摘要：The induced cessation of ventilation or suspension of external breathing is a common occurrence in anaesthetic practice. During the period of induced apnoea, there is no movement of the muscles of inhalation and lung volumes initially remain unchanged. Maintaining haemoglobin saturation during airway management is critical to guarantee the safety of patients. However, there has been little quantitative study of apnoea especially on the rate of change in oxygen saturation in relation to haemoglobin concentration in the apnoeic period of induction of anaesthesia. The study sought to determine the safe apnoea period in relation to haemoglobin concentration. The study showed that patients with low haemoglobin concentration took less time to reach 100% oxygen saturation, while those with high haemoglobin concentration took more time to reach 100% oxygen saturation during pre-oxygenation. The study found that the average safe apnoea period for patients in relation to haemoglobin concentrations to desaturation (from 100% - 92%) following the administration of suxamethonium was 7.0 - 9.9 g/dl was 3:15.07 minutes, 10.0 - 12.9 g/dl was 3:43.05 minutes and 13.0 - 16 g/dl was 4:23.04 minutes. And the overall safe apnoea time for the patients was 3:27.02 minutes. All the patients who attained 100% oxygen saturation without inhaling 100% oxygen were living in mountainous areas. The mean induction period (6:52.26 ms) of the patients was higher than the mean safe apnoea period (3:27.02 ms). The study recommends that anaemia should be corrected before induction of anaesthesia and people living at high altitude should be advised to occasionally move down to areas of low altitude to improve tissue oxygenation.
