Objective:To investigate the effects of a single deep helium-oxygen (heliox) diving on divers’ pulmonary function.Methods:In April 2019, 15, 5, and 6 male divers of the Second Detachment of Risk Prevention and Rescue were selected to perform the 80 m, 100 m, and 120 m heliox diving, respectively. Their pulmonary functions were measured before, immediately after, and 24 h after diving.Results:The forced expired volume in one second (FEV1.0) / forced vital capacity (FVC), and maximum expiratory flow at 25% of vital capacity (MEF 25%) of divers immediately after 80 m heliox diving were lower than those before diving, and there were statistically significant differences ( P<0.05). The FEV1.0, FEV1.0/FVC, peak expiratory flow (PEF), and maximum expiratory flow at 75% of vital capacity (MEF 75%) of divers immediately after 100 m and 120 m heliox diving presented a decreasing trend, but there was no statistically significant difference( P>0.05). The results of the above measurements 24 h after the diving rebounded close to the levels before diving. Conclusion:A single deep heliox diving can cause temporary expiratory and small airway dysfunction, which will disappear 24 h after the diving.

Objective:To investigate the effects of a single deep helium-oxygen (heliox) diving on divers’ pulmonary function.Methods:In April 2019, 15, 5, and 6 male divers of the Second Detachment of Risk Prevention and Rescue were selected to perform the 80 m, 100 m, and 120 m heliox diving, respectively. Their pulmonary functions were measured before, immediately after, and 24 h after diving.Results:The forced expired volume in one second (FEV1.0) / forced vital capacity (FVC), and maximum expiratory flow at 25% of vital capacity (MEF 25%) of divers immediately after 80 m heliox diving were lower than those before diving, and there were statistically significant differences ( P<0.05). The FEV1.0, FEV1.0/FVC, peak expiratory flow (PEF), and maximum expiratory flow at 75% of vital capacity (MEF 75%) of divers immediately after 100 m and 120 m heliox diving presented a decreasing trend, but there was no statistically significant difference( P>0.05). The results of the above measurements 24 h after the diving rebounded close to the levels before diving. Conclusion:A single deep heliox diving can cause temporary expiratory and small airway dysfunction, which will disappear 24 h after the diving.

Objective:To calculate a new depth-time heliox conventional diving decompression scheme for improving the training efficiency of deep heliox conventional diving.Methods:Based on the classical calculation model of Haldane’s diving decompression scheme, we used its supersaturation safety coefficient for 60-120 m heliox conventional diving decompression scheme, calculated the decompression schemes for 80 m/15 min, 100 m/15 min, and 120 m/15 min depth-time diving, and verified them by training.Results:The total decompression time of the three schemes were shortened by 20, 31, and 36 min respectively than those of the depth/ 20 min scheme at the same depth. After 54 person/times heliox conventional diving trials, no decompression sickness symptoms were found.Conclusion:A new heliox conventional diving decompression scheme with every 5 minutes as an interval for underwater operation can effectively improve the diving training efficiency while ensuring divers’ safety.

Objective:To calculate a new depth-time heliox conventional diving decompression scheme for improving the training efficiency of deep heliox conventional diving.Methods:Based on the classical calculation model of Haldane’s diving decompression scheme, we used its supersaturation safety coefficient for 60-120 m heliox conventional diving decompression scheme, calculated the decompression schemes for 80 m/15 min, 100 m/15 min, and 120 m/15 min depth-time diving, and verified them by training.Results:The total decompression time of the three schemes were shortened by 20, 31, and 36 min respectively than those of the depth/ 20 min scheme at the same depth. After 54 person/times heliox conventional diving trials, no decompression sickness symptoms were found.Conclusion:A new heliox conventional diving decompression scheme with every 5 minutes as an interval for underwater operation can effectively improve the diving training efficiency while ensuring divers’ safety.

Objective To explore changes in the capacity and working efficiency of divers performing deep saturation dives at various depths.Methods The divers completed the specified underwater operations at the depths of 70 m,255 m and 493 m,and changes in their working efficiency were assessed by working time and errors occurred during the underwater operations.Results The time consumed for the joining up of flanges,the binding and measurement of underwater objects at the depth of 255 m all significantly prolonged,when compared with the time used at 70 m(P <0.05).The time used for the joining up of flanges,the binding of underwa-ter objects at the depth of 493 m did not prolong significantly,when compared with the time spent at 255 m(P <0.05).However,the time used for underwater measurement prolonged significantly(P <0.01)and the rate of error both in the joining up of flanges and meas-urement of underwater objects increased significantly (P <0.05).Conclusion In deep saturation dives,the capability and working ef-ficiency of divers all considerably reduced.The greater the depths were,the more significantly their operating dexterity and short-term memory were affected.

Objective To explore changes in the capacity and working efficiency of divers performing deep saturation dives at various depths.Methods The divers completed the specified underwater operations at the depths of 70 m,255 m and 493 m,and changes in their working efficiency were assessed by working time and errors occurred during the underwater operations.Results The time consumed for the joining up of flanges,the binding and measurement of underwater objects at the depth of 255 m all significantly prolonged,when compared with the time used at 70 m(P <0.05).The time used for the joining up of flanges,the binding of underwa-ter objects at the depth of 493 m did not prolong significantly,when compared with the time spent at 255 m(P <0.05).However,the time used for underwater measurement prolonged significantly(P <0.01)and the rate of error both in the joining up of flanges and meas-urement of underwater objects increased significantly (P <0.05).Conclusion In deep saturation dives,the capability and working ef-ficiency of divers all considerably reduced.The greater the depths were,the more significantly their operating dexterity and short-term memory were affected.