美国重症医学（FCCM）基础教程急性呼吸衰竭诊断和管理.pptVIP

Diagnosis and Management of Acute Respiratory Failure Objectives Define and classify acute respiratory failure Describe pathophysiology of acute respiratory failure Discuss clinical manifestations Review oxygen supplementation strategies Discuss noninvasive positive-pressure ventilation Acute Respiratory Failure Hypoxemic Room air PaO2 ? 50 torr (6.7 kPa) Hypercapnic PaCO2 ? 50 torr (6.7 kPa) Acute vs chronic Pathophysiology of Hypoxemia Ventilation/perfusion mismatch Shunt effect Decreased diffusion of O2 Alveolar hypoventilation High altitude Pathophysiology of Hypercapnia Decreased tidal volume and/or respiratory rate Inability to sense elevated PaCO2 Inability to signal effector mechanisms Inability to effect a response from respiratory muscles Increased Dead Space Hypovolemia Low cardiac output Pulmonary embolus High airway pressures Short-term compensation by increasing tidal volume and/or respiratory rate Manifestations of Respiratory Distress Altered mental status Increased work of breathing Tachypnea Accessory muscle use, retractions, paradoxical breathing pattern Catecholamine release Tachycardia, diaphoresis, hypertension Abnormal arterial blood gas values Acute Respiratory Failure Management Oxygen supplementation Increase FIO2 Match flow between delivery device and inspiratory demand High- vs. low-oxygen systems High- vs. low-flow systems Nasal Cannula 100% oxygen delivered Low flow 0.5–5.0 L/min Low oxygen FIO2 0.4–0.5 Air-Entrainment Face Mask 100% O2 + entrainment device High flow Variable oxygen FIO2 0.24–0.5 Aerosol Face Mask 100% O2 + large-bore tubing Nebulizer/O2 blender Flow matching If mist disappears in inspiration, air is entrained Moderate-flow, variable FIO2 device Reservoir Face Mask Reservoir bag filled with 100% O2 High oxygen High flow Resuscitation Bag-Mask-Valve Device 100% O2 High flow ( 15 L/min) Emergency equipment Little to no air entrainment with firm fit Noninvasive Positive-Pressur