AARC Clinical Practice Guideline: Spontaneous Breathing Trials for Liberation From Adult Mechanical Ventilation.

Despite prior publications of clinical practice guidelines related to ventilator liberation, some questions remain unanswered. Many of these questions relate to the details of bedside implementation. We, therefore, formed a guidelines committee of individuals with experience and knowledge of ventilator liberation as well as a medical librarian. Using Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology, we make the following recommendations: (1) We suggest that calculation of a rapid shallow breathing index is not needed to determine readiness for a spontaneous breathing trial (SBT) (conditional recommendation; moderate certainty); (2) We suggest that SBTs can be conducted with or without pressure support ventilation (conditional recommendation, moderate certainty); (3) We suggest a standardized approach to assessment and, if appropriate, completion of an SBT before noon each day (conditional recommendation, very low certainty); and (4) We suggest that FIO2 should not be increased during an SBT (conditional recommendation, very low certainty). These recommendations are intended to assist bedside clinicians to liberate adult critically ill patients more rapidly from mechanical ventilation.

Oxygen Delivery With an Open Oxygen Mask and Other Conventional Masks: A Simulation-Based Study.

BACKGROUND: A recently introduced open oxygen mask design was marketed in 2021 (open mask A). The manufacturer claims that the mask "…provides one solution for all your oxygen delivery needs across your patients' continuum of care." The new oxygen mask specifies flow (1-15 L/min and flush) with an expected FIO2 from 0.25-0.85. This suggests that this mask eliminates the need for multiple oxygen delivery devices as FIO2 requirements change. This study aimed to describe the FIO2 performance of the new open oxygen mask and other commonly used oxygen masks. METHODS: The following oxygen masks were studied: open mask A, open mask B, simple mask, partial rebreather, and non-rebreather. An adult mannequin head was attached to a breathing simulator, which recorded FIO2 at the simulated alveolar level. The simulator was set to a closed-loop volume control mode: VT = 320 mL, compliance = 50 mL/cm H2O, resistance = 4 cm H2O/L/s, breathing frequency = 15 breaths/min, increase = 25%, hold = 0%, and release = 30%. Oxygen was run through each mask at the recommended flows. Each flow was verified with a flow analyzer before attaching the mask for oxygen measurement. Each experiment was performed twice. The FIO2 measurements were averaged and compared using a 2-way ANOVA with P < .05 indicating significance. RESULTS: The FIO2 delivery was significantly different for each device. The measured FIO2 range was open mask A, 0.30-0.60; open mask B, 0.28-0.64; simple mask, 0.55-0.73; partial non-rebreather, 0.73-1.0; non-rebreather, 0.93-1.00. CONCLUSIONS: The performance of each oxygen mask from highest to lowest FIO2 : non-rebreather, partial rebreather, simple mask, open mask A, and open mask B. These findings suggest that no oxygen mask tested serves as a substitute for the others across a flow range of 1-15 L/min and flush.

Multiplex Ventilation: Solutions for Four Main Safety Problems.

BACKGROUND: The COVID-19 pandemic has led to an increased demand for mechanical ventilators and concerns of a ventilator shortage. Several groups have advocated for 1 ventilator to ventilate 2 or more patients in the event of such a shortage. However, differences in patient lung mechanics could make sharing a ventilator detrimental to both patients. Our previous study indicated failure to ventilate in 67% of simulations. The safety problems that must be solved include individual control of tidal volume (VT), individual measurement of VT, individualization of PEEP settings, and individual PEEP measurement. The purpose of this study was to evaluate potential solutions developed at our institution. METHODS: Two separate lung simulators were ventilated with a modified multiplex circuit using pressure control ventilation. Parameters of the lung models used for simulations (resistance and compliance) were evidence-based from published studies. Individual circuit-modification devices were first evaluated for accuracy. Devices were an adjustable flow diverter valve, a prototype dual volume display, a PEEP valve, and a disposable PEEP display. Then the full modified multiplex circuit was assessed by ventilating 6 pairs of simulated patients with different lung models and attempting to equalize ventilation. Ventilation was considered equalized when VT and end-expiratory lung volume were within 10% for each simulation. RESULTS: The adjustable flow diverter valve allowed volume adjustment to 1 patient without affecting the other. The average error of the dual volume display was -17%. The PEEP valves individualized PEEP, but the PEEP gauge error ranged from 17% to 41%. Using the multiplex circuit, ventilation was equalized regardless of differences in resistance or compliance, reversing the "failure modes" of our previous study. CONCLUSIONS: The results of this simulation-based study indicate that devices for individual control and display of VT and PEEP are effective in extending the usability and potential patient safety of multiplex ventilation.