Respiratory failure in children

1. Mohammad Rezaei
Fellowship of Pediatric Pulmonology

2. Respiratory distress

Respiratory distress is a clinical
impression

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. 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. 
Respiratory distress can occur in
patients without respiratory disease,
and

respiratory failure can occur in patients
without respiratory distress.

6. Respiratory failure
Acute
 Chronic


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. The causes:

conditions that affect the respiratory
pump

conditions that interfere with the normal
function of the lung and airways

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. 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. 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. Alveolar Gas Composition

PAO2 = PIO2 – (PCO2/R)
PIO2 = (BP – PH2O) . Fio2
 PAO2 = [(BP – PH2O) . Fio2] – (PCO2/R)


13. Hypoventilation

VA = VT . RR

low respiratory rate and shallow breathing
are both signs of hypoventilation.

14. Dead Space Ventilation
Anatomical
 Physiological

VD/ VT = (PaCO2-PECO2)/ PaCO2
= 0.33
Increases in decreased pulmonary perfusion:
PHTN, hypovolemia, decreased cardiac output

15. Alveolar Ventilation
VA = (VT-VD). RR

16. Hypoventilation

The Paco2 increases in proportion to a
decrease in ventilation.

Pao2 falls approximately the same
amount as the Paco2 increases.

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. 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. Thus:
oximetry is not a sensitive indicator of the
adequacy of ventilation.
This is particularly true when a patient is receiving oxygen.

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. Ventilation-Perfusion
Mismatch

22. hypoxemia due to V/Q mismatch
&
 hypoxemia due to shunt

administering Oxygen

23. Intrapulmonary Shunt

24. Diffusion

diffusion defects manifest as hypoxemia
rather than hypercarbia.
Examples :
interstitial
pneumonia, ARDS, Scleroderma, Pulmonar
y lymphangiectasia,…


25. Monitoring a Child in
Respiratory Distress and
Respiratory Failure

26. Clinical Examination

Clinical observation is the most
important component of monitoring.

27. ABG & Oximetry

ABG /CBG/ VBG

Oximetry
- Oximetry provides an invaluable and usually
accurate measurement of oxygenation.
- important to recognize its technical limitations

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. Acute
Respiratory Failure

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. 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. Chronic
Respiratory Failure

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. 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. 






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
