Question

Total Lung Capacity (TLC) 1. Write the equation you will use here. TLC = IRVITVTERUTRV 2. Check your equation with your instructor 3. Calculate TLC 4. Record TLC in Table 8-4. Calculate the total lung capacity (TLC). Record the TLC in Table 8-4. Forced Expiratory Volume (FEV) L e volume measurements can provide information on how well a patient's lungs are functioning. For example vital capacity can be divided into different measurements based on how quickly the air is forced out of the lungs. In forced vital capacity (FVC), the amount of air quickly forced out is plotted against the time it takes to empty the lungs. A similar measurement to FVC is forced expiratory volume in one second (FEV1). In a healthy person, the ratio of FEV 1 to FVC is about 80%. A patient with obstructive lung disease, such as emphysema or chronic bronchitis, has a lower vital capacity but also blows our less air in one second, so the FEV 1/FVC ratio is much lower than normal. In restrictive lung disease, such as interstitial lung disease, the lungs cannot fully inflate, and thus the FVC of the patient will be greatly reduced. This leads to a higher than normal FEV 1/FVC ratio, because he or she is able to quickly blow out the air to near capacity in one second. Examine the graphs in Figure 8-5, and label each graph as Normal, Obstructive, or Restrictive. obstructive FEV, FVC: FEV, FVC Volume (liters) Volume (liters) Volume (liters) Time (seconds) Time (seconds) Time (seconds) FIGURE 8-5 Graphs of FEV1/FVC.

Answer 1

Total lung capacity : it is the maximum volume of air the lung can accommodate.. it is the amount of air in the lung after maximum inspiration. It is computed as TLC=VC+RV

VC=TV+IRV+ERV. VC vital capacity

IRV inspiratory reserve volume

ERV expiratory reserve volume

RV: reserve volume

TLC=IRV+ERV+TV+RV

normal 6 Litres

Figure8.5

graph 1 normal FEV1 =80%VC

graph 2 obstructive (inspiration normal expiration obstructed)

VC normal FEV1 decreases

graph 3 restrictive (chest expansion restricted)

VC decreases FEV1 normal

TIP: plot dotted line and observe VC and FEV1 and also the difference between them.