A Study on the influence of flying height of medical rescue aircraft on sputum aspiration
Objective To study the effect of flight height of medical rescue aircraft on the efficacy of sputum suction on board.Methods The internal environment of medical rescue aircraft at flying heights of 0 m,1 000 m,2 350 m,3 350 m,and 4 300 m above sea level was simulated using low-pressure chambers.Artificial sputum of the same viscosity was used as the sample for experimentation.The same sputum suction equipment and procedures were adopted during the sputum suction test for the injured.The time taken by sputum suction was recorded separately.Results Under simulated conditions of a medical rescue helicopter flying at five different altitudes from the ground,the time required to suction 5 ml of simulated sputum gradually increased as the simulated flight altitude increased.The suction time at a height of 0,1 000,2 350,3 350 m and 4 300 m respectively was(4.26±1.13),(5.09±0.30),(9.37±1.00),(11.75±0.78)s and(15.54±0.92)s.The results of the analysis of variance showed that there was no statistically significant difference(P=0.27)between the sputum suction time at a flight altitude of 1 000 m and 0 m,while the differences in sputum suction time at flight altitudes of 2 350,3 350,4 300 m and 0 m were all statistically significant(all P＜0.001).The pairwise comparison results showed that there were statistically significant differences in the suction time at heights of 2 350 m and 1 000 m(P＜0.001),3 350 m and 2 350 m(P＜0.001),and 4 300 m and 3 350 m(P＜0.001).Conclusion The increase in flight altitude of medical rescue aircraft will increase the time required for each sputum suction,reducing the efficiency of sputum suction and increasing the risk of suffocation for patients.As flight altitude increases,effective measures such as increasing negative pressure and humidifying the airway should be taken to ensure the effectiveness of sputum suction on board.
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