有温度 有深度 有广度
Temperature has depth and breadth
Just waiting for you to pay attention.
来源：儿科助手 | 图：Sarah
Source: pediatric | assistant: Sarah
编辑：莹莹 | ID：gjekzjpd
Editor: Yingying | ID:gjekzjpd
(please indicate the above information)
Virus induced acute respiratory distress syndrome
急性呼吸窘迫综合征(acuterespiratory distress syndrome，ARDS)是1967年由Ashbough发现的一种急性进行性低氧性呼吸衰竭，其特征为肺泡毛细血管屏障广泛破坏、蛋白渗出性肺水肿、进行性呼吸困难和顽固性低氧血症。ARDS一直是重症医学工作者关注的焦点。ARDS病死率的高低在一定程度上折射出该地区ICU救治水平的高低。
Acute respiratory distress syndrome (acuterespiratory distress, syndrome, ARDS) is a kind of acute hypoxic respiratory failure was found in 1967 by Ashbough, characterized by extensive destruction of alveolar capillary barrier, protein exudative pulmonary edema, dyspnea and intractable hypoxemia. ARDS has been the focus of attention of critical care workers. The mortality rate of ARDS reflects the level of ICU treatment in a certain extent.
Since 2003, severe acute respiratory syndrome (SARS) outbreak in China has experienced the pediatric community local epidemic or large-scale avian flu, foot and mouth disease, influenza, measles, adenovirus pneumonia and other viral diseases, the most serious form is ARDS. Virus induced ARDS has become one of the most important diseases in pediatric intensive care physicians.
Etiology and common clinical manifestations
1 the seasonal viral infection is that the virus pneumonia accounts for the community acquired pneumonia of 10% ~ 40%. Foreign reports of influenza virus and rhinovirus are the most common, other respiratory viruses such as hepatitis C virus, adenovirus, respiratory syncytial virus and coronavirus. These viruses can cause severe viral pneumonia, leading to ARDS. In our country, in recent years, ARDS has been caused by seasonal viral pneumonia, including adenovirus, seasonal influenza virus and. There is no clinical epidemiological data on the incidence of ARDS caused by these viral pneumonia. Because a considerable part of the pneumonia in the clinic, observation room and the general treatment of the disease, the objective of making its clinical epidemiological study is impossible.
Adenovirus pneumonia is a common disease which can cause ARDS in China in recent years. It occurred in spring and summer, which accounted for 8% to 10% of all viral pneumonia. The common symptoms were fever, cough, poor complexion and progressive dyspnea. Some patients with heart failure, shock, chest X-ray showed progressive exacerbation of pulmonary infiltrates. The treatment is mainly cidofovir resistance to infection, provide respiratory support.
The 2 pandemic virus infection in recent ten years, the epidemic virus infection can cause respiratory failure and ARDS are 4 kinds of diseases in Chinese children: caused by SARS coronavirus, caused by avian influenza pneumonia caused by influenza H5N1, H1N1 virus and measles.
(1) SARSSARS was first discovered in Guangdong, China in 2002 and has spread to more than 26 countries on 5 continents, with a total of more than 8 thousand people suffering from the disease and the death of 774 people. The onset of symptoms were fever, chills, muscle pain, cough, shortness of breath, breathing faster. Chest X-ray showed that nearly 100% of patients with pulmonary infiltrates two. During the epidemic period, only 1 \/ 3 of the patients were normal, and severe complications were found in both the 2 and 3 of the patients. The most severe cases were ARDS. The disease mainly affects adults, pediatric patients are relatively small. There is no specific treatment for this disease.
(2) avian influenza caused by H5N1, first discovered in 1998, can lead to severe pneumonia, often rapid progress of ARDS, the mortality rate as high as 60%. The most common symptoms and nonspecific, fever, shortness of breath, cough, vomiting, diarrhea, headache, etc.. The majority of cases rapidly progressed to respiratory failure and ARDS. Autopsy revealed diffuse alveolar damage, hyaline membrane formation, lobular interstitial plasma cell infiltration, bronchiolitis with localized squamous metaplasia, pulmonary congestion, pulmonary hemorrhage, etc.. In the treatment of respiratory support, given oseltamivir and Pana Mi Vee therapy. The disease is mainly seen in adults, but children also reported.
(3) influenza A H1N1 influenza caused by H1N1, 2009 the first place in the American state of California, triggered a global epidemic, the incidence of children in our country is very high, almost every PICU in many children were admitted during the epidemic period. The onset symptoms of respiratory tract symptoms, progression of viral pneumonia, mostly benign, severe progression of ARDS. In 2009, severe influenza A was found in infants less than 1 years old, pregnant women, chronic cardiovascular disease, chronic lung disease, pathological obesity, chronic kidney disease, hemoglobin disease, sclerosis, etc.. But in the hospital or death of the children, half of the children with no such complications. Viral pneumonia with hypoxemia, ARDS, shock, renal failure and necrotizing encephalopathy are the common causes of PICU in children. The autopsy found from the upper airway to the alveoli were viral colonization, all specimens showed diffuse alveolar damage, visible alveolar hemorrhage and alveolar edema, perivascular inflammation, micro thrombosis and pulmonary embolism (or). Alveolar cells, such as type I and type II alveolar epithelial cells, are the most important alveolar cells. Of particular note is that nearly 25% of patients with bacterial infection. The disease in the treatment of respiratory support, oseltamivir is the preferred antiviral drugs, drug resistant patients with zanamivir or Pana Mi Vee.
(4) measles virus recently popular in many areas of our country, not found in the vaccination of children and infants less than 8 months. Many children with measles pneumonia complicated with ARDS, the main symptoms of high fever, cough, pulmonary infiltrates, hypoxemia. Treatment mainly to maintain a negative balance of the liquid, the combination of infection in a timely manner to antibiotic treatment, high-dose vitamin A therapy, respiratory support, etc.. Two, diagnosis
ARDS diagnosis is currently based on two criteria, namely the 2012 ARDS Berlin standard and the United States children’s acute lung injury in collaboration with the children’s ARDS consensus in 2015. There is no big difference between the two standards, the former easy to grasp, more intuitive; the latter closer to the actual 49L, but some difficult to grasp the standard. In any case, the two criteria can be diagnosed as ARDS. Diagnostic criteria see Table 1 and table 2.
Three, clinical features
After nearly ten years of clinical treatment, combined with the relevant literature, we summarize the clinical features of viral ARDS are as follows.
1 children with sudden onset from pneumonia to ARDS into a short time, some children in the 1 ~ 2D, in 3 ~ 5D, with little more than 1 weeks before the occurrence of ARDS, especially in the relationship between the onset of ARDS avian influenza pneumonia most quickly, influenza associated pneumonia ARDS onset of measles pneumonia is relatively slow.
2 hypoxemia was significantly more rapid progression of such children with severe ARDS, and there was a progressive trend. The blood PaO2 is very low, often as low as 20mmHg ~ 40mmHg, were easily misdiagnosed as venous blood gas, this time as long as check with cyanosis and pulse oxygen saturation can be determined. On the other hand, if the blood in the clinical encounter in poor, fast development, and should be suspected of severe viral pneumonia, should pay attention to careful history, history and local poultry epidemiological contact history, and a variety of routine virological testing. It is worth noting that, in asking the history of exposure to poultry, should be careful to ask their neighbors, the village or community, have no history of contact with live poultry, there is no abnormal dead bird birds including death phenomenon and has no substantive contact etc..
3 poor lung compliance in children with viral pneumonia most lung compliance is poor, but some patients had refractory hypoxemia but pulmonary compliance is still good, especially in children with influenza and adenovirus pneumonia is prominent. These children with the imaging revealed pulmonary lesions is very heavy, but the pressure parameter is not high, the tidal volume is very high, far more than the tidal volume lung protective ventilation requirements, strain (strain) increased significantly, can easily lead to ventilator induced lung injury, the increase in the presence of ARDS. This is more strongly associated with this type of nerve impulses, the need for strong sedation and muscle relaxants, or can not be lung protective ventilation strategy.
4 another important clinical feature of spontaneous pneumothorax viral pneumonia is spontaneous pneumothorax, which may be related to the presence of necrotizing bronchiolitis in children with viral pneumonia complicated with ARDS. The children did not receive any positive pressure ventilation under pneumothorax, mediastinal emphysema, brought great difficulties to the mechanical ventilation in the treatment of ARDS. On the one hand, this kind of children will appear spontaneous pneumothorax, on the other hand, mechanical ventilation is more prone to pneumothorax than other children. To explore the mechanism, we can see from the pathological anatomy, some viral pneumonia in addition to the lung parenchyma lesions, still prone to necrotizing bronchiolitis. This will inevitably lead to gas leakage, along the bronchial sheath into the mediastinum caused by mediastinal emphysema and pneumothorax.
ARDS lung real change CT image
Viral pneumonia caused by ARDS is the biggest challenge in PICU, its treatment is extremely difficult, the need to focus on the strength of the whole team, the application of all possible technical means, to the best possible treatment of children. This article is only for special treatment means.
1 lung protective mechanical ventilation strategy of lung protective ventilation strategy is the essence of low tidal volume, high pressure PEEP and restricted platform. Pa02 will be maintained at 55 ~ 80mmHg, PaC02 maintained at 35 ~ 45mmHg, Sa02 maintained at between 88% ~ 92%.
(1) the low tidal volume and low tidal volume at present has become the industry consensus, but whether it can be used every day low tidal volume is an important problem to. ARDS treatment of PICU in China by clinicians pressure control ventilation mode, its important characteristics is the tidal volume is not stable, if not daily close monitoring of tidal volume, there will be two results: one is the children with lung compliance is getting worse, the tidal volume is far less than 6ml \/ kg, if the PaC02 is normal, oxygenation range in May, it is the ideal state, is a. More children is a serious shortage of ventilation, high PaC02, oxygenation affected, with disease progression, if not adjusted high pressure tidal volume remained at 6ml \/ kg, will produce a vicious outcome; two patients compliance improved, tidal volume is far greater than 6ml \/ kg, this will inevitably lead to the strain ARDS of the lung (strain) increased significantly, leading to ventilator induced lung injury.
Here there is a misunderstanding, some doctors think lung compliance improved, tidal volume rising point Never mind theory, seems to be correct, but if the stress (stress) strain (strain) theory to evaluate with ARDS tidal volume, especially viral pneumonia caused by ARDS tidal volume, large tidal volume should be far less than many children 6ml \/ kg, the clinical application of comprehensive ventilation function is set to 6ml \/ kg before, so when the lung compliance improved will still set tidal volume is 6ml \/ kg should be exactly in line with the ARDS pulmonary physiological needs. The United States this year, a multicenter study also confirmed this point of view, they discovered that the initial parameters, each tidal volume increased 1ml \/ kg, the mortality rate of ARDS increased by 23%; after the initial parameter setting, follow-up parameters, each increase in tidal volume of 1ml \/ kg, the mortality rate increased by 15%. The first 8D application after continuous ventilator tidal volume of 8ml \/ kg, compared with the continuous application of 8D \/ kg tidal volume 6ml, initial 8D mortality rates were 7.2% and 2.7%.
(2) compared with the high PEEP clinicians, when children with ARDS were not well oxygenated, they first adjusted the oxygen concentration, rather than the PEEP. It is the best choice to adjust the PEEP to the ideal state, because the maintenance of alveolar opening is one of the most important conditions for children to get better oxygenation. We advocate the United States should be provided by the ARDS collaboration Fi02 \/ PEEP bundle method to set PEEP, PEEP maintained at 8 ~ 16cmH2O is the most common choice, not too low.
2 prone ventilation viral pneumonia caused by ARDS, once with severe ARDS, suggestions for prone position ventilation, if effective, should adhere to the above application 16h every day. If it is not valid, it can be tried again after 24h. Prone ventilation is another major progress after ARDS treatment of low tidal volume, and can decrease the mortality rate of ARDS, but should pay close attention to avoid complications, hemodynamic instability and tube off accident. At the same time, if there is hemodynamic instability, cervical spinal cord injury and other circumstances should not use this method. Specific visible reference.
3 conservative fluid replacement ARDS is essentially a pulmonary edema caused by damage to the alveolar capillary barrier. Because of the alveolar capillary barrier damage, if we do not pay attention to the clinical fluid balance, the formation of liquid intake is greater than the amount of the daily excess the amount of fluid into the alveolar pressure gradient along the inevitable, aggravate the existing pulmonary edema. Previous observational studies have shown that the cumulative fluid volume of 3D in patients with ARDS is greater than that in the patients, and is associated with a better prognosis. An observational study has shown that spontaneous diuresis may occur in patients with ARDS, who have a good prognosis, to alleviate pulmonary edema (3D). The implication of this study is that we should artificially create a negative balance of fluid to relieve pulmonary edema in children with ARDS. Therefore, in clinical practice, should assess the daily intake, ensure that the volume is greater than or equal to the amount, in the maintenance of children with mild dehydration state.
4 analgesia sedation muscle relaxation almost all of the children with mechanical ventilation are required to give analgesia sedation, the Ramsay score in 2 ~ 5 minutes or so, this has become a consensus. This may not be enough for children with viral ARDS. In front of the clinical features we mentioned, some children with viral ARDS, the lung lesions in extremely poor oxygen saturation, but its adaptability is very good, our tidal volume target set at 6ml \/ kg, which cannot be achieved, the tidal volume in 10ml \/ kg or more often, it is bound to cause ventilator induced lung injury. The children should be given the depth of sedation and analgesia and muscle relaxation were destroyed, spontaneous breathing, to ensure the implementation of the scheme of low tidal volume. It is worth noting that the reasonable time of muscle relaxant is not more than 48h, the combination of muscle relaxant and hormone.
5 extracorporeal membrane oxygenation (ARDS) in patients with severe influenza A (ARDS) was associated with a significant reduction in mortality. Extracorporeal membrane oxygenation is the ultimate means of treatment of viral ARDS, but because of its high investment, suitable for the small number of cases, at present in our country is not much, I believe that with the country’s economic strength is increasing, extracorporeal membrane oxygenation will gradually gain popularity.
6 symptomatic treatment of spontaneous pneumothorax and mechanical ventilation in children after the emergence of pressure pneumothorax is the most common complications of viral ARDS, but also a little can be fatal complications. Children with viral pneumonia caused by ARDS should be closely monitored with spontaneous pneumomediastinum and pneumothorax, if found on children with sudden exacerbation should first exclude pneumothorax, if pneumothorax, should reduce ventilator parameters first, timely closed thoracic drainage, the children most breathing machine parameters is higher, can not observe, timely closed thoracic drainage is the most important method. Closed thoracic drainage after the success of the parameter can be transferred back to the original value, as long as the attention of closed thoracic drainage, ventilator parameters can be adjusted freely almost completely. Some children only mediastinal emphysema and subcutaneous emphysema, these children are difficult to dispose of. The conditions of the hospital as the suprasternal fossa or epigastric flap drainage, no condition available injection needle into the subcutaneous bleeding, the ventilator parameters can be arranged at relatively low levels, if later pneumothorax can be closed thoracic drainage, mediastinal pneumatosis will be discharged, the breathing machine parameters can be adjusted freely.
Sources of data:
Yu Wenliang, Ge Xu Hua. Acute respiratory distress syndrome caused by virus. Chinese pediatric emergency medicine, 2015, 22 (): 818-821825.
To participate in the International Academy of Pediatrics, please add the housekeeper
Sweep the concern of the public, WeChat