Evaluation of patients who underwent hyperbaric oxygen therapy with the diagnosis of carbon monoxide poisoning

Introduction: Carbon monoxide is a colorless, odorless toxic gas, which is produced by incomplete combustion of carbon containing fuels. Carbon monoxide poisoning remains an important cause of suicidal or accidental poisoning worldwide. There are several clinical studies showing that hyperbaric oxygen therapy (HBOT) is more effective on pathophysiological mechanisms compared to normobaric oxygen therapy and prevents delayed brain damage and immune-mediated neurological sequelae in the treatment of carbon monoxide poisoning. However, algorithms for the use of HBOT in carbon monoxide poisoning are not clear today. In this study, it is aimed to determine demographic, clinical and laboratory features of the patients who underwent HBOT with the diagnosis of carbon monoxide poisoning in Istanbul University, Istanbul Faculty of Medicine, Department of Underwater and Hyperbaric Medicine, to share the experience, to clarify the criteria for selecting the patients for HBOT, and to identify the benefits of proper treatment approaches before admission to our clinic. Material and method: Patients who were admitted to our clinic with the diagnosis of carbon monoxide poisoning and underwent HBOT between January 2009 and March 2019 were included in the study. The data of the cases were recorded by creating a form and IBM SPSS Version 21 statistical program was used for the evaluation of the data. If the p value was less than 0.05, the difference was considered statistically significant. Results: In this study, the records of 262 patients were evaluated. At the time of admission mean age was 29.7 and median age was 26. The distribution of the gender and age of the cases were as 49.6% female, 50.4% male and 63.4% adult and 36.6% children. Most of the treatments were made in January and December, in winter. The most common source of carbon monoxide was coal stove with the rate of 58%. It was found that 54% of the cases transferred to the hospital by ambulance and 46% by themselves. 49% of the cases who were transported to the hospitals by ambulance did not use an appropriate oxygen mask during the transfer, and 45% of the cases did not use an appropriate oxygen mask during the transfer to our department. The most common symptom recorded on admission was unconsciousness with a rate of 47%. The mean value of first carboxyhemoglobin level (COHb) was 30.0%. There was no information about the level of carbon monoxide level at the poisoning environment. The cases who transferred by ambulance, admitted to our center without delay and had no cardiac dysfunction were healed by the administration of a single session HBOT. The patients who had higher Glasgow Coma Scale (GCS) score and lower COHb levels at the time of admission were found to have a significantly higher rate of healing by a single session HBOT comparing to other cases. In addition, the cases who were younger and admitted to our clinic without a delay discharged by complete healing. The factors contributed the complete healing rate after the completion of HBOT were higher GCS score at the time of admission, higher blood pH level, lower COHb level and blood lactate level. The mean numbers of HBOT sessions in the cases who were discharged with complete healing, with partial healing and without a benefit were 1,62. 85.9%, 8.0% and 6.1% respectively. The mortality rate was 2.3%. The total number of HBOT sessions applied to all cases was determined as 424. None of the patients had any complications due to HBOT. Conclusion: The most important aspect of carbon monoxide poisoning is that although it can be prevented with small precautions, it may be fatal. HBOT is an effective method for the treatment of carbon monoxide poisoning. In our country the number of HBOT center is increasing and more cases had the opportunity of receiving HBOT. The awareness about HBOT is increasing in our country. The success of the HBOT in carbon monoxide poisoning cases is increased when applied without a delay. Prospective long term studies are needed to determine the algorithm of the appropriate treatment and approach to patients with carbon monoxide poisoning.