First aid management involves the basic principles of resuscitation, establishing an airway and ensuring that there is ventilation of the lungs and that the oxygenated blood is circulating; 100 per cent O2 should be administered as soon as possible. Further management depends on the aetiology of the hypoxia.
First aid: Airway – Head extended, lower neck flexed, jaw forward; foreign material, secretions removed.Breathing – If breathing, 100 per cent oxygen by mask; if not breathing, mouth-to-mouth or mouth-to-nose respiration followed by intermittent positive pressure resuscitation with 100 per cent oxygen when available.Circulation – If pulse absent, cardiac massage.
In many cases there may be an overlap of different causes of tissue hypoxia, and all patients should receive a high inspired O2 concentration.
Recompression or hyperbaric oxygenation may be indicated as a temporary measure to allow the foregoing regimens time to have an effect (see Chapters 6, 13 and 19).
These patients should be given supplemental inspired O2 or ventilated with 100 per cent O2 at whatever pressure is needed to ensure adequate arterial O2 levels. Once these goals have been achieved, the pressure and percentage of O2 can be progressively reduced while arterial gases or tissue O2 is monitored by transcutaneous oximetry.
The aim of therapy is to increase perfusion to the affected areas. This may require restoration of total circulatory volume, as well as vasodilator drugs, and hyperoxygenation as a temporary measure.
Blood loss from trauma may require blood transfusion with packed red blood cells after crystalloid or colloid resuscitation. Synthetic blood substitutes show promise but have yet to be introduced to clinical practice.
In the case of carbon monoxide poisoning, hyperbaric oxygenation may be lifesaving during the early critical period.
This form of hypoxia can be treated only by removing the toxic substance and using hyperoxygenation as a temporary measure.