- Infection: This is the inflammatory response initiated by the presence of a micro-organisms in normally sterile tissue.
- Bacteraemia: The presence of live bacteria in the blood stream. This can occur in a healthy individual and present with no symptoms. Common causes include surgery, dental procedures and even tooth brushing.
- Septicaemia: Often misused to describe sepsis, septicaemia is the presence of a pathogen in the blood stream leading to sepsis.
- Systemic Inflammatory Response Syndrome (SIRS): This syndrome consists of a set of clinical signs in response to systemic inflammation. These symptoms will be discussed shortly. SIRS can be triggered by many causes including infection, surgery, trauma, malignancy and chronic inflammatory diseases.
- Sepsis: This is defined as SIRS triggered by a primary localised infection. Bacterial, fungal, viral and parasitic infections can all cause sepsis.
- Sepsis can progress to severe sepsis and septic shock, which will be discussed later.
Signs and Symptoms
Two or more of the following:
Two or more of the above signs resulting from infection.
Sepsis along with signs of organ hypo-perfusion.
Signs include hypoxemia, oliguria, lactic acidosis or acute alteration in mental state.
Severe sepsis with hypotension (systolic BP <90 mmHg or a decrease of >40mmHg from baseline) – OR – the requirement for vasoactive drugs – despite adequate fluid resuscitation.
1. Potential sites of infection causing sepsis in a healthy adult (+ example of organism).
- Skin – staphylococcus aureus
- Respiratory tract – streptococcus pneuomoniae
- Gall bladder / Bowel – Escherichia coli, enterococcus faecalis,
- Pelvic viscera – Neisseria gonorrhoeae
2. Potential sources of infection in hospitalised patients
- Burns – gram +ve cocci
- IV catheter (cannula, arterial line etc) – S. aureus, S. epidermidis, Pseudomonas spp, Candida albicans
- Wound infection (trauma, post-surgical) – S. aureus, E. coli
- Peritoneal catheter (ascites drain, peritoneal dialysis) – S. epidermidis
- Urinary catheter – E. coli, Proteus spp, Klebsiella spp
- Immuno-compromised – most pathogens.
- Interleukins (1b, 4, 6, 8, 10)
- TNF alpha
- TGF beta
Cytokines stimulate nitric oxide synthesis, which causes vasodilatation, and a drop in SVR. Tachycardia is initiated as a response to a drop in SVR.
Tachypnoea, hypoxemia, respiratory alkalosis. ARDS*
In ARDS, dysfunction (leakiness) of pulmonary capillaries causes alveolar oedema and neutrophil activation.
Cytokine-mediated vasodilation and hypotension cause decreased renal perfusion
Disseminated intravascular coagulation (DIC)
Cytokine mediated activation of extrinsic coagulation cascade.
In addition, lactic acidosis is caused by tissue hypoxia. The hypoxia results from tissue hypoperfusion as a result of hypotension and arteriovenous shunting.
- Give high flow oxygen
- Take blood cultures
- Give empirical IV antibiotics
- IV fluid resuscitation
- Check Hb and lactate (ABG or VBG)
- Monitor urine output accurately
(An easy way to remember this is – give 3 and take 3; i.e. take cultures, ABG and urine and give O2, fluids and antibiotics).
- My local trust guidelines recommend prescribing benzylpenicillin 1.2g IV QDS + Gentamicin 5mg/kg IV OD (maximum 400mg gentamicin per day).
- In patients with penicillin allergy vancomycin 1g can be given i nstead of the penicillin
- Always check your local guidelines
Ventilation and Oxygenation
Cardiac output and BP
· Maintain patent airway. Patient may require:
· High flow oxygen
Aims of supportive treatment:
- Clinical Medicine 7th Ed. (2009) by Kumar and Clark.
- Paterson, RL., Webster, NR. (2000). Sepsis and the systemic inflammatory response syndrome. J.R.Coll.Surg.Edinb., 45, 178-182
- Oxford Handbook of Clinical Medicine 7th Ed. (2008). Longmore et al.