HJAR May/Jun 2020

18 MAY / JUN 2020 I  HEALTHCARE JOURNAL OF ARKANSAS AMERICAN ASSOCIATION FOR RESPIRATORY CARE SARS CoV-2 GUIDANCE compliance might be attempted after approval of local Ethics Committee and/or Institutional Review Board (IRB).” The interest in ventilating multiple pa- tients on a given ventilator has been piqued by well-intended but potentially dangerous internet videos. The first modern descriptions for 4 patients per ventilator were advanced by Neyman et al3 in 2006 and Paladino4 in 2008. In each instance Branson, Rubinson and others have cautioned against the use of this technique. At present we recommend that you DO NOT attempt to ventilate 4 pa- tients with a single ventilator. 5-7 Of note, the jump to 4 patients without considering just 2 patients is nonsensical due to the complexity of this approach. We hope to provide more guidance on the safest pos- sible application of a single ventilator for 2 patients in the near future. Regarding the 4-patient scenario, the pa- tients would have to be arranged around the ventilator like spokes abound a hub. This po- sitioning moves the patient away from the supplies of oxygen, air, and vacuum at the head of the bed. It also places the patients in close proximity for transfer of other organ- isms. It cannot be done in separate rooms. One of our concerns is that in attempt to po- sition patients, extra dead space (resulting in hypercarbia) or longer tubing contributing to compressible volume could be dangerous. We do not find that matching patients by size is relevant, however matching by compli- ance, driving pressure, PEEP, and FIO2 are far more important. Patients have to be heavily sedated and paralyzed. Spontaneous breath- ing by a single patient sensed by the ventila- tor would set the respiratory frequency for all the others. Worse, the added circuit volume could preclude triggering (note the internet presentations suggest making the ventilator less sensitive) and may cause the patients to share gas between circuits in the absence of one-way valves. Pendelluft between pa- tients is not out of the question resulting in rebreathing, cross infection, and over-dis- tension. The reasons not to ventilate 4 sub- jects with 1 ventilator are too numerous to mention. An abbreviated list is shown below: 1. The added circuit volume defeats the operational selftest (the test fails). You have to operate the ventilator without a successful test adding to errors in the measurement 2. Additional external monitoring is re- quired – the ventilator monitors only the average pressures and volume. The system prevents monitoring changes in the individual patients. 3. Even if respiratory mechanics of all 4 patients are the same at initiation, if one becomes sicker, one stays the same, two are getting better, the dis- tribution of gas to each patient is un- equal and unmonitored. The sickest patient gets the smallest VT and the improving patient gets the largest VT. This was clearly evident in the study by Paladino4 wherein all four sheep were observed to have episodes of pronounced decreases in PaO2 and acute hypercapnia likely signifying underventilation resulting from sub- stantial changes in chest mechanics between the animals. 4. Ventilator weaning or ventilator dis- continuation is impossible and the patient who is improving has to be switched to a single ventilator. 5. During airway suctioning of one pa- tient, ventilation of the other patient is interrupted. 6. There are longer term consequences to this approach that paradoxically could worsen the supply of ventilators dur- ing a pandemic. Chief among these is that prolonged use (i.e. > 48 hr) of par- alytic agents may be associated with ICU acquired weakness that prolongs the need for mechanical ventilation. This becomes particularly worrisome as the median duration of mechanical ventilation in SARS and MERS ranges between 8-31 days. In addition, the ability to reduce mechanical ventila- tion duration and ICU length of stay is inextricably related to the ability to perform spontaneous breathing tri- als and daily sedation interruptions. This process is stymied by havingmore than one patient tethered to the same ventilator. To address this issue would require changing the ventilator used for the patient(s) who “appear” to be recovering faster and would consume an extraordinary amount of clinician time and logistics in a situation when intensive care resources are under maximal stress. 7. We refute the “it’s better than nothing defense,” as in a cohort of 4 patients, one of whom may die regardless of maximal efforts, the deterioration in that subject may lead to injury in the other three. 8. We suggest that these videos be re- moved from the internet as they pro- mote a very inexperienced and cavalier approach to a very complicated issue fraught with patient harm. 9. Before any unconventional approach- es like this are used, they MUST be approved by the appropriate Ethics Committees and, in some cases, the Institutional Review Board. Failure to do so could result in severe penalties. What about using artificial resuscitators or minimal function mechanical ventilators? Artificial resuscitators have little utility in caring for the subjects requiring mechanical ventila- tion in this scenario. The use of disposable and limited func- tion ventilators unable to control VT, PEEP, or FIO2 and those with limited inspiratory flow capabilities (limiting the total rate) are