A guide to pre-operative fasting

Dr. Manith Kha

Consultant Anaesthetist

Cathy Andrews

Clinical Services Coordinator

June 2008

Rationale for Pre-operative fasting

• Patients are fasted from fluids & solids prior to surgery to reduce the risk of vomiting and aspiration of stomach contents.

• The literature supports a fasting time of 6-8 hours prior to surgery for solids and 2 hours for clear fluids.

• Some patients are thought to be at greater risk of aspiration or vomiting than others. There is limited research available with these patient groups and so they are treated with caution.

• If in doubt, refer to the home team.

Who is at risk of vomiting / aspiration?

• All patients undergoing general anaesthesia are at risk, but for some the risk is thought to be greater. This includes:

– The obese (BMI over 30)

– Patients who may have delayed gastric emptying – those with reflux, hiatus hernia, neurological disorders or neuropathies such as diabetics.

– Patients with a difficult airway

– Patients with sepsis or renal failure

– Pregnant or immediately post partum women

What are the consequences of prolonged fasting?

• Prolonged fasting periods can be detrimental to patient outcomes. Possible consequences include:

– Psychological effects –confusion, irritability, a sense of isolation.

– Physical effects – dehydration, thirst, headaches, hypoglycaemia and electrolyte imbalance, nausea or vomiting.

– Increased incidence of post operative nausea & vomiting.

Why are patients fasted for longer than necessary?

• The most common reason for patients to be fasted for extended periods is that it is easy and convenient for staff to do so.

• There is uncertainty over what the policy actually is.

• Different units have different “routines”.

• Sometimes it is unclear what time an operation will take place – for example if the patient is on an ‘Emergency List’

• Staff sometimes don’t have the knowledge to inform their practice.

So what is the policy at the Queen Elizabeth?

• The QEH pre-op fasting protocol was revised in 2002 and since this time it has been policy to fast patients for 6 – 8 hours prior to surgery.

• In 2007 a number of the JBI procedures were adopted by the QEH. The JBI procedure (Pre-operative care: Fasting) explains the rationale behind fasting periods and differs slightly from the old QEH protocol.

• In view of this it is felt it is timely to revisit our pre-op fasting procedure and provide clear guidelines and supporting education.

The new policy

DEPARTMENT OF ANAESTHESIA THE QUEEN ELIZABETH HOSPITAL

PRE-OPERATIVE FASTING GUIDELINES*IF IN DOUBT – CONSULT THE ANAESTHETIST*

Patients scheduled for surgery

ELECTIVE SURGERY : Minimum fasting times:•8 hours after meat, fried or fatty foods•6 hours after light meal, milk, juice, cordial or carbonated drinks, lollies or chewing gum, tea or coffee•2 hours after water – maximum last drink 150ml•Small sips of water may be given with pre-operative oral medications

MORNING LISTS:•Fast (from foods, drinks, lollies and chewing gums) from midnight•Water only until 6AM preoperatively - maximum last drink 150ml•Oral medications should be continued with a sip of water unless specifically discontinued by medical staff

AFTERNOON LISTS:•Fast (from foods, drinks, lollies and chewing gums) after a light breakfast (e.g.. tea and toast) at 6AM•Water only until 10AM preoperatively - maximum last drink 150ml•Oral medications should be continued with a sip of water unless specifically discontinued by medical staff

ALL DAY LISTS:•Fast as for morning lists even if on latter parts of the lists (order of cases on lists may change at short notice)

EMERGENCY SURGERY :•Remain fasting from foods, drinks, lollies and chewing gums unless otherwise stated•Oral medications should be continued with a sip of water unless specifically discontinued by medical staff•Intravenous fluid therapy may be necessary•Any doubt - consult medical staff

PATIENTS ON FAST TRACK PROTOCOL – NO RISK OF DELAYED GASTRIC EMPTYING•Fast as above•Nutricia carbohydrate drink may be given 2 hours preoperatively

PATIENTS WITH RISKS OF DELAYED GASTRIC EMPTYING•E.g.. Obesity or BMI>30, hiatus hernia or reflux, diabetes, renal failure, sepsis, difficult airway•Fast as for normal patients•Nutricia carbohydrate drink may be given 6 hours but not 2 hours preoperatively

FASTING AND ORAL MEDICATIONS :•Oral (especially cardiac and slow release opioid) medications should be continued while fasting unless specifically discontinued by medical staff•Any doubt about particular drugs and/or situations – consult relevant medical staff

The new policy.

• Elective surgery patients:

– Fast from food for 8 hours after meat, fried or fatty foods

– Fast from food for 6 hours after a light meal, milk, juice, cordial, carbonated drinks, tea or coffee. Lollies and chewing gum are also not permitted.

– Patients may drink water until 2 hours prior to surgery.

– The last drink of water should not exceed 150mls. That is, if the patient has to fast from 10am, they may only have 150mls water from 9am to 10am.

– Small sips of water may be given with medications.

The new policy.

Elective surgery cont..

Morning lists:

– Will fast from solids from midnight but may drink water until 6am (maximum last drink 150mls)

Afternoon lists:

– Will fast from solids after a light breakfast at 6am but may drink water until 10am (max last drink 150mls)

All day lists:

– Have to fast as for morning lists as the list may be subject to change.

The new policy.

Emergency surgery:

– Discuss with medical staff.

– Unless otherwise stated, to remain fasting from all food, drinks, chewing gum etc.

– Consider IV fluid therapy.

• NB – there may be some exceptions to this regimen – such as patients requiring bowel prep who will be prescribed a low residue / clear fluid diet 24 hours prior to surgery

The new policy.

“Nutricia” high carbohydrate drink:

– Certain surgical units, including those with “fast track” patients, allow a carbohydrate drink “Nutricia” to be given pre-operatively.

– For those with no risk of delayed gastric emptying this is prescribed 2 hours pre-operatively.

– Patients with risks of delayed gastric emptying may still be given this drink 6 hours pre-operatively.

What about medications?

• Unless otherwise stated, all oral medications should be continued whilst the patient is fasting.

• This includes slow release opioids and cardiac medications.• Medications which may be held after discussion with medical

staff include;– Those that have to be given with food, such as NSAID’s– Those that need to be given with lots of water, such as

biphosphonates.– Oral anti-hyperglycaemics.

• NB patients may have diuretics held for minor surgery of a long duration under regional analgesia +/- sedation due to concerns about incontinence

References

• For a list of supporting evidence please refer to the JBI Pre-operative Care: Fasting procedure.

• This is located in the TQEH clinical practice manual available on the hospital intranet.

• http://qehintranet/tqeh/policies_procedures/policies_procedures_tqeh/clinical_manuals/clinical_practice_manual_new.jsp