Sevoflurane is not pungent and does not irritates respiratory tract

Question 22

Which of the following statement is wrong

a.       Sevoflurane has rapid onset and recovery

b.      Sevoflurane is pungent and irritates respiratory tract

c.       Desflurane has lower Blood Gas Partition Co Efficient than Sevoflurane

d.      Sevoflurane has lower MAC than Desflurane

Answer

b)      Sevoflurane is pungent and irritates respiratory tract

Reference

Katsung Page 403

QTDF :

Anaesthesia Books / Katsung

Quality

Thinker

Discussion

Anaesthetic	Blood : Gas Partition Co-efficient	Brain : Blood Partition Co-efficient	Minimal Alveolar Conc (MAC) (%)2	Remarks
Nitrous Oxide	0.47	1.1	> 100	Incomplete Anaesthetic. Rapid Onset and Recovery
Desflurane	0.42	1.3	6-7	Low Volatality. Poor Induction Agent. Rapid Recovery
Sevoflurane	0.69	1.7	2.0	Rapid Onset and Recovery. Unstable in Soda Lime
Isoflurane	1.40	2.6	1.4	Medium Rate of Onset and Recovery
Enflurane	1.80	1.4	1.7	Medium Rate of Onset and Recovery
Halothane	2.30	2.9	0.75	Medium Rate of Onset and Recovery
Methoxyflurane	12	2.0	0.16	Slow Onset and recovery

Explanation

a.       Sevoflurane (2,2,2-trifluoro-1-[trifluoromethyl]ethyl fluoromethyl ether), also called fluoromethyl hexafluoroisopropyl ether, has rapid onset and recovery

b.      Sevoflurane is a sweet-smelling, non-flammable, highly fluorinated methyl isopropyl ether which does not irriate the respiratory tract

c.       Desflurane has lower Blood Gas Partition Co Efficient (0.42) than Sevoflurane (0.67)

d.      Sevoflurane has lower MAC(2) than Desflurane(6-7)

Comments

Gas	Cylinder Colour		Pin Index	Pressure at 15oC
	In Other Countires	In USA		Lbf/in2	Bar
Oxygen(O2)	Black body with white shoulder	Green	2-5	1987	137
Nitrous Oxide (N2O)	French Blue	Blue	3-5	638	44
Cyclopropane	Orange	Orange	3-6	73	5
Carbon Di Oxide(CO2)	Grey	Grey	1-6	725	50
Halothane bottle	Amber
Ethylene bottle	Red
Helium (He)	Brown	Brown		1987	137
Entonoc	Blue body with white shoulder	Blue / Green	7	1987	137
Air	Grey body with B & White shoulder	Yellow	1-5	1987	137
O2/Helium	Black	Green / Brown	4-6,2-4	1987	137
O2/CO2	Black	Green / Grey	2-6,1-6	1987	137
Nitrogen			1-4

Tips

Few agents are in bottles rather than in cylinders

Gases	Bottle Colour
Halothane	Amber
Ethylene	Red

Sometimes the supply is through pipes and we have a few details here also

Gas	Hose Colour	Socket Colour	Pressure
Oxygen(O2)	White	White	4 Bar
Nitrous Oxide (N2O)	Blue	Blue	4 Bar
Air	Black	Black	7 Bar
Suction	Yellow	Yellow

The boiling points of the Anaesthetic agents also are worth remembering

Gas	Boiling Point
Ethylene Chloride	12.5 oC
Desflurane	23 oC
Ether	34.6 oC
Isoflurane	45.5 oC
Halothane	50 oC
Enflurane	56.5 oC
Sevoflurane	58.5 oC
Tricholoroethylene	86 oC
Nitrous Oxide	89 oC
Methoxyflurane	104 oC

Propofol is not contraindicated in Porphyria

Question 21

Which of the following statements about Propofol is not true

a.       It is Contraindicated in porphyria

b.      It does not trigger Malignant hyperthrermia"   Induction is rapid and recovery of consiousness after 4-7 minutes

c.       Post anaesthetic Performance of Mental, Manual and Mechanical task is back to normal within 1-2 hours

d.      Suited for Day care Surgery

Answer

a) It is contraindicated in Porphyria

Reference

Clinical Anaesthesia 3rd Edition - Morgan Page 173

Also can be Seen at

KDTripathi,4th Edition Page 352

Lee, 12th Edition, Page 417

Quality

Spotter

Status

Repeat

QTDF

All books give this

Discussion

Propofol is Di-Isopropylphenol

• It is prepared as an emulsion in 10% Soyabean oil and 1.2%egg phosphatide and 2.25%Glycerol
• Induction dose is 2-3 mg/kg
• Highly lipophilic
• 30%-40% of patients complain of pain/burning during injection.
• Induction is rapid and recovery of consiousness after 4-7 minutes
• Post anaesthetic Performance of Mental, Manual and Mechanical task is abck to normalwithin 1-2 hours
• Suited for Day care Surgery
• Safe for patients with Acute Intermittent Poyphyria
• It does not trigger Malignant hyperthrermia
• Hypotension is a common side effect
• Apnoea is common after induction and may last for 40-50 seconds
• Antioxidant
• Antiemetic
• Antipruritic

Explanation

a.       Propofol is NOT Contraindicated in porphyria

b.      It does not trigger Malignant hyperthrermia"   Induction is rapid and recovery of consiousness after 4-7 minutes

c.       Post anaesthetic Performance of Mental, Manual and Mechanical task is back to normal within 1-2 hours

d.      Propofol is Suited for Day care Surgery

Comments

We have seen that Propofol is the Anaesthesia of choice in Day care anaesthesis. The other agents that are used are

1.         Alfentanyl

2.         Remifentanyl

3.         Isoflurane

4.         Sevoflurane

5.         Desflurane

6.         Methohexitone

7.         Thiopentone

8.         Etomidate

Tips

ü      Another recently described rare, but serious, side effect is propofol infusion syndrome. This potentially lethal metabolic derangement has been reported in critically-ill patients after a prolonged infusion of high-dose propofol in combination with catecholamines and/or corticosteroids. [Iwersen-Bergmann S, Rösner P, Kühnau HC, Junge M, Schmoldt A. Death after excessive propofol abuse. International Journal of Legal Medicine. 2001;114(4-5):248-51.]

ü      Abuse of propofol as a recreational drug has been reported, usually among medical staff such as anaesthesiologists who have access to the drug. Despite a lack of analgesic properties, propofol's sedative action presumably produces euphoric effects. The steep dose response curve of the drug makes such abuse very dangerous without proper monitoring, and several deaths have been recorded [Kranioti EF, Mavroforou A, Mylonakis P, Michalodimitrakis M. Lethal self administration of propofol (Diprivan). A case report and review of the literature. Forensic Science International. 2007 Mar 22;167(1):56-8. Epub 2006 Jan 23.]

“Train of four” is associated with Weaning of ventilation

Question 20

“Train of four” is associated with

a.       Mechanical ventilation

b.      Muscle relaxants

c.       Weaning of ventilation

d.      None of the above

Answer

b. Muscle relaxants

Reference

Katsung 9^th Edition Page 435

Quality

Reader

QTDF

Katsung

Discussion

Assessment of Neuromuscular Transmission

Monitoring the effect of muscle relaxants during surgery (and recovery following the uise of cholinesterase inhibitors) typically involves the use of a device that produces transdermal electrical stimulation of one of the peripheral nerves to the hand and recording of the evoked contractions.

Explanation

Train of Four is A method for measuring magnitude and type of neuromuscular blockade, based upon the ratio of the amplitude of the fourth evoked mechanical response to the first one, when four supramaximal 2-Hz electrical currents are applied for 2 seconds to a peripheral motor nerve.

Comments

The three most commonly used patterns include

1. Single twitch stimulation
2. Train of four (TOF) Stimulation
3. Tetanic Stimulation

Tips

Two newer modalities are available to monitor neuromuscular transmission : double burst stimulation and post titanic count