Kingdom of Saudi
     Arabia
king Fahd Hospital
      Jeddah
 Intensive Care Unit

                       1
Mechanical
    ventilation

  Dr.Wail Bajhmoom

15.3.2005 A.D   5.2.1425A.H

                              2
•Background.
•Definitions.
•Classifications.
•Indications.


                    3
•Physiologic aspects.
•Ventilator mode.
•Complications.
•Weaning.

                        4
Background.
• 1929 was one of the first
  negative-pressure
  ventilators widely used for
  mechanical ventilation. This
 ...
• known as the iron lung, this
  device used negative
  pressure to cause a drop in
  the intrapulmonary pressure
  and to...
• In the 1950s, the intensive
  use of mechanical ventilation
  started during the polio
  epidemic in Scandinavia and
  t...
• ventilating patients with
  polio and respiratory
  paralysis by manually forcing
  50% oxygen through a
  tracheostomy ...
Definition   :

  Ventilators are: specially
   designed pumps that can
   support the ventilator
   function of the
   re...
They improve oxygenation
 through application of high
 oxygen content gas and
 positive pressure.



                     ...
Classifications.
• Modern ventilators are
  classified by the method of
  cycling from the inspiratory
  phase to the expi...
Classifications.
• The signal to terminate the
  machine's inspiratory activity
  can be:
• (volume-cycled ventilator),
• ...
volume-cycled ventilator
• a preset volume
• is the most common form of
  ventilator cycling used in
  adult medicine
• be...
Indications:
• Mechanical ventilation should
  not be initiated without
  thoughtful consideration
  because intubation an...
Indications:
• Many factors are considered
  in the decision to institute
  mechanical ventilation.
• Respiratory failure ...
Indications:
• Apnea with respiratory arrest
• Acute lung injury
     -R.R more than 30 BPM
    -Minute   ventilation>10 L...
• Chronic obstructive lung disease

    - Blood gases - Persistent
 hypoxemia, PCO2 (acutely) greater than
 50 mm Hg with ...
• Neuromuscular disease

• Clinical judgment should be used ;
An increasing severity of the illness is
  a sign that shoul...
Physiologic aspects.
• Most modern mechanical ventilators
  function by providing warmed and
  humidified gas to the airwa...
• replacing the muscles of the
  diaphragm and chest wall.
  Expiration is passive, driven by
  the recoil of the lungs an...
Ventilator mode:
• This setting specifies the
  manner in which ventilator
  breaths are triggered,
  cycled, and limited ...
• Assist Control Mode Ventilation
  (ACMV)
An inspiratory cycle is initiated
  either by the patient's inspiratory
  effor...
• Every breath delivered consists of
  the operator-specified tidal
  volume.
• ACMV is the recommended mode for
  initiat...
• ACMV is not effective for
  weaning patients from
  mechanical ventilation because
  it provides full ventilator
  assis...
• Synchronized Intermittent
  Mandatory Ventilation
 (SIMV)
The major difference between SIMV
 and ACMV is that in the for...
• If the patient fails to initiate
  a breath, the ventilator
  delivers a fixed-tidal-volume
  breath and resets the inte...
• SIMV is a useful mode of
  ventilation for both supporting and
  weaning intubated patients
• SIMV may be difficult to u...
• Continuous Positive Airway Pressure
 (CPAP)
.This is not a true support-mode of
  ventilation, since all ventilation
  o...
• CPAP is used to assess extubation
  potential in patients who have been
  effectively weaned and are
  requiring little ...
• Pressure-Control Ventilation
  (PCV)
This form of ventilation is time triggered,
 time cycled, and pressure limited. Dur...
• PCV is the preferred mode of
  ventilation for patients with
  documented barotrauma, since
  airway pressures can be
  ...
• Pressure-Support Ventilation
 (PSV)
This form of ventilation is patient
 triggered, flow cycled, and
 pressure limited; ...
PSV is well tolerated by most
 patients who are being weaned:
 PSV parameters can be set in such
 a way as to provide full...
COMPLICATIONS:
• Endotracheal intubation and positive-
  pressure mechanical ventilation have
  direct and indirect effect...
• barotrauma, nosocomial pneumonia,
  oxygen toxicity, tracheal stenosis,
  and deconditioning of respiratory
  muscles.
•...
• Patients intubated for longer than 72 h
  are at high risk for nosocomial
  pneumonia as a result of aspiration from
  t...
• Oxygen toxicity is a potential
  complication when an FIO2 of 0.6 or
  greater is required for more than 72 h.

•    Hyp...
• Gastrointestinal effects of
  positive-pressure ventilation include
  stress ulceration and mild to
  moderate cholestas...
Weaning.
• Many approaches to weaning patients
  from ventilator support have been
  advocated.

• T-piece and CPAP weanin...
Weaning.
• SIMV and PSV are best for
  patients who have been intubated
  for extended periods and require
  gradual respi...
ThANK YOU

            41
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Mehanical Ventilation Dr wail bajhmoum

  1. 1. Kingdom of Saudi Arabia king Fahd Hospital Jeddah Intensive Care Unit 1
  2. 2. Mechanical ventilation Dr.Wail Bajhmoom 15.3.2005 A.D 5.2.1425A.H 2
  3. 3. •Background. •Definitions. •Classifications. •Indications. 3
  4. 4. •Physiologic aspects. •Ventilator mode. •Complications. •Weaning. 4
  5. 5. Background. • 1929 was one of the first negative-pressure ventilators widely used for mechanical ventilation. This metal cylinder completely covered the patient up to the neck. 5
  6. 6. • known as the iron lung, this device used negative pressure to cause a drop in the intrapulmonary pressure and to allow ambient airflow into the patient's lungs. 6
  7. 7. • In the 1950s, the intensive use of mechanical ventilation started during the polio epidemic in Scandinavia and the United States. In Copenhagen, Denmark. 7
  8. 8. • ventilating patients with polio and respiratory paralysis by manually forcing 50% oxygen through a tracheostomy reduced the mortality rate from 80% to 25%. 8
  9. 9. Definition : Ventilators are: specially designed pumps that can support the ventilator function of the respiratory system. 9
  10. 10. They improve oxygenation through application of high oxygen content gas and positive pressure. 10
  11. 11. Classifications. • Modern ventilators are classified by the method of cycling from the inspiratory phase to the expiratory phase. 11
  12. 12. Classifications. • The signal to terminate the machine's inspiratory activity can be: • (volume-cycled ventilator), • (pressure-cycled ventilator), • (time-cycled ventilator). 12
  13. 13. volume-cycled ventilator • a preset volume • is the most common form of ventilator cycling used in adult medicine • because it provides a consistent breath-to-breath tidal volume. 13
  14. 14. Indications: • Mechanical ventilation should not be initiated without thoughtful consideration because intubation and positive-pressure ventilation could have potentially harmful effects. 14
  15. 15. Indications: • Many factors are considered in the decision to institute mechanical ventilation. • Respiratory failure is the primary indication 15
  16. 16. Indications: • Apnea with respiratory arrest • Acute lung injury -R.R more than 30 BPM -Minute ventilation>10 L/min -PaO2, with supplemental (FIO2) less than 55 mm Hg 16
  17. 17. • Chronic obstructive lung disease - Blood gases - Persistent hypoxemia, PCO2 (acutely) greater than 50 mm Hg with pH less than 7.25 _ Clinical deterioration Respiratory muscle fatigue, coma, hypotension, or tachypnea or bradypnea 17
  18. 18. • Neuromuscular disease • Clinical judgment should be used ; An increasing severity of the illness is a sign that should alert the clinician to consider instituting mechanical ventilation. 18
  19. 19. Physiologic aspects. • Most modern mechanical ventilators function by providing warmed and humidified gas to the airway opening in conformance with various specific volume, pressure, and time patterns. The ventilator serves as the energy source for inspiration, 19
  20. 20. • replacing the muscles of the diaphragm and chest wall. Expiration is passive, driven by the recoil of the lungs and chest wall 20
  21. 21. Ventilator mode: • This setting specifies the manner in which ventilator breaths are triggered, cycled, and limited . 21
  22. 22. • Assist Control Mode Ventilation (ACMV) An inspiratory cycle is initiated either by the patient's inspiratory effort or, if no patient effort is detected within a specified time window, 22
  23. 23. • Every breath delivered consists of the operator-specified tidal volume. • ACMV is the recommended mode for initiation of mechanical ventilation because it ensures a backup minute ventilation in the absence of an intact respiratory drive. 23
  24. 24. • ACMV is not effective for weaning patients from mechanical ventilation because it provides full ventilator assistance on each patient- initiated breath. 24
  25. 25. • Synchronized Intermittent Mandatory Ventilation (SIMV) The major difference between SIMV and ACMV is that in the former the patient is allowed to breathe spontaneously, i.e., without ventilator assist 25
  26. 26. • If the patient fails to initiate a breath, the ventilator delivers a fixed-tidal-volume breath and resets the internal timer for the next inspiratory cycle. 26
  27. 27. • SIMV is a useful mode of ventilation for both supporting and weaning intubated patients • SIMV may be difficult to use in patients with tachypnea because they may attempt to exhale during the ventilator-programmed inspiratory cycle. 27
  28. 28. • Continuous Positive Airway Pressure (CPAP) .This is not a true support-mode of ventilation, since all ventilation occurs through the patient's spontaneous efforts. 28
  29. 29. • CPAP is used to assess extubation potential in patients who have been effectively weaned and are requiring little ventilator support 29
  30. 30. • Pressure-Control Ventilation (PCV) This form of ventilation is time triggered, time cycled, and pressure limited. During the inspiratory phase, a given pressure is imposed at the airway opening, and the pressure remains at this user- specified level throughout inspiration 30
  31. 31. • PCV is the preferred mode of ventilation for patients with documented barotrauma, since airway pressures can be limited, • 31
  32. 32. • Pressure-Support Ventilation (PSV) This form of ventilation is patient triggered, flow cycled, and pressure limited; it is specifically designed for use in the weaning process. 32
  33. 33. PSV is well tolerated by most patients who are being weaned: PSV parameters can be set in such a way as to provide full or nearly full ventilatory support and can be withdrawn slowly over a period of days in a systematic fashion to gradually load the respiratory muscles. 33
  34. 34. COMPLICATIONS: • Endotracheal intubation and positive- pressure mechanical ventilation have direct and indirect effects on several organ systems • Including: -the lung and upper airways, the cardiovascular system, and the gastrointestinal system. 34
  35. 35. • barotrauma, nosocomial pneumonia, oxygen toxicity, tracheal stenosis, and deconditioning of respiratory muscles. • emphysema, pneumomediastinum, subcutaneous emphysema, or pneumothorax. 35
  36. 36. • Patients intubated for longer than 72 h are at high risk for nosocomial pneumonia as a result of aspiration from the upper airways via small leaks around the endotracheal tube cuff • enteric gram-negative rods, Staphylococcus aureus, and anaerobic bacteria. 36
  37. 37. • Oxygen toxicity is a potential complication when an FIO2 of 0.6 or greater is required for more than 72 h. • Hypotension resulting from elevated intrathoracic pressures with decreased venous return 37
  38. 38. • Gastrointestinal effects of positive-pressure ventilation include stress ulceration and mild to moderate cholestasis. It is common practice to provide prophylaxis with H2-receptor antagonists or sucralfate for stress-related ulcers. 38
  39. 39. Weaning. • Many approaches to weaning patients from ventilator support have been advocated. • T-piece and CPAP weaning are best tolerated by patients who have undergone mechanical ventilation for brief periods 39
  40. 40. Weaning. • SIMV and PSV are best for patients who have been intubated for extended periods and require gradual respiratory-muscle reconditioning. 40
  41. 41. ThANK YOU 41

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