17.11 — Sepsis

Sepsis kills around 11 million people a year — roughly one in five of all deaths worldwide.

And the damage is done by the response, not by the organism.

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. Every word of that definition is deliberate, and the useful one is dysregulated.

Mortality rises by several percent for every hour of delay in treatment. Which makes this a chapter about recognition more than about anything else.

What goes wrong

The changes that are useful locally become catastrophic when they occur everywhere at once (Chapter 13.4).

Vasodilation throughout the body — blood pressure collapses.

Increased capillary permeability everywhere — fluid leaves the circulation into the tissues. So the person is simultaneously waterlogged and intravascularly empty, which is why they need large volumes of fluid while their legs and lungs swell.

Widespread clotting activation — microclots block small vessels, consuming platelets and clotting factors, so the person clots and bleeds at the same time (Chapter 7.1).

Impaired oxygen use at cellular level — the mitochondria stop working properly even when oxygen is delivered.

And organs fail — kidneys, lungs, liver, brain, heart, in sequence.

Septic shock is the subset with persistent low blood pressure requiring drugs to support it, plus a raised lactate — and mortality is around 40 percent.

Recognising it

This is the part that matters, and it belongs to everybody rather than only to clinicians, because sepsis presents at home before it presents to a hospital.

The signs, in an adult:

Slurred speech or confusion.Extreme shivering, or severe muscle pain.Passing no urine in a day.Severe breathlessness.A feeling that something is seriously wrong — patients and families frequently describe a sense of impending doom, and it is a real and under-weighted sign. Skin that is mottled, blue or unusually pale.

In a child, add: fast breathing, a rash that does not fade under pressure, a fit or convulsion, unusual coldness, abnormal sleepiness or floppiness, and not feeding.

Two things that catch people out:

Temperature can be high or low. A low temperature in sepsis is more ominous than a high one.

And the source may be obvious or entirely hidden. Chest, urine, abdomen, skin and lines are the commonest, and in a substantial minority no source is ever found.

And the single most useful thing a member of the public can do is ask the question.

"Could this be sepsis?"

Campaigns encouraging patients and families to say it have measurably improved recognition, because it triggers a specific set of actions rather than a general reassessment.

What is done

Time-critical, and defined as a bundle to be completed within the first hour.

Blood cultures — taken before antibiotics wherever possible, because a single dose substantially reduces the yield (Chapter 17.1).

Antibiotics — broad-spectrum, immediately, narrowed later when the organism is known.

And antibiotics within the first hour save lives, demonstrated repeatedly.

Intravenous fluids — because the circulation is depleted.

Lactate measurement — a raised lactate indicates tissues are not getting enough oxygen (Chapter 1.6), and it is one of the strongest single predictors of death. It is also used to judge whether treatment is working.

Oxygen.

Urine output monitoring — a catheter, because falling urine output is an early sign of organ failure.

Then: source control — draining an abscess, removing an infected line, operating on a perforated bowel. Antibiotics do not cure an undrained collection (Chapter 14.4).

Vasopressors where fluid alone does not restore blood pressure.

And organ support — ventilation, dialysis — in intensive care.

What has not worked, which is worth saying: a long list of immune-modulating therapies has been tried and failed in trials, including activated protein C, which was licensed and then withdrawn. Steroids have a modest role in septic shock. The pattern is that dampening a dysregulated response without knowing which part is dysregulated has proved very difficult.

Who is at risk

The very young and the very old.Pregnancy and the postpartum period — sepsis remains a leading direct cause of maternal death (Chapter 15.7). Immunosuppression, chemotherapy, and asplenia (Chapter 7.8). Diabetes, liver disease, kidney disease.Indwelling lines and catheters.Recent surgery.And injecting drug use.

Neutropenic sepsis deserves separate emphasis (Chapter 7.1). A fever in someone on chemotherapy is an emergency, treated with intravenous antibiotics within the hour, before any results. The usual signs of infection are muted, because the cells that produce them are absent — there may be no pus, no redness, and very little to find.

After sepsis

And this is under-recognised.

Survivors frequently do not simply return to normal.

Post-sepsis syndrome — fatigue, muscle weakness, breathlessness, cognitive impairment, anxiety and depression, lasting months.

And mortality remains elevated for years afterwards.

The causes are multiple: the illness itself, the immobility, the intensive care experience, and often a permanent step down in functional reserve.

Rehabilitation helps, and it is frequently not offered, because the person was discharged alive and the episode was treated as closed.

Prevention

Vaccination — pneumococcal, influenza, meningococcal, Hib, and COVID-19. A substantial proportion of sepsis begins as a vaccine-preventable infection.

Treating infections promptly and adequately.

Infection control — hand hygiene, line care, and removing devices that are no longer needed (Chapter 17.4).

Wound care.

And knowing your own risk. A person without a spleen, on immunosuppression, or on chemotherapy should know that fever means seeking help the same day rather than waiting.

The encouraging part

Sepsis mortality has fallen substantially over the last two decades — driven not by new drugs but by earlier recognition, protocolised care bundles, and better organ support.

Screening tools embedded in hospital records now flag deteriorating patients automatically, and rapid response teams act on them.

And public awareness campaigns have worked. The UK Sepsis Trust and equivalents elsewhere have made "sepsis" a word ordinary people use, which is precisely the mechanism by which recognition improves.

The single sentence worth carrying out of this chapter: if someone with an infection becomes confused, very breathless, stops passing urine, or looks seriously unwell, that is an emergency — and saying the word "sepsis" is a reasonable thing to do.

What the next page fixes

Antibiotics made bacterial infection treatable. Chapter 17.12 covers what is happening to them, why it is happening, and what actually slows it — because it is one of the few medical problems where individual behaviour genuinely aggregates into a global outcome.