Case Respiratory System
1. What are the values for Mary’s tidal volume (TV) and the alveolar ventilation rate (AVR)? (Remember to consider the dead space of 150ml). Normal alveolar ventilation is 4.0-5.0L. How does Mary’s AVR compare with normal volumes? a. Tidal volume= Minute Ventilation Rate divide by respiratory rate (MVR/RR) MVR= 6.1L/min=6100ml?min RR=30bpm TV= 6100/30=203ml b. Alveolar ventilation rate= the difference between Tidal volume and Dead space multiplied by Respiratory rate (TV-DSV)*RR TV= 203ml DSV=150ml RR=30bpm AVR=(203-150)*30=1590ml=1.6L Mary’s AVR is in 2.5-3 times lower than normal values.
2. What caused the drop in alveolar ventilation? Explain your answer. PO2=60mmHg and PCO2=45mmHg are caused the drop in alveolar ventilation. The normal range of PO2=104mmHg and PCO2=40mmHg, but in our case PO2=60mmHg that is low, and PCO2=45mmHg that is high. According to the https://emedicine.medscape.com, the chemoreceptors PCO2, PO2, and pH are regulate and influence our ventilation; therefore, failure of any of these mechanisms can lead hypoventilation. Also, because PO2 is only 60mmHg (is low) it increases respiratory activity. So in our case the respiratory rate is high (30bpm). The high RR and low TV decrease AVR. The AVR=1.6L that would be not enough to meet CO2 that would lead to increases PCO2. “Even if the rate was slowed to 30 breaths per minute, the result would be an alveolar ventilation of only 1.50 L. This would be inadequate to meet CO2 production and would lead to an elevation of the Paco2 and a lowering of the pH. Both the central and peripheral chemoreceptors would be stimulated. There might also be a concomitant fall in Pao2, which would lead to increased neural output from the carotid bodies. The result of the increase of input to the central center would be an alteration in the rate and pattern of breathing” (https://www.ncbi.nlm.nih.gov/books/NBK365/).
How it works
3. Which nerves and muscles are involved in this patient to cause her paralysis? Explain your answer. The Spinal cord is involved in this patient to cause her paralysis. The spinal cord is part of the central nervous system and has a direct connection with the internal organs, skin and muscles of a person. It is the main channel providing the brain with information from the rest of the body. The spinal cord is allowing the brain to control the executive organs, including transmitting “orders” to regulate movement. The damage of spinal cord causes the full or partial paralysis of voluntary mobility and leads to the loss of all types of sensitivity below the damage zone (https://www.guttmann.com). The spinal cord has long nerve fibers called axons. Axons in spinal cord carry signals downward from the brain and upward toward the brain. Many axons are covered by myelin; therefore, loss of myelin, which can occur with cord trauma, prevents effective transmission of nerve signals. According to the https://www.christopherreeve.org, the cervical region C1 through C8 control signals to the neck, arms, hands, and some cases the diaphragm. “Injury above the C3 level may require a ventilator for the person to breathe. Injury above the C4 level usually means loss of movement and sensation in all four limbs, although often shoulder and neck movement is available to facilitate sip-and-puff devices for mobility, environmental control, and communication. C5 injuries often spare the control of shoulder and biceps, but there is not much control at the wrist or hand. Those at C5 can usually feed themselves and independently handle many activities of daily living. C6 injuries generally allow wrist control, enough to be able to drive adaptive vehicles and handle personal hygiene, but those affected at this level often lack fine hand function.”
4. How is the residual volume involved in this scenario? Explain your answer. The Residual volume in this scenario is very high. Residual volume (RV) is amount of air remaining in the lungs after max expiration; it is amount that can never voluntary be exhaled. To find RV we should subtract Forced Viral Capacity (FCV or VC) from Total Lung Capacity (TLC). RV=TLC-VC. Typical volume of TLC=6000ml. RV=6000-660=5340ml that it is to high, typically RV=1300ml. In this case, there is around 4 times more air in the lungs than with normally functioning lungs.
5. Define dyspnea. Dyspnea is shortness of breath, or difficult or labored breathing. It is usually a sing with serious lungs’ disease or heart’ disease.
6. What is causing Mary to experience dyspnea? Explain your answer. The lack of oxygen is causing Mary to experience dyspnea. The respiratory center in the brain accelerates breathing with low levels of oxygen in the blood or high levels of carbon dioxide. If the lungs do not function normally, even a small effort can significantly increase the frequency of breathing. Mary’s PO2=60mmHg that is low; therefore, her respiratory rate is increased; Mary has shortness of breath (dyspnea). This dyspnea may be caused by trauma.
7. Define tachypnea. Tachypnea is abnormal rapid breathing (fast or deep respiration) that occur when the person los of CO2 from the blood; therefore, the blood pressure is decreased.