1. Post-Operative Nausea & Vomiting
Dr James F Peerless
Anaesthetics StR
October 2014

2. Objectives Definitions Physiology Risk Factors Prevention
Treatment of PONV

3. What? Nausea Vomiting PONV The sensation of the need to vomit
The involuntary, forceful ejection of gastric contents via the mouth
PONV
Nausea and/or vomiting post-operatively(!)
Early 0-6, late 6-24, delayed >24

4. So what?

5. So What? Incidence – up to 70% in high risk patients
Patient dissatisfaction
Increased hospital stay or unexpected hospital admission
Adverse Effects

6. Potential Complications
Psychological
Aspiration of gastric contents
Wound dehiscence
Electrolyte imbalance
Loss of H+, Cl-, K+ ions
Dehydration
Elevated intracranial and intraocular pressures
Oesophageal Rupture
Pain

7. Who Can We Blame

8. The Patient Female (2-4x) Non-smoker Previous PONV (3x)
History of motion sickness
Children (2x)
Obesity
Anxiety

9. The Surgeon Middle ear surgery Ophthalmic surgery
(esp. squint correction)
Gynaecological surgery
Prolonged fasting
Duration of surgery
Dehydration
Emergency surgery

10. The Anaesthetist Use of N2O Opioids Etomidate Neostigmine Ergometrine
Hypotension

11. Assessing Risk Apfel et al., 1999 Identified four main risk factors
Female
Non-smoker
Previous PONV/motion sickness
Use of post-operative opioids
Patients assigned score of 0-4 according to risk
10, 20, 40, 60 80%

12. Physiology

14. Pharmacology

16. Antiemetic Drugs Drug group Examples Maximum adult dose Side effects
H1 antagonists
Cyclizine
50 mg 8 hourly PO/IM/IV
Sedation, dry mouth, blurred vision, hypotension, tachycardia
5-HT3 antagonists
Ondansetron
4-8 mg 8 hourly PO/IM/IV
Headache, dizziness, hypersensitivity reactions
D2 antagonists
Metoclopramide
Prochlorperazine
20 mg 8 hourly PO/IM/IV
5-10 mg 8 hourly PO
12.5 mg 8 hourly IM
3-6 mg 12 hourly buccal
Abdominal cramping, restlessness,
extrapyramidal & dystonic effects, sedation, hypotension
Antimuscarinics
(M2 antagonists)
Hyoscine
1 mg transdermal patch (released over 72 hours)
(at least 4 hours before the end of surgery)
Dry mouth, dizziness, blurred vision,
central anticholinergic syndrome
Corticoteroids
Dexamethasone
4-8 mg IV at induction of anaesthesia
Flushing, perineal itching, hyperglycaemia, peptic ulceration, fluid retention, psychosis, infection

17. Prevention

18. Prevention is Best Identify the high risk patient
Adapt procedure to benefit the patient
Modify all possible risk factors
e.g. length of fasting
Anaesthetic technique
Multimodal pharmacological approach

19. Treatment

20. The Vomiting Patient Reassurance ABCD approach Exclude surgical causes
Look for causes
Antiemetics
Exclude:
Hypoxaemia
Hypotension
Dehydration
Hypothermia
Pyrexia
Pain
Consider: O2
Ephedrine
IV fluids
Warming
Paracetamol
Analgesia
Persistent PONV despite prophylactic measures warrants an examination of the patient.
Once contributing factors have been excluded, rescue treatment is recommended.
If PONV occurs in the first 6 h after surgery, the drug chosen for rescue therapy should be from a different pharmacological class to that used for prophylaxis. PONV occurring after 6 h can be treated with any drug, though there appears to be no further benefit to repeating dexamethasone within 8 h of an initial dose. Similarly, transdermal hysocine acts for 72 h and should not be repeated.
Surgical causes: distended abdomen, NGT aspirate

21. Summary N&V is an unpleasant experience for the patient
Has an associated morbidity
Prolongs hospital stay
Prevention is better than cure
Assess the patient for reversible causes
Apply a multimodal approach

22. The End