Changes of splanchnic perfusion after applying positive end expiratory pressure in patients with acute respiratory distress syndrome

Background:

Positive end-expiratory pressure (PEEP) improves oxygenation and can prevent ventilator- induced lung injury in patients with acute respiratory distress syndrome (ARDS). Nevertheless, PEEP can also induce detrimental effects by its influence on the cardiovascular system. The purpose of this study was to assess the effects of PEEP on gastric mucosal perfusion while applying a protective ventilatory strategy in patients with ARDS.

Materials and Methods:

Thirty-two patients were included in the study. A pressure–volume curve was traced and ideal PEEP, defined as lower inflection point + 2cmH₂O, was determined. Gastric tonometry was measured continuously (Tonocap). After baseline measurements, 10, 15 and 20cmH₂O PEEP and ideal PEEP were applied for 30 min each. By the end of each period, hemodynamics, CO₂ gap (gastric minus arterial partial pressures), and ventilatory measurements were taken.

Results:

PEEP had no effect on CO₂ gap (median [range], baseline: 18 [2–30] mmHg; PEEP 10: 18 [0–40] mmHg; PEEP 15: 17 [0–39] mmHg; PEEP 20: 16 [4–39] mmHg; ideal PEEP: 19 [9–39] mmHg; P = 0.19). Cardiac index also remained unchanged (baseline: 4.7 [2.6–6.2] l min⁻¹ m⁻²; PEEP 10: 4.4 [2.5–7] l min⁻¹ m⁻²; PEEP 15: 4.4 [2.2–6.8] l min⁻¹ m⁻²; PEEP 20: 4.8 [2.4–6.3] l min⁻¹ m⁻²; ideal PEEP: 4.9 [2.4–6.3] l min⁻¹ m⁻²; P = 0.09).

Conclusion:

PEEP of 10–20 cmH₂O does not affect splanchnic perfusion and is hemodynamically well tolerated in most patients with ARDS, including those receiving inotropic supports.     

A practical approach to adult acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a common disease encountered in hospitalized adult patients that, historically, has carried a very high mortality. This article reviews the clinical features and how pathophysiology informs the evidence-based management of ARDS.     

经鼻间歇正压通气防治早产儿呼吸窘迫综合征的临床研究

目的探讨经鼻间歇正压通气(NIPPV)在防治早产儿呼吸窘迫综合征(RDS)中的应用价值。方法选择2017年6月至2018年12月梧州市人民医院RDS早产儿90例,其中男性48例,女性42例;胎龄(29.03±0.58)周;出生体质量(996.91±98.52)g;病程(3.48±0.56)h;临床分级Ⅰ级58例,Ⅱ级32例;Apgar评分(6.85±1.06)分。依据随机数字表分为NIPPV组和持续气道正压通气(NCPAP)组,每组45例。NIPPV组给予NIPPV治疗,NCPAP组给予NCPAP治疗,若两组治疗后不能维持患儿生命体征则使用肺表面活性物质(PS)或行有创机械通气。结果NIPPV组和NCPAP组治疗12、24 h后和治疗结束时动脉血氧分压(PaO2)、氧合指数(OI)明显高于治疗前。NIPPV组治疗12、24 h后PaO2、OI明显高于NCPAP组,差异有统计学意义(P<0.05)。NIPPV组和NCPAP组治疗结束时PaO2、OI比较,差异无统计学意义(P>0.05);NIPPV组PS使用率(22.22%vs 44.44%)、有创通气率(17.78%vs 40.00%)、氧疗时间[(71.42±7.62)h vs(85.62±9.24)h]、有创通气时间[(46.78±5.32)h vs(55.27±6.14)h]、住院时间[(30.42±3.65)d vs(35.62±3.89)d]、并发症率(31.11%vs 53.33%)明显低于NCPAP组,差异有统计学意义(P<0.05)。结论NIPPV可有效改善RDS早产儿通气功能,有利于减少PS使用、有创通气及并发症,值得临床推广。     

Analysis of heart rate variability in individuals subjected to different positive end expiratory pressure levels using expiratory positive airway pressure

Introduction

The increase in the number of studies has led to greater security in the application of this method and the determination of its effectiveness in adults.. The purpose of the present study was to evaluate heart rate variability in healthy individuals submitted to different levels of positive expiratory pressure using an expiratory positive airway pressure (EPAP) device.

Material and methods

The study involved 27 healthy male individuals ranging in age from 20 to 35 years. Patient histories were taken and the subjects were submitted to a physical examination. The volunteers were monitored using the Polar 810s^® and submitted to the EPAP experiment. Analyses were performed on variables of the frequency domain. Sympathetic and parasympathetic bands and their relationship with sympathovagal response were also analyzed.

Results

The mean value of this variable was 526.89 (55.50) ms² in the first period, 2811.0 (721.10) ms² in the fourth period and 726.52 (123.41) ms² in the fifth period. Regarding the parasympathetic area, significant differences were detected when Periods 1 and 5 (no load) were compared with periods in which the individuals were subjected to the use of the therapy. Sympathetic and parasympathetic areas together, a significant difference was detected regarding the sympathetic/parasympathetic ratio in the comparison between Periods 1 and 4 (p < 0.01) as well as Periods 2 and 4 (p < 0.05).

Conclusions

The findings of the present study suggest that the therapeutic use of EPAP significantly alters the parameters of heart rate variability in the frequency domain, highlighting the importance of monitoring and care during the practice of EPAP.     

Acute respiratory distress syndrome: Pulmonary and extrapulmonary not so similar

Acute respiratory distress syndrome (ARDS) is characterized by acute onset respiratory failure with bilateral pulmonary infiltrates and hypoxemia. Current evidence suggests different respiratory mechanics in pulmonary ARDS (ARDSp) and extrapulmonary ARDS (ARDSexp) with disproportionate decrease in lung compliance in the former and chest wall compliance in the latter. Herein, we report two patients of ARDS, one each with ARDSp and ARDSexp that were managed using real-time esophageal pressure monitoring using the AVEA ventilator to tailor the ventilatory strategy.     

Isolation and phenotypic characteristics of microparticles in acute respiratory distress syndrome

Objective: To investigate the alterations of microparticles in acute respiratory distress syndrome (ARDS) in rats. Methods: 18 Wistar male rats were randomly divided into three groups: no intervention, sham (saline control) group and ARDS group (LPS induced). Blood was collected from abdominal aorta and microparticles were extracted through multiple rounds of centrifugation. Particles were analyzed by flow cytometry and transmission electron microscope. Results: The circulating concentration of total microparticles of rats with ARDS induced by lipopolysaccharide (LPS) did not change compared with other two groups. However, ARDS rats expressed higher concentration of leukocyte- and endothelium- derived microparticles in the three groups. Conclusion: Our results indicate that leukocyte and endothelial cell-derived particles may play an important role in ARDS. Thus it is important not only to monitor total microparticle levels but also the phenotypes, which may contribute to the prevention and early treatment of ARDS.     

Alveolar recruitment maneuvers in acute lung injury/acute respiratory distress syndrome

Mechanical ventilation can worsen lung damage in acute lung injury and acute respiratory distress syndrome. The use of low tidal volumes is one of the strategies that has been shown to reduce lung injury and improve outcomes in this situation. However, low tidal volumes may lead to alveolar derecruitment and worsening of hypoxia. Recruitment maneuvers along with positive end-expiratory pressure may help to prevent derecruitment. Although recruitment maneuvers have been shown to improve oxygenation, improved clinical outcomes have not been demonstrated. The optimal recruitment strategy and the type of patients who might benefit are also unclear. This review summarizes the impact of recruitment maneuvers on lung mechanics and physiology, techniques of application, and the clinical situations in which they may be useful.     

慢性酗酒与急性肺损伤/急性呼吸窘迫综合征

急性肺损伤/急性呼吸窘迫综合征(acute lung injury/accute respiratory distress syndrome,ALI/ARDS)是在非心源性疾病过程中.     

胸外科术后急性呼吸窘迫综合征的临床分析

目的：探讨胸外科术后急性呼吸窘迫综合征的防治措施。方法：回顾性分析21例开胸术后发生急性呼吸窘迫征患者的临床资料。结果：综合治疗为胸外科术后急性呼吸窘迫综合征的有效方法,有效率85．71％。治疗前后的生理指标改善明显。结论：早期和综合治疗对胸外科术后急性呼吸窘迫综合征具有重要意义。     

模式识别受体PRRs在急性肺损伤/急性呼吸窘迫综合征发病机制中的作用研究进展

急性肺损伤(ALI)/急性呼吸窘迫综合征(ARDS)是继发于肺内或全身的炎症反应过程,它由肺泡损伤导致并形成炎症性非心源性的肺水肿.模式识别受体(PRRs)参与先天免疫系统的激活,PRRs可以启动炎症信号级联反应,并释放促炎细胞因子.本综述对PRRs所包括的跨膜受体TLRs、胞质受体RLRs和NLRs以及下游炎症通路N...     

Incidence and outcome of acute lung injury and acute respiratory distress syndrome in the surgical intensive care unit

Introduction:

To determine the incidence and mortality of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in a cohort of patients with risk factors admitted to the Surgical Intensive Care Unit (SICU).

Materials and Methods:

A prospective observational inception cohort study with no intervention was conducted over 12 months. All patients with at least one known risk factor for ALI/ARDS admitted to the SICU were included in the study. The APACHE II severity of disease classification system scoring was performed within 1 h of admission. The ventilatory parameters and chest radiographs were recorded every 24 h. The P/F ratio, PEEP and Lung Injury Score were calculated each day until the day of discharge from the Intensive Care Unit or for the first 7 days of admission, whichever was shorter.

Results:

The incidence of ARDS among those who were mechanically ventilated was 11.4%. Sepsis was the most common (34.6%) etiology. Among those with risk factors, the incidence of ARDS was 30% and that of ALI was 32.7%. The mortality in those with ARDS was 41.8%. Those who develop ARDS had higher APACHE II scores, lower pH and higher PaCO₂ at admission compared with those who developed ALI or no lung injury.

Conclusion:

The incidence and mortality of ARDS was similar to other studies. Identifying those with risk factors for ARDS or mortality will enable appropriate interventional measures.     

肾移植术后巨细胞病毒性肺炎并发急性呼吸窘迫综合征中治疗方案分析

目的 探讨有创通气治疗、有创-无创通气治疗方案在肾移植术后巨细胞病毒性肺炎并发急性呼吸窘迫综合症（acute respiratory distress syndrome,ARDS）治疗中的应用价值.方法 将50例肾移植术后巨细胞病毒性肺炎并发ARDS患者随机分为两组,以接受常规有创通气治疗者为对照组,以接受有创-无创通气治疗者为观察组,每组25例,对比两组临床治疗效果.结果 两组治疗前动脉血氧分压（PaO2）、动脉二氧化碳分压（PaCO2）、动脉血Ph值（Ph）、心率（HR）及收缩压（SBP）比较无统计学意义（P＞0.05）,观察组治疗后死亡率明显低于对照组（P＜0.05）.经治疗7天后,两组以上指标均明显改善（P＜0.05）,两组改善程度比较无统计学意义（P＞0.05）.但观察组的首创通气时间、总通气时间、ICU住院时间及肺炎治疗时间均明显低于对照组（P＜0.05）.结论 有创-无创通气治疗方案可显著降低肾移植术后巨细胞病毒性肺炎并发ARDS患者死亡率,改善患者临床治疗效果,并可降低通气相关并发症.     

Celastrol attenuates impairments associated with lipopolysaccharide-induced acute respiratory distress syndrome (ARDS) in rats

Celastrol, a constituent from a traditional Chinese medicinal herb belonging to the family Celastraceae, has been shown to impart anti-inflammatory properties, in part, by inhibiting NF-κB activity and related induction of pro-inflammatory cytokine formation/release. The present study investigated the effects of celastrol in an animal model of acute respiratory distress syndrome (ARDS) induced by intratracheal administration of lipopolysaccharides (LPSs). Celastrol pre-treatment groups received celastrol by intraperitoneal injection on seven consecutive days before LPS treatment. In rats evaluated 24?h after LPS administration, oxygenation indices and lung injury were measured, as were levels of inflammatory cells and cytokines in isolated bronchoalveolar lavage fluid (BALF). Lung tissue expression of proteins involved in NF-κB and ERK/MAPK pathways were measured by Western blot analyses. Celastrol pre-treatments appeared to attenuate LPS-induced lung injury and inflammatory responses in the rats, including decreases in inducible aggregation\infiltration of inflammatory cells and production/release of pro-inflammatory cytokines into the lung airways. Celastrol appeared to also inhibit NF-κB activation, but had no effect on ERK/MAPK pathways in the LPS-induced ARDS. The results here thus indicated that celastrol pre-treatment could impart protective effects against LPS-induced ARDS, and that these effects may be occurring through an inhibition of induction of NF-κB signaling pathways.     

A study on the role of noninvasive ventilation in mild-to-moderate acute respiratory distress syndrome

Aim:There is sparse data on the role of noninvasive ventilation (NIV) in acute respiratory distress syndrome (ARDS) from India. Herein, we report our experience with the use of NIV in mild to moderate ARDS.Results:A total of 41 subjects (27 women, mean age: 30.9 years) were included in the study. Tropical infections followed by abdominal sepsis were the most common causes of ARDS. The use of NIV was successful in 18 (44%) subjects, while 23 subjects required intubation. The median time to intubation was 3 h. Overall, 19 (46.3%) deaths were encountered, all in those requiring invasive ventilation. The mean duration of ventilation was significantly higher in the intubated patients (7.1 vs. 2.6 days, P = 0.004). Univariate analysis revealed a lack of improvement in PaO₂/FiO₂ at 1 h and high baseline Acute Physiology and Chronic Health Evaluation II (APACHE II) as predictors of NIV failure.Conclusions:Use of NIV in mild to moderate ARDS helped in avoiding intubation in about 44% of the subjects. A baseline APACHE II score of >17 and a PaO₂/FiO₂ ratio <150 at 1 h predicts NIV failure.     

实验性急性呼吸窘迫综合征大鼠脑组织Gq蛋白-肌醇磷脂途径的变化

目的：探讨急性呼吸窘迫综合征（ARDS）大鼠脑组织中Gq蛋白-肌醇磷脂途径的变化及其作用。方法：健康雄性40只 Wistar 大鼠随机分为油酸组（OA组）和对照组。OA组由大鼠尾静脉注射OA 0.2 mL/kg （2 min内）复制ARDS模型,根据不同观测时点分为30 min、60 min、90 min和120 min 4个亚组。检测各组大鼠平均动脉血压（MABP）,血气,血浆和脑组织丙二醛含量及乳酸脱氢酶（LDH）、肌酸激酶（CK）活性。免疫印迹法检测各组大鼠脑组织中的Gq/11蛋白α活性亚基以及磷脂酶C （PLC）含量。结果：与对照组相比,OA组MABP、PaO2明显降低（P<0.05）。OA 90 min和120 min组血浆和脑组织的MDA含量和LDH活性明显升高（P<0.05）。OA组血浆CK活性较对照组明显升高（P<0.05）,脑组织CK活性在OA 60 min组升高（P<0.05）,随后在90 min和120 min组降低（P<0.05）。脑组织Gαq/11蛋白在OA 60 min、90 min和120 min组明显升高（P<0.05）。OA组脑组织PLC表达明显上调（P<0.05）。脑组织Gαq/11蛋白表达与PaO2 的改变呈负相关（r=-0.579,P<0.05）,与脑组织MDA变化呈正相关（r=0.538,P<0.05）,与脑组织LDH的变化亦呈正相关（r=0.624,P<0.05）。结论：ARDS时Gq蛋白-肌醇磷脂信号通路活性增强可能参与了脑组织的损伤。     

高呼气末正压加小潮气量治疗急性呼吸窘迫综合征

目的：评价高呼吸末正压（PEEP）加小潮气量治疗急性呼吸窘迫综合征（ARDS）的临床疗效和安全性。方法：选择2009年3月至2011年6月在中煤三建总医院重症监护病房（ICU）收治的30例ARDS患者,采用高PEEP加小潮气量（6ml／kg）及其它对症措施治疗。结果：30例患者经治疗动脉血气氧分压（PaO2）和氧合指数（PaO2／FiO2）均明显改善,治疗第2—5天动脉血氧分压（PaO2）改善最明显,第4、5天氧合指数（PaO2／FiO2）改善最为明显。患者均无气压伤发生,无心律失常发生,心率和平均动脉压无明显变化。中心静脉压随呼气末压增高而偏高,但对平均动脉压无显著影响。结论：高PEEP加小潮气量可增加肺泡气体交换,改善氧合。减少呼吸机相关性肺损伤。     

Prone position and pressure control inverse ratio ventilation in H1N1 patients with severe acute respiratory distress syndrome

Aim:To observe the 28 and 90 days mortality associated with prone position and assist control-pressure control (with inverse ratio) ventilation (ACPC-IRV).Results:At admission, among these six patients the mean tidal volume generated was about 376.6 ml which was in the range of 6–8 ml/kg predicted body weight. The mean lung injury score was 3.79, mean PaO₂ /FiO₂ ratio was 52.66 and mean oxygenation index was 29.83. The mean duration of ventilation was 9.4 days (225.6 h). The ICU length of stay was 11.16 days. There was no mortality at 28 and 90 days.Conclusion:Early prone combined with ACPC-IRV in H1N1 patients having severe ARDS can be used as a rescue therapy and it should be confirmed by large observational studies.     

Role of inflammatory mediators in the pathophysiology of acute respiratory distress syndrome

Inflammatory response leading to organ dysfunction and failure continues to be the major problem after injury in many clinical conditions such as sepsis, severe burns, acute pancreatitis, haemorrhagic shock, and trauma. In general terms, systemic inflammatory response syndrome (SIRS) is an entirely normal response to injury. Systemic leukocyte activation, however, is a direct consequence of a SIRS and if excessive, can lead to distant organ damage and multiple organ dysfunction syndrome (MODS). When SIRS leads to MODS and organ failure, the mortality becomes high and can be more than 50%. Acute lung injury that clinically manifests as acute respiratory distress syndrome (ARDS) is a major component of MODS of various aetiologies. Inflammatory mediators play a key role in the pathogenesis of ARDS, which is the primary cause of death in these conditions. This review summarizes recent studies that demonstrate the critical role played by inflammatory mediators such as tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, platelet activating factor (PAF), IL-10, granulocyte macrophage-colony stimulating factor (GM-CSF), C5a, intercellular adhesion molecule (ICAM)-1, substance P, chemokines, VEGF, IGF-I, KGF, reactive oxygen species (ROS), and reactive nitrogen species (RNS) in the pathogenesis of ARDS. It is reasonable to speculate that elucidation of the key mediators in ARDS coupled with the discovery of specific inhibitors would make it possible to develop clinically effective anti-inflammatory therapy.     

Right heart failure in acute respiratory distress syndrome: An unappreciated albeit a potential target for intervention in the management of the disease

Mortality from acute respiratory distress syndrome (ARDS) has gone down recently. In spite of this trend, the absolute numbers continue to be high even with improvements in ventilator strategies and a better understanding of fluid management with this disease. A possible reason for this could be an under-recognized involvement of the pulmonary vasculature and the right side of the heart in ARDS. The right heart is not designed to function under situations leading to acute elevations in afterload as seen in ARDS, and hence it decompensates. This brief review focuses on the magnitude of the problem, its detection in the intensive care unit, and recognizes the beneficial effect of prone-positioning on the pulmonary vasculature and right heart.     

NOD样受体蛋白3炎症小体在急性肺损伤/急性呼吸窘迫综合征中的作用机制研究进展

急性肺损伤/急性呼吸窘迫综合征(ALI/ARDS)是由多种非心源性肺内外因素引起的急性进行性呼吸衰竭,发病核心为过度放大或失控的炎症反应,目前没有特效的治疗药物.NOD样受体蛋白3(nucleotide-binding domain (NOD)-like receptor protein 3,NLRP3)炎症小体是细胞受到刺激时形成的多蛋白复合体,活化后导致细胞焦亡及IL-1β、IL-18等产生,在多种感染性、炎症性疾病中起重要作用.引起肺损伤的多种因素均可导致NLRP3炎症小体形成、活化,有研究提示,与ALI/ARDS中的过度炎症反应有关.因而深入研究NLRP3炎症小体在ALI/ARDS中的作用,对于进一步阐明ALI/ARDS的发病机制有重要意义,甚至有望成为治疗ALI/ARDS的新靶点.