CARDIOPULMONARY
PHYSIOTHERAPY
Dr. Binish Adeel(PT)
Assistant Professor
MSAPT, BS PT, DPT
Dow University of Health Sciences
Institute of Physical Medicine and Rehabilitation
27/8/ 2019
MECHANICAL
VENTILATION
Objectives
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Introduction
Indications
Airway
Principles
Benefits
Complications
Settings
Modes
Positive end‐expiratory pressure
High‐frequency ventilation
Weaning and extubation
INTRODUCTION
▪ Intermittent positive pressure ventilation (IPPV) augments or replaces the function of
the inspiratory muscles by delivering gas under positive pressure to the lungs.
▪ This substitutes for the respiratory pump but is not necessarily beneficial for lung
tissue, which is vulnerable to the shear forces of repetitive opening of alveoli.
▪ There is a narrow range of pressures and volumes within which the lungs are safe
from either over distension or atelectasis
INDICATIONS
▪ unable to ventilate adequately, oxygenate adequately or both. EG:
respiratory depression due to post‐anaesthesia or drug overdose,
inspiratory muscle fatigue due to exacerbation of COPD, inspiratory
muscle weakness due to neurological impairment, or severe hypoxaemia
due to lung parenchymal disease.
▪ Patients who are able to breathe adequately but for whom this is
considered inadvisable, e.g. those with acute head injury.
▪ Patients who require intubation for airway protection or to overcome
upper airway obstruction. They require some ventilatory support to
compensate for the work of breathing (WOB) through the tubing.
INDICATIONS
▪ Arterial Pao2 < 55‐60 mm Hg (on supplemental oxygen or CPAP)
▪ Arterial Paco2 > 50 mm Hg (absence of chronic disease) and pH
< 7.32
▪ Evidence of increased work of breathing = RR > 35/min,
INDICATIONS
▪ VT < 5 mL/kg
▪ Retractions/nasal flaring
▪ Paradoxical/divergent chest motion
▪ Post operatively
INDICATIONS
▪ Respiratory Arrest
▪ Acute ventilator failure (e.g. rising PaCO2 with acidosis.
▪ Respiratory muscle dysfunction, excessive ventilatory load,
altered central ventilatory drive)
▪ Acute exacerbation of COPD
▪ Impending respiratory failure
▪ Severe oxygenation deficit
▪ Acute head injury
▪ To protect airway
▪ To overcome upper airway obstruction
INTUBTION/ INDUCTION
Intubation
▪ Insertion of ETT
▪ Patient connect to ventilator through
ETT (
endotracheal tube) and tracheostomy tube OR nasal tubes.
▪ Average internal diameter sizes are 8 mm for oral and 7 mm
for nasal tubes.
Endotracheal tube
CUFF
▪ A cuff (prevents escape of ventilating gas past the tracheal tube and
inhibits large volume aspiration).
▪ Approximately 0.5 inches from the end of an endotracheal or tracheal
tube is a cuff (balloon).
▪ (1) ensure that all of the supplemental oxygen being delivered by the
ventilator via the artificial airway enters the lungs
▪ (2) help hold the artificial airway in place. Cuff inflation pressure
should be adequate to ensure that no air is leaking around the tube;
however, cuff pressures should not exceed 20 mm Hg. High cuff
pressures have been linked to tracheal damage and scarring, which
can cause tracheal stenosis.
Complication for ETT
intubation
▪ Trauma to lips, teeth, tongue and nose
▪ Hypertension, tachycardia, bradycardia and arrhythmia
▪ Raised intracranial pressure
▪ Laryngeal trauma and Laryngospasm
▪ Bronchospasm
▪ Cord avulsions, fractures and dislocation of arytenoids
▪ Airway perforation Nasal, retropharyngeal, pharyngeal, uvular,
laryngeal, tracheal, esophageal and bronchial trauma
▪ Esophageal intubation
▪ Bronchial intubation
▪ Disrupted communication
▪ Swallowing difficulty
▪ Chest infection
▪ Discomfort,gagging,over salivation
▪ Sore throat
▪ Laryngeal edema
▪ Hoarseness
▪ Nerve injury
▪ Superficial laryngeal ulcers Laryngeal
granuloma
▪ Glottis and subglottic granulation tissue
▪ Vocal cord paralysis
▪ Tracheal stenosis
▪ Tracheo‐oesophageal fistula
PARAMETERS/SETTINGS
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Ventilator mode
Respira tory rate
Tidal volume or pressure settings
Inspira tory flow
I:E ratio
PEEP
FiO2
Inspira tory trigger
Respiratory Rate
▪ A respiratory rate (RR) of 10‐15 breaths per minute
▪ High respiratory rates allow less time for exhalation, cause
air trapping in patients with obstructive airway disease.
Tidal Volume
▪ 5‐8 mL/kg of body weight
▪ lowest values recommended in the presence of obstructive
airway disease and ARDS.
Inspiratory flow
▪ Varies with the Vt, I:E and RR
▪ Normally about 60 l/min
▪ Can be majored to 100‐ 120 l/min
Inspiratory/Expiratory
Ratio:
▪ Normal (I/E) ratio is 1:2.
▪ Inverse ratio ventilation(4:1) used in hypoxemic
patients to recruit alveoli
Inspiratory pause
▪ End inspiratory hold enhance gas distribution by allowing
time for recruitment of poor ventilated alveoli
PEEP:
▪ Applying physiologic PEEP of 3‐5 cm H2 O is common to
prevent decreases in functional residual capacity in
those with normal lungs.
▪ CAN GO UPTO 20 cm H2 O
Inspiratory Trigger
▪ Normally set automatically
▪ 2 modes:
▪ Airway pressure
▪ Flow triggering
FiO2(fraction of
inspired oxygen)
▪ Initial FiO2 set at 1.0, and then reduce
▪ Adjusted according to pao2
Two Ways to Achieve
Continuous Ventilation
▪ Negative pressure ventilation
▪ Positive pressure ventilation
Spontaneous Breathing
Positive Pressure Breath
Cycling
Cycling refers to how the ventilator ends
the inspiratory phase of the breath
Cycling Mechanisms
▪ Volume cycling – inspiration ends when a preset tidal
volume is delivered
▪ Pressure cycling – inspiration ends when a preset pressure is
reached on the airway
▪ Time cycling – inspiration ends when a preset inspiratory
time has elapsed
▪ Flow cycling – inspiration ends when a preset flow has been
reached
Triggering
The mechanism that starts the inspiratory phase
Trigger Mechanisms
▪ Pressure triggered – a drop in airway pressure triggers the
ventilator
▪ Flow triggered – a constant (bias) flow of gas passes through the
ventilator circuit. When the patient starts to inhale the
ventilator detects the drop in bias flow and triggers
▪ Types of triggered breaths: patient = assisted; ventilator =
controlled.
MODES
Positive pressure
ventilation
Ventilation modes can be divided into two groups:
▪ volume‐controlled modes
▪ pressure‐controlled modes
volume controlled
▪ Volume constant: Attempts to achieve preset Volume
▪ Peak airway pressure: Variable.
▪ Determined by changes in airway resistance, lung
compliance, or extra pulmonary pressure level.
▪ Volume control (or volume‐limited ventilation) delivers a
specific minute volume at a constant flowrate
▪ using preset variables such as
▪ respiratory rate (RR), tidal volume (VT) and inspiratory
:expiratory (I:E) ratio.
▪ Airway pressure rises slowly during inspiration to a peak
value that varies with airway resistance and lung
compliance. A pressure limit is set for safety.
▪ Volume control is commonly used for adults for three
reasons:
▪ • It can be relied on to deliver a consistent minute volume
regardless of airway resistance and lung compliance.
▪ • It maintains steady PaC02 levels when this is imperative, e
.g. In acute head‐injured patients.
▪ Inspiratory pressure increases gradually and may cause
lesser shear forces on the alveoli
Pressure controlled
▪ Volume variable: Attempts to achieve preset pressures.
▪ Peak airway pressures: Fixed
▪ Pressure control (or pressure‐limited ventilation) delivers a
preset pressure during inspiration, resulting in a variable VT
that depends on the preset pressure, airway resistance,
lung compliance, patient effort and inspiratory time.
▪ Pressure control is usually considered to be safer for
patients with stiff lungs (indicated by peak airway
pressure above 35 cmH20 on volume control),
especially for those with ARDS, for whom it reduces
the work of breathing .
▪ For babies, it limits alveolar pressures and may
reduce the risk of barotrauma.
Controlled mandatory
ventilation(CMV)
▪ Ventilator trigger mode
▪ Fully controlled ventilation :
▪ preset rate; Fio2; VT; flow rate; I : E ratio.
▪ Reserved for patients unable to breath at all or under
pharmacologic paralysis or heavy sedation, in a coma.
Control Mode
Assist control
▪ Patient trigger mode
▪ Patient controls initiation of breath and rate. If the patient
stops breathing spontaneously, the ventilator goes into
backup mode with the preset rate and VT until spontaneous
inspiratory effort is sensed.
Assist Mode
Intermittent mandatory
ventilation(IMV)
▪ Allows patient to breath spontaneously between preset
number of mechanical breath.
IMV – Intermittent Mandatory
Ventilation
Synchronized Intermittent
Mandatory Ventilation (SIMV):
▪ patient receives a preset respiratory rate at a set tidal
volume
▪ machine allows for the patient to breathe spontaneously
during the machine breaths.
▪ If the patient breathes near the time that the machine is
prepared to deliver the preset volume, the machine will
deliver the preset tidal volume.
▪ The breaths that the patient initiates in between the
machine breaths are not supplemented by the machine.
It is usually tolerated well by the patient, because of the
synchronicity involved.
Pressure Support Ventilation (PSV)
▪ PSV is preset pressure that augments the patient’s
spontaneous inspiratory effort and decreases the
work of breathing.
▪ patient completely controls the respiratory rate and
tidal volume.
▪ PSV is used for patients with a stable respiratory
status and is often used with SIMV to overcome the
resistance of breathing through ventilator circuits
and tubing.
Continuous Positive
Airway Pressure (CPAP):
▪ Used either intermittently during long‐term weaning as a way
to strengthen the muscles, or as a final step before removing
the patient from the ventilator, to see how they tolerate the
lack of ventilatory assistance.
▪ All breaths are generated by the patient, and the patient’s
effort determines the tidal volume.
▪ The machine simply provides a continuous airway pressure,
supplemental oxygen, and apnea alarms. The continuous
airway pressure makes the effort of breathing easier for the
patient.
Positive End Expiratory Pressure (PEEP)
▪ PEEP is positive pressure that is applied by the
ventilator at the end of expiration.
▪ This mode does not deliver breaths, but is used as an
adjunct to CV, A/C, and SIMV to improve oxygenation
by opening collapsed alveoli at the end of expiration.
▪ Pressures vary from 3 cmH20 to over 20 cmH20
▪ In healthy adults, 5 cmH20 of PEEP raises
▪ FRC by 400‐500 mL
Benefits
▪ Stability of alveoli and conservation of surfactant .
▪ Resting lung volume raised out of the range of airway
closure
▪ Increased alveolar availability for gas exchange.
Disadvantages
▪ Excess PEEP can cause hyperinflation
▪ Impairs venous return and cardiac output.
▪ Hemodynamic compromise usually occurs at over 1 5 cmH20
PEEP in normovolaemic patients
▪ Increases the risk of barotrauma in patients who have lung
disease, especially in hyperinflation conditions
Precautions
▪ High‐level PEEP should be avoided in undrained
pneumothorax
▪ with caution in surgical emphysema, bulla or
bronchopleural fistula.
▪ Hypervolemia is a relative contraindication, but if necessary
, use inotropes support.
▪ above 10 cmH20, manual hyperinflation requires certain
precautions
Best PEEP
▪ Effective PEEP increases lung compliance and boosts Sa02,
excessive PEEP decreases compliance by over‐distending
alveoli
▪ 'Physiological' PEEP at 3‐5 cmH20 is routinely applied in
order to maintain alveolar stability, and is especially useful
in low lung volume states to prevent progressive
parenchymal injury.
▪ Higher levels of PEEP promote gas exchange and reduce the
necessity for toxic levels of inspired oxygen.
ALARMS
Alarms and Common Causes
High Pressure
Limit
Low Pressure
High Respiratory
Rate
Low Exhaled
Volume
•
Secretions
in ETT/airway or
condensation in
tubing
•
Kink in
vent tubing
•
Patient
biting on ETT
•
Patient
coughing, gagging,
or trying to talk
•
Increased airway
pressure from
•
Ventilator tubing
not connected
•
Displaced ETT or
tracheostomy
tube
•
Patient
anxiety or pain
•
Secretions in
ETT/airway
•
Hypoxia
•
Hypercabnia
•
Ventilator tubing
not connected
•
Leak in
cuff or
inadequate cuff
seal
•
Occurrence of
another alarm
preventing full
delivery of breath
COMPLICATIONS
Barotrauma
▪ Barotrauma is extra‐alveolar aIr, e.g. pneumothorax. The
name arose from assumptions that the cause was excess
pressure, because affected patients tend to have high peak
pressures.
▪ Excess volume is the cause, because sustained alveolar
distension can rupture the delicate alveolar capillary
membrane
▪ Pneumothorax
▪ Pneumomediastenum
▪ Subcutaneous emphysema
Displaced ventilation
ventilation abolished in dependent area of lungs
▪ Positive pressure gas takes the path of least resistance
which is to the more open upper regions.
▪ The diaphragm is inactive and it is irrelevant
that its dependent fibers are more stretched by abdominal
viscera.
▪
Increased dead space
▪ Dead space increases because of reduced overall
▪ perfusion, and to a lesser extent because of distension of
ventilator tubing.
Ventilation perfussion
mismatched
▪ Disturbed ventilation and perfusion gradients, and increased dead
space, result in VA/Q mismatch
Gut dysfunction
▪ Decrease perfusion increase permeability increase incidence
of bleeding, paralytic ileus and ulcer
▪ Delay gastric emptying
Absorption atelectasis
▪ During 100% oxygen delivery, OXygen is extremely soluble in
blood and diffuses very quickly into the pulmonary
vasculature. if in fact, that not enough gas is left in the
alveoli to maintain patency, and the alveolus collapses; this
is known as absorption atelectasis.
Excess secretions
▪ Irritation from ETT
▪ Impaired mucuociliary clearance system
Weak inspiratory muscles
▪ atrophy
Ventilator­associated
pneumonia (VAP)
▪ Develops at a rate of approximately 1% per day and has an
attributable mortality rate as high as 20–50%.
▪ Hand washing, elevation of the head of the bed, non‐nasal
intubation, and proper nutrition all reduce the rate of VAP.
▪ Avoidance of unnecessary antibiotics decreases the risk of
VAP with a resistant pathogen.
▪ WEANING
Weaning requires:
▪ progressive reduction In support so patient is able to sustain
spontaneous breathing
▪ trial of spontaneous breathing through the tracheal tube
▪ Extubation.
Weaning criteria
▪ Reversal of primary problem causing need for
ventilation
▪ Patient awake and responsive
▪ Good analgesia, ability to cough
▪ Reducing or minimal doses of inotropic support Ideally
▪ Functioning bowels, absence of abdominal distension
▪ Normalizing metabolic status
▪ Adequate hemoglobin concentration
cont.
▪ Minute ventilation>10l/mint
▪ Vital capacity>10ml/kg
▪ Respiratory rate<35
▪ Tidal volume>5ml/kg
▪ maximum inspiratory pressure > 20 cmH20
▪ Pa02 > 60mmHg on 40% oxygen and 5cm PEEP
Weaning process
Reduction in ventilatory support by
▪ Decreased number of breaths in SIMV mode or
▪ Decreased pressure in PS mode.
Steps of weaning
▪ Explanations
▪ patient takes up in preferred posture, usually sitting
upright.
▪ Humidified oxygen is connected to the tracheal tube
by a T‐piece
▪ airway suctioning if necessary.
▪ patient is disconnected from the ventilator, given
oxygen, encouraged to breathe, and monitored for
signs of labored breathing, anxiety, desaturation,
fatigue or drowsiness
▪ If the diaphragm tires, it may need 24 hours to recover, and
it is better to return the patient to respiratory support than
to await respiratory distress
Extubation
Removal of Endotracheal tube
Criteria for Extubation
▪ can maintain a patent airway.
▪ can protect the airway from aspiration.
▪ can maintain a clear chest.
▪ reason for intubation has been alleviated.
▪ Able to cough
▪ sustainable 30‐60 minutes of spontaneous breathing
Steps for Extubation
▪ Give physiotherapy or simply suction the airway.
▪ Sit the patient upright.
▪ Explain how the tube will be removed
▪ Suck out the mouth and throat to clear secretions
▪ Cut the tape holding the tube a fresh catheter to reach just
distal to the tip of the tube, deflate the cuff, slide the tube
out in a gentle downward curve, suctioning during
withdrawal.
▪ Encourage the patient to cough out
▪ Give oxygen, non‐invasive ventilation
▪ monitors and breathing pattern, listen for stridor.
REFERENCES
▪ Physiotherapy in respiratory care by alexander hough
▪ Nancy D Ciesla. Chest Physical Therapy for Patients in
Intensive Care Unit ;PHYS THER.1996;76:609‐625.
▪ Susan berney et al, physiotherapy in critical care in
austrailia, CPTJ Vol 23 /1 march 2012 ‘19‐23.
▪ Wai pong wong,physical therapy for patient in acute
respiratory failure.PT. vol 80. july 2000:662‐669.
THANK YOU