Transcript Document

Management of Patient
Requiring Breathing Assistance
Topic 2
(Q and A session)
Dr. S. Nishan Silva
(MBBS)
Q : Parts of the
Respiratory System?
Q : Explain the different
“Lung volumes”
Q : Indications for
Ventilation?
Initiation of Mechanical Ventilation

Indications
– Indications for Ventilatory Support
– Acute Respiratory Failure
– Prophylactic Ventilatory Support
– Hyperventilation Therapy
Initiation of Mechanical Ventilation

Indications
– Acute Respiratory Failure (ARF)
 Respiratory
activity is inadequate or is insufficient to
maintain adequate oxygen uptake and carbon
dioxide clearance.
 Inability
of a patient to maintain arterial PaO2,
PaCO2, and pH acceptable levels
 PaO2
< 70 on on O2
 PaCO2 > 55 mm Hg and rising
 pH 7.25 and lower
Initiation of Mechanical Ventilation
Indications

–
Acute Respiratory Failure (ARF)

Hypoxic lung failure (Type I)
–
–
–
–
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Ventilation/perfusion mismatch
Diffusion defect
Right-to-left shunt
Alveolar hypoventilation
Decreased inspired oxygen
–
Acute life-threatening or vital
organ-threatening tissue hypoxia
Initiation of Mechanical Ventilation

Indications
– Acute Respiratory Failure (ARF)
 Clinical
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–
–
–
–
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Presentation of Severe Hypoxemia
Tachypnea
Dyspnea
Central cyanosis
Tachycardia
Hypertension
Irritability, confusion
Loss of consciousness
Coma
Initiation of Mechanical Ventilation
Indications

–
Acute Respiratory Failure (ARF)

Acute Hypercapnic Respiratory Failure
(Type II)
–
CNS Disorders

Reduced Drive To Breathe: depressant
drugs, brain or brainstem lesions (stroke,
trauma, tumors), hypothyroidism

Increased Drive to Breathe: increased
metabolic rate (CO2 production), metabolic
acidosis, anxiety associated with dyspnea
Initiation of Mechanical Ventilation
Indications

–
Acute Respiratory Failure (ARF)

Acute Hypercapnic Respiratory Failure
(Type II)
–
Neuromuscular Disorders

Paralytic Disorders: Myasthenia Gravis,
Guillain-Barre´, ALS, poliomyelitis, etc.

Paralytic Drugs: Curare, nerve gas,
succinylcholine, insecticides

Drugs that affect neuromuscular
transmission; calcium channel blockers,
long-term adenocorticosteroids, etc.

Impaired Muscle Function: electrolyte
imbalance, malnutrition, chronic pulmonary
disease, etc.
Initiation of Mechanical Ventilation
Indications

–
Acute Respiratory Failure (ARF)

Acute Hypercapnic Respiratory Failure
–
Increased Work of Breathing

Pleural Occupying Lesions: pleural
effusions, hemothorax, empyema,
pneumothorax

Chest Wall Deformities: flail chest,
kyphoscoliosis, obesity

Increased Airway Resistance: secretions,
mucosal edema, bronchoconstriction,
foreign body

Lung Tissue Involvement: interstitial
pulmonary fibrotic diseases
Initiation of Mechanical Ventilation
Indications

–
Acute Respiratory Failure (ARF)

Acute Hypercapnic Respiratory Failure
–
Increased Work of Breathing (cont.)

Lung Tissue Involvement: interstitial
pulmonary fibrotic diseases, aspiration,
ARDS, cardiogenic PE, drug induced PE

Pulmonary Vascular Problems:
pulmonary thromboembolism,
pulmonary vascular damage

Dynamic Hyperinflation (air trapping)

Postoperative Pulmonary
Complications
Initiation of Mechanical Ventilation

Indications
– Acute Respiratory Failure (ARF)
 Clinical
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Presentation of Hypercapnia
Tachypnea
Dyspnea
Tachycardia
Hypertension
Headache (hallucinations when severe)
Confusion (loss of consciousness, even
coma when severe)
– Sweating
Initiation of Mechanical Ventilation

Prophylactic Ventilatory Support
– Clinical conditions in which there is a high
risk of future respiratory failure
 Examples:
Brain injury, heart muscle injury,
major surgery, prolonged shock, smoke injury
 Ventilatory
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–
–
support is instituted to:
Decrease the WOB
Minimize O2 consumption and hypoxemia
Reduce cardiopulmonary stress
Control airway with sedation
Initiation of Mechanical Ventilation

Hyperventilation Therapy
– Ventilatory support is instituted to control
and manipulate PaCO2 to lower than normal
levels
 Acute
head injury
Initiation of Mechanical Ventilation

Contraindications
– Untreated pneumothorax

Relative Contraindications
– Patient’s informed consent
– Medical futility
– Reduction or termination of patient pain and
suffering
Nomenclature
Nomenclature
 Airway
Pressures
– Peak Inspiratory Pressure (PIP)
– Positive End Expiratory Pressure (PEEP)
– Pressure above PEEP (PAP or ΔP)
– Mean airway pressure (MAP)
– Continuous Positive Airway Pressure
(CPAP)
 Inspiratory
Time or I:E ratio
 Tidal Volume: amount of gas delivered
with each breath
Modes
 Control
Modes:
– every breath is fully supported by the
ventilator
– in classic control modes, patients were
unable to breathe except at the controlled
set rate
– in newer control modes, machines may
act in assist-control, with a minimum set
rate and all triggered breaths above that
rate also fully supported.
Modes
 IMV
Modes: intermittent mandatory
ventilation modes - breaths “above”
set rate not supported
 SIMV: vent synchronizes IMV “breath”
with patient’s effort
 Pressure Support: vent supplies
pressure support but no set rate;
pressure support can be fixed or
variable (volume support, volume
assured support, etc)
Ventilator Settings
Terminology (con’t)
PRVC:
Pressure Regulated Volume
Control
PEEP: Positive End Expiratory
Pressure
CPAP: Continuous Positive Airway
Pressure
PSV:
Pressure Support Ventilation
NIPPV: Non-Invasive Positive
Pressure Ventilation
Modes
Whenever a breath is supported by the
ventilator, regardless of the mode,
the limit of the support is determined
by a preset pressure OR volume.
– Volume Limited: preset tidal volume
– Pressure Limited: preset PIP or PAP
Modes of Ventilation: The Basics
Assist-Control
Ventilation Volume
Control
Assist-Control Ventilation Pressure
Control
Pressure Support Ventilation
Synchronized Intermittent Mandatory
Ventilation Volume Control
Synchronized Intermittent Mandatory
Ventilation Pressure Control
CMV
Control Mode
Assist Control Ventilation
A
set tidal volume (if set to volume
control) or a set pressure and time (if
set to pressure control) is delivered
at a minimum rate
Additional ventilator breaths are
given if triggered by the patient
A/CV
A/C cont.
Negative deflection,
triggering assisted
breath
Synchronized Intermittent Mandatory
Ventilation
 Breaths
are given are given at a set minimal
rate, however if the patient chooses to breath
over the set rate no additional support is
given
 One advantage of SIMV is that it allows
patients to assume a portion of their
ventilatory drive
 SIMV is usually associated with greater work
of breathing than AC ventilation and therefore
is less frequently used as the initial ventilator
mode
 Like AC, SIMV can deliver set tidal volumes
(volume control) or a set pressure and time
(pressure control)
SIMV
SIMV cont.
Machine Breaths
Spontaneous Breaths
PSV(pressure support
ventilation)
Spontaneous inspiratory efforts
trigger the ventilator to provide a
variable flow of gas in order to attain
a preset airway pressure.
Can be used in adjunct with SIMV.
Pressure Support Ventilation
 The
patient controls the respiratory rate
and exerts a major influence on the
duration of inspiration, inspiratory flow
rate and tidal volume
 The model provides pressure support to
overcome the increased work of breathing
imposed by the disease process, the
endotracheal tube, the inspiratory valves
and other mechanical aspects of
ventilatory support.
Tidal Volume or Pressure
setting
 Maximum
volume/pressure to
achieve good ventilation and
oxygenation without producing
alveolar overdistention
 Max
cc/kg? = 10 cc/kg
 Some
clinical exceptions
Flow Rate
The
peak flow rate is the maximum
flow delivered by the ventilator
during inspiration. Peak flow rates of
60 L per minute may be sufficient,
although higher rates are frequently
necessary. An insufficient peak flow
rate is characterized by dyspnea,
spuriously low peak inspiratory
pressures, and scalloping of the
inspiratory pressure tracing
Inspiratory flow
 Varies
with the Vt, I:E and RR
 Normally
 Can
about 60 l/min
be majored to 100- 120 l/min
Inspiratory Time: Expiratory Time
Relationship (I:E Ratio)
 During
spontaneous breathing, the normal
I:E ratio is 1:2, indicating that for normal
patients the exhalation time is about twice
as long as inhalation time.
 If exhalation time is too short “breath
stacking” occurs resulting in an increase in
end-expiratory pressure also called autoPEEP.
 Depending on the disease process, such as
in ARDS, the I:E ratio can be changed to
improve ventilation
I:E Ratio
 1:2
 Prolonged
 Inverse
at 1:3, 1:4, …
ratio
Fraction of Inspired Oxygen
The
lowest possible fraction of
inspired oxygen (FiO2) necessary to
meet oxygenation goals should be
used. This will decrease the likelihood
that adverse consequences of
supplemental oxygen will develop,
such as absorption atelectasis,
accentuation of hypercapnia, airway
injury, and parenchymal injury
FIO2
 The
usual goal is to use the
minimum Fio2 required to have a
PaO2 > 60mmhg or a sat >90%
 Start
at 100%
 Oxygen
>40%
toxicity normally with Fio2
Inspiratory Trigger
 Normally
2
set automatically
modes:
– Airway pressure
– Flow triggering
Positive End-expiratory
Pressure (PEEP)
What is PEEP?
What is the goal of PEEP?
– Improve oxygenation
– Diminish the work of breathing
– Different potential effects
Positive End-Expiratory Pressure
(PEEP)
Applied
PEEP is generally added to
mitigate end-expiratory alveolar
collapse. A typical initial applied PEEP
is 5 cmH2O. However, up to 20
cmH2O may be used in patients
undergoing low tidal volume
ventilation for acute respiratory
distress syndrome (ARDS)
PEEP

What are the secondary effects of PEEP?
– Barotrauma
– Diminish cardiac output
–
–
–
–
Regional hypoperfusion
NaCl retention
Augmentation of I.C.P.?
Paradoxal hypoxemia
PEEP
 Contraindication:
– No absolute CI
– Barotrauma
– Airway trauma
– Hemodynamic instability
– I.C.P.?
– Bronchospasm?
PEEP
 What
PEEP do you want?
– Usually, 5-10 cmH2O
PEEP cont.
Pressure above zero
PEEP is the
amount of
pressure
remaining in the
lung at the END
of the expiratory
phase.
Continuous Positive Airway
Pressure (CPAP):
• This IS a mode and simply means that a preset pressure is present in the circuit and
lungs throughout both the inspiratory and
expiratory phases of the breath.
• CPAP serves to keep alveoli from collapsing,
resulting in better oxygenation and less
WOB.
• The CPAP mode is very commonly used as a
mode to evaluate the patients readiness for
extubation.
Advantages of Each Mode
Mode
Advantages
Assist Control Ventilation (AC)
Reduced work of breathing
compared to spontaneous
breathing
AC Volume Ventilation
Guarantees delivery of set
tidal volume
AC Pressure Control
Ventilation
Allows limitation of peak
inspiratory pressures
Pressure Support Ventilation
(PSV)
Patient comfort, improved
patient ventilator interaction
Synchronized Intermittent
Mandatory Ventilation (SIMV)
Less interference with normal
cardiovascular function
Disadvantages of Each Mode
Mode
Disadvantages
Assist Control Ventilation (AC)
Potential adverse
hemodynamic effects, may
lead to inappropriate
hyperventilation
AC Volume Ventilation
May lead to excessive
inspiratory pressures
AC Pressure Control
Ventilation
Potential hyper- or
hypoventilation with lung
resistance/compliance
changes
Pressure Support Ventilation
(PSV)
Apnea alarm is only back-up,
variable patient tolerance
Synchronized Intermittent
Mandatory Ventilation (SIMV)
Increased work of breathing
compared to AC
Intubation
Intubation
Procedure
Check and Assemble Equipment:
Oxygen
flowmeter and O2 tubing
Suction apparatus and tubing
Suction catheter or yankauer
Ambu bag and mask
Laryngoscope with assorted blades
3 sizes of ET tubes
Stylet
Stethoscope
Tape
Syringe
Magill forceps
Towels for positioning
Intubation
Procedure
Position your patient into the
sniffing position
Intubation Procedure
Preoxygenate with 100% oxygen
to provide apneic or distressed
patient with reserve while
attempting to intubate.
Do not allow more than 30 seconds to
any intubation attempt.
If intubation is unsuccessful, ventilate
with 100% oxygen for 3-5 minutes
before a reattempt.
Intubation Procedure
Insert Laryngoscope
Intubation
Procedure
Intubation
Procedure
After displacing the
epiglottis insert the ETT.
The depth of the tube for a
male
patient on average is
21-23 cm at teeth
The depth of the tube on average
for a female patient is 19-21 at
teeth.
Intubation
Procedure
Confirm tube position:
By auscultation of the chest
Bilateral chest rise
Tube location at teeth
CO2 detector – (esophageal
detection device)
Intubation Procedure
Stabilize the ETT
Q: Describe suction
procedure for ventilated
patients.
TROUBLESHOOTING
Troubleshooting
 Is
it working ?
–Look at the patient !!
–Listen to the patient !!
–Pulse Ox, ABG, EtCO2
–Chest X ray
–Look at the vent (PIP; expired
TV; alarms)
TROUBLESHOOTING

Anxious Patient
– Can be due to a malfunction of the ventilator
– Patient may need to be suctioned
– Frequently the patient needs medication for
anxiety or sedation to help them relax
Attempt
to fix the problem
Call your doctor
Low Pressure Alarm
 Usually
due to a leak in the circuit.
– Attempt to quickly find the problem
– Bag the patient and call your doctor
High Pressure Alarm

Usually caused by:
– A blockage in the circuit (water
condensation)
– Patient biting his ETT
– Mucus plug in the ETT
– You can attempt to quickly fix the
problem
– Bag the patient and call for your
doctor
Low Minute Volume Alarm
 Usually
caused by:
– Apnea of your patient (CPAP)
– Disconnection of the patient
from the ventilator
– You can attempt to quickly fix
the problem
– Bag the patient and call for
your doctor
Accidental Extubation

Role of the Nurse:
– Ensure the Ambu bag is attached to
the oxygen flowmeter and it is on!
– Attach the face mask to the Ambu
bag and after ensuring a good seal
on the patient’s face; supply the
patient with ventilation.
–Bag the patient and call for
your doctor
OTHER
 Anytime
you have concerns,
alarms, ventilator changes or
any other problem with your
ventilated patient.
–Call for your doctor
–NEVER hit the silence
button!
Trouble Shooting
ABG
• Goal:
• Keep patient’s acid/base balance within
normal range:
• pH
• PCO2
• PO2
7.35 – 7.45
35-45 mmHg
80-100 mmHg
Complications
 Ventilator
Induced Lung Injury
–Oxygen toxicity
–Barotrauma / Volutrauma
Peak Pressure
Plateau Pressure
Shear Injury (tidal volume)
PEEP
Complications
 Cardiovascular
Complications
–Impaired venous return to RH
–Bowing of the Interventricular Septum
–Decreased left sided afterload (good)
–Altered right sided afterload
 Sum
Effect…..decreased cardiac
output (usually, not always and often
we don’t even notice)
Complications
 Other
Complications
–Ventilator Associated Pneumonia
–Sinusitis
–Sedation
–Risks from associated devices
(CVLs, A-lines)
–Unplanned Extubation
Extubation
 Weaning
–Is the cause of respiratory failure
gone or getting better ?
–Is the patient well oxygenated and
ventilated ?
–Can the heart tolerate the
increased work of breathing ?
Extubation
 Weaning
(cont.)
–decrease the PEEP (4-5)
–decrease the rate
–decrease the PIP (as needed)
 What
you want to do is decrease
what the vent does and see if
the patient can make up the
difference….
Extubation
 Extubation
– Control of airway reflexes
– Patent upper airway (air leak around
tube?)
– Minimal oxygen requirement
– Minimal rate
– Minimize pressure support (0-10)
– “Awake ” patient
Mechanical
Ventilators
Different Types of Ventilators
Available:
Will depend on you place of
employment
Mechanical Ventilators
Mechanical Ventilators
Mechanical Ventilators
Mechanical Ventilators
Mechanical Ventilators
High Frequency Mechanical
Ventilator