Nausea and vomiting can occur due to various factors before, during, and after surgery. Nausea is an unpleasant sensation while vomiting is an active reflex that expels the contents of the stomach through the mouth. The vomiting reflex involves the vagus nerve, spinal nerves, and phrenic nerve acting on the stomach, esophagus, diaphragm, and abdominal muscles. Individual predisposition, female gender, obesity, motion sickness history, and type of surgery or anesthesia used can increase the risk of postoperative nausea and vomiting. Prevention focuses on minimizing risk factors like avoiding prolonged fasting, maintaining hydration and blood pressure, using anti-emetics, and controlling pain and anxiety.

1. Nausea and Vomiting

2. Definitions
• Nausea
unpleasant sensation
• Regurgitation
passive
gravity
raised intra-abdominal pressure
• Retching
reverse peristalsis
• Vomiting
active reflex action
‘unstoppable’

3. Vomiting
• Vagus
Oesophagus
Cardiac sphincter
Body of stomach
Pyloric part
• Spinal nerves
Abdominal muscles
• Phrenic nerve
Diaphragm
Relax
Contracts strongly
Contract
Contracts Descends

4. PONV Pre Operative Factors
• Individual
predisposition
• History of motion
sickness
• Raised ICP
• Female>Male
• Children>Adults
• Obesity
• Constipation
• Distended Stomach
• Metabolic disturbance
• Drug toxicity
• Alcohol
• Prolonged fasting
• Renal failure

5. PONV – Types of Surgery
• Bowel obstruction and ileus
• Appendicitis
• ENT
Ear Surgery
Blood in Stomach
• Uterine procedures
• Mauling of GIT
• Strabismus surgery
• IV radiological contrast media

6. PONV – Anaesthetic Factors
• Inflation of stomach
• Hypotension (neural blockade)
• Opioids
• Ether

7. PONV – Post-Op
• Opioids
• Pain
• Hypoxia
• Sights and Sounds
• Malodour
• Anxiety
• Hypovolaemia
• Head down
• Movement stimulating
the vestibular
apparatus

8. Higher Cortical
Centres
Sensory input
(Pain, Smell, Sight)
Memory, Fear,
Anticipation
Chemoreceptor
Trigger
Zone
Chemotherapy
Opioids
Anaesthetics
Stomach,
Small Intestine
Chemotherapy
Surgery
Radiotherapy
Vomiting
Centre
Labyrinths
Surgery
VOMITING
REFLEX
Neuronal pathways
Factors which can cause N&V

9. Prevention/Treatment
• Avoid opioid premedication
• Avoid prolonged pre-op fasting
• Avoid dehydration & hypovolaemia
• Good pain control
• Avoid vestibular stimulation
• Well oxygenated
• Diminish psychological factors
• Anti-emetics

10. Delayed Gastric Emptying
• Physiological
- Pain, Anxiety
• Pathological
- GI tract obstruction, Acute gastritis, Electrolyte
imbalance, DM
• Pharmacological
- e.g. Opioids

11. Drug induced N&V
• GI irritation
- NSAID’s, FeSO, Antibiotics, Alcohol
• Gastric stasis
- Opioids, Tricyclics
• CTZ stimulation
- Opioids, Digoxin, Antibiotics, Cytotoxics
• 5HT3 receptors
- cytotoxics

12. Flowchart for Treatment of PONV