Perioperative clear fluid fasting: sip til send.
An independent, clinician-maintained reference on the sip til send model, the supporting evidence, local implementation reports and professional society guidelines.
What it is
Sip til send allows patients scheduled for elective anaesthesia to drink specified clear fluids until they are called to theatre, rather than observing a fixed minimum fasting interval for fluids.
Published protocols typically permit up to 200 mL per hour for adults and 3 mL/kg per hour for children, though the volume cap varies by jurisdiction — for example, CPOC (UK) specifies up to 170 mL per hour for adults (and for children ≥55 kg), with no further fluids in the hour immediately before anaesthesia. Minimum fasting intervals for solids and non-clear liquids are unchanged.
Individual aspiration-risk assessment is retained under every published protocol. Patients with delayed gastric emptying, bowel obstruction, GLP-1 receptor agonist therapy or other relevant risk factors are managed according to that risk, not the standard pathway.
Regimens compared
Traditional NBM
Clear fluids stopped at a set time, historically midnight or 6 hours before anaesthesia.
2-hour minimum fast
Clear fluids permitted up to 2 hours before induction. The minimum retained in current ASA and ANZCA guidance.
Sip til send
Clear fluids permitted until the patient is called to theatre. Recognised in ANZCA PG07 and state-level guidance in Victoria and NSW.
How it came about
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1946
Mendelson's syndrome described
Aspiration pneumonitis in obstetric anaesthesia reported, the basis for conventional fixed-fasting practice. Mendelson CL, Am J Obstet Gynecol 1946;52:191–205.
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1986
Early trials on shorter fasting
Maltby et al. report clear fluids 2–3 hours before anaesthesia do not increase gastric residual volume compared with prolonged fasting.
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1999
ASA 2-hour guideline
The American Society of Anesthesiologists publishes practice guidelines permitting clear fluids up to 2 hours before elective anaesthesia in healthy patients.
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2022
Paediatric liberalisation and single-centre QI reports
ESAIC publishes a paediatric fasting guideline supporting fluids up to 1 hour before anaesthesia (Frykholm et al., Eur J Anaesthesiol 2022;39:4–25). A German centre (Bremen) publishes an iterative quality-improvement study moving to unrestricted clear fluid intake (Rüggeberg & Nickel, Anaesthesia 2022;77:1386–1394).
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2021
"Sip til send" introduced at NHS Tayside
Following a department poll and audit evidence of a mean 7.5-hour fluid fast, NHS Tayside (Ninewells Hospital, Scotland) develops and implements a sip til send protocol from December 2021, generally credited with coining the term. CPOC resource page →
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2023
Wider adoption begins; SipTilSend Network ANZ formed
The Australasian SipTilSend Network is established; Royal Adelaide Hospital and Cairns Hospital adopt the model. More than 30 UK NHS trusts adopt sip til send policies following the NHS Tayside model (per CPOC). A Dutch academic centre publishes a before-and-after cohort of a liberal fluid policy (Marsman et al., JAMA Surg 2023;158:254–263).
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2024
ANZCA guideline recognition
ANZCA PG07 recognises sip til send. Safer Care Victoria and NSW ACI publish state-level clinical guidance.
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2025
EUROFAST published; MARS recruitment opens
Frykholm et al. report a 31-centre, 306,900-anaesthetic cohort (Br J Anaesth 2025;135:141–147) finding statistical non-inferiority of sip til send versus 2-hour fasting for confirmed pulmonary aspiration in children. The Australasian MARS study (see Local implementation) opens recruitment across more than 40 hospitals.
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2026
Further evidence and an adult consensus statement
A systematic review and meta-analysis of paediatric fasting duration is published, supporting EUROFAST's findings (Dabke et al., Br J Anaesth 2026;136:158–166). An international, multidisciplinary consensus statement on adult perioperative fasting is published (Rüggeberg, Bilotta et al., Anaesthesia 2026;81:840–851). ANZCA PG07's fasting appendix is revised. MARS remains underway; see Key papers for current status.
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