ReviewInhalation injury: Pathophysiology and clinical care: Proceedings of a Symposium Conducted at the Trauma Institute of San Antonio, San Antonio, TX, USA on 28 March 2006
Introduction
Despite advances in critical care in general and in mechanical ventilation in particular, inhalation injury continues to impose an unacceptable burden of morbidity and mortality on burn patients. The recent conflict in Iraq has produced an increase in the number of patients with inhalation injury treated here at the U.S. Army Burn Center, and has led to new observations concerning the many complications of inhalation injury such as the risk of laryngeal sequelae. Meanwhile, ongoing research has continued to expand our understanding of the pathophysiology of inhalation injury. In March 2006, we conducted a multidisciplinary conference under the auspices of the Trauma Institute of San Antonio (TRISAT) which was broadcast from this center at the U.S. Army Institute of Surgical Research, via videoteleconference, to our sister institutions, Wilford Hall Medical Center and the University of Texas Health Science Center at San Antonio. Our purpose was to review both current clinical practice and recent laboratory investigations.
Section snippets
Ventilation–perfusion (V/Q) heterogeneity
Attempts to investigate ventilation–perfusion (V/Q) heterogeneity have been made for about 100 years and initially were based on calculations of the pulmonary venous admixture [1] and dead space ventilation [2], and assessment of regional distribution of blood flow and ventilation by radioactive tracer techniques [3], [4]. These methods unveiled considerable information on V/Q relationships, but were limited in resolution both at the lower and upper scales of the V/Q ratios [5].
Multiple Inert Gas Elimination Technique (MIGET)
With the
Oxidants affect the lining fluid of the respiratory tract where antioxidant concentrations vary
As it is currently understood, oxidants, such as inhaled components of smoke, gaseous air pollutants, particulate matter, or other toxicants, react first with the lining fluid that covers the surfaces of the respiratory tract. This lining fluid contains a number of compounds with antioxidant properties, both enzymatic and non-enzymatic, that serve as a major line of defense against oxidative injury [16]. However, the concentrations of these antioxidants vary along the respiratory tract such
Evaluation of CT scan in inhalation injury in an animal model
The presence of inhalation injury is currently diagnosed by bronchoscopy or by xenon lung scan. No method, however, is available for grading the severity of injury. The objective of this study [22] was to evaluate the utility of CT scan in assessing the severity of injury. Twenty anesthetized sheep evenly divided into 4 groups, consisting of controls, mild, moderate, and severe injuries, underwent inhalation of wood bark smoke. After injury, the sheep were mechanically ventilated for 48 h in the
Emergency ventilation with insufflated oxygen (Ian H. Black, MD)
Insufflation of oxygen has been used as a rescue technique for airway obstruction and as an adjunctive technique for acute lung injury (ALI). What is the rationale for tracheal gas insufflation, the efficacy of tracheal gas insufflation, and some of its problems in a clinical setting? Before addressing these questions it is important to clarify some nomenclature. Apneic oxygenation (AO) usually refers to supraglottic airway delivery. Tracheal insufflation of oxygen (TRIO) is either supra- or
Clinical care of patients with inhalation injury (Rubén Gómez, MD, PhD)
This section reviews the clinical care of patients with inhalation injury. Where appropriate, a rating for the quality of evidence is provided. Inhalation injury is present in 8–15% of burn-center admissions [37], was associated with a mean mortality of 56% in two large series [37], [38], and, when suspected, is considered one of the major criteria for burn-center referral according to the American Burn Association and the American College of Surgeons [39]. Inhalation injury below the glottis
Vocal cord paresis in lung injury
We present results of a recent evaluation of the laryngeal sequelae seen in burn patients. Upon request by burn-center surgeons, a total of 52 patients underwent evaluation by a speech pathologist at the U.S. Army Burn Center. Twenty-five of these were diagnosed with vocal-cord paresis. Patients who were intubated overseas (mostly patients from the current conflict in Iraq) had a 4.5-fold increase in the incidence of vocal-cord paresis. In addition, the risk of vocal-cord paresis increased with
Extracorporeal membrane oxygenation (ECMO)
Extracorporeal membrane oxygenation (ECMO) has been available for many years, but is costly and cumbersome. ECMO has a significant complication rate, and is labor- and equipment-intensive. Increasingly, instead of ECMO for the treatment of patients with ARDS, simpler technologies are being proposed. These include intravenous devices such as the Hattler catheter, and extracorporeal devices such as those for arteriovenous CO2 removal (AVCO2R) and the venovenous Paracorporeal Respiratory Assist
Inhalation injury: summary and conclusions (Steven E. Wolf, MD)
Inhalation injury is associated with increased mortality in burn patients [60]. Thus, inhalation injury is often included in multivariate predictors of burn mortality, along with factors such as burn size and age [61]. Clinically, however, the diagnosis of inhalation injury is very difficult. Dr. Park's data summarize what we know from clinical experience: that inhalation injury is readily managed unless the injury is severe, in which case mortality increases substantially [22].
Dr. Gomez gave a
Acknowledgements
The authors gratefully acknowledge Ms. Amy Newland for help in preparing this manuscript, and Ms. Gabrietta Roney and Josie Soliz for transcribing the proceedings.
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