Health minister also explains why dexamethasone helps
Ventilating Covid-19 patients is not always in their best interest, health minister Dr Zweli Mkhize said on Tuesday.
Mkhize said in a statement that despite the fast-growing number Covid-19 patients in SA, the current treatment protocol evidence supported the avoidance of invasive ventilation strategies as far as possible”.
As of Monday night there were 144,264 confirmed cases of the virus across the country. There have been 2,529 recorded deaths.
Mkhize said on Tuesday that health professionals in SA and across the world were “constantly learning more about the behaviour of the virus when it enters the body”.
The avoidance of ventilation was among the newer clinical management protocols.
“This is because when one is very ill, they generate a fight-or-flight response. These hormones drive your body to work harder to breathe, your heart to beat faster to circulate oxygen and nutrients to a body that is demanding more, and for you to be able to pay attention to warning signs such as pain or heat,” said Mkhize.
“When we intubate a patient and ventilate them artificially, this has to be facilitated by sedation and a limited period of muscle relaxation. These processes remove, or significantly dampen, the fight-or-flight response and therefore remove the ability for the patient to physiologically cooperate with the interventions you are making as a doctor.”
He added that it was “always better” to have a patient who could “optimally mount these responses that lead to improved outcomes”.
“We soon expect the ministerial advisory committee on Covid-19 to issue advisories on the use of high-flow oxygen for patients who are very ill but can be managed without intubation and ventilation.”
Dexamethasone ‘reduces damage to lung tissue’
The minister also explained another of the new treatment protocols that was showing success: the prescription of dexamethasone. This, he said, “has shown that deaths can be reduced by a third for patients on ventilators and can also help patients who only need supplemental oxygen”.
Explaining why the medication appeared to work, Mkhize said: “The ‘spikes’ that have become a branding trademark of Covid-19 are made up of proteins that like to interact with a certain receptor, called the angiotensin-converting enzyme 2 receptor (or ACE-2), that is found in large amounts in the alveoli. This causes direct injury to the lung tissue due to a local inflammatory response.
“This response is mediated by a hyperactive immune response system that is meant to deal with the virus. Unfortunately, in ARDS [acute respiratory distress syndrome], this response is exaggerated, resulting in significant and sustained inflammatory damage to lung tissue itself. Oedema (water in the lungs) also forms a part of this pathology.
“With pneumonia, the pathology is slightly different in that the spaces in the lung alveoli fill up with inflammatory sediment causing a consolidation (all the air filled up) of a particular part of the lung. The body can to some extent redirect its blood flow to healthier parts of the lung during pneumonia. We call this shunting. So pneumonia is generally a little bit easier to manage than ARDS, which causes widespread lung damage.
“In both these instances, the process mediating the inflammatory response is an important part of the damage caused.
“Dexamethasone and other corticosteroids exert their effect by attenuating the inflammatory response, thus reducing damage to lung tissue – which means less stiff lungs that are more compliant to the work of breathing or ventilating.
“It is for this reason that we now recommend early administration of dexamethasone to critically ill patients who require oxygen support.”
In the statement, which focused on case management amid a “surge” in infections, Mkhize said the National Institute for Communicable Diseases (NICD) had given an indication of the specific challenges in SA.
He said the NICD looked at 10,700 Covid-19 admissions from 269 facilities across SA, of which 71 were in the public sector and 198 in the private sector, between March 5 and June 21.
These were among the key findings of the study:
- the median age of Covid-19 admissions was 50, with 338 (3%) admissions in patients younger than 18 and 1,386 (13%) older than 70;
- 54% of people admitted were female;
- among 8,245 (77%) patients with data on comorbid conditions, 2,810 (34%) had one condition and 3,126 (37%) had two or more;
- of the 5,836 patients with comorbidities, the most commonly reported were hypertension (3,419 or 59%) and diabetes (2,813 or 48%);
- there were 1,116 (19%) patients admitted with HIV, 240 (4%) with active tuberculosis (TB) and 579 (10%) with a previous history of tuberculosis; and
- obesity was noted by clinicians as a risk factor in 297 (3%) patients.