SURGERY PHARMACOLOGY Flashcards
GOAL OF PERIOPERATIVE PAIN MANAGEMENT =
to have the patient comfortable when they awaken from anesthesia
ADVERSE OUTCOMES OF UNDERTREATED PERIOPERATIVE PAIN
⦁ Thromboembolic complications ⦁ Pulmonary complications ⦁ Increased length of hospitalization ⦁ Hospital readmission for further pain management ⦁ Needless suffering ⦁ Impairment of quality of life ⦁ Development of chronic pain
ADVERSE OUTCOMES OF PERIOPERATIVE PAIN MANAGEMENT
Respiratory depression Brain injury Neurologic injury Sedation Circulatory depression Nausea and vomiting Pruritus Urinary retention Impairment of bowel function Sleep disruption
must always document
⦁ pain intensity
⦁ the effects of pain therapy
⦁ the SE caused by pain therapy
approach to the patient: factors to consider
⦁ Type of surgery
⦁ Expected severity of postoperative pain
⦁ Underlying medical conditions
⦁ CVD, Pulmonary, allergies, renal or liver failure
⦁ Risk-benefit ratio for the available techniques
⦁ Patient’s preferences
⦁ Patient’s previous experience with pain
pre-op prep of patient
- History
- PE
- Post-op pain control plan
perioperative techniques for pain management
- central regional opioid analgesia
- patient controlled analgesia with systemic opioids (PCA)
- peripheral regional analgesia (intercostal blocks, plexus blocks, local anesthetic infiltration of incisions)
CENTRAL REGIONAL OPIOID ANALGESIA
- epidural or intrathecal administration of analgesia
⦁ epidural = injection outside the dura
⦁ intrathecal (spinal) = injection through the dura, directly into the CSF
Benefits = improved pain relief when preincisional epidural or intrathecal morphine is given compared with po, IV or IM morphine
Risks = increased pruritus and urinary retention in post-op epidural anesthesia compared to IM morphine
intrathecal administration of opioids
- intrathecal morphine (0.1 - 0.2 mg) or fentanyl (10-20 mcg)
- a single dose of intrathecal opioid (morphine) can provide pain relief for up to 18-24 hours post-op
⦁ onset of action = 45 minutes - Fentanyl provides pain relief for 1-2 hours
⦁ onset of action = 5-10 minutes
PATIENT CONTROLLED ANALGESIA
- for moderate to severe post-op pain
Benefits = decreased delay in patient access to pain medication, and decreased likelihood of overdose
- the pump is usually discontinued when able to take oral meds
- morphine, hydromorphone and fentanyl can be given PCA
- Fentanyl = less desirable due to short DOA (may be useful with morphine allergy, and is easier to use in hepatic or renal insufficiency than others)
- Improved pain scores with IV PCA (patient controlled analgesia) when compared to IM morphine
- studies show that having an IV PCA pump with a background infusion of morphine vs PCA pump without background infusion
⦁ more analgesic used
⦁ equal amounts of pain relief, nausea, vomiting, pruritus, and sedation
why is fentanyl less desirable for analgesia
shorter duration of action
when is fentanyl used
morphine allergy
easier to use in hepatic or renal insufficiency
MULTIMODAL TECHNIQUES FOR PAIN MANAGEMENT
- using 2 or more drugs that act by different mechanisms for providing analgesia
- systemic meds = Opioids + NSAIDS
- Central and regional meds = epidural + local anesthetics (fentanyl + bupivocaine)
- have better pain control with multi-modal, but more muscle weakness & pruritus
systemic analgesics
- improved pain scores & reduced analgesic use when given IV morphine + ketorolac compared to IV morphine alone
- Ketorolac (NSAID) along with PCA opioid administration = more effective at decreasing pain vs COX 2 or nonselective NSAID
- Lower pain scores when adding gabapentin or pregabalin to IV opioids
Unless contraindicated, patients should receive scheduled regimens of NSAIDS, COXIBs or acetaminophen
PERIPHERAL REGIONAL TECHNIQUES
- peripheral nerve blocks, intra-articular blocks, and infiltration of the incisions
- preoperative nerve blocks are effective at reducing post-op pain and decreasing the need for opioid use (post-op blocks are not as helpful)
- Pre-op infiltration of the incision with local anesthetic (ex: Bupivicaine) decreases post-op pain scores
patients at risk for inadequate pain control
⦁ Pediatrics ⦁ Geriatrics ⦁ Critically ill ⦁ Cognitively impaired ⦁ Others who may have difficulty communicating
OPIOID DRUGS
OPIOIDS ⦁ Morphine ⦁ Hydrophormone (Dilaudid) ⦁ Fentanyl ⦁ Meperidine
3 most commonly used for post-op IV pain management = Morphine, Dilaudid & Fentanyl
most widely used meds for tx of post-op pain
opioids
OPIOIDS
- Most widely used medication for the treatment of postoperative pain
- Bolus injections are often used
⦁ Given this way = they fail to provide a steady state of the drug
Continuous infusions
⦁ May be dangerous due to the potential for drug build up and cause respiratory depression
⦁ Must be given in a highly supervised environment
- Patient controlled analgesia
opioid metabolism
- all opioids are hepatically metabolized to active and inactive metabolites, which are eliminated in the urine
- patients with severe liver disease will need dosage adjustments
MORPHINE
- rapid onset
- duration = 4-5 hours
- need to dose adjust for kidneys; pts with renal dysfunction = at risk for toxicity
- active metabolites are eliminated renally; so in renal insufficiency, active metabolites may accumulate and cause neurotoxicities (myoclonus, confusion, coma, death)
- relatively contraindicated in severe renal disease
- erratic absorption from the GI tract
HYDROMORPHONE (DILAUDID)
- more rapid onset of analgesia than morphine
- about 4-6x more potent than morphine
FENTANYL
- synthetic derivative of morphine
- about 100x more potent than morphine
- more lipid soluble than morphine; so more rapid onset of action, improved penetration of BBB, shorter half-life, and elimination half life = 2-4 hours
- does NOT release histamine - and may be preferred in the presence of hemodynamic instability or bronchospasm
⦁ administration > 5 days may lead to deposition of drug in adipose tissue and prolonged sedation
contraindicated in patients with MAOIs
meperidine
- indicated for short term management of acute pain
lowered seizure threshold
has dysphoric effect
meperidine
MEPERIDINE
- indicated for short term management of acute pain
- contraindicated in patients on MAOIs
- lowers seizure threshold
- has a dysphoric effect
- not as effective as other drugs
- slower rate of metabolism in elderly or if liver / renal failure
- not used for PCA pumps because of the risk for accumulation of the active metabolite
not used often because of lowered seizure threshold & dysphoric effect
histamine release = most common with which opioid
morphine
OPIOID SE
Somnolence
Depression of brainstem control of respiratory drive
Hypotension
Urinary retention
N/V
Slowing of GI transit
Constipation, ileus
Histamine release (most common after morphine)
Flushing, tachycardia, hypotension, pruritus, bronchospasm
transitioning from IV to oral opioids
- Switch from IV to oral once the patient can tolerate PO
- Calculate the 24 hour opioid consumption to determine the coverage needed
⦁ Consult equianalgesic charts - PO – analgesic effects take 30-60 minutes
- Switch to one of the following: Oxycodone, hydrocodone, hydromorphone, morphine
⦁ Ex: 40 mg of IV morphine given in 24 hours would require 20 mg oxycodone Q 4 hours or 5 mg of hydromorphone Q 4 hours
ORAL OPIOIDS
⦁ Oxycodone (Oxycontin) (Roxicodone) = Schedule II
- Oxycodone + Acetaminophen = Percocet - Oxycodone + Ibuprofen = Combunox
⦁ Hydrocodone = Schedule III
Hydrocodone + Acetaminophen = Lortab, Vicodin, Norco
Hydrocodone + Ibuprofen = Vicoprofen
⦁ Hydromorphone (Dilaudid) = Schedule II
⦁ Morphine = schedule II
opioid duration of action
Fentanyl = short acting
Morphine / Codeine/ Hydromorphone / Oxycodone = intermediate acting
Methadone = Long acting
patients with renal dysfunction
⦁ Hydromorphone & Oxycodone = have inactive metabolites = are safer than morphine for use in renal impairment
⦁ Fentanyl = also safer than morphine for use in renal impairment
OPIOID REVERSAL
- Naloxone (Narcan)
- reversal of respiratory depression with therapeutic opioid doses
- given IV, IM, SQ, or endotracheal
- initially = give 0.04 - 0.4 mg; may repeat until desired response is achieved; if not observed after 0.8 mg total, consider other causes of respiratory depression
NON-OPIOID ADJUNCTIVE MEDICATIONS
⦁ NSAIDS ⦁ Ketamine ⦁ Lidocaine ⦁ Magnesium ⦁ IV Acetaminophen
don’t give ketorolac to
elderly patients & renal dysfunction
NSAIDS
- administration of NSAIDS can reduce the does of opioid required
- caution with kidney impairment (and elderly)
- Non-selective NSAIDS (inhibits COX1 & COX2)
⦁ IV formulations : Ketorolac & Ibuprofen
⦁ Ketorolac reduces opioid consumption by 25-45% - Selective NSAIDS
⦁ no IV formulations available
⦁ sometimes just a single dose will suffice
acetaminophen = contraindicated in
hepatic failure
first line acetaminophen route
oral or rectal first line
then IV
ORAL NSAIDS
- Non-selective PO or PR
⦁ Ibuprofen
⦁ Diclofenac
⦁ Ketoprofen - Selective
⦁ Celecoxib (Celebrex)
KETAMINE
- NMDA receptor inhibitor
- use is limited due to hallucinations
- reduces hyperalgesia & opioid tolerance
ACETAMINOPHEN
- oral or rectal = first line
- then try IV
- may be given in addition to NSAIDS
- Contraindicated in hepatic failure
LIDOCAINE
- class I antiarrhythmic
- IV infustion intra op or post-op for pain control
- most effective for analgesia following major abdominal surgery
MAGNESIUM SULFATE
- can reduce opioid requirements
- NMDA receptor antagonist (just like ketamine)
- Bolus or Infusion
- Not routinely used at this time, despite many studies that show its effectiveness
