Acute lung disease in the immunocompromised host

Chest complications in immunocompromised patients without acquired immunodeficiency syndrome (AIDS): differentiation between infectious and non-infectious diseases using high-resolution CT findings

AIM

To differentiate between infectious and non-infectious diseases occurring in immunocompromised patients without acquired immunodeficiency syndrome (AIDS) using high-resolution computed tomography (HRCT).

MATERIALS AND METHODS

HRCT images of 555 patients with chest complications were reviewed retrospectively. Infectious diseases (n=341) included bacterial pneumonia (n=123), fungal infection (n=80), septic emboli (n=11), tuberculosis (n=15), pneumocystis pneumonia (n=101), and cytomegalovirus pneumonia (n=11), while non-infectious diseases (n=214) included drug toxicity (n=84), infiltration of underlying diseases (n=83), idiopathic pneumonia syndrome (n=34), diffuse alveolar haemorrhage (n=8), and pulmonary oedema (n=5). Lung parenchymal abnormalities were compared between the two groups using the χ² test and multiple logistic regression analysis.

RESULTS

The χ2 test results showed significant differences in many HRCT findings between the two groups. Multiple logistic regression analysis results indicated the presence of nodules with a halo and the absence of interlobular septal (ILS) thickening were the significant indicators that could differentiate infectious from non-infectious diseases. ILS thickening was generally less frequent among most infectious diseases and more frequent among most non-infectious diseases, with a good odds ratio (7.887, p<0.001). The sensitivity and accuracy for infectious diseases in the absence of ILS thickening were better (70% and 73%, respectively) than those of nodules with a halo (19% and 48%, respectively), while the specificity in the nodules with a halo was better (93%) than that of ILS thickening (78%).

CONCLUSIONS

The presence of nodules with a halo or the absence of ILS thickening tends to suggest infectious disease. Specifically, ILS thickening seems to be a more reliable indicator.

Infection in Immunocompromised Hosts: Imaging

Immunocompromised patients are encountered with increasing frequency in clinical practice. In addition to the acquired immunodeficiency syndrome (AIDS), therapy for malignant disease, and immune suppression for solid organ transplants, patients are now rendered immunosuppressed by advances in treatment for a wide variety of autoimmune diseases. The number of possible infecting organisms can be bewildering. Recognition of the type of immune defect and the duration and depth of immunosuppression (particularly in hematopoietic and solid organ transplants) can help generate a differential diagnosis. Radiologic imaging plays an important role in the detection and diagnosis of chest complications occurring in immunocompromised patients; however, chest radiography alone seldom provides adequate sensitivity and specificity. High-resolution computed tomography (CT) can provide better sensitivity and specificity, but even CT findings may be nonspecific findings unless considered in conjunction with the clinical context. Combination of CT pattern, clinical setting, and immunologic status provides the best chance for an accurate diagnosis. In this article, CT findings have been divided into 4 patterns: focal consolidation, nodules/masses, small/micronodules, and diffuse ground-glass attenuation/consolidation. Differential diagnoses are suggested for each pattern, adjusted for both AIDS and non-AIDS immunosuppressed patients.

The Diagnostic Yield, Safety, and Impact of Flexible Bronchoscopy in Non-HIV Immunocompromised Critically Ill Patients in the Intensive Care Unit

Background

Flexible bronchoscopy (FB) and bronchoalveolar lavage (BAL) have major roles in the evaluation of parenchymal lung diseases in immunocompromised patients. Given the limited evidence, lack of standardized practice, and variable perception of procedural safety, uncertainty still exists on what constitutes the best approach in critically ill patients with immunocompromised state who present with pulmonary infiltrates in the era of prophylactic antimicrobials and the presence of new diagnostic tests.

Objective

To evaluate the diagnostic yield, safety and impact of FB and BAL on management decisions in immunocompromised critically ill patients admitted to the intensive care unit (ICU).

Methods

A prospective, observational study of 106 non-HIV immunocompromised patients admitted to the intensive care unit with pulmonary infiltrates who underwent FB with BAL.

Results

FB and BAL established the diagnosis in 38 (33%) of cases, and had a positive impact on management in 44 (38.3%) of cases. Escalation of ventilator support was not required in 94 (81.7%) of cases, while 18 (15.7%) required invasive and 3 (2.6%) required non-invasive positive pressure ventilation after the procedure. Three patients (2.6%) died within 24 h of bronchoscopy, and 46 patients (40%) died in ICU. Significant hypoxemia developed in 5% of cases.

Conclusion

FB can be safely performed in immunocompromised critically ill patients in the ICU. The yield can be improved when FB is done prior to initiation of empiric antimicrobials, within 24 h of admission to the ICU, and in patients with focal disease.

Diagnoses unveiled by early bronchoscopy in children with leukemia and pulmonary infiltrates

Pulmonary complications in children with leukemia often display nonspecific clinical and radiologic manifestations that lead to a delay in diagnosis. The role of fiberoptic bronchoscopy (FOB) and the proper time for its performance are controversial. The aim of our study was to evaluate the frequency and nature of specific diagnoses revealed by FOB. Children with leukemia submitted to FOB because of suspicion of pulmonary involvement (mainly pneumonia) were retrospectively analyzed. A total of 33 FOB procedures performed in 31 patients (20 males) with an average age of 9.4 years (range, 3.5 to 15 y) were evaluated. Microorganisms isolated from 21 (63.6%) bronchoalveolar lavage samples were mainly fungi including Candida in 13 cases (39.4%) and Aspergillus in 3 cases (9.1%). Isolation rate in 10 procedures performed within the first 3 days was 90%. Tracheobronchitis was present in > 50% of patients, pulmonary hemorrhage was seen in 7 (21.0%) patients, and leukemic infiltration was demonstrated in 2 patients (6.1%), among other conditions visualized by FOB. Complications of FOB were minimal and transient. Our study suggests that FOB is a useful and safe procedure in patients with leukemia and pulmonary infiltrates. The earlier the FOB was performed, the higher the isolation rate of causative agents. In addition, this procedure allowed the identification of noninfectious airway comorbidities. Further studies in regard to this issue are warranted.

Pulmonary complications in the non-HIV immunocompromised patient

The incidence of non-HIV immunocompromised patients is increasing. This is primarily due to improved immunosuppressive regimes for autoimmune diseases and also increases in stem cell transplantation. Pulmonary complications are a major cause of morbidity and mortality in these patients. Imaging is frequently used to assess these complications and to streamline therapies, as microbiological and/or pathological diagnosis can often be difficult, invasive, or protracted. This review provides the reader with a structured approach to interpret the imaging findings and differentiate between different infective and non-infective complications in these patients.

Guidelines for diagnosing and treating pulmonary infiltrates in children with acute leukaemia: impact of timely decisions

AIM

Children with leukaemia are at increased risk of pulmonary complications, often with unspecific clinical data, delayed diagnosis and a high mortality rate. We evaluated the usefulness of diagnostic-therapeutic guidelines (DTG) in which specific times for decision making were incorporated.

METHODS

Clinical charts of children with acute leukaemia and suspicion of pulmonary involvement were reviewed. Patients were allocated to group I if their diagnostic and therapeutic decisions were in accordance with the DTG, and to group II if not.

RESULTS

Children from group I (n=32) and group II (n=28) did not differ with respect to age (9.3+/-0.5 years old, mean+/-SEM), gender, type, risk and stage of leukaemia, anaemia and neutropenia. Total length of hospital stay and hospitalization due to the pulmonary disease were shorter in group I than in group II (14.8+/-2.1 vs. 28.5+/-3.7 days, p=0.0016; and 10.8+/-1.0 vs. 18.4+/-1.8 days, p=0.0003, respectively). Two patients (6.3%) died due to the pulmonary pathology in group I, and nine (32.1%, p=0.016) in group II.

CONCLUSIONS

Diagnostic-therapeutic guidelines that incorporate timely decisions constitute a useful algorithm to reduce the length of hospital stay and mortality in children with acute leukaemia and pulmonary infiltrates. A prospective study is needed to validate these results.

Guidelines for evaluation of new fever in critically ill adult patients: 2008 update from the American College of Critical Care Medicine and the Infectious Diseases Society of America

OBJECTIVE

To update the practice parameters for the evaluation of adult patients who develop a new fever in the intensive care unit, for the purpose of guiding clinical practice.

PARTICIPANTS

A task force of 11 experts in the disciplines related to critical care medicine and infectious diseases was convened from the membership of the Society of Critical Care Medicine and the Infectious Diseases Society of America. Specialties represented included critical care medicine, surgery, internal medicine, infectious diseases, neurology, and laboratory medicine/microbiology.

EVIDENCE

The task force members provided personal experience and determined the published literature (MEDLINE articles, textbooks, etc.) from which consensus was obtained. Published literature was reviewed and classified into one of four categories, according to study design and scientific value.

CONSENSUS PROCESS

The task force met twice in person, several times by teleconference, and held multiple e-mail discussions during a 2-yr period to identify the pertinent literature and arrive at consensus recommendations. Consideration was given to the relationship between the weight of scientific evidence and the strength of the recommendation. Draft documents were composed and debated by the task force until consensus was reached by nominal group process.

CONCLUSIONS

The panel concluded that, because fever can have many infectious and noninfectious etiologies, a new fever in a patient in the intensive care unit should trigger a careful clinical assessment rather than automatic orders for laboratory and radiologic tests. A cost-conscious approach to obtaining cultures and imaging studies should be undertaken if indicated after a clinical evaluation. The goal of such an approach is to determine, in a directed manner, whether infection is present so that additional testing can be avoided and therapeutic decisions can be made.

Comparison of CT features of Aspergillus and bacterial pneumonia in severely neutropenic patients

PURPOSE

To establish whether a relationship exists between computed tomography features of lung opacities in severely neutropenic patients and their Aspergillus or bacterial etiology.

METHODS

Computed tomography scans of 124 patients with lung opacities larger than 5 mm occurring during severe (neutrophils <500/mm) and prolonged (>7 d) neutropenia-induced by bone marrow transplantation and/or high-dose chemotherapy for hematologic malignancies-were reviewed. Invasive pulmonary aspergillosis or bacterial pneumonia were assessed by means of bronchoalveolar lavage, bronchial washing, trans-bronchial biopsy or (for bacteria only) blood cultures. Pulmonary opacities were classified as nodules or as consolidations. The presence of a perinodular ground-glass halo, the similarity of consolidations to a pulmonary infarction and the presence of cavitation (crescent-shaped or not) were recorded.

RESULTS

Invasive pulmonary aspergillosis was diagnosed in 68 patients; bacterial pneumonia in 56. Nodules (85) were more common than consolidations (39); their distribution among the patients with aspergillosis (52 nodules and 16 consolidations) and those with bacterial pneumonia (33 nodules and 23 consolidations) was even. Out of the 19 nodules surrounded by a halo 17 were due to aspergillosis. Nine consolidations (3 due to aspergillosis) were infarctionlike shaped. Cavitation appeared during 22/68 aspergillosis and 31/56 bacterial pneumonias; an air-crescent in 6 patients with aspergillosis and in 24 with bacterial pneumonia.

CONCLUSIONS

Although rare enough, the perinodular halo is highly specific for invasive aspergillosis. The nodular pattern of lung opacities, their similarity to a pulmonary infarction, the occurrence of cavitation and the air-crescent are not related to aspergillosis.

Autopsy-proven causes of death in lungs of patients immunocompromised by secondary interstitial pneumonia

PURPOSE

To present the more frequent associations found in autopsies of immunocompromised patients who developed secondary interstitial pneumonia as well as the risk of death (odds ratio) in having specific secondary interstitial pneumonia according to the cause of immunocompromise.

METHOD

From January 1994 to March 2004, 17,000 autopsies were performed at Hospital das Clínicas, São Paulo University Medical School. After examining the pathology report review, we selected 558 of these autopsies (3.28%) from patients aged 15 years or more with primary underlying diseases who developed radiologically diffuse infiltrates of the lung during their hospital course and died after secondary interstitial pneumonia (bronchopneumonia, lobar pneumonia, interstitial pneumonia, diffuse alveolar damage, pulmonary recurrence of underlying disease, drug-induced lung disease, cardiogenic pulmonary edema, or pulmonary embolism). Histology slides were reviewed by experienced pathologists to confirm or not the presence of secondary interstitial pneumonia. Statistical analysis included the Fisher exact test to verify any association between histopathology and the cause of immunocompromise; a logistic regression was used to predict the risk of death for specific histological findings for each of the independent variables in the model.

RESULTS

Secondary interstitial pneumonia was histologically represented by diffuse interstitial pneumonitis ranging from mild nonspecific findings (n = 213) to a pattern of diffuse alveolar damage (n = 273). The principal causes of immunocompromise in patients with diffuse alveolar damage were sepsis (136 cases), neoplasia (113 cases), diabetes mellitus (37 cases), and transplantation (48 cases). A high risk of death by pulmonary edema was found for patients with carcinoma of colon. Similarly, in patients with lung cancer or cachexia, A high risk of death by bronchopneumonia (OR = 3.6; OR = 2.6, respectively) was found. Pulmonary thromboembolism was associated with an appreciable risk of death (OR = 2.4) in patients with arterial hypertension. The risk of death was also high in patients presenting hepatic cancer (OR = 2.5) or steroid therapy (OR = 2.4) who developed pulmonary hemorrhage as the histological pattern of secondary interstitial pneumonia . The risk of death by lung metastasis was also elevated (OR = 1.6) for patients that were immunosuppressed after radiotherapy.

CONCLUSION

Patients with secondary immunosuppression who developed secondary interstitial pneumonia during treatment in hospital should be evaluated to avoid death by diffuse alveolar damage, pulmonary edema, bronchopneumonia, lung hemorrhage, pulmonary thromboembolism, or lung metastasis. The high-risk patients are those immunosuppressed by hematologic disease; those under steroid treatment; or those with colon or hepatic carcinoma, cachexia, or arterial hypertension.

Predictors of pulmonary zygomycosis versus invasive pulmonary aspergillosis in patients with cancer

BACKGROUND

Pulmonary zygomycosis (PZ), an emerging mycosis among patients with cancer, has a clinical manifestation similar to that of invasive pulmonary aspergillosis (IPA). Most cases of PZ in such patients develop as breakthrough infections if treatment with antifungal agents effective against Aspergillus species is administered. However, clinical criteria to differentiate PZ from IPA are lacking.

METHODS

We retrospectively reviewed the clinical characteristics and computed tomography (CT) findings for 16 patients with cancer and PZ and for 29 contemporaneous patients with cancer and IPA at the time of infection onset (2002-2004). Patients with mixed infections were excluded. Parameters predictive of PZ by univariate analysis were included in a logistic regression model.

RESULTS

Almost all patients with PZ (15 of 16) and IPA (28 of 29) had underlying hematological malignancies and typical risk factors for invasive mold infections. In logistic regression analysis of clinical characteristics, concomitant sinusitis (odds ratio [OR], 25.7; 95% confidence interval [CI], 1.47-448.15; P = .026) and voriconazole prophylaxis (OR, 7.76; 95% CI, 1.32-45.53; P = .023) were significantly associated with PZ. The presence of multiple (> or = 10) nodules (OR, 19.8; 95% CI, 1.94-202.29; P = .012) and pleural effusion (OR, 5.07; 95% CI, 1.06-24.23; P = .042) at the time that the patient underwent the initial CT were both independent predictors of PZ in the logistic regression analysis of radiological parameters. No difference occurred in the frequency of other CT findings suggestive of pulmonary mold infections (e.g., masses, cavities, halo sign, or air-crescent sign) between the 2 patient groups.

CONCLUSIONS

PZ in immunocompromised patients with cancer could potentially be distinguished from IPA on the basis of clinical and radiological parameters; prospective validation is needed.

AS. Comprometimento pulmonar nas leucemias: avaliação por tomografia computadorizada de alta resolução

OBJETIVO: Avaliar o papel da tomografia computadorizada de alta resolução (TCAR) no estudo de pacientes com leucemia e sintomas pulmonares, analisar os principais padrões encontrados e definir sua etiologia. MATERIAIS E MÉTODOS: Foi feito estudo retrospectivo das TCAR de 15 pacientes com diagnóstico confirmado de leucemia, em vigência de sintomas respiratórios. Os exames foram feitos com protocolo de alta resolução espacial, sendo avaliados por dois radiologistas, de forma independente. RESULTADOS: Os principais padrões observados foram: atenuação em vidro fosco (n = 11), consolidação (n = 9), nódulos do espaço aéreo (n = 3), espessamento de septos interlobulares (n = 3), padrão de árvore em brotamento (n = 3) e derrame pleural (n = 3). A infecção pulmonar foi o achado mais comum, observado em 12 pacientes, com a seguinte freqüência: pneumonia bacteriana (n = 6), infecção fúngica (n = 4), tuberculose pulmonar (n = 1) e infecção viral (n = 1). Os outros três pacientes mostraram infiltração leucêmica pleural (n = 1), linfoma (n = 1) e hemorragia pulmonar (n = 1). CONCLUSÃO: Concluiu-se que a TCAR é de grande importância na avaliação de pacientes com leucemia e neutropenia, com o objetivo de sugerir a causa do quadro pulmonar, avaliar a sua extensão e, em alguns casos, orientar procedimentos invasivos.

Radiologic approach to the diagnosis of infectious pulmonary diseases in patients infected with the human immunodeficiency virus

Nearly all patients infected with HIV experience respiratory infection at some point in the course of their illness. The spectrum of infections is varied and in order to generate a useful differential diagnosis based on imaging findings it is imperative for the radiologist to be aware of changing trends in disease prevalence and epidemiology, and the possible pathology related to new therapies. The characterization of the radiographic pattern in correlation with clinical findings and laboratory values (in particular the degree of immunosuppression as reflected in the CD4 level) would be helpful in narrowing the differential diagnosis of infectious pulmonary disease in HIV-positive patients. The most common radiologic patterns considered include areas of ground-glass, consolidation, nodules, and lymphadenopathy. We also include airways diseases and cavitary/cystic lesions because their prevalence has increased over recent years, and we also mention the significance of a normal chest radiograph in the suspicion of a lung infection. In most cases, the clinical and radiographic findings are sufficient for confident diagnosis. The radiologic diagnosis of thoracic infections in patients with AIDS has improved with the use of CT. The greatest value of CT is in excluding lung disease when the radiographic findings are equivocal and in confirming the presence of clinically suspected disease when the radiograph is normal.

Cystic and cavitary lung diseases: focal and diffuse

Cysts and cavities are commonly encountered abnormalities on chest radiography and chest computed tomography. Occasionally, the underlying nature of the lesions can be readily apparent as in bullae associated with emphysema. Other times, cystic and cavitary lung lesions can be a diagnostic challenge. In such circumstances, distinguishing cysts (wall thickness < or = 4 mm) from cavities (wall thickness > 4 mm or a surrounding infiltrate or mass) and focal or multifocal disease from diffuse involvement facilitates the diagnostic process. Other radiological characteristics, including size, inner wall contour, nature of contents, and location, when correlated with the clinical context and tempo of the disease process provide the most helpful diagnostic clues. Focal or multifocal cystic lesions include blebs, bullae, pneumatoceles, congenital cystic lesions, traumatic lesions, and several infectious processes, including coccidioidomycosis, Pneumocystis carinii pneumonia, and hydatid disease. Malignant lesions including metastatic lesions may rarely present as cystic lesions. Focal or multifocal cavitary lesions include neoplasms such as bronchogenic carcinomas and lymphomas, many types of infections or abscesses, immunologic disorders such as Wegener granulomatosis and rheumatoid nodule, pulmonary infarct, septic embolism, progressive massive fibrosis with pneumoconiosis, lymphocytic interstitial pneumonia, localized bronchiectasis, and some congenital lesions. Diffuse involvement with cystic or cavitary lesions may be seen in pulmonary lymphangioleiomyomatosis, pulmonary Langerhans cell histiocytosis, honeycomb lung associated with advanced fibrosis, diffuse bronchiectasis, and, rarely, metastatic disease. High-resolution computed tomography of the chest frequently helps define morphologic features that may serve as important clues regarding the nature of cystic and cavitary lesions in the lung.

Pulmonary considerations in the immunocompromised patient

The compromised patient who presents to the emergency department with pulmonary complaints is becoming a common occurrence. An immunocompromised state can result from a disease process such as HIV or from medications used to prevent graft rejection in solid organ recipients or to treat conditions such as collagen vascular disease. The emergency department physician should be familiar with the more common complications that can afflict this unique patient group. This article addresses the presentation, evaluation, and treatment of the more common pulmonary complications that can occur in solid organ transplant recipients, cancer patients, patients suffering from collagen vascular disease, and patients with HIV disease.

Diagnostic approach to the patient with diffuse lung disease

Detecting diffuse lung infiltrates on chest radiography is a common clinical problem. Many diverse pathological processes can cause diffuse lung disease. The presentation of these diseases can vary from acute to chronic and includes a side array of radiological patterns that are optimally evaluated on high-resolution computed tomography of the chest. In diagnosing diffuse lung disease, it is helpful to focus on a few pivotal parameters to narrow the broad differential diagnosis. We describe the diagnostic approach to a patient with diffuse lung disease usingthe following key parameters: tempo of the pathological process, characteristics of the radiological pattern, and clinical context.