By Dr.SoliMaN ELKADY I.C.U ReSiDeNt

1. Respiratory Failure

2. By
Dr.SoliMaN ELKADY
I.C.U ReSiDeNt

3. Introduction
Most common reason for admission to ICU is to
protect airway and ventilator care to critically
ill patients

4. Primary functions of lung and thorax is to oxygenate
arterial blood and to eliminate
CO2.

5. Dysfunction may occur in
oxygenation (intrapulmonary gas
exchange)
or in ventilation (the movement of
gases between the environment and the
lungs)

6. 0VERVIEW: RESPIRATORY SYSTEM
ORGANS

7. Gas Exchange Unit

8. Respiratory system includes:
CNS (medulla)
Peripheral nervous system (phrenic nerve)
Respiratory muscles
Chest wall
Lung
Upper airway
Bronchial tree
Alveoli
Pulmonary vasculature

9. WE SHOULD DIFFRENTIAT BETWEEN
RESPIRATORY INSUFFICIENCY AND
RESPIRATORY FAILURE

10. Respiratory insufficiency
The condition in which the lungs can not take in
sufficient oxygen or expel sufficient carbon
dioxide to meet the needs of the cells of the
body..

11. Respiratory failure
Respiratory failure is a syndrome in which the respiratory
system fails in one or both of its gas exchange functions:
oxygenation and carbon dioxide elimination.

12. In practice :
respiratory failure defiend as Pao2 value less
than 60 mm Hg or PaCO2 value more than
50 mm Hg.

13. classification
（1）according to PaCO2
■ hypoxemic (Group Ⅰ) respiratory failure
PaO2 of less than 60 mm Hg with a normal or low PaCO2.
Cause of: Edema, Vascular disease, Chest Wall.
■ hypercapnic (Group Ⅱ ) respiratory failure
PaO2 low 60 mm Hg and PaCO2 of more than 50 mm Hg.
Cause of: Airway obstruction, Neuromuscular disease.

14. （2）according to pathogenic mechanism
■ ventilatory disorders
1-obstructive ventilatory disorders
asthma, emphysema, chronic bronchitis, and bronchiectasis
2-restrictive ventilatory disorders
deformity of thorax , fracture of several ribs, tension pneumothorax
diffuse interstitial fibrosis
■ gas exchange disorders
1-diffusion disorders
2-ventilation-perfusion mismatching

15. （3）according to primary site
■ central respiratory failure
■ peripheral respiratory failure
airway obstruction between the glottis and the carina
■Obstruction is located in the
airway outside the thorax：
inspiratory dysnea
■Obstruction is located in the
airway inside the thorax：
expiratory dysnea
expire inspire

16. ■ peripheral respiratory failure
Peripheral airway obstruction may be caused by: specific
chemical mediators (such as histamine, leukotrienes,
prostaglandins ), other substances released during inflammatory
and allergic responses
（4）according to duration
■ acute respiratory failure minute to hours
■ chronic respiratory failure several dayes or longer

17. clinical

18. The most important practical classification

19. HYPOXIC RESPIRATORY FAILURE (TYPE 1)
Most common form of respiratory failure
Lung disease is severe to interfere with pulmonary O2
exchange, but over all ventilation is maintained

20. Causes of Hypoxic Respiratory failure
1- FiO2 high altitude
2- Ventilation-perfusion (V/Q) mismatch
3- Shunt
4- Diffusion limitation
5- Alveolar hypoventilation

21. V/Q mismatch
Normal ventilation of alveoli is
comparable to amount of
perfusion
Normal V/Q ratio is 0.8 (more
perfusion than ventilation)
V/Q Mismatch :
Inadequate ventilation
Poor perfusion
VA Q VA/ Q
Top 1.2L/min 0.4L/min 3.0
Middle 1.8L/min 2.0L/min 0.9
Bottom 2.1L/min 3.4L/min 0.6

22. Causes
COPD
Pneumonia
Asthma
Atelectasis
Pulmonary embolus

23. Shunt An extreme V/Q mismatch
((Perfusion without ventilation))
Shunting is the most common cause for hypoxaemic respiratory failure
in ICU patients.
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%

24. Causes
I- Anatomic shunt
Blood passes through parts of respiratory system that
receives no ventilation
II- Intracardiac
Right to left shunt
Fallot’s tetralogy
Eisenmenger’s syndrome
III- IntraPulmonary
A/V malformation
Pneumonia
Pulmonary edema
Atelectasis/collapse
Pulmonary Hge
Pulmonary contusion

25. Diffusion limitation
Distance between alveoli and pulmonary capillary is
one- two cells thick
With diffusion abnormalities:
there is an increased distance
between alveoli and pulmonary capillary.
causes
A.R.D.S
Sever emphysema
Recurrent pulmonary emboli
Pulmonary fibrosis

26. Alveolar hypoventilation
Is a generalized decrease in ventilation of lungs
and resultant buildup of CO2
Causes
Restrictive lung disease
CNS disease
Chest wall dysfunction
Neuromuscular disease

27. Hypercapnic Respiratory Failure (Type II)
This occurs in patients with chronic CO2 retention who worsen and have
rising CO2 and low pH.
Mechanism: respiratory muscle fatigue

28. Causes of Hypercapnic Respiratory failure
Respiratory centre (medulla) dysfunction
Drug over dose,
CVA
hypothyroidism
Neuromuscular disease
Guillain-Barre, Myasthenia Gravis, polio, spinal
injuries
Chest wall/Pleural diseases
kyphoscoliosis, pneumothorax, massive pleural
effusion
Upper airways obstruction
tumor, foreign body, laryngeal edema
Peripheral airway disorder
asthma, COPD

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

30. Effects of respiratory failure
1- Acid-base disturbances & disorders of electrolyte balance
2- Alteration of the respiratory system
peripheral chemoreceptor
■ PaO2↓ ＜60mmHg respiratory center(+) respiratory movement↑
＜30mmHg respiratory center (-) respiratory movement ↓
■ PaCO2↑ central chemoreceptor
＜80mmHg respiratory center (+) respiratory movement↑
＞80mmHg respiratory center (-) respiratory movement ↓

31. 3. Alteration of the cardiovascular system
■ compensatory reaction
PaO2<60 mmHg，PaCO2 increase cardiovascular center(+)
increase in cardiac output : increase in stroke volume and heart rate
redistribution of blood flow
■ injurious changes
PaO2< 40 mmHg，PaCO2> 80 mmHg cardiovascular center(-)
rate slow, decreased blood pressure
cardiac output decrease
pulmonary hypertension

32. 4. Alteration of the nervous system
(1) Hypoxia: the nervous system is very sensible to oxygen lack.
< 40~50 mmHg, serious but reversible deterioration in cerebral function
( orientation, arithmetic tasks, memory) occurs, and restlessness and
confusion are common.
< 30 mmHg, loss of consciousness results.
< 20 mmHg, irreversible damage of neural cells.
(2) Hypercapnia: CO2 nacosis.
condition of confusion, tremors, convulsions, and possible coma that
may occur if blood levels of carbon dioxide increase to 80mm Hg or higher

33. 5. Alteration of the renal function
6. Alteration of the digestive system

34. Respiratory Failure Symptoms
When compensatory mechanisms fail, respiratory failure occurs
CNS:
Headache
Visual Disturbances
Anxiety
Confusion
Memory Loss
Weakness
Decreased Functional Performance

35. Pulmonary:
Cough
Chest pains
Sputum production
Stridor
Dyspnea
Cardiac:
Orthopnea
Chest pain
Other:
Fever, Abdominal pain, Anemia, Bleeding

36. Clinical diagnosis
Respiratory compensation
Tachypnoea RR > 35 Breath /min
Accessory muscl
Retraction intercostal ms
Nasal flaring
Sympathetic stimulation
HR
BP Tissue hypoxia
sweating
Altered mental state
Haemoglobin desaturation HR and BP (late)
Low spo2
Cyanosis (late)

37. Causes of error Pulse oximetry
Poor peripheral perfusion
Dark skin
False nails or nail PAINTING
Bright ambient light
Poorly adherent probe
Excessive motion
Carboxyhaemoglobin or
methaemoglobin

38. ASSESSMENT OF PATIENT
1-Careful history
2-Physical Examination
3-Investigations
I- ABG analysis :
PaO2
PaCO2
pH
Alveolar-Arterial PO2 Gradient
P(A-a)02 = (PiO2 - PaCO2) – PaO2
R

39. where PiO2 = partial pressure of inspired air, R = 0.8
i.e, at sea level, breathing air;
PAO2 = 20 - PaCO2/0.8
A-a Gradient = 20 - PaCO2/0.8 -PaO2
Normal P(A-a)O2 gradient: 5-10 mm of Hg
A sensitive indicator of disturbance of gas exchange.
Useful in differentiating extrapulmonary and pulmonary causes of
resp. failure.

40. II-Chest x-ray
III-CBC,
IV- sputum/blood cultures,
V- Serum electrolytes
VI- ECG
VII- Urinalysis
VIII-V/Q lung scan
IX- Pulmonary artery catheter (severe cases)

41. Management of Respiratory Failure Principles
Hypoxemia may cause death in RF
Primary objective is to reverse and prevent
hypoxemia
Secondary objective is to control PaCO2 and
respiratory acidosis
Treatment of underlying disease
Patient’s CNS and CVS must be monitored
and treated

42. Management
Correction of hypoxemia
Supplemental O2 therapy essential
Titration based on SaO2, PaO2 levels and PaCO2
Goal is to prevent tissue hypoxia
Tissue hypoxia occurs (normal Hb & C.O.)
- venous PaO2 < 20 mmHg or SaO2 < 40%
- arterial PaO2 < 38 mmHg or SaO2 < 70%
Increase arterial PaO2 > 60 mmHg(SaO2 > 90%) or venous SaO2 > 60%
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

43. Mobilization of secretions
Encourage pt 4 Effective coughing
Positioning
Semisetting

44. Hydration and humidification
Chest Physiotherapy
Chest percussion to loosen
secretion
Airway suctioning

45. Drug Therapy
Relief of bronchospasm
Bronchodilators
Reduction of airway inflammation
Corticosteroids
Reduction of pulmonary congestion
IV diuretics
Treatment of pulmonary infections
IV antibiotics
Nutritional Therapy
Maintain protein and energy stores
Enteral or parenteral nutrition Supplements

46. Noninvasive Ventilatory support (IPPV)
BiPAP CPAP
Mild to moderate RF
NIPPV INDICATED In
Acute exacerbation of COPD WITH
Respiratory acidosis pH 7.25 Or less
Cardiogenic pulmonary edema
Asthma
Type II R.F secondary to chest wall deformity
or neuro muscular diseases
Weaning off mechanical ventilation

47. Benefits NIPPV
of
Improved alveolar ventilation
Reduced work of breathing
Rest of the respiratory musculature
Increased intrathoracic pressure
decreases preload and
afterload

48. should not be considered for NPPV?
Contraindications
Cardiac or respiratory arrest
Nonrespiratory organ failure
Hemodynamic instability
Severe encephalopathy
Severe UGI bleed
Facial or neurosurgery, trauma
Upper airway obstruction
Inability to cooperate or protect airway
High risk for aspiration

49. Mechanical ventilation
Indications
PaO2< 55 mm Hg or PaCO2 > 60 mm Hg
despite 100% oxygen therapy.
Deteriorating respiratory status despite
oxygen and Nebulization therapy
Anxious, with deteriorating mental status.
Respiratory fatigue: for relief of metabolic
stress of the work of breathing

50. Mechanical Ventilation: Strategies
1-SIMV, A/C with PEEP
PEEP (positive End-Expiratory pressure)
Increase intrathoracic pressure
Keeps the alveoli open
Decrease shunting
Improve gas exchange

51. 2-High frequency ventilation (HFV)
Very small tidal volumes are used
(<1ml/kg), very rapid rates and lower mean
airway pressures are used
3-Lung Recruitment
To open the collapsed alveoli
A sustained inflation of the lungs to higher
airway pressure and volumes
4-Permissive Hypercapnia
Allows the PaCO2 to rise into the 60-70 mm of
Hg range, as long as the patient is adequately
oxygenated (SaO2> 92%), and able to tolerate
the acidosis.
This strategy is used to limit the amount of
barotrauma and volutrauma to the patient

52. 5-Prone positioning
Improve oxygenation in about 2/3 of all
treated patients
No improvement on survival, time on
ventilation, or time in ICU
Might be useful to treat refractory
hypoxemia
Routine use is not recommended

53. Respiratory failure common in old age due to
↓ Ventilatory capacity
Alveolar dilation
Larger air spaces
Loss of surface area
Diminished elastic recoil
Decreased respiratory muscle strength
↓ Chest wall compliance

56. Thanks for attention

59. Direct Lung Injury
Infectious pneumonia
Aspiration, chemical pneumonitis
Acute Respiratory Distress Syndrome Pulmonary contusion, penetrating lung
injury
Fat emboli
Near-drowning
Inhalation injury
Reperfusion pulmonary edema s/p lung
transplant
Indirect Lung Injury
Sepsis
Severe trauma with shock/hypoperfusion
Burns
Massive blood transfusion
Drug overdose: ASA, cocaine, opioids,
phenothiazines, TCAs.
Cardiopulmonary bypass
Acute pancreatitis