COVID-19 Flashcards
Pathogenesis.
a) Viral cause
b) Receptor
c) Risk of mild illness (flu-like), severe (pneumonia) and critical (ARDS)
d) Incubation period
e) Transmission
f) Median time from symptom onset to: i) ICU admission, ii) death or recovery to discharge
a) Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2)
b) Angiotensin converting enzyme 2 (ACE-2)
- Same as for SARS-Cov (i.e. SARS)
- Found in lungs, heart, kidneys, etc.
- Up-regulated by ACE inhibitors and NSAIDs (so patients on these may have more severe disease)
c) Mild - 80%
Severe - 15%
Critical - 5%
- Note: risk higher in older patients/ those with comorbidities such as as diabetes, heart failure, etc.
d) 5 - 11 days
e) - Aerosol - coughing, sneezing, contaminated particles on surfaces (direct contact)
- Also found in blood and stool in lower quantities
f) i) 10 days (1 -2 weeks)
ii) 2 - 3 weeks
Presentation.
a) Main symptoms core features
b) Other common features
c) Less common features
d) Signs o/e
a) • Fever (37.8 C or higher), +/- chills, rigors
• Cough (new and continuous; usually dry)
• Dyspnoea - may warrant hospital admission
• Altered sense/loss of smell/taste
b) • Headache • Myalgia • Fatigue • Sore throat • Anorexia
c) • Resp - Sputum production, haemoptysis
• GI symptoms - Diarrhoea, nausea/vomiting, abdo pain
• Neuro - Confusion, dizziness
• Rhinorrhoea, conjunctival congestion
• Chest pain/ palpitations (may indicate myocarditis)
d) - Fever, tachycardia
- Pneumonia/ARDS - hypoxia, tachypnoea, cyanosis, confusion, crackles/bronchial breathing/etc.
- Pharyngitis/ tonsillar enlargement
- “Silent hypoxia” - hypoxia without any SOB
Preventive measures: community
Hygiene.
- Hand washing, cough/sneeze hygiene
Containment.
- Isolation of confirmed/suspected cases
- Contact tracing
- Household/close contact quarantine
Mitigation/suppression.
- Social distancing
- School/university/workplace closures
- Closure of public places (eg. pubs, restaurants, shops)
- Banning public gathering
- ?Vaccine
Preventing nosocomial infection
- Isolation of suspected cases
- Wear PPE
- Hand-washing
- Dispose of clinical waste
- Limit visitors/ contact
- Sterilise rooms/ equipment used by COVID-19 cases
- Testing of staff
Investigations in hospital
a) Diagnostic investigations
b) Bedside/bloods
c) Imaging
Diagnosis.
- Nasopharyngeal and oropharyngeal swabs*
(+/- sputum samples if obtainable)
- Send for reverse transcriptase PCR (RT-PCR) - 75% senstive
- If negative but high suspicion of infection, take further samples for testing
- May also be positive for influenza A/B or other viruses
- Stool samples may be positive for COVID
- Can be taken as: a) individual nose and throat swabs in separate collection tubes; OR, b) Combined nose and throat swab in one collection tube containing universal transport medium; OR, c) single swab used for throat then nose
- In patients with severe lower respiratory symptoms, consider taking broncho-alveolar sample but ensure full PPE (including visor and FFP3 mask) as this is likely an aerosol generating procedure
Bedside.
- Pulse oximetry
- ABG (low PaO2, ?raised PaCO2)
- Blood cultures
- Sputum cultures
Bloods.
• FBC (cytopenia*, eg. thrombocytopenia or lymphopenia, - poor prognostic indicator)
• U+E (calculate CURB-65 score, AKI, deranged electrolytes - e.g. hypoK/hypoCa)
• LFTs (elevated ALT and bilirubin, low albumin)
• Coagulation screen (raised D-dimer common, if also raised PT/low fibrinogen -?DIC)
• Inflammatory markers (CRP, procalcitonin)
• Serum troponin (raised)
• Serum ferritin (raised)
• Serum lactate dehydrogenase (raised)
• Serum creatine kinase (raised)
*Cytopenia + unremitting fever + raised ferritin = cytokine storm
Imaging.
- CXR - in those with pneumonia, you will likely see lung infiltrates (25% unilateral, 75% bilateral)
- ?CT - bilateral ground glass opacity/ consolidation, crazy paving pattern, interlobular septal thickening
Management of suspected cases.
a) Immediate
b) Supportive treatments in non-ICU environment
c) ICU treatments
d) Experimental treatments
a) - Immediately isolate and don PPE, etc.
- Take observations and swabs for RT-PCR
- High-flow oxygen
- Consider need for critical care (SpO2 < 94% on 40% oxygen and rising RR = ARDS) and appropriateness (clinical frailty scale, CFS)
- Once confirmed - notify PHE
- Severe COVID-19 (RR > 30, requiring oxygen/ ventilation) = dexamethasone 6mg daily PO/IV for 10/7
- Select patients with severe COVID-19 = remdesevir 100mg IV daily for 5-10 days
b) - Oxygen (initially aim for >94%, once stable aim for > 90%)
- RECOVERY-RS - CPAP/HFNO
- ?trial of NIV in T2RF
- Conservative fluid management - encourage mod oral intake, run “on the dry side” (no more than 2L/day); if shocked, avoid aggressive fluid resus to avoid ARDS
- Paracetamol for fever/ pain
- Antibiotics - empirical for chest sepsis (Sepsis 6), and follow Start Smart/Then Focus (review at 48 - 72h)
- Neuraminidase inhibitor (eg. Tamiflu) if flu cannot be ruled out
- Thromboprophylaxis - raised VTE risk in COVID
- Monitoring - vital signs, ACVPU, fluid status, pain, etc.
- Treatment of underlying conditions (eg. asthma, diabetes and heart failure)
- Consider ceilings of care - decide if candidates for critical care (if > 65 without long-term disability, use CFS, with threshold of < 5 and other factors)
- End of life care
c) - Intubation (PPE to protect from aerosol generation)
- Neuromuscular paralysis
- Mechanical ventilation
- Haemofiltration
- Vasopressor therapy
- ECMO
d) Do not administer unless part of clinical trial:
- RECOVERY - azithromycin, convalescent plasma, tocilizumab, monoclonal antibody
- Lopinavir/ ritonavir (antiretroviral)
- Chloroquine/ hydroxychloroquine
- IVIG (children)
Clinical frailty scale (CFS).
a) Score 1 = ? Score 5 = ? Score 9 = ?
b) Score of 4 or less in Covid patient indicates…?
c) Score of 5+ in Covid patient indicates…?
d) Should only be used in patients who are…
a) 1 = Very fit for age
5 = mildly frail (may need some support with high order ADLs, eg. finances, transport, medication)
9 = Terminally ill
b) Likely to benefit from critical care support
c) Unlikely to benefit from critical care support
d) - 65 years old and over
- Without long-term physical or learning disability (eg. cerebral palsy, intellectual impairment, autism) - do an individualised assessment of frailty
Principles of ventilating Covid-19 patients.
a) In intubated ICU patient
b) In non-intubated patient
a) ARDS management.
- Low tidal volumes
- Consider neuromuscular paralysis
- Consider prone ventilation
b) - High-flow oxygen: NRB or HFNC
- CPAP/BiPAP
ARDS.
a) Define
b) Severe according to PaO2: FiO2 ratio
c) Pathogenesis
d) Causes
a) An acute inflammatory syndrome manifesting as:
- diffuse pulmonary oedema, and
- respiratory failure
…that cannot be explained by, but may co-exist with, left-sided heart failure
b) PaO2: FiO2 ratio < 20 %
- eg. on 50% oxygen but PaO2 < 10 mmHg
c) Inflammation in the alveolar-capillary membrane, leading to distal consolidation and collapse and reducing the surface area in the lungs for gas exchange
d) - Pneumonia
- Aspiration
- Sepsis
- Inhalation injury
- Trauma/ contusion
- Pancreatitis
- Burns
- Drug overdose
Complications of severe infection
a) Main one (cause of death)
b) Others
c) Long-term
a) ARDS, causing respiratory failure
b) - Sepsis and shock (+ DIC)
- Secondary infection (super-added infection)
- Heart failure
- AKI
- Acute liver injury
- Acute cardiac injury - myocarditis and arrhythmias
- Cytokine storm syndrome (hyperinflammation): triad of unremitting fever, cytopenias, and hyperferritinaemia
- Paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS)
- Neurological - most commonly stroke
c) - “Long COVID” - 90% of hospitalised patients report at least one symptom persisting 2 months later
- Post-ICU syndrome
Patients at greater risk of severe infection
- Male
- Older age
- Obesity
- Pre-existing lung disease
- CVD - hypertension, CHD, heart failure
- Diabetes
- Immunosuppression
- ?NSAID users?
Public Health England.
a) Definition of ‘possible case’
b) Definition of a ‘contact’
c) Isolation period (as of October 2020)
a) - Influenza-type illness (Fever 37.8+ and 1 or more URTI or LRTI symptom), OR
- Clinical/radiological evidence of pneumonia or ARDS
b) A contact is a person who has experienced any one of the following exposures during the 2 days before and the 14 days after the onset of symptoms of a probable or confirmed case:
• Face-to-face contact with a probable or confirmed case within 3 feet and for more than 15 minutes
• Direct physical contact with probable/confirmed case
• Direct care for a patient with probable/confirmed COVID-19 without using recommended PPE
• Other situations as indicated by local risk assessments.
c) - Suspected/confirmed - isolate for 10 days after symptom onset plus at least 3 days without fever and respiratory symptoms
- Contact positive - isolate for 14 days from last contact
or obtain at least two negative RT-PCR tests on respiratory specimens collected 24 hours apart before ending isolation if a test-based strategy is used.
Aerosol-generating procedures.
- Intubation, extubation and ventilation
- Tracheotomy/ tracheostomy
- BiPAP/CPAP
- High-flow nasal cannula (NFNC)
- Nebulisers
- Chest compressions and BVM ventilation
- Sputum induction
- Bronchoscopy
- Suctioning
- Surgery and post-mortem procedures
- Some ENT and dental procedures
High-flow nasal cannulae.
- Mnemonic: HI FLOW
- Heated + humidified - so does not dry out nasal mucosa, can therefore be delivered at higher flow
- Inspiratory demand met - in tachypnoeic patient, minute ventilation may be 20 L/min or more, so need a flow rate to exceed this in order to oxygenate properly
- Functional residual capacity improved - probably via delivery of some PEEP - avoids atelectasis
- Lighter - nasal cannula easier to tolerate than face mask
- Oxygen dilution less (due to higher flow, negating dilution from mouth-breathing of room air)
- Washout of dead space - flushes out CO2 from pharynx
PPE rules.
a) Fluid-resistant masks and gowns, eye and face protection
b) What should be changed between every patient?
c) When should FFP3 be worn?
a) ‘Single-session’ use: i.e. a period of time spent in the same setting, ending when healthcare worker leaves this setting
b) Disposable gowns and gloves
c) During aerosol-generating procedures
Features of more serious infection.
a) Moderate
b) Severe
c) Oxygen requirement indicating ?deterioration
d) Critical
a) Clinical signs of pneumonia but SpO2 > 90% on room air
b) RR > 30
- Signs of respiratory distress
- SpO2 < 90% on room air
- Lung infiltrates > 50%
c) Oxygen requirement > 4L/min (or FiO2 of 28% to maintain target sats)
b) - Unable to maintain target saturations (92–96% or 88–92% in type 2 respiratory failure risk group)
- Inspired oxygen ≥ 50% to maintain target saturations
- Respiratory Rate > 30 despite oxygen
- Acidosis: pH < 7.2
- Systolic BP < 90 mmHg
- Other organ failure (e.g. liver/kidney/heart/brain)
- Decreased conscious state
Covid and Resuscitation.
a) Resus council guidance on full CPR
b) What may still be performed in the absence of full CPR?
a) Only safe to perform if wearing full PPE (including FFP3 masks), as chest compressions and BVM ventilation are aerosol-generating procedures
- This will rarely be appropriate, but may be performed in suitable individuals if staff already wearing full PPE or if notified of arrest in advance by paramedics
b) - Cardiac monitoring
- If shockable rhythm - defibrillation is permissible without the need for full PPE
- Treatment of reversible causes (eg. hypovolaemia, hypoglycaemia, hypokalaemia)
Interpreting swab results.*
a) Positive result
b) Negative result
c) False positive rates
d) False negative rates
e) Antibody test accuracy
- Note: Results should be interpreted in the context of the pretest probability of disease
a) A positive RT-PCR result confirms SARS-CoV-2 infection
- However, if pre-test probability is low, interpret the result with caution
b) If the result is negative, and there is
still a clinical suspicion of infection (e.g. an epidemiologic link, typical x-ray findings, absence of
another etiology), resample the patient and repeat the test.
- A positive second swab result confirms infection.
- If the second test is negative, consider serologic testing
c) Low - less than 5% of tests (but if low prevalence, there will be a low PPV)
d) As high as 25%
e) A Cochrane review found that antibody tests for IgG/IgM detected:
- 30% of people with COVID-19 when the test was performed 1 week after the onset of symptoms
- Week 2 = 70% detected
- Week 3 = over 90% detected.
Differentiating COVID from:
a) CAP/HAP
b) Influenza
c) Atypical pneumonia
a) Bacterial pneumonia more likely to have:
- Sputum production
- Focal signs o/e or CXR
- Blood/sputum culture positive
COVID more likely to have:
- Contact positivity
- Anosmia/ ageusia
- COVID swab positive
b) Influenza more likely to have:
- Symptom peak within 3-7 days (vs. COVID symptom peak around 14 days)
- Influenza swab positive
- Children more at risk
COVID more likely to have:
- Abnormal XR or CT
- Abnormal biomarkers (e.g. lymphopenia, raised CRP, ferritinaemia, raised ALT, raised troponins, etc.)
c) - Legionella antigen
- Immunosuppressed? - consider PCP pneumonia
- Foreign travel (non-COVID area)
- Aspiration risk
Paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS).
a) Diagnostic criteria
Children and adolescents 0–19 years of age with:
- Fever > 3 days
AND two of the following:
- Rash or bilateral non-purulent conjunctivitis or muco-cutaneous inflammation signs (oral, hands or feet).
- Hypotension or shock.
- Features of myocardial dysfunction, pericarditis, valvulitis, or coronary abnormalities (including ECHO findings or elevated Troponin/NT-proBNP),
- Evidence of coagulopathy (by PT, PTT, elevated d-Dimers).
- Acute gastrointestinal problems (diarrhoea, vomiting, or abdominal pain).
AND
Elevated markers of inflammation such as ESR, C-reactive protein, or procalcitonin.
AND
No other obvious microbial cause of inflammation, including bacterial sepsis, staphylococcal or streptococcal shock syndromes.
AND
Evidence of COVID-19 (RT-PCR, antigen test or serology positive), or likely contact with patients with COVID-19
