Measurement Of Diaphragm Contraction Function In Process Of Acquired Funnel Chest Formation On Rats

Objective: By measurement of the acquired funnel chest rat diaphragmatic musclecontraction force,explore acquired funnel chest in the formation of the change of thediaphragm contraction function.Methods: Four weeks SD rats one hundred and twenty,divided into the experimentalgroup and the control sixty.The experimental group through the sternum cut off forthree under observation of rib cartilage formation funnel chest,the control groupwithout any treatment.Take each group of10animal specimens of diaphragm at3d、1w、2w、4w、8w and12w after chest made model animals.Assessments were madeof the diaphragm contractility only ten with the control group rats and theircontrol,such as peak twitch tension(Pt),maximum tetanic tension(Po),and calculate thediaphragm force-frequency relationships.Two groups of Pt and Po corresponding timepoints between groups of the measurement results of t test analysis;Two groups ofdiaphragmatic muscle tension under different frequency corresponding time pointsbetween groups of the measurement results of variance analysis.Results: Funnel with in a week after chest made model animals a marked changerespiratory condition,in the subsequent breeding process,the chest area graduallybegan to sink in seven days,the groove shaped change and gradually aggravate in tendays,broadening the range of the anterior chest wall subsidence in two weeks,formeda typical funnel chest deformity,three to four weeks deformity and heavy speedgradually slow,basically stable after4weeks,with no obvious difference betweentwelve weeks.there is no visible difference for the animal survival state betweennormal animals and the experimental group in process of acquired funnel chest. The results of peak twitch tension and maximum tetanic tension at each timepoint after the test results in the age between animal group is significantdifference,which is statistically significant. while diaphragmatic muscle contractionforce is falling in3days after chest made model animals, decreased obviously in1wand2w, maintained in a low status in4w.Under the stimulus frequency of10、20、40、60、100Hz,With the increasingof stimulus frequency, two groups of animals diaphragmatic muscle contractiontension increased. but the result is that at each time point the experimental group werelower than the control group, which is significant difference(p<0.05). Under the samefrequency, in3d、1w and2w after chest made model animals of test results in thesame age control group, there are significant difference observed(p<0.05). in4w、8wand12w after chest made model animals of test results in the same age control group,there are no significant difference observed(p>0.05).Conclusion: The rat diaphragmatic muscle contraction force drops in process ofacquired funnel chest formation,it cannot restore after stability of the deformity.Despite the fact that there is obvious contraction reserve capacity in process ofacquired funnel chest formation, still below the normal level.