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Conduct of anaesthesia

Conduct of anaesthesia
Use local anaesthetic, or short-acting general anaesthetic drugs which have few residual psychomotor effects and a low incidence of postoperative nausea or vomiting (PONV).
Preoperative
  • Nurses, surgeon, and anaesthetist will need to undertake an adequate history and examination as a full medical clerking is not usually performed by junior medical staff. This should include blood pressure measurement and cardiorespiratory examination. Consent should be performed by the operating surgeon either in the outpatient department or on the day of surgery.
  • Avoid premedication if at all possible. If necessary use oral midazolam (up to 0.5 mg/kg) in a little undiluted sweet fruit cordial (as it tastes awful) for children, or temazepam (10–20 mg) in adults.
  • There is no evidence for any increase in regurgitation/aspiration in day case patients so the routine use of antacid drugs is probably unnecessary. However, in those with a history of regurgitation ranitidine (300 mg PO) or omeprazole (40 mg PO) is appropriate.
  • NSAIDs, e.g. diclofenac 50–100 mg, given orally or rectally, reach peak effect after 1–2 h and are a useful adjunct to anaesthesia, with very few sideeffects. Remember that slow release oral preparations do not reach steady state concentrations until after several doses, and are thus not useful for early analgesia.
Perioperative
  • Total intravenous anaesthesia with propofol is widely used. Inhalation of oxygen-enriched air will also allow omission of nitrous oxide. Propofol induction with isoflurane/sevoflurane maintenance is an alternative.
  • Incremental fentanyl, often 2–4 µg/kg in divided doses.
  • Diclofenac (PO/PR) and local anaesthetic for every suitable patient/operation.
  • Whenever possible use a laryngeal mask airway, avoiding intubation, muscle relaxants, and reversal agents where possible. Laryngeal masks for gynaecological laparoscopy and armoured laryngeal masks for wisdom tooth extraction, and many nasal operations can be used safely in most circumstances.
  • Antiemetics are not indicated routinely but should be reserved for treatment of any PONV or prophylaxis in those with a history of PONV.
Postoperative
  • The inclusion of opioids, NSAIDs, and local anaesthetics should provide early analgesia. If more analgesia is needed it is imperative to treat it early. 50–75 µg fentanyl provides good, fast-onset analgesia.
  • Give morphine if stronger analgesia is required. Remember that pain worsens nausea.

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  • Simple oral analgesics may be of help, as may physical therapies such as hotwater bottles, particularly for the cramping lower abdominal pain following gynaecological surgery.
Postoperative nausea and vomiting
A multifactorial approach to the prevention of PONV should be used. Early ambulation is a risk factor for PONV, so all day case patients should be treated as high risk. PONV must be fully controlled before discharge home.
TIVA propofol, omitting nitrous oxide, mutimodal analgesic therapy, good hydration, and minimal (2 h) fluid fast are appropriate. This is a recipe approach which works well and leaves a small number of patients requiring treatment, which can then be cost effectively done with a 5-HT3 antagonist such as ondansetron.
Regional anaesthesia
Regional anaesthesia is widely used in Europe and North America for day case anaesthesia. PONV is reduced. Timing and planning are important as blocks take a longer time to set up or wear off compared with general anaesthesia. Perform spinal anaesthetics early on the list, to allow maximum time for recovery. Spinals must have worn off completely before discharge to allow safe ambulation. However, it is reasonable to discharge patients with working plexus blocks thus allowing the benefit of prolonged postoperative analgesia. Remember that patients need special instructions on care of the anaesthetized part so as to avoid inadvertent damage. This would include a sling for patients with brachial plexus blocks.
Local anaesthesia and sedation
With increased use of local anaesthetics, short-acting sedative drugs will inevitably be used to increase tolerability. It must be noted that sedation is a poor adjunct to an imperfect local anaesthetic block. However, judicious use of intermittent midazolam or propofol infusions (TCI 1–1.5 µg/ml) can provide good amnesia with few postoperative effects. If sedation is to be used it must be provided and monitored by someone other than the operating surgeon.
Specific blocks
  • Field block: excellent for LA hernia repair as provides postoperative analgesia and obviates the need for general anaesthesia.
  • Spinals: use 25/26 gauge pencil point needles and 0.25% heavy bupivacaine (1:1 diluted 0.5% heavy bupivicaine and sterile saline). This gives a similar onset of anaesthesia with a shorter discharge time (4 versus 6 h).
  • Epidurals are less suitable due to the time factor in achieving block.
  • Caudals: use dilute solutions (0.125% bupivacaine) add preservative free ketamine 0.5 mg/kg or clonidine 1 µg/kg to prolong the block for up to 24 h. Warn the patients about ambulation difficulties.
  • Brachial plexus blocks: use axillary approach (low incidence of pneumothorax). If used with GA use dilute local anaesthetic (0.25% bupivacaine) to minimize motor block. If without GA, take onset time into account when planning the list.
  • The use of femoral nerve blocks is controversial as mobilization is difficult.

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Discharge drugs
All patients should have a supply of suitable oral postoperative analgesics at home or be given it to take home. Inguinal hernia repair, laparoscopic surgery, wisdom tooth extraction, etc. should be given at least 2 days’ supply of analgesics (diclofenac 50 mg three times a day, Cocodamol-a combination of codeine/paracetamol 30 mg/500 mg 2 tablets four times a day or similar).

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Postoperative admission
Reasons for overnight admission:
  • Do not fulfil discharge criteria before unit closes.
  • Observation after surgical or anaesthetic complications.
  • Unexpectedly more extensive surgery.
  • Inadequate social circumstances.
  • Uncontrolled pain or PONV.
Overall unanticipated admission occurs in between 0.5 and 2.0% of cases, depending on the mix of surgery.
Gynaecology and urology have the highest admission rates. Surgical causes of hospital admission are three to five times greater than anaesthetic causes. Common anaesthetic reasons for hospital admission are inadequate recovery, nausea and vomiting, and pain. Anaesthesia-related complications are more frequent with general anaesthesia than with local anaesthesia plus sedation or regional anaesthesia. Surgical reasons include bleeding, extensive surgery, perforated viscus, and further treatment. Admissions still occur when social circumstances have changed, i.e. patient has no one for 24 h supervision.
Further reading
Chung F, Mezei G (1999). Adverse outcomes in ambulatory anesthesia. Canadian Journal of Anesthesia, 46, R18–R26.

Liu S S (1997). Optimizing spinal anesthesia for ambulatory surgery. Regional Anesthesia, 22, 500–10.

Peng PWH, Chan VWS, Chung FFT (1997). Regional anaesthesia in ambulatory surgery. Ambulatory Surgery, 5, 133–43.

Rowe WL (1998). Economics and anaesthesia. Anaesthesia, 53, 782–8.

Website of the British Association of Day Surgery: http://www.bads.co.uk (for updates and new day surgery links).
Website of the Society of Ambulatory Anesthesia: http://www.sambahq.org (use ‘search’ for ‘core curriculum’).

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