急性呼吸窘迫综合征完整通气支持适应性支持通气:一个试点,随机对照试验

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Statistical methods
Statistical significance was assumed at a P-value <0.05. The categorical variables were analyzed using chi-square test, while the continuous variables were analyzed using Mann–Whitney U-test. The change in variables over time was analyzed with repeated measures analysis of variance using the mixed linear model.[23] Survival curves were constructed to study the effect of ventilator strategy on respiratory intensive care unit stay using Kaplan–Meier analysis, and group differences were analyzed using the log-rank test.

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Results
There were 352 respiratory intensive care unit admissions (227 patients received invasive ventilation, 43 patients received non-invasive ventilation (NIV), and 82 received oxygen therapy and ICU care for various indications) during the study period. Seventy-three (20.7%) patients were admitted with a diagnosis of ARDS. Of these, seven patients had a duration of illness of more than 7 days, six had contraindications to permissive hypercapnea, and 12 had underlying chronic lung disease and were excluded prior to randomization (Fig. 2). Forty-eight patients met the inclusion criteria and were enrolled in the study. There were 28 males and 20 females with mean (standard deviation) age of 30 (13) years. Twenty-five patients were randomized to the VCV arm and 23 to the ASV group. Sepsis (29.2%) and community-acquired pneumonia (22.9%) were the most common cause of ARDS (Table 1). A total of seven (14.5%) patients received a trial of NIV prior to intubation, with a significantly higher number in the VCV (n = 6) compared with the ASV arm (n = 1). The baseline characteristics of the study group were similar except for Vt, which was higher in the ASV group (Table 1). The baseline disease severity assessed by acute physiology and chronic health evaluation II and sequential organ failure assessment scores was not different in the two groups. Figure 3 shows the change in Vt, PEEP, Pplat, static compliance, pH and PaO2/FIO2 scores over time. The tidal volume delivered significantly increased with time and was different between the two groups until 10 days. The PEEP used gradually decreased over time and was similar in the two groups. There was gradual decline in the Pplat and was significantly different between the groups only on days 4 and 5. The PaO2/FIO2 ratio, pH and static compliance also gradually increased and were not different between the two groups.
研究期间有352个呼吸重症监护室患者(227名患者接受侵入性通风,43名患者接受非侵入式通风(9),和82名患者氧气疗法和ICU护理各种迹象)。73例(20.7%)患者诊断ARDS，其中,7个病人疾病持续时间超过7天,6个病人呼吸过度,12个病人潜在的慢性肺部疾病,排除随机化之前(图2)。48例符合入选标准和参与这项研究。有28个男性和20名女性,平均年龄30岁(13)。25个病人被随机分为VCV和23 ASV组。脓毒症(29.2%),肺炎(22.9%)的最常见原因ARDS(表1)。总共七个(14.5%)患者接受插管前,与数量明显高于VCV(n = 6)相比ASV(n = 1)。研究小组的基线特征相似除了Vt, 更高的ASV组(表1)。基线疾病严重度评估急性生理和慢性健康评估II 和顺序器官衰竭评估分数两组是不同的。图3显示了Vt的变化,peep,Pplat,静态顺应性,pH值随着时间的推移,PaO2 /供给分数。随着时间的推移潮气量显著增加,不同的两组间,直到10天。随时间逐渐减少使用的窥视,在两组相似。两组之间在天4和5Pplat有逐渐下降和明显不同。PaO2 /供给比、pH值和静态依从性也逐渐增加,两组之间没有不同。

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Discussion
The results of this study suggest that clinical outcomes with ASV are similar to VCV in managing patients with ARDS. ASV was comparable to VCV in maintaining Pplat below 30 cm of H2O.[18] This is the first trial to report ARDS outcomes in patients solely ventilated with ASV. In fact, the majority of evidence regarding the use of ASV is for weaning postoperative patients[24-29] or chronic obstructive pulmonary disease patients.[30] The use of ASV in ARDS is conceptually appealing because it is a pressure-targeted form of closed-loop ventilation that optimizes the relationship between Vt and respiratory frequency based on lung mechanics.[8] ASV automatically determines the best Vt and fR that maintains the peak pressure below the target level. Further, ASV by automatically adjusting airway pressure prevents the adverse effects of excessive Pplat than a fixed tidal volume.[12] In a physiological study of total ventilatory support in respiratory failure, ASV was found superior to conventional ventilation with regard to haemodynamic, ventilatory and gas exchange parameters, except for excessive Vt in few patients with obstructive lung disease.[31]
这项研究的结果表明,临床结果ASV与vcv管理ARDS患者相类似。 维护Pplat低于30厘米水柱ASV相媲美VCV。这是第一次试验报告ARDS患者结果只用ASV通气。事实上,大多数的证据关于ASV的使用是术后患者(24-29)或慢性阻塞性肺病患者。利用ASV（ ARDS）是概念上的吸引力,因为它是基于肺力学一个pressure-targeted的闭环通风形式优化Vt和呼吸频率之间的关系。ASV自动确定最佳Vt和fR,维护峰值压力低于目标水平。此外,相比固定的潮气量ASV通过自动调整气道压力防止过度Pplat的副作用。除了过度Vt阻塞性肺疾病患者，生理研究总通气支持呼吸衰竭,ASV发现优于传统的通风对血液动力学的通气和气体交换参数。
In this study, Vt delivered by ASV were slightly higher compared with VCV, albeit the Pplat was comparable on most days and so were the other end-points. In the ASV mode, we measured only the Pinsp and not the Pplat. In ASV, the alveolar pressure can be considered equal to Pinsp only when inspiratory time is adequate for inspiratory flow to reach zero, in which circumstance there is no pressure gradient between proximal airway pressures and alveolar pressure. However, such a setting is not possible with ASV; as such, the Pplat may actually be lower in the ASV group.
在这项研究中,与VCV相比Vt由ASV略高,尽管Pplat可比大多数日子里,所以在ASV模式,另一个端点。我们只测量Pinsp而不是Pplat。在ASV,肺泡的压力可以被认为是等于Pinsp只有当吸气时间是足够的吸气流达到零,在这情况下没有近端气道压力和肺泡之间的压力梯度。然而,这种环境下不适合ASV;因此,ASV组Pplat实际上可能是降低。
Studies designed specifically to compare ASV with VCV have suggested conflicting results with the ASV strategy.[12, 13] In a study comparing ASV with VCV, the inspiratory and expiratory Vt and expiratory resistance were higher, while the total fR and maximum pressure were lower with ASV. No changes in the arterial blood gases, heart rate or mean arterial pressure were observed.[13] In contrast, another study found ASV to deliver lower Vt compared with VCV.[12] Earlier studies have also reported higher Vt–fR ratios in patients ventilated with ASV.[11, 32, 33] In a study that evaluated only the breathing pattern, ASV was found to deliver Vt at a range of 4.8–10 mL/kg in patients with restrictive lung disease.[31] As ASV manipulates the ventilator with each breath, the number of interventions by the physician and the alarms are likely to be lesser, although this was not particularly evaluated in the current trial.
研究专门比较ASV VCV建议与ASV策略冲突的结果。(12、13)在一项比较ASV VCV,吸气和呼气Vt和呼气阻力高,虽然总fR和最大压力与ASV低。没有动脉血液气体的变化,心率、平均动脉压观察。[13]与此相反,另一项研究发现ASV提供低比VCV Vt。[12]早期的研究也报道患者通风ASV Vt-fR比率增加。[11,32岁,33]在一项研究中,只有呼吸模式进行评估,发现ASV Vt的范围4.8 -10毫升/公斤限制性肺病患者。[31]虽然这不是特别评估当前的评判，ASV操纵通气机每次呼吸,医生干预措施的数量和警报可能较小。
ASV reopens the debate of pressure versus volume ventilation in the management of ARDS, although data supporting the use of either approach are equivocal.[34-38] The ARDS network trial used volume ventilation in both arms.[18] Studies comparing the effects of pressure versus volume ventilation have not been well designed.[39] However, the advent of closed-loop mechanical ventilation now combines the best characteristics of both pressure and volume-controlled ventilation.[19] Regardless of the mode used, the emphasis of ventilation has shifted to supportive care and prevention of aggravation of lung injury rather than cure of ARDS. This study suggests that ASV could be a viable alternative to VCV in the management of ARDS.

ASV重开辩论的压强与体积通气ARDS的管理,尽管数据支持使用方法是模棱两可的。 ARDS  通风使用。 研究比较压强与体积的影响通气没有设计好。 然而,闭环机械通气的出现现在的最佳特征结合压力和交织通气。无论模式使用,通气的重点已经转移到支持性护理和预防肺损伤的加重而不是治疗ARDS。这项研究表明,在ARDS的管理中ASV可能是一个可行的替代VCV方案。
The strength of the current study includes its randomized nature, ASV as a primary mode of ventilation and the comparison of clinical outcomes for up to 2 weeks following randomization. The limitations include the small study sample, conducted at a single centre and the unblinded nature of the study. Further, we collected only hospital mortality and not 28-day or 90-day survival, which are better descriptors of outcome. Although the attending physicians found VCV easier to use than ASV, this difference reflects mere statistical significance as the scores were low in both the groups. The other reason could be the unfamiliarity, as the mode was in practice only for 1 year prior to this trial. Specific training of the intensivists on how to best set the ASV is an important issue, which should be considered in any future trial involving ASV.
当前研究的力量包括其随机性质,ASV作为主要通气方式和临床结果的比较随机化后2周。限制包括小型研究样本,在一个中心的选取进行这项研究。此外,我们只收集医院死亡率,而不是28天或90天的生存,更好的描述符合结果。尽管主治医生发现ASV比 VCV更容易使用,这种差异反映了仅仅是统计学意义的分数高低。另一个原因在此之前评判可能是在实践中不熟悉,通气模式。重症的特定培训等如何最好的ASV的设置是一个很重要的问题,应该考虑在未来任何涉及ASV的评判。
In conclusion, this study found no difference in the outcomes in patients with ARDS ventilated with either ASV or VCV with regard to the duration of medical care, morbidity or mortality. Larger clinical studies are warranted to clarify the role of ASV as a primary mode for ventilation in ARDS.
总之,本研究结果没有发现ARDS患者的通气与ASV或VCV关于医疗保健的持续时间,发病率或死亡率存在差异。必要更大的临床研究证实ASV作为ARDS主要通气模式。

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