Sepsis: the Sepsis Six and Source Control

Sepsis on the ward is graded on the NEWS2 score, and a patient with suspected infection and a score of 7 or more is at high risk of severe illness or death. According to NICE guideline NG253, published on 19 November 2025 and replacing NG51, high risk means broad-spectrum intravenous antibiotics and a fluid bolus within 1 hour. At the CT1 anaesthetics interview the marks are for that hour, for the source, and for saying who you call when the patient does not respond.

Key takeaways

• NG51 no longer applies: NICE replaced it on 19 November 2025 with NG253 for people aged 16 or over, NG254 for under 16s and NG255 in pregnancy
• NEWS2 bands the risk: 7 or more is high, 5 or 6 moderate, 1 to 4 low and 0 very low, interpreted alongside the patient's physiology and comorbidities
• High risk gets broad-spectrum intravenous antibiotics within 1 hour of the NEWS2 score being calculated, plus a fluid bolus without delay
• Fluid is a 250 ml balanced crystalloid bolus ideally over 10 to 15 minutes, repeated in 250 ml steps to a maximum of 1,000 ml, reassessing after each
• The UK Sepsis Trust Sepsis Six, reissued in 2025 against NG253, is six actions inside one hour, with drainable sources drained always within 12 hours
• No response within 1 hour of any intervention means the senior clinical decision maker attends in person, critical care is involved and the consultant is told

How do you recognise sepsis on the ward?

You recognise sepsis on the ward as suspected or confirmed infection plus physiological derangement, scored with NEWS2. NG253 asks for history, examination findings that suggest infection, and the NEWS2 score together, interpreted in context.

The guideline also lists findings that should push your judgement above the score alone: a mottled or ashen appearance, a non-blanching petechial or purpuric rash, and cyanosis of the skin, lips or tongue.

However, deterioration counts too. NG253 says to rate the risk higher than the NEWS2 suggests if the patient has worsened, or failed to improve, since the last score or the last intervention.

Which NEWS2 score puts the patient at high risk?

A NEWS2 score of 7 or more in a patient with suspected or confirmed infection suggests high risk of severe illness or death from sepsis. NG253 sets 5 or 6 as moderate, 1 to 4 as low and 0 as very low.

A single parameter scoring 3 points is its own trigger. The guideline asks for a high-priority review by a clinician with core competencies in the care of acutely ill patients, at foundation year 2 level or above.

The rescore interval follows the band: every 30 minutes at high risk, hourly at moderate risk, every 4 to 6 hours at low risk, and with routine observations at very low risk. Deterioration restarts the clock.

What is the Sepsis Six, and what is the time limit?

The Sepsis Six is the UK Sepsis Trust's six actions completed within one hour of a red flag in a patient with suspected sepsis. Its 2025 acute hospital tool was rewritten against NG253.

• Inform a senior clinician, noting that not every red flag needs the Sepsis Six urgently and a senior decision maker at ST3 level or equivalent may find another diagnosis
• Give oxygen if required, starting below a saturation of 92% and aiming for 94 to 98%, or 88 to 92% if at risk of hypercarbia
• Send bloods including cultures: blood cultures, venous gas, glucose, lactate, full blood count, urea and electrolytes, liver function, C-reactive protein and clotting
• Give intravenous antibiotics and think about source control, escalating if the patient is already on antibiotics
• Give intravenous fluids and consider vasopressors: 250 ml of Hartmann's or saline over 10 to 15 minutes, repeated up to 1,000 ml, then call an ST3 or above to attend
• Monitor with NEWS2 and urine output, repeating the lactate at least hourly if it was raised or the picture changes

The tool adds an escalation rule. If the septic patient is worsening or not improving after one hour, escalate to the consultant, and reassess NEWS2 at least every 30 minutes.

How much fluid, and how fast?

Fluid resuscitation in sepsis is now a 250 ml bolus, ideally over 10 to 15 minutes, of an isotonic balanced crystalloid such as Hartmann's, or 0.9% sodium chloride if a balanced solution is not available. That is NG253, 2025.

Further 250 ml boluses follow if needed, up to 1,000 ml in total including anything already given, with reassessment after each one. If 1,000 ml has not improved the patient, get advice from a senior clinical decision maker.

The older 500 ml figure many candidates quote is the Resuscitation Council UK number for undifferentiated hypotension, not the sepsis number. Knowing which guideline each volume belongs to is itself a mark.

When do antibiotics have to be given?

In the high-risk septic patient, broad-spectrum intravenous antibiotics go in within 1 hour of the NEWS2 score being calculated on initial assessment in the emergency department or on ward deterioration.

At moderate risk, NG253 allows a foundation year 2 or above to consider deferring broad-spectrum antibiotics for up to 3 hours while a more specific diagnosis is sought, and up to 6 hours at low risk.

That said, deferral is conditional. Once a decision to give antibiotics is made, the guideline says not to delay administration any further, and moderate risk with a lactate over 2 mmol/L or acute kidney injury is treated as high risk.

What does source control actually mean?

Source control in sepsis means finding the infection and removing, draining or debriding it. NG253 asks for microbiological and blood samples before any antimicrobial, and for the search to start alongside treatment.

• Consider urine analysis and a chest radiograph in every patient with suspected sepsis
• Consider imaging of the abdomen and pelvis if no likely source is found after examination and initial tests
• Involve the relevant surgical team early where surgery or radiology could control the source
• The surgeon or interventional radiologist seeks senior advice on timing and carries out the intervention as soon as possible
• The UK Sepsis Trust tool puts a limit on it: a source amenable to drainage is drained as soon as possible, and always within 12 hours

In practice this is where an anaesthetic CT1 becomes relevant. The septic patient with a drainable collection needs an anaesthetist to get them to theatre safely, not just antibiotics on the ward.

What do you do if the patient does not respond?

If the high-risk septic patient does not respond within 1 hour of any intervention, NG253 gives three simultaneous actions: the senior clinical decision maker attends in person, critical care is involved, and the responsible consultant is informed.

Vasopressors are a discussion, not a reflex. The guideline asks you to discuss with critical care, or the senior decision maker if critical care is unavailable, whether to start them and whether to start them peripherally.

Before starting them, NG253 wants a shared decision with the patient and, where appropriate, family, taking account of overall condition and any escalation plan, while acknowledging there may not be time for every conversation.

What do the assessors score besides the bundle?

Beyond the bundle, the assessors in a sepsis scenario score antimicrobial stewardship and honesty about uncertainty. NG253 builds in deferral windows precisely so that broad-spectrum antibiotics are not the automatic answer to every derangement.

The UK Sepsis Trust tool words it well, and it is worth quoting: where senior clinical input is available, experienced clinical judgement should trump any clinical tool. Say that, and you sound like a clinician rather than a checklist.

Reflective practice is a named domain, so a real example lands: a septic patient in whom you started the bundle and later found a different diagnosis, and what you now do differently before committing to broad-spectrum cover.

Which mistakes cost marks in a sepsis scenario?

The sepsis mistakes at interview are mostly out-of-date facts said confidently. The guideline changed in November 2025 and most revision material has not caught up.

• Quoting NG51: it was replaced on 19 November 2025 by NG253, NG254 and NG255
• Giving 500 ml boluses in sepsis, when NG253 gives 250 ml up to a total of 1,000 ml
• Treating the Sepsis Six as compulsory for every red flag, when the tool itself allows a senior decision maker to seek another diagnosis or de-escalate
• Forgetting the lactate: moderate risk with a lactate over 2 mmol/L or acute kidney injury is managed as high risk
• Naming antibiotics but never naming the source, when drainage is what actually stops the sepsis
• Never saying when you would call, so the answer has no escalation point at all

How this comes up at the CT1 anaesthetics interview

Sepsis reaches the clinical judgement station as a ward call: a post-operative patient with a rising NEWS2, or an unwell patient with a lactate of 4. The station is 15 minutes after five minutes of reading, marked out of 50 by two assessors.

Clinical judgement and decision making is scored on the risk band, the hour and the source. Reflective practice is scored on stewardship and on what you would change, and working under pressure on your rescore intervals and your escalation point.

The follow-up usually adds a complication: 1,000 ml has gone in and the blood pressure has not moved, or there is no critical care bed. anaestheticinterview's bank of 340 questions carries AI-marked spoken practice, which is where these numbers stop being revision and start being answers.