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Acute Respiratory Failure

Acute Respiratory Failure. NURCAN KIZILCIK. Learning objectives. Definition , Diagnosis , Causes of ARF Clinical & laboratory findings of ARF Treatment of ARF. Acute Respiratory Failure r esults from inadequate gas exchange : Either i nsufficient O 2 transferred to the blood

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Acute Respiratory Failure

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  1. Acute Respiratory Failure NURCAN KIZILCIK

  2. Learning objectives • Definition, • Diagnosis, • Causes of ARF • Clinical & laboratory findings of ARF • Treatment of ARF

  3. AcuteRespiratoryFailure results from inadequate gas exchange: • Either insufficient O2 transferred to the blood • Hypoxemia • or inadequate CO2 removal • Hypercapnia

  4. Not a disease but a condition Result of one or more diseases involving the lungs or other body systems

  5. Respiratory tract Pump System Lungs Gas exchange O2and CO2crossthealveolar-capillarywallbydiffusion. O2 is transportedfromthelungstothecellsandCO2 is transportedfromthecellstothelungs. Roussos et al, Eur Respir J 2003;22;suppl 47: 3s-14s Laghi and Tobin, AJRCCM 2003;168:10 Ventilation

  6. ARF is inability to sustain • Arterial partial oxygen pressure (PaO2) • Carbon dioxide (PaCO2) pressure at physiological range

  7. Clinical findings • Tachypnea • Dyspnea • Stridor • Wheezing • Theuse of auxiliaryrespiratorymuscles

  8.   Intercostal retraction • Sweating • Hypertension • Mental status changes • Tachycardia / bradycardia

  9. EVALUATION OF CLINICAL FINDINGS OF HYPOXIA

  10. EVALUATION OF CLINICAL FINDINGS OF HYPERCAPNIA

  11. Traditionally, respiratory failure is divided into: type 1 and type 2 but these are not practical terms and it is better to think instead of: • Failure to ventilate • Failure to oxygenate • Failure to both ventilate and oxygenate

  12. Respiratory Failure Lung Failure Pump Failure Gas exchangeProblem Hypoxemia Decrease in ventilation Hypercapnia Roussos et al, Eur Respir J 2003;22;suppl 47: 3s-14s

  13. Laboratory • Hypoxia: pO2 < 60 mmHg • Hypercarbia: pCO2 > 45 mmHg

  14. Most important lab. indicator of adequate ventilation is arterial partial carbon dioxide level (PaCO2). • The normal value is 35 to 45 mmHg.

  15. Partial arterial oxygen (PaO2) indicates the adequacy of tissue oxygenation. Normal PaO2: 80-100 mmHgat room air. When decreased below this level, tissue hypoxia may occur.

  16. Respiratory physiology The act of respiration engages 3 processes: 1-Transfer of oxygen across the alveolus 2-Transport of oxygen to the tissues 3-Removal of CO2from blood into the alveolus and thento the environment Respiratory failure may occur from malfunctioning of any of these processes.

  17. Respiration primarily occurs at the alveolar capillary units of the lungs Fig. 66-1

  18. After diffusing into the blood, the oxygen molecules reversibly bind to the hemoglobin. • 1 g of hemoglobin combines with a maximum of 1.36 mL of oxygen.

  19. The CO2is transported in 3 main forms: 1- in simple solution 2- as bicarbonate 3-combined with protein of hemoglobin as a carbamino compound.

  20. ETIOLOGY Pulmonary52% • Pneumonia 23.7% • Atelectasis 15.4% • Chronic obstructive pulmonary disease 13.7% • Pulmonary & cardiogenic edema 9.2% • Aspiration 5.7% • Pulmonary edema –non-cardiogenic 4.9%

  21. Non- Pulmonary 47.9% • Abdominal 18.4% • Central nervous system 17.2% • Sepsis 12.3%

  22. Hypoxemic respiratory failure The pathophysiologic mechanisms: 1-V/Q mismatch: mostcommon cause of hypoxemia 2-Shunt: persistence of hypoxemia despite 100% O2inhalation

  23. Causes of type I (hypoxemic) respiratory failure: • COPD • Pneumonia • Pulmonary edema • Pulmonary fibrosis • Asthma • Pneumothorax • Pulmonary embolism • Pulmonary arterial hypertension • Pneumoconiosis • Granulomatous lung diseases • Cyanotic cong.heart disease • Bronchiectasis • ARDS • Fat embolism syndrome • Kyphoscoliosis • Obesity

  24. Causes of type II (hypercapnic) respiratory failure: • COPD • Severe asthma • Drug overdose • Poisonings • Myasthenia gravis • Polyneuropathy • Poliomyelitis • Primary muscle disorders • Porphyria • Cervical cordotomy • Head &cervical cord injury • Primary alveolar hypoventilation • Obesity-hypoventilation syndrome • Pulmonary edema • ARDS • Myxedema • Tetanus

  25. Diffusion Limitation Fig. 68-5

  26. NORMAL Neuromuscularcapacity Respiratoryworkload RESPIRATORY FAILURE Neuromuscularcapacity Respiratoryworkload Neuromuscularcapacity Respiratoryworkload Laghi and Tobin, AJRCCM 2003;168:10

  27. Increased respiratory workload : • 30-50%  Inspiratoryresistance • 100%  Elasticrecoil • 100-200%  iPEEP -Bronchoconstriction  -Bronchialedema  -Pulmonaryedema  -Pulmonaryinflammation

  28. Decreased neuromuscular capacity : • Hyperinflation • Critical illness polyneuropathy • Myopathy • Critical illness myopathy • Sepsis • Ventilator-related muscle damage • Drugs • Metabolic abnormalities • Reduction in the transport of oxygen • Drugs • Muscle fatigue

  29. Patient Evaluation • Adequacy of oxygenation is evaluated with • Pulse oximetry (SpO2) • Arterial partial blood O2 pressure • Adequacy of Ventilation • End-tidal CO2 • Arterial blood gas CO2 • Chest x-ray

  30. Cardiopulmonary Tests • Vital signs and organ perfusion • Blood pressure • Skin symptoms • Consciousness / cooperation • Pneumonia • Congestive Heart Failure • Asthma /COPD

  31. Objectives of clinical evaluation • Detection and correction of life-threatening blood gas abnormalities • Determination of ventilation requirements • Noninvasive Positive Pressure Ventilation • Invasive Mechanical Ventilation • Clarify the cause of respiratory failure • Additional diagnostic tests Sigillito et al, Emerg Med Clin N Am 2003;21:239

  32. TREATMENT • Adequate tissue oxygenation must be ensured - Airway patency and - Adequate ventilation should be ensured, - Oxygen therapy - Blood transfusion - For respiratory depression: adequate muscle and nerve function should be maintained and responsible drugs should be discontinued • The primary cause should be treated • Symptomatic treatment

  33. Oxygen Therapy • Nasal cannula • Simple oxygen mask • Partial nonrebreathing mask • Non-rebreathing maske • Large volume nebulizer mask

  34. When Mechanical Ventilation is needed? • paO2 < 60 mmHg ± paCO2 > 45 mmHg • Respiratory rate > 30-35 /minute • Abdominal breathing • Rapid shallow breathing • Supporting the use of inspiratory respiratory muscles

  35. Objectives of Mechanical Ventilation • ↑ PaO2 • ↓ PaCO2 • ↓ Acidosis • Unloading of respiratory muscles • Reduce breathlessness

  36. Mechanical Ventilation Treatment Options • Endotracheal intubation + invasivemechanical ventilation • Noninvasive mechanical ventilation

  37. Indications for invasive intubation • Respiratory arrest • Hemodynamic instability • Confusion • Acute progressive respiratory acidosis • When NIPPV is contraindicated • No response to NIPPV • Hypoxemic patients unresponsive to oxygen therapy

  38. Differential Diagnosis • Pulmonary Diseases • Cardiovascular Diseases • Systemic Diseases

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