1
Q
Mechanical Ventilation:
A
- replaces the function of the inspiratory muscles by delivering gas under positive pressure to the lungs. This substitutes for the respiratory pump
- Either the ventilator or the patient “triggers” inspiration. If Patient triggered - the ventilator delivers the breath as soon as it senses the beginning of the patients inspiration
2
Q
Respiratory pump is:
A
The abdominal and thoracic structures that contribute to the expansion and contraction of the lungs
3
Q
Compliance reflects:
A
the ability to change the shape of a structure when mechanical load applied. So Lung compliance is the ability of the alveoli and lung tissue to expand on inspiration
4
Q
Intubation process occurs by:
A
- Endotracheal tubes (ETT): most common route to ventilation
- Tracheostomy: often follows if ventilation is predicted to be prolonged. Sometimes 1st choice of intubation if upper airway obstruction or severe facial trauma present. Helps with weaning process
- Nasal endotracheal tubes: less common in adult, often 1st choice in paediatrics. Normally used after failed attempts with ETT. May be used as 1st choice if mouth is inaccessible, i.e. mouth Ca, vocal cord Ca.
5
Q
Mechanical Ventilation Indications include:
A
- Hospitals will vary: Most common indications: inadequate oxygenation (type 1 respiratory failure), inadequate ventilation (type 2 respiratory failure), inability to protect airway (disturbed consciousness)
- Post-operative, Head injuries, Polytrauma: to maintain coma after major trauma/surgery
- Spinal injury
- Airway obstruction
6
Q
Complications of intubation include:
A
- CVS instability: intubation requires sedation and paralysis reducing BP. This is difficult to manage and often requires other strong meds to increase BP.
- Barotrauma: if ventilation settings mismatch
- V/Q mismatch
- Discomfort: ETT once awake may lead to coughing and gagging
- Excess secretions/infection: process is not sterile
- Complications of high O2,
- Gut & bowel dysfunction: sedatives and paralysing drugs
- Weakened respiratory muscles: if ventilation is prolonged or resp. muscles weak prior to intubation
7
Q
Compliance varies depending on:
A
the elasticity and surface tension of the lungs. The stiffer the lung the less compliant, i.e. PF, CF, COPD, recurrent infection and inflammation causing fibrotic changes
8
Q
Relationship between lung compliance and mechanical ventilation:
A
Poorly compliant lungs are harder to mechanically ventilate
9
Q
Mechanical ventilation process includes:
A
- During complete mechanical ventilation an air & oxygen mixture is pushed into the lungs for inspiration.
- The gas flow is then stopped and air is allowed to be passively exhaled.
- Mechanical ventilation uses positive pressures
10
Q
Effect of Ventilation on VQ:
A
- Accentuates the perfusion gradient
- Reverses the ventilation gradient: 1) diaphragm is passive 2) positive pressure takes the path of least resistance 3) lower regions compressed by increased perfusion 4) absorption atelectasis at higher oxygen concentrations
11
Q
Ventilation settings include:
A
- Inspiratory pressure or tidal volume driven: depending on mode
- RR
- PEEP: required for gas exchange
- FiO2: oxygen requirement for gas exchange
- I:E ratio: manipulate length in inspiration or expiration to either help with oxygenation (2:1) or CO2 removal (1:3).
12
Q
Invasive mechanical ventilation can be controlled by:
A
- Pressure controlled
- Volume controlled
- Dual mode
13
Q
Pressure controlled ventilation means:
A
- Respiratory rate, inspiratory time are pre-set. Flow is delivered to a pre-set target pressure limit during inspiration until target pre-set pressure is reached & then expiration is allowed to happen passively.
- Pressure is constant and set so the volume can change from breath to breath depending on lung compliance. Better lung compliance leads to larger lung volume, poorer lung compliance leads to smaller volumes and does not guarantee adequate amount of volume, i.e. airway obstructed the pressure will be reached very quickly therefore only a small volume of gas is delivered. Hence, poor compliance may suggest areas of collapse and sputum retention
14
Q
Volume controlled ventilation means:
A
- Inspiratory time, pause time and respiratory rate are all pre-set. Ventilator delivers a pre-set tidal volume.
- Airway pressure rises slowly as the ventilator reaches the desired volume (normal TV for age, gender) during inspiration and once reached expiration is allowed to occur passively.
- Peak airway pressure will vary from breath to breath as this mode is volume controlled and the ventilator will deliver its set volume irrespective of variations in lung compliance and resistance to flow. If low lung compliance patient at risk of barotrauma hence pneumothorax, clinically ventilators are advanced enough with pressure detection to prevent barotrauma.
15
Q
Dual mode controlled ventilation means:
A
- Combines volume control and pressure control in an attempt to avoid barotrauma but maintain good lung volumes.
- Delivers a pre-set volume with the lowest possible pressure. If the volume falls below the pre set value the pressure level rises but only to a point (upper pressure limit). Expiration remains passive
- If the upper pressure limit is reached before the ventilator can deliver the appropriate amount of volume that has been set, the ventilator will alarm indicating setting need updating.
16
Q
Main advantage of pressure controlled ventilation:
A
pressure can be controlled reducing the risk of barotrauma and volutrauma (overdistention of normal alveoli) in patients with stiff lungs
17
Q
Main advantage of volume controlled ventilation:
A
reduces risk of collapse and sputum retention
18
Q
Mechanical ventilation modes:
A
- Spontaneous modes: Pressure Support (PS)/Assisted Spontaneous Breath (ASB), Biphasic positive airway pressure (BiPAP) and CPAP need the patient to be able to initiate a breath or they won’t provide any support for ventilation
- Synchronised Intermittent Mandatory Ventilation (SIMV): Automode allows for some synchronisation with the patients effort.
- Controlled Mandatory Ventilation (CMV): Fully controlled by the machine
19
Q
Pressure support (PS) or AKA Assisted spontaneous Breath (ASB) indications:
A
Self-breathing, to reduce ventilatory support and increase breath time.
20
Q
Volume support indications:
A
Self-breathing, to reduce ventilatory support and increase breath time
21
Q
How does PS/ASB work:
A
- A Spontaneous mode: so the patient must trigger the machine or there will be no breath given
- Provides a pre-set pressure boost to each breath. Pressure support/ASB is more common than Volume Support
22
Q
How does VS work:
A
- Spontaneous mode: so the patient must trigger the machine or there will be no breath given
- A set tidal volume is delivered with different pressure support from the ventilator depending on the patients effort/activity. Volume support might not be universally used but used at KGH due to the ventilators that are used there.
23
Q
CPAP/BiPAP indications:
A
Invasive: Self-breathing, to reduce ventilatory support and increase breath time.
Non-invasive: weaning from full mechanical ventilation once patients are extubated or can be the “ceiling” of care for some when invasive ventilation with sedation is not appropriate
24
Q
How does CPAP work:
A
- Spontaneous mode: Provides positive pressure but with no mandatory breaths so the patient has to breathe spontaneously.
It increases FRC improving gas exchange by splinting open alveoli increasing PEEP. - Unlike BIPAP - CPAP delivers the same flow of gas through inspiration as expiration increasing PEEP.
- CPAP can be delivered non-invasively via a face mask or invasively through an ETT by a ventilator
25
How does BiPAP work:
- Pressure controlled mode giving the patient unrestricted opportunities for spontaneous breathing at pre-set high and low pressure levels.
- Uses 2 shifting pressure levels- IPAP and EPAP
- Can be delivered non-invasively via a face mask or invasively through an ETT by a ventilator
26
Indications for Automode:
Partial breathing, allows for weaning from full mechanical ventilation
27
How does automode work:
Interactive mode: Allows patient to receive a supported breath if triggered or a mandatory breath if not. Automode might not be widely available but used at KGH
28
Indications for CMV:
Non-breathing requiring mandatory breaths. Often used in high levels of sedation and/or paralysis.
29
How does CMV work:
Delivers set no. of breaths and is either volume or pressure controlled. No option for patient to breath spontaneously.
30
Other modes of mechanical ventilation include:
- High Frequency Oscillation Ventilation (HFOV): Works on principle of maximum recruitment of all alveoli for maximal expansion followed with small TV at great rates up to 600bpm. Often seen in extremely unwell and/or paediatrics, used less commonly.
- Adaptive Supportive Ventilation (ASV): Advanced mode. Patient data is input (height and ideal BW) to calculate a minute volume (volume of gas required in over a minute for adequate oxygenation) that is maintained, with adjustments as appropriate (fully sedated it will deliver all, waking up some of it). Very common and often seen as a weaning type mode.
31
In mechanical ventilation there is always an aim to:
to reduce ventilator support and increase patient contribution to ventilation of lungs. Ventilator mode indicates level of support required for the patient
32
What is PEEP and why is it used?
- Positive end expiratory pressure: positive pressure applied at the end of expiration.
- On mechanical ventilation it is difficult to maintain opening of all alveoli as ventilation favours non-dependent regions by taking path of least resistance to already well ventilated areas resulting in vulnerable alveoli that are prone to collapse on expiration (alveolar collapse). Applying PEEP will assist in splinting of these alveoli preventing alveolar collapse.
33
Weaning off ventilator procedure:
- Weaning may be consultant preference or protocol led. Evidence suggests protocol is more effective - reduces length of time of ventilation and on critical care unit and carries higher success rate of extubation (removal of ETT) without intubation recurrence.
- Introduction to ventilator independence: reduces support from ventilator until spontaneous breathing and then breath time is gradually increased.
- Management of artificial airway
34
Failure to wean may be due to:
- Load: often original problem has not fully resolved or secondary problem: Bronchospasm, LVF, Sepsis, Pyrexia, Fitting, Increased secretions, hyperinflation
- Lack of drive: Sedation, CNS problems, Hypercapnia, Motivation, Psychological issues
- Capacity of pump/ability to breath: pain/discomfort, abdominal discomfort/distention from constipation secondary to immobility, poor positioning, paralysing agents not worn off, dysfunctional diaphragm
- Other: Hb, Anxiety, Fear, Sensory overload/deprivation (common in ITU), Communication/depression
35
What is a tracheostomy
is a surgical procedure which consists of making an incision on the anterior aspect of the neck and opening a direct airway through an incision in the anterior wall of the trachea to facilitate ventilation/respiration
36
Types of tracheostomy include:
Surgical
| Percutaneous
37
Surgical tracheostomy is:
Patient in supine head will be extended and under GA an incision of approx 2-3cm to the second tracheal ring is made. Then an incision through the central part of the thyroid gland (thyroid isthmus) is made and divided. Hole made between 3rd and 4th tracheal ring and anterior portion of tracheal ring is removed. The tracheostomy tube is then inserted
38
Percutaneous tracheostomy is:
Placement of tracheostomy under guide wires (fine wire) and dilators. Guide wire placed between 1st and 2nd tracheal ring then gradually hole size is increased using dilators of varying sizes that are passed through the guide wire to stretch the skin wide enough to allow for tracheostomy to pass in. Can be performed in bedspace in ITU. Sometimes a bronchoscope is used to ensure correct placement of the tube
39
Indications for tracheostomy include:
- To maintain an airway: in those who cannot maintain their own
- To bypass possible or actual upper airway obstructions: congenital defect, trauma following head and neck surgery, infection/inflammation, tumour
- Protection of tracheo-bronchial tree: prevent aspiration risk from food, vomit, blood
- To assist in removal of bronchial secretions
- Prolonged need for artificial ventilation: deemed more comfortable, enables eating, drinking, talking
- To facilitate weaning from a ventilator: reduces anatomical dead space by 150ml
- Total laryngectomy: often performed due to Ca
40
Complications of tracheostomy include:
- Blocked/displaced tubes: life-threatening
Infection
- Long term tracheal damage
- Aspiration risk: if tube pulls down and tethers tissue making it more difficult to swallow
- Psychological effects: fear of blockage, dependent rel. reduced WOB
- Scar formation
- Long term vocal cord damage
- Drying of secretions
- Loss of normal filtering systems: more risk of infection
- Reduced mucociliary transport
- Reduced airway pressure: reduced PEEP due to trachea being always open (glottis bypassed) results in atelectasis
41
Humidification can be increased in tracheostomy by:
- Hydration: tripling fluid intake increases fluidity of secretions by 2/3
- Warm/cold water systems: considered in O2 therapy
- Nebulisers
- Saline instillation: directly down tracheostomy tube. Not recommended as standard practice but can be used if secretions are extremely thick
- Swedish nose/thermovent: only if not on O2 therapy. Cardboard roll that catches moisture and heat of expelled air that is then used on the next breath in.
- Buchanan bibs: moistened piece of cloth over tracheostomy. Washed daily
42
Patient criteria for weaning tracheostomies includes:
- Primary cause resolved
- Adequate nutritional state: patient will be working harder and will require greater energy
- Adequate sleep
- Psychological support: full aware of what is going to happen
- Able to protect airway
- Adequate ventilatory reserve
- Spontaneous breathing off ventilator for 24–48 hrs
- O2 <40 %
- Manageable secretions
- CVS stable
43
Questions to ask in regards to suitability to weaning for tracheostomy includes:
1) Do they need a tracheostomy? 2) should we start weaning? 3) if YES then is it important to start weaning immediately or will a start date be more appropriate?
44
Process of weaning tracheostomies includes:
```
Mechanical ventilation
↓
CPAP
↓
Trachy Mask
↓
Deflate cuff
↓
Speaking valve
↓
Decannulation cap: blocks tube completely, expect patient to breath past tube independently
↓
Decannulation (+/- Minitracheostomy: for sputum clearance via suctioning)
```
45
Importance of weaning and decannulation of tracheostomies is:
- ↓ risk of complications
- ↓ patient stress
- Psychological boost for patient
- May promote speed of recovery
- Cost savings
- ↓ dependency of patient on MDT
46
Continuation of tracheostomy is indicated when:
- Upper airway obstruction permanently
- Severe neurological deficit
- Inability to maintain own airway
- Persistent severe aspiration
- Severely reduced lung compliance
47
Features of tracheostomy tubes include:
Depending on type of tube it may or may not have all the features:
- Shaft: main part
- Flange: prevents tube from falling into person. On the outside of the body
- Cuff: Balloon to seal off airways to ensure air passes only passes through the tube. Not on all tubes
- Pilot balloon: entry port to inject air in to inflate the cuff
15mm connector: for all emergency equipment can attach to should a respiratory event occur. Standardised size on all tubes
- +/- inner tube
- Attachments – speaking valves, caps and spigots
48
Benefits of tracheostomies include:
- ↑patient mobility and patient comfort
- Ease for suctioning
- Aids weaning from mechanical ventilation
↓ anatomical dead space: by 150ml reducing WOB
- Enables/assists communication
- Enables oral intake
- ↓risk of infection
49
Failed decannulation occurs due to:
- Decreased saturations
- Changes in heart rate (ECG)
- Increased respiratory rate
- Increased work of breathing
- Inability to cough and expectorate
- Fatigue
- Stridor
Intro to Practice 3 C/R
flashcards
Decks in class (17)
# Cards
-
Assessment13
-
Auscultation17
-
CXR16
-
Positioning + Lung Function21
-
Chest X Ray Abnormalities5
-
Breathing Re-education & Sputum Management55
-
General Anaesthesia22
-
Management of volume loss26
-
Paediatric Respiratory Care19
-
ABGs24
-
Respiratory Failure23
-
O2 Therapy36
-
Management of Breathlessness43
-
Critical Care39
-
Mechanical Ventilation49
-
Management of volume loss in ITU16
-
Mobilisation18
