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