Septic Shock
Shock is inadequate cellular oxygen utilization and is distinguished from hypotension. Signs and symptoms include decreased mental status, cold and clammy skin, and decreased urine output.
Vocab
Sepsis: Maladaptive or dysregulated response to an infection and the presence of organ damage
Septic shock: Type of sepsis in which there is decreased cellular utilization of oxygen from circulatory, cellular, and metabolic abnormalities. E.g., sepsis with hypotension.
Systemic Inflammatory Response Syndrome (SIRS)
Diagnosis includes two or more of the following
- High or low temperature: Greater than 38 or less than 36 C
- High heart rate: Greater than 90 bpm
- Tachypnea: RR greater than 20 or hyperventilation PaCO2 less than 32 mmHg
- High or low blood WBC: Greater than 12k or less than 4k
Epidemiology
Mortality rates
- SIRS: 7%
- Sepsis: 25-30%
- Septic shock: 40-70%
Types of Shock
Hypovolemic shock
Decreased blood flow to the heart and subsequent oxygen delivery to tissues due to volume loss.
Compensation includes increasing total peripheral resistance.
Cardiogenic shock
Failure of the heart leading to decreased cardiac output.
Compensation includes increasing total peripheral resistance.
Obstructive shock
Blockage of outflow from the heart leading to decreased cardiac output. Caused by pericardial tamponade, pulmonary embolism, or tension pneumothorax.
Compensation includes increasing total peripheral resistance.
Distributive shock
Severely decreased vascular resistance.
Compensation includes increasing heart rate/contractility to improve cardiac output.
Inflammatory Response
Prolonged inflammation can lead to tissue damage and necrotic cell death. Dying cells release DAMPs (damage-associated molecular patterns) that perpetuate pro-inflammatory activities, creating a positive feedback loop.
This requires immunosuppression, which has the downside of making the patient more susceptible to the existing infection.
Edema in sepsis
Activated neutrophils cause vasodilation and increase vascular permeability, leading to the flow of protein-rich fluid into the tissues.
Therapeutic Approaches
Infection control is essential with broad spectrum IV antibiotics to start, followed by narrow spectrum antibiotics post-identification.
Cardiovascular resuscitation protocol
Includes guidelines for administration of fluids, vasopressors, blood transfusions, and inotropic agents. This protocol decreased in-hospital mortality from 46.5% to 30.5%.
Surviving sepsis framework
A side effect of pressors is vasoconstriction of arterioles in the extremities, leading to tissue hypoperfusion and necrosis. Use of vasopressors is emphasized, especially norepinephrine which is a first line therapy.