Mechanical Ventilation - Introduction www.flight-medical.com Flight Medical Confidential 1

Ventilation is Versatile Everywhere Invasive and non-invasive Short and long term

Mechanical ventilation is indicated in many situations ALS Pneumothorax Asthma Obesity Spinal cord lesion Bronchiolitis Fatigue When a patient is unable to adequately remove CO2 and maintain adequate levels of O2 in the arterial blood

Goals of Mechanical Ventilation Decrease work of breathing Enhance the quality of life     Prolong survival Provide cost effective care – enable out of hospital care

Respiratory failure  2 types Diaphragm 1. Gas exchange failure (Lungs i.e. alveoli level) 2. “Pump” failure (Diaphragm & accessory muscles, Impaired chest) Need respiratory assistance if one of failure mentioned append

Obstructive Lung Disease Exhibit increased airway resistance Air trapping “can’t get air out” Decreased elastance; increased compliance Examples: (COPD) a. asthma b. emphysema c. bronchitis d. bronchiolitis

Restrictive Lung Disease Decreased volumes and capacities, normal flow rates “can’t get volume in” Exhibit decreased compliance, increased elastance Examples: Intrinsic: a. Pulmonary fibrosis b. Pulmonary edema c. Pneumo/hemo thorax d. ARDS/IRDS Extrinsic e. Chest wall deformities f. Obesity g. Neuromuscular disorders

Start-Gas delivery-Stop Breath Characteristics Start-Gas delivery-Stop Trigger: what initiates breath Gas delivery target or limit: what controls gas flow Cycle: what terminates the breath

Triggering: Starting Inspiration Breath Characteristics Triggering: Starting Inspiration Machine Trigger (Time) Patient Trigger (Pressure, Flow, Auto) Caregiver Trigger (Manual Breath)

Breath Characteristics Gas delivery

Breath Characteristics Ending Expiration (Termination, Cycling) Reach set volume Reach set time Reach certain flow reduction: Flow Termination (% of maximum flow) 30% of peak flow Peak flow

Mandatory & Spontaneous breath Mandatory breath The ventilator controls the length and size Machine or Patient triggered Spontaneous breath The patient controls the length and size Only patient triggered

Flight 60 Basic Control Parameters Terminology Tidal Volume - VCV Exhaled Minute Volume - MVe Respiratory Rate - Rate Inspiratory Time - Ti PEEP Trigger: Ptirg or Ftrig

Ventilation Parameters Exercise

Parameters

Mechanical Ventilation Volume Ventilation Pressure Ventilation Mixed mode ventilators

Breath Characteristics Gas delivery

Volume-Targeted Ventilation Preset volume is delivered to patient Inspiration ends once volume is delivered Volume constant, pressure variable Ensures proper amount of air is delivered to lungs regardless of lung condition May generate undesirable(high) airway pressures

Volume Ventilation Advantages Guaranteed Vti and Vte Full Ventilator Support Minimal patient WOB (if parameters properly adjusted) Allows some patient control of RR and Ve SAFE !

Volume Ventilation Disadvantages High Pressure Limit must be set appropriately Excessive patient WOB if flow and sensitivity not set appropriately Flow is fixed, which inhibits the patient who has an unstable inspiratory flow or volume demand May be poorly tolerated in awake, non-sedated patients

Pressure-Targeted Ventilation Preset inspiratory pressure is delivered to patient Pressure constant, volume variable Clinician determines ventilating pressures Volumes may increase or decrease in response to changing lung conditions

Pressure Ventilation Advantages PS and PCV control peak and mean airway pressures => Tidal Volume Varies by patient demand Inspiratory flow is variable Rise time variable COMFORTABLE :-) 21 21

Pressure Ventilation Disadvantages No Guaranteed Vt Low exhaled Vt and VE alarms must be set properly Improperly set Rise time or termination can lead to ineffective breath delivery or asynchrony and increased work of breathing 21 21

Pressure Support Ventilation vs. Volume Support Ventilation +++: Good patient tolerance & efficient leak compensation ---: Instability of tidal volume in case of patient respiratory mechanics changes +++: Stability of Tidal volume even in case of patient respiratory mechanics changes ---: No leak compensation, high pressure peaks Use AVAPS.exe to show differences between pressure ventilation, volume ventilation and AVAPS.

Basic Modes of Ventilation

Ventilation modality types Pressure Volume Controlled breath Assist/Controlled breath Spontaneous breath Patient trigger the breath Ventilator cycle the breath Patient trigger and cycle the breath Ti Te + Sedation -

Spontaneous Mode (SPONT) Therapy mode in which all breaths are spontaneous In Spontaneous (S) mode, the device delivers bi-level pressure support. This mode provides only spontaneous breaths. In this mode, an Inspiratory Positive Airway Pressure (IPAP) is delivered during inhalation and a lower Expiratory Positive Airway Pressure (EPAP) is delivered during exhalation. Patient triggers and cycles Machine supports based on pressure support settings

ACMV (Assist/Control Mandatory Ventilation) Time activated (mandatory) breaths are delivered in accordance with the breath rate setting Patients can trigger mandatory breaths in addition to, or in place of, time activated (mandatory) breaths. Breath rate may be increased The breath can be volume or pressure controlled * Mandatory breath: The ventilator controls the timing & size Show the trainee how to set a multiple choice control (Mode) Show the trainee how to set a numeric value control (VCV) Flight Medical Confidential Flight Medical Confidential 28

ACMV (Assist/Control Mandatory Ventilation) VCV 500ml, f 20, Ti 1sec Patient Trigger Time Trigger Use the EGD to present the ACMV, trigger few breaths to demonstrate that all breaths are mandatory. Flight Medical Confidential Flight Medical Confidential 29

SIMV (Synchronized Intermittent Mandatory Ventilation) For the first patient trigger detected within a breath period, an assist breath is given. For all subsequent patient triggers within the same breath period, spontaneous patient breaths are given. At the beginning of a breath period, if no triggered breaths were given in the previous breath period, a machine breath is given. Explain that patient triggered mandatory breath will delay the next time triggered mandatory breath. Use the EGD to present the SIMV, ventilate at 6 b/min PCV 15 PSV 10 and trigger few breaths to demonstrate the combination of mandatory and spontaneous breaths. Within the expiratory phase the first patient trigger will initiate a mandatory breath and the second trigger will initiate pressure support breath. Flight Medical Confidential Flight Medical Confidential 30

SIMV (Synchronized Intermittent Mandatory Ventilation) Patient receives a fixed number of mandatory breaths (time or patient activated) & may breathe spontaneously in between, with or w/o pressure support Time triggered mandatory breath Patient triggered mandatory breath Spontaneous breaths Explain that patient triggered mandatory breath will delay the next time triggered mandatory breath. Use the EGD to present the SIMV, ventilate at 6 b/min PCV 15 PSV 10 and trigger few breaths to demonstrate the combination of mandatory and spontaneous breaths. Within the expiratory phase the first patient trigger will initiate a mandatory breath and the second trigger will initiate pressure support breath. A B C C A A Flight Medical Confidential Flight Medical Confidential 31

SIMV (Synchronized Intermittent Mandatory Ventilation) PCV 15cmH2O, f 10, Ti 1sec, PSV 10cmH2O Mandatory Spontaneous (PSV) Within the expiratory phase the first patient trigger will initiate a mandatory breath and the second trigger will initiate pressure support breath. Flight Medical Confidential Flight Medical Confidential 32

Ventilators & patient circuit type Different technologies used in mechanical ventilation (IV & NIV) Inspiratory limb Expiratory limb Air wall Turbine Piston O2 wall Dual limb system with proportional expiratory valve Inspiration Exhalation Single limb system with proximal expiratory valve Ventilateur Expiratory valve O2 wall O2 low flow Turbine Piston Soufflet Inspiratory limb Inspiration Exhalation Expiratory leak Ventilateur Turbine O2 wall O2 low flow Single limb system with intentional expiratory leak Inspiratory limb Inspiration Exhalation

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