Sepsis & SIRS

Question 1

What is the systemic inflammatory response syndrome?

Answer 1

SIRS is the body’s reaction to a critical illness such as overwhelming infection or trauma (including surgery).

The clinical criteria is
• Temperature > 38°C or < 36°C
• Heart rate > 90 beats/min
• Respiratory rate > 20/min or PaCO2 < 4.3 kPa (32mmHg)
• WCC > 12 000 or 4000/mL (or 10 per cent immature forms)

Question 2

What is sepsis?

Answer 2

The body’s response to proven infection which includes two of
the clinical criteria for SIRS

Question 3

What is severe sepsis?

Answer 3

Sepsis with evidence of organ dysfunction.

Question 4

What is septic shock?

Answer 4

Sepsis + hypotension with systolic <90mmHg or drop in BP of >40mmHg which is refractory to fluid replacement

Question 5

Why is fluid resuscitation alone usually ineffective in cases of severe sepsis?

Answer 5

Remember that the effects of sepsis are threefold:
• Vasodilatation
• Capillary leak after endothelial damage
• Myocardial depression (caused by an unknown toxin or cytokine)
These three factors dictate that fluid resuscitation alone will not solve the
problem. Vasoconstrictors and inotropic support are usually required

Question 6

Multiple organ dysfunction syndrome

Answer 6

The presence of an acute, potentially reversible dysfunction
of two or more organ systems such that homoeostasis cannot be maintained
without intervention.

Question 7

What are the 2 categories of MODS?

Answer 7

Primary MODS: directly attributable to the initial insult

Secondary MODS (more common): failure is secondary to the effects of SIRS.

Question 8

Which organ systems can be involved in MODS?

Answer 8

Cardiovascular system: Initially a hyperdynamic state with decreased SVR as a result of massive systemic
vasodilatation and increase in capillary permeability. After this, myocardial depression
may occur.

Respiratory system: ARDS is one of the potential components of MODS

Acute Renal Failure: This can occur as the result of acute tubular necrosis

Gut: Decreased absorption is associated with downregulation of secretory IgA. Bacteria
translocate across the deficient gut wall, perpetuating sepsis

Liver: Deranged liver function and hepatocellular jaundice

Blood: A coagulopathy can eventually lead to DIC

Question 9

What is the mortality associated with MODS?

Answer 9

The mortality associated with MODS is directly related to the number of organs
affected. Failure of one organ (most commonly renal failure or respiratory failure)
has a mortality of about 10 per cent whereas renal failure and one other is around
70 per cent, with three or more organs at 95 per cent

Question 10

What are the principles of treatment for MODS, SIRS and Sepsis?

Answer 10

A-E
Removal of any precipitating cause and treatment of any underlying infection.
Antibiotic treatment is initially broad spectrum and empirical. This will be
changed depending on culture results and microbiological advice.
• Airway and breathing: ventilatory support for ARDS and respiratory failure.
• Circulation: intravenous fluids, invasive monitoring (arterial line, CVP PAFC)
and inotropic support to maintain cardiac index, noradrenaline to increase SVR,
MAP and organ perfusion, thereby maximizing oxygen delivery to the tissues.
• Renal support: maintain urine output and renal perfusion. Dopamine and
frusemide have been used to maintain renal perfusion but there is no evidence
that either of these improves outcome. Renal replacement is the mainstay of
renal support (haemofiltration, haemodialysis, haemodiafiltration).
• Nutritional support: in the presence of gut failure, parenteral feeding may be
necessary to account for the body’s
massive calorific demands in MODS and SIRS.

Question 11

What is the role of of activated protein C in severe sepsis

Answer 11

A large RCT has proven the efficacy of activated protein C to significantly reduce mortality. It is indicated if the patient has a systemic inflammatory response, at least one organ dysfunction and known or suspected infection.

Question 12

What is the definition of shock?

Answer 12

A sudden and generalised lack of perfusion and usually oxygenation of all of the
peripheral tissues and end organs, usually caused by cardiovascular collapse.

Question 13

What are the clinical features of shock?

Answer 13

• Hypotension (systolic < 90 mmHg or drop of > 40mmHg)
• Decreased capillary refill
• Tachycardia
• Oliguria
• Confusion and decreased level of consciousness
• Pyrexia and warm peripheries in septic shock

Question 14

What are the types of shock?

Answer 14

• Cardiogenic
• Hypovolaemic
• Anaphylactic
• Septic
• Spinal (evidence of spinal injury and no other reason for hypotension)

Question 15

What is cardiogenic shock?

Answer 15

Pump failure causing circulatory collapse

Question 16

What are the causes of cariogenic shock?

Answer 16

• Acute myocardial infarction (MI)
• Arrhythmias, e.g. ventricular fibrillation (VT), fast AF
• Tension pneumothorax
• Massive pulmonary embolus (PE)
• Cardiac tamponade.

Treatment
In broad terms, MIs should be thrombolysed or stented,
arrhythmias should be cardioverted, tension pneumothoraces should be decompressed,
massive PEs may be thrombolysed or undergo embolectomy, and cardiac tamponade
may be resolved by pericardiocentesis or may require cardiothoracic surgery
(e.g. pericardial window/repair of myocardial rupture).

Question 17

What are the causes of hypovolaemic shock?

Answer 17

Haemorrhage
• Ruptured AAA
• Ruptured ectopic 
• Trauma: pelvic/long bone trauma, splenic rupture, liver laceration. 
• Upper/lower GI bleeding

Loss of fluid 
• Pancreatitis 
• Intestinal obstruction
• High output stoma 
• Iatrogenic (haemofiltration)

Treatment
In this case treatment is largely aimed at stopping the plasma loss and replacing
appropriately with blood, crystalloids, colloids and clotting products if necessary.

Question 18

What are common causes of anaphylactic shock?

Answer 18

Common allergies
• Drugs especially antibiotics (e.g. penicillin and radiological contrast agents)
• Foods (e.g. peanuts/shellfish)
• Medical equipment materials especially latex
• Insect bites/stings.
Treatment
Supportive treatment and cardiac support with adrenaline (epinephrine). Patients
who have an anaphylactic reaction to everyday substances such as foods should be
offered an EpiPen to carry around with them.

Question 19

What is septic shock?

Answer 19

Hypotension complicating severe sepsis despite adequate fluid resuscitation.

Treatment
This is with fluids until adequately filled, then vasoconstrictors such as noradrenaline
(norepinephrine) should be used.
This will need to be given through central venous access in an HDU/ITU setting