Transcript Advances in pharmacology applied to maxillofacial anaesthesia

Advances in pharmacology
applied to maxillofacial
anaesthesia
Postoperative nausea and vomiting
(PONV) and Anti-emetics
Pain and Analgesics
Future developments
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PONV
Incidence approximately 25%, (5-75%)
Medical impact minor
Patient’s impact HUGE
Requires treatment
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PONV
Patient characteristics
Female>male (x3). Incidence increases during menstruation and decreases after the menopause.
after 70 years of age,both sexes are equally affected.
Obese (has been suggested, although there is currently insufficient evidence to conclude an
association).
Young. Risk of PONV is almost twice that for adults. Equal distribution between boys and girls until
puberty.
Previous history of PONV/motion sickness
Early ambulation, early postoperative eating and drinking.
Surgery
Intra-abdominal-laparoscopic
Intracranial, middle ear
Squint surgery (highest incidence of PONV in children)
Gynaecological, especially ovarian
Head and neck, especially tonsillectomy and adenoidectomy (suggested due to blood in upper
gastrointestinal tract (GIT), stimulation of trigeminal nerve afferents and peroperative opioids).
Prolonged surgery
Painful
Anaesthesia/drugs
Opioids (NB untreated pain is also emetogenic)
Sympathomimetics
Inhalational agents (Isoflurane++)
Etomidate, ketamine, methohexitone (compared with propofol and thiopentone)
Neostigmine (recent work suggests that this is not associated with PONV)
Nitrous oxide (GIT distension/expansion of middle ear cavities).
Prolonged anaesthesia
Spinal anaesthesia (blocks above T5), hypotension.
Intraoperative dehydration
Inexperienced bag and mask ventilation (gastric dilatation).
Intercurrent Disease
Intestinal obstruction
Metabolic, e.g. hypoglycaemia, uraemia
Hypoxia
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PONV
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PONV
Tramèr MR. A rational approach to the control of postoperative
nausea and vomiting: evidence from systematic reviews. Part I.
Efficacy and harm of antiemetic interventions, and
methodological issues.
Acta Anaesthesiol Scand. 2001 Jan;45(1):4-13.
Tramèr MR. A rational approach to the control of postoperative
nausea and vomiting: evidence from systematic reviews. Part II.
Recommendations for prevention and treatment, and research
agenda.
Acta Anaesthesiol Scand. 2001 Jan;45(1):14-9.
Tramèr MR. (Editorial) Rational control of PONV – the rule of
three/Le contrôle rationnel des NVPO – la règle de trios.
Canadian Journal of Anesthesia. 2004 51:283-285
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PONV
1. Reduce the baseline risk by such measures as
reducing nitrous oxide use, avoiding neostigmine, using local
anaesthetics wherever possible instead of opiates and using propofol
for induction and maintenance of anaesthesia.
2. Do not use routine preventative
treatment as it does not work well, is less cost effective and
unnecessarily exposes patients to the drugs.
3. Identify the high risk patients and
then use an effective drug
combination.
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PONV
Apfel CC, Läärä E, Koivuranta M, Greim CA, Roewer N. A
simplified risk score for predicting postoperative nausea and
vomiting: conclusions from cross-validations between two
centers. Anesthesiology. 1990; 91:693-700.
Koivuranta M, Läärä E, Snare L, Alahunta S. A survey of
postoperative nausea and vomiting.
Anesthesia. 1997; 52:443-449.
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PONV
Major Proven Risk factors
Female gender
P/H of PONV or motion sickness
Non smokers
Opiates
Surgery duration >60 mins
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PONV
Cumulative risk %
Apfel
Koivuranta
Background risk
10
17
Plus 1 risk factor
2
3
4
5
21
39
61
79
18
42
54
74
87
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PONV
Major Proven Risk factors
Female gender
P/H of PONV or motion sickness
Non smokers
Opiates
Surgery duration >60 mins
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PONV
For an effective drug combination:
It has been shown that both dexamethasone and
droperidol increase the efficacy of “setrons” and it
is more effective to give a “cocktail” of prophylaxis.
For example: steroid (dexamethasone 8mg) at
induction and a 5-HT3 antagonist, good for treating
vomiting, (ondansetron 4mg) with a D2 antagonist,
good for treating nausea, (droperidol 0.75mg) at the
end of the procedure.
There is no evidence for an effect greater
than placebo for metoclopramide.
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PONV
Conclusion 1
MORE IS BETTER !
Prospective randomized, double-blind comparative study of dexamethasone, ondansetron, and ondansetron
plus dexamethasone as prophylactic antiemetic therapy in patients undergoing day-case gynaecological
surgery.
Thomas R, Jones N.
Br J Anaesth 2001; 87(4): 588-92.
Prevention of vomiting after strabismus surgery in children: dexamethasone alone versus dexamethasone
plus low-dose ondansetron.
Splinter WM.
Paediatr Anaesth 2001; 11(5): 591-5.
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PONV
Conclusion 2
“ The best ‘setron’ is the cheapest ‘setron’. “
(Remember oral formulations are available)
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ANALGESICS
Williams DG, Patel A, Howard RF.
Pharmacogenetics of codeine metabolism
in an urban population of children and its
implications for analgesic reliability.
Br J Anaesth. 2002 Dec;89(6):839-45.
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ANALGESICS
Codeine analgesia is wholly or mostly due to its
metabolism to morphine by the cytochrome
P450 enzyme CYP2D6
Forty-seven per cent of children had
genotypes associated with reduced enzyme
activity.
Morphine and its metabolites were not
detected in 36% of children given codeine
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ANALGESICS
Intra-venous paracetamol
PERFALGAN® Bristol-Meyers Squibb
1gm infusion equivalent to 10mg Morphine
IMI
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ANALGESICS
Tramadol
Karen Kaye,
Executive Officer, NSW Therapeutic
Advisory Group (formerly NSW Therapeutic
Assessment Group), Sydney
Trouble with tramadol
Key words: analgesia, drug interactions,
serotonin.
Aust Prescr 2004;27:26–7
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ANALGESICS
As of March 2004 the Australian Adverse Drug Reactions Advisory
Committee (ADRAC) has received 726 reports of adverse events
associated with tramadol, detailing 1922 reactions
Nausea, vomiting, dizziness, confusion and seizures. The potential for
serious drug-drug interactions should not be underestimated.
Like codeine, tramadol is metabolised via the CYP2D6 isoenzyme of
cytochrome P450 to an active metabolite which binds to µ receptors
For most patients, a combination of paracetamol and codeine will be
equally effective and possibly better tolerated than tramadol
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ANALGESICS
COX 2 Inhibitors
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ANALGESICS
COX2 inhibitors
can also increase blood pressure, induce or
worsen cardiac failure and impair kidney
function to the point of renal failure
but, no significant effect on platelets or
bleeding time, no opioid side effects and
highly rated by the patients
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ANALGESICS
PARECOXIB, DYNASTSAT® Pharmacia
in combination with morphine provides significant
opioid-sparing effects
improved pain management and patient satisfaction,
in two major surgical pain models, compared with
morphine alone.
T. Philip Malan, Jr, MD, PhD, Stephen Gordon, MD , Richard Hubbard, MD , and
Michael Snabes, MD
The Cyclooxygenase-2-Specific Inhibitor Parecoxib Sodium Is as Effective as 12 mg of
Morphine Administered Intramuscularly for Treating Pain After Gynecologic Laparotomy
Surgery
Anesth Analg 2005;100:454-460
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ANALGESICS
Chemical structure of remifentanil
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ANALGESICS
C.-S. Degoute, M.-J. Ray, M. Manchon, C. Dubreuil, and V. Banssillon
Remifentanil and controlled hypotension; comparison with nitroprusside or
esmolol during tympanoplasty
Can J Anesth, January 1, 2001; 48(1): 20 - 27.
Caverni, Valentina PhD; Rosa, Giovanni; Pinto, Giovanni;
Tordiglione, Paolo PhD; Favaro, Roberto
Hypotensive Anesthesia and Recovery of Cognitive Function in Long-term
Craniofacial Surgery.
Journal of Craniofacial Surgery. 16(4):531-536, July 2005.
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THE FUTURE
Org 25969
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THE FUTURE
Fentanyl PCTS
Iontophoretic patient controlled
transdermal system
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THE FUTURE
ACRUX
Analgesics, anxiolytics, antiemetics
(Competing Interests: Shareholder)
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THE FUTURE
New antiemetics
Antineurokinins AntiNK1
Cannabinoids
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Nabilone
The Future
“…a safe substitute for propofol,with
many propofol like properties, is
expected to be approved by the FDA
for non-anesthesiologists’ use in the
next year or two.”
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THE FUTURE
Fechner, Jorg M.D. ; Ihmsen, Harald Ph.D. ;
Hatterscheid, Dirk M.D. ; Jeleazcov, Christian M.D. ;
Schiessl, Christine M.D. ; Vornov, James J. M.D.,
Ph.D. ; Schwilden, Helmut M.D., Ph.D.; Schuttler,
Jurgen M.D.
Comparative Pharmacokinetics and
Pharmacodynamics of the New Propofol Prodrug
GPI 15715 and Propofol Emulsion.
Anesthesiology. 101(3):626-639, September 2004.
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THE END
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