Shock Flashcards
Define aerobic respiration
The process of producing cellular energy involving oxygen
Define anaerobic respiration
The process of producing cell energy when there is not enough oxygen for aerobic respiration. Glucose -> lactic acid (+energy released)
Define metabolic acidosis
A pH imbalance where too much acid is accumulated in the body or too much alkali (bicarbonate) has been lost from the body
Define respiratory acidosis
Results of hypoventilation and accumulation of CO2
Define stroke volume
The volume of blood pumped out of the left ventricle with every heart beat
Define blood pressure
The pressure of blood on the walls of the arteries
Define systolic blood pressure
The force exerted on the walls of the arteries as blood is pumped from the ventricles
Define diastolic blood pressure
The force of blood on the walls of the arteries when the ventricles are relaxed (filling)
Define shock
Situation where oxygen delivery to cells/tissues is insufficient for demand
What does SIRS stand for?
Systemic inflammatory response syndrome
Define bacteraemia
Presence of viable bacteria in the blood
Define sepsis
Clinical manifestations of SIRS secondary to an infectious cause
When is sepsis considered severe?
Evidence of dysfunction of at least one organ
Definer septic shock
Severe sepsis association with hypotension that is unresponsive to appropriate fluid resuscitation
What does MODS stand for?
Multiple organ dysfunction syndrome
Define MODS
Dysfunction of the endothelial, cardiopulmonary, renal, nervous, endrocrine and gastrointestinal systems associated with the progression of system inflammation
What does DIC stand for?
Disseminated intravascular coagulation
What is a crystalloid?
Solutions of electrolyte and/or glucose in water
Define a colloid
Macromolecules in solution. Because of their size, they are retained intravascularly and exert colloid osmotic pressure
What does anaerobic metabolism produce?
Lactic acid accumulation -> metabolism acidosis
What substances are produced by ongoing anaerobic respiration that are harmful to cells?
Cytokines
lactate
Nitric oxide
What are the four categories of shock?
Hypovolaemic
Distributive
Obstructive
Cardiogenic
Define hypovolaemic shock
Due to loss of intravascular volume which leads to decreased venous cardiac return/cardiac preload i.e. blood loss
Define distributive shock
Maldistribution of blood and is generally associated with sepsis, SIRS or anaphylaxis. Widespread vasodilation, ‘leaky’ vessels and activation of the coagulation cascade
Define obstructive shock
Associated with physical impediment to blood flow i.e. GDV
Define cardiogenic shock
Caused by severe cardiac dysfunction which results in markedly decreased cardiac output despite normal blood volume i..e ventricular tachycardia
What are the most common causes of shock?
Hypovolaemic and septic
What are some common causes of hypovolaemic shock
Haemorrhage (trauma, surgical, coagulopathy)
Gastrointestinal losses (vomiting secondary to gastrointestinal foreign body)
What are common causes of septic shock?
Septic peritonitis
Pyometra
Pyothorax
What are causes of obstructive shock?
Pericardial effusion
GDV
Pulmonary thromboembolism
Give an example of a patient with obstructive shock where hypovolaemia may also be present
GDV
What are common causes of cardiogenic shock?
End-stage DCM
Severe arrhythmias
What is blood pressure affected by?
Cardiac output
Total peripheral resistance (vasodilation/construction)
Blood viscosity
What are compensatory mechanisms mediated by?
HPA axis - also known as the sympatho-adrenal response
What is the aim of compensatory mechanisms?
Increase cardiac output and blood vessel tone to increase cell perfusion
Define acute compensatory mechanisms
Focused on increased venous return to the heart and increasing blood supply to the myocardium
What triggers the acute compensatory response?
Sympathetic nervous system
What stimulates the sympathetic nervous system during decreased blood volume?
Decreased baroreceptor impulses
What is the acute compensatory response during decreased blood volume?
Increased sympathetic activity and catecholamine release leads to peripheral vasoconstriction, tachycardia and increase in cardiac contractility