Acute Resp Failure

Acute Respiratory Failure: 

Acute Respiratory Failure Cindy Kin Trauma Conference 6 August 2007 Stanford Surgery

Acute Respiratory Failure: 

Acute Respiratory Failure Failure in one or both gas exchange functions: oxygenation and carbon dioxide elimination In practice: PaO2<60mmHg or PaCO2>46mmHg Derangements in ABGs and acid-base status

Acute Respiratory Failure: 

Acute Respiratory Failure Hypercapnic v Hypoxemic respiratory failure ARDS and ALI

Hypercapnic Respiratory Failure: 

Hypercapnic Respiratory Failure ( PAO2 - PaO2) Alveolar Hypoventilation V/Q abnormality  PI max increased normal Nl VCO2 PaCO2 >46mmHg Not compensation for metabolic alkalosis Central Hypoventilation Neuromuscular Problem  VCO2 V/Q Abnormality Hypermetabolism Overfeeding

The Case of Patient RV: 

The Case of Patient RV 71M s/p L AKA revision. PMH: CAD s/p CABG, COPD on home O2 and CPAP, DM, CVA, atrial fibrillation PACU: L pleural effusion, hypotension, altered mental status. Sent to ICU for monitoring. POD#1: RR overnight, intermittently hypoxic. BiPAP 40%: 7.34/65/63/35/+10 Preintubation: 7.28/91/81/43

Hypercapnic Respiratory Failure: 

Hypercapnic Respiratory Failure ( PAO2 - PaO2) Alveolar Hypoventilation V/Q abnormality  PI max increased normal Nl VCO2 PaCO2 >46mmHg Not compensation for metabolic alkalosis Central Hypoventilation Neuromuscular Problem  VCO2 V/Q Abnormality Hypermetabolism Overfeeding

Hypercapnic Respiratory Failure: 

Hypercapnic Respiratory Failure Alveolar Hypoventilation Brainstem respiratory depression Drugs (opiates) Obesity-hypoventilation syndrome  PI max Central Hypoventilation Neuromuscular Disorder nl  PI max Critical illness polyneuropathy Critical illness myopathy Hypophosphatemia Magnesium depletion Myasthenia gravis Guillain-Barre syndrome

Hypercapnic Respiratory Failure: 

Hypercapnic Respiratory Failure ( PAO2 - PaO2) Alveolar Hypoventilation V/Q abnormality  PI max increased normal Nl VCO2 PaCO2 >46mmHg Not compensation for metabolic alkalosis Central Hypoventilation Neuromuscular Disorder  VCO2 V/Q Abnormality Hypermetabolism Overfeeding

Hypercapnic Respiratory Failure: 

Hypercapnic Respiratory Failure V/Q abnormality Increased Aa gradient Nl VCO2  VCO2 V/Q Abnormality Hypermetabolism Overfeeding

Hypercapnic Respiratory Failure: 

Hypercapnic Respiratory Failure V/Q abnormality Increased Aa gradient Nl VCO2  VCO2 V/Q Abnormality Hypermetabolism Overfeeding Increased dead space ventilation advanced emphysema PaCO2 when Vd/Vt >0.5 Late feature of shunt-type edema, infiltrates

Hypercapnic Respiratory Failure: 

Hypercapnic Respiratory Failure V/Q abnormality Increased Aa gradient Nl VCO2  VCO2 V/Q Abnormality Hypermetabolism Overfeeding VCO2 only an issue in pts with ltd ability to eliminate CO2 Overfeeding with carbohydrates generates more CO2

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Is PaCO2 increased? Hypoventilation ( PAO2 - PaO2)? Hypoventilation alone  Respiratory drive Neuromuscular dz Hypovent plus another mechanism Shunt Inspired PO2 High altitude  FIO2  (PAO2 - PaO2) No No Yes Is low PO2 correctable with O2? V/Q mismatch No Yes Yes

The Case of Patient ES: 

The Case of Patient ES 77F s/p MVC. Injuries include multiple L rib fxs, L hemopneumothorax s/p chest tube placement, L iliac wing fx. PMH: atrial arrhythmia, on coumadin. INR>2 HD#1 RR 30s and shallow. Pain a/w breathing deeply. Placed on BiPAP overnight PID#1 BiPAP 80%: 7.45/48/66/32/+10

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Is PaCO2 increased? Hypoventilation ( PAO2 - PaO2)? Hypoventilation alone  Respiratory drive Neuromuscular dz Hypovent plus another mechanism Shunt Inspired PO2 High altitude  FIO2  (PAO2 - PaO2) No No Yes Is low PO2 correctable with O2? V/Q mismatch No Yes Yes

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure V/Q mismatch V/Q mismatch DO2/VO2 Imbalance PvO2>40mmHg PvO2<40mmHg  DO2: anemia, low CO  VO2: hypermetabolism

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure V/Q mismatch SHUNT V/Q = 0 DEAD SPACE V/Q = ∞ Atelectasis Intraalveolar filling Pneumonia Pulmonary edema Pulmonary embolus Pulmonary vascular dz Airway dz (COPD, asthma) Intracardiac shunt Vascular shunt in lungs ARDS Interstitial lung dz Pulmonary contusion

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure V/Q mismatch SHUNT V/Q = 0 DEAD SPACE V/Q = ∞ Atelectasis Intraalveolar filling Pneumonia Pulmonary edema Pulmonary embolus Pulmonary vascular dz Airway dz (COPD, asthma) Intracardiac shunt Vascular shunt in lungs ARDS Interstitial lung dz Pulmonary contusion

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Acute Respiratory Distress Syndrome Severe ALI B/L radiographic infiltrates PaO2/FiO2 <200mmHg (ALI 201-300mmHg) No e/o L Atrial P; PCWP<18

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Acute Respiratory Distress Syndrome Develops ~4-48h Persists days-wks Diagnosis: Distinguish from cardiogenic edema History and risk factors

Slide 21: 

Inflammatory Alveolar Injury

Slide 22: 

Inflammatory Alveolar Injury Pro-inflmm cytokines (TNF, IL1,6,8)

Slide 23: 

Inflammatory Alveolar Injury Pro-inflmm cytokines (TNF, IL1,6,8) Neutrophils - ROIs and proteases damage capillary endothelium and alveolar epithelium

Slide 24: 

Inflammatory Alveolar Injury Fluid in interstitium and alveoli Pro-inflmm cytokines (TNF, IL1,6,8) Neutrophils - ROIs and proteases damage capillary endothelium and alveolar epithelium

Slide 25: 

Inflammatory Alveolar Injury Fluid in interstitium and alveoli Impaired gas exchange  Compliance  PAP Pro-inflmm cytokines (TNF, IL1,6,8) Neutrophils - ROIs and proteases damage capillary endothelium and alveolar epithelium

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Acute Respiratory Distress Syndrome Exudative phase Fibrotic phase Proliferative phase Diffuse alveolar damage

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Acute Respiratory Distress Syndrome Direct Lung Injury Infectious pneumonia Aspiration, chemical pneumonitis Pulmonary contusion, penetrating lung injury Fat emboli Near-drowning Inhalation injury Reperfusion pulmonary edema s/p lung transplant

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Acute Respiratory Distress Syndrome Indirect Lung Injury Sepsis Severe trauma with shock/hypoperfusion Burns Massive blood transfusion Drug overdose: ASA, cocaine, opioi ds, phenothiazines, TCAs. Cardiopulmonary bypass Acute pancreatitis

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Acute Respiratory Distress Syndrome Complications Barotrauma Nosocomial pneumonia Sedation and paralysis  persistent MS depression and neuromuscular weakness

Hypoxemic Respiratory Failure: 

Hypoxemic Respiratory Failure Acute Respiratory Distress Syndrome 861 patients, 10 centers Randomized Tidal Vol 12mL/kg PDW, PlatP<50cmH2O Tidal Vol 6mL/kg PDW, PlatP<30cmH2O NNT 12 31% mortality v 39.8% 65.7% breathing without assistance by day 28 v 55% Significantly more ventilator-free days Significantly more days without failure of nonpulmonary organs/systems