trauma Flashcards
shock
hypoperfusion
Hypoxia at the cellular level
perfusion
Adequate delivery of blood through the capillary bed in tissues
inotropy
strength of the heart’s contractions
chronotropy
rate of the heart’s contractions
preload
Amount of venous return available to the ventricle
afterload
the total resistance against which blood must be pumped.
mean arterial pressure (MAP)
a function of total cardiac output (CO) and systemic vascular resistance (SVR)
MAP forumla
MAP = [(DBP × 2) + SBP]/3
ejection fraction
a measurement of the percentage of blood volume pumped out of the left ventricle with each contraction. Normally, 50% to 70% of the blood is ejected out of the left ventricle. A borderline ejection fraction is 41% to 49%. At this level, a patient may have shortness of breath on exertion. When the ejection fraction is less than 40%, tissue perfusion may be compromised. Echocardiograms are used to estimate ejection fraction.
tunicae
All vessels larger than capillaries have layers of tissue surrounding the endothelium. These layers provide supporting connective tissue to counter the pressure of blood contained in the vascular system. They also have elastic properties that enable the blood vessels to dampen pressure pulsations and minimize flow variations throughout the cardiac cycle. Finally, the tunicae have muscle fibers that can contract and relax to control the vessel diameter. The vascular system maintains blood flow by changes in pressure and peripheral vascular resistance.
muscular arterioles
small blood vessels that regulate blood flow to capillaries by constricting or dilating their smooth muscle walls
anaerobic metabolism
refers to the energy production processes within cells that occur in the absence of oxygen. It’s a vital process, especially for short bursts of intense activity, as it provides a quick source of energy when the body can’t rely on oxygen-dependent metabolism. A key process in anaerobic metabolism is anaerobic glycolysis
anaerobic glycolysis
glucose is broken down to produce ATP, but also generates lactate, a byproduct that can lead to muscle fatigue.
capillary response in shock
anaerobic metabolism produces excess lactic acid and leads to metabolic acidosis. The arteriolar and precapillary sphincter control fails. Capillary engorgement and clumping of red blood cells follow, affecting nutritional flow and the removal of metabolic waste products.
hypovolemic shock
inadequate circulating blood volume. The most common causes are hemorrhage and dehydration. Illnesses and injuries that can lead to hypovolemic shock include trauma, gastrointestinal bleeding, burns, diarrhea, vomiting, endocrine disorders, and internal third-space loss, as in peritonitis.
cardiogenic shock
Cardiogenic shock is the result of a severe compromise in cardiac output due to dysfunction of the heart itself such that inadequate tissue perfusion occurs despite an adequate amount of circulating blood volume.
obstructive shock
Obstructive shock is a form of shock associated with the inability to produce adequate cardiac output despite normal intravascular volume and myocardial function. Causes of obstructive shock include:
Pericardial tamponade
Tension pneumothorax
Pulmonary embolism
distributive shock
Distributive shock occurs when peripheral vasodilation causes a decrease in SVR. Patients tend to have warm extremities, particularly early in the course of disease when the body is able to compensate by significantly increasing the cardiac output.
The most common causes of distributive shock are neurogenic shock, anaphylactic shock, and septic shock
signs of compensated shock
mild tachycardia
lethargy, confusion, combativeness
delayed cap refill, cool skin
normal or elevated bp
signs of decompensated shock
moderate tachycardia
confusion, unconsciousness
delayed cap refill, cyanosis, cold
decreased BP
signs of irreversible shock
bradycardia, severe dysrhythmias
coma
pale, cold, clammy skin
frank hypotension
compensated shock
homeostasis is maintained and catecholamine production is increased.
decompensated shock
the body is no longer able to maintain and adequate blood pressure.
irreversible shock
cells and organelles begin to die due to lack of oxygen and are no longer able to produce energy. necrosis is inevitable even if perfusion is returned.
