of acute lung injury (ALI). Our goal was to devise such a classification.

METHODS

Between February 1993 and January 2002, 167 patients with highly suspicious inhalation injuries were collected. All patients received fiber-optic bronchoscopy within 24 h after their accident. In total, 108 patients were diagnosed as positive under direct inspection. The patients were divided into three groups (G(1), G(2), and G(3)) according to the depth of mucosal damage. Six patients were found to be positive by biopsy and were assigned to group Gb. Of these 114 positive cases, 27 developed ALI. Meanwhile, 53 patients were diagnosed as negative; these patients were assigned to group G(0).

RESULTS

After analysis, the following results were noted: G(0) (n = 53), two ALI (3.8%); G(1) (n = 49), two ALI (4%); G(2) (n = 46), 15 ALI (33%); G(3)(n = 13),10 ALI (77%); Gb (n = 6), no ALI. We discovered that the deeper the mucosal injuries, the higher the rate of ALI. There were no deaths related to the procedure.

CONCLUSIONS

Fiber-optic bronchoscopy is a safe and effective method for the early diagnosis of inhalation injuries. Also, it is a good predictor of ALL. We hope that in the near future, this classification will serve as a treatment guideline for the early prevention of ALI. The more severe the damage, the more alert clinicians need to be to improve the patient's chances for survival.

Alterations in regional ventilation, perfusion, and shunt after smoke inhalation measured by PET

Regional changes in ventilation and perfusion occurring in the early hours after smoke inhalation injury were evaluated through the use of positron emission tomography. Five lambs were imaged before and 1, 2, and 4 h after receiving 100 breaths of cotton smoke. Utilizing a recently developed model of (13)N tracer kinetics (3), we evaluated changes in ventilation, perfusion, shunt, and regional gas content in nondependent, middle, and dependent lung zones. The data demonstrated a progressive development of regional shunt in dependent (dorsal) regions in which perfusion remained the highest throughout the study. These findings, together with decreasing regional ventilation and fractional gas content in the dependent regions, correlated with decreasing arterial Pa(O(2)) values over the course of the study. A negative correlation between regional shunt fraction and regional gas content in dependent and middle regions suggests that shunt was caused by progressive alveolar derecruitment or flooding.

Carbon monoxide poisoning--a public health perspective

Carbon monoxide (CO) may be the cause of more than one-half of the fatal poisonings reported in many countries; fatal cases also are grossly under-reported or misdiagnosed by medical professionals. Therefore, the precise number of individuals who have suffered from CO intoxication is not known. The health effects associated with exposure to CO range from the more subtle cardiovascular and neurobehavioral effects at low concentrations to unconsciousness and death after acute or chronic exposure to higher concentrations of CO. The morbidity and mortality resulting from the latter exposures are described briefly to complete the picture of CO exposure in present-day society. The symptoms, signs, and prognosis of acute CO poisoning correlate poorly with the level of carboxyhemoglobin (COHb) measured at the time of hospital admission; however, because CO poisoning is a diagnosis frequently overlooked, the importance of measuring COHb in suspicious settings cannot be overstated. The early symptoms (headache, dizziness, weakness, nausea, confusion, disorientation, and visual disturbances) also have to be emphasized, especially if they recur with a regular periodicity or in the same environment. Complications occur frequently in CO poisoning. Immediate death is most likely cardiac in origin because myocardial tissues are most sensitive to the hypoxic effects of CO. Severe poisoning results in marked hypotension, lethal arrhythmias, and electrocardiographic changes. Pulmonary edema may occur. Neurological manifestation of acute CO poisoning includes disorientation, confusion, and coma. Perhaps the most insidious effect of CO poisoning is the development of delayed neuropsychiatric impairment within 2-28 days after poisoning and the slow resolution of neurobehavioral consequences. Carbon monoxide poisoning during pregnancy results in high risk for the mother by increasing the short-term complication rate and for the fetus by causing fetal death, developmental disorders, and chronic cerebral lesions. In conclusion, CO poisoning occurs frequently; has severe consequences, including immediate death; involves complications and late sequelae; and often is overlooked. Efforts in prevention and in public and medical education should be encouraged.

Facial burns in children: a series analysis with implications for resuscitation and forensic odontology

This study comprises a continuous (1981-1995) unselected series of all children who died from thermal injuries in the State of Queensland, Australia. One hundred and six children, so identified, died from incineration (35 per cent), respiratory burns with smoke or carbon monoxide inhalation (33 per cent), body surface area burns comprising greater than 60 per cent (9 per cent) and electrocution (20 per cent). The burn fatality rate was 0.98 per hundred thousand children (0-14 years) per year, with no secular trend and, specifically, no reduction in the annual rate of such fatalities. Eighty-two children (49 males) had concomitant facial injuries, both thermal and nonthermal; of whom 55 per cent were under the age of five years. Sixty (73 per cent) child burn victims died in house fires. Forensic odontology is important in confirming the age of such victims in single incinerations but is of limited value when larger numbers of children are incinerated, because of the relative lack of dental restorations in the infant and pre-school age group. Of the 82 children with facial and airway injuries, 12 per cent had only mild or superficial facial damage and only seven (8 per cent) were alive or resuscitable at the time of rescue from the conflagration or burning injury. child deaths from burns contributed an annual loss rate of 506 years of potential life lost (YPLL) in a population of 3 million of whom 21.5 per cent were children under the age of 15 years. Airway management and resuscitation, in the context of managing surviving burn victims of any age with facial injuries, pose special difficulties. Inhalational burns (smoke and the gases of conflagration) result in a mortality greater than 60 per cent. Although 81 per cent of children showed evidence of airway obstruction, analysis of current data indicates that a maximum of 8 per cent could have survived with airway maintenance and protection. Inhalational burns (to both upper and lower airways) grossly reduce survivability. Primary prevention would seem vital and thus remains a major challenge to reduce the incidence of such deaths. Some strategies include advocacy to promote the compulsory installation of smoke alarms, family drills to practise escape and the teaching of 'first aid for all'

Smoke inhalation injury

Pulmonary injury due to smoke inhalation is a significant cause of death in fire victims. Singed nasal hair and carbonaceous sputum are easily recognized warning signs, but other subtle clues should prompt thorough evaluation and aggressive treatment. Dr Lee-Chiong describes the basic mechanisms of injury and discusses how to assess and manage complications caused by smoke inhalation.

Carbon monoxide poisoning: a review for clinicians

Carbon monoxide (CO) poisoning continues to be a significant health problem both in the United States and in many other countries. CO poisoning is associated with a high incidence of severe morbidity and mortality. Epidemics of CO poisoning commonly occur during winter months and sources include: smoke from fires, fumes from heating systems burning fuels, and exhaust fumes from motor vehicles. The history of exposure and carboxyhemoglobin levels should alert the physician to this diagnosis. In the absence of exposure history, CO poisoning should be considered when two or more patients are simultaneously sick. The clinical presentation is non-specific and may range from nausea and headache to profound central nervous system dysfunction. The mainstay of therapy for CO poisoning is supplemental oxygen, ventilatory support, and monitoring for cardiac dysrhythmias. This article reviews up-to-date information of this potentially devastating exposure.

Cardiopulmonary resuscitation: a review for clinicians

Attempts at cardiopulmonary resuscitation (CPR) date from antiquity, but it is only in the last 50 years that a scientifically-based methodology has been developed. External chest compressions is the standard method for managing circulatory arrest, however, numerous alterations of this technique have been proposed in attempts to improve outcome from CPR. Defibrillation is the single most important therapy for the management of ventricular fibrillation or pulseless ventricular tachycardia. Adrenergic agents used to improve myocardial and cerebral perfusion are also the subject of considerable investigation with new agents entering clinical study. This paper reviews the history, current techniques and pharmacotherapy as well as controversial issues in the management of patients with cardiac arrest.

Early complications and value of initial clinical and paraclinical observations in victims of smoke inhalation without burns

OBJECTIVE

To evaluate the incidence of early pulmonary complications and the value of initial clinical signs and paraclinical investigations in victims of smoke inhalation not suffering from burns following structural fires.

DESIGN

Retrospective chart review.

SETTING

Thirteen-bed ICU.

PATIENTS

Sixty-four victims of smoke inhalation following household fires were admitted to the ICU between January 1987 and December 1992. Exclusion criteria from the study were patients with cutaneous burns or multiple trauma or blast injury, and patients found in cardiac arrest.

METHODS

Clinical, biological, and radiologic parameters were collected over a 5-day period.

RESULTS

The mortality rate in relation to progressive respiratory failure was 3.1%. Mean ICU stay was 5.8 days (range, 1 to 33 days), and was longer in the patients presenting with soot deposits in the oropharynx (p = 0.02), dysphonia (D) (p = 0.05), or ronchi (R) (p = 0.0004) at the first examination, and in those having a positive sputum bacteriologic analysis (p = 0.003) or requiring parenteral bronchodilator agents for more than 24 h (p = 0.04). Thirty-five patients underwent mechanical ventilation (MV) for a mean of 101.2 h (range, 8 to 648 h). Mean MV duration was higher in the patients presenting initially with R (p = 0.003), high carbon monoxide (but not cyanide) levels (p = 0.02), or a positive bacteriologic sample (p = 0.0001). Positive bacteriologic sampling correlated with the presence of D (p = 0.02) or R (p = 0.04) and with immediate intubation (p = 0.0003). No correlation was found with chest radiograph.

CONCLUSIONS

In this selected series of fire victims without cutaneous burns, respiratory injury was frequent. The initial clinical signs may be helpful to predict pulmonary complications.

The World Trade Center bombing: injury prevention strategies for high-rise building fires

The WTC disaster provided an opportunity to look for ways to prevent morbidity among occupants of high-rise buildings during fires. This paper first describes the overall morbidity resulting from the explosion and fire, and second, presents the results of a case-control study carried out to identify risk factors for smoke-related morbidity. The main ones include: increased age, presence of a pre-existing cardio-pulmonary condition, entrapment in a lift and prolonged evacuation time. Study results point to the importance of the following safety systems during high-rise building fires: smoke-control systems with separate emergency power sources; lift-cars, lift-car position-monitoring systems, and lift-car communication systems with separate emergency power sources; two-way emergency communication systems on all floors and in stairwells; stairwells with emergency lighting and designed for the rapid egress of crowds; evacuation systems/equipment to assist in the evacuation of vulnerable people (elderly, infirm). Also important are evacuation plans that include regularly scheduled safety training and evacuation drills.

Predictors of carbon monoxide and hydrogen cyanide exposure in smoke inhalation patients

OBJECTIVE

A prospective study of civilian (nonfirefighter) smoke inhalation patients was carried out to test the hypotheses that: 1) absorption of carbon monoxide and hydrogen cyanide from smoke can be predicted by clinical examination and historical data; and, more specifically 2) a history of exposure to burning synthetic polymers is an important predictor of systemic cyanide levels.

METHODS

The study was conducted over a three-year period at six urban hospitals. Patients with or without burns who were exposed to smoke within five hours of hospital arrival were sampled for carboxyhemoglobin, whole blood cyanide, urine cotinine and urine creatinine. Controls consisted of a smaller group of smoking status-matched, nonsmoke-exposed burn patients.

ANALYSIS

Historical information was obtained on SMOKING status, FIRETYPE (structural vs other), MATERIAL burned (natural vs synthetic) and LAGTIME (from exposure to sampling). A smoke inhalation SCORE (0-10) was assigned to each case, based on physical examination findings and changes on chest X ray, and carboxyhemoglobin and cyanide levels were entered into various multivariate linear regression models.

RESULTS

A total of 40 cases and 9 controls were recruited, ranging in age from 15 to 92 years. Thirty-four cases were discharged alive and six expired in-hospital. Observed carboxyhemoglobin levels ranged from 1.2% to 41.6% in cases (mean 8.6%), and from 0.5 to 7.3% in controls (mean 2.9%). Observed cyanide levels ranged from nondetectable (< 0.05 micrograms/mL) to 2.79 micrograms/mL in cases (mean 0.25 micrograms/mL), and from nondetectable to 0.11 micrograms/mL in controls (mean 0.03 micrograms/mL). Among cases, linear regression models explained up to 35% of the observed variance in carboxyhemoglobin levels (p < 0.001) and up to 48% of the variance in cyanide levels (p = 0.0001).

CONCLUSIONS

SCORE was the strongest predictor of both carboxyhemoglobin and cyanide levels; LAGTIME also explained significant variance for [log-transformed] carboxyhemoglobin. Historical factors, such as FIRETYPE, MATERIAL, and SMOKING status, did not explain significant variance in most of the statistical models employed.