Severe hand, foot and mouth disease (HFMD) may lead to the high mortality due to brainstem encephalitis, encephalomyelitis, pulmonary edema/pulmonary hemorrhage and cardiopulmonary failure in children. Some patients are complicated with severe gastrointestinal dysfunction, manifested as abdominal distension, intestinal paralysis, bleedy stool, haematemesis. "Catecholamine storm" and viral systemic inflammatory response syndrome may be the main mechanisms for gastrointestinal dysfunction. It is important to focus on the monitoring of gastrointestinal dysfunction of severe HFMD. Preventing and avoiding iatrogenic damage of gastrointestinal dysfunction are main treatment strategies.

Adenovirus,respiratory syncytial virus,influenza virus type A and B,cytomegalovirus and EB virus are the mainly etiology of severe pneumonia in children.New type of virus,such as influenza-H1N1 virus,avian influenza virus(H5N1 or H7N9) can also be epidemic in pediatric population.Ribavirin is effective drugs in the treatment of respiratory syncytial virus and adenovirus pneumonia.Acyclovir or ganciclovir is used for EB virus or immune deficiency and irnmunosuppressive patients with CMV pneumonia.Current opinin strongly recommend treatment with oral oseltamivir as soon as possible in influenza and seasonal influenza.Oseltamivir reduces the severity,duration of the symptoms of influenza,and reduces the frequency of secondary illnesses and exacerbation of underlying conditions.Zanamivir and peramivir may be effective in patients infected with influenza virus,including oseltamivir-resistant virus.Some Chinese medicine such as maxingshigan-yinqiaosan can obtain similar effect of oseltamivir in treatment of influenza virus infection.

Early goal-directed therapy ( EGDT ) emerged as a novel approach for reducing septic shock mortality and the EGDT protocol requires invasive patient monitoring to guide resuscitation with intra-venous fluids.EGDT was incorporated into guidelines published by the international Surviving Sepsis Cam-paign,but remains controversial.Recently,large randomized trials showed that EGDT did not significantly de-crease mortality in patients with septic shock compared with usual care.Fliud resuscitation and monitoring is the most important in septic shock.Therefore the EGDT is still valuable in present stage.Further,development practical methods for accurately assessing optimal fluid administration is needed.

The improvement of oxygenation basis on prone positioning in acute respiratory distress syndrome (ARDS) includes increased end-expiratory lung volume,improved ventilation-perfusion (V/Q) matching,and drainage of secretions.Randomized controlled trials report that prone position ventilation in patients with ARDS tends to reduce mortality rates,especially when used in conjunction with lung protective strategies and greater prone positioning durations.At present,the available data suggest that early prone positioning may provide benefit to ARDS with severe hypoxemia.keeping in mind that a risk of positioning-related complications will have to be taken into account when weighing the risk to benefit for patient with ARDS.There is still limited information available of prone position ventilation application in pediatric ARDS.

The invasive fungal infection( IFI)in PICU has increased steadily during the recent years. Candida spp. and Aspergillus spp. are the most frequently fungi in children. Candida spp. is the leading cause and invasive Candida spp. Infection( ICI)is approximately five times frequency than invasive Aspergillus spp. Infection( IAI). The attributable mortality of ICI or IAI remains different mainly because of different basic diseases. Stay in the PICU presents risk factors for ICI especialy using central venous catheter,parenteral nutrition,dialysis,mechanical ventilation,and prolonged antibiotics application. The patients with hematologic malignancies and leukemia are higher prevalence of IAI who were treated with cytotoxic or immunosuppres-sive drugs,broad-spectrum antibiotics and stem cell transplantation. The most important challenge remains to propose targeted prophylaxis and to identify IFI earily in high risk critically ill children in PICU.

MicroRNAs are small,single-stranded and non-coding RNAs.MicroRNAs modulates gene expression by binding themselves to complementary sites of target genes.It had been discovered that micmRNAs modulate sepsis in multiple levels.Through targeting Ca2+/calmodulin-dependent protein kinase Ⅱ,miR-152 and miR-148 impair innate response and antigen presentation,and also suppress proliferation of antigen specific CD4 + T cells; miR-29 family regulate cellular immunity through setting the threshold in thymic involution; MicroRNA-17-92 plays a causative role in B cell lineage; miR-146 and miR-155 down-regulate proinflammatory cytokines through suppressing components of pattern recognition receptors,while miR-132 through acetylcholinesterase degeneration.miR-124 degenerates mRNA of glucocorticoid receptorαand results in glucocorticoid resistant in treatment of sepsis.Immune regulation of microRNAs in sepsis is briefly described in this paper.

Adrenal crisis is a life-threatening emergency caused by the destruction or altered function of the adrenal gland with a primary deficit in cortisol secretion(primary adrenal insufficiency)or by hypotha-lamic-pituitary pathologies determining a deficit of adrenocorticotropic hormone(secondary adrenal insuffi-ciency).Infection and abrupt end glucocorticoid treatment are the major precipitating causes of adrenal crisis. Patients with adrenal crisis typically present with hypovolemic shock or hypotension,nausea,vomiting,and fe-ver responding well to parenteral hydrocortisone administration.The main laboratory findings include lower serum cortisol concentrations,hyponatremia,hypoglycaemia and/or hyperkalemia.Delay diagnosis of adrenal insufficiency leads to adrenal crisis which is potentially lethal complication.Empirical glucocorticoid replace-ment should be initiated as soon as the suspicious of adrenal crisis,or sooner if the patient presents in adrenal crisis in critically ill children.

Biomarkers are objective tools with an important role for diagnosis in patients with acute myocarditis.Traditional biomarkers,such as aspartate aminotransferase,creatine kinase and myoglobin seem to have low sensitivity.Creatine kinase-MB′s major limitation is short in half-life,which makes monitoring more difficult.To date,cardiac troponins are closest to optimal biomarker with high sensitivity and specificity in the early diagnosis of acute myocarditis.Novel biomarkers,including stromal cell-derived factor 1 ,heart-type fatty acid binding protein and MicroRNA have the potential to be valuable biomarkers for early diagno-sis.Combining biomarkers and clinical features have appeared to improve diagnostic accuracy than either one alone.

The presence and persistence of systemic and lung inflammation in children with acute respiratory distress syndrome (ARDS) is the basis for the use of corticosteroids as a therapeutic agent.The trial of ARDS treated with high-dose short-course corticosteroids showed no benefit,even increase motality.At present,the results of randomized controlled trial and meta-analysis suggested that low-dose and replacement-dose methylprednisolone [1-2 mg/(kg· d)] or equivalent types of corticosteroids may decrease the fatality rate,reduce staying days in ICU and the duration of mechanical ventilation.Use of corticosteroids for ARDS in children is still lack of multicenter randomized controlled trial.

Moraxella Catarrhalis emerged as the third cause of respiratory tract infection in children.Over 90% of the Moraxella Catarrhalis strains isolated currently produced by β-lactamases positive.Moraxella Catarrhalis resist to Ampicillin because of the β-lactamases,such as the BRO-1 type,BRO-2 type and BRO-3 type.The BRO genes appeared to be located on the chromosome and be coded.Twenty-one new mutations were found in the putative promoter region of the BRO genes.