Health care worker exposure to aerosolized ribavirin: biological and air monitoring

Effect of Nebuliser and Patient Interface Type on Fugitive Medical Aerosol Emissions in Adult and Paediatric Patients

BACKGROUND

Open circuit aerosol therapy is associated with the potential for fugitive emissions of medical aerosol. Various nebulisers and interfaces are used in respiratory treatments, including the recent consideration of filtered interfaces. This study aims to quantify fugitive medical aerosols from various nebuliser types, in conjunction with different filtered and non-filtered interfaces.

METHODS

For both simulated adult and paediatric breathing, four nebuliser types were assessed including; a small volume jet nebuliser (SVN), a breath enhanced jet nebuliser (BEN), a breath actuated jet nebuliser (BAN) and a vibrating mesh nebuliser (VMN). A combination of different interfaces were used including filtered and unfiltered mouthpieces, as well as open, valved and filtered facemasks. Aerosol mass concentrations were measured using an Aerodynamic Particle Sizer at 0.8 m and 2.0 m. Additionally, inhaled dose was assessed.

RESULTS

Highest mass concentrations recorded were 214 (177, 262) µg m^-3 at 0.8 m over 45-minute run. The highest and lowest fugitive emissions were observed for the adult SVN facemask combination, and the adult BAN filtered mouthpiece combination respectively. Fugitive emissions decreased when using breath-actuated (BA) mode compared to continuous (CN) mode on the BAN for the adult and paediatric mouthpiece combination. Lower fugitive emissions were observed when a filtered facemask or mouthpiece was used, compared to unfiltered scenarios. For the simulated adult, highest and lowest inhaled dose were 45.1 (42.6, 45.6)% and 11.0 (10.1,11.9)% for the VMN and SVN respectively. For the simulated paediatric, highest and lowest inhaled dose were 44.0 (42.4, 44.8)% and 6.1 (5.9, 7.0)% for the VMN and BAN CN respectively. Potential inhalation exposure of albuterol was calculated to be up to 0.11 µg and 0.12 µg for a bystander and healthcare worker respectively.

CONCLUSION

This work demonstrates the need for filtered interfaces in clinical and homecare settings to minimise fugitive emissions and to reduce the risk of secondary exposure to care givers.

Prevention and Treatment Strategies for Respiratory Syncytial Virus (RSV)

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract disease, especially in young children. Despite its global impact on healthcare, related to its high prevalence and its association with significant morbidity, the current therapy is still mostly supportive. Moreover, while more than 50 years have passed since the first trial of an RSV vaccine (which unfortunately caused enhanced RSV disease), no vaccine has been approved for RSV prevention. In the last two decades, our understanding of the pathogenesis and immunopathology of RSV have continued to evolve, leading to significant advancements in RSV prevention strategies. These include both the development of new potential vaccines and the successful implementation of passive immunization, which, together, will provide coverage from infancy to old age. In this review, we provide an update of the current treatment options for acute disease (RSV-specific and -non-specific) and different therapeutic approaches focusing on RSV prevention.

Investigation of Fugitive Aerosols Released into the Environment during High-Flow Therapy

BACKGROUND

Nebulised medical aerosols are designed to deliver drugs to the lungs to aid in the treatment of respiratory diseases. However, an unintended consequence is the potential for fugitive emissions during patient treatment, which may pose a risk factor in both clinical and homecare settings.

METHODS

The current study examined the potential for fugitive emissions, using albuterol sulphate as a tracer aerosol during high-flow therapy. A nasal cannula was connected to a head model or alternatively, a interface was connected to a tracheostomy tube in combination with a simulated adult and paediatric breathing profile. Two aerodynamic particle sizers (APS) recorded time-series aerosol concentrations and size distributions at two different distances relative to the simulated patient.

RESULTS

The results showed that the quantity and characteristics of the fugitive emissions were influenced by the interface type, patient type and supplemental gas-flow rate. There was a trend in the adult scenarios; as the flow rate increased, the fugitive emissions and the mass median aerodynamic diameter (MMAD) of the aerosol both decreased. The fugitive emissions were comparable when using the adult breathing profiles for the nasal cannula and tracheostomy interfaces; however, there was a noticeable distinction between the two interfaces when compared for the paediatric breathing profiles. The highest recorded aerosol concentration was 0.370 ± 0.046 mg m-3 from the tracheostomy interface during simulated paediatric breathing with a gas-flow rate of 20 L/min. The averaged MMAD across all combinations ranged from 1.248 to 1.793 µm by the APS at a distance of 0.8 m away from the patient interface.

CONCLUSIONS

Overall, the results highlight the potential for secondary inhalation of fugitive emissions released during simulated aerosol treatment with concurrent high-flow therapy. The findings will help in developing policy and best practice for risk mitigation from fugitive emissions.

Investigation of the Quantity of Exhaled Aerosols Released into the Environment during Nebulisation

BACKGROUND

Secondary inhalation of medical aerosols is a significant occupational hazard in both clinical and homecare settings. Exposure to fugitive emissions generated during aerosol therapy increases the risk of the unnecessary inhalation of medication, as well as toxic side effects.

METHODS

This study examines fugitively-emitted aerosol emissions when nebulising albuterol sulphate, as a tracer aerosol, using two commercially available nebulisers in combination with an open or valved facemask or using a mouthpiece with and without a filter on the exhalation port. Each combination was connected to a breathing simulator during simulated adult breathing. The inhaled dose and residual mass were quantified using UV spectrophotometry. Time-varying fugitively-emitted aerosol concentrations and size distributions during nebulisation were recorded using aerodynamic particle sizers at two distances relative to the simulated patient. Different aerosol concentrations and size distributions were observed depending on the interface.

RESULTS

Within each nebuliser, the facemask combination had the highest time-averaged fugitively-emitted aerosol concentration, and values up to 0.072 ± 0.001 mg m-3 were recorded. The placement of a filter on the exhalation port of the mouthpiece yielded the lowest recorded concentrations. The mass median aerodynamic diameter of the fugitively-emitted aerosol was recorded as 0.890 ± 0.044 µm, lower the initially generated medical aerosol in the range of 2⁻5 µm.

CONCLUSIONS

The results highlight the potential secondary inhalation of exhaled aerosols from commercially available nebuliser facemask/mouthpiece combinations. The results will aid in developing approaches to inform policy and best practices for risk mitigation from fugitive emissions.

Update in the treatment of non-influenza respiratory virus infection in solid organ transplant recipients

INTRODUCTION

Despite the improved outcomes in solid organ transplantation with regard to prevention of rejection and increased patient and graft survival, infection remains a common cause of morbidity and mortality. Respiratory viruses are a frequent and potentially serious cause of infection after solid organ transplantation. Furthermore, clinical manifestations of respiratory virus infection (RVI) may be more severe and unusual in solid organ transplant recipients (SOTRs) compared with the non-immunocompromised population. Areas covered: This article reviews the non-influenza RVIs that are commonly encountered in SOTRs. Epidemiologic and clinical characteristics are highlighted and available treatment options are discussed. Expert opinion: New diagnostic tools, particularly rapid molecular assays, have expanded the ability to identify specific RVI pathogens in SOTRs. This is not only useful from a treatment standpoint but also to guide infection control practices. More data are needed on RVIs in the solid organ transplant population, particularly regarding their effect on rejection and graft dysfunction. There is also a need for new antiviral agents active against these infections as well as markers that can identify which patients would most benefit from treatment.

Precautionary Practices of Respiratory Therapists and Other Health-Care Practitioners Who Administer Aerosolized Medications

BACKGROUND

Respiratory therapists (RTs) and other health-care workers are potentially exposed to a variety of aerosolized medications. The National Institute for Occupational Safety and Health (NIOSH) Health and Safety Practices Survey of Healthcare Workers describes current exposure control practices and barriers to using personal protective equipment during administration of selected aerosolized medications.

METHODS

An anonymous, multi-module, web-based survey was conducted among members of health-care professional practice organizations representing RTs, nurses, and other health-care practitioners. A module on aerosolized medications included submodules for antibiotics (amikacin, colistin, and tobramycin), pentamidine, and ribavirin.

RESULTS

The submodules on antibiotics, pentamidine, and ribavirin were completed by 321, 227, and 50 respondents, respectively, most of whom were RTs. The relatively low number of ribavirin respondents precluded meaningful interpretation of these data and may reflect the rare use of this drug. Consequently, analysis focused on pentamidine, classified by NIOSH as a hazardous drug, and the antibiotics amikacin, colistin, and tobramycin, which currently lack authoritative safe handling guidelines. Respondents who administered pentamidine were more likely to adhere to good work practices compared with those who administered the antibiotics. Examples included training received on safe handling procedures (75% vs 52%), availability of employer standard procedures (82% vs 55%), use of aerosol delivery devices equipped with an expiratory filter (96% vs 53%) or negative-pressure rooms (61% vs 20%), and always using respiratory protection (51% vs 13%).

CONCLUSIONS

Despite the availability of safe handling guidelines for pentamidine, implementation was not universal, placing workers, co-workers, and even family members at risk of exposure. Although the antibiotics included in this study lack authoritative safe handling guidelines, prudence dictates that appropriate exposure controls be used to minimize exposure to the antibiotics and other aerosolized medications. Employers and employees share responsibility for ensuring that precautionary measures are taken to keep exposures to all aerosolized medications as low as practicable.

RSV prevention and treatment in pediatric lung transplant patients: a survey of current practices among the International Pediatric Lung Transplant Collaborative

RSV infection can be severe after pediatric lung transplantation. Strategies to prevent and treat RSV in this population are underreported. To assess the current practices, we surveyed the members of the IPLTC regarding RSV prevention and treatment strategies. Twenty-eight programs were surveyed; 18 (64.3%) responded at least partially. A median of 53 transplants (range, 8-355) occurred since inception. RSV testing occurs in asymptomatic (6/17) and symptomatic (17/17) patients. Diagnostic method is polymerase chain reaction at 13 sites and DFA at 8. Transplant candidates were received prophylaxis at 10 sites, with nine following national (5) or local (4) guidelines. All use palivizumab IM and/or IV. Recipients were received prophylaxis with palivizumab at eight centers (eight IM, one IV). Fourteen were treated for RSV (seven all patients; seven age-related). Medications include inhaled (6), oral (4), or IV (4) ribavirin, plus IVIG (9), steroids (8), and IV (2) or IM (3) palivizumab. Prevention and treatment barriers include insurance/hospital concerns, such as institutional reluctance to use inhaled ribavirin. RSV prevention and treatment strategies are diverse at pediatric lung transplant programs. Many centers offer prophylaxis (9/17) and treatments (14/17), but strategies are not uniform.

Long-term therapy with aerosolized ribavirin for parainfluenza 3 virus respiratory tract infection in an infant with severe combined immunodeficiency

We report the case of an infant with severe combined immunodeficiency who was presented with PIV3 infection. Aerosolized ribavirin was administered for 10 months until the child gained a functional immune system through an allogeneic hematopoietic stem cell transplant and cleared PIV3 infection. No adverse effect was observed in the child and in healthcare personnel, with a follow-up of three years. Despite the burden of aerosolized administration, early and prolonged administration of aerosolized ribavirin was feasible, well tolerated, and safe for the patient and the caregivers. This is a case report and no definite conclusions can be drawn. However, our experience suggests that prolonged aerosolized ribavirin administration should be considered for the treatment of PIV3 infection in the context of primary immunodeficiency, where there is no currently available alternative treatment, until a functional immune system is gained.

Occupational risk factors and asthma among health care professionals

RATIONALE

Recent U.S. data suggest an increased risk of work-related asthma among health care workers, yet only a few specific determinants have been elucidated.

OBJECTIVES

To evaluate associations of asthma prevalence with occupational exposures in a cross-sectional survey of health care professionals.

METHODS

A detailed questionnaire was mailed to a random sample (n=5,600) of all Texas physicians, nurses, respiratory therapists, and occupational therapists with active licenses in 2003. Information on asthma symptoms and nonoccupational asthma risk factors obtained from the questionnaire was linked to occupational exposures derived through an industry-specific job-exposure matrix.

MEASUREMENTS

There were two a priori defined outcomes: (1) physician-diagnosed asthma with onset after entry into health care ("reported asthma") and (2) "bronchial hyperresponsiveness-related symptoms," defined through an 8-item symptom-based predictor.

MAIN RESULTS

Overall response rate was 66%. The final study population consisted of 862 physicians, 941 nurses, 968 occupational therapists, and 879 respiratory therapists (n=3,650). Reported asthma was associated with medical instrument cleaning (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.34-3.67), general cleaning (OR, 2.02; 95% CI, 1.20-3.40), use of powdered latex gloves between 1992 and 2000 (OR, 2.17; 95% CI, 1.27-3.73), and administration of aerosolized medications (OR, 1.72; 95% CI, 1.05-2.83). The risk associated with latex glove use was not apparent after 2000. Bronchial hyperresponsiveness-related symptoms were associated with general cleaning (OR, 1.63; 95% CI, 1.21-2.19), aerosolized medication administration (OR, 1.40; 95% CI, 1.06-1.84), use of adhesives on patients (OR, 1.65; 95% CI, 1.22-2.24), and exposure to a chemical spill (OR, 2.02; 95% CI, 1.28-3.21).

CONCLUSIONS

The contribution of occupational exposures to asthma in health care professionals is not trivial, meriting both implementation of appropriate controls and further study.

Randomized controlled multicenter trial of aerosolized ribavirin for respiratory syncytial virus upper respiratory tract infection in hematopoietic cell transplant recipients

BACKGROUND

Respiratory syncytial virus infection of the upper airways may progress to fatal pneumonia in hematopoietic cell transplant recipients. The safety and efficacy of aerosolized ribavirin in preventing disease progression is unknown.

METHODS

In a multicenter prospective trial, hematopoietic cell transplant recipients with respiratory syncytial virus infection of the upper airways were randomized to receive ribavirin (2 g 3 times daily) or supportive care for 10 days. The primary end point was progression to radiographically proven pneumonia. Secondary end points included virologically proven respiratory syncytial virus pneumonia, viral load changes, and safety.

RESULTS

Fourteen patients were randomized to 1 of 2 treatment arms. The trial was discontinued after 5 years because of slow accrual. Pneumonia at 1 month after randomization occurred in 1 of 9 patients who received ribavirin and in 2 of 5 patients who received supportive care (P=.51); virologically proven respiratory syncytial virus pneumonia occurred in 0 of 9 and 2 of 5 patients, respectively (P=.11). At 10 days after randomization, the average viral load decreased by 0.75 log10 copies/mL in ribavirin recipients, compared with a viral load increase of 1.26 log10 copies/mL in untreated patients (P=.07). No discontinuations of ribavirin therapy because of adverse effects occurred during 84 drug administrations. Rates of adverse events were similar in both groups.

CONCLUSIONS

Preemptive aerosolized ribavirin treatment appeared to be safe, and trends of decreasing viral load over time were observed. However, proof of efficacy remains elusive in hematopoietic cell transplant recipients.

Respiratory health survey of respiratory therapists

STUDY OBJECTIVES

The purpose of this study was to determine whether respiratory therapists (RTs) had an elevated risk of respiratory symptoms and to determine the association of work exposures with symptoms.

METHODS

Mailed questionnaire responses from 275 RTs working in British Columbia, Canada, were compared to those of 628 physiotherapists who had been surveyed previously. Analyses incorporated logistic regression analysis with adjustment for age, sex, smoking status, and childhood asthma.

RESULTS

Compared to physiotherapists, RTs had over twice the risk of being woken by dyspnea, having wheeze, asthma attacks, and asthma diagnosed after entering the profession. Among RTs, two work factors associated with asthma were sterilizing instruments with glutaraldehyde-based solutions and the use of aerosolized ribavirin. RTs who used an oxygen tent or hood had the highest risk of asthma diagnosed after entering the profession (odds ratio [OR], 8.3; 95% confidence interval [CI], 12.6 to 26.0) and of asthma attacks in the last 12 months (OR, 3.6; 95% CI, 1.2 to 10.9).

CONCLUSIONS

Our data suggest that RTs may be at an increased risk for asthma-like symptoms and for receiving a diagnosis of asthma since starting to work in their profession, possibly related to exposure to glutaraldehyde and aerosolized ribavirin.

The natural history of respiratory syncytial virus infection in cancer and transplant patients: implications for management

Respiratory syncytial virus (RSV) has been reported to cause severe morbidity and mortality among cancer patients receiving chemotherapy with or without autologous peripheral blood stem cell transplantation (APBSCT). However, little is known about the natural history of this infection in these patients, and current standard practice, aerosolized ribavirin plus intravenous immunoglobulin (IVIG), is extremely expensive, difficult to use, and not supported by controlled clinical trials. The purpose of this observational study was to determine the frequency, seasonality, morbidity, and mortality of RSV infection in a group of cancer patients receiving cytotoxic chemotherapy with neither ribavirin nor IVIG treatment. During the period of October 3, 1997, through October 14, 1998, 190 cancer patients (median age, 58 years; 71 women) underwent viral nasopharyngeal washing prior to chemotherapy. Multiple myeloma (MM) accounted for most patients (147, 77%). RSV was recovered from cultures taken from 71 patients (37%) throughout the year, although more frequently during fall and winter seasons (P < .001) than spring and summer. Serious respiratory complications developed in 19 (27%) of 71 RSV-positive patients versus 24 (20%) of 119 patients whose RSV cultures were negative (P = .384). The presence of renal failure or increased lactate dehydrogenase (LDH) prior to chemotherapy and the development of mucositis were the only predictive factors for severe respiratory complications. Recovery of RSV from nasopharyngeal washings among cancer patients is common, occurs throughout the year, and does not appear to increase serious morbidity or mortality. RSV infection may not necessarily be a contraindication for APBSCT or an indication for therapy with aerosolized ribavirin and IVIG.

Prevention and treatment recommendations for respiratory syncytial virus infection. Background and clinical experience 40 years after discovery

Though 40 years have passed since its discovery, respiratory syncytial virus (RSV), one of the most ubiquitous viruses known, continues to evade most of our efforts to prevent or treat the clinical disease it causes. Long recognised as the most common cause of lower respiratory tract infections in virtually all children in the first 2 years of life, it has been increasingly recognised as a cause of more serious disease in several 'high risk' populations. These populations include infants with cardiac or pulmonary disease and infants and adults with immunodeficiencies, particularly those undergoing bone marrow transplantation. Early attempts to immunise children with a simple formalin-inactivated vaccine led to severe disease in vaccinated children who subsequently were infected with RSV from the community. Other vaccine constructs have failed for a variety of reasons, although surface glycoprotein subunit vaccines may hold promise. For years, ribavirin, a synthetic nucleoside analogue administered by constant aerosol, has been felt by many to lead to more rapid improvement in clinical disease caused by RSV, but it is still unclear whether its benefits are truly significant. An intravenous immunoglobulin product prepared from donors screened for the presence of high titres of RSV neutralising antibody (known as RSVIG) appears to be well tolerated and relatively effective in protecting high-risk infants against serious RSV disease, although therapeutic use has proven less dramatic. At least one monoclonal antibody undergoing current testing may prove easier to use in similar immunoprophylactic use. Results on the use of corticosteroids as supportive therapy have not been conclusive. In short, RSV will continue to be a challenge for clinicians and researchers well into the next century.