0522 - Pathophysiology and Management of Septic Shock

Question 1

Define Infection

Answer 1

An inflammatory response to presence of microorganisms.

Question 2

Define Sepsis

Answer 2

The systemic response to infection (HR, WCC, RR, Temp) (Systemic Inflammatory Response).

Question 3

Define severe sepsis

Answer 3

Sepsis associated with organ dysfunction, hypoperfusion, hypotension.

Question 4

Define septic shock

Answer 4

Sepsis with hypotension unresponsive to fluid therapy, along with evidence of hypoperfusion.

Question 5

What is the impact of septic shock on patient outcome?

Answer 5

30-50% Mortality. Have significantly worse outcomes than others in the hospital, and others in the ICU.

Question 6

What are the most common sources of septic infection?

Answer 6

Pneumonia
Peritonitis/diverticulitis
UTI
Primary blood stream

Question 7

What is the ultimate cause of septic shock?

Answer 7

It’s the host response, rather than the infecting organism, that determines the severity. Systemic cytokine storm causes full-body vasodilation, lowering BP and potentially causing DIC. Even when O2 delivery is adequate, the shocked cell is unable to utilise it effectively.
Not from lecture - she says she is more CO than pressure person - Oedema in peripheral tissue prevents adequate O2 delivery even in the presence of sufficient CO after fluid resuscitation.

Question 8

What is the pathogenesis of severe sepsis?

Answer 8

Overstimulation of the innate immune system by microbial products from phagocytes. This activates TLR’s, causing massive cytokine release throughout the body, massive vasodilation, septic shock.

Question 9

What is the pathogenesis of Gram negative sepsis?

Answer 9

Endotoxin release (LPS) binds to LPS binding protein. This binds to CD14 receptor on macrophages, which presents it to a TLR, activating the macrophage. Releases TNF, IL’s 1, 6, 8. Causing vasodilation, complement, coagulation etc.

Question 10

What factors can influence the degree of septic shock?

Answer 10

Virulence and dose of organism
State of host defence (local and general)
The chain of events from pathogen recognition to overwhelming host response.

Question 11

Why does a septic shock patient have warm hands, low BP and high HR?

Answer 11

Infection causes cytokine release, leading to vasodilation and low TPR.
Warm hands - low TPR with peripheral vasodilation.
Low BP - Peripheral vasodilation means more arterial blood
Vasodilation/causes low VR (pre-load), causes low SV, therefore HR rises to compensate.

Question 12

What is required for adequate arterial O2 content (saturation)?

Answer 12

Adequate and patent airway
Effective lung mechanics (neurological and muscular)
Effective lung tissue
Effective pulmonary circulation
Effective haemoglobin

Question 13

What is required for adequate haemoglobin?

Answer 13

Effective (adult) Hb

Concentration (no anaemia)

Question 14

What is the O2 delivery equation? Explain each contributor

Answer 14

DO2 = (SVxHR) x ([Hb] x SaO2 x 1.39) + PaO2 x 0.003
SV x HR - Cardiac Output - getting the blood around
[Hb] - Amount of Hb in blood
SaO2 - Amount of Hb that is saturated
1.39 - mL of O2 on each gram of Hb
PaO2x0.003 - Amount of O2 dissolved in plasma

Question 15

What are the principles of management of septic shock?

Answer 15

FLUIDS
Correct underlying infection
Support through cytokine storm.