Causes and description of adult respiratory failure

1. Respiratory
Failure (RF)
• Mohankumar T, MD,ABIM,DSc,DPPR
• Chief & Senior Consultant Pulmonologist,
• Department of Pulmonary, Critical Care &
Sleep Medicine,
• One Care Medical Center,
• Coimbatore.
• Email: tmkdr@yahoo.co.in
•

2. Respiratory
Failure (RF)
Normal ABG
Definition
Classification of RF
Distinction between Acute and Chronic RF
Pathophysiologic causes of Acute RF
Diagnosis of RF
Causes
Clinical presentation
Investigations
Management of RF

3. Arterial Blood Gases (ABG)
Normal values at sea level
• pH 7.35-7.45
• PaO2 >70 mmHg
• PaCO2 35-45 mmHg
• HCO3 22-28 mmol/l
• Minute ventilation = Tidal
volume X Respiratory rate
• ↓pH Acidosis
• ↑pH Alkalosis
• ↓ PaO2 Hypoxemia
• ↑PaCO2 Hypercapnia
• ↓pH+ ↑PaCO2 R. acidosis
• ↑HCO3
• ↑pH+↓PaCO2 R.Alkalosis
• ↓HCO3

5. Respiratory
Failure (RF)
• Definitions
• Clinical conditions in which
PaO2 < 60 mmHg while
breathing room air or a PaCO2
> 50 mmHg
• Failure of oxygenation and
carbon dioxide elimination
• Acute and chronic
• Type 1 or 2

6. Classification of RF
Type 1
Hypoxemic RF
❑PaO2 < 60 mmHg with
normal or ↓ PaCO2
❑Associated with acute
diseases of the lung
❑Pulmonary edema
Cardiogenic, noncardiogenic
(ARDS), pneumonia,
pulmonary hemorrhage, and
collapse
Type 2
Hypercapnic RF
• PaCO2 > 50 mmHg
• Hypoxemia is common
• Drug overdose,
neuromuscular disease, chest
wall deformity, COPD, and
Bronchial asthma

8. ▪ Distinction between Acute and Chronic RF
Acute RF
• Develops over minutes to
hours
• ↓ pH quickly to <7.2
• Example; Pneumonia
Chronic RF
• Develops over days
• ↑ in HCO3
• ↓ pH slightly
• Polycythemia, Corpulmonale
• Example; COPD

9. Pathophysiologic causes of Acute RF
●Hypoventilation
●V/P mismatch
●Shunt
●Diffusion abnormality

10. Pathophysiologic causes of Acute RF
1 - Hypoventilation
Occurs when ventilation ↓ 4-6 l/min
Causes
• Depression of CNS from drugs
• Neuromuscular disease of respiratory ms
↑PaCO2 and ↓PaO2
Alveolar –arterial PO2 gradient is normal
COPD

11. Pathophysiologic causes of Acute RF
●Hypoventilation
●V/P mismatch
●Shunt
●Diffusion abnormality

12. Pathophysiologic causes of Acute RF
2 -V/Q mismatch
Most common cause of hypoxemia
Low V/Q ratio, may occur either from
• Decrease of ventilation 2ry to airway or interstitial
lung disease
• Overperfusion in the presence of normal ventilation
e.g. PE
Admin. of 100% O2 eliminate hypoxemia

13. Pathophysiologic causes of Acute RF
●Hypoventilation
●V/P mismatch
●Shunt
●Diffusion abnormality

14. Pathophysiologic causes of Acute RF
3 -Shunt
The deoxygenated blood bypasses the ventilated
alveoli and mixes with oxygenated blood → hypoxemia
Persistent of hypoxemia despite 100% O2 inhalation
Hypercapnia occur when shunt is excessive > 60%

15. Pathophysiologic causes of Acute RF
3 – Causes of Shunt
Intracardiac
• Right to left shunt
• Fallot’s tetralogy
• Eisenmenger’s syndrome
Pulmonary
• A/V malformation
• Pneumonia
• Pulmonary edema
• Atelectasis/collapse
• Pulmonary Hge
• Pulmonary contusion

16. Pathophysiologic causes of Acute RF
●Hypoventilation
●V/P mismatch
●Shunt
●Diffusion abnormality

17. Pathophysiologic causes of Acute RF
4 - Diffusion abnormality
Less common
Due to
• Abnormality of the alveolar membrane
• ↓ The number of the alveoli
Causes
• ARDS
• Fibrotic lung disease

18. Diagnosis of RF
1 – Clinical (symptoms, signs)
Hypercapnia
• ↑Cerebral blood flow, and CSF
Pressure
• Headache
• Asterixis
• Papilloedema
• Warm extremities, collapsing pulse
• Acidosis (respiratory, and
metabolic)
• ↓pH, ↑ lactic acid
Hypoxemia
Dyspnea, Cyanosis
Confusion, somnolence, fits
Tachycardia, arrhythmia
Tachypnea (good sign)
Use of accessory ms
Nasal flaring
Recession of intercostal ms
Polycythemia
Pulmonary HTN, Corpulmonale, Rt. HF

19. Diagnosis of RF
2 – Causes
1 – CNS
• Depression of the neural
drive to breath
• Brain stem tumors or vascular
abnormality
• Overdose of a narcotic, sedative
Myxedema, chronic metabolic
alkalosis
• Acute or chronic hypoventilation
and hypercapnia

20. Diagnosis of RF
2 – Causes
2. Disorders of peripheral nervous system, Respiratory muscles, and
Chest wall
Inability to maintain a level of minute ventilation appropriate for
the rate of CO2 production
Guillian-Barre syndrome, muscular dystrophy, myasthenia gravis,
KS, morbid obesity
Hypoxemia and hypercapnia

21. Diagnosis of RF
2 – Causes
3 - Abnormities of the airways
Upper airways
• Acute epiglotitis
• Tracheal tumors
Lower airway
• COPD, Asthma, cystic fibrosis
Acute and chronic hypercapnia

22. Diagnosis of RF
2 – Causes
4 - Abnormities of the alveoli
Diffuse alveolar filling
Hypoxemic RF
• Cardiogenic and noncardiogenic pulmonary edema
• Aspiration pneumonia
• Pulmonary hemorrhage
Associate with Intrapulmonary shunt and increase work of
breathing

23. Diagnosis of RF
3 – Common causes
Hypoxemic RF
Chronic bronchitis, emphysema
Pneumonia, pulmonary edema
Pulmonary fibrosis
Asthma, pneumothorax
Pulmonary embolism,
Pulmonary hypertension
Bronchiectasis, ARDS
Fat embolism, KS, Obesity
Cyanotic congenital heart disease
Granulomatous lung disease
Hypercapnic RF
Chronic bronchitis,emphysema
Severe asthma, drug overdose
Poisonings, Myasthenia gravis
Polyneuropathy, Poliomyelitis
Primary ms disorders
1ry alveolar hypoventilation
Obesity hypoventilation synd.
Pulmonary edema, ARDS
Myxedema, head and cervical
cord injury

24. Diagnosis of RF
3 - Investigations
ABG
CBC, Hb
• Anemia → Tissue hypoxemia
• Polycythemia →Chronic RF
Urea, Creatinine
LFT → clues to LF or its complications
Electrolytes (K, Mg, Ph) → Aggravate RF
↑ CPK, ↑ Troponin 1 → MI
↑CPK, normal Troponin 1 → Myositis
TSH → Hypothyroidism

25. Diagnosis of RF
3 - Investigations
❑Chest x ray → Pulmonary edema
→ ARDS
❑Echocardiography → Cardiogenic pulmonary
edema
→ ARDS
→ PAP, Rt ventricular
hypertrophy in CRF
■ PFT- (FEV1/ FVC ratio)
Decrease → Airflow obstruction
Increase → Restrictive lung disease

26. Diagnosis of RF
3 - Investigations
ECG → cardiac cause of RF
→ Arrhythmia due to hypoxemia and
severe acidosis
■ Right heart catheterization to measure
• ●Pulmonary capillary wedge pressure (PCWP)
• ● Normal → ARDS (<18 mmHg)
• ● Increased → Cardiogenic pulmonary
edema

27. Distinction
between
Noncardiogenic
(ARDS) and
Cardiogenic
pulmonary
edema
ARDS
• Tachypnea, dyspnea,
crackles
• Aspiration, sepsis
• 3 to 4 quadrant of
alveolar flooding with
normal heart size,
systolic, diastolic
function
• Decreased compliance
• Severe hypoxemia
refractory to O2 therapy
• PCWP is normal <18 mm
Hg
Cardiogenic edema
• Tachypnea, dyspnea,
crackles
• Lt ventricular
dysfunction, valvular
disease, IHD
• Cardiomegaly, vascular
redistribution, pleural
effusion, perihilar bat-
wing distribution of
infiltrate
• Hypoxemia improved on
high flow O2
• PCWP is High >18
mmHg

28. Management of ARF

29. Management of ARF
ICU admition
1 -Airway management
• Endotracheal intubation:
• Indications
• Severe Hypoxemia
• Altered mental status
• Importance
• Precise O2 delivery to the lungs
• Remove secretion
• Ensure adequate ventilation

30. Management of ARF
2 -Correction of
hypoxemia
❑O2 administration via
nasal prongs, face mask,
intubation and
Mechanical ventilation
❑Goal: Adequate O2
delivery to tissues
❑PaO2 = > 60 mmHg
❑ Arterial O2 saturation
>90%

31. Management of ARF
3- Correction of
hypercapnia
➢Control the underlying cause
➢Controlled O2 supply
1 -3 lit/min, titrate according O2
saturation
➢O2 supply to keep the O2
saturation >90% but <93 to
avoid inducing hypercapnia
➢COPD-chronic bronchitis,
emphysema

32. Management of ARF
4 – Mechanical ventilation
Indications
• Persistence hypoxemia despite O2supply
• Decreased level of consciousness
• Hypercapnia with severe acidosis (pH< 7.2)

33. Management of ARF
• 4 - Mechanical ventilation
• Increase PaO2
• Lower PaCO2
• Rest respiratory muscle (respiratory muscle
fatigue)
• Ventilator
• Assists or controls the patient breathing
• The lowest FIO2 that produces SaO2 >90% and
PO2 >60 mmHg should be given to avoid O2
toxicity

34. Goals of Mechanical
Ventilation
n Correct hypoxemia
❑ High F IO2
❑ Positive end expiratory pressure
(PEEP)
n Improve cardiac function
n Decreases preload
n Decreases afterload
n Decreases metabolic demand

35. Goals of Mechanical
Ventilation
n Improve ventilation by augmenting respiratory
rate and tidal volume
➢ Assistance for neural or muscle dysfunction
➢ Sedated, comatose or paralyzed patient
➢ Neuropathy, myopathy or muscular dystrophy
➢ Intra-operative ventilation
➢ Correct respiratory acidosis, providing goals of
lung- protective ventilation are met
➢ Match metabolic demand
➢ Rest respiratory muscles

36. Indications for Mechanical
Ventilation
➢ Cardiac or respiratory arrest
➢ Tachypnea or bradypnea with respiratory fatigue or
impending arrest
➢ Acute respiratory acidosis
➢ Refractory hypoxemia (when the PaO2 could not be
maintained above 60 mm Hg with inspired O2 fraction
(FIO2)>1.0)
➢ Inability to protect the airway associated with depressed levels
of consciousness

37. Indications for Mechanical
Ventilation
❑ Shock associated with excessive respiratory work
❑ Inability to clear secretions with impaired gas exchange
or excessive respiratory work
❑ Newly diagnosed neuromuscular disease with a vital
capacity <10-15 mL/kg
❑ Short term adjunct in management of acutely increased
intracranial pressure (ICP)

38. MechanicalVentilation
Correct Hypoxemia Optimize cardiac function
Correct respiratory
acidosis*
RR, TV
Meet increased
metabolic
demand
*Avoid ventilator induced lung injury and dynamic hyperinflation
Hyperventilation may be used as a short
term adjunct to treat acutely elevated ICP
Enhance Ventilation *
Assistance for neural and/or
muscle dysfunction

39. Invasive vs. Non-invasive
Ventilation
n Consider non-invasive ventilation particularly
in the following settings:
• COPD exacerbation
• Cardiogenic pulmonary edema
• Obesity hypoventilation syndrome
• Noninvasive ventilation maybe tried in selected
patients with asthma or non-cardiogenic
hypoxemic respiratory failure

40. Permissive Hypercapnia
n Ventilation strategy that allows PaCO2 to rise by
accepting a lower alveolar minute ventilation to
avoid specific risks:
❖ Dynamic hyperinflation (“auto-peep”)
and barotrauma in patients with asthma
❖ Ventilator-associated lung injury, in patients with,
or at risk for, ALI and ARDS
n Contraindicated in patients with increased
intracranial pressure such as head trauma

41. Management
of ARF
5 -PEEP (positive End-
Expiratory pressure
• Increase intrathoracic pressure
• Keeps the alveoli open
• Decrease shunting
• Improve gas exchange
Used with mechanical ventilation
• ARDS
• Pneumonias
Hypoxemic RF (type 1)

42. Management of ARF
6 - Noninvasive Ventilatory
support (IPPV)
• Mild to moderate RF
• Patient should have
• Intact airway,
• Alert, normal airway protective reflexes
• Nasal or full-face mask
• Improve oxygenation,
• Reduce work of breathing
• Increase cardiac output
• AECOPD, asthma, CHF

43. Management
of ARF
7 - Treatment of
the underlying
causes
• Ibratropium bromide
• Inhibit vagal tone
• Relax smooth ms
Anticholinergics
(COPD,BA)
• Improve diaphragmatic
contraction
• Relax smooth ms
Theophylline
(COPD, BA)
• Frusemide, Metalzone
Diuretics
(pulmonary
edema)

44. Management of ARF
7 - Treatment of the underlying causes
Methyl prednisone (COPD, BA, acute esinophilic pn)
• Reverse bronchospasm, inflammation
Fluids and electrolytes
• Maintain fluid balance and avoid fluid overload
IV nutritional support
• To restore strength, loss of ms mass
• Fat, carbohydrate, protein

45. Management of ARF
• 7 - Treatment of the
underlying causes
• Physiotherapy
❖Chest percussion to loosen
secretion
❖Suction of airways
❖ Help to drain secretion
❖Maintain alveolar inflation
❖Prevent atelectasis, help
lung expansion

46. Management of ARF
8 - Weaning from mechanical ventilation
Stable underlying respiratory status
❖Adequate oxygenation
❖Intact respiratory drive
❖Stable cardiovascular status
❖Patient is a wake, has good nutrition,
able to cough and breath deeply

47. Complications of
ARF
Infections
Nosocomial infection
Pneumonia, UTI,
catheter related sepsis
Renal
ARF (hypoperfusion,
nephrotoxic drugs)
Poor prognosis
Nutritional
Malnutrition,
diarrhea hypoglycemia,
electrolyte disturbances
Pulmonary
• Pulmonary embolism
• barotrauma
• pulmonary fibrosis (ARDS)
• Nosocomial pneumonia
Cardiovascular
• Hypotension, ↓COP
• Arrhythmia
• MI, pericarditis
GIT
• Stress ulcer, ileus, diarrhea, hemorrhage

48. Management of
ARF
7 - Treatment of the underlying
causes
• After correction of hypoxemia,
hemodynamic stability
• Antibiotics
• Pneumonia
• Infection
• Bronchodilators (COPD, BA)
• Salbutamol
• reduce bronchospasm
• airway resistance

49. Prognosis of ARF
Mortality rate for ARDS → 40%
• Younger patient <60 has better survival rate
• 75% of patient survive ARDS have impairment of
pulmonary function one or more years after recovery
Mortality rate for COPD →10%
• Mortality rate increase in the presence of hepatic,
cardiovascular, renal, and neurological disease

50. So in
conclusion
I Have discussed respiratory failure
and bored you
ABG A must in treatment
NIV is sufficient in most of the cases
In medicine , always there is change
todays findings may be obsolete
tomorrow.
Read ,learn, and practice

51. Thank you Ladies & Gentlemen for
your kind attention