Objective:To investigate the efficacy and safety of doxycycline in children with macrolide-resistant mycoplasma pneumoniae pneumonia（MRMPP）.Methods:A retrospective analysis was conducted on the data from 92 children with severe MRMPP admitted to the Intensive Care Unit of Hunan Children's Hospital from January 2020 to November 2023.Depending on antibiotic treatment strategies for mycoplasma pneumoniae，patients were divided into three groups：Doxycycline group（those treated with doxycycline，12 cases）；Azithromycin group（those treated with azithromycin，53 cases）；and Switch group（those switched from azithromycin to doxycycline，27 cases）.Clinical outcomes and adverse reactions were compared among the three groups.Results:Significant statistical differences were found among the three groups in terms of age（ F=49.365， P<0.001）and weight（ H=40.595， P<0.001），with the Doxycycline group presenting the highest average age and median weight，followed by the Switch group，and then the Azithromycin group.After antibiotic treatment，children in the Doxycycline group，when compared to the Switch group and the Azithromycin group，showed a shorter fever resolution time[3.0（2.0，3.8）days vs.5.0（4.0，5.0）days vs.6.0（5.0，7.0）days， H=25.243， P<0.001]，a higher defervescence rate at 48 hours and 72 hours (41.7% vs.0 vs.0 at 48 hours，and 75.0% vs.0% vs.5.7% at 72 hours，both P<0.001]，a shorter mechanical ventilation duration[83.0（70.0，93.0）hours vs.135.0（129.0，172.0）hours vs.152.0（139.0，164.5）hours， H=9.980， P=0.007]，a shorter ICU stay[7.0（6.0，8.0）days vs.10.0（8.0，13.0）days vs.11.0（9.0，13.0）days， H=21.887， P<0.001]，and a lower proportion of Methylprednisolone usage [8.3% vs.57.1% vs.54.7%， P=0.008].There was no significant statistical difference in extrapulmonary complications and co-pathogens（both P>0.05）.Gastrointestinal reactions occurred in all children treated with doxycycline and azithromycin，with rates of 10.3%（4/39）and 13.8%（11/80）,respectively，showing no statistical significance（ P=0.771）.Among the 67（72.8%）cases with available follow-up data，the incidence of bronchiolitis obliterans was 8.3%（1/12）in the Doxycycline group，13.6%（3/22）in the Switch group，and 15.2%（5/33）in the Azithromycin group，with no statistical significance（ P>0.05）.Among the 34 cases using doxycycline with follow-up data available，none had tooth discoloration or enamel hypoplasia related to the medication. Conclusion:Doxycycline in the treatment of severe MRMPP in children could rapidly improve clinical symptoms，shorten the course of the disease，reduce the likelihood of methylprednisolone use，and is relatively safe for short-term use.

Objective:To investigate the efficacy and safety of doxycycline in children with macrolide-resistant mycoplasma pneumoniae pneumonia（MRMPP）.Methods:A retrospective analysis was conducted on the data from 92 children with severe MRMPP admitted to the Intensive Care Unit of Hunan Children's Hospital from January 2020 to November 2023.Depending on antibiotic treatment strategies for mycoplasma pneumoniae，patients were divided into three groups：Doxycycline group（those treated with doxycycline，12 cases）；Azithromycin group（those treated with azithromycin，53 cases）；and Switch group（those switched from azithromycin to doxycycline，27 cases）.Clinical outcomes and adverse reactions were compared among the three groups.Results:Significant statistical differences were found among the three groups in terms of age（ F=49.365， P<0.001）and weight（ H=40.595， P<0.001），with the Doxycycline group presenting the highest average age and median weight，followed by the Switch group，and then the Azithromycin group.After antibiotic treatment，children in the Doxycycline group，when compared to the Switch group and the Azithromycin group，showed a shorter fever resolution time[3.0（2.0，3.8）days vs.5.0（4.0，5.0）days vs.6.0（5.0，7.0）days， H=25.243， P<0.001]，a higher defervescence rate at 48 hours and 72 hours (41.7% vs.0 vs.0 at 48 hours，and 75.0% vs.0% vs.5.7% at 72 hours，both P<0.001]，a shorter mechanical ventilation duration[83.0（70.0，93.0）hours vs.135.0（129.0，172.0）hours vs.152.0（139.0，164.5）hours， H=9.980， P=0.007]，a shorter ICU stay[7.0（6.0，8.0）days vs.10.0（8.0，13.0）days vs.11.0（9.0，13.0）days， H=21.887， P<0.001]，and a lower proportion of Methylprednisolone usage [8.3% vs.57.1% vs.54.7%， P=0.008].There was no significant statistical difference in extrapulmonary complications and co-pathogens（both P>0.05）.Gastrointestinal reactions occurred in all children treated with doxycycline and azithromycin，with rates of 10.3%（4/39）and 13.8%（11/80）,respectively，showing no statistical significance（ P=0.771）.Among the 67（72.8%）cases with available follow-up data，the incidence of bronchiolitis obliterans was 8.3%（1/12）in the Doxycycline group，13.6%（3/22）in the Switch group，and 15.2%（5/33）in the Azithromycin group，with no statistical significance（ P>0.05）.Among the 34 cases using doxycycline with follow-up data available，none had tooth discoloration or enamel hypoplasia related to the medication. Conclusion:Doxycycline in the treatment of severe MRMPP in children could rapidly improve clinical symptoms，shorten the course of the disease，reduce the likelihood of methylprednisolone use，and is relatively safe for short-term use.

Objective:To summarize and analyze the results of gene detection and clinical characteristics of children with unknown etiology in pediatric intensive care unit (PICU).Methods:The clinical data from children with unknown clinical diagnosis and completed the whole exon sequencing who were admitted to PICU at Hunan Children's Hospital from September 20,2014 to December 30,2018 were collected .According to the results of gene detection,patients were divided into positive gene test group and regative gene test group,and the clinical characteristics between two groups were compared.Results:A total of 58 cases were included,and 119 samples were sent for the whole exone sequencing (including samples from both children and their families).Pathogenic mutations were identified in 34 cases (58.6%),with 39 pathogenic genes detected.Three pathogenic genes were detected in one patient (1.7%),two pathogenic genes were detected in each of the three patients (5.2%),and one pathogenic gene was detected in each of the 30 patients (51.7%).Among the 39 pathogenic genes,18 genes(46.2%) were autosomal dominant,15 genes(38.5%) were autosomal recessive,four genes(10.3%) were X-linked recessive,and two genes(5.1%) were copy number variants .The proportion of congenital heart disease in positive gene test group was higher than that in negative gene test group（32.4% vs.8.3%，χ 2=4.668， P=0.031）,while there was no statistical difference in other clinical features（ P>0.05）.There was no significant difference in clinical characteristics between the positive gene test group and the negative gene test group among the death children ( P>0.05）.Among 58 cases,39 cases (67.2%) resulted in death,and the positive rate of genetic disease diagnosis of the dead children was 66.7%(26/39).The mortality rate of children with positive genetic test was 76.5%(26/34),22 cases (84.7%) died directly from genetic diseases,and four cases died indirectly. Conclusion:Genetic diseases are one of the important causes of death among children in PICU.The clinical characteristics of children with genetic diseases in PICU are complex and diverse,lacking specificity.The whole exon sequencing presents a high diagnosis rate in severe and fatal PICU patients.It is recommended that children with unknown etiology in PICU should undergo genetic testing,especially those with congenital heart disease,in order to help make a clear diagnosis and guide treatment.

Objective:To summarize and analyze the results of gene detection and clinical characteristics of children with unknown etiology in pediatric intensive care unit (PICU).Methods:The clinical data from children with unknown clinical diagnosis and completed the whole exon sequencing who were admitted to PICU at Hunan Children's Hospital from September 20,2014 to December 30,2018 were collected .According to the results of gene detection,patients were divided into positive gene test group and regative gene test group,and the clinical characteristics between two groups were compared.Results:A total of 58 cases were included,and 119 samples were sent for the whole exone sequencing (including samples from both children and their families).Pathogenic mutations were identified in 34 cases (58.6%),with 39 pathogenic genes detected.Three pathogenic genes were detected in one patient (1.7%),two pathogenic genes were detected in each of the three patients (5.2%),and one pathogenic gene was detected in each of the 30 patients (51.7%).Among the 39 pathogenic genes,18 genes(46.2%) were autosomal dominant,15 genes(38.5%) were autosomal recessive,four genes(10.3%) were X-linked recessive,and two genes(5.1%) were copy number variants .The proportion of congenital heart disease in positive gene test group was higher than that in negative gene test group（32.4% vs.8.3%，χ 2=4.668， P=0.031）,while there was no statistical difference in other clinical features（ P>0.05）.There was no significant difference in clinical characteristics between the positive gene test group and the negative gene test group among the death children ( P>0.05）.Among 58 cases,39 cases (67.2%) resulted in death,and the positive rate of genetic disease diagnosis of the dead children was 66.7%(26/39).The mortality rate of children with positive genetic test was 76.5%(26/34),22 cases (84.7%) died directly from genetic diseases,and four cases died indirectly. Conclusion:Genetic diseases are one of the important causes of death among children in PICU.The clinical characteristics of children with genetic diseases in PICU are complex and diverse,lacking specificity.The whole exon sequencing presents a high diagnosis rate in severe and fatal PICU patients.It is recommended that children with unknown etiology in PICU should undergo genetic testing,especially those with congenital heart disease,in order to help make a clear diagnosis and guide treatment.

Objective:To study the clinical features of children with pertussis and the risk factors of severe pertussis.Methods:A retrospective analysis was performed based on clinical data and laboratory examination results of hospitalized children with pertussis who admitted to the intensive care unit, respiratory department, and emergency general department at Hunan Children′s Hospital from January 2019 to March 2020.According to the age, the patients were divided into age ≤3 months group( n=58)and age >3 months group( n=64). According to sputum culture, 63 cases were divided into negative sputum culture group and 59 cases were positive sputum culture group.The patients were also divided into vaccinated group( n=19)and unvaccinated group( n=103). Severe disease was seen in 28 cases, and the other 94 cases had the modest disease.The clinical characteristics between two groups were compared, and the risk factors of severe pertussis pneumonia were analyzed. Results:The hospitalization days in age ≤3 months group was higher than that in age >3 months group.It was also found that shortness of breath, apnea, cyanosis after coughing, heart rate decline were more common in age ≤3 months group than those in age >3 months group( P<0.05). The incidences of respiratory failure and heart failure in positive sputum culture group were higher than those in negative sputum culture group.Clinical characteristics such as hospitalization days, hospitalization expenses, peak white blood cell count, peak lymphocyte count, and incidence of bacterial infection were higher in severe pertussis group than those in non-severe pertussis group( P<0.05). Four patients were treated with exchange blood transfusion, and one patient died.Logistic regression analysis revealed that fever, wheezing, cyanosis after coughing and white blood cell count>20×10 9/L were risk factors for severe pertussis.White blood cell count of 20×10 9/L and lymphocyte count of 14×10 9/L had the highest sensitivity and specificity in predicting severe pertussis(0.71, 0.78; 0.54, 0.79). Conclusion:The younger the children are, the more likely they have shortness of breath, apnea, cyanosis, heart rate falls, and the longer the hospital stay.Bacterial infection will aggravate pertussis.Patients with fever, wheezing, cyanosis after coughing, and white blood cell count>20×10 9/L are more likely to develop severe pertussis.The white blood cell count >20×10 9/L and the lymphocyte count >14×10 9/L are associated with severe pertussis.

Objective:To retrospectively analyze the clinical application of extracorporeal membrane oxygenation (ECMO) in severe adenovirus pneumonia, and to evaluate the application value of ECMO in children with severe adenovirus pneumonia.Methods:Children diagnosed with severe adenovirus pneumonia and intervened with ECMO in the Hunan Children′s Hospital from January 1, 2018 to December 31, 2019 were recruited in this study for analyzing.The gender, age, clinical manifestations, mechanical ventilation duration, ECMO duration, the length of hospital stay, complications and prognosis were collected and analyzed.Results:A total of 4 children were included in the study, involving 2 cases were successfully evacuated from ECMO.Finally, 3 children died, and 1 case survived.Three death cases had a longer than 18 days of duration from the onset to the start with ECMO.Their ventilator assist time before star-ting ECMO was 3-5 days, and ECMO intervention time was longer, with the maximum of 27.5 days.The survived case had an 11-day duration from the onset to the start with ECMO, and the ventilator assisted time and ECMO intervention time were 5 days, and less than 10 days, respectively.Conclusions:ECMO treatment for children with severe adenovirus pneumonia has a low success rate, but it is still the most important way to save children.Early application of ECMO can improve the prognosis of children with severe adenovirus pneumonia.

Objective:To summary the mixed infection as well as clinical characteristics and analyze the risk factors for mixed infection of severe adenovirus pneumonia(SAP) in children.Methods:The clinical data of 114 children with SAP were retrospectively analyzed.Multivariate Logistic regression analysis was performed to assess the risk factors for mixed infection.Results:The incidence age was from 6 months to 2 years(62.5%). High fever(94.7%), cough(98.2%), dyspnea(86.8%) and lethargy(95.6%) were the main symptoms.Laboratory examination showed that children with SAP were prone to increased white blood cell count, C-reactive protein, procalcitonin, aspartate aminotransferase, alanine aminotransferase and CK-MB, as well as decreased proportion of CD3 + , CD4 + , CD8 + , CD4 + /CD8 + and NK cells.The main complications intrapulmonary organ were respiratory failure(80.7%). The main complications extrapulmonary organ were circulatory complications (55.3%). SAP was easily combined with other pathogenic infections.Streptococcus pneumoniae(22.9%)was the most common bacterial pathogen.Respiratory syncytial virus(10.0%)were the most common virus, in addition, mycoplasma pneumoniae(17.1%) was also common.Multivariable Logistic regression analysis showed that the decreasing ratio of CD4 + /CD8 + and NK cells, congenital heart disease and congenital airway dysplasia were the independent risk factors for mixed infection of SAP in children( P<0.05). Conclusion:The SAP patients could easily suffer from mixed infection and high fatality rate.Immune dysregulation is the important risk factors for mixed infection of SAP in children.So immunoregulatory treatment is very important.

Objective:To discuss the role of continuous blood purification (CBP) therapy in children with severe adenovirus pneumonia.Methods:A total of 114 children with severe adenovirus pneumonia admitted to the Department of PICU at Children′s Hospital of Hunan Province from June 2018 to July 2019 were selected as the research objects.According to whether treated with CBP, they were divided into CBP group and control group.The following indicators during the process of treatment were compared between two groups, including respiratory mechanics indicators[respiratory index(PaO 2/FiO 2), dynamic lung compliance(Cdyn)]; hemodynamic indicators(heart rate and mean arterial pressure); changes in levels of inflammatory factors interleukin(IL)-6, IL-10, tumor necrosis factor(TNF)-α and the prognosis 28 days after admission. Results:The respiratory mechanics index, serum IL-6 and TNF-α levels of two groups after treatment were significantly lower than those before treatment, and the serum IL-10 level was significantly higher than that of this group before treatment.There were statistical differences in the CBP group before and after treatment, while there was no statistical difference in control group.In the CBP group, the serum IL-6 and TNF-α levels after treatment were significantly lower than those of the control group( P<0.05), and the serum IL-10 level was significantly higher than that of the control group( P<0.05). The 28-day mortality rate of patients in CBP group was 8.6%(3/35), which was significantly lower than 13.9%(11/79) of control group ( P<0.05). Conclusion:CBP could improve the main respiratory mechanical indexes of adenovirus pneumonia and decrease the level of inflammatory cytokines.

Objective To compare the clinical efficacy of different blood purification methods in children with acute liver failure,and to explore the clinical application mode,time and prognosis of blood pur-ification in children with acute liver failure. Methods The clinical data of 85 children with acute liver failure admitted to PICU of Hunan Children′s Hospital from January 2010 to October 2016 were retrospectively ana-lyzed. Sixteen patients were treated with general integrated medical treatment(conservative group). Twenty-seven patients were treated with continuous venovenous hemodiafiltration ( CVVHDF) model non-biological artificial liver on the basis of general integrated medical treatment(CBP group). Sixteen cases were treated with plasma exchange ( PE group). Twenty-six cases were treated with plasma exchange combined with CVVHDF mode (combination group). The main biochemical indexes,coagulation function,model for end-stage liver disease(MELD) score and delta MELD before and after treatment among groups were compared. Results Compared with those before treatment,the improvement of liver function and prognosis in the con- servative was not significant after treatment. There were significant differences in the improvement of liver function and prognosis among the other three groups treated with non-biological artificial liver. Comparing the biochemical indexes and prognosis of three groups of children treated with different modes of non-biological artificial liver,there was no significant difference in the total effective rate between PE group and CBP group [56. 3% (9/16) vs 55. 6% (15/27),P>0. 05]. The total effective rate of combined group[84. 6% (22/26)] was significantly higher than those of PE group and CBP group. There was no significant difference in the improvement of liver function between PE group and CBP group (all P>0. 05),but the indexes of liver function in combined group were significantly lower than those in PE group and CBP group ( P<0. 05). It significantly increased prothrombin activity,albumin and alpha-fetoprotein levels(all P<0. 05). At the same time,procalcitonin, sequential organ failure assessment scores, pediatric end-stage liver disease scores and MELD scores in the death group were significantly higher than those in the survival group,and there were significant differences between the two groups. However,the effect of non-biological artificial liver was not good in the subgroups of MELD<25 and MELD>40. Conclusion PE and CBP have a good effect on chil-dren with acute liver failure,and if combined with the two methods can improve the therapeutic effect. At the same time,MELD score should be monitored in children with acute liver failure,and non-biological artificial liver therapy should not be recommended for children with MELD<25 and MELD>40.

Objective To explore the application value of the FilmArray detection system in the diagnosis and treatment of severe pneumonia in children,and to understand the pathogenic characteristics of severe pneumonia in children.Methods A tolal of 158 nasopharyngeal swab specimens were collected from children with severe pneumonia in Hunan Children's Hospital from May 2017 to March 2018.FilmArray were used to detect respiratory pathogen.Blood routine,C-reactive protein (CRP),procalcitonin (PCT) and seven kinds of respiratory virus antigen were also performed on all the samples.The pathogenic characteristics of 158 cases of severe pneumonia were analyzed,and the positive rate of seven kinds of respiratory virus antigen test method and FilmArray were statistically analyzed.Results Among 158 patients with severe pneumonia,114(72.15％) were positive and 91 (57.59％) single pathogen infection were detected by FilmArray,with the highest detection rate of rhinoviruses/enteroviruses (16.46％).23(14.56％) mixed infection were detected by FilmArray,respiratory syncytial virus combined with adenovirus infection had the highest positive rate (2.53％).The detection of respiratory pathogens in different age groups was analyzed.The highest positivity rates of children aged ＜ 1 years were human rhinovirus/enterovirus and respiratory syncytial virus (25％),＞ 1-3 years was human rhinovirus/enterovirus (25％),3-5 years were influenza virus A and adenovirus (27.27％),＞ 5 years was human rhinovirus/enterovirus (26.08％).Among 158 patients,53(33.54％) had bacterial infection,and the most common bacterial infection was Streptococcus pneumoniae (7.59％).In seven respiratory virus antigen test negetive children,PCT in Film Array negative group was higher than that in Film Array positive group (P =0.03).The positive rate of FilmArray was higher than that of the seven respiratory virus antigen test method (72.15％ vs 19.62％,P ＜0.01).The level of white blood cell and cough days in pertussis group were higher than that in non-pertussis group,which was significantly different (P ＜ 0.01).The PCT level in non-pertussis group was higher than that in pertussis group,with significant difference (P ＜ 0.01).Conclusions FilmArray detection can detect 20 kinds of respiratory tract pathogens rapidly and accurately.The positive rate of detection is high,and the diagnosis rate of virus is improved.The combination of infection indicators and sputum culture results by clinicians can better guide the clinical diagnosis and treatment.