Applied anatomy, physiology and pharmacology

Question 1

Define sedation

Answer 1

A continuum which extends from normal alert consciousness to complete unresponsiveness

Question 2

Minimal sedation responsiveness, airway, ventilation and cardiovascular effects?

Answer 2

Responsiveness - Normal response to verbal commands
Airway - Unaffected
Ventilation - Unaffected
Cardiovascular - Unaffected

Question 3

Moderate sedation responsiveness, airway, ventilation and cardiovascular effects?

Answer 3

Responsiveness - Purposeful response to verbal or tactile stimulation
Airway - Maintained without intervention
Ventilation - Adequate
Cardiovascular - Usually maintained

Question 4

Deep sedation responsiveness, airway, ventilation and cardiovascular effects?

Answer 4

Responsiveness - Purposeful response following repeated or painful stimulation
Airway - Intervention may be required
Ventilation - May be inadequate
Cardiovascular - Usually maintained

Question 5

GA responsiveness, airway, ventilation and cardiovascular effects?

Answer 5

Responsiveness - Unrousable even with painful stimulation
Airway - Intervention often required
Ventilation - Frequently inadequate
Cardiovascular - May be impaired

Question 6

Steps to respiration?

Answer 6

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

Question 7

Inspiration features?

Answer 7

Active process
Initiated by diaphragm
Supported by intercostals
Accessory muscles for more vigorous inhalation
Normal rate 10-18 per minute

Question 8

Expiration features?

Answer 8

Passive process
Elastic recoil of lung
Forced expiration involves abdominal and intercostals

Question 9

Where does pulmonary gas exchange occur?

Answer 9

Alveoli

Question 10

Alveoli features?

Answer 10

Wall single layer thick
0.2 micrometers
Adjacent to pulmonary capillary wall
Gas diffuses down concentration gradients

Question 11

How does delivery of O2 occur?

Answer 11

O2 binds to haemoglobin
Each molecule can carry 4 O2 molecules 
Carried within RBC
CaO2= 1.34 x Hb x SpO2
Delivery =  CaO2 x Cardiac Output
Properties of haemoglobin means it releases O2 when it gets to the tissues

Hb - Lungs - Resp centre - Tissues

Question 12

What does O2 delivery equal?

Answer 12

CaO2 x Cardiac Output

Question 13

What makes up the Autonomic Nervous System?

Answer 13

Brainstem, medulla, pons

Question 14

How to monitor the pt whilst sedated?

Answer 14

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

Advanced - pulse oximetry (mandatory), carbon dioxide monitoring (optional)

Question 15

Venous blood O2 and CO2 levels compared to air? How does this impact diffusion?

Answer 15

Venous blood has less O2 compared to air - diffuses out alveoli
Venous blood has more CO2 compared to air - diffuses into alveoli

Question 16

Cellular respiration?

Answer 16

Mitochondria uses O2 for metabolism

Question 17

CV system basic function?

Answer 17

Deliver oxygenated blood to body organs and tissues for metabolism
“tissue perfusion”

Question 18

What happens with inadequate perfusion?

Answer 18

Organs, tissues fail
Cardiac ischaemia - angina - myocardial infarct
Cerebral ischaemia - fain, collapse - stroke
Lung - hypoxia

Question 19

What is the main determinant of organ perfusion?

Answer 19

Blood pressure

- Systolic, diastolic and mean (MAP) 12060 (80)

Question 20

How to calculate MAP?

Answer 20

Diastolic + 1/3 (systolic - diastolic)

Question 21

What is the normal MAP?

Answer 21

80mmHg

Question 22

What determines BP?

Answer 22

Cardiac output

Systemic vascular resistance

Question 23

What is cardiac output?

Answer 23

Amount of blood ejected by the heart per minute - average 5 litres/min
Determined by HR and stroke volume
HR between 50-180 have little effect

Question 24

How to reduce stroke volume?

Answer 24

Dehydration/blood loss
Ischaemic heart disease/heart failure
- Anaesthetic drugs

Question 25

Systemic vascular resistance?

Answer 25

Resistance produced by the vascular system to the flow of blood Predominantly small arterioles throughout the body Constriction increases SVR and BP Dilation decreases SVR and BP

Question 26

How to decrease systemic vascular resistance?

Answer 26

Sedative drugs Anaphylaxis Sepsis/infec

Question 27

Acute control of BP?

Answer 27

Baroreceptors in aortic arch and internal carotids Send signals to brainstem Autonomic nervous system alters rate and strength of heart contraction and constriction of blood vessels

Question 28

Chronic control of BP?

Answer 28

Renin-angiotensin system Aldosterone Chronic regulation of blood sodium concentration and body fluid retention

Question 29

Drugs for moderate sedation?

Answer 29

Benzodiazepines - Midazolam Opiates - fentanyl, remifentanil Others - propofol, ketamine, dexomethomedine

Question 30

Midazolam mode of action?

Answer 30

--

Question 31

Midazolam features?

Answer 31

``` Benzodiazepine Given IV for moderate sedation Onset 1-3 mins Peak 5-7 mins Duration 20-30 mins Titrate dose to desired end point e.g. slurred speech ```

Question 32

Midazolam dosing? Cautions?

Answer 32

Initial dose 2.5mg given over 2 mins Wait 2 mins for effect Subsequent doses of 1mg Usually no more than 5mg Cautions - decrease initial dose to 1.5mg in the elderly If used with a pre-med then reduce dose by 1/3

Question 33

Midazolam advantages?

Answer 33

Quick onset Short action of duration Minimal CV effects

Question 34

Midazolam disadvantages?

Answer 34

Resp depression | Airway obstruction

Question 35

Flumazentil features?

Answer 35

Reverse benzodiazepine effects quickly Dose of 200mcg every 1-2 mins as required Onset within 1-2 minutes, peak effect within 6-10 minutes

Question 36

Fentanyl features?

Answer 36

``` Opiate Provides analgesia and sedation Onset 1-2 mins Peak 10-15 mins Duration 30-60 mins ``` Dosing 25mcg (0.5ml) bolus up to 200mcg max

Question 37

Fentanyl advantages?

Answer 37

Provides analgesia as well as sedation Fast onset Short duration of action

Question 38

Fentanyl adverse effects?

Answer 38

Hypotension and bradycardia Respiratory depression Nausea and vomiting

Question 39

Remifentanil features?

Answer 39

Ultra short acting opiate V potent analgesic effect Has to be administered by continuous infusion via syringe driver

Question 40

Remifentanil advantages?

Answer 40

Excellent analgesic properties | Extremely short duration of action (8 mins)

Question 41

Adverse effects of Remifentanil?

Answer 41

Hypotension Bradycardia Respiratory depression and apnoea

Question 42

Propofol features?

Answer 42

Intravenous anaesthetic induction agent Onset: 30 seconds Duration: 10 - 15 minutes Dosage: 10 - 20mg (1 -2 mls) every 5 minutes Or By continuous infusion

Question 43

Propofol advantages?

Answer 43

Very potent sedative | Rapid onset

Question 44

Propofol adverse effects?

Answer 44

Only for use by trained sedationist or anaesthetic staff Can rapidly progress to general anaesthesia Significant cardiovascular and respiratory depression

Question 45

Tips for sedation?

Answer 45

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

Question 46

Polypharmacy positives?

Answer 46

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

Question 47

Polypharmacy negatives?

Answer 47

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….. Midazolam 5 - 7 minutes Fentanyl 10 - 15 minutes Propofol 1 minute Not waiting for full effect of first drug may lead to dosing of second drug peaking with first drug Leads to significant over-sedation and side effects