1. MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics-
PONV – insights
Dr. S. Parthasarathy
MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics-
PhD ( physiology),
( IDRA )

2. Some history
One of the first extensive descriptions of this phenomenon was by Sir John Snow in 1848, within 18 months of chloroform introduction in anaesthesia.
ether era, reported incidence of PONV was as high as 75–80%
Olive oil oral on recovery – does it absorb ether ?

3. Some history
Brown sequard – atropine to morphine – decreased PONV – still there
70 % to 50 % over the years to almost 20 % down now with proper prophylaxis comes down in single digit !?

4. Some definitions
Nausea is an unpleasant and difficult to describe psychic experience in humans
Retching ("dry heaves") refers to spasmodic respiratory movements conducted with a closed glottis
Vomiting is a forceful expulsion of the contents of the stomach and sometimes the gut.

5. Nausea
Nausea is derived from the Greek word naus denoting ‘ship’ and was used originally to describe the feeling of seasickness.
Nausea is an unpleasant sensation referred to the upper gastrointestinal tract and pharynx. It is associated with dizziness and a strong urge to vomit.
Score - not clear – assessment difficult

6. Retching
Retching is the involuntary process of ‘unproductive vomiting’.
It is characterized by the synchronous contraction of diaphragmatic and abdominal muscles against a closed mouth and glottis.
Retching is extremely distressing

7. What is vomiting ??
Vomiting represents the final common pathway of a highly coordinated sequence of events involving gastrointestinal, abdominal, respiratory and pharyngeal muscles which results in the active and rapid expulsion of contents from the stomach and upper intestine.
vomiting is easily identifiable and measurable!

8. Physiology of vomiting
Chemoreceptor Trigger Zone (CTZ)
Highly specialized are in the floor of the fourth ventricle
Responds to chemicals
Histamine. Serotonin, opioids, cholinergic , dopaminergic receptors
When stimulated , it stimulates the vomiting centre

9. Vomiting center
Medulla
Final push
Main sensory input is CTZ

10. GI tract
Any threat to the integrity of the GI system, e.g. gastric distension, irritation, damage or toxins,
triggers an ascending vagal activity which relays directly or indirectly to the vomiting centre
Cholinergic (M1), serotoninergic (5-HT3 ) and dopaminergic D2 receptors are the principal mediators of signal transduction within the gut mucosa

11. Motion sickness is an unpleasant side-effect induced by aberrant vestibular or visual activity
nausea may represent an important sign of underlying hypotension, particularly in patients who have just received regional nerve blockade.
? Retrograde autonomic signalling

12. Higher cortical centres (e. g
Higher cortical centres (e.g. the limbic system) involved with initiation and modification of the vomiting reflex.
Example: unpleasant sights, sounds or smells induce emetic responses

13. The act of vomiting
Pre-Ejection Phase Nausea (not a prerequisite to vomiting).
Gastric smooth muscle relaxes and retrograde peristalsis begins.
Deep inspiration.
Glottis closes (to avoid aspiration).

14. Ejection Phase Abdominal and diaphragmatic muscles contract.
Lower and upper oesophageal sphincters relax.
Intra-abdominal pressure increases.
Mouth opens and gastric contents are forcefully expelled.

15. Post-Ejection Phase Autonomic and visceral nerves ‘recalibrate’
Lethargy and weakness.
Increased autonomic activity results in salivation, pallor and tachycardia throughout all phases of the vomiting reflex.

17. Pictures from the internet for closed academic purpose only

18. Incidence ??
The general incidence of vomiting is about 30%, the incidence of nausea is about 50%
Big little problem ?
Classify
Early: 2-6 hours after surgery ( in PACU)
Late: hour period
Delayed: Occurs beyond 24 hours in inpatient setting
Why do we need to bother ??

19. Can it trigger to others ?
Ps and Ds
Can it trigger to others ?

20. Risk factors
Patient related
Anesthesia related
Surgery related

21. Patient related
Age : The incidence of PONV is 5% in infants, 25% below 5 years, 42-51% in the 6-16 age group and 14-40% in adults.
b) Gender : Adult women are 2-4 times likely to suffer from PONV than men, may be - female hormones.
c) Obesity : reported to have more PONV
excessive adipose tissue - storage for anaesthetic - --excessive production of estrogen by adipose tissue.
d) H/O motion sickness : -- predisposed to PONV.

22. Patient related
e) Delayed gastric emptying : Patients with intraabdominal pathology, diabetes mellitus, hypothryoidism, pregnancy, increase ICT, h/o. swallowing blood and with full stomach are at increased risk of PONV
f) Smokers : Non smokers are more prone to PONV

23. Anesthesia factors Opioids – intrathecal also
10 % 0f fentanyl dose is recovered in cervical spinal fluid in ten minutes
N2O. Ether, cyclopropane –etomidate
Movement of head on extubation
Excessive fasting or recent food intake ??
Stress and anxiety ??
Nerve blocks < spinal < General
Spinal hypotension

24. Volatile anaesthesia may increase PONV by decreasing serum levels of anandamide, an endogenous cannabinoid neurotransmitter that acts on cannabinoid-1 and transient receptor potential vanilloid-1 receptors to suppress nausea and vomiting.

25. Intrathecal ? Spinal = incidence = hypotension episodes Opioids
Epinephrine increased
Intrathecal clonidine – no role
Epidural 10 – 20 % incidence
Is there a role – parenteral opioid blunting pain and caused decreased PONV - because pain is potent stimulus for vomiting centre ??

26. Surgical factors Gynaec Squint ENT GIT
patients with wired jaw !!?? Not increased but we cant allow even 10 %

27. Taken from internet for closed academic purpose only
Apfel scoring system
Taken from internet for closed academic purpose only

28. Taken from internet for closed academic purpose only
In children
Taken from internet for closed academic purpose only

29. Receptors and drugs
Anti Histaminergic : block histamine receptors in the nucleus tractus solitarius.
Cyclizine & Meclizine 50 mg oral
Dimenhydrinate Dose is 1–2 mg/kg IV.
Sedation, dry mouth, urinary retention as side effects

30. Antimuscarinic -Transdermal scopolomine
It is a competitive inhibitor at postganglionic muscarinic receptors in the parasympathetic nervous system and acts directly on the CNS by antagonizing cholinergic transmission in the vestibular nuclei---
applied as transdermal patch mg is secreted over 72 h
applied the evening before surgery or 2–4 h before the start of anesthesia.
Side effects are visual disturbances, dry mouth, and dizziness.
Atropine as antiemetic in spinal !!

31. 5‑hydroxytryptamine subtype 3 receptor antagonists
These peripherally block gut vagal afferents and act centrally in area postrema.
Ondan 4 mg IV
Dolasetron – 12.5 mg
Granisetron 3 mg IV
At the end of surgery preferably
Side effects are headache, mild sedation, dizziness prolongation of QT interval.

32. Ramosetron Dose 0.3 mg IV is most effective to prevent vomiting and decrease nausea for patients receiving fentanyl patient-controlled analgesia
Palonosetron It is the second generation 5-HT3 receptor antagonist with a longer half-life of 40 h
It provokes a conformational change of 5-HT3 receptor through allosteric binding. Most effective dose is mg IV approved for 24 h
Oral 0.5 mg two hours prior- personal experience

33. Metoclopramide
It is a strong D2-receptor antagonist and blocks H1 and 5-HT3 receptors also
Gastric transit time is increased !!
Peripheral cholinergic agonist ?
10 mg IV IM or oral
dyskinesia or extrapyramidal symptoms, headache, dizziness, and sedation.

34. NK 1 receptor antagonism
new group of drugs used for PONV treatment thought to prevent both acute and delayed emesis.
act mainly at nucleus tractus solitarius and areas of reticular formation blocking NK-1 receptors. ( No to substance P )
They are more effective in inhibiting emesis than nausea.

35. NK 1 receptor antagonism
Antiemetic , antidepressant , anxiolytic
Aprepitant Dose is 40 mg PO 1–2 h prior to surgery
40 hours half life ( late PONV )
Side effects are constipation, headache, pyrexia, pruritis.
Cospitant Dose is 50–150 mg PO
Rolapitant Dose is 70–200 mg
Fosaprepitant - Intravenous use

36. Steroids Dexamethasone 4 – 8 mg on induction – slow onset
Anti prostaglandin and anti serotonin
Hyperglycemia at hours later
Insomnia
Methyl prednisolone – 40 mg IV also effective

37. Butyrophenone
low-dose droperidol (<1 mg or 15 µg/kg IV) in adults, there is still significant antiemetic efficacy with a low risk of adverse effects..
Sedation and hypotension
Dopamine antagonism at CTZ

38. Phenothiazines
Perphenazine It prevents PONV at doses between 2.5 and 5 mg IV or IM.
Chlorpromazine It is a D2 receptor antagonist at CTZ and dosage is 10 mg IV; its side effect is severe sedation.
Promethazine 25 mg IM (phenergan)
Extrapyramidal side effects !! rare

39. Miscellaneous Propofol – subhypnotic doses Mirtazipine 30 mg oral
Gabapentin 600 mg oral
Alpha 2 agonists
Midazolam 2 mg IV on induction

40. Manual electrical stimulation of the P-6 acupuncture point (Neiguan) by needle results in decrease in incidence of PONV upto 6 hours. Application of pressure on P-6 point every 2 hours is reported to produce effect for 24 hours.

41. Strategies not effective for PONV prevention
music therapy,
Supplemental oxygen
isopropyl alcohol inhalation,
intraoperative gastric decompression,
the proton pump inhibitor
ginger root,
cannabinoids

42. Pictures from internet for closed academic purpose only

43. Drugs and side effects Serotonin antagonists Neurokinin inhibitors
Steroids
Antihistamines
Butyrophenones
Headache, diarrhoea, constipation, arrhythmia
Dizziness, diarrhoea, headaches, weakness
hyperglycemia mood changes, nervousness
Confusion, drying of mucosal membranes, sedation, urinary retention
Prolonged QT interval (at doses ≥0.1 mg kg), hypotension, tachycardia, extra-pyramidal symptoms

44. PDNV ?? Post discharge nausea and vomiting After Ambulatory –
More with ambulatory lap scopy ?
Upto 35 %
Two drugs may be tried
Dexa and ondansetron ( palonosetron !! )

45. Guidelines Guideline 1 : Identify Patients’ Risk for PONV
individual risk and titrate for side effects

46. Guideline 2 – avoiding risk factors
Avoidance of general anesthesia by the use of regional anesthesia
Use of propofol for induction and maintenance of anesthesia
Avoidance of nitrous oxide
Avoidance of volatile anesthetics
Adequate hydration
Less opioids

47. Guideline 3
Administer PONV Prophylaxis Using 1 to 2 Interventions in Adults at Moderate Risk for PONV
Guideline 4. Administer Prophylactic Therapy With Combination (≥2) Interventions/ Multimodal Therapy in Patients at High Risk for PONV

48. Guideline 5.
Administer Prophylactic Antiemetic Therapy to Children at Increased Risk for POV;
As in Adults, Use of Combination Therapy Is Most Effective
Guideline 6. Provide Antiemetic Treatment to Patients With PONV who did not Receive Prophylaxis or in whom Prophylaxis Failed

49. Guideline 7. Ensure PONV Prevention and Treatment Is Implemented in the Clinical Setting- SOP
Guideline 8 : form policies and implement

50. Drug prophylaxis for PONV
No risk – not needed – low risk – one
Moderate to high risk – risk removal with multimodal approach – non pharmacological also
Vomits
Don’t repeat
Target Another receptor

52. From the internet for closed academic purpose only
Treatment strategies
From the internet for closed academic purpose only

53. Summary History Physiology Risk score Drugs and side effects
Guidelines

54. If you want to listen to a class how should we do ?
Thank you all