Mechanical Vent Flashcards
4 Main Types of conditions which would lead to mechanical ventilation
- Depressed respiratory drive
- Excessive ventilatory workload (increased work of breathing)
- Failure of ventilatory pump (respiratory muscle failure)
- Impending respiratory failure
What might cause a depressed respiratory drive
- Drug overdose
- Acute SCI
- Head trauma
- Sleep disorders
What might cause an excessive ventilatory workload
- Airflow obstruction - COPD
- Dead space ventilation - PE
- Congenital heart disease - Pulmonary artery hypertension
- Decreased lung compliance - ARDS, Pneumonia
What might lead to failure of ventilatory pump
Chest trauma
What are the two type of Clinical signs of impending respiratory failure
- Decreased PaO2
2. Decreased PaO2 and increased PaCO2
Features of decreased PaO2
- Agitation
- Cyanosis
- Decreased SpO2
- Air hunger
- Tachycardia
Features of decreased PaO2 and PaCO2
- Agitation
- Cyanosis
- Decreased SpO2
- Air hunger
- Tachycardia
- Decreased LOC
- Confusion
- Rapid shallow breathing
2 types of mechanical ventilation?
- Positive pressure ventilation - pushing air into lungs
- Negative pressure ventilation - putting them in cavity with sub-atmospheric pressure surround lungs in turn allowing chest wall to expand and air to flow into lungs
Is positive pressure or negative pressure ventilation closer to normal lung physiology
Negative pressure
Is positive pressure or negative pressure ventilation the most common for of mechanical ventilation
positive pressure
Two methods for positive pressure ventilation
- Invasive positive pressure ventilation
- non-invasive positive pressure ventilation
What are the pulmonary effects of mechanical ventilation that need monitoring
- Increased V/Q and dead space/tidal volume ratio
- Air trapping
- Barotrauma leading to multisystem failure
- Pneumothorax and subcutaneous emphysema
- Increased work of breathing
- Respiratory distress (narrow ETT tube, discomfort)
What are the Hemodynamic effects of mechanical ventilation that need monitoring
- Decreased venous return
- Decreased cardiac output (caused by decreased venous return)
- Decreased BP (due to decreased CO)
- Decreased renal perfusion (as a result of decreased BP)
In MV air flows in which way
Path of least resistance
What is the pump for the venous system (i.e heart is pump for arterial system)
The lungs!! they pull the blood back up to heart
Does prophylactic manual chest physio decrease the incidence of ventilatory associated pneumonia
no
Ventilator associated pneumonia is a pneumonia which starts after ____ hours of ventilation
> 48hours
What are some extra precautions taken when on a ventilator
- Head of bed elevation
- oral hygiene
- DVT and peptic ulcer prophylaxis (prevention)
- Daily sedation vacation
- Reduced frequency of changing vent circuit
Contraindications + precautions of non-invasive ventilation
- Facial trauma
- Obstruction to upper airway
- Hemodynamic instability & multi organ failure
- Decreased LOC
- Undrained pneumothorax
- High risk of aspiration & vomiting
Do you want to put a patient with COPD on a ventilator
No - it is very hard to get them off
Patient interfaces for non-invasive MV
- Face mask
- Nasal mask
- Nasaal Cannula
- Full face mask
Patient interfaces for invasive MV
- Oral endotracheal tube
- Nasal endotracheal tube
- Tracheostomy
When do you most often see a nasal endotracheal tube
in neonatal population or if there was an oral surgery
How do you decide type of patient interface?
For NIV: Patient comfort is biggest player. Most often start with oronasal mask
For IPPV: Most adults intubated with a cuffed oral endotracheal tube.
Why is a cuff an important part of a oral ET tube?
Cuff is there because high pressure air flow follows past of least resistance, in adults most of the air would come out of the mouth. Cuff seals up space around trachea and forces most the air down into the lungs
Benefits of endotracheal tubes vs tracheostomies?
ET more easily inserted + removed
Cons or ET vs tracheostomies
ET:
- triggers gag
- jaw open with OET
- Sedation required
- Pt can’t speak or swallow
- Vocal cords abducted
- Risk of subglottic stenosis
- Increases dead space
Cons of Trach vs ET
Leaves a scar when removed
Requires surgical/bedside procedure
benefits of Trach vs. ET
Trach:
- Does not trigger gag
- Mouth closed at rest
- less sedation required
- Speaking + swallowing possible
- Decreased dead space
What does an ET tube increased dead space and a trach decrease it?
ET tube:
- Because of tubing
Trach:
- Has tubing but has bipassed all the upper airways
MV Control parameters
- Pressure or volume control
- RR
- Pressure support
- positive end expiratory pressure
- FiO2
What is physiological PEEP? Therapeutic PEEP?
- 5cmH2O
- 15-20cmH2O
What is room air FiO2
21%
Why do airways + lungs need a warm moist environment
Mucocilliary clearance
What are 2 types of humidification
passive: HME Filter: Catches warmth and moisture as Pt breaths out and puts it back into air they are breathing in
- Active: Coils inside vent try and maintain heat
3 types of non-invasive ventilation
- CiPAP
- BiPAP
- Optiflow
CPAP essentially only give Pt ____, and relieves ____
PEEP
Work of breathing
Strongest evidence to support use of CPAP
- acute cardiogenic pulmonary edema
- COPD
What does BiPAP stand for
Bilevel positive airway pressure
With BiPAP ___ and ___ are set
IPAP and EPAP
What is optiflow?
High flow device which creates PEEP
Does optiflow provide humidification
yes
Advantages of Optiflow over CPAP
- Communication
- Sputum clearance
- Comfort
- nutrition
Advantages of Optiflow over other high flow O2 devices
- Less drying to airways
- FiO2 and flow are independent of each other
- Higher flow rates
3 forms of invasive ventilation
- Spontaneous & pressure support ventilation
- Synchronized intermittent mechanical ventilation
- Continuous mandatory ventilation
Spontaneous & pressure support ventilation is similar to ___ and ___
BiPAP and CPAP
Spontaneous & pressure support ventilation is used for ____
Weaning
How is Spontaneous & pressure support ventilation used for weaning? What indicates weaning failure?
Via spontaneous breathing trials
- Patient left on enough support to overcome resistance of the circuit and ETT
Rapid shallow breathing index - RR/Tv >105
Features of Synchronized intermittent mechanical ventilation
- Involves periodic targeted breaths that occur at set intervals
- Volume or pressure controlled
- patient has a set rate
- Patient can breath spontaneous b/w mandatory breaths
- Baseline pressure between mandatory breaths can be set/adjusted to suit patient
What are the triggering options for Continuous mandatory ventilation ? Which is most commonly used
- Patient triggered - more common
- Time triggered
When is time triggered used in Continuous mandatory ventilation
When patient is fully sedated and offer no spontaneous effort
What is neurally adjusted ventilatory assist
- Newer mode of ventilation
- breaths triggered by EMG of the diaphragm
What type of condition may use high frequency oscillation
ARDS patients
What does the ventilatory in proportional assist ventilation do?
Ventilator adjusts flow and volume based on a set minuet volume.
Calculates patients work of breathing
What patients is proportional assist ventilation used for?
Difficult to wean patients
What is the effect of nitric oxide? Who is it used in?
- pulmonary vasodilator - Reduces shunt by causing pulmonary vasculature to vasodilate
- In refectory hypoxemia and pulmonary artery hypertension
What does helium do? who is it used in?
- Reduces resistance to airflow
- Improves ventilation in acute asthma
