01Approach to the Critical Patient/attcp54

Immediate priorities

›Airway and oxygenation threats

›Hypoxemia recognition

›SpO2 < 90% on supplemental oxygen

›Rising oxygen requirement despite current delivery

›Ventilation failure

›RR >= 30 per minute as critical threshold

›Accessory muscle use and respiratory fatigue

›If SpO2 < 90% unresponsive to oxygen, prepare for mechanical ventilation

›Low tidal volume ARDS strategy

›Airborne precautions during intubation mandatory

›Infection control activation

›Immediate airborne isolation

›Negative-pressure single room

›N95 or powered air-purifying respirator for all contacts

›Contact precautions

›Gown and gloves for all room entries

›Eye protection during aerosol-generating procedures

›Nosocomial super-spreading risk

›Alert infection control team immediately

›Limit number of personnel entering room

Monitoring and targets

›Continuous monitoring bundle

›Continuous pulse oximetry

›SpO2 target >= 92%

›Falling trend requires immediate escalation

›Cardiac monitor

›Tachyarrhythmia from hypoxemia

02History/hx52

Presentation pattern

›Core syndrome

›Fever

›Earliest and most universal symptom in 97 to 100% of cases

›High fever > 38 degrees C with rigors and chills

›Cough

›Typically dry and nonproductive

›Onset mean 4.5 days after fever onset

›Cough preceding fever argues against SARS

›Dyspnea

›Develops in 42 to 80% of patients

›Often emerges during the second week of illness

›Constitutional symptoms

›Myalgia

›Present in 49 to 70% of patients

›Early prodromal symptom

›Malaise

›Present in approximately 70% of patients

›Headache common in early phase

›Diarrhea

›Present in up to 50 to 66% of cases

›Typically appears around day 6 after fever onset

Exposure and epidemiology history

›Epidemiologic context

›Close contact history

›Contact with confirmed or suspected SARS patient within 10 days

›Healthcare worker caring for SARS patients

›Travel history

03Physical Exam/exam51

Vital signs

›Critical vital sign patterns

›Temperature

›High fever > 38 degrees C at presentation

›Absent or low fever may occur despite significant disease

›Respiratory rate

›>= 30 per minute indicates critical disease

›Rising trend as marker of deterioration

›Oxygen saturation

›Room air value essential

›SpO2 < 90% triggers escalation

›Tachycardia

›From fever and hypoxemia

›Also evaluate for myocardial involvement

Respiratory examination

›Lung exam findings

›Inspiratory crackles

›Consolidation and alveolar filling

›Peripheral and dependent distribution

›Percussion dullness

›Consolidation correlation

›Effusion uncommon and argues against SARS

›Tachypnea

›Work of breathing assessment

›Accessory muscle use severity marker

›Important negative findings

›Absence of pleural effusion signs

›Pleural effusion presence argues against SARS

04Differential Diagnosis/ddx36

Life-threatening mimics

›Respiratory pathogens

›MERS-CoV

›ICD-10 U07.2 consideration

›Different epidemiologic exposure (Middle East, camel contact)

›Avian influenza H5N1

›ICD-10 J09.X1

›Poultry exposure history

›Severe influenza

›ICD-10 J09 to J11

›Rhinorrhea, sore throat, sputum more common than SARS

›Bacterial pneumonia

›Community-acquired pneumonia

›ICD-10 J18.9

›Productive cough, responds to antibiotics

›Atypical pneumonia

›Legionella, Mycoplasma, Chlamydia

›May partially overlap clinically

Distinguishing features

›SARS-specific differentiating clues

›Lymphopenia hallmark

›Present in 54 to 95% of SARS patients

›Bacterial pneumonia typically has leukocytosis with neutrophilia

›Radiographic pattern

›Peripheral ground-glass opacities without pleural effusion or cavitation

›No hilar lymphadenopathy

›Epidemiologic link

›Exposure history essential for diagnosis

05Laboratory Tests/lt60

Hallmark laboratory findings

›Lymphopenia

›Present in 54 to 95% of patients

›Hallmark finding for SARS

›Distinguishes from bacterial pneumonia

›Serial monitoring for progression

›Worsening lymphopenia correlates with severity

›Thrombocytopenia

›Present in 28 to 40% of patients

›Severity marker

›Part of clinical prediction scoring

›Platelet count monitoring

›Trend over illness course

›LDH elevation

›Present in 58 to 88% of patients

›Independent predictor of poor outcome

›Serial monitoring guides prognosis

›Elevation level correlates with lung injury severity

Metabolic and organ function

›Liver function tests

›Aminotransferase elevation

›Mildly elevated AST/ALT in majority of patients

›Monitor for drug-induced hepatotoxicity if ribavirin used

›Bilirubin

›Usually normal

›Significant elevation suggests alternative or complication

›Creatine kinase

›Elevated in 18 to 56% of patients

06Diagnostic Tests/dt77

Scoring Systems

›Clinical prediction tools

›Hong Kong ED-based clinical score

›Inputs: contact history, fever, myalgia, malaise, lymphopenia, thrombocytopenia, CXR findings

›AUC of 0.85 for SARS diagnosis

›Six-item clinical symptom score

›Inputs: cough timing relative to fever, myalgia, diarrhea, absence of rhinorrhea and sore throat, lymphopenia, thrombocytopenia

›Achieved 100% sensitivity and 86% specificity in validation cohort

›Severity stratification

›Predictors of poor outcome

›Age >= 60 years

›Elevated LDH at admission

›High neutrophil count at admission

›Comorbidities including diabetes and cardiac disease

›ICU admission rate

›20 to 38% of hospitalized patients

›59 to 100% of ICU patients required mechanical ventilation

MRI

›MRI role in SARS-CoV-1

›Limited acute pulmonary utility

›Motion artifact and availability constraints

›CT remains preferred modality

›Potential complication assessment

›Avascular necrosis of femoral heads

›Corticosteroid complication in survivors

›Neurological complications

›Encephalopathy evaluation if clinically indicated

›Limited data in SARS-CoV-1 cohorts

07Disposition/dispo40

Admission criteria

›All suspected and probable SARS cases require hospital admission

›Airborne isolation mandatory

›Negative-pressure single room required

›Contact and airborne precautions for all staff

›Epidemiologic rationale

›No confirmed discharge criteria can exclude transmission risk

›Outbreak control depends on early isolation

ICU admission triggers

›Respiratory failure criteria

›SpO2 < 90% on supplemental oxygen

›Progressive oxygen requirement

›Failure to maintain saturation targets

›RR >= 30 per minute with signs of fatigue

›Impending intubation consideration

›HFNC or ventilatory support planning

›Radiographic progression to bilateral diffuse disease

›ARDS criteria fulfilment

›Intensive monitoring requirement

›Hemodynamic compromise

›MAP < 65 mmHg

›Vasopressor initiation

›Invasive monitoring consideration

›Refractory hypoxemia

›Prone positioning consideration

›Neuromuscular blockade if ventilated

Discharge criteria

›Safe discharge requirements

08Treatment/t94

Supportive care

›Oxygen therapy

›Nasal cannula

›Initial low-flow oxygen

›Titrate to SpO2 >= 92%

›HFNC for moderate to severe hypoxemia

›Flow rates up to 60 L per minute

›FiO2 titrated to SpO2 target

›Airborne precaution compliance mandatory

›NIPPV use cautious

›Aerosol generation risk

›Strict airborne precautions if used

›Preferred only in controlled setting with adequate PPE

›Fluid and electrolyte management

›IV fluids for dehydration from fever and diarrhea

›Reassess fluid responsiveness frequently

›Avoid fluid overload in hypoxemic patients

›Calcium supplementation

›Hypocalcemia present in approximately 60%

›Monitor and correct electrolyte abnormalities

›Antipyretics

›Acetaminophen for fever control

›500 to 1000 mg PO or IV every 6 hours

›Maximum 4 g per day; reduce if hepatic impairment

Empiric antibiotics

›Broad-spectrum coverage to exclude bacterial pneumonia

›Beta-lactam plus macrolide

›Ceftriaxone 2 g IV daily

›Azithromycin 500 mg IV or PO daily

›Alternative fluoroquinolone monotherapy

›Levofloxacin 750 mg IV or PO daily

›QT prolongation risk monitoring required

›De-escalate or discontinue when bacterial etiology excluded

›Negative cultures and no bacterial indicators

›SARS-CoV-1 confirmed

Antiviral considerations

›Lopinavir/ritonavir

›Most favorable observational data

›Reduced intubation rates in retrospective cohort

›Used when initiated early in illness course

›Dosing

›400 mg lopinavir / 100 mg ritonavir PO twice daily

›No definitive RCT evidence; observational benefit only

›Monitoring

›QT prolongation risk

›Drug interactions review

›Ribavirin

›No longer recommended

›No in vitro activity at achievable concentrations

›Hemolytic anemia in 76% of treated patients

›Hemoglobin drop >= 2 g/dL in 49%

›Historical context only

›Widely used in 2003 outbreak without benefit

›Interferon therapy

›Interferon-beta and interferon-alfa demonstrated in vitro activity

›Limited clinical data available

›Specialist guidance recommended if considered

›Investigational status

›Not routine standard of care

Corticosteroids

›Pulse methylprednisolone for critical SARS

›Indication

›Progressive respiratory failure with deteriorating oxygenation

›Increasing oxygen requirements during second week of illness

›Dosing

›250 to 500 mg IV per day for 3 to 6 days

›Evidence remains uncontrolled observational only

›Risks

›Disseminated fungal infection with prolonged use without effective antimicrobial coverage

›Avascular necrosis of femoral heads (long-term complication in survivors)

›Secondary bacterial infection risk

›Steroid precautions

›Avoid prolonged high-dose without infectious disease guidance

›Fungal prophylaxis consideration in high-risk patients

›Monitor blood glucose closely

Mechanical ventilation

›Low tidal volume ventilation per ARDS protocol

›Tidal volume

›6 mL per kg ideal body weight

›Maximum plateau pressure <= 30 cmH2O

›PEEP titration

›High PEEP strategy for moderate to severe ARDS

›FiO2 and PEEP table guidance

›Prone positioning

›For moderate to severe ARDS (PaO2/FiO2 < 150 mmHg)

›16 hours per day prone protocol

›Ventilator infection control

›Closed suction systems mandatory

›Minimize circuit disconnection

›N95 or PAPR for all circuit manipulations

Rescue therapies

›Convalescent plasma

›Used as rescue therapy in 2003 outbreak

›Anecdotal benefit reported

›No RCT evidence available

›Infectious disease specialist guidance required

›IVIG

›Used for refractory cases anecdotally

›No controlled evidence

›Consider in specialist context only

09Special Populations/sp76

Pregnancy

›Pregnancy-specific risks

›Higher severity reported in pregnant women

›Increased rates of preterm delivery

›Maternal mortality risk elevated

›Physiologic changes affecting presentation

›Increased basal oxygen consumption

›Reduced functional residual capacity

›Oxygen targets in pregnancy

›Maintain SpO2 >= 95% when feasible

›Fetal oxygenation depends on maternal SpO2

›Fetal monitoring when viable gestation

›Medication considerations

›Lopinavir/ritonavir use

›Limited pregnancy safety data

›Consult maternal-fetal medicine

›Ribavirin contraindicated in pregnancy

›Teratogenic risk

›Avoid in all trimesters

›Corticosteroids

›Betamethasone for fetal lung maturity if preterm delivery anticipated

›Pulse methylprednisolone dosing risk-benefit discussion with obstetrics

›Imaging

›CXR with abdominal shielding when indicated

›Benefit outweighs radiation risk in critically ill

›CT chest when diagnosis unclear

›Use low-dose protocol when feasible

›Fetal dose remains within acceptable limits for thoracic CT

Geriatric

›Age-related severity

›Significantly higher mortality in patients >= 60 years

›Attack rates up to 27.6% in quarantined contacts aged 60 to 90

›Age is independent predictor of death in multivariate analyses

›Atypical presentation risk

›Delirium as primary presenting symptom

›Afebrile despite significant infection

›Comorbidity impact

›Cardiovascular disease and diabetes amplify mortality risk

›Baseline functional assessment

›Goals of care discussion early

›Polypharmacy and drug interactions

›Lopinavir/ritonavir interactions

›QT prolongation risk increased

›Infection control

›Healthcare facility transmission highest risk for older adults

›Early isolation critical

›Visitor restriction during outbreak conditions

›Supportive care modifications

›Renal dosing adjustment for medications

›eGFR-based antibiotic dosing

›Nutritional support early

›Malnutrition risk with prolonged illness

›Enteral nutrition preference in mechanically ventilated

Pediatrics

›Milder disease pattern in children

›Children have consistently milder clinical course than adults

›No pediatric deaths reported in 2003 SARS outbreak

›Rarely required ICU admission

›Infants and young children

›More likely to have fever and upper respiratory symptoms

›Less likely to develop respiratory failure

›Diagnostic differences

›Lower RT-PCR sensitivity reported

›Multiple specimen types recommended

›Repeat testing if high clinical suspicion

›Treatment in pediatrics

›Supportive care as primary approach

›Supplemental oxygen titrated to age-appropriate SpO2 targets

›IV fluids weight-based

›Corticosteroids

›Methylprednisolone 1 to 2 mg per kg per day for severe disease

›Risk-benefit assessment with pediatric specialist

›Antiviral agents

›Lopinavir/ritonavir solution: 12 mg per kg lopinavir twice daily (< 15 kg)

›Weight-band dosing per pediatric formulary

›Infection control

›Same airborne and contact precautions as adults

›Pediatric-sized N95 when feasible

›Family visitation restrictions per outbreak protocols

10Background/b76

Epidemiology

›2003 global outbreak statistics

›Total cases worldwide

›8098 probable cases across 27 countries

›774 deaths (approximately 10% case fatality rate)

›Geographic distribution

›China, Hong Kong, Singapore, Canada, Vietnam most affected

›Contained by July 2003

›No confirmed human cases since 2004

›Laboratory accidental exposures occurred in 2003 to 2004

›Healthcare worker burden

›Comprised approximately 28% of all infections

›77 to 80% of cases in 2003 were nosocomial

›17% were household contacts

›Super-spreading events documented

›Single unrecognized cases infected dozens of healthcare workers

›ICU and emergency department highest risk settings

›Age distribution and mortality

›Overall mortality approximately 6 to 10%

›Mortality > 50% in patients >= 65 years

›Very low mortality in children

›ICU admission rates 20 to 38%

›59 to 100% of ICU patients required mechanical ventilation

Pathophysiology

›Viral characteristics

›SARS-CoV-1 betacoronavirus

›ACE2 receptor binding for cell entry

›Spike protein tropism for lower respiratory tract

›Viral load kinetics

›Peak viral load approximately day 10 of illness

›Clinical deterioration in week 2 despite falling viral load

›Biphasic disease mechanism

›Phase 1: viral replication phase (days 1 to 10)

›Fever, myalgia, malaise dominant

›Viral load driving initial symptoms

›Phase 2: immunopathologic phase (days 10 to 21)

›Respiratory failure despite decreasing viral load

›T-cell depletion and cytokine dysregulation

›Lymphopenia most pronounced in severe cases

›Organ injury mechanisms

›Lung

›Diffuse alveolar damage

›ARDS pattern injury

›Organizing pneumonia pattern may follow

›Systemic effects

›Hepatocyte injury reflected in elevated AST/ALT

›Myositis from CK elevation

›Gastrointestinal epithelial ACE2 expression explains diarrhea

›Transmission characteristics

›Droplet and contact primary routes

›Airborne transmission during aerosol-generating procedures

›Fecal-oral route documented

›Basic reproduction number R0 approximately 2 to 4

›Containable with strict infection control

›Super-spreading events drove most transmission

Therapeutic Considerations

›No proven specific antiviral therapy exists

›All 2003 outbreak treatments lacked RCT-level evidence

›Lopinavir/ritonavir has the best observational data

›Ribavirin abandoned due to toxicity and inefficacy

›Future outbreak preparedness includes investigational agents

›Remdesivir has theoretical mechanistic relevance (SARS-CoV-2 cross-reactivity data)

›No approved SARS-CoV-1 specific antivirals

›Immunomodulatory strategy

›Timing critical for corticosteroid use

›Early use may prolong viral shedding

›Reserved for phase 2 immunopathologic injury

›Convalescent plasma rationale

›Passive immunity transfer from recovered patients

›Neutralizing antibody titers guide selection

›Ventilatory strategy

›ARDS lung protective ventilation standard

›Validated across ARDS etiologies including viral

›Prone positioning early in severe ARDS

›PaO2/FiO2 < 150 mmHg threshold for initiation

›No approved vaccine for SARS-CoV-1

›Multiple candidate vaccines developed after 2003 but not licensed

›Outbreak containment eliminated urgency

›Lessons applied to SARS-CoV-2 vaccine development

11Patient Discharge Instructions/pdi46

copy discharge instructions

›SARS-CoV-1 recovery instructions

›Continue all prescribed medications as directed

›Complete full course of antibiotics if prescribed

›Do not stop medications without provider guidance

›Isolation requirements after discharge

›Follow public health authority instructions for home isolation

›Avoid contact with others until cleared by public health

›Rest and activity

›Gradual return to activity as tolerated

›Fatigue and weakness may persist for weeks

›Monitoring at home

›Temperature measurement twice daily

›Record and report fever > 38 degrees C to public health

›Oxygen saturation if home oximeter available

›Report SpO2 < 92% immediately

›Symptom diary

›Track cough, breathlessness, fever trend

›Warning signs to return to emergency department immediately

›Difficulty breathing at rest

›Unable to complete a sentence

›Lips or fingernails turning blue

›SpO2 < 92% on home oximeter

›Do not wait for scheduled appointment

›Confusion or new severe drowsiness

›May indicate hypoxemia or deterioration

›Persistent high fever despite acetaminophen

›Temperature > 39 degrees C unresponsive to antipyretics

12References/r28

Guidelines and key sources

›Foundational guidelines

›WHO guidance on SARS-CoV-1 infection control and clinical management (2003)

›Infection prevention and control recommendations

›Clinical case definitions for probable and suspected SARS

›CDC SARS clinical guidance and interim infection control precautions

›N95 and PPE hierarchy recommendations

›Discharge criteria guidance

›Key clinical studies

›Peiris JSM et al. SARS coronavirus clinical features, Hong Kong 2003 (Lancet)

›Lymphopenia, LDH, thrombocytopenia as severity markers

›Biphasic illness characterization

›Booth CM et al. Clinical features and short-term outcomes of 144 patients with SARS, Toronto (JAMA 2003)

›ICU admission rates and mechanical ventilation requirements

›Tsui PT et al. Severe acute respiratory syndrome: clinical outcome and prognostic correlates (Emerg Infect Dis 2003)

›Independent predictors of mortality

›Leong HN et al. SARS in Singapore: clinical features of index patient and initial contacts (Emerg Infect Dis 2003)

›Diagnostic scoring references

›Sung JJ et al. Clinical prediction score for SARS diagnosis (AUC 0.85)

›Emergency department triage tool

›Rainer TH et al. Six-item clinical score achieving 100% sensitivity and 86% specificity

›Radiologic references

›Wong KT et al. Thin-section CT of severe acute respiratory syndrome (Radiology 2003)

›Peripheral ground-glass opacities, posterior lower lobe predominance

›Temporal progression characterization

›Treatment references

›Chu CM et al. Role of lopinavir/ritonavir in the treatment of SARS (Thorax 2004)

›Observational reduction in intubation rates

Evidence & Review

Evidence & Review