Making respiratory care safe for neonatal and paediatric intensive care unit staff: mitigation strategies and use of filters.

Background: Many medical devices in pediatric and newborn intensive care units can potentially expose healthcare workers (HCWs) and others to transmission of respiratory and other viruses and bacteria. Such fomites include ventilators, nebulizers, and monitoring equipment. Approach: We report the general, novel approach we have taken to identify and mitigate these risks and to protect HCWs, visitors and patients from exposure while maintaining the optimal performance of such respiratory equipment. Findings: The approach combined a high level of personal protective equipment (PPE), strict hand hygiene, air filtration and air conditioning and other relevant viral risk mitigation guidelines. This report describes the experiences from the SARS-CoV-2 pandemic to provide a reference framework that can be applied generally. The steps we took consisted of auditing our equipment and processes to identify risk through sources of potentially contaminated gas that may contain aerosolized virus, seeking advice and liaising with suppliers/manufacturers, devising mitigation strategies using indirect and direct approaches (largely filtering), performing tests on equipment to verify proper function and the absence of negative impacts and the development and implementation of relevant procedures and practices. We had a multidisciplinary team to guide the process. We monitored daily for hospital-acquired infections among staff caring for SARS-CoV-2 patients. Conclusion: Our approach was successful as we have continued to offer optimal intensive care to our patients, and we did not find any healthcare worker who was infected through the course of caring for patients at the bedside. The lessons learnt will be of benefit to future local outbreaks or pandemics.

Epistemic injustice, children and mental illness.

The concept of epistemic (specifically testimonial) injustice is the latest philosophical tool with which to try to theorise what goes wrong when mental health service users are not listened to by clinicians, and what goes right when they are. Is the tool adequate to the task? It is argued that, to be applicable at all, the concept needs some adjustment so that being disbelieved as a result of prejudice is one of a family of alternative necessary conditions for its application, rather than a necessary condition all on its own. It is then argued that even once adjusted in this way, the concept does not fit well in the area where the biggest efforts have been made to apply it so far, namely the highly sensitive case of adult patients suffering from delusions. Indeed it does not serve the interests of service users struggling for recognition to try to apply it in this context, because there is so much more to being listened to than simply being believed. However, the concept is found to apply smoothly in many cases where the service users are children, for example, in relation to children's testimony on the efficacy of treatment. It is suggested that further research would demonstrate the usefulness of the concept in adult cases of a similar kind.

Characterising the ambient sound environment for infants in intensive care wards.

AIM: The purpose of this study is to characterise ambient sound levels of paediatric and neonatal intensive care units in an old and new hospital according to current standards. METHODS: The sound environment was surveyed for 24-h data collection periods (n = 80) in the Neonatal and Paediatric Intensive Care Units (NICUs and PICUs) and Special Care Nursery of the old and new Royal Children's Hospital Melbourne. The ambient sound environment was characterised as the proportion of time the ongoing ambient sound met standard benchmarks, the mean 5-s sound levels and the number and duration of noise events. RESULTS: In the old hospital, none of the data collection periods in the NICU and PICU met the standard benchmark for ongoing ambient sound, while only 5 of the 22 data collection periods in the new hospital met the recommended level. There was no change in proportion of time at recommended Leq between the old and the new Special Care Nursery. There was strong evidence for a difference in the mean number of events >65 dBA (Lmax ) in the old and new hospital (rate ratio = 0.82, 95% confidence interval: 0.73 to 0.92, P = 0.001). The NICU and PICU were above 50 dBA in 75% of all data collection periods, with ventilatory equipment associated with higher ongoing ambient sound levels. CONCLUSIONS: The ongoing ambient sound suggests that the background sound environment of the new hospital is not different to the old hospital. However, there may be a reduction in the number of noise events.

Are All Oscillators Created Equal? In vitro Performance Characteristics of Eight High-Frequency Oscillatory Ventilators.

BACKGROUND: The mode of waveform generation and circuit characteristics differ between high-frequency oscillators. It is unknown if this influences performance. OBJECTIVES: To describe the relationships between set and delivered pressure amplitude (x0394;P), and the interaction with frequency and endotracheal tube (ETT) diameter, in eight high-frequency oscillators. METHODS: Oscillators were evaluated using a 70-ml test lung at 1.0 and 2.0 ml/cm H2O compliance, with mean airway pressures (PAW) of 10 and 20 cm H2O, frequencies of 5, 10 and 15 Hz, and an ETT diameter of 2.5 and 3.5 mm. At each permutation of PAW, frequency and ETT, the set x0394;P was sequentially increased from 15 to 50 cm H2O, or from 20 to 100% maximum amplitude (10% increments) depending on the oscillator design. The x0394;P at the ventilator (x0394;PVENT), airway opening (x0394;PAO) and within the test lung (x0394;PTRACH), and tidal volume (V(T)) at the airway opening were determined at each set x0394;P. RESULTS: In two oscillators the relationships between set and delivered x0394;P were non-linear, with a plateau in x0394;P thresholds noted at all frequencies (Dräger Babylog 8000) or ≥10 Hz (Dräger VN500). In all other devices there was a linear relationship between x0394;PVENT, x0394;PAO and x0394;PTRACH (all r2 >0.93), with differing attenuation of the pressure wave. Delivered V(T) at the different settings tested varied between devices, with some unable to deliver V(T) >3 ml at 15 Hz, and others generating V(T)>20 ml at 5 Hz and a 1:1 inspiratory-to-expiratory time ratio. CONCLUSIONS: Clinicians should be aware that modern high-frequency oscillators exhibit important differences in the delivered x0394;P and V(T).

Pressure and flow waveform characteristics of eight high-frequency oscillators.

OBJECTIVES: The differences in performance of early generation high-frequency oscillators have been attributed to their distinct pressure and flow waveforms. Recently, five new oscillators have been commercially released. The objective of this study was to characterize the pressure and flow waveforms of eight commercially available oscillators. DESIGN: In vitro benchtop study. SETTING: Tertiary pediatric teaching hospital. INTERVENTIONS: Eight oscillators were evaluated using a test lung; mean airway pressure 10 and 20 cm H2O; frequencies 5, 10, and 15 Hz; pressure amplitude 30 cm H2O (or equivalent); compliance 1.0 mL/cm H2O; and endotracheal tube 3.5 mm. Ventilators tested were Sensormedics 3100A and B (Carefusion), SLE5000 (SLE), Fabian (Acutronic), Leonie+ (Heinen+Löwenstein), Sophie (Stephan), and VN500 and Babylog 8000 (Dräger). MEASUREMENTS AND MAIN RESULTS: Pressure (airway opening, at oscillator and within the test lung) and airway opening flow waveforms were recorded. Airway opening waveforms were characterized by type (square or sine) and by determining power spectral density analysis. The Sensormedics A and B and the SLE5000 delivered square waves; all other oscillators generated sine waves. Sensormedics, the SLE5000, and the Sophie had a characteristic inspiratory slope (incisura). The pressure waveform within the test lung was a sine wave for all oscillators. Oscillators with square waves or an inspiratory incisura exhibited the highest number of nonfundamental frequency components on power spectral density analysis, suggesting more complex harmonic waveforms with potentially greater transmissive power to the lungs. At frequencies of 5 and 10 Hz, all ventilators, except Babylog 8000, generated airway pressure amplitudes greater than 28.6 cm H2O and tidal volumes greater than 6 mL at the airway opening. CONCLUSIONS: Current high-frequency oscillators deliver different waveforms. As these may result in variable clinical performance, operators should be aware that these differences exist.

Dräger VN500's oscillatory performance has a frequency-dependent threshold.

AIM: The aim of this study is to compare the high-frequency pressure amplitude (oscillatory change in pressure (ΔP)) and tidal volume (high-frequency tidal volume at the airway opening (VTHF )) delivered by the Dräger VN500 (Drägerwerk Ag & Co., Lübeck, Germany) and the Sensormedics 3100 (SM3100; CareFusion, San Diego, CA, USA) through a range of oscillatory frequencies. METHODS: In this benchtop study, high-frequency oscillations were applied to an infant test lung at unrestricted set amplitudes. Pressure and flow were measured as a function of frequency, incremented by 1 Hz from 5 to 15 Hz. Measurements were repeated for a range of ventilator settings, and lung resistive and compliance states. RESULTS: The VN500, but not the SM3100, demonstrated an exponential decrease in airway opening ΔP as frequency increased. The difference between the SM3100- and VN500-delivered VTHF became greater with each frequency increment. At 15 Hz, VN500 VTHF was 49% of SM3100 VTHF . CONCLUSIONS: The VN500 demonstrates a frequency-related reduction in ΔP not observed in the SM3100. Clinicians need to be aware of these differences in performance characteristics.