Severe respiratory syncytial virus infection: clinical features, nosocomial acquisition and outcome

Update in postinfectious bronchiolitis obliterans

Postinfectious bronchiolitis obliterans (PiBO) is a rare and severe form of chronic obstructive lung disease caused by an infectious injury to the lower respiratory tract. The most commonly recognized inciting stimuli leading to PiBO are airway pathogens, such as adenovirus and Mycoplasma. PiBO is characterized by persistent and nonreversible airway obstruction, with functional and radiological evidence of small airway involvement. The literature has limited information on the aetiology, clinical profile, treatment, and outcome of PiBO.

Risk factors for the development of bronchiolitis obliterans in children with severe adenovirus pneumonia: A retrospective study with dose-response analysis

To investigate and analyze the relevant risk factors for bronchiolitis obliterans (BO) in children with severe adenovirus pneumonia, a retrospective study of children with severe adenovirus pneumonia was performed in 34 cases that developing BO and 105 cases not developing BO in Children's hospital of Chongqing Medical University from January 2015 to February 2019. The multivariate logistic regression analysis was used to identify factors which were significantly associated with development of BO after the univariate analysis, and receiver operating characteristic (ROC) curve analysis was performed to find out the cut-off value for the significant relevant factors. A nonlinear dose-response relationship between risk factors and the risk of BO was assessed by restricted cubic spline model. Three factors were independently associated with development of BO, which were length of fever (OR 1.129, 95% CI 1.033-1.234), dyspnea (OR 3.922, 95% CI 1.060-14.514) and invasive mechanical ventilation (OR 6.861, 95% CI 1.854-25.387). The cut-off value of length of fever were 10.5 days. A linear dose-response relationship between length of fever and occurrence of BO was observed (P = .57 for nonlinearity). Children with severe adenovirus pneumonia who have a longer duration of fever (especially more than 10.5 days), have dyspnea or require invasive mechanical ventilation in the acute phase are more likely to develop BO.

Post-infectious Bronchiolitis Obliterans: HRCT, DECT, Pulmonary Scintigraphy Images, and Clinical Follow-up in Eight Children

Background: Bronchiolitis obliterans (BO), first mentioned in 1901, is a severe and rare chronic lung disease in children. BO has various etiologies and the most common in children is post-infectious BO (PIBO). High resolution CT (HRCT) is an often-used image tool for the diagnosis of BO, and pulmonary scintigraphy is an alternative tool that can functionally evaluate BO. Recently, dual-energy computed tomography (DECT) have also been applied to BO for its accuracy and safety. Here we described the characteristics of HRCT, pulmonary scintigraphy, DECT, and the clinical profiles of patients with PIBO. Methods: This is a retrospective and descriptive study. Data were collected from patients diagnosed with PIBO from 2014 to 2019 in the Pediatric Cardiopulmonary Outpatient Clinics of Kaohsiung Medical University Hospital. The diagnosis was based on clinical, chest X-ray, and HRCT findings. Clinical profile, radiological characteristics, and images of pulmonary scintigraphy were documented. Results: Eight children (4 boys and 4 girls) were diagnosed with PIBO at a mean age of 25.8 months (range 15 to 41 months). Two of our patients developed pulmonary hypertension. The most common HRCT finding is mosaic pattern, where match ventilation/perfusion (V/Q) defects is a general feature in pulmonary scintigraphy. DECT pulmonary blood vasculature images revealed various degrees of decreased perfusion and is compatible with the decreased perfusion on pulmonary scintigraphy. Conclusion: The therapeutic strategy of PIBO is still lacking of standardization. HRCT and V/Q scans are important image tools in diagnosis and follow-up of BO. DECT may be used in BO patients as it has no additional radiation exposure and add value on functional information of HRCT.

Post-infectious bronchiolitis obliterans

Bronchiolitis obliterans is a rare and severe chronic lung disease resulting from a lower respiratory tract lesion. It may occur after a bone marrow or lung transplantation, infectious diseases, or less frequently after inhaling toxic substances or after connective tissue diseases. Pathology, pathogenesis, and molecular biology, as well as the best treatment of bronchiolitis obliterans, remain the subject of ongoing research. This review discusses our current knowledge of different areas of bronchiolitis obliterans associated with infectious lesions.

Vaccines for the common cold

BACKGROUND

The common cold is a spontaneously remitting infection of the upper respiratory tract, characterised by a runny nose, nasal congestion, sneezing, cough, malaise, sore throat, and fever (usually < 37.8º C). The widespread morbidity caused by the common cold worldwide is related to its ubiquitousness rather than its severity. The development of vaccines for the common cold has been difficult because of antigenic variability of the common cold virus and the indistinguishable multiple other viruses and even bacteria acting as infective agents. There is uncertainty regarding the efficacy and safety of interventions for preventing the common cold in healthy people. This is an update of a Cochrane review first published in 2011 and previously updated in 2013.

OBJECTIVES

To assess the clinical effectiveness and safety of vaccines for preventing the common cold in healthy people.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (September 2016), MEDLINE (1948 to September 2016), Embase (1974 to September 2016), CINAHL (1981 to September 2016), and LILACS (1982 to September 2016). We also searched three trials registers for ongoing studies and four websites for additional trials (February 2017). We included no language or date restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of any virus vaccines compared with placebo to prevent the common cold in healthy people.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated methodological quality and extracted trial data. We resolved disagreements by discussion or by consulting a third review author.

MAIN RESULTS

We found no additional RCTs for inclusion in this update. This review includes one RCT dating from the 1960s with an overall high risk of bias. The RCT included 2307 healthy participants, all of whom were included in analyses. This trial compared the effect of an adenovirus vaccine against placebo. No statistically significant difference in common cold incidence was found: there were 13 (1.14%) events in 1139 participants in the vaccines group and 14 (1.19%) events in 1168 participants in the placebo group (risk ratio 0.95, 95% confidence interval 0.45 to 2.02; P = 0.90). No adverse events related to the live vaccine were reported. The quality of the evidence was low due to limitations in methodological quality and a wide 95% confidence interval.

AUTHORS' CONCLUSIONS

This Cochrane Review was based on one study with low-quality evidence. We found no conclusive results to support the use of vaccines for preventing the common cold in healthy people compared with placebo. We identified a need for well-designed, adequately powered RCTs to investigate vaccines for the common cold in healthy people. Any future trials on medical treatments for preventing the common cold should assess a variety of virus vaccines for this condition. Outcome measures should include common cold incidence, vaccine safety, and mortality related to the vaccine.

Vaccines for the common cold

BACKGROUND

The common cold is a spontaneously remitting infection of the upper respiratory tract, characterised by a runny nose, nasal congestion, sneezing, cough, malaise, sore throat and fever (usually < 37.8˚C). The widespread morbidity it causes worldwide is related to its ubiquitousness rather than its severity. The development of vaccines for the common cold has been difficult because of antigenic variability of the common cold virus and the indistinguishable multiple other viruses and even bacteria acting as infective agents. There is uncertainty regarding the efficacy and safety of interventions for preventing the common cold in healthy people.

OBJECTIVES

To assess the clinical effectiveness and safety of vaccines for preventing the common cold in healthy people.

SEARCH METHODS

We searched CENTRAL (2012, Issue 12), MEDLINE (1948 to January week 1, 2013), EMBASE (1974 to January 2013), CINAHL (1981 to January 2013) and LILACS (1982 to January 2013).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of any virus vaccines to prevent the common cold in healthy people.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated methodological quality and extracted trial data. Disagreements were resolved by discussion or by consulting a third review author.

MAIN RESULTS

This review included one RCT with 2307 healthy participants; all of them were analysed. This trial compared the effect of an adenovirus vaccine against a placebo. No statistically significant difference in common cold incidence was found: there were 13 events in 1139 participants in the vaccines group and 14 events in 1168 participants in the placebo group; risk ratio (RR) 0.95, 95% confidence interval (CI) 0.45 to 2.02, P = 0.90). No adverse events related to the live vaccine were reported.

AUTHORS' CONCLUSIONS

This Cochrane review has found a lack of evidence on the effects of vaccines for the common cold in healthy people. Only one RCT was found and this did not show differences between comparison groups; it also had a high risk of bias. There are no conclusive data to support the use of vaccines for preventing the common cold in healthy people. We identified the need for well-designed, adequately powered RCTs to investigate vaccines for the common cold in healthy people. Unless RCTs provide evidence of a treatment effect and the trade-off between potential benefits and harms is established, policy-makers, clinicians and academics should not recommend the use of vaccines for preventing the common cold in healthy people. Any future trials on medical treatments for preventing the common cold should assess a variety of virus vaccines for this condition. Outcome measures should include common cold incidence, vaccine safety and mortality related to the vaccine.

Virus respiratorio sincitial, metapneumovirus y virus parainfluenza humanos: cuadro clínico y fisiopatología

El VRSh causa la mayor parte de las bronquiolitis del lactante, infecciones respiratorias bajas que provocan trastornos respiratorios obstructivos y sibilancias. Los factores relacionados con las características del paciente (prematuridad, enfermedades asociadas, predisposición genética), con el virus (VRShA, genotipo, etc.) o el ambiente (contaminación, tabaquismo, etc.) son determinantes en la génesis de las bronquiolitis y determinan su gravedad. La mortalidad de la bronquiolitis es del 0,005-0,2% dependiendo de las características del paciente. No se conoce la fisiopatología de la bronquiolitis por VRSh. El papel directo del virus sobre el epitelio, la inmadurez del pulmón del lactante y, como se ha demostrado recientemente, el papel de la reacción inflamatoria, son factores destacados. También es probable que haya mecanismos inmunopatológicos (anticuerpos IgE, respuesta CD4+ Th2, etc.) que intervengan en ciertas bronquiolitis. La inmunidad anti-VRSh nunca llega a ser completa y las reinfecciones son frecuentes en los niños pequeños y las personas de edad avanzada, en quienes la infección por el VRSh representa aproximadamente el 5% de las afecciones respiratorias bajas. Con frecuencia se presentan con un cuadro de neumopatía infecciosa atípica con signos de bronquiolitis. Las infecciones debidas al VPIh3 suelen manifestarse por bronquiolitis, y las infecciones secundarias al VPIh1 y al 2 por laringotraqueítis. No se conoce bien la expresión clínica de las infecciones por VPIh4. El MPVh causa bronquiolitis comparables en todos sus aspectos a las que origina el VRSh.

Clinical prediction rule to diagnose post-infectious bronchiolitis obliterans in children

RATIONALE

Infant pulmonary function testing has a great value in the diagnosis of post-infectious bronchiolitis obliterans (BOs), because of characteristic patterns of severe and fixed airway obstruction. Unfortunately, infant pulmonary function testing is not available in most pediatric pulmonary centers.

OBJECTIVE

To develop and validate a clinical prediction rule (BO-Score) to diagnose children under 2 years of age with BOs, using multiple objectively measured parameters readily available in most medical centers.

METHODS

Study subjects, children under 2 years old with a chronic pulmonary disease assisted at R. Gutierrez Children's Hospital of Buenos Aires. Patients were randomly divided into a derivation (66%) and a validation (34%) set. ROC analyses and multivariable logistic regression included significant clinical, radiological, and laboratory predictors. The main outcome measure was a diagnosis of BOs. The performance of the BO-Score was tested on the validation set.

RESULTS

Hundred twenty-five patients were included, 83 in the derivation set and 42 in the validation set. The BO-Score (area under ROC curve = 0.96; 95% CI, 0.9-1.0%) was developed by assigning points to the following variables: typical clinical history (four points), adenovirus infection (three points), and high-resolution computed tomography with mosaic perfusion (four points). A Score > or =7 predicted the diagnosis of BOs with a specificity of 100% (95% CI, 79-100%) and a sensitivity of 67% (95% CI, 47-80%).

CONCLUSIONS

The BO-Score is a simple-to-use clinical prediction rule, based on variables that are readily available. A BO-Score of 7 or more predicts a diagnosis of post-infectious BOs with high accuracy.

Strategies for prevention of RSV nosocomial infection

OBJECTIVE

To review the literature on respiratory syncytial virus (RSV) as a cause of nosocomial infections (NI) on neonatal intensive care units (NICUs) and pediatric wards, and the effectiveness of various containment strategies.

STUDY DESIGN

We conducted a literature review to define characteristics of RSV NI, and to evaluate the relative effectiveness of various infection containment programs, including the use of palivizumab on the reported incidence of RSV NI on NICUs and pediatric wards.

RESULT

Highly variable rates of RSV NI have not significantly changed since RSV was first identified. The evaluation of the effectiveness of containment strategies has relied on before/after study designs. Focus on rapid patient diagnosis, compliance of acceptable handwashing techniques and cohorting of patients and staff appears to form the backbone of most prevention and containment programs. When these or other measures have failed, the administration of palivizumab has been useful in halting the spread of RSV NI in children.

CONCLUSION

RSV NI continues to be prevalent in the NICU despite adoption of infection control programs. Preventive measures should be employed to lower the risk of RSV NI and, if identified, appropriate containment strategies should be rapidly implemented.

Insights into post-infectious bronchiolitis obliterans in children

New information contributing to our understanding of risk factors predisposing to bronchiolitis obliterans in children

Risk factors for the development of bronchiolitis obliterans in children with bronchiolitis

BACKGROUND

Bronchiolitis obliterans (BO) is an uncommon and severe form of chronic obstructive lung disease in children that results from an insult to the lower respiratory tract.

METHODS

A case-control study of children under the age of 3 years was performed in 109 cases and 99 controls to determine risk factors for the development of BO. Participants were evaluated by immunofluorescence viral tests, pulmonary function tests, and questions to assess tobacco and other exposures.

RESULTS

Bronchiolitis due to adenovirus (odds ratio (OR) 49, 95% confidence interval (CI) 12 to 199) and the need for mechanical ventilation (OR 11, 95% CI 2.6 to 45) were strongly and independently associated with an increased risk for BO. Factors not associated with post-infectious BO included age of the child, sex, and environmental tobacco exposure (either in utero or during infancy).

CONCLUSIONS

Adenovirus infection and need for mechanical ventilation are significant risk factors for developing BO in children. Further research is needed to determine why these risk factors are so strong and how they may contribute to the development of the disease.

Serious and lethal respiratory tract infections of viral etiology in children

Viruses may lead to serious and lethal pulmonary infections in immunocompetent and immunocompromised children. Series of children with acute respiratory distress syndrome and series of children requiring extracorporeal membrane oxygenation, as well as reported series of nosocomial viral illness, offer an insight into the extent of serious viral disease documented in the medical literature. Series of children with specific viral respiratory illness also will be reviewed, as will the means of diagnosis in these groups of patients. Copyright © 2000 by W.B. Saunders Company

Controversies in isolation and general infection control practices in pediatrics

Current controversies in pediatric isolation and infection control include correct application of standard precautions, importance of providing adequate staffing levels in intensive care units to prevent transmission of infectious agents, use of rapid diagnostic testing and best precautions to prevent transmission of respiratory syncytial virus, best methods to prevent transmission of multidrug-resistant organisms in acute care settings, and preventing transmission of infections to pregnant healthcare workers. Recommendations are evidence-based.

Respiratory viral infections among pediatric inpatients and outpatients in Taiwan from 1997 to 1999

The present study examined the association of specific virus infections with acute respiratory tract conditions among hospitalized and outpatient children in a subtropical country. A total of 2,295 virus infections were detected in 6,986 patients between 1997 and 1999, including infections caused by respiratory syncytial virus (RSV) (1.7%), parainfluenza virus (2.0%), influenza B virus (2.6%), adenovirus (4.0%), herpes simplex virus type 1 (4. 4%), influenza A virus (5.5%), and enterovirus (12.7%). There were 61 mixed infections, and no consistent seasonal variation was found. One or more viruses were detected among 24.8% of hospitalized patients and 35.0% of outpatients. The frequencies and profiles of detection of various viruses among in- and outpatients were different. The occurrence of enterovirus infections exceeded that of other viral infections detected in 1998 and 1999 due to outbreaks of enterovirus 71 and coxsackievirus A10. RSV was the most prevalent virus detected among hospitalized children, whereas influenza virus was the most frequently isolated virus in the outpatient group. Most respiratory viral infections (39.3%) occurred in children between 1 and 3 years old. RSV (P < 0.025) and influenza A virus (P < 0.05) infections were dominant in the male inpatient group. In addition, most pneumonia and bronchiolitis (48.4%) was caused by RSV among hospitalized children less than 6 months old. Adenovirus was the most common agent associated with pharyngitis and tonsilitis (45.5%). These data expand our understanding of the etiology of acute respiratory tract viral infections among in- and outpatients in a subtropical country and may contribute to the prevention and control of viral respiratory tract infections.

Le virus respiratoire syncytial: importance en pathologie, méthodes diagnostiques, traitement et prévention

Les bronchiolites à VRS sont fréquentes, épidémiques et nécessitent parfois l'hospitalisation des nourrissons, voire une réanimation.Le déterminisme des lésions pulmonaires est complexe, lié au virus et à la réaction immunitaire. Le traitement est symptomatique, et l'utilisation de la ribavirine est limitée aux formes sévères. Le diagnostic virologique doit être rapide, et la recherche immunologique directe des protéines virales est la technique la plus utilisée.

Lung function in infants with chronic pulmonary disease after severe adenoviral illness

OBJECTIVE

To evaluate pulmonary function and bronchodilator responses in young children with chronic pulmonary disease (CPD) after a severe adenoviral lower respiratory tract infection.

METHODS

Pulmonary function tests were performed in 13 patients (mean age, 1.32 +/- 0.8 years) with CPD and were compared with a control group of 13 healthy infants (mean age, 1.16 +/- 0.4 years).

RESULTS

Respiratory rate, peak tidal expiratory flow (PTEF), PTEF/tidal volume, absolute time up to PTEF, time percentage to PTEF, volume percentage for PTEF, and compliance and resistance of the respiratory system were significantly affected in the CPD group. Similarly, maximal flow at functional residual capacity (V'maxFRC) was 56.0 +/- 42 mL/s and 373 +/- 107 mL/s in the CPD and control groups, respectively (P =.001). No within-group differences with baseline values or between-group differences were noted in response to treatment with ipratropium bromide or albuterol.

CONCLUSION

Young children with CPD caused by adenovirus have pulmonary function changes characterized by severe obstruction and diminished lung distensibility not responsive to the administration of inhaled ipratropium bromide or albuterol.

Respiratory syncytial virus infection in tropical and developing countries

Little is known about the epidemiology of respiratory syncytial virus (RSV) infection in tropical and developing countries; the data currently available have been reviewed. In most studies, RSV was found to be the predominant viral cause of acute lower respiratory tract infections (ALRI) in childhood, being responsible for 27-96% of hospitalised cases (mean 65%) in which a virus was found. RSV infection is seasonal in most countries; outbreaks occur most frequently in the cold season in areas with temperate and Mediterranean climates and in the wet season in tropical countries with seasonal rainfall. The situation on islands and in areas of the inner tropics with perennial high rainfall is less clear-cut. The age group mainly affected by RSV in developing countries is children under 6 months of age (mean 39% of hospital patients with RSV). RSV-ALRI is slightly more common in boys than in girls. Very little information is available about the mortality of children infected with RSV, the frequency of bacterial co-infection, or the incidence of further wheezing after RSV. Further studies on RSV should address these questions in more detail. RSV is an important pathogen ill young children in tropical and developing countries and a frequent cause of hospital admission. Prevention of RSV infection by vaccination would have a significant impact on the incidence of ALRI in children in developing countries.

Acute respiratory distress syndrome caused by respiratory syncytial virus

Acute respiratory distress syndrome (ARDS) complicating severe respiratory syncytial virus (RSV) infection has been described in only a few infants. In contrast to the low mortality rates usually associated with RSV infections (< 5%), mortality rates in the range of 40-70% have been reported in pediatric patients with ARDS. However, studies on patients with ARDS are usually lumped with respect to causation, and the disease course of RSV-induced ARDS has not been previously studied. We examined the pulmonary function abnormalities of 37 infants with RSV-induced respiratory failure who were admitted to our pediatric intensive care unit for assisted ventilation. Measurements included respiratory mechanics, maximum expiratory flow-volume curves, and lung volumes. These allowed the calculation of a Murray lung injury score (modified for pediatric use) in which radiographic findings, ventilator settings, lung compliance, and blood gas results were considered. We identified ten infants with severe restrictive lung disease who fulfilled the clinical criteria for classification as ARDS. All had lung injury scores above 2.5, compatible with a diagnosis of ARDS. Twenty-seven infants had obstructive patterns of lung function consistent with a clinical diagnosis of RSV bronchiolitis. The patients with RSV-induced ARDS were significantly younger, and had a longer time on assisted ventilation (P < 0.05) and a higher proportion of predisposing illnesses (P < 0.05, odds ratio = 6.67, two-tailed Fisher's exact test) when compared with the patients who had obstructive disease. Only one patient (who had immunodeficiency) died, and all others were successfully managed on conventional mechanical ventilation. We conclude that RSV-induced respiratory failure represents a relatively benign cause of ARDS in pediatric patients. Our observations support the notion of differentiating ARDS with respect to causation, especially when novel and experimental therapy is considered and mortality rates are analyzed.

Atypical extrapulmonary presentations of severe respiratory syncytial virus infection requiring intensive care

The patterns and nature of a four-month epidemic of severe respiratory syncytial virus (RSV)-associated disease were analyzed using presenting, demographic, clinical, and therapeutic data. Of 218 infants with RSV infection admitted to Rainbow Babies and Childrens Hospital, 49 (22.4%), most born prematurely, entered the pediatric intensive care unit (PICU). Fluorescent antibody and/or enzyme-linked immunosorbent assay documented RSV infection. PICU patients underwent airway stabilization; 53.5% were intubated and evaluated for sepsis. Patients with positive bacterial cultures received antibiotics; 18% were given ribavirin. Patterns of infection included hypothermia, septic shock appearance, apnea, pneumonia, and wheezing due to bronchiolitis. The average age difference between patients with hypothermia (23.3 days) and those with pneumonia (11.2 months) was statistically significant. There were no significant differences in average age, gestational age at birth, number intubated, worst pH and PCO2, duration of intensive care, or treatment modalities between infants with bronchopulmonary dysplasia who received ribavirin and those who did not.

Respiratory syncytial virus infection among intubated adults in a university medical intensive care unit

Respiratory syncytial virus is the major cause of lower respiratory tract infection in children. Adults who are immunocompromised, aged, institutionalized, and/or have underlying medical diseases may be at risk for severe RSV infection. Intubated adults in an MICU were evaluated for evidence of RSV infection. Respiratory secretions were analyzed by cell culture and RSV EIA. Serologic testing was obtained. Respiratory secretions from MICU personnel with acute respiratory symptoms and patients admitted for pneumonia, asthma, or COPD also were screened. Five of 11 intubated patients had evidence of RSV infection. One of seven MICU employees and four of 48 ward patients had RSV-positive respiratory secretions. During community outbreaks of RSV infection, adults admitted to an MICU already may be infected with RSV; those admitted for other reasons are at risk for nosocomial infection. Patients occupying other hospital units and personnel may be instrumental in the nosocomial dissemination of RSV.

Screening for respiratory syncytial virus and assignment to a cohort at admission to reduce nosocomial transmission

To limit nosocomial spread of respiratory syncytial virus (RSV) infection, a longitudinal intervention trial was instituted. Nasal secretions or washes were screened for RSV antigen by enzyme-linked immunosorbent assay, and patients were assigned to an RSV-infected or an RSV-uninfected cohort. The baseline (preintervention) rate of 7.17 nosocomial cases of RSV per 1000 patient-days of care was used for comparison. Despite continued infections in the community after screening was initiated, there were no cases of RSV infection in 1880 patient-days of care for 3 months (p = 0.039). During the fourth month, an RSV-infected child was erroneously assigned to the RSV-uninfected cohort, and three nosocomial cases occurred--5.33/1000 patient-days of care (p = 0.286). Overall, there were three nosocomial RSV infections in 2443 patient-days of care in the 1987 season after screening was introduced--1.23/1000 patient-days of care (p = 0.026). In the subsequent RSV season, there was one nosocomial case--0.461/1000 patient-days of care for 3 months (p = 0.0074). During the same period, nosocomial cases of RSV were observed in the pediatric and neonatal intensive care units, where assignment to a cohort was not possible. We conclude that entry into a cohort at the time of admission, on the basis of prospective RSV screening by enzyme-linked immunosorbent assay, effectively reduces nosocomial transmission of RSV.

Use of extracorporeal membrane oxygenation in the treatment of respiratory syncytial virus bronchiolitis: the national experience, 1983 to 1988

In an effort to obtain data to provide the basis for the design of controlled clinical trials, we contacted all U.S. participants in the National ECMO Registry to assemble the national experience on the use of extracorporeal membrane oxygenation in respiratory syncytial virus bronchiolitis during the past 5 years. Twelve infants were treated at nine centers between 1983 and 1988. Eight had been born prematurely, and five had bronchopulmonary dysplasia. The mean age at onset of infection with respiratory syncytial virus was 108 +/- 102 days. The mean length of ventilator management before extracorporeal membrane oxygenation was 7.8 +/- 7.1 days. All infants had persistent hypoxemia with a mean arterial oxygen pressure of 39.2 +/- 11.7 torr (5.3 +/- 1.6 kPa) despite high ventilator pressures (mean airway pressure 19.7 +/- 6.4 cm H2O) and 100% inspired oxygen; six had air leak syndrome. Seven infants survived (58%). The mean duration of extracorporeal membrane oxygenation for survivors was 233 +/- 139 hours. Preexisting chronic lung disease did not predict a poor outcome: four of the five infants with bronchopulmonary dysplasia survived. Six of the survivors have subsequently achieved expected developmental milestones and one has slight motor delay. We conclude that, for infants with severe respiratory syncytial virus bronchiolitis whose condition deteriorates despite maximal ventilator management, extracorporeal membrane oxygenation may provide lifesaving support. The duration of successful treatment with this therapy may be longer than that for conventional neonatal indications, but excellent neurologic outcome may be expected in survivors.

Evaluation of a monoclonal antibody pool for rapid diagnosis of respiratory viral infections

A pool of monoclonal antibodies (MAbP) was evaluated both as a method of cell culture confirmation and as a rapid diagnostic screen for viral infection in respiratory secretions. The MAbP was used in a two-step fluorescent staining procedure on cells harvested from cultures (phase 1) and on exfoliated nasopharyngeal or tracheal cells (phase 2). Antibodies in the MAbP were directed against respiratory syncytial virus, adenoviruses, parainfluenza virus types 1, 2, and 3, and influenza viruses A and B. Individual antiviral antibody stains were used to identify specific viruses from MAbP-positive specimens. In phase 1 (cell culture confirmation only), 241 respiratory specimens were tested. MAbP sensitivity and specificity were 91 and 94%, respectively. In phase 2, 376 respiratory specimens were evaluated by direct staining of exfoliated cells, and these results were compared with results of cell culture isolation. The sensitivity and specificity of the MAbP used in direct specimen testing were 69 and 97%, respectively. These results indicate that the MAbP is highly specific and fairly sensitive for detection of seven different respiratory viruses in one testing procedure. The MAbP is a rapid screening technique for respiratory secretions and is potentially a cost-effective approach to viral detection.

Clinical considerations in the diagnosis of viral respiratory infections

Recent advances are allowing the transfer of sensitive and precise rapid viral antigen detection technology from sophisticated research laboratories to standardly equipped clinical diagnostic facilities. It is now possible to identify many viral respiratory pathogens directly from clinical specimens in less than 1 hr. Rapid antigen detection promises to be of the most value in the identification of respiratory viruses 1) for which antiviral therapy is available, 2) which can be prevented by employing isolation precautions, chemoprophylaxis, and/or immunization, 3) whose presence usually is associated with acute respiratory disease, not just asymptomatic colonization, and 4) which ordinarily are not associated with concomitant bacterial infection, and thus, whose early detection may allow withholding or withdrawing antibiotics. Based on these considerations, the relative usefulness of rapid viral antigen detection of commonly encountered respiratory pathogens will be discussed. In addition, the role of rapid viral detection in diagnosis of respiratory infections in high risk versus otherwise healthy individuals will be explored.

Rapid detection of respiratory syncytial virus in nasopharyngeal aspirates by a commercial enzyme immunoassay

A commercial enzyme immunoassay (EIA) for the rapid detection of respiratory syncytial virus (RSV) in respiratory secretions was evaluated by comparison with both virus isolation in HEp-2 cells and indirect immunofluorescence (IFA) staining of exfoliated respiratory cells. Initial examination of 80 nasopharyngeal aspirates collected from infants with acute respiratory illness showed that the RSV EIA was positive for 21 of 24 specimens positive by virus isolation or IFA (87.5% sensitivity) and negative for 53 of 56 specimens negative by virus isolation and IFA (95% specificity). The EIA appears to be an acceptable and more rapid test than virus isolation for the detection of RSV, especially for laboratories in which prompt inoculation of specimens is not always possible. IFA staining with commercial bovine anti-RSV serum was found to be the most sensitive and rapid test for the detection of RSV. However, three of four specimens positive by IFA and negative by virus isolation were not cultured under optimal conditions. In addition, the IFA test requires a highly trained technologist to interpret the staining results.