ITU (Airway maintenance, ventilation, pulse oximetry and oxygen therapy) Flashcards
1
Q
In trauma patients what can cause airway obstruction?
A
- Coma due to loss of protective airway reflexes
- Blood or vomit may block the airway
- Direct trauma, haematoma or burns
2
Q
What are the signs of severe airway obstruction?
A
The patient cannot speak or breathe and attempts at coughing are silent
3
Q
How do you manage severe airway obstruction?
A
A cycle of 5 back blows and 5 abdominal thrusts
If loss of consciousness then commence ALS protocol to retrieve the object with forceps/ suction where possible
4
Q
What are the signs of a mild airway obstruction?
A
The patient can speak, cough and breathe
5
Q
How do you manage mild airway obstruction?
A
Encourage the patient to cough
6
Q
What is the first step to airway maintenance?
A
Look in the mouth and pharynx for foreign bodies, blood and vomit.
Remove any obstruction with Magill’s forceps or Yankauer sucker
7
Q
Describe the two basic manoeuvres for airway maintenance and when you would use each one
A
- Head tilt, chin lift - standard if no risk of c-spine injury
- Jaw thrust (place fingers behind angle of the mandible and apply anterior pressure. use the thumbs to open the mouth slightly) This is first line in any trauma patient (or chin lift without head tilt)
8
Q
How do you size a guedel airway?
A
Incisors to the angle of the mandible (most adults require size 3)
9
Q
How do you insert a guedel airway and why?
A
Insert upside down and rotate
to avoid pushing the tongue backwards
10
Q
When can you not use a nasopharyngeal airway?
A
If there is a risk of basal skull fracture
11
Q
How do you size a nasopharyngeal airway?
A
Incisors to the tragus (most men are 7.0 and women are 6.0)
12
Q
How do you insert a nasopharyngeal airway?
A
Insert lubricated by twisting along the floor of the nose
13
Q
What are some advantages of using LMAs over ET tubes?
A
- Prevent damage to the teeth or vocal cords
- Can be used to temporarily establish an airway before an ET tube is inserted (e.g. in ALS patients)
14
Q
What’s the difference between an i-gel and an LMA?
A
After an LMA has been inserted the cuff needs to be inflated but i-gels don’t require inflation
15
Q
When will Intubation be used over LMAs/ i-gels?
A
- Surgical procedures where there is a risk of vomiting and aspiration or where the patient has a difficult airway
- The patient is in an ICU setting and will likely need airway protection for a prolonged period of time
- In an acute setting as a superior alternative to an LMA/ i-gel
16
Q
What is usually used as a muscle relaxant in surgical patients before intubation and why?
A
Suxamethonium (short acting)
Muscle relaxation increases the ease of intubation
17
Q
When muscle relaxation can’t be used, e.g. in cardiac arrest patients, how are patients intubated?
A
- Position patient with neck and head extended
- Slide the laryngoscope blade down with the right side of the tongue into the vallecular (between the tongue and epiglottis) while protecting the teeth)
- Lift the laryngoscope blades and visualise the cords, pass the lubricated ET tube through them
- Remove the laryngoscope and inflate the cuff
18
Q
What patients make intubation difficult?
A
- Obese
- Short neck/ impaired neck flexion and extension
- Receding chin
- Protruding teeth
- TMJ disorder/ fractured mandible
19
Q
What is a needle cricothyroidotomy?
A
Used an emergency surgical airway in children
A large IV cannula is passed into the cricothyroid membrane (between the cricoid and thyroid cartilages)
20
Q
What is a surgical cricothyroidotomy?
A
Similar to percutaneous tracheostomy but specifically at the cricothyroid cartilage
21
Q
What is a percutaneous tracheostomy (PCT) and what technique is involved?
A
An airway that is inserted subglotically through the neck tissues directly into the trachea.
It involves the Seldinger technique and dilation of the trachea between cartilage rings before passing the tracheostomy tube
22
Q
When is PCT indicated?
A
- Bypassing upper airway obstruction
- Prolonged mechanical ventilation (as it is easier to wean patients from tracheostomy than it is from intubation)
- Requirement for airway protection and a need for frequent suctioning (airway toilet)
23
Q
What advantages are there for PCT compared to long term intubation?
A
- Easier to wean patients from tracheostomy
- Patients can communicate by phonation (if a fenestrated tube is used)
- Sedation can be reduced as it is more comfortable than an ET tube
- Nursing care in terms of mouth care and mobility is easier
24
Q
What are the complications of PCT?
A
At the time of insertion:
- Bleeding
- Hypoxaemia
- Loss of airway
- Injury to the posterior tracheal wall
- Pneumothorax
Later complications:
- Dislodgement and obstruction of the tube
- Tracheoesophageal fistula
- Stenosis of the trachea
- Swallow dysfunction
25
What should you do if you suspect aspiration of foreign material?
1. Apply cricoid pressure and use suction to remove debris from the mouth
2. Intubate with an ET tube and refrain from ventilating (if oxygen sats are adequate)
3. Empty the stomach with an NG tube
26
What are different types of artificial ventilation?
1. Mouth to mask ventilation
2. Bag - valve - mask ventilation
(pre-op or in an emergency prior to establishing a secure airway +/- mechanical ventilation)
3. Non-invasive ventilation (ventilatory support without using an invasive artificial airway. it is delivered via a sealed face mask, nasal mask or helmet)
4. Invasive mechanical ventilation
(requires intubation)
27
For Bag-valve-mask ventilation, by how much do you squeeze the bag and at what rate?
Squeeze 2/3 of the bag
| Rate of 10-12 breaths per minute
28
What are the indications for NIV?
In patients that require HDU level support but are not yet candidates for intubation.
Patients must be conscious and able to maintain their airway
29
What is the difference between CPAP and BiPAP and when are they used?
CPAP = continuous positive airway pressure
Used in T1RF
BiPAP = bi-level positive airway pressure (the air pressure increases during inspiration)
Used in T2RF
30
What should you increase to reduce hypercapnia?
iPAP
31
What should you increase to reduce hypoxia?
ePAP
32
What are the indications for Invasive mechanical ventilation?
- Respiratory or cardiorespiratory arrest (or impending arrest)
- NIV is failing to reduce PaCO2 or maintain SpO2
- Surgical procedures requiring paralysis
- A sedated patient in an ITU setting that is not self-ventilating
33
How do you make sure you get appropriate inspiratory and expiratory airway pressures with mechanical ventilation?
Titrate
- If patient is paralysed IPPV is used - with tidal vol and pressure altered as necessary
- PEEP is often used as an adjunct to this - helping splint open the alveoli and increase the SA for gas exchange
34
How much of the oxygen in the blood stream is bound to Hb?
Over 90%
35
How many molecules of oxygen must be bound to a molecule of Hb for it to be 100% saturated?
4 molecules of oxygen
36
What is oxygen saturation (SO2)?
Saturated Hb/ Total Hb x 100
37
How does pulse oximetry work?
A pulse oximeter uses two wavelengths of light, one high frequency in the visible spectrum (which picks up the different colour of saturated/ oxyhaemoglobin) and one close to the isobesetic point (which picks up both oxyhaemoglobin and Hb not bound to O2 so that gives you total Hb)
It used this to identify the % saturation of Hb in the bloodstream
It is calculated from the pulsatile (arterial) ends of the capillaries where there is variable absorption of light
38
What are some limitations of pulse oximetry?
Falsely low readings can occur in:
- Methaemoglobinaemia
- Injection of methylene blue or indocyanine green
- Fluorescent lighting
- Shivering
- Nail varnish
- Use of surgical diathermy
- Venous conjestion (e.g. tricuspid regurg, high airway pressure) will decrease pulsitility
Falsely high readings can occur in:
- Carboxyhaemoglobin
Other false readings can occur in:
- Poor perfusion
- Anaemia
Also:
- Older pulse oximeters can be inaccurate
- Doesn't give any information about CO2
39
How is it possible for a patient to desaturate even at a high PO2?
CO2 shifts the dissociation curve right (as well as low pH and high 2,3-DPG)
40
What is Capnography?
It is used to measure the level of CO2 in expired air during anaesthesia and critical care
(Most widely used way of measuring CO2 is with infra-red spectrometry - the amount of light absorbed is proportional to the concentration of CO2)
41
Describe a Capnogram
Expiration begins and line goes up then plateaus before inspiration begins causing the line to fall back to baseline. Then there is a pause before this repeats.
42
What can a capnograph be used for?
- Enables you to calculate RR
- Enables you to estimate PaCO2
- It can alert to disconnection or displacement of equipment, rebreathing and circuit failures and reduced pulmonary blood flow
43
When can errors be generated in capnography?
- Calibration errors
- Wrong sample site in the breathing equipment
- Blockages or water in the sampling hose
44
What is oxygen therapy?
The administration of oxygen at concentrations greater than in ambient air (21%) with the intent of treating or preventing hypoxia
45
What is SpO2?
Peripheral oxygen saturation
46
What is Sa02?
Arterial oxygen saturations
47
What is hypoxaemia and what can it lead to?
Hypoxaemia = when the partial pressure of oxygen in the blood is reduced
Can lead to hypoxia (insufficient oxygen reaching the body tissues)
48
What are the possible causes for low saturations?
- Respiratory disease e.g. pneumonia, ARDS, oedema, asthma, COPD
- Cardiac disease e.g. arrhythmias, ischaemia, oedema
- Other conditions particularly where there is raised RR, metabolic acidosis or hypotension e.g. trauma, neurological impairment, renal failure, liver failure
49
What is important to document when prescribing oxygen?
- The litres per minute the patient is receiving
- The percentage Fi02
- Target saturations
50
What oxygen saturations do healthy patients have?
Over 94%
51
What is the inspiratory flow rate in healthy patients?
25-30L/ min
52
What should be the target saturations in a patient not at risk of type 2 respiratory failure?
94-98%
53
What should be the target saturations in a patient at risk of type 2 respiratory failure?
88-92%
54
What is type 2 respiratory failure?
Hypoxic (PO2 less than 11) and Hypercapnic (PCO2 above 6kPa)
55
Which patients are at risk of type 2 respiratory failure?
- COPD
- Morbid obesity
- Chest wall disease
56
What are the signs of respiratory deterioration?
- Inc RR (esp above 30)
- Red SpO2
- Inc O2 dose needed to keep SpO2 in target range
- Inc EWS
- CO2 retention
- Drowsiness
- Headache
- Flushed face
- Tremor
57
If the patient is not at risk of type 2 respiratory failure but needs oxygen (and is self ventilating) how would you deliver oxygen (give stepwise)?
1. Nasal cannulae 1 litre/ min
2. Nasal cannulae 2 litres/ min
3. Nasal cannulae 4 litres/ min
4. Simple face mask 5 litres/ min
5. Simple face mask 7 litres/ min
6. Reservoir mask/ non-rebreathe mask 15 litres/ min
58
If the patient is at risk of type 2 respiratory failure but needs oxygen (and is self ventilating) how would you deliver oxygen (give stepwise)?
1. Venturi 24% 2 litres/ min
2. Venturi 28% 4 litres/ min
3. Venturi 35% 8 litres/ min
4. Venturi 40% 10 litres/ min
5. Venturi 60% 15 litres/ min
6. Reservoir mask 15 litres/ min
59
What are the advantages of using nasal cannulae to deliver oxygen therapy?
- Comfortable
| - Well tolerated
60
How much more oxygen is delivered to a patient via nasal cannulae above air concentration for every extra litre/ min given?
3-4%
61
What are some of the disadvantages/ limitations of using nasal cannulae?
- The inspired oxygen concentration is dependent on rate, pattern (mouth vs nose) and depth of breathing
- Patients will breathe through their mouth as well as their nose
- Can only give up to 6L/min and anything above 4L/min can cause irritation
62
What type of breathing will achieve a higher FiO2 when delivering oxygen through nasal cannulae?
Slower, deeper breathing
63
What is the maximum amount of oxygen that can be given via nasal cannulae?
6L/min
64
When delivering oxygen through nasal cannulae, at what amount of oxygen can it start causing irritation?
4L/min
65
When delivering oxygen via a simple face mask (Hudson mask) what flow rate and concentration of oxygen is delivered?
35-50% oxygen at a flow rate of 5-10L/ min
66
If the mask is attached to 100% oxygen why is the patient not getting all of this oxygen?
There is extensive air entrainment through holes in the mask (as peak inspiratory flow rate is more than the hudson mask flow rate)
and because they are variable performance masks
67
What is meant by a variable performance mask?
They do not give a fixed inspired oxygen concentration and are dependent on the rate and depth of breathing
68
What can happen if simple face masks/ hudson masks are used long term?
Skin irritation and pressure sores
69
What are non-rebreathe masks and why are they used?
They are simple face masks with a reservoir bag attached
They can give a fixed oxygen concentration (as in expiration oxygen flows into the reservoir bag and a one way valve prevents expired air entering the reservoir bag. therefore in inspiration there is little dilution of inspired oxygen with room air)
70
What oxygen concentration and flow rate can be achieved with non rebreathe masks?
60-80% oxygen at a 10-15L/ min flow rate
71
Can non rebreathe masks be used long term? and why?
No - because the gas cannot be humidified
Long term oxygen therapy can dry out the nasal mucosa leading to nose bleeds and poor tracheobronchial clearance (humidification of air normally happens in the upper airways)
72
What is a venturi mask and when are they used?
A group of masks that will deliver fixed oxygen concentrations.
They generate a 30L/min flow rate at different ratios of entrained air and oxygen.
They are used when the inhaled oxygen concentration needs to be carefully calculated e.g. COPD
73
How do you know which venturi mask delivers what percentage of oxygen to the patient?
The venturi valves are colour coded according to the percentage of oxygen they deliver
74
Which device would you use to deliver oxygen in these types of patients:
Normal vital signs but lowered SaO2, post-operatively, Long term oxygen therapy
Nasal Cannulae
75
Which device would you use to deliver oxygen in these types of patients:
Chronic respiratory failure, CO2 retention, COPD
Venturi masks
76
Which device would you use to deliver oxygen in these types of patients:
Emergency situations e.g. severe asthma, LVF, pneumonia, trauma, sepsis
Non- rebreathe masks
77
What gas is in a white cylinder?
Medical oxygen
78
What gas is in a dark blue cylinder?
Medical N2O
79
What gas is in a back and white cylinder?
Medical air
80
What gas is in a dark blue and white cylinder?
Entonox
