The Critical Assessment of Oxidative Stress Parameters as Potential Biomarkers of Carbon Monoxide Poisoning.

In conventional clinical toxicology practice, the blood level of carboxyhemoglobin is a biomarker of carbon monoxide (CO) poisoning but does not correspond to the complete clinical picture and the severity of the poisoning. Taking into account articles suggesting the relationship between oxidative stress parameters and CO poisoning, it seems reasonable to consider this topic more broadly, including experimental biochemical data (oxidative stress parameters) and patients poisoned with CO. This article aimed to critically assess oxidative-stress-related parameters as potential biomarkers to evaluate the severity of CO poisoning and their possible role in the decision to treat. The critically set parameters were antioxidative, including catalase, 2,2-diphenyl-1-picryl-hydrazyl, glutathione, thiol and carbonyl groups. Our preliminary studies involved patients (n = 82) admitted to the Toxicology Clinical Department of the University Hospital of Jagiellonian University Medical College (Kraków, Poland) during 2015-2020. The poisoning was diagnosed based on medical history, clinical symptoms, and carboxyhemoglobin blood level. Blood samples for carboxyhemoglobin and antioxidative parameters were collected immediately after admission to the emergency department. To evaluate the severity of the poisoning, the Pach scale was applied. The final analysis included a significant decrease in catalase activity and a reduction in glutathione level in all poisoned patients based on the severity of the Pach scale: I°-III° compared to the control group. It follows from the experimental data that the poisoned patients had a significant increase in level due to thiol groups and the 2,2-diphenyl-1-picryl-hydrazyl radical, with no significant differences according to the severity of poisoning. The catalase-to-glutathione and thiol-to-glutathione ratios showed the most important differences between the poisoned patients and the control group, with a significant increase in the poisoned group. The ratios did not differentiate the severity of the poisoning. The carbonyl level was highest in the control group compared to the poisoned group but was not statistically significant. Our critical assessment shows that using oxidative-stress-related parameters to evaluate the severity of CO poisoning, the outcome, and treatment options is challenging.

Extracorporeal membrane oxygenators with light-diffusing fibers for treatment of carbon monoxide poisoning: Experiments, mathematical modeling, and performance assessment with unit cells.

BACKGROUND AND OBJECTIVES: Approximately 50,000 emergency department visits per year due to carbon monoxide (CO) poisoning occur in the United States alone. Tissue hypoxia can occur at very low CO concentration exposures because CO binds with a 250-fold higher affinity than oxygen to hemoglobin. The most effective therapy is 100% hyperbaric oxygen (HBO) respiration. However, there are only a limited number of cases with ready accessibility to the specialized HBO chambers. In previous studies, we developed an extracorporeal veno-venous membrane oxygenator that facilitates exposure of blood to an external visible light source to photo-dissociate carboxyhemoglobin (COHb) and significantly increase CO removal from CO-poisoned blood (photo-extracorporeal veno-venous membrane oxygenator [p-ECMO]). One objective of this study was to describe in vitro experiments with different laser wavelength sources to compare CO elimination rates in a small unit-cell ECMO device integrated with a light-diffusing optical fiber. A second objective was to develop a mathematical model that predicts CO elimination rates in the unit-cell p-ECMO  device design upon which larger devices can be based. STUDY DESIGN/MATERIAL AND METHODS: Two small unit-cell p-ECMO devices consisted of a plastic capillary with a length and inside diameter of 10 cm and 1.15 mm, respectively. Either five (4-1 device) or seven (6-1 device) gas exchange tubes were placed in the plastic capillary and a light-diffusing fiber was inserted into one of the gas exchange tubes. Light from lasers emitting either 635 nm or 465 nm wavelengths was coupled into the light-diffusing fiber as oxygen flowed through the gas exchange membranes. To assess the ability of the device to remove CO from blood in vitro, the percent COHb reduction in a single pass through the device was assessed with and without light. The Navier Stokes equations, Carreau-Yesuda model, Boltzman equation for light distribution, and hemoglobin kinetic rate equations, including photo-dissociation, were combined in a mathematical model to predict COHb elimination in the experiments. RESULTS: For the unit-cell devices, the COHb removal rate increases with increased 635 nm laser power, increased blood time in the device, and greater gas exchange membrane surface-to-blood volume ratio. The 6-1 device COHb half-life versus that of the 4-1 device with 4 W at 635 nm light was 1.5 min versus 4.25 min, respectively. At 1 W laser power, 635 nm and 465 nm exhibited similar CO removal rates. The COHb half-life times of the 6-1 device were 1.25, 2.67, and 8.5 min at 635 nm (4 W), 465 nm (1 W), and 100% oxygen only, respectively. The mathematical model predicted the experimental results. An analysis of the in vivo COHb half-life of oxygen respiration therapy versus an adjunct therapy with a p-ECMO device and oxygen respiration shows a reduction from 90 min to as low as 10 min, depending on the device design. CONCLUSION: In this study, we experimentally studied and developed a mathematical model of a small unit-cell ECMO device integrated with a light-diffusing fiber illuminated with laser light. The unit-cell device forms the basis for a larger device and, in an adjunct therapy with oxygen respiration, has the potential to remove COHb at much higher rates than oxygen therapy alone. The mathematical model can be used to optimize the design in practical implementations to quickly and efficiently remove CO from CO-poisoned blood.

[Prehospital emergency care of patients exposed to poisoning: Assessment of epidemiological, clinical characteristics and quality of care]. / Atención prehospitalaria urgente de los pacientes pediátricos expuestos a tóxicos: características epidemiológico-clínicas y evaluación de la calidad asistencial.

OBJECTIVE: To describe the characteristics of paediatric patients with suspected poisoning treated by advanced life support (ALS) units, and to evaluate quality indicators (QI) for the prehospital emergency care of these patients. METHOD: A one-year observational study of patients under 18 years of age exposed to poisoning and treated by an ALS unit of the Medical Emergency System in Catalonia. Severe clinical criteria were defined, with 8 QI being evaluated for prehospital emergency care of poisoned paediatric patients. RESULTS: The study included a total of 254 patients, with a median age of 14 years-old (p25-75 = 7-16), with intentional poisoning in 50.8% of cases. The most frequently involved toxic agent was carbon monoxide (CO) (33.8%). Poisoning was found in 48.8% of those patients, being serious in 16.5%. Intentionally (OR 5.1; 95% CI: 1.9-13.8) and knowledge of the time of exposure (OD 3.1; 95% CI: 1.3-7.3) were independent risk factors associated with the appearance of severe clinical symptoms. Five QI did not reach the quality standard and included, availability of specific clinical guidelines, activated charcoal administration in selected patients, oxygen therapy administration at maximum possible concentration in carbon monoxide poisoning, electrocardiographic assessment in patients exposed to cardiotoxic substances, and recording of the minimum data set. CONCLUSIONS: Paediatric patients attended by ALS units showed specific characteristics, highlighting the involvement of CO and adolescents with voluntary poisoning. The QI assessment was useful to detect weak points in the quality of care of these patients and to develop strategies for improvement.

[Evaluation and assessment of the health care process in patients with carbon monoxide poisoning in Germany]. / Evaluation und Beurteilung des Versorgungsprozesses von Patienten mit Kohlenmonoxidvergiftung in Deutschland.

BACKGROUND: Carbon monoxide poisoning (COP) is the most common cause for poisoning by inhalation in Germany. In the past 8 years, a marked increase in the number of COP-related deaths has been registered nationwide. A national German guideline is missing. METHODS: The national and international literature was screened systematically. Existing international guidelines and expert recommendations for the diagnosis and treatment of COP were compared and evaluated. Furthermore, quality of health care was analyzed by a prospective preclinical dataset of emergency rescue services and retrospective analysis of routine data from 2014 to 2016 in Germany. RESULTS: There is not a single evidence-based guideline worldwide. We determined 8 key performance indicators based on the five recommendations available for treatment of COP. These indices were subdivided into prehospital terms, hospital facilities, and diagnostic and therapeutic measures performed; they act as indicators for quality of care. In particular, the key figure "start oxygen" revealed that up to 41 % of the patients had not been treated with inhaled oxygen. In summary, data capture showed considerable incompleteness that is mainly due to missing time stamps. CONCLUSION: In order to achieve a consistent treatment of patients with COP which meets the standard of recommended care, there is an urgent need for a consented national guideline. Another objective is to establish a nationwide prospective registry evaluating the treatment of carbon monoxide poisoning.

Treatment with normobaric or hyperbaric oxygen and its effect on neuropsychometric dysfunction after carbon monoxide poisoning: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Carbon monoxide (CO) poisoning may result in acute neurological sequelae, cognitive sequelae, and delay neurological sequelae. The administration of hyperbaric oxygen (HBO) to prevent the development of delayed neurological sequelae in CO poisoning have extensively investigated but conflicting results have been reported. We performed a systematic literature review and meta-analysis of randomized controlled trials (RCTs) evaluating HBO treatment and its effect on neuropsychometric dysfunction after CO poisoning. METHODS: We searched Medline, Embase, Pubmed, and the Cochrane Register of Controlled Trials from inception to December 2017. Eligible studies compared HBO therapy with normobaric oxygen (NBO) in patients with CO poisoning. RESULTS: Six studies compared HBO with NBO in CO poisoning patients. Compared with patients treated with NBO, a lower percentage of patients treated with HBO reported headache (16.2% vs 16.5%, relative risk [RR] = 0.83, 95% CI = 0.38-1.80), memory impairment (18.2% vs 23.8%, RR = 0.80, 95% CI = 0.43-1.49), difficulty concentrating (15.0% vs 18.4%, RR = 0.86, 95% CI = 0.55-1.34), and disturbed sleep (14.7% vs 16.2%, RR = 0.91, 95% CI = 0.59-1.39). Two sessions of HBO treatment exhibited no advantage over one session. CONCLUSIONS: The meta-analysis indicated that compared with CO poisoning patients treated with NBO, HBO treated patients have a lower incidence of neuropsychological sequelae, including headache, memory impairment, difficulty concentrating, disturbed sleep, and delayed neurological sequelae. Taking into consideration the cost-effectiveness of one session of HBO, one session of HBO treatment could be an economical option for patients with CO poisoning with high severity.

Hyperbaric programs in the United States: Locations and capabilities of treating decompression sickness, arterial gas embolisms, and acute carbon monoxide poisoning: survey results.

Hyperbaric oxygen therapy is the primary treatment for arterial gas embolism, decompression sickness and acute carbon monoxide poisoning. Though there has been a proliferation of hyperbaric centers throughout the United States, a scarcity of centers equipped to treat emergency indications makes transport of patients necessary. To locate and characterize hyperbaric chambers capable of treating emergency cases, a survey of centers throughout the entire United States was conducted. Using Google, Yahoo, HyperbaricLink and the UHMS directory, a database for United States chambers was created. Four researchers called clinicians from the database to administer the survey. All centers were contacted for response until four calls went unreturned or a center declined to be included. The survey assessed chamber readiness to respond to high-acuity patients, including staff availability, use of medical equipment such as ventilators and intravenous infusion devices, and responding yes to treating hyperbaric emergencies within a 12-month period. Only 43 (11.9%, N = 361) centers had equipment, intravenous infusion pumps and ventilators, and staff necessary to treat high-acuity patients. Considering that a primary purpose of hyperbaric oxygen therapy is the treatment of arterial gas embolism and decompression sickness, more hyperbaric centers nationwide should be able to accommodate these emergency cases quickly and safely.

Informe de evaluación rápida de tecnología sobre seguridad y efectividad de la oxigenoterapia hiperbárica / Rapid evaluation report of technology on safety and effectiveness of hyperbaric oxygen therapy

La oxigenación hiperbárica es una modalidad terapéutica no invasiva en la cual el pacientes respira oxígeno puro en el interior de una cámara de acero herméticamente cerrada, a presión atmosférica mayor a la ambiental (cámara hiperbárica). Existen solo dos efectos básicos que describen el mecanismo de acción de la OHB en el cuerpo humano, los cuales son: a. El efecto volumétrico, producido por la presión aumentada a la cual se somete el organismo. Dicho efecto es de fundamental importancia en la reducción del tamaño de las burbujas de gas que pueden contener los tejidos corporales como consecuencia de un accidente de buceo o iatrogenia médica (embolismo gaseoso en las intervenciones quirúrgicas u otros procedimientos terapéuticos invasivos), o el producido por bacterias anaerobias. b. El segundo efecto es solumétrico, debido al incremento de la presión parcial de oxígeno en los tejidos, siendo este multifacético, ya que a las presiones atmosféricas manejadas en este tratamiento el oxígeno se comporta como un fármaco con indicaciones específicas y posibles efectos adversos. Se recomienda cubrir en las siguientes condiciones: enfermedad por descompresión, embolia gaseosa, gangrena gaseosa, intoxicación por monóxido de carbono, fasceitis necrotizante, gangrena de Fournier, lesiones de pie diabético grado IV de Wagner, lesiones de bóveda craneal, parrilla costal, esternón, mandíbula, proctitis y enteritis.(AU)

Diagnosis and management of carbon monoxide poisoning in the emergency department.

An 89-year-old female is found by her family, lying unconscious on her kitchen floor after they had been unable to reach her by phone for several hours. EMS is activated and when the paramedics arrive, they note that the gas oven is on, and there is thin, gray smoke coming from around the door. The house gas supply is turned off, windows are opened, and the family and the patient are immediately evacuated from the home. En route to the hospital, the patient is placed on high-flow oxygen at 15 liters per minute by non-rebreather mask. Her bedside glucose determination is 229 mg/dL. Vital signs are within normal limits during transport. She opens her eyes to sternal rub, and makes spontaneous movements of all extremities. Upon arrival to the ED, the patient becomes more alert and is able to respond to your questions. She tells you that she remembers putting a tray of calzones into the oven, after which she has no recall of the day's events. She has a past medical history of "well-controlled" hypertension, hyperlipidemia, and non-insulin-dependent diabetes. Her medications include hydrochlorothiazide 25 mg daily, lisinopril 10 mg daily, simvastatin 20 mg daily, and metformin 1000 mg twice daily. On physical examination, weight is 65 kg, blood pressure is 97/50 mm Hg, heart rate is 113 beats per minute, respiratory rate is 22 breaths per minute, temperature is 37.1 degrees C (98.8 degrees F), and oxygen saturation is 99% on 15 liters per minute via non-rebreather mask. She appears her stated age. Cardiopulmonary examination is remarkable only for tachycardia. Her abdomen is soft and non-tender with normal bowel sounds. Her skin is warm and dry, and there is no peripheral edema. Her cranial nerves are intact, with briskly reactive, symmetric pupils. Motor and sensory examination is non-focal, and cerebellar testing is notable only for an intention tremor on finger-nose-finger test. Gait is normal and speech is fluent and without errors. Laboratory testing shows a hemoglobin of 10.3 g/dL and a leukocyte count of 11.7 x 10(9)/L. Electrolyte results fall within the normal range, and her serum creatinine is 1.7 mg/dL. Qualitative CK-MB and troponin I tests are positive, and the sample has been sent to the STAT lab for quantitative testing. Serum carboxyhemoglobin level is 15% with normal serum pH on an arterial blood gas. An ECG reveals deep, down-sloping inferior and lateral ST-segment depressions which were not present on a routine cardiogram 1 month prior. You have many questions about this patient's care. What symptoms and physical signs need to be addressed and treated? What additional diagnostic testing should be performed? What treatment regimen is appropriate and what should be avoided? What are the risks or delayed complications from her illness? Are there special considerations for this or other patient populations?

[Screening for carbon monoxide (CO) poisoning by general practitioners in home visits]. / Dépistage des intoxications au monoxyde de carbone (CO) par des médecins généralistes effectuant des visites à domicile.

OBJECTIVE: To evaluate the interest of carbon monoxide (CO) detector used by general practionners visiting patients at home. METHODS: CO detector (cost: 200 euros) was attributed to 300 general practionners visiting at least 20 patients at home per week. Alarm was triggered when ambient CO concentration exceeded 80ppm. Measurement of CO in expired breath was also possible. Activity and alarms were prospectively collected. Circumstances of intoxication were recorded. Evaluation was finally performed. The end-poind was to quantify CO-poisoning detected by the use of the device and the cost of this stratégy. RESULTS: From November 2001 to November 2004, 65 scenes of intoxication with 79 victims were prospectively reported by 12 general practionners. Final evaluation revealed that 23 physicians omitted to declare alarms. Alarm incidence was of 1 for 17.527 visits; with a related cost of approximately 858 euros for 24 months. Ambient carbon monoxide concentration exceeded 200ppm in 25% of cases. Hospital admission was required for 91% of the victims. Hyperbaric oxygen therapy was performed in two cases. General practionners (n=272) considered that CO detector was useful for safety reasons (91%), they wanted to continue the experience, but did not plan to buy such device (59%). DISCUSSION: Use of CO detectors by general practionners visiting patients at home allowed to identify 65 scenes of CO intoxication. In most cases, the cause of the visit did not suggested CO poisoning. The cost of the device seems to limits its large use. CONCLUSION: CO detector is a safety tool for both general prationners and patients. Its large use has to be questioned.

Assessment of myocardial injury in the emergency department independently predicts the short-term poor outcome in patients with severe carbon monoxide poisoning receiving mechanical ventilation and hyperbaric oxygen therapy.

OBJECTIVES: Patients with severe carbon monoxide (CO) poisoning are often prone to unconsciousness and respiratory distress and as a result will receive mechanical ventilation and hyperbaric oxygen (MV-HBO) therapy. Factors associated with poor outcome at discharge are less defined in this patient population. This study was conducted to identify the prognostic predictors of short-term poor outcome in severely CO-poisoned patients receiving MV-HBO therapy. METHODS: The departmental database and the medical records of 81 patients treated with MV-HBO therapy were reviewed. Demographic and clinical data were extracted for analysis. HBO therapy with 2.5 or 2.8 atmosphere absolute (ATA) was administered to these patients. Short-term poor outcome was defined as an in-hospital death or neurologic sequelae at discharge. All patients were divided into two groups: those with a poor outcome and those without a poor outcome. RESULTS: Nine patients died while in the hospital, 32 patients had neurologic sequelae at discharge, and the incidence of poor outcome was 50.6%. Parameters that were assessed in the emergency department (ED) and highly associated with patients with a poor outcome included myocardial injury, typical findings on brain computed tomography related to CO poisoning, and higher serum levels of alanine transaminase, aspartate aminotransferase, blood urea nitrogen, creatinine, creatine kinase, creatine kinase-myocardial band, troponin-I, and C-reactive protein. These poor outcomes were also correlated with prolonged lag times from the end of CO exposure to ED arrival and from ED arrival to HBO therapy. In a multivariate analysis, myocardial injury was the only independent predictor of poor outcome (odds ratio, 8.2; 95% confidence interval, 1.012-67.610; p=0.049). CONCLUSIONS: The results of this study indicate that myocardial injury assessed at ED arrival independently predicts the short-term poor outcome in severely CO-poisoned patients who receive MV-HBO therapy. Emergency physicians could use this objective marker to identify patients with an increased risk of poor outcome at discharge and refine the treatment protocol by shortening the time of patient transport and administering HBO therapy as soon as possible.

Indications de l'oxygénothérapie hyperbare: mise à jour / Indications for hyperbaric oxygen therapy: update

INTRODUCTION: Dans la première moitié du XXe siècle, l'oxygénothérapie hyperbare (OHB) fut utilisée pour le traitement des accidents de décompression. D'autres indications se sont ajoutées au fil des ans, de sorte que l'OHB est aujourd'hui recommandée par l'Hyperbaric Oxygen Therapy Committee de l'Undersea and Hyperbaric Medical Society (UHMS) pour prévenir ou traiter les 13 affections suivantes: 1) les accidents de décompression; 2) l'embolie gazeuse; 3) l'intoxication au monoxyde de carbone; 4) les radionécroses; 5) les plaies réfractaires; 6) les brûlures thermiques; 7) les problèmes de greffes de peau et de tissus; 8) la gangrène gazeuse; 9) les infections nécrosantes des tissus mous; 10) l'ostéomyélite réfractaire; 11) l'abcès intracrânien; 12) les lésions par écrasement, les syndromes compartimentaux et les traumatismes ischémiques aigus; et 13) les anémies particulières. Toutefois, à l'exception des situations d'urgence comme les accidents de décompression et les embolies gazeuses, les applications de l'OHB demeurent controversées dans la littérature scientifique. Dans ce contexte, le ministre de la Santé et des Services sociaux a demandé à l'Agence d'évaluation des technologies et des modes d'intervention en santé (AETMIS) de revoir l'état actuel des connaissances sur l'utilisation de l'OHB pour la prévention et le traitement de ces 13 affections. Plus précisément, il désire savoir si depuis la publication du rapport du Conseil d'évaluation des technologies de la santé (CETS, le prédécesseur de l'AETMIS) en 2000, de nouvelles recherches ont donné des résultats probants quant à l'efficacité de cette technologie et si d'autres indications peuvent s'ajouter aux 13 premières. Rappelons que l'AETMIS a produit récemment deux rapports sur la place de l'OHB dans la prise en charge de la paralysie cérébrale et de l'autisme, deux indications non reconnues par les sociétés savantes. RÉSULTATS: Les études quantitatives et qualitatives publiées depuis 2000 sur les 13 indications et quelques autres affections traitées avec l'OHB ont été analysées. En ce qui concerne le traitement de la surdité cochléaire soudaine idiopathique, les connaissances actuelles indiquent que l'OHB réduirait significativement la perte d'audition dans les premières semaines suivant son apparition. Cependant, l'importance clinique de ce gain reste incertaine et ne peut donc justifier, pour le moment, le recours systématique à l'OHB sans l'appui de nouvelles études. Par contre, les experts de l'ECHM maintiennent la recommandation de 1994, qui préconise l'OHB pour le traitement de cette affection, jusqu'à ce qu'une étude européenne en cours sur le sujet soit terminée. Enfin, la place de l'OHB dans la prise en charge de la paralysie cérébrale et de l'autisme a été examinée de façon exhaustive dans deux rapports récents (2007) de l'AETMIS : selon l'état actuel des connaissances, ces applications restent expérimentales et la démonstration de leur efficacité nécessite des essais cliniques comparatifs rigoureux. CONCLUSION: L'objectif principal de ce rapport était de mettre à jour le précédent rapport du CETS publié en 2000 sur les indications reconnues de l'oxygénothérapie hyperbare (OHB). Étant donné la rareté de nouvelles études et la faible qualité de plusieurs d'entre elles, l'AETMIS a appuyé en grande partie son évaluation sur des consensus d'experts, dont les deux principaux sont issus de l'Hyperbaric Oxygen Therapy Committee de l'Undersea and Hyperbaric Medical Society (UHMS) et de l'European Committee for Hyperbaric Medicine (ECHM). Au terme de son évaluation, l'AETMIS conclut que les indications recommandées de l'oxygénothérapie hyperbare demeurent semblables, dans leur ensemble, bien que des précisions se soient ajoutées. Selon les données probantes (regroupées selon trois niveaux de preuve : A - élevé, B - moyen et C - faible), la liste des indications se présente maintenant comme suit: I. Indication recommandée en prévention: Ostéoradionécrose après une extraction dentaire en zone irradiée (niveau de preuve B; aucune nouvelle donnée). II. Indications recommandées en 1re intention de traitement: Accidents de décompression (niveau de preuve C) Embolie gazeuse artérielle ou veineuse compliquée (niveau de preuve C; aucune nouvelle donnée). III. Indications recommandées en 2e ou en 3e intention de traitement: Intoxication au monoxyde de carbone (niveau de preuve B) Gangrène gazeuse (niveau de preuve C; aucune nouvelle donnée). Nécroses infectieuses autres que la gangrène gazeuse (niveau de preuve C; aucune nouvelle donnée) Ostéoradionécrose mandibulaire, radionécrose des tissus mous et des greffes musculocutanées après une chirurgie majeure en zone irradiée, rectite hémorragique postradique (niveau de preuve B) et cystite hémorragique postradique (niveau de preuve C; aucune nouvelle donnée) Plaies réfractaires (lésions diabétiques, ulcères veineux de jambes) (niveau de preuve B) Greffes cutanées et musculocutanées en zone ischémique (niveau de preuve B; aucune nouvelle donnée) Ostéomyélite réfractaire (niveau de preuve C) Abcès intracrânien (niveau de preuve C) Lésions ischémiques et traumatiques : lésions par écrasement, syndrome compartimental et autres traumatismes ischémiques aigus (niveau de preuve B; aucune nouvelle donnée). IV. Indications recommandées en traitement optionnel: Brûlures thermiques (niveau de preuve C; aucune nouvelle donnée) Anémies particulières (niveau de preuve C; aucune nouvelle donnée). Pour la plupart de ces indications, les paramètres d'administration de l'OHB (durée d'exposition optimale, pression, fréquence des séances) restent à confirmer. Enfin, selon l'ECHM, l'OHB peut être un traitement optionnel de la surdité cochléaire soudaine idiopathique dans les premières semaines suivant son apparition (niveau de preuve B). Toutefois, selon la présente évaluation, de nouvelles études sont nécessaires pour justifier le recours systématique à l'OHB pour cette surdité particulière, puisque l'importance clinique des bénéfices obtenus reste incertaine. Pour d'autres affections, les données disponibles ne permettent pas de confirmer l'efficacité de l'OHB : il s'agit des affections malignes, des blessures sportives, du syndrome coronarien aigu, de la chirurgie cardiopulmonaire, des migraines et des céphalées, de la paralysie de Bell, des accidents vasculaires cérébraux et des traumatismes crâniens, et de la sclérose en plaques. Toutefois, le consensus d'experts de l'ECHM précise que l'OHB peut être un traitement optionnel du neuroblastome de stade IV, de la pneumatose kystique de l'intestin et de l'affection ophtalmique ischémique aiguë. Enfin, dans deux rapports récents (2007), l'AETMIS a déjà conclu que l'OHB constitue un traitement expérimental de la paralysie cérébrale et de l'autisme, deux indications aussi non reconnues par les sociétés savantes. Force est de constater que peu d'indications de l'oxygénothérapie hyperbare ont fait l'objet de recherches rigoureuses et que les données probantes sont rares. Il est clair que certaines affections ne se prêtent pas facilement à des recherches pour des raisons éthiques. Les consensus d'experts, bien que non complètement concordants, constituent donc l'assise principale qui appuie et justifie le recours à l'OHB pour une majorité d'indications cliniques. Ces consensus d'experts ouvrent également des avenues intéressantes à de nouvelles recherches de meilleure qualité méthodologique et à des expériences cliniques futures.

INTRODUCTION: During the first half of the 20th century, hyperbaric oxygen (HBO) therapy was used to treat decompression sickness. Other indications have been added over the years, with the result that the Hyperbaric Oxygen Therapy Committee of the Undersea and Hyperbaric Medical Society (UHMS) now recommends HBO therapy for the prevention or treatment of the following 13 conditions: 1) decompression sickness; 2) gas embolism; 3) carbon monoxide poisoning; 4) radionecrosis; 5) problem wounds; 6) thermal burns; 7) skin and tissue graft problems; 8) gas gangrene; 9) necrotizing soft-tissue infections; 10) refractory osteomyelitis; 11) intracranial abscess; 12) crush injuries, compartment syndromes and acute traumatic ischemia; and 13); exceptional blood loss anemias. However, with the exception of emergency situations such as decompression sickness and gas embolism, the applications of HBO therapy are still debated in the scientific literature. In this context, the Minister of Health and Social Services asked the Agence d'évaluation des technologies et des modes d'intervention en santé (AETMIS) to review the current state of knowledge concerning the use of HBO therapy to prevent and treat these 13 conditions. More specifically, it would like to know if, since the publication of the report by the Conseil d'évaluation des technologies de la santé (CETS, AETMIS's predecessor) in 2000, new research has yielded any evidence regarding the efficacy of this technology and if other indications could be added to these 13. It will be noted that AETMIS recently produced two reports on the role of HBO therapy in managing cerebral palsy and autism, two indications that are not recognized by the learned societies. RESULTS: The quantitative and qualitative studies published since 2000 on the 13 indications and a few other conditions treated with HBO therapy were analyzed. With regard to the treatment of idiopathic sudden sensorineural hearing loss, the current knowledge indicates that HBO therapy would significantly reduce hearing loss during the first few weeks following its occurrence. However, the clinical importance of this gain is uncertain and cannot, therefore, justify, at this time, the systematic use of HBO therapy without the support of new studies. However, the ECHM's experts maintain the 1994 recommendation, which advises the use of HBO therapy to treat this condition, until an ongoing European study on this matter is completed. Lastly, the role of HBO therapy in managing cerebral palsy and autism is exhaustively examined in two recent AETMIS reports (2007). Based on the current state of knowledge, these applications are still experimental, and rigorous controlled clinical trials are needed to demonstrate their efficacy. CONCLUSION: The main objective of this report was to update the previous report (published by CETS in 2000) on the recognized indications for hyperbaric oxygen (HBO) therapy. Given the paucity of new studies and the fact that a number of them are of poor quality, AETMIS has, to a large extent, based its assessment on expert consensus, the two main ones being from the Hyperbaric Oxygen Therapy Committee of the Undersea and Hyperbaric Medical Society (UHMS) and the European Committee for Hyperbaric Medicine (ECHM). At the end of its assessment, AETMIS concludes that, on the whole, the recommended indications for hyperbaric oxygen therapy remain the same, although there is now additional information. Based on the evidence (classified into three levels: A - high; B - medium; C - low), the list of indications is now as follows: I. Recommended indication for prevention: Osteoradionecrosis after tooth extraction in an irradiated area (level of evidence: B; no new data). II. Recommended indications as first-line therapy: Decompression sickness (level of evidence: C). Complicated venous or arterial gas embolism (level of evidence: C; no new data). III. Recommended indications as second- or third-line therapy: Carbon monoxide poisoning (level of evidence: B). Gas gangrene (level of evidence: C; no new data). Infectious necroses other than gas gangrene (level of evidence: C; no new data). Mandibular osteoradionecrosis, radionecrosis of soft tissues and musculocutaneous grafts after major surgery in an irradiated area, hemorrhagic radiation rectitis (level of evidence: B) and hemorrhagic radiation cystitis (level of evidence: C; no new data). Problem wounds (diabetic lesions, venous leg ulcers) (level of evidence: B). Skin and musculocutaneous grafts in ischemic areas (level of evidence: B; no new data). Refractory osteomyelitis (level of evidence: C). Intracranial abscess (level of evidence: C). Ischemic and traumatic lesions: crush injuries, compartment syndromes and other acute traumatic ischemia (level of evidence: B; no new data). IV. Recommended indications as optional therapy: Thermal burns (level of evidence: C; no new data). Specific anemias (level of evidence: C; no new data). For most of these indications, the parameters for administering HBO therapy (optimum duration of exposure, pressure, frequency of sessions) have yet to be determined. Lastly, according to the ECHM, HBO therapy can be an optional treatment modality for idiopathic sudden sensorineural hearing loss during the first few weeks following its occurrence (level of evidence: B). However, according to this assessment report, new studies are required in order to justify the systematic use of HBO therapy for this particular type of hearing loss, since the clinical importance of the benefits that it confers is uncertain. For other conditions, it cannot be established from the available evidence that HBO therapy is effective. They are malignant conditions, sports injuries, acute coronary syndrome, cardiopulmonary surgery, migraine, Bell's palsy, head injury, stroke and multiple sclerosis. However, the ECHM expert consensus states that HBO therapy may be an optional treatment for stage IV neuroblastoma, pneumatosis cystoides intestinalis, and acute ischemic ophthalmological disorders. Lastly, in two recent reports (2007), AETMIS concludes that HBO therapy is an experimental treatment for cerebral palsy and autism, two indications that are also not recognized by the learned societies. It should be noted that few indications for hyperbaric oxygen therapy have been rigorously studied and that the evidence is scarce. Obviously, for ethical reasons, certain conditions are not easily amenable to scientific research. Although they are not entirely concordant, the expert consensus are thus the main foundation for supporting and justifying the use of HBO therapy for most of the clinical indications. These expert consensuses are also opening up interesting avenues for new studies of better methodological quality and future clinical experiments.

Carbon monoxide poisoning: two cases of assessment by magnetization transfer ratios and 1H-MRS for brain damage.

We describe two patients with carbon monoxide (CO) poisoning. One developed diseased hypoxic encephalopathy, and the other recovered completely. In the patient with progressive hypoxic encephalopathy, the magnetization transfer ratios (MTRs) had already decreased during the lucid period, while the patient with complete recovery showed no reduction of MTRs during this period. 1H-MRS in the two patients revealed no definite abnormality during this lucid period. The MTR maps suggested that irreversible change had already occurred during the lucid period, and 1H-MRS was useful to determine the duration of treatment. The combination of MTRs and 1H-MRS may help to manage patients with CO poisoning.

Hyperbaric oxygen therapy in the management of carbon monoxide poisoning, osteoradionecrosis, burns, skin grafts, and crush injury.

OBJECTIVES: To systematically assess the evidence for effectiveness of hyperbaric oxygen therapy in the treatment of conditions of significance in the West Midlands region and to determine whether there is a case for establishing a hyperbaric oxygen unit in the region. METHODS: Systematic review of the literature assessing randomized controlled trials from 1968 onward. RESULTS: A total of 154 full-text articles was obtained of which 13 relevant randomized control trials were identified. There was little consistency in the studies. Treatment protocols, study groups, time to treatment, and other characteristics and outcomes measured all varied considerably. No convincing evidence of effectiveness was identified. CONCLUSIONS: Although hyperbaric oxygen therapy is clearly appropriate in the treatment of decompression sickness and air/gas embolism, there is no convincing evidence of effectiveness for the conditions reviewed, despite its widespread use. Although this review has found no evidence to support the establishment of a unit in the West Midlands, there is a physiological case for an effect in conditions involving hypoxia and, given the limited volume (and in some cases quality) of published research, a case for a national research program.

Carbon monoxide poisoning in Kentucky.

Fatal and nonfatal cases of carbon monoxide (CO) poisoning continue to be widespread. Hospital discharge data were used to identify cases of CO poisoning in Kentucky during 1998-1999. Additional data collection was conducted through medical record abstraction. Information was collected on 205 cases at 33 Kentucky hospitals. Over half of the CO poisoning cases occurred in residential settings. The most common types of equipment operating at the time of exposure were motor vehicles and gas heating sources. Eighteen percent of the cases required hospitalization. Almost half of the incidents occurred during December, January, and February. Incidents of CO poisoning can be reduced through education and implementation of appropriate prevention strategies. Public health professionals and health care professionals should provide education about the sources of CO and the hazards of exposure. Recommendations for prevention are provided.

Uses of hyperbaric oxygen therapy in the 1990s.

Hyperbaric oxygen can produce a variety of effects in addition to reducing air and gas embolism. It increases the killing ability of leukocytes and is lethal to certain anaerobic bacteria. It inhibits toxin formation by certain anaerobes, increases the flexibility of red cells, reduces tissue edema, preserves intracellular adenosine triphosphate, maintains tissue oxygenation in the absence of hemoglobin. In addition, it stimulates fibroblast growth, increases collagen formation, promotes more rapid growth of capillaries, and terminates lipid peroxidation. These actions of hyperbaric oxygen are useful in treating anaerobic infections that result in gas gangrene, as well as severe aerobic infections such as necrotizing fasciitis, malignant external otitis, and chronic refractory osteomyelitis. Hyperbaric oxygen can help preserve ischemic tissues and facilitates the rapid spread and arborization of new capillaries. It promotes healing in certain problem wounds. Adjunctive hyperbaric oxygen treatment is a new approach to the management of radionecrosis. Hyperbaric oxygen treatment reduces morbidity and mortality resulting from carbon monoxide poisoning. Protocols for hyperbaric oxygen therapy are at present mostly empirical; much additional research is needed to better define therapeutic indications.