Prevalence and prognosis of shunting across patent foramen ovale during acute respiratory distress syndrome

Lactate and Echocardiography Before Veno-Venous Extracorporeal Membrane Oxygenation Support

BACKGROUND

Lactate has been recognised as a prognostic factor in several critical conditions. Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO) is a well-established therapy in patients with Acute Respiratory Disease Syndrome (ARDS) unresponsive to conventional therapy and echocardiography pre ECMO initiation has been recently reported to help in risk stratifying these patients.

METHODS

We assessed whether the detection of hyperlactataemia could be associated with the presence of left ventricle (LV) or right ventricle (RV) dysfunction in 121 consecutive patients with refractory ARDS.

RESULTS

The mortality rate was 42.9% (52/121). Higher dosages of norepinephrine and dobutamine were administered to non survivors (p=0.023 and p=0.047, respectively) who showed significantly higher levels of lactate (p=0.002). At echocardiography, non survivors showed higher values of systolic pulmonary artery pressure (sPAP) (p=0.05) and a higher incidence of RV dysfunction (as indicated by lower Tricuspid Annular Plane Excursion (TAPSE)) and RV dilatation (p=0.001). At multivariate logistic regression analysis, the following variables were independent predictors of death: body mass index (BMI) (OR: 0.914, 95%CI 0.857-0.975, p=0.006), RV dilatation (OR: 0.239, 95%CI 0.101-0.561, p=0.001) and lactate (OR: 1.292, 95%CI 1.015-1.645, p=0.038). Lactate values were directly correlated with the simplified acute physiology score (SAPS) II (r=0.38, p<0.001), while they showed an indirect correlation with left ventricular ejection fraction (LVEF) (r=-0.24, p=0.009) and TAPSE (r=-0.21, p=0.024).

CONCLUSIONS

In refractory ARDS, hyperlactataemia before VVV-ECMO identified a subset of patients at higher risk of death, being an independent predictor of in-Intensive Care Unit (ICU) mortality. Lactate values are mainly related to disease severity (as indicated by SAPS II) and haemodynamic impairment (as inferred by LVEF) and RV failure, as (indicated by TAPSE).

On the complexity of scoring acute respiratory distress syndrome: do not forget hemodynamics!

Acute respiratory distress syndrome (ARDS) remains associated with a poor outcome despite recent major therapeutic advances. Forecasting the outcome of patients suffering from such a syndrome is of a crucial interest and many scores have been proposed, all suffering from limits responsible for important discrepancies. Authors try to elaborate simple, routine and reliable scores but most of them do not consider hemodynamics yet acknowledged as a major determinant of outcome. This article aims at reminding the approach of scoring in ARDS and at deeply describing the most recently published one in order to highlight their main pitfall, which is to forget the hemodynamics.

Critical care ultrasonography in acute respiratory failure

Acute respiratory failure (ARF) is a leading indication for performing critical care ultrasonography (CCUS) which, in these patients, combines critical care echocardiography (CCE) and chest ultrasonography. CCE is ideally suited to guide the diagnostic work-up in patients presenting with ARF since it allows the assessment of left ventricular filling pressure and pulmonary artery pressure, and the identification of a potential underlying cardiopathy. In addition, CCE precisely depicts the consequences of pulmonary vascular lesions on right ventricular function and helps in adjusting the ventilator settings in patients sustaining moderate-to-severe acute respiratory distress syndrome. Similarly, CCE helps in identifying patients at high risk of ventilator weaning failure, depicts the mechanisms of weaning pulmonary edema in those patients who fail a spontaneous breathing trial, and guides tailored therapeutic strategy. In all these clinical settings, CCE provides unparalleled information on both the efficacy and tolerance of therapeutic changes. Chest ultrasonography provides further insights into pleural and lung abnormalities associated with ARF, irrespective of its origin. It also allows the assessment of the effects of treatment on lung aeration or pleural effusions. The major limitation of lung ultrasonography is that it is currently based on a qualitative approach in the absence of standardized quantification parameters. CCE combined with chest ultrasonography rapidly provides highly relevant information in patients sustaining ARF. A pragmatic strategy based on the serial use of CCUS for the management of patients presenting with ARF of various origins is detailed in the present manuscript.

Pulmonary Edema and Hypoxic Respiratory Failure

OBJECTIVES

The purpose of this chapter is to outline the causes, physiology, pathophysiology, and management strategies for hydrostatic and permeability pulmonary edema and hypoxic respiratory failure.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

The pulmonary parenchyma and vasculature are at high risk in conditions where injury occurs to the lung and or heart. A targeted approach that uses strategies that optimize the particular pathophysiology of the parenchyma and vasculature is required.

Cardiopulmonary Interactions

OBJECTIVES

The objectives of this review are to discuss the mechanisms by which respiration impacts cardiovascular function and vice versa, with an emphasis on the impact of these interactions in pediatric cardiac critical care.

DATA SOURCE

A search of MEDLINE was conducted using PubMed.

CONCLUSIONS

In the presence of underlying cardiac and respiratory disease, the interplay between these two systems is significant and plays a pivotal role in the pathophysiology of acute and chronic phases of a wide spectrum of diseases. An understanding of these relationships is essential to optimizing the care of critically ill patients.

Worsening Hypoxemia in the Face of Increasing PEEP: A Case of Large Pulmonary Embolism in the Setting of Intracardiac Shunt

Patient: Male, 40

Final Diagnosis: Patent foramen ovale

Symptoms: Dyspnea exertional • hemoptysis • shortness of breath

Medication: —

Clinical Procedure: Airway pressure release ventilation

Specialty: Critical Care Medicine

[Respiratory monitoring of pediatric patients in the Intensive Care Unit]

Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined.

The potential role and limitations of echocardiography in acute respiratory distress syndrome

Bedside use of Doppler echocardiography is being featured as a promising, clinically useful tool in assessing the pulmonary circulation in patients with acute respiratory distress syndrome (ARDS). The present review is aimed at summarizing the available evidence obtained with echocardiography on right ventricle (RV) function and pulmonary circulation in ARDS and to highlight the potential of this technique in clinical practice (only articles in English language were considered). According to the available evidence on echocardiographic findings, the following conclusions can be drawn: (a) echocardiography (transthoracic and transesophageal) has a growing role in the management ARDS patients mainly because of the strict interactions between the lung (and ventilation) and the RV and pulmonary circulation; (b) there may be a continuum of alterations in RV size and function and pulmonary circulation which may end in the development of acute cor pulmonale, probably paralleling ARDS disease severity; and (c) the detection of acute cor pulmonale should prompt intensivists to tailor their ventilatory strategy to the individual patient depending on the echocardiography findings. Bearing in mind the clinical role and growing importance of echocardiography in ARDS and the available evidence on this topic, we present a flow chart including the parameters to be measured and the timing of echo exams in ARDS patients. Despite the important progress that echocardiography has gained in the evaluation of patients with ARDS, several open questions remain and echocardiography still appears to be underused in these patients. A more systematic use of echocardiography (mainly through shared protocols) in ARDS could help intensivists to tailor the optimal treatment in individual patients as well as highlighting the limits and potential of this methodology in patients with ALI.

Postoperative rescue closure of patent foramen ovale in the clinical setting of acute hypoxemic respiratory failure and stroke following coronary artery bypass surgery

We describe a case of intraoperative diagnosis and successful deferred percutaneous closure of a patent foramen ovale (PFO) in the clinical setting of acute refractory hypoxemic respiratory failure and new-onset ischemic stroke in an elderly patient after coronary artery bypass graft. Perioperative morbidity (i.e. severe hypoxemia, worsening right ventricular dysfunction, and embolic stroke) that is potentially related to intraoperatively diagnosed PFO during cardiac surgery can complicate management in the Intensive Care Unit and perhaps affect the patient's outcome. Although the PFO closure can be challenging in the clinical setting of hypoxemic respiratory failure and stroke following cardiac surgery, it can be a reasonable perioperative option.

Management of right heart failure in the critically ill

Right ventricular failure complicates several commonly encountered conditions in the intensive care unit. Right ventricular dilation and paradoxic movement of the interventricular septum on echocardiography establishes the diagnosis. Right heart catheterization is useful in establishing the specific cause and aids clinicians in management. Principles of treatment focus on reversal of the underlying cause, optimization of right ventricular preload and contractility, and reduction of right ventricular afterload. Mechanical support with right ventricular assist device or veno-arterial extracorporeal membrane oxygenation can be used in select patients who fail to improve with optimal medical therapy.

Hemodynamic monitoring using a single-use indwelling transesophageal echocardiography probe in an unstable patient after open-heart surgery

Background

Hemodynamic monitoring is frequently needed in ventilated patients with unstable hemodynamics after open-heart surgery. Novel miniaturized single-use transesophageal echocardiographic probe has been scarcely used in this clinical setting.

Case presentation

A patient who underwent a scheduled open-heart surgery developed a ventilator-associated pneumonia and was referred to the intensive care unit for post-operative acute respiratory distress syndrome. Hemodynamic monitoring was performed with a single-use indwelling transesophageal echocardiography probe during 50 h. Initially, a contrast study depicted a patent foramen ovale with a right-to-left shunt. Nitric oxide was administered and positive end-expiration pressure was reduced. Subsequently, the patient became hemodynamically unstable and the identification of a localized tamponade due to compressive left atrial hematoma prompted reoperation.

Conclusions

The novel hemodynamic monitoring device described here appears valuable to help identifying severe post-operative complications and guide acute care.

Acute right ventricular dysfunction: real-time management with echocardiography

In critically ill patients, the right ventricle is susceptible to dysfunction due to increased afterload, decreased contractility, or alterations in preload. With the increased use of point-of-care ultrasonography and a decline in the use of pulmonary artery catheters, echocardiography can be the ideal tool for evaluation and to guide hemodynamic and respiratory therapy. We review the epidemiology of right ventricular failure in critically ill patients; echocardiographic parameters for evaluating the right ventricle; and the impact of mechanical ventilation, fluid therapy, and vasoactive infusions on the right ventricle. Finally, we summarize the principles of management in the context of right ventricular dysfunction and provide recommendations for echocardiography-guided management.

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

Introduction

Acute 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.

Methods

In 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.

Results

ACP 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.

Conclusions

In 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.

Effect of positive end-expiratory pressure on porcine right ventricle function assessed by speckle tracking echocardiography

Background

Right ventricle (RV) dysfunction and hypotension can be induced by high levels of positive end-expiratory pressure (PEEP). We sought to determine in an animal model if a novel ultrasound analysis technique: speckle tracking echocardiography (STE), could determine deterioration in RV function induced by PEEP and to compare this to a conventional method of RV analysis: fractional area change (FAC). STE is a sensitive, angle-independent method for describing cardiac deformation (‘strain’) and is particularly useful in analyzing RV function as has been shown in pulmonary hypertension cohorts.

Methods

Ten pigs, 40-90 kg, anaesthetized, fully mechanically ventilated at 6 ml/kg were subject to step-wise escalating levels of PEEP at two-minute intervals (0, 5, 10, 15, 20, 25 and 30cmH₂0). Intracardiac echocardiography was used to image the RV as transthoracic and transesophageal echocardiography did not give sufficient image quality or flexibility. Off-line STE analysis was performed using Syngo Velocity Vector Imaging (Seimens Medical Solutions Inc., USA). STE systolic parameters are RV free wall strain (RVfwS) and strain rate (RVfwSR) and the diastolic parameter RV free wall strain rate early relaxation (RVfwSRe)

Results

With escalating levels of PEEP there was a clear trend of reduction in STE parameters (RVfwS, RVfwSR, RVfwSRe) and FAC. Significant hypotension (fall in mean arterial blood pressure of 20 mmHg) occurred at approximately PEEP 15 cmH₂O. Comparing RVfwS, RVfwSR and RVfwSRe values at different PEEP levels showed a significant difference at PEEP 0 cmH₂O vs PEEP 10 cmH₂O and above. FAC only showed a significant difference at PEEP 0 cmH₂O vs PEEP 20 cmH₂O and above. 30% of pigs displayed dyssychronous RV free wall contraction at the highest PEEP level reached.

Conclusions

STE is a sensitive method for determining RV dysfunction induced by PEEP and deteriorated ahead of a conventional assessment method: FAC. RVfwS decreased to greater extent compared to baseline than FAC, earlier in the PEEP escalation process and showed a significant decrease before there was a clinical relevant decrease in mean arterial blood pressure. Studies in ICU patients using transthoracic echocardiography are warranted to further investigate the most sensitive echocardiography method for detecting RV dysfunction induced by mechanical ventilation.

Echocardiographic detection of transpulmonary bubble transit during acute respiratory distress syndrome

Background

Transpulmonary bubble transit (TPBT) detected with contrast echocardiography is reported as a sign of intrapulmonary shunt during cirrhosis or exercise in healthy humans. However, its physiological meaning is not clear during acute respiratory distress syndrome (ARDS). Our aim was to determine the prevalence, significance, and prognosis of TPBT detection during ARDS.

Methods

This was a prospective observational study in an academic medical intensive care unit in France. Two hundred and sixteen consecutive patients with moderate-to-severe ARDS underwent transesophageal echocardiography with modified gelatine contrast. Moderate-to-large TPBT was defined as right-to-left passage of at least ten bubbles through a pulmonary vein more than three cardiac cycles after complete opacification of the right atrium. Patients with intra-cardiac shunt through patent foramen ovale were excluded.

Results

The prevalence of moderate-to-large TPBT was 26% (including 42 patients with moderate and 15 with large TPBT). Patients with moderate-to-large TPBT had higher values of cardiac index and heart rate as compared to those without TPBT. There was no significant difference in PaO₂/FIO₂ ratio between groups, and TPBT was not influenced by end-expiratory positive pressure level in 93% of tested patients. Prevalence of septic shock was higher in the group with moderate-to-large TPBT. Patients with moderate-to-large TPBT had fewer ventilator-free days and intensive care unit-free days within the first 28 days, and higher in-hospital mortality as compared to others.

Conclusions

Moderate-to-large TPBT was detected with contrast echocardiography in 26% of patients with ARDS. This finding was associated with a hyperdynamic and septic state, but did not influence oxygenation.

Recent advances in mechanical ventilation in patients with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterised by different degrees of severity and different stages. Understanding these differences can help to better adapt the ventilatory settings to protect the lung from ventilator-induced lung injury by reducing hyperinflation or keeping the lung open when it is possible. The same therapies may be useful and beneficial in certain forms of ARDS, and risky or harmful at other stages: this includes high positive end-expiratory pressure, allowance of spontaneous breathing activity or use of noninvasive ventilation. The severity of the disease is the primary indicator to individualise treatment. Monitoring tools such as oesophageal pressure or lung volume measurements may also help to set the ventilator. At an earlier stage, an adequate lung protective strategy may also help to prevent the development of ARDS.

Oxygenation response to positive end-expiratory pressure predicts mortality in acute respiratory distress syndrome. A secondary analysis of the LOVS and ExPress trials

RATIONALE

Previous trials of higher positive end-expiratory pressure (PEEP) for acute respiratory distress syndrome (ARDS) failed to demonstrate mortality benefit, possibly because of differences in lung recruitability among patients with ARDS.

OBJECTIVES

To determine whether the physiological response to increased PEEP is associated with mortality.

METHODS

In a secondary analysis of the Lung Open Ventilation Study (LOVS, n = 983), we examined the relationship between the initial response to changes in PEEP after randomization and mortality. We sought to corroborate our findings using data from a different trial of higher PEEP (ExPress, n = 749).

MEASUREMENTS AND MAIN RESULTS

The oxygenation response (change in ratio of arterial partial pressure of oxygen to fraction of inspired oxygen: P/F) after the initial change in PEEP after randomization varied widely (median, 9.5 mm Hg; interquartile range, -16 to 47) and was only weakly related to baseline P/F or the magnitude of PEEP change. Among patients in whom PEEP was increased after randomization, an increase in P/F was associated with reduced mortality (multivariable logistic regression; adjusted odds ratio, 0.80 [95% confidence interval, 0.72-0.89] per 25-mm Hg increase in P/F), particularly in patients with severe disease (baseline P/F [less-than-or-equal-to] 150 mm Hg). Changes in compliance and dead space were not associated with mortality. These findings were confirmed by a similar analysis of data from the ExPress trial.

CONCLUSIONS

Patients with ARDS who respond to increased PEEP by improved oxygenation have a lower risk of death. The oxygenation response to PEEP might be used to predict whether patients will benefit from higher versus lower PEEP.

Modern Protective Ventilation Strategies: Impact upon the Right Heart

‘Protective ventilation’ for acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) is a major advance in intensive care medicine. However, components of protective ventilation expose the right heart to challenges. Acute cor pulmonale (ACP), patent foramen ovale (PFO) and right ventricular failure (RVF) are recognised complications that could potentially reduce the benefit of protective ventilation. We sought to determine the rates of ACP, PFO and RVF in critically ill adults undergoing protective ventilation with ARDS/ALI and to identify their impact on mortality and critical illness acuity. A comprehensive search of electronic databases including Medline (OVID, EmBase) and CINAHL (EBSCO) was undertaken, including Cochrane Library and international registries, between January 1991 and December 2011. A systematic review identified a total of 248 articles; 27 were reviewed in full and 22 studies were included. All 22 included studies were observational or quasi-experimental with no randomised, controlled trials available. ACP was present in 16–100%, PFO 1.3–22.0% and RVF 9.6–26.0%. Neither ACP nor PFO was associated with an adverse effect on mortality and ACP seemed reversible in survivors; however both ACP and PFO were associated with prolonged need for ICU support. RVF was variously associated with no increase in mortality to an odds ratio 5.1 for death in multivariate analysis. There was marked heterogeneity in the studies included, explaining the range of observed values. Recommendations for future research and practice were produced. Modern protective ventilation during ARDS has been shown to exert inconsistent effects on the right heart which may be of clinical significance. Further research is needed to determine these effects better.

The relationship between positive end-expiratory pressure and cardiac index in patients with acute respiratory distress syndrome

PURPOSE

The purpose of the study is to evaluate the association between positive end-expiratory pressure (PEEP) and cardiac index in patients with acute respiratory distress syndrome (ARDS).

METHODS

This is a secondary cross-sectional analysis of the multicenter randomized controlled Fluid and Catheter Treatment Trial enrolling adult patients within 48 hours of ARDS onset. Patients randomized to the pulmonary artery catheter arm, who had PEEP and cardiac index measurements performed within a short period of each other during the first 3 days of the FACTT study enrollment, were included in this study. Because FACTT had a 2 × 2 factorial design, half of the patients were in a "liberal fluids" study arm, and the other half were in a "conservative fluids" study arm.

RESULTS

The final study population (833 measurements or observations, in 367 patients) was comparable with the original overall FACTT study population. The mean PEEP level used was 8.2 ± 3.4 cm H2O, and the mean cardiac index was 4.2 ± 1.2 L/min per square meter. There was no association between PEEP and cardiac index in patients with ARDS, even when adjusted for Acute Physiology and Chronic Health Evaluation score, age, fluid study arm in FACTT, and sepsis.

CONCLUSION

In patients with ARDS who are managed with liberal or conservative fluid management protocols, PEEP is not associated with lower cardiac index.

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(I)O₂: 115 ± 39 with F(I)O₂: 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.

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.

Thermodilution and Fick cardiac outputs differ: impact on pulmonary hypertension evaluation

BACKGROUND

The relationship between thermodilution and indirect Fick cardiac output determination methods has not been well described.

OBJECTIVE

To describe the relationship between these two cardiac output determination methods in patients evaluated for pulmonary hypertension and to highlight potential clinical implications.

METHODS

A retrospective review of charts of all adult patients who underwent a right heart catheterization (RHC) between January 1, 2007 and November 10, 2010, and participated in the pulmonary hypertension program of the pulmonary division at an academic institution was conducted. For validation, the charts of all patients who underwent RHC during the same period within the cardiology division were reviewed.

RESULTS

A total of 198 patients underwent 213 RHCs, 79 (40%) of whom had pulmonary arterial hypertension, were included. Forty-three per cent of patients had >20% difference between thermodilution and Fick. The average difference (thermodilution - Fick ±SD) was -0.39±2.03 L⁄min (n=213; P=0.006). There was no significant difference in bias or variability between thermodilution and Fick among patients with tricuspid regurgitant jet velocity (TRJ) of <3 m⁄s versus those with TRJ >3 m⁄s (-0.41±2.10 L⁄min versus -0.36±1.93 L⁄min, respectively; P=0.87). In a multivariable analysis, the thermodilution-Fick difference increased with age (P=0.001).

DISCUSSION

The presence of such discrepancy in 36% of patients evaluated for heart failure and⁄or heart transplant validated the results. In total, 37% of the 1315 procedures (213 performed by pulmonologists and 1102 performed by cardiologists) had a difference of >20% between thermodilution and Fick.

CONCLUSION

Significant discrepancy exists between thermodilution and indirect Fick methods. This discrepancy potentially impacts pulmonary arterial hypertension prognostication and diagnosis, and is independent of TRJ.

Effect of different seated positions on lung volume and oxygenation in acute respiratory distress syndrome

RATIONALE

Lung volume available for ventilation is markedly decreased during acute respiratory distress syndrome. Body positioning may contribute to increase lung volume and partial verticalization is simple to perform. This study evaluated whether verticalization had parallel effects on oxygenation and end expiratory lung volume (EELV).

METHODS

Prospective multicenter study in 40 mechanically ventilated patients with ALI/ARDS in five university hospital MICUs. We evaluated four 45-min successive trunk position epochs (supine slightly elevated at 15°; semi recumbent with trunk elevated at 45°; seated with trunk elevated at 60° and legs down at 45°; back to supine). Arterial blood gases, EELV measured using the nitrogen washin/washout, and static compliance were measured. Responders were defined by a PaO₂/FiO₂ increase >20 % between supine and seated position. Results are median [25th-75th percentiles].

RESULTS

With median PEEP = 10 cmH₂O, verticalization increased lung volume but only responders (13 patients, 32 %) had a significant increase in EELV/PBW (predicted body weight) compared to baseline. This increase persisted at least partially when patients were positioned back to supine. Responders had a lower EELV/PBW supine [14 mL/kg (13-15) vs. 18 mL/kg (15-27) (p = 0.005)] and a lower compliance [30 mL/cmH₂O (22-38) vs. 42 (30-46) (p = 0.01)] than non-responders. Strain decreased with verticalization for responders. EELV/PBW increase and PaO₂/FiO₂ increase were not correlated.

DISCUSSION

Verticalization is easily achieved and improves oxygenation in approximately 32 % of the patients together with an increase in EELV. Nonetheless, effect of verticalization on EELV/PBW is not predictable by PaO₂/FiO₂ increase, its monitoring may be helpful for strain optimization.

Clinical review: Respiratory monitoring in the ICU - a consensus of 16

Monitoring plays an important role in the current management of patients with acute respiratory failure but sometimes lacks definition regarding which 'signals' and 'derived variables' should be prioritized as well as specifics related to timing (continuous versus intermittent) and modality (static versus dynamic). Many new techniques of respiratory monitoring have been made available for clinical use recently, but their place is not always well defined. Appropriate use of available monitoring techniques and correct interpretation of the data provided can help improve our understanding of the disease processes involved and the effects of clinical interventions. In this consensus paper, we provide an overview of the important parameters that can and should be monitored in the critically ill patient with respiratory failure and discuss how the data provided can impact on clinical management.

Goal-oriented respiratory management for critically ill patients with acute respiratory distress syndrome

This paper, based on relevant literature articles and the authors' clinical experience, presents a goal-oriented respiratory management for critically ill patients with acute respiratory distress syndrome (ARDS) that can help improve clinicians' ability to care for these patients. Early recognition of ARDS modified risk factors and avoidance of aggravating factors during hospital stay such as nonprotective mechanical ventilation, multiple blood products transfusions, positive fluid balance, ventilator-associated pneumonia, and gastric aspiration can help decrease its incidence. An early extensive clinical, laboratory, and imaging evaluation of “at risk patients” allows a correct diagnosis of ARDS, assessment of comorbidities, and calculation of prognostic indices, so that a careful treatment can be planned. Rapid administration of antibiotics and resuscitative measures in case of sepsis and septic shock associated with protective ventilatory strategies and early short-term paralysis associated with differential ventilatory techniques (recruitment maneuvers with adequate positive end-expiratory pressure titration, prone position, and new extracorporeal membrane oxygenation techniques) in severe ARDS can help improve its prognosis. Revaluation of ARDS patients on the third day of evolution (Sequential Organ Failure Assessment (SOFA), biomarkers and response to infection therapy) allows changes in the initial treatment plans and can help decrease ARDS mortality.

Patent foramen ovale: Its significance in anesthesia and intensive care: An illustrated case

Patent foramen ovale (PFO) is defined as a valve-like opening at the level of foramen ovale or between septum primum and secundum without evidence of the anatomical defect. Paradoxical embolism (PDE) is an embolus passing through a defect PFO leading to end-organ dysfunction. PDE in septic shock is not yet reported in the literature. A 49-year male presented to the emergency department with shortness of breath since one day and pain in the left side of the chest. Chest x0 -ray revealed middle-left lobe pneumonia with pleural effusion; he was started on Co-amoxiclav, and admitted to the ward. After 6 h, his chest pain suddenly significantly increased difficulty in breathing and his oxygen saturation dropped. X-ray of the chest showed left pneumothorax, chest drain was inserted and he was intubated. He became hemodynamically unstable with maximum ventilatory support and noradrenalin. On day 4, he was found to have new pansystolic murmur in the tricuspid area. An echocardiogram revealed global hypokinesia, two mobile thrombi in the right atrial cavity, and PFO. It was noticed that his right toe had blackish discoloration. An angiogram showed occlusion of the right superficial femoral artery and immediately an embolectomy. On day 11, he was transferred to the ward. PDE needs a high index of suspicion in septic shock patients with ARDS. PDE requires PEEP adjustment, early anticoagulation, and thromboprophylaxis.

Acute respiratory distress syndrome, mechanical ventilation, and right ventricular function

PURPOSE OF REVIEW

To reiterate the effects of positive pressure ventilation on right ventricular (RV) function in acute respiratory distress syndrome (ARDS), to explain in which conditions acute cor pulmonale (ACP) may worsen prognosis, and to define an approach to protection of the right ventricle.

RECENT FINDINGS

In unselected populations of ARDS patients, large studies have reported a 25% incidence of ACP. ACP has deleterious consequences, such as patent foramen ovale shunting and fewer ventilator-free days within the first 28 days. ACP may also worsen prognosis if not taken into account to adapt respiratory settings to RV function. ACP reflects the balance between lung recruitment and lung overdistension. To prevent ACP or to correct it, plateau pressure must be below 27-28 cmH2O, hypercapnia controlled, intrinsic positive end-expiratory pressure (PEEP) avoided, and a 'low' PEEP applied. Recent findings have suggested a negative correlation between the deleterious effect of PEEP on RV function and its ability to recruit the lung.

SUMMARY

Routine RV function assessment leads to an approach to mechanical ventilation in ARDS patients designed for protection of the right ventricle. This approach called 'RV protective approach' must be associated with prone positioning, a method of ventilation that improves RV function.

Acute respiratory distress syndrome: A clinical review

The acute respiratory distress syndrome (ARDS) is a complex disorder of heterogeneous etiologies characterized by a consistent, recognizable pattern of lung injury. Extensive epidemiologic studies and clinical intervention trials have been conducted to address the high mortality of this disorder and have provided significant insight into the complexity of studying new therapies for this condition. The existing clinical investigations in ARDS will be highlighted in this review. The limitations to current definitions, patient selection, and outcome assessment will be considered. While significant attention has been focused on the parenchymal injury that characterizes this disorder and the clinical support of gas exchange function, relatively limited focus has been directed to hemodynamic and pulmonary vascular dysfunction equally prominent in the disease. The limited available clinical information in this area will also be reviewed. The current standards for cardiopulmonary management of the condition will be outlined. Current gaps in our understanding of the clinical condition will be highlighted with the expectation that continued progress will contribute to a decline in disease mortality.