Methylprednisolone does not protect the lung from inhalation injury

Análise do lavado broncoalveolar em vítimas de queimaduras faciais graves

OBJETIVO: Analisar o lavado broncoalveolar (LBA) de vítimas de queimaduras que inalaram fumaça a fim de identificar alterações que possam estar associadas à morte ou à sobrevida. MÉTODOS: Dezoito vítimas de queimaduras faciais foram submetidas a LBA até 24 h após o evento, sendo realizadas a análise do conteúdo celular e proteico, incluindo TNF-α, HLA-DR, CD14, CD68 e iNOS. RESULTADOS: Dos 18 pacientes submetidos à broncoscopia, 8 (44,4%) morreram durante o seguimento. A média de idade dos pacientes que morreram foi significativamente maior (44,7 vs. 31,5 anos). A superfície corporal queimada foi em média de 60,1% nos pacientes que morreram e de 26,1% nos sobreviventes (p < 0,0001). Entre os 18 pacientes submetidos à broncoscopia, 11 (61,1%) apresentaram sinais endoscópicos de lesão por inalação de fumaça, e 4 (36,4%) destes faleceram. Dos 7 pacientes sem sinais de lesão por inalação de fumaça, 4 (57,1%) faleceram. A média do número de células epiteliais ciliadas no LBA dos pacientes que morreram foi significativamente maior daquela dos sobreviventes (6,6% vs. 1,4%; p = 0,03). Os demais parâmetros analisados não mostraram diferença entre os grupos. CONCLUSÕES: A superfície corporal queimada mostrou ser um fator preditivo de mortalidade. O aumento do número de células epiteliais ciliadas no LBA, denotando descamação epitelial brônquica, esteve associado à maior mortalidade de pacientes com queimaduras faciais.

Thermal and electrical injuries

Through progress in wound management, resuscitation, intensive care treatment, and a coordinated rehabilitation process, modern burn care has been able to deliver substantial increases in survival and improvement in functional outcomes for burn victims. The development of regionalized burn centers has contributed greatly to this progress. As the field of burns matures, burn centers are preparing to meet future challenges through collaborative efforts in disaster management and outcomes research.

Smoke Inhalation

Unfortunately, fires are common events both in urban and rural portions of the United States. Smoke inhalation is the leading fire-related cause of death. The elemental combustion products of fire are light, heat, and smoke. Smoke is a very complex mixture of potentially harmful substances. Although a relatively rare presenting event to small animal hospitals, when animal fire victims do appear, clinicians must know how to recognize the signs of smoke inhalation and how to successfully deal with them. This discussion will investigate the toxic nature of fire smoke, its mechanism of action upon respiratory tissues, the clinical signs displayed, and its diagnosis and treatment. Differential diagnoses of smoke inhalation and prevention and prognosis will also be explored. Veterinary hospitals should have set protocols in place for managing animal victims of smoke inhalation in order to ensure a successful outcome.

[Primary treatment of burn patients]

Burn injuries can be caused by thermal, electrical, chemical, or mechanical trauma or radiation and are relatively rare, as they represent only about 1% of all emergencies. They are caused by accidents at home, during recreational activities, or in the occupational environment. Minor burn traumas are much more common than severe burn injuries with their systemic and potentially life-threatening effects. Altogether, these circumstances may result in a lack of routine for treating such injuries properly by physicians and their colleagues in the emergency room or intensive care unit. A clearly outlined concept for preclinical and clinical treatment can be the keystone of successful further clinical progress. The following article summarizes the current guidelines for first medical aid at the injury scene, burn stabilization and assessment in the emergency room, and the interdisciplinary approach for further clinical care. The treatment of dermatologic emergencies (acute epidermolytic syndromes) or caustic injuries by chemical agents is similar to the treatment of burn victims in many aspects but must be adapted in selected cases.

Is high PEEP low volume ventilation in burn patients beneficial? A retrospective study of 61 patients

In burn care lung damage by inhalation injury is a major cause of mortality in burn patients. In the field of intensive care medicine ventilation strategies to reduce lung injury caused by ventilation are under investigation. The promising results of the application of pressure controlled high PEEP low volume (HPLV) ventilation prompted us to use this ventilation strategy in our burn ICU. To establish whether this ventilation regime is beneficial the charts of 61 consecutive patients needing artificial respiration were reviewed. A scoring system for PEEP level and tidal volume was developed and treatment groups with high PEEP and low volume and low PEEP high volume regimes were compared. No statistically significant differences could be found when comparing treatment versus mortality, the number of pulmonary complications or incidence of pneumothoraces. However, the trend showed a benefit in mortality for patients with an ABSI scoring up to 9, but at the same time pulmonary complications increase. The Horovitz oxygenation index showed no advantage for the HPLV Group. In a separate analysis we found a significant correlation between absolute PEEP and mortality. The correlation between PEEP level and mortality is a dynamic factor predicting outcome, This not been described yet and can be an addition to the static ABSI score. Differences between ventilation strategies were not as evident as expected in this retrospective study, so prospective randomized studies are needed.

Acute inhalation injury

Recent events have underscored the importance of proper diagnosis and management of patients with inhalation injury. Clinicians who care for individuals who have sustained inhalation damage to their respiratory tract need to take a careful exposure history and be alert to possibilities of delayed effects and clinical deterioration. Although supportive care and prevention remain the cornerstone of current approaches to this condition, better understanding of the mechanisms of cellular injury and repair may lead to improved treatments in the future.

Segmental pulmonary vascular resistance following wood smoke inhalation

OBJECTIVES

To locate the specific site (i.e., pulmonary arteries, veins, or capillaries) of increased pulmonary vascular resistance after wood smoke inhalation and to demonstrate whether the prostanoids, thromboxane B2 or 6-keto-prostaglandin F1 alpha, play a role in these vascular resistance changes.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Laboratory at a university medical center.

SUBJECTS

Five mongrel dogs.

INTERVENTIONS

The isolated canine left lower lobe preparation was used to measure changes in the pressure drop across the pulmonary arteries, veins, and capillaries. The left lower lobe was surgically isolated and perfused by a pump primed with autologous blood. The arterial and venous occlusion technique and the vascular pressure-flow relationship were used to assess changes in pulmonary vascular resistance. After baseline measurements, the left lower lobe was exposed to wood smoke for 2.5 mins and measurements were repeated.

MEASUREMENTS AND MAIN RESULTS

Smoke exposure caused an immediate (5 mins post-inhalation) increase in the total pressure gradient across the lobe (baseline = 9.8 +/- 0.5 torr [1.3 +/- 0.06 kPa]); smoke inhalation = 24.3 +/- 3.9 torr [3.24 +/- 0.5 kPa]; p < .05). Total pressure drop was partitioned longitudinally into pressure drops across arteries, veins, and the middle vessels. The increase in total pressure drop was associated with a moderate increase in the pressure drop across the middle vessels (baseline = 1.1 +/- 0.2 torr [0.14 +/- 0.02 kPa]; smoke inhalation = 5.2 +/- 1.1 torr [0.69 +/- 0.14 kPa]; p < .05); a large increase in the pressure drop across the veins (baseline = 4.8 +/- 1.3 torr [0.64 +/- 0.17 kPa]; smoke inhalation = 20.7 +/- 3.4 torr [2.7 +/- 0.45 kPa]; p < .05), and no significant change in the pressure drop across the arteries (baseline = 3.7 +/- 0.4 torr [0.49 +/- 0.05 kPa]; smoke inhalation = 4.8 +/- 0.5 torr [0.64 +/- 0.06 kPa]; p = NS). Increases in the pressure drop across the middle and venous vessels were transient and no longer significantly different from baseline 15 mins after smoke inhalation. Similarly, analysis of the pulmonary artery/blood flow data demonstrated that the mean slope and pressure intercept were greater than baseline only at 5 mins postsmoke inhalation (p < .05). Thromboxane B2 did not significantly change from baseline values after smoke exposure and prostaglandin F1 alpha demonstrated a slight but significant decrease 30 mins postsmoke. Pulmonary edema was measured gravimetrically (wet/dry weight ratio) and smoke significantly increased lung water in the left lower lobe (wet/dry weight ratio = 6.55 +/- 0.4) as compared with the normal left upper lobe (wet/dry weight ratio = 4.97 +/- 0.2).

CONCLUSIONS

We conclude that smoke causes an intense but transient increase in the pressure drop across the venous segment that may accelerate the formation of pulmonary edema, which is not mediated by changes in thromboxane B2 or prostaglandin F1 alpha.