Pub Maths

Monday 11th May 2020

Figures for 10th May

UK COVID Deaths 269 / Total 31,855

James Cook Hospital – Total COVID deaths – 204

All COVID cases within South Tees Hospitals Trust – 65

James Cook Critical Care COVID cases – 9 (8 ventilated)

James Cook Critical Care non-COVID cases – 30 (12 ventilated)

Things remain relatively quiet at work today. We have only admitted one COVID patient during the day-shift. This is a healthcare worker in her 50’s who at present seems to be managing on CPAP. Compared to the men, many more women are treated successfully with CPAP and do not go on to require intubation and ventilation.

The COVID death rate continues to fall. This is due to the lack of ongoing virus transmission as a result of the lockdown. It is important to understand that the death rate lags significantly behind the date of likely virus transmission. The incubation period for the novel coronavirus is, on average between 5-7 days. Most patients with severe disease spend approximately 3 days at home prior to admission to hospital. They then spend 2-3 days on the ward before becoming so unwell that they need admission to critical care. At this point predicting what and when happens gets a bit hazy.

Some of these patients will be elderly, frail and have sufficiently significant underlying illnesses that admission to Critical Care would not improve their extremely poor prognosis. Other patients will be admitted to the ICU but, for similar reasons, would not benefit from intubation & ventilation should they deteriorate. Others will be placed on ventilators as required but some of these will not survive.

I’m digressing somewhat here. What I am trying to do is work out how much of a lag there is between people getting infected and the death rate rising. I believe that the death rate is the only accurate way in the UK of tracking the progression of the disease.

So, if I were to scribble this down on the back of a beer mat in a pub (oh, happy days!) then I would come up with the following:

Incubation period – 6 days

Time to requiring hospital admission - 3 days

Time spent in hospital prior to death – 7 days

Delay in reporting death – 1 day

Total = 17 days

So, on average, the death rate might lag behind current events by approximately 17 days. This means that if you looked out of your window on VE Day and saw your irresponsible neighbours having it phat and large with all their friends at a street party and wondered if this would affect the death rate, you wouldn’t know until 25th May. Or thereabouts.

The corollary of this is that today’s low death rate is due to the effects of social distancing that happened around 24th April.

It’s important that I cannot emphasise enough, how totally dobbins and whisky-fuelled these calculations are, but it gives you some idea of the time-frame involved.

Meanwhile, back at the hospital, one of the patients we have been looking after today has worsened to the point where he has required intubation and ventilation. The gentleman, who is in his 50’s with some mild asthma has been with us for the past four days, struggling with CPAP in an attempt to buy time while we waited for an improvement that did not come.

This is not surprising; many of our COVID patients who need CPAP will often need it for 4-6 days, sometimes longer. If you’ve not had to wear a tight-fitting CPAP face mask, then it’s hard to understand just what this entails. They are uncomfortable, noisy, hot, claustrophobic and demoralising. It’s hard for some of the patients to see that CPAP is doing them any good when they feel so dreadful. The patients who can remain calm often do better and anxious patients will sometimes be unable to tolerate CPAP for long periods of time. I have written before how patients seem more inclined than ever to believe us when we tell them that, despite how they feel, CPAP can save their life.

Having said that, there comes a point when the viral pneumonitis has caused such damage within the lung that CPAP is no longer enough to maintain oxygenation and the situation rapidly worsens. It is important to recognise that this is about to happen in order to be able to intubate and ventilate the patient in a relatively controlled fashion. If not, there is a risk of respiratory and/or cardiac arrest at the time of intubation and, in the COVID patients, it can be very difficult to recover this situation.

We have been watching our patient, hoping that he can avoid the ventilator but deep-down knowing that this is unlikely. It’s hard to put a finger on exactly what it is that makes us know which patients will manage on CPAP and which won’t. It’s not just a matter of the length of the illness or examining the chest. It’s not looking at the blood results or the chest x-rays or CT scans. It’s not watching the monitor and looking at the numbers, It’s not even seeing how well the patient appears to be doing after you start CPAP, although this may be the most reliable indicator. It’s more a sense that you get when you put all of these things together and add a hard-to-define element that the ladies might call intuition and the gentleman would call experience.

We try hard to keep patients off the ventilator where possible, but it’s not necessarily a disaster if CPAP fails. We have seen many of our ventilated patients recover and we hope that this patient will be one of them.