Hyperbaric oxygen therapy for COVID-19 patients with respiratory distress: treated cases versus propensity-matched controls

Abstract

Decompression sickness (DCS) occurs when nitrogen gas (N2) comes out of solution too quickly, forming bubbles in the blood and tissues. These bubbles can be a serious condition; thus it is of extreme interest in the dive community to model DCS risk. Diving models use tissue compartments to calculate tissue partial pressures, often using data obtained from other mammalian species (i.e., pigs). Adipose tissue is an important compartment in these models because N2 is five times more soluble in fat than in blood; at any blood/ tissue interface N2 will diffuse into the fat and can lead to bubble formation on ascent. Little is known about many characteristics of adipose tissue relevant to diving physiology. Therefore, we measured microvessel density and morphology, lipid composition, and N2 solubility in adipose tissue from humans and pigs. Human adipose tissue has significantly higher microvascular density (1.79 Å} 0.04 vs. 1.21 Å} 0.30%), vessel diameter (10.25 Å} 0.28 vs. 6.72 Å} 0.60 μm), total monounsaturated fatty acids (50.1 vs. 41.2 mol%) and N2 solubility (0.061 Å} 0.003 vs. 0.054 Å} 0.004 mL N2 mL-1 oil) compared to pig tissue. Pig adipose tissue has significantly higher lipid content (76.1 Å} 4.9 vs. 64.6 Å} 5.1%) and total saturated fatty acids (38.8 vs. 29.5 mol%). Though two important components in gas kinetics within adipose tissue during diving (blood flow rates and degree of perfusion) are not well understood, our results indicate differences between the adipose tissue of humans and pigs. This suggests data from swine may not exactly predict gas dynamics for estimating DCS in humans.

Hyperbaric oxygen as an adjuvant treatment for patients with COVID-19 severe hypoxaemia: a randomised controlled trial

“… 22 HBO 2 treatment below 2.0 ATA increases the activity of antioxidant enzymes, including first-line defence antioxidants superoxide dismutase and catalase. 11 …”

“… 12–15 However, as the increased pressure of HBO 2 therapy may exacerbate an acute lung injury or induce pulmonary oedema among patients with COVID-19, potential complications must be assessed. 11 The objective of this study was to analyse the safety and efficacy of HBO 2 treatment in patients with COVID-19 with severe hypoxaemia in the reduction of time for recovery from hypoxaemia (defined as SatO 2 ≤93%). Also, the study evaluated if HBO 2 treatment decreased progression to respiratory distress, mechanical ventilation requirements and mortality.…”

“…In case studies, HBO 2 therapy has proved to be effective and safe in patients with COVID-19 pneumonia 9 10. In patients that received HBO 2 therapy, SpO 2 increased, tachypnoea resolved and inflammatory markers decreased 10 11. Randomised controlled trials investigating HBO 2 therapy in patients with COVID-19 have not been published so far.…”

“…HBO 2 therapy at medium pressure (below 2 ATA) has shown that it is neurologically safer than treatment at higher pressures 12–15. However, as the increased pressure of HBO 2 therapy may exacerbate an acute lung injury or induce pulmonary oedema among patients with COVID-19, potential complications must be assessed 11. The objective of this study was to analyse the safety and efficacy of HBO 2 treatment in patients with COVID-19 with severe hypoxaemia in the reduction of time for recovery from hypoxaemia (defined as SatO 2 ≤93%).…”

Hyperbaric oxygen therapy for patients with COVID-19

“…Nevertheless, the data from this study are consistent with other recent work involving HBO 2 therapy in patients with COVID-19. These studies have shown that patients begin treatment with very high respiratory rates and raised inflammatory markers, both of which seem to decrease with HBO 2 5 6. during and even after HBO therapy periods.…”