1. Respiratory Support Strategies

Management of hypoxemic respiratory failure in emerging viral infections follows a stepwise escalation from low‐flow oxygen to invasive ventilation with lung‐protective settings. The primary goal is to maintain adequate oxygenation while minimizing iatrogenic lung injury.

A. Oxygen Therapy and Escalation Criteria

• Conventional modalities: Nasal cannula (up to 6 L/min), simple face mask (up to 10 L/min), and Venturi mask (FiO₂ up to 50%).
• SpO₂ targets: 92–96% for most patients; a lower target of 88–92% is appropriate for those with chronic obstructive pulmonary disease (COPD) or others at risk for hypercapnia.
• Escalation triggers (assess within 1 hour): Respiratory rate > 30 breaths/min, significant accessory muscle use, PaO₂/FiO₂ ratio < 200, or rising PaCO₂ with developing acidosis.

B. High‐Flow Nasal Cannula (HFNC)

HFNC is a key therapy for moderate-to-severe hypoxemia, delivering heated, humidified oxygen at high flow rates to reduce work of breathing and improve oxygenation.

• Indications: Moderate-to-severe hypoxemia (PaO₂/FiO₂ 150–300), tachypnea (> 25 breaths/min), or need for FiO₂ > 40%.
• Initial settings: Start with a flow rate of 40 L/min and FiO₂ of 0.6. Titrate both parameters to achieve SpO₂ goals and patient comfort, with flow rates typically ranging from 20–70 L/min.
• Failure criteria: Persistent tachypnea, declining ROX index, worsening gas exchange (rising PaCO₂), or new hemodynamic instability.

C. Noninvasive Ventilation (NIV)

NIV (e.g., BiPAP, CPAP) is used selectively in viral pandemics due to the high risk of aerosol generation and potential for delaying necessary intubation.

• Primary Indications: Hypercapnic respiratory failure (e.g., COPD exacerbation) and cardiogenic pulmonary edema. Its role in pure hypoxemic respiratory failure is limited.
• Contraindications: Hemodynamic instability, altered mental status, high aspiration risk, or inability to protect the airway.
• Failure criteria: Worsening acidosis (pH < 7.30), rising PaCO₂, failure to improve tidal volume, or increased work of breathing.

D. Lung-Protective Mechanical Ventilation for ARDS

Once a patient is intubated, adherence to a lung-protective ventilation strategy is critical to mitigate ventilator-induced lung injury (VILI).

1. Tidal Volume: Target 6 mL/kg of predicted body weight.
2. Plateau Pressure: Maintain a plateau pressure of ≤ 30 cm H₂O.
3. PEEP: Use moderate-to-high levels of PEEP for patients with a PaO₂/FiO₂ < 150 to improve oxygenation and recruit collapsed alveoli.
4. Prone Positioning: Implement for 12–16 hours per day in patients with severe ARDS (PaO₂/FiO₂ < 100).
5. Neuromuscular Blockade: Consider a continuous infusion early in severe ARDS to improve ventilator synchrony and prevent dyssynchrony-related lung injury.
6. Weaning: Perform daily assessments for readiness to wean, including daily spontaneous breathing trials and minimization of sedation.

E. Aerosol-Generating Procedures (AGPs) and Infection Control

Strict infection control is paramount during AGPs to protect healthcare workers.

• High-Risk Procedures: Intubation, extubation, bronchoscopy, NIV, HFNC, and open suctioning of the airway.
• Personal Protective Equipment (PPE): A fitted N95/FFP2 or higher-level respirator, eye protection (goggles or face shield), fluid-resistant gown, and gloves are mandatory.
• Environment: Perform AGPs in a negative-pressure room whenever possible, with the number of personnel present limited to only those essential for the procedure.

2. ICU Complication Prophylaxis

Critically ill patients with severe viral infections are at high risk for several preventable complications. Prophylactic strategies targeting VTE, stress-related bleeding, and secondary infections are a cornerstone of supportive care.

A. Venous Thromboembolism (VTE) Prophylaxis

Systemic inflammation and endothelial injury from viral infections create a prothrombotic state, necessitating aggressive VTE prophylaxis.

B. Stress-Related Mucosal Bleeding Prophylaxis

• High-Risk Indications: Mechanical ventilation for > 48 hours, or coagulopathy (platelets < 50,000/µL or INR > 1.5).
• Agents: Proton pump inhibitors (PPIs) like pantoprazole 40 mg IV daily are generally preferred over histamine-2 receptor antagonists (H2RAs).
• Deprescribing: Prophylaxis should be reassessed daily and discontinued promptly when high-risk factors are no longer present to reduce risks of C. difficile and pneumonia.

C. Prevention of Secondary Infections

• Antibiotic Stewardship: Reserve empiric antibiotics for patients with a high suspicion of bacterial co-infection. Biomarkers like procalcitonin can help guide de-escalation.
• Infection Control Bundles: Strict adherence to evidence-based bundles is crucial. This includes head-of-bed elevation (30-45 degrees), regular oral care with chlorhexidine, and meticulous central line insertion and maintenance protocols.

3. Management of Iatrogenic Complications

Therapies essential for managing severe viral illness, such as corticosteroids and immunomodulators, can cause significant adverse effects that require proactive monitoring and management.

A. Corticosteroid-Induced Hyperglycemia

• Monitoring: Check blood glucose every 4–6 hours in patients receiving high-dose corticosteroids.
• Management: An intravenous insulin infusion is the preferred method for managing significant hyperglycemia (e.g., BG > 180 mg/dL) in the ICU. As steroids are tapered, patients can be transitioned to a subcutaneous basal-bolus regimen.

B. IL-6 Inhibitor–Associated Complications

Immunomodulators like tocilizumab can increase the risk of opportunistic infections and cause laboratory abnormalities.

• Screening: Before administration, screen for latent tuberculosis and chronic hepatitis B.
• Prophylaxis: Consider antifungal prophylaxis in patients with other risk factors for invasive fungal disease, such as prolonged neutropenia.
• Monitoring: Check a complete blood count (CBC) and liver function tests (LFTs) weekly for 2–4 weeks after a dose to monitor for neutropenia, thrombocytopenia, and transaminitis.

4. Multidisciplinary Goals-of-Care and Ethical Considerations

During a pandemic, structured, empathetic communication and ethical resource allocation are essential components of critical care.

A. Candidacy for Advanced Therapies (e.g., ECMO)

Decisions regarding highly resource-intensive therapies like Extracorporeal Membrane Oxygenation (ECMO) require a multidisciplinary team assessment.

• Inclusion Criteria: Typically reserved for younger patients (< 65 years) with reversible pathology, refractory hypoxemia (PaO₂/FiO₂ < 80) despite optimal ventilation, and an absence of severe comorbidities.
• Team Composition: The decision-making team should include specialists in critical care and ECMO, alongside palliative care and ethics consultants.

B. Shared Decision-Making and Family Engagement

Early and frequent communication with patients and their families is critical to ensure that care aligns with their values and goals.

• Timing: Initiate a formal goals-of-care discussion within 72 hours of ICU admission.
• Process: Utilize decision aids and review any advance directives. Involve palliative care specialists to help facilitate these complex conversations.

C. Crisis Standards and Resource Allocation

In a public health emergency, institutions must have predefined, ethical frameworks for allocating scarce resources.

• Core Principles: The framework must be built on principles of maximizing benefit to the population, equity, and transparency.
• Mechanism: Triage committees, using objective and predefined protocols, should make allocation decisions to ensure fairness and consistency.

5. Monitoring and Quality Metrics

Continuous quality improvement is driven by the regular audit of care processes and patient outcomes.

A. Checklists and Care Bundles

Standardized bundles improve reliability and reduce complications.

• Ventilator-Associated Pneumonia (VAP) Bundle: Includes sedation minimization (“sedation vacations”), daily spontaneous breathing trials, regular oral care, and head-of-bed elevation.
• Central Line-Associated Bloodstream Infection (CLABSI) Bundle: Includes strict hand hygiene, use of maximal sterile barriers during insertion, and daily review of line necessity.

B. Key Performance Indicator (KPI) Tracking

Tracking key metrics allows for identification of trends and areas for improvement.

• Metrics: Incidence of VTE, stress ulcers, VAP, and CLABSI; glycemic control (e.g., time in target range).
• Review: These metrics should be reviewed in monthly multidisciplinary meetings to drive performance improvement cycles.

C. Education and Process Improvement

A culture of safety and learning is vital.

• Simulation Training: Conduct regular simulation-based training for high-risk procedures like AGPs and emergency airway management.
• Feedback Loops: Implement structured debriefs after adverse events and create a system for rapidly updating protocols based on new evidence and local experience.