Multimodal Anesthesia (2) Flashcards
The emphasis on multimodal anesthesia for GA includes these 2 aspects:
Short acting Anesthetics Agents and Opioid Sparing
What happens if acute pain is left untreated?
Can progress to chronic pain
What are the classes of opioids?
Phenanthrene
Benzylisoquinolones
What structure is in most opioid agonists?
Piperdine ring
What class of opioid are morphine, codeine, and thebaine?
Phenanthrenes
What class of opioid is papaverine, noscapine?
Benzylisoquinolones (lack opioid acticity)
Which phenanthrene isomer has opioid activity?
L-isomer
What are the 3 opioid receptors? Describe characteristics of each:
Mu
Kappa
Delta
What is the preop dose for acetaminophen? What is daily tylenol max?
1000mg PO or Ofirmev 1g intraop
Max: 4g/day
What is the preop dose of gabapentin?
300mg PO
What tylenol dose is continued postop x1 week?
1000mg TID
What mag dose is continued post op x1 week?
Super mag 400mg BID (or mag aspartate 615mg TID or Magoxide 500mg BID)
What is the intraop dose for lidocaine?
1mg/kg infusion over 1 hour
What gabapentin dose is continued post op x1 week?
300mg TID
What is the intraop dose of ibuprofen and the max dose?
200-800 IV over 30 min (Q6H PRN)
Max: 3200 mg/day
With MAGA, what medications can be giver both in preop and post op?
Gabapentin
Tylenol
What is the MOA of Gabapentin?
- Structural analogue of GABA with no activity in GABA transmission
- Binds to voltage gates Ca++ channels
→enhances descending inhibition
→inhibits excitatory neurotrans release
What are the pharmacokinetics of Gabapentin?
- Lipid soluble
- Non protein bound (<3%)
- No drug interactions
- short 1/2 time (need redosing)
What are the uses of Gabapentin?
- Partial seizures in adults and kids
- Chronic pain syndromes
- DM neuropathy
- Post-herpetic neuralgia
- Reflex sympathetic dystrophy
- Phantom limb pain
- Fibromyalgia
What patients is Gabapentin contraindicated in?
MG and myoclonus
Reduce dose in elderly
What is the preemptive dose of Gabapentin for analgesia?
300-1200mg PO 1-2 hours prior to OR
What are side effects of gabapentin?
- Fatigue
- somnolence
- ataxia
- vertigo
- constipation
- abrupt withdrawal in seizure patients
- weight gain
What are the effects of NSAIDS?
What enzyme catalyzes synthesis of PG?
Cyclooxygenase
What is the difference between COX 1 and COX 2?
COX 1:
* Physiologic (ubiquitous)
* many adverse effects with inhibition
COX 2:
* Pathological
* expressed at site of injury
*
What are properties of NSAIDS?
- Analgesic
- Anti-inflammatory
- Antipyretic
Which NSAIDS listed in class inhibit COX 1?
- Ibuprofen, Naproxen, ASA, Tylenol, Ketorolac
- NON specific,: concern for GIB with COX 1 inhibition
Which NSAIDS are COX 2 selective?
- Celebrex, Vioxx, Bextra, Dynastat
Why is COX 2 inhibition better than non specific inhibitors?
- comparable anagesia
- Lack effects on platelets
- may have decreased GI effects
- dosage ceiling (increase in side effects–may be associated in increase MI/CVA)
What was the 1st cox-2 inhibitos on the market?
Celebrex (1998)
What is the dose and peak of celebrex?
Decreases PG synthesis
200-400 mg PO once per day
Peak: 3 hours
What is the MOA of Ofirmev?
Reduces PG metabolites
No significant anti-inflammatory property
What is the dose/peak/duration of Ofirmev? Which pts are contraindicated?
Dose: 1000mg IV q4-6 hours
Peak: PO: 1-3 hrs IV: 30min-1hr
Duration: 6-8 hrs
Dont give to liver patients
What is MOA of Ketorolac?
Inhibit PG synthesis by inihibiting COX 1 and COX 2
When is Ketorolac contraindicated?
Severe renal impairment, Risk for bleeding, CAD, CABG, pregnancy, decrease dose in elderly, NSAID allergy
What is the dose/ peak for toradol?
Dose: 15-30mg q6 hours Max: 60-120mg/day
(1/2 dose for renal impairment)
Peak: 45-60 min IV (give during emergence)
What are the post analgesic properties of Ketorolac?
Only moderate anti-inflammatory
May potentiate opioid antinociception
What is a relative contraindication with Ketorolac use?
> 65 years old
What are examples of absolute contraindications for ketorolac?
Allergy to tylenol
Chronic renal failure
Low platelet count
What is the MOA of ibuprophen?
Anti-inflammatory, analgesic, and antipyretic
Inhibits COX 1 and 2
Which patients is ibuprofen contraindicated?
Allergies to NSAIDs, CABG, bleeding ulcers
What is the dose/peak/excretion of ibuprofen?
Dose: 200-800 IV over 30 min q6hour PRN MAX: 3200 mg/day
Peak: 1-2 hours
Excretion: urine and bile
What are 2 short acting anesthetic agents?
Propofol
Ketamine
What chemical component is lidocaine?
Amide (metabolism in the liver)
What is the dose for lidocaine bolus and gtt? When to terminate the gtt?
1-2 mg/kg IV (initial bolus) over 2-4min
1-2mg/kg/hr (gtt)
Terminate 12-72 hours
What are the dose dependent effects of lidocaine at plasma concentrations of 1-5, 5-10, 10-15, 15-25, and >25? (mcg/mL)
What is the MOA for magnesium when used for analgesia?
Anti-nociceptive effects
NMDA receptor antagonist (potentiates opioids centrally and peripherally)
What does magnesium regulate?
- Ca++ access into cell and actions within cell
- Neurotransmission
- Cell signaling
- Enzyme function
Does Mag cross BBB?
Limited passage across BBB
Which patients is magnesium contraindicated?
MG, renal failure (pts with hypotension and muscle weakness)
What is the dose for MAGA magnesium? (loading and intraop)
Loading: 50mg/kg IV preop
Intraop: 8 mg/kg/hr
What are the benefits/SE of using magnesium for multimodal anesthesia?
- significant decreased fentanyl requirement
- Be prepared to treat bradycardia and/or hypotension
Which med is the first 5-HT3 antagonist?
Ondansetron
Ondansetron responsiveness in decreased by variations in CYP_____ activity
CYP2D6
What are SE of zofran?
HA, constipation, QT prolongation
What is the adult dose/duration/plasma 1/2 life of ZOfran?
Dose: 4mg IV (up to 8mg)
Duration: 4 hours
What is the pedi dose for zofran?
0.1mg/kg IV
What is the MOA of corticosteroids? Where are glucocorticoid receptors located?
Unknown
Receptors in nucleus tractus solitarius
What happens if corticosteroids are given with 5HT-3 antagonists or droperidol?
Increases effectiveness (antinausea and anti inflammatory)
What is the dose for decadron? What is Decadron MOA?
MOA: anti-inflam, inhibition of phospholipase and cytokines and stabilization of cellular membrane
dose: 8-10 mg
What is the onset of decadron? What are the adverse effects?
Onset: 2 hours (efficacy lasts 24 hours) give prior to incision
Perineal burning/itching (give slowly and give versed 1st
A 50 yo, 60 kg patient receives a lidocaine initial dose of 1mg/kg with a subsequent infusion of 1.5 mg/kg/hr for 1.5 hours. How much total lidocaine in mgs did she receive prior to PACU?
195mg
Tx wes Reference guide for Non-opioid analgesics:
What is the MOA for Dexmedetomidine?
Highly selective, specific (potine locus coeruleus) potent and full alpha 2 agonist
________ is 7-10x more selective than clonidine
Precedex (shorter duration of action–safer)
Clonidine is only a partial agonist
What is the antagonist for precedex?
Atipamezole
How is Dexmedetomidine used for conscious sedation?
Calmness, easily rousable, spontaneous ventilation, amnesia is not assured
How is Dexmedetomidine used for GA?
Tracheal intubation; decreased perioperative requirements fo inhaled anesthetics and opioids
How is precedex used for TIVA?
Depression of ventilation, need secured airway
What are the pharmacokinetics of precedex?
T ½: 2-3 hours
(Clonidine: 6-10 hours)
Weak inhibition of CP450 enzymes
Metabolism: Hepatic
Excretion: Kidneys
Hypotension with high doses
Bradycardia with rapid infusion (cardiac arrest)
What are the doses of dexmedetomidine for TIVA/GA?
Bolus 0.5-1 mcg/kg, over 10 mins
High Dose
Loading dose of 1 mcg/kg, then 5-10 mcg/kg/hour IV
0.1-1.5 mcg/kg/min infusion
What are the doses of Dexmedetomidine for sedation?
0.2-0.7 mcg/kg/hr IV
What is the dose for IV regional anesthesia with precedex?
0.5 mcg/kg with lidocaine
What is the dose for precedex with spinal and epidural?
Spinal/intrathecal/SAB:
* 3mcg
* 5mcg with fentanyl 25mcg
Epidural:
* 2mcg/kg
How many mL can you add to a 200 mcg/2mL to dilute into a final concentration of 4mcg/mL?
48mL
