Propofol infusion principles

What propofol is (and why infusions behave differently to boluses)

• Propofol is an IV hypnotic used for induction and maintenance of anaesthesia and for sedation.
• It has rapid onset and short effect after a single bolus, but with an infusion the drug can accumulate in tissues over time.
• Practical meaning: the longer the infusion runs, the more likely you need to reduce the rate to maintain the same depth (to avoid “over-shooting”).
• Propofol has no analgesic effect: you usually need opioid and/or regional/local anaesthesia for pain.

Common indications (new starter level)

• Maintenance of anaesthesia (e.g., TIVA) when volatile agents are not used or are undesirable.
• Sedation: procedures, transfer, ICU sedation (local policy dependent).
• Anti-emetic benefit: propofol can reduce postoperative nausea and vomiting compared with some alternatives.
• Seizure management: sometimes used by specialists for refractory seizures (follow senior guidance).

Before you start: key safety checks

• Confirm indication and target (anaesthesia vs sedation) and who is supervising/setting the plan.
• Check allergy history (rare true propofol allergy; be cautious with previous anaphylaxis to anaesthetic drugs).
• Baseline observations: BP, HR, SpO2, ECG; ensure capnography if the patient is ventilated or at risk of hypoventilation.
• IV access: reliable cannula (propofol is irritant; consider a larger vein; consider lidocaine or a running fluid to reduce pain on injection).
• Airway plan: propofol can cause apnoea and airway obstruction—have oxygen, suction, bag-mask, airway adjuncts ready.
• Prepare vasopressor strategy (e.g., metaraminol/phenylephrine/ephedrine as per local practice) and IV fluids if appropriate.

Setting up the infusion (practical steps)

• Use a dedicated infusion pump and a dedicated IV line/port where possible to avoid accidental bolus from line flushing.
• Label the syringe/line clearly: drug, concentration, date/time, and your initials (follow local policy).
• Use the correct concentration and syringe size for your pump setup; avoid “ad hoc” concentrations unless your department supports it.
• Prime the giving set carefully to remove air; ensure anti-siphon/anti-reflux valves are used if required by local policy.
• Be aware of dead space: changes in rate may take time to reach the patient depending on extension tubing and carrier flow.

Dosing principles (how to think about rates)

• Propofol dosing is usually weight-based (mg/kg/h or micrograms/kg/min) and adjusted to clinical effect.
• Typical pattern: higher rate initially, then reduce as the case progresses to avoid accumulation and hypotension.
• Sedation generally requires lower rates than general anaesthesia; always titrate to the minimum effective dose.
• Elderly, frail, hypovolaemic, and shocked patients often need much lower doses and are more prone to hypotension.
• When in doubt: make small changes, wait for effect, reassess (avoid rapid large swings unless clinically necessary).

What to monitor (and what changes mean)

• Depth: clinical signs (movement, tearing, tachycardia, hypertension) and, if used, processed EEG monitors (interpret in context).
• Ventilation: respiratory rate, capnography, tidal volumes (propofol can cause apnoea and reduced drive).
• Circulation: BP and HR—propofol commonly causes vasodilation and myocardial depression leading to hypotension.
• IV site: extravasation can occur; check for swelling/pain and poor effect despite high rates.
• Temperature: propofol anaesthesia can contribute to hypothermia—use warming measures.

Managing common first-time scenarios

• Hypotension after starting/increasing infusion: check depth, reduce propofol, give fluid if appropriate, use vasopressor early, and consider other causes (bleeding, anaphylaxis, high neuraxial block).
• Patient moving or “light”: check IV patency, pump running, line not occluded, adequate analgesia, and consider a small bolus plus a temporary rate increase (with senior support).
• Apnoea/airway obstruction during sedation: stop/reduce propofol, open airway (chin lift/jaw thrust), give oxygen, assist ventilation; escalate early.
• Pain on injection: use a large vein, consider lidocaine, and avoid small hand veins if possible.
• Delayed wake-up: stop infusion in good time, consider accumulation (long case), check other sedatives/opioids, temperature, glucose, CO2, and neurological causes.

Infection control and lipid emulsion precautions

• Propofol is a lipid emulsion and can support bacterial growth: use strict aseptic technique when drawing up and connecting.
• Follow local policy on maximum hang time and syringe change intervals (do not “top up” old syringes).
• Discard if contamination suspected or if the syringe has been in use beyond local limits.

Propofol Infusion Syndrome (PRIS): what new starters must know

• PRIS is rare but life-threatening; risk increases with high doses and prolonged infusions, especially in critical illness.
• Key features: unexplained metabolic acidosis, rhabdomyolysis, hyperkalaemia, acute kidney injury, arrhythmias, and cardiovascular collapse.
• If suspected: stop propofol, call for senior/ICU support urgently, and treat complications (ABG, CK, U&Es, ECG; supportive care).
• For routine theatre cases, PRIS is uncommon, but awareness is essential—especially for long infusions or ICU sedation.

Stopping the infusion and handover

• Plan emergence: stop or reduce in advance depending on case length, patient factors, and analgesia plan.
• Ensure antiemetic and analgesic plans are in place before stopping (propofol wears off quickly).
• Handover essentials: total propofol used, current/last rate, time stopped, other sedatives/opioids, haemodynamic issues, airway events, and any concerns (e.g., difficult IV access).