Two for one with split- or co-ventilation at the peak of the COVID-19 tsunami: is there any role for communal care when the resources for personalised medicine are exhausted?

Staffing crisis capacity: a different approach to healthcare resource allocation for a different type of scarce resource

Severe staffing shortages have emerged as a prominent threat to maintaining usual standards of care during the COVID-2019 pandemic. In dire settings of crisis capacity, healthcare systems assume the ethical duty to maximise aggregate population-level benefit of existing resources. To this end, existing plans for rationing mechanical ventilators and intensive care unit beds in crisis capacity focus on selecting individual patients who are most likely to survive and prioritising these patients to receive scarce resources. However, staffing capacity is conceptually different from availability of these types of discrete resources, and the existing strategy of identifying and prioritising patients with the best prognosis cannot be readily adapted to fit this real-world scenario. We propose that two alternative approaches to staffing resource allocation offer a better conceptual fit: (1) prioritise the worst off: restrict access to acute care services and hospital admission for patients at relatively low clinical risk and (2) prioritise staff interventions with high near-term value: universally restrict selected interventions and treatments that require substantial staff time and/or energy but offer minimal near-term patient benefit. These strategies-while potentially resulting in care that deviates from usual standards-support the goal of maximising the aggregate benefit of scarce resources in crisis capacity settings triggered by staffing shortages. This ethical framework offers a foundation to support institutional leaders in developing operationalisable crisis capacity policies that promote fairness and support healthcare workers.

Exhalatory dynamic interactions between patients connected to a shared ventilation device

In this work a shared pressure-controlled ventilation device for two patients is considered. By the use of different valves incorporated to the circuit, the device enables the restriction of possible cross contamination and the individualization of tidal volumes, driving pressures, and positive end expiratory pressure PEEP. Possible interactions in the expiratory dynamics of different pairs of patients are evaluated in terms of the characteristic exhalatory times. These characteristic times can not be easily established using simple linear lumped element models. For this purpose, a 1D model using the Hydraulic and Mechanical libraries in Matlab Simulink was developed. In this sense, experiments accompany this study to validate the model and characterize the different valves of the circuit. Our results show that connecting two patients in parallel to a ventilator always resulted in delays of time during the exhalation. The size of this effect depends on different parameters associated with the patients, the circuit and the ventilator. The dynamics of the exhalation of both patients is determined by the ratios between patients exhalatory resistances, compliances, driving pressures and PEEPs. Adverse effects on exhalations became less noticeable when respiratory parameters of both patients were similar, flow resistances of valves added to the circuit were negligible, and when the ventilator exhalatory valve resistance was also negligible. The asymmetries of driving pressures, compliances or resistances exacerbated the possibility of auto-PEEP and the increase in relaxation times became greater in one patient than in the other. In contrast, exhalatory dynamics were less sensitive to the ratio of PEEP imposed to the patients.

Titration of Parameters in Shared Ventilation With a Portable Ventilator

BACKGROUND

Dual-patient, single-ventilator protocols (ie, protocols to ventilate 2 patients with a single conventional ventilator) may be required in times of crisis. This study demonstrates a means to titrate peak inspiratory pressure (PIP), PEEP, and [Formula: see text] for test lungs ventilated via a dual-patient, single-ventilator circuit.

METHODS

This prospective observational study was conducted using a ventilator connected to 2 test lungs. Changes in PIP, PEEP, and [Formula: see text] were made to the experimental lung, while no changes were made to the control lung. Measurements were obtained simultaneously from each test lung. PIP was titrated using 3D-printed resistors added to the inspiratory circuit. PEEP was titrated using expiratory circuit tubing with an attached manual PEEP valve. [Formula: see text] was titrated by using a splitter added to the ventilator tubing.

RESULTS

PIP, PEEP, and [Formula: see text] were reliably and incrementally titratable in the experimental lung, with some notable but manageable changes in pressure and [Formula: see text] documented in the control lung during these titrations. Similar results were measured in lungs with identical and different compliances.

CONCLUSIONS

Pressures and [Formula: see text] can be reliably adjusted when utilizing a dual-patient, single-ventilator circuit with simple, low-cost modifications to the circuit. This innovation could potentially be lifesaving in a resource-limited or crisis setting. Understanding the interactions of these circuits is imperative for making their use safer.

Bubble CPAP splitting: innovative strategy in resource-limited settings

BACKGROUND

Non-invasive respiratory support for neonates using bubble continuous positive airway pressure (bCPAP) delivery systems is now widespread owing to its safety, cost effectiveness and easy applicability. Many innovative solutions have been suggested to deal with the possible shortage in desperate situations like disasters, pandemics and resource-limited settings. Although splitting of invasive ventilation has been reported previously, no attempts to split non-invasive respiratory support have been reported.

OBJECTIVE

The primary objective was to test the feasibility of splitting the bCPAP assembly using a T-piece splitter in a simulation model.

METHODS

A pilot simulation-based study was done to split a single bCPAP assembly using a T-piece. Other materials consisted of a heated humidification system, an air oxygen blender, corrugated inspiratory and expiratory tubing, nasal interfaces and two intercostal chest tube drainage bags. Two pressure manometers were used simultaneously to measure delivered pressures at different levels of set bCPAPs at the expiratory limb of nasal interfaces.

RESULTS

Pressures measured at the expiratory end of two nasal interfaces were 5.1 and 5.2 cm H2O, respectively, at a flow of 6 L/min and a water level of 5 cm H2O in both chest bags. When tested across different levels of set continuous positive airway pressure (3-8 cmH2O) and fractional inspired oxygen concentration (0.30-1.0), measured parameters corresponded to set parameters.

CONCLUSION

bCPAP splitting using a T-piece splitter is a technically simple, feasible and reliable strategy tested in a simulation model. Further testing is needed in a simulated lung model.

Pragmatic Recommendations for the Management of Acute Respiratory Failure and Mechanical Ventilation in Patients with COVID-19 in Low- and Middle-Income Countries

Management of patients with severe or critical COVID-19 is mainly modeled after care for patients with severe pneumonia or acute respiratory distress syndrome (ARDS) from other causes, and these recommendations are based on evidence that often originates from investigations in resource-rich intensive care units located in high-income countries. Often, it is impractical to apply these recommendations to resource-restricted settings, particularly in low- and middle-income countries (LMICs). We report on a set of pragmatic recommendations for acute respiratory failure and mechanical ventilation management in patients with severe/critical COVID-19 in LMICs. We suggest starting supplementary oxygen when SpO2 is persistently lower than 94%. We recommend supplemental oxygen to keep SpO2 at 88-95% and suggest higher targets in settings where continuous pulse oximetry is not available but intermittent pulse oximetry is. We suggest a trial of awake prone positioning in patients who remain hypoxemic; however, this requires close monitoring, and clear failure and escalation criteria. In places with an adequate number and trained staff, the strategy seems safe. We recommend to intubate based on signs of respiratory distress more than on refractory hypoxemia alone, and we recommend close monitoring for respiratory worsening and early intubation if worsening occurs. We recommend low-tidal volume ventilation combined with FiO2 and positive end-expiratory pressure (PEEP) management based on a high FiO2/low PEEP table. We recommend against using routine recruitment maneuvers, unless as a rescue therapy in refractory hypoxemia, and we recommend using prone positioning for 12-16 hours in case of refractory hypoxemia (PaO2/FiO2 < 150 mmHg, FiO2 ≥ 0.6 and PEEP ≥ 10 cmH2O) in intubated patients as standard in ARDS patients. We also recommend against sharing one ventilator for multiple patients. We recommend daily assessments for readiness for weaning by a low-level pressure support and recommend against using a T-piece trial because of aerosolization risk.

Modification of a domiciliary ventilator to increase FiO2: an off-label modification which may be of value in COVID-19

Although nasal continuous positive airway pressure or non-invasive ventilation is used to manage some patients with acute lung injury due to COVID-19, such patients also demonstrate increased minute ventilation which makes it hard, if the device is used in line with the manufacturer's instructions, to achieve adequate oxygen delivery. In addition, if a hospital contains many such patients, then it is possible that the oxygen requirements will exceed infrastructure capacity. Here we describe a simple modification of two exemplar ventilators normally used for domiciliary ventilation, which substantially increased the fraction of inspired oxygen (FiO2) delivered.

3D-printed valves to assist noninvasive ventilation procedures during the COVID-19 pandemic: a case study

Aim: To produce valves to be used with full-face snorkeling masks for noninvasive ventilation (NIV) procedure during the coronavirus disease 2019 (COVID-19) pandemic. Materials & methods: ISINNOVA’s Charlotte valves for full-face snorkeling masks used for NIV procedures were redesigned, produced by selective laser sintering additive manufacturing, and submitted to air leakage tests. Results: The final model assembly did not present air leakage during the NIV procedure on human models, minimizing risks of air contamination. Conclusion: This study shows the feasibility of using additive manufactured valves with snorkel facial masks to support health systems during COVID-19 and possible future pandemics.

Frequency of Abnormalities Detected by Point-of-Care Lung Ultrasound in Symptomatic COVID-19 Patients: Systematic Review and Meta-Analysis

The COVID-19 pandemic has resulted in significant morbidity, mortality, and strained healthcare systems worldwide. Thus, a search for modalities that can expedite and improve the diagnosis and management of this entity is underway. Recent data suggested the utility of lung ultrasound (LUS) in the diagnosis of COVID-19 by detecting an interstitial pattern (B-pattern). Hence, we aimed to pool the proportion of various reported lung abnormalities detected by LUS in symptomatic COVID-19 patients. We conducted a systematic review (PubMed, MEDLINE, and EMBASE until April 25, 2020) and a proportion meta-analysis. We included seven studies examining the role of LUS in 122 COVID-19 patients. The pooled proportion (PP) of B-pattern detected by lung ultrasound (US) was 0.97 (95% CI: 0.94–1.00 I² 0%, Q 4.6). The PP of finding pleural line abnormalities was 0.70 (95% CI: 0.13–1.00 I² 96%, Q 103.9), of pleural thickening was 0.54 (95% 0.11–0.95 I² 93%, Q 61.1), of subpleural or pulmonary consolidation was 0.39 (95% CI: 0.21–0.58 I² 72%, Q 17.8), and of pleural effusion was 0.14 (95% CI: 0.00–0.37 I² 93%, Q 27.3). Our meta-analysis revealed that almost all SARS-CoV-2–infected patients have abnormal lung US. The most common abnormality is interstitial involvement depicted as B-pattern. The finding from our review highlights the potential role of this modality in the triage, diagnosis, and follow-up of COVID-19 patients. A sizable diagnostic accuracy study comparing LUS, computed tomography scan, and COVID-19–specific tests is warranted to further test this finding and to delineate the diagnostic and prognostic yield of each of these modalities.