Equipment Flashcards
1
Q
What are the key components of an arterial line
A
500/1000mls pressurised bag of saline, stiff non compliant tubing, a transducer, a cable connecting it to the monitor and the arterial canula
2
Q
How does an arterial line work
A
Changes in blood pressure are transmitted via the fluid filled rigid tubing to the pressure transducer. The diaphragm in the transducer responds to these pressure changes which are changed into an electrical signal via the Wheatstone bridge. The electric signal is transmitted via the cable to a microprocessor, amplified and processed to display on the monitor
3
Q
What level do you zero an arterial line to
A
4th intercostal space, mid clavicular line
4
Q
If the art line trace looks like a hump, what is wrong and what causes this
A
It is over damped.
Causes by air bubbles, Long thin tubing, kinks in the line, clots, vasospasm
5
Q
What is resonance and damping
A
Resonance: the natural frequency of a system is the frequency at which it will ocsilate freely. Resonance is the amplification of a signal when it’s frequency is too close to that of the natural frequency of a system
Damping: is the process of the system absorbing the energy or amplification of the oscillations.
6
Q
How does a passey muir work
A
This is a speaking valve attached to a cuffed or uncuffed tracheostomy tube. This involves a one way valve attached to the ventilator / high flow or nothing that during inspiration opens but closes on expiration. Therefore air is forced around the tube and through the larynx.
7
Q
What should the cuff pressure be limited to in a trache
A
20-25
8
Q
Talk me through the bronchial tree
A
Right main bronchus splits into right upper lobar bronchus (leading to the apical segment of the right upper lobe), and the bronchus intermedius. Off the BI is the right middle and the right lower lobe bronchus.
Off the left main bronchus is the left upper which subdivides into the lingular, and the left lower lobe bronchus.
2 upper lobes, 3 middle lobes, 5 lower lobes
9
Q
Main risks of bronchoscopy
A
Hypoxia, difficult to ventilate, bronchospasm, hyperinflation (barrotrauma and pneumothorax) , raising the ICP, tachycardia, hypertension, bleeding/ damage to the airway.
10
Q
How does therapeutic hypothermia work
A
Decreased the metabolic rate of the brain which reduces the release of harmful molecules (e.g. free radicals) which stabilises cell membranes
11
Q
Which patients should be considered for TTM
A
TTM trial 2013
- Cardiac arrest with rosc
- <15mins between collapse and attempted rosc
- < 60mins between collapse and rosc
- Comatose and intubated
- Systolic > 90 with or without Inotropes
12
Q
Exclusions for TTM
A
Coma due to a neurological event
Sepsis
Not suitable for ITU
Bleeding / coagulopathy
13
Q
Complications from cooling
A
Arterial spasm
Bradycardia
Shivering
Hypokalaemia
14
Q
Effect of cooling on an abg
A
Reduction in measured pco2
Lower k, mg and phosphate
15
Q
How do we re-warm
A
0.2 -0.5 degrees each hour
16
Q
How does a PA catheter work ?
A
It is used to measure cardiac output based on the principle of thermodilution.
10mls of cold saline is injected at the proximal and the change in temperature is measured by a thermistor at the distal end. As per the Stuart Hamilton equation the cardiac output is inversely proportional to the change in temperature over time.
17
Q
Can you talk me through the pressures at each stage of the PA Catheters placement
A
Right atrial pressure 0-6mm
Right ventricular pressure 15-30/ 2-8 diastolic
Pulmonary artery 15-30/ 8-15 diastolic
Pulmonary Capillary wedge pressure 8-15
18
Q
Contraindications to an NG
A
Base of skull fracture
Oesophageal varicies
Coagulopathy
Nasal surgery
19
Q
How to estimate the length of an NG
A
Ear lobe to xiphisternum
20
Q
How far is an NJ inserted
A
100cm
21
Q
What are the physiological effects of NIV
A
Larger tidal volumes Reduces atelectasis Aids recruitment Reduces work of breathing Decreased left ventricular after load Reduces left and right ventricular preload
22
Q
What does the equipment for HFNC consist of
A
Nasal canula Face strap Heated circuit Oxygen air blender Heated humidifier
23
Q
What flow rates are delivered to the patient on HFNC
A
70l /min
24
Q
What inspiratory flow rates can a patient generate on HFNC
A
Up to 100l /min
25
Benefits of HFNC
Humidified and heated
Meets the inspiratory needs of the patient - Generate higher flow rates therefore exceed the patients peak inspiratory flow rates
Increase functional residual capacity of the patient
Lightweight
Oxygen dilution is reduced as you don’t entrain air
Wash out of deadspace- high flow rates wash out co2 in deadspace
26
What are ABCD in the arterial waveform
A peak systolic pressure
B diacrotic notch - closure of aortic valve
C map
D diastolic pressure
27
What is pulse pressure variation.
In a mechanically ventilated patient there will be changes in the arterial pressure due to respiration. PP variation is the maximum -minimum / mean of the 2 values and it is expressed as a %
28
What is pulse contour analysis
A measurement of stroke volume variation with each beat using the artierial waveform
It assumes vessel diameter changes are due to cardiac output.
29
Explain the fick principle
Blood flow to an organs can be calculated using a marker substance if the following info is know
The amount of substance taken up in unit/ time
The affluent concentration of marker substance
The effluent concentration of marker substance
30
What is an ultrasound wave
Sound at frequency greater than 20 k hz
31
What is the relationship between frequency velocity and wavelength
Velocity = wave length x frequency
32
How can you distinguish pericardial from pleural fluid on ECHO
Pericardial fluid lies in front of the descending aorta
33
What is the difference between a Minnesota and S-B tube
SB has 3 ports where as Minnesota tube has a 4th port for oesophageal suctioning
The Minnesota tube has 450-500mls in the gastric ballon whereas the SB has 250-300mls
34
How would you inserted a Minnesota tube
Test the ballon integrity and verify the volume with a manometer
Measure from Angle of the mouth to xiphisternum for an estimated depth
Insert the tube to the estimated length under direct Vision
Inflate the gastric ballon 50mls and X-ray to confirm position
Inflate the ballon in increments of 50mls to 450 and check pressure with manometer
Clamp and withdraw the tube and attach traction 500mls bag saline
Oesophageal ballon inflation to 40mmhg if required
35
What are the complications of a SBT or Minnesota tube
```
Migration of ballon resulting in via us perforation
Necrosis or oesophagus
Aspiration pneumonia
Mouth or nose pressure damage
Cardiac arrhythmia
```
36
What are the effects on the respiratory system from using cold dry gas
```
Mucosal dysfunction
Mucosal or epithelium lesions
Decreased compliance
Decreased frc
Increased energy expenditure
```
37
In what situations might a heat and moisture exchanger not perform as well as normal
Expired volume is less than inspired (BP fistula)
Hypothermia
High minute ventilation.
38
What are the risks associated with the use of an Heat and moisture exchanger
Obstruction due to secretions blood or vomit
Increased dead space
Increased expiratory resistance
39
How can condensation in the ventilation tubing circuit cause problems when using active humidification
Obstruction of the ventilator circuit
Auto trigger the ventilator
Increased risk of Infection
40
How can you reduce the risk of condensation in the circuit during active humidification
Heat the circuit distal to the humidifier
Add a heated expiratory filter to the circuit
Add a water trap
41
What is the Doppler effect
When a wave strikes a moving object the reflected wave undergoes a proportional change in frequency depending on the velocity of the object.
Increase in frequency when it comes towards and decrease when it moves away
42
How does tcd work
Vasospasm developed due to narrowing of the inter cranial arteries causing a reduction in blood flow and increase in mean blood velocity. Tcd uses Doppler to measure the increase in velocity of blood
43
What is the lingaard ratio
Ratio of blood velocity in MCA to the velocity in the intercranial artery on the same side
Helps to distinguish hyperaemia from vasospasm
> 3 mild / mod vasospasm
> 6 severe
44
When are patients at greatest risk of vasospasm following an SAH
3-14 days
45
What are the uses of capnography in critical care
Et tube placement
Adequate ventilation
Identify bronchospasm
Identify low cardiac output states
46
How is partial pressure ofco2 measures on critical care
Infrared spectrography
47
How can the absorption of IR light be used to measure the partial pressure of co2
The absorption of ir light at 4.3 is proportional to the concentration of pco2
By measuring the degree of absorption and comparing it to references the partial pressure can be determined
48
2 methods of IR capnography
Main stream
| Side stream analysers
49
What do the four phases of capnography waveform represent
Phase 1: expiration of co2 from the anatomical dead space
Phase 2: mixed gas from airways and alveoli
Phase 3: gas leaving the alveoli
Phase 0: inspiration
50
What is the difference between end tidal and arterial partial pressure of co2 and why
End tidal usually 2-5 lower due to effect of alveolar dead space (ventilated but not perfused)
51
Indications for RRT
```
Severe metabolic acidosis
Symptomatic uraemia
Fluid overload resistant medical mx
Hyperkalaemia resistant to medical mx
Poisoning
```
52
What is the definition of dose with regards to RrT
The volume of blood purified per unit time
53
What medications are used for RrT anticoagulants
Citrate
UF heparin
LMWH
Prostacyclin
54
What are the risk factors for citrate toxicity with citrate RrT
```
Hepatic dysfunction
Hypocalcaemia
Hypoalbuminaemia
Hupothermia
Low cardiac output
```
55
What ph range is used for correct ng placement
1- 5.5
56
Describe how to perform a nex measurement for ngt placement
Hold exit port to top of nose
Extend length to earlobe
Extend length to xiphisternum
57
Five questions for correct NG placement
Most recent X-ray
Contours of the oesophagus bisect carina
Cross diaphragm in midline
Visible below HD
58
Causes of damped aerial line trace
```
Narrow tube
Bubbles
Kinked
Arterial spasm
Clot
Poor flush bag pressure
Over compliant tubing
```
59
What changes are seen on an art line when a patient has vasodilation
Wide pulse pressure
Low systolic and diastolic bp
Delayed dicrotic notch
60
What drugs can be used to maintain distal perfusion after accidental injection of a drug
```
Heparin
Steroids
NSAIDs
Prostacyclin
thrombolysis
Ca Chanel blockers
```
61
Indications for tracheostomy
```
Upper airway obstruction
Airway protection
Wean from mechanical support
Secretion management
Long term ventilation in neuro msk injury
```
62
What is the appropriate size of a trache tube
No larger 3/4 size of the internal diameter
63
How often measure cuff pressure
| Of a trache
8 hourly
64
Maximum cuff pressure of a trache
25 cm h20
65
How frequently should an established trache’s inner canula be changed
30 days
66
Which patients benefit from an adjustable flange
Obese
Large neck
Anatomical - mediastinal mass or burns
Low lying trache
67
What was the outcome of Tracman study
Compared trache early (around day 4) vs late (at 10days )
All cause mortality at 30 days same (30%)
No effect on critical care LOS
No effect hospital LOS
Decrease in sedation with early
68
What are the benefits of work place based assessments
The learner takes ownership of the assessment- promoting active learning
The assessment has high construct and content validity
The assessment is timely
The assessment is structured
The assessment is formative and promotes future learning and development
69
Which canulation configurations are used for Ecmo
Venous venous
Central
Venous arterial
70
What are the disadvantages of va Ecmo compared to vv
Risk of arterial canulation
Arterial embolisation
Impaired pulmonary / coronary/ cerebral perfusion
Increased lv afterload
71
What are the potential canula options for VV Ecmo
IJ to femoral
Femoral to femoral
Single dual lumen in IJ or femoral
72
What are the key components of Ecmo
```
Cannula
Blender
Oxygenator
Heat exchanger
Centrifugal pump
Interface/ console
```
73
How to reduce recirculation of oxygenated blood within the Ecmo circuit
Adjust cannula position
use dual lumen cannula
Change to VA Ecmo
74
Contraindications to an Intraosseous needle
```
Bone injury at or proximal to site
Acute ischaemic limb or compartment syndrome
Burn
skin or bone infection
Osteoporosis/ bone fragility
```
75
Sites for IO insertion
```
Proximal tibia
Proximal humerus
Distal tibia
Distal femur
Iliac crest
```
76
Confirmation of positioning of io needle
Loss of resistance
Stability of the needle
Aspiration of bone marrow
2mls flush without swelling or resistance
77
Complications of io insertion
```
Malposition
Pain
Extravisation
Compartment syndrome
Infection
Damage to surrounding structures
Disruption of growth plate
```
78
Which blood tests poorly correlate when taken IO
```
White cell count
Platelet
Sodium
Potassium
Calcium
Co2
```
79
What view drains the proximal tibia, the distal tibia and the proximal humerus
PT- popliteal vein
DT- great saphenous
Proximal h- axillary
80
What material is an ET tube made from
Polyvinyl chloride
81
What is murphy’s eye and what is it for
Side hole near tip of ET
| Allows gas flow should the end become occluded
82
What is the diameter of the connection at the proximal end of the ET
15 mm
83
What is the significance of the code IT in reference to an ET tube
Denotes it has been tested to confirm tissue compatibility
84
Indications for a double lumen tube
Massive pulmonary haemorrhage
Bronchopleural fistula
Protection of transplanted lung from high pressures
Whole lung lavage
85
How does a right differ from a left Double lumen tube
The right sided tube has a ventilation slot to allow for ventilation of the right upper lobe
86
Describe the insertion technique for a blind left sided double lumen tube
Insert a stylet into the DLT and perform direct laryngoscopy
Insert the dlt through laryngeal inlet with curved tip facing up
Remove the stylet rotate dlt 90 degrees anti-clockwise and advance to resistance
Inflate tracheal cuff
Confirm etco2
Clamp proximaly to the tracheal cap and inflate the bronchial cuff so that left lung is ventilated. Release clamp and replace cap.
Confirm position with fibre optic bronch
87
What are the risks of a blood transfusion.
```
Incorrect administration
Viral infection 1:1.3 million
Bacterial contamination
Allergy
Taco
Trali
Febrile reaction 1:75
Urticaria 1:100
No longer give blood
```
88
How to optimise view on direct laryngoscopy
```
Optimise head and neck position
Adequate neuromuscular blockade
Attempt with different blade or size
Video laryngoscopy
External laryngeal manipulation
Remove cricoid
```
89
Recommended max attempts at
| Laryngoscopy
3 plus 1 expert
90
What is the purpose of a ventricular assist device
Supports or replaces the right and left ventricular function
91
How can you classify a VAD
- ventricle supported: right, left, both
- type of pump; pulsitile , axial flow (impella) centrifugal
- extra corporeal or Intracorporeal
92
Where does an lvad and RVad take blood from and to
Left ventricle to the aorta
| Right ventricle to the pulmonary artery
93
Indications for a VAD
Bridge to recovery - myocarditis, post transplant
Bridge to transplant- heart failure
Permanent
94
What is the x descent
Atrial relaxation
95
What is an A C V wave
A is atrial contraction
C closure of TV
V atrial filling prior to TV opening
96
What would be seen on the CVP wave form with significant Tricuspid regurgitation
Enlarge V wave with no clear x decent
97
Causes of cannon A waves
Complete HB
VT
Junctional rhythm
Avnrt
(When atrial and ventricle contract simultaneously)
98
How is pulmonary hypertension defined
Mean pulmonary pressure > 25
| At rest on right heart catheterisation
99
What factors affect the fraction of Inspired oxygen via a standard face mask
Peak inspiratory flow rate
RR
OXygen flow rate
Mask fit
100
Why do masks have side holes
To entrain ambient air when the inspiratory flow exceeds oxygen flow
Alows expired gasses to be flushed out
101
How does a venturi mask provide a fixed fraction of inspired oxygen
The oxygen flows through a restriction in the nozzle. The size of the constriction determines the final concentration of oxygen for a given gas flow.
As the flow of oxygen passes through the constriction, a negative pressure is created.
The smaller the orifice is, the greater the negative pressure generated, so the more ambient air entrained, the lower the FiO2.
102
Which adult diseases could worsen with hyperoxic therapy
Stroke, copd, mi, head injury, acute lung injury, pulmonary fibrosis,
103
Primary function of an intra aortic balloon pump
Increase myocardial oxygen supply
Reduce afterload
Decrease myocardial oxygen demand
104
Why is the balloon of an IABP filled with helium
Helium has a low viscosity therefore travels quicker within the tubing and the risk of embolism is lower
105
Where should the tip of an IABp lie
2 cm distal to the origin of the left subcalavian
106
What are the absolute and relative contraindications of an IABp
Severe AR
Dissection
Aortic stents
No recovery
Severe pvd
Aortic aneurysm
Sepsis
Tachyarrythmias
107
What is lamberts law
The absorption of radiation by a substance is directly proportional to the thickness of the absorbing layer
108
What is an isosbestic point in pulse oximetry
590 and 805
| Wavelengths where absorption of light is equal for oxyhaemoglobin and deoxyhaemoglobin
109
Wave length of the two sources of light in a pulse oximetry
660
| 940
110
How does amyl nitrates cause methhaemoglobinaemia
Nitrates oxidise Haem from ferrous 2+ state to ferric 3+ state
Methaemoglobin increases the oxygen carrying capacity of the blood and prevents offloading in the peripheries
111
What shifts the oxygen dissociation curve left
Increase ph
Decreased temp, 23 DPG pco2
Presence of methaemoglobin
112
Treatment for amylnitrate poisioning
Methylene blue
| Oxygen
113
What distance should the pa catheter be inserted to be in the pulmonary artery occlusion pressure the pa and the rv
Rv 25
Pa 35
Paop 45
114
How to do an ssep
An electrical stimuli is delivered to a peripheral nerve
Scalp electrodes and positioned over the corresponding cortex
The eeg is then recorded to see if the amplitude changes
115
What are the different types of evoked potential measures
Brain stem Auditory EP- demyelinating or brain stem lesions
Visual EP- optic neuritis
Somatosensory and motor EP - prognostication
116
What depth place an oesophageal Doppler
Nasal - 40-45
| Mouth - 35-40
117
What does oesophageal Doppler measure
Velocity of blood flow in the descending aorta
118
What assumptions are made when deriving data from the oesophageal Doppler
The probe placement is optimal
The aorta is cylindrical
The normogram accurate calculates cross sectional area
No diastolic flow
119
```
On an oesophageal Doppler
What is the peak of the triangle
What is the area under the triangle
What is the upstroke of the triangle
What is the base of the triangle
```
Peak -peak velocity ( contractility)
Area - stroke distance(stroke vol)
Upstroke- mean acceleration
Base- flow time
120
Risks of a trache
```
Bleeding
Collapsed lung
Scaring windpipe
Oxygen / bp problems
Wound healing
Death
Change to voice
```
121
How is an image generated using a single bronchoscope
Led and distal camera
122
What is the difference between cleaning disinfecting and sterilising
Cleaning - removal of visible contamination
Disinfecting - removal of organisms able to cause infection
Sterilising - removal of all microbials
123
Methods of sterilising
Dry heat
Moist heat
Chemical
Irradiation.
124
What is the relationship between delivered current and thoracic impedance h
Delivered current = 1/ thoracic impedance
125
Components of a defib circuit
```
Transformer
Switch
Capacitor
Diode
Inductor coil
```
126
What is activated clotting time
Blood is added to a tube containing a surface activator which triggers the intrinsic pathways and the end point of clot formation is recorded.
Used on bypass or Ecmo - heparin is Troy rated to an act 400-600
127
How does teg work
```
Blood is inserted into 2 cups
Heated
A pin or torsion wire is inserted
Cups are rotated
As the clot forms the pin moves and forms a trace generated by a transducer
```
Uses kaolin as an activator to accelerate clotting
128
How does rotem work
Blood is placed into a cup
Sensory pin is inserted
Pin is attached to a mirror which triggers an LED and detector to generate trace
Extem extrinsic pathway
Intem intrinsic pathway
Fibtem platelet inhibitor - analysed fibrinogen
Aptem detects fibrinolysis
129
What does the r time or clotting time show and what should be given
Time until fibrin clot formation
Give ffp or pcc as it indicates if there are clotting factors
130
What does the maximum clot firmness or Ma Time show
| And what should be given
This is an indication of clot strength
Give platelets or cryoprecipitate
131
What does cryoprecipitate contain
Fibrinogen
Factor 7
Factor 8
Vwf
132
What does PCC contain
2 7 9 10
| Protein c and s
133
What is the k time or the clot formation time, and what should be given
Clot kinetics
Give ffp or platelet
134
What is cl30 or clot lysis time
| And what should be given
Represents fibrinolysis
Give txa
135
What are the benefits of bird
Increase lung volumes
Assist sputum clearance
Inspiratory muscle training
Improved oxygenation
136
What is another word for the bird
Intermittent positive pressure breathing
137
Tracheostomy approach
2 finger breaths above the sternal notch make a transverse incision
Blunt dissect to the tracheal rings
Needle puncture through between 1st and 2nd rings
Insert guide wire then dilate
138
Cricothyroidostomy approach
Stabilise thyroid cartilage with left hand
If palp-> horizontal stab, turn 90 then bougie and railroad tube 0.6
If not -> 8cm vertical incision, dissect to membrane, then horizontal -> vertical
139
What blood vessel is often in the way during a tracheostomy
Anterior jugular vein
140
How fast can you give fluid via an IO
150mls/ min
141
Gauge or IO needle
15g
142
Sites of IO access
```
Proximal humerus
Proximal tibia
Distal tibia
Femoral
Iliac crest
Sternum
```
143
Causes of epidural dense motor block
Large Bolus anaesthetic
Migration into subarachnoid or extradural
Epidural abscess
Epidural haematoma
144
When does a heat and moisture exchange filter not work optimally
Expired vol less than inspired
Hypothermia
High minute ventilation
145
Oxygenated blood wavelengths absorbed on pulse oximetry
Absorbs more infra- red (940)
Letting more red (660) pass through
146
How does capnography work
Infrared light is passed though gas and falls onto a sensor
| The presence of co2 decreases the light reaching the sensor and therefore changes the voltage in the circuit.
147
Which spinal needle has a short bevel cutting tip
Quincke type
148
Which spinal needle has an atraumatic pencil tip
Whitacre
149
What level does the spinal cord end
Typically it becomes the cauda equina l1-2
