2. RESPIRATORY FAILURE
Inability of the respiratory system to maintain normal arterial
gas exchange i.e.
Failure to maintain normal arterial oxygen and carbon-di-
oxide tensions
Type I Hypoxemia (Low PaO2,
Normal or low PaCO2)
Type II Hypoxia and Hypercapnia
(Low PaO2 and raised Pa CO2)
3. CAUSES & PATHOPHYSIOLOGY
Impairment of lung ventilation and/or perfusion due to
diseases of lung, chest wall, pulmonary circulation or
ventilation control.
Results in low oxygen uptake or impaired CO2 removal
from arterial blood
Both type I and type II respir failure can be acute or chronic
10. HOW TO DETECT HYPOXIA & HYPERCAPNIA?
1. Clinical features
2. Blood gas estimation
Invasive: PO2, PCO2, pH
Noninvasive: SaO2
PtcO2, CO2
End tidal CO2
11. MANAGEMENT
Management of disease causing respiratory failure
Management of complications
Correction of blood gas abnormalities
Oxygen administration
Correction of acid-base anomalies
Assisted respiratory supports
12. OXYGEN THERAPY INDICATIONS
A. Acute: Short term
Hypoxemia: (PaO2 < 60mmHg)
Normoxemic hypoxia
(Low QT, Ac. M.I., Anaemia
Hypermetabolism, CO poisoning)
B. Chronic: Long term
Ch. Respiratory disease
Hypoxemia – at rest / nocturnal / exertional
13. OXYGEN THERAPY FOR ACUTE HYPOXIA
1. Correct hypoxia as early as possible
2. Higher concentrations required
3. Maintain (near) normal PaO2
4. May require assisted ventilation
5. Gradually scale down O2 concentrations/ weaning
14. COPD: BLOOD GAS ABNORMALITIES
1. Hypoxia: Ventilation: perfusion mismatch
2. Hypercapnia and Acidosis:
Airway obstruction
Alveolar hypoventilation
Respiratory muscle fatigue
Central hypoventilation
Hypoxic pulmonary vasoconstriction –
Worsening of pulmonary hypertension
15. OXYGEN THERAPY FOR COPD
Acute exacerbation/ Acute (on chronic) respiratory failure
(Hypercapnic hypoxia): Supplemental oxygen
Chronic respiratory failure- Long term oxygen therapy
(Domicilliary)
16. OXYGEN FOR AE-COPD
Worsening of hypoxemia & Hypercapnia
Small increase in FiO2 - good response
However, this can worsen hypercapnia
CO2 Narcosis
Release of hypoxic vasoconstriction Increased dead-space
Loss of hypoxic respiratory drive
Haldane effect ↓ CO2 binding capacity
•Venturi mask preferred to a simple mask
•Avoid oxygen-driven nebulization of drugs
17. MANAGEMENT OF CO2 NARCOSIS
Titrate FiO2 by the PaO2 to PAO2 ratio
Appropriate delivery systems
Management of hypercapnia
Non-invasive respiratory support
Intubation and mechanical ventilation
Respiratory stimulants
Clearing secretions/ antibiotic treatment
18. OXYGEN TOXICITY
SETTINGS
1. ICUs and “Acute” indications
Mechanical ventilation
High FiO2 vs. duration
2. Hyperbaric oxygen
3. Domiciliary use
19. OXYGEN RISKS
Physical – Fire
Functional – Increased hypoventilation,
Narcosis - High PaCO2
Cytotoxic damage – proliferative and fibrotic changes in
lungs - ARDS
20. ADULT (OR ACUTE) RESPIRATORY
DISTRESS SYNDROME
Acute respiratory failure, following an acute insult /
catastrophe (systemic or respiratory), in a previously healthy
individual, attributable to diffuse damage to alveolo-capillary
membrane resulting in interstitial and alveolar oedema.
23. WHEN TO SUSPECT?
Acute onset of breathlessness
- Respiratory distress
Presence of a catastrophe
No known cardiac or pulmonary illness (?)
No significant relief with therapy for CHF
24. DIAGNOSIS
Clinical
Radiological: CXR May be normal in first 24 hrs; Later
fluffy opacities, prominent interstitial lines, consolidations,
pulm edema
Biochemical for systemic organ function
Investigations for cause of ARDS
ECG, ECHO or cardiac cath to rule out the presence of
cardiac edema/ LHF
30. MANAGEMENT PRINCIPLES
1. Resuscitation and management of underlying
condition
2. Oxygenation: Respiratory support
3. Fluid & electrolytes
4. Nutrition support
5. Specific organ failure management
6. General care
7. Monitoring
32. VENTILATORY MANAGEMENT
Avoid alveolar over distension
Maintain FiO2 < 0.6
Use sufficient PEEP to prevent significant tidal recruitment –
derecruitment
Mode of ventilation is less important
Tolerate hypercapnia, if necessary
Weaning: Spontaneous breathing trials - T-piece, CPAP or PSV.
NIV can be used as a weaning method