Breath Test To Measure Red Blood Cell Survival

BackgroundRed blood cell survival(RBCS)refers to the time from red blood cells(RBC)after being released from the bone marrow into the peripheral circulation to be removed by reticular endothelial system.RBCS is an important physiological index,and the important foundation to judge the change of RBC physiological pathology.To measure RBCS accurately helps to understand the causes of various anemia and RBC destruction,but also is the gold standard for hemolytic anemia diagnosis.In the previous methods,51 Cr labeling was once considered "gold standard" and became a clinical test item.But because of its radioaction,it is not suitable for the infant,children and pregnant women.And it needs to deal with the radioactive waste,which could increase the cost.Moreover,it needs to collect peripheral blood many times,and takes a period over a month.Therefore,hospitals in domestic have terminated 51 Cr labeling,and rare foreign hospital uses.15N-glycine labeling is a non-isotopic label.It is not only marking Hb,but also marking other proteins.Moreover,it can be reused by the new erythrocytes,which will affect the test result.And it has to be measured by the mass spectrometer,which also affecting its clinical application.Although biotin labeling has no radioactive damage,but it also takes more than a month.And biotin is a kind of foreign proteins,which may cause allergic potentially.Studies have found that human exhaled CO mainly comes from endogenous and exogenous inhalation.The former is derived from the hemoglobin(Hb)degradation(more than 86%)and non-Hb metabolism(no more than 14%).Of the CO derived from Hb degradation,85% come from RBC degradation,and 15% from non-erythrocyte Hb.Thus,about 70% of the endogenous CO of the exhaled gas is derived from erythrocyte degradation.When Hb is decomposed into bilirubin,?-methylene carbon in Hb generates CO,that is,one Hb produces one CO molecule.Therefore,exclusing the interference of exogenous CO,the metabolic rate of redblood cells can be calculated from end-tidal CO(ETCO).According to the result of Strocchi,when the body erythrocytes are at steady state that the rate of RBC generation equal to the rate of destruction,or when the synthesis rate of Hb is equal to its decomposition rate,RBCS can be calculated according to ETCO and Hb:RBCS(d)=Hb(g/mL)×1380/ETCO(ppm)However,currently,there is no large sample study of RBCS measured by CO breath test in healthy subjects,and no RBCS reference range for children and adolescents,and no system study of influencing factors of RBCS.Therefore,in this study,we used CO breath test to detect ETCO and RBCS in normal children and adolescents,and to explore the influencing factors of RBCS.In order to promote the application of CO breath test for clinical,and provide a basis for the differential diagnosis of anemia.Objective1.Establish a reference range for ETCO and RBCS in normal children.2.Investigate the influencing factors of ETCO and RBCS in normal children.Contents1.Measure the ETCO and RBCS in normal children,and establish a reference range for ETCO and RBCS in normal children.2.Analyse the influencing factors of RBCS.Methods1.Subject Inclusion criteria: 7 to 18 years old.Students of second grade,7th grade and 10 th grade in Guangzhou were selected as three age groups,each group 50,and gender is not limited.And MCV,Ret,WBC and IBIL are in the normal range.Exclusion criteria: does not meet any of the above criteria,or infection,or heart,liver,kidney and other organs dysfunction,or acute or chronic bleeding when detection,or within 24 hours before the test had active and / or passive smoking.Reject criteria:unable to cooperate with the exhaled gas collection,or gas samples were poorly preserved.2.Collection of information Information about the subjects,including age,sex,menstrual status,smoking,blood transfusion,medication and family history.3.Auxiliary inspection Including blood routine,reticulocyte and liver function.Who RBCS <x-1s were further examined: RBC morphology,urine analysis,anti-human globulin test,G6 PD activity test,Hb analysis,erythrocyte osmotic fragility test,abdominal B-ultrasonic.4.Gas collection,and ETCO and RBCS detection On the day of the above-mentioned auxiliary examination.(1)Alveolar gas collection: subjects holding the alveolar gas collection device,taking a deep breath and holding the breath 8 to10 seconds,and then blowing the alveolar gas into the collection bag,until collection bag sag is inflatable enough.(2)Environment air collection: pump the air into collection bag,until it is filled with gas.(3)ETCO and RBCS detection: inserted alveolar gas collection bags and environmental gas collection bags in the gas mouth of "alveolar gas" and "breath",and in the two "inverted bag" insert two inverted bags.After the four indicators are fully lit,press the "INPUT" button to input the Hb value.Then,press the "RUN / MEAS" key to start the measurement.5.Influencing factors Including age,gender,menstrual cycle,smoking,cavity gas bag size and alveolar gas specimens.6.Statistical analysis(1)The data were expressed by the measurement data,and analyzed by SPSS18.0 statistical software.The data were normality and F test.T test or Mann-Whitney U test were used to compare the average between the two groups,and ANOVA or Kruska-Wallis H test were used to compare three groups and above average.The correlation between RBCS and ETCO,Hb and Ret was analyzed by Pearson or Spearman correlation analysis.?= 0.05.(2)The date of ETCO and RBCS in normal children carry out the normality test.If the data conforms to normal distribution,its 95% reference range is "_x-1.96 s ~_x+1.96s",and 99% reference range is "_x-2.58 s ~_x+2.58s".If the data no conforms to normal distribution,its 95% reference range is P2.5~P97.5,and 99% reference range is P0.5~P99.5.Results1.ETCO and RBCS result The result of ETCO and RBCS in 222 normal children,whose aged were 7.02 to 17.68,was 1.589 ± 0.391 ppm,and the 95%reference range was 0.895 ~2.231 ppm,and the 99% reference range was 0.683~2.443 ppm.RBCS was 126 ± 32 days,and the 95% reference range was 72 ~174days,and the 99% reference range of 56~190 days.2.Correlation between RBCS and ETCO,Hb,RetRBCS was negatively correlated with ETCO and IBIL(r=-0.890,p=0.000,r=-0.331,p=0.000).RBCS was not associated with Hb and Ret(r=0.036,p=0.595,r=-0.043,p=0.525).3.Influencing factors Age,sex,menstrual period and cavity bag size had no effect on ETCO and RBCS,and smoking and alveolar gas sample leakage affected ETCO and RBCS.Conclusions1.The advantages of CO breath test to measure ETCO and RBCS are noninvasive,safe,simple,fast and stable.2.ETCO in normal children was 1.589 ± 0.391 ppm,and the 95% reference range was 0.895 ~2.231 ppm,and the 99% reference range was 0.683 ~2.443 ppm.3.RBCS in normal children was 126 ± 32 days,and the 95% reference range was72 ~174 days,and 99% reference range of 56~190 days.4.RBCS was negatively correlated with ETCO and IBIL,and not associated with Hb and Ret5.Age,sex,menstrual period and cavity bag size had no effect on ETCO and RBCS,and smoking and alveolar gas sample leakage affected ETCO and RBCS.