Respiratory failure in children

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Respiratory failure in children

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Respiratory failure in children

  1. 1. Mohammad Rezaei Fellowship of Pediatric Pulmonology
  2. 2. Respiratory distress  Respiratory distress is a clinical impression
  3. 3. Respiratory failure  inability of the lungs to provide sufficient oxygen (hypoxic respiratory failure) or remove carbon dioxide (ventilatory failure) to meet metabolic demands.
  4. 4. Respiratory failure Pao2 < 60 torr with breathing of room air and  Paco2 > 50 torr resulting in acidosis,   the patient's general state, respiratory effort, and potential for impending exhaustion are more important indicators than blood gas values.
  5. 5.  Respiratory distress can occur in patients without respiratory disease, and  respiratory failure can occur in patients without respiratory distress.
  6. 6. Respiratory failure Acute  Chronic 
  7. 7. The physiologic basis of respiratory failure determines the clinical picture. normal respiratory drive are breathless and anxious  decreased central drive are comfortable or even somnolent. 
  8. 8. The causes:  conditions that affect the respiratory pump  conditions that interfere with the normal function of the lung and airways
  9. 9. Respiratory Pump Dysfunction ● Decreased Central Nervous System (CNS) Input  — Head injury  — Ingestion of CNS depressant  — Adverse effect of procedural sedation  — Intracranial bleeding  — Apnea of prematurity ● Peripheral Nerve/Neuromuscular Junction  — Spinal cord injury  — Organophosphate/carbamate poisoning  — Guillian-Barre´ syndrome  — Myasthenia gravis  — Infant botulism ● Muscle Weakness  — Respiratory muscle fatigue due to increased work of breathing  — Myopathies/Muscular dystrophies
  10. 10. Airway/Lung Dysfunction ● Central Airway Obstruction  — Croup  — Foreign body  — Anaphylaxis  — Bacterial tracheitis  — Epiglottitis  — Retropharyngeal abscess  — Bulbar muscle weakness/dysfunction ● Peripheral Airways/Parenchymal Lung Disease  — Status asthmaticus  — Bronchiolitis  — Pneumonia  — Acute respiratory distress syndrome  — Pulmonary edema  — Pulmonary contusion  — Cystic fibrosis  — Chronic lung disease (eg, bronchopulmonary dysplasia)
  11. 11. Arterial gas composition depends on : the gas composition of the atmosphere  the effectiveness of alveolar ventilation  pulmonary capillary perfusion  diffusion across the alveolar capillary membrane 
  12. 12. Alveolar Gas Composition  PAO2 = PIO2 – (PCO2/R) PIO2 = (BP – PH2O) . Fio2  PAO2 = [(BP – PH2O) . Fio2] – (PCO2/R) 
  13. 13. Hypoventilation  VA = VT . RR  low respiratory rate and shallow breathing are both signs of hypoventilation.
  14. 14. Dead Space Ventilation Anatomical  Physiological  VD/ VT = (PaCO2-PECO2)/ PaCO2 = 0.33 Increases in decreased pulmonary perfusion: PHTN, hypovolemia, decreased cardiac output
  15. 15. Alveolar Ventilation VA = (VT-VD). RR
  16. 16. Hypoventilation  The Paco2 increases in proportion to a decrease in ventilation.  Pao2 falls approximately the same amount as the Paco2 increases.
  17. 17. Hypoventilation  The relationship between oxygenation and hypoventilation is complicated by the shape of the Hb-dissociation curve  Because of the dissociation curve, a patient who exhibits alarming CO2 retention might have a near normal oxygen saturation.
  18. 18. When Paco2 increases from 40 to 70 mm Hg, a dangerous level of hypoventilation, might have a Pao2 that has decreased from 100 to 60 mm Hg and, therefore, maintain an oxygen saturation of 90%. 1. PO2 100 mm Hg= SpO2 of 97% 2. PO2 60mm Hg= SpO2 of90%
  19. 19. Thus: oximetry is not a sensitive indicator of the adequacy of ventilation. This is particularly true when a patient is receiving oxygen.
  20. 20. Lung/Airway Disease  Diseases of the lung or airways affect gas exchange most often by disrupting the normal matching of V/Q or by causing a shunt.  usually can maintain a normal Paco2 as lung disease worsens simply by breathing more.  hypoxemia is the hallmark of lung disease
  21. 21. Ventilation-Perfusion Mismatch
  22. 22. hypoxemia due to V/Q mismatch &  hypoxemia due to shunt  administering Oxygen
  23. 23. Intrapulmonary Shunt
  24. 24. Diffusion  diffusion defects manifest as hypoxemia rather than hypercarbia. Examples : interstitial pneumonia, ARDS, Scleroderma, Pulmonar y lymphangiectasia,… 
  25. 25. Monitoring a Child in Respiratory Distress and Respiratory Failure
  26. 26. Clinical Examination  Clinical observation is the most important component of monitoring.
  27. 27. ABG & Oximetry  ABG /CBG/ VBG  Oximetry - Oximetry provides an invaluable and usually accurate measurement of oxygenation. - important to recognize its technical limitations
  28. 28. Condition Limitation Dark skin pigment Anemia Causes inadequate signal Bright external light Motion Decreased perfusion Venous pulsations — Severe right heart failure — Tricuspid regurgitation — Tourniquet or blood pressure cuff above site Results in low reading Abnormal hemoglobin concentration — Methemoglobin Unreliable reading (tends to read 80% to 85% saturation regardless of actual saturation) — SS hemoglobin Saturation accurate, but hemoglobin dissociation curve shifted to right — Carboxyhemoglobin Spuriously high saturation readings
  29. 29. Acute Respiratory Failure
  30. 30. ARF  most common cause of cardiac arrest in children. When presented with a child who has:  a decreased level of consciousness,  slow/shallow breathing, or increased  respiratory drive, the possibility of ARF should be considered
  31. 31. First:  to assure adequate gas exchange and circulation (the ABCs). Oxygen Administration to maintain ….  If Ventilation is or appears to be inadequate …..  Intubation ?  Need ICU
  32. 32. Chronic Respiratory Failure
  33. 33. CRF is seen most commonly in children who have: Respiratory muscle weakness (muscular dystrophy, anterior horn cell disease) or  severe chronic lung diseases (BPD, endstage cystic fibrosis) 
  34. 34. usually has an insidious onset  Most children do not have dyspnea.  PH normal or near normal , unless…..   Recognizing need careful monitoring of children at risk for CRF
  35. 35.        Disordered sleep Daytime hypersomnolence Morning headaches Altered mental status Increased respiratory symptoms Cardiomegaly Decreased baseline oxygenation CRF often presents first during sleep  Develops an intercurrent illness , Fever 

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