Severe exercise hypoxaemia with normal or near normal X-rays: a feature of Pneumocystis carinii infection

Pneumocystis jirovecii pneumonia in people living with HIV: a review

Pneumocystis jirovecii is a ubiquitous opportunistic fungus that can cause life-threatening pneumonia. People with HIV (PWH) who have low CD4 counts are one of the populations at the greatest risk of Pneumocystis jirovecii pneumonia (PCP). While guidelines have approached the diagnosis, prophylaxis, and management of PCP, the numerous studies of PCP in PWH are dominated by the 1980s and 1990s. As such, most studies have included younger male populations, despite PCP affecting both sexes and a broad age range. Many studies have been small and observational in nature, with an overall lack of randomized controlled trials. In many jurisdictions, and especially in low- and middle-income countries, the diagnosis can be challenging due to lack of access to advanced and/or invasive diagnostics. Worldwide, most patients will be treated with 21 days of high-dose trimethoprim sulfamethoxazole, although both the dose and the duration are primarily based on historical practice. Whether treatment with a lower dose is as effective and less toxic is gaining interest based on observational studies. Similarly, a 21-day tapering regimen of prednisone is used for patients with more severe disease, yet other doses, other steroids, or shorter durations of treatment with corticosteroids have not been evaluated. Now with the widespread availability of antiretroviral therapy, improved and less invasive PCP diagnostic techniques, and interest in novel treatment strategies, this review consolidates the scientific body of literature on the diagnosis and management of PCP in PWH, as well as identifies areas in need of more study and thoughtfully designed clinical trials.

Exercise-induced hypoxia among emergency department patients admitted for suspected COVID-19

BACKGROUND

Exercise-induced hypoxia (EIH) has been assessed at ED triage as part of an assessment of COVID-19; however, evidence supporting this practice is incomplete. We assessed the use of a 1-minute sit-to-stand exercise test among ED patients admitted for suspected COVID-19.

METHODS

A case note review of all ED patients assessed for suspected COVID-19 between March and May 2020 at Monklands University Hospital was conducted. Demographic characteristics, clinical parameters, baseline blood tests and radiographic findings, hospital length of stay, intensive care and maximum oxygen requirement were obtained for those admitted. Using logistic regression, the association between EIH at admission triage and COVID-19 diagnosis was explored adjusting for confounding clinical parameters.

RESULTS

Of 127 ED patients admitted for possible COVID-19, 37 were ultimately diagnosed with COVID-19. 36.4% of patients with COVID-19 and EIH had a normal admission chest radiograph. In multivariate analysis, EIH was an independent predictor of COVID-19 (adjusted OR 3.73 (95% CI (1.25 to 11.15)), as were lymphocyte count, self-reported exertional dyspnoea, C-reactive peptide and radiographic changes.

CONCLUSIONS

This observational study demonstrates an association between EIH and a COVID-19 diagnosis. Over one-third of patients with COVID-19 and EIH exhibited no radiographic changes. EIH may represent an additional tool to help predict a COVID-19 diagnosis at initial presentation and may assist in triaging need for admission.

One minute sit-to-stand test as a potential triage marker in COVID-19 patients: A pilot observational study

Background

The crisis of critical care resource allocation during the novel coronavirus infectious disease 2019 (COVID-19) pandemic has underscored the importance of triage. COVID-19 is associated with increased hypoxemia and desaturation on exertion. We hypothesized that desaturation after 1-min sit-to-stand test (1MSTS), a validated field exercise test can serve as a potential marker for triage of COVID 19 patients.

Methods

Subjects with proven COVID 19 without hypoxemia on ambient air at presentation underwent the 1MSTS. The demographic details, clinical profile, pre and post-test vitals and pulse oximetric saturation was recorded and they were followed up for outcome throughout the hospital stay and after discharge.

Results

55 mild cases of COVID-19 and 6 cases of recovering severe COVID-19 were included. The mild cohort had a median age of 35 years (IQR, 27-41.5) and a median hospital stay of 16 days (IQR 14,20). The severe cohort had a median age of 47.5 years (IQR, 42.3,54.3) and median intensive care and hospital stays of respectively 9 (IQR, 7.5,9) and 23.5 (IQR, 21.5,27) days. The two cohorts showed median desaturations of 0% (IQR, 0.5-1) and 5.5% (IQR, 4.3-6) respectively. No subjects in the mild cohort needed oxygen therapy or escalation of care to intensive care.

Conclusions

Significant desaturation after 1-MSTSin severe COVID 19 patients demonstrates the potential role of 1-MSTS both in triage for planning care and as a discharge criteria from intensive care unit. However, larger prospective studies are warranted for its evaluation and establishment of relevant cut-offs.

Direct and indirect evidence of efficacy and safety of rapid exercise tests for exertional desaturation in Covid-19: a rapid systematic review

BACKGROUND

Even when resting pulse oximetry is normal in the patient with acute Covid-19, hypoxia can manifest on exertion. We summarise the literature on the performance of different rapid tests for exertional desaturation and draw on this evidence base to provide guidance in the context of acute Covid-19.

MAIN RESEARCH QUESTIONS

1. What exercise tests have been used to assess exertional hypoxia at home or in an ambulatory setting in the context of Covid-19 and to what extent have they been validated? 2. What exercise tests have been used to assess exertional hypoxia in other lung conditions, to what extent have they been validated and what is the applicability of these studies to acute Covid-19?

METHOD

AMED, CINAHL, EMBASE MEDLINE, Cochrane and PubMed using LitCovid, Scholar and Google databases were searched to September 2020. Studies where participants had Covid-19 or another lung disease and underwent any form of exercise test which was compared to a reference standard were eligible. Risk of bias was assessed using QUADAS 2. A protocol for the review was published on the Medrxiv database.

RESULTS

Of 47 relevant papers, 15 were empirical studies, of which 11 described an attempt to validate one or more exercise desaturation tests in lung diseases other than Covid-19. In all but one of these, methodological quality was poor or impossible to fully assess. None had been designed as a formal validation study (most used simple tests of correlation). Only one validation study (comparing a 1-min sit-to-stand test [1MSTST] with reference to the 6-min walk test [6MWT] in 107 patients with interstitial lung disease) contained sufficient raw data for us to calculate the sensitivity (88%), specificity (81%) and positive and negative predictive value (79% and 89% respectively) of the 1MSTST. The other 4 empirical studies included two predictive studies on patients with Covid-19, and two on HIV-positive patients with suspected pneumocystis pneumonia. We found no studies on the 40-step walk test (a less demanding test that is widely used in clinical practice to assess Covid-19 patients). Heterogeneity of study design precluded meta-analysis.

DISCUSSION

Exertional desaturation tests have not yet been validated in patients with (or suspected of having) Covid-19. A stronger evidence base exists for the diagnostic accuracy of the 1MSTST in chronic long-term pulmonary disease; the relative intensity of this test may raise safety concerns in remote consultations or unstable patients. The less strenuous 40-step walk test should be urgently evaluated.

Post-exertion oxygen saturation as a prognostic factor for adverse outcome in patients attending the emergency department with suspected COVID-19: a substudy of the PRIEST observational cohort study

BACKGROUND

Measurement of post-exertion oxygen saturation has been proposed to assess illness severity in suspected COVID-19 infection. We aimed to determine the accuracy of post-exertional oxygen saturation for predicting adverse outcome in suspected COVID-19.

METHODS

We undertook a substudy of an observational cohort study across 70 emergency departments during the first wave of the COVID-19 pandemic in the UK. We collected data prospectively, using a standardised assessment form, and retrospectively, using hospital records, from patients with suspected COVID-19, and reviewed hospital records at 30 days for adverse outcome (death or receiving organ support). Patients with post-exertion oxygen saturation recorded were selected for this analysis. We constructed receiver-operating characteristic curves, calculated diagnostic parameters, and developed a multivariable model for predicting adverse outcome.

RESULTS

We analysed data from 817 patients with post-exertion oxygen saturation recorded after excluding 54 in whom measurement appeared unfeasible. The c-statistic for post-exertion change in oxygen saturation was 0.589 (95% CI 0.465 to 0.713), and the positive and negative likelihood ratios of a 3% or more desaturation were, respectively, 1.78 (1.25 to 2.53) and 0.67 (0.46 to 0.98). Multivariable analysis showed that post-exertion oxygen saturation was not a significant predictor of adverse outcome when baseline clinical assessment was taken into account (p=0.368). Secondary analysis excluding patients in whom post-exertion measurement appeared inappropriate resulted in a c-statistic of 0.699 (0.581 to 0.817), likelihood ratios of 1.98 (1.26 to 3.10) and 0.61 (0.35 to 1.07), and some evidence of additional prognostic value on multivariable analysis (p=0.019).

CONCLUSIONS

Post-exertion oxygen saturation provides modest prognostic information in the assessment of selected patients attending the emergency department with suspected COVID-19.

TRIAL REGISTRATION NUMBER

ISRCTN Registry (ISRCTN56149622) http://www.isrctn.com/ISRCTN28342533.

What items should be included in an early warning score for remote assessment of suspected COVID-19? qualitative and Delphi study

BACKGROUND

To develop items for an early warning score (RECAP: REmote COVID-19 Assessment in Primary Care) for patients with suspected COVID-19 who need escalation to next level of care.

METHODS

The study was based in UK primary healthcare. The mixed-methods design included rapid review, Delphi panel, interviews, focus groups and software development. Participants were 112 primary care clinicians and 50 patients recovered from COVID-19, recruited through social media, patient groups and snowballing. Using rapid literature review, we identified signs and symptoms which are commoner in severe COVID-19. Building a preliminary set of items from these, we ran four rounds of an online Delphi panel with 72 clinicians, the last incorporating fictional vignettes, collating data on R software. We refined the items iteratively in response to quantitative and qualitative feedback. Items in the penultimate round were checked against narrative interviews with 50 COVID-19 patients. We required, for each item, at least 80% clinician agreement on relevance, wording and cut-off values, and that the item addressed issues and concerns raised by patients. In focus groups, 40 clinicians suggested further refinements and discussed workability of the instrument in relation to local resources and care pathways. This informed design of an electronic template for primary care systems.

RESULTS

The prevalidation RECAP-V0 comprises a red flag alert box and 10 assessment items: pulse, shortness of breath or respiratory rate, trajectory of breathlessness, pulse oximeter reading (with brief exercise test if appropriate) or symptoms suggestive of hypoxia, temperature or fever symptoms, duration of symptoms, muscle aches, new confusion, shielded list and known risk factors for poor outcome. It is not yet known how sensitive or specific it is.

CONCLUSIONS

Items on RECAP-V0 align strongly with published evidence, clinical judgement and patient experience. The validation phase of this study is ongoing.

TRIAL REGISTRATION NUMBER

NCT04435041.

Missed opportunity to diagnose HIV with Pneumocystis carinii pneumonia as its sequela

Pneumocystis carinii pneumonia (PCP) is an opportunistic infection of the lung occurring primarily in patients with HIV infection with a CD4 cell count <200 mm3, solid organ transplant recipients and those taking immunosuppressive therapy. The 1980s heralded the HIV pandemic, turning PCP into a major medical and public health problem worldwide. Manifestations of unusual infections such as pneumocystis and Kaposi's sarcoma, were, after all, the first signs of the emerging pandemic to be recognised and may indeed, be the presenting feature of a previously undiagnosed HIV infection. With the advent of pneumocystis chemoprophylaxis and the initiation of highly active antiretroviral therapy, there has been a decreased incidence in developed countries, but it remains high in developing countries. Unfortunately, late presentation of HIV remains a problem resulting in significant morbidity and mortality. The authors report the case of a new diagnosis of HIV infection in a 45-year-old woman, presenting with a dry cough, dyspnoea, unintentional weight loss and PCP. Two weeks after commencing highly active antiretroviral therapy, she was diagnosed with immune reconstitution inflammatory syndrome. Research shows that stigma and discrimination in the healthcare setting contributes to keeping individuals from accessing HIV prevention, care and treatment services and adopting key preventive behaviours. The barriers to HIV testing and stigma eradication in primary care will be explored as well as missed opportunities to diagnosis HIV in primary care in individuals presenting with signs and symptoms of immunosuppression, in this case shingles.

Time-related Decrease in Diffusion Capacity in HIV-infected Patients with Impaired Immune Function

The purpose of this study was to investigate acute and time-related changes in lung function, i.e. forced expiratory volume in 1 second (FEV1), vital capacity (VC) and transfer factor (KCO) in HIV-infected patients with CD4 cell counts less than 400 x 10(6)/l. 66 males with no history of HIV-related pulmonary symptoms participated in a prospective lung function study for 9 months with 3-month intervals between examinations. 15/66 patients (23%) developed acute pulmonary symptoms, i.e. dyspnea (n = 12), cough (n = 13), fever greater than 38 degrees C (n = 13) and interstitial infiltrates on the X-ray (n = 9). Among the 51 asymptomatic patients, a significant time-related decrease in KCO (median decrease of 7%) was found, whereas no significant change in FEV1 or VC was observed during the study. Baseline KCO, i.e. KCO at entry, was found to be significantly higher in the asymptomatic patients (102% predicted (pred.) than in those patients who developed pneumonia (88% pred.). Development of pulmonary symptoms was both followed by a significant decrease in KCO (median decrease 17%), FEV1 and VC. We therefore conclude that HIV-infected patients with impaired immune function have in the absence of pulmonary symptoms a decrease in KCO. In case of pneumonia an acute decrease in both KCO, FEV1 and VC occurs.

Pneumocystis pneumonia in HIV-positive adults, Malawi

In a prospective study of 660 HIV-positive Malawian adults, we diagnosed Pneumocystis jirovecii pneumonia (PcP) using clinical features, induced sputum for immunofluorescent staining, real-time PCR, and posttreatment follow-up. PcP incidence was highest in patients with the lowest CD4 counts but uncommon compared with incidences of pulmonary tuberculosis and bacterial pneumonia.

Pneumocystis carinii pneumonia in patients with and without HIV infection

Advances in the prevention and treatment of Pneumocystis carinii pneumonia in HIV infected patients have led to a decrease in the incidence and improved outcomes. Pneumocystis carinii pneumonia continues to be problematic in non-HIV infected immunocompromised patients.

Anatomical diagnostic protocol in evaluating chronic cough with specific reference to gastroesophageal reflux disease

Using the anatomic, diagnostic protocol, the cause of chronic cough can be determined 88% to 100% of the time, leading to specific therapy with success rates of 84% to 98%. Gastroesophageal reflux disease (GERD), along with postnasal drip syndrome (PNDS) and asthma, is one of the three most common causes of chronic cough in all age groups. When GERD is the cause of chronic cough, there may be no gastrointestinal (GI) symptoms up to 75% of the time, and, in these cases, the term "silent GERD" is used. The most sensitive and specific test for GERD is 24-hour esophageal pH monitoring. In interpreting this test, it is essential not only to evaluate the duration and frequency of the reflux episodes but also to determine the temporal relationship between reflux and cough events. Patients with normal standard reflux parameters still may have reflux diagnosed as the likely cause of cough if a temporal relationship exists. The definitive diagnosis of cough resulting from GERD can only be made if cough goes away with antireflux therapy. When 24-hour esophageal pH monitoring cannot be done, an empiric trial of antireflux medical therapy is appropriate when GERD is a likely cause of chronic cough. It is likely in the following settings: patients with prominent GI symptoms consistent with GERD and/or those with no GI complaints and normal chest x-rays, who are not taking angiotensin-converting enzyme inhibitors and who are not smoking, and in whom asthma and PNDS have been excluded. However, if empiric treatment fails, it cannot be assumed that GERD has been ruled out as a cause of chronic cough; rather, objective investigation for GERD is recommended, because the empiric therapy may not have been intensive enough or it may have failed. In treating patients with chronic cough resulting from GERD, cough has been reported to resolve with medical therapy 70% to 100% of the time. Mean time to recovery may take as long as 161 to 179 days, and patients may not start to get better for 2 to 3 months. In patients who fail to respond to maximal medical therapy, antireflux surgery can be successful.

Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia (PCP) remains an important complication of AIDS. Advances have been made in establishing the taxonomy of the organism but the life cycle of the organism and pathogenetic mechanisms of disease remain obscure. In HIV patients the incidence of PCP has decreased because of widespread use of prophylaxis and survival of those with PCP has improved with use of adjunctive corticosteroid therapy. Less toxic drug therapies are still needed as well as better noninvasive diagnostic techniques.

Pneumocystis carinii

Improved understanding of Pneumocystis carinii, in particular the widespread use of chemoprophylaxis, has resulted in a declining incidence of infection in patients infected with HIV since the late 1980s. Despite these advances, P. carinii pneumonia continues to represent an important cause of pulmonary disease in HIV-seropositive individuals who do not receive chemoprophylaxis or when breakthrough episodes occur. This article reviews the history, biology, clinical manifestations, prognostic markers, therapy, and chemoprophylaxis of P. carinii pneumonia in HIV-seropositive patients.

Pulmonary disease

This article has presented the reader with an overview of the pulmonary disorders that develop during the course of HIV disease with special emphasis on the more commonly encountered entities. This information is intended to prepare the clinician to recognize the hallmark characteristics of the various diseases as well as atypical features. Despite the advances in basic understanding of the clinicopathologic consequences of infection with HIV, a cure has not been realized. There has, however, been success in controlling some of the major pulmonary problems that adversely affect both the quality and the length of life for persons with AIDS. For most complications of HIV infection, prognosis ultimately depends not only on treatment of the specific problem, but also controlling the relentless process of progressive immunosuppression. Continued research into treatment or prevention of HIV infection itself is needed, but at present prevention, rapid diagnosis, and treatment of recognized problems remain an intermediary goal.

Simplified exercise test for the initial differential diagnosis of Pneumocystis carinii pneumonia in HIV antibody positive patients

BACKGROUND

This study was designed to evaluate the usefulness of a simplified exercise test in the differential diagnosis of Pneumocystis carinii pneumonia (PCP).

METHODS

Forty five subjects with antibodies against the human immunodeficiency virus (HIV) and pneumonia were included and divided into two groups: those with PCP and those with "other pneumonias" (non-PCP). The test involved pedalling for two minutes on a stretcher bed and was considered positive if SaO2 decreased by at least 3%.

RESULTS

During the exercise the mean(SE) SaO2 fell in patients with PCP from 88(4)% to 84(3)%, p < 0.01, whilst it improved slightly in subjects with non-PCP from 91(1)% to 93(3)%, p < 0.05. Sensitivity was 77% and specificity 91%.

CONCLUSIONS

This simple test seems potentially useful for the initial investigation of HIV antibody positive patients with pneumonia.

Efficient diagnosis of Pneumocystis carinii pneumonia

In patients with HIV infection the diagnosis of PCP is relatively simple when patients present late, with advanced pneumonia. The diagnosis becomes more difficult when patients present with minimal symptoms, are receiving specific prophylactic therapy or have had previous AIDS-related pulmonary diseases. A number of non-invasive tests, such as Gallium scanning, exercise-induced hypoxaemia, DTPA scanning and lung function testing have been developed to improve on the diagnostic value of clinical examination and the chest X-ray. Although each has its own particular advantages and disadvantages, the most efficient means of diagnosing PCP, in patients presenting with respiratory symptoms, is to use these investigations as part of a diagnostic algorithm, thereby maximizing resources and defining relative risks for different types of patients.

Cost effectiveness of noninvasive oxygen saturation measurement during exercise for the diagnosis of Pneumocystis carinii pneumonia

We assessed (1) the sensitivity and specificity of exercise oxygen saturation measurement (EOS) for the diagnosis of Pneumocystis carinii pneumonia (PCP); and (2) the cost of introducing this indirect diagnostic test compared with that of standard diagnostic strategies for PCP. In a prospective study, 85 HIV-infected patients with suspected PCP underwent EOS, followed by induced sputum (IS) and bronchoalveolar lavage (BAL) if IS was negative for P. carinii. The prevalence of PCP was 0.22, the sensitivity of IS was 0.6, and its specificity was perfect. The cost ratios of IS to BAL and EOS to BAL were 0.1 and 0.2, respectively. A desaturation of three points was the best cutoff point, giving perfect sensitivity and a specificity of 0.77. The cost analysis showed that the introduction of EOS into diagnostic strategies for PCP is highly justified when the local prevalence is low. Exercise oxygen saturation measurement is simple and safe, and the results are available rapidly; its sensitivity is perfect and its specificity good. Its economic utility depends on its cost and the local prevalence of PCP in the test population.

Diagnosis of Pneumocystis carinii pneumonia in HIV antibody positive patients by simple outpatient assessments

BACKGROUND

As increasing numbers of patients with immunosuppression induced by the human immunodeficiency virus (HIV) present with respiratory symptoms it is important to differentiate Pneumocystis carinii pneumonia from other chest diseases rapidly and start treatment early. The management of pneumocystis pneumonia could be improved if clinicians could diagnose this condition confidently on the basis of simple clinical assessments.

METHODS

Three hundred and eighteen patients with evidence of immunosuppression due to HIV infection and suspected pneumocystis pneumonia were investigated. A clinical history was taken and arterial blood gas analysis, chest radiography, oximetry during exercise, and sputum induction or bronchoscopy (or both) were performed.

RESULTS

Pneumocystis pneumonia was confirmed microscopically from induced sputum or bronchoalveolar lavage fluid in 154 patients; 118 had other chest disease. The remaining 46 patients had no definitive diagnosis. The best single independent predictors of a diagnosis of pneumocystis pneumonia were exercise induced oxygen desaturation and obvious interstitial infiltrates on the chest radiograph (odds ratios of 4.88 and 5.44 respectively). The symptom triad of exertional dyspnoea, cough, and fevers; the absence of pneumocystis pneumonia prophylaxis; and resting arterial hypoxaemia were less predictive (odds ratio 2.07, 3.72, and 0.69). An algorithm was developed that gave a positive predictive value for confirmed pneumocystis pneumonia of 95% and also identified those patients with a very small chance of having pneumocystis pneumonia (negative predictive value 85%).

CONCLUSIONS

The diagnosis of an initial episode of pneumocystis pneumonia can be confidently made in a large proportion of immunosuppressed patients with respiratory symptoms on the basis of clinical symptoms, the absence of prophylaxis, chest radiographic appearances, and oxygen desaturation during exercise as shown by oximetry. Using these simple features clinicians can rapidly assign patients to the appropriate type of management at presentation.

Thoracic magnetic resonance imaging in the evaluation of HIV-1/AIDS pneumonitis

Magnetic resonance imaging of the thorax was performed on ten occasions in eight HIV-positive patients with a clinical picture suggestive of Pneumocystis carinii pneumonia. The diagnosis of PCP was subsequently confirmed on six occasions. Patients without PCP had low MRI profusion scores, while four of six patients with PCP had MRI profusion scores greater than 6/21. Neither the chest roentgenogram appearance nor computer-generated T1 and T2 relaxation times could reliably distinguish between these two groups. Magnetic resonance imaging may be useful in the early and noninvasive diagnosis of PCP in HIV-positive patients.

The management of HIV-related illness in the emergency department

As the AIDS epidemic progresses, the number of ED patients with HIV-related illness will continue to increase. As reviewed in this article, much of the existing clinical research in HIV-related illness has an impact on the diagnostic and management issues that arise in the ED. Many of the patterns of disease, subtleties of diagnosis, and therapies unique to AIDS patients have already been greatly elucidated. However, as the recognition of this disease goes into only its second decade, many questions remain. Further studies are needed, for example, to improve physician assessment of HIV risk, to further identify discriminators of PCP and bacteremia, and to optimize strategies for disposition and outpatient management. In the future, in the areas of research and clinical care, emergency medicine will play an increasing important role in the front-line attack on this modern epidemic.

Diagnostic value of lung clearance of 99mTc DTPA compared with other non-invasive investigations in Pneumocystis carinii pneumonia in AIDS

Various non-invasive investigations were carried out in patients infected with HIV who had respiratory symptoms with and without pneumocystis pneumonia (with pneumonia, n = 13 (five smokers); without pneumonia, n = 22 (13 smokers]. These included chest radiography; lung function tests (forced expiratory volume in one second, forced vital capacity; transfer factor and coefficient for carbon monoxide); arterial blood gas tensions; arterial oxygen saturation at rest and on exercise; and lung clearance of diethylenetriaminepenta-acetic acid labelled with technetium-99m (99mTc DTPA). The effect of scan time (seven v 45 minutes from peak counts) and subtraction of background counts were examined. There were no significant differences between the two groups in lung function tests or arterial blood gas tensions at rest. The median clearance half time of inhaled 99mTc DTPA for the first seven minutes from peak counts was 7.2 minutes for patients with pneumocystis pneumonia and 22 minutes for those without. The median arterial oxygen desaturation on exercise was 5% in patients with pneumocystis pneumonia and 2% in those without. 99mTc DTPA lung clearance was better than the other non-invasive tests in discriminating pneumocystis pneumonia from other pulmonary disorders in patients positive for HIV. A short scan time of seven minutes was as sensitive and specific as the longer scan time of 45 minutes, and this allows the clearance of 99mTc DTPA to become a rapid screening test.

Pneumocystis carinii infections in HIV-infected children

Since 1981, 1200 children with acquired immunodeficiency syndrome have been reported to the Centers for Disease Control. Among these children, Pneumocystis carinii has been the leading cause of serious morbidity and mortality. This review discusses the epidemiology, diagnosis, and treatment of P. carinii.

Pulmonary disease in AIDS patients

Pulmonary disease remains a major complication of the human immunodeficiency virus (HIV). Over the past decade several changes in the pattern of disease have occurred. Pneumocystis carinii pneumonia (PCP) remains the most common opportunistic pathogen in AIDS patients, though its incidence on bronchoscopy has declined and empiric therapy often occurs without a specific diagnosis. Changes in the management of patients with PCP have included different dosages and routes of administration for chemotherapy, improved overall survival, and a recent increase in the number of patients surviving episodes of respiratory failure. In addition, infection with mycobacteria tuberculosis (M.Tb.) has emerged as a major public health problem. The pattern of M.Tb. is distinct from non-immunocompromised patients though response to therapy usually occurs.

The evolving challenge of Pneumocystis carinii. A deadly opportunist in AIDS

Considerable progress has been made in the identification and treatment of Pneumocystis carinii pneumonia related to acquired immunodeficiency syndrome (AIDS). Prophylaxis, either primary or secondary, represents a major advance and should be used appropriately by physicians caring for patients infected with human immunodeficiency virus. Yet with success come new challenges. Centers for treatment of AIDS that aggressively use prophylaxis have seen a shift toward severe illness due to other pathogens and generalized wasting. The strategies employed in combating P carinii pneumonia are likely to be tried against other AIDS-related infections.

AIDS and the lung. 4-- Non-invasive investigation of pulmonary disease in patients positive for the human immunodeficiency virus

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