Transcript Respiratory Failure
Acute Respiratory Failure
Respiratory System
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Consists of two parts:
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Gas exchange organ (lung): responsible for OXYGENATION
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Pump (respiratory muscles and respiratory control mechanism): responsible for VENTILATION NB: Alteration in function of gas exchange unit (oxygenation) OR of the pump mechanism (ventilation) can result in respiratory failure
Normal Lung
Lung Anatomy
Normal Alveoli
Gas Exchange Unit Fig. 66-1
Normal ABGs
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pH = 7.35-7.45
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CO2 = 35-45
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HCO3= 23-27
Respiratory and Metabolic Acidosis and Alkalosis
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CO2 is an acid and is controlled by the Respiratory (Lung) system
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HCO3 is an alkali and is controlled by the Metabolic (Renal) system
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Respiratory response is immediate; Metabolic response can take up to 72 hours to respond (except in patients with COPD who are in a constant state of Compensation!)
Step 1:
ABG Interpretation
Check the pH: Is it acidotic or alkalotic or normal? pH below 7.35 is acidotic; pH above 7.45 is alkalotic If pH is normal, then the ABG is compensated; if pH not normal, then the ABG is uncompensated
ABG Interpretation (cont’d)
Step 2. Check the CO2 and HCO3:
If the CO2 (acid) is above 45 , the pt is acidotic; if the CO2 is below 35 , the pt is alkalotic
If the HCO3 is above 27 , the patient is alkalotic; if the HCO3 is below 23 , the patient is acidotic
ABG Interpretation (cont’d)
Step 3 If the CO2 is high (above 45), then the patient is in Respiratory Acidosis; if the CO2 is low (below 35), then the patients is in Respiratory Alkalosis.
If the HCO3 is high (above 27), then the patient is in Metabolic Alkalosis; if the HCO3 is low (below 23), then the patient is in Metabolic Acidosis.
ABG Example #1
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pH = 7.36
CO2 = 41 HCO3 = 27 Diagnosis: ?
ABG Example #2
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pH = 7.49
CO2 = 37 HCO3 = 32 Diagnosis: ?
ABG Example #3
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pH = 7.29
CO2 = 50 HCO3 = 26 Diagnosis: ?
ABG Example #4
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pH = 7.40
CO2 = 32 HCO3 = 30 Diagnosis: ?
Acute Respiratory Failure
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Results from inadequate gas exchange
Insufficient O 2 transferred to the blood
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Hypoxemia
Inadequate CO 2 removal
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Hypercapnia
Acute Respiratory Failure with Diffuse Bilateral Infiltrates
Acute Respiratory Failure
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Not a disease but a condition Result of one or more diseases involving the lungs or other body systems
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NB: Acute Respiratory Failure: when oxygenation and/or ventilation is inadequate to meet the body’s needs
Acute Respiratory Failure
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Classification:
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Hypoxemic respiratory failure (Failure of oxygenation)
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Hypercapnic respiratory failure (Failure of ventilation)
Classification of Respiratory Failure Fig. 66-2
Acute Respiratory Failure
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Hypoxemic Respiratory Failure
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PaO 2 of 60 mm Hg or less (Normal = 80 - 100 mm Hg)
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Inspired O 2 concentration of 60% or greater
Acute Respiratory Failure
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Hypercapnic Respiratory Failure
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PaCO 2 above normal (>45 mm Hg)
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Acidemia (pH <7.35)
Hypoxemic Respiratory Failure Etiology and Pathophysiology
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Causes:
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Ventilation-perfusion (V/Q) mismatch
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Shunt
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Diffusion limitation
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Alveolar hypoventilation
V-Q Mismatching
I) V/ Q mismatch
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Normal ventilation of alveoli is comparable to amount of perfusion
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Normal V/Q ratio is 0.8 (more perfusion than ventilation)
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Mismatch d/t:
Inadequate ventilation
Poor perfusion
Range of V/Q Relationships Fig. 66-4
Hypoxemic Respiratory Failure Etiology and Pathophysiology Causes V/ Q mismatch
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COPD
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Pneumonia
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Asthma
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Atelectasis
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Pulmonary embolus
Hypoxemic Respiratory Failure Etiology and Pathophysiology II) Shunt
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An extreme V/Q mismatch
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Blood passes through parts of respiratory system that receives no ventilation
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d/t obstruction OR fluid accumulation Not Correctable with 100% O2
Diffusion Limitations
III) Diffusion Limitations
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Distance between alveoli and pulmonary capillary is one- two cells thick
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With diffusion abnormalities: there is an increased distance between alveoli (may be d/t fluid)
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Correctable with 100% O2
Hypoxemic Respiratory Failure Etiology and Pathophysiology Causes Diffusion limitations
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Severe emphysema
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Recurrent pulmonary emboli
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Pulmonary fibrosis
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Hypoxemia present during exercise
Diffusion Limitation Fig. 66-5
Alveolar Hypoventilation
IV) Alveolar Hypoventilation
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Is a generalized decrease in ventilation of lungs and resultant buildup of CO2
Hypoxemic Respiratory Failure Etiology and Pathophysiology Causes Alveolar hypoventilation
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Restrictive lung disease
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CNS disease
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Chest wall dysfunction
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Neuromuscular disease
Hypoxemic Respiratory Failure Etiology and Pathophysiology
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Interrelationship of mechanisms
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Hypoxemic respiratory failure is frequently caused by a combination of two or more of these four mechanisms Effects of hypoxemia
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Build up of lactic acid → metabolic acidosis → cell death CNS depression Heart tries to compensate → ↑ HR and CO If no compensation: ↓ O2, ↑ acid, heart fails, shock, multi system organ failure
Hypercapnic Respiratory Failure Etiology and Pathophysiology
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Imbalance between ventilatory supply and demand
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Occurs when CO2 is increased
Causes Hypercapnic Respiratory Failure
I) Alveolar Hypoventilation and VQ Mismatch:
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Ventilation not adequate to eliminate CO2 Leads to respiratory acidosis
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Eg. Narcotic OD; Guillian-Barre, ALS, COPD, asthma
Causes Hypercapnic Respiratory Failure
II) VQ Mismatch: - Leads to increased work of breathing - Insufficient energy to overcome resistance; ventilation falls; ↑PCO2; respiratory acidosis
Hypercapnic Respiratory Failure Categories of Causative Conditions
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I) Airways and alveoli
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Asthma
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Emphysema
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Chronic bronchitis
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Cystic fibrosis
Hypercapnic Respiratory Failure Categories of Causative Conditions
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II) Central nervous system
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Drug overdose
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Brainstem infarction
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Spinal cord injuries
Hypercapnic Respiratory Failure Categories of Causative Conditions
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III) Chest wall
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Flail chest
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Fractures
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Mechanical restriction
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Muscle spasm
Hypercapnic Respiratory Failure Categories of Causative Conditions
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IV) Neuromuscular conditions
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Muscular dystrophy
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Multiple sclerosis
Respiratory Failure Tissue Oxygen Needs
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Major threat is the inability of the lungs to meet the oxygen demands of the tissues
Respiratory Failure Clinical Manifestations
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Sudden or gradual onset A sudden
in PaO 2 or rapid
is a serious condition in PaCO 2
Respiratory Failure Clinical Manifestations
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When compensatory mechanisms fail, respiratory failure occurs
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Signs may be specific or nonspecific
Respiratory Failure Clinical Manifestations
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Severe morning headache Cyanosis
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Late sign Tachycardia and mild hypertension
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Early signs
Respiratory Failure Clinical Manifestations
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Consequences of hypoxemia and hypoxia
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Metabolic acidosis and cell death
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Cardiac output
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Impaired renal function
Respiratory Failure Clinical Manifestations
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Specific clinical manifestations
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Rapid, shallow breathing pattern
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Sitting upright
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Dyspnea
Respiratory Failure Clinical Manifestations
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Specific clinical manifestations
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Pursed-lip breathing
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Retractions
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Change in Inspiratory:Expiratory ratio
Respiratory Failure Diagnostic Studies
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Physical assessment ABG analysis Chest x-ray CBC ECG
Respiratory Failure Diagnostic Studies
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Serum electrolytes Urinalysis V/Q lung scan Pulmonary artery catheter (severe cases)
Acute Respiratory Failure Nursing and Collaborative Management
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Nursing Assessment
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Past health history
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Medications
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Surgery
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Tachycardia
Acute Respiratory Failure Nursing and Collaborative Management
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Nursing Assessment
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Fatigue
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Sleep pattern changes
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Headache
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Restlessness
Acute Respiratory Failure Nursing and Collaborative Management
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Nursing Diagnoses
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Ineffective airway clearance
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Ineffective breathing pattern
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Risk for imbalanced fluid volume
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Anxiety
Acute Respiratory Failure Nursing and Collaborative Management
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Nursing Diagnoses
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Impaired gas exchange
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Imbalanced nutrition: less than body requirements
Acute Respiratory Failure Nursing and Collaborative Management
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Planning
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Overall goals:
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ABGs and breath sounds within baseline
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No dyspnea
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Effective cough
Acute Respiratory Failure Nursing and Collaborative Management
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Prevention
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Thorough physical assessment
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History
Acute Respiratory Failure Nursing and Collaborative Management
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Respiratory Therapy
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Oxygen therapy
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Mobilization of secretions
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Effective coughing and positioning
Acute Respiratory Failure Nursing and Collaborative Management
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Respiratory Therapy
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Mobilization of secretions
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Hydration and humidification
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Chest physical therapy
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Airway suctioning
Acute Respiratory Failure Nursing and Collaborative Management
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Respiratory Therapy
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Positive pressure ventilation (PPV)
Acute Respiratory Failure Nursing and Collaborative Management
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Drug Therapy
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Relief of bronchospasm
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Bronchodilators
Acute Respiratory Failure Nursing and Collaborative Management
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Drug Therapy
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Reduction of airway inflammation
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Corticosteroids
Acute Respiratory Failure Nursing and Collaborative Management
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Drug Therapy
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Reduction of pulmonary congestion
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IV diuretics
Acute Respiratory Failure Nursing and Collaborative Management
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Drug Therapy
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Treatment of pulmonary infections
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IV antibiotics
Acute Respiratory Failure Nursing and Collaborative Management
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Drug Therapy
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Reduction of severe anxiety, pain, and agitation
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Benzodiazepines
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Narcotics
Acute Respiratory Failure Nursing and Collaborative Management
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Medical Supportive Therapy
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Treat the underlying cause
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Maintain adequate cardiac output and hemoglobin concentration
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Monitor BP, O2 saturation, urine output
Acute Respiratory Failure Nursing and Collaborative Management
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Nutritional Therapy
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Maintain protein and energy stores
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Enteral or parenteral nutrition
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Supplements