HJBR May/Jun 2020

16 MAY / JUN 2020 I  HEALTHCARE JOURNAL OF BATON ROUGE AMERICAN ASSOCIATION FOR RESPIRATORY CARE SARS CoV-2 GUIDANCE What are the major findings in patients with SARS CoV-2 viral pneumonia requiring mechanical ventilation? Patients who require mechanical ventilation are severely ill. The intensity of treatment parallels treatment for any severe ARDS patient. The preponderance of evidence is for se- vere hypoxemic respiratory failure in the most critically ill subjects. Of note, pulmo- nary compliance appears to be reduced but not to levels typically seen with ARDS. In a recent ESICMpresentation, Pesenti reported on 672 patients fromLombardy, Italy.1 In this cohort, the median PEEPwas 14 cmH2Owith the majority of patients managed between 10 and 20 cm H2O (25%-75% percentile 12 - 15 cm H20). The median FIO2 was 0.55 with the 25%-75% percentiles of 0.45 and 0.70. Nearly 30% of patients required an FIO2 of 0.70 or greater. adjustments in preset Vt tomaintain alveolar ventilation. During SARS-CoV-1 in Canada, following identification of the infection, patients testing positive for SARS were placed on ventilators with heated expiratory filters. The impact on transmission following this change was dif- ficult to measure. To date, COVID-19 has not been associ- ated with increased airway secretions. We do not know if using an HMEF makes an expiratory filter redundant. An expiratory filter may provide additional protection of the environment. Can the SNS stockpile ventilators manage patients with COVID-19? The LTV-1200 and the Impact 754 can both be used to treat the majority of patients described to date. (Please see the videos for use at the AARC website.) In the recent report from Seattle byArentz et al,2 in a series of 21 subjects, more than half had severe ARDS (57%) with a mean PaO2/ FIO2 at admission of 169 (69-492) and a nadir PaO2/FIO2 108 (58-247). Humidification An HMEF or heated humidifier can be used in these subjects. While heated humidification has advan- tages, the use of a heat and moisture ex- changing filter (HMEF) can provide suffi- cient humidification while also protecting staff and the environment. These can be stan- dard filters or HEPA filters. Caution: the use of HMEFs increases mechanical deadspace by ~30 mL, which for an average sized adult translates to 0.5 mL/kg and an increase in VD/VT of 8%. As VD/VT in moderate and severe ARDS typically is ~0.60 and ~0.70, these devices likely will require similar small “There have been suggestions in the media that CPAPmachines 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.”