Lecture 15: Pain Management of the Dental Patient

- acute pain ID and management --> move rapidly to period of healing and return to function

What is the goal of pain management for dental patients?

- projection

- transmission (maxillary N or mandibular N)

- transduction

What parts of the pain pathway do we target with local blocks?

- activate proportional to stimuli in the normal state

- pain generates an intense stimulus and then triggers as proportional response in CNS

How do pain receptors work normally?

- increased sensitivity (lowers threshold)

- budding of new receptive terminals

- receptive field expansion

- recruitment of previously quiescent nociceptors (silent nociceptor)

How do pain receptors change with repeated stimuli?

- repeated and amplified stimulus leading to axonal, spinal cord, brain stem, thalamic and cortical changes

How does chronic pain develop?

- how quickly/effectively initial pain is treated

- degree of nerve injury/CNS injury

- secondary healing problems from initial injury (infection)

- degree of anxiety/depression/fear

Chronic/maladaptive pain is hard to treat. What should you be aware of when treating it?

- minimize magnitude and duration of signal generated

- modulate neuroplasticity away from reactive/maladaptive and toward healing/adaptive

How do analgesic interventions help with managing chronic/maladaptive pain?

- nervous system has a lot of reserve capacity, but heals badly

What is the concept of neuroplacisity?

- implement gentle handling

- appropriate positioning

- decrease stress

What should be the first step of treating pain?

- opioids (best for acute pain)

What is the first line of treating pain?

- centrally and peripherally to decrease the magnitude of the acute pain signal

How do opioids work to treat pain?

- extremely effective analgesics and anti-inflammatory

- few contradictions for short term use

- work well with opioids = allows for opioid dose reduction

What are NSAIDs good for in regards to treatment of pain?

- once the P is stabilized = not in Ps that are cold, hypotensive, or with poor perfusion (renal/GI tox)

When should NSAIDs be given for pain?

- regional anesthesia

- reduce amount of inhalant due to multimodal approach

- continuing post-op analgesia without winding P up (pic)

What benefits do oral nerve blocks provide during dental procedures?

- A

- infraorbital N

Which needle indicates the rostral maxillary nerve block? What nerve does it block?

- D

- mental N

Which needle indicates the rostral mandibular nerve block? What nerve does it block?

- B/C (a few locations to give)

- caudal maxillary N

Which needle indicates the caudal maxillary nerve block? What nerve does it block?

- E

- inferior alveolar N

Which needle indicates the caudal mandibular nerve block? What nerve does it block?

- bone, teeth, intraoral soft tissue from the 3rd MX PM rostral to midline

What structures does the rostral maxillary nerve block impact?

- bone, teeth, intraoral soft tissue from the last molar rostral to midline

- ipsilateral soft/hard palatal mucosa and bone

What structures does the caudal maxillary nerve block impact?

- bone, teeth, intraoral soft tissue from the 2nd- 3rd MN PM rostral to midline

What structures does the rostral mandibular nerve block impact?

- bone, teeth, intraoral soft tissue from the 3rd molar rostral to midline

What structures does the caudal mandibular nerve block impact?

- 0.5% Bupivacaine/Ropivacaine

What is the drug of choice for oral nerve blocks?

- 5-15 mins onset

- 4-6 hour duration

Bupivacaine/Ropivacaine has what type of onset and duration?

- 2mg/kg

What is the max total dose of Bupivacaine/Ropivacaine for dogs and cats?

- Don't combine with lidocaine = shortens block duration

- No need to add buprenorphine = does not improve analgesic effect

What does not need to be added to Bupivacaine/Ropivacaine oral nerve blocks? Why?

- each site is based on size and weight of animal

- use clinical judgement

- do not exceed total calculated dose for all sites combined

How do you determine a dose (volume) for oral nerve blocks?

- 0.2 - 0.3 ml per site (0.25 ml)

What is the general dose of Bupivacaine/Ropivacaine given to small dogs cats for oral blocks?

- 0.3 - 0.6 ml per site (0.5ml)

What is the general dose of Bupivacaine/Ropivacaine given to a medium dog (15-25 kg) for oral blocks?

- 0.8 - 1.2 ml per site (1ml)

What is the general dose of Bupivacaine/Ropivacaine given to a large dog (26 - 40 kg) for oral blocks?

- 1.4 - 1.6 ml per site (1.5 ml)

What is the general dose of Bupivacaine/Ropivacaine given to a giant dog (40+ kg) for oral blocks?

- 1 ml or 3 ml syringes

- Bupivacaine/Ropivacaine

- needles 25g x 5/8 or 22 x 1/2

What equipment is need to perform oral nerve blocks?

- changes to ECG

- intralipid emulsion therapy

What can signify a local anesthetic toxicity? How would you treat?

- aspirate

What should you do prior to giving a nerve block?

- infraorbital foramen

What is the skeletal landmark for the rostral maxillary nerve block?

- middle mental foramen

What is the skeletal landmark for the rostral mandibular nerve block?

- infraorbital foramen

- rostral maxillary nerve block

What is this structure? What block goes here?

- find/palpate the infraorbital foramen just dorsal to the distal root of the 3rd Max PM

- advance needle just rostral to infraorbital foramen opening parallel + adjacent to the maxillary bone in a rostral-caudal direction

- needle should rest just inside the canal

How do you perform a rostral maxillary nerve block?

- brachycephalic breeds

- short infraorbital canal allows agent placed rostrally to travel caudally

Which breeds to not require a caudal maxillary nerve block? Why?

- insert needle in a ventral to dorsal direction into the soft palate mucosa where it meets the bone just caudal to the 2nd mandibular molar

- advance needle no more than 3-5 mm ensuring the tip rests directly under the nerve

How do you perform a caudal maxillary nerve block?

- small dogs and cats = hard to do due to limited ability to access nerve

Who do we not often perform the rostral mandibular nerve block in? why?

- retract the mandibular labial frenulum ventrally

- advance the needle slightly (~15 degrees) ventral and caudal to enter the foramen

How do you perform a rostral mandibular nerve block?

- palpate the mandibular foramen

- direct the needle through the skin toward the lingual aspect of the mandibular body.

- palpation the needle tip to ensure contact with the bone

- tip should rest just ventral to where the inferior alveolar nerve

How do you perform a caudal mandibular nerve block, using an extraoral approach?

- opioids

- ketamine/memantine (NMDA antagonist)

- gabapentin (oral)

Other than oral nerve blocks what other meds can be given to a dental anesthetic patient to help with pain?

- attenuates excitatory neurotransmitters in brain and SC

- helps prevent and Tx CNS sensitization

- prevents and reverse opioid tolerance/hyperalgesia

How does ketamine/memantine (NMDA antagonist) help with pain?

- not an analgesic --> an ANTI--HYPERALGESIC

How does gabapentin help with main?