Volatile anaesthetics:

 

Halothane

Isoflurane

Enflurane

Methoxyflurane

Desflurane

Sevoflurane

Nitrous oxide

Xenon

Molecular weight

198

185

185

165

168

200

44

131

Boiling point (°C)

50

49

57

105

24

59

-88

-108

Saturated vapour pressure

243

238

172

22.5

669

157

 

 

MAC

0.75%

1.2%

1.7%

0.16%

6.6%

1.8-2.3%

105%

71%

Blood-gas PC

2.4

1.4

1.8

12

0.42

0.69

0.47

0.14

Muscle-blood PC

 

2.9

 

 

2.0

3.1

1.2

 

Brain-blood PC

 

1.6

 

 

1.3

1.7

 

 

Fat-blood PC

60

45

 

400

27

48

2.3

 

Oil-gas PC

224

98

98

950

29

80

1.4

1.9

% Metabolised

20

0.2

2

70

0.02

2-5

0.004

0

Smell

Sweet

Irritant

Sweet

Sweet

Irritant

Sweet

Sweet

Nil

Analgesic

 

 

 

Yes

 

 

Yes

Yes

 

IV induction agents:

 

Thiopentone

Methohexital

Propofol

Ketamine

Etomidate

Midazolam

Induction dose (mg/kg)

3.5-7

1-1.5

1-2

 

 

 

VDSS (L/kg)

2.5

2

4

3

3

1.5

Cl (mL/kg/min)

3.5

11

30-60

17

10-20

10

t1/2α (mins)

8 (t1/2α fast)

60 (t1/2α slow)

 

2 (t1/2α fast)

?20 ?50 (t1/2α slow)

11

 

 

t1/2β (hours)

6-15

3-5

5-12

2

1-4

1-4

t1/2ke0 (mins)

1.2

?

2.6

0.5

1.5

4

Plasma protein binding (%)

80

60

98

25

75

97

Active metabolites

Pentobarbital

Others

Minimal

No

Norketamine (30% as active)

No

Oxazepam

α-OH-midazolam

pKa

7.6 (acid)

8.7 (acid)

11 (acid)

7.5 (base)

18.8 (acid)

4.5 (base)

6.5 (base)

pH at presentation

10.5

7.2

7.5

4.5

6

3.5

% unionized at pH 7.4

12% free ionized

8% free unionized

76%

>99%

?

>99%

90%

 

Opioids:

 

% Plasma protein bound

t1/2β (mins)

VDss (L/kg)

Cl (mL/kg/min)

pKa

% unionized at pH 7.4

Lipid solubility (octanol:water)

Morphine

35

170

3.5

16

8

23

1

Pethidine

60

210

4

12

8.5

5

30

Fentanyl

83

190

4

13

8.4

9

600

Alfentanil

90

100

0.6

6

6.5

89

90

Sufentanil

90

160

1.7

13

8

23

1700

Remifentanil

70

10

0.3

40

7.1

68

20

Methadone

90

15-60 hours

6

6

8.6

?

115

Oxycodone

45

200

2.5

13

8.5

5

1

 

Local anaesthetics:

 

Lipid solubility

Toxic conc (mcg/mL)

Onset

Duration

% plasma protein bound

pKa

% unionised @ pH 7.4

Potency

t1/2β

Amethocaine

200

?

Slow

Long

75

8.5

7

8

80

Cocaine

?

0.5

Medium

Short

95

8.6

5

1

100

Lignocaine

150

5

Fast

Medium

70

7.9

25

2

100

Prilocaine

50

5

Fast

Medium

55

7.7

33

2

100

Bupivacaine

1000

1.5

Medium

Long

95

8.1

15

8

160

Ropivacaine

300

4

Medium

Long

94

8.1

15

8

120

Mepivacaine

150

5

Short

Medium

77

7.6

40

2

115

 

Muscle relaxants:

 

Rocuronium

Vecuronium

Pancuronium

Atracurium

Cisatracurium

Mivacurium

Tubocurarine

ED95

0.31

0.04

0.07

0.2

0.04

0.08

0.5

Onset

Fast

Medium

Medium

Medium

Medium

Medium

Slow

Duration

Medium

Medium

Long

Medium

Medium

Short

Long

CVS side effects

 

 

Tachycardia

 

 

 

Autonomic ganglion blockade

Histamine release

 

 

 

Yes

 

Yes

Yes

% plasma protein bound

10

10

20-60

15

15

10

30-50

VDss (L/kg)

0.2

0.23

0.27

0.15

0.15

0.21-0.32

0.3

% Metabolised

<5

20

30

90

95

90

0

% Into bile

60

70

20

0

0

0

30

% Into urine

40

30

80

10

5

5

70

 

Medical gases and water:

 

Oxygen

Nitrogen

Nitrous oxide

Entonox

(Water)

Boiling point

-180°C

-196°C

-88°C

 

100°C

Critical temperature

-118°C

 

36.5°C

-5.5°C pseudo-CT

(separates)

374°C

Critical pressure

50atm

 

71atm

 

218atm

Triple point temperature

 

 

-91°C

 

0.01°C

Triple point pressure

 

 

 

 

0.006atm

Cylinder pressure

137 atm

 

44atm

 

 

E cylinder volume

680L

 

 

1800L

(400L when gas only)

 

 

J cylinder volume

6800L

 

 

 

 

 

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