Acute respiratory distress syndrome (ARDS)-associated acute cor pulmonale and patent foramen ovale: a multicenter noninvasive hemodynamic study

IntroductionAcute cor pulmonale (ACP) and patent foramen ovale (PFO) remain common in patients under protective ventilation for acute respiratory distress syndrome (ARDS). We sought to describe the hemodynamic profile associated with either ACP or PFO, or both, during the early course of moderate-to-severe ARDS using echocardiography.MethodsIn this 32-month prospective multicenter study, 195 patients with moderate-to-severe ARDS were assessed using echocardiography during the first 48 h of admission (age: 56 (SD: 15) years; Simplified Acute Physiology Score: 46 (17); PaO₂/FiO₂: 115 (39); V_T: 6.5 (1.7) mL/kg; PEEP: 11 (3) cmH₂O; driving pressure: 15 (5) cmH₂O). ACP was defined by the association of right ventricular (RV) dilatation and systolic paradoxical ventricular septal motion. PFO was detected during a contrast study using agitated saline in the transesophageal bicaval view.ResultsACP was present in 36 patients, PFO in 21 patients, both PFO and ACP in 8 patients and the 130 remaining patients had neither PFO nor ACP. Patients with ACP exhibited a restricted left ventricle (LV) secondary to RV dilatation and had concomitant RV dysfunction, irrespective of associated PFO, but preserved LV systolic function. Despite elevated systolic pulmonary artery pressure (sPAP), patients with isolated PFO had a normal RV systolic function. sPAP and PaCO₂ levels were significantly correlated.ConclusionsIn patients under protective mechanical ventilation with moderate-to-severe ARDS, ACP was associated with LV restriction and RV failure, whether PFO was present or not. Despite elevated sPAP, PFO shunting was associated with preserved RV systolic function.     

Acute cor pulmonale in massive pulmonary embolism: incidence, echocardiographic pattern, clinical implications and recovery rate

OBJECTIVE: The indications for the use of thrombolytic agents in massive pulmonary embolism (MPE) remain controversial and it has been suggested that transthoracic echocardiographic (TTE) examination, which is able to detect an associated right ventricular dysfunction, may cast light on this question. The goal of this study was to examine the incidence of acute cor pulmonale (ACP) in MPE, diagnosed on the basis of TTE criteria, its clinical implications and its resolution rate. DESIGN: Ten-year retrospective clinical study. SETTING: A medical and a coronary intensive care unit, university hospital. Patients: One hundred sixty-one patients with proven MPE. INTERVENTIONS: Acute cor pulmonale was defined as right ventricular end-diastolic area / left ventricular end-diastolic area (RVEDA/LVEDA) ratio in the long axis greater than 0.6 associated with septal dyskinesia in the short axis. ACP patients were divided into three groups according to circulatory status: 32 patients without circulatory failure constituted group 1, 32 patients with circulatory failure requiring inotropic support, but free of metabolic acidosis, constituted group 2 and 34 patients in whom circulatory failure was associated with metabolic acidosis (defined by a base deficit >5 mEq/l) constituted group 3. RESULTS: Acute cor pulmonale was present in 61% of patients with MPE and carried a 23% mortality, but this mortality was very different in stable patients (groups 1 and 2, 64 patients, 3% mortality) and in unstable patients (group 3, 34 patients, 59% mortality). A multivariate logistic regression analysis showed that the TTE results were not predictive of the risk of death. Conversely, the same analysis showed that the presence of metabolic acidosis was a powerful predictor of death. CONCLUSION: Because none of the TTE measurements in ACP could be used to stratify the severity of MPE, TTE was of no help in deciding on medical thrombolysis. However, depending on its severity, metabolic acidosis could justify a large cooperative study to assess the impact of thrombolytic therapy on mortality rate in this specific group.     

基于氧合指数指导下的进阶式肺康复训练结合俯卧位通气对重度老年ARDS患者心肺功能及血气指标的影响

目的 探究基于氧合指数指导下的进阶式肺康复训练结合俯卧位通气对重度老年急性呼吸窘迫综合征(ARDS)患者心肺功能及血气指标的影响.方法 选取128例重度老年ARDS患者,采用随机数字表法将患者分为对照组和观察组,每组64例,对照组给予俯卧位机械通气和肢体被动活动,观察组增加基于氧合指数指导下的进阶式肺康复训练,对比2组...     

Improvement of right ventricular performance by continuous positive airway pressure in adult respiratory distress syndrome

Continuous positive airway pressure (CPAP) appears to improve arterial oxygenation in patients with ARDS more than mechanical ventilation at the same level of PEEP due to a less detrimental effect on cardiac output. To determine the mechanisms responsible, we studied the changes in right and left ventricular performance induced by CPAP in seven such young patients who were able to maintain spontaneous ventilation. We measured cardiac output by thermodilution and biventricular ejection fraction by equilibrium gated blood-pool scintigraphy. Biventricular end-diastolic volumes were then calculated by dividing stroke volume by ejection fraction. During CPAP breathing, cardiac output fell about 9% due to a 9% fall in heart rate as oxygen consumption fell to the same extent (11%). The stroke volume remained unchanged with a decrease in both right ventricular end-systolic (−22%) and end-diastolic (−16%) volumes. Volume expansion to normalize cardiac output during CPAP restored right ventricular preload, while end-systolic volume remained decreased. This persistent decrease in end-systolic volume with CPAP associated with a fall in right ventricular end-systolic transmural pressure suggests that right ventricular afterload decreased with CPAP. In patients with ARDS treated with CPAP, we conclude that the stroke volume does not change because of a decrease in right ventricular afterload and even increases after normalizing right ventricular preload by volume expansion.     

Chemotherapy-induced late acute respiratory distress syndrome following right pneumonectomy for bronchogenic carcinoma

We report 2 patients who suffered late postoperative acute respiratory distress syndrome (ARDS) that was probably chemotherapy-induced. Both patients underwent neoadjuvant combination chemotherapy prior to right pneumonectomy for primary bronchogenic carcinoma, and then suffered ARDS in the remaining lung a few weeks after surgery. No evidence of infection or other specific ARDS etiologies could be found, whereas the bronchoalveolar lavage fluid cell differentiation and protein content suggested the permeability form of lung edema. Both patients had rapid clinical, functional, and radiologic improvement with high-dose corticosteroids. In the first patient the course was complicated by the development of a critical illness polyneuropathy with complete tetraplegia, but the patient recovered. The second patient died from septic shock 4 weeks after starting mechanical ventilation. The incidence of a chemotherapy-related ARDS in the remaining lung, occurring more than 4 weeks after extensive operations or after a pneumonectomy, is unknown. This kind of acute lung injury calls for particularly delicate treatments, the most potentially life-threatening complications being mainly associated with difficulties in ventilatory support and the high doses of corticosteroids required to rescue the remaining lung.     

Bedside echocardiographic evaluation of hemodynamics in sepsis: is a qualitative evaluation sufficient?

Objective Transesophageal echocardiography (TEE) has proven its efficiency in assessing hemodynamics in patients by its ability to evaluate cardiac function and fluid responsiveness. Classically, it requires quantitative measurements, whereas in routine practice TEE is used in our unit especially as a qualitative procedure. We assessed the accuracy of this qualitative central hemodynamic evaluation obtained by TEE at the bedside.Design and setting Prospective study conducted in a medical ICU between September 2004 and April 2005. All TEE examinations performed in consecutive patients hospitalized for septic shock and mechanically ventilated for an associated acute lung injury were eligible for evaluation. Intensivists trained in echocardiography were asked to classify (a) respiratory changes in the superior vena cava (SVC), (b) left ventricular (LV) systolic function, (c) right ventricular (RV) end-diastolic size, and (d) shape and kinetics of the interventricular septum (IVS). A post-hoc quantitative evaluation was then performed by a trained investigator unaware of the patients' status.Results We evaluated 83 examinations in 30 patients. Qualitative evaluation was easily able to distinguish patients with significant or nonsignificant SVC respiratory changes, normal, moderately or markedly depressed LV systolic function, and nondilated or dilated right ventricle. Acute cor pulmonale was also well recognized.Conclusion By its ability accurately to evaluate hemodynamic status qualitative TEE could be useful for intensivists in managing circulatory failure in septic shock, rendering the more time-consuming quantitative evaluation useless.     

Prevalence and prognostic value of acute cor pulmonale and patent foramen ovale in ventilated patients with early acute respiratory distress syndrome: a multicenter study

Purpose

We sought to determine the prevalence of and factors associated with acute cor pulmonale (ACP) and patent foramen ovale (PFO) at the early phase of acute respiratory distress syndrome (ARDS), and to assess their relation with mortality.

Methods

In this prospective multicenter study, 200 patients submitted to protective ventilation for early moderate to severe ARDS [PaO₂/F_IO₂: 115 ± 39 with F_IO₂: 1; positive end-expiratory pressure (PEEP): 10.6 ± 3.1 cmH₂O] underwent transthoracic (TTE) and transesophageal echocardiography (TEE) <48 h after admission. Echocardiograms were independently interpreted by two experts. Factors associated with ACP, PFO, and 28-day mortality were identified using multivariate regression analysis.

Results

TEE depicted ACP in 45/200 patients [22.5%; 95 % confidence interval (CI) 16.9–28.9 %], PFO in 31 patients (15.5 %; 95 % CI 10.8–21.3 %), and both ACP and PFO in 9 patients (4.5 %; 95 % CI 2.1–8.4 %). PFO shunting was small and intermittent in 27 patients, moderate and consistent in 4 patients, and large or extensive in no instances. PaCO₂ >60 mmHg was strongly associated with ACP [odds ratio (OR) 3.70; 95 % CI 1.32–10.38; p = 0.01]. No factor was independently associated with PFO, with only a trend for age (OR 2.07; 95 % CI 0.91–4.72; p = 0.08). Twenty-eight-day mortality was 23 %. Plateau pressure (OR 1.15; 95 % CI 1.05–1.26; p < 0.01) and air leaks (OR 5.48; 95 % CI 1.30–22.99; p = 0.02), but neither ACP nor PFO, were independently associated with outcome.

Conclusions

TEE screening allowed identification of ACP in one-fourth of patients submitted to protective ventilation for early moderate to severe ARDS. PFO shunting was less frequent and never large or extensive. ACP and PFO were not related to outcome.     

Right ventricular performance in patients with acute respiratory failure

To examine the right ventricular response to acute respiratory failure, serial studies of biventricular performance were analysed in 34 such patients, specifically detailing the role of associated underlying disease. During the initial study, the 34 patients with acute respiratory failure had a higher right ventricular end-diastolic volume than the control group (+21%), associated with a decrease in right ventricular ejection fraction, abnormalities which tended to return to normal values in the 15 survivors. In the 9 patients who died of refractory hypoxemia with severe pulmonary hypertension, the right ventricular dilation allowed to maintain stroke volume. In contrast, in 8 patients who died of septic shock, biventricular function was progressively altered (right and left ventricular ejection fraction= -37% and -35%). In 4 patients who died of cardiogenic shock (viral myocarditis), the cardiac function was the lowest (right and left ventricular ejection fraction= -59% and -60%). Only patients with acute respiratory failure associated with septic shock or viral myocarditis are unable to maintain their stroke volume.     

Right ventricular response to high-dose almitrine infusion in patients with severe hypoxemia related to acute respiratory distress syndrome

OBJECTIVE: To evaluate the effects of high-dose almitrine infusion on gas exchange and right ventricular function in patients with severe hypoxemia related to acute respiratory distress syndrome (ARDS). DESIGN: Prospective study. SETTING: Medicosurgical intensive care department (ten beds). PATIENTS: Nine patients with ARDS and severe hypoxemia (PaO2/FIO2 ratio, <150 torr [20 kPa]). INTERVENTION: High-dose almitrine infusion (16 microg/kg/min for 30 mins). MEASUREMENTS AND MAIN RESULTS: Gas exchange and hemodynamic parameters were recorded before and after almitrine infusion. Right ventricular function was evaluated by using a fast response thermistor pulmonary artery catheter that allowed measurement of right ventricular ejection fraction and calculation of right ventricular end-diastolic and end-systolic volumes. Almitrine did not significantly alter arterial oxygenation and intrapulmonary shunt. Almitrine increased mean pulmonary arterial pressure (MPAP) from 31 +/- 4 to 33 +/- 4 mm Hg (p < .05), pulmonary vascular resistance index from 353 +/- 63 to 397 +/- 100 dyne x sec/ cm5 x m2 (p < .05), and right ventricular end-systolic volume index from 71 +/- 22 to 77 +/- 21 mL/m2 (p < .05); almitrine decreased right ventricular ejection fraction from 36% +/- 7% to 34% +/- 8% (p < .05). Stroke volume index and cardiac index did not change. The almitrine-induced changes in right ventricular ejection fraction were closely correlated with the baseline MPAP (r2 = .71, p < .01). CONCLUSION: In patients with severe hypoxemia related to ARDS, high-dose almitrine infusion did not improve arterial oxygenation and impaired the loading conditions of the right ventricle. The decrease in right ventricular ejection fraction induced by almitrine was correlated with the baseline MPAP. Thus, high-dose almitrine infusion may be harmful in ARDS patients with severe hypoxemia and pulmonary hypertension.     

成人呼吸窘迫综合征（5例诊治体会）

报告我院普外科１９９３年１月～１９９４年１２月危重病人３７１例中发生成人呼吸窘迫综合征（ＡＲＤＳ）５例，发生率为１．３％，治愈４例，死亡１例。根据我们诊治体会提出，对可能发生ＡＲＤＳ的原发病病人，在围手术期应注意呼吸监测，做到早期发现，早期治疗。强调了救治ＡＲＤＳ病人必须与积极治疗原发病同步进行。本组治愈４例，均系采用经鼻导管高频喷射通气（ＨＦＪＶ）通气治疗，从而也证实了ＨＦＪＶ是抢救ＡＲＤＳ简便而有效的治疗方法。     

Two-dimensional echocardiographic evaluation of right ventricular size and contractility in acute respiratory failure

Right ventricular size and contractility were evaluated using two-dimensional echocardiography during the first days of respiratory support in 23 patients requiring mechanical ventilation for acute respiratory failure. Nine patients had normal echocardiographic right ventricular function, and nine other patients had a slightly enlarged right ventricle with normal systolic function. The remaining five patients had a severely enlarged right ventricle with abnormal contractile pattern. In these five patients, two-dimensional echocardiography also showed a reduction in left ventricular size suggesting detrimental ventricular interdependence. All 23 patients had normal left ventricular systolic function by two-dimensional echocardiography.     

Acute cor pulmonale in patients with acute respiratory distress syndrome: A comprehensive review

Acute respiratory distress syndrome (ARDS)-related acute cor pulmonale (ACP) is found in 8%-50% of all patients with ARDS, and is associated with adverse hemodynamic and survival outcomes. ARDS-related ACP is an echocardiographic diagnosis marked by combined right ventricular dilatation and septal dyskinesia, which connote simultaneous diastolic (volume) and systolic (pressure) overload respectively. Risk factors include pneumonia, hypercapnia, hypoxemia, high airway pressures and concomitant pulmonary disease. Current evidence suggests that ARDS-related ACP is amenable to multimodal treatments including ventilator adjustment (aiming for arterial partial pressure of carbon dioxide < 60 mmHg, plateau pressure < 27 cmH₂O, driving pressure < 17 cmH₂O), prone positioning, fluid balance optimization and pharmacotherapy. Further research is required to elucidate the optimal frequency and duration of routine bedside echocardiography screening for ARDS-related ACP, to more clearly delineate the diagnostic role of transthoracic echocardiography relative to transesophageal echocardiography, and to validate current and novel therapies.     

Extracorporeal membrane oxygenation for refractory, life-threatening, and herpes simplex virus 1-induced acute respiratory distress syndrome. Our experience and literature review

We report our first experience of treating an immunocompetent adult patient with acute respiratory distress syndrome (ARDS) due to type 1 herpes simplex (HSV1) pneumonitis, using extracorporeal membrane oxygenation (ECMO). Similar cases reported in literature are reviewed as well. The therapeutic options for this particular complication are discussed. Pneumonia caused by HSV1 is a rare finding in immunocompetent individuals; it occurs more often in immunosuppressed and ventilated patients. It is a severe illness; therefore, early diagnosis and initiation of treatment are imperative. Diagnosis is based on cytologic and histologic findings, viral cultures, or serologic methods. This condition can be reversible; however, often, it can progress into refractory ARDS with limited therapeutic options available. We demonstrate the causative role of HSV1 in refractory ARDS of a previously healthy 18-year-old man who presented to the intensive care unit with acute respiratory distress after a week of flulike syndrome. Due to severe hypoxemia and hypercarbia, the patient required mechanical ventilation and later emergent blood oxygenation with extracorporeal support. For the first time in this condition, we used venovenous ECMO management, to rest the lung, sustain blood oxygenation and end-organ oxygen delivery, and promote potential lung recovery. During ECMO and after our etiologic diagnosis, specific therapy was introduced. After viral negativization, corticosteroid therapy (Meduri protocol) was initiated. Extracorporeal membrane oxygenation allowed us to initiate therapy while maintaining end-organ oxygenation and support the patient until lung recovery. After 18 days of ECMO, our patient recovered completely. Near-normal lung structures and functions were documented on a chest x-ray/computed tomography, thoracic ultrasonography, and pulmonary functional tests at hospital discharge and at a 1-year follow-up. Data suggest that severe pulmonary involvement in HVS1 infection associated with septicemia/shock is a rare but often fatal in immunocompetent adult as well. We suggest that ECMO might be the selected treatment for severe refractory ARDS in this clinical scenario. It seems to be an effective and useful ultimate therapeutic strategy for preventing death and furthermore permitting near-full pulmonary function recovery.     

Respiratory index/pulmonary shunt relationship: quantification of severity and prognosis in the post-traumatic adult respiratory distress syndrome

The relationship between the respiratory index (RI = alveolar-arterial oxygen gradient [P(A-a)O2] normalized by PaO2) and the pulmonary shunt (Qsp/Qt) has been examined in 929 studies from 240 critically ill post-traumatic patients. Of these, 88 patients (443 studies) were individuals who developed post-traumatic adult respiratory distress syndrome (ARDS) and 152 were patients (486 studies) who did not develop ARDS. This study demonstrates that the RI to Qsp/Qt [RI/(Qsp/Qt)] relationship was significantly (p less than .0001) increased in patients who developed fatal ARDS compared with those who did not develop ARDS, or with those whose ARDS resolved. Because of the increased oxygen consumption (VO2) in ARDS patients in association with their severe limitations in gas exchange (RI) and increased Qsp/Qt, surviving ARDS patients had a significant increase in the cardiac index which resulted in a higher oxygen delivery to VO2 ratio. ARDS patients showed significant (p less than .0001) evidence of increased pulmonary vascular tone, correlated with the increase in the RI/(Qsp/Qt) relationship. In addition, those patients with high RI/(Qsp/Qt) also had increased right ventricular (RVSW) to left ventricular work (LVSW) ratios which were shown to be a direct function of the rise in RI. This increase in both RVSW/LVSW and RI/(Qsp/Qt) ratios was significantly (p less than .0001) correlated with an increased mortality. Thus, the RI/(Qsp/Qt) relationship, which can be obtained from arterial and mixed venous blood gases and saturations only, can be used to predict the severity of the ARDS process as well as important pulmonary vascular and right ventricular overload consequences.     

急性呼吸窘迫综合征患者机械通气和营养支持治疗37例分析

目的探讨急性呼吸窘迫综合征（ARDS）患者机械通气和营养支持治疗的临床特点及治疗效果。方法回顾性分析37例ARDS患者经机械通气和营养支持治疗的临床资料。结果37例ARDS机械通气患者1次脱机成功者30例,2次脱机成功者5例,3次脱机成功者2例。机械通气3—10d,无一例依赖呼吸机。全胃肠外营养（TPN）支持4-12d,TPN支持期间合并高血糖5例,消化道出血4例,肺感染、呼吸衰竭5例,无一例中心静脉置管并发症。结论机械通气和营养支持治疗ARDS临床效果较好。但应注意营养供给方式的选择。     

2018年：急性呼吸窘迫综合征与呼吸支持理念的进步

急性呼吸窘迫综合征（ARDS）是严重威胁人类健康的危重症，如何合理呼吸支持治疗避免呼吸机相关肺损伤仍是ARDS治疗面临的难题。2018年ARDS的诊治及呼吸支持理念仍在不断更新，ARDS的再分层和对治疗反应的再思考使得其治疗更为精准；肺保护性通气理念的进展让临床医师更为关注驱动压和膈肌功能的保护，然而，高流量氧疗并未能改善免疫抑制的呼吸衰竭患者的预后。今后基于病理生理和治疗反应性的研究会让我们能够更为精准地选择治疗措施进而改善患者的临床预后。     

Ventilator-associated pneumonia and ICU mortality in severe ARDS patients ventilated according to a lung-protective strategy

ABSTRACT: INTRODUCTION: Ventilator-associated pneumonia (VAP) may contribute to the mortality associated with acute respiratory distress syndrome (ARDS). We aimed to determine the incidence, outcome, and risk factors of bacterial VAP complicating severe ARDS in patients ventilated by using a strictly standardized lung-protective strategy. METHODS: This prospective epidemiologic study was done in all the 339 patients with severe ARDS included in a multicenter randomized, placebo-controlled double-blind trial of cisatracurium besylate in severe ARDS patients. Patients with suspected VAP underwent bronchoalveolar lavage to confirm the diagnosis. RESULTS: Ninety-eight (28.9%) patients had at least one episode of microbiologically documented bacterial VAP, including 41 (41.8%) who died in the ICU, compared with 74 (30.7%) of the 241 patients without VAP (P = 0.05). After adjustment, age and severity at baseline, but not VAP, were associated with ICU death. Cisatracurium besylate therapy within 2 days of ARDS onset decreased the risk of ICU death. Factors independently associated with an increased risk to develop a VAP were male sex and worse admission Glasgow Coma Scale score. Tracheostomy, enteral nutrition, and the use of a subglottic secretion-drainage device were protective. CONCLUSIONS: In patients with severe ARDS receiving lung-protective ventilation, VAP was associated with an increased crude ICU mortality which did not remain significant after adjustment.     

Daily changes of the area of density in the dependent lung region – evaluation using transesophageal echocardiography

OBJECTIVE: To evaluate the daily changes of the area of density using transesophageal echocardiography (TEE) in acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) patients. DESIGN: Retrospective observational study. SETTING: General ICU in a university hospital. PATIENTS: Fifteen patients with ARDS or ALI who underwent TEE examination for more than 5 days. MEASUREMENTS: Densities in the lower left lung region were observed through the descending aorta by TEE. Daily changes of the area of density were evaluated. The areas of density estimated by TEE were compared with those obtained by computed tomography (CT). The relation between the area of density and PaO(2)/FIO(2)was calculated. RESULTS: The area of density in the dependent lung region measured by TEE was 11.1+/-5.7 cm(2) (mean +/- SD) at the mid-esophageal position. The area of density in ARDS patients changed daily from 12.0+/-2.8 cm(2) to 8.5+/-6.7 cm(2).The areas of density evaluated using TEE in the left lung correlated significantly with those estimated using CT ( r=0.72, p<0.01). In addition, we found a significant correlation between PaO(2)/FIO(2) and the area of density estimated by TEE ( r=-0.53, p<0.05). CONCLUSION: Using TEE, we could evaluate daily changes of the area of density in the dependent lung region in the intensive care situation. The areas of density in ARDS patients changed from day to day following the changes of oxygenation.     

Prevalence and prognosis of cor pulmonale during protective ventilation for acute respiratory distress syndrome

Purpose

Pulmonary vascular dysfunction is common during acute respiratory distress syndrome (ARDS), but there is controversy concerning prevalence and prognosis of cor pulmonale during protective ventilation for ARDS.

Methods

This was a prospective observational study in an academic medical intensive care unit in France. Two hundred and twenty-six consecutive patients with moderate to severe ARDS (Berlin definition) ventilated with plateau pressure limited at 30 cmH₂O (mean PEEP of 8.8 ± 3.6 cmH₂O) underwent transesophageal echocardiography (TEE) within the first 3 days after the diagnosis of ARDS. Cor pulmonale was defined as a dilated right ventricle associated with septal dyskinesia.

Results

Cor pulmonale was detected in 49 patients (prevalence of 22 %; 95 % confidence interval, 16–27 %). Multivariate logistic regression identified infectious causes of lung injury and higher driving pressures as independent factors associated with cor pulmonale. Patients with cor pulmonale exhibited a higher incidence of shock (need for vasoactive drug) at the time of TEE and were more often managed with prone positioning and/or nitric oxide as adjunctive therapy for severe hypoxemia during ARDS course. The 28-day mortality rate was significantly higher in the group with cor pulmonale (60 vs. 36 %, p < 0.01). Multivariate logistic regression identified McCabe and Jackson class, lung injury not related to pneumonia, aspiration, or sepsis, lactic acidosis, driving pressure, and cor pulmonale as independent risk factors for 28-day mortality.

Conclusion

Cor pulmonale occurrence is not negligible in ARDS patients ventilated with airway pressure limitation. Cor pulmonale was associated with sepsis and higher values of driving pressure and was an independent risk factor for 28-day mortality in our series.     

Prone-position ventilation induces sustained improvement in oxygenation in patients with acute respiratory distress syndrome who have a large shunt

OBJECTIVES: Prone-position ventilation (PPV) induces acute improvement in oxygenation in many patients with acute respiratory distress syndrome (ARDS), with some maintaining their oxygenation even after they were returned to the supine position, but it is unclear what clinical factors determine the sustained oxygenation benefit. We hypothesized that patients with ARDS who have a larger shunt would have a better acute and sustained oxygenation response to PPV. DESIGN: Prospective, nonrandomized interventional study. SETTING: Medical and surgical intensive care units, university tertiary care center. PATIENTS: Twenty-two consecutive patients, with ARDS with an average PaO2/FiO2 of 94, were administered PPV for 12 hrs followed by supine-position ventilation for 2 hrs. MEASUREMENTS: Hemodynamic and gas exchange variables were monitored. The shunt was measured as venous admixture at an FiO2 of 1.0, and compliances of the respiratory system, lung, and chest wall were measured by the esophageal balloon technique before PPV, during PPV, and during subsequent supine-position ventilation. MAIN RESULTS: Fourteen patients (64%) responded to PPV, with PaO2/FiO2 increasing by > or =20. These changes were associated with a decrease in chest wall compliance. Responders had significantly shorter time from ARDS to PPV, a lower baseline PaO2/FiO2, and a higher venous admixture. All responders maintained the improvement in oxygenation and had a greater respiratory system compliance after returning to the supine position. Time from ARDS to PPV and baseline lung injury score were negatively associated, whereas chest wall compliance, heart rate, and PaCO2 were positively associated with sustained improvement in oxygenation. CONCLUSIONS: PPV induced acute and sustained improvement in oxygenation in many patients with ARDS. The sustained improvement is more significant if PPV is administered early to patients with a larger shunt and a more compliant chest wall. Measuring venous admixture and chest wall compliance before PPV may help select a subgroup of patients with ARDS who may benefit the most from PPV.