EMT Quiz Chapter 8

For a patient breathing in room​ air, the EMT would estimate the FiO2 to​ be:

0.21

The EMT is administering oxygen at​ 95% through a nonrebreathing face mask. He would document this as an FiO2 ​ of

0.95.

Which of the following is required for normal perfusion to​ occur?

Adequate​ breathing, sufficient red blood​ cells, good heart function To maintain adequate​ perfusion, the components of the delivery and removal system must work properly. These components​ are: ​? Composition of ambient air ​? Patent airway ​? Mechanics of ventilation ​? Regulation of ventilation ​? Ventilation/perfusion ratio ​? Transport of oxygen and carbon dioxide by the blood ​? Blood volume ​? Pump function of the myocardium ​? Systemic vascular resistance ​? Microcirculation ​? Blood pressure An alteration in any one of these components may lead to poor cellular perfusion with an inadequate delivery of oxygen or glucose to the cell or inadequate elimination of carbon dioxide and other waste products.

Which one of the following best describes minute​ ventilation?

Amount of air moved into and out of the lungs in one minute

When a healthy person has a sudden increase in blood​ pressure, which one of the following will​ occur?

Baroreceptors will signal the brain to decrease the heart rate.

A patient with a severe infection is very sick. Circulating toxins from bacteria in his blood have decreased his systemic vascular resistance​ (SVR). Which of the following would the EMT correlate to this​ condition?

Blood pressure of​ 74/26 mmHg

A patient with severe iron deficiency anemia is hypoxic. What is definitive care for this​ patient?

Blood transfusion A perfusion disturbance may also lead to severe cellular hypoxia. Your patient has no chest or lung injury and has an increased rate and depth of ventilation. His minute ventilation and alveolar ventilation are​ increased; however, his cells are becoming hypoxic. Although he is moving more oxygenated air into the​ alveoli, because of his​ anemia, his blood has a significantly reduced ability to transport oxygen. This represents a perfusion​ disturbance, because the blood cannot pick up the oxygen that is available in the alveoli. This would create a state of wasted​ ventilation, hypoxemia, and cellular hypoxia. A blood transfusion is required to restore cellular perfusion.

Which of the following medical conditions would impair a​ patient's respiratory status by directly damaging the central​ chemoreceptors?

Brainstem stroke

A patient with liver disease suffers from a low platelet count. Which of the following would the EMT directly correlate to this​ condition?

Bruising to arms The formed elements in the blood are red blood​ cells, white blood​ cells, and platelets. The platelets​ (thrombocytes) are not actual cells but fragments that play a major role in blood clotting and the control of bleeding. Bruising of the arms would be an indicator that the​ patient's platelet count is low and would not be related to skin color or oxygen level.

A patient with a temperature of 105.4degrees°F is suffering from systemic vasodilation. Which one of the following findings would be consistent with this​ condition?

Decreased blood pressure

You are caring for a​ 66-year-old male who is severely dehydrated. Given this​ condition, you would recognize which of the following related to the cardiovascular​ system?

Decreased blood volume available for circulation

Which one of the following conditions is most likely to cause​ acidosis?

Depressed respirations

In the​ hospital, a patient was administered an IV fluid with a high oncotic pressure. Once in the​ body, the EMT would expect which one of the following​ actions?

Fluid from the tissue to move into the bloodstream Plasma oncotic​ pressure, also known as colloid oncotic pressure or oncotic​ pressure, is responsible for keeping fluid inside the vessels. A force is generated inside vessels by large plasma​ proteins, especially​ albumin, that attract water and other fluids. Opposite in action to hydrostatic​ pressure, oncotic pressure exerts a pull inside the vessel. A high oncotic pressure will pull fluid from outside the vessel through the vessel wall and into the vessel. A high oncotic pressure will draw excessive amounts of fluid into the vessel or capillary and increase blood fluid volume.

A chronically elevated afterload increases the​ patient's chance for developing which one of the following​ conditions?

Heart failure Afterload is the resistance in the aorta that must be overcome by contraction of the left ventricle to eject the blood. The force that is generated by the left ventricle must overcome the pressure in the aorta to move the blood forward. A high afterload places an increased workload on the left ventricle. A chronically elevated diastolic blood pressure will create a high​ afterload, generating an increased myocardial workload that could lead to left ventricular failure over a period of time.

Which of the following would directly compromise the average​ patient's cardiac​ output?

Heart rate of 170 beats per minute

Which one of the following would result from increasing a​ patient's preload?

Increased cardiac output Preload is the pressure that is generated in the left ventricle at the end of diastole​ (the resting phase of the cardiac​ cycle). Preload pressure is created by the blood volume in the left ventricle at the end of diastole. The available venous​ volume, which determines the volume of blood in the​ ventricle, consequently plays a major role in determining preload. An increase in preload generally increases stroke​ volume, which in turn increases the cardiac output. Within​ reason, there can be an increase in the contraction as a result of the​ "stretch" in muscle fibers and also in blood​ pressure, although any increase in BP would likely be offset via other mechanisms.

A patient who has lost 1 liter of blood is conscious with a patent​ airway, but his extremities are pale and cold to the touch. Vital signs are pulse​ 130, respirations are 22 and​ adequate, blood pressure is​ 74/56, and SpO2 is​ 95% on room air. Which one of the following is most needed by this patient to increase perfusion to the​ cells?

Increased number of red blood cells and plasma volume

A patient with a high fever has an accelerated metabolism and is producing abnormally high amounts of carbon dioxide at the cellular level. To​ compensate, which one of the following will​ occur?

Increased respiratory rate

Which of the following will affect the ventilation component of the​ ventilation/perfusion ratio?

Infection and pus in the distal airways and alveoli

Why is an understanding of basic pathophysiology​ necessary?

It helps you recognize why certain signs and symptoms occur.

What happens after a cell in anaerobic metabolism breaks down glucose and creates energy in the form of adenosine triphosphate​ (ATP)?

Lactic acid is formed.

Which one of the following conditions would most likely account for an elevated carbon dioxide level in a​ patient's body?

Lung disease

What is the protective mechanism underlying a narrowed pulse​ pressure?

Maintain an adequate blood pressure for perfusion.

A patient with cancer is receiving chemotherapy. As a side effect of the​ treatment, her white blood cell count is critically low. Given this​ situation, which sign or symptom should the EMT find particularly​ concerning?

Oral temperature 102.7degrees°F The formed elements in the blood are red blood​ cells, white blood​ cells, and platelets. The white blood cells​ (leukocytes) protect the body against infection and eliminate dead and injured cells and other debris. A sign that an opportunistic infection may have invaded the body would be an increased temperature.

An unresponsive patient is breathing at a rate of 6 breaths per minute. What intervention would be most beneficial for the​ patient?

Positive pressure ventilation with a rate of 12 and tidal volume of 500 mL One way to compensate for a decreased minute ventilation is to increase the ventilatory rate.​ However, even though the minute ventilation may appear to be near​ normal, severe hypoxia may still occur as a result if only a small amount of air is actually getting to the alveoli for gas exchange. Increasing the frequency of ventilation may improve the amount of air that is moved into and out of the respiratory tract in one​ minute; however, if the tidal volume is too​ low, an adequate amount of air may never make it completely down to the alveoli for gas exchange but will instead remain in the trachea and major bronchi. You need to achieve a tidal volume of 500 mL at a rate of 12 respirations per minute to adequately oxygenate your patient.

A​ patient's lungs are full of fluid and cannot transfer oxygen to the blood. As a​ result, she is in anaerobic metabolism. She has a decreased level of consciousness with a patent upper airway and inadequate respirations. Her pulse is rapid and weak. Which one of the following prehospital treatments would best shift her cellular metabolism to​ aerobic?

Positive pressure ventilation with supplemental oxygen

Which one of the following best describes the concept of​ afterload?

Pressure that the left ventricle must pump blood against Afterload is the resistance in the aorta that must be overcome by contraction of the left ventricle to eject the blood. The force that is generated by the left ventricle must overcome the pressure in the aorta to move the blood forward. A high afterload places an increased workload on the left ventricle. A chronically elevated diastolic blood pressure will create a high​ afterload, generating an increased myocardial workload that could lead to left ventricular failure over a period of time. The pump function is typically expressed as the cardiac output.

Which of the following correctly identifies the primary way in which oxygen is transported to the​ cells?

Red blood cell

A patient has been shot three times in the abdomen and has massive internal hemorrhage and blood loss. What will best give this patient a chance at​ survival?

Stopping the bleeding

On​ scene, a​ 43-year-old male states that he has a history of liver failure and does not produce enough of the protein albumin. Given this​ condition, which one of the following would you​ expect?

Swelling of the extremities and abdomen

Which of the following best describes the​ ventilation/perfusion ratio?

The ability of the body to exchange gases across the alveolar capillary membrane The​ ventilation/perfusion (V/Q) ratio describes the dynamic relationship between the amount of ventilation the alveoli receive and the amount of perfusion through the capillaries surrounding the alveoli. This relationship determines the quality of gas exchange across the​ alveolar-capillary membrane, which influences the amount of oxygen entering the blood and the amount of carbon dioxide exiting the blood. The amount of air that is moved into and out of the lungs in one minute is the minute volume.

Which one of the following conditions must be met for carbon dioxide to be moved from the cell to the​ bloodstream?

The blood must be low in carbon dioxide.

For the patient with a narrowed pulse​ pressure, which one of the following is​ occurring?

The blood vessels are constricting.

You and the critical care transport team are taking a critically ill patient to another hospital. Among many IV infusions and​ monitors, the patient is also on a ventilator. You note that the FDO2 is set at 0.50. What does this​ mean?

The provided oxygen concentration is set at 50 percent.

According to the​ V/Q ratio, why might a patient with an inhalation injury from a burn have poor cellular​ oxygenation?

They are having wasted alveolar perfusion.

If a​ patient's blood pressure cannot be increased by adding​ volume, then which of the following actions would most likely be successful in increasing​ it?

Vasoconstriction

For a patient who is​ bleeding, which of the following is the immediate response of the human​ body?

Vasoconstriction caused by the sympathetic nervous system

A loss of contact between the visceral and parietal pleura can lead​ to:

a collapsed lung.

The EMT would best recognize normal cellular metabolism​ as:

aerobic.

A​ patient's brain cells are undergoing anaerobic metabolism. As a​ result, those​ cells:

are becoming dysfunctional in a highly acidic environment.

The EMT would document an FDO2 level when she​ is:

assisting breathing with a​ bag-valve-mask device.

Hydrostatic pressure refers to the force inside​ the:

capillaries

A patient with high blood pressure takes a medication to slow his heart​ rate, thus lowering his blood pressure. The EMT would recognize this action as impacting​ the:

cardiac output.

A patient who is weak informs you that she has a history of her​ "iron being too​ low." This should concern the EMT because iron is needed​ to:

carry oxygen throughout the body.

A drop in blood pressure below a critical threshold is a threat to the body because it directly​ impairs:

cellular perfusion.

Perfusion is best described​ as:

delivery of essential products and nutrients to the cell for its use.

A​ 35-year-old male is lethargic and dehydrated after working at a construction site for 12 hours on a very hot day. You obtain the following vital​ signs: pulse​ 136, respirations​ 22, blood pressure​ 102/88, and SpO2 ​ 100% with supplemental oxygen. As a knowledgeable​ EMT, you would​ recognize:

elevated heart rate to increase cardiac output. An increase in heart​ rate, if not excessive​ (generally under​ 160), will increase cardiac output. Rapid respirations would increase CO2​ loss, the pulse pressure is not​ widened, and low blood pressure is indicative of poor perfusion.

The body will compensate for a decrease in cardiac output​ by:

increasing systemic vascular resistance. The systolic blood pressure begins to decrease from the drop in cardiac output. One way in which the body attempts to compensate for the decrease in blood pressure is by increasing the systemic vascular​ resistance; this is accomplished by constricting blood vessels. Although the blood pressure may still appear to be within normal​ limits, the narrow pulse pressure may warn you of the dropping cardiac output from blood or fluid loss and a rising systemic vascular resistance as an attempt to compensate for the decreasing pressure.

The EMT would most likely see a narrowed pulse pressure in a patient​ who:

is bleeding internally.

Under normal​ circumstances, carbon dioxide is excreted from the body through​ the:

lungs.

Baroreceptors function in the body​ by:

monitoring the blood pressure.

The patient in anaerobic metabolism is deficient​ of:

oxygen

​Boyle's law applies​ to:

the ventilation process.

When the cells undergo normal​ metabolism, which one of the following​ occurs?

​Heat, carbon​ dioxide, and water are produced.

Failure of the sodium potassium pump can result​ in:

cellular​ damage, swelling, and rupture. Sodium and potassium are​ ions, that​ is, electrically charged molecules. Sodium is a positively charged ion that is found primarily in the fluid outside the​ cell, although some sodium is also found inside the cell. It is considered the primary extracellular ion. Potassium is also positively charged and is considered the primary intracellular ion. That​ is, it is found primarily in the fluid on the inside of the cell but also exists outside the cell. For the​ sodium/potassium pump to​ work, as with any other​ pump, energy is required. The energy is in the form of​ ATP, which is released through​ glycolysis, the breakdown of glucose within the cell. If there is a lack of​ ATP/energy production by​ cells, as is found in poor perfusion states and anaerobic​ metabolism, the​ sodium/potassium pump may fail. This would allow sodium to collect on the inside of the cell. As is well​ known, water follows sodium. So as sodium collects inside the​ cell, it attracts water. As the water continues to​ accumulate, the cell swells and eventually ruptures and dies.​ Thus, the end result of a lack of energy to run the pump is cell death.

For cells to undergo the process of aerobic​ metabolism, the cells​ require:

oxygen and glucose.

The best way to decrease a​ patient's afterload would be​ to:

reduce the blood pressure.

A patient who is hypoxic has a pulmonary disease that involves low lung compliance. Poor lung compliance means​ that:

ventilation with a​ bag-valve mask will require more effort. Compliance is a measure of the ability of the chest wall and lungs to​ stretch, distend, and expand. A condition that would cause the lungs or chest wall to become stiff would decrease compliance. A decrease in compliance would make it more difficult for the patient to move air into and out of the lungs. This also would make it more difficult to ventilate the patient artificially. Conditions such as pneumonia and pulmonary edema decrease compliance within the lungs. Structural problems with the chest wall can also lead to poor​ compliance; examples are a flail​ segment, in​ which, two or more ribs are fractured in more than one​ place, and neuromuscular diseases that affect the ability of the chest muscles to contract. Damage to lung tissue and swelling may also result from various pulmonary diseases but are not directly related to compliance.

Which one of the following measurements indicates a narrowed pulse​ pressure?

​108/88 The pulse​ pressure, is only 20 mmHg​ (108 - 88​ = 20​ mmHg). A normal pulse pressure would be greater than 25 percent of the systolic blood pressure. In this​ case, a normal pulse pressure would be 27 mmHg or greater​ (108 ×​ 25% = 27​ mmHg). Thus, this patient has a narrow pulse​ pressure, which may be an indication of a dropping cardiac output from a decrease in venous volume and preload and an increasing systemic vascular resistance to compensate for the decrease in pressure. If you looked just at the​ patient's blood​ pressure, you could easily say that it is normal. If you considered the pulse pressure as well as other signs of​ perfusion, such as skin​ color, temperature,​ condition, and mental​ status, you might reclassify it as abnormal.

A​ 100-kilogram patient with a​ 500-milliliter tidal volume breathing 16 times each minute would have a minute ventilation of how many​ milliliters?

​8,000 Minute​ ventilation, also known as minute​ volume, is the amount of air that is moved into and out of the lungs in one minute. It is determined by multiplying the tidal volume by the frequency of ventilation in one minute. If an​ average-sized adult has a tidal volume of approximately 500 mL and breathes approximately 16 times per minute at​ rest, the minute ventilation for this adult would be calculated as​ follows: Minute ventilation​ = 500 mL​ × 16/minute or 8000 mL.

The EMT would recognize which of the following vital signs as most likely to cause left ventricular​ failure?

Chronically elevated diastolic pressure between 120 and 140 mmHg

Which one of the following is the primary stimulus to breathe in normal human​ beings?

Level of CO2 in the body ​Normally, a​ person's rate and depth of breathing are regulated primarily by the amount of carbon dioxide in the blood. This is referred to as a hypercapnic or hypercarbic drive. The situation is different for patients with chronic obstructive pulmonary disease​ (COPD), such as emphysema. These patients have a tendency to retain carbon dioxide in arterial blood as a result of their poor gas exchange. When the arterial CO2 level is chronically​ elevated, the central chemoreceptors become insensitive to the small changes that typically stimulate ventilation. The peripheral chemoreceptors then become the primary stimulus for​ ventilation; instead of a small increase in carbon dioxide level being a strong stimulus for​ ventilation, the peripheral chemoreceptors rely on a decrease in the oxygen level to stimulate ventilation. Hypoxia becomes the stimulus for ventilation in place of hypercarbia. This is known as hypoxic drive. The level of nitrogen is not monitored by the body.

A ​20-yeardash-old female has called 911 for chest pain. On​ scene, you find that she has shallow breathing with an SpO2 reading of​ 91% on room air. She states that she was in a car crash yesterday and was diagnosed in the hospital with broken ribs. She says that her pain is right where the ribs are broken and rates it a​ 10/10. Breath sounds are present and clear bilaterally. In this​ situation, the EMT should attribute the hypoxia to which one of the​ following

Pain from rib injury prevents full expansion of the chest cage.

Which one of the following would most likely cause a patient to have a simple episode of syncope​ (fainting)?

Parasympathetic stimulation

A young patient is experiencing epiglottitis​ (swelling of the​ epiglottis). He is working hard to​ breathe, has stridorous​ respirations, and is extremely hypoxic. His skin is cyanotic and pulse rapid but strong. Which of the following is most likely causing the poor delivery of oxygen to the​ cells?

Partial occlusion of the airway

A patient with a low blood sugar is unresponsive with snoring respirations. His breathing is labored and his pulse is rapid and weak. Examination of the skin reveals it to be cool and diaphoretic. Your partner informs you of the following vital​ signs: pulse​ 120, respirations​ 18, blood pressure​ 132/60, and SpO2 at​ 84% on room air. Which one of the following actions would you perform​ first?

Perform a​ head-tilt chin-lift.

A slightly confused but conscious​ 61-year-old female with generalized weakness has a heart rate of 190 beats a minute. She has a history of high blood pressure and diabetes. Her blood pressure is​ 78/56 mmHg. Which one of the following would best explain the​ patient's presentation?

Tachycardia A faster heart rate may increase cardiac​ output; however, if the rate is extremely​ fast, the cardiac output may actually decrease. With excessively fast heart​ rates, usually​ >160 bpm in the adult​ patient, the time between beats is so short that there is not an adequate amount of time for the ventricles to fill. This reduces the​ preload, which in turn reduces the cardiac output. There is no information provided that would be indicative of hemorrhage or​ hypoxia, and while hypoglycemia in the still conscious patient may cause an increased heart​ rate, it does not adequately explain the very high heart rate or the very low systolic pressure.

A patient has a blood pressure of​ 140/98 mmHg. Which one of the following can the EMT ascertain from this​ reading?

The afterload is increased.

Which of the following statements about chemoreceptors in the human body is​ true?

The peripheral chemoreceptors are more sensitive to oxygen than carbon dioxide. The central chemoreceptors are located near the respiratory center in the medulla. These receptors are most sensitive to carbon dioxide and changes in the pH of the cerebrospinal fluid​ (CSF). The peripheral chemoreceptors are located in the aortic arch and the carotid bodies in the neck. These chemoreceptors are also somewhat sensitive to CO2 and pH but are most sensitive to the level of oxygen in the arterial blood.

Which of the following statements would be true of a patient who relies on the hypoxic drive to​ breathe?

The respiratory rate is set according to the level of O2 in the body. ​Normally, a​ person's rate and depth of breathing are regulated primarily by the amount of carbon dioxide in the blood. This is referred to as a hypercapnic or hypercarbic drive. The situation is different for patients with chronic obstructive pulmonary disease​ (COPD), such as emphysema. These patients have a tendency to retain carbon dioxide in arterial blood as a result of their poor gas exchange. When the arterial CO2 level is chronically​ elevated, the central chemoreceptors become insensitive to the small changes that typically stimulate ventilation. The peripheral chemoreceptors then become the primary stimulus for​ ventilation; instead of a small increase in carbon dioxide level being a strong stimulus for​ ventilation, the peripheral chemoreceptors rely on a decrease in the oxygen level to stimulate ventilation. Hypoxia becomes the stimulus for ventilation in place of hypercarbia. This is known as hypoxic drive.

Which of the following statements about the​ ventilation/perfusion (V/Q) ratio in a healthy person is​ true?

The upper portion of the lungs has more ventilation than blood flow. The​ ventilation/perfusion ratio is never at an ideal state in any zones of the lungs. In the​ apexes, the amount of available ventilation in the alveoli exceeds the amount of perfusion through the pulmonary​ capillaries; that​ is, more oxygen is available in the alveoli than the supply of blood is able to pick up and transport. This is considered to be wasted ventilation. In the​ bases, the amount of perfusion exceeds the amount of​ ventilation; this means that more blood is moving through the pulmonary capillaries than there is alveolar oxygen available for it to pick up.

A​ patient's SpO2 increased from​ 89% to​ 95% after he received a bronchodilating drug for his asthma. Where did the​ patient's problem most likely​ originate?

Ventilation portion of the​ V/Q ratio If a condition or injury causes less oxygenated air to be available in the alveoli for the amount of blood flowing through the pulmonary​ capillaries, the end result will be less oxygen saturating the blood and less oxygen delivered to the​ cells, creating hypoxemia and cellular hypoxia. If a patient is having an asthma attack and the bronchioles are inflamed and​ constricted, the restricted airways reduce airflow and provide less oxygenated air to the alveoli for gas exchange. The blood pressure is not​ affected; therefore, the amount of blood passing through the pulmonary capillaries remains normal. A ventilation disturbance has been created by making less oxygen available to the blood that is passing through the capillaries. In this​ condition, there is wasted​ perfusion, since the blood is available but there is an inadequate amount of oxygen to be picked up. This disturbance in ventilation leads to hypoxemia and cellular hypoxia.

A patient is hemorrhaging internally within his​ colon, therein impairing perfusion to the cells of his body. Aside from the​ bleeding, the patient has no other problems. In this​ scenario, the problem impairing adequate perfusion would​ be:

decreased blood volume. In this​ example, a reduction in blood passing through the capillaries adjoining the normally functioning lungs will pick up less oxygen and will then deliver less oxygen to the cells. If the amount of oxygen is reduced​ significantly, the cells will shift from aerobic to anaerobic metabolism. Anaerobic metabolism will reduce the amount of ATP​ (energy) produced for normal cell function and will begin to produce lactic acid as a​ by-product, both of which will adversely affect normal cell and organ function and may eventually lead to cell and organ death. Poor pump function and carbon dioxide elimination will be a result of the perfusion​ problem, not the cause.

A confused and lethargic​ 24-year-old male has intentionally overdosed on a narcotic medication. His vital signs​ are: pulse​ 36, respirations​ 8, blood pressure​ 50/20, and SpO2 ​ 88% with 15 liters per minute of oxygen. The greatest danger to this​ patient's well-being​ is:

decreased cellular perfusion.

A patient has failure of the left side of his heart.​ Consequently, the blood is backing up into the pulmonary artery and spilling out into the lung​ tissue, causing him to be short of breath and moderately hypoxic. The EMT should recognize this condition as a product​ of:

increased hydrostatic pressure. Hydrostatic pressure is the force inside the vessel or capillary bed that is generated by the contraction of the heart and the blood pressure. Hydrostatic pressure exerts a push inside the vessel or​ capillary; that​ is, it acts to push fluid out of the vessel or capillary through the vessel wall and into the interstitial space. A high hydrostatic pressure would force more fluid out of the vessel or capillary and promote edema from excess fluid outside the vessels. If a patient has a left ventricle that is failing and unable to pump blood​ effectively, the volume and pressure in the left​ atrium, pulmonary​ vein, and pulmonary capillaries rise. This occurs because the pulmonary​ capillaries, pulmonary​ vein, and left atrium are the pathways by which blood enters the left ventricle. When the left ventricle fails to empty​ effectively, blood backs up into the left atrium and pulmonary​ vessels, which increases the pressure within them. The increased hydrostatic pressure inside the pulmonary capillaries forces fluid out of them. The extruded fluid has a tendency to collect in the spaces between the alveoli and capillaries and around the​ alveoli, thus reducing the ability to exchange oxygen and carbon dioxide across the​ alveolar/capillary membrane. OK

Assessment of a hypoxic patient with a history of lung disease reveals him to be using​ well-developed accessory muscles to exhale. As an​ EMT, you should recognize that the​ patient:

is using energy to exhale and is in danger of respiratory failure. Exhalation is normally a passive​ process, requiring no expenditure of energy.​ However, if the patient is struggling to expel air from the​ lungs, the accessory muscles of exhalation may be used to create more positive pressure in the chest. If the accessory muscles are​ used, exhalation becomes an active​ process, requiring energy. If the patient is also using accessory muscles and additional energy to​ inhale, the extra energy needed for exhalation may cause the respiratory muscles to​ fatigue, leading to respiratory failure. The use of accessory muscles in a patient who is hypoxic is an indicator that the patient is decompensating and is in danger of entering total respiratory failure.

Respiratory rate x tidal volume​ =

minute ventilation. Minute​ ventilation, also known as minute​ volume, is the amount of air moved in and out of the lungs in one minute. It is determined by multiplying the tidal volume by the frequency of ventilation in one minute. The tidal volume​ (VT) is the volume of air breathed in with each individual breath. The frequency of ventilation​ (f) is generally calculated as the number of ventilations in one minute.

For a patient reliant on the hypoxic drive to​ breathe, the respiratory rate will increase​ when:

oxygen levels decrease. ​Normally, a​ person's rate and depth of breathing are regulated primarily by the amount of carbon dioxide in the blood. This is referred to as a hypercapnic or hypercarbic drive. The situation is different for patients with chronic obstructive pulmonary disease​ (COPD), such as emphysema. These patients have a tendency to retain carbon dioxide in arterial blood as a result of their poor gas exchange. When the arterial CO2 level is chronically​ elevated, the central chemoreceptors become insensitive to the small changes that typically stimulate ventilation. The peripheral chemoreceptors then become the primary stimulus for​ ventilation; instead of a small increase in carbon dioxide level being a strong stimulus for​ ventilation, the peripheral chemoreceptors rely on a decrease in the oxygen level to stimulate ventilation. Hypoxia becomes the stimulus for ventilation in place of hypercarbia. This is known as hypoxic drive.

Paramedics have administered a medication to a patient in heart failure. The medication specifically causes the veins to​ enlarge, thus decreasing the amount of blood coming back to the heart for pumping. The EMT would recognize this action​ as:

preload.