W7: Mechanical Ventilation Flashcards
2 types of oxygen delivery systems
low-flow
high-flow
Low-flow oxygen delivery systems
Provide lower oxygen than the actual inspiratory flow (30 L/min-1)
Degree of dilution depends on inspiratory flows
High-flow oxygen delivery systems
provide higher oxygen flows and FiO2 is stable and is not affected by the patient’s type of breathing
Nasal Prongs
low flow oxygen
Should not exceed maximum oxygen flow of 4L/min
Simple face mask/Hudson mask
Delivers concentrations of 35-65% depending on patient’s respiratory rate and tidal volume
Should not be used at flow rates <5/6 L/min as rebreathing of CO2 may occur
Venturi Mask
suited for patients who require O2 concentrations between 24-50%
Which conditions cannot have high FiO2 and why
COPD and emphysema as it pushes them into type 2 respiratory failure
Non-rebreather mask/oxygen reservoir mask
delivers 90-100% O2
15L/min
precise method to deliver high concentrations of O2 for a short period
Oxygen delivery systems
Nasal prongs
Simple face mask/Hudson mask
Venturi mask
Non-rebreather mask/oxygen reservoir mask
How many puffs for manual ventilation
RR is 12-20 so one puff every 5s
Two types of ventilation therapy
Non-invasive: CPAP or BiPAP
Invasive: intubation
What is the aim of ventilation therapy?
provide positive pressure ventilation, which relates to gas flow along a pressure gradient between the upper airways and the alveoli
What does inspiratory pressure do
pressure support helps to get air in
- would increase if not enough oxygen is getting in
What is expiratory pressure
helps the air get out and PEEP doesn’t allow the lung to fully deflate
What is the difference between CPAP and BiPAP
CPAP is constantly blowing air into the lungs and the flow doesn’t change.
This is necessary for hypoxic patients as you need to get lots of oxygen in at a fast rate
Type 1 Respiratory patients
BiPAP has 2 pressures which allow you to breathe out as well.
Good for type 2 respiratory patients as they can blow off the CO2
When would you use CPAP
Type 1 respiratory patients
Hypoxic patients - need to get lots of oxygen in at a fast rate
When would you use BiPAP
Type 2 respiratory patients so they can blow off CO2
BiPAP
Assists both inspiratory and expiratory phases of breathing. It can actively assist respiration through augmentation of alveolar ventilation
Contraindications of manual hyperinflation
- Undrained pneumothorax
- Severe bronchospasm
- Head injury
- High PEEP
- decreased lung compliance
What is the range for PEEP
5-10 cmH2O
A high peak inspiratory pressure may indicate what?
increased airway resistance
decreased lung compliance
SIMV
This mode provides a set number of mandatory breaths with either a fixed tidal volume or inspiratory pressure. The patient can breathe spontaneously between these mandatory breaths, and the ventilator synchronizes with the patient’s effort
CMV
This mode does not allow spontaneous breathing from the patient. All breaths are controlled by the ventilator, delivering a preset tidal volume or pressure. This mode is generally used for sedated or paralyzed patients
PCV
In pressure control ventilation, a constant pressure is applied during inspiration, and the tidal volume varies depending on the patient’s lung compliance. Pressure support may be added to help the patient initiate breaths and decrease the work of breathing
When would you use manual hyperinflation
- Optimise alveolar ventilation
- Mobilise pulmonary secretions
- secretion clearance
- Improve lung compliance
For every litre increase of Oxygen - Fio2 will be increased by approximately ___%
4
Different levels of ventilation based on heaviest to least support
CMV: heaviest support
SIMV: middle
PS: least support
When would intubation be indicated
other methods unsuccessful in maintaining a patients airway or if the patient’s level of consciousness is compromised
What is indicated for long term ventilation
Tracheostomy
Medical management
for gas exchange
- medications: bronchodilators, steroids, pain relief
- oxygen therapy
- airway management and ventilation
Physiotherapy management
- education
- positioning
- breathing exercise
- mobilisation and exercise
Types of positioning
General positioning
Specific positioning
General positioning
Increase lung volumes
increase FRC above closing capacity (lung volume where small airways start to close)
Specific positioning
Aim to re-expand areas of localised atelectasis
When is positioning indicated
prolonged bed rest and supine positioning
reduces muscle strength and conditioning
decreased FRC
increased atelectasis
What position has highest FRC
upright posture and standing
What can positioning help
Increase oxygenation
increase lung volumes
decrease work of breathing
increases V/Q matching
Increase FRC (above CC) and increase V/Q matching and gas exchange
What happens if FRC < CC
small airway closure during tidal breathing
results in reduced gas exchange and decreased PaO2 and SaO2
When would you use general positioning
Upright positions increases FRC
So you would use general positioning in patients with generalised low lung volumes e.g. postop
When would you use prone positioning
commonly used for ventilated patients
When is lean forward position used
used as a strategy to help relieve acute dyspnea
aims to reduce respiratory effort by stabilising the thorax and accessory muscles and optimising function of the diaphragm
When are deep breathing exercises indicated
patients with atelectasis/low lung volume
when is deep breathing exercises NOT indicated
hyperinflated, breathless patients
What do deep breathing exercises do
encourage lateral basal expansion
better distribution of ventilation (air flow) to the dependent regions of the lungs
reduces risk of pulmonary complications
What does the position of Pursed lips breathing create
back pressure producing PEEP which increases CO2 removal, increases gas exchange and decreases workload of breathing
How does early mobilisation help
reduced duration of mechanical ventilation
increased FRC
increased inspiratory flow rates
increased expiratory flows
reasons to intubate
maintain a patient’s airway
means of supplying oxygen
protects from aspiration
enables paralysis and sedation
rest the respiratory muscles
facilitate secretion removal
Common modes of ventilation
Controlled mechanical ventilation
Assist control ventilation
Synchronised intermittent mandatory ventilation
Pressure support ventilation
Reasons for tracheostomy
bypass an obstructed upper airway
removing secretions from airways
prolonging mechanical ventilation > 2 weeks
more easily and usually more safely deliver oxygen to the lungs
What is PEEP?
The positive pressure that remains in the airways at the end of a respiratory cycle that is greater than the atmospheric pressure in mechanically ventilated patients
what does PEEP do for mechanically ventilated patients
- For patients placed on mechanical ventilation, PEEP will be used to keep the airways & alveoli open to allow for adequate oxygenation – ultimately, increase FRC
how much PEEP for mechanically ventilated patients
5-15cmH2O
