Anaesthesia and Analgesia Flashcards
Adrenaline can reduce uterine blood flow and induce premature labour, therefore non-urgent procedures requiring the use of adrenaline should be postponed until after pregnancy.
T
Tetracaine can provide anaesthesia to mucous membranes for up to 45 mins.
T
sharp well-localised pain is trasmitted by fast myelinated A-delta fibres
T
Having the patient place the thumb and last two digits together accentuates the palmaris longus tendon.
T
Conventional pulse oximeters are reliable in detecting metHb.
F
Use blood gases and blood metHb levels.
Flexing the wrist in a slightly ulnar direction helps identify the flexor carpi ulnaris tendon.
T
Higher concentrations of lignocaine can cause muscle twitching, nystagmus, blurred vision and confusion.
T
Field or ring block involves placement of anaesthesia circumferentially around the operative site.
T
Psychogenic attacks in response to LA can manifest as vasovagal episodes and lead to lightheadedness, diaphoresis, nausea, syncope, bradycardia and hypotension
T
Neuropathic pain is due to stimulation of nociceptors
F -
Vasoconstrictors added to local anaesthetic impair the absorption of the anaesthetic and prolong its duration.
T
Concurrent use of medications that inhibit cytochrome p450-3A4 enzyme can potentially result in systemic toxicity when used in conjunction with amide-type LA.
T
In healthy patients, increased blood pressure and arrhythmias generally don’t occur if the dose of adrenaline is limited to 1mg.
F
0.5mg (50mL of 1:100 000 dilution).
The auriculotemporal nerve block is performed by palpating for the TMJ with the jaw open and injecting 2-3mL superior to the joint over periosteum at the zygomatic arch.
T
inadequate post op pain relief can result in poor compliance with dressings
T
Injecting 1-2mL of anaesthetic just to the radial side of the palmaris longus tendon and under the flexor retinaculum at the proximal crease of the wrist will block the median nerve.
F
Use 3-5ml anaesthetic. Everything else is true. This will anaesthetise most of the radial side of the palm.
The A-delta fibres conduct pain and temperature. They are the smallest of the A fibres.
T
Adrenaline reactions from local anaesthetic are associated with decreased blood pressure, whereas anaphylactic reactions are associated with increased blood pressure.
F
Other way around.
Warming of the tumescent solution to 104F before infiltration will reduce pain
T
Methylene blue is contraindicated in patients with G6PD deficiency.
T
Give ascorbic acid 300-1000mg/day iv in 3-4 doses.
Concomitant administration of other methemoglobin-forming drugs such as sulphonamides and antimalarials can increase the risk of methaeoglobinaemia
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Topical eye preparations have an onset time of 30seconds
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The mental nerve emerges mid-height of the mandible, in the midpupillary line, approximately 1cm inferior to the second premolar.
T
Local infiltration is suitable for infected or inflamed tissue
F
Field blocks are appropriate
Use of topical benzocaine can cause contact sensitisation.
T
Procaine, tetracaine, benzocaine, chloroprocaine, and cocaine are types of amide anaesthetics.
F
Esters
The external nasal nerve emerges at the junction of the upper lateral cartilage and nasal bones.
T
The infraorbital nerve can be blocked using the intraoral approach – the needle is advanced through the gingival buccal sulcas at the apex of the canine fossa
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Procaine lasts longer than lignocaine.
F
Procaine 15-30mins, ligno 30-120 mins.
Seizures and cardiac toxicity generally do not occur until plasma concentrations of lignocaine approach 5mg/mL.
F
10mg/mL. increasing blood levels cause coma and respiratory arrest.
Local anaesthetics can be excreted in breast milk.
T
Ester anaesthetics are most commonly used for nerve blocks
F
Amides
A lower pKa correlates to a higher concentration of base and a faster onset of action.
T
Injection of anaesthetic into the nerve itself can cause a neuropraxia resulting in paraesthesia in the distribution of the nerve itself.
T
This can rarely be permanent
A fibres are the largest of the nerve fibres.
T
A radial nerve block is performed by infiltrating anaesthetic in the area lateral to the radial artery, extending toward the dorsum of the wrist.
T
The superficial peroneal, sural, saphenous and deep peroneal nerves innervate the dorsal aspect of the foot.
T
To prevent methemoglobinaemia you should avoid using prilocaine and benzocaine in patients with risk factors
T
The A-beta fibres conduct motor impulses.
F
Light touch and pressure.
Safe upper limit of lignocaine with tumescent anaesthesia is estimated to be 35mg/kg
F
55mg/kg
Postoperative analgesia is always required in patients who have been given tumescent analgesia
F
It provides post-op analgesia itself
The infraorbital nerve supplies sensation to the contralateral lower eyelid, nasal sidewall, upper lip, medial cheek, upper teeth and maxillary gingiva.
F
Ipsilateral
A scalp block can be performed by injecting LA approximately 4-5cm apart starting at the mid-forehead extending circumferentially toward the occiput and back around to the mid-forehead.
T
Slower the rate of tumescent solution does not reduce the pain of infiltration
F
Yes, it does
Adding sodium bicarbonate to local anaesthetics allows for increased amounts of uncharged, lipid-soluble base, which more readily crosses the nerve membrane, leading to faster onset of action.
T
The greater auricular nreve innervates the ipsilateral angle of the jaw to the submandibular area and posterior auricle
T
The depth of analgesia after 60mins of EMLA application is 5.0mm. .
F
3mm. 120 mins gives 5mm
Adrenaline use in digital blocks should be avoided in patients with severe hypertension, peripheral vascular and vasospastic disease, and connective tissue disease.
T
Two dorsal and two ventral nerves lie along the lateral aspects of the digits and innervate each digit.
T
Lignocaine and etidocaine are the LAs most commonly associated with clinically significant methaemoglobinaemia.
F
Benzocaine and prilocaine.
Highly protein-bound anaesthetics, such as bupivacaine, are tightly associated with the neural membrane, leading to a longer duration of action.
T
The auriculotemporal nerve is a branch of the maxillary nerve (V2).
F Mandibular nerve (V3).
Adrenaline should be avoided in patients with hyperthyroidism, severe hypertension, and phaeochromocytoma.
T
Management of anaphylactic reaction include administration of 03-0.5mg adrenaline subcut, BLS and transport to an acute care facility
T
LMX has a slower onset of action than EMLA.
F
Faster – 30min application time.
A total volume of 3-5mL of lignocaine typically provides adequate anaesthesia for a digital block.
F
1-3mL.
Ester derivatives are metabolised by microsomal enzymes in the liver and excreted by the kidneys.
F
This is true for amides.
Nociceptive pain is due to damage/dysfunction of nerves
F
C-fibres are the smallest and conduct pain and temperature.
T
An eye patch must be worn following anaesthesia to the eye to protect the cornea
T
The mental nerve supplies the lower lip and cheeks.
F
Lower lip and chin.
Nerve blocks involve injecting anaesthesia adjacent to a nerve or within the same fascial compartment as the nerve to be anaesthetized.
T
The external nasal nerve supplies sensation to the dorsum, tip and alar of the nose.
F
Dorsum, tip and columella.
The interaction of TCAs and adrenaline may lead to hypertension, tachycardia and arrhythmias.
T
Symptoms of methaemoglobinaemia will occur at the time of LA administration.
F
Occur 1-3hrs following Rx, because its caused by metabolites of the LA.
The intraoral approach for the infraorbital nerve block is more painful
F
Less painful
The greater auricular and transverse cervical nerves emerge at Erb’s point.
T
Local anaesthetics reversibly interrupt propagation of nerve impulses by interfering with sodium ion influx into peripheral nerve cells.
T
Infants and children are at greater risk of metHb than adults because haemoglobin F is more susceptible to oxidation, newborns have lower levels of reductive enzymes, and the dose tends to be greater per kilogram body weight.
T
Complications from nerve blocks are rare, but care must be taken to avoid digital ischaemia
T
Vasoconstrictors such as adrenaline should not be added to the anaesthetic agent when performing a nerve block due to the risk of vessel trauma.
F
It will improve haemostasis, slow absorption of anaesthetic, prolong its duration and decrease amount needed
But avoid in digits
The maximum dose of adrenaline for LA should not exceed 1mg over approximately 8-10hours
T
The infraorbital nerve is the smallest branch of the maxillary nerve (V2).
F
Largest branch.
PDT is reported to be more painful for patients than Mohs micrographic surgery
T
EMLA is a eutectic mixture of 2.5% lignocaine and 2.5% prilocaine.
T
Oil-in-water emulsion cream.
To block the posterior tibial nerve, anaesthetic is injected at the level of the upper half of the medial malleolus, posterior to the posterior tibial artery pulse and anterior to the calcaneal tendon.
T
3-4mL injected.
For adults, the maximum total dose of EMLA is 10g, to a maximum application area of 100cm2, for 4 hours.
F
20g, 200cm2, 4 hours.
