POST OPERATIVE NAUSEA AND VOMITING-2.pptx

1. MODERATOR : Dr Balwinder kaur rekhi Presentor : dr lovepreet POST OPERATIVE NAUSEA AND VOMITING

2. INCIDENCE PONV- two of the most common and unpleasant side effects following anaesthesia and surgery. Incidence of nausea- 22% to 38% Incidence of vomiting-12% to 26% An episode of vomiting prolongs postanaesthetic care unit stay by about 25 minutes.

3. SIGNIFICANCE OF PONV PONV remains a significant problem in modern anesthetic practice because of adverse consequences such as delayed recovery unexpected hospital admission delayed return to work of ambulatory patients pulmonary aspiration wound dehiscence Considering increasing demand for ambulatory and day care surgery, a holistic approach should be attempted before and during surgery to prevent PONV.

4. DEFINATION NAUSEA It is an unpleasant sensation referred to a desire to vomit not associated with expulsive muscular movement. VOMITING It is the forceful expulsion of even a small amount of upper gastrointestinal contents through mouth.

5. CLASSIFICATION Early PONV- within 6 hrs of emergence from anesthesia Late PONV- 6-24 hrs after procedure

6. PATHOPHYSIOLOGY The neuro anatomical site controlling nausea and vomiting is an ill-defined region called ‘vomiting centre ’ within reticular formation in the brainstem. It recieves 5 primary afferent pathways : The chemoreceptor trigger zone (CTZ) : It lies outside BBB and is in close contact with CSF to interact . Adsorbed toxins ,drugs ,circulating in blood stimulate CTZ . Reflex afferent pathway from cerebral cortex Neuronal pathways from vestibular system The vagal mucosal pathway in the gastrointestinal system. Midbrain afferents

7. These afferents stimulate the vomiting centre and initiate the process of vomiting by sending efferent signals . There occur coordinated contraction of abdominal muscles against closed glottis. The pyloric sphincter contracts and esophageal sphincter relaxes and there is active antiperistalsis within esophagus which forcibly expels the gastric contents . Stimulation of any of these afferent pathway can activate the sensation of vomiting via various receptors Serotonergic( 5HT3) Dopaminergic(D2) Histaminergic (H1) Cholinergic (muscarinic)(M) NK1 receptor

8. ETIOLOGY The etiology of PONV is usually multifactorial and associated with anesthetic and analgesic agents, the type of surgical procedure, intrinsic patient factors such as history of motion sickness It is important to recognize that nausea is common complain reported at the onset of hypotension, particularly following spinal or epidural anesthesia.

9. RISK FACTORS FOR PONV Patient factors - young age - female gender ( particular menstruating on day of surgery or first trimester of pregnancy) - nonsmoker ( 1.8 times more) - history of prior postoperative emesis - history of motion sickness Anesthetic technique - general anaesthesia > epidural > SAB > PNB - drugs: opioids, volatile agents, nitrous oxide

10. Surgical procedure - strabismus surgery - ear surgery - laparoscopy - orchiopexy - ovum retrieval - tonsillectomy - breast surgery Postoperative factors - posteroperative pain - hypotension

11. RULE OUT Hypotension Hypovolemia Postoperative pain Inadequate oxygenation Temperature- hypothermia, or patient feels too warm Poor oral hygiene Foul or upsetting smell in the vicinity of the patient

12. APFEL SCORE RISK FACTORS POINTS FEMALE 1 NON SMOKERS 1 HISTORY OF PONV AND/ OR MOTION SICKNESS 1 POST- OPERATIVE OPIOID ADMINISTRATION 1 POINTS SCORE % RISK OF PONV 10 1 20 2 40 3 60 4 80 LOW RISK HIGH RISK

13. PONV : DRUGS FOR PROPHYLAXIS AND T/T 5HT3 RECEPTOR ANTAGONIST: - Ondansetron - Granisetron - Dolasetron - Palonsetron CORTICOSTEROIDS -Dexamethasone DOPAMINE ANTAGONIST -Metoclopramide - Prochlorperazine BUTYROPHENONES - Droperidol -Haloperidol

14. ANTIHISTAMINES -Promethazine - cyclizine - dimenhydrinate ANTICHOLINERGIC -Transdermal Scopolamine NK-1 RECEPTOR ANTAGONIST - Aprepitant PROPOFOL GABAPENTINE MIDAZOLAM

15. 5HT3 ANTAGONIST Selectively block 5-HT3 receptors of GI tract and CTZ in area postrema of brain. ONDENSETRON: FDA dose - 4mg iv plasma ½ life -3 hours (most effective when given at the end of surgery) Reduce risk by 26% S/E : Headache , nausea, slight prolongation of QT interval , allergic reactions Metabolism - ondensetron undergoes extensive metabolism in liver via hydrolation and cojugation by cytochrome P-450 enzymes. Dose should be reduced in liver failure.

16. DOLASETRON FDA Dose : 12-50 mg iv- 12.5mg oral- 25-30 mg Plasma ½ life- 7 hours ( at induction) Not recommended due to QT prolongation. GRANISTRON FDA Dose: 1mg( 20-40 ug /kg) Plasma ½ life -9 hours ( at induction)

17. PALANOSETRON Most effective antiemetic in this group with NK-1 antagonism. FDA Dose-0.075 mg iv Reduce the risk by 30% with ½ life of 40 hrs ( usually given at the start of surgery) Most useful in PDNV

18. DEXAMETHASONE MOA- Inhibition of corticosteroid receptors inNTS Inhibition of prostaglandins synthesis FDA Dose – 4-5mg iv Slower in onset Administer at the induction Complication-Perioperative hyperglycemia in DM and obese patients, post op infection.

19. BUTYROPHENONES DROPERIDOL MOA: It is relatively selective D2 receotor antagonist . It is very effective in small doses ( 0.625-1.25mg iv)for prevention and treatment of PONV. Plasma ½ life of 3 hours Risk reduced by 26% FDA has given Black box warning Unfortunately its use has declined after its association with rare fatal arrythmias Contraindicated in suspected QT prolongation. S/E: Anxiety , restlessness , akathsia,dystonia , torsedes de pointes.

20. METOCLOPRAMIDE FDA Dose – 10mg iv ( 0.2-0.5 mg/kg) MOA- D2 receptor antagonist both central( CTZ) and peripheral. Peripheral prokinetic activity COMPLICATIONS- EPS, hypotension, tachycardia CONTRAINDICATED- Parkinson’s disease, restless leg syndrome.

21. NK1 ANTAGONIST APREPITANT MOA : Blocks NK1 receptors present in GIT FDA Dose – 40mg orally ( at induction) Risk reduced by 69% High cost

22. ANTIHISTAMINES PROMETHAZINE DIPHENHYDRAMINE CYCLIZINE MOA : H1 antagonism and anti cholinergic activity. S/E : Drowsiness , urinary retention , dry mouth,blurred vision. Given at the start –sedative side effects may delay recovery if given at end of surgery.

23. PROPOFOL The median plasma propofol concentration associated with an antiemetic response was 343ng/ml , which is much lower than the concentration ranges associated with general anaesthesia( 3-6 mcg/ml) or sedation (1-3mcg/ml) Propofol in small doses (20mg as needed) can be used as rescue therapy.

24. GABAPENTINE 600mg orally given 2 hours before surgery 800mg 1hour before surgery. MIDAZOLAM Midazolam 2mg when administered 30 mints before the end of surgery was as effective against PONV as ondensetron 4mg.

25. 5 HT antagonists and dexamethasone are the most effective antiemetics in the prophylaxis of pediatric POV.