mechanical ventilation Flashcards
goal with mechanical ventilation
-supportive respiratory therapy that is used to support and improve ventilation and perfusion
what does mechanical ventilation maintain
- alveolar ventilation appropriate for the patient’s metabolic needs
- correct hypoxemia
- 02 transport
- Bridge to recovery or until decision for EOL
- Non Curative
definition of mechanical ventilation
- Oxygen moved in and out of lungs by mechanical means
- Required Endotracheal tube (ETT) or tracheostomy (Trach)
types of mechanical ventilation
- Negative Pressure Ventilation
- Positive Pressure Ventilation
1. Volume Ventilation or Pressure ventilation
2. Other: PEEP and CPAP (NIVVP)
indications for mechanical ventilation
- Apnea
- Unprotected airway
- Acute Respiratory Failure
- Acute Respiratory Distress Syndrome (ARDS) - Severe Hypoxemia
- Severe Respiratory Muscle fatigue/impairment
data r/t indications
- Failure to ventilate
- PCO2 > 50 mmHg , pH 7.3 or less
- PaO2 < 50 mm Hg
- Respiratory rate: Increased ineffective > 40
- Low RR/ Breathing Ineffective: RR <8* , apnea (apneic periods), diminished or absent lung sounds, shallow expansion, Acute Resp Failure, ARDS , respiratory muscle fatigue
ventilator modes
-methods by which the inspirations/expirations are provided or set
mode selections
- Based on individual patient status
- ABG, LOC, Respiratory drive or therapeutic needs
- Provider ordered
- RT and RN : recommends and monitors
- Mode Setting placed into Ventilator control panels
how to decide ventilator settings
- individualized
- Pt weight (ideal weight)
- LOC
- Pt Response
ventilator settings
- Fraction of Inspired Air: FiO2
- Rate
- Tidal volume
- Positive End-Expiratory Pressure
- Sensitivity
- High Pressure limits
WHAT IS THE TIDAL VOLUME
-amount of gas delivered each breath
what is the RR
-number of breaths delivered each minute
Fi02
-fraction of inspired oxygen
pressure limits
-if the pressure goes too high (past this) excess will be released
negative pressure ventilation
- Device Chamber surrounds chest with negative pressure.
- Result: Chest is pulled “outward” and Air enters lungs
- Expiration is positive
- Examples: iron lung, cuirass
advantage to negative pressure ventilation
-no artificial airway required and home use is possible
disadvantage to negative. pressure ventilation
- volume per breath (unsure how much getting), uncontrolled therapy, skin irritation/damage
when is negative pressure ventilation usually used
- used in pts . With neuromuscular disorders such as MS or MD
- Not used in critical care for acute impairment
positive pressure ventilation
- Positive Pressure applied to airways at inspiration
- Expiration: Passive
- Intrathoracic pressure increases with inspiration as the ventilator send measured tidal volume or breath in – this stays positive until the breath ends
modes on positive pressure ventilation
- Volume modes: used in past
- Assist Control (AC)
- Synchronized Intermittent Mandatory Ventilation (SIMV) - Pressure modes: more commonly used, safe, effective
- Pressure Support Ventilation
- PEEP
- CPAP
ventilator mode: volume type- assist control
- Tidal Volume (Vt) are set
- Number of Breaths are set
- The patient Can initiate own breaths
- Each breath still provided at SET Tidal Volume (Vt)
-rate set plus whatever breaths they take on own
advantages to assist control
- Allows decrease WOB
- Allow some independence by patient
disadvantages to assist control
- Hypoventilation if settings are too low
- Hyperventilation if patient is breathing too fast
if patient initiates a breath on assist control what will the end tidal volume be if was set to 550
550
On AC mode: if patient initiates a breath How does that effect the Rate?
The patient rate will be 12 PLUS whatever breaths taken on own; so the RR is now 13
PPV modes- SIMV (Synchronized intermittent mandatory ventilation)
-A set number of breaths with set volume
-Patient can initiate own breath at own volume
I.e.: SIMC 10, Vt 650 FiO2 40%
-Each of the set 10 breaths are delivered at Vt of 650
-Pts. Own breath could be at any vT the patient is able to pull
-The “synchronized” breath is delivered at the end of expiration so patient is comfortable
SIMV advantages
- Decrease in positive pressure breath
- Improving C. O. since allowing to take breaths on own
SIMV disadvantages
- Hypoventilation is rate is set too low & pt not taking own breath
- Close monitoring
- If rate is set too low: pt may become fatigued or acidotic
SIMV use in the past and now
- In the past SIMV was used for weaning
- Improved synchrony between pt and ventilator
- More comfort for pt.
- Used in combo with pressure support for wean
-With newer Ventilators this Mode not used very often , might find SIMV used in rehab units
Pressure control ventilation (PCV)
- Provides set rate
- Amount of pressure needed to provide Rate is Controlled
- No Tidal volumes set:
Airway pressure release ventilation (APRV)
- Allows for release of pressure at any time
- Pt can take a breath and the ventilator allows
- Less PPV
- Used for patients who need high pressures to open up and recruit alveoli
- Reduces need for deep sedation
Pressure Control Inverse Ration (PC-IRV)
- Combines pressure controlled ventilation with inverse ratio of Inspiration and Expiration.
- Normal RR ratio is 1:2 or 1:3
- This IRV is 1:1
- Used in ARDS,
- Not everyone responds
Mechanical Ventilation: other settings: Adjunctive Ventilator /Respiratory support Settings
- Positive End Expiratory Pressure (PEEP)
- Continuous Positive Airway Pressure (CPAP)
- This can be Set on Ventilators
- and we also use it in accessory devices - Pressure Support (PS)
PEEP
- Prevents alveolar collapse
- aeration of alveoli
- provides counter pressure to fluid extravasation
PEEP indication
- pt. cannot maintain a pO2 greater than 60 mm Hg on less than 50% FiO2
- PEEP is commonly used in patients who are suspected of having a pathology that predisposes their alveoli to collapse, this is generally due to a large amount of fluid in the lungs
mechanics of PEEp
- Normally, the pressure in alveoli is zero with exhalation.
- By adding pressure to the alveoli at the end of expiration, lung volume during expiration and between breaths increases, FRC increases, alveoli remain open longer or open if closed
major purpose of PEEP
- maintain or improve oxygenation while limited risk of O2 toxicity
- Allows for lower levels of FiO2