Sepsis Pathophysiology and Consequences

• Sepsis is a life-threatening condition
• Sepsis is caused by the body's extreme systematic response to an existing infection

Step-by-step Pathophysiology of Sepsis:

• An infection triggers an immune response
• In sepsis, this immune response becomes an immunologic overactivity
• Excess leukocytes (white blood cells) are produced
• The excessive immune response becomes systemic instead of localized
• Capillaries become dilated and permeable, causing fluid to leak out of the vessels
• This impacts preload and stroke volume

Consequences of Sepsis:

• Compromised blood flow to organs and tissues
• Decreased intravascular volume, leading to poor tissue perfusion
• Activation of the extrinsic pathway of the clotting cascade
• Disseminated Intravascular Coagulopathy (DIC) occurs
• Micro clots form, causing blockages
• Oxygen availability to tissues decreases due to both volume loss and blockages
• Anaerobic metabolism occurs because of oxygen loss
• Lactic acid builds up, leading to metabolic acidosis
• Cell death and tissue death occur
• Multiple organ failure can result

Physiological Responses to Sepsis:

• Adrenaline is released in response to vascular dilation and inadequate vascular volume, causing tachycardia

Effects of Sympathetic Stimulation on Different Organs:

• Heart: Increased heart rate and force of contraction (Beta 1 and Beta 2 receptors)
• Arteries: Constriction (alpha 1 receptor), Dilation (beta 2 receptor)
• Veins: Constriction (alpha 1 receptor), Dilation (beta 2 receptor)
• Lungs: Bronchial muscle dilation (Beta 2 receptor)

Blood Gas Values in Sepsis:

• pH: 7.23 (acidic, normal range: 7.35-7.45)
• PaO2: 9.85 kPa (slightly low, normal range: 11-13 kPa)
• PaCO2: 3.2 kPa (low, normal range: 4.7-6.0 kPa, may indicate hyperventilation)
• BE: -16.7 (indicates the amount of alkaline needed to restore balance)
• HCO3: 12.6 mmol/l (low, normal range: 22-26 mmol/l, indicates a metabolic problem)
• Lactate: 6.2 mmol/l (high, normal range: <2 mmol/l)

Red Flag Criteria for Sepsis:

• 40 mm Hg less than baseline systolic BP
• Respiratory rate over 25/min
• Heart rate over 130
• Altered consciousness/new confusion (AVPU)
• Limited urine output
• SpO2 under 91%

Sepsis Management ("Sepsis 6"):

• Administer oxygen due to volume loss and DIC
• Take cultures to determine appropriate antibiotics
• Administer IV antibiotics (broad spectrum initially)
• Administer IV fluids to replace fluid loss
• Check lactate levels to confirm sepsis
• Monitor urine output to assess renal function

Goals of Sepsis Management:

• Correct the disbalance and provide vascular support
• Aim for a minimum urine output of 0.5 ml/kg/hour to ensure kidney perfusion and lactate excretion

Shock:

• Inadequate tissue and organ perfusion

Three Main Components for Effective Blood Flow:

• Effective pump (heart)
• Effective circulatory system (blood vessels)
• Adequate blood volume (fluid)

Blood Pressure Formula:

• Stroke Volume x Heart Rate = Cardiac Output
• Cardiac Output x Systemic Vascular Resistance = Blood Pressure

Factors in Sepsis:

• Volume and systemic vascular resistance

Types of Shock:

• Hypovolemic: Hemorrhage or other fluid loss (related to volume)
• Cardiogenic: Myocardial infarction/arrhythmia (related to heart and heart muscle)
• Distributive: Neurogenic/septic/anaphylactic (related to blood vessels)
• Obstructive: Tension pneumothorax/tamponade (something stopping breathing and heart)
• Dissociative: Severe anemia/O2 carrying capacity depletion (blood mixture)

Sepsis is a life-threatening condition caused by the body's extreme response to an infection, leading to an overactive immune response. This systemic response causes capillaries to become dilated and permeable, compromising blood flow and activating the clotting cascade. Ultimately, this results in decreased tissue perfusion, micro clot formation, and lactic acid buildup.