Septic Shock

Shock – Syndrome in which tissue perfusion is inadequate in supplying tissue metabolic requirements:
• Hypovolaemic
• Cardiogenic
• Distributive e.g. septic, anaphylaxis
• Obstructive e.g. tensionpneumothorax, PE

Septic shock:
Definitions
Sepsis: source of infection, temperature >38 ‘C, heart rate >90, resp. rate > 20 or PaC02 < 4,3kPa, WCC . 12000 or > 10% immature forms

Septic shock: Sepsis plus hypotension, despite adequate fluid resuscitation, plus organ perfusion abnormalities e.g. lactic acidosis, oliguria and mental impairment

Definitions continue
SIRS: Systemic inflammatory response syndrome has the same definition as sepsis but can occur as a response to insults other than infection, e.g. pancreatitis or multiple trauma

Pathology
Severity of illness determined more by nature of inflammatory response than by infection itself

Chemical mediators, complex interactive pathways, some are pro and others anti-inflammatory

Gram negative bacteria endotoxins activate mediators e.g. TNF, PG, interleukin, NO, macrophages

Pathological effects
Vasodilatation
Increased capillary permeability
Impaired tissue oxygen utilization
Myocardial depression

Clinical signs

Pyrexia, tachycardia, warm bounding peripheries and hypotension
Other: confusion, drowsiness, cool peripheries, tachypnoea and oliguria

BEWARE: young children
elderly
pre-existing pathology
steroids or beta blockers
moribund advanced sepsis

Investigations
FBC: high WBC neutrophilia, low WBC and low platelets indicate severe sepsis
U&E: dehydration and renal impairment
Coagulation: raised INR indicate septic coagulopathy
Bloodsugar: usually raised
Bloodgas: metabolic acidosis, low C02 and hypoxia
Lactate: high due to tissue hypoxia
CXR: ‘ wet lungs’ or ARDS changes

Monitoring: Oxygenation & Perfusion
Routine non invasive monitors
CVP and arterial line
CO monitoring e.g. PiCCO
Urine output
Mixed venous oxygenation via PA catheter, normal >75%
Regular bloodgasses, U&E, lactate, clotting
Peripheral – core temperature difference, normal < 2 ‘C (more useful in low cardiac output states

Treatment: Restoration & maintaining tissue oxygenation
IV fluid therapy
Inotropes/vasoconstrictors
Oxygen and PEEP
Ventilation

Treatment: continue
Appropriate antibacterial and antifungal drugs, microbiology input
Nutrition
Maintain normo- glycaemia
Activated Protein C
Steroids?
Prevent stress gastric ulcers
Other: PG’s, nalaxone, thyrotropin releasing hormone?

Complications
Multi-organ failure including ARDS, renal failure, hepatic failure, pancreatitis & DM, DIC, cardiac failure and coma
DEATH: Mortality 50%