Research On Ultrasound Evaluation And Protection Of Severe Blast Lung Injury

Backgrounds:Nowadays,with the continuous conflicts in the world and the frequent occurrence of terrorist events and life accidents,both soldiers and ordinary people are facing the threat of blast injuries.As one of the most vulnerable target organs of blast injury,the morbidity and mortality of blast lung injury is high.Besides,lack of effective evaluation methods in the early stage also attracted widespread attention.Ultrasound is widely used in the critical care medicine because it can quickly scan the chest to identify different causes of dyspnea.It also provides a choice for diagnosis on site.At the same time,due to the lack of targeted treatment means for blast lung injury,protection is particularly important.While the bulletproof clothing in active use mainly focuses on the performance of fragment prevention,the performance of shock wave prevention is poor.Polyurea material came into public eyes just because of its excellent mechanical properties and good dissipation performance to shock wave.So it has a wide range of application prospects in the field of protective equipment.Materials and methods:1.Twenty female healthy goats were randomly divided into three groups by different driving pressures:4.0MPa group?n=4?,4.5MPa group?n=12?and 5.0MPa group?n=4?.The severe blast lung injury model of goats was established using a BST-I bio-shock tube.Vital signs?respiration,heart rate and blood pressure?,lung ultrasound score?LUS?,PaO₂/FiO₂ and extravascular lung water?EVLW?were measured before injury?0 h?and at 0.5 h,3 h,6 h,9 h,12 h after injury,and LUS was examined by D236 portable wireless color ultrasound device.Computed tomography scan was performed before injury?0 h?and at 12 h after injury for dynamic monitoring of blast lung injury and measurement of lung volume.The correlation of LUS with PaO₂/FiO₂,EVLW,and lung injury ratio?lesion volume/total lung volume*100%?was analyzed.All animals were sacrificed at 12 h after injury for gross observation of lung injury and histopathological examination.2.To observe the changes of gross injury of lung in rats,covered with a series of polyurea materials after molecular structure modification or micron glass particle inclusions,BST-I bio-shock tube was used under the driving pressure of 5.0MPa-6.0MPa to cause blast injury.Seventy-one male healthy SD rats were randomly numbered and divided into non-protective control group?C:n=38?and polyurea protective groups?PUR1:n=8;PUR2:n=3;PUR1/G10:n=3;PUR1/G30:n=3;PUR3A:n=2;PUR3B:n=3;PUR3C:n=3?.Normal group?N:n=8?was observed without any treatment.According to the animal's body shape,the protective materials were wrapped around the rat's chest and abdomen in a small cylinder,and the non-protective group didn't wear any materials.Mortality was rated within6h after injury in each group.All animals were sacrificed at 6 h after injury for gross observation of lung injury.Pressure testing device was arranged at the end of BST-I biological shock tube.The peak pressure of shock wave in shock tube was measured under the driving pressure of 4.0MPa,4.5MPa and 5.0MPa respectively.Then different polyurea materials?PUR1,PUR2,PUR1/G30,PUR2/G30 and PUR3?were fixed on the device's surface and peak pressure of shock wave behind materials were tested respectively under the driving pressure of 5.0MPa.The attenuation rates of different materials were calculated.3.A 7kg TNT explosive ball was used to observe the changes in the peak pressure of shock waves in a human torso model,covered with a series of polyurea materials after molecular structure modification or micron glass particle inclusions,at 3.8m and 5.8m from the explosion center respectively under open field conditions.The first experiment is divided into the ultra-high molecular weight polyethylene?UHWPE,PE?and new polyurea series+PE groups.The new polyurea materials are divided into three types?PUR1,PUR2,PUR3?according to the molecular structure transformation method,and two types?PUR1,PUR2?of them contain three types?none,G20,G30?of volume fractions of glass particles respectively.A total of seven types were thus included.Then a typical type of polyurea with good blast mitigation was selected in the bioprotective evaluation.In the second experiment,a goat chest mold for anti-blast was were prepared.Twenty-four experimental goats were randomly divided into the unprotected,PE,polyurea?PUR?,and polyurea?PUR?+PE groups.Based on the estimation of peak pressure of 7kg TNT air explosion,the chest wall acceleration,vital signs,cavity organ injuries,and gross injury levels in explosions as previously described were observed at 3.6m and 3.8m from the explosion center.Results:1.At 12 h after injury,the mortality of goats was 0,41.67%and 100%in the 4.0MPa,4.5MPa and 5.0MPa groups respectively;the lung injury ratio was 17.10%±4.02%in the4.0MPa group and 34.15%±7.62%in the 4.5MPa group;the area of pulmonary hemorrhage was 20.00%±13.14%in the 4.0MPa group and 42.14%±15.33%in the 4.5MPa group.A severe blast lung injury model was established under the driving pressure of 4.5MPa.The respiratory rate,heart rate,LUS and EVLW were significantly increased,while PaO₂/FiO₂was significantly reduced immediately after injury,and then they gradually recovered and became stabilized at 3 h after injury.?3?LUS was positively correlated with EVLW?3 h:r=0.597,6 h:r=0.698,9 h:r=0.729;p<0.05?and lung injury ratio?12 h:r=0.884,p<0.05?,negatively correlated with PaO₂/FiO₂?3 h:r=0.871,6 h:r=0.637,9 h:r=0.658;p<0.05?2.Under the driving pressure of 5.0MPa-6.0MPa,the blast lung injuries were mainly severe injuries,while polyurea protective groups basically had no injury or slight injuries.At6h after injury,the mortalities of all polyurea protective groups were 0 and group C was47.37%.The average peak pressures of shock wave in shock tube under the driving pressure of 4.0MPa,4.5MPa and 5.0MPa were 383.68±51.68kPa,418.21±51.37k Pa and503.28±55.52kPa respectively;the attenuation rates of peak pressure PUR1,PUR2,PUR1/G30,PUR2/G30 and PUR3 under the driving pressure of 5.0MPa were 23%,33%,44%,50%and 52%respectively.3.At 3.8m and 5.8m from the explosion center,the attenuation effects of new polyurea group on shock waves were increased by 23%-35%and 25%-50%,respectively,compared with the PE group.At 3.6m and 3.8m from explosion center,the chest wall acceleration in the polyurea+PE group was preferably 55.56%and 65.20%lower than that in the unprotected group,respectively.The lung injury was significantly alleviated compared with the PE group,and the injury was reduced by 2 levels.Conclusions:1.We established a severe blast lung injury model of goats using the BST-I bio-shock tube under the driving pressure of 4.5MPa which mortality at 12h after injury was 41.67%and average area of pulmonary hemorrhage was of severe grade.And we confirmed that ultrasound can be used for quick evaluation and dynamic monitoring of blast lung injury.2.The polyurea materials could significantly reduce severe blast lung injury in bio-shock tube of rats.The protective effect of CPUR series is better than that of PUR series in gross scores of lungs and pressure attenuation results.3.Under the simulated open field explosions,new polyurea materials had good attenuation and biological protective effects on the shock wave.