| Purpose:In order to provide evidence for the treatment of clinical severe asthma,we will give the asthma model mechanical ventilation and explore the appropriate positive end expiratory pressure(PEEP)after we had established severe asthma rabbits model.Method:1.Rabbits were randomly divided into control group and model group.According to the different PEEP,the model group were divided into OcmH2O group,3cmH2O group,5cmH2O group,10cmH2O group.Each group has 5 big white rabbits.2.10%Aluminum hydroxide(Al(OH)3)gelatine preparation:We took sodium hydroxide(NaOH)and aluminum sulfate(Al2(S04)3)in proportion,and let them dissolve in sterile water respectively,mixed and separated the precipitation.Finally,we produced 10%Al(OH)3 gelatine.3.Establishment of asthma model:The model group were injected intraperitoneally with 4mg albumin(OVA)+400mg Al(OH)3 gelatine in 2ml mixture at the first day and the 8th day respectively.The model group were atomized with 8ml OVA solution for 20 minutes at the 15th to the 19th day.Between the 20th day and the 23th day,the rabbits were continuously inspired with ozone for 10 minutes.In the control group,we replaced OVA with saline,and replaced the ozone with air to build a fake asthma model,and then the rest steps were the same with the model group.4.All rabbits were anesthetized,intubated,then ventilated.The model group were atomized with 20 mg/ml acetylcholine(Ach)to build the severe asthma model,then measured respiratory indicators and blood gas analysis before treatment.Then different groups were given different PEEP,and ventilated for 2 hour.And then measured respiratory indicators and blood gas analysis again.The control group was ventilated and atomized with physiological saline instead of Ach.Then set PEEP at 0cmH2O,and the rest steps were the same with the model group.5.Killed rabbits,lavaged left lung,then measured the protein of bronchoalveolar lavage fluid(BALF).The right lung was subjected to hematoxylin-eosin(HHE)staining.We observed 10 fields randomly.And the number of lymphocytes and eosinophils in bronchial mucosa and submucosal lung tissue under the radius of 0.3mm were counted.Result:1.Successfully build the asthma model1)During the day of the asthma model established,rabbits in the model group showed cough,rapid respiration,cyanosis.At the same time,rabbits had obvious scratched face action,and did not like moving.2)Compared with the control group,the number of eosinophils,lymphocytes in lung tissue of rabbit asthma models and total protein content of BALF increased significantly.3)The respiratory mechanics of the rabbit asthma models were significantly changed,and the airway resistance,intrinsic PEEP(PEEPi),the platform pressure in the model group were significantly higher;The lung compliance was significantly lower;All of these were similar to the changes of asthma model.4)Compared with the control group,the blood gas indexs of the rabbit asthma model were significantly changed,and partial pressure of oxygen(PaO2)significantly decreased,partial pressure of carbon dioxide in arterial blood(PaCO2)significantly increased;Both of them were the same with severe asthma blood gas indexs.2.The effects of mechanical ventilation treatment in severe asthma1)Mechanical ventilation could improve the cyanosis symptom of asthmatic rabbits.2)3cmH2O PEEP could significantly improve airway resistance,airway plateau pressure and PEEPi in asthmatic rabbits,and the next one was 5cmH2O PEEP.3)PEEP had no obvious effect on lung compliance in asthmatic rabbits.4)After the models treated with 3cmH2O PEEP,the PaO2 was significantly increased in asthmatic rabbits,and the next one was 5cmH20 PEEP.5)After the models treated with 3cmH2O PEEP,the PaCO2 was significantly decreased in asthmatic rabbits.Conclusion:During mechanical ventilation,3cmH2O and 5cmH2O PEEP are beneficial for the treatment of severe asthmatic rabbits,and 3cmH2O PEEP is more significant. |
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