FiO2:PaO2 calculator: can enter both mmHg and KPa

Ventilator guide

Front of neck access.

Steve Withington shares Ashburton\'s thoughts:

Rural Hospitals have been very busy so far in the NZ fight against COVID, though reporting so far disguises this, as all is at DHB level. In Ashburton so far we have been mostly in preparation mode. One recent rural modification we have made that might work for you is repurposing our operating theatre. We have no negative pressure rooms in Ashburton, which is not ideal in times of COVID, particularly for aerosol generating procedures. However, our operating theatre – which in recent times has only been used for elective gastroscopy procedures (now suspended) – has, like all theatres, a positive pressure ventilation system. Our engineer has kindly reverse engineered this (And assures me it is not that hard), converting it to a negative pressure environment. That will allow us to perform more high risk procedures, like intubation, in that environment without risk of contaminating elsewhere in the admitting unit.

A recent EMRAP (https://www.emrap.org/episode/emraplivecovid1/emraplivecovid) discussion of COVID-19 and airway management discussed a number of issues relevant to rural hospitals, for example, what to do when the ventilators run out, and we are left with the patients in rural. High flow nasal O2 is probably not as concerning as we think for aerosolisation and risk to staff, but, in a negative pressure environment, with appropriate PPE, this may result in bridging of time to ventilation. Similarly, using CPAP, may buy some time though the window may also be very short and transfer arrangements need to be discussed urgently. It seems that higher pressures than usual, are important in recruitment of small airways in the COVID-19 lung disease, and may extend the usefulness of CPAP, both in pre-oxygenation and potentially maintaining someone for a while.

One method of providing CPAP in an ongoing way, without using up our one NIV machine, is to connect a CPAP mask with a Bag Valve Mask (connected to high flow O2) via a viral filter, pressuring the line with O2 (6 l/min) via the CO2 port, and using a PEEP valve on the BVM, titrated up higher than usual, as necessary (to 15-18cm) (https://emcrit.org/pulmcrit/cpap-covid/). No machine so less staff-intensive. We hope this will prove a viable way to look after a cohort of sick people in a time of restrictive ICU spaces, but at least it may help with pre-oxygenating someone prior to intubation. With a well-fitting CPAP mask the risk of aerosolisation should be small (but we should use N95 masks around these people for sure). Low threshold for some ketamine dissociative dosing to stop lots of coughing, fighting the mask, and risking infection control breaches.

There has been a lot of discussion around PPE, and clearly intubation needs the highest level of protection: with N95 masks, full visor, neck protection, gown, gloves, viral filters, and also videolaryngoscopy if possible – to maintain maximum feasible distancing from the infected airway. Having someone supervise the removal of PPE after procedure is finished is crucial as this is probably as risky a procedure as the intubation itself. Evidence from Singapore on PCR testing of air and environmental samples in 3 symptomatic patient rooms for PCR detection supports continued use of surgical masks as aerosolisation was not detected, though environmental contamination highlighted the importance of PPE and regular cleaning. (https://jamanetwork.com/journals/jama/fullarticle/2762692).

I’m keen to hear if people have rural hospital related issues with COVID-19 so I can try to escalate these to the Ministry of Health via the College. And let’s keep sharing potential solutions as we find them that work for our environments.

Cheers, Steve (steve.withington@cdhb.health.nz)

Jared is a infectious disease specialist and rural hospital doctor who currently works at Waikato hospital, Waikato DHB.

Matilda is a rural hospital doctor who works at Taupo hospital and is a convener on GENA 728 cardiorespiratory medicine in rural hospital medicine and the Continuing Medical Education Chief for the Rural Postgraduate programme.