Low temperature worsens mammalian oxygen toxicity

Area of Science:

• Physiology
• Toxicology
• Hyperbaric Medicine

Background:

• Hyperbaric oxygen therapy (HBOT) is used therapeutically, but oxygen toxicity is a concern.
• Hypothermia is a known side effect of hyperbaric oxygen exposure.
• The protective role of hypothermia against oxygen toxicity is not fully understood.

Purpose of the Study:

• To investigate the combined effects of hyperbaric oxygen and hypothermia on oxygen toxicity in mice.
• To assess the impact of hypothermia on central nervous system and lung toxicity induced by hyperbaric oxygen.

Main Methods:

• Mice were exposed to 5 atmospheres absolute (ATA) of oxygen.
• Central nervous system toxicity was measured by the latency to convulsions.
• Lung damage was assessed using wet and dry weight measurements.
• Mice were exposed at ambient temperatures of 15°C and 5°C to induce hypothermia.

Main Results:

• Hyperbaric oxygen induced profound hypothermia in mice at lower ambient temperatures.
• Hypothermia had minimal effect on the latency to convulsions, indicating no protection against central nervous system toxicity.
• The combination of hypothermia and hyperbaric oxygen resulted in significantly more severe lung damage compared to hyperbaric oxygen alone.
• Lung weight increased 2.7-fold in mice exposed to 5°C and hyperbaric oxygen.

Conclusions:

• Hypothermia does not protect against hyperbaric oxygen-induced central nervous system toxicity.
• Hypothermia potentiates hyperbaric oxygen toxicity, particularly leading to severe lung damage.
• The findings suggest that hypothermia may exacerbate, rather than mitigate, the adverse effects of hyperbaric oxygen exposure.