Long-term follow-up of cardiac arrest survivors: Protocol of the DESAC (Devenir des survivants d'Arrets Cardiaques) study, a French multicentric prospective cohort

Background

While the short-term prognosis of cardiac arrest patients - nearly 250,000 new cases per year in Europe - has been extensively studied, less is known regarding the mid and long-term outcome of survivors.

Objective

The aim of the DESAC study is to describe mid- and long-term survival rate and functional status of cardiac arrest survivors, and to assess the influence of pre and intra hospital therapeutic strategies on these two outcomes.

Methods

Between Jul 2015 and Oct 2018, adult patients over 18 years who were discharged alive from any intensive care units (public and private hospitals) in the Ile-de-France area (Paris and suburbs, France) after a non-traumatic cardiac arrest were screened for participation in this multicentric study. Survivors were included after they signed (or the proxies) an informed consent before discharge during initial hospitalisation. We calculated that including 600 patients in total would allow an 80% power to demonstrate a 2 years survival rate difference of 10% between patients who did and those who did not receive therapeutic hypothermia after resuscitation. Pre- and in-hospital data related to the circumstances surrounding the event and to the therapeutic interventions (such as cardio-pulmonary resuscitation, defibrillation, emergent coronary revascularization, neuroprotective therapeutics) were collected. After discharge, patients were interviewed at 3 months, 6 months and every year thereafter for a minimum follow-up of 26 months and a maximum follow-up of 48 months. Information on vital status, occurrence of cardiovascular events, medications and a comprehensive assessment of the functional status (qualitive of life as assessed by the Short-Form General Health Survey (SF36) scale, activities of daily living (ADL) scale, neurological Cerebral Performance Categories (CPC) and Overall Performance Categories (OPC) scales, socio-professional activities) were collected at follow-up interviews.

Discussion

The DESAC study should provide important information regarding several dimensions of the mid and long-term prognosis of cardiac arrest survivors and on the benefit (and potentially harm) of early therapeutic strategies.

Differential Effect of Targeted Temperature Management Between 32 °C and 36 °C Following Cardiac Arrest According to Initial Severity of Illness: Insights From Two International Data Sets

BACKGROUND

Recent guidelines have emphasized actively avoiding fever to improve outcomes in patients who are comatose following resuscitation from cardiac arrest (ie, out-of-hospital cardiac arrest). However, whether targeted temperature management between 32 °C and 36 °C (TTM32-36) can improve neurologic outcome in some patients remains debated.

RESEARCH QUESTION

Is there an association between the use of TTM32-36 and outcome according to severity assessed at ICU admission using a previously derived risk score?

STUDY DESIGN AND METHODS

Data prospectively collected in the Sudden Death Expertise Center (SDEC) registry (France) between May 2011 and December 2017 and in the Resuscitation Outcomes Consortium Continuous Chest Compressions (ROC-CCC) trial (United States and Canada) between June 2011 and May 2015 were used for this study. Severity at ICU admission was assessed through a modified version of the Cardiac Arrest Hospital Prognosis (mCAHP) score, divided into tertiles of severity. The study explored associations between TTM32-36 and favorable neurologic status at hospital discharge by using multiple logistic regression as well as in tertiles of severity for each data set.

RESULTS

A total of 2,723 patients were analyzed in the SDEC data set and 4,202 patients in the ROC-CCC data set. A favorable neurologic status at hospital discharge occurred in 728 (27%) patients in the French data set and in 1,239 (29%) patients in the North American data set. Among the French data set, TTM32-36 was independently associated with better neurologic outcome in the tertile of patients with low (adjusted OR, 1.63; 95% CI, 1.15-2.30; P = .006) and high (adjusted OR, 1.94; 95% CI, 1.06-3.54; P = .030) severity according to mCAHP at ICU admission. Similar results were observed in the North American data set (adjusted ORs of 1.36 [95% CI, 1.05-1.75; P = .020] and 2.42 [95% CI, 1.38-4.24; P = .002], respectively). No association was observed between TTM32-36 and outcome in the moderate groups of the two data sets.

INTERPRETATION

TTM32-36 was significantly associated with a better outcome in patients with low and high severity at ICU admission assessed according to the mCAHP score. Further studies are needed to evaluate individualized temperature control following out-of-hospital cardiac arrest.

Risk factors for surgical site infection after pancreatic surgery: a better postoperative antibiotic strategy is possible

INTRODUCTION

Pancreatic surgery is associated with high morbidity, mainly due to infectious complications, so many centres use postoperative antibiotics (ATBpo) for all patients. However, antibiotic regimens vary according to local practices. The aims of this study were to describe the occurrence of surgical site infection (SSI) and ATBpo prescription after pancreatic surgery, and to determine the risk factors of postoperative SSI, in order to better define the clinical indications for ATBpo in this context.

PATIENTS AND METHODS

All patients undergoing scheduled major pancreatic surgery from January 2007 to November 2018 were included in this retrospective study. Patients were classified into four groups according to SSI and routine ATBpo prescription: SSI+/ATBpo+, SSI-/ATBpo+, SSI+/ATBpo- and SSI-/ATBpo-. In addition, risk factors (fever and pre-operative biliary prosthesis) associated with the occurrence of SSI and ATBpo were analysed using a logistic regression model.

RESULTS

Data from 149 patients (115 pancreaticoduodenectomies and 34 splenopancreatectomies) were analysed. Thirty (20.1%) patients experienced SSI and 42 (28.2%) received ATBpo. No difference was found in routine ATBpo prescription between patients with and without SSI (26.7% vs 28.6%, respectively; P=0.9). Amongst the 107 patients who did not receive routine ATBpo, 85 (79.4%) did not develop an SSI. In-hospital mortality did not differ between infected and uninfected patients (7% vs 2%, respectively; P=0.13). The occurrence of postoperative fever differed between SSI+ and SSI- patients (73.3% vs 34.2%, respectively; P<0.001), while the prevalence of pre-operative biliary prosthesis was similar (37.9% vs 26.7%, respectively; P=0.3).

CONCLUSION

Non-routine ATBpo after major pancreatic surgery resulted in 85 (56%) patients being spared unnecessary antibiotic treatment. This suggests that routine ATBpo prescription could be excessive, but further studies are needed to confirm such antibiotic stewardship. Fever appears to be a relevant clinical sign for individual-based prescription, but the presence of a biliary prosthesis does not.

Systematic review and literature appraisal on methodology of conducting and reporting critical-care echocardiography studies: a report from the European Society of Intensive Care Medicine PRICES expert panel

Background

The echocardiography working group of the European Society of Intensive Care Medicine recognized the need to provide structured guidance for future CCE research methodology and reporting based on a systematic appraisal of the current literature. Here is reported this systematic appraisal.

Methods

We conducted a systematic review, registered on the Prospero database. A total of 43 items of common interest to all echocardiography studies were initially listed by the experts, and other “topic-specific” items were separated into five main categories of interest (left ventricular systolic function, LVSF n = 15, right ventricular function, RVF n = 18, left ventricular diastolic function, LVDF n = 15, fluid management, FM n = 7, and advanced echocardiography techniques, AET n = 17). We evaluated the percentage of items reported per study and the fraction of studies reporting a single item.

Results

From January 2000 till December 2017 a total of 209 articles were included after systematic search and screening, 97 for LVSF, 48 for RVF, 51 for LVDF, 36 for FM and 24 for AET. Shock and ARDS were relatively common among LVSF articles (both around 15%) while ARDS comprised 25% of RVF articles. Transthoracic echocardiography was the main echocardiography mode, in 87% of the articles for AET topic, followed by 81% for FM, 78% for LVDF, 70% for LVSF and 63% for RVF. The percentage of items per study as well as the fraction of study reporting an item was low or very low, except for FM. As an illustration, the left ventricular size was only reported by 56% of studies in the LVSF topic, and half studies assessing RVF reported data on pulmonary artery systolic pressure.

Conclusion

This analysis confirmed sub-optimal reporting of several items listed by an expert panel. The analysis will help the experts in the development of guidelines for CCE study design and reporting.

[Cor pulmonale]

Cor pulmonale is a disease of the heart characterised by dilatation of the right ventricle and paradoxical movement of the interventricular septum. The diagnosis depends on echocardiography even if pulmonary artery catheterisation suggests it. It is secondary to pulmonary disease or a disorder of the pulmonary circulation. These two mechanisms, which are often connected, involve pulmonary hypertension as the origin of a systolic and diastolic overload of the right ventricle, which then leads to the alterations of its structure and performance. Acute cor pulmonale is usually secondary to an acute respiratory distress syndrome or to a pulmonary embolism but it can also be seen in primary lactic acidosis, a vaso-occlusive crisis in a patient with sickle cell anaemia, severe acute asthma, and entry of air or injected crushed tablets into the circulation. Chronic cor pulmonale is the terminal stage of pulmonary hypertension. Clinically these patients are dyspnoeic with signs of chronic right heart failure. They should have an echocardiogram confirming the cardiac involvement. Certain precipitating factors, such as infection of any origin, have been reported, leading to acute on chronic cor pulmonale that has a particularly high mortality.

Extracorporeal cardiopulmonary resuscitation in out-of-hospital cardiac arrest: a registry study

Aims

Out-of-hospital cardiac arrest (OHCA) without return of spontaneous circulation (ROSC) despite conventional resuscitation is common and has poor outcomes. Adding extracorporeal membrane oxygenation (ECMO) to cardiopulmonary resuscitation (extracorporeal-CPR) is increasingly used in an attempt to improve outcomes.

Methods and results

We analysed a prospective registry of 13 191 OHCAs in the Paris region from May 2011 to January 2018. We compared survival at hospital discharge with and without extracorporeal-CPR and identified factors associated with survival in patients given extracorporeal-CPR. Survival was 8% in 525 patients given extracorporeal-CPR and 9% in 12 666 patients given conventional-CPR (P = 0.91). By adjusted multivariate analysis, extracorporeal-CPR was not associated with hospital survival [odds ratio (OR), 1.3; 95% confidence interval (95% CI), 0.8–2.1; P = 0.24]. By conditional logistic regression with matching on a propensity score (including age, sex, occurrence at home, bystander CPR, initial rhythm, collapse-to-CPR time, duration of resuscitation, and ROSC), similar results were found (OR, 0.8; 95% CI, 0.5–1.3; P = 0.41). In the extracorporeal-CPR group, factors associated with hospital survival were initial shockable rhythm (OR, 3.9; 95% CI, 1.5–10.3; P = 0.005), transient ROSC before ECMO (OR, 2.3; 95% CI, 1.1–4.7; P = 0.03), and prehospital ECMO implantation (OR, 2.9; 95% CI, 1.5–5.9; P = 0.002).

Conclusions

In a population-based registry, 4% of OHCAs were treated with extracorporeal-CPR, which was not associated with increased hospital survival. Early ECMO implantation may improve outcomes. The initial rhythm and ROSC may help select patients for extracorporeal-CPR.

La Haute Autorité de santé prive les patients en choc septique de vasopressine : une perte de chance !

Le choc septique demeure un grave problème de santé publique en raison de son incidence élevée et du taux élevé de morbimortalité. Les recommandations internationales concernant la prise en charge hémodynamique font une place à la vasopressine en seconde ligne chez les patients « réfractaires » à la noradrénaline. L’arginine-vasopressine a obtenu l’Autorisation européenne de mise sur le marché le 31 mai 2018. Ce médicament est disponible dans de nombreux pays. Pourtant, la Haute Autorité de santé vient de refuser l’inscription de l’arginine-vasopressine dans cette indication. Cet article met en lumière la discordance d’appréciation de l’évidence scientifique entre la Haute Autorité de santé et les nombreuses sociétés savantes qui ont endossé les recommandations de la Surviving Sepsis Campaign.

Practical approach to diastolic dysfunction in light of the new guidelines and clinical applications in the operating room and in the intensive care

There is growing evidence both in the perioperative period and in the field of intensive care (ICU) on the association between left ventricular diastolic dysfunction (LVDD) and worse outcomes in patients. The recent American Society of Echocardiography and European Association of Cardiovascular Imaging joint recommendations have tried to simplify the diagnosis and the grading of LVDD. However, both an often unknown pre-morbid LV diastolic function and the presence of several confounders-i.e., use of vasopressors, positive pressure ventilation, volume loading-make the proposed parameters difficult to interpret, especially in the ICU. Among the proposed parameters for diagnosis and grading of LVDD, the two tissue Doppler imaging-derived variables e' and E/e' seem most reliable. However, these are not devoid of limitations. In the present review, we aim at rationalizing the applicability of the recent recommendations to the perioperative and ICU areas, discussing the clinical meaning and echocardiographic findings of different grades of LVDD, describing the impact of LVDD on patients' outcomes and providing some hints on the management of patients with LVDD.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Experts' opinion on management of hemodynamics in ARDS patients: focus on the effects of mechanical ventilation

RATIONALE

Acute respiratory distress syndrome (ARDS) is frequently associated with hemodynamic instability which appears as the main factor associated with mortality. Shock is driven by pulmonary hypertension, deleterious effects of mechanical ventilation (MV) on right ventricular (RV) function, and associated-sepsis. Hemodynamic effects of ventilation are due to changes in pleural pressure (Ppl) and changes in transpulmonary pressure (TP). TP affects RV afterload, whereas changes in Ppl affect venous return. Tidal forces and positive end-expiratory pressure (PEEP) increase pulmonary vascular resistance (PVR) in direct proportion to their effects on mean airway pressure (mPaw). The acutely injured lung has a reduced capacity to accommodate flowing blood and increases of blood flow accentuate fluid filtration. The dynamics of vascular pressure may contribute to ventilator-induced injury (VILI). In order to optimize perfusion, improve gas exchange, and minimize VILI risk, monitoring hemodynamics is important.

RESULTS

During passive ventilation pulse pressure variations are a predictor of fluid responsiveness when conditions to ensure its validity are observed, but may also reflect afterload effects of MV. Central venous pressure can be helpful to monitor the response of RV function to treatment. Echocardiography is suitable to visualize the RV and to detect acute cor pulmonale (ACP), which occurs in 20-25 % of cases. Inserting a pulmonary artery catheter may be useful to measure/calculate pulmonary artery pressure, pulmonary and systemic vascular resistance, and cardiac output. These last two indexes may be misleading, however, in cases of West zones 2 or 1 and tricuspid regurgitation associated with RV dilatation. Transpulmonary thermodilution may be useful to evaluate extravascular lung water and the pulmonary vascular permeability index. To ensure adequate intravascular volume is the first goal of hemodynamic support in patients with shock. The benefit and risk balance of fluid expansion has to be carefully evaluated since it may improve systemic perfusion but also may decrease ventilator-free days, increase pulmonary edema, and promote RV failure. ACP can be prevented or treated by applying RV protective MV (low driving pressure, limited hypercapnia, PEEP adapted to lung recruitability) and by prone positioning. In cases of shock that do not respond to intravascular fluid administration, norepinephrine infusion and vasodilators inhalation may improve RV function. Extracorporeal membrane oxygenation (ECMO) has the potential to be the cause of, as well as a remedy for, hemodynamic problems. Continuous thermodilution-based and pulse contour analysis-based cardiac output monitoring are not recommended in patients treated with ECMO, since the results are frequently inaccurate. Extracorporeal CO2 removal, which could have the capability to reduce hypercapnia/acidosis-induced ACP, cannot currently be recommended because of the lack of sufficient data.

Right ventricular failure in acute lung injury and acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a clinical entity involving not only alveolar lesions but also capillary lesions, both of which have deleterious effects on the pulmonary circulation, leading to constant pulmonary hypertension and to acute cor pulmonale (ACP) in 20-25% of patients ventilated with a limited plateau pressure (Pplat). Considering the poor prognosis of patients suffering from such acute right ventricular (RV) dysfunction, RV protection by appropriate ventilatory settings has become a crucial issue in ARDS management. The goal of this review is to emphasize the importance of analyzing RV function in ARDS, using echocardiography, in order to limit RV afterload. Any observed acute RV dysfunction should lead physicians to consider a strategy for RV protection, including strict limitation of Pplat, diminution of positive end-expiratory pressure (PEEP) and control of hypercapnia, all goals achieved by prone positioning.

Reversal of refractory septic shock with drotrecogin alpha (activated)

OBJECTIVE

We previously reported that early continuous veno-venous hemodiafiltration (CVVHDF) enables rapid identification of a subgroup of patients with "refractory" septic shock and a 100% risk of death. The objective of this study was to investigate whether early administration of drotrecogin alpha (activated) (DrotAA) to this selected subgroup of septic patients at extremely high risk of death would significantly improve prognosis.

METHOD

Prospective observational study in a medical intensive-care unit of a University Hospital. Twenty-three patients with refractory septic shock were included. "Refractory" shock was defined as persistent circulatory failure despite adequate circulatory support, associated with persisting lactic acidosis despite early CVVHDF. Response to CVVDHF was assessed after 6 h of this continuous procedure. Patients selected by this strategy received DrotAA infusion for four days.

RESULTS

The 28-day mortality rate of the 23 patients was 39%. No difference was observed at inclusion between survivors and nonsurvivors. In patients who finally survived, 12 h of DrotAA infusion was associated with a significant decrease in lactic acidosis and in norepinephrine dose.

CONCLUSION

DrotAA therapy was associated with unexpectedly high 28-day survival in patients with "refractory" septic shock.

Weaning from mechanical ventilation

Weaning covers the entire process of liberating the patient from mechanical support and from the endotracheal tube. Many controversial questions remain concerning the best methods for conducting this process. An International Consensus Conference was held in April 2005 to provide recommendations regarding the management of this process. An 11-member international jury answered five pre-defined questions. 1) What is known about the epidemiology of weaning problems? 2) What is the pathophysiology of weaning failure? 3) What is the usual process of initial weaning from the ventilator? 4) Is there a role for different ventilator modes in more difficult weaning? 5) How should patients with prolonged weaning failure be managed? The main recommendations were as follows. 1) Patients should be categorised into three groups based on the difficulty and duration of the weaning process. 2) Weaning should be considered as early as possible. 3) A spontaneous breathing trial is the major diagnostic test to determine whether patients can be successfully extubated. 4) The initial trial should last 30 min and consist of either T-tube breathing or low levels of pressure support. 5) Pressure support or assist-control ventilation modes should be favoured in patients failing an initial trial/trials. 6) Noninvasive ventilation techniques should be considered in selected patients to shorten the duration of intubation but should not be routinely used as a tool for extubation failure.

[Negative D-dimers and peripheral pulmonary embolism]

The measurement of D-dimers is a recent addition to the diagnostic strategy of pulmonary embolism and has been shown to be a valuable tool with excellent sensitivity. However, there have been rare reports of patients with pulmonary embolism but negative D-dimer tests. The object of this study was to study patients with pulmonary embolism but negative D-dimers and to compare them with a population of patients with pulmonary embolism and raised D-dimers. One hundred and fifty consecutive patients admitted for pulmonary embolism were included in this study. All underwent measurement of D-dimers (normal <500 ng/ml) by an ELISA technique. The data of clinical examination and complementary investigations were analysed with respect to the D-dimers result. The sensitivity of raised D-dimers for pulmonary embolism was 96% (6 patients had results <500 ng/ml). The finding of chest pain was statistically greater in the group with negative D-dimers (p=0.01). In these cases, the emboli were all distal (p=0.0003), the average Miller index was significantly lower than in patients with high D-dimers (p=0.04) and the diagnostic value of ultrasound investigations (echocardiography, ultrasonography of lower limb veins) was less (p<0.0001). The authors conclude that measurement of D-dimers by the ELISA method may be non-diagnostic in distal pulmonary embolism and one explanation could be the less extensive thromboembolic process. In cases with negative D-dimers, a strong clinical suspicion of pulmonary embolism should lead to the request for further investigations.

The issue of dynamic hyperinflation in acute respiratory distress syndrome patients

Dynamic hyperinflation is produced by a diffuse expiratory flow limitation impairing exhalation under mechanical ventilation. It constitutes a serious clinical problem in patients exhibiting bronchial asthma or chronic obstructive pulmonary disease, when mechanical ventilation is required. But this phenomenon may also complicate respiratory support in acute respiratory distress syndrome (ARDS) patients. The presence of diffuse airflow limitation in ARDS patients has sometimes been noticed in the past, but its consequences have only recently been emphasised in a dynamic study, using bedside recording of flow/volume loops during respiratory support. More recently, by recording systematically a prolonged expiration, the current authors have observed a localised airflow limitation in a majority of ARDS patients, constituting another potential factor of dynamic hyperinflation under respiratory support. In the same report, the current authors' have emphasised the impact of this limitation on the shape of the pressure/volume loop. At a time when increasing respiratory support is proposed to improve carbon dioxide clearance in acute respiratory distress syndrome submitted to protective ventilation, dynamic hyperinflation may become a major clinical problem in this setting.

[Incidence of acute cor pulmonale and deep venous thrombosis in acute pulmonary embolism]

OBJECTIVE

Ultrasounds are a useful tool when looking for indirect evidence in favor of pulmonary embolism. The aim of this study was to determine the incidence of acute cor pulmonale and deep venous thrombosis revealed by ultrasonographic techniques in a population of patients presenting with pulmonary embolism.

METHODS

96 consecutive patients with a mean (+/- SD) age of 65 +/- 15 years, admitted to our hospital for pulmonary embolism were included in this study. The diagnosis of pulmonary embolism was made either by spiral computed tomography or selective pulmonary angiography. Each patient subsequently underwent both trans-thoracic echocardiography and venous ultrasonography. The diagnostic criterion used for defining acute cor pulmonale by echocardiography was the right to left ventricular end-diastolic area ratio over (or equal to) 0.6. Diagnosis of deep venous thrombosis was supported by the visualization of thrombi or vein incompressibility and/or the absence of venous flow or loss of flow variability by venous ultrasonography.

RESULTS

Using ultrasounds, an acute cor pulmonale was found in 63% of our patients while 79% were found to have deep venous thrombosis and 92% of the patients had either acute cor pulmonale or deep venous thrombosis or both. All of the patients with proximal pulmonary embolism had acute cor pulmonale and/or deep venous thrombosis. The presence of acute cor pulmonale on echocardiography was significantly higher in patients with proximal pulmonary embolism (p < 0.0001).

CONCLUSION

This study emphasizes the potential value of ultrasonographic techniques in the diagnosis of acute pulmonary embolism.

Influence of superior vena caval zone condition on cyclic changes in right ventricular outflow during respiratory support

BACKGROUND

Adequate fluid resuscitation in critically ill patients undergoing mechanical ventilation remains a difficult challenge, and diastolic and systolic right ventricular (RV) changes produced by positive airway pressure are important to consider in an individual patient with inadequate circulatory adaptation during respiratory support. We hypothesized that insufficient thoracic vena cava filling, predisposing to inspiratory collapse (zone 2 condition), may transiently affect RV outflow.

METHODS

We measured beat-to-beat superior vena caval diameter and Doppler RV outflow during a routine transesophageal echocardiographic examination in 22 patients undergoing mechanical ventilation, all of whom required hemodynamic monitoring, and we calculated a collapsibility index for the superior vena cava as maximal expiratory diameter minus minimal inspiratory diameter, divided by maximal expiratory diameter.

RESULTS

In 15 patients (group 1), the collapsibility index was low (17 +/- 7%) and was associated with a moderate inspiratory decrease in RV outflow (25 +/- 17%). However, in seven patients (group 2), we observed a high collapsibility index (71 +/- 7%), which was associated with a major inspiratory decrease in RV outflow (69 +/- 14%) combined with a reduced pulmonary artery flow period. A rapid volume expansion, only performed on group 2, markedly and significantly reduced both the collapsibility index (15 +/- 12%) and the inspiratory decrease in RV outflow (31 +/- 20%).

CONCLUSION

A major inspiratory decrease in RV outflow associated with a reduced pulmonary artery flow period in a patient undergoing mechanical ventilation reflected a high collapsibility index of the thoracic vena cava, suggesting a zone 2 condition, and may be corrected by blood volume expansion.

Gelatinase expression in pulmonary arteries during experimental pulmonary hypertension

Structural remodelling of pulmonary vessels is an important feature of pulmonary hypertension (PH), which reflects distal artery muscularization and matrix remodelling. The matrix metalloproteinases (MMPs) are involved in extracellular matrix turnover and hence, in smooth muscle cell migration and endothelial cell migration and proliferation. Among the MMPs, gelatinases (MMP-2 and MMP-9) can degrade basement membrane components and promote cell proliferation and migration. This study evaluated gelatinases in pulmonary vessels during progressive PH in two rat models: exposure to hypoxia or monocrotaline. Zymography of tissue homogenates revealed an association of progression of hypoxic PH with a time-dependent increase in gelatinase MMP-2 activity, specific to pulmonary vessels. Increased MMP-2 activity was also found 30 days postmonocrotaline. Reverse transcription polymerase chain reaction demonstrated upregulation of MMP-2 messenger ribonucleic acid. Immunolocalization showed MMP-2 throughout the pulmonary vasculature, from the trunk to the distal vessels, with strong staining of the intima, media and adventitia. MMP-2 was found in its active form and gelatinolytic activity was correlated to PH severity. Activity localization by in situ zymography corroborated with the immunolocalization findings. In conclusion, the authors demonstrated that matrix metalloproteinase-2 activity is increased in pulmonary vessels during progression of pulmonary hypertension, probably as a result of involvement in the matrix turnover associated with vascular remodelling during pulmonary hypertension.

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.

Acute cor pulmonale in acute respiratory distress syndrome submitted to protective ventilation: incidence, clinical implications, and prognosis

CONTEXT

The incidence of acute cor pulmonale (ACP), a frequent and usually lethal complication of acute respiratory distress syndrome (ARDS) during traditional respiratory support, has never been re-evaluated since protective ventilation gained acceptance.

OBJECTIVE

We performed a longitudinal transesophageal echocardiographic (TEE) study to determine whether this incidence, and its severe implications for prognosis, might have changed in our unit as we altered respiratory strategy.

DESIGN

Prospective open clinical study.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Seventy-five consecutive ARDS patients given respiratory support with airway pressure limitation (plateau pressure < or =30 cm H2O).

INTERVENTIONS

ACP was defined as a ratio of right ventricular end-diastolic area to left ventricular end-diastolic area in the long axis >0.6 associated with septal dyskinesia in the short axis during TEE examination.

RESULTS

Normal right ventricular function was present in 56 patients, whereas right ventricular dysfunction was observed in 19 patients after 2 days of respiratory support. ACP was associated with pulmonary artery hypertension, increased heart rate, and decreased stroke index. Significant impairment of left ventricular diastolic function was also seen. All echo-Doppler abnormalities were reversible in patients who recovered, and the mortality rate was the same in both groups (32%). However, ACP patients who recovered required a longer period of respiratory support. A multivariate analysis individualized Paco2 level as the sole factor independently associated with ACP, suggesting that ACP development in ARDS is influenced by the severity of lung damage and/or the respiratory strategy.

CONCLUSION

Evaluation of right ventricular function by TEE in a group of 75 ARDS patients submitted to protective ventilation revealed the persistence of a 25% incidence of ACP, resulting in detrimental hemodynamic consequences associated with tachycardia. However, ACP was reversible in patients who recovered and did not increase mortality.

New CT index to quantify arterial obstruction in pulmonary embolism: comparison with angiographic index and echocardiography

OBJECTIVE

This study was designed to define and evaluate a specific index to quantify arterial obstruction with helical CT in acute pulmonary embolism.

MATERIALS AND METHODS

Fifty-four patients (mean age, 56 years) with proven pulmonary emboli among 158 consecutive patients, who had undergone both CT and pulmonary angiography for clinically suspected pulmonary embolism, were eligible for the study. The CT obstruction index was defined as (n. d) (n, value of the proximal clot site, equal to the number of segmental branches arising distally; d, degree of obstruction scored as partial obstruction [value of 1] or total obstruction [value of 2]). We compared the CT obstruction index with pulmonary arterial obstruction on angiography (assessed by the Miller index), using linear regression, and correlated it with findings on echocardiography. Interobserver variability was determined for both CT and pulmonary angiography indexes.

RESULTS

The CT obstruction index (29% +/- 17%) and the Miller index (43% +/- 25%) were well correlated (r = 0.867, p < 0.0001) with an excellent concordance between investigators for both the CT index (r = 0.944, p < 0.0001) and the Miller index (r = 0.904, p < 0.0001). A CT obstruction index greater than 40% identified more than 90% of patients with right ventricular dilatation.

CONCLUSION

The degree of arterial obstruction in pulmonary embolism may be quantified by a specific CT index that appears reproducible and highly correlated to the previously described index with pulmonary angiography. Further evaluations are needed to investigate the usefulness of the CT obstruction index for stratification of patient risk and determining therapeutic options.

Positive end-expiratory pressure titration in acute respiratory distress syndrome patients: impact on right ventricular outflow impedance evaluated by pulmonary artery Doppler flow velocity measurements

OBJECTIVE

Positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome patients remains debatable. We used two mechanical approaches, calculation of the compliance of the respiratory system and determination of the lower inflexion point of the pressure-volume curve of the respiratory system, to identify specific PEEPs (PEEPS and PEEPA) whose impact on right ventricular (RV) outflow was compared with Doppler analysis of pulmonary artery flow velocity.

DESIGN

Prospective, open, clinical study.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Sixteen consecutive ventilator-dependent acute respiratory distress syndrome patients.

INTERVENTIONS

Two PEEPs were determined: PEEPS was the highest PEEP associated with the highest value of respiratory compliance, and PEEPA was the coordinate of the lower inflexion point of the inspiratory pressure-volume curve on the pressure axis plus 2 cm H2O.

MEASUREMENTS AND MAIN RESULTS

We observed a large difference between the two PEEPs, with PEEPA (13 + 4 cm H2O) > PEEPS (6 + 3 cm H2O). Changes in RV outflow impedance produced by tidal ventilation with zero end-expiratory pressure (ZEEP) and after application of these two PEEPs were assessed by Doppler study of pulmonary artery flow velocity obtained by a transesophageal approach, with particular reference to the end-expiratory and end-inspiratory pulmonary artery velocity-time integral, as reflecting RV stroke output, and mean acceleration as reflecting RV outflow impedance during an unchanged flow period. A significant inspiratory reduction in pulmonary artery velocity-time integral (from 11.8 + 0.3 to 10.0 + 0.3 cm) and mean acceleration (from 11.9 + 0.9 to 8.0 + 0.9 m/sec2) was observed with ZEEP, showing a reduction in RV stroke index (from 29.0 + 0.9 to 26.0 + 0.6 cm3/m2) by a sudden increase in outflow impedance during tidal ventilation. Application of PEEPA, which improved Pao2 (102 + 40 vs. 65 + 18 torr with ZEEP), worsened the inspiratory drop in RV stroke index (21.6 + 0.8 cm3/m2), resulting in a significant reduction in cardiac index compared with ZEEP (from 3.0 + 1.0 to 2.7 + 1.1). Application of PEEPS, which also significantly improved Pao2 (81 + 21 torr), was associated with a lesser impact on RV outflow impedance (inspiratory mean acceleration: 9.5 + 1 m/sec2) and cardiac index (3.2 + 1.0) than PEEPA.

CONCLUSION

RV outflow impedance evaluated by the Doppler technique appeared sensitive to PEEP titration. Application of PEEPA worsened RV systolic function impairment produced by tidal ventilation. Conversely, application of PEEPS reduced RV systolic function impairment, suggesting an association with a lower pulmonary vascular resistance.

Echocardiographic evaluation of left ventricular function in critically ill patients: dynamic loading challenge using medical antishock trousers

STUDY OBJECTIVE

We hypothesized that a dynamic left ventricular (LV) evaluation during a loading challenge might enhance diagnostic capabilities of routine transesophageal echocardiography in critically ill patients and selection of therapeutic options against circulatory failure, particularly the choice between volume expansion and vasoactive agent infusion.

DESIGN

Prospective clinical study in a group of 26 patients requiring hemodynamic support by vasoactive infusion because of low systemic arterial pressure (< 90 mm Hg by invasive monitoring) during mechanical ventilation.

SETTING

University hospital ICU.

PATIENTS

Patients required respiratory support for an episode of acute respiratory failure of various causes or for an episode of coma. They were studied by transesophageal echocardiography during mechanical ventilation in the controlled mode, before and during a loading challenge made using the legs compartment of medical antishock trousers inflated at 80 mm Hg.

MEASUREMENTS

A short-axis view of the left ventricle was obtained by a transgastric approach, and end-diastolic and end-systolic areas were measured. LV stroke area (LVSA) and LV fractional area contraction (LVFAC) were calculated.

RESULTS

Changes in LV echocardiographic measurements permitted separation of the patients into two groups. In nine patients (group 1), LVSA, used as an index of stroke output, was significantly increased during the challenge, together with a significant increase in LV end-diastolic area, suggesting preload improvement by the challenge. Conversely, in 17 patients (group 2), LVSA was significantly reduced by the challenge, together with a significant decrease in LVFAC, suggesting a negative effect of increased afterload by the challenge.

CONCLUSION

Study of the changes in LV dimensions during loading challenge in hemodynamically unstable patients was used to evaluate the balance between the adequacy of preload and the ability of the heart to pump against an increased load, and might thus guide hemodynamic support.

Left ventricular volume analysis for the detection of coronary artery disease during dobutamine stress echocardiography in patients undergoing vascular surgery

AIMS

The purpose of the study was to prospectively evaluate the effectiveness of left ventricular volume changes analysis as compared to wall motion assessment for detecting coronary artery disease during dobutamine stress echocardiography in patients undergoing elective vascular surgery.

METHODS AND RESULTS

Left ventricular volumes, measured by using the ellipsoid biplane method combining the apical four- and two-chamber echocardiographic views, and classical wall motion score were determined at rest and peak stress (dobutamine infusion 5-40 microg/kg/min+/- atropine 0.25-1mg) in 68 consecutive patients. A positive test was defined as a decrease of less than 15% in left ventricular end-diastolic or end-systolic volume at peak stress for volume analysis and as an increase in score between rest and peak stress in one or more segments for wall motion assessment. Stress test was not analysable in five patients. Coronary angiography revealed significant coronary artery disease (coronary stenosis >or=70%) in 28/63 (44%) patients: one-vessel in 15, two- or three-vessel disease in 13. Overall sensitivity and specificity for coronary artery disease detection were 56% and 97% with left ventricular volume analysis, as compared to 64% and 89% with wall motion assessment. For patients with two- or three-vessel disease, sensitivity and specificity of volume analysis reached 92%.

CONCLUSION

The present data suggest that left ventricular volume change analysis during dobutamine stress echocardiography could be a reliable method for the detection of extensive coronary artery disease for patients undergoing vascular surgery.

Pulmonary embolism detection: prospective evaluation of dual-section helical CT versus selective pulmonary arteriography in 157 patients

PURPOSE

To evaluate the accuracy of dual-section helical computed tomography (CT) in acute pulmonary embolism (PE) diagnosis.

MATERIALS AND METHODS

Of 204 consecutive patients with clinically suspected acute PE (mean age, 58 years +/- 14 [SD]), 158 were enrolled. All patients underwent dual-section helical CT (2.7-mm effective section thickness) and selective pulmonary arteriography within 12 hours of each other. Each image was analyzed independently by two observers, who determined image quality and presence of PE among arterial segments, including at the subsegmental level. The final diagnosis was made with consensus.

RESULTS

Selective pulmonary arteriography was considered optimal in 147 (93%), suboptimal in 10 (6%), and inconclusive in one (0.6%) of 158 patients. Dual-section helical CT findings were considered technically optimal in 140 (89%), suboptimal in 11 (7%), and inconclusive in six (4%). Selective pulmonary arteriography demonstrated PE in 62 patients. Four (6%) of 62 patients had isolated subsegmental PE. The sensitivity of dual-section helical CT was 90%, and the specificity was 94%. The positive and negative predictive values were 90% and 94%, respectively.

CONCLUSION

Dual-section helical CT is an improvement in helical CT that offers a high sensitivity and specificity for the depiction of PE, including at the subsegmental level. Dual-section helical CT can replace pulmonary arteriography for the direct demonstration of PE in a majority of patients.

Inhibition of matrix metalloproteinases by lung TIMP-1 gene transfer or doxycycline aggravates pulmonary hypertension in rats

Chronic hypoxic pulmonary hypertension (PH) results from persistent vasoconstriction, excess muscularization, and extracellular matrix remodeling of pulmonary arteries. The matrix metalloproteinases (MMPs) are a family of proteinases implicated in extracellular matrix turnover and hence in smooth muscle and endothelial cell migration and proliferation. Because MMP expression and activity are increased in PH, we designed the present study to investigate whether inhibition of lung MMPs in rats subjected to chronic hypoxia (CH) contributes to or protects against vascular remodeling and PH. To achieve lung MMP inhibition, rats exposed to 10% O(2) for 15 days were treated with either doxycycline (20 mg/kg per day by gavage starting 2 days before and continuing throughout the CH period) or a single dose of recombinant adenovirus (Ad) for the human tissue inhibitors of metalloproteinases-1 (hTIMP-1) gene (Ad.hTIMP-1, 10(8) plaque-forming units given intratracheally 2 days before CH initiation). Control groups either received no treatment or were treated with an adenovirus containing no gene in the expression cassette (Ad.Null). Efficacy of hTIMP-1 gene transfer was assessed both by ELISA on bronchoalveolar lavages and by hTIMP-1 immunofluorescence on lung sections. MMP inhibition in lungs was evaluated by in situ zymography and gelatinolytic activity assessment using [(3)H]gelatin. Rats treated with either doxycycline or Ad.hTIMP-1 had higher pulmonary artery pressure and right heart ventricular hypertrophy more severe than their respective controls. Worsening of PH was associated with increased muscularization and periadventitial collagen accumulation in distal arteries. In conclusion, our study provides compelling evidence that MMPs play a pivotal role in protecting against pulmonary artery remodeling.

Predictors of mortality in acute respiratory distress syndrome. Focus On the role of right heart catheterization

Right heart catheterization (RHC) has been suspected of increasing mortality. The acute respiratory distress syndrome (ARDS) is a frequent reason for RHC. We designed a retrospective cohort study of 119 consecutive ARDS patients admitted to two medical intensive care units of tertiary care hospitals in which two different approaches are used for hemodynamic monitoring: RHC on demand (Henri Mondor Hospital [HM]) and no use of RHC (Ambroise Paré Hospital [AP]). The study tried to identify risk factors for death, and to assess the influence of RHC, with adjustment for the intensity of hemodynamic support as a confounding factor, using 98 patients in whom the delay between onset of ARDS, use of vasopressors, and RHC did not exceed 48 h. Several variables, including septic shock, cause of ARDS, Simplified Acute Physiology Score (SAPS) II, use of epinephrine/norepinephrine, and presence of RHC were entered into a logistic regression model to evaluate their independent prognostic roles. Mortality was different at HM and AP (36 of 55 patients [65.5%] versus 16 of 43 patients [37.2%], p < 0.005), and 29 of the 35 RHC-monitored patients died (82.8%), as compared with 23 of 63 patients (36.5%) treated without RHC (p < 0.0001). However, administration of epinephrine/norepinephrine and a nonpulmonary cause of ARDS were each independently associated with death. It is only when administration of vasopressors was omitted from the model that RHC, septic shock, and SAPS II became independent predictors of mortality. These results suggest that: (1) the use of vasopressors, but not of RHC, represents an important prognostic factor; and (2) not taking into account the use of these drugs may be misleading when assessing the influence of RHC on outcome.

Persistent preload defect in severe sepsis despite fluid loading: A longitudinal echocardiographic study in patients with septic shock

STUDY OBJECTIVE

To investigate the rate of recovery from septic shock in patients with suspected left ventricular (LV) preload deficiency and LV systolic dysfunction.

DESIGN

A monitoring period was defined by the need for inotropic/vasopressor support, and LV function was assessed daily during this period by bedside two-dimensional echocardiography (2D-ECHO).

SETTING

University hospital ICU.

PATIENTS

During a 5-year period, 90 patients with an episode of septic shock (60% with gram-positive bacteria as the causative agent) were consecutively enrolled in the study (mean age, 55 +/- 18 years). Standard volume resuscitation combined with inotropic/vasopressor support was used to maintain systolic arterial pressure > 90 mm Hg. All patients received mechanical ventilation because of associated respiratory failure. The average duration of hemodynamic support was 4.4 +/- 1.6 days. Thirty-four patients were weaned from hemodynamic support during the monitoring period and ultimately recovered (group I). Twenty-eight patients died from refractory circulatory failure during the monitoring period, and 28 died later from ARDS or multiple organ dysfunction syndrome, leading to a 62% overall mortality rate (group II).

METHODS

Daily bedside LV volumes and ejection fraction (LVEF) were recorded using 2D-ECHO. Data obtained at the start (day 1 and day 2) and end of the monitoring period (day n) were compared.

RESULTS

LV end-diastolic volume was within the normal range of our laboratory values in all patients, but was initially smaller in group II than in group I, and remained so despite fluid loading. LVEF was significantly depressed in all patients, resulting in severe reduction in LV stroke volume (LVSV), which was initially more marked in group I. In group I patients, LVEF significantly improved during the monitoring period, resulting in an increase in LVSV.

CONCLUSION

2D-ECHO changes during hemodynamic support in 90 septic patients confirmed defective LV preload with a propensity to worsen despite fluid loading in nonsurvivors (62% in the present study). Our results are also in agreement with previous studies reporting depressed LV systolic function at the initial phase of septic shock. Since LV dysfunction was more marked in patients who recovered, we suggest that the exact significance of this finding should be reevaluated.

Cyclic changes in right ventricular output impedance during mechanical ventilation

In a context such as acute respiratory distress syndrome, where optimum tidal volume and airway pressure levels are debated, the present study was designed to differentiate the right ventricular (RV) consequences of increasing lung volume from those secondary to increasing airway pressure during tidal ventilation. The study was conducted by combined two-dimensional echocardiographic and Doppler studies in 10 patients requiring mechanical ventilation in the controlled mode because of acute respiratory failure. Continuous monitoring of airway pressure on echocardiographic and Doppler recordings provided accurate timing of each cardiac event during the respiratory cycle, with particular attention being paid to end-expiratory and end-inspiratory atrial diameters, RV dimensions, and pulmonary artery and tricuspid flow estimated by the velocity-time integral (PA(VTI) and T(VTI), respectively). At baseline, lung inflation during the inspiratory phase of mechanical ventilation produced a drop in PA(VTI) from 14.3 +/- 2.6 cm at end expiration to 11.3 +/- 2.1 cm at end inspiration. This drop occurred without reduction in right atrial diameter or in RV diastolic dimensions. It was not preceded but was followed by a decrease in T(VTI), thus confirming an increase in RV outflow impedance. Manipulation of tidal volume without changing airway pressure and manipulation of airway pressure without changing tidal volume demonstrated that tidal volume, but not airway pressure, was the main determinant factor of RV afterloading during mechanical ventilation.

Improved prognosis of acute respiratory distress syndrome 15 years on

OBJECTIVE

Evaluation of the impact of low-volume, pressure-limited ventilation on the recovery rate of acute respiratory distress syndrome (ARDS).

DESIGN

Prospective observational clinical study with historical control.

SETTING

University hospital intensive care unit (ICU).

PATIENTS

We studied two groups of, respectively, 33 and 37 ARDS patients separated by 15 years ("historical", June 1978-April 1981, and "recent", October 1993-June 1996).

METHOD

ARDS was defined as the presence of bilateral chest infiltrates and a PaO(2)/FIO(2) ratio of less than 200 mmHg under controlled ventilation regardless of PEEP level. Any cardiac participation was excluded by right heart catheterization in the "historical" group and by echo-Doppler examination in the "recent" group. The origin of ARDS was principally pulmonary (ARDS(p)) in both groups (26/33 and 29/37, respectively), and secondarily extrapulmonary (ARDS(exp)) (7/33 and 8/37, respectively). In the "historical" group, normocapnia was the major goal for respiratory support and was achieved in all patients regardless of airway pressure levels. In contrast, end-inspiratory plateau pressure in the "recent" group was limited to 30 cmH(2)O under respiratory support, regardless of PaCO(2) level. The "historical" and "recent" ARDS groups were compared with regard to therapeutic procedure and outcome.

RESULTS

Normalization of PaCO(2) (36 +/- 6 mmHg) in the "historical" group required high airway pressure (end-inspiratory plateau pressure at 39 +/- 4 cmH(2)O) and high tidal volume (13 ml/kg). Respiratory support used in the "recent" group was less aggressive, with lower airway pressure (end-inspiratory plateau pressure 25 +/- 4 cmH(2)O) and tidal volume (9 ml/kg) resulting in "permissive" hypercapnia (51 +/- 10 mmHg). Mortality rates significantly decreased from 64 % in the "historical" group to 32 % in the "recent" group (p < 0.01). This decrease concerned only ARDS(p), which was markedly predominant in both groups.

CONCLUSION

Mortality due to ARDS of pulmonary origin has declined in our unit over the last 15 years. Low-volume, pressure-limited (protective) ventilation seems the most likely reason for improved survival, despite hypercapnia.