Airway pressure release ventilation in acute respiratory distress syndrome

Airway pressure release ventilation (APRV) is an alternative mode of ventilation that is increasingly used in patients with acute respiratory failure, acute lung injury (ALI), and acute respiratory distress syndrome (ARDS). Animal and clinical studies have demonstrated that, compared with conventional ventilation, APRV has beneficial effects on lung recruitment, oxygenation, end-organ blood flow, pulmonary vasoconstriction, and sedation requirements. Further studies, however, are required to directly compare APRV to ARDSnet protocol ventilation, specifically in patients with ALI/ARDS, and to determine whether managing ALI/ARDS with APRV will also achieve mortality reduction.     

Airway pressure release ventilation: an alternative mode of mechanical ventilation in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) results in collapse of alveoli and therefore poor oxygenation. In this article, we review airway pressure release ventilation (APRV), a mode of mechanical ventilation that may be useful when, owing to ARDS, areas of the lungs are collapsed and need to be reinflated ("recruited"), avoiding cyclic alveolar collapse and reopening.     

Airway pressure release ventilation increases cardiac performance in patients with acute lung injury/adult respiratory distress syndrome

Background  

The purpose of the present study is to determine whether airway pressure release ventilation (APRV) can safely enhance hemodynamics in patients with acute lung injury (ALI) and/or adult respiratory distress syndrome (ARDS), relative to pressure control ventilation (PCV).     

气道压力释放通气对急性呼吸窘迫综合征患者疗效的Meta分析

目的系统评价气道压力释放通气（APRV）治疗急性呼吸窘迫综合征（ARDS）患者的疗效。 方法计算机检索Cochrane Library、PubMed、Embase、中国生物医学文献数据库、中国知网、万方数据库,查找关于APRV与常规机械通气对比治疗ARDS患者的随机对照试验（RCTs）,检索时限从建库到2021年3月。由2名研究者按照纳入与排除标准筛选文献、提取数据和评价质量后,采用RevMan 5.2软件和Stata 1.4软件进行Meta分析。 结果共纳入11项RCTs,合计611例患者。Meta结果显示,治疗后,APRV组ARDS患者的氧合指数高于对照组[均数差（MD）= 31.70,95%置信区间（CI）（3.76,59.63）,Z = 2.22,P = 0.03],且APRV组患者28 d病死率显著低于对照组[比值比（OR）= 0.55,95%CI（0.36,0.84）,Z = 2.77,P = 0.006]。 结论对于ARDS患者而言,早期应用APRV能够增加氧合功能,降低28 d病死率。     

急性呼吸窘迫综合征患者早期应用气道压力释放通气的疗效

目的探讨早期应用气道压力释放通气（APRV）对急性呼吸窘迫综合征（ARDS）患者的临床疗效。 方法将2017年9月至2019年6月收住在兰州大学第一医院ICU的71例ARDS患者分为APRV组（36例）和小潮气量（LTV）组（35例）。APRV组患者起初给予容量辅助控制通气模式,测量气道平台压后转为APRV模式;LTV组患者接受LTV通气,目标潮气量设置为6~8 mL/kg,依据ARDSnet协议调节呼气末正压（PEEP）水平、潮气量和呼吸频率。记录两组患者的一般资料,比较其机械通气第1天和第7天呼吸机参数、呼吸力学指标、血气功能指标、循环功能指标及预后情况;绘制Kaplan-Meier生存曲线,比较两组患者28 d生存情况。 结果机械通气第7天,APRV组和LTV组患者吸入氧浓度（FiO₂）[（47 ± 5）% vs.（66 ± 5）%,t = 3.746,P < 0.001]、呼吸频率[（24 ± 4）次/min vs.（18 ± 4）次/min,t = 3.453,P < 0.001]、PEEP[（5.6 ± 2.3）cmH₂O vs.（10.8 ± 4.4）cmH₂O,t = 3.011,P < 0.001]、气道峰压[23.9（18.5,29.6）cmH₂O vs. 25.1（11.3,31.8）cmH₂O,H = 2.736,P = 0.014]、气道平台压[22.2（18.7,24.3）cmH₂O vs. 19.6（17.2,22.4）cmH₂O,H = 2.154,P = 0.023]、平均气道压[23.8（22.1,24.3）cmH₂O vs. 15.4（13.9,19.4）cmH₂O,H = 2.814,P = 0.018]、肺顺应性[52.7（37.4,62.3）mL/cmH₂O vs. 41.8（31.5,57.6）mL/cmH₂O,H = 2.008,P = 0.034]、动脉血氧分压（PaO₂）[（89 ± 7）mmHg vs.（72 ± 7）mmHg,t = 2.324,P < 0.001]、PaO₂/FiO₂ [（201 ± 15）mmHg vs.（140 ± 12）mmHg,t = 2.743,P < 0.001]、动脉血氧饱和度（SaO₂）[（95.4 ± 2.1）% vs.（92.3 ± 1.8）%,t = 2.658,P < 0.001]、心率[（99 ± 9）次/min vs.（108 ± 9）次/min,t = 2.733,P = 0.014]及平均动脉压[（84 ± 11）mmHg vs.（74 ± 13）mmHg,t = 3.012,P = 0.011]比较,差异均有统计学意义。APRV组ARDS患者机械通气时间[（9.6 ± 2.2）d vs.（11.9 ± 2.9）d,t = 3.687,P < 0.001]、住ICU时间[（11.3 ± 3.1）d vs.（13.2 ± 2.7）d,t = 2.722,P = 0.008]、住院时间[（13.9 ± 2.5）d vs.（16.2 ± 2.4）d,t = 3.924,P = 0.004]均较LTV组显著缩短,拔管成功率[80.6%（29/36）vs. 54.3%（19/35）,χ² = 5.592,P = 0.018]显著升高,肺复张[5.6%（2/36）vs. 48.6%（17/35）,χ² = 16.753,P < 0.001]、俯卧位通气[11.1%（4/36）vs. 34.3%（12/35）,χ² = 5.460,P = 0.019]、气胸发生率[8.3%（3/36）vs. 28.6%（10/35）,χ² = 4.860,P = 0.028]及28 d住院病死率[13.9%（5/36）vs. 34.3%（12/35）,χ² = 4.054,P = 0.044]均显著降低。Kaplan-Meier生存曲线结果显示,APRV组ARDS患者生存情况显著优于LTV组（χ² = 4.118,P = 0.015）。 结论与LTV组比较,早期应用APRV可显著改善ARDS患者的氧合功能和呼吸系统顺应性,提高拔管成功率,降低气胸发生率,并减少机械通气时间和住院时间。     

Adult respiratory distress syndrome in a child with acute epiglottitis

Intubation of a 23-month-old child suffering epiglottitis was complicated by pulmonary edema progressing to the adult respiratory distress syndrome. Increased pulmonary shunt and pulmonary hypertension required high levels of positive end-expiratory pressure and prolonged mechanical ventilation to correct hypoxemia. A possible role for a cuffed endotracheal tube in epiglottitis is discussed.     

Early application of airway pressure release ventilation may reduce the duration of mechanical ventilation in acute respiratory distress syndrome

Purpose

Experimental animal models of acute respiratory distress syndrome (ARDS) have shown that the updated airway pressure release ventilation (APRV) methodologies may significantly improve oxygenation, maximize lung recruitment, and attenuate lung injury, without circulatory depression. This led us to hypothesize that early application of APRV in patients with ARDS would allow pulmonary function to recover faster and would reduce the duration of mechanical ventilation as compared with low tidal volume lung protective ventilation (LTV).

Methods

A total of 138 patients with ARDS who received mechanical ventilation for <48 h between May 2015 to October 2016 while in the critical care medicine unit (ICU) of the West China Hospital of Sichuan University were enrolled in the study. Patients were randomly assigned to receive APRV (n = 71) or LTV (n = 67). The settings for APRV were: high airway pressure (P_high) set at the last plateau airway pressure (P_plat), not to exceed 30 cmH₂O) and low airway pressure ( P_low) set at 5 cmH₂O; the release phase (T_low) setting adjusted to terminate the peak expiratory flow rate to ≥ 50%; release frequency of 10–14 cycles/min. The settings for LTV were: target tidal volume of 6 mL/kg of predicted body weight; P_plat not exceeding 30 cmH₂O; positive end-expiratory pressure (PEEP) guided by the PEEP–FiO₂ table according to the ARDSnet protocol. The primary outcome was the number of days without mechanical ventilation from enrollment to day 28. The secondary endpoints included oxygenation, P_plat, respiratory system compliance, and patient outcomes.

Results

Compared with the LTV group, patients in the APRV group had a higher median number of ventilator-free days {19 [interquartile range (IQR) 8–22] vs. 2 (IQR 0–15); P < 0.001}. This finding was independent of the coexisting differences in chronic disease. The APRV group had a shorter stay in the ICU (P = 0.003). The ICU mortality rate was 19.7% in the APRV group versus 34.3% in the LTV group (P = 0.053) and was associated with better oxygenation and respiratory system compliance, lower P_plat, and less sedation requirement during the first week following enrollment (P < 0.05, repeated-measures analysis of variance).

Conclusions

Compared with LTV, early application of APRV in patients with ARDS improved oxygenation and respiratory system compliance, decreased P_plat and reduced the duration of both mechanical ventilation and ICU stay.

     

机械通气与急性呼吸窘迫综合征

经过多年来对机械通气认识水平的提高与操作技能的发展,机械通气已经成为临床常用的治疗方法,尤其是在对急性肺损伤/急性呼吸窘迫综舍征(ALI/ARDS)的治疗过程中,已经得到了较为广泛的共识和普遍的应用.ALI与ARDS在重症患者中仍然具有非常高的发病率和相关病死率,也因在最近一些公共医疗卫生重大事件中作为影响预后的主要因素,而被广为关注.     

无创正压通气治疗急性呼吸窘迫综合征的前瞻性队列研究

目的 观察和评价无创正压通气(NPPV)对急性呼吸窘迫综合征(ARDS)的疗效和安全性.方法 采用前瞻性队列研究,分析2004年1月-2007年12月北京朝阳医院呼吸重症监护病房(RICU)使用NPPV治疗ARDS患者的临床资料.结果 ①31例患者纳入本研究,其中男23例,女8例;年龄20～76岁,平均(49±17)岁;NPPV前急性生理学与慢性健康状况评分系统Ⅰ(APACHE Ⅰ)评分(14±8)分,氧合指数(PaO2/FiO2)(123±32)mm Hg(1 mm Hg=0.133 kPa).②NPPV成功率为74.2%(23/31),非肺部感染所致ARDS的成功率显著高于肺部感染所致ARDS(100%比60%,P=0.017).③与NPPV前相比,成功组NPPV治疗后2 h及24 h的心率(HR)、呼吸频率(RR)及PaO2/FiO2均有显著改善(P均<0.01),而失败组上述指标不但无显著改善,尚伴有动脉血二氧化碳分压(PaCO2)逐渐升高(P<0.05).患者均无NPPV相关的严重并发症.结论 对于无NPPV禁忌的ARDS患者,NPPV可作为一线呼吸支持手段;但对于在短期应用NPPV后生命体征及动脉血气无显著改善者,尤其是肺部感染诱发ARDS时应及早改为有创通气.     

Protective ventilation of patients with acute respiratory distress syndrome

In a recent issue of the British Journal of Anaesthesia, Moloney and Griffiths reviewed clinically pertinent issues surrounding the management of the acute respiratory distress syndrome (ARDS) patient, particularly as it pertains to the treatment of ventilator induced/associated lung injury (VILI). In addition to highlighting the important observations that have contributed to further our understanding of the relationship between the mechanical ventilator and inflammatory lung injury, the authors also offer a concise reappraisal of the clinical strategies used to minimize VILI in ARDS. Special emphasis is placed on the theory of biotrauma, which attempts to explain how multi-organ failure may develop in patients who ultimately succumb to this syndrome.     

Airway pressure release ventilation

Airway pressure release ventilation (APRV) delivers continuous positive airway pressure (CPAP) and may support ventilation simultaneously. This investigation tested whether, after acute lung injury (ALI), APRV promotes alveolar ventilation and arterial oxygenation without increasing airway pressure (Paw) above the CPAP level and without depressing cardiac function. Ten anesthetized dogs randomly received either intermittent positive-pressure ventilation (IPPV) or APRV. APRV was delivered with a continuous-flow CPAP system. Expiration occurred when a switch in the expiratory limb opened and Paw decreased to near-ambient, which decreased lung volume. After baseline data collection, ALI was induced by infusing oleic acid iv. Two hours later, IPPV and APRV were administered randomly, and data were collected. With normal lungs, APRV and IPPV achieved similar gas exchange and hemodynamic function. During ALI, arterial oxygenation was improved, and peak Paw which did not exceed the CPAP level, was lower during APRV. Similar minute ventilations were delivered by both modes but resulted in lower PaCO2 with APRV. Thus, APRV decreased physiologic deadspace ventilation. Hemodynamic status was similar during both modes. Therefore, APRV is an improved method of oxygenation and ventilatory support for patients with ALI that will allow unrestricted spontaneous ventilation and may decrease the incidence of barotrauma.     

无创正压通气治疗急性肺损伤/急性呼吸窘迫综合征的观察

目的 评价无创正压通气(NPPV)治疗急性肺损伤(ALI)／急性呼吸窘迫综合征(ARDS)患者的临床效果。方法 对18例ALI/ARDS患者实施NPPV治疗结果进行回顾性总结，分析NPPV治疗前后动脉血氧分压／吸氧浓度(PaO2／FiO2)、呼吸频率(RR)和心率(HR)的变化。结果 NPPV治疗成功率为55.6％(10／18)，8例NPPV治疗失败患者中7例改用气管插管有创通气。总死亡率为33．3％(6／18)。NPPV成功组50％(5／10)为ALI患者，治疗后1～2h PaO2／FiO2、RR和HR较治疗前有显著改善。NPPV失败组均为ARDS患者，治疗后1-2h PaO2／FiO2、RR和HR无明显变化。结论 NPPV对部分ALI／ARDS患者是有效的支持治疗手段，尤其是ARDS早期的ALI阶段可考虑选用NPPV。如NPPV治疗失败，应及时转换为气管插管有创通气。     

Protective ventilation of patients with acute respiratory distress syndrome

In a recent issue of the British Journal of Anaesthesia, Moloney and Griffiths reviewed clinically pertinent issues surrounding the management of the acute respiratory distress syndrome (ARDS) patient, particularly as it pertains to the treatment of ventilator induced/associated lung injury (VILI). In addition to highlighting the important observations that have contributed to further our understanding of the relationship between the mechanical ventilator and inflammatory lung injury, the authors also offer a concise reappraisal of the clinical strategies used to minimize VILI in ARDS. Special emphasis is placed on the theory of biotrauma, which attempts to explain how multi-organ failure may develop in patients who ultimately succumb to this syndrome.     

High-frequency oscillatory ventilation in adults with acute respiratory distress syndrome

The last decade has seen increased appreciation of ventilator-induced lung injury. The understanding that the process of mechanical ventilation can itself damage lungs has spurned the search for ventilation strategies that are more lung protective. High-frequency oscillatory ventilation is a mode of high-frequency ventilation that may accomplish all of the current goals of lung protection. Historically, much of the data evaluating high-frequency oscillatory ventilation came from neonatal and pediatric populations. In the past year, a number of provocative and exciting studies have been published that contribute significantly to our understanding of high-frequency oscillatory ventilation, its role in preventing and reducing ventilator-induced lung injury, and its use in the support of adult patients with lung injury. In this article, we discuss the current understanding of high-frequency oscillatory ventilation and highlight the most recent literature addressing its application in adult patients with acute respiratory distress syndrome.     

压力控制通气治疗创伤性急性呼吸窘迫综合征的应用探讨

目的：探讨压力控制通气（ＰＣＶ）用于治疗创伤性急性呼吸窘迫综合征（ＡＲＤＳ）的临床应用价值。方法：观察创伤性ＡＲＤＳ患者ＰＣＶ组和容量控制通气（ＶＣＶ）治疗后６和１２小时气道峰压（ＰＩＰ）,平均气道压（ＭＰａｗ）和呼气末正压（ＰＥＥＰ）的大小,并比较ＰＣＶ治疗对血气、血压和心率的影响。结果：ＰＣＶ组治疗后６和１２小时ＰＩＰ均显著低于ＶＣＶ组（Ｐ均〈０．０１）,６小时ＭＰａｗ和ＰＥＥＰ与ＶＣＶ比较无     

气道压力释放通气对ARDS患者有效性的Meta分析与试验序贯分析

目的评价气道压力释放通气（APRV）对急性呼吸窘迫综合征（ARDS）患者的有效性。 方法应用计算机检索美国国立医学图书馆PubMed数据库、科学网（Web of Science）、Cochrane图书馆数据库、中国知网（CNKI）、中国生物医学文献数据库（CBM）、维普数据库（VIP）、万方数据库2019年12月31日以前公开发表的关于APRV对ARDS患者疗效的临床随机对照试验,并通过纳入文献的参考文献进行引证检索。试验组采用APRV,对照组采用传统机械通气（CV）;结局指标包括住院病死率、ICU住院时间、肺顺应性、氧合指数及平均气道压。纳入文献的质量由2名经过专业培训的循证医学研究人员完成,对符合质量标准的文献进行Meta分析,同时采用试验序贯分析（TSA）方法评价APRV对ARDS患者住院病死率样本量的情况。 结果纳入8篇文献,共纳入患者461例患者,其中APRV组232例、CV组229例。结果显示APRV能够降低ARDS患者住院病死率（OR=0.63,95%CI=0.40~0.97,P=0.04）,TSA结果显示Meta分析的样本量还未达到期望信息量,为避免假阳性结果的出现,还需进一步扩大临床样本量来验证结果的可靠性;APRV能够缩短ARDS患者ICU住院时间（OR=-4.14,95%CI=-6.81~-1.47,P=0.002）;同时APRV能够改善ARDS患者肺部顺应性（MD=5.12,95%CI=0.33~9.91,P=0.04）;但2组在改善氧合及平均气道压方面并无差异。 结论APRV较CV能够降低ARDS患者住院病死率、缩短ARDS患者ICU住院时间、改善肺部顺应性;2组在改善患者氧合及平均气道压方面无差异。     

无创正压通气治疗创伤性湿肺的临床研究

目的 观察无创正压通气（NIPPV）治疗创伤性湿肺的疗效。方法 选择30例行无创正压通气治疗的创伤性湿肺患者为治疗组，24例未用NIPPV治疗的创伤性湿肺患者为对照组，通过对2组患者进行心电监测、血氧饱和度、呼吸频率、血气分析等指标的监测，比较2组患者呼吸频率和动脉血气参数、肺部病变吸收时间、气管插管率、ICU住院时间及预后。结果 30例创伤性湿肺患者经NIPPV治疗后动脉血气指标与临床表现明显改善（P〈0．01）；与对照组相比，NIPPV治疗组患者临床症状改善时间、肺部病变吸收时间、ICU住院时间明显缩短（P〈0．01），肺实变率显著减低（P〈0．05），但2组患者气管插管率和病死率差异却无显著性。结论 NIPPV通过调节压力支持与呼吸末正压水平，早期应用可明显改善创伤性湿肺患者病情及缩短病程，但并不能改善其预后。     

Uneven distribution of ventilation in acute respiratory distress syndrome

As in the adult with acute lung injury and acute respiratory distress syndrome, the use of lung-protective ventilation has improved outcomes for neonatal lung diseases. Animal models of neonatal respiratory distress syndrome and congenital diaphragmatic hernia have provided evidence that 'gentle ventilation' with low tidal volumes and 'open-lung' strategies of using positive end-expiratory pressure or high-frequency oscillatory ventilation result in less lung injury than do the traditional modes of mechanical ventilation with high inflating pressures and volumes. Although findings of retrospective studies in infants with respiratory distress syndrome, congenital diaphragmatic hernia, and persistent pulmonary hypertension of the newborn have been similar to those of the animal studies, prospective, randomized, controlled trials have yielded conflicting results. Successful clinical trial design in these infants and in children with acute lung injury/acute respiratory distress syndrome will require an appreciation of the data supporting the modern ventilator management strategies for infants with lung disease.     

High-frequency oscillatory ventilation in adult acute respiratory distress syndrome

Objective This study examined whether ARDS patients in whom predefined ventilator settings fail to maintain oxygenation and CO₂ removal can be safely transitioned to high-frequency oscillatory ventilation (HFOV), and whether HFOV use is efficacious.Design and setting Prospective observational study in the 14-bed intensive care unit of a university hospital.Patients and participants 42 patients with ARDS (APACHE II score 28 (IQR 24–37) and ventilation time prior HFOV 3.0 days (0.7–9.1).Measurements and results Gas exchange parameters and ventilator data were recorded before and during HFOV treatment (–12 h, –6 h, baseline, 10 min, 1 h, 6 h, 12 h, 24 h). Primary endpoints included: (a) P_aO₂/FIO₂ ratio 24 h after start of HFOV treatment or the last point of measurement if HFOV ended within the first 24 h; (b) HFOV-related complications. Post hoc analysis assessed the relationship between outcome and the response to HFOV, and between outcome and time of mechanical ventilation prior to HFOV. At baseline the median P_aO₂/FIO₂ ratio was 95 (IQR 62–129); after 24 h of HFOV the P_aO₂/FIO₂ ratio had increased significantly to 165 (88–225); only one patient developed a unilateral pneumothorax. Of the 42 patients 18 (43%) had died by day 30. Subset analyses showed a significantly higher 30-day mortality rate in patients with at least 3 days of mechanical ventilation prior to HFOV (64%) and in patients without oxygenation improvement after 24 h on HFOV (71%).Conclusions HFOV is an effective and safe method to ventilate ARDS patients. Failure to improve oxygenation within 24 h of HFOV is associated with high mortality.An editorial regarding this article can be found in the same issue