shock Flashcards
(36 cards)
What is the requirement for adequate tissue perfusion?
Oxygen delivery must exceed oxygen consumption levels to maintain normal metabolic activities.
This is essential for sustaining cellular metabolism and preventing tissue injury.
Define shock.
Shock is circulatory insufficiency that creates an imbalance between tissue oxygen supply and oxygen demand.
It is characterized by inadequate organ and peripheral tissue perfusion.
What are the stages of shock?
- Initial
- Compensatory
- Progressive
- Refractory
Each stage represents a different level of tissue perfusion deficiency and metabolic response.
List the different types of shock.
- Hypovolemic shock
- Cardiogenic shock
- Restrictive (vasodilatory/distributive) shock
These types are categorized based on their etiology.
What is systemic inflammatory response syndrome (SIRS)?
SIRS is a widespread inflammatory response that can occur in the context of shock.
It often involves multiple organ systems and can exacerbate the state of shock.
What is the relationship between perfusion and hydration?
Perfusion refers to the delivery of blood to tissues, while hydration refers to fluid balance in the body.
Fluid deficits can cause clinical signs of dehydration.
What physical findings indicate 4-5% dehydration?
Semidry oral mucous membranes, normal skin turgor, and eyes maintaining normal moisture.
These signs help to estimate the percentage of dehydration.
What heart rate and blood pressure changes indicate poor perfusion?
Changes in heart rate, pulse intensity, capillary refill time, mucous membrane color, and blood pressure.
These parameters are clinically used to detect intravascular volume deficits.
What happens when oxygen supply is insufficient to meet demand?
The first compensatory mechanism is an increase in cardiac output (COP).
If COP is inadequate, tissues extract more oxygen from hemoglobin.
What is lactic acidosis?
Lactic acidosis occurs when anaerobic metabolism takes place due to insufficient oxygen supply, leading to increased lactate levels.
Normal lactate levels range between 0.5 and 1.5 mM/L.
Is shock always associated with hypotension?
False. Shock is usually associated with hypotension, but it can occur with normal blood pressure.
Hypotension can also occur without shock.
What is the formula for Mean Arterial Pressure (MAP)?
MAP = DP + 1/3(SP – DP) or MAP = DP + 1/3(PP)
MAP ensures adequate perfusion of blood to tissues.
What occurs during the initial stage of shock?
Hypoperfusion causes hypoxia, leading to lactic acid fermentation and lactate accumulation.
This stage is characterized by reversible cellular injury.
What characterizes the compensatory stage of shock?
Physiological mechanisms attempt to reverse the condition through neural, hormonal, and biochemical responses.
The body tries to restore balance in tissue perfusion.
What occurs in the progressive stage of shock?
Compensatory mechanisms begin to fail, leading to significant cellular ATP degradation and further tissue damage.
Restoration of oxygen becomes ineffective at this stage.
What happens during the refractory stage of shock?
Vital organ failure occurs, brain damage and cell death are imminent, and shock can no longer be reversed.
This stage marks the point of no return for the patient.
What are the key components of normal cardiovascular homeostasis?
Pump, circulating fluid, microcirculatory factors, and vessels.
These components work together to maintain blood flow and tissue perfusion.
What is cardiogenic shock?
A type of shock caused by the heart’s inability to pump blood effectively.
This can result from various cardiac conditions.
What is hypovolemic shock?
Shock resulting from significant fluid loss, leading to inadequate blood volume and poor perfusion.
It is also referred to as cold shock.
What is irreversible shock?
A stage of shock where the condition cannot be reversed, often leading to death.
This represents the final state of shock.
What is low resistance shock?
Also known as warm shock, it occurs when there is a significant decrease in vascular resistance.
This can lead to widespread vasodilation and hypotension.
What are the four categories of shock classified by etiology?
- Hypovolemic
- Cardiogenic
- Distributive
- Obstructive
These categories help in identifying the underlying causes of shock.
What is the pathophysiological sequence of changes in hypovolemic shock?
Loss of intravascular volume → ↓ venous return → ↓ preload → ↓ stroke volume → ↓ cardiac output → ↓ MAP → inadequate tissue perfusion → lactic acidosis
MAP stands for Mean Arterial Pressure.
What are the compensatory mechanisms in early hypovolemic shock?
- Activation of sympathetic nervous system → tachycardia, vasoconstriction → maintenance of MAP
- RAAS activation → fluid retention
RAAS stands for Renin-Angiotensin-Aldosterone System.
