1 / 31

Acute Respiratory Failure: Recognition and Early Intervention

Acute Respiratory Failure: Recognition and Early Intervention. Carrie Samiec, D.O. Pulmonary & Critical Care Franklin Square Hospital Center. Definition: Respiratory Failure . Failure of the respiratory system in one or both of its gas exchange functions: Oxygenation

sandra_john
Télécharger la présentation

Acute Respiratory Failure: Recognition and Early Intervention

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Acute Respiratory Failure:Recognition and Early Intervention Carrie Samiec, D.O. Pulmonary & Critical Care Franklin Square Hospital Center

  2. Definition: Respiratory Failure • Failure of the respiratory system in one or both of its gas exchange functions: • Oxygenation • Carbon dioxide elimination • Can be acute or chronic • Documented by PaCO2 > 50 mm of Hg or PaO2 < 60 mm of Hg.

  3. Respiratory Failure Classification • Hypoxemic • PaO2 <60 mmHg, normal or low PaCO2 • Hypercapnic • PaCO2 >50 mmHg, can also see hypoxemia • Acute drop in blood pH (<7.3) • Acute • Chronic • Renal compensation, metabolic alkalosis, polycythemia, pulmonary hypertension, cor pulmonale

  4. Respiratory Failure: Causes • Upper airway dysfunction • Lower airway obstruction • Alveolar and pleural disease • CNS causes

  5. Respiratory Failure: Causes • Upper airways obstruction: > Laryngomalacia > Subglottic stenosis > Laryngotracheobronchitis > Tracheitis & Epiglottitis > Retropharyngeal / Peritonsillar abscess > Acute hypertrophic tonsillitis > Diphtheria > foreign body, trauma, vocal cord palsy

  6. Lower airway obstruction: > Bronchiolitis, Asthma, Foreign body • Alveolar and pleural disease: > pneumonia, pulmonary edema, effusion empyma, pneumothorax, ARDS • CNS causes: > Infections, injury, trauma, seizures > tetanus, SMA, Polio > AIDP, Phrenic nerve injury > Myasthenia gravis, botulism, > Muscle dystrophies, Polymyositis > Congenital myopathies, muscle fatigue

  7. Respiratory Distress:signs of impending respiratory failure • Tachypnea, diaphoresis • Exaggerated use of accessory muscles • Intercostal, supraclavicular and subcostal retractions • Paradoxical/abdominal breathing • In neuromuscular disease, the signs of respiratory distress may not be obvious • In CNS disease, an abnormally low respiratory rate, and shallow breathing are clues to impending respiratory failure

  8. Arterial Blood Gases • Arterial Blood Gas analysis: single most important lab test for evaluation of respiratory failure.

  9. Evaluation of Respiratory failure The following parameters are important in evaluation of respiratory failure: • PaO2 • PaCO2 • Alveolar-Arterial PO2 Gradient • Hyperoxia Test • Blood pH

  10. PaO2 / PaCO2 • Normal value depends on : a. Position of patient during sampling b. Age of patient • PaO2 (Upright) = 104.2 -- 0.27 x age (Yrs) • PaO2 (Supine) = 103.5 – 0.47 x age (Yrs) • PaCO2 : normal value= 35-45 mm of Hg unaffected by age/ positioning

  11. A - a Gradient • PAO2= FiO2 x (PB - PH20) - PACO2 / R • A-a gradient = PAO2 - PaO2 • PB = 760 mmHg (sea level) • PH20 = 47 mmHg (100% humidity) • (760 - 74) = 713 • R = 0.8 • A-a gradient = • [FiO2 x 713 - (PaCO2 / 0.8)] - PaO2

  12. Sample ABG • 7.34 / 58 / 92 / 21 / 94% on 100% Fi02 • A - a gradient: • [1.0 x 713 - (58 / 0.8)] - 92 • [713 - 72.5] - 92 • [640.5] - 92 = 548.5 • A - a gradient = 548.5 • Severe defect in gas exchange/ hypoxemia

  13. Alveolar-Arterial O2 gradient • Normal P(A-a)O2 gradient: 5-10 mm of Hg • A sensitive indicator of disturbance of gas exchange. • Useful in differentiating extrapulmonary and pulmonary causes of resp. failure. • For any age, an A-a gradient > 20 mm of Hg is always abnormal.

  14. Causes of Hypoxemia • Low PiO2~ at high altitude • Hypoventilation ~ Normal A-a gradient • V/Q mismatch ~ increased A-a gradient • R/L shunt ~ increased A-a gradient

  15. Hypoventilation-Diagnosis • PaO2 • PaCO2 is always increased • A-a gradient is normal (≤ 10 mm of Hg) • Hyperoxia Test : dramatic rise in PO2

  16. V/Q mismatch- Diagnosis • PaO2 • A-a gradient is elevated • PaCO2 may or may not be elevated • Hyperoxia test : Dramatic rise in PaO2

  17. V/Q Mismatch • Most common cause of hypoxemia • Causes include • Decreased ventilation: COPD, ILD • Hypo/hyperperfusion: PE • Minute ventilation increases due to chemoreceptor stimulation • Corrects with hyperoxia/100% oxygen

  18. R-L shunt: diagnosis • PaO2 is • PaCO2 is usually normal unless shunt is severe (>60%) • A-a gradient is • Hyperoxia Test : Poor / No response

  19. Shunt Physiology • Shunt occurs when deoxygenated blood bypasses ventilated alveoli and mixes with oxygenated blood • Results in decreased arterial O2 content • Intracardiac shunts: • ASD, VSD, PFO • Intrapulmonary shunts • PNA, Pulm edema, AVMs

  20. Hypercapnia :Causes • Acute Hypoventilation • CNS depression: drugs, stroke, seizure • Neuromuscular disease: ALS, MS, Guillain-Barre, MG, C-spine injury • Severe low V/Q mismatch • COPD, Asthma, ARDS • Chronic hypoventilation • OSA, obesity

  21. Status of ABG • It is not possible to predict PaO2 and PaCO2 accurately using clinical criteria. • Thus, the diagnosis of Respiratory failure depends on results of ABG studies.

  22. Respiratory failure:Interventions • Supportive therapy • Upon arrival to the bedside • Establish factors contributing to resp failure • Use ABG to identify type of resp failure • Choose therapies based on physiology and severity • Specific therapy

  23. Assessment &Supportive Therapy • Secure the airway (ABCs) • Pulse oximetry, vital signs • Oxygen: by mask, nasal cannula, bag-valve mask • Proper positioning • Nebulization if indicated • Blood sampling: Routine, electrolytes, ABG • Secure IV access • CXR: upright AP & lateral views

  24. Hypoxemic / Non - Hypercapnic respiratory failure • The major problem is PaO2. • If due to low V/Q mismatch; oxygen therapy. • If due to pulmonary intra-parenchymal shunts (ARDS), assisted ventilation with PEEP may be needed. • If due to intracardiac R-L shunt: O2 therapy is of limited benefit. Surgical/advanced intervention is often needed.

  25. Hypercapnic Respiratory failure • Key decision is whether mechanical ventilation is required or not. • In Acute respiratory acidosis: Mechanical ventilation must be strongly considered. • Chronic Resp acidosis: patient should be followed closely, mech ventilation is rarely required. • In acute-on-chronic respiratory failure, the trend of acidosis over time is a crucial factor.

  26. Mechanical Ventilation: Indications • PaO2< 55 mm Hg or PaCO2 > 60 mm Hg despite 100% oxygen therapy. • Deteriorating respiratory status despite oxygen and nebulization therapy • Anxious, sweaty, or lethargic patient with deteriorating mental status. • Respiratory fatigue: for relief of metabolic stress due to work of breathing or underlying condition (sepsis, MI, CHF, etc.)

  27. Mechanical Ventilation: Strategies • Non-Invasive Ventilation: • CPAP / BIPAP • Invasive Ventilation: • AC, VC, PC, Bilevel ventilation

  28. Non-Invasive Ventilation • BIPAP should be considered in patients with mild-moderate respiratory failure • Must have intact airway, airway-protective reflexes, appropriate mentation • NOT for: excessive secretions, obtunded patient, vomiting, severe agitation • “Bridge” therapy to stave off intubation and reverse resp. failure acutely while other therapies are administered

  29. Non-Invasive Ventilation • Proven beneficial in clinical trials for: • Acute exacerbations of COPD, Asthma, CHF • Not clear for PNA, ALI • Unloads respiratory muscles and work-of-breathing • Recruits alveoli with adjustable PEEP • May increase cardiac output in CHF

  30. Clinical Follow-up • Patients with respiratory insufficiency require very close follow-up • Usually need close interval assessments • ICU or Intermediate/Step down units • Continuous pulse-ox monitoring, cardiac and hemodynamic monitoring • Most need pulmonary and/or critical care input and management

  31. Thank you!

More Related