Download - Acute Resp Failure Cyndy Kin
Acute Respiratory FailureAcute Respiratory Failure
Cindy Kin
Trauma Conference6 August 2007
Stanford Surgery
Acute Respiratory FailureAcute 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 FailureAcute Respiratory Failure
• Hypercapnic v Hypoxemic respiratory failure
• ARDS and ALI
Hypercapnic Respiratory FailureHypercapnic Respiratory Failure
(PAO2 - PaO2)
Alveolar Hypoventilation
V/Q abnormality
PI max
increasednormal
Nl VCO2
PaCO2 >46mmHgNot compensation for metabolic alkalosis
CentralHypoventilation
NeuromuscularProblem
VCO2
V/Q Abnormality
HypermetabolismOverfeeding
The Case of Patient RVThe 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/+10Preintubation: 7.28/91/81/43
Hypercapnic Respiratory FailureHypercapnic Respiratory Failure
(PAO2 - PaO2)
Alveolar Hypoventilation
V/Q abnormality
PI max
increasednormal
Nl VCO2
PaCO2 >46mmHgNot compensation for metabolic alkalosis
CentralHypoventilation
NeuromuscularProblem
VCO2
V/Q Abnormality
HypermetabolismOverfeeding
Hypercapnic Respiratory FailureHypercapnic Respiratory Failure
Alveolar Hypoventilation
Brainstem respiratory depression Drugs (opiates) Obesity-hypoventilation syndrome
PI max
CentralHypoventilation
NeuromuscularDisorder
nlPI max
Critical illness polyneuropathyCritical illness myopathy
HypophosphatemiaMagnesium depletion
Myasthenia gravisGuillain-Barre syndrome
Hypercapnic Respiratory FailureHypercapnic Respiratory Failure
(PAO2 - PaO2)
Alveolar Hypoventilation
V/Q abnormality
PI max
increasednormal
Nl VCO2
PaCO2 >46mmHgNot compensation for metabolic alkalosis
CentralHypoventilation
NeuromuscularDisorder
VCO2
V/Q Abnormality
HypermetabolismOverfeeding
Hypercapnic Respiratory FailureHypercapnic Respiratory Failure
V/Q abnormalityIncreased Aa gradient
Nl VCO2
VCO2
V/Q Abnormality
HypermetabolismOverfeeding
Hypercapnic Respiratory FailureHypercapnic Respiratory Failure
V/Q abnormalityIncreased Aa gradient
Nl VCO2
VCO2
V/Q Abnormality
HypermetabolismOverfeeding
• Increased dead space ventilation• advanced emphysema• PaCO2 when Vd/Vt >0.5
• Late feature of shunt-type• edema, infiltrates
Hypercapnic Respiratory FailureHypercapnic Respiratory Failure
V/Q abnormalityIncreased Aa gradient
Nl VCO2
VCO2
V/Q Abnormality
HypermetabolismOverfeeding
• VCO2 only an issue in pts with ltd ability to eliminate CO2
• Overfeeding with carbohydrates generates more CO2
Hypoxemic Respiratory FailureHypoxemic Respiratory Failure
Is PaCO2 increased?
Hypoventilation (PAO2 - PaO2)?
Hypoventilation alone
Respiratory driveNeuromuscular dz
Hypovent plus another
mechanism
Shunt
Inspired PO2
High altitudeFIO2
(PAO2 - PaO2) No
NoYes
Is low PO2 correctable
with O2?
V/Q mismatch
No Yes
Yes
The Case of Patient ESThe 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#1BiPAP 80%: 7.45/48/66/32/+10
Hypoxemic Respiratory FailureHypoxemic Respiratory Failure
Is PaCO2 increased?
Hypoventilation (PAO2 - PaO2)?
Hypoventilation alone
Respiratory driveNeuromuscular dz
Hypovent plus another
mechanism
Shunt
Inspired PO2
High altitudeFIO2
(PAO2 - PaO2) No
NoYes
Is low PO2 correctable
with O2?
V/Q mismatch
No Yes
Yes
Hypoxemic Respiratory FailureHypoxemic Respiratory Failure
V/Q mismatch
V/Q mismatch DO2/VO2 Imbalance
PvO2>40mmHg PvO2<40mmHg
DO2: anemia, low COVO2: hypermetabolism
Hypoxemic Respiratory FailureHypoxemic Respiratory Failure
V/Q mismatch
SHUNTV/Q = 0
DEAD SPACEV/Q = ∞
AtelectasisIntraalveolar filling Pneumonia Pulmonary edema
Pulmonary embolusPulmonary vascular dzAirway dz (COPD, asthma)
Intracardiac shuntVascular shunt in lungs
ARDSInterstitial lung dzPulmonary contusion
Hypoxemic Respiratory FailureHypoxemic Respiratory Failure
V/Q mismatch
SHUNTV/Q = 0
DEAD SPACEV/Q = ∞
AtelectasisIntraalveolar filling Pneumonia Pulmonary edema
Pulmonary embolusPulmonary vascular dzAirway dz (COPD, asthma)
Intracardiac shuntVascular shunt in lungs
ARDSInterstitial lung dzPulmonary contusion
Hypoxemic Respiratory FailureHypoxemic 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 FailureHypoxemic Respiratory Failure
Acute Respiratory Distress Syndrome
• Develops ~4-48h• Persists days-wks• Diagnosis:
– Distinguish from cardiogenic edema
– History and risk factors
Inflammatory Alveolar Injury
Inflammatory Alveolar Injury
Pro-inflmm cytokines (TNF, IL1,6,8)
Inflammatory Alveolar Injury
Pro-inflmm cytokines (TNF, IL1,6,8)
Neutrophils - ROIs and proteases damage capillary endothelium and alveolar epithelium
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
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 FailureHypoxemic Respiratory Failure
Acute Respiratory Distress Syndrome
Exudative phase Fibrotic phaseProliferative phase
Diffuse alveolar damage
Hypoxemic Respiratory FailureHypoxemic 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 FailureHypoxemic Respiratory Failure
Acute Respiratory Distress Syndrome
Indirect Lung Injury• Sepsis• Severe trauma with shock/hypoperfusion• Burns• Massive blood transfusion• Drug overdose: ASA, cocaine, opioids, phenothiazines,
TCAs. • Cardiopulmonary bypass• Acute pancreatitis
Hypoxemic Respiratory FailureHypoxemic Respiratory Failure
Acute Respiratory Distress Syndrome
Complications• Barotrauma
• Nosocomial pneumonia
• Sedation and paralysis persistent MS depression and neuromuscular weakness
Hypoxemic Respiratory FailureHypoxemic 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