Can breathing circuit filters help prevent the spread of influenza A (H1N1) virus from intubated patients?

INTRODUCTION: In March 2010, more than 213 countries worldwide reported laboratory confirmed cases of influenza H1N1 infections with at least 16,813 deaths. In some countries, roughly 10 to 30% of the hospitalized patients were admitted to the ICU and up to 70% of those required mechanical ventilation. The question now arises whether breathing system filters can prevent virus particles from an infected patient from entering the breathing system and passing through the ventilator into the ambient air. We tested the filters routinely used in our institution for their removal efficacy and efficiency for the influenza virus A H1N1 (A/PR/8/34). METHODS: Laboratory investigation of three filters (PALL Ultipor(®) 25, Ultipor(®) 100 and Pall BB50T Breathing Circuit Filter, manufactured by Pall Life Sciences) using a monodispersed aerosol of human influenza A (H1N1) virus in an air stream model with virus particles quantified as cytopathic effects in cultured canine kidney cells (MDCK). RESULTS: The initial viral load of 7.74±0.27 log10 was reduced to a viral load of ≤2.43 log10, behind the filter. This represents a viral filtration efficiency of ≥99.9995%. CONCLUSION: The three tested filters retained the virus input, indicating that their use in the breathing systems of intubated and mechanically ventilated patients can reduce the risk of spreading the virus to the breathing system and the ambient air.

A method for the rapid detection of urinary tract infections.

OBJECTIVE: To determine the reliability of a rapid detection method compared with the reference standard streaked agar plate in diagnosing the presence of urinary tract infection (UTI). METHODS: De-identified clean catch urine specimens from 980 office visit patients were processed during a 30-day period. Classic 1-µL and 10-µL streaked agar plates were used in parallel with the new CultureStat Rapid UTI Detection System (CSRUDS). Urine results were evaluated using the CSRUDS at 30 and 90 minutes after collection. A comparative analysis of the subsequent plate results versus the CSRUDS results was achieved for 973 of these samples. RESULTS: Positive UTI conditions were accurately identified by both CSRUDS and agar streak plate methods. CSRUDS accurately identified UTI negative conditions with 99.3% reliability at 90 minutes. The negative predictive value of CSRUDS was 99.2% at 30 minutes. CONCLUSION: Current agar plating for first-round UTI screening has substantial documented problems that can negatively affect an accurate and timely UTI diagnosis. A novel rapid detection system, the CSRUDS provides UTI negative/positive same-day results in ≤ 90 minutes from the start of test. Such rapidly available results will enable more accurate and timely clinical decisions to be made in the urology office, particularly regarding infection status before urologic instrumentation.

Nutritional effects of culture media on mycoplasma cell size and removal by filtration.

Careful media filtration prior to use is an important part of a mycoplasma contamination prevention program. This study was conducted to increase our knowledge of factors that influence efficient filtration of mycoplasma. The cell size of Acholeplasma laidlawii was measured after culture in various nutritional conditions using scanning electron microscopy. The maximum cell size changed, but the minimum cell size remained virtually unchanged and all tested nutritional conditions resulted in a population of cells smaller than 0.2 microm. Culture in Tryptic Soy Broth (TSB) resulted in an apparent increase in the percentage of very small cells which was not reflected in increased penetration of non-retentive 0.2 microm rated filters. A. laidlawii cultured in selected media formulations was used to challenge 0.2 microm rated filters using mycoplasma broth base as the carrier fluid. We used 0.2 microm rated filters as an analytical tool because A. laidlawii is known to penetrate 0.2 microm filters and the degrees of penetration can be compared. Culture of A. laidlawii in TSB resulted in cells that did not penetrate 0.2 microm rated filters to the same degree as cells cultured in other media such as mycoplasma broth or in TSB supplemented with 10% horse serum.

Method for qualifying microbial removal performance of 0.1 micron rated filters. Part IV: Retention of hydrogenophaga pseudoflava (ATCC 700892) and Ralstonia pickettii (ATCC 700591) by 0.2 and 0.22 micron rated filters.

Ralstonia pickettii has emerged as a bioburden microorganism of considerable importance in pharmaceutical processes utilizing conventional 0.2 or 0.22 micron rated "sterilizing grade" filters. In this article, we re-evaluated and studied the retention efficiencies of 0.2 micron rated nylon 6.6 and 0.22 microns rated modified polyvinylidene fluoride (PVDF) filters for Hydrogenophaga pseudoflava (ATCC 700892) and R. pickettii (ATCC 700591). Out of a total of forty-four 0.2/0.22 micron rated filters discs tested in this study (spanning different challenge fluids, different challenge conditions, and different filter types), H. pseudoflava penetration was observed for every filter disc tested. Log titer reduction (LTR) values ranged from 0.3 to 2.0 logs for 20-48 hour challenges conducted in Water for Injection (WFI), and 3.8-7.1 logs for 6-hour challenges conducted in Minimal Media Davis (MMD). For 0.2 micron nylon 6.6 filter discs, penetration by R. pickettii was observed only in WFI challenges and was dependent on the culture and challenge conditions used. Penetration by R. pickettii was also restricted to only those membrane discs that were very close to the filter manufacturer's production integrity test (the Quantitative Bubble Point, QBP, test) limit. Where R. pickettii penetration was observed, LTR values were significantly higher than those observed for H. pseudoflava with the same filter discs. This study: 1) supports the use of H. pseudoflava as a worst-case challenge model for R. pickettii in process- and product-specific bacterial retention testing; 2) provides experimental evidence, for the first time, for the need to include filter membrane lots that have a physical integrity test value at or near the filter manufacturer's production (lower) limit in these tests; and 3) demonstrates how a standardized membrane integrity test (such as the QBP test) can be used select such "worst-case" membranes and to verify the inclusion of such "worst-case" membranes in these tests, thus serving as the link between the membrane disc used in bacterial retention validation testing and the production process filter.

A CNS integrated health care delivery system model.

The more complicated a client's health needs are, the higher the risk for inappropriate utilization of services, fragmentation of care and delays in system access. The challenge is to ensure that patients move appropriately from one access point to another in the most efficient, effective manner. The Integrated Health Care Delivery System is designed to meet this challenge.

Collegial model for clinical nurse specialists: implementation.

CNSs have typically reported to a variety of administrative or management positions within organizational structures. The Collegial Model for Clinical Nurse Specialists was developed and operationalized as a self-governing strategy for CNSs within a multihospital medical center. Implementation process of this model, including the driving forces, obstacles encountered, and strategies for operationalization are addressed in this article.

Evaluation of manometer use in manual ventilation of infants in neonatal intensive care units.

Variations exist in the techniques used to perform manual ventilation in neonates and in the proficiency levels of nurses in neonatal intensive care units (NICU) who perform the procedure. This study was undertaken to determine (1) whether significant differences exist in nurses' ability to control prescribed peak inspiratory pressure (PIP) accurately when mamometers are used, as compared with when they are not used, during manual ventilation in NICU infants; and (2) whether the number of years of work experience nurses have in the NICU is related to manometer use and success in controlling prescribed PIP. The sample included 60 professional nurses whose experience ranged from 1 to 26 years. A statistically significant difference was found in nurses' ability to control PIP successfully when manometers were used as compared with when they were not used (t = 12.04, p = 0.001). Nurses with more experience tended to rely less on manometers to guide their manual ventilation techniques, but were also less accurate in controlling the delivery of PIP without the devices. We provide recommendations for clinical practice based on these findings.