COVID-19

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COVID-19\: contagious respiratory disease caused by SARS-CoV-2.
Transmission\: respiratory droplets, saliva, contaminated surfaces; incubation time ~5 days, infectivity 1-3 days before
symptoms.
Pathophysiology\: enters nasal epithelial cells via ACE-2 receptor, immune response causes di
pulmonary oedema, endothelial damage, procoagulant state, multi-organ e
Risk factors\: close contact with infected person, old age, healthcare/care home settings; male sex, Asian/Afro-Caribbean
ethnicity, comorbidities (chronic respiratory disease, type 2 diabetes, heart failure), smoking.
Symptoms\: fever, new continuous cough, altered smell/taste, dyspnoea, fatigue, myalgia, pharyngitis, delirium, reduced
mobility in elderly.
Clinical
urticaria, petechial rash).
Investigations\:
Bedside\: COVID-19 swab (RT-PCR), pulse oximetry, sputum culture, arterial blood gas.
Laboratory\: FBC, CRP, U&Es, LFTs, coagulation screen.
Imaging\: chest X-ray (bilateral ground-glass opaci
Management\:
Conservative\: self-isolation (10 days), symptom management, hydration, nutrition.
Medical\: oxygen therapy, antipyretics, dexamethasone (severe disease), remdesivir (severe disease), empirical antibiotics (if
bacterial co-infection), VTE prophylaxis (e.g., enoxaparin).
Ventilation\: CPAP (type 1 respiratory failure), NIV (type 2 respiratory failure), mechanical ventilation, ECMO (severe cases).
Complications\:
Disease-related\: VTE, acute kidney injury, septic shock, cardiovascular complications,
“Long COVID” (persistent symptoms
>12 weeks).
Treatment-related\: hyperglycaemia (dexamethasone), ventilator-associated lung injury/pneumonia, laryngeal injury.
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A comprehensive topic overview

Introduction

Coronavirus disease 2019 (COVID-19) is a contagious respiratory disease, caused by the severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2).
1
In the year since the
deaths worldwide.
2Aetiology
SARS-CoV-2 is primarily transmitted through respiratory air droplets, which are expelled when an infected person talks,
coughs and sneezes.
3
SARS-CoV-2 can also be transmitted through saliva and by touching contaminated surfaces, although it signi
decays on surfaces within 72 hours.
4
The virus has been detected in other bodily
5
The mean incubation time (time from exposure to symptom onset) is
6
Infectivity begins one to three days before symptom onset and can last for 10 days in mild-moderate cases, and even
longer in severe cases. 7
There are several variants of SARS-CoV-2, and more variants continue to be discovered. Some
variants are more infectious than others.
8
Pathophysiology
SARS-CoV-2 enters nasal epithelial cells via the ACE-2 receptor and then migrates to the upper respiratory tract. This
triggers an immune response, including the release of interferons (IFN-β and IFN-γ) from infected cells.
9
In most patients, the immune response halts the spread of the virus at the upper respiratory tract, and so most patients only
develop mild symptoms. However, in approximately 20% of patients, the virus progresses to the lower respiratory tract.
10
Infected pneumocytes release in
(including T helper cells).
11
The exaggerated immune response to SARS-CoV-2 results in di
with acute respiratory distress syndrome).
12
SARS-CoV-2 also causes damage to endothelial cells, which are found in the inner layer of blood vessels (Figure 1).
Endothelial dysfunction results in a procoagulant state, leading to thrombotic complications (such as pulmonary
embolism and microvascular thrombi in the lungs).
13
There is emerging evidence that SARS-CoV-2 can a
potentially through its ability to disrupt endothelial surfaces and incite exaggerated immune responses. 14-15
symptoms which persist months after the acute infection (often referred to as “Long COVID”).
This can cause
Figure 1. Cross-section of an arterial wall showing the location of the endothelium,
which can be damaged in COVID-19.
16

Risk factors

The following risk factors are associated with an increased risk of contracting COVID-19\:
Close contact with an infected person (within one metre for at least 15 minutes)
Old age
Residence or employment in an area with increased transmission (such as healthcare settings or care homes)The following risk factors are associated with an increased risk of developing severe COVID-19 infection\:
Male sex
Asian and Afro-Caribbean ethnicity
17
Medical comorbidities (including chronic respiratory disease, type 2 diabetes and heart failure)
Current or former smokers

Clinical features

History
Typical symptoms of COVID-19 include\:
Fever
New and continuous cough (typically described as dry, but may be productive)
Altered sense of smell and taste
Dyspnoea (initially on exertion, but may progress to resting dyspnoea)
Non-speci
Delirium and reduced mobility in the elderly
Other important areas to cover in the history include\:
Recent contact with suspected or con
Smoking history\: quantify in pack-years (1 pack-year = smoking 20 cigarettes a day for a year)
Travel history\: the patient may have travelled from an endemic area
Clinical examination
A full respiratory examination should be performed in suspected cases of COVID-19.
Typical clinical
Tachypnoea and tachycardia
Crepitations and bronchial breathing on auscultation
Cutaneous manifestations\: such as maculopapular rash, urticaria and petechial rash (Figure 2)
Figure 2. Petechial rash, which can occur in COVID-19.
18

Di

Di
Community-acquired bacterial pneumonia
In
Common cold
Middle East Respiratory Syndrome (MERS)
Aspiration pneumoniaInvestigations
Bedside investigations
Relevant bedside investigations include\:
COVID-19 nasopharyngeal and/or oropharyngeal swab\: the swab is used to sample the respiratory mucosa. The sample
is analysed using real-time reverse-transcription polymerase chain reaction (RT-PCR). A positive result indicates the
presence of SARS-CoV-2 viral RNA.
Pulse oximetry\: aim for 94-98% initially, but the target saturations may be reduced to 88-92% if the patient has COPD (this
is a risk-bene
Sputum culture\: to exclude other causes of lower respiratory tract infection, including bacterial causes.
Arterial blood gas\: recommended in patients with low oxygen saturations or signs of respiratory distress. May show type
1 or type 2 respiratory failure. May also show elevated lactate, which indicates tissue hypoxia and organ dysfunction.
Laboratory investigations
Relevant laboratory investigations include\:
Full blood count\: may show leucocytosis and lymphopenia
CRP\: may be elevated
U&Es\: may be elevated and indicate acute kidney injury
LFTs\: may be elevated (associated with severe disease)
Coagulation screen\: may show elevated D-dimer and prolonged prothrombin time (both associated with severe
disease).
19
Imaging
Chest X-ray
A chest X-ray may reveal bilateral ground-glass opaci
Ground-glass opaci
pulmonary vasculature or bronchial structures.
20
CT chest
National guidelines recommend CT chest for patients with severe disease when chest X-ray is unclear or normal (though
local guidelines may vary).
21
Common CT chest
peribronchovascular thickening (thickening of the connective tissue that encloses the bronchi and pulmonary arteries).
22Figure 3. Chest X-ray in COVID-19 pneumonia, showing bilateral ground-glass opaci
23
Figure 4. CT chest in COVID-19 pneumonia, showing bilateral ground-glass opaci
24

Management

Conservative management
Conservative management of COVID-19 includes\:
Self-isolation\: at the time of writing, all COVID-19 cases and their close contacts must self-isolate for 10 days. Self-
isolation should continue after 10 days if the patient still has a fever, rhinorrhoea, malaise or diarrhoea.
25
Symptom management\: such as honey to reduce cough frequency, and discouraging patients from lying on their back
as this reduces cough e
Adequate hydration and nutrition.
Medical management
Medical management of COVID-19 includes\:
Oxygen therapy\: to maintain target saturations 94-98% (or 88-92% if the patient has COPD)
Antipyretics\: such as paracetamol
Dexamethasone\: used in severe disease (such as oxygen saturations \<90% on room air, sepsis or ARDS). The dose is
6mg once daily for 7-10 days.
26-27
Remdesivir\: this antiviral may be used in severe disease (this is a senior-led decision). Remdesivir is usually given as a
loading dose of 200mg IV on day 1, followed by 100mg IV for 5-10 days.
28,29
Empirical antibiotics\: only recommended if bacterial co-infection is suspected. Signs of bacterial co-infection include a
change in symptoms (such as new pyrexia), new neutrophilia and radiological
pneumonia.
30
Venous thromboembolism prophylaxis\: used in hospitalised patients as COVID-19 increases the risk of venous
thromboembolism. Low-molecular-weight heparins are commonly used (such as enoxaparin).
Ventilation
Options for ventilatory support in COVID-19 include\:
Continuous positive airway pressure (CPAP)\: may be used in type 1 respiratory failure (PaO 2
\< 8kPa/ 60mmHg).
31
Non-invasive ventilation (NIV)\: may be used in type 2 respiratory failure (PaO 2 2
\< 8kPa / 60mmHg and PaCO 45mmHg).
> 6.0kPa /
Mechanical ventilation\: may be needed if the patient continues to deteriorate despite optimal use of CPAP or NIV.Extracorporeal membrane oxygenation (ECMO)\: may be needed if the patient continues to deteriorate despite
mechanical ventilation and if the patient has potentially reversible respiratory failure. ECMO involves diverting the
patient’s blood to an arti
blood is then pumped back into the patient’s circulatory system (Figure 5). The decision to start ECMO is senior-led, and
ECMO is only performed in specialist centres.
Figure 5. Schematic diagram of extra-corporeal
membrane oxygen (ECMO).
32

Complications

Disease-related complications
Disease-related complications include\:
Venous thromboembolism (e.g. pulmonary embolism)
Acute kidney injury
Septic shock
Cardiovascular complications (e.g. acute coronary syndrome and myocarditis)
“Long COVID”
\: approximately 10% of COVID-19 patients display symptoms for 12 weeks or more after the initial
infection. 33 34
These symptoms include persistent cough, lethargy and myalgia.
Treatment-related complications
Treatment-related complications include\:
Dexamethasone\: hyperglycaemia and confusion
Mechanical ventilation\: ventilator-associated lung injury (VALI), ventilator-associated pneumonia (VAP) and laryngeal
injury

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Reviewer

Dr Bhamini Puvaneswaran
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