Get Ready for a 1918-like Scenario
Eric Toner, MD | March 13, 2020
My colleagues and I just submitted to medRxiv a paper on what a Wuhan-like epidemic would do to US ICUs. https://medrxiv.org/cgi/content/short/2020.03.09.20033241v1 The bottom line is that demand would far exceed capacity, and some people in need of critical care would not be able to get it. But it is not just Wuhan; Italy is currently in the midst of a similar outbreak, and critical care services are overwhelmed there, too.
The encouraging news, however, is that it seems that community mitigation strategies—such as isolating the sick, home quarantining the exposed, canceling mass gatherings, and social distancing—have worked to tamp down the height of the epidemic wave and therefore have kept the healthcare systems functional in other parts of China, Hong Kong, Singapore, South Korea, and Japan. But to be effective, these measures need to be vigorously implemented several weeks before hospitals become overwhelmed.
Applying Wuhan data to the average US city
To make this very clear, let’s do a thought experiment and look at some simple calculations based on data from our recent research. On the peak day of the outbreak in late February, there were slightly more than 2,000 COVID-19 patients in critical condition in Wuhan. Based on the estimated remaining adult population in Wuhan at that time, we can calculate the per capita fraction requiring critical care = 259 per million.
We can estimate from census data the adult US population (minus veterans who get care at the VA health system) = 261 million. There are an estimated 46,500 medical ICU beds in the United States, or 178 per million. But approximately 70% to 80% are in use on any given day, and even more are occupied right now in flu season. So, in an average US metropolitan area of 1 million, we might expect there to be only 36 to 53 empty staffed ICU beds unless some intervention is made. Hospitals have other kinds of ICUs: surgical units, neuro units, cardiac units, etc. Together these approximately double the number of ICU beds. Of course, they are normally usually pretty full, too. In addition, some hospitals have plans to take over other spaces for critical care, such as PACU, cath prep and recovery, endoscopy, etc. And these can add some additional surge capacity.
Assuming we could double ICU capacity with maximal effort, using all of the above and contingency standards of care, if we are lucky, we could have about 214 ICU beds available. Still not enough! Unless patients can be transferred, we would then enter the uncharted territory of having to ration life-saving care in order to save the most lives—something we have never done before in an organized way.
The story is similar for ventilators. If we used every single ventilator that can be used for an adult with ARDS/severe pneumonia (including transport vents, anesthesia machines, pediatric vents, etc.), and after accounting for other patients who normally need mechanical ventilation, we might have as many as 380 ventilators, which would be enough but would come at a crippling cost to the facility that would have to cancel most surgeries and procedures. It would also require crisis standards of care to have enough staff to operate the ventilators.
We have to keep in mind that these calculations are based on an average US city, but the prevalence of ICU beds varies by a factor of 2 across the United States. So, some areas will do better than this, but others might be even more severely affected.
What this means for hospitals
The experience of Wuhan and northern Italy is as bad as or worse than 1918. The case fatality ratios in these locations now are twice what the United States experienced in 1918. Other places have been able to avoid such a dire situation by aggressive public health and community mitigation interventions. For hospitals, while we can hope for the best, we cannot exclude the possibility of a Wuhan-like outbreak in your city. Hospitals should be all-out preparing now for their worst-case scenario.
What this means for the general public
For all of us, we need to keep our hospitals functioning so that if we get sick with COVID-19 or have a heart attack or stroke, we can get appropriate care. To do this we all play an essential role. The reason schools may close and gatherings may be canceled is to slow down the epidemic and spread it out over time, so fewer people are sick all at the same time. We must adhere to public health guidance and accept the temporary hardships that implies. We have to hold 2 disparate ideas in our heads: It is true that the personal risk of COVID to the average young and healthy person is quite small, but at the same time the risk to the healthcare system upon which we all depend is very high.