preanaesthetic medication

1. Dr. Arundev P Nair
Dept of Anaesthesiology
G.M.C Kottayam

2. Are drugs administered before
an anesthetic with various
objectives so
as to obtain a smoother induction,
maintenance,and emergence from
anesthesia.
Ensures comfort to the patient & to
minimize adverse effects of
anaesthesia
What is preanaesthetic
medication…???

3. Preanaesthetic medication
objectives…
 Relief of anxiety and apprehension
 Amnesia for pre- & intra-operative
events
 Potentiate action of anaesthetics, so
less dose is needed
 Antiemetic effect extending to post-
operative period
 Decrease secretions
 Decrease vagal stimulation caused by
anaesthetics

4. Preanaesthetic medication
objectives…
 Decrease acidity & volume of gastric juice
to prevent reflux & aspiration pneumonia

5. When will you premedicate the
patient..??
 administered from night before to half an
hour before surgery

6. Methodologies can be
Psychological
&
Pharmacological

7. Psychological…???

8. Psychological…???
 As patient is going for operation, he is
apprehensive even before they come to the
hospital for admission.
 As an anaesthetist we have to schedule a
preoperative visit to the patient
 Explain the procedure to the patient in a
simple language and not in a complicated
manner
 Explain to them what to expect during the
procedure

10.  In some countries to address this issue,
“SATURDAY CLUBS” has been formed.
 It includes a lot of strategies like puppet show,
play oriented preoperative teaching,
videotapes showing operating rooms which
relieves child’s anxiety and produce a
smoother induction.

11. Drugs used for preanesthetic
medication
 Relief of anxiety and apprehension with sedation &
postoperative amnesia
 BENZODIAZEPINES:-Midazolam, Diazepam,
Lorazepam,Alprazolam,Nitrazepam
 Neuroleptics like Haloperidol, Droperidol
 OPIOIDS

12. BENZODIAZEPINES
 Is a sedative-hypnotic
 Reduces anxiety, provides amnesia and is
also a sedative & hasz centrally acting MR
property

13. BENZODIAZEPINES
 MIDAZOLAM(iv)
 DIAZEPAM(oral)
 LORAZEPAM
 REMIMAZOLAM
 ALPRAZOLAM
 DIAZEPAM
 NITRAZEPAM
 All are good premedicants. Is the treatment of choice to reduce
anxiety
 Chief difference is in the duration of action
 Those who regularly take BZD will be resistant to premedication of
these drugs
 Midaz is the most preferred
 provide no analgesia
 ANXIOLYSIS+SEDATION+AMNESIA(anterograde)+VAGOLYSIS+
REDUCTION OF PONV+MUSCLE RELAXATION

14. CLASSIFICATION “based on duration of
action”
MIDAZOLAM
LORAZEPAM, TEMAZEPAM
DIAZEPAM

15. Midazolam
 A short acting water soluble BZD
 Most frequently used BZD for premed
 Routes of administration
oral,iv/im/intranasally
• Dose:determined by a lot of factors such as
age, level of anxiety and surgical procedure
which is planned 0.25mg/kg(7.5to 15mg
orally)
• SIDE EFFECTS::Respiratory depression

16. LORA as a premedicant…???
 When prolonged and intense anxiolysis is
required as in cardiac surgery we use 2-
4mg of LORAZEPAM administered
ORALLY 2hours before anaesthesia

17. NITRAZEPAM
 A long-acting benzodiazepine
 mean elimination half-life 26 hours
 Residual "hangover" effects after nighttime
administration of nitrazepam such as sleepiness,
impaired psychomotor and cognitive functions may
persist into the next day
 Dose is 5-10mg

20. ANTICHOLINERGICS
ATROPINE &
GLYCOPYRROLATE
Drugs which
Decrease secretions
&
Decrease vagal stimulation
caused by anaesthetics

21. USES in premed
 These drugs are given to counteract the
effects caused by vagal stimulation like
bradycardia
 To reduce salivary & bronchial secretions
 To prevent gastrointestinal hypermotility esp
when neostigmine is used

22. MOA

24. WHAT EFFECT DO
ANTICHOLINERGICS HAVE ON THE
VARIOUS BODY SYSTEMS???

Atropine::: crosses BBB & causes CAS
Hyoscine:::CNS depressant+sedation
Glyco:::No effect

25. WHAT EFFECT DO
ANTICHOLINERGICS HAVE
ON THE VARIOUS BODY
SYSTEMS???
Atropine & Hyoscine::: Cycloplegia & Mydriasis
Glyco:::No effect
Antisialagogue actions
Atropine=hyoscine<glyco

26. WHAT EFFECT DO
ANTICHOLINERGICS HAVE ON
THE VARIOUS BODY
SYSTEMS???
Tachycardia
Atropine>glyco>hyoscine
Reverse order for propensity to generate arrythmia
Bronchodilatation
Atropine+glyco>hyoscine
Reduces salivation
Volume of gastric secrn
Antispasmodic
Reduced tone & peristalsis

28. ATROPINE vs
GLYCOPYRROLATE An ester alkaloid, tertiary
structure
• iv DOSE:::0.01-0.02mg/kg
Vagolytic(2-3mg)
 Onset of action 1min
 Lasts for 3hours
 Effect on HR++++
 Inhibn of sweating+++
 Effects on CNS:::CACS
 Quarternary ammonium
compound with
anticholinergic ppty
 0.005-0.01mg/kg
 1min
 6hours
 ++
 ++body temp not affected
 No effects

30.  Glycopyrrolate has a selective peripheral action,
acts rapidly,longer acting,potent antisecretory
agent, prevents vagal bradycardia
effectively….hence preferred
BUT…
 Atropine is preferred for prophylaxis and treatment
of vagal mediated bradycardia

31.  In modern anaesthesiology,
anticholinergics are not used routinely
as premed. There are specific
indications like… esp when ketamine
is used/ when airway handling is
anticipated

32.  In children, there is high vagal tone
and airway manipulation causes reflex
brady. So atropine is preferred

33. Antiemetic effect extending to
post-operative period
 Metoclopramide
 Domperidone
 Ondansetron,Granisetron
 PROMETHAZINE

37. Metoclopramide
 A procainamide derivative
 Moa
1. Dopamine antagonism(D2)
2. 5HT3 antagonism at higher doses

39. Metoclopramide
 Side effects
abdominal cramps, extrapyramidal side
effects like akathisia, galactorrhea &
gynaecomastia

40. Metoclopramide
 Dose:::5-10mg orally or 0.2-0.5mg/kg
iv
in children 0.1mg/kg orally(syp
5/5)
 S/E:::diarrhoea, abdominal cramps,
movement disorders like NMS

41. ONDANSETRON
 5HT3 ANTAGONIST
Blocks afferent pathway as well as
central processing of emetogenic
impulses
• Dose:::0.06mg/kg iv
0.1mg/kg oral rptd 4-6 hourly
Side effect::: headache,elevated LFT
Most effective when administered at
end of surgery in case of ponv

42. GRANISETRON
 Similar to ondansetron except that it is
longer acting

44. GRANISETRON
 Dose:::10mcg/kg iv
2mg orally

45. PROMETHAZINE(phenergan)
 first generation antihistamine with D2
antagonism

46. PROMETHAZINE
 strong sedative + antiemetic property
is utilised
 Often administered with
pethidine(meperidine) “BALANCED
ANAESTHESIA”
 S/E:::Tardive dyskinesia, constipation,
dry mouth,etc
 Dose:::25mg oral/iv

48. Drugs reducing acid secretion thereby
reducing the risk of aspiration
 Ranitidine (150-300mg oral) or Famotidine
(20-40mg oral) given night before & in
morning along with Metoclopramide reduces
risk of gastric regurgitation & aspiration
pneumonia
 Proton pump inhibitors like Omeprazole
(20mg) with Domperidone (10mg) is
preferred nowadays

49. Drugs reducing acid
secretion thereby reducing
the risk of aspiration
 Sod citrate
 Metoclopramide

50. Sodium citrate
 Is a nonparticulate antacid
 Given 15-30 mins before induction raises
gastric pH to >2.5. But the disadvantage is
that it increases volume of gastric juice
 If aspirated they produce less severe hypoxia
& lung abnormalities than others
Barash 6E

51. Newer agents for
premedication
 Dexmedetomidine
 Propofol
 Acupressure..!!!!

52. Dexmedetomidine
 is an alpha 2 receptor agonist
 With Sedative+analgesic+hypnotic+anxiolytic+
sympatholytic effects
• So used as a premedicant @ iv doses of 0.33-0.67mcg/kg
15minutes before procedure
Dexmedetomidine, when used prior to anaesthesia, blunts sympathetic
response to surgery & stress
does not depress ventilation &
reduces anaesthetic as well as opioid requirement

55. Decreases
shivering
threshhold

57. Opioid analgesics
 Morphine (8-12mg i.m.) or Pethidine (50-
100mg i.m.) used one hour before surgery
 Provide sedation, pre-& post-operative
analgesia, reduction in anaesthetic dose
 Fentanyl (50-100μg i.m. or i.v.) preferred
nowadays (just before induction of
anaesthesia)

59. Premedication in special
situations..??
 Premedication in paediatrics
 Need for premed is individualised. Depends on many factors:-underlying
medical disorder, length of surgery, desired induction agent, anaesthetist
preference,etc
 Not necessary for infants less than 6 months appear relatively undisturbed
when separated from their mothers.
 m/c used premed is oral midaz 0.25-0.33mg/kg
 For those children who refuse oral premed is given im ketamine(2-
4mg/kg)+atropine(0.02mg/kg)+midaz(0.05mg/kg)
 Oral Transmucosal Fentanyl Citrate(OTFC) may also be given. Pruritis,
desaturation,PONV are S/E
Anticholinergics are not routinely administered im to children

60. TRICLOFOS(Pedicloryl)
 Is a sedative drug
 Used especially in paediatrics
 Is a chloral derivative(1gm triclofos=660mgchloral
hydrate)
 Is metabolised in our body to trichloroethanol, which is
the pharmacologically active form
 Dose::75-100mg/kg

62. References
 Miller’s Anaesthesia 8E
 Wylie & Churchill-Davidson Practice of
Anaesthesia7E
 Lee’s Synopsis of Anaesthesia
 Handbook Of Clinical Anesthesia By Paul G Barash