What is the most dangerous sign of hypoxic hypoxia?

Impaired judgement and impaired self-criticism is considered the most dangerous sign of hypoxic hypoxia because these cognitive effects can significantly impact a person's ability to recognize and respond to their deteriorating condition. When an individual experiences hypoxia, especially at higher altitudes, the brain receives insufficient oxygen, which can lead to confusion, impaired decision-making, and a reduced ability to assess their own performance and safety critically.

These impairments make it difficult for the pilot or crew member to identify that they are experiencing hypoxia and may compromise their ability to take necessary corrective actions, such as descending to a lower altitude or using supplemental oxygen. This lack of self-awareness can lead to dangerous situations, as the individual may not realize they are in trouble until it is too late.

While decreased heart rate, increased respiration rate, and bluish skin can also indicate hypoxia or its effects, they are not as critical in terms of immediate decision-making and safety responses. The cognitive effects associated with impaired judgement mean that the person is less likely to react appropriately to other symptoms or the conditions that might be putting them and others at risk. Thus, the neurological impacts of hypoxia, particularly on judgement and self-awareness, are paramount to understanding the dangers it poses.