Sepsis

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection (2016 Society of Critical Care Medicine & European Society of Intensive Care Medicine task force).

  • Organ dysfunction is defined as an increase of two or more points in the SOFA score and is associated with an in-hospital mortality >10%.
  • There is no universal definition of infection; this is determined by the patient’s symptoms, clinical signs, baseline blood tests, radiology results and microbiological investigations. On presentation infection is often presumed, and relevant investigations can often take up to 24-48 hours to come back.

Sepsis is considered a disease process that occurs in a continuum:

Patients with septic shock suffer persistent hypotension requiring vasopressors to maintain a normal mean arterial pressure  (MAP) (i.e. ≥65 mmHg) and have a serum lactate >2 mmol/L despite adequate fluid resuscitation. Patients with septic shock have a hospital mortality over 40%.

Multiple organ dysfunction (MODS) is a clinical syndrome usually involving one or more of the respiratory, haematological, liver, renal, central nervous system (CNS) and cardiovascular systems occurring in the acutely ill patient and potentially rapidly leading to death.

Screening systems have been developed to help identify patients who may have sepsis and determine which of these patients are likely to have a poor outcome. It is important to remember screening systems do not diagnose sepsis, they cannot differentiate organ dysfunction caused by infection or another cause (e.g. a myocardial infarction) and they do not aim to influence treatment strategies.

The quick Sequential Organ Failure Assessment score (qSOFA) score assigns a score of one if the patient has any of the following:

  • Respiratory rate ≥22/minute
  • Altered mentation
  • Systolic blood pressure ≤100 mmHg

A score ≥2 is associated with a poor clinical outcome.

The National Early Warning Score 2 (NEWS 2) score is an aggregate scoring system derived from six physiologic parameters: respiratory rate, temperature, oxygen requirement, systolic blood pressure, conscious level and heart rate. The overall score should help determine the urgency and level of clinical response required as well as frequency of monitoring. It is endorsed as a system the helps detect patients with infection who are at clinical risk of acute deterioration due to sepsis.

The clinical assessment of patients who may have infection and sepsis should look for:

  1. Non-specific signs of infection: Hypo / hyperthermia, tachycardia, tachypnoea, hypotension
  2. Features of a specific source of infection: for a respiratory infection for example this would be cough, tachypnoea, low oxygen saturation, and possibly pleuritic chest pain
  3. Risk factors for sepsis: age ≥65 years, immunosuppression, diabetes, obesity, malignancy, or recent admission to hospital.

Also remember that the elderly, those with impaired immunity (e.g. patients with diabetes or cancer and those on immunosuppressant medication), and pregnant women may present atypically and a lower index of suspicion for infection and sepsis is required when assessing them.

Investigations for all patients with potential sepsis should include:

  • Baseline blood tests: full blood count, glucose, C-reactive protein, urea and electrolytes, coagulation, liver function tests 
  • Blood gas: assessing for hypoxemia, acid balance and lactate
  • Monitoring of hourly urine output
  • Relevant imaging looking for a source of infection: a CXR to look for pneumonia is considered standard, but where it is clinically suspected consider a CT or USS to assess for underlying intra-abdominal infections, or an echocardiogram to look for infective endocarditis for example
  • Microbiology: Blood cultures are considered “routine” microbiological investigations for everyone with suspected sepsis. Targeted investigations are also required to look for a source and organism, for example sputum samples for pneumonia, wound swabs for skin and soft tissue infections. Remember a positive culture is not required to make a decision regarding treatment with empiric antibiotics.

A diagnosis of sepsis secondary to infection is often made empirically at the bedside upon presentation, or retrospectively when follow-up data returns (e.g., microbiological investigations or imaging reports). 

Management

Many trusts now use the Red and Amber criteria from the Sepsis Trust in patients with suspected infection to help identify those with sepsis and escalate their care appropriately.

Patients fulfilling the AMBER Flag sepsis criteria will require routine bloods and a senior review within 1 hour of presentation.

Patients fulfilling the RED Flag sepsis criteria should be commenced on the Sepsis-6 pathway. This management pathway is a bundle of interventions aimed to offer basic support within the first hour of presentation. The Sepsis-6 bundle includes:

  1. Administration of oxygen
  2. Taking blood cultures [and other important investigations to investigate source of sepsis e.g. CSF, urine, radiological investigations]
  3. Giving IV antibiotics
  4. Administration of IV fluids based on lactate and blood pressure status
  5. Measuring lactate
  6. Monitoring of urine output.

The sepsis trust has developed specific tools for identifying sepsis in pregnant women and those up to 6 weeks post partum (https://sepsistrust.org/wp-content/uploads/2020/01/Sepsis-Acute-Pregnant-Version-1.4.pdf).

The ABCDE Approach may also be an appropriate system to a manage patients with suspected sepsis. This is more comprehensively covered elsewhere but in patients with suspected sepsis would include:

  • Airway stabilisation if necessary
  • Administration of oxygen and monitoring of oxygen saturations with continuous pulse oximetry. Intubation and ventilation may be necessary if oxygen saturations are inadequate despite maximal oxygen therapy
  • Establishing early venous access and using this to obtain baseline investigations, and administering IV fluids and antibiotics.

Top tips:

  • Fluid therapy should be administered in well-defined (e.g., 250-500 mL), rapidly infused boluses. The patients haemodynamic response to fluid resuscitation should be continuously monitored by measuring their blood pressure, pulse and urine output. Remember oliguria is defined as a urine output of <0.5 mL/kg/hour.
  • Use your trust antimicrobial policy to dictate what antibiotics you administer, remember targeted antibiotics are preferred so an appropriate search for a source of sepsis is required. Remember the choice of antimicrobial therapy will also be determined by host characteristics such as comorbidities, immunosuppression, recent hospitalisation, presence of indwelling devices etc.
  • Don’t forget to monitor your patient to assess whether they are responding to your initial management: this will require regular assessment of their NEWs 2 score, urine output, their mentation, lactate and acid balance.
  • Escalate care promptly to the senior member of your team and/or the critical care team in your hospital.

Useful resources:

Sepsis definitions: Article explaining the different clinical definitions used in sepsis.

Sepsis Management Guidelines: Detailed review of the most up to date sepsis management guidelines.

The Sepsis Trust: UK based charity doing research, instigating change and raising awareness of sepsis.

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