Mechanical ventilation Flashcards
what is mechanical ventilation
it is assisting oxygenation and ventilation of the lungs by artificial means usually a ventilator
what are the types of ventilators
invasive and non invasive
what type of pressure does a ventilator give (2)
- negative
- positive
** we now focus on positive pressure ventilators
what is the indication for going on mechanical ventilator
Impending or Acute respiratory failure with pulmonary gas exchange abnormalities
what things could cause impending/ acute respiratory failure with gas exchange abnormalities (4)
- Mechanical failure:
- neuromuscular diseases e.g. Myasthenia Gravis, Guillain-Barré Syndrome, and Poliomyelitis - Musculoskeletal abnormalities:
- chest wall trauma e.g flail chest. - Infectious/non infectious lung conditions:
- pneumonia
- tuberculosis
- asthma
- chronic bronchitis
- emphysema
- pulmonary edema
- atelectasis
- pulmonary fibrosis. - Others:
- General anesthesia
- Cardiac arrest
- inhalational burns
- moderate to severe head injury
- other CNS pathologies.
what helps us to know that this abnormal gas exchange is an indication for ventilation
arterial blood gases:
- PH < 7.25
- PaO2 (mmHg) < 60mmHg
- PaCO2 (mmHg) > 50mmHg
what are the modes of ventilation (2)
- pressure cycled
- volume cycled
what are non invasive ways of ventilation (2)
- CPAP
- BiPAP
what do you use in CPAP
tight fitting mask
CPAP is used on what type of patients
those that are spontaneously breathing
what does CPAP not provide
inspiratory support
what does CPAP do
delivers end expiratory pressure
what is the difference between CPAP and BiPAP
BiPAP provides inspiratory support
what are contraindications for NIV (6)
1, those with high risk of aspiration:
- pts with ileus/ gastric distention/ have recently eaten
2. agitated patients
3. impaired consciousness/ reduced gag reflex
4. severe respiratory failure
5. severe facial trauma
6. untreated pneumothorax
what is a possible limitation of NIV
high risk of aspiration
what do you use in invasive ventilation
intubation
for the pressure cycled mode how does the pressure control work (2)
- Delivers a constant pressure during each breath
- Gives full control but not all breaths are triggered by the machine
in the pressure cycled mode how does pressure support ventilation work (2)
- There is no minimum rate set
- All breaths triggered by patient
what can you use pressure support ventilation for
weaning off patients
under the pressure cycled mode what things can the ventilator provide (3)
- pressure control
- pressure support ventilation
- synchronized intermittent mandatory ventilation (SIMV)
under the volume cycled mode what things can the ventilator provide (2)
- volume control
- synchronized intermittent mandatory ventilation (SIMV)
how does volume control work (2)
- Delivers a constant volume during each breath gives full control
- It has a set Tidal volume
when setting mechanical ventilation what is it based on
underlying patient condition
what things do you set on a mechanical ventilator (5)
- mode
- oxygenation
- minute volume
- sensitivity/ trigger
- I:E
for oxygenation what parameters do you look at (2)
- FiO2 ( fraction of inspired oxygen)
- PEEP
what is the initial FiO2 that is set
<0.6
what is the initial setting for PEEP
5cmH2O
what does PEEP do
Increases end expired lung volume
what scenarios would you use a higher PEEP (2)
- pulmonary edema
- ARDS
what is minute volume
tidal volume x RR
how do you calculate tidal volume
6-8ml/kg of ideal body weight
what is the ideal RR for a ventilator
10-12 breaths/ min
what is sensitivity/ trigger
Level of negative pressure/gas flow required to trigger a breath
what is the initial setting for I:E
1:2 for adults
1:1 for children
how does I:E work in COPD/asthma
prolonged expiratory time
in I:E what would an increase in inspiratory flow rate do
60L/min to 120L/min
facilitate having more time in exhalation
what are methods of weaning (4)
- T-piece trial
- Continuous Positive Airway Pressure (CPAP) weaning
- Pressure Support Ventilation (PSV) weaning
- Synchronized Intermittent Mandatory Ventilation (SIMV)
when would you discontinue weaning
if there are signs of fatigue or respiratory distress develops
what would be the initial reason for weaning off mechanical ventilation
the reason for ventilation has improved/ resolved
what is step 2 in the weaning off mechanical ventilation
to check daily screening of respiratory function
- Pao2/FiO2> 200
- PEEP < 5
- adequate cough
- t/V < 100
- no use of vasopressors or sedatives
if daily screening of respiratory function does not show improvement what do you do
continue ventilation
if daily screening of respiratory function shows improvement what do you do
you try a spontaneous breathing trial
what are ways of initiating a spontaneous breathing trial (3)
30 mins with:
- T piece
- CPAP
- low level pressure support
if spontaneous breathing trial is poorly tolerated what do you do
gradual weaning with daily T piece trials/ pressure support ventilation
if the spontaneous breathing trial or gradual weaning is tolerated what do you do
extubate
if pt gets respiratory failure post-extubation what should you do (2)
- consider trial of non invasive ventilation for 1-2h ( for cardiogenic pulmonary edema, COPD, immunosuppressed, post thoracic surgery)- if that doesnt work intubate
- intubate if appropriate
what are complications of mechanical ventilation (4)
- Airway Complications
- Mechanical complications
- Physiological Complications
- Artificial Airway Complications
what are airway complications (4)
- oxygen toxicity
- nosocomial or ventilator acquired pneumonia
- decreased clearance of secretions
- aspiration
what are the mechanical complications (7)
- barotrauma
- Closed pneumothorax
- Tension pneumothorax
- Pneumomediastinum
- Subcutaneous emphysema - Hypoventilation with atelectasis with respiratory acidosis or hypoxemia.
- Hyperventilation with hypocapnia and respiratory alkalosis
- Alarm “turned off”
- Failure of alarms or ventilator
- Inadequate nebulization or humidification
- Overheated inspired air, resulting in hyperthermia
what are the physiological complications (7)
- Fluid overload with humidified air and sodium chloride (NaCl) retention
- Depressed cardiac function and hypotension
- Stress ulcers
- Paralytic ileus
- Gastric distension
- Starvation
- Dyssynchronous breathing pattern
what are the artificial airway complications related to endotracheal tube (9)
- tube kinked or plugged
- tracheal stenosis or tracheomalacia
- laryngeal edema
- rupture of piriform sinus
- Mainstem intubation with contralateral (located on or affecting the opposite side of the lung) lung atelectasis
- Cuff failure
- Sinusitis
- Otitis media
what are the artificial airway complications related to the tracheostomy tube (12)
- laryngeal nerve damage
- obstruction of tracheostomy tube
- accidental decannulation with loss of airway
- Acute hemorrhage at the site
- Air embolism
- Aspiration
- Erosion into the innominate artery with exsanguination
- Failure of the tracheostomy cuff
- Subcutaneous and mediastinal emphysema
- Swallowing dysfunction
- Tracheoesophageal fistula
- Infection
