ABSTRACT
Oxygen can be used, at least as a first aid, in almost all serious scuba diving accidents.
Breathing dry air, at 1 ATA results in an inspired oxygen pressure of approximately 160 mmHg. The oxygen pressure is diluted somewhat due to the 'dead space' of the respiratory passages, the continual absorption of oxygen from the lungs, and humidification, resulting in an alveolar oxygen pressure (PAO2) of approximately 100 mmHg. The arterial oxygen level (Pao2) reaches about 673 mmHg, if 100 per cent oxygen is breathed. These and subsequent figures are approximations, and vary with many factors such as ventilation perfusion ratio, haemoglobin, pH, exercise and carbon dioxide (CO2) levels.
