● PONV Incidence & Impact
Post-operative nausea and vomiting remains one of the most common and distressing complications after surgery and anaesthesia. 25–35% of general surgical patients experience PONV, rising to 70–80% in high-risk groups if no prophylaxis is given.
Studies consistently show patients rate PONV as more distressing than post-operative pain. It is the leading cause of unexpected hospital admission after day surgery.
Clinical Consequences
- Patient distress — significant suffering, anxiety, reduced satisfaction
- Wound dehiscence — raised intra-abdominal pressure during retching tears sutures
- Pulmonary aspiration — risk highest in patients with reduced consciousness
- Electrolyte imbalance — hypokalaemia, hypochloraemia, metabolic alkalosis from repeated vomiting
- Dehydration — inability to tolerate oral fluids delays recovery
- Delayed discharge — day surgery patients may require unplanned admission
- Haematoma formation — venous engorgement during vomiting (especially ENT/head & neck surgery)
- Increased healthcare costs — extended PACU time, unplanned admissions
● Apfel Simplified Risk Score
The Apfel score is the most widely used and validated PONV risk stratification tool. Each factor scores 1 point:
| Risk Factor | Score | Rationale |
|---|
| Female sex | +1 | Hormonal influence — oestrogen sensitises chemoreceptor trigger zone |
| Non-smoker | +1 | Smoking induces hepatic CYP enzymes, accelerates antiemetic metabolism — paradoxically protective against PONV |
| History of PONV or motion sickness | +1 | Prior sensitivity of vestibular/CTZ pathways |
| Post-operative opioid use expected | +1 | Opioids stimulate CTZ via mu-receptors; reduce GI motility |
Apfel Score — Risk Percentage
| Score | PONV Risk | Category | Prophylaxis Strategy |
|---|
| 0 | ~10% | Low | No routine prophylaxis; consider TIVA |
| 1 | ~21% | Low | No routine prophylaxis; consider TIVA |
| 2 | ~39% | Moderate | Single antiemetic (ondansetron 4mg) ± TIVA |
| 3 | ~61% | High | Combination antiemetics + TIVA + minimise opioids |
| 4 | ~79% | High | Triple prophylaxis + TIVA + regional analgesia |
● Additional Surgical Risk Factors
Surgery Type (Higher Risk)
- Laparoscopic surgery — gas insufflation, trocar manipulation
- Gynaecological procedures — hormonal factors + anaesthetic duration
- ENT / middle ear surgery — vestibular stimulation
- Strabismus surgery — oculocardiac reflex, ophthalmic manipulation
- Breast surgery — hormonal, high female proportion
- Thyroid surgery — neck dissection, wound haematoma risk
- Neurosurgery — raised ICP, brainstem proximity
Anaesthetic Factors
- Volatile anaesthetic agents (desflurane > sevoflurane > isoflurane)
- Nitrous oxide (N2O) — direct CTZ stimulation
- Duration of anaesthesia >1 hour
- High-dose neostigmine for reversal
- Perioperative opioids (fentanyl, morphine, tramadol)
Patient Factors
- Younger age — elderly patients have reduced CTZ sensitivity
- Anxiety and high preoperative stress
- Obesity — raised intra-abdominal pressure, gastro-oesophageal reflux
- History of migraine
- Gastroparesis (diabetic patients)
● GCC Context
GCC hospitals have a high proportion of gynaecological, laparoscopic, and day-surgery cases — this concentrates PONV risk in typical caseloads. PONV risk stratification and prevention are especially critical in these settings.
Halal Considerations
An important GCC-specific consideration is the halal certification of antiemetic formulations:
- Some oral antiemetic capsules and soft-gel tablets contain porcine-derived gelatin as the capsule shell
- Muslim patients in GCC countries require halal-certified alternatives
- IV and IM formulations generally do not contain gelatin — confirm with pharmacy
- Ondansetron IV injection is halal; oral wafer (Zofran Zydis) formulation — verify with local pharmacy
- Nurses should document patient preference and liaise with pharmacy for halal-certified oral alternatives
- In emergencies, Islamic jurisprudence (fiqh) generally permits use of non-halal medication if no alternative is available — patient counselling is important
Ramadan Fasting Context
Patients fasting during Ramadan follow standard preoperative NPO guidelines — safety principles are unchanged. Educate patients that anaesthesia and medically necessary medications are generally permissible during Ramadan fasting.
● Overview of Antiemetic Drug Classes
Antiemetics work by blocking specific neurotransmitter receptors involved in the vomiting reflex pathway — primarily in the chemoreceptor trigger zone (CTZ), nucleus tractus solitarius (NTS), and vestibular nuclei. Understanding the mechanism guides selection and combination therapy.
● 5-HT3 Receptor Antagonists — First Line
First-line agents for PONV prophylaxis and treatment. Most effective class with favourable side-effect profile.
Ondansetron (Zofran)
Dose: 4mg IV/IM prophylaxis; 4–8mg IV rescue
Timing: End of surgery (prophylaxis)
Route: IV, IM, oral tablet, oral wafer
Notes: Most widely used; minimal sedation; QTc prolongation at high doses; hepatic metabolism — reduce dose in liver disease
Halal: IV injection — halal; oral formulations — verify with pharmacy
Granisetron (Kytril)
Dose: 1mg IV; transdermal patch 3.1mg/24h
Route: IV, oral, transdermal
Notes: Longer duration of action than ondansetron; transdermal patch useful for prolonged PONV prevention; used in CINV
Tropisetron / Ramosetron
Dose: Tropisetron 2mg IV; Ramosetron 0.3mg IV
Notes: Available in some GCC countries; similar mechanism and efficacy to ondansetron; ramosetron has very long half-life
● NK1 Receptor Antagonists — High-Risk Patients
Highly effective for high-risk PONV. Expensive — reserved for Apfel 3–4 or failed prior prophylaxis. Block substance P at NK1 receptors centrally and peripherally.
Aprepitant (Emend)
Dose: 40mg oral 1–3h pre-op
Notes: CYP3A4 interactions; expensive; oral only — limitation if patient cannot swallow pre-op
Fosaprepitant (Ivemend)
Dose: 150mg IV over 20 min (pre-op)
Notes: IV prodrug of aprepitant; useful when oral route unavailable; very effective combined with ondansetron + dexamethasone
● Corticosteroids
Dexamethasone
Dose: 4–8mg IV after induction of anaesthesia
Mechanism: Not fully understood — inhibits prostaglandin synthesis, reduces 5-HT release, anti-inflammatory
Notes: Additive effect with 5-HT3 antagonists; also reduces pain, swelling, and fatigue; give at induction not end of surgery (delayed onset ~2–4h); transient hyperglycaemia — monitor BSL in diabetics; single dose safe in most patients
● Dopamine Antagonists
Metoclopramide (Maxolon)
Dose: 10mg IV/IM/oral
Mechanism: D2 antagonist; also prokinetic (increases gastric emptying)
Notes: Less evidence than 5-HT3 for PONV; extrapyramidal side effects — dystonia, akathisia, tardive dyskinesia (especially in young patients); avoid in Parkinson's; limit to short courses
Prochlorperazine (Stemetil)
Dose: 12.5mg IM; 3–6mg buccal tablet
Mechanism: D2 and D3 antagonist; also H1 antihistamine
Notes: Sedating; buccal route useful when vomiting prevents oral intake; extrapyramidal effects possible; avoid in Parkinson's
Droperidol
Dose: 0.625–1.25mg IV (low dose)
Mechanism: Butyrophenone D2 antagonist
Notes: BLACK BOX WARNING — QTc prolongation and risk of torsades de pointes at higher doses; at low doses (0.625mg) very effective with acceptable cardiac risk; requires ECG monitoring; avoid in known QTc prolongation, hypokalaemia, concurrent QTc-prolonging drugs
● Antihistamines & Anticholinergics
Cyclizine (Valoid)
Dose: 50mg IV/IM/oral TDS
Mechanism: H1 antihistamine; also muscarinic (M1) anticholinergic
Notes: Effective; drowsiness and dry mouth common; IV formulation available; good rescue option when 5-HT3 already used; useful in vestibular PONV and motion sickness component
Scopolamine (Hyoscine) Patch
Dose: 1.5mg transdermal patch — apply behind ear 2–4h pre-op
Mechanism: Muscarinic (M1) antagonist — blocks vestibular input
Duration: 72 hours
Notes: Effective for PONV prevention especially with vestibular component; anticholinergic side effects — dry mouth, blurred vision, urinary retention, confusion (elderly); remove after 72h
● Antiemetic Drug Summary Table
| Drug | Class | Receptor | Dose / Route | Key Side Effect |
|---|
| Ondansetron | 5-HT3 antagonist | 5-HT3 | 4mg IV/IM/oral | Headache, constipation, mild QTc |
| Granisetron | 5-HT3 antagonist | 5-HT3 | 1mg IV | Headache, constipation |
| Aprepitant | NK1 antagonist | NK1 | 40mg oral pre-op | CYP3A4 interactions |
| Fosaprepitant | NK1 antagonist | NK1 | 150mg IV | Infusion site reactions |
| Dexamethasone | Corticosteroid | Multiple | 4–8mg IV at induction | Hyperglycaemia, insomnia |
| Metoclopramide | Dopamine antagonist | D2 | 10mg IV/IM/oral | Extrapyramidal effects |
| Prochlorperazine | Phenothiazine | D2, H1 | 12.5mg IM / 3mg buccal | Sedation, extrapyramidal |
| Droperidol | Butyrophenone | D2 | 0.625mg IV | QTc prolongation (black box) |
| Cyclizine | Antihistamine | H1, M1 | 50mg IV/IM/oral | Sedation, dry mouth |
| Scopolamine patch | Anticholinergic | M1 | 1.5mg TD patch | Dry mouth, confusion (elderly) |
● Risk-Stratified Prophylaxis Strategy
PONV prophylaxis should be tailored to individual risk using the Apfel score. Over-prophylaxis exposes low-risk patients to unnecessary drug side effects; under-prophylaxis leads to preventable PONV in high-risk patients.
| Apfel Score | Risk Level | PONV Risk | Prophylaxis Strategy |
|---|
| 0–1 |
Low |
10–21% |
No routine antiemetic prophylaxis. Prefer TIVA (propofol) over volatile agents — propofol has intrinsic antiemetic properties and reduces PONV vs inhalational anaesthesia. |
| 2 |
Moderate |
~39% |
Single antiemetic — ondansetron 4mg IV at end of surgery. Consider TIVA. Consider regional anaesthesia/analgesia to reduce opioid requirements. |
| 3–4 |
High |
61–79% |
Combination antiemetics: 5-HT3 antagonist + dexamethasone ± NK1 antagonist (if available). TIVA mandatory. Maximise regional analgesia to minimise opioids. Consider scopolamine patch pre-op. |
Key principle: Combination antiemetics from different classes have additive (not just additive) effects — each added agent in high-risk patients reduces PONV risk by approximately 25%.
● TIVA & Anaesthetic Choices
- TIVA (propofol-based) — reduces PONV by ~30% vs volatile; preferred in all moderate and high-risk patients
- Avoid N2O — nitrous oxide increases PONV risk; use air/O2 mixture instead
- Avoid volatile agents where possible in high-risk patients — desflurane > sevoflurane for PONV risk
- Short-acting opioids — remifentanil intraoperatively with transition to multimodal post-op analgesia
- Minimise neostigmine — high doses provoke PONV; sugammadex preferred for reversal when available
- BIS-guided anaesthesia — avoids anaesthetic overdose which increases emergence PONV
● Non-Pharmacological Prevention
- Adequate IV hydration — perioperative fluid loading (1–2L crystalloid) reduces PONV; dehydration is a trigger
- Acupressure — P6 (Neiguan point) — inner wrist, between flexor carpi radialis and palmaris longus tendons, 3 finger-breadths proximal to wrist crease; wristbands (Sea-Band) available; evidence supports modest benefit
- Ginger — evidence-based; ginger root extract or ginger tea reduces nausea; can be used alongside pharmacological prophylaxis
- Minimise preoperative anxiety — anxiolytic premedication, thorough patient information
- Adequate pre-op fasting — but avoid excessive fasting (dehydration worsens PONV)
- Isopropyl alcohol inhalation — inhaled vapour from alcohol swab provides rapid nausea relief in PACU (limited evidence but simple and safe)
- Cool, fresh air — fan directed at face reduces nausea sensation
● Treatment of Established PONV
Critical rule: When treating established PONV, use an antiemetic from a different class than what was given prophylactically. Repeating the same drug within 6 hours is unlikely to add benefit.
Rescue Antiemetic Options
Cyclizine 50mg IV
First rescue choice if 5-HT3 given prophylactically. Different class (H1). Administer slowly IV over 1 min.
Ondansetron 4mg IV
Use if NOT given prophylactically or >6h since last dose. Give slowly IV over 15–30 seconds.
Droperidol 0.625mg IV
Effective rescue agent. Check QTc before administration. Avoid with other QTc-prolonging drugs.
Management Steps for Active Vomiting
- Position patient lateral or semi-prone immediately — aspiration prevention is the priority
- Ensure airway is clear — suction if vomit in mouth/pharynx
- Maintain IV access — IV route preferred for antiemetics when actively vomiting (oral ineffective)
- Administer rescue antiemetic IV (different class from prophylaxis)
- Give IV fluid bolus (250–500mL crystalloid) — address dehydration and hypotension
- Reassess after 20–30 minutes — if not resolved, consider second rescue agent from another class
- Monitor for aspiration signs — SpO2, breath sounds, respiratory rate
- Document: frequency, volume, character of vomit, medications given, response
Documentation Requirements
- Frequency and severity of nausea/vomiting episodes
- Antiemetics given — drug, dose, route, time, and patient response
- Fluid intake and output (especially if prolonged vomiting)
- Vital signs before and after antiemetic administration
- Any aspiration concerns and actions taken
● PACU Arrival Assessment
On arrival to PACU, every patient requires a structured handover from the anaesthetist and immediate systematic assessment. PONV risk and prophylaxis already given must be communicated clearly.
Modified Aldrete Score — Discharge Readiness
| Domain | Score 2 | Score 1 | Score 0 |
|---|
| Activity | Moves all 4 limbs purposefully | Moves 2 limbs | Unable to move |
| Respiration | Breathes deeply, coughs freely | Dyspnoea or limited breathing | Apnoea |
| Circulation | BP ±20% of pre-op baseline | BP ±20–49% of baseline | BP ±50% of baseline |
| Consciousness | Fully awake, oriented | Arousable on calling | Not responding |
| O2 Saturation | SpO2 >92% on room air | Needs O2 to maintain SpO2 >90% | SpO2 <90% even with O2 |
Discharge from PACU requires Modified Aldrete Score ≥9/10. PONV must be controlled — active vomiting is a criterion for PACU retention.
● PONV Monitoring in PACU
- First 2 hours — highest risk period for PONV; assess every 15 minutes
- Ask the patient directly about nausea (do not wait for vomiting to occur)
- Use a verbal nausea scale (0–10) if patient is cooperative
- Anticipate PONV peaks: emergence, first oral fluids, mobilisation, opioid administration
- PONV monitoring is part of routine obs charting — document every assessment
- Notify anaesthetist if PONV uncontrolled after two rescue antiemetic doses
Most PACU units have standing orders for nurse-initiated rescue antiemetics — nurses should administer without waiting for individual prescriptions, within standing order parameters.
● IV Fluid Management
- Maintain IV access until patient is tolerating oral fluids without nausea
- Adequate IV hydration directly reduces PONV — perioperative fluid deficit contributes to nausea
- Standard crystalloid (0.9% NaCl or Hartmann's) 250–500mL bolus for dehydration-associated PONV
- Monitor urine output — catheterised patients: minimum 0.5mL/kg/hr
- Avoid premature removal of IV access — PONV may recur, especially with first oral intake
- Check electrolytes if prolonged vomiting — correct hypokalaemia and hypochloraemia
● Pain-Opioid Balance
Post-operative pain management and PONV are deeply linked — opioids are both necessary for pain control and a major PONV trigger. The nurse's role is to help optimise multimodal analgesia to reduce opioid burden.
Regular Non-Opioid Analgesia
- Paracetamol (acetaminophen) 1g IV/oral QDS — opioid-sparing, no PONV risk
- NSAIDs (ibuprofen, ketorolac, diclofenac) — if no contraindication (renal impairment, peptic ulcer, bleeding risk)
- COX-2 inhibitors (celecoxib) — reduced GI side effects
Regional & Local Techniques
- Nerve blocks (TAP block, femoral, brachial plexus)
- Epidural analgesia
- Wound infiltration with local anaesthetic
- Spinal morphine (with antiemetic cover)
Opioid Minimisation
- Titrate opioids to effect — smallest effective dose
- IV PCA (patient-controlled) — better titration, less bolus nausea
- Avoid PRN IM morphine — large intermittent doses worsen PONV
- Tramadol — lower PONV risk than morphine but not zero
● Staggered Mobilisation Protocol
Rapid position change is a common PONV trigger in the PACU — orthostatic hypotension contributes significantly to post-operative nausea especially after spinal anaesthesia.
- Nurse patient head of bed elevated 30–45 degrees once conscious and airway stable
- Encourage slow movement — no sudden position changes
- Before sitting upright: check BP lying, then sit up slowly and recheck BP after 2 minutes
- Before standing: wait 10 minutes sitting with legs dependent — allows venous adaptation
- First standing attempt: nurse at bedside, patient stands slowly — reassess immediately for dizziness/nausea
- If nausea on standing: return to sitting, administer antiemetic, rehydrate, wait further 15 minutes
● Day Surgery PONV Discharge Planning
Uncontrolled PONV is the most common reason for unplanned admission after day surgery. Discharge antiemetic planning is a nursing responsibility.
PACU Discharge Criteria (Day Surgery)
- Modified Aldrete Score ≥9
- Pain controlled — NRS ≤3 at rest
- PONV controlled — no vomiting in last 30 minutes, nausea ≤3/10
- Vital signs stable and within baseline range
- Tolerating small amounts of oral fluid (where applicable)
- Voiding — if catheter removed
- Responsible adult present for escort home
Discharge Antiemetic Prescription
- All day surgery patients at Apfel ≥2 should be discharged with oral antiemetic prescription
- Ondansetron 4mg oral ODT (or halal-certified equivalent) — take if nausea occurs at home
- Written patient instructions: when to take antiemetic, when to seek medical attention
- Return criteria: unable to tolerate any oral fluids after 6h, vomiting blood, signs of dehydration
● Paediatric PONV
Children have a higher baseline PONV risk than adults. PONV is the primary reason for unexpected hospital admission after paediatric day surgery.
Paediatric Risk Factors
- Age >3 years (infants paradoxically lower risk)
- Strabismus surgery (highest risk in paediatrics)
- Adenotonsillectomy (ENT)
- Orchidopexy / hernia repair
- Duration >30 minutes
- History of PONV or family history
Paediatric Antiemetics
- Ondansetron — 0.1mg/kg IV (max 4mg); first-line in children
- Dexamethasone — 0.15mg/kg IV (max 8mg); at induction
- Droperidol — 0.01–0.015mg/kg IV; effective, monitor QTc
- Combination (ondansetron + dexamethasone) for high-risk paediatric cases
- Avoid promethazine in children <2 years (respiratory depression risk)
- TIVA (propofol) reduces paediatric PONV significantly
● Obstetric PONV — Caesarean Section
Spinal anaesthesia for caesarean section has high PONV incidence (~80%) — primarily driven by hypotension from sympathetic blockade.
Mechanism in CS
- Spinal sympathetic block → profound hypotension → reduced cerebral perfusion → CTZ activation → PONV
- Uterine exteriorisation and visceral traction — direct stimulation of vagal afferents
- IV oxytocin bolus — vasodilatory, can cause hypotension and nausea
Management Strategy for CS
- Phenylephrine infusion — maintain maternal BP; prevention of hypotension prevents PONV
- Ondansetron 4mg IV — given at time of cord clamping (safe for breastfeeding)
- Slow IV oxytocin (infusion rather than large bolus) — reduces vasodilation and nausea
- Left lateral tilt until delivery — reduces aortocaval compression
- Ephedrine as rescue vasopressor if phenylephrine unavailable
● Chemotherapy-Induced Nausea (CINV)
CINV has a different mechanism to PONV but overlapping drug targets. Relevant for nurses in oncology and haematology settings.
CINV Phases
- Acute CINV: 0–24h — mediated by 5-HT3 from enterochromaffin cells in gut
- Delayed CINV: 24h–5 days — mediated by NK1 (substance P); often undertreated
- Anticipatory CINV: conditioned response before chemotherapy — treat anxiety, consider lorazepam
Gold-Standard CINV Prophylaxis (High Emetogenic Chemotherapy)
- NK1 antagonist (aprepitant Day 1–3) +
- 5-HT3 antagonist (ondansetron/granisetron Day 1) +
- Dexamethasone (Days 1–4) — triple regimen
- Olanzapine addition for breakthrough or highly refractory CINV
● Opioid-Induced Nausea
Opioids cause nausea via multiple mechanisms — CTZ stimulation, vestibular sensitisation, reduced GI motility. Common in palliative care, post-op, and chronic pain patients.
Management Options
- Opioid rotation — switching to a different opioid often resolves nausea (incomplete cross-tolerance); morphine → oxycodone, fentanyl, or hydromorphone
- Cyclizine — effective for vestibular component of opioid nausea
- Haloperidol (low dose 0.5–1mg) — D2 antagonist; effective for CTZ-mediated opioid nausea in palliative care
- Metoclopramide — addresses gastroparesis component
- Low-dose naloxone (naloxone infusion) — peripheral opioid antagonism without reversing analgesia; investigational in some centres
- Reduce opioid dose — reassess pain management; add non-opioid adjuncts
● Cancer Patients on Chronic Opioids
- Chronic opioid use often induces tolerance to nausea (PONV risk may be lower than expected)
- However, dose escalation or change in opioid type can trigger nausea
- Post-operative period: significantly higher opioid requirements — multimodal analgesia essential
- Opioid rotation consideration: if nausea with current opioid — trial alternate opioid at equianalgesic dose
- Cyclizine 50mg TDS or haloperidol 0.5mg nocte are commonly used in palliative nausea management
- Consider laxatives concurrently — constipation worsens nausea
● Ramadan & Elective Surgery — GCC Context
Patients undergoing elective surgery during Ramadan require specific preoperative counselling:
- Standard NPO (nil by mouth) guidelines apply — 6h solid food, 2h clear fluids — safety is unchanged regardless of Ramadan
- Patients must be counselled that anaesthetic administration and medically necessary treatments are permissible (necessity principle in Islamic jurisprudence — darura)
- IV medications during surgery and recovery do not break the fast under most scholarly opinions — patient and family counselling is important to reduce anxiety and improve compliance with preoperative instructions
- Post-operative oral antiemetics: if patient wishes to maintain fast after recovery, defer oral medications until breaking fast (iftar) if clinically safe; IV antiemetics available as alternative
- Nurses should approach this sensitively and involve family/chaplaincy support where appropriate
● Apfel Score — Exam Format Summary
| Component | Points | Why It Matters (Exam Explanation) |
|---|
| Female sex | 1 | Oestrogen sensitises the chemoreceptor trigger zone (CTZ) |
| Non-smoker | 1 | Smokers have induced CYP enzymes — faster antiemetic clearance paradoxically protective |
| History of PONV or motion sickness | 1 | Prior vestibular/CTZ hypersensitivity — genetic predisposition |
| Post-operative opioid use expected | 1 | Opioids stimulate CTZ mu-receptors; delay gastric emptying |
| Score | Risk % | Category |
|---|
| 0 | 10% | Low |
| 1 | 21% | Low |
| 2 | 39% | Moderate |
| 3 | 61% | High |
| 4 | 79% | High |
Exam tip: The Apfel score uses only 4 items — all easy to assess preoperatively without investigations. This is a favourite MCQ topic across DHA, DOH, SCFHS, and QCHP exams.
● Antiemetic Classes — Quick Reference Table
| Class | Drug Examples | Receptor Blocked | Primary Use |
|---|
| 5-HT3 antagonist | Ondansetron, Granisetron | 5-HT3 (serotonin) | First-line prophylaxis & rescue |
| NK1 antagonist | Aprepitant, Fosaprepitant | NK1 (substance P) | High-risk patients, CINV |
| Corticosteroid | Dexamethasone | Multiple (anti-inflammatory) | Combination prophylaxis |
| Dopamine antagonist | Metoclopramide, Droperidol, Prochlorperazine | D2 (dopamine) | Rescue; droperidol low dose |
| H1 antihistamine | Cyclizine, Promethazine | H1 (histamine) | Rescue; vestibular PONV |
| Anticholinergic | Scopolamine patch | M1 (muscarinic) | Prevention; motion sickness |
● PACU Discharge Criteria (Aldrete)
Score out of 10 — must be ≥9 for PACU discharge:
- Activity — 2 (all limbs), 1 (2 limbs), 0 (none)
- Respiration — 2 (deep/cough), 1 (limited), 0 (apnoea)
- Circulation — 2 (≤20% of baseline), 1 (20–49%), 0 (≥50%)
- Consciousness — 2 (awake), 1 (arousable), 0 (not responding)
- O2 saturation — 2 (>92% RA), 1 (needs O2), 0 (<90% with O2)
PONV control is an additional PACU discharge requirement — not scored in Aldrete but required for safe discharge.
● Prevention Strategy Summary
- Apfel 0–1 (Low): No antiemetic; TIVA preferred
- Apfel 2 (Moderate): Ondansetron 4mg IV + TIVA
- Apfel 3–4 (High): 5-HT3 + dexamethasone ± NK1 + TIVA + regional
- Treatment rule: Use a DIFFERENT class from prophylaxis for rescue
- TIVA (propofol) reduces PONV risk by ~30% vs volatile agents
- Dexamethasone must be given at induction (not end of surgery)
- Droperidol black box — QTc monitoring required
- Combination antiemetics — each added agent reduces risk ~25%
● DHA / DOH / SCFHS / QCHP High-Yield PONV Questions
| Question Theme | Key Answer |
|---|
| Most common cause of unplanned admission after day surgery | Uncontrolled PONV |
| First-line antiemetic for PONV prophylaxis | Ondansetron (5-HT3 antagonist) |
| Apfel score — highest risk factor | All 4 factors equally score 1 point each |
| Antiemetic with black box QTc warning | Droperidol |
| Non-pharmacological evidence-based PONV treatment | Acupressure (P6/Neiguan point) |
| PONV rescue rule — what class to choose | Different class from prophylaxis used |
| Timing of dexamethasone for PONV prevention | At induction (not end of surgery) |
| Anaesthetic technique that reduces PONV | TIVA (propofol-based) |
| Patient position for active vomiting | Lateral (recovery position) — aspiration prevention |
| Modified Aldrete score for PACU discharge | ≥9 out of 10 |
| Paediatric PONV — highest risk procedure | Strabismus surgery |
| Obstetric CS PONV — primary cause | Hypotension from spinal sympathetic block |
| Opioid-induced nausea — management option | Opioid rotation to different opioid |
| Extrapyramidal side effects — which antiemetics | Metoclopramide, prochlorperazine, droperidol |
| Halal consideration for PONV medications | Some oral capsules contain porcine gelatin — use IV or verify halal-certified alternatives |