New Technologies And Mechanisms For Monitoring And Protecting Acute Compartment Syndrome

Background and aimsAcute osteofascial compartment syndrome(AOCS)is a surgical clinical syndrome that requires urgent treatment.Delays in diagnosis and treatment can lead to serious poor prognosis.The current clinical diagnosis and treatment methods are single,and it is difficult to achieve early diagnosis of AOCS only by relying on medical history and clinical manifestations.Osteofascial incision and decompression should be performed immediately after diagnosis of AOCS patients.As the only passive treatment method after AOCS diagnosis,osteofasciotomy decompression is only recommended for early diagnosis of AOCS,because late AOCS fasciotomy decompression is often accompanied by many serious clinical complications.Therefore,the current dilemma in the diagnosis and treatment of AOCS lies in the lack of early diagnosis methods and standards,and the lack of early effective intervention methods for AOCS to reduce skeletal muscle damage and slow down the progression of AOCS disease.Therefore,the purpose of this research is to explore new technologies and mechanisms for early monitoring and protection of AOCS.Bedside ultrasound is becoming more and more widely used in clinical applications.A small number of studies have found that increased pressure in the fascia can cause changes in the blood flow spectrum of the limbs.Therefore,ultrasound Doppler may have the value of early monitoring of AOCS.The AOCS skeletal muscle damage is related to the imbalance of cell energy supply and demand.Therefore,increasing the skeletal muscle energy supply and reducing energy demand can reduce the early damage of AOCS.Studies have found that long-chain free fatty acids may improve tissue ischemia-reperfusion injury,while medium-chain fatty acids have more metabolic advantages than long-chain fatty acids,suggesting that medium-chain fatty acids may reduce AOCS skeletal muscle damage,but there is currently a lack of relevant research.While low temperature reduces tissue energy requirements,studies have proven its protective effect on skeletal muscle ischemia-reperfusion injury,but because the specific low temperature strategy is unknown,clinical promotion and research cannot be carried out.Therefore,the purpose of this study is: 1.To study the continuous monitoring value of ultrasound Doppler in the AOCS process.2.To study the protective effect of sodium caprylate on AOCS and related mechanisms.3.Discuss the low temperature intervention strategy and low temperature protection mechanism of AOCS.MethodsPart 1:The pressure increase of acute compartment syndrome is simulated by the stepwise compression of the calf,and a healthy human AOCS model is constructed.The Doppler blood flow spectrum of the proximal popliteal artery,poplitral vein and the distal dorsal foot artery were monitored under different pressure levels by Doppler ultrasound.Measure the vascular cross-sectional shape and flow velocity changes and calculate the relevant blood flow spectrum parameters.The perfusion pressure was30 mm Hg as the threshold for AOCS diagnosis and ROC curve analysis.Part 2:Acute compartment syndrome was built by injecting nomal saline into fascia chambr in the lower limbs in 18 male SD rats.After maintaining the pressure in the fascia chamber at 80 mm Hg for 2h,the fascia was incised.The animals were divided into 3 groups: sham group,AOCS group and Sodium octanoate group(SO group).In the Sodium octanoate group,160 mg/kg Sodium octanoate solution was given by intraperitoneal injection at the beginning of nomal saline injection.Before operation and within 2 days after operation,the animal’s lower limb movement ability was evaluated every day.After 2 days,the tibial anterior muscle was taken for histopathological evaluation and TUNEL test.Western blot was used to detect the expression of mitochondrial dynamics-related proteins,verifying that Sodium octanoate played a protective role in tissue protection by regulating mitochondrial morphology.Part 3:30 male SD rats constructed an ischemia related AOCS model through lower limb arteriovenous occlusion.After 2 hours of ischemia,the arteries and veins were opened for reperfusion.The animals are divided into 5 groups: sham group,AOCS group,ischemic hypothermia group(ITH group),reperfusion hypothermia group(RTH group)and hypothermia during ischemia-reperfusion group(IRTH group).The target temperature for skeletal muscle hypothermia is 20°C.In the ITH group,the tissues of the anterior tibial fascia compartment of the lower limbs were hypothermic for 2h during ischemia.In the RTH group,hypothermia was 2 hours early in the reperfusion period.In the IRTH group,2 hours during ischemia combined with 2 hours of hypothermia during the early reperfusion period.Measure the intra-fascial pressure during the operation.The tibial anterior muscle was taken 4 days after the operation for histopathological evaluation and TUNEL test.Part 4:Male SD rats were used to inject nnomal saline into the fascia chamber to construct a rat model of acute compartment syndrome in the lower limbs.After maintaining the pressure in the fascia chamber at 80 mm Hg for 2h,the fascia was incised.120 SD rates are divided into 5 groups: sham group,AOCS group,30℃ TH group,25℃ TH group and 20℃ TH group.The hypothermia time of skeletal muscle is2 hours from the ischemic period of water injection and 4 hours in the early reperfusion period after incision.Before and 7 days after the operation,the animal’s lower limb movement ability was evaluated every day.After 7 days,the tibial anterior muscle was taken for histopathological evaluation and TUNEL test.Part 5:Constructing C2C12 cell oxygen and glucose deprivation(OGD)model,deglycosylation and deoxygenation for 4h,and reglycosylation and reoxygenation for4 h.The cells are divided into 3 groups: control group,OGD group and TH group.The X hypothermic group had a low temperature of 32°C during the deglycosylation and deoxygenation period,and then reoxygenated at 37°C.Compare the three groups of cells CCK8 cell activity,LDH release,superoxide,SOD content,and detect the mitochondrial membrane potential of the three groups,and TUNEL to detect the level of apoptosis.After transfection of si RNA-cirbp plasmid and cirbp plasmid,compare the control group,OGD group,si RNA-cirb transfection group,cirbp transfection group HIF-1α,cirbp,mitochondrial apoptosis pathway related proteins(bax,bcl-2,casp3,casp9)protein expression levels.ResultsPart 1:Popliteal artery peak flow velocity,valley flow velocity,resistance index,and reverse blood flow ratio increase with the increase of intrafascial pressure(all P<0.05).Popliteal vein peak flow velocity gradually increases as the pressure inside the fascia increases(P<0.001),the peak velocity of the dorsal foot artery,the forward blood flow ratio gradually decrease as the pressure increase in the fascia chamber(all P<0.05),while the parvus tardus waveform ratio of the dorsal artery gradually increases during the compression process(P<0.05).The ultrasound Doppler was selected to construct an AOCS prediction model.The best model ROC curve analysis AUC=0.921,the diagnostic sensitivity was 81.7%,and the specificity was 90.9%.Part 2:The behavioral scores of lower limbs in the AOCS group decreased,and the behavioral scores in the Sodium octanoate group were higher(all P<0.05).In the AOCS group,the neutrophil infiltration and cell necrosis of the tibial anterior muscle increased at 2 days postoperatively.Compared with the AOCS group,the neutrophil infiltration and cell necrosis in the SO group were less.The apoptosis of tibial anterior muscle cells increased in the AOCS group 2 days after surgery,while the number of apoptosis in the SO group was less than that in the AOCS group.Western blot results showed that the expression of mitochondrial dynamics related proteins in the AOCS group was down-regulated after surgery,while the mitochondrial dynamics related proteins in the SO group had an increasing trend compared with the AOCS group.Part 3:The intrafascial pressure in the AOCS group was significantly increased during ischemia and reperfusion,while the intrafascial pressure in the ITH and IRTH groups was lower(all P<0.05).In the AOCS group,the neutrophil infiltration and cell necrosis of the tibial anterior muscle increased significantly 4 days after the operation.However,there was less neutrophil infiltration and cell necrosis in the ITH and IRTH groups.The apoptotic number of tibial anterior muscle cells increased significantly in the AOCS group 4 days after surgery,while the number of apoptotic cells in the ITH group and IRTH group was less(both P<0.05).Part 4:The lower limb behavioral scores of the AOCS group decreased after the operation,and the behavioral scores of the 30 ℃ TH group and the 25 ℃ TH group improved after the operation.In the AOCS group,the normal structure of muscle fibers was lost,neutrophil infiltration,and necrotic cells increased;compared with the AOCS group,muscle fiber necrosis and neutrophil infiltration in the 30℃ group,25℃ group and 20℃ group were less at different time points after surgery.The apoptotic number of tibial anterior muscle cells in the AOCS group increased significantly after 3 days,while the number of apoptotic cells in the 30°C TH group and 25°C TH group was less(both P<0.05).Part 5:C2C12 cells after OGD injury decreased cell activity detected by cck8,increased LDH release,increased superoxide production,decreased mitochondrial membrane potential,increased TUNEL apoptotic cells(all P<0.05);compared with OGD group injury,TH group cell activity increased,LDH release decreased,superoxide production decreased,SOD production increased,mitochondrial membrane potential decreased,and TUNEL apoptotic cells increased(all P<0.05).Early low temperature after AOCS stimulates the expression of CIRBP protein,which further promotes the increase of HIF-1α expression and reduces the activation of mitochondrial-related apoptosis pathways.After si RNA inhibits the expression of CIRBP,the expression of HIF-1α decreases and promotes the activation of mitochondrial-related apoptosis pathways.ConclusionsPart 1 : Ultrasound Doppler can be used for early monitoring of acute compartment syndrome.The proximal arterial reverse blood flow ratio,the distal forward blood flow ratio and the parvus tardus waveform ratio are early sensitive indicators.Ultrasound Doppler ’s clinical application needs further research.Part 2:The early application of Sodium octanoate in AOCS can effectively reduce the pathological damage and apoptosis of skeletal muscle.Part 3:Hypothermia during ischemia or combined hypothermia during ischemia reperfusion can effectively improve the pathological damage of patients with ischemia related AOCS,while the effect of hypothermic tissue protection during reperfusion alone is poor.Part 4:Early mild and moderate hypothermia have tissue protective effects on AOCS injury to skeletal muscle,while the protective effect of severe hypothermia is lower than that of mild and moderate hypothermia.Part 5:The protective mechanism of low temperature on AOCS skeletal muscle may be through cold-induced RNA binding protein to up-regulate HIF-1α,regulate mitochondrial apoptosis-related pathways,and mediate tissue protection after OGD in skeletal muscle cell.