What is the standard of care for a morbidly obese adult patient with Respiratory Syncytial Virus (RSV) infection requiring Bilevel Positive Airway Pressure (BiPAP) support?

Standard of Care for Adult RSV in Morbidly Obese Patients Requiring BiPAP

For morbidly obese adults with RSV infection requiring BiPAP support, the standard of care is supportive management with non-invasive ventilation (NIV/BiPAP) using high EPAP settings (10-15 cm H₂O) and high IPAP (often >30 cm H₂O), combined with aggressive fluid management, supplemental oxygen targeting SpO₂ 88-92%, and close monitoring for NIV failure requiring intubation. 1, 2, 3

Respiratory Support Strategy

BiPAP Settings for Morbidly Obese Patients

• Start with high EPAP (10-15 cm H₂O) to recruit collapsed alveoli and overcome upper airway obstruction, which is common in obese patients and worsens during sleep 1
• Use high IPAP (often >30 cm H₂O) because the impedance to inflation is very high in morbidly obese patients, and adequate tidal volume may be difficult to achieve with lower pressures 1
• Prolong inspiratory time (Ti) with I:E ratio of 1:1 to increase delivered tidal volume when high EPAP is required 1
• Consider volume-controlled ventilation or volume-assured modes if adequate tidal volume cannot be achieved with pressure-controlled settings 1
• Position the patient upright to reduce abdominal pressure on the diaphragm and improve ventilation 1

Oxygenation Management

• Target SpO₂ 88-92% rather than higher saturations, as achieving adequate oxygenation may be difficult due to dependent lung collapse and potential underlying pulmonary vascular disease 1
• Use oxygen blending capability if high EPAP settings fail to improve the alveolar-arterial gradient 1
• Anticipate precipitous falls in oxygenation when BiPAP is temporarily removed, and minimize interruptions in ventilatory support 1

Supportive Care Measures

Fluid Management

• Implement forced diuresis aggressively as fluid overload is common and frequently underestimated in obese patients with respiratory failure, often exceeding 20 liters 1
• Provide intravenous fluids judiciously to maintain hydration without exacerbating pulmonary edema 2

Airway Clearance

• Assist with secretion clearance as difficulty clearing secretions contributes to poor gas exchange in obese patients 1
• Monitor for upper airway obstruction indicated by intermittent abdominothoracic paradox during NIV-assisted breaths or intermittent mask leak accompanying obstructed inspiration 1

Antipyretics and Symptomatic Treatment

• Administer antipyretics as part of standard supportive care for RSV infection 2

Monitoring for NIV Failure

Critical Warning Signs

• Persistent hypoxemia despite high EPAP (SpO₂ <88% on FiO₂ >0.5 and EPAP 10-15 cm H₂O) 1
• Worsening acidosis (pH <7.3) or rising PaCO₂ (>6.5 kPa/49 mmHg) despite adequate BiPAP settings 1
• Inability to achieve adequate tidal volume even with maximum pressure settings and prolonged inspiratory time 1
• Sudden deterioration which carries significant risk in obese patients who are likely difficult to intubate 1

Intubation Considerations

• Prepare for difficult intubation as morbidly obese patients with severe respiratory failure have significantly increased risk of difficult airway management 1, 3
• Use BiPAP for preoxygenation prior to rapid sequence induction if intubation becomes necessary, as traditional preoxygenation may be inadequate (inspiratory pressure 17 cm H₂O, expiratory pressure 7 cm H₂O with 10 L/min oxygen flow) 4
• Apply lung-protective ventilation if invasive mechanical ventilation is required, using low tidal volumes (4-8 mL/kg predicted body weight, NOT actual body weight) and limiting plateau pressure <30 cm H₂O 1, 3

Placement and Monitoring

• Admit to ICU or high-dependency unit given the significant risk of sudden deterioration and need for close monitoring 1, 3
• Involve senior staff early in decision-making, particularly regarding appropriateness of invasive mechanical ventilation if NIV fails 1
• Monitor arterial blood gases regularly to assess response to therapy and detect early deterioration 3

Important Caveats

• No RSV-specific antiviral therapy is currently available for adults, so treatment remains entirely supportive 2, 5
• Antibiotics are commonly used (administered in 51-61% of hospitalized RSV patients across risk groups) but should be reserved for documented bacterial superinfection rather than routine use 5
• Early application of NIV in morbidly obese patients with hypoventilation has been shown to improve respiratory parameters, decrease need for invasive mechanical ventilation, and improve survival 3
• Median hospital length of stay for RSV in adults is 6 days, with disease severity having the greatest impact on duration 5