Respiratory Failure Management in CVICU

Diagnosis and Assessment

Respiratory failure is defined as inadequate gas exchange characterized by hypoxemia and/or hypercapnia, requiring prompt recognition and intervention to prevent deterioration and death, with Type 1 (Hypoxemic) characterized by PaO2 <60 mmHg with normal or low PaCO2, and Type 2 (Hypercapnic) characterized by PaCO2 >45 mmHg 1
Clinical presentation includes dyspnea, increased work of breathing, and subjective shortness of breath, with signs such as tachypnea, use of accessory muscles of respiration, and paradoxical motion of rib cage and abdomen 2
Altered mental status or drowsiness is a sign of impending respiratory failure, and inability to speak in complete sentences is an indication of severe respiratory distress 3, 4
Vital signs such as tachycardia and hypotension are common, and oxygen saturation <90% on room air is an indicator of hypoxemia 2, 5
Laboratory findings include arterial blood gas showing hypoxemia and/or hypercapnia, with PaO2/FiO2 ratio <300 indicating severity, and elevated lactate levels indicating tissue hypoxia 1, 6, 5

Initial assessment and support include positioning the patient upright, administering oxygen, and monitoring continuously with pulse oximetry and cardiac monitoring 6, 7, 2
Non-invasive support includes high-flow nasal cannula as first-line therapy for mild to moderate respiratory distress, and non-invasive ventilation for appropriate candidates, with consideration of helmet NIV over face-mask when available 6, 2
Invasive mechanical ventilation is indicated for failure of non-invasive support, severe respiratory distress, and impending respiratory failure signs, with ventilation strategies including low tidal volume ventilation and selection of PEEP based on gas exchange and hemodynamics 6, 4, 1
Pharmacological management includes opioids as first-line treatment for dyspnea, benzodiazepines for anxiety, and vasopressors for managing hypotension during intubation, with consideration of ketamine for induction in patients with risk of hemodynamic instability 6, 2
Adjunctive measures include early mobilization to prevent ICU-acquired weakness, chest physiotherapy for secretion clearance, and adequate nutrition to support respiratory muscle function 6

Cardiac-pulmonary interactions are significant, with respiratory interventions impacting cardiac function and vice versa, and hemodynamic instability is common during intubation and ventilation changes 2
Post-cardiac surgery patients are at risk for atelectasis, pleural effusions, and diaphragmatic dysfunction, and ventilator-associated pneumonia is a common complication in patients requiring prolonged mechanical ventilation 2
Diaphragmatic weakness can develop rapidly in mechanically ventilated patients, and weaning and liberation from ventilation should be considered when PaO2/FiO2 >200 mmHg and PEEP <10 cmH2O, with implementation of prophylactic NIV after extubation in high-risk patients 6, 2