Applied anatomy, physiology and pharmacology for IV sedation Flashcards

(77 cards)

1
Q
Minimal sedation:
1. responsiveness
2. airway
3. ventilation
4. cardiovascular
 (4)
A
  1. Normal response to verbal commands
  2. Airway unaffected
  3. Ventilation unaffected
  4. Cardiovascular unaffected
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2
Q
Moderate sedation:
1. responsiveness
2. airway
3. ventilation
4. cardiovascular
 (4)
A
  1. Purposeful response to verbal or tactile stimulation
  2. Airway maintained without intervention
  3. Ventilation adequate
  4. Cardiovascular usually maintained
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3
Q
Deep sedation:
1. responsiveness
2. airway
3. ventilation
4. cardiovascular
 (4)
A
  1. Purposeful response following repeated or painful stimulation
  2. Airway intervention may be required
    Ventilation may be inadequate
  3. Cardiovascular usually maintained
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4
Q
GA:
1. responsiveness
2. airway
3. ventilation
4. cardiovascular
 (4)
A
  1. Unrousable even with painful stimulation
  2. Airway intervention often required
  3. Ventilation frequently inadequate
  4. Cardiovascular may be impaired
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5
Q

5 parts of respiration (5)

A
  1. Ventilation of gas into and out of lungs
  2. Diffusion of gases from lungs into blood
  3. Transport of oxygen by blood to cells and transport away of carbon dioxide
  4. Diffusion of gases from blood to cells
  5. Oxidation: use of oxygen to produce energy within cell and production of carbon dioxide
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6
Q

Learn upper airway anatomy

A

Learn upper airway anatomy

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7
Q

Learn lower airway anatomy

A

Learn lower airway anatomy

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8
Q

Inspiration vs expiration (4)

A

Active vs passive
Initiated by diaphragm vs elastic recoil of lungs
Inspiration supported by intercostals, accessory muscles for more vigorous inhalation
Forced expiration involves abdominals and intercostals

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9
Q

Normal rate of ventilation

A

10-18 per minute

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10
Q

Gas exchange
-where
-how
(5)

A
Occurs within the alveoli
Wall single layer thick
0.2 micrometers
Adjacent to pulmonary capillary wall
Gases diffuse down concentration gradients
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11
Q

Action of haemoglobin (7)

A

O2 binds to haemoglobin
Each molecule can carry 4 O2 molecules
Carried within red blood cells
CaO2= 1.34 x Hb x SpO2
Rely on adequate circulation to transport to tissues
Delivery = CaO2 x Cardiac Output
Properties of haemoglobin mean it releases O2 when it gets to the tissues

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12
Q

Cellular respiration simple equation (5)

A

Glucose + 6O2 –> 6CO2 + 5H2O + ATP

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13
Q

Control of respiration (3)

A

Autonomic nervous system: brainstem, medulla and pons
Respiratory centre
Respond to blood CO2 levels

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14
Q

Monitoring respiration: basic clinical signs (4)

A

Respiratory rate 10-18 per minute
Depth of breathing
Pattern of breathing
Cyanosis

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15
Q

Monitoring respiration: advanced (2)

A
Pulse oximetry (mandatory)
Carbon dioxide monitoring (optional)
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16
Q

Limitations of pulse oximetry (5)

A
Ambient light
Movement 
Cold peripheries
Nail varnish
Measurement lag
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17
Q

What is capnography? (2)

A

Detected exhaled CO2 in breath

Usually via nasal prongs

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18
Q

How does capnography work? (3)

A

Waveform displayed on a monitor
Allows confirmation of adequate ventilation and an open airway
Patient has to be breathing through their nose

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19
Q

Name 2 respiratory complications (2)

A

Upper airway obstruction

Hypoventilation

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20
Q

Describe upper airway obstruction (3)

A

Sedation leads to a decrease in tone of the muscles of the pharynx
Leads to pharyngeal collapse, tongue falls against back wall of pharynx
Mild cases lead to partial airway obstruction, more severe leads to complete obstruction

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21
Q

Signs of airway obsruction (5)

A
Snoring
Stridor
Drop in O2 saturations
Loss of CO2 trace
Seesaw respiration
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22
Q

Management of airway obstruction (4)

A

Supplementary oxygen
Careful titration of sedation
Basic airway opening manoeuvres
Airway adjuncts

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23
Q

Detection of hypoventilation (2)

A

Monitoring of respiratory rate

Drop in oxygen saturation

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24
Q

Describe hypoventilation and its effects (4)

A

Sedative drugs also sedate the Respiratory center in the brain
Also reduce receptor sensitivity to CO2
Leads to reduced respiratory rate or complete cessation of breathing
CO2 levels can build up leading to narcosis

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25
Management of hypoventilation (2)
Reversal of sedation with Flumazenil or Naloxone | Assisted ventilation with self-inflating AMBU bag
26
Basic function of the CV system (2)
Deliver oxygenated blood to body organs and tissues for metabolism "Tissue perfusion"
27
``` What happens with inadequate perfusion in -cardiac ischaemia -cerebral ischaemia -lung (4) ```
Organs and tissues quickly begin to fail: - cardiac ischaemia --> angina --> MI - cerebral ischaemia --> faint/ collapse --> stroke - lung --> hypoxia
28
What is the main determinant of organ perfusion? (1)
Blood pressure
29
How is blood pressure displayed? (3)
systolic, diastolic and mean (MAP) | e.g. 120/60 (80)
30
How is the MAP calculated? (1)
Diastolic + 1/3 (systolic - diastolic) | -modern machines calculate it for you
31
What is a normal MAP? (1)
Around 80mmHg
32
What is autoregulation? (2)
Ensures adequate perfusion over a range of MAPs Limits will shift in people with chronic hypertension (graph)
33
What is blood pressure determined by? (2)
1. Cardiac output (CO) | 2. Systemic vascular resistance (SVR)
34
What is cardiac output? (1)
The amount of blood ejected by the heart per minute
35
What is the average cardiac output? (1)
5litres / min
36
How is cardiac output determined? (2)
By heart rate and stroke volume | -HR between 50-180 have little effect
37
When is stroke volume reduced? (3)
Dehydration / blood loss Ischaemic heart disease / heart failure Anaesthetic drugs
38
What is systemic vascular resistance? (2)
The resistance produced by the vascular system to the flow of blood, predominantly small arterioles throughout body
39
Effect of dilation and constriction on SVR (2)
Constriction increases SVR and hence BP | Dilation decreases SVR and hence BP
40
SVR is decreased by (3)
Sedative drugs Anaphylaxis Sepsis/ infection
41
Acute blood pressure control (3)
Baroreceptors in aortic arch and internal carotids Send signals to brain stem Autonomic nervous system alters rate and strength of heart contraction and constriction of blood vessels
42
Chronic blood pressure system (3)
Renin-angiotensin system Aldosterone Chronic regulation of blood sodium concentration and body fluid retention
43
Monitoring BP: basic clinical signs (5)
``` Heart rate (from pulse oximeter) Heart rhythm Conscious level Skin colour Capillary refill ```
44
Monitoring BP: advanced (2)
Non-invasive blood pressure (mandatory) | ECG monitoring
45
How does non-invasive blood pressure (NIBP) work? (3)
Automated machines Cuff around arm or calf Automatic cycling - every 5 minutes
46
What is NIBP affected by? (2)
Movement | Wrong size cuff
47
What is sedation? (1)
Is a continuum which extends from normal alert consciousness to complete unresponsiveness
48
ECG monitonitoring: what can it detect and when is it used? (2)
Used in pts with history of significant CV disease Can detect arrythmias and also signs of cardiac ischaemia and infarction Usually a 3-lead configuration
49
Name 3 cardiovascular complications (3)
1. Hypotension 2. Cardiac arrhythmias 3. Cardiac arrest
50
Causes of CV hypotension (2)
Vasodilation caused by sedative drugs | Some drugs decrease strength of heart contraction
51
Risk factors in CV hypotension (2)
Dose related | More likely to occur in elderly, and those with existing CV disease
52
Treatment for CV hypotension (5)
Prevention better than the cure! Pre-assessment of comorbidity (recent IHD) Stop administering agent Place patient head down and with feet elevated IV fluids may be required
53
Risk factors/ causes of cardiac arrhythmias (4)
Multi-factorial aetiology May be precipitated by adrenaline in LA More likely in elder and those with CVS disease Raised blood CO2 levels also increase risk
54
Treatment for cardiac arrhythmias (2)
Call for expert help | ALS standard algorithms
55
Commonly used drug types in moderate sedation (3)
Benzodiazepines: Midazolam Opiates: Fentanyl, Remifentanil Others: Propofol, Ketamine, Dexomethomedine
56
Mode of action of Midazolam
***
57
How is Midazolam given including onset, peak and duration? (5)
``` IV for moderate sedation -onset: 1-3mins -peak: 5-7mins -duration: 20-30mins Titrate dose to desired end-point e.g. slurring of speech ```
58
Dosing of midazolam (4)
Initial dose ≈ 2.5mg given over 2 minutes Wait at least 2 minutes for effect Subsequent doses of 1mg Usually no more than 5mg total
59
Midazolam: cautions (2)
Decrease initial dose to 1.5mg in the elderly | If used with a pre-med then reduce dose by 1/3
60
Advantages of Midazolam (3)
Quick onset Short action of duration Minimal cardiovascular effects
61
Adverse effects of Midazolam (2)
Respiratory depression | Airway obstruction
62
What does flumazenil do including onset and peak effect (3)
Reverse benzodiazepine effects quickly | Onset within 1-2mins, peak effect within 6-10mins
63
Dose of Flumazenil (2)
Dose of 200mcg every 1-2mins as required
64
What is fentanyl and what does it do including onset, peak and duration (5)
``` Man-made synthetic opiate drug Provides analgesia and sedation Onset: 1 - 2 mins Peak: 10 - 15 mins Duration: 30 - 60 mins ```
65
Dosing of Fentanyl (1)
25mcg (0.5ml) bolus up to 200mcg max
66
Advantages of Fentanyl (3)
Provides analgesia as well as sedation Fast onset Short duration of action
67
Adverse effects of Fentanyl (3)
Hypotension and bradycardia Respiratory depression Nausea and vomiting
68
Remifentanil: what is it and how it is administered? (3)
Ultra short acting opiate Very potent analgesic effect Has to be administered by continuous infusion via syringe driver
69
Advantages of Remifentanil (2)
Excellent analgesic properties | Extremely short duration of action (8 minutes)
70
Adverse effects of Remifentanil (3)
Hypotension Bradycardia Respiratory depression and apnoea
71
What is Propofol including onset and duration (3)
IV induction agent Onset: 30s Duration: 10-15mins
72
Dosage of Propofol (2)
10-20mg (1-2mls) every 5mins OR By continuous infusion
73
Advantages of Propofol (2)
Very potent sedative | Rapid onset
74
Adverse effects of Propofol (3)
Only for use by trained sedationist or anaesthetic staff Can rapidly progress to general anaesthesia Significant cardiovascular and respiratory depression
75
General tips for IV sedation (4)
Use single drug if possible - avoid ‘polypharmacy’ Give small incremental boluses to titrate effect in individual patient Easier to give a bit more than to deal with effects of giving too much Knowledge of time to onset and peak effect of the drug you are using
76
What is polypharmacy and what are the good aspects? (4)
Use of more than one drug Can have advantages Different drugs give different effects e.g. Opiate + Benzodiazepine gives both sedation and analgesia Giving a second drug means you can use less of the first drug and so potentially reducing side effects
77
Disadvantages of polypharmacy (3)
Opens the door for greater risk of overdosing and over-sedating patients Drugs with the same side effects will have synergistic action and make those side effects even more likely Must be aware of time to peak effect of the drugs you are using as not waiting for full effect of first drug may lead to dosing of 2nd drug peaking with 1st drug --> significant over-sedation and side effects