Post-operative nausea and vomiting
With an increased drive to day-surgery procedures across the NHS, anaesthetists are being increasingly challenged to provide safe and effective perioperative care that also facilitates a rapid post-operative recovery. After inadequate analgesia, post-operative nausea and vomiting (PONV) is the commonest reason for unplanned overnight admission.
1 Effectively assess a patient at risk of PONV
2 Consider alternative anaesthetic and analgesic strategies to minimize risk of PONV
3 Outline the different classes of antiemetic agents.
1A02; 2A03
It is 8.15 a.m., and you meet a 44-year-old lady presenting for elective wire-guided wide local excision of breast tumour, with sentinel node biopsy. She is ASA 1, takes no medication, and has no allergies. She has a history of PONV.
◆ Height and weight/body mass index (BMI)
◆ Presence or absence of reflux
◆ Fasting status
◆ Presence or absence of carer at home
◆ Further details about her PONV.
Your patient is 1.70 m tall and weighs 60 kg, giving a BMI of 21 kg/m2. She has no reflux and is fasted for solids overnight, though she had a cup of black coffee at 7.00 a.m. She is chewing gum when you meet her.
Your patient had three previous operations: a tonsillectomy at age 12, a laparoscopy and excision of skin lesions under general anaesthetic at age 39. She was sick after all operations, despite telling the anaesthetist about her PONV prior to her laparoscopy. She was assured she would get anti-sickness drugs and a ‘special’ anaesthetic last time, but she vomited post-operatively and had to stay in hospital for 4 days post-operatively following the laparoscopy and 3 days following the skin lesion excision.
Not necessarily. She requires to go to the radiology department to have ultrasound-guided wire insertion. This means it should be unlikely she will be first on the list. The commonly accepted preoperative fasting in adults undergoing elective surgery is ‘the 2–6 rule’:
◆ ‘2’: intake of water up to 2 hours before induction of anaesthesia
◆ ‘6’: a minimum preoperative fasting time of 6 hours for food (solids, milk, and milk-containing drinks).
She had black coffee. This does not contain fat or solids, so many anaesthetists would treat this as equivalent to water and accept a 2-hour period of fasting as acceptable. If there were other concerns or she had milk in her coffee or food at 7.00 a.m., she would need to wait until 1.00 p.m. before proceeding to surgery.
Chewing gum may be allowed up to 2 hours prior to surgery, as suggested by the AAGBI in 2010. It is now 8.15 a.m., so her procedure should not be carried out before 10.15 a.m.
No. She should have a carer at home who is able to look after her for 24 hours post-operatively.
Yes. She needed to stay in hospital as a result of vomiting for 4 days following her last two procedures. It is not uncommon for patients to be sick following tonsillectomy if they swallow some blood in the immediate post-operative period. This causes gastric irritation, nausea, and vomiting. Published rates of PONV following tonsillectomy range from 0% to as high as 44%.
Laparoscopy is also regarded as relatively high risk for PONV, with 41% of patients requiring some form of antiemetic in the post-anaesthetic care unit (PACU) following gynaecological laparoscopy if they received only placebo. This can be reduced to 2% with multimodal antiemetic prophylaxis.
Skin lesion excision would be expected to be a low-risk procedure for PONV. It is body surface surgery and can usually be analgesed effectively without the use of opiates. Her history suggests she is at high risk of PONV, and her breast surgery procedure is likely to be more emetogenic than her last procedure.
◆ What analgesics has she taken in the past?
◆ Are there particular drugs which cause her to be nauseated?
◆ Can she tolerate non-steroidal anti-inflammatory drugs (NSAIDs)?
◆ Does she suffer from travel sickness?
◆ Are there any medications she takes for travel sickness that she finds effective?
◆ Were there any antiemetics she found helpful following her last operation?
Wide local excision could be carried out under local infiltration, but axillary node sampling is unlikely to be tolerated. Paravertebral block is used by many centres for breast surgery and could be considered. Some centres will use this technique for day case surgery. An epidural covering dermatomes C8–T5 could, in theory, be used (insertion C7/T1). There are a number of risks involved in epidural analgesia, and careful balancing of the risks and benefits would be needed. The authors are unaware of any institutions where cervical/thoracic epidural anaesthesia for day case procedures is routinely carried out.
◆ Use a technique and drugs that will minimize the risk of nausea
◆ Avoid drugs that have emetic effects, if possible, and use multimodal antiemetics
◆ Use drugs with half-lives that maximize the chance of same-day discharge.
◆ Avoid long preoperative fasting, and hence dehydration, so limit fluid fasting to 2 hours for water or clear fluids
◆ Early on morning or afternoon list with 6-hour solids fasting
◆ Premedication: consider hyoscine patch, omeprazole 20–40 mg if history of dyspepsia, benzodiazepine anxiolysis only if absolutely necessary as may decrease chance of same-day discharge.
◆ Airway: laryngeal mask airway (LMA) or tracheal tube—both acceptable
◆ Breathing: spontaneous ventilation or intermittent positive pressure ventilation (IPPV)—both acceptable. Muscle relaxant is not required for surgical reasons. IPPV will increase risk of PONV if gas is forced into the stomach
◆ Induction: ideally use propofol TIVA. Thiopental and etomidate should be avoided, as they may be emetogenic. Remifentanil is an ideal agent to cover airway manipulation without long-lasting opioid effects and could be used. Nitrous oxide should be avoided. Bag-and-mask ventilation should aim to minimize inflation of the stomach. Short-acting opiate may be required to aid LMA/ETT placement. Fentanyl and alfentanil can be considered, though fentanyl has the advantage of being less likely to cause apnoea when using an LMA, yet being redistributed prior to emergence if used in a small enough dose
◆ Maintenance: the optimal choice for this patient’s procedure is propofol, delivered by TCI
◆ Analgesia: minimally emetogenic, analgesic options include:
• Clonidine: 75–150 micrograms IV, but this will result in significant post-operative sedation and will make same-day discharge unlikely
• Ketamine: 0.15 mg/kg IV, following induction, will provide excellent analgesia, but with likely side effects of hallucinations and sedation which will prevent same-day discharge
• Paracetamol: 1 g either pre- or intraoperative
• Bupivicaine: 2 mg/kg infiltration by surgeon at end of case
• Oxycodone can be considered and has been found to be less emetogenic than other opiates in our unit
• Tramadol is not minimally emetogenic. Some patients may tolerate its emetic side effects if it is given prior to emergence, though this is not reliable.
◆ Antiemetics: combination antiemetic therapy is vital for this patient. The mainstay would be a 5-HT3 antagonist such as ondansetron, granisetron, or dolasetron. An H1-antagonist (antihistamine) would commonly be added, e.g. cyclizine 50 mg. Adjuncts include: dexamethasone, an anticholinergic such as a hyoscine transdermal patch, or an antidopaminergic agent such as piperizine, prochlorperazine, droperidol. There is conflicting evidence regarding the antiemetic efficacy of metoclopramide
◆ Acupuncture and acupressure are also reported to be useful in some patients.
◆ Regular paracetamol, oral 1 g 6-hourly
◆ NSAIDs, e.g. ibuprofen 400 mg qds or diclofenac 50 mg tds, are usually avoided in the first 24 hours following breast surgery, due to a perceived increased risk of haematoma. Consider gastric protection, such as ranitidine or lanzoprazole, if longer duration therapies of NSAIDs are used
◆ Tramadol 50 mg is unlikely to be better tolerated than dihydrocodeine 30 mg as take-home analgesia for breakthrough pain, but there is some interindividual variation. Ask if the patient has prior experience and any preference
◆ Oxycodone can be considered and may be less emetic than other opiates.
Yes. There is some evidence that the administration of IV fluid in the perioperative period decreases PONV.
Palonosetron is a second-generation 5-HT3 blocker with a 40-hour half-life. It may be more effective for post-discharge nausea and vomiting. It does not seem to prolong QTc.
Yes, a number of these drugs have sedative effects and long half-lives and, when combined, can produce marked sedation which may last a number of hours. The patient would need to be observed in the recovery area (PACU), prior to returning to a ward environment where staff would need to be informed that longer-acting drugs had been used and to be vigilant for signs of sedation. The aim is for same-day discharge, so the use of sedating drugs with long half-lives is to be avoided.
She may still be suitable if some longer-acting drugs were used, though this would depend on the rate and nature of her recovery. Performing her surgery earlier in the day would allow time for her to recover and being fit for discharge on the day of surgery. The priority is to provide safe and effective anaesthesia and antiemesis. Day of surgery discharge should be aimed for, but not to the extent of compromising care. Careful anaesthesia and a 1-night post-operative stay are preferable to a poorly considered technique and a 4-day inpatient stay.
Summary
There has been an increasing drive towards day case surgery. Certain criteria must be fulfilled for this to be done safely. This includes the patient having the necessary domestic support before they can be discharged. In addition, they can only be discharged home when they are comfortable and any PONV is adequately treated. Analgesia will usually involve a multimodal approach.
Although the management of PONV is important in any field of anaesthesia, it is especially important in day case surgery, due to the effect this will have on discharge.
The anaesthetist has an important role in both the management of post-operative analgesia and the prevention and treatment of PONV.
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