Chapter 7: Ventilation, Perfusion and Shock Flashcards
pathophysiology
the study of how disease processes affect the function of the body
metabolism
the cellular function of converting nutrients into energy.
electrolyte
a substance that, when dissolved in water, separates into charged particles
aerobic metabolism
the cellular process in which oxygen is used to metabolize glucose. Energy is produced in an efficient manner with minimal waste products.
anaerobic metabolism
the cellular process in which glucose is metabolized into energy without oxygen. Energy is produced in an inefficient manner with many waste products (carbon doixide).
FiO2
fraction of inspired oxygen; the concentration of oxygen in the air we breathe.
tidal volume
the volume of air moved in one cycle of breathing.
minute volume
the amount of air breathed in during each respiration multiplied by the number of breaths per minute
dead area space
air that occupies the space between the mouth and alveoli but that does not actually reach the area of gas exchange (~150 mL)
chemoreceptor
chemical sensors in the brain and blood vessels that identify changing levels of oxygen and carbon dioxide.
plasma oncotic pressure
the pull exerted by large proteins in the plasma portion of blood that tends to pull water from the body into the bloodstream
hydrostatic pressure
the pressure within a blood vessel that tends to push water out of the vessel.
stretch receptors
sensors in blood vessels that identify internal pressure
systemic vascular resistance (SVR)
the pressure in the peripheral blood vessels that the heart must overcome to pump blood into the system.
stroke volume
the amount of blood ejected from the heart in one contraction
cardiac output
the amount of blood ejected from the heart in one minute (heart rate × stroke volume).
V/Q match
ventilation/perfusion match. This implies that the alveoli are supplied with enough air and that the air in the alveoli is matched with sufficient blood in the pulmonary capillaries to permit optimum exchange of oxygen and carbon dioxide
perfusion
the supply of oxygen to and removal of wastes from the cells and tissues of the body as a result of the flow of blood through the capillaries
hypoperfusion/shock
inability of the body to adequately circulate blood to the body’s cells to supply them with oxygen and nutrients. A life-threatening condition.
diaphoresis
cool, pale, and moist/sweaty skin; sweating.
dehydration
an abnormally low amount of water in the body
edema
swelling associated with the movement of water into the interstitial space
hypersensitivity
an exaggerated response by the immune system to a particular substance.
Endoplasmic reticulum
plays key role in synthesizing proteins
mitochondria
where energy for the cell is largely produced; Conversion of glucose & other nutrients into energy in the form of ATP
adenosine triphosphate (ATP)
responsible for powering all the other cellular functions
who much more energy does aerobic metabolism produce compared to anaerobic?
16x
What is the ultimate goal of emergency care?
move air into the lungs and ensure adequate circulation so that all cells are perfused with oxygen
cardiopulmonary system
the respiratory and cardiovascular system combined
Typical oxygen chemical breakdown
79% N and 21% oxygen
patent airway
open pathway
Pathway of Air
Air follows a path from the openings of the mouth and nose into the pharynx and/or nasopharynx, travels to the rear of the throat (or hypopharynx), then enters the larynx, below which the trachea begins. Air travels down the trachea to the point where it branches into two large tubes called the mainstem bronchi, one leading to each lung. Air follows the paths of the bronchi as they subdivide repeatedly (like branches of a tree) until they reach their endpoints at the multitude of tiny air pockets in the lungs called alveoli . The alveoli are where the exchange of oxygen and carbon dioxide with the blood takes place
Tidal volume
the volume of air moved in and out in-and-out cycle fo breathing
Minute volume
the amount of air that gets into and out of the lungs in one minute (tidal volume x respiration per minute)
When does respiratory dysfunction occur?
any time a minute volume is interfered with
What controls the respiratory system? what can interfere?
medulla oblongata; Stroke, infection, brain trauma, intracranial pressure, spinal cord injuries or other neurological disorders can interfere; toxins & drugs (narcotics)
pleural space
slight space between lung tissue and chest wall (slight negative pressure)
What can interfere with the pressure required for respiratory function?
if bleeding develops within the chest, blood can accumulate in the pleural space and force the lung to collapse away from the chest wall. This can also occur if a hole in either the lung or the chest wall (or both) allows air to accumulate between the lung and the chest wall
What can interfere with lung tissue?
- mechanical force (displace or destroy lung tissue)
- congestive heart failure and severe sepsis change the ability of the alveoli to transfer gases across their membranes
Respiratory Compensation
increased respiratory rate and respiratory effort
In patients with liver failure what can cause an issue with blood?
albumin, one of the large proteins in plasma, is created in the liver. Liver-failure patients often do not produce enough albumin. Without the pulling-in force of albumin, water freely leaves the bloodstream and accumulates around the body cells and even in cavities, leading to dehydration of the blood and edema (swelling) in the patient as fluid accumulates out-side the bloodstream.
What are the most common blood dysfunctions?
(usually has to do with volume) bleeding; dehydration
What carries blood from the heart to the lungs?
pulmonary arteries carry deoxygenated blood
What carries blood from the lungs to the heart?
pulmonary veins carry oxygenated blood
What can lead to a loss of tone of blood vessels?
- injuries to the brain and spinal cord
- sepsis
- allergic reactions lead to dilation
What can lead to excessive permeability of blood vessels?
Sepsis, high altitude, and certain diseases can frequently cause increases in capillary permeability which leads to a loss in volume
What can occur is there is excessive permeability of blood vessels in the lungs?
In the lungs, increased permeability allows the plasma in the blood to cross the membrane and occupy space in the tissues in and around the alveoli. If fluid occupies this space, airflow can be restricted, causing significant gas exchange problems.
What is the average stroke volume of a healthy adult?
70 mL per contraction
The equation for Cardiac output
the amount of blood ejected from the heart in one minute (heart rate × stroke volume)
What does the Stroke factor/volume depend on?
reload is how much blood is returned to the heart prior to the contraction
§ Contractility is the force of contraction, that is, how hard the heart squeezes.
Afterload is a function of systemic vascular resistance. It is how much pressure the heart has to pump against to force blood out into the system. The greater the pressure in the system, the lower the stroke volume
A heart rate over ____ in adults can limit the filling of the heart and decrease stroke factors.
180 bpm
What mechanical problems can lead to heart dysfunction?
physical trauma (such as bullet holes and stab wounds), squeezing forces (such as when the heart is compressed by bleeding inside its protective pericardial sac), or loss of cardiac muscle function from cell death (as in a heart attack).
What electrical problems can lead to heart dysfunction?
diseases such as heart attacks or heart failure that damage the electrical system of the heart. These cardiac electrical problems include unorganized rhythms, such as ventricular fibrillation, and rate problems, such as bradycardias (too slow) and tachycardias (too fast)
hypovolemic shock
low blood volume, occurs when blood is lost from the cardiovascular system (as in severe bleeding) or when the volume portion of the blood is lost (as in dehydration)
distributive shock
The smooth muscle in the vessels loses its ability to maintain a normal diameter. Conditions such as anaphylaxis or sepsis cause normally constricted vessels to dilate and as a result, the pressure within the system is reduced.
cardiogenic shock
the heart fails in its ability to pump blood. Conditions such as myocardial infarction or trauma can lead to either an electrical problem, such as dysrhythmia or a mechanical problem, such as damage to the heart muscle itself
Obstructive shock
Occasionally blood is physically prevented from flowing. In conditions such as tension pneumothorax or pulmonary embolism, large quantities of blood are prevented from reaching essential organs and vital areas
What happens in the kidneys and bone marrow during compensated shock?
kidney: signal to stop eliminating fluid
bone marrow: produce more hemoglobin
Signs of compensated shock
□ Slight mental status changes including anxiety and feeling of impending doom
□ Increased heart rate
□ Increased respiratory rate
□ Delayed capillary refill time
□ Pale skin that is cool and moist to touch (diaphoresis)
□ Sweating
decompensated/ hypotensive shock
compensatory mechanisms have not been successful or have subsequently failed in their effort to sustain perfusion
decreased blood pressure and altered mental status
can lead to irreversible shock
irreversible shock
inadequately perfused organ systems begin to die. Patient death commonly follows.
How will shock vary in children compared to adults?
rely on heart rate more
How is water divided in the body?
§ Intracellular (70%) inside the cell
§ Intravascular (5%) in the bloodstream
§ Interstitial (25%) water can be found between cells and blood vessels
What can lead to dehydration?
-severe vomiting or diarrhea
-rapid breathing
-sweating profusely
The plasma portion of blood can be lost with injuries such as burns
Meningitis
an infection of the protective layers of the brain and spinal cord
encephalitis
an infection of the brain itself
Signs of Dysfunction in the nervous system
□ Altered mental status
□ Seizures
□ Inability to speak or difficulty speaking
□ Visual or hearing disturbances
□ Inability to walk or difficulty walking
□ Paralysis (sometimes limited to one side)
□ Weakness (sometimes limited to one side)
□ Loss of sensation (sometimes limited to one side or area of the body )
□ Pupil changes
Grave’s disease
- thyroid overproduces its hormones
- Inability to regulate temperature and fast heart rate
Gastrointestinal bleeding
§ can occur anywhere in the digestive tract from the esophagus to the anus
can be slow and chronic or can present with hypovolemic shock from acute massive bleeding in the form of rectal bleeding or vomiting blood
Immune response
responds to specific body invaders by identifying them, marking them, and destroying them white blood cells and antibodies are transported in the bloodstream to attack the invaders
What happens during an allergic reaction?
One of the chemicals released, called histamine, produces edema and, in some cases, a narrowing of the airways because of changes in blood vessel permeability. Other chemicals can cause dilation of the smooth muscles of blood vessels, resulting in a rapid drop in blood pressure and distributive shock. Hypersensitivity reactions range from minor and localized reactions to severe and life-threatening ones.
