Hemodynamic effects of fluid loading in acute massive pulmonary embolism

[Cardiopulmonary interactions in the course of mechanical ventilation]

INTRODUCTION

The haemodynamic consequences of ventilation are multiple and complex and may affect all the determinants of cardiac performance such as heart rate, preload, contractility and afterload. These consequences affect both right and left ventricle and are also related to the biventricular interdependence.

STATE-OF-THE-ART

Ventilation modifies the lung volume and also the intrathoracic pressure. Variations in lung volume have consequences on the pulmonary vascular resistance, hypoxic pulmonary vasoconstriction and ventricular interdependence. Variations in intrathoracic pressure have a major impact and affect systemic venous return, right ventricular preload, left ventricular preload, right ventricular afterload, left ventricular afterload and myocardial contracility. The haemodynamic consequences of positive pressure ventilation depend on the underlying chronic cardiopulmonary pathologies leading to the acute respiratory failure that was the indication for ventilation.

CONCLUSION

In this review, we will focus on severe COPD exacerbation, acute left heart failure and weaning from ventilation.

Management of pulmonary hypertension and right heart failure in the intensive care unit

Management of acute right ventricular failure, both with and without coexisting pulmonary hypertension, is a common challenge encountered in the intensive care setting. Both right ventricular dysfunction and pulmonary hypertension portend a poor prognosis, regardless of the underlying cause and are associated with significant morbidity and mortality. The right ventricle is embryologically distinct from the left ventricle and has unique morphologic and functional properties. Management of right ventricular failure and pulmonary hypertension in the intensive care setting requires tailored hemodynamic management, pharmacotherapy, and often mechanical circulatory support. Unfortunately, our understanding of the management of right ventricular failure lags behind that of the left ventricle. In this review, we will explore the underlying pathophysiology of the failing right ventricle and pulmonary vasculature in patients with and without pulmonary hypertension and discuss management strategies based on evidence-based studies as well as our current understanding of the underlying physiology.

Management of massive and submassive pulmonary embolism: focus on recent randomized trials

PURPOSE OF REVIEW

Although early pulmonary revascularization is the treatment of choice for patients with high-risk (massive) pulmonary embolism, it remains controversial in patients with intermediate-risk (submassive) pulmonary embolism until recently. Recent published data on the management of high-risk and intermediate-risk pulmonary embolism patients will be the main focus of this review.

RECENT FINDINGS

The PEITHO trial supports the rationale of risk stratification in normotensive patients with pulmonary embolism. Patients with right ventricular dilation on echocardiography and positive cardiac troponin test have a high intermediate risk of complication and death. Thrombolysis prevents hemodynamic collapse in these patients but with an increased risk of major bleeding particularly in older patients (>75 years). Reduced dose of thrombolysis and catheter-based reperfusion with or without fibrinolysis have shown promising results.

SUMMARY

Thrombolysis is the treatment of choice for patients with high-risk pulmonary embolism. Surgical embolectomy is recommended in case of absolute contra-indication to thrombolysis. In patients with acute right ventricular dysfunction on cardiac imaging and myocardial injury, thrombolysis should be considered if they are 75 years or less of age and are at low risk of bleeding. Full-dose thrombolysis may be excessively risky in patients over 75 years. In patients with either RV dilation or elevated cardiac biomarker, thrombolysis is not recommended.

[Pulmonary embolism]

Pulmonary embolism is a potentially fatal disorder and frequently seen in critical care and emergency medicine. Due to a high mortality rate within the first few hours, the accurate initiation of rational diagnostic pathways in patients with suspected pulmonary embolism and timely consecutive treatment is essential. In this review, the current European guidelines on the diagnosis and therapy of acute pulmonary embolism are presented. Special focus is put on a structured patient management based on the individual risk of early mortality. In particular risk assessment and new risk-adjusted treatment recommendations are presented and discussed in this article.

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.

Diuretic versus placebo in normotensive acute pulmonary embolism with right ventricular enlargement and injury: a double-blind randomised placebo controlled study. Protocol of the DiPER study

INTRODUCTION

In acute pulmonary embolism (PE), poor outcome is usually related to right ventricular (RV) failure due to the increase in RV afterload. Treatment of PE with RV failure without shock is controversial and usually relies on fluid expansion to increase RV preload. However, several studies suggest that fluid expansion may worsen acute RV failure by increasing RV dilation and ischaemia, and increase left ventricular compression by RV dilation. By reducing RV enlargement, diuretic treatment may break this vicious circle and provide early improvement in normotensive patients referred for acute PE with RV failure.

METHODS AND ANALYSIS

The Diuretic versus placebo in Pulmonary Embolism with Right ventricular enlargement trial (DiPER) is a prospective, multicentre, randomised (1:1), double-blind, placebo controlled study assessing the superiority of furosemide as compared with placebo in normotensive patients with confirmed acute PE and RV dilation (diagnosed on echocardiography or CT of the chest) and positive brain natriuretic peptide result. The primary end point will be a combined clinical criterion derived from simplified Pulmonary Embolism Severity Index (PESI) score and evaluated at 24 h. It will include: (1) urine output >0.5 mL/kg/min for the past 24 h; (2) heart rate <110 bpm; (3) systolic blood pressure >100 mm Hg and (4) arterial oxyhaemoglobin level >90%. Thirty-day major cardiac events defined as death, cardiac arrest, mechanical ventilation, need for catecholamine and thrombolysis, will be evaluated as a secondary end point. Assuming an increase of 30% in the primary end point with furosemide and a β risk of 10%, 270 patients will be required.

ETHICS AND DISSEMINATION

Ethical approval was received from the ethical committee of Ile de France (2014-001090-14). The findings of the trial will be disseminated through peer-reviewed journals, and national and international conference presentations.

TRIAL REGISTRATION NUMBER

NCT02268903.

Pulmonary Hypertension in the Intensive Care Unit

Pulmonary hypertension occurs as the result of disease processes increasing pressure within the pulmonary circulation, eventually leading to right ventricular failure. Patients may become critically ill from complications of pulmonary hypertension and right ventricular failure or may develop pulmonary hypertension as the result of critical illness. Diagnostic testing should evaluate for common causes such as left heart failure, hypoxemic lung disease and pulmonary embolism. Relatively few patients with pulmonary hypertension encountered in clinical practice require specific pharmacologic treatment of pulmonary hypertension targeting the pulmonary vasculature. Management of right ventricular failure involves optimization of preload, maintenance of systemic blood pressure and augmentation of inotropy to restore systemic perfusion. Selected patients may require pharmacologic therapy to reduce right ventricular afterload by directly targeting the pulmonary vasculature, but only after excluding elevated left heart filling pressures and confirming increased pulmonary vascular resistance. Critically-ill patients with pulmonary hypertension remain at high risk of adverse outcomes, requiring a diligent and thoughtful approach to diagnosis and treatment.

Management of massive and submassive pulmonary embolism

Massive pulmonary embolism has a high mortality rate despite advances in diagnosis and therapy. This article attempts to review the evidence-based risk stratification, diagnosis, initial stabilization, and management of massive and submassive pulmonary embolism.

Massive pulmonary embolism

Massive pulmonary embolism (PE) is a potentially lethal condition, with death usually caused by right ventricular (RV) failure and cardiogenic shock. Systemic thrombolysis (unless contraindicated) is recommended as the first-line treatment of massive PE to decrease the thromboembolic burden on the RV and increase pulmonary perfusion. Surgical pulmonary embolectomy or catheter-directed thrombectomy should be considered in patients with contraindications to fibrinolysis, or those with persistent hemodynamic compromise or RV dysfunction despite fibrinolytic therapy. Critical care management predominantly involves supporting the RV, by optimizing preload, RV contractility, and coronary perfusion pressure and minimizing afterload. Despite these interventions, mortality remains high.

Should furosemide be avoided in acute right ventricular myocardial infarction?

BACKGROUND

Diuretics are conventionally prohibited in acute right ventricular myocardial infarction.

AIMS

To assess the benefit of diuretics compared to fluid expansion in patients with inferior myocardial infarction extended to the right ventricule.

METHODS

Of 295 patients admitted for inferior or posterior acute myocardial infarction between November 2008 and November 2010, 77 had a right ventricular extension. Among these 77 patients, 19 presented with oligoanuria (<0.5 mL/kg per hour) and no criteria for cardiogenic shock. Overall, 11 patients were treated by low dose of furosemide (40 to 80 mg) and eight received fluid expansion using isotonic saline solution.

RESULTS

Baseline right ventricular dilatation and dysfunction, systolic blood pressure and heart rate were similar between the groups. Twenty-four hours after treatment, urine output was similar between the two groups but only the patients in the diuretic group improved their blood pressure (103 ± 16 mmHg versus 127 ± 20 mmHg, P < 0.001), heart rate (71 ± 15 bpm versus 76 ± 13 bpm, P = 0.03), creatinin level and alanine aminotrasferase plasmatic level. Hospitalization duration and the need of inotropic support were similar in the two groups.

CONCLUSIONS

Diuretics and fluid expansion provide similar efficiency for triggering diuresis in patients with right ventricular infarction and oligoanuria but only diuretics seem to be associated with improvement in hemodynamic status and venous congestion.

Pulmonary Embolism in the Mechanically-Ventilated Critically Ill Patient: Is it Different?

Pulmonary embolism (PE) confers significant in-hospital morbidity and mortality, and critically ill patients remain at risk for venous thromboembolism despite thromboprophylaxis. Recognition of the clinical manifestations and immediate management of PE are of paramount importance. Despite diagnostic advances, PE is often undiagnosed and untreated in patients receiving mechanical ventilation, as these patients do not exhibit the common clinical features of the condition, making the diagnosis very challenging. Computed tomographic pulmonary angiography is probably the reference standard for the diagnosis of acute PE in the haemodynamically stable, ventilated patient. In the setting of circulatory collapse, bedside echocardiography may be used to risk stratify these patients, based on the presence or absence of right ventricular dysfunction, and guide further management. Treatment options include anticoagulation alone, anticoagulation plus thrombolysis, surgical or catheter embolectomy. Inotropes, vasopressors and pulmonary artery vasodilators may be considered after initial resuscitation of the right ventricle. Few studies have focused on estimating the prevalence of PE among mechanically-ventilated intensive care unit (ICU) patients and there is notable lack of data assessing predictive factors, prevention, diagnostic strategy and management of PE in the ICU setting.

Management of massive and nonmassive pulmonary embolism

Massive pulmonary embolism (PE) is characterized by systemic hypotension (defined as a systolic arterial pressure < 90 mm Hg or a drop in systolic arterial pressure of at least 40 mm Hg for at least 15 min which is not caused by new onset arrhythmias) or shock (manifested by evidence of tissue hypoperfusion and hypoxia, including an altered level of consciousness, oliguria, or cool, clammy extremities). Massive pulmonary embolism has a high mortality rate despite advances in diagnosis and therapy. A subgroup of patients with nonmassive PE who are hemodynamically stable but with right ventricular (RV) dysfunction or hypokinesis confirmed by echocardiography is classified as submassive PE. Their prognosis is different from that of others with non-massive PE and normal RV function. This article attempts to review the evidence-based risk stratification, diagnosis, initial stabilization, and management of massive and nonmassive pulmonary embolism.

Acute pulmonary embolism after pneumonectomy

Pulmonary embolism (PE) by occlusion of the pulmonary arterial bed may lead to acute life-threatening but potentially reversible right ventricular failure, one of the most severe complications of thoracic surgery. Still, the incidence of acute pulmonary embolism after surgery is reduced by comprehensive anticoagulant prevention, improved surgical techniques, appropriate perioperative management and early ambulation. However, there is difficulty in diagnosing PE after thoracic surgery due to the lack of specific clinical manifestations. So that optimal diagnostic strategy and management according to the clinical presentation and estimated risk of an adverse outcome is fundamental.

Right ventricular responses to massive and submassive pulmonary embolism

It is critically important to quickly recognize and treat acute pulmonary embolism (PE). Submassive and massive PEs are associated with right ventricular (RV) dysfunction and may culminate in RV failure, cardiac arrest, and death. A rapid and coordinated diagnostic and management approach can maximize success and save lives.

Pulmonary embolism in the emergency department: a Singaporean nursing case review

INTRODUCTION

The presentation of pulmonary embolism to the emergency department (ED) can prove challenging because of the myriad of potential disease processes that mimic its signs and symptoms. The incidence of pulmonary embolism and indeed the mortality associated with it is relatively high. Early diagnosis and treatment is crucial in off-setting the potential deleterious effects associated with this condition. The aim of this article is to present a nursing case review of a patient presenting to the ED with a diagnosis of pulmonary embolism.

METHOD

We chose to use a case review to highlight the nursing and medical care that was provided for a patient who presented to the emergency department acutely with dyspnoea, chest pain and pyrexia. The use of case reviews are useful in reporting unusual or rare cases and this format is typically seen more in medicine than in nursing. They can naturally take one of two formats-a single case report or a series of case reports; in this case we opted to report on a single case.

DISCUSSION

The gentleman in question was an ambulance admission to the ED with a three day history of chest pain, shortness of breath and one episode of syncope which brought him to the ED. Over the course of his admission a variety of treatment modalities were used successfully to alleviate the problem. More notable from a nursing perspective was the use of diagnostic tools as an interpretation to guide his care and provide a platform from which a deeper understanding and appreciation of the intricacies the critically ill patient often presents.

CONCLUSION

We found the use of case review very enlightening in understanding the disease process and the decision-making that accompanies this. Whilst our patient was successfully rehabilitated home, we learnt a lot from the experience which has been most beneficial in supporting our understanding of pulmonary embolism.

Advances in the diagnosis and treatment of acute pulmonary embolism

Over the past two decades, considerable progress in technology and clinical research methods have led to advances in the diagnosis, treatment and prevention of acute venous thromboembolism. Despite this, however, the diagnosis is still often missed and preventive methods are often ignored. Published guidelines are useful, but are limited by the existing evidence base so that controversies remain with regard to topics such as duration of anticoagulation, indications for placement and removal of inferior vena caval filters, and when and how to administer thrombolytic therapy. The morbidity and mortality of this disease remain high, particularly when undiagnosed. While preventive approaches remain crucial, the focus of this review is on the diagnostic and therapeutic approach to acute venous thromboembolism, with an emphasis on acute pulmonary embolism.

Intensive care unit management of patients with severe pulmonary hypertension and right heart failure

Despite advances in medical therapies, pulmonary arterial hypertension (PAH) continues to cause significant morbidity and mortality. Although the right ventricle (RV) can adapt to an increase in afterload, progression of the pulmonary vasculopathy that characterizes PAH causes many patients to develop progressive right ventricular failure. Furthermore, acute right ventricular decompensation may develop from disorders that lead to either an acute increase in cardiac demand, such as sepsis, or to an increase in ventricular afterload, including interruptions in medical therapy, arrhythmia, or pulmonary embolism. The poor reserve of the right ventricle, RV ischemia, and adverse right ventricular influence on left ventricular filling may lead to a global reduction in oxygen delivery and multiorgan failure. There is a paucity of data to guide clinicians caring for acute right heart failure in PAH. Treatment recommendations are frequently based on animal models of acute right heart failure or case series in humans with other causes of pulmonary hypertension. Successful treatment often requires that invasive hemodynamics be used to monitor the effect of strategies that are based primarily on biological plausibility. Herein we have developed an approach based on the current understanding of RV failure in PAH and have attempted to develop a treatment paradigm based on physiological principles and available evidence.

Acute lung failure

Lung failure is the most common organ failure seen in the intensive care unit. The pathogenesis of acute respiratory failure (ARF) can be classified as (1) neuromuscular in origin, (2) secondary to acute and chronic obstructive airway diseases, (3) alveolar processes such as cardiogenic and noncardiogenic pulmonary edema and pneumonia, and (4) vascular diseases such as acute or chronic pulmonary embolism. This article reviews the more common causes of ARF from each group, including the pathological mechanisms and the principles of critical care management, focusing on the supportive, specific, and adjunctive therapies for each condition.

[Update on diagnosis and treatment of high-risk pulmonary embolism]

INTRODUCTION

High-risk pulmonary embolism (PE) is associated with a significant early mortality, approaching 25%, and is defined by the presence of cardiogenic shock.

STATE OF THE ART

The high early mortality rate for patients with shock requires a rapid diagnostic approach with bedside tests. Right ventricular dilatation assessed by echocardiography in patients with a high clinical probability for PE confirms the diagnosis without the need for additional testing. Spiral CT pulmonary angiography remains the first line investigation for patients without shock. Anticoagulant treatment should be started as soon as pulmonary embolism is suspected. Fibrinolytic therapy is recommended for patients with high-risk pulmonary embolism. The prognostic value of cardiac biomarkers, such as B natriuretic peptide, troponins and right ventricular dilatation for early mortality has been demonstrated. These markers permit the identification of an intermediate risk group of patients with normotensive pulmonary embolism and prognostic scores have been developed.

PERSPECTIVES

It remains to be established whether fibrinolysis can have a clinical benefit or reduce mortality in patients with intermediate risk pulmonary embolism. A large randomised placebo-controlled study is currently under way to answer this question. Further studies will more clearly define the role of various predictive rules to identify patients requiring hospital care or those who should be considered for outpatient management.

Pulmonary vascular and right ventricular dysfunction in adult critical care: current and emerging options for management: a systematic literature review

INTRODUCTION

Pulmonary vascular dysfunction, pulmonary hypertension (PH), and resulting right ventricular (RV) failure occur in many critical illnesses and may be associated with a worse prognosis. PH and RV failure may be difficult to manage: principles include maintenance of appropriate RV preload, augmentation of RV function, and reduction of RV afterload by lowering pulmonary vascular resistance (PVR). We therefore provide a detailed update on the management of PH and RV failure in adult critical care.

METHODS

A systematic review was performed, based on a search of the literature from 1980 to 2010, by using prespecified search terms. Relevant studies were subjected to analysis based on the GRADE method.

RESULTS

Clinical studies of intensive care management of pulmonary vascular dysfunction were identified, describing volume therapy, vasopressors, sympathetic inotropes, inodilators, levosimendan, pulmonary vasodilators, and mechanical devices. The following GRADE recommendations (evidence level) are made in patients with pulmonary vascular dysfunction: 1) A weak recommendation (very-low-quality evidence) is made that close monitoring of the RV is advised as volume loading may worsen RV performance; 2) A weak recommendation (low-quality evidence) is made that low-dose norepinephrine is an effective pressor in these patients; and that 3) low-dose vasopressin may be useful to manage patients with resistant vasodilatory shock. 4) A weak recommendation (low-moderate quality evidence) is made that low-dose dobutamine improves RV function in pulmonary vascular dysfunction. 5) A strong recommendation (moderate-quality evidence) is made that phosphodiesterase type III inhibitors reduce PVR and improve RV function, although hypotension is frequent. 6) A weak recommendation (low-quality evidence) is made that levosimendan may be useful for short-term improvements in RV performance. 7) A strong recommendation (moderate-quality evidence) is made that pulmonary vasodilators reduce PVR and improve RV function, notably in pulmonary vascular dysfunction after cardiac surgery, and that the side-effect profile is reduced by using inhaled rather than systemic agents. 8) A weak recommendation (very-low-quality evidence) is made that mechanical therapies may be useful rescue therapies in some settings of pulmonary vascular dysfunction awaiting definitive therapy.

CONCLUSIONS

This systematic review highlights that although some recommendations can be made to guide the critical care management of pulmonary vascular and right ventricular dysfunction, within the limitations of this review and the GRADE methodology, the quality of the evidence base is generally low, and further high-quality research is needed.

[Massive pulmonary embolism]

Massive pulmonary embolism is defined by systemic hypotension or cardiogenic shock. Clinically stable patients with right ventricular dysfunction on echocardiography, elevated brain natriuretic peptide or troponin are usually considered as having sub-massive pulmonary embolism, but this definition is not universally accepted. The time-lag to confirm massive pulmonary embolism should be kept as short as possible and every effort should be done to rely on bedside tests and to avoid patient transfer to the radiology department. D-dimer tests are useless in this setting and the diagnosis is mainly based on clinical probability and bedside echocardiography. When clinical probability is high, right ventricular dilatation assessed by echocardiography allows confirming the diagnosis without additional testing. On the other hand a normal echocardiography does not allow excluding pulmonary embolism. In this setting, a spiral computed tomography is mandatory after the patient has been stabilized. Anticoagulant treatment should be started as soon as pulmonary embolism has been suspected. Supportive care includes oxygen, fluid loading and inotropes. There is little doubt that thrombolytic treatment is of value in patients with massive pulmonary embolism. Conversely, the use of thrombolytic therapy in patients with so-called sub-massive pulmonary embolism remains controversial. Current data do not confirm that thrombolytic therapy decreases mortality in those patients but cannot exclude a clinically significant benefit. A large randomised comparison of heparin and thrombolysis in patients with sub-massive pulmonary embolism is underway to answer this question. Surgical or catheter embolectomy is nowadays only rarely performed in patients with pulmonary embolism. This method can be undertaken in the few patients with persisting shock despite supportive care and who have an absolute contraindication for thrombolytic therapy. Before new data are available there is no special indication for vena cava interruption in patients with massive pulmonary embolism.

Guidelines on the diagnosis and management of acute pulmonary embolism: the Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC)

Non-thrombotic PE does not represent a distinct clinical syndrome. It may be due to a variety of embolic materials and result in a wide spectrum of clinical presentations, making the diagnosis difficult. With the exception of severe air and fat embolism, the haemodynamic consequences of non-thrombotic emboli are usually mild. Treatment is mostly supportive but may differ according to the type of embolic material and clinical severity.

Right ventricular dysfunction

PURPOSE OF REVIEW

Until recently the right ventricle's role in myocardial dynamics has not been fully appreciated. This article provides an overview of the pathophysiology, imaging and management of right ventricular dysfunction.

RECENT FINDINGS

That levosimendan may promote right ventricular function opens new avenues for treatment. In addition there are existing therapies such as phosphodiesterase inhibitors and nitric oxide, which offer yet further modalities to improve outcome in right ventricular failure. How these drugs are used, in combination or alone, in conjunction with ventilatory and cardiovascular strategies has not been evaluated in multicentred randomized controlled trials.

SUMMARY

Acute right ventricular dysfunction is relatively common. There is a lack of convincing evidence in favour of any single treatment modality. Imaging methods now permit a more accurate evaluation of the right ventricle and its function. Combining treatments may offer significant advantages and the imaging and monitoring available allows real-time assessment of the response to intervention. This article illustrates how incomplete our knowledge of this condition and its management within the critical care setting is and reinforces previous calls for suitably designed trials to evaluate and develop guidelines for existing strategies and therapeutic agents.

The influence of volume management on outcome

PURPOSE OF REVIEW

Fluid (volume) therapy is an integral component in the management of critically ill patients and fluid management may influence outcome. There is much controversy, however, about the type, timing and amount of fluid therapy. Here, we discuss the evidence available to guide such choices.

RECENT FINDINGS

Fluid therapy is widely endorsed for resuscitation of critically ill patients across a range of conditions. Yet, the approach to fluid therapy is subject to substantial variation in clinical practice. Emerging data show that the choice, timing and amount of fluid therapy may affect clinical outcomes. Synthetic colloids may increase the risk of acute kidney injury. Albumin may benefit hypoalbuminemic patients with sepsis and acute lung injury but may worsen outcome in traumatic brain injury. Early administration of fluid therapy in sepsis may improve survival but may be unnecessary in patients with penetrating trauma. Later fluid therapy in acute lung injury patients will increase the duration of ventilator dependence without achieving better survival. A positive cumulative balance likely contributes to increased morbidity and mortality after major surgery.

SUMMARY

Emerging evidence shows that choice, timing and amount of fluid therapy affect outcome. Future studies need to focus on these aspects of fluid therapy by means of larger, more rigorous and blinded controlled trials.

Lungenembolie

In the population the annual incidence of pulmonary embolism amounts to 1.3-2.8 per 1000 at the age of 65-89 years. Mortality reaches about 17% within the first 3 months. Acute pulmonary embolism is characterized by an increase in pulmonary arterial pressure and an impairment of the pulmonary gas exchange. Elevation of the right cardiac pressure up to right heart decompensation may follow. In addition, hypoxemia, hyperventilation, dead space ventilation, right to left shunting, bronchoconstriction, and vasoconstriction may occur. Clinical examination, ECG, laboratory findings such as elevated D-dimer, blood gas analysis, ultrasound examination of the veins of the lower extremities, and transthoracic echocardiography are acutely available diagnostic methods of an emergency department. In addition, extensive diagnostic procedures like pulmonary scintigraphy and pulmonary angiography may be required. The aim is to get a definite diagnosis as quickly as possible to direct therapy. In acute pulmonary embolism with cardiac shock, monitoring and stabilization of the circulatory function as well as an appropriate anticoagulant therapy are essential. In some cases surgery or a local fibrinolytic intervention is indicated.

What role does the right side of the heart play in circulation?

Right ventricular failure (RVF) is an underestimated problem in intensive care. This review explores the physiology and pathophysiology of right ventricular function and the pulmonary circulation. When RVF is secondary to an acute increase in afterload, the picture is one of acute cor pulmonale, as occurs in the context of acute respiratory distress syndrome, pulmonary embolism and sepsis. RVF can also be caused by right myocardial dysfunction. Pulmonary arterial catheterization and echocardiography are discussed in terms of their roles in diagnosis and treatment. Treatments include options to reduce right ventricular afterload, specific pulmonary vasodilators and inotropes.

Pulmonary Embolism in the Critically Ill

Pulmonary embolism in the critically ill requires considerations beyond anticoagulant therapy. Measurements of chamber size by echocardiography and CT and of circulating biomarkers identify higher-risk patients with moderate accuracy and may aid determination of patient acuity. Preserving right ventricular function requires judicious use of volume administration, vasopressor, and perhaps vasodilator therapies. Obstructing thrombus can be treated with fibrinolytic drugs, percutaneous instrumentation, or surgically, but these treatments may not be equally effective or safe. Anticoagulant therapy in critically ill patients is likely best administered IV. Bleeding complications should be assiduously sought but do not necessitate anticoagulant discontinuation in every case. The antidotes protamine, desmopressin acetate, factor VIII inhibitory bypass activity, and recombinant factor VIIa may each have a place in controlling anticoagulant-related bleeding. The grave prognosis of heparin-induced thrombocytopenia warrants close surveillance, with rapid switching to lepirudin, argatroban, or fondaparinux necessary if it is suspected. Retrievable vena cava filters can be lifesaving, and at least one type may be safely removed after residence of nearly 1 year.

[Diagnostic and therapeutic progress. Venous thromboembolism, cardiac insufficiency and radio contrast agents]

MODALITIES FOR THE DIAGNOSIS OF VENOUS THROMBOEMBOLISM: Currently rely on the confrontation of the initial clinical data and the results of D-dimer measurements, a venous Doppler, although reliable, is not a first-line exploration. REGARDING TREATMENT: Indications for thrombolysis are currently limited to massive pulmonary oedema with shock. Alteplase added to heparin improves the progression of severe embolism; it spares the patients from heavy interventions of resuscitation but the mortality remains the same. Concerning anticoagulant treatments, prolonged antivitamin K at classical doses is more effective than low doses and for limited duration if phlebitis is an idiopathic one. FOR HEART FAILURE WITH PRESERVED EJECTION FRACTION: Treatment of these heart failures, formerly know as 'diastolic' is similar to that of the acute phase of systolic heart failure. However, care should be taken with vasodilatators. CONCERNING HEART FAILURE IN GENERAL: The brain natriuretic peptide (BNP) represents a remarkable progress for the aetiological diagnosis of dyspnoea (inferior to 80 pg/ml in the case of pulmonary origin, superior to 300 pg/ml in the case of cardiac origin or severe pulmonary embolism). Regarding treatment, for acute heart failure, it is still the association of nitrates and diuretics, with oxygen therapy and eventually inotropics. Beta-blockers, which have revolutionized the treatment of chronic heart failure, must be maintained whenever possible in the case of the onset of acute pulmonary oedema. Multisite pacing is increasingly used in refractory chronic heart failure. Implantable defibrillation has become common practice. Non-invasive ventilation (Bi or C-PAP) is interesting in acute cardiogenic pulmonary oedema. THE PREVENTIVE ROLE OF N ACETYL-CYSTEINE: N acetyl cysteine reduces the incidence of nephropathies induced by the radio contrast products in patients with chronic kidney failure. Combined with hydratation, it must be proposed the day before and on the day of the procedure in any patient with diabetes or kidney failure.

Monitoring mixed venous oxygen saturation in patients with obstructive shock after massive pulmonary embolism

BACKGROUND

Patients with massive pulmonary embolism and obstructive shock usually require hemodynamic stabilization and thrombolysis. Little is known about the optimal and proper use of volume infusion and vasoactive drugs, or about the titration of thrombolytic agents in patients with relative contraindication for such treatment. The aim of the study was to find the most rapidly changing hemodynamic variable to monitor and optimize the treatment of patients with obstructive shock following massive pulmonary embolism.

PATIENTS AND METHODS

Ten consecutive patients hospitalized in the medical intensive care unit in the community General Hospital with obstructive shock following massive pulmonary embolism were included in the prospective observational study. Heart rate, systolic arterial pressure, central venous pressure, mean pulmonary-artery pressure, cardiac index, total pulmonary vascular-resistance index, mixed venous oxygen saturation, and urine output were measured on admission and at 1, 2, 3, 4, 8, 12, and 16 hours. Patients were treated with urokinase through the distal port of a pulmonary-artery catheter.

RESULTS

At 1 hour, mixed venous oxygen saturation, systolic arterial pressure and cardiac index were higher than their admission values (31+/-10 vs. 49+/-12%, p<0.0001; 86+/-12 vs. 105+/-17 mmHg, p<0.01; 1.5+/-0.4 vs. 1.9+/-0.7 L/min/m2, p<0.05; respectively), whereas heart rate, central venous pressure, mean pulmonary-artery pressure and urine output remained unchanged. Total pulmonary vascular-resistance index was lower than at admission (29+/-10 vs. 21+/-12 mmHg/L/min/m2, p<0.05). The relative change of mixed venous oxygen saturation at hour 1 was higher than the relative changes of all other studied variables (p<0.05). Serum lactate on admission and at 12 hours correlated to mixed venous oxygen saturation (r=-0.855, p<0.001).

CONCLUSION

In obstructive shock after massive pulmonary embolism, mixed venous oxygen saturation changes more rapidly than other standard hemodynamic variables.

Acute right ventricular failure--from pathophysiology to new treatments

The right ventricle (RV) provides sustained low-pressure perfusion of the pulmonary vasculature, but is sensitive to changes in loading conditions and intrinsic contractility. Factors that affect right ventricular preload, afterload or left ventricular function can adversely influence the functioning of the RV, causing ischaemia and right ventricular failure (RVF). As RVF progresses, a pronounced tricuspid regurgitation further decreases cardiac output and worsens organ congestion. This can degenerate into an irreversible vicious cycle. The effective diagnosis of RVF is optimally performed by a combination of techniques including echocardiography and catheterisation, which can also be used to monitor treatment efficacy. Treatment of RVF focuses on alleviating congestion, improving right ventricular contractility and right coronary artery perfusion and reducing right ventricular afterload. As part of the treatment, inhaled nitric oxide or prostacyclin effectively reduces afterload by vasodilating the pulmonary vasculature. Traditional positive inotropic drugs enhance contractility by increasing the intracellular calcium concentration and oxygen consumption of cardiac myocytes, while vasopressors such as norepinephrine increase arterial blood pressure, which improves cardiac perfusion but increases afterload. A new treatment, the calcium sensitiser, levosimendan, increases cardiac contractility without increasing myocardial oxygen demand, while preserving myocardial relaxation. Furthermore, it increases coronary perfusion and decreases afterload. Conversely, traditional treatments of circulatory failure, such as mechanical ventilation and volume loading, could be harmful in the case of RVF. This review outlines the pathophysiology, diagnosis and treatment of RVF, illustrated with clinical case studies.

Efficacy of alteplase thrombolysis for ED treatment of pulmonary embolism with shock

Our objective was to assess efficacy and tolerance of thrombolysis using 0.6 mg/kg of Alteplase in patients with massive pulmonary embolism defined as the association of a pulmonary embolism with shock. We retrospectively included 21 patients presenting with a massive pulmonary embolism confirmed by either scintigraphy or spiral computed tomography. Patients were treated on the basis of a standard rationale followed by thrombolysis with 0.6 mg/kg Alteplase over a period of 15 minutes. Hospital mortality, vital signs before and 2 hours after thrombolysis, and incidence of hemorrhagic events were recorded. Five patients (23.8%) died, 4 of these deaths occurred during the first 4 hours after hospital admission. Systolic and diastolic blood pressure (Sp02) were significantly improved 2 hours after the beginning of thrombolysis. Five minor hemorrhagic events occurred. This study demonstrates that for patients with pulmonary embolism and shock, a bolus treatment with Alteplase is potentially effective and well tolerated.

Factors determining the duration of tracheal intubation in cardiac surgery: a single-centre sequential patient audit

BACKGROUND AND OBJECTIVE

The study was designed to identify those factors associated with early tracheal extubation following cardiac surgery. Previous studies have tended to concentrate on surgery for coronary artery bypass or on other selected cohorts.

METHODS

Sequential cohort analysis of 296 unselected adult cardiac surgery patients was performed over 3 months.

RESULTS

In total, 39% of all patients were extubated within 6 h, 89% within 24 h and 95% within 48 h. Delayed extubation (>6 h after surgery) appeared unrelated to age, gender, body mass index, a previous pattern of angina or myocardial infarction, diabetes, preoperative atrial fibrillation, and preoperative cardiovascular assessment, as well as other factors. Delayed tracheal extubation was associated with poor left ventricular, renal and pulmonary function, a high Euroscore, as well as the type, duration and urgency of surgery. Early extubation (<6 h) was not associated with a reduced length of stay in either the intensive care unit or in hospital compared with patients who were extubated between 6 and 24 h. In these groups, it is presumed that organizational and not clinical factors appear to be responsible for a delay in discharge from intensive care. Patients who were extubated after 24 h had a longer duration of hospital stay and a greater incidence of postoperative complications. Postoperative complications were not adversely affected by early tracheal extubation.

CONCLUSIONS

In an unselected sequential cohort, both patient- and surgery-specific factors may be influential in determining the duration of postoperative ventilation of the lungs following cardiac surgery. In view of the changing nature of the surgical population, regular re-evaluation is useful in reassessing performance.

Injection pain of rocuronium and vecuronium is evoked by direct activation of nociceptive nerve endings

BACKGROUND AND OBJECTIVE

Rocuronium and, to a lesser extent, vecuronium can induce burning sensations associated with withdrawal reactions during administration. Dermal microdialysis in human and electrophysiological recordings of nociceptors in mouse skin were used to elucidate the underlying mechanisms of pain induction.

METHODS

Microdialysis catheters were inserted intradermally into the forearm of 10 volunteers and were perfused with two different concentrations of rocuronium and vecuronium (1 and 10 mg mL(-1)) or a control. Dialysis samples were taken every 15 min and analysed for protein, histamine, tryptase and bradykinin content. Pain intensity was rated on a numerical scale of 0-10. In a parallel design, activation of cutaneous nociceptors was assessed directly in a skin-nerve in vitro preparation of the mouse hind paw. The receptive fields of identified single C-nociceptors (n = 12) were superfused with rocuronium or vecuronium solutions (10 mg mL(-1)) at physiological pH.

RESULTS

In accordance with clinical observations, microdialysis of rocuronium (10 mg mL(-1)) induced sharp burning pain (NRS 4.1 +/- 1.8), whereas vecuronium given in the usual clinical concentration (1 mg mL(-1)) induced only minor pain sensations (NRS 0.6 +/- 1.3). At equimolar concentrations, pain sensation and concomitant mediator release evoked by both drugs were similar. No correlations were found between pain rating and mediator release. In the in vitro preparation, C-fibres showed a consistent excitatory response with rapid onset after stimulation with vecuronium as well as rocuronium (differences not significant).

CONCLUSIONS

The algogenic effect of aminosteroidal neuromuscular blocking drugs can be attributed to a direct activation of C-nociceptors.

Anaesthetic strategies to reduce perioperative blood loss in paediatric surgery

In adults, a number of measures to reduce perioperative blood loss have been established. These techniques serve to reduce patients' exposure to homologous blood. Most adults are concerned with this issue especially since many patients became infected with human immunodeficiency virus (HIV) during the 1980s through exposure to blood components. While blood-saving strategies are widely used in adults, they are mostly neglected in infants. However, it is these young patients with their whole life in front of them who, it could be argued, would benefit especially from any potentially avoidable infection (HIV, hepatitis, etc.) or immunological complications. In infants and small children, these blood-sparing techniques may not be as effective as in adults and technical limitations may prevent their application. However, some of these measures can be used and may serve to prevent or reduce exposure to homologous blood. In the following review, blood-saving techniques established in adults are described and their applicability for paediatric patients discussed.