Misc Topics Flashcards
Misc Pain Topics
What term describes the following: a stimulus that is normally expected to produce pain
allogenic
What term describes the following: a stimulus that does not normally produce pain.
Allodynia
Define dysesthesia
Abnormal or unpleasant sense of touch
Provide an example of a condition that produces dysesthesia
Diabetic neuropathy that causes a burning sensation
Where does pain modulation occur?
The spinal cord. During central sensitization, the inhibitory pathway can become impaired. This is why antidepressants that increase norepinephrine and serotonin can help treat chronic pain.
List some examples of tricyclic antidepressants
Amitriptyline
Nortriptyline
Imipramine
TCAs have the most significant side effects including: QT prolongation and orthostatic hypotension
List some examples of serotonin & norepinephrine reuptake inhibitors
Venlafaxine
Duloxetine
Minacipran
The combination of a SNRI and SSRI can precipitate serotonin syndrome
What does CPRS stand for and what are the two types?
Complex regional pain syndrome
Type 1: reflex sympathetic dystrophy
Type 2: causalgia
Type 2 is always preceded by a nerve injury
CPRS is characterized by what?
Neuropathic pain with autonomic involvement. Risk factors include females and previous trauma or surgery.
List some treatments for CPRS
Ketamine
Memantine (NMDA antagonist)
Gabapentin
Regional sympathetic block
PT
Steroids
Amitriptyline
What does the thoracic paravertebral nerve block target?
The ventral ramus of the spinal nerve as it exits the vertebral foramen. This block is used for breast surgery, thoracotomies and rib fractures. The block needs to be performed at each dermatome to be anesthetized
What kind of coverage does a thoracic paravertebral nerve block provide?
This block creates a unilateral sympathetic and sensory block along each dermatome. It can be thought of as a unilateral epidural block
List some common complications of a celiac plexus block
orthostatic hypotension
retroperitoneal hematoma
hematuria
diarrhea
abdominal aortic aneurysm
back pain
retrograde migration of injectate
What type of pain is a cervical plexus block useful for?
Cancer pain of the abdominal organs including: stomach, liver, pancreas, distal esophagus and colon (except descending)
What type of pain is a superior hypogastric plexus block used for?
Cancer pain to the pelvic organs including uterus, ovaries, prostate and descending colon
What is the sphenopalatine block commonly used to treat?
post dural puncture headache
Describe how the anatomy of the optic nerve impacts the type of anesthesia for a retrobulbar block
The optic nerve is actually part of the central nervous system. Because it is wrapped in the meningeal sheath and surrounded by CSF, injection of local anesthetic into the optic sheath provides direct entry to the brain - like a spinal for the optic sheath
What complication can occur during a retrobulbar block if local anesthesia migrates toward the optic chiasm?
If LA migrates, it can anesthetize cranial nerve 2 and 3 on the opposite side and cause blindness in the contralateral eye (amaurosis)
Why can apnea occur after a retrobulbar block?
Local anesthesia that reaches the brainstem can cause apnea (post retrobulbar block apnea). Usually occurs 2-3 minutes after the injection with spontaneous ventilation resuming 15-20 minutes later. Full recovery may take up to an hour
What are some indications that post retrobulbar block apnea may occur?
Shortly after the block, if a pupil that was small has dilated, you should anticipate apnea and be ready to provide support until the local has cleared from the CSF
What types of procedures are TAP blocks best suited for?
Procedures that involve T9-T12 distribution. Bilateral TAP blocks are needed from midline incisions or laparoscopic surgery.
Innervation of the anterolateral abdominal wall arises from the anterior rami of T7-L1
What are the components of the triangle of Petit?
External oblique
Latissimus dorsi
Iliac crest
What are complications of the a TAP block despite using ultrasound guidance?
Peritoneal puncture and liver hematoma. The tip of the needle should be positioned in the fascial plane between the internal oblique and the transverse abdominis muscle
Inhibition of COX-1 causes what effects?
COX 1 is always present and is responsible for normal physiologic function. Inhibition of it can cause gastric irritation, reduced renal blood flow and impaired platelet function
Inhibition of COX 2 produces what?
Analgesia, anti inflammatory and antipyretic effects. COX 2 is not always present and expressed during inflammation. Analgesia from COX 2 inhibitors has a ceiling effect unlike opioids.
List some common non selective COX Inhibitors and then some COX 2 selective inhibitors
Non selective: aspirin, ibuprofen, naproxen, ketorolac, diclofenac
COX 2 selective: celecoxib and any drug with the suffix -coxib
How do COX inhibitors increase the risk of brochospasm?
Decreased prostaglandins lead to leukotrienes that can induce a bronchospasm
List some cardiovascular complications of COX inhibitor use
Increased risk of HTN, MI and heart failure. Complication rate is higher with COX 2 inhibitors compared to COX 1. COX 2 inhibitors were supposed to be associated with less side effects but increased CV risk has caused most to be removed from the market except Celebrex.
How many morphine equivalents is 30mg ketorolac equal to?
IV ketorolac is equivalent to about 10mg morphine IV
