Diagnosis and Management of Acute Respiratory Failure ARF 1 ®

ObjectivesObjectives Define and classify acute respiratory failure Define and classify acute respiratory failure Describe pathophysiology of acute respiratory failure Describe pathophysiology of acute respiratory failure Discuss clinical manifestations Discuss clinical manifestations Review oxygen supplementation strategies Review oxygen supplementation strategies Discuss noninvasive positive-pressure ventilation Discuss noninvasive positive-pressure ventilation Define and classify acute respiratory failure Define and classify acute respiratory failure Describe pathophysiology of acute respiratory failure Describe pathophysiology of acute respiratory failure Discuss clinical manifestations Discuss clinical manifestations Review oxygen supplementation strategies Review oxygen supplementation strategies Discuss noninvasive positive-pressure ventilation Discuss noninvasive positive-pressure ventilation ARF 2 ®

Acute Respiratory Failure Hypoxemic Hypoxemic – Room air PaO 2  50 torr (6.7 kPa) Hypercapnic Hypercapnic – PaCO 2  50 torr (6.7 kPa) Acute vs chronic Acute vs chronic Hypoxemic Hypoxemic – Room air PaO 2  50 torr (6.7 kPa) Hypercapnic Hypercapnic – PaCO 2  50 torr (6.7 kPa) Acute vs chronic Acute vs chronic – –

Pathophysiology of Hypoxemia Ventilation/perfusion mismatch Ventilation/perfusion mismatch Shunt effect Shunt effect Decreased diffusion of O 2 Decreased diffusion of O 2 Alveolar hypoventilation Alveolar hypoventilation High altitude High altitude Ventilation/perfusion mismatch Ventilation/perfusion mismatch Shunt effect Shunt effect Decreased diffusion of O 2 Decreased diffusion of O 2 Alveolar hypoventilation Alveolar hypoventilation High altitude High altitude

Pathophysiology of Hypercapnia Decreased tidal volume and/or respiratory rate Decreased tidal volume and/or respiratory rate Inability to sense elevated PaCO 2 Inability to sense elevated PaCO 2 Inability to signal effector mechanisms Inability to signal effector mechanisms Inability to effect a response from respiratory muscles Inability to effect a response from respiratory muscles Decreased tidal volume and/or respiratory rate Decreased tidal volume and/or respiratory rate Inability to sense elevated PaCO 2 Inability to sense elevated PaCO 2 Inability to signal effector mechanisms Inability to signal effector mechanisms Inability to effect a response from respiratory muscles Inability to effect a response from respiratory muscles

Increased Dead Space Hypovolemia Hypovolemia Low cardiac output Low cardiac output Pulmonary embolus Pulmonary embolus High airway pressures High airway pressures Short-term compensation by increasing tidal volume and/or respiratory rate Short-term compensation by increasing tidal volume and/or respiratory rate Hypovolemia Hypovolemia Low cardiac output Low cardiac output Pulmonary embolus Pulmonary embolus High airway pressures High airway pressures Short-term compensation by increasing tidal volume and/or respiratory rate Short-term compensation by increasing tidal volume and/or respiratory rate

Manifestations of Respiratory Distress Altered mental status Altered mental status Increased work of breathing Increased work of breathing – Tachypnea – Accessory muscle use, retractions, paradoxical breathing pattern Catecholamine release Catecholamine release – Tachycardia, diaphoresis, hypertension Abnormal arterial blood gas values Abnormal arterial blood gas values Altered mental status Altered mental status Increased work of breathing Increased work of breathing – Tachypnea – Accessory muscle use, retractions, paradoxical breathing pattern Catecholamine release Catecholamine release – Tachycardia, diaphoresis, hypertension Abnormal arterial blood gas values Abnormal arterial blood gas values ARF 7 ®

Acute Respiratory Failure Management Oxygen supplementation Oxygen supplementation – Increase F IO 2 – Match flow between delivery device and inspiratory demand – High- vs. low-oxygen systems – High- vs. low-flow systems Oxygen supplementation Oxygen supplementation – Increase F IO 2 – Match flow between delivery device and inspiratory demand – High- vs. low-oxygen systems – High- vs. low-flow systems ARF 8 ®

Nasal Cannula 100% oxygen delivered 100% oxygen delivered Low flow Low flow – <0.5–5.0 L/min Low oxygen Low oxygen – F IO 2 <0.4–0.5

Air-Entrainment Face Mask 100% O 2 + entrainment device 100% O 2 + entrainment device High flow High flow Variable oxygen Variable oxygen – F IO – % O 2 + entrainment device 100% O 2 + entrainment device High flow High flow Variable oxygen Variable oxygen – F IO –0.5

Aerosol Face Mask 100% O 2 + large-bore tubing 100% O 2 + large-bore tubing Nebulizer/O 2 blender Nebulizer/O 2 blender Flow matching Flow matching – If mist disappears in inspiration, air is entrained Moderate-flow, variable F IO 2 device Moderate-flow, variable F IO 2 device 100% O 2 + large-bore tubing 100% O 2 + large-bore tubing Nebulizer/O 2 blender Nebulizer/O 2 blender Flow matching Flow matching – If mist disappears in inspiration, air is entrained Moderate-flow, variable F IO 2 device Moderate-flow, variable F IO 2 device

Reservoir Face Mask Reservoir bag filled with 100% O 2 Reservoir bag filled with 100% O 2 High oxygen High oxygen High flow High flow Reservoir bag filled with 100% O 2 Reservoir bag filled with 100% O 2 High oxygen High oxygen High flow High flow

Resuscitation Bag-Mask- Valve Device 100% O 2 100% O 2 High flow (> 15 L/min) High flow (> 15 L/min) Emergency equipment Emergency equipment Little to no air entrainment with firm fit Little to no air entrainment with firm fit 100% O 2 100% O 2 High flow (> 15 L/min) High flow (> 15 L/min) Emergency equipment Emergency equipment Little to no air entrainment with firm fit Little to no air entrainment with firm fit

Noninvasive Positive- Pressure Ventilation (NPPV) Ventilatory assistance with controlled F IO 2 Ventilatory assistance with controlled F IO 2 Unilevel or bilevel pressure support Unilevel or bilevel pressure support Nasal or face mask Nasal or face mask Volume or pressure-cycled ventilator Volume or pressure-cycled ventilator Most effective with alert, oriented and cooperative patient Most effective with alert, oriented and cooperative patient Successful in hypoxemic and hypercapnic failure Successful in hypoxemic and hypercapnic failure Ventilatory assistance with controlled F IO 2 Ventilatory assistance with controlled F IO 2 Unilevel or bilevel pressure support Unilevel or bilevel pressure support Nasal or face mask Nasal or face mask Volume or pressure-cycled ventilator Volume or pressure-cycled ventilator Most effective with alert, oriented and cooperative patient Most effective with alert, oriented and cooperative patient Successful in hypoxemic and hypercapnic failure Successful in hypoxemic and hypercapnic failure ARF 14 ®

Relative Contraindications for NPPV Decreased level of consciousness Decreased level of consciousness Poor airway protective reflexes Poor airway protective reflexes Copious secretions Copious secretions Cardiovascular instability Cardiovascular instability Progressive pulmonary decompensation Progressive pulmonary decompensation Upper gastrointestinal hemorrhage Upper gastrointestinal hemorrhage Decreased level of consciousness Decreased level of consciousness Poor airway protective reflexes Poor airway protective reflexes Copious secretions Copious secretions Cardiovascular instability Cardiovascular instability Progressive pulmonary decompensation Progressive pulmonary decompensation Upper gastrointestinal hemorrhage Upper gastrointestinal hemorrhage ARF 15 ®

Initiation of NPPV Set F IO 2 at 1.00 Set F IO 2 at 1.00 Hypoxemic failure Hypoxemic failure – Inspiratory pressure (IPAP) 10 cm H 2 O – Expiratory pressure (EPAP) 5 cm H 2 O – Titrate EPAP in 2 cm H 2 O increments Ventilatory failure Ventilatory failure – IPAP 10 and EPAP 2 cm H 2 O – Titrate IPAP in 2 cm H 2 O increments

Initiation of NPPV Make changes every minutes Make changes every minutes Monitor vital signs, appearance, pulse oximetry and blood gases Monitor vital signs, appearance, pulse oximetry and blood gases Head of bed at 45  angle Head of bed at 45  angle Consider gastric decompression Consider gastric decompression Intubation if patient deteriorates Intubation if patient deteriorates

Pharmacologic Adjuncts Pharmacologic Adjuncts Bronchodilators Bronchodilators –  2 -agonists – Anticholinergics (ipratropium) Corticosteroids Corticosteroids Theophylline Theophylline Antibiotics Antibiotics Bronchodilators Bronchodilators –  2 -agonists – Anticholinergics (ipratropium) Corticosteroids Corticosteroids Theophylline Theophylline Antibiotics Antibiotics

Key Points