Acute Resp. Failure/Acute Lung Injury
ARF: sudden deterioration in pulmonary gas exchange = CO2 retention & inadequate oxygenation |
paO2 < 60 mmHg |
(should be 80-100) |
paCO2 60 mmHg |
(should be 35-45) |
arterial pH < 7.35 |
(pts usually acidotic) |
Causes
Direct |
Indirect |
Aspiration |
Sepsis |
Pneumonia |
Burns |
Contusions/trauma |
Truama |
Upper airway
obstruction |
TRALI |
Toxic inhalation |
Drug reaction/OD |
SARS |
Cardiopulm. bypass |
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Pancreatitis |
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Multiple fractures |
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Lung/bone marrow tx |
Stages of ARF
Stage 1: inc. SOB, RR, few CXR changes... within 24 hr signs of ARDS (CXR changes)
- Tachypneic, dyspneic |
Stage 2 (Exudative): vent. required
- Address underlying issues |
Stage 3 (Proliferative): hemodynamically unstable
- Can't maintain BP, tachy, compen. mechanisms, inflammation & cascade of events |
Stage 4 (Fibrotic): lung fibrosis issues; vent. management issues
- Dec. compliance, stiffness |
Types of Respiratory Failure
Type 1 - Acute Hypoxemic: abnl. transport of O2 w/ resultant inadequate oxygenation |
Type 2 - Hypercapnic: inadequate alveolar ventilation; marked elevation in paCO2 |
Type 3 - Mixed Hypoxemic-Hypercapnic: inadequate alveolar ventilation & abnormal O2 transport
- Often most common type |
Management of ARF
Warrants immediate intervention! |
GOALS:
Correct the cause
Alleviate hypoxemia & hypercapnia |
Indications for Intubation
Altered mental status or coma |
Severe respiratory distress |
Extremely low or agonal RR (gasping)
- Cerebral issue r/t O2 |
Obvious respiratory muscle fatigue - r/t inc. work of breathing = mechanical vent. |
Peripheral cyanosis - fingers, lips dusky |
Impending cardiopulm. arrest - heart starts to compensate (tachy, arrythmias) cardiac arrest |
Better to intubate electively rather than emergently!
Mechanical vent. - helps to breathe, protects airway
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Systemic Inflammatory Response Syndrome (SIRS)
2+ of... |
Temp. > 100.4oF (38oC) or 98.6oF (36oC) |
HR > 90 bpm |
RR > 20 breaths/min or paCO2 < 32 |
WBC > 12,000 or < 4,000 or/ >10% bands |
Older adults - inc. risk for MODS w/ less chance of recovery from ARDS
Acute Respiratory Distress Syndrome (ARDS)
Severe end of continuum |
Complex syndrome w/ high mortality risk |
Precipitated by direct or indirect lung injury |
Pathophysiology:
Lung injury Dec. blood flow to lungs (inflamm. mediators thin lung lining) Alveolar membrane damage (membranes thicken, gases can't exchange)
Inc. membrane protein permeability ("Leak syndrome"; changes osmotic pressure) Interstitial & intra-alveolar edema (alveolar area flooded = pulm. edema) Further impaired oxygenation Pulm. edema Inflamm. changes can lead to fibrosis (may cause permanent lung change) |
Surfactant gets lost & makes process worse...
- Dec. gas exchange
- Dec. lung compliance (resistance, pressure)
ARDS (cont.)
Symptoms can develop very quickly after lung insult |
Assessment: |
- Accessory muscle use |
- Tachypneic |
- Tachycardia |
- Restless, air hunger = change in O2
- Confusion |
- New/worsening lung sounds (crackles, wheezes) steroids |
- Change in SpO2 |
- Lethargy (lose ability to protect airway) |
- Dyspnea |
- At risk for arrythmias |
- Change in renal status |
Bolded are the earliest signs
ARDS Diagnostic Criteria
paO2-FiO2 ratio < 200 - shunt formula; normally > 300 |
B/L infiltrates on CXR - white out |
Elevated serum lactate levels - indicates anaerobic metabolism, tissue hypoxia |
No cariac etiology for pulm. edema |
Deterioration of ABG's despite intervention - resistant to O2 |
ARDS Management
GOALS:
- Correct the cause
- Prevent further damage
- Supportive care |
Care bundles to improve outcomes |
5 P's of ARDS:
- Perfusion (max O2 transport)
- Position
- Protective lung vent.
- Protocol weaning
- Prevent complications |
Mechanical ventilation |
Fluid status: RA/CVP, JVD, BP, urinary output
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Mechanical Ventilation
Improves O2, figures out CO2, buys time |
Lowest FiO2 possible, smallest TV possible |
Modes of MV: |
- Volume cycled: pushes air in until preset volume delivered |
- Time cycled: pushes air in until preset time reached |
- Assist modes: pt can assist but vent can take over work of breathing |
- Pressure support: weaning mode; depends on pt's breathing (used for weaning) |
- Pressure control: preset volume (based on age, sex, height) |
- Airway Pressure-Release Ventilation (APRV) |
Weaning ASAP!
- Infection
- Dependent on machine
- Muscles dependent
- Vent may cause trauma (barotrauma, pressure trauma) |
Positive End Expiratory Pressure (PEEP): back pressure prevents alveolar collapse; helps to keep fluid out of alveoli |
- Inc. PEEP = inc. intrathoracic pressure dec. perfusion = dec. CO
- Affected intrathoracic pressure = organ failure |
Management of Ventilated Patients
3 Priorities: |
1) Monitor & evaluate pt response
- Vent setting, trach appropriately
- Assess s/s of distress (lung sounds, chest expansion, ABC & disynchrony r/t proper setting [change vent settings]) |
2) Manage vent safely
- Not alone, daily CXR for placement |
3) Prevent complications
- Oral care (dec. bacteria), turn & repo. (changes lung perfusion), VAP protocol (elevate HOB >30o, aspiration precautions), DVT prophylaxis, skin care |
Note:
- Breath sounds should be equal & symm.
- Document safety, measurement |
Proning: no shock, inc. ICP, unstable spine |
Pharmacotherapy:
- Antibiotics (if known microorganism)
- Bronchodilators (airway patency)
- Surfactant? (not really used, expensive)
- Corticosteroids? (immunosuppressed, glycemic control)
- Diuretics (dec. lung/general edema, watch electrolytes)
- Neuromuscular blocking agents (paralytic agents, sedatives = dec. work of breathing)
- Flolan? (new; inc. flow, V/Q mismatch)
- Epinephrine
- Low dose dopamine |
Ex. Neuromuscular Blocking Agents - propophol, Nimbex, + inotropes
+ Inotropes: dilate vascular bed = inc. CO (dibutamine, watch for dec. BP - r/t dose; vasopressors) |
Nutrition:
- Dec. mortality, days of not eating prophylactic enzyme release
- Avoid inc. carb feeds |
Prevent complications - VAP, SIRS, MODS, DVT, infection, skin breakdown |
Nursing Diagnoses
ARDS |
Mechanical Vent |
Impaired gas exchange |
Risk for infection |
Dec. tissue perfusion |
Risk for injury - r/t airway |
Airway clearance |
Risk for injury - r/t immobility |
NO ineffective breathing pattern
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