Simple screening to detect asymptomatic COVID patients entering dental clinics – a suggestion
The recent 'Times Fact India Outbreak Report' suggests that around 22 May 2020 India could see the number of coronavirus cases surge up to 75,000. Experts in India have warned that the country may face a critical shortage of ventilators and intensive care unit staff if coronavirus infections rise rapidly. Also, with Lockdown 2.0 ending on May 3rd the dental community is worried about the post-lockdown risk of infection spread in dental clinics, especially from asymptomatic patients. The entire dental community is busy identifying ways to minimize the risk. Drawing parallels from a recent report published in The New York Times meant for medical hospitals, this article throws light on a simple, easy to do and inexpensive procedure to detect positive but asymptomatic patients who could be entering the dental clinics.
The recent 'Times Fact India Outbreak Report' suggests that around 22 May 2020 India could see the number of coronavirus cases surge up to 75,000. Experts in India have warned that the country may face a critical shortage of ventilators and intensive care unit staff if coronavirus infections rise rapidly. A recent (20th April 2020) opinion published in The New York Times shows how the presentation of respiratory symptoms in COVID patients differs from other patients and how we have been missing the real picture all these days. The article also suggests what medical hospitals, COVID centres and ICUs should do in order to prevent the emerging ventilator crisis.
Also, with Lockdown 2.0 ending on May 3rd the dental community is worried about the post-lockdown risk of infection spread in dental clinics, especially from asymptomatic patients. At least 80 percent of COVID-19 patients may be asymptomatic or could be showing mild symptoms. The entire dental community is busy right now identifying ways to minimize the risk.
So to help the dental community, we have extrapolated the findings from The New York Times article and suggested a simple, inexpensive, and easy-to-do procedure for dentists and dental staff to identify asymptomatic-but-positive patients as soon as they enter the dental clinics. Read on.
Dr Levitan is a physician practising emergency medicine for the last 30 years in the USA, who invented an imaging system (1994) for teaching intubation- the procedure of inserting breathing tubes, and who has been doing research on airway procedures and teaching it to the physicians worldwide for the last two decades.
He has observed that the main problem lies in doctors not detecting the deadly pneumonia early enough, due to the different characteristics of this disease and how it progresses. Detecting the COVID pneumonia early enough holds the key, which if done, can keep patients off ventilators — and alive. His observation comes from his 10 days of experience in managing the COVID patients of Bellevue Hospital, where he saw that even patients without respiratory complaints had COVID pneumonia.
It appears that most COVID-19 patients experience relatively mild symptoms and get over the illness in a week or two without treatment. However, many COVID-19 patients die suddenly although they were not feeling any shortness of breath for many days. This is because of a unique but misleading feature of COVID pneumonia, which is different from typical pneumonia. It is known as silent hypoxia, because of which patients may not complain of breathing problems for many days, even though their oxygen levels are low and their chest X-rays show diffuse pneumonia. It is called “silent” because of its insidious, hard-to-detect nature.
Pneumonia is an infection of the lungs in which the air sacs fill with fluid or pus. COVID pneumonia differs from typical pneumonia in that the lungs in COVID pneumonia patients remain compliant - they continue to expel carbon dioxide without letting it accumulate inside the body, and also because these patients, without realizing it, begin to compensate for the low oxygen in their blood by breathing faster and deeper. In other words, these patients end up injuring their own lungs by breathing harder and harder, and by the time they have noticeable trouble breathing and present to the hospital with dangerously low oxygen levels, many will be requiring a ventilator.
In typical pneumonia cases, patients develop chest discomfort, pain with breathing, and also other breathing problems. In COVID pneumonia, the patients do not complain of shortness of breath, even as their oxygen levels keep falling, and by the time they do, they have alarmingly low oxygen levels and moderate-to-severe pneumonia (as seen on chest X-rays).
Another difference - most patients requiring emergency intubation because of acute hypoxia are in extreme duress - often unconscious or struggling beyond their capacity to take a breath, whereas COVID pneumonia patients with silent hypoxia are completely different - they have minimal apparent distress, despite having dangerously low oxygen levels and terrible pneumonia on chest X-rays.
So the most critical phase is silent hypoxia that keeps the patients asymptomatic for many days, and then progresses rapidly to respiratory failure, so by the time patients go to the hospital, their COVID- pneumonia is already well advanced, and many wind up on ventilators, causing shortages of the machines. And once on ventilators, many patients die.
Putting a patient on a ventilator is not the final step and it's not the end of challenges. Even with patients put ventilators, there are many other things that doctors and nurses are supposed to do, which strains the healthcare infrastructure. Wisdom lies not in having more number of ventilators or putting more patients on ventilators but in preventing the patients from getting to the stage of ventilators, which is a huge win for both patient and the health care system.
So the trick lies in detecting the silent hypoxia in the early stages of pneumonia. What if can do it at home, without requiring to wait for a coronavirus test at a hospital or doctor’s office? What if it is possible by using a common medical device that can be purchased without a prescription at most pharmacies: a pulse oximeter.
Pulse oximeters are very easy to use and understand. These small devices, placed on a fingertip, will show two numbers in a few seconds: oxygen saturation and pulse rate. Dr Levitan observed that the COVID pneumonia patients he saw had oxygen saturations as low as 50 per cent (Normal oxygen saturation for most persons at sea level is 94 - 100 %). So an inexpensive pulse oximeter can detect silent hypoxia very easily.
A lot of dentists are worried right now about the possibility of asymptomatic carriers entering their dental clinics and causing the disease transmission. Compulsory testing with a pulse oximeter as soon as the patient enters the dental clinic can tell you if he has silent hypoxia - even if the patient has not been tested for the virus, or even if his swab test was negative.
Fig 1 given by @airwaycam on twitter. He is an airway obsessed Emerg Doctor from New York. He says "We've been fighting in the wrong zone. We need to fight in BLUE zone, the DETECTION ZONE for SILENT hypoxia. Pulse oximeter--for all COVID patients for 14 days; and for any & all w COVID symptoms (those not tested, or with a negative test-- 30% false negatives)''
- Widespread screening for COVID pneumonia by pulse oximetry — either done at home by patients themselves, or in clinics and hospitals - could provide an early warning system for the kinds of breathing problems associated with COVID pneumonia.
- All patients who have tested positive for the coronavirus should have pulse oximetry monitoring for two weeks, the phase of silent hypoxia - during which COVID pneumonia typically develops.
- All persons with symptoms - cough, fatigue and fevers - should also have pulse oximeter monitoring even if they have not had virus testing, or even if their swab test was negative.
- Lastly, the most important thing. This is for the dentists. Compulsory testing with a pulse oximeter as soon as the patient enters the dental clinic can tell you if he has silent hypoxia - even if he has not been tested for the virus, or even if his swab test was negative.
This summary has come from an article The Infection That’s Silently Killing Coronavirus Patients published in The New York Times on 20th April 2020
War plan COVID pneumonia: We've been fighting in the wrong zone. We need to fight in BLUE zone, the DETECTION ZONE for SILENT hypoxia. Pulse oximeter--for all COVID patients for 14 days; and for any & all w COVID symptoms (those not tested, or w neg test--30% false negatives) pic.twitter.com/lllqIOgHfb
— airwaycam (@airwaycam) April 20, 2020