Autonomic Nervous System, Cardiovascular System, and Cognitive Function Response in Selected Parameters to Normobaric Hyperoxia Exposure in Healthy Subjects
Molecular oxygen, O2, takes part in energy generation by mitochondrial respiration. An increase of oxygen partial pressure, pO2 in inhaled air is potentially an effective therapeutic option in certain neurological disorders and improvement of physical capacity in amateur and professional athletes. Normobaric hyperoxia in experimental research applied in the treatment of patients with acute brain infarction may prevent tissue necrosis from ischaemia and partially prevent its consequences. Normobaric hyperoxia improves cerebral blood flow and oxygenation, by which it favours mitigation of adverse effects from neurodegenerative disorders. The assumptions for the therapeutic effects of normobaric hyperoxia are partially related to hyperbaric oxygen therapy; however, the clinical aspect of hyperbaric oxygen therapy is definitely different from normobaric hyperoxia. Hyperbaric oxygen therapy has been used for nearly a century in treatment of multiple severe, often life-threatening morbidities, usually under intense therapeutic regimes or in personalised therapy programs.
Hyperbaric oxygen therapy (HBOT) involves respiration of elevated oxygen concentrations inside of a hyperbaric chamber which is under elevated pressure the level of which is higher than the absolute atmospheric pressure determined to be 1 physical atmosphere (1 ATA). The pressure ranges used in HBOT usually varies between 1.5 ATA and 3 ATA, whereas the therapy cycle can be between 30 to 120 minutes. Inhalation of oxygen at 3 ATA increases the blood partial pressure to more than 200 kPa, increasing the arterial blood oxygen level from 6.6 mL to 6.8 mL (O2/100 mL). Under normal conditions, the most part of the oxygen carried by the bloodstream is bound to haemoglobin in RBC (red blood cells). What is key in HBOT is that when the pressure increases to 3 ATA, the level of O2 delivered with blood increases 10 to 15 times above the normal. This mechanism is especially important in carbon monoxide poisoning. Carbon monoxide is 250 times easier to bind with haemoglobin, this disturbing haemoglobin oxygen transport. The application of HBOT to carbon monoxide poisoning can be sufficient to support life functions even if haemoglobin is missing. However, the side effects of HBOT that occur rarely include oxygen toxicity, pulmonary oedema, and more often, hyperoxic myopia. Moreover, many patients undergoing HBOT experiences claustrophoby inside of the chamber, which can be mitigated by increasing the internal space of the chamber.
EKONSTAL Sp. z.o.o. Sp. k. has developed a pressure chamber the specifics of which is different from the chambers routinely used in HBOT around the world. It is why the EKONSTAL designers decided to name it a ‘normobaric chamber’, despite its internal pressure of 1500 hPa, which is higher than the sea-level atmospheric pressure (1013.25 hPa). The exposure inside of a normobaric chamber is accompanied by modified pressure of three gases with the following parameters: 41 pO2 kPa, 0.55 pH2 kPa, 2.1 pCO2 kPa. A review of available reference literature allows a hypothesis that these parameters of respiratory gases trigger positive and expected therapeutic effects with full safety of exposure conditions.
Moreover, the exposure in a normobaric chamber developed by EKONSTAL Sp. z.o.o. Sp. k. may reduce the risk of triggering a claustrophobic response due to the larger than normal internal space, which seems to be especially important.
Therapeutic applications of normobaric hyperoxia are a subject of many publications and continue to be a field explored by acclaimed research teams. The many positive effects of normobaric hyperoxia include:
- improved function of vascular endothelium,
- reduced eyeball swelling in diabetes sufferers,
- reduced lymphatic oedema,
- improved angiogenesis,
- improved cognitive functions,
- reduction of adverse effects from nervous tissue hypoxia,
- reduced severity of inflammatory processes,
- improved trophic in tissues,
- stimulative response of the skin cells, especially in fibroblasts, with improvement in elasticity,
- retardation of adverse effects from neurodegenerative disorders.
The objective of the research project completed by the authors’ research team was to investigate the effectiveness of a therapeutic program which involved a series of 10 exposures inside of a normobaric chamber developed by EKONSTAL Spółka z.o.o. The therapeutic program duration was two weeks, with each exposure lasting two hours. The effects of the intervention by normobaric chamber exposure on cognitive functions, biochemical functions (oxidative stress parameters and neurotrophin level), and functional parameters of the cardiovascular system, largely in terms of autonomic control, were assessed. […]
The primary conclusion from this research project is that 10 exposures in the normobaric chamber at 1500 hPa of pressure and modified concentrations of gases (41 pO2 kPa, 0.55 pH2 kPa, 2.1 pCO2 kPa) had a favourable effect on the rate of visual information processing and the ability to switch visual targets, and the auditory/oral short-term memory. A higher expression of neurotrophins was found with improved sensitivity of response in arterial baroreceptors. Changes in the sympathetic/parasympathetic balance control and arterial blood pressure control were found in the response to an active stand test, which suggests an improvement in the control of orthostatic response. The observed improvement in response to orthostatic rection is very important to short-term autonomic control. Much of the research work to date suggests that the improvement of autonomic control can be a marker of overall improvement in the reactiveness of the nervous systems at its different tiers, including cognitive functions. […]
The exposures experienced by the subjects in the normobaric chamber triggered an oxidative stress modulation, which was proven by significant changes in these biochemical parameters, MDA and SOD. Reduced MDA and increased SOD could be considered to be beneficial to the capability to cope with oxidative stress in the subjects who had undergone the intervention by normobaric chamber exposure. Importantly, the SOD increase found in this research could be a response to elevated oxidative stress related to oxygen-induced reactive forms of oxygen. Another very important point is the elevated level of CC16, a marker of oxidative stress and reconstruction within pulmonary tissue. […]
When planning exposure to normobaric hyperoxia, a number of contra-indications and restrictions to the exposure effects should be considered. So far, no major side effect of this therapy have been observed, which is an argument for the safety of normobaric hyperoxia; however, this does not waive the necessity to apply all possible precautions.
Manager of Department of Exercise Physiology and Functional Anatomy, CM UMK
Prof. Paweł Zalewski, PhD