Skip to main content

PPE--personal protective equipment. How we can have enough in the era of Covid-19.

We doctors are worrying about shortages of personal protective equipment. PPE is what we call it. When we see a patient with a disease that could be transmitted to others, we wear things that cover our bodies that can either be washed or thrown away. Infections can be spread by contact, by droplets or aerosols. We have different precautions for each type and within these categories, what we do depends on precisely which kind of infection we are worried about. We also, since the advent of HIV, use "universal precautions" to protect ourselves and our patients from bloodborne pathogens that we may have no reason to suspect but might be present anyway.

Universal precautions include wearing gloves for any procedure that involves contact with a patient's blood or body fluids or presents a significant risk for that, such as drawing blood or cleaning wounds.

Diseases such as influenza or certain pneumonias are transmitted by droplets. For those infections we need to use a mask and ideally the patient will use one too. Contact precautions, requiring the use of gowns and gloves, cleaning equipment we use on the patient before re-use, is for things like infectious gastroenteritis (stomach flu, norovirus), Clostridium difficile and resistant bacterial infections such as MRSA. Airborne precautions are for diseases such as tuberculosis, measles and chickenpox. Those require a mask that filters out most particles. The N95 mask filters out 95% of airborne particles. The N stands for "not" oil resistant since these masks are also used for industrial particle protection. We also use a helmet type device called a PAPR or powered air purifying respirator. This has a little battery powered HEPA filter that creates airflow inside a plastic shield that hangs off of a well fitting lightweight helmet.

Covid19 is carried by droplets but viruses also can move as an aerosol. The arosolized viruses can float further than a droplet and when the virus lands it is viable for hours to days. Protection in this case includes droplet, aerosol and contact precautions. So that means we should use a gown, gloves and a mask at least as good as an N-95. N-95 masks work if they have been fitted to a person's face and don't allow air around the sides. When I was fitted for my N-95 mask, a skilled occupational medicine nurse at my hospital found the right size and showed me how to put it on. She then put a hood over my masked head and sprayed a few small but pungent particle sprays in the hood to see if I could taste or smell them. The small size mask fit me well so that is the size I wear. Nobody in my clinic that I know of has been fitted for N-95 masks and we don't have any in my clinic anyway. We use the much more common surgical mask that is only effective for droplet transmission or a PAPR for very high risk patients. We also use gloves and disposable gowns. All masks and gowns and perhaps gloves are available only in the numbers that we normally use, so we're going to run out in places with a high volume of visits. We will run out even in places where Covid19 doesn't overrun us because we will be using them, appropriately, for everyone we suspect of having it.

The good news is that the virus causing Covid19 does not live forever on dry surfaces. A group of researchers in Hamilton, Montana looked at the survival of virus on various dry surfaces and found that it survives best on metal and plastic, up to 72 hours, but less well on copper or cardboard. This means that it would be possible to "quarantine" our masks and gowns for some number of days and re-use them in rotation. This would be especially safe in equipment we used just to be super safe around a person with a cough or sore throat who turned out to be very unlikely to have Covid19. If we put the (not grossly soiled) PPE in a bag with a date on it we could be quite sure that it would be safe to re-use after 5 days. This will not help the hospitals already at the end of their supplies. There will also be attrition of PPE as it gets ratty, torn, soiled or breaks. We still need all of the ideas for increasing supply of this stuff, especially to the hardest hit areas of the country.

Be aware, though, that the longer the virus is away from the host, the less infectious it will be. This applies to our home situations as well. Right after being sick with this virus our homes will have viable virus around. When we are well, however, it won't take long for the virus in our environment to be well and truly gone. Cleaning and disinfecting may be a good idea but once people in the home are well and immune it won't be strictly necessary.

Making masks out of cloth is probably not terribly useful except in situations of dire need since it would be very difficult to make a mask that was able to protect against aerosols. But droplet protection is better than nothing, especially for people working outside of healthcare. I saw a hilarious and probably effective mask from Tbilisi, Georgia, on a guy in a bus. It was a 5 gallon water bottle with the bottom cut off, attached to a sweater, with a baffle at the neck of the bottle which was at the top. Not attractive, certainly, but most likely very effective. Also encourages social distancing!


Popular posts from this blog

How to make your own ultrasound gel (which is also sterile and edible and environmentally friendly) **UPDATED--NEW RECIPE**

I have been doing lots of bedside ultrasound lately and realized how useful it would be in areas far off the beaten track like Haiti, for instance. With a bedside ultrasound (mine fits in my pocket) I could diagnose heart disease, kidney and gallbladder problems, various cancers as well as lung and intestinal diseases. Then I realized that I would have to take a whole bunch of ultrasound gel with me which would mean that I would have to check luggage, which is a real pain when traveling light to a place where luggage disappears. I heard that you can use water, or spit, in a pinch, or even lotion, though oil based coupling media apparently break down the surface of the transducer. Or, of course, you can just use ultrasound gel. Ultrasound requires an aqueous interface between the transducer and the skin or else all you see is black. Ultrasound gel is a clear goo, looks like hair gel or aloe vera, and is made by several companies out of various combinations of propylene glycol, glyce

Actinic Keratoses and Carac (fluorouracil) cream: why is this so expensive?

First, a disclaimer: I don't know why Carac (0.5% flourouracil cream) is so expensive. I will speculate, though, at the very end of this blog. Sun and the skin: what happens If a person reaches a certain age, has very little pigment in her skin, and has spent lots of time in the sun, bad stuff happens. The ultraviolet radiation of the sun does all kinds of great things: it makes us happy, causes us to synthesize vitamin D which strengthens our bones and it gives us this healthy glow until we get old and wrinkled and leathery. And even that can be charming. The skin cells put up with this remarkably well for a long time, partly aided by melanin pigment which absorbs the radiation, which is why we tan and freckle, if we are fair skinned. Eventually, though, we absorb enough radiation that it injures the skin and produces cells which multiply oddly. It also damages the skin's elasticity which creates wrinkles. The cells which reproduce in odd ways peel, creating dry skin or

I'm now a certified ultrasonographer: passing the ARDMS test

I just finished taking an exam for the American Registry of Diagnostic Medical Sonography. Having passed it, I can now put RDMS after my name, standing for Registered Diagnostic Medical Sonographer. The RDMS is a credential that many ultrasound technicians carry, and occasional physicians, especially those who make ultrasound part of their practice. So now, should I ever be at loose ends, I can potentially get a job as an ultrasound tech. To take the ARDMS qualifying test, one must first satisfy various requirements, which fit into categories meant to include ultrasonographers of great experience, ultrasonographers who have gone through a training program (usually 1-2 years) physicians who studied ultrasonography extensively during their medical school and residency training and physicians whose experience includes extensive review of hundreds of scans by experts. Proving experience requires letters from a supervising teacher. The exam is a proctored 5 hour test, 3 of which is i