Safety of pulmonary angiography in the 1990s

Evaluation and management of patients with chronic thromboembolic pulmonary hypertension - consensus statement from the ISHLT

ISHLT members have recognized the importance of a consensus statement on the evaluation and management of patients with chronic thromboembolic pulmonary hypertension. The creation of this document required multiple steps, including the engagement of the ISHLT councils, approval by the Standards and Guidelines Committee, identification and selection of experts in the field, and the development of 6 working groups. Each working group provided a separate section based on an extensive literature search. These sections were then coalesced into a single document that was circulated to all members of the working groups. Key points were summarized at the end of each section. Due to the limited number of comparative trials in this field, the document was written as a literature review with expert opinion rather than based on level of evidence.

Percutaneous Venous Interventions in The Pulmonary Vascular, Central and Peripheral Venous Systems: How to Recognize, Avoid and Treat Complications

Endovascular treatment of venous disease encompasses a broad range of interventions. Both central and peripheral venous interventions can range from the simple to the complex which increases the need for proper patient selection, procedural planning and technical proficiency. The following article will discuss the importance of avoiding, recognizing and addressing complications associated with venous interventions. Our goal is to raise awareness and educate to help the reader improve performance.

Pulmonary Embolism in Children

Pulmonary embolism (PE) in children is a rare condition with potential for high mortality. PE incidence is increasing owing to increased survival of children with predisposing conditions, increased use of central venous catheters, and improved awareness and recognition. Although pediatric PE is distinct from adult PE, management guidelines in children are extrapolated from the adult data. Treatment includes thrombolysis or thrombectomy, and pharmacologic anticoagulation. Ongoing clinical trials are evaluating the use of direct oral anticoagulants in children. Further research is required to develop pediatric-specific evidence-based guidelines for diagnosis and management of PE.

Diagnostic Considerations of Venous Thromboembolic Disease

Venous thromboembolism (VTE) includes deep venous thrombosis (DVT) and pulmonary embolism (PE). The clinical presentation of VTE is nonspecific and requires confirmatory testing. The most common diagnostic tool for DVT is duplex ultrasonography since it is a noninvasive test with high accuracy. Contrast venography is considered the gold standard modality to diagnose DVT, but it is an invasive test. Magnetic resonance venography and computed tomography venography are alternative diagnostic methods for DVT, which can be helpful in certain circumstances. Pulmonary embolism is commonly diagnosed by computed tomography pulmonary angiography. Ventilation perfusion scanning is an alternative imaging to diagnose PE in patients who cannot receive intravenous contrast. Pulmonary angiography is still the gold standard in the diagnosis of PE and is usually needed in specific conditions. D-dimer assay can be utilized in ruling VTE out in low-risk patients. Estimating the pretest clinical probability for having VTE is the key step in guiding the clinicians and nurses to the appropriate diagnostic method for patients with suspected DVT or PE.

Radiology in the Intensive Care Unit (Part 2)

This review of intensive care unit (ICU) radiology has been divided into two sections. In Part 1, previously published, the discussion focused on the role of the portable radiograph in the evaluation of the critically ill patient and the impact of the introduction of digital radiography and picture-archiving communications systems on patient care. Part 2 of this review will emphasize the role of computed tomography and the increasing contribution of image-guided interventional procedures in patient management. The deleterious effects of mechanical ventilation due to barotrauma will also be discussed.

Neonatal and infant pulmonary thromboembolism: a literature review

Pulmonary thromboembolism (PTE) is rare in neonates and infants; however evidence suggests it is underdiagnosed. The primary objective is to conduct a scientific review to determine if the presentation, diagnosis, treatment and outcomes of neonates and infants with PTE are consistent across studies. Secondly, to develop an algorithm to establish the diagnosis and management of the condition based on current information. Two authors searched the literature independently using existing databases and verified that identical articles were assembled. Infants aged less than 1 year with PTE were included and further categorized into neonates 28 days or less and infants 29 days to 1 year or less. Forty-five articles with 157 cases (121 neonates; 36 infants) were identified with PTE. All of the reports were descriptive and neither randomized controlled trials nor prospective or case-control studies were identified. The reports are sub-classified into cases of pulmonary air embolism (PAE) with a higher mortality rate and patients with PTE. Diagnostic and treatment strategies varied widely and were individually case-based, dependent on clinical findings, which influenced patient outcomes. Scientific data to guide an evidence-based, diagnostic and treatment approach to PTE is limited because of the absence of rigorous clinical trials. Large scale, multicenter collaborative studies are required to firmly establish the management of PTE in this population.

Cardiological Society of India practice guidelines for angiography in patients with renal dysfunction

PREAMBLE: The potential risk of contrast-induced acute kidney injury (CI-AKI) has made utilization of coronary angiography in the work-up for the diagnosis of coronary artery disease in CKD quite low.(1) This is in contrast to increasing prevalence and severity of CAD as the serum creatinine rises.(2) In fact most CKD patients will succumb to CAD and not to ESRD.(3) Thus the judicious use of CAG/PCI in this setting is of prime importance but underused. The CSI began to develop guidelines for Indian context as most guidelines are those developed by ACC/AHA or ESC. The aim was to assist the physicians in selecting the best management strategy for an individual patient under his care based on an expert committee who would review the current data and write the guidelines with relevance to the Indian context. The guidelines were developed initially in June 2010 as an initiative of Delhi CSI. Three interventional cardiologist (SB, AS, KKS), one nephrologist (SCT) and two clinical cardiologists (ST, RG) along with Dr. Roxana Mehran (New York) and Dr. Peter McCullough (Missouri), U.S.A.; were involved in a three-way teleconference to discuss/debate the data. This was presented by SB, and over the next two hours each data subset was debated/agreed/deleted and this resulted in the "Guidelines for CAG in Renal Dysfunction Patients". These were then written and re- circulated to all for final comments. Further, these guidelines were updated and additional Task Force Members nominated by Central CSI were involved in the formation of the final CSI Guidelines. Both (Roxana Mehran and Peter McCullough) reviewed these updated Guidelines in October 2012 and after incorporating the views of all the Task Force members-the final format is as it is presented in this final document.

Management of pulmonary arteriovenous malformations

Pulmonary arteriovenous malformations are rare lesions with significant clinical complications. These lesions are commonly seen in patients with hereditary hemorrhagic telangiectasia (formerly Osler-Weber-Rendu syndrome). Interventional radiologists are a key part of the treatment team in this complex disease, and a thorough understanding of the disease process is critical to providing good patient care. In this article, the authors review the disease course and its association with hereditary hemorrhagic telangiectasia, discusses the clinical evaluation and treatment of these complex patients, and outlines complications and follow-up.

Safety of endovascular treatment of chronic cerebrospinal venous insufficiency: a report of 240 patients with multiple sclerosis

PURPOSE

To evaluate the safety of outpatient endovascular treatment in patients with multiple sclerosis (MS) and chronic cerebrospinal venous insufficiency (CCSVI).

MATERIALS AND METHODS

A retrospective analysis was performed to assess complications occurring within 30 days of endovascular treatment of CCSVI. The study population comprised 240 patients; 257 procedures were performed over 8 months. The indication for treatment in all patients was symptomatic MS. Of the procedures, 49.0% (126 of 257) were performed in a hospital, and 51.0% (131 of 257) were performed in the office. Primary procedures accounted for 93.0% (239 of 257) of procedures, and repeat interventions accounted for 7% (18 of 257). For patients treated primarily, 87% (208 of 239) had angioplasty, and 11% (26 of 239) had stent placement; 5 patients were not treated. Of patients with restenosis, 50% (9 of 18) had angioplasty, and 50% (9 of 18) had stent placement.

RESULTS

After the procedure, all but three patients were discharged within 3 hours. Headache after the procedure was reported in 8.2% (21 of 257) of patients; headache persisted > 30 days in 1 patient. Neck pain was reported in 15.6% (40 of 257); 52.5% (21 of 40) of these patients underwent stent placement. Three patients experienced venous thrombosis requiring retreatment within 30 days. Sustained intraprocedural arrhythmias were observed in three patients, and two required hospital admission. One of these patients, who was being retreated for stent thrombosis, was hospitalized because of a stress-induced cardiomyopathy.

CONCLUSIONS

Endovascular treatment of CCSVI is a safe procedure; there is a 1.6% risk of major complications. Cardiac monitoring is essential to detect intraprocedural arrhythmias. Ultrasonography after the procedure is recommended to confirm venous patency and to identify patients experiencing acute venous thrombosis.

Ventilation/perfusion lung scintigraphy: what is still needed? A review considering technetium-99m-labeled macro-aggregates of albumin

Lung perfusion scintigraphy (LPS) with technetium-99m-labeled macro-aggregates of albumin (Tc-99m-MAA) is well established in the diagnostic of pulmonary embolism (PE). In the last decade, it was shown that single-photon emission computer tomography (SPECT) acquisition of LPS overcame static scintigraphy. Furthermore, there are rare indications for LPS, such as preoperative quantification of regional lung function prior to lung resection or transplantation, optimization of lung cancer radiation therapy, quantification of right-left shunt, planning of intra-arterial chemotherapy, and several rare indications in pediatrics. Moreover, LPS with Tc-99m-MAA is a safe method with low radiation exposure. PE can also be diagnosed by spiral computer tomography (CT), ultrasound, magnetic resonance angiography, or pulmonary angiography (PA, former gold standard). The present review considers all these methods, especially spiral CT, and compares them with LPS with respect to sensitivity and specificity and gives an overview of established and newer publications. It shows that LPS with Tc-99m-MAA represents a diagnostic method of continuing value for PE. In comparison with spiral CT and/or PA, LPS is not to be defeated as mentioned also by the most actual Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II reports. This applies in particular to chronic or recurring embolisms, whereas currently spiral CT may be of greater value for major or life-threatening embolisms. At present, LPS cannot be replaced by other methods in some applications, such as pediatrics or in the quantification of regional pulmonary function in a preoperative context or prior to radiation therapy. LPS still has a place in the diagnostics of PE and is irreplaceable in several rare indications as described earlier.

Catheter-Induced Pulmonary Artery Dissection and Contrast Extravasation During Pulmonary Angiography

Pulmonary artery injury during pulmonary angiography is an uncommon complication. We describe two cases of iatrogenic pulmonary artery extravasation that resulted from the use of pigtail catheters for pulmonary angiography. No further complications occurred and no treatment was necessary in either case. Thus, mild contrast extravasation appears to be a self-limited complication that likely requires little more than short-term observation.

Venous thrombosis in children

The advances in pediatric tertiary care have resulted in a decrease in the mortality of children with serious underlying conditions. Consequently, there has been an increase in previously rare complications of therapy in children, including venous thrombosis. Although there is a paucity of properly designed trials in the field of pediatric thrombosis, many advances have been made over the past 15 years. Venous thrombosis in children has been the subject of many reviews. This review is an update of the available evidence in the management of venous thrombosis in children, excluding thrombosis of the CNS.

Thoracic imaging in the ICU

Imaging in the ICU plays a crucial role in patient care. The portable chest radiograph (CXR) is the most commonly requested radiographic examination, and, despite its limitations, it often reveals abnormalities that may not be detected clinically. Recent advances in CT technology have made it possible to obtain diagnostic-quality images even in the most dyspneic patient. This article reviews the significant contribution thoracic imaging makes in diagnosing and managing critically ill patients.

Multidetector computed tomographic angiography of the cardiovascular system

The introduction of multidetector computed tomography (MDCT) is considered a dramatic development in CT imaging that has direct implication in the imaging of various systems, in particular the cardiovascular system. The advantages of MDCT are an enormous increase in imaging acquisition speed, more coverage of the patient, and high spatial resolution. This article reviews the recent developments in CT angiography and discusses the clinical application relevant to diagnosis and endovascular treatment of cardiovascular diseases.

Contrast medium use

Various properties of iodinated contrast media (osmolality, ionic versus nonionic, and viscosity) may contribute to contrast-induced nephropathy (CIN). Therefore, the choice of contrast medium affects the risk for CIN. There is good evidence that low-osmolar contrast media are less nephrotoxic than high-osmolar contrast media in patients at increased risk for CIN who receive intra-arterial iodinated contrast. Current evidence suggests that nonionic isosmolar contrast presents the lowest risk for CIN in patients with chronic kidney disease (CKD), particularly in those patients with diabetes mellitus. Intra-arterial administration of contrast media may be associated with a greater risk for CIN above that observed with intravenous administration. The use of gadolinium or CO(2) as alternative contrast media to avoid the risk of nephrotoxicity cannot be substantiated by clinical trials and therefore cannot be recommended. Most studies show that, within a class, higher volumes (>100 mL) of iodinated contrast medium are associated with a higher risk for CIN. However, in patients at high risk, such as those with CKD and diabetes, even small volumes of contrast medium can have adverse effects on renal function.

Portopulmonary hypertension: hemodynamics, pulmonary angiography, and configuration of the heart

BACKGROUND

The goal of the present study was to examine the cardiac configuration and pulmonary vascular changes in patients with portopulmonary hypertension (PPHTN) and compare them with those of idiopathic pulmonary arterial hypertension (IPAH).

METHODS AND RESULTS

The subjects were 10 patients with PPHTN and 18 with IPAH. In PPHTN, the increases in the right ventricular end-diastolic volume index (89+/-19 vs 128+/-50 ml/m2; p=0.04), right end-systolic volume index (50+/-19 vs 95+/-47 ml/m 2; p=0.02) and right ventricular mass index (47+/-18 g/m2 vs 79+/-31; p=0.04) were low compared with IPAH. The decrease in the right ventricular ejection fraction was also low in PPHTN (45+/-10 vs 28+/-13%; p=0.01). The degree of sparse arborization and abrupt narrowing on wedged pulmonary angiography was moderate in PPHTN compared with IPAH. In PPHTN, the proximal pulmonary arteries were dilated near the segmental arteries, which were narrow in IPAH.

CONCLUSION

Changes in the configuration of the heart were moderate in PPHTN compared with those in IPAH. The degree of sparse arborization and abrupt narrowing were also moderate in PPHTN.

Acute Pulmonary Embolism: Imaging in the Emergency Department

Acute pulmonary embolism (PE) is a life-threatening condition that requires accurate diagnostic imaging. Morbidity and mortality that result from PE can be reduced significantly if appropriate treatment is initiated early; this makes timely diagnosis imperative. Historically, the gold standard for the imaging of PE has been pulmonary angiography. Rapid advances in radiology and nuclear medicine have led to this modality largely being replaced by noninvasive techniques, most frequently multidetector helical CT pulmonary angiography (CTPA). In cases in which CTPA is contraindicated, other modalities for diagnosis of PE include nuclear ventilation perfusion scanning, magnetic resonance pulmonary angiography, duplex Doppler ultrasonography for deep venous thrombosis, and echocardiography. This article reviews the literature on the role of these imaging modalities in the diagnosis of PE.

Bedside ultrasonography in the ICU: part 1

Ultrasonography has become an invaluable tool in the management of critically ill patients. Its safety and portability allow for use at the bedside to provide rapid, detailed information regarding the cardiovascular system and the function and anatomy of certain internal organs. Echocardiography can noninvasively elucidate cardiac function and structure. This information is vital in the management hemodynamically unstable patients in the ICU. In addition, ultrasonography has particular value for the assessment and safe drainage of pleural and intra-abdominal fluid and the placement of central venous catheters. A new generation of portable, battery-powered, inexpensive, hand-carried ultrasound devices have recently become available; these devices can provide immediate diagnostic information not assessable by physical examination alone and allow for ultrasound-guided thoracocentesis, paracentesis, and central venous cannulation. This two-part article reviews the application of bedside ultrasonography in the ICU.

Pulmonary thromboembolism in children

Pulmonary thromboembolism (PTE) is uncommonly diagnosed in the pediatric patient, and indeed often only discovered on autopsy. The incidence of pediatric PTE depends upon the associated underlying disease, diagnostic tests used, and index of suspicion. Multiple risk factors can be found including: peripartum asphyxia, dyspnea, haemoptysis, chest pain, dehydration, septicemia, central venous lines (CVLs), trauma, surgery, ongoing hemolysis, vascular lesions, malignancy, renal disease, foreign bodies or, uncommonly, intracranial venous sinus thrombosis, burns, or nonbacterial thrombotic endocarditis. Other types of embolism can occur uncommonly in childhood and need to be recognized, as the required treatment will vary. These include pulmonary cytolytic thrombi, foreign bodies, tumor and septic emboli, and post-traumatic fat emboli. No single noninvasive test for pulmonary embolism is both sensitive and specific. A combination of diagnostic procedures must be used to identify suspect or confirmed cases of PTE. This article reviews the risk factors, clinical presentation and treatment of pulmonary embolism in children. It also highlights the current diagnostic tools and protocols used to evaluate pulmonary embolism in pediatric patients.

Suspected acute pulmonary embolism: evaluation with multi-detector row CT versus digital subtraction pulmonary arteriography

PURPOSE

To determine diagnostic accuracy of four-channel multi-detector row computed tomography (CT) in emergency room and inpatient populations suspected of having acute pulmonary embolism (PE) who prospectively underwent both CT and pulmonary arteriography (PA).

MATERIALS AND METHODS

Patients referred for PA to assess suspected PE were eligible. Institutional review board approval and written informed consent were obtained. All patients underwent CT and PA within a 48-hour period. For CT, 4 x 2.5-mm collimation was used. Three readers independently evaluated each study for PE presence. PE status, vessel level, and lobar location were determined by means of majority rule, and interobserver agreement (kappa) was calculated for PE status, as assessed with each modality. Sensitivity and specificity of CT were calculated by using PA as the reference standard. Two radiologists later reviewed false-positive CT studies.

RESULTS

The study group comprised 93 patients (median age, 56 years; range, 19-88 years). Sensitivity, specificity, and accuracy of CT were 100%, 89%, and 91%, respectively. kappa values were 0.71 and 0.83 for CT and PA, respectively, and were not significantly different between modalities. At PA, 18 patients (19%) had PE at 50 vessel levels (five main and/or interlobar, 24 segmental, and 21 subsegmental), 17 (94%) of which had PE at multiple sites. At CT, 26 patients (28%) had PE at 71 vessel levels (24 main and/or interlobar, 33 segmental, and 14 subsegmental). Twenty patients (77%) had PE at multiple sites. Review of eight false-positive CT studies showed an appearance highly suggestive of acute PE in three patients, chronic PE in one, and no PE in three; one study was inconclusive. CT better demonstrated large-level vessel involvement (P < .01), while PA better demonstrated small-level vessel involvement (P < .01).

CONCLUSION

Multi-detector row CT has an accuracy of 91% in the depiction of suspected acute PE when conventional PA is used as the reference standard.

MR angiography with sensitivity encoding (SENSE) for suspected pulmonary embolism: comparison with MDCT and ventilation-perfusion scintigraphy

OBJECTIVE

The aim of our study was to determine the utility of time-resolved contrast-enhanced MR angiography combined with sensitivity encoding (SENSE) for patients with pulmonary embolism. SUBJECTS AND METHODS. Forty-eight consecutive patients (26 men and 22 women; age range, 27-73 years; mean age, 55 years) with suspected pulmonary embolism underwent chest radiography, contrast-enhanced MDCT, MR angiography with SENSE, ventilation-perfusion scintigraphy, and pulmonary angiography. MR angiography with SENSE was performed using IV administration of gadolinium contrast medium with a 3D turbo field-echo pulse sequence (TR/TE, 4.0/1.2; flip angle, 30 degrees ) on a 1.5-T scanner. Capabilities of diagnosing pulmonary embolism using MR angiography (data set A), contrast-enhanced MDCT (data set B), contrast-enhanced MDCT with MR angiography (data set C), ventilation-perfusion scintigraphy (data set D), and contrast-enhanced MDCT with ventilation-perfusion scintigraphy (data set E) were determined by receiver operating characteristic analysis, using the results of pulmonary angiography as the reference standard. The diagnostic capability of each data set was analyzed on a per-vascular zone and a per-patient basis with the McNemar test.

RESULTS

Sensitivity and specificity of data set A were 83% and 97%, respectively, on a per-vascular zone basis and 92% and 94%, respectively, on a per-patient basis. Specificity and accuracy of data set A were significantly higher than those of data set D on a per-patient basis (p < 0.05).

CONCLUSION

Time-resolved MR angiography with SENSE is effective for the diagnosis of pulmonary embolism.

Diagnosis of pulmonary embolism with various imaging modalities

Pulmonary embolism (PE) is a major health concern that affects approximately 600,000 new patients annually. The diagnosis of PE can be difficult to make, and several imaging studies have been developed to aid in this process. Initial evaluation involves the acquisition of a chest radiograph. Findings on radiography, however, are often non-specific. The gold-standard study historically has been pulmonary angiography, with increasing diagnostic yield since the implementation of digital subtraction technology. This is an invasive procedure, however, but the incidence of major complications is low. Less invasive modalities have been developed and include ventilation-perfusion lung scans. These are used as one of the initial screening tests in evaluation of patients with suspected PE. The presence of a high-probability scan usually indicates the presence of a PE, although few patients have high probability scans. The test is significantly affected by underlying pulmonary disease or previous PE. Given this, ventilation-perfusion lung scans are limited as a primary diagnostic tool in the evaluation of suspected PE. Helical computed tomography (CT) is currently under much scrutiny as a diagnostic tool for PE. Currently a prospective, multicenter trial evaluating its efficacy (PIOPED II) has been initiated, but the results are pending. Preliminary reports suggest the helical CT and venous phase CT may become a first line study in patient evaluation. The diagnosis of PE is challenging and several imaging modalities are currently used to assist the clinician. Currently, multiple modalities are often required to make the diagnosis. With the advent of new technology and improved imaging techniques, the diagnosis of PE will become easier.

CT angiography for diagnosis of pulmonary embolism: state of the art

In daily clinical routine, computed tomography (CT) has practically become the first-line modality for imaging of pulmonary circulation in patients suspected of having pulmonary embolism (PE). However, limitations regarding accurate diagnosis of small peripheral emboli have so far prevented unanimous acceptance of CT as the reference standard for imaging of PE. The development of multi-detector row CT has led to improved visualization of peripheral pulmonary arteries and detection of small emboli. The finding of a small isolated clot at pulmonary CT angiography, however, may be increasingly difficult to correlate with results of other imaging modalities, and the clinical importance of such findings is uncertain. Therefore, the most realistic scenario to measure efficacy of pulmonary CT angiography when PE is suspected may be assessment of patient outcome. Meanwhile, the high negative predictive value of a normal pulmonary CT angiographic study and its association with beneficial patient outcome has been demonstrated. While the introduction of multi-detector row technology has improved CT diagnosis of PE, it has also challenged its users to develop strategies for optimized contrast material delivery, reduction of radiation dose, and management of large-volume data sets created at those examinations.

Risk of Pulmonary Embolism After Negative MDCT Pulmonary Angiography Findings

OBJECTIVE

The purpose of our study was to determine the risk of pulmonary embolism in patients who have negative MDCT pulmonary angiography findings.

SUBJECTS AND METHODS

In this prospective study, one hundred two consecutive patients with suspected pulmonary embolism underwent MDCT pulmonary angiography. Scans were reviewed jointly by two observers and findings recorded by consensus. Observers noted whether pulmonary embolism or other disease was present. No pulmonary embolism was seen in 85 patients (52 men and 33 women; age range, 20-94 years; mean age, 60 years) who were followed up for a mean of 9 months (range, 4-13 months) for evidence of subsequent pulmonary embolism.

RESULTS

One patient had a diagnosis of pulmonary embolism made within 3 weeks of undergoing CT pulmonary angiography. MDCT pulmonary angiography showed additional potentially significant findings in 76% of patients; 47% of these findings were not suspected on chest radiography.

CONCLUSION

The risk of pulmonary embolism at a mean of 9 months after negative MDCT pulmonary angiography findings is 1%. In our study of patients without pulmonary embolism, MDCT pulmonary angiography revealed other causes for individual patients' signs or symptoms in most cases.

Diagnosing pulmonary embolism: a question of too much choice?

The diagnosis of pulmonary embolism (PE) is difficult with many patients treated without the disease or left untreated without an adequate diagnostic work up. Recent advances in PE diagnosis are reviewed. The use of risk stratification in PE diagnosis is strongly recommended and evidence on how it can best be performed summarized. The Ginsberg/Wells stratification rule is recommended currently as the best validated rule. Computed tomographic pulmonary angiography (CTPA) was found to have quite poor sensitivity and to be poorly validated. It is recommended as adequate as a positive test in moderate/high risk groups and an exclusionary test in low risk groups or where an adequate alternative diagnosis is found. For D-Dimer tests the only test with adequate sensitivity and validation in management studies is the VIDASCopyright D-Dimer. This is in low/intermediate risk groups in the ED population. The Simpli-RedCopyright test is also reviewed but is too insensitive for most populations. Echocardiography: this is good in compromised patients as it is a bedside test which when negative virtually excludes PE. If positive in the right setting it has a high positive predictive value. A negative echocardiogram predicts a benign clinical course for PE. The rest of the paper details the authors approach to integrating these new techniques with established algorithms and where progress is likely to occur in the next few years. These include improvements in CTPA (plus the addition of CT venography), new point of care D-Dimer tests, better risk stratification rules and integration of new strategies with artificial neural networks or computerized guidelines.

Review article: Effects of radiographic contrast media on the lung

The pulmonary adverse effects of intravascular use of water soluble radiographic contrast media (RCM) include bronchospasm, pulmonary oedema and increase in the pulmonary arterial blood pressure (Ppa). Symptomatic bronchospasm is rare but subclinical increase in airways resistance is common after intravascular injection of RCM. Experimental studies have demonstrated that the low osmolar ionic dimer ioxaglate can induce significant bronchospasm in comparison with other types of RCM. Histamine and endothelin, which are potent bronchoconstrictors and released in response to the administration of RCM, do not seem to mediate the bronchospastic effect of RCM. Pretreatment with corticosteroids or antihistamine does not appear to prevent RCM induced bronchospasm, but the administration of beta(2) adrenergic agonist can abolish this adverse effect. RCM induced pulmonary oedema can be secondary to endothelial injury causing an increase in the permeability of the microcirculation. It may also occur in patients with incipient cardiac failure, when large doses of RCM particularly of the high osmolar type are used. A rise in Ppa induced by RCM seems to be secondary to an increase in pulmonary vascular resistance through direct effects on the pulmonary circulation. Low osmolar non ionic monomers induce the least changes in the pulmonary circulation and should be the contrast media of choice for intravascular use in patients with pulmonary hypertension. The mechanisms responsible for the effects of RCM on airway resistance and pulmonary circulation remain unclear. Intrabronchial administration of high osmolar water soluble RCM is dangerous and can induce severe bronchial irritation and pulmonary oedema. Low osmolar RCM are well tolerated by the lungs following aspiration with minimal histological reaction.

Venous thromboembolism in the intensive care unit

Most ICU patients have a significant number of risk factors for VTE. The high incidence of DVT in the ICU population and the recognition of a high incidence of PE at autopsy confirm this. We have alluded to the difficulty of clinical diagnosis of VTE and the need for diagnostic investigations. We have reviewed currently available diagnostic investigations with regard to their sensitivity and specificity and their practicability in ICU patients, and have formulated recommended diagnostic algorithms (Figs. 4 and 5). The most important factor in the management of VTE is prevention. In the ICU, all patients are at high risk for VTE, and therefore, at a minimum should receive subcutaneous prophylactic heparin unless it is contraindicated. Alternative methods of prophylaxis are available, and should be considered for patients who have contraindications to heparin.

Diagnosis of posttraumatic pulmonary embolism: is chest computed tomographic angiography acceptable?

BACKGROUND

Pulmonary angiography (PA-gram) has long been the accepted criterion standard for diagnosing pulmonary embolism (PE). Computed tomographic angiography has recently been advocated as an equivalent alternative to PA-gram. CT angiography is known to be insensitive for peripheral (segmental and subsegmental) emboli. We have previously found that a significant number of posttraumatic PEs occur early. We therefore hypothesized that because of the fragmentation of these early (soft) clots, posttraumatic PEs would be found disproportionately in the lung periphery.

METHODS

Trauma patients with PE confirmed by PA-gram were identified from our trauma database and medical records. PA-grams and reports were re-reviewed and the location of all emboli was documented.

RESULTS

We identified 45 patients, with an average age of 46 +/- 19 years; two thirds of the patients were men and 82% had a blunt mechanism of injury. Patients had PE diagnosed between days 0 and 57. Overall, PE was confined to segmental or smaller vessels in 27 (60%) patients and to subsegmental vessels in 7 (16%) patients. Twelve patients (27%) had a PE within the first 4 days. Furthermore, 32 patients (71%) had unilateral clot and 22 patients (48.9%) had clot confined to one region.

CONCLUSION

PE frequently occurs soon after injury. The majority of PEs after trauma are found peripherally (in segmental or subsegmental vessels). Right/left pulmonary artery embolisms are likely to be found only later in a trauma patient's course. Any diagnostic study used to diagnose pulmonary embolism in trauma patients must have sufficient resolution capacity to reliably detect segmental and subsegmental clot. A diagnostic modality such as CT scanning that is insensitive to peripheral embolisms may miss a significant number of posttraumatic PEs.

Spiral CT for pulmonary embolism: the paradigm has shifted

Computed tomography (CT) is rapidly becoming the first-line modality for imaging pulmonary embolism (PE). However, limitations for the accurate diagnosis of small peripheral emboli have prevented the unanimous embrace of CT as the new standard of reference for imaging PE, although the actual significance of isolated peripheral emboli is uncertain. At the same time, the high negative predictive value of CT pulmonary angiography for excluding clinically significant PE has been established. The introduction of multidetector-row spiral CT has greatly improved visualization of peripheral pulmonary arteries and detection of small emboli. Previous concerns regarding the use of spiral CT for the accurate diagnosis of peripheral pulmonary emboli should thus be overcome. Multidetector-row spiral CT has become a widely available and cost-effective technology and appears to have surpassed other imaging modalities for the accurate detection of central and peripheral PE. In this review, the authors assess the current role of spiral CT in the diagnostic algorithm of PE.

Current management of primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a rare disorder of the lung vasculature characterised by an increase in pulmonary artery pressure. Although the aetiology of this disease remains unknown, knowledge of the pathophysiology of the disease has advanced considerably. Diagnosis of PPH is largely by exclusion. The clinical symptoms associated with PPH are aspecific and similar to those seen in other cardiovascular and pulmonary diseases. Electrocardiography, echocardiography, pulmonary function tests, and a lung perfusion scan are necessary to exclude secondary forms of pulmonary hypertension and also help to confirm the diagnosis of PPH. A definite diagnosis of PPH is established by right-heart catheterisation which gives a precise measure of the blood pressure in the right side of the heart and the pulmonary artery, right ventricular function and cardiac output. Once a diagnosis of PPH is established, treatment involving drug therapy or surgery is commenced on the basis of the New York Heart Association functional class. Conventional treatment consists of lifetime administration of anticoagulants, oxygen, diuretics, and digoxin. Vasodilator therapy with calcium channel antagonists is indicated in patients who are 'vasoreactive' to acute vasodilator challenge as assessed by right-heart catheterisation. Promising results are obtained by continuous intravenous administration of epoprostenol (prostacyclin). Newer therapies for PPH include prostacyclin analogues, endothelin receptor antagonists, nitric oxide, phosphodiesterase-5 inhibitors, elastase inhibitors, and gene therapy. Surgical treatment consists of atrial septostomy, thromboendarterectomy, and lung or heart-lung transplantation.

CT pulmonary angiography in the detection of pulmonary emboli: a meta-analysis of sensitivities and specificities

OBJECTIVE

To determine the overall sensitivity and specificity for CT pulmonary angiography (CTPA) in the diagnosis of pulmonary emboli (PE) using a meta-analysis of the published literature.

MATERIALS AND METHODS

A Medline search was constructed to include all English language publications indexed in the Index Medicus from 1990 to 2000, which included the terms CT, PE and pulmonary angiography. Studies selected were designed principally to compare CTPA in the overall detection of PE as confirmed by an abnormal fluoroscopic pulmonary angiogram or a high probability V:Q scan. Results were corrected for the patient sample size in the respective studies prior to pooling the data. In the absence of an accepted technique for calculating a ROC curve in the meta-analysis of imaging studies, a previously untested theoretical technique was used to obtain a composite ROC curve.

RESULTS

Twelve studies of CTPA comprising a total of 1250 patients were analyzed. The overall sensitivity and specificity for CTPA after correction for study size was 74.1% and 89.5% with a range of 57-100% and 68-100%, respectively, for the detection of PE. No trend was detected with respect to the year of publication or sample size.

CONCLUSIONS

CTPA has acceptable sensitivity and specificity with a strong ROC curve making it a good first line investigation for PE.

Major pulmonary embolism: review of a pathophysiologic approach to the golden hour of hemodynamically significant pulmonary embolism

Major pulmonary embolism (PE) results whenever the combination of embolism size and underlying cardiopulmonary status interact to produce hemodynamic instability. Physical findings and standard data crudely estimate the severity of the embolic event in patients without prior cardiopulmonary disease (CPD) but are unreliable indicators in patients with prior CPD. In either case, the presence of shock defines a threefold to sevenfold increase in mortality, with a majority of deaths occurring within 1 h of presentation. A rapid integration of historical information and physical findings with readily available laboratory data and a structured physiologic approach to diagnosis and resuscitation are necessary for optimal therapeutics in this "golden hour." Echocardiography is ideal because it is transportable, and is capable of differentiating shock states and recognizing the characteristic features of PE. Spiral CT scanning is evolving to replace angiography as a confirmatory study in this population. Thrombolytic therapy is acknowledged as the treatment of choice, with embolectomy reserved for those in whom thrombolysis is contraindicated.

Current strategies for the diagnosis of pulmonary embolus

Venous thromboembolic disease (VTD), comprising venous thrombosis and pulmonary embolus, is responsible for innumerable deaths every day. Wide variance in its presentation and clinical manifestations and the resultant difficulties in achieving its diagnosis have confounded attempts to define optimal diagnostic and treatment strategies. Those strategies should be predicated on the understanding of the manifestations of VTD and of the attributes and interrelationship of the various modalities available for its diagnosis. This review will present an overview of the literature describing those modalities, their strengths and deficiencies, and their current value in algorithms for the diagnosis of VTD.

Computed tomography scan versus ventilation-perfusion lung scan in the detection of pulmonary embolism

This study compared the sensitivity and specificity of computed tomography (CT) scan and ventilation-perfusion (V-P) scan in detecting pulmonary embolism (PE) with pulmonary angiogram (AG) as the reference standard. Following a comprehensive search of the indexed medical literature, CT scan studies related to PE diagnosis were systematically evaluated to select those using AG as the reference standard and meeting specified methodologic criteria. Studies were further grouped by those reporting results for central PE findings only versus central and peripheral PE combined. A composite analysis of data derived from seven selected publications yielded sensitivity and specificity estimates for CT scan in detecting PE, which were statistically compared to the published results of a multi-center study reporting the sensitivity and specificity of the V-P scan with pulmonary AG as the reference standard. The calculated CT scan sensitivity was 77% for central PE only data and 81% for central and peripheral PE combined data, and the CT scan specificity was 91% and 98%, respectively. High-probability V-P scan sensitivity was 41% and specificity 97%; high- and intermediate-probability V-P scans combined yielded sensitivity 83% and specificity 52%. The sensitivity for PE detection was significantly greater for CT scan than for high-probability V-P scan; CT scan sensitivity was equivalent to V-P when high- and intermediate-probability scans were considered together. CT scan specificity for central and peripheral PE combined was equivalent to that of the high-probability V-P scan, but significantly greater than that of high- and intermediate-probability V-P scans considered together. Considering that only a small proportion of patients with suspected PE yield high-probability V-P scan results (which are usually indicative of PE), while as many as one-half of patients may yield intermediate-probability results (which are commonly not useful in PE diagnosis), our results suggest the CT scan may be an appropriate study for use by Emergency Physicians in the clinical evaluation of suspected PE.

Transesophageal echocardiography (TEE) in the critical care patient

Critically ill patients often pose special diagnostic problems to the clinician, intensified by limited physical examination findings and difficulty in transportation to imaging suites. Mechanical ventilation and the limited ability to position the patient make transthoracic echocardiography difficult. Transesophageal echocardiographic (TEE) imaging, however, is well suited to the critical care patient and is frequently used to evaluate hemodynamic status, the presence of vegetations, a cardioembolic source, and an intracardiac cause of hypoxemia. Using proper precautions, TEE can be performed safely in unstable patients and frequently leads to important changes in management.

Accuracy of CT angiography versus pulmonary angiography in the diagnosis of acute pulmonary embolism: evaluation of the literature with summary ROC curve analysis

RATIONALE AND OBJECTIVES

The authors performed this study to estimate, by using published data, the sensitivity and specificity of computed tomographic (CT) angiography in the evaluation of suspected acute pulmonary embolism (PE).

MATERIALS AND METHODS

Summary receiver operating characteristic (ROC) curve analysis was used to determine the sensitivity and specificity of CT angiography in the diagnosis of acute PE. Pulmonary angiography was used as the diagnostic standard of reference. The authors reviewed the results of 11 independent studies published in the English-language literature between January 1992 and June 1999.

RESULTS

The sensitivity of CT angiography in the diagnosis or exclusion of PE in the central pulmonary arteries (to the level of the segmental pulmonary arteries) ranged from 0.74 to 0.81 on the basis of specificities of 0.89-0.91. The sensitivity of CT angiography in the diagnosis or exclusion of PE in all pulmonary arteries (to the level of the subsegmental pulmonary arteries) was 0.68 on the basis of a specificity of 0.91.

CONCLUSION

On the basis of the studies in the current literature, most of which used 5.0-mm collimation and single-detector CT, CT angiography may be less accurate in the diagnosis of PE than previously reported. With improvements in data acquisition, particularly the use of thinner section collimation and multidetector CT, and in the increased use of workstations for data analysis, the accuracy and utility of CT angiography will require continued investigation.

Subsequent pulmonary embolism: risk after a negative helical CT pulmonary angiogram--prospective comparison with scintigraphy

PURPOSE

To determine whether a helical computed tomographic (CT) scan that is negative for pulmonary embolism (PE) is a sufficiently reliable criterion to safely withhold anticoagulation therapy.

MATERIALS AND METHODS

Patients with negative helical CT scans were prospectively compared with patients with negative or low-probability scintigrams. In a 460-bed university hospital and clinic, 1,015 adult patients underwent either scintigraphy or helical CT for possible PE for 25 months. Five hundred forty-eight patients who had negative images and were not receiving anticoagulation therapy were prospectively followed up for 3 months for clinical, new imaging, death certificate, or autopsy evidence of subsequent PE. Ninety-seven patients were lost to follow-up.

RESULTS

Subsequent PE was found in two (1.0%) of 198 patients with negative CT scans, none of 188 patients with negative ventilation-perfusion (V-P) scans, and five (3.1%) of 162 patients with low-probability V-P scans (not statistically significant). Patients in the helical CT group were hospitalized more often, had more severe disease, had more substantial PE risk factors, and had a higher death rate. No deaths were attributed to PE in either group.

CONCLUSION

The frequency of clinical diagnoses of PE after a negative CT scan was low and similar to that after a negative or low-probability V-P scan. Helical CT is a reliable imaging tool for excluding clinically important PE.

Modern management of pulmonary embolism

BACKGROUND

Pulmonary embolism is a significant cause of morbidity and death after operation. The introduction of new technologies in the diagnosis, and thrombolysis in the treatment, of pulmonary embolism has led to a need to reappraise the management of this condition.

METHODS

This review encompasses a comprehensive discussion of diagnostic modalities and therapeutic strategies used in the current management of pulmonary embolism. Relevant papers on the diagnosis and treatment of pulmonary embolism were identified from a Medline search for the period 1967-1998. Additional papers were derived from the reference lists of retrieved articles. Articles presenting prospectively gathered data have been referenced preferentially.

RESULTS AND CONCLUSION

Algorithms for the diagnosis and treatment of pulmonary embolism are presented.