Pre-operative oral medications in nil by mouth(NBM) patient undergoing surgical procedure

Consideration for NBM:

• Pre or post surgery
• When the bowel is non-functional e.g. gastric outlet obstruction
• The patient is unable to swallow safely e.g. after a stroke, head injury, myasthenia gravis or reduced level of consciousness.
• Nausea or vomiting may also inhibit the intake of fluids, nutrition and oral medicines

Why NBM?

Patients are at risk of aspirating their stomach contents during general anaesthesia. Therefore minimum fasting periods for scheduled surgery are:

• 6 Hours for solid food, infant formula or milk
• 4 Hours for breast milk
• 2 Hours for water, dilute squash or tea/coffee with a small amount of milk
• As water leaves the stomach within 2 hours of ingestion, medicines can be given up to two hours before surgery with water.

Oral medications
To continue or omit prior to surgery? It may be appropriate to give the oral medicine. Consider:

1. Medicines that should be continued throughout the peri-operative period to prevent relapse of the treated condition or to avoid the effects of drug withdrawal.
2. Medicines that should be withheld before surgery to reduce the risks that they may impose upon the procedure.

Medications to CONTINUE

Medications	Exception
All cardiac or BP drugs (eg anti-anginal, anti-arrhythmia)	Except ACE inhibitors, ARB and diuretics (refer below) Amiodarone can be safely omitted for a few days as it has a very long half-life. Alpha blocker to continue if indicated for BP control. If for urinary retention and patient is catheterized, may be withheld if patient at risk of hypotension.
All epilepsy or Parkinsons drug
All asthma drugs/inhalers
All tablets which reduce gastric pH eg ranitidine, omeprazole, pantoprazole
All thyroid drugs
All major and minor tranquilisers eg benzodiazepines, antidepressants and nicotine patches
All steroids including inhalers
All immunosuppressants and cancer drugs
All analgesics (eg opiods)	Except NSAIDS

Medications to OMIT

Lithium	Omit due to risk of toxicity
NSAIDS	Omit unless prescribe as premed EXCEPTION: Cox-2 selective inhibitor (to continue) Non selective NSAIDs Possible increased risk of bleeding. If the risks of postoperative bleeding are high or where the consequences of even minor bleeding are significant e.g. retinal, stop NSAIDs 3 days before surgery to allow platelet function to recover.

Clozapine	Stopped 24 hours before surgery.
Glucosamine	Glucosamine may affect blood glucose control. Glucosamine and chondroitin may have an anticoagulant effect and should therefore be discontinued two weeks prior to surgery.

Aspirin, clopidogrel, dipyridamole, warfarin

Omit except for patients with coronary artery stent upon discussion with GP Should be stopped when risk of preoperative bleeding are high or where consequences of even minor bleeding are significant, balanced against risk of precipitating thromboembolic complications if these are stopped. To stopped generally 7 days before surgery to allow recovery of adequate platelet function  Warfarin ideally stop 5 days before surgery to allow INR to drop below 1.5. Epidural analgesia will require INR ≤1.5

MIXED review:

Medications	Consideration
ACE inhibitors/ ARB	May drop blood pressure during anaesthetic.  To withhold unless requested(1) ACE I  To continue therapy and inform the anaesthetist who may request the preop dose to be omitted(2) ARB For hypertensive patient’s likely to have an epidural anaesthetic, withhold on the morning of surgery. For congestive heart failure and/or history of myocardial infarction patients, continue therapy and inform the anaesthetist(2)
All diuretics	Depends on clinical judgement(1) Thiazide and loop diuretics need not be omitted. Any electrolyte imbalance should be corrected before surgery. Withhold if patient dehydrated but seek advice if patient has cardiac failure. Omit potassium-sparing diuretics on the morning of surgery as reduced kidney perfusion in the immediate post-operative period may predispose to hyperkalaemia.

Others

Drugs not essential in short term eg vitamins, iron, laxatives, osteoporosis treatment, liquid antacids, HRT, herbal can be omitted(1) Counteract arguments(2): COC should be discontinued 4-6 weeks before major elective surgery and all surgery to the legs to reduce the risk of thromboembolism. Alternative contraception e.g. progestogen only pill. Iron supplementations, continue unless bowel surgery then discontinue 7 days pre-operatively. Vitamins and mineral supplements can be continued. Herbal should be discontinued HRT Preferably discontinue 4 weeks prior to major surgery or where there is a high risk of a thromboembolic event. If not, HRT may be continued peri-operatively but thromboprophylaxis is recommended.

Kindly refer to link (2) for further information.

References:

1.http://www.uhs.nhs.uk/Media/subtideal/Doctors/SaferPrescribingWorkbook/Section4Appendix2-Peri-operativedrugs.pdf

2 http://www.worcsacute.nhs.uk/EasysiteWeb/getresource.axd?AssetID=11296