Bài Giảng Hô Hấp Ký

1. HÔ HẤP KÝ
(SPIROMETRY)

2. GIỚI THIỆU
 Hô hấp ký là một trong bốn xét nghiệm
cơ bản của thăm dò CNHH (hô hấp ký,
đo tổng dung lượng phổi, khả năng
khuếch tán của phổi và khí trong máu).
 Là tiêu chuẩn vàng để chẩn đoán COPD
 Là dụng cụ dùng để đo các thể tích hít
vào và thở ra theo thời gian.
 Giá trị lâm sàng của HHK phụ thuộc vào
chất lượng máy, kỹ thuật đo, và chọn
giá trị dự đoán phù hợp.

3. CÁC LOẠI HÔ HẤP KÝ
 Máy đo thể tích theo thời gian:
Là loại cổ điển có chuông úp trên một
thùng nước hay dạng đèn xếp.

4. MÁY HHK ĐO THỂ TÍCH

5. CÁC LOẠI HÔ HẤP KÝ
 Máy đo lưu lượng theo thể tích phổi
Loại dùng bộ phận nhận cảm để đo
khuynh áp từ đó tính ra lưu lượng và thể
tích phổi

6. MÁY HHK ĐO LƯU LƯỢNG

7. MÁY HHK ĐIỆN TỬ ĐỂ BÀN

8. MÁY HHK XÁCH TAY

9. Các thể tích và dung tích phổi
 4 thể tích: thể tích
dự trữ hít vào, thể
tích khí lưu thông,
thể tích dự trữ thở
ra, và thể tích khí
cặn
 4 dung tích: dung
tích sống, dung tích
hít vào, dung tích
cặn chức năng,
dung tích phổi toàn
bộ

10. Các thể tích phổi
 Thể tích khí lưu thông
(Tidal Volume- TV):
Thể tích khí của một
lần hít vào hoặc thở ra
bình thường
 Thể tích dự trữ hít vào
(Inspiratory Reserve
Volume -IRV): Thể tích
khí hít vào thêm khi
gắng sức, sau khi đã
hít vào bình thường
 Thể tích khí dự trữ thở
ra (Expiratory Reserve
Volume -ERV): Thể tích
khí thở ra thêm được
khi gắng sức, sau khi
đã thở ra bình thường

11. Các thể tích phổi
 Thể tích khí cặn
(Residual Volume
-RV):
 Thể tích khí vẫn còn
ở trong phổi sau khi
thở ra tối đa
 Được đo trực tiếp
(FRC-ERV) bằng
phế thân kế (Body
Plethysmography)
hay pha loãng
helium, không đo
bằng spirometry

12. Các dung tích phổi
 Total Lung Capacity
(TLC): Tổng các thể
tích trong phổi
 Vital Capacity (VC):
Thể tích lớn nhất mà
người ta có thể huy
động được bằng cách
thở ra hết sức sau khi
đã hít vào hết sức
 Inspiratory Capacity
(IC): Tổng của thể tích
dự trữ hít vào và thể
tích khí lưu thông

13. Các dung tích phổi (tt)
 Dung tích cặn chức
năng (Functional
Residual Capacity -
FRC):
 Tổng RV và ERV
hoặc thể tích khí của
phổi ở cuối thì thở ra
bình thường
 Được đo bằng phế
thân kế (Body
Plethysmography)
hay pha loãng
helium, không đo
bằng spirometry

14. CÁC CHỈ SỐ HÔ HẤP KÝ
 FVC (Forced vital capacity):
Thể tích khí toàn bộ được thở ra gắng sức
trong một lần thở
 FEV1 (Forced expiratory volume in one
second): Thể tích khí thở ra trong giây đầu
 Tỉ số FEV1/FVC (chỉ số Gaensler); FEV1/VC (
chỉ số Tiffeneau):
Phân số khí được thở ra trong giây đầu liên
quan với thể tích khí toàn bộ được thở ra

15. CÁC CHỈ SỐ HÔ HẤP KÝ
 FEF 25-75% (Forced Expiratory
Flow between 25% and 75% of the
FVC)(L/s):
Lưu lượng thở ra gắng sức trong
khoảng 25 – 75% của dung tích
sống gắng sức
 PEF ( Peak Expiratory Flow)(L/s):
Lưu lượng thở ra đỉnh

16. CÁC CHỈ SỐ HÔ HẤP KÝ (tt)
 PIF ( Peak Inspiratory Flow)(L/s):
Lưu lượng hít vào đỉnh: Lưu lượng cao nhất
trong lúc hít vào, thường được dùng để đánh
giá tắc nghẽn đường hô hấp trên.
 MVV ( Maximal Volumtary Ventilation)
(L/phút)
Thể tích thông khí tự ý tối đa

17. GIẢN ĐỒ THỂ TÍCH THEO THỜI GIAN

18. ĐƯỜNG CONG LƯU LƯỢNG THỂ TÍCH

19. KẾT QUẢ HÔ HẤP KÝ
Bình thường
Tắc nghẽn
Hạn chế
Dạng hỗn hợp

20. HÔ HẤP KÝ
CÁC GIÁ TRỊ BÌNH THƯỜNG

21. CÁC GIÁ TRỊ BÌNH THƯỜNG
ĐƯỢC DỰ ĐOÁN
Phụ thuộc vào:
 Tuổi
 Chiều cao
 Giới
 Chủng tộc

22. CÁC GIÁ TRỊ BÌNH THƯỜNG
ĐƯỢC DỰ ĐOÁN (tt)
 Được dựa trên các khảo sát trong dân số
lớn
 Các giá trị được dự đoán là các giá trị
trung bình lấy từ kết quả khảo sát
 Không có các khảo sát trong dân số
người già

23. Tiêu chuẩn cho một hô hấp ký bình
thường sau dãn phế quản
FEV1: % dự đoán > 80%
FVC: % dự đoán > 80%
FEV1/FVC: > 0.7

24. Đường cong lưu lượng - thể tích
và thể tích theo thời gian của một người bình thường

25. HÔ HẤP KÝ
BỆNH PHỔI TẮC NGHẼN

26. Tiêu chuẩn chẩn đoán hội chứng tắc
nghẽn trên hô hấp ký
FEV1:%dự đoán < 80
FVC:%dự đoán > 80 hoặc < 80
FEV1/FVC:< 0.7

27. Đường cong chỉ sự tắc nghẽn

28. HÔ HẤP KÝ
BỆNH PHỔI HẠN CHẾ

29. Tiêu chuẩn bệnh phổi hạn chế
FEV1: % dự đoán > 80 hoặc <
80
FVC: % dự đoán < 80
FEV1/FVC: > 0.7

30. Đường cong chỉ sự hạn chế

31. RỐI LOẠN THÔNG KHÍ HỔN HỢP
FEV1: % dự đoán < 80%
FVC: % dự đoán < 80%
FEV1 /FVC: < 0.7

32. Đường cong chỉ rối loạn thông khí
kiểu hổn hợp
Thể tích, lít
Thời gian, giây
Bình thường
Tắc nghẽn + hạn
chế

33. HÔ HẤP KÝ
ĐƯỜNG CONG
LƯU LƯỢNG - THỂ TÍCH

34. ĐƯỜNG CONG LƯU LƯỢNG -THỂ
TÍCH
chuẩn cho hầu hết các máy hô hấp ký
để bàn
Cung cấp thông tin thêm vào đường
cong thể tích theo thời gian
Không quá khó để giải thích kết quả
Phát hiện tốt hơn khi có sự tắc nghẽn
luồng khí nhẹ

35. Các dạng đường cong lưu lượng thể tích

36. CHỈ ĐỊNH
 Đánh giá các triệu chứng, các dấu hiệu bệnh
phổi
 Đánh giá sự tiến triển của bệnh phổi
 Theo dõi hiệu quả điều trị
 Đánh giá nguy cơ hô hấp trước phẫu thuật
 Giám định y khoa về sức khỏe hô hấp
 Tầm soát các đối tượng có nguy cơ bệnh phổi
 Theo dõi tác dụng độc hại của một số thuốc,
hóa chất

37. CHỐNG CHỈ ĐỊNH
 Tình trạng tim mạch không ổn định
 Nhồi máu cơ tim gần đây
 Phẫu thuật mắt, ngực, bụng gần đây
 Tràn khí màng phổi
 Phình động mạch chủ
 Ho ra máu
 Các tình trạng cấp tính như chóng mặt,
viêm phổi

38. CÁC BIẾN CHỨNG
 Ngất, chóng mặt, nhức đầu nhẹ
 Co thắt phế quản
 Ho
 Giảm độ bão hòa oxy nếu điều trị
oxy bị gián đoạn
 Áp lực nội sọ tăng
 Tràn khí màng phổi
 Đau ngực
 Nhiễm trùng

39. Hết

40. Spirometry and Related Tests
RET 2414
Pulmonary Function Testing
Module 2.0

41. SPIROMETRY AND RELATED TESTS
 Learning Objectives
 Determine whether spirometry is
acceptable and reproducible
 Identify airway obstruction using forced
vital capacity (FVC) and forced expiratory
volume (FEV1)
 Differentiate between obstruction and
restriction as causes of reduced vital
capacity

42. SPIROMETRY AND RELATED TESTS
 Learning Objectives
 Distinguish between large and small
airway obstruction by evaluating flow-volume
curves
 Determine whether there is a significant
response to bronchodilators
 Select the appropriate FVC and FEV1 for
reporting from series of spirometry
maneuvers

43. Predicted Values
 Laboratory Normal Ranges
 Laboratory tests performed on a large
number of normal population will show
a range of results

44. Predicted Values
 Laboratory Normal Ranges

45. Predicted Values
 Laboratory Normal Ranges
Most clinical laboratories consider
two standard deviations from the
mean as the normal range since it
includes 95% of the normal
population.

46. PFT Reports
o When performing PFT’s three values
are reported:
o Actual – what the patient performed
o Predicted – what the patient should
have performed based on Age, Height,
Sex, Weight, and Ethnicity
o % Predicted – a comparison of the
actual value to the predicted value

47. PFT Reports
 Example
Actual Predicted %Predicted
VC 4.0 5.0 80%

48. SPIROMETRY
 Vital Capacity
The vital capacity (VC) is the volume
of gas measured from a slow,
complete expiration after a maximal
inspiration, without a forced effort.

49. SPIROMETRY
 Vital Capacity

50. SPIROMETRY
 Vital Capacity
 Valid VC measurements important
 IC and ERV used to calculate
RV and TLC
Example:
 RV = FRC - ERV
 TLC = IC + FRC

51. SPIROMETRY
 VC: Criteria for Acceptability
1. End-expiratory volume varies by less than
100 ml for three preceding breaths
2. Volume plateau observed at maximal
inspiration and expiration

52. SPIROMETRY
 VC: Criteria for Acceptability
3. Three acceptable VC maneuvers should be
obtained; volume within 150 ml.
4. VC should be within 150 ml of FVC value

53. SPIROMETRY
 VC: Selection Criteria
The largest value from at least 3 acceptable
maneuvers should be reported

54. SPIROMETRY
 VC: Significance/Pathophysiology
 Decreased VC
 Loss of distensible lung tissue
 Lung CA
 Pulmonary edema
 Pneumonia
 Pulmonary vascular congestion
 Surgical removal of lung tissue
 Tissue loss
 Space-occupying lesions
 Changes in lung tissue

55. SPIROMETRY
 VC: Significance/Pathophysiology
 Decreased VC
 Obstructive lung disease
 Respiratory depression or
neuromuscular disease
 Pleural effusion
 Pneumothorax
 Hiatal hernia
 Enlarged heart

56. SPIROMETRY
 VC: Significance/Pathophysiology
 Decreased VC
 Limited movement of diaphragm
 Pregnancy
 Abdominal fluids
 Tumors
 Limitation of chest wall movement
 Scleraderma
 Kyphoscoliosis
 Pain

57. SPIROMETRY
 VC: Significance/Pathophysiology
 If the VC is less than 80% of
predicted: FVC can reveal if caused by
obstruction

58. SPIROMETRY
 VC: Significance/Pathophysiology
 If the VC is less than 80% of
predicted: Lung volume testing can
reveal if caused by restriction

59. SPIROMETRY
 Forced Vital Capacity (FVC)
The maximum volume of gas that
can be expired when the patient
exhales as forcefully and rapidly as
possible after maximal inspiration
(sitting or standing)

60. SPIROMETRY
 FVC (should be within 150 ml of VC)

61. SPIROMETRY
 FVC: Criteria for Acceptability
1. Maximal effort; no cough or glottic closure
during the first second; no leaks or obstruction
of the mouthpiece.
2. Good start-of-test; back extrapolated volume
<5% of FVC or 150 ml, whichever is greater

62. SPIROMETRY
 FVC: Criteria for Acceptability
3. Tracing shows 6 seconds of exhalation or an
obvious plateau (<0.025L for ≥1s); no early
termination or cutoff; or subject cannot or
should not continue to exhale

63. SPIROMETRY
 FVC: Criteria for Acceptability
4. Three acceptable spirograms obtained; two
largest FVC values within 150 ml; two largest
FEV1 values within 150 ml

64. SPIROMETRY
 FVC: Selection Criteria
The largest FVC and largest FEV1 (BTPS)
should be reported, even if they do not
come from the same curve

65. SPIROMETRY
 FVC: When to call it quits !!!
If reproducible values cannot be
obtained after eight attempts, testing
may be discontinued

66. SPIROMETRY
 FVC: Significance and Pathophysiology
 FVC equals VC in healthy individuals
 FVC is often lower in patients with
obstructive disease

67. SPIROMETRY
 FVC: Significance and Pathophysiology
 FVC can be reduced by:
 Mucus plugging
 Bronchiolar narrowing
 Chronic or acute asthma
 Bronchiectasis
 Cystic fibrosis
 Trachea or mainstem bronchi obstruction

68. SPIROMETRY
 FVC: Significance and Pathophysiology
 Healthy adults can exhale their FVC
within 4 – 6 seconds
 Patients with severe obstruction (e.g.,
emphysema) may require 20 seconds,
however, exhalation times >15
seconds will rarely change clinical
decisions

69. SPIROMETRY
 FVC: Significance and Pathophysiology
 FVC is also decreased in restrictive
lung disease
 Pulmonary fibrosis
 dusts/toxins/drugs/radiation
 Congestion of pulmonary blood flow
 pneumonia/pulmonary hypertension/PE
 Space occupying lesions
 tumors/pleural effusion

70. SPIROMETRY
 FVC: Significance and Pathophysiology
 FVC is also decreased in restrictive
lung disease
 Neuromuscular disorders, e.g,
 myasthenia gravis, Guillain-Barre
 Chest deformities, e.g,
 scoliosis/kyphoscoliosis
 Obesity or pregnancy

71. SPIROMETRY
 Forced Expiratory Volume (FEV1)
The volume expired over the first
second of an FVC maneuver

72. SPIROMETRY
 Forced Expiratory Volume (FEV1)
May be reduced in obstructive or
restrictive patterns, or poor patient
effort

73. SPIROMETRY
 Forced Expiratory Volume (FEV1)
 In obstructive disease, FEV1 may be
decreased because of:
 Airway narrowing during forced expiration
 emphysema
 Mucus secretions
 Bronchospasm
 Inflammation (asthma/bronchitis)
 Large airway obstruction
 tumors/foreign bodies

74. SPIROMETRY
 Forced Expiratory Volume (FEV1)
 The ability to work or function in daily
life is related to the FEV1 and FVC
 Patients with markedly reduced FEV1
values are more likely to die from COPD or
lung cancer

75. SPIROMETRY
 Forced Expiratory Volume (FEV1)
 FEV1 may be reduced in restrictive
lung processes
 Fibrosis
 Edema
 Space-occupying lesions
 Neuromuscular diseases
 Obesity
 Chest wall deformity

76. SPIROMETRY
 Forced Expiratory Volume (FEV1)
 FEV1 is the most widely used
spirometric parameter, particularly
for assessment of airway
obstruction

77. SPIROMETRY
 Forced Expiratory Volume (FEV1)
 FEV1 is used in conjunction with
FVC for:
 Simple screening
 Response to bronchodilator therapy
 Response to bronchoprovocation
 Detection of exercise-induced
bronchospasm

78. SPIROMETRY
 Forced Expiratory Volume Ratio (FEVT%)
 FEVT% = FEVT/FVC x 100
 Useful in distinguishing between
obstructive and restrictive causes of
reduced FEV1 values

79. SPIROMETRY
 Forced Expiratory Volume Ratio (FEVT%)
 Normal FEVT% Ratios for Health Adults
 FEV 0.5% = 50%-60%
 FEV 1% = 75%-85%
 FEV 2% = 90%-95%
 FEV 3% = 95%-98%
 FEV 6% = 98%-100%
 Patients with obstructive disease have
reduced FEVT% for each interval

80. SPIROMETRY
 Forced Expiratory Volume Ratio (FEVT%)
 A decrease FEV1/FVC ratio is the
“hallmark” of obstructive disease
 FEV1/FVC <75%

81. SPIROMETRY
 Forced Expiratory Volume Ratio (FEVT%)
 Patients with restrictive disease often have
normal or increased FEVT% values
 FEV1 and FVC are usually reduced in equal
proportions
 The presence of a restrictive disorder may
by suggested by a reduced FVC and a
normal or increased FEV1/FVC ration

82. SPIROMETRY
 Forced Expiratory Flow 25% - 75%
(maximum mid-expiratory flow)
 FEF 25%-75% is measured from a
segment of the FVC that includes flow
from medium and small airways
 Normal values: 4 – 5 L/sec

83. SPIROMETRY
 Forced Expiratory Flow 25% - 75%
In the presence of a borderline
value for FEV1/FVC, a low FEF
25%-75% may help confirm
airway obstruction

84. SPIROMETRY
 Flow – Volume Curve
 AKA: Flow–Volume Loop (FVL)
The maximum expiratory flow-volume
(MEFV) curve shows flow
as the patient exhales from
maximal inspiration (TLC) to
maximal expiration (RV)
 FVC followed by FIVC

85. SPIROMETRY
 FVL
 X axis: Volume
 Y axis: Flow
 PEF (Peak Expiratory Flow)
 PIF (Peak Inspiratory Flow)
.
 Vmax 75 or FEF 25%
FVC Remaining or Percentage FVC exhaled
.
 Vmax 50 or FEF 50%
.
 Vmax 25 or FEF 75%
FEF 25% or Vmax 75
FEF 75% or Vmax 25%

86. SPIROMETRY
 FVL
 FEVT and FEF% can be read from
the timing marks (ticks) on the FVL

87. SPIROMETRY
 FVL
 Significant decreases in flow or volume
are easily detected from a single graphic
display

88. SPIROMETRY
 FVL: Severe Obstruction

89. SPIROMETRY
 FVL: Bronchodilation

90. SPIROMETRY
 Peak Expiratory Flow (PEF)
 The maximum flow obtained
during a FVC maneuver
 Measured from a FVL
 In laboratory, must perform a
minimum of 3 PEF maneuvers
 Largest 2 of 3 must be within 0.67
L/S (40 L/min)
 Primarily measures large airway
function
 Many portable devices available

91. SPIROMETRY
 Peak Expiratory Flow (PEF)
When used to monitor asthmatics
 Establish best PEF over a 2-3 week
period
 Should be measured twice daily
(morning and evening)
 Daily measurements are compared to
personal best

92. SPIROMETRY
 Peak Expiratory Flow (PEF)
 The National Asthma Education Program
suggests a zone system
 Green: 80%-100% of personal best
 Routine treatment can be continued; consider
reducing medications
 Yellow: 50%-80% of personal best
 Acute exacerbation may be present
 Temporary increase in medication may be
needed
 Maintenance therapy may need increases
 Red: Less than 50% of personal best
 Bronchodilators should be taken immediately;
begin oral steroids; clinician should be
notified if PEF fails to return to yellow or
green within 2 – 4 hours

93. SPIROMETRY
 Peak Expiratory Flow (PEF)
 PEF is a recognized means of
monitoring asthma
 Provides serial measurements
of PEF as a guide to treatment
 ATS Recommended Ranges
 60-400 L/min (children)
 100-850 L/min (adults)

94. SPIROMETRY
 Maximum Voluntary Ventilation
(MVV)
The volume of air exhaled in a
specific interval during rapid, forced
breathing

95. SPIROMETRY
 MVV
 Rapid, deep breathing
 VT ~50% of VC
 For 12-15 seconds

96. SPIROMETRY
 MVV
 Tests overall function of
respiratory system
 Airway resistance
 Respiratory muscles
 Compliance of lungs/chest wall
 Ventilatory control mechanisms

97. SPIROMETRY
 MVV
 At least 2 acceptable maneuvers should be
performed
 Two largest should be within 10% of each
other
 Volumes extrapolated out to 60 seconds
and corrected to BTPS
 MVV is approximately equal to 35 time the
FEV1

98. SPIROMETRY
 MVV
 Selection Criteria
 The highest MVV (L/min, BTPS) and MVV
rate (breaths / min) should be reported

99. SPIROMETRY
 MVV
Decreased in:
 Patients with moderate to severe
obstructive lung disease
 Patients who are weak or have decreased
endurance
 Patients with neurological deficits

100. SPIROMETRY
 MVV
Decreased in:
 Patients with paralysis or nerve damage
 A markedly reduced MVV correlates with
postoperative risk for patients having
abdominal or thoracic surgery

101. SPIROMETRY
 Before/After Bronchodilator
 Spirometry is performed before
and after bronchodilator
administration to determine the
reversibility of airway obstruction

102. SPIROMETRY
 Before/After Bronchodilator
 An FEV1% less than predicted is a
good indication for bronchodilator
study
 In most patients, an FEV1% less
than 70% indicates obstruction

103. SPIROMETRY
 Before/After Bronchodilator
 Any pulmonary function parameter
may be measured before and after
bronchodilator therapy
 FEV1 and specific airway
conductance (SGaw) are usually
evaluated

104. SPIROMETRY
 Before/After Bronchodilator
 Lung volumes should be recorded
before bronchodilator
administration
 Lung volumes and DLco may also
respond to bronchodilator therapy

105. SPIROMETRY
 Before/After Bronchodilator
 Routine bronchodilator therapy should be
withheld prior to spirometry
 Ruppel 9th edition, pg. 66: Table 2-2
 Short-acting β-agonists 4 hours
 Short-acting anticholinergic 4 hours
 Long-acting β-agonists 12 hours
 Long-acting anticholinergic 24 hours
 Methylxanthines (theophyllines) 12 hours
 Slow release methylxanthines 24 hours
 Cromolyn sodium 8-12 hours
 Leukotriene modifiers 24 hours
 Inhaled steroids Maintain dosage

106. SPIROMETRY
 Before/After Bronchodilator
 Minimum of 10 minutes, up to 15
minutes, between administration
and repeat testing is recommended
(30 minutes for short-acting
anticholinergic agents)
 FEV1, FVC, FEF25%-75%, PEF,
SGaw are commonly made before
and after bronchodilator
administration

107. SPIROMETRY
 Before/After Bronchodilator
 Percentage of change is calculated
%Change = Postdrug – Predrug X 100
Predrug

108. SPIROMETRY
 Before/After Bronchodilator
 FEV1 is the most commonly used
test for quantifying bronchodilator
response
 FEV1% should not be used to judge
bronchodilation response
 SGaw may show a marked increase
after bronchodilator therapy

109. SPIROMETRY
 Before/After Bronchodilator
Significance and Pathophysiology
 Considered significant if:
 FEV1 or FVC increase ≥12% and ≥200 ml
 SGaw increases 30% - 40%

110. SPIROMETRY
 Before/After Bronchodilator
Significance and Pathophysiology
 Diseases involving the bronchial
(and bronchiolar) smooth muscle
usually improve most from “before”
to “after”
 Increase >50% in FEV1 may occur in
patients with asthma

111. SPIROMETRY
 Before/After Bronchodilator
Significance and Pathophysiology
 Patients with chronic obstructive
diseases may show little
improvement in flows
 Inadequate drug deposition (poor
inspiratory effort)
 Patient may respond to different drug
 Paradoxical response <8% or 150 ml not
significant

112. SPIROMETRY
 Maximal Inspiratory Pressure
(MIP)
 The lowest pressure developed
during a forceful inspiration against
an occluded airway
 Primarily measures inspiratory muscle
strength

113. SPIROMETRY
 MIP
 Usually measured at maximal
expiration (residual volume)
 Can be measured at FRC
 Recorded as a negative number in
cm H20 or mm Hg, e.g. (-60 cm H2O)

114. SPIROMETRY
 MIP

115. SPIROMETRY
 MIP
Significance and Pathophysiology
 Healthy adults > -60 cm H2O
 Decreased in patients with:
 Neuromuscular disease
 Diseases involving the diaphragm,
intercostal, or accessory muscles
 Hyperinflation (emphysema)

116. SPIROMETRY
 MIP
Significance and Pathophysiology
 Sometimes used to measure
response to respiratory muscle
training
 Often used in the assessment of
respiratory muscle function in
patients who need ventilatory
support

117. SPIROMETRY
 Maximal Expiratory Pressure (MEP)
 The highest pressure developed
during a forceful exhalation against
an occluded airway
 Dependent upon function of the
abdominal muscles, accessory muscles
of expiration, and elastic recoil of lung
and thorax

118. SPIROMETRY
 MEP
 Usually measured at maximal
inspiration (total lung capacity)
 Can be measured at FRC
 Recorded as a positive number in
cm H20 or mm Hg

119. SPIROMETRY
 MIP and MEP

120. SPIROMETRY
 MEP
Significance and Pathophysiology
 Healthy adults >80 to 100 cm H2O
 Decreased in:
 Neuromuscular disorders
 High cervical spine fractures
 Damage to nerves controlling
abdominal and accessory muscles of
inspiration

121. SPIROMETRY
 MEP
Significance and Pathophysiology
 A low MEP is associated with
inability to cough
 May complicate chronic bronchitis, cystic
fibrosis, and other diseases that result in
excessive mucus production

122. SPIROMETRY
 Airway Resistance (Raw)
 The drive pressure required to
create a flow of air through a
subject’s airway
 Recorded in cm H2O/L/sec
 When related to lung volume at the
time of measurement it is known as
specific airway resistance (SRaw)

123. SPIROMETRY
 Raw
 Measured in a
plethysmograph
as the patient
breathes
through a
pneumo-tachometer

124. SPIROMETRY
 Raw
 Criteria of Acceptability
 Mean of three or more acceptable
efforts should be reported;
individual values should be within
10% of mean

125. SPIROMETRY
 Airway Resistance (Raw)
Normal Adult Values
Raw 0.6 – 2.4 cm H2O/L/sec
SRaw 0.190 – 0.667 cm H2O/L/sec/L

126. SPIROMETRY
 Airway Resistance (Raw)
 May be increased in:
 Bronchospasm
 Inflammation
 Mucus secretion
 Airway collapse
 Lesions obstructing the larger airways
 Tumors, traumatic injuries, foreign bodies

127. SPIROMETRY
 Raw
Significance and Pathology
 Increased in acute asthmatic episodes
 Increased in advanced emphysema because of
airway narrowing and collapse
 Other obstructive disease, e.g., bronchitis may
cause increase in Raw proportionate to the
degree of obstruction in medium and small
airways

128. SPIROMETRY
 Airway Conductance (Gaw)
 A measure of flow that is generated
from the available drive pressure
 Recorded in L/sec/cm H2O
 Gaw is the inverse of Raw
 When related to lung volume at the
time of measurement it is known as
specific airway conductance (SGaw)

129. SPIROMETRY
 Gaw
 Measured in a
plethysmograph
as the patient
breathes
through a
pneumo-tachometer

130. SPIROMETRY
 Gaw
 Criteria of Acceptability
 Mean of three or more acceptable
efforts should be reported;
individual values should be within
10% of mean

131. SPIROMETRY
 Airway Conductance (Gaw)
Normal Adult Values
Gaw 0.42 – 1.67 L/sec/cmH2O
SGaw 0.15 – 0.20 L/sec/cm H2O/L

132. SPIROMETRY
 Airway Conductance (Gaw)
Significance and Pathology
SGaw Values <0.15 – 0.20
L/sec/cm H2O/L are consistent
with airway obstruction

133. Quiz Practice
Most clinical laboratories consider
two standard deviations from the
mean as the normal range when
determining predicted values since it
includes 95% of the normal
population.
a. False
b. Only for those individuals with lung
disease
c. This applies only to cigarette smokers
d. True

134. Quiz Practice
Vital capacity is defined as which of
the following?
a. The volume of gas measured from a slow,
complete exhalation after a maximal
inspiration, without a forced effort
b. The volume of gas measured from a rapid,
complete exhalation after a rapid maximal
inspiration
c. The volume of gas measured after 3 seconds of
a slow, complete exhalation
d. The total volume of gas within the lungs after a
maximal inhalation

135. Quiz Practice
Which of the following statements are
true regarding the acceptability criteria
for vital capacity measurement?
I. End-expiratory volume varies by less than 100
ml for three preceding breaths
II. Volume plateau observed at maximal inspiration
and expiration
III. Three acceptable vital capacity maneuvers
should be obtained; volume within 150 ml
IV. Vital capacity should be within 150 ml of forced
vital capacity in healthy individuals
a. I, II, and IV
b. II, III, and IV
c. III and IV
d. I, II, III, IV

136. Quiz Practice
Which of the following best
describes the Forced Vital Capacity
(FVC) maneuver?
a. The volume of gas measured from a slow,
complete exhalation after a maximal
inspiration, without a forced effort
b. The volume of gas measured from a slow,
complete exhalation after a rapid maximal
inspiration
c. The volume of gas measured after 3 seconds
of a rapid, complete exhalation
d. The maximum volume of gas that can be
expired when the patient exhales as forcefully
and rapidly as possible after maximal
inspiration

137. Quiz Practice
All of the following are true
regarding the acceptability
criteria of an FVC maneuver
EXCEPT?
a. Maximal effort, no cough or glottic
closure during the first second; no leaks
of obstruction of the mouthpiece
b. Good start of test; back extrapolated
volume less than 5% of the FVC or 150 ml
c. Tracing shows a minimum of 3 seconds of
exhalation
d. Three acceptable spirograms obtained;
two largest FVC values within 150 ml; two
largest FEV1 values within 150 ml

138. Quiz Practice
The FEV1 is the expired volume of
the first second of the FVC
maneuver.
a. True
b. False
c. Only when done slowly
d. Only when divided by the FVC

139. Quiz Practice
Which of following statements is
true regarding FEV1?
a. FEV1 may be larger than the FVC
b. FEV1 is always 75% of FVC
c. May be reduced in obstructive and
restrictive lung disease
d. Is only reduced in restrictive disease

140. Quiz Practice
The FEV1% is useful in
distinguishing between obstructive
and restrictive causes of reduced
FEV1 values
a. True
b. False
c. Only helps to distinguish obstructive
lung disease
d. Only helps to distinguish restrictive
lung disease

141. Quiz Practice
Which statements are true
regarding the FEV 1%, also known
as the FEV1/FVC?
I. A decreased FEV1/FVC is the hallmark of
obstructive disease
II. Patients with restrictive lung disease often
have normal or increased FEV1/FVC ratios
III. The presence of a restrictive disorder may
be suggested by a reduced FVC and a
normal or increased FEV1/FVC ratio
IV. A normal FEV1/FVC ratio is between 75%
- 85%
a. I and II
b. I, II and III
c. II, III and IV
d. I, II, III and IV

142. Quiz Practice
What test is
represented by the
graph to the right?
a. Forced Vital Capacity
b. Flow-Volume Loop
c. Slow Vital Capacity
d. Total Lung Capacity
Maneuver

143. Quiz Practice
What type of pulmonary disorder is
represented by the graph below?
a. Obstructive lung disease
b. Restrictive lung disease
c. Upper airway obstruction
d. Normal lung function
(The dotted lines represent the predicted values)

144. Quiz Practice
Which is true regarding Peak
Expiratory Flow (PEF)?
I. Primarily measures large airway function
II. Is a recognized means of monitoring
asthma
III. Serial measurements of PEF are used a
guide to treat asthma
IV. When less than 50% of personal best, it is
an indication that immediate treatment is
required
a. I only
b. II and III
c. II, III, and IV
d. I, II, III, and IV

145. Quiz Practice
MVV is decreased in patients with
which of the following disorders?
I. Moderate to severe obstructive lung
disease
II. Weak or with decrease endurance
III. Neurological defects
IV. Paralysis or nerve damage
a. I and IV
b. II and III
c. III and IV
d. I, II, III, and IV

146. Quiz Practice
Spirometry before and after
bronchodilator therapy is used to
determine which of the following?
a. Reversibility of airway obstruction
b. The severity of restrictive disorders
c. The rate at which CO diffuses through the lung
into the blood
d. If the patient has exercised induced asthma

147. Quiz Practice
What is the minimum amount of
time between administration of
bronchodilator therapy and repeat
pulmonary function testing?
a. 5 minutes
b. 10 minutes
c. 30 minutes
d. 60 minute

148. Quiz Practice
Bronchodilation is considered
significant when which of the
following occurs?
a. FEV1/FVC increases by 12%
b. SGaw increases by 12%
c. FVC and/or FEV1 increases by 12% and 150 ml
d. DLco increases by 12%

149. Quiz Practice
Which of the following is true
regarding Maximal Inspiratory
Pressure (MIP)?
I. Primarily measures inspiratory muscle
strength
II. Measures airway resistance during
inspiration
III. Is decreased in patients with neurological
disease
IV. Often used in the assessment of
respiratory muscle function in patients
who need ventilatory support
a. I, II, and III
b. I, III, and IV
c. II and III
d. II, III, and IV

150. Quiz Practice
Airway resistance (Raw) is the
drive pressure required to create a
flow of air through a subject’s
airway.
a. True
b. False
c. Only in patients with COPD
d. Only in patients with restrictive
disorders

151. Quiz Practice
Airway resistance may be increased
in which of the following patients?
I. Purely restrictive lung disorders
II. Acute asthmatic episodes
III. Mucus secretion
IV. Lung compliance changes
a. I only
b. I and IV
c. II and III
d. I, II, III, and IV

152. Quiz Practice
Airway Conductance (Gaw) is a
measure of flow that is generated
from the available drive pressure.
a. True
b. False
c. Only in patients with COPD
d. Only in patients with restrictive
disorders

153. Quiz Practice
A patient’s pulmonary function
tests reveal the following:
Actual Predicted %Predicted
 FVC 4.01 L 4.97 L 81
 FEV1 2.58 L 3.67 L 56
 FEV1% 51 >75 _
Select the correct interpretation
a. Restrictive pattern
b. Obstructive pattern
c. Inconclusive
d. Normal

154. Quiz Practice
A patient’s pulmonary function tests reveal
the following:
Actual Predicted %Predicted
FVC 3.75 L 4.97 L 75
FEV1 2.80 L 3.67 L 76
FEV1% 75 >/=75 _
Select the correct interpretation
a. Restrictive pattern
b. Obstructive pattern
c. Inconclusive
d. Normal