INTRODUCTION

The new human H7N9 viruses are the product of reassortment that are of avian origin, which can cause severe illness, including pneumonia and acute respiratory distress syndrome (ARDS), with high rates of ICU admission and death. Since the identification of H7N9 on 30 March 2013,[1] a second wave of H7N9 virus infection has occurred in 2014 with the number of new cases reported thus far exceeding twice the number from the previous year.[2]

The disease progresses rapidly in severe cases and may develop into ARDS associated with both acute pneumonia and acute interstitial inflammation.[3,4] It is reported that 97.3% patients with confirmed H7N9 virus infection had findings that were consistent with pneumonia and 76.6% patients were admitted to an intensive care unit (ICU). Moderate-to-severe ARDS was the most common complication and 58.6% patients needed invasive mechanical ventilation(MV). [5] The risks of admission to an ICU, mechanical ventilation, and fatality were high.[6]

The situation of the increasing number of new cases and the high rate of death associated with these infections has raised global public health concerns.[7] The data on the clinical characteristics and laboratory abnormalities of the illnesses and risk factors for severe illness among patients who were hospitalized for the treatment of H7N9 virus infection were also provided.[5,6] However, data on the MV characteristics for the cases with ARDS were still lacking. In this report, we describe MV characteristics and radiologic features with a lung-protective strategy,recruitment maneuvers, prone positioning.

METHO DS

This study was approved by the Regional Ethics Committee of our hospital (No: 2016KY155). The requirement for written informed consent from the patients was waived by the institutional review board because the design of this study was a retrospective study.

Patients

Eight adult Chinese patients, who were admitted to the ICU with severe bilateral pneumonia and ARDS,were confirmed to be infected with H7N9 avian flu by Shanghai Public Health Clinical Center, the Shanghai Centers for Disease Control and Prevention (CDC)and the Chinese National Influenza Center (CNIC) in 2014 (all of them were admitted in first quarter). All the patients required invasive mechanical ventilation in the ICU and underwent at least one chest computed tomography (CT) scan in the hospital. All patients were defined as severe ARDS according to the Berlin Definition.[8] The general severity of disease was assigned an APACHE II score. The extent of multiple organ failure was evaluated by means of the SOFA score. These scores were calculated on the days of ICU admission and days 3,7, and 14 after ICU admission.

Ventilator management

The ventilatory strategy of the low tidal volume by limiting tidal volume (VT) to 4-6 mL/kg and plateau pressure(PPlat) to 30 cmH2O and open-lung approach was chosen using conventional modes of mechanical ventilation.

Recruitment maneuvers (RM) were used to make improvements in oxygenation in the patients with refractory hypoxemia as a rescue strategy. Optimal PEEP was considered if the step preceding the drop of oxygen saturation to below 90%.[9] We use bedside ultrasound and pressure volume curve (P-V curve) to identify which collapsed lung units have a high potential for reopening.Prone positioning was performed following the protocol[10] to improve oxygenation on t he patients who had poor response to the RM without contraindications.

Pressure-volume curves and measurement of PEEP-induced RM

P-V curves were measured using a ventilator equipped with specific software. Decrease in endexpiratory lung volume (EELV) was defined as the difference in lung volume before and after a PEEP release maneuver. In patients with focal loss of aeration,PEEP-induced lung recruitment was quantified as previously described.[11] In patients with diffuse loss of aeration, PEEP-induced lung recruitment was defined asEELV. We also used lung ultrasound (LUS) to provide a bedside estimate of potentially recruitable lung.[11,12]

CT examination

All patients underwent first CT scan of the chest once within 2 days after the admission to the ICU. Ventilator management at the time of the CT examination was designed to limit plateau pressure at 30 cmH2O or less,with positive end-expiratory pressure of 5-8 cmH2O.None of the patients experienced a deterioration in condition as a result of undergoing the CT examination.We used the first CT scan to score the CT findings. The CT findings were graded on a scale of 1-6 on the basis of the classification system previously described.[13-15]

RESULTS

Clinical characteristics

Over a 3-month period, our medical ICU managed 8 patients with severe H7N9 infection complicated by ARDS. The clinical characteristics of the patients are presented in Tables 1 and 2. The mean age was 57.38±16.75 years, and men comprised 62.5% of all the patients. The baseline severity of illness assessed by APACHE II and SOFA score was 11.77±6.32 and 7.71±3.12, respectively. Four patients had one or more comorbidities, the most common of which was hypertension (n=3). Interestedly, all of patients did not have underlying pulmonary disease. All patients received oral oseltamivir (150 mg twice daily) for 7 days following the guideline[16] and parenteral antibiotics. Five patients were proven to have secondary infections. Three patients already required intubation before ICU admission.The other five patients were intubated in 24 hours after the admission of ICU. The mean duration of MV was 14.63±6.14 days. Two patients without contraindications underwent prone positioning to improve oxygenation which had poor response to the RM. Three patients died within the first 28 days after ICU admission. One of them died from multiple organ dysfunction syndrome(MODS) after refractory hypoxemia, one patient died of secondary infection (Candida) and the other patient died of pneumothorax after long-term MV.

CT findings

20 Zhang Z, Zhang J, Huang K, Li KS, Yuen KY, Guan Y, et al.Systemic infection of avian in fl uenza A virus H5N1 subtype in humans. Hum Pathol. 2009;40(5):735-9.

Table 1. Cli nical characteristics of 8 patients infected wi th H7N9 virus

LMW heparins: low molecular weight heparins.

?

Table 2. CT findings in 8 patients infected with H7N9 virus, n (%)

?

Figure 1. Finding in a 35-year-old man who survived (patient 2). A:first CT; B: six months after discharge from hospital.

Figure 2. Finding in a 54-year-old man who did not survive (patient 3). CT shows diffuse interstitial exudation and areas of ground glass attenuation associated with traction bronchiolectasis (arrows),bronchiectasisand architectural distortion. This patient died of pneumothorax after long-term MV.

Evaluation of RM

We used the ultrasound reaeration score (Figure 3),the change of P-V curve and PaO 2/FiO2 ratio to evaluate the effect of RM. The result is summarized in Table 4.There were 4 patients who did not need RM with set PEEP limitedly (≤20 cmH2O, PaO2/FIO2 ≥150 mmHg).RM was performed on the other 4 patients with lifethreatening hypoxemia in the early stage of ARDS.We did not perform RM again on patient 4 who had poor response to the RM and the patient 1 who without hemodynamic stability.

根据国内企业的财务软件现实使用来看，软件内部的每一个核算子系统之间互相分割，财务数据、信息传输的实时性、一致性、系统性较差，每一个子系统模块之间相互独立，缺乏有效的联系。各个版本的财务软件大多不能有效地结合使用，从而使得财务电算化的系统独立于子系统，而数据交换、信息共享、控制管理等也无法有效开展。

Prone positioning

供给情况：氮肥方面，尿素企业整体开工率有所下滑，局部地区企业因大气污染治理生产受限；气头企业因天然气价格上涨，开工率下滑显著，西北及内蒙古气头企业多降低负荷生产。磷肥方面，二铵企业停产复产交替，整体开工率回升至60%。钾肥方面，盐湖基准产品60%粉晶到站价2300-2350元/吨，与前周持平，有涨价计划；港口钾方面，大合同尚未到货，供给紧俏；边贸钾少量到货，价格小幅松动。复合肥方面，企业整体开工率较前周小幅下滑，新单跟进乏力，企业停产检修增多。

TPP试图通过减免关税促进贸易发展来深化签署国之间的经济联系，但是美国国内反对者担心该协定将会影响国内就业，特别是会导致家具业工人失去工作。鉴于此，美国贸易委员会专门举办了听证会来消除公众的这种担忧。中国虽然不是TPP的成员国，但是马来西亚和越南都是该协定的成员国，并且这两个国家都是美国主要的家具进口来源国。因此，TPP协定的生效必然会影响中国家具对美国的出口，同时也会对美国国内正在缓慢复苏的家具制造业带来压力。另外，TPP有意在签署国实施劳工改革并且建立更高的劳工标准，但是家具业人士并不相信这会影响(至少在短期内影响)生产国和消费国之间的劳动力成本差异。

Table 3. Extent of each CT finding in 8 patients infected with H7N9 virus

Parameters　1 　2 　3 　4 　5 　6 　7 　8 　Mean±SD The Murray's score at the first CT examination 3.67　 3.25　 2.75　 2.75　 3.25　 3.33　 2.5　 2.5　 2.97±1.03 The CT score at the first CT examination 260.9　240.4　294.7　207.6　240.4　196.3　255.7　285.4　247.68±34.28 Spared area (%)　 26.0　 17.0　 33.5　 55.3　 35.2　 60.0　 24.5　 25.6　 34.64±15.32 Ground-glass attenuation (%)　 22.4　 32.6　 6.5　 10.2　 10.5　 10.5　 18.6　 24　 16.91±8.98 Air-space consolidation (%)　 31.3　 46.9　 13.5　 17.2　 42.4　 16.1　 40　 6.4　 26.73±15.31 Ground-glass attenuation +traction bronchiolectasis or bronchiectasis (%)5.3　 0　 24.8　 6.2　 2.5　 0　 10.5　 30.4　 9.96±11.52 Air-space consolidation +traction bronchiolectasis or bronchiectasis (%)15.0　 3.5　 21.7　 11.1　 9.4　 13.4　 6.4　 10.6　 11.39±5.54 Honeycombing (%)　 0　 0　 0　 0　 0　 0　 0　 3　 0.375±1.06

Figure 3. Illustration of PEEP induced lung recruitment detected by bedside ultrasound in patient 2. A: The images of upper part of anterior region of left chest wall before and after RM. Left: Transversal view of a lung region with alveolar syndrome. Multiple well-defined B lines(B1 lines) arising from the pleural line are present. Right: After RM,the same lung region appears normally aerated. The pleural line can be seen. B: The images of upper part of anterior region of right chest wall before and after RM. Left: Coalescent B lines (B2 lines) arising from the pleural line are present. Right: After RM, the same lung region appears normally aerated. The pleural line can be seen with two isolated B lines. These artifacts correspond to ground-glass areas on chest computed tomography. C: The images of lower part of lateral region of right chest wall before and after RM. Left: Transversal view of consolidated right lobe. Lung consolidation appears as a tissue structure can be seen. Right: After RM, the same lung region appears normally aerated. The pleural line can be seen with an isolated B line.These artifacts correspond to air-space consolidation areas on chest computed tomography.

Table 4. Extent of each CT finding in 8 patients infected with H7N9 virus

?

DISCUSSION

The A (H7N9) virus are one of the most virulent respiratory tract viruses infecting humans.[17] Previous studies have showed that the histopathological damages could be divided into 3 stages after avian influenza infection.[18-21] An exudative inflammatory phase is seen in H7N9 infection within 8 days after symptom onset,characterized by intra-alveolar hemorrhage, diffuse alveolar damage, edema, fibrous exudates and hyaline formation. And the H7N9-infected patients who died on day 11 after symptom onset developed pneumocyte hyperplasia and interstitial fibrosis in addition to the diffuse alveolar damage, which were compatible with the fibro-proliferative phase.[18] In our cases, the mean CT scores of the eight patients was 247.68±34.28, which means H7N9 caused serious damage to the lung. The patient 2 who survived underwent a follow-up CT that showed extensive interstitial fibrosis in right lung six months after discharge from hospital. Thus, it is crucial to reduce iatrogenic lung damage and the formation of fibrosis during respiratory support.

地下开采过程中岩石物理力学性质的测量通常是比较困难的，而对岩石物理力学性质的影响因素又多种多样，容易造成结果的不确定性，因此对岩石物理力学性质的研究，采用较多的是岩石弹性波速测量及声发射观测等声学方法，主要分为2种[8]：

阿托伐他汀钙是HMG-CoA还原酶的选择性、竞争性抑制剂，通过抑制肝脏内HMG-CoA还原酶和胆固醇的合成从而降低血浆中胆固醇和脂蛋白水平，并通过增加细胞表明的肝脏LDL受体以增强LDL的摄取和代谢。阿托伐他汀可降低低密度脂蛋白胆固醇胆固醇生成和低密度脂蛋白胆固醇颗粒数，并导致低密度脂蛋白胆固醇受体活性显著和持久性增加，进而循环中的低密度脂蛋白胆固醇颗粒治疗发生有益变化，疗效显著[12-13]。

Figure 4. The PaO2/FiO2 ratio, PaCO2, PEEP, FiO2 values of the 61-year-old female patient (No. 1) during the prone positioning.This patient died of multiple organ failure (MOF) after refractory hypoxemia.

Currently, the low tidal volume strategy is recommended for the management of patients with ARDS to protect the lung from ventilator-induced lung injury (VILI) and hopefully improve outcomes.[22-24]During the H7N9 pandemic, the ventilator strategy of low tidal volume and open-lung approach was chosen in our ICU as the conventional mode of mechanical ventilation. And high levels of PEEP were often used to achieve adequate oxygenation. In our cases, PEEP was increased to levels of 18-30 cmH2O, with variable response in terms of oxygenation. This variable response seems not to correlate with extent of alveolar infiltrates or severity of hypoxemia. Alternative modes of ventilation such as airway pressure release ventilation(APRV) and high-frequency oscillatory ventilation(HFOV), if available, may be considered in the setting of persistent hypoxemia (SaO2＜88%-90%, with high PEEP and FiO2＞0.8) or when the goals of lung-protective ventilation cannot be met (PPlat ＞30-35, VT ＞8 mL/kg),particularly in the setting of progressive patient decline.[25]

RM with the transient application of high levels of PEEP is one of the options to improve the oxygenation in patients with life-threatening hypoxemia, which aim to open collapsed lung units and increase functional residual capacity by increasing transpulmonary pressure.Its positive effect on the final mortality is still under debate.[26] And the optimal method for delivering RM is unknown.[27] In our practice, we used ultrasound reaeration score, the change of P-V curve and PaO2/FiO2 ratio to provide a bedside estimate of potentially recruitable lung before RM. The optimal PEEP after RM is the minimum PEEP level that sustains the oxygenation benefit of the recruitment maneuver. Like ARDS induced by H1N1 infection,[25] the variability in response to RM also may have been related to differences in the percentage of collapsed lung vs. ground-glass infiltrates o n chest computed tomography. Two out of the 4 patients (no. 2 and 3) with H7N9 infection responded to the RM with decremental PEEP titration. But patient 2 developed extensive interstitial fibrosis in right lung which may occur secondary to lung damage induced by RM. And although patient 3 with diffuse architectural distortion (the highest CT score, 294.7) at early stage responded to RM, he died of pneumothorax which is a common complication of RM. Our H7N9-infected patients with pulmonary endogenous ARDS were found t o have serious architectural distortion and high CT scores. Use of high transpulmonary pressures in these patients may cause further lung damage, and induce bad outcomes. Thus, application of RM in H7N9-infected patients with ARDS requires serious consideration.Once patients improved and the weaning process should started to decrease PEEP. The best approach was that of watchful waiting with very small changes made daily to the ventilator settings, and an attempt was often made to decrease PEEP＜20 cmH2O before weaning FiO2 significantly.[25]

Figure 5. The PaO2/FiO2 ratio, PaCO2, PEEP, FiO2 values of the 34-year-old male patient (No. 4) during the prone positioning.

1）建设用地的变化速度最快，1985－2000年和2000－2016年的单一动态度分别达到1.17%和1.96%，远远高于其他土地利用类型；

Prone position has been utilized to improve oxygenation in patients with ARDS. Alveolar recruitment, improvement in ventilation/perfusion matching from redistribution of ventilation to dorsal lung regions, elimination of the heart’s compressive effects on the lungs, better drainage of respiratory secretions and reduction of parenchymal lung stress/strain are the physiologic mechanisms to explain the improvement in oxygenation.[28,29] The recent study on prone positioning have showed a significant improvement in 28-day and 90-day mortality.[10] Recently,two meta-analysis of randomized control trials on prone ventilation in adults found to significantly reduce overall mortality in patients with ARDS in the low tidal volume era.[30,31] Gattinoni et al[32] had demonstrated that ARDS patients who respond to prone positioning with reduction of their PaCO2 (decreased physiologic dead space ratio)show an increased survival at 28 days. In patient 4 who had a poor chest wall compliance (BMI=35.49),the total respiratory system compliance increased depending on the increased lung compliance because of lung recruitment in prone position while chest wall compliance didn’t change too much. Thus, improvement in oxygenation was immediate in the prone position in this patient and the PaCO2 value got lower. The other patient (No. 1) who died of refractory hypoxemia got higher PaO2 value in the prone position with a higher PaCO2 value. Therefore, in our experience, prone position is an intervention that can be used in the setting of hypoxemia with mortality benefit in the early stage of ARDS. Patients who are hemodynamically unstable would be poor candidates because of the difficulty resuscitating a patient in the prone position. In these patients, other interventions like neuromuscular blockade and extracorporeal membrane oxygenation (ECMO)should be tried to adjust the hypoxemia (ECMO was refused by patient 1’s family).

CONCLUSION

In summary, in H7N9-infected patients with severe ARDS who need MV, low tidal volume strategy with the use of PEEP was the conventional mode. Application of RM as one of rescue therapies to refractory hypoxemia in these patients with serious architectural distortion and high CT scores, which could cause further lung damage, may induce bad outcomes and requires serious consideration. Prone ventilation may improve mortality,and should be performed at the early stage of the disease,not as a rescue therapy.

Funding: This work was supported by the National Natural Science Foundation of China (grant number 81501654)and Natural Science Foundation of Shanghai (grant number 14ZR1433700).

Ethical approval: This study was approved by the Regional Ethics Committee of our hospital (No: 2016KY155).

Conflicts of interest: The authors state they have no competing interests.

Contributors: HX and ZGZ contributed equally to this work. All authors read and approved the final version of the manuscript.

REFERENCE

1 To KK, Chan JF, Chen H, Li L, Yuen KY. The emergence of influenza A H7N9 in human beings 16 years after influenza A H5N1: a tale of two cities. Lancet Infect Dis. 2013;13(9):809-21.

4 Tsai NW, Ngai CW, Mok KL, Tsung JW. Lung ultrasound imaging in avian influenza A (H7N9) respiratory failure. Crit Ultrasound J. 2014;6(1):6.

16 Guideline on prevention and control of H7N9 avian influenza human infection. J Thorac Dis. 2013;5 Suppl 2:S168-72.

3 Lin ZQ, Xu XQ, Zhang KB, Zhuang ZG, Liu XS, Zhao LQ, et al. Chest X-ray and CT findings of early H7N9 avian in fl uenza cases. Acta Radiol. 2015;56(5):552-6.

Two patients (No. 1 and No. 4) underwent prone positioning to improve oxygenation which had poor response to the RM. Figures 4 and 5 illustrate the PaO2/FiO2 ratio, PaCO2, PEEP, FiO2 values obtained during the prone positioning of the two patients. Improvements in oxygenation were immediate in the prone position in both 2 patients. The PaCO2 value got higher in one patient (No. 1) and the prone treatment was stopped in this patient because of the following hypercapnia (PaCO2108.5 mmHg), acute kidney injury (AKI) and continues renal replacement therapy (CRRT). The other patient(No. 4) met the criteria (PaO2/FiO2 ≥150 mmHg with PEEP≤10 cmH2O and FiO2 ≤0.6, these criteria had to be met in supine at least 4 hours after the end of the last prone session) in the second day of the prone positioning and we decided to stop the prone intervention.

长期以来，如何应对干旱一直是国际社会普遍关注的问题。如今，美国的干旱管理已从危机管理转向风险管理；英国、澳大利亚提倡工程与非工程结合的管理体系，注重更为科学地规划、设计、建设、管理与运用好水利工程体系，充分发挥水利工程的综合效益；南非、以色列等国家，更加关注水的利用效率和效益，转为适应性管理。总体来看，当前世界各地的对策主要为：①水资源短缺→＋增加投资→＋增加供水→－缺水率→＋经济发展→＋水资源短缺；②水资源短缺→＋加强管理→＋减少需水→－缺水率→＋经济发展→＋水资源短缺。式中，“＋”表示正反馈；“－”表示负反馈。

其实，巨大的霸王龙对肿头龙的威胁并不大，一些中小型的食肉恐龙才是肿头龙真正的敌人，比如冥河盗龙、达科他盗龙、矮暴龙等。体长超过5米的达科他盗龙和矮暴龙是肿头龙的噩梦，一个像是放大版的恐爪龙，另一个则像缩小版的霸王龙，都是凶残、聪明且行动敏捷的“恐龙杀手”。为了能在危险的世界中生存，肿头龙必须成群结队地生活在一起，并在危险来临时，使出它们的绝招——铁头功。

5 Gao HN, Lu HZ, Cao B, Du B, Shang H, Gan JH, et al. Clinical findings in 111 cases of influenza A (H7N9) virus infection. N Engl J Med. 2013;368(24):2277-85.

6 Yu H, Cowling BJ, Feng L, Lau EH, Liao Q, Tsang TK, et al. Human infection with avian influenza A H7N9 virus: an assessment of clinical severity. Lancet. 2013;382(9887):138-45.

7 Uyeki TM, Cox NJ. Global concerns regarding novel in fl uenza A(H7N9) virus infections. N Engl J Med. 2013;368(20):1862-4.

8 Ranieri VM, Rubenfeld GD, Thompson BT, Ferguson ND,Caldwell E, Fan E, et al. Acute respiratory distress syndrome: the Berlin Definition. JAMA. 2012;307(23):2526-33.

9 Girgis K, Hamed H, Khater Y, Kacmarek RM. A decremental PEEP trial identifies the PEEP level that maintains oxygenation after lung recruitment. Respiratory Care. 2006;51(10):1132-9.

10 Guerin C, Reignier J, Richard JC, Beuret P, Gacouin A, Boulain T, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013;368(23):2159-68.

传统上，开发智能系统的目标是追求一种理想的问题求解技术，这里的关键是我们需要解决的是什么样的问题。神经网路是用结构的复杂性而不是规则的复杂性来克服其处理问题的复杂性。让人工神经网络这一工具变得前所未有地强大的，正是其网络性而不是有关神经元的设想——因为神经元本身不管怎样复杂仍然是一个经典的输入输出系统。尽管如此，还是应该牢记一点，那就是神经网络主要是用来解决模式识别问题的。

11 Bouhemad B, Brisson H, Le-Guen M, Arbelot C, Lu Q, Rouby JJ. Bedside ultrasound assessment of positive end-expiratory pressure-induced lung recruitment. Am J Respir Crit Care Med.2011;183(3):341-7.

12 Bouhemad B, Liu ZH, Arbelot C, Zhang M, Ferarri F, Le-Guen M, et al. Ultrasound assessment of antibiotic-induced pulmonary reaeration in ventilator-associated pneumonia. Crit Care Med.2010;38(1):84-92.

13 Ichikado K, Johkoh T, Ikezoe J, Takeuchi N, Kohno N, Arisawa J, et al. Acute interstitial pneumonia: high-resolution CT findings correlated with pathology. AJR Am J Roentgenol.1997;168(2):333-8.

14 Ichikado K, Suga M, Muller NL, Taniguchi H, Kondoh Y, Akira M, et al. Acute interstitial pneumonia: comparison of highresolution computed tomography findings between survivors and nonsurvivors. Am J Respir Crit Care Med. 2002;165(11):1551-6.

15 Ichikado K, Suga M, Muranaka H, Gushima Y, Miyakawa H,Tsubamoto M, et al. Prediction of prognosis for acute respiratory distress syndrome with thin-section CT: validation in 44 cases.Radiology. 2006;238(1):321-9.

2 Poovorawan Y. Epidemic of avian influenza A (H7N9) virus in China. Pathog Glob Health. 2014;108(4):169-70.

17 W.H. Organization, Overview of the emergence and characteristics of the avian in fl uenza A(H7N9) virus. Available at: http://www.who.int/influenza/human_animal_interface/in fl uenza_h7n9/WHO_H7N9_review_31May13.pdf, Accessed 1 June 2013.

18 Yu L, Wang Z, Chen Y, Ding W, Jia H, Chan JF, et al. Clinical,virological, and histopathological manifestations of fatal human infections by avian influenza A(H7N9) virus. Clin Infect Dis.2013;57(10):1449-57.

19 To KK, Hung IF, Li IW, Lee KL, Koo CK, Yan WW, et al.Delayed clearance of viral load and marked cytokine activation in severe cases of pandemic H1N1 2009 influenza virus infection. Clin Infect Dis. 2010;50(6):850-9.

动迁办力度很大，效率也很高，普查，公布补偿政策，动员拆迁户，几乎同时铺开。先搬的，有奖励，不仅免费帮你请搬家公司，还送一台36寸液晶电视。超过限期不搬的，强制执行。汤翠暗暗为政府叫好，要是搁从前，别说 1：1.4，1：1 都难，土地是国家的，给不给你还不由着国家？

The Murray’s lung injury score at the time of first CT examination was 2.97±1.03. The CT finding in the 8 patients is summarized in Table 2 (Figures 1, 2) and the extent of each CT finding is summarized in Table 3.Figure 1 shows the CT Finding in a 35-year-old man who survived (patient 2). First CT shows a wide range of ai rspace consolidation with air bronchograms posteriorly and areas of ground-glass attenuation anteriorly(Figure 1A). The follow-up CT shows (6 months after discharge from hospital) irregular reticular opacities,traction bronchiolectasis (arrows) and bronchiectasis.The chest X-ray shows elevation of right diaphragm induced by restricted lung expansion (Figure 1B).Architectural distortion, ground-glass attenuation and air-space consolidation were the most commonly seen in the patients with ARDS caused by H7N9 infection.The extent of ground-glass attenuation and air-space consolidation combined with or without traction bronchiolectasis or bronchiectasis was about 65% of the whole lung. The abnormalities were bilateral in all the patients. Th e overall CT scores of the patients was 247.68±34.28 and the range of CT scores was 196.3 to 294.7. The 2 observers showed good agreement in their evaluations of the presence of lung abnormalities(Kappa statistic 0.73), and the assessments of the extent of abnormalities made by the two observers were also well correlated (Spearman rank correlation coefficient,r=0.78, P＜0.01).

21 Korteweg C, Gu J. Pathology, molecular biology, and pathogenesis of avian in fl uenza A (H5N1) infection in humans.Am J Pathol. 2008;172(5):1155-70.

22 Serpa Neto A, Cardoso SO, Manetta JA, Pereira VG, Esposito DC, Pasqualucci Mde O, et al. Association between use of lungprotective ventilation with lower tidal volumes and clinical outcomes among patients without acute respiratory distress syndrome: a meta-analysis. JAMA. 2012;308(16):1651-9.

23 Terragni PP, Del Sorbo L, Mascia L, Urbino R, Martin EL,Birocco A, et al. Tidal volume lower than 6 ml/kg enhances lung protection: role of extracorporeal carbon dioxide removal.Anesthesiology. 2009;111(4):826-35.

[34]北京大学哲学系外国哲学史教研室编译：《西方哲学原著选读》(上卷)，北京：商务印书馆，1999年，第176页。

24 Acute Respiratory Distress Syndrome Network, Brower RG,Matthay MA, Morris A, Schoenfeld D, Thompson BT, et al.Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342(18):1301-8.

25 Ramsey CD, Funk D, Miller RR 3rd, Kumar A. Ventilator management for hypoxemic respiratory failure attributable to H1N1 novel swine origin influenza virus. Crit Care Med.2010;38(4 Suppl):e58-65.

26 Zhang HW, Wei LY, Zhao G, Yang YJ, Liu SZ, Zhang ZY, et al. Periplaneta americana extract used in patients with systemic inflammatory response syndrome. World J Emerg Med.2016;7(1):50-4.

27 Spieth PM, Gama de Abreu M. Lung recruitment in ARDS: we are still confused, but on a higher PEEP level. Crit Care. 2012;16(1):108.

28 Nizami MI, Narahari NK, Paramjyothi GK, Sharma A.An unusual cause of simultaneous bilateral spontaneous pneumothorax.World J Emerg Med. 2017;8(1):74-6.

综上所述，在初中数学教学过程中，利用多媒体辅助教学可以有效提高教学效果，为学生的学习开拓更加广阔的空间，提高学习效率。但教师在多媒体运用过程中，也要注意一些现实的问题，比如多媒体可以扩大课堂教学的容量，但是内容安排太多的话，学生的思维根本就跟不上教师的步伐，反而会适得其反。再比如多媒体课件过于花哨，学生的注意力就容易被吸引，影响教学效果。总之，扬长避短，适度使用，才是保障多媒体教学的有效策略。

29 Wei M, Gong YJ, Tu L, Li J, Liang YH, Zhang YH. Expression of phosphatidylinositol-3 kinase and effects of inhibitor Wortmannin on expression of tumor necrosis factor-α in severe acute pancreatitis associated with acute lung injury. World J Emerg Med. 2015;6(4):299-304.

目前待发布的水利行业标准《水库大坝风险标准》，参照《生产安全事故报告和调查处理条例》（国务院令第493号）将水库大坝安全分为四类：特别重大、重大、较大、一般,具体见表1。

30 Lee JM, Bae W, Lee YJ, Cho YJ. The efficacy and safety of prone positional ventilation in acute respiratory distress syndrome: updated study-level meta-analysis of 11 randomized controlled trials. Crit Care Med. 2014;42(5):1252-62.

31 Beitler JR, Shae fi S, Montesi SB, Devlin A, Loring SH, Talmor D, et al. Prone positioning reduces mortality from acute respiratory distress syndrome in the low tidal volume era: a meta-analysis. Intensive Care Med. 2014;40(3):332-41.

32 Gattinoni L, Vagginelli F, Carlesso E, Taccone P, Conte V,Chiumello D, et al. Decrease in PaCO2 with prone position is predictive of improved outcome in acute respiratory distress syndrome. Crit Care Med. 2003;31(12):2727-33.