Management of Patient Requiring Breathing Assistance

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Management of Patient Requiring Breathing
Assistance

• Topic 2
• (Q and A session)

Dr. S. Nishan Silva (MBBS)
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Q Parts of the Respiratory System?
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Q Explain the different Lung volumes
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Q Indications for Ventilation?
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Initiation of Mechanical Ventilation

• Indications
• Indications for Ventilatory Support
• Acute Respiratory Failure
• Prophylactic Ventilatory Support
• Hyperventilation Therapy

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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 lt 70 on on O2
• PaCO2 gt 55 mm Hg and rising
• pH 7.25 and lower

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Initiation of Mechanical Ventilation

• Indications
• Acute Respiratory Failure (ARF)
• Hypoxic lung failure (Type I)
• Ventilation/perfusion mismatch
• Diffusion defect
• Right-to-left shunt
• Alveolar hypoventilation
• Decreased inspired oxygen
• Acute life-threatening or vital organ-threatening
  tissue hypoxia

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Initiation of Mechanical Ventilation

• Indications
• Acute Respiratory Failure (ARF)
• Clinical Presentation of Severe Hypoxemia
• Tachypnea
• Dyspnea
• Central cyanosis
• Tachycardia
• Hypertension
• Irritability, confusion
• Loss of consciousness
• Coma

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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

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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.

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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

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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

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Initiation of Mechanical Ventilation

• Indications
• Acute Respiratory Failure (ARF)
• Clinical Presentation of Hypercapnia
• Tachypnea
• Dyspnea
• Tachycardia
• Hypertension
• Headache (hallucinations when severe)
• Confusion (loss of consciousness, even coma when
  severe)
• Sweating

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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 support is instituted to
• Decrease the WOB
• Minimize O2 consumption and hypoxemia
• Reduce cardiopulmonary stress
• Control airway with sedation

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Initiation of Mechanical Ventilation

• Hyperventilation Therapy
• Ventilatory support is instituted to control and
  manipulate PaCO2 to lower than normal levels
• Acute head injury

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Initiation of Mechanical Ventilation

• Contraindications
• Untreated pneumothorax
• Relative Contraindications
• Patients informed consent
• Medical futility
• Reduction or termination of patient pain and
  suffering

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Nomenclature
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Nomenclature

• Airway Pressures
• Peak Inspiratory Pressure (PIP)
• Positive End Expiratory Pressure (PEEP)
• Pressure above PEEP (PAP or ?P)
• Mean airway pressure (MAP)
• Continuous Positive Airway Pressure (CPAP)
• Inspiratory Time or IE ratio
• Tidal Volume amount of gas delivered with each
  breath

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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.

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Modes

• IMV Modes intermittent mandatory ventilation
  modes - breaths above set rate not supported
• SIMV vent synchronizes IMV breath with
  patients effort
• Pressure Support vent supplies pressure support
  but no set rate pressure support can be fixed or
  variable (volume support, volume assured support,
  etc)

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Ventilator Settings Terminology (cont)

• 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

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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

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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

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CMV
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Control Mode

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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

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A/CV
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A/C cont.

Negative deflection, triggering assisted breath
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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)

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SIMV
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SIMV cont.
Machine Breaths
Spontaneous Breaths
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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.

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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.

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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

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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

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Inspiratory flow

• Varies with the Vt, IE and RR
• Normally about 60 l/min
• Can be majored to 100- 120 l/min

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Inspiratory Time Expiratory Time Relationship
(IE Ratio)

• During spontaneous breathing, the normal IE
  ratio is 12, 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 auto-PEEP.
• Depending on the disease process, such as in
  ARDS, the IE ratio can be changed to improve
  ventilation

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IE Ratio

• 12
• Prolonged at 13, 14,
• Inverse ratio

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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

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FIO2

• The usual goal is to use the minimum Fio2
  required to have a PaO2 gt 60mmhg or a sat gt90
• Start at 100
• Oxygen toxicity normally with Fio2 gt40

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Inspiratory Trigger

• Normally set automatically
• 2 modes
• Airway pressure
• Flow triggering

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Positive End-expiratory Pressure (PEEP)

• What is PEEP?
• What is the goal of PEEP?
• Improve oxygenation
• Diminish the work of breathing
• Different potential effects

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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)

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PEEP

• What are the secondary effects of PEEP?
• Barotrauma
• Diminish cardiac output
• Regional hypoperfusion
• NaCl retention
• Augmentation of I.C.P.?
• Paradoxal hypoxemia

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PEEP

• Contraindication
• No absolute CI
• Barotrauma
• Airway trauma
• Hemodynamic instability
• I.C.P.?
• Bronchospasm?

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PEEP

• What PEEP do you want?
• Usually, 5-10 cmH2O

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PEEP cont.
Pressure above zero
PEEP is the amount of pressure remaining in the
lung at the END of the expiratory phase.
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Continuous Positive Airway Pressure (CPAP)

• This IS a mode and simply means that a pre-set
  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.

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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
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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
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Intubation

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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

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Intubation Procedure

• Position your patient into the sniffing position

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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.

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Intubation Procedure

• Insert Laryngoscope

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Intubation Procedure

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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.

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Intubation Procedure

• Confirm tube position
• By auscultation of the chest
• Bilateral chest rise
• Tube location at teeth
• CO2 detector (esophageal
• detection device)

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Intubation Procedure
Stabilize the ETT
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Q Describe suction procedure for ventilated
patients.
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TROUBLESHOOTING
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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)

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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

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Low Pressure Alarm

• Usually due to a leak in the circuit.
• Attempt to quickly find the problem
• Bag the patient and call your doctor

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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

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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

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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 patients face
  supply the patient with ventilation.
• Bag the patient and call for your doctor

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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!

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Trouble Shooting

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ABG

• Goal
• Keep patients acid/base balance within normal
  range
• pH 7.35 7.45
• PCO2 35-45 mmHg
• PO2 80-100 mmHg

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Complications

• Ventilator Induced Lung Injury
• Oxygen toxicity
• Barotrauma / Volutrauma
• Peak Pressure
• Plateau Pressure
• Shear Injury (tidal volume)
• PEEP

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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 dont even notice)

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Complications

• Other Complications
• Ventilator Associated Pneumonia
• Sinusitis
• Sedation
• Risks from associated devices (CVLs, A-lines)
• Unplanned Extubation

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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 ?

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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.

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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

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Mechanical Ventilators

• Different Types of Ventilators Available
• Will depend on you place of employment

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Mechanical Ventilators

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Mechanical Ventilators

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Mechanical Ventilators

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Mechanical Ventilators

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Mechanical Ventilators

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High Frequency Mechanical Ventilator

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