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
