The applications of hyperbaric oxygen therapy in emergency medicine

Damage of white matter tract correlated with neuropsychological deficits in carbon monoxide intoxication after hyperbaric oxygen therapy

Carbon monoxide (CO) intoxication can result in cognitive deficits and demyelinating changes of the white matter (WM), for which hyperbaric-oxygen (HBO) treatment is considered effective in reducing neuropsychiatric symptoms. This study aimed to analyze cognitive functions and WM diffusion properties in CO intoxication after standard HBO treatment. Seventeen CO intoxicated patients were evaluated 4-6 months after HBO treatment. They also underwent diffusion tensor imaging (DTI) and cognitive assessment, and the results were compared with those from 34 age-matched controls. DTI was transformed into fractional anisotropy (FA) and mean diffusivity (MD) and assessed at every voxel level with tract-based spatial statistics across the brain. Correlation between reduced FA and increased MD with neuropsychological deficits were performed. Cognitive results showed that impairment in executive function, as well as verbal and visual memories, were most prominent. There were extensive areas of increased MD and decreased FA. Correlation analyses showed that memory retrieval, judgment, and verbal generation tasks were related to FA of the frontotemporal WM. MD showed weaker correlation with cognitive deficits. These data suggest that neurologic deficits and WM changes are detectable 4-6 months after HBO therapy. The correlation of WM diffusion with cognitive deficits also suggests that reduced connectivity between different cortical regions is a pathophysiologic mechanism.

Pyridoxine does not prevent hyperbaric oxygen-induced seizures in rats

Normobaric supplemental oxygen can prolong seizures not caused by hyperbaric oxygen therapy. In addition, hyperbaric oxygen therapy can cause seizures. The mechanism of hyperbaric oxygen-induced seizures is unknown. We hypothesized that pretreatment with pyridoxine may delay the onset of hyperbaric oxygen-induced seizures, recognizing that pyridoxine is already an antidote for some epileptogenic poisons such as isoniazid and monomethylhydrazine. Therefore, rats were pretreated with intraperitoneal injections of pyridoxine at 48, 24, and 2 h before undergoing hyperbaric oxygen (HBO) treatment at 3 atmospheres absolute with 100% oxygen and were compared to a control group of HBO-treated rats for time to onset of seizures. There was no difference in onset of seizure time between the pyridoxine-treated group of rats and the control rats. Supplemental pyridoxine pretreatment did not alter the time to onset of seizures during HBO treatment in this study.

Cyanides

Cyanide is a likely weapon for terrorists due to its notoriety, lethality, and availability. Poisoning results in central nervous system and cardiovascular dysfunction due to inhibition of oxidative phosphorylation. Laboratory findings of anion gap metabolic acidosis and hyperlactemia aid in confirming the diagnosis. Treatment for significant poisonings includes aggressive supportive care and administration of antidotes such as sodium nitrite, sodium thiosulfate, and hydroxocobalamin. Survivors of significant poisonings can have long-term neurologic dysfunction.

Cyanide poisoning and its treatment

Cyanide is both widely available and easily accessible throughout the world. Although the compound is not frequently encountered, it has been used as a poison and contaminant in the past and is a potential terrorist agent. Cyanide has the ability to cause significant social disruption and demands special attention to public health preparedness. It can be obtained from a variety of sources, including industrial, medical, and even common household products. Another frequently encountered source of cyanide exposure is residential fires. Exposure to high concentrations of the chemical can result in death within seconds to minutes. Long-term effects from cyanide exposure can cause significant morbidity. The only treatment for cyanide toxicity approved for use in the United States is a kit consisting of amyl nitrite, sodium nitrite, and sodium thiosulfate. Future research aims to find a faster-acting, more effective, and better tolerated treatment for cyanide toxicity.

Burns

During the past 20 yrs, as burn care has evolved as a specialty of surgery, survival and outcome quality have soared. Public expectations for survival and long-term outcomes are at previously unprecedented levels. These changes are the result of a number of advances in aspects of burn care that have occurred in parallel and have fostered increasing regionalization of this resource-intensive activity into fewer specialized centers. These are complex hospitalizations and can be divided into four phases: initial evaluation and resuscitation, initial wound excision and biological closure, definitive wound closure, and rehabilitation and reconstruction.

Hyperbaric oxygen in trauma and surgical emergencies

Hyperbaric oxygen therapy (HBO), that is the administration of 100% oxygen delivered under pressure, has a beneficial effect in several surgical conditions. Its use has been assessed and audited and its pharmacological effects demonstrated. It is appropriate for use in several acute surgical conditions as evidence-based therapy. These are: Gas Gangrene Crush Injuries, Compartment Syndromes & Acute Traumatic Ischaemias Enhancement of Healing in Selected Problem Wounds Exceptional Blood loss Anaemia Necrotising Soft Tissue Infections Compromised Skin Grafts & Flaps Thermal Burns HBO therapy suffers from previous inappropriate use, lack of knowledge, and scarce hyperbaric facilities. Hyperbaric therapy, when properly supervised by a physician trained in its use, working closely with a surgeon, and ethically used for appropriate indications, can be a useful adjunct to surgical practice. Military surgeons may be in a situation in which they can utilize HBO in acute surgical conditions and trauma. They are urged to identify HBO facilities, both fixed and portable, and to establish communication with hyperbaric therapy colleagues.

Necrotizing soft-tissue infections

Necrotizing soft-tissue infections may be rapidly fatal because of toxin-induced circulatory collapse. Because of the often nonspecific clinical presentation, prompt diagnosis may be difficult but is imperative as prompt treatment can be lifesaving. This article discusses necrotizing fasciitis and clostridial myonecrosis, and highlights pathogenesis, clinical presentation, diagnosis, and treatment.

Overwhelming Sepsis and Bleeding in a Previously Splenectomized Patient

The occurrence of overwhelming sepsis due to Streptococcus pneumoniae infection is a rare but well- known complication of splenectomy. Its occurrence 31 years postsplenectomy in a 35-year-old woman is the sub ject of this report. In spite of septic shock, disseminated intravascular coagulation, adult respiratory distress syn drome, gastrointestinal hemorrhage, and digital gangrene, the patient recovered with only minimal loss of parts of digits. The use of high-dose penicillin empirically in the emergency room along with liberal use of resuscitative fluids and dopamine may have been the major determi nants of her recovery. Intravenous corticosteroids, fresh- frozen plasma, and packed red blood cells appeared to be beneficial as well. A diagnosis of hereditary spherocyto sis was made following recovery. This case is discussed in the light of guidelines for prophylaxis of overwhelming sepsis in high-risk patients issued by the Centers for Dis ease Control of the National Institute of Health. Vacci nation with pneumococcal vaccine (23 valent) and men ingococcal vaccine is highly recommended for adults at high risk of overwhelming sepsis. This treatment should be repeated every 6 years. It is critical that the patient, the doctor, and emergency room physicians be aware of the importance of prompt aggressive antibacterial treat ment for any suspected infection.

Objectives to direct the training of emergency medicine residents on off-service rotations: hyperbaric medicine

Objectives for Emergency Medicine residents on Hyperbaric Medicine rotations is the 22nd article in this continuing series of "off-service" goals and objectives. The role of the emergency medicine physician in hyperbaric treatment is evolving as part of a multidisciplinary approach to patients with widely divergent disease states who may benefit from serum hyperoxia and compression. Therefore, emergency residents with interests in this area will benefit from clear goals and objectives during a 2 to 4-week Hyperbaric Medicine Elective.