Transesophageal echocardiography in prone position during severe acute respiratory distress syndrome

Objective  

Patients with severe acute respiratory distress syndrome (ARDS) often require prolonged sessions of prone position (PP) because of refractory hypoxemia. Because of frequent hemodynamic impairment, use of transesophageal echocardiography (TEE) is also advocated during ARDS, but its implementation during PP has not been described yet. Our objective is to report the feasibility, tolerance, and therapeutic implications of TEE during PP for severe ARDS, and to compare it with TEE performed supine.     

俯卧位机械通气在急性呼吸窘迫综合症患者中的应用状况

急性呼吸窘迫综合征（acuterespiratorydistresssyndrome,ARDS）是指肺内、外严重疾病导致以肺毛细血管弥漫性损伤、通透性增强为基础,以肺水肿、透明膜形成和肺不张为主要病理变化,以进行性呼吸窘迫和难治性低氧血症为临床特征的急性呼吸衰竭综合征。ARDS是急性肺损伤（acutelunginjury,ALI）发展到后期的典型表现。该病起病急骤,发展迅猛,预后极差,     

Ventilation in the prone position in patients with acute lung injury/acute respiratory distress syndrome

PURPOSE OF REVIEW: To contrast the beneficial effects of the prone position on the lungs and the lack of proven clinical benefits on patient outcome. RECENT FINDINGS: Recent human investigations in acute respiratory distress syndrome have shown that the prone position was able to abolish tidal expiratory flow limitation, to improve oxygenation in the case of localized infiltrates, to allow for reducing positive end-expiratory pressure level, and to reduce lung stress and strain. Experimental studies have confirmed that distribution of ventilation was more homogeneous in the prone position but showed that positive end-expiratory pressure affected ventilation distribution differently in the prone and in the supine position. Experimental work has also shown that proning reduced strains imposed on the lungs and made them more homogeneously distributed. Finally, one recent large randomized controlled trial of systematic proning in hypoxemic patients showed no reduction in mortality but less ventilator-associated pneumonia incidence in the prone position group. SUMMARY: The prone position is not systematically used in hypoxemic patients. Patients who could benefit from prone position sessions are those with the most severe acute respiratory distress syndrome and those with dorsal lung infiltrates. Whether this can be translated into improvement in patient outcome has yet to be tested in clinical trials.     

急性呼吸窘迫综合征患者侧卧位通气与俯卧位通气的临床疗效观察

目的 评价侧卧位通气和俯卧位通气对急性呼吸窘迫综合征（ARDS）患者的临床疗效。并对两种体位通气方法进行对比观察。方法 将ICU2005年收治的23例ARDS患者随机分为两组，分别施行侧卧位通气（15例）和俯卧住通气（8例），监测仰卧位时，体位改变后1、2、4h及转复为仰卧位后1h的呼吸循环指标，并分别进行比较。结果 体位改变后1、2、4h及转复为仰卧住后1h，两组患者动脉血氧分压、氧舍指数均较仰卧位时升高（P〈0．05），心率、平均动脉压、气道峰压及动脉血二氧化碳分压与仰卧位时比较差异无统计学意义（P〉0．05）。以氧分压升高10mmHg为有效标准。治疗有效率侧卧位组73．3％，俯卧位组66．7％，两组比较差异无统计学意义（P〉0．05）。结论 作为ARDS机械通气治疗手段，侧卧位通气与俯卧位通气治疗的有效率接近。但侧卧位实施更容易，护理更方便。并发症少，值得临床进一步探讨。     

Use of the prone position in the management of acute respiratory distress syndrome.

The positioning of patients is usually within the domain of nursing practice, whether this is to achieve increased comfort or as a therapeutic intervention to avoid the occurrence of pressure sores. The use of the prone position to improve oxygenation, in the acute respiratory distress syndrome, has become increasingly popular in intensive care over the past decade (Thomas 1997). A systematic review was, therefore, undertaken to ascertain if the prone position did, in fact, improve oxygenation, leading to decreased mortality, or if the effects were merely transitory. Review findings indicate that use of the prone position does improve oxygenation, as measured by PaO2/FiO2 indices, and appears to reduce mortality. However, caution should be taken in applying these results to practice. First, the studies available for review demonstrated various methodological flaws. It is also apparent that untoward incidences associated with the prone position have yet to be investigated systematically.     

Efficacy of prone position in acute respiratory distress syndrome patients: A pathophysiology-based review

Acute respiratory distress syndrome (ARDS) is a syndrome with heterogeneous underlying pathological processes. It represents a common clinical problem in intensive care unit patients and it is characterized by high mortality. The mainstay of treatment for ARDS is lung protective ventilation with low tidal volumes and positive end-expiratory pressure sufficient for alveolar recruitment. Prone positioning is a supplementary strategy available in managing patients with ARDS. It was first described 40 years ago and it proves to be in alignment with two major ARDS pathophysiological lung models; the “sponge lung” - and the “shape matching” -model. Current evidence strongly supports that prone positioning has beneficial effects on gas exchange, respiratory mechanics, lung protection and hemodynamics as it redistributes transpulmonary pressure, stress and strain throughout the lung and unloads the right ventricle. The factors that individually influence the time course of alveolar recruitment and the improvement in oxygenation during prone positioning have not been well characterized. Although patients’ response to prone positioning is quite variable and hard to predict, large randomized trials and recent meta-analyses show that prone position in conjunction with a lung-protective strategy, when performed early and in sufficient duration, may improve survival in patients with ARDS. This pathophysiology-based review and recent clinical evidence strongly support the use of prone positioning in the early management of severe ARDS systematically and not as a rescue maneuver or a last-ditch effort.     

Improvement in oxygenation by prone position and nitric oxide in patients with acute respiratory distress syndrome

Objective: Inhaled nitric oxide (NO) and prone position improve arterial oxygenation in patients with the acute respiratory distress syndrome. This study was undertaken to assess the combined effects of NO and prone position in these patients. Design: Prospective clinical study. Setting: General intensive care service in a community teaching hospital. Patients: 14 mechanically ventilated adult patients with the acute respiratory distress syndrome (mean lung injury score 3.23 ± 0.27). Measurements and results: We measured hemodynamic and oxygenation parameters in the supine position and 2 h later in the prone position, before and during inhalation of 10 ppm NO. A positive response in oxygenation was defined as a ≥ 20 % increment in the arterial oxygen tension/fractional inspired oxygen ratio (PaO₂/FIO₂). In the prone position PaO₂/FIO₂ increased significantly (from 110 ± 55 to 161 ± 89 mmHg, p < 0.01) and venous admixture decreased (from 38 ± 12 to 30 ± 7 %, p < 0.01) compared to the supine position. Ten of the 14 patients were responders in the prone position. In the supine position, inhalation of NO improved oxygenation to a lesser extent, increasing PaO₂/FIO₂ to 134 ± 64 mmHg (p < 0.01) and decreasing venous admixture to 35 ± 12 %, (p < 0.01). Five of the 14 patients responded to NO inhalation supine and 8 of 14 responded prone (p = 0.22). The combination of NO therapy and prone positioning was additive in increasing PaO₂/FIO₂ (197 ± 92 mmHg) and decreasing venous admixture (27 ± 8 %) (p < 0.01). This combination also showed a positive oxygenation response on compared to the supine value without NO in 13 of the 14 patients (93 %). NO-induced changes in PaO₂/FIO₂ were correlated to changes in pulmonary vascular resistance only in the prone position. Conclusions: In patients with the acute respiratory distress syndrome, the combination of NO and prone position is a valuable adjunct to mechanical ventilation. Received: 15 June 1998 Final revision received: 13 October 1998 Accepted: 30 October 1998     

俯卧位通气联合呼气末正压治疗急性呼吸窘迫综合征家猪的疗效研究

目的 探讨俯卧位通气联合呼气末正压(PEEP)治疗急性呼吸窘迫综合征(ARDS)的疗效及其机制.方法 12头家猪静脉注射油酸建立ARDS模型,分为仰卧位组和俯卧位组,均给予0(ZEEP)、10(PEEP10)、20 cm H2O(PEEP20,1 cm H2O=0.098 kPa)PEEP的机械通气15 min,监测家猪血流动力学、肺气体交换和呼吸力学指标;处死动物观察肺组织病理学变化.结果 俯卧位组ZEEP、PEEP10时氧合指数(PaO2/FiO2)明显优于仰卧位组[ZEEP:(234.00±72.55)mm Hg比(106.58±34.93)mm Hg,PEEP10:(342.97±60.15) mm Hg比(246.80±83.69)mm Hg,1 mm Hg=0.133 kPa,P均<0.05];PEEP20时两组PaO2/FiO2差异无统计学意义(P>0.05).PEEP10时两组肺复张容积(RV)差异无统计学意义(P>0.05);但PEEP20时俯卧位组RV显著高于仰卧位组[(378.55±101.80)ml比(302.95±34.31)ml,P<0.05].两组间心率(HR)、平均动脉压(MAP)、心排血指数(CI)、呼吸系统顺应性(Cst)及动脉血二氧化碳分压(PaCO2)差异均无统计学意义(P均>0.05);仰卧位组背侧肺组织的肺损伤总评分明显高于俯卧位组[(12.00±1.69)分比(6.03±1.56)分,P<0.05].结论 俯卧位通气联合合适的PEEP可改善ARDS家猪氧合,并且不影响血流动力学和呼吸力学,肺组织损伤的重新分布可能是其机制之一.     

Long-term outcomes in survivors of acute respiratory distress syndrome ventilated in supine or prone position

Purpose  

The aim of this study is to examine long-term pulmonary function and quality of life in survivors of acute respiratory distress syndrome (ARDS) previously enrolled in a randomized multicenter trial testing prone compared with supine positioning (PSII study) at five Italian centers.     

俯卧位通气在ARDS中的临床应用价值探讨

目的探讨俯卧位通气（PPV）在急性呼吸窘迫综合征（ARDS）的临床应用价值。方法选取2006—05—2011—05江苏泗洪分金亭医院ICU收治的36例急性呼吸窘迫综合征患者．随机分为仰卧位组和俯卧位通气,两组均采用肺保护性通气策略,分别监测两组患者在充分镇静情况下初始仰卧位及俯卧位通气1h、2h、4h、6h后患者的动脉血氧分压（Pa02）、氧合指数（PaO。／Fi02）、pH值、动脉血二氧化碳分压（PaC02）、Sp02、心率（HR）、平均动脉压（MAP）、中心静脉压（CVP）等呼吸循环指标。结果俯卧位组在动脉血氧分压（PaOz）、氧合指数（PaO2／FiO2）、SpO2等呼吸指标方面较对照组明显改善（P〈0．05）,机械通气时间、住院时间和住院期问死亡率明显降低（P〈0．05）。而心率（HR）、平均动脉压（MAP）、中心静脉压（CVP）等循环指标较对照组无明显差异（P〉0．05）。结论俯卧位通气可明显改善ARDS患者的氧合状况,而对血流动力学影响不明显。     

Clinical guidelines for the use of the prone position in acute respiratory distress syndrome.

The mortality associated with acute respiratory distress syndrome (ARDS) remains high. It has been suggested that use of the prone position may improve survival. However, approaches to the use of the position are often haphazard. The development of clinical guidelines indicating the need for the prone position in ARDS and the process by which the manoeuvre may be performed were thought to be important for two reasons. Primarily, we sought to improve oxygenation through the use of the prone position whilst promoting patient safety. Secondly, we wished to standardize our approach to the use of the prone position and make recommendations for practice so that its use was no longer seen as a last resort in the management of ARDS. The process associated with the development of clinical guidelines is first described. This is followed by presentation of the clinical guidelines. Included in these are the criteria and discussion which indicate consideration of the prone position, potential exclusion criteria, pre-turn considerations, the turning technique, monitoring the effectiveness of the prone position, passive movements and limb positioning and, finally, documentation of the problems associated with use of the prone position. The paper concludes with discussion concerning the potential for future research in this area.     

俯卧位通气对急性肺损伤和急性呼吸窘迫综合征临床疗效影响的Meta分析

目的 系统评价俯卧位通气(PPV)对我国急性肺损伤(ALI)和急性呼吸窘迫综合征(ARDS)患者的短期临床疗效.方法 利用Cochrane系统评价法,全面检索2000年至2009年国内公开发表的所有ALI与ARDS患者PPV的临床研究资料.对纳入研究独立进行质量评价、资料提取、交叉核对后行Meta分析.结果 纳入研究8项共184例患者,PPV时患者动脉血氧分压(PaO2)、氧合指数(PaO2/FiO2)、呼吸系统总顺应性(C)均显著升高;动脉血二氧化碳分压(PaCO2)、中心静脉压(CVP)、呼吸道峰压(PIP)和呼吸系统总阻力(Raw)无显著的变化;心率(HR)与平均动脉压(MAP)显著升高. 结论 ALI与ARDS患者行PPV可增加呼吸系统总顺应性,改善患者低氧血症,相关临床研究结果基本一致.但因Meta分析的自身局限性,我们仍急需开展设计严谨的高质量大样本临床研究,明确PPV临床疗效、作用机制、科学的操作流程及PPV对患者血流动力学的影响等临床实际问题,改善国内ALI与ARDS患者的临床护理水平.     

Extended prone position ventilation in severe acute respiratory distress syndrome: A pilot feasibility study

Objectives

The aim of the study was to evaluate the safety of extended prone position ventilation (PPV) and its impact on respiratory function in patients with severe acute respiratory distress syndrome (ARDS).

Design

This was a prospective interventional study.

Setting

Patients were recruited from a mixed medical-surgical intensive care unit in a university hospital.

Patients

Fifteen consecutive patients with severe ARDS, previously unresponsive to positive end-expiratory pressure adjustment, were treated with PPV.

Intervention

Prone position ventilation for 48 hours or until the oxygenation index was 10 or less (extended PPV).

Results

The elapsed time from the initiation of mechanical ventilation to pronation was 35 ± 11 hours. Prone position ventilation was continuously maintained for 55 ± 7 hours. Two patients developed grade II pressure ulcers of small extent. None of the patients experienced life-threatening complications or hemodynamic instability during the procedure. The patients showed a statistically significant improvement in Pao₂/Fio₂ (92 ± 12 vs 227 ± 43, P < .0001) and oxygenation index (22 ± 5 vs 8 ± 2, P < .0001), reduction of PaCo₂ (54 ± 9 vs 39 ± 4, P < .0001) and plateau pressure (32 ± 2 vs 27 ± 3, P < .0001), and increment of the static compliance (21 ± 3 vs 37 ± 6, P < .0001) with extended PPV. All the parameters continued to improve significantly while they remained in prone position and did not change upon returning the patients to the supine position.

Conclusions

The results obtained suggest that extended PPV is safe and effective in patients with severe ARDS when it is carried out by a trained staff and within an established protocol. Extended PPV is emerging as an effective therapy in the rescue of patients from severe ARDS.     

俯卧位机械通气应用于老年急性呼吸窘迫综合征病人的效果评价

[目的]研究老年急性呼吸窘迫综合征病人俯卧位机械通气时的护理方法及效果。[方法]选择30例俯卧位机械通气老年病人,记录俯卧位前和俯卧位后1 h、2 h病人心率、呼吸、平均动脉压（MAP）和动脉血气变化。[结果]俯卧位通气治疗后1 h、2 h病人的血氧饱和度（SpO2）、动脉血氧分压（PaO2）均升高（P〈0.01）,心率、呼吸均减慢（P〈0.01）,而 MAP、动脉血二氧化碳分压（PaCO2）、pH 值的差异无统计学意义（P〉0.05）。[结论]对老年急性呼吸窘迫综合征病人应用俯卧位机械通气,可以提高老年病人的氧合状态,减慢心率、呼吸。     

俯卧位通气联合一氧化氮吸入对急性呼吸窘迫综合征患者氧合的影响

目的 评价俯卧位通气(PPV)联合NO吸入对急性呼吸窘迫综合征(ARDS)患者氧合的影响.方法 将我院重症医学科2008年9月至2011年1月收治的,应用最佳PEEP后仍需较高的吸入氧体积分数(FIO2≥60％)的21例ARDS患者,随机(随机数字法)分为三组进行对照研究.A组采取单纯NO吸入4h;B组采取俯卧位通气2h,2h后恢复仰卧位通气;C组采取俯卧位通气联合NO吸入2h,2h后恢复仰卧位通气并继续吸入NO.分别测三组患者治疗干预前、2h及4h氧合指数.统计学处理采用SPSS 13软件,数据以均数±标准差(-x±s)表示,组间比较用单因素方差分析,组内比较用t检验,P ＜0.05为差异有统计学意义.结果 与治疗干预前比较,三组患者2h后氧合指数均较前改善,但A组患者差异无统计学意义(P＞0.05),B组和C组患者差异有统计学意义(P ＜0.05);4h后A组和B组氧合指数跟治疗干预前比较无显著差异(P＞0.05),C组氧合指数仍保持改善(P＜0.05).结论 俯卧位通气可以有效地改善严重ARDS患者氧合,俯卧位通气联合NO吸入不但可以改善氧合,而且恢复仰卧位后能有效的维持氧合,因此卧位通气联合NO吸入的方法在改善氧合的同时能减少俯卧位通气时间.     

急性呼吸窘迫综合征病人俯卧位通气的实施与护理

[目的]总结俯卧位通气的原理、实施方法和护理,为ICU护士实施俯卧位通气提供理论、实践支持.[方法]对4例急性呼吸窘迫综合征(ARDS)病人实施了俯卧位通气,并以此为基础查阅了大量的国内外资料,给予病人精心的护理.[结果]俯卧位通气明显改善了肺的氧合功能,4例病人俯卧位通气后氧合明显改善,其中3例最终撤离呼吸机,1例因心跳呼吸停止抢救无效死亡.[结论]ICU护士在俯卧位通气的实施中,要懂得安全有效地转换病人的体位,提供适当的护理,尽早发现及处理可能出现的并发症.     

Recruitment maneuvers during prone positioning in patients with acute respiratory distress syndrome

OBJECTIVE: To evaluate the interaction of recruitment maneuvers and prone positioning on gas exchange and venous admixture in patients with early extrapulmonary acute respiratory distress syndrome ventilated with high levels of positive end-expiratory pressure. We hypothesized that a sustained inflation performed after 6 hrs of prone positioning would induce sustained improvement in oxygenation (Pao2/Fio2) and venous admixture. DESIGN: Prospective, interventional study. SETTING: Tertiary care, postoperative intensive care unit. PATIENTS: Fifteen patients with early extrapulmonary acute respiratory distress syndrome. INTERVENTIONS: After 6 hrs of prone positioning, a sustained inflation was performed with 50 cm H2O maintained for 30 secs. Data were recorded in supine position, after 6 hrs of prone positioning, at 3, 30, and 180 mins following the sustained inflation. MEASUREMENTS AND MAIN RESULTS: A response to prone positioning was observed in nine of 15 patients leading to an improvement of Pao2/Fio2 (147 +/- 37 torr vs. 225 +/- 77 torr, p = .005) and venous admixture (35.4 +/- 8.3% vs. 28.9 +/- 9.8%, p = .001). Six patients did not respond to prone positioning. Following the sustained inflation, the responders to prone positioning showed a further increase of Pao2/Fio2 and decrease of venous admixture at 3 mins (Pao2/Fio2, 225 +/- 77 torr vs. 368 +/- 90 torr, p = .018; venous admixture, 28.9 +/- 9.8% vs. 18.9 +/- 6.7%, p = .05). In all six nonresponders to prone positioning, an improvement of Pao2/Fio2 and venous admixture occurred at 3 mins following the sustained inflation (128 +/- 18 torr vs. 277 +/- 59 torr, p = .03; venous admixture, 34.2 +/- 6.0% vs. 23.8 +/- 6.3%, p = .05). The beneficial effects of the sustained inflation remained significantly elevated over 3 hrs in responders and nonresponders to prone positioning. CONCLUSION: In patients with early extrapulmonary acute respiratory distress syndrome, a sustained inflation performed after 6 hrs of prone positioning induced further and sustained improvement of oxygenation and venous admixture in both responders and nonresponders to prone positioning.