Mechanical ventilation

1. MECHANICAL
VENTILATION

2. ARTIFICIAL AIRWAYS
• Inserting a tube into the trachea, bypassing upper airway and
laryngeal structures, creates an artificial airway. The tube is
placed into the trachea via the mouth or nose past the larynx
(endotracheal [ET] intubation) or through a stoma in the neck
(tracheostomy).
• Indications for ET intubation include
(1) upper airway obstruction (e.g., secondary to burns,
tumor, bleeding)
(2) apnea
(3) high risk of aspiration
(4) ineffective clearance of secretions
(5) respiratory distress

3. ENDOTRACHEAL TUBES
• In oral intubation the ET tube is passed through
the mouth and vocal cords and into the trachea
with the aid of a laryngoscope or a bronchoscope.
• In nasal ET intubation the ET is placed blindly (i.e.,
without seeing the larynx) through the nose,
nasopharynx, and vocal cords

5. ENDOTRACHEAL INTUBATION PROCEDURE
• consent for the procedure

7. NURSING MANAGEMENT
Nursing responsibilities for the patient with an artificial
airway may include some or all of the following:
(1) maintaining correct tube placement
(2) maintaining proper cuff inflation
(3) monitoring oxygenation and ventilation
(4) maintaining tube patency
(5) assessing for complications
(6) providing oral care and maintaining skin integrity
(7) fostering comfort and communication.

8. MAINTAINING CORRECT TUBE PLACEMENT
• Maintain proper ET tube position by placing an “exit mark”
on the tube.
• Confirm that the mark remains constant while at rest and
during patient care, repositioning, and transport.
• Observe for symmetric chest wall movement and
auscultate to confirm bilateral breath sounds.
• If the tube is dislodged, maintain the airway, support
ventilation, and call for the appropriate help to
immediately reposition the tube.

9. MAINTAINING PROPER CUFF INFLATION
• The high-volume, low-pressure cuff stabilizes and
“seals” the ET tube within the trachea and prevents
escape of ventilating gases.
• Inflate the cuff with air, and measure and monitor
the cuff pressure ,because excess volume in the cuff
can damage the tracheal mucosa.
• Maintain cuff pressure at 20 to 25 cm H2O.

10. MONITORING OXYGENATION AND
VENTILATION
• Assess for signs of hypoxemia such as a change in
mental status (e.g., confusion), anxiety, dusky skin,
and dysrhythmias.
• Assess the patient’s respirations for rate, rhythm,
and use of accessory muscles.

11. MAINTAINING TUBE PATENCY
• Regularly assess the patient to determine if suctioning is needed.
Indications for suctioning include
• (1) visible secretions in the ET tube
• (2) sudden onset of respiratory distress
• (3) suspected aspiration of secretions
• (4) increase in peak airway pressures
• (5) auscultation of adventitious breath sounds over the trachea or bronchi
• (6) increase in respiratory rate or sustained coughing
• (7) sudden or gradual decrease in PaO2 or SpO2.

12. • Two recommended suctioning methods : closed-suction technique (CST) and
the open-suction technique (OST).
• The CST uses a suction catheter that is enclosed in a plastic sleeve
connected directly to the patient-ventilator circuit. With the CST,
oxygenation and ventilation are maintained during suctioning, and exposure
to the patient’s secretions is reduced.
Indication for CST
• (1) require high levels of positive end-expiratory pressure (PEEP) (greater
than 10 cm H2O)
• (2) have high levels of FIO2
• (3) have bloody or infected pulmonary secretions
• (4) require frequent suctioning
• (5) experience clinical instability with the OST

14. POTENTIAL COMPLICATIONS ASSOCIATED WITH
SUCTIONING
• Hypoxemia
• Bronchospasm
• Increased intracranial pressure
• Dysrhythmias, hypertension
• Hypotension
• Mucosal damage
• Pulmonary bleeding
• Pain
• Infection

15. PROVIDING ORAL CARE AND MAINTAINING SKIN
INTEGRITY
• Perform oral care using pediatric or adult soft toothbrushes at
least twice a day by gently brushing to clean and remove
plaque.
• Use oral swabs with a 1.5% hydrogen peroxide solution every
2-4 hr.
• Use 0.12% chlorhexidine oral rinse twice daily.
• Apply a mouth moisturizer to oral mucosa and lips with each
cleaning.
• Suction oral cavity and pharynx frequently

16. MECHANICAL VENTILATION
• Mechanical ventilation is the process by which
the fraction of inspired oxygen (FIO2) is at 21%
(room air) or greater and moved into and out
of the lungs by a mechanical ventilator.
• It is used as a means of supporting patients
until they recover the ability to breathe
independently, as a bridge to long-term
mechanical ventilation, or until a decision is
made to withdraw ventilatory support.

17. INDICATIONS FOR MECHANICAL VENTILATION
• Apnea or impending inability to breathe
• Acute respiratory failure
• Severe hypoxia
• Respiratory muscle fatigue
• COPD
• Drug overdose
• Neuromuscular disorders
• Thoracic or abdominal surgery
• Multiple trauma
• Multisystem failure
• Coma

18. TYPES
The two major types of mechanical ventilation
are:
• Negative Pressure Ventilation.
• Positive pressure ventilation

19. NEGATIVE PRESSURE VENTILATION
• Negative pressure ventilation exert a negative pressure on the
external chest wall causes the chest to be pulled outward.
• This reduces intrathoracic pressure which allows air to flow into
the lung during inspiration.
• Expiration is passive; the machine cycles off, allowing chest
retraction.
• The “iron lung” was the first form of negative pressure
ventilation.
• Used mainly in chronic respiratory failure associated with
neuromscular conditions.

21. POSITIVE PRESSURE VENTILATION
• Positive pressure ventilation (PPV) is the primary method
used with acutely ill patients.
• During inspiration the ventilator pushes air into the lungs
under positive pressure.
• Expiration occurs passively as in normal expiration.
• There are 2 modes of PPV
 PRESSURE CYCLED
 VOLUME CYCLED

22. CONT…..
Pressure- cycled modes
• Pressure Support Ventilation (PSV)
• CPAP (Continuous positive airway pressure)
• BiPAP (Bi-level positive airway pressure)
Volume-cycled modes
• Control mode
• Assist mode
• Assist/Control mode
• Intermittent Mandatory Ventilation (IMV)
• Synchronous Intermittent Mandatory Ventilation
(SIMV)

23. PRESSURE CYCLED VENTILATORS
• PCV delivers a flow of air (inspiration) until it
reaches a preset pressure , then the machine
cycles off and expiration occurs passively.

24. VOLUME CYCLED VENTILATORS
• Deliver a preset tidal volume of inspired gas. Once
this preset volume is delivered to the patient, the
ventilator cycle off and exhalation occurs passively.
TIME CYCLED VENTILATORS
• Terminate or control inspiration after a preset time

25. SETTINGS OF MECHANICAL VENTILATORS
Respiratory rate (f)
Number of breaths the ventilator delivers per minute; usual
setting is 6-20 breaths/min
Tidal volume (VT)
Volume of gas delivered to patient during each ventilator
breath; usual volume is 10-12 ml/kg
Oxygen concentration (FIO2): Fraction of inspired oxygen
delivered to patient; may be set between 21% (essentially
room air) and 100%; usually adjusted to maintain PaO2 level
>60 mm Hg or SpO2 level >90%

26. CONT…..
• Positive end- expiratory pressure (PEEP) : Positive pressure
applied at the end of expiration of ventilator breaths; usual
setting is 3-5 cm H2O
• Pressure support
Positive pressure used to augment patient's inspiratory
pressure; usual setting is 5-10 cm H2O
• Inspiratory flow rate and time
Speed with which the VT is delivered; usual setting is 40-80
L/min and time is 0.8-1.2 sec
• SENSITIVITY : Determines the amount of effort the patient
must generate to initiate a ventilator breath.

27. MODES OF MECHANICAL VENTILATION
VOLUME MODES:
Control Ventilation (CV) or Controlled Mandatory
Ventilation (CMV):
• delivers gas at a preset rate and tidal volume,
regardless of patients inspiratory efforts
• patient has no drive to breathe
• CMV is used in the patients with anesthetized or
paralyzed from a neuromuscular disease

28. ASSIST-CONTROL (AC) OR ASSISTED
MANDATORY VENTILATION (AMV)
• Sets the rate, VT, inspiratory time, PEEP and sensitivity
for the patient. Ventilator delivers a preset VT at a
preset frequency.
• When the patient initiates a spontaneous breath, a
full-volume breath is delivered.
• This mode has the advantage of allowing the patient
some control over ventilation while providing some
assistance.
• ACV is used in patients with a variety of conditions,
including neuromuscular disorders (e.g., GuillainBarré
syndrome), pulmonary edema, and acute respiratory
failure.

29. SYNCHRONIZED INTERMITTENT
MANDATORY VENTILATION (SIMV)
• Rate, VT, inspiratory time, sensitivity, and PEEP are set by the clinician.
• In between “mandatory breaths,” patients can spontaneously breathe
at their own rates and VT.
• With SIMV, the ventilator synchronizes the mandatory breaths with
the patient's own inspirations.
• It is used during continuous ventilation and during weaning from the
ventilator.
• Potential benefits of SIMV include improved patient-ventilator
synchrony, lower mean airway pressure, and prevention of muscle
atrophy as the patient takes on more of the work of breathing (WOB).
• Disadvantages : If spontaneous breathing decreases when the preset
rate is low, ventilation might not be adequately supported

30. PRESSURE MODES
• Pressure Support Ventilation (PSV)
• This mode provides an augmented inspiration to a
spontaneously breathing patient.
• With PSV the clinician selects an inspiratory pressure level,
PEEP, and sensitivity.
• When the patient initiates a breath, a high flow of gas is
delivered to the preselected pressure level and pressure is
maintained throughout inspiration. The patient
determines the parameters of VT, rate, and inspiratory
time.

31. Pressure-Controlled Inverse Ratio Ventilation (PC-IRV)
• This mode combines pressure-limited ventilation with an
inverse ratio of inspiration to expiration. The I/E ratio is the
ratio of duration of inspiration to the duration of expiration.
This value is normally a ratio of 1:2.
• With IRV the I:E ratio begins at 1:1 and may progress to 4:1.
• With IRV a prolonged positive pressure is applied, increasing
inspiration time
• The short exp time has a PEEP like effect, preventing alveolar
collapse.
• PC-IRV is indicated for patients with acute respiratory distress
syndrome (ARDS) who continue to have refractory hypoxemia
despite high levels of peep

32. OTHER VENTILATORY MANEUVERS
PEEP (Positive End-Expiratory Pressure (PEEP) :
• Positive pressure is applied to the airway during exhalation
• PEEP restores functional residual capacity (FRC) thereby
improves oxygenation and prevent alveolar collapse
throughout the resp cycle.

33. CONTINUOUS POSITIVE AIRWAY PRESSURE
Continuous positive airway pressure (CPAP)
• CPAP provides positive pressure to the airways throughout
the resp cycle, thus preventing airway pressure from falling
to zero
• Used in obstructive sleep apnea.
• CPAP can be administered noninvasively by a tight-fitting
mask or an ET or tracheal tube. CPAP increases WOB
because the patient must forcibly exhale against the CPAP
and so must be used with caution in patients with
myocardial compromise.

34. BILEVEL POSITIVE AIRWAY PRESSURE
• Bilevel positive airway pressure (BiPAP) provides two levels
of positive pressure support, higher inspiratory positive
airway pressure (IPAP) and lower expiratory positive airway
pressure (EPAP), along with oxygen.
• It is a noninvasive modality and is delivered through a tight-
fitting face mask, nasal mask, or nasal pillows.
• Indications include acute respiratory failure in patients with
COPD and heart failure, and sleep apnea.
• BiPAP may also be used after extubation to prevent
reintubation.

35. HIGH-FREQUENCY VENTILATION
• High-frequency ventilation (HFV) involves delivery of a
small tidal volume (usually 1 to 5 ml/kg of body weight) at
rapid respiratory rates (100 to 300 breaths/min) in an
effort to recruit and maintain lung volume
• HPV reduce intrapulmonary shunting and minimizing the
risk of volutrauma.
• HFV has been widely accepted in neonatal and pediatric
ICUs

36. COMPLICATIONS OF POSITIVE PRESSURE
VENTILATION
Cardiovascular System.
• With increased intrathoracic pressure, thoracic
vessels are compressed. This results in decreased
venous return to the heart, decreased preload,
decreased CO, and hypotension.

37. PULMONARY SYSTEM
Barotrauma
• Increased airway pressure readily distends the
lungs and may rupture alveoli.
• Air can escape into the pleural space from alveoli
or interstitium, accumulate, and become trapped.
Pleural pressure increases and collapses the lung,
causing pneumothorax.

38. • Pneumomediastinum usually begins with rupture
of alveoli into the lung interstitium; progressive air
movement then occurs into the mediastinum and
subcutaneous neck tissue (subcutaneous
emphysema). This is commonly followed by
pneumothorax.

39. VOLUTRAUMA
• Occurs when large tidal volumes are used to
ventilate noncompliant lungs (e.g., ARDS).
Volutrauma results in alveolar fractures and
movement of fluids and proteins into the alveolar
spaces.

40. ALVEOLAR HYPOVENTILATION
• Hypoventilation can be caused by inappropriate
ventilator settings, leakage of air from the
ventilator tubing or around the ET tube or
tracheostomy cuff, lung secretions or obstruction

41. ALVEOLAR HYPERVENTILATION.
• Respiratory alkalosis can occur if the
respiratory rate or VT is set too high
(mechanical overventilation) or if the patient
receiving assisted ventilation is
hyperventilating.

42. VENTILATOR-ASSOCIATED PNEUMONIA
• VAP is defined as a pneumonia that occurs 48
hours or more after ET intubation. VAP occurs in
9% to 27% of all intubated patients, with 50% of
the occurrences developing within the first 4 days
of mechanical ventilation.
• Organisms associated with VAP include
Escherichia coli, Klebsiella, Proteus, Streptococcus
pneumoniae, Haemophilus influenzae

43. NEUROLOGIC SYSTEM
• In patients with head injury, PPV, especially with PEEP,
can impair cerebral blood flow. This is related to
increased intrathoracic positive pressure impeding
venous drainage from the head as evidenced by jugular
venous distention.
• As a result of the impaired venous return and increase in
cerebral volume, the patient may exhibit increases in
intracranial pressure.
• Elevating the head of the bed and keeping the patient's
head in alignment may decrease the deleterious effects
of PPV on intracranial pressure.

44. GASTROINTESTINAL SYSTEM
• Patients receiving PPV are often stressed because of
serious illness, immobility, and discomforts associated
with the ventilator. Thus the ventilated patient is at risk
for developing stress ulcers and GI bleeding.
• Gastric and bowel dilation may occur as a result of gas
accumulation in the GI tract from swallowed air. The
irritation of an artificial airway may cause excessive air
swallowing and subsequent gastric dilation. Gastric or
bowel dilation may put pressure on the vena cava,
decrease CO

45. SODIUM AND WATER IMBALANCE
• Progressive fluid retention often occurs after 48 to 72
hours of PPV
• It is associated with decreased urinary output and
increased sodium retention.
• Fluid balance changes may be due to decreased CO, which
in turn results in diminished renal perfusion.
Consequently, renin release is stimulated with subsequent
production of angiotensin and aldosterone. This results in
sodium and water retention.
• There is less insensible water loss via the airway because
ventilated delivered gases are humidified with body
temperature water.

46. MUSCULOSKELETAL SYSTEM
• Maintenance of muscle strength and prevention of the
problems associated with immobility are important.
• Progressive ambulation of patients receiving long-term
PPV can be attained without interruption of mechanical
ventilation.
• Passive and active exercises, consisting of movements to
maintain muscle tone in the upper and lower extremities,
should be done in bed.

47. PSYCHOSOCIAL NEEDS
• The patient receiving mechanical ventilation may experience
physical and emotional stress.
• The patient supported by a mechanical ventilator is unable to
speak, eat, move, or breathe normally.
• Tubes and machines may cause pain, fear, and anxiety.
Ordinary activities of daily living such as eating, elimination,
and coughing are extremely complicated.
• The nurse should encourage hope and build trusting
relationships with the patient and family.

48. MACHINE DISCONNECTION OR MALFUNCTION
• Mechanical ventilators may become disconnected or
malfunction.
• When turned on and operative, alarms alert the nurse to
problems.
• Most deaths from accidental ventilator disconnection
occur while the alarm is turned off.
• Alarms can be paused during suctioning or removal from
the ventilator and should always be reactivated before
leaving the patient's bedside.

49. WEANING FROM POSITIVE PRESSURE
VENTILATION AND EXTUBATION
• The process of reducing ventilator support and resuming
spontaneous ventilation is termed weaning.
Weaning consist of three phases:
• The preweaning phase,
• The weaning process, and the
• Outcome phase.

50. PREWEANING PHASE
• The preweaning or assessment phase determines the
patient's ability to breathe spontaneously.
• Assessment in this phase depends on a combination of
respiratory and nonrespiratory factors.
• Weaning assessment parameters should include criteria to
assess muscle strength (negative inspiratory force [NIF]) and
spontaneous tidal volume [VT] , vital capacity [VC], and
spontaneous resp rate.
• In addition, the patient's lungs should be reasonably clear on
auscultation and chest x-ray.
• Nonrespiratory factors include the assessment of the patient's
neurologic status, hemodynamics, fluid and electrolytes/acid-
base balance, nutrition, and hemoglobin.

51. INDICATORS FOR WEANING
Weaning Readiness
• Patients receiving mechanical ventilation for respiratory failure
should undergo a formal assessment of weaning potential if the
following are satisfied:
• 1. Reversal of the underlying cause of respiratory failure
• 2. Adequate oxygenation:
 PaO2/FIO2 >150-200
 PEEP ≤5-8 cm H2O
 FIO2 ≤40%-50%
 pH ≥7.25

52. • 3. Hemodynamic stability:
• Absence of myocardial ischemia
• Absence of clinically significant hypotension
• 4. Patient ability to initiate an inspiratory effort

53. WEANING PHASE
• Weaning is usually carried out during the day, with the
patient ventilated at night in a rest mode. The rest mode
should be a stable, nonfatiguing, and comfortable form of
support for the patient.
• Baseline vital signs and respiratory parameters are
measured.
• During the weaning trial, the patient must be monitored
closely for noninvasive criteria that may signal intolerance
and result in cessation of the trial (e.g., tachypnea,
dyspnea, tachycardia, dysrhythmias, sustained desaturation
[SpO2 <91%], hypertension or hypotension, changes in level
of consciousness

54. OUTCOME PHASE
• The weaning outcome phase refers to the period when
weaning stops and the patient is extubated.
• The patient who is ready for extubation should receive
hyperoxygenation and suctioning (e.g., oropharynx, ET
tube).
• The patient should be instructed to take a deep breath, and
at the peak of inspiration, the cuff should be deflated and
the tube removed in one motion.
•

55. • After removal, the patient should be encouraged to deep
breathe and cough, and the pharynx should be suctioned
as needed.
• Supplemental oxygen should be applied and naso-oral
care provided.
• The nurse must carefully monitor the patient's vital signs,
respiratory status, and oxygenation immediately following
extubation, within 1 hour
• If the patient cannot tolerate extubation, immediate
reintubation may be necessary.