HJAR May/Jun 2020

HEALTHCARE JOURNAL OF ARKANSAS I  MAY / JUN 2020 17 The SNS ventilators include the LTV-1200, the Impact 754 and the LP-10. The LTV-1200 and Impact 754 can deliver the required tidal volumes, FIO2, and PEEP to maintain the majority of patients based on the current clinical presentation. Both devices have been used to manageARDS patients during military transport and in disaster operations. Both are capable of delivering a PEEP of 20 cm H2O and near 100% oxygen. The LTV-1200 is the most common and newest device in the stockpile and we believe will likely be issued first. The LP-10 is a piston-based home care ventilator with only a low flow oxygen inlet and the addition of PEEP with an external valve. The LP-10 can only provide volume ventilation. Three factors limit utility of this ventilator for hypoxemic respiratory failure: its limited FIO2 range, inability to select and maintain a set FIO2 and it’s requirement for an external PEEP valve. Notes regarding function: 1. The maximum peak flow of the Im- pact 754 is 60 L/min using a constant flowwaveform. The 754 only provides volume ventilation. Patients with high inspiratory flow demands may have flow asynchrony. 2. Tidal volume delivery with the 754 at the low end is improved with the use of external air bypassing the internal compressor. 3. None of the ventilators in the stock- pile have an expiratory filter. Place- ment of an expiratory filter will be important prior to use on infectious patients. 4. All the SNS ventilators have a room air inlet for the compressor and in- let filters should be added to the 754 and the LP-10. The LTV-1200 has an internal filter. Can bilevel ventilators be used for invasive ventilation? CPAP machines designed for obstructive sleep apnea cannot be repurposed as venti- lators by clinicians. However, bilevel devices are ventilators and can be used for invasive ventilation. There have been suggestions in the me- dia that CPAP machines designed to treat obstructive sleep apnea can be repurposed as ventilators. This is not something that a respiratory therapist can do and this should not be attempted. It is possible for bilevel devices, includ- ing those used in the hospital and those used in the home, to be used for invasive mechanical ventilation. Some, but not all, bilevel devices are FDA-cleared for use as an invasive ventilator. These ventilators are commonly used for chronic respiratory fail- ure and some sleep disorders. Bilevel ventilators do not have an ac- tive exhalation valve. Of concern is aero- sol generation from the leak port. This is a legitimate concern. There are commer- cially available filters that can be fitted to the leak port. Check with the manufacturer to purchase these for your circuits before using this ventilator type on a patient with COVID-19. We recommend active humidification when a bilevel ventilator is used for invasive respiratory support. Alternatively, a heat- and-moister exchanger (HME) can be used. If using an HME, ideally an HME-filter is used and this might obviate the need for a filter on the leak port. On bilevel ventilators, the level of respira- tory support is determined by the difference between IPAP and EPAP. This difference is the level of pressure support or pressure control. The level of EPAP (PEEP) can be increased as needed to support hypoxemic respiratory failure, but it is important to re- member that IPAPmust be increased when EPAP is increased (and vice versa). FIO2 can be set directly on some bilevel ventilators. For others, oxygen is titrated into the system. For oxygen titration, follow the instructions of the manufacturer. As with any ventilator, lung protective ventilation strategies should be used. If the ventilator displays tidal volume, target 6 mL/kg predicted body weight and a driving pressure (IPAPEPAP) less than 15 cm H2O. Titrate PEEP appropriately, such as with the high PEEPARDSnet table. For safety, alarms should be set appro- priately when any bilevel ventilator is used. Continuous pulse oximetry should also be used, with alarms set appropriately. We suggest that use of bilevel ventilators for invasive support should be triaged. Ide- ally, they should be used for patients who do not have COVID-19, thus freeing critical care ventilators for patients with COVID-19 hypoxemic respiratory failure. Triage ventilator performance to patient illness Use the highest technology equipment for the most severely ill patients. As with any asset, the ventilators at your disposal should be triaged for use, matching the device capabilities with the severity of patient illness. The patients with the most severe hypoxemia requiring high PEEP and high FIO2, with reduced compliance, should be triaged to ICU ventilators. Patients re- quiring ventilation for non-COVID related illness can be managed with portable de- vices and less sophisticated devices in your inventory. The SNS ventilators can be woven into that matrix which includes the use of anesthesia workstations. Can I ventilate more than one patient with a single ventilator? Do not attempt to ventilate multiple patients with a single ventilator. As a last-ditch effort, an attempt to ventilate 2 subjects with similar