ANAESTHESIA B (23)

Question 1

WHAT IS TRAMADOL?

Answer 1

• TRAMADOL is an opiod analgesic which is said to have less respiratory depressant and abuse potential than other opiods, but it makes make some patients chuck
• DOSE
  
  • 50-100 mg O 4/24
  • or 100mg slow IV
• dont mix with SSRIs as it also causes central Serotonin release, so can precipitate SEROTONIN SYNDROME with confusion, tremors, seizures

Question 2

ORAL OPIODS - OXYCODONE - OXYCONTIN - MS-CONTIN - KAPANOL

Answer 2

These are all oral opiod preparations with ~1/3 the potency of parenteral morphine*

• OXYCODONE has a short T1/2 : so is given 2/24, typically 5-15 mg
• OXYCONTIN is SR OXYCODONE, & MS-CONTIN & KAPANOL are SR oral Morphine preparations : give all in a dose of “3x the daily parenteral Morphine requirement, split BD”

* as a general rule, the oral bioavail of any opiate is ~30%

Question 3

10 mg PARENTERAL MORPHINE : ORAL EQUIVALENTS

Answer 3

10 mg of PARENTERAL MORPHINE =

• 20mg oral METHADONE
• 30 mg oral MORPHINE or OXYCODONE
• 100mg oral CODEINE
• 2x Panadeine Forte (allowing for the 30% opiod sparing effect of PARACETAMOL)

Question 4

OXYCODONE vs MORPHINE POTENCY

Answer 4

• OXYCODONE and MORPHINE are equipotent, which we often forget, because we are usually transitioning from PARENTERAL Morphine to ORAL Oxycodone, necessitating 3x the dose

Question 5

TYPICAL HOURLY IV MORPHINE REQUIREMENTS BY AGE =

Answer 5

• young adults ~ 4mg/h
• middle aged ~ 2mg/h
• elderly ~ 1 mg/h

Question 6

KIDS MORPHINE DOSES

Answer 6

• INTRA-OP LD = 0.1mg/kg IV
• POSTOP =
  
  • BOLUS = 0.05 mg/kg IV 2/24
  • INFUSION = 0.5 mg/kg made up to 50 mls, run at 0-4mls/h

Question 7

PAEDIATRIC ORAL OPIOD OPTIONS

Answer 7

1. ‘PAINSTOP’ = PARACETAMOL 120mg + CODEINE 5mg per 5ml : dosed per the PARACETAMOL, its of similar potency to Panadeine Forte
2. OXYCODONE SYRUP, 1mg/ml : Dose = 0.1mg/kg 4/24 O

Question 8

FENTANYL PATCHES

Answer 8

• Come in 12/25/50/100 mcg/h patches, which have a 12h onset/offset time, and are changed 3/7

Question 9

FENTANYL LOLLIPOPS

Answer 9

• ORAL TRANSCUTANEOUS FENTANYL CITRATE (OTFC) lollipops were originally licensed for cancer patients but are increasingly used in military circles
• they come in in doses of 200-1600 mcg, which, when placed against the buccal mucosa*
  
  • dissolve in 15m, with
  • 1/4 of the dose absorbed (IV)
  • 3/4 swallowed, where 1/3 survives 1st pass metabolism (like any opiate), giving an overall bioavailability of 50%
• onset is slower than IV, with maximum effect in 15-30m and a dose dependent duration of 1-2 hours
• a typical US SOF 800mcg lollipop equates to 200mcg IV over 15 min and 400 over an hour

* sucking increases rate of absorption but do not chew as this increases oral uptake so slows onset and reduces effect

Question 10

CLONIDINE DOSE FOR ANALGESIA

Answer 10

DOSE = 25-50 mcg IV or O tds

Question 11

AMITRIPTYLINE FOR CHRONIC PAIN

Answer 11

• AMITRIPTYLINE or ‘ENDEP’ is a Sodium Channel blocking* TCA useful for neuropathic pain
• DOSE = 25mg O nocte, or 10mg in elderly, but
  
  • beware 1st dose effect
  • dont mix with SSRIs

* Local Anaesthetics also act by blocking Sodium Channels

Question 12

WHAT ARE SSRIs?

Answer 12

• SSRIs = Selective Serotonin Reuptake Inhibitors, a class of antidepressant drugs that block the reuptake of Serotonin from the mood circuits of the brain
• examples include PAROXETINE and FLUOXETINE (PROZAC)
• related drugs include VENLAFAXINE and MIRTAZEPENE

Question 13

WHICH ANALGESICS NOT TO MIX WITH SSRIs

Answer 13

“TRAM & TRIP”

• TRAMADOL because of its central Serotonin releasing effect
• AMITRIPTYLINE ?why

Question 14

WHAT ARE OLANZAPINE & QUETIAPINE?

Answer 14

• These are ATYPICAL ANTIPSYCHOTICs used to treat SCHIZOPHRENIA, BIPOLAR disorder and MAJOR DEPRESSION.
• Both are part of COUNTRY HEALTH’s management plan for acutely disturbed patients
• DOSES:
  
  • OLANZAPINE: 10mg O or IM
  • QUETIAPINE: 100mg O

Question 15

GABAPENTIN and PREGABALIN for CHRONIC PAIN

Answer 15

• GABAPENTIN (NEURONTIN) and PREGABALIN (LYRICA) are Ca channel blocking anticonvulsants derived from the neurotransmitter Gamma-Amino-Butyric-Acid (GABA)
• Both are sedative, anxiolytic and opiod sparing in acute pain, and may be beneficial in chronic pain.
• FMC prefers LYRICA as it is easier to continue on PBS after discharge
• DOSE:
  
  • PREGABALIN : 75 mg O BD, incr to 150 or 300 if needed

*Rx LYRICA, 75 mg, take 1 O BD, n = 56, costs $49

Question 16

WHAT IS BUPRENORPHINE?

Answer 16

• BUPRENORPHINE = NORSPAN, a ‘PARTIAL OPIOD AGONIST’, which means it’s positive effects (analgesia & euphoria) ceiling off before it’s negative effects (nausea and sedation)
• It has good oral bioavailability and a long half life so was originally used as a METHADONE like opiod blocking drug, but is increasingly being used in patch form for chronic pain
• DOSE:
  
  • commence with a 5mcg/h patch, may incr to 10 or 20
  • change weekly, rotate sites
• It is no longer stopped before elective surgery : drive over it postoperatively with high dose narcotics

Question 17

WHAT IS TARGIN?

Answer 17

• TARGIN combines OXYCONTIN and NALOXONE in a single tablet, with the claim that the local effect of the NALOXONE in the GUT reduces constipation

Question 18

WHAT IS HYDROMORPHONE?

Answer 18

• HYDROMORPHONE (DILAUDID) is a potent* opiod analgesic long used for acute pain in the US and increasingly for chronic pain (esp pal care) in Australia
• It has poor oral bioavailability, so is usually given parenterally, although there is a once daily oral preparation called JURNISTA
• DOSE: typically
  
  • Intra-op: 1-2 mg IV
  • Postop: 0.5-1 mg IV 4/24 (US)
  • pal care: start with 1mg 6/24 sc

*7x as potent as Morphine

Question 19

TOLERANCE V ADDICTION

Answer 19

• TOLERANCE is the physical state of needing increasing doses of a drug to maintain a therapeutic effect over time, and of experiencing withdrawal effects if it is stopped
• ADDICTION is the destructive syndrome of compulsive drug seeking behaviour in the absence of therapeutic need
• whilst Tolerance usually develops with prolonged therapeutic opiod use, Addiction usually does not

Question 20

REMIFENTANYL

Answer 20

• REMIFENTANYL is an ultrashort acting opiod used as an adjunct* to anaesthesia, particularly where sympatholysis and muscle relaxation is desired
• DOSE
  
  • mix 2mg in 50 mls (40mcg/ml)
  • run at 5-100ml/h, commencing at 25

* it cannot be relied upon as a solo anaesthetic agent, and must be combined with Propofol or 0.5 MAC vapour

Question 21

WHATS DEXMEDETOMIDINE (US) ?

Answer 21

• DEXMEDETOMIDINE, (PRECEDEX) is a central Alpha agonist like CLONIDINE, or the Veterinary Anaesthetic XYLAZINE
• It provides sedation without respiratory depression, although it is sympatholytic
• it’s typically used for procedural and ICU sedation
• DOSE
  
  • 400 mcg/100mls
  • infused at 6-14 mls/h (dont bolus - hypotension)

Question 22

WATTCHOWS POINT STUDY

Answer 22

• showed that major bowel surgery patients had less postoperative ILEUS if given a COX2 inhibitor orally postop (CELECOXIB), but not if given a regular NSAID (DICLOFENAC)
• Dave now routinely uses CELECOXIB 100mg O BD postop unless CI by
  
  • IHD
  • CRF
  • Asthma
  • DU
• NOTE: Hollington also cites emerging evidence that high dose NSAIDs (PARACOXIB 40 IV intraop) increase anastomotic leaks, so avoids them

Question 23

TAPENTADOL