This document discusses respiratory distress and respiratory failure. Respiratory distress refers to increased work of breathing, while respiratory failure is the inability of the lungs to provide oxygen or remove carbon dioxide. Respiratory failure can be acute or chronic. It can occur due to problems with the respiratory pump (central nervous system issues, muscle weakness) or due to airway/lung dysfunction (conditions affecting gas exchange like asthma, pneumonia). Proper monitoring of patients with respiratory distress or failure includes clinical examination, blood gas analysis, and oximetry. Immediate treatment of acute respiratory failure focuses on oxygenation and ventilation. Chronic respiratory failure often has a more insidious onset and requires careful monitoring, especially during sleep or illness.

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
