Don’t try this at home. 27.04.20

April 27, 2020 Good Soldier

Welcome to the Plague Pit – issue number 10. First – a quick update on the possible benefits of PPE.

This week sees the publication of a paper on COVID-19 deaths in 119 NHS staff, 98 of them in patient-facing roles. Taking into account the number of people employed in the NHS, this number ‘does not clearly show that healthcare workers are dying at rates proportionately higher than other employed individuals or even the population as a whole’. (1)

Two other findings are of interest. NHS staff from black and minority ethnic (BAME) groups appear to be at greater risk of COVID-19 related death than their non-BAME counterparts. BAME staff make up 21% of NHS staff but 63% of NHS deaths. I hope to look at why this might be in another issue

The first author of the paper is Tim Cook, a prominent anaesthetist. He led a national project I was involved with a few years ago, on unintended awareness under general anaesthesia.

The finding of his that’s causing all the talk among my colleagues is this. None of the COVID-19 deaths appear to have occurred in medical, nursing or physiotherapy staff involved in intensive care or anaesthesia. These ‘are believed to be among the highest risk groups of all healthcare workers’.

As Tim writes: ‘What is likely is that that these groups of staff are rigorous about use of personal protective equipment and the associated practices known to reduce risk.’

Down the hatch?

In the light of recent announcements from the US, I’ll continue with some medical advice. Injecting disinfectant is a bad idea. Intravenous disinfectant, specifically, has been used as a murder weapon. (2)

Splash it all over?

Disinfectants are used to kill or eliminate microorganisms and/or inactivate viruses on inanimate objects and surfaces. Antiseptics are used on living tissues to the same end. The American Society of Microbiology has published a good review of the differences, which may not have made it to the right bedside table (3)

Before any external skin incision, a surgeon will prepare the site with an antiseptic solution. Antiseptic solutions are also used internally sometimes. Chlorhexidine mouthwashes may help in gum disease (periodontitis), for example. They also lower the risk of ventilator-associated pneumonia (VAP) in intubated intensive care patients (4) by killing mouth bacteria. It’s unclear, though, whether killing those same bacteria with antiseptic solutions before operations in the mouth prevents postoperative wound infections. Many surgeons don’t bother (5)

The use of disinfectant in the mouth, rather than antiseptic, is very dangerous indeed. I have given anaesthetics to a few patients who attempted to commit suicide by swallowing bleach – a disinfectant solution. Damage to the oesophageal lining was extensive and severe. In survivors of this injury (many die), the scarred sections of oesophagus may even require replacement with a portion of the patient’s own bowel.

In other bleach survivors, the disinfectant quickly erodes through the oesophageal wall into the mediastinum, the space surrounding the oesophagus and between the lungs. The mediastinum also contains the heart and major blood vessels.

Oesophageal perforations like this may also require very complicated surgical management. Below is a link to a 1:30 min video recording, taken though an endoscope – a fibreoptic camera introduced through the mouth. The video shows a T shaped tube being positioned by the endoscopist in the perforated oesophagus of a bleach survivor. The perforation can be seen on the right of the screen at about 1:22 min, with the stem of the ‘T’ passing horizontally through it from left (inside the oesophagus) to right (mediastinal cavity, not visible).

This will allow any caustic stomach contents that come up into the oesophagus to drain safely to the outside. The patient’s history and other details appear in the article cited below, together with more diagrams.

https://commons.wikimedia.org/wiki/File:Endoscopic-T-tube-placement-in-the-management-of-lye-induced-esophageal-perforation-Case-report-of-1754-9493-3-19-S1.ogv

Both from: McMahon MA et al. Endoscopic T-tube placement in the management of lye-induced esophageal perforation: Case report of a safe treatment strategy. Patient Safety in Surgery volume 3, Article number: 19 (2009) (6)

Returning gratefully to antiseptics, these may be useful elsewhere in the body. Many surgeons swill povidone-iodine antiseptic (PI) round the cavities they create to receive artificial body parts – or prostheses’ – such as metal joints and breast implants. Where there’s a prosthesis, fewer bacteria are needed to cause an infection (7) Evidence that cavity washout before prosthesis insertion reduces the risk of future infection is weak. (8)

Surgeons sometimes apply PI internally if they suspect or know that there is severe bacterial contamination. Bites and other dirty wounds routinely get flushed with PI intraoperatively. Some surgeons use it during laparotomies, washing it round the abdominal cavity if there has been major leakage of colonic contents. Again, the available studies don’t really give a clear picture if this helps (9). Some animal experiments suggest that PI used in this way does a good deal of harm (10)

Hard evidence (‘hard’ as in ‘difficult’)

Perhaps that’s enough bowel surgery for now. Back to COVID-19.

From the section above, I hope you can see that even for a really ‘obvious’, well-established intervention – antiseptic application to reduce the risk of infection – the collected evidence can be equivocal. It may also be voluminous, variable in quality and of limited relevance in different clinical contexts.

A new problem like coronavirus presents a further problem. Whether the proposed interventions are clinical ones to treat individual patients or societal ones aimed at reducing viral spread, there has simply not been time to accumulate any significant evidence for their effect.

With this in mind, I’m grateful to Dr Graham Winyard, of Barton Peveril Sixth Form College, for drawing my attention to this recent article about doubt, science and coronavirus.

https://www.theguardian.com/commentisfree/2020/apr/21/doubt-essential-science-politicians-coronavirus

Kills all known germs

In times of doubt – especially mortal doubt – speculation thrives. The propagation of inaccurate scientific information has been a hallmark of this pandemic. (11) I’m sure I’ll be returning to fake news in future issues but in the meantime, I am confident that injecting or swallowing disinfectant is not a useful treatment for COVID-19.

Patients on intensive care with life-threatening infections sometimes end up on a several antimicrobial drugs. Microbiologists will advise on which ones, choosing them for their known effects against specific organisms identified in tissue samples from the patient. At least one antibiotic is usually involved – an example is meropenem. Active against three main categories of bacteria (gram-positive, gram negative, anaerobes), this tends to be reserved for infections caused by bacteria in the patient that have been shown to be resistant to more traditional ones.

Long term intensive care patients often test positive for multiple organisms, some of which become a problem in hospital. Sometimes it is not clear which organisms are causing the damage. So, rarely, a very sick patient may end up on an antifungal (e.g. amphotericin B) and an antiviral (e.g. gancyclovir) as well as one or more antibiotics. Occasionally doctors refer to such a combination, flippantly, as ‘Domestos’. They don’t mean it literally.

I spoke to one of our intensivists about some of his COVID-19 patients recently. They are all on one or more antimicrobial drugs – none of them antivirals. The drugs are being used to treat secondary bacterial infections that have become evident after admission with COVID-19.

Some COVID-19 patients in my hospital have been enrolled into clinical trials. My research colleagues are looking at a number of different treatments and drugs, including those effective against other viruses. Several trials like this are going on around the world. The most reliable summary of the options that I can find right now is this:

Sanders JM et al. Pharmacologic Treatments for Coronavirus Disease 2019 (COVID-19)A Review. JAMA. Published online April 13, 2020. doi:10.1001/jama.2020.6019 (. https://jamanetwork.com/journals/jama/fullarticle/2764727

The paper ends with this sobering paragraph:

‘The COVID-19 pandemic represents the greatest global public health crisis of this generation and, potentially, since the pandemic influenza outbreak of 1918. The speed and volume of clinical trials launched to investigate potential therapies for COVID-19 highlight both the need and capability to produce high-quality evidence even in the middle of a pandemic. No therapies have been shown effective to date.’

If that seems too downbeat, here’s another abstract from “The New England Journal of Medicine” to finish this week’s issue: