Workup of Dyspnea - Pulmonary
Joel A Wirth, MD, FCCP
Director, Division of Pulmonary and Critical Care Medicine, Maine Medical Center
Staff Physician, Chest Medicine Associates
Case 2
48 year old woman with unexplained exertional dyspnea.
Age 9: CHD (ASD with endocardial cushion defect) with a late
repair at Boston Children’s Hospital
Age 10: Mitral Valve replacement ( porcine)
Age 13: Mechanical valve.
Age 40: MV re-do with a TV ring and pacemaker placement.
Worsening DOE for the past 8 years. She is a lifelong nonsmoker,
has history of mild asthma. Episodes of daily chest tightness are
very severe, aggravated climbing stairs, supine position and
humidity. Associated symptoms include dry cough, fatigue, lower
extremity edema and occasional wheezing.
Case 2 (Continued)
Past Medical/Surgical History
Congenital heart disease s/p ASD and MV repair, TV ring
Secondary pulmonary hypertension
Bradycardia s/p pacemaker placement
Right hemidiaphragm paralysis
(phrenic nerve injury) 2005
Diastolic heart failure
Hepatitis C
Asthma
Medications
VITAMIN B COMPLEX, VALIUM, COUMADIN, CITALOPRAM,
ATIVAN
Social History
Education and Employment: Radiation therapist. Never smoker.
Case 2 (Continued)
PHYSICAL EXAMINATION
Vital Signs
P
78
Physical Exam
Constitutional
Head / Face
ENT
Respiratory
Cardiovascular
Abdomen
Back / Spine
Musculoskeletal
Extremities
Neurological
Psychiatric
RR BP
SpO2
16 104/68 97% on RA
Weight kg/lb
59.320/130.8
BMI
21.43
No apparent distress. Thin and well developed.
Normocephalic.
Normal. No mucosal lesions.
Normal to inspection and palpation. Lungs CTA.
Right hemidiaphragm diminished excursion to percussion.
RRR. Crisp MV Prosthetic HS. No MRG.
Soft, non-tender without organomegaly or masses.
No kyphosis or scoliosis.
No skeletal tenderness or joint deformity.
No edema or cyanosis, no clubbing.
Alert and oriented.
No anxiety or depression.
Our Patient: Resting Echocardiogram
Basic Workup of Exertional Dyspnea
Lung Disease
Airways disease
Interstitial Lung Disease
Neuromuscular Disease
Vocal Cord Dysfunction
PFTs
Heart Disease
Myocardial Disease (Systolic, Diastolic)
Valvular Heart Disease
Coronary Artery Disease
EKG
Chest Imaging (CXR, CT)
Methacholine Challenge Testing
Echocardiography
BNP
Pulmonary Vascular Disease
(Pulmonary Hypertension, PE)
Echocardiography, CTPA, V/Q
Metabolic Disease
Anemia
Thyroid Disease
CBC, TFTs
Deconditioning, Anxiety
Exclusion
Our Differential Diagnosis for her Dyspnea:
1. Lung Disease
• Airways disease (Asthma)
• Interstitial Lung Disease
• Vocal Cord Dysfunction
• Thoracic Cage Abnormality (Paralyzed right hemidiaphragm)
2. Heart Disease
• Left ventricular diastolic dysfunction
• Valvular Heart Disease
• Pacemaker Malfunction
• Coronary Artery Disease
3.
4.
5.
6.
7.
8.
Pulmonary Vascular Disease (Pulmonary Hypertension, PE)
Peripheral (Myopathy/Malnutrition/Neuromuscular dysfunction)
Anemia
Thyroid Disease
Deconditioning
Perception/Anxiety
Evaluation of Unexplained Dyspnea
Balady G J et al. Circulation. 2010;122:191-225
Does Anemia cause dyspnea and
exercise limitation?
Cote et al., Eur Resp J. 2007 29:923-929
Thyroid Disease: Mechanisms for
Exertional Dyspnea
Hyperthyroidism:
Reduced Heart Rate Reserve
Slower Heart Rate and BP Recovery
Hypothyroidism:
Impaired oxygen metabolism
Reduced maximal Heart Rate
Reduced maximal Ventilation
Causes of dyspnea as assessed by Spirometry
Echocardiography, & EKG in 129 Danish Subjects
Only 69% of
patients were
diagnosed by
these 3 tests
* Heart Disease
defined as AFib,
LV systolic
dysfunction or
valve disease
† Lung Disease
defined as
FEV1% < 70%
‡ Obesity
defined as
BMI > 30 kg/m2
Pedersen et al., Int J Clin Pract, 2007, 61, 9, 1481–1491
Why perform exercise testing for
exertional dyspnea?
• Cardiopulmonary measurements obtained at rest
may not reliably reflect functional capacity or limitations
• Determine if dyspnea is physiologic or pathologic
• Determine cause of limitation: cardiac, pulmonary, or peripheral
Types of Exercise Tests
• 6-min walk test
 Submaximal
• Shuttle walk test
 Incremental, maximal, symptom-limited
• Exercise bronchoprovocation
• Exertional oximetry
• Cardiac stress test
• Exercise echocardiography
• Cardiopulmonary Exercise Testing (CPET)
What can CPET do for YOU?
1.
Evaluation of dyspnea
•
•
2.
Pulmonary rehabilitation
•
•
3.
4.
5.
Distinguish Cardiac vs Pulmonary vs Peripheral limitation
Detection of exercise-induced bronchospasm (EIB)
•
•
•
•
•
Exercise intensity/prescription
Response to participation
Pre-op evaluation and risk stratification
Lung resection
Prognostication of life expectancy
Congestive Heart Failure/Cardiomyopathy
Pulmonary Arterial Hypertension
Cystic Fibrosis
Assess response to therapy
COPD, Asthma, PAH
6.
Disability determination
7.
Fitness evaluation
Internal and External Respiration
What is CPET?
• Symptom-limited exercise test
• Measure workload, ventilation,
SpO2, HR, Blood Pressure, EKG,
oxygen consumed and carbon
dioxide expired, respiratory
exchange ratio (RER)
• Allows calculation of peak oxygen
consumption, anaerobic threshold
• Identifies general cause of exercise
limitation and if limit is normal or
abnormal
Contraindications to CPET
•
•
•
•
•
•
•
•
•
•
•
•
Acute MI
Unstable angina
Unstable arrhythmia
Acute endocarditis, myocarditis, pericarditis
Syncope
Severe, symptomatic AS
Uncontrolled CHF
Acute PE, DVT
Respiratory failure
Uncontrolled asthma
SpO2 < 88% on RA
Significant non-cardiopulmonary disorder that may affect
or be adversely affected by exercise
• Psychiatric/cognitive impairment limiting cooperation
Relative Contraindications to CPET
•
•
•
•
•
•
•
•
•
•
Left main or 3-V CAD
Severe arterial HTN (>200/120)
Significant pulmonary HTN
Tachyarrhythmia, bradyarrhythmia
High degree AV block
Hypertrophic cardiomyopathy
Electrolyte abnormality
Moderate stenotic valvular heart disease
Advanced or complicated pregnancy
Orthopedic impairment
General Mechanisms of Exercise
Limitation
•
Pulmonary
– Ventilatory
•
•
Peripheral
– Respiratory muscle dysfunction
– Inactivity/Atrophy/ Malnutrition
– Impaired gas exchange
– Neuromuscular dysfunction
– Reduced oxidative capacity of
Cardiovascular
– Reduced stroke volume
skeletal muscle
– Abnormal HR response
•
Perceptual
– Circulatory abnormality
•
Motivational
– Blood abnormality
General Mechanisms of Exercise
Limitation
•
Pulmonary
– Ventilatory
•
•
Peripheral
– Respiratory muscle dysfunction
– Inactivity/Atrophy/ Malnutrition
– Impaired gas exchange
– Neuromuscular dysfunction
– Reduced oxidative capacity of
Cardiovascular
– Reduced stroke volume
skeletal muscle
– Abnormal HR response
•
Perceptual
– Circulatory abnormality
•
Motivational
– Blood abnormality
Ventilatory
Limits
Exercise:
Figure 7.
Flow-volumeto
loops.
Expiratory Flow Rates and MVV
Balady G J et al. Circulation. 2010;122:191-225
Figure 6. V̇o2
Oxygenation Limits
tokinetics.
Exercise: Oxygen
Deficit and Debt
Balady G J et al. Circulation. 2010;122:191-225
Use of the “V-Slope” Method to detect the
Ventilatory (Anaerobic) Threshold, VT (AT)
Balady G J et al. Circulation. 2010;122:191-225
CPET Pulmonary Parameters
1. O2 consumed = VO2
2. CO2 produced = VCO2
3. Respiratory Exchange Ratio (RER) = CO2 produced / O2 consumed=VCO2 / VO2
4. Maximum Minute Ventilation (Vemax) = measured exhaled volume (L/min)
5. Maximum Voluntary Ventilation = Peak Ventilation in L/min
•
Normal = 35 to 41 times FEV1
6. Breathing Reserve = (Predicted MVV – Vemax /Predicted MVV) x 100%
•
Normal > 30%
7. Ventilatory equivalent for CO2 = Ve / VCO2
•
•
Efficiency of ventilation, normal is < 30 and improves during exercise
Liters of ventilation to eliminate 1 L of CO2
8. Ventilatory equivalent for O2 = Ve / VO2
• Liters of ventilation per L of oxygen uptake
General Mechanisms of Exercise
Limitation
•
Pulmonary
– Ventilatory
•
•
Peripheral
– Respiratory muscle dysfunction
– Inactivity/Atrophy/ Malnutrition
– Impaired gas exchange
– Neuromuscular dysfunction
– Reduced oxidative capacity of
Cardiovascular
– Reduced stroke volume
skeletal muscle
– Abnormal HR response
•
Perceptual
– Circulatory abnormality
•
Motivational
– Blood abnormality
Cardiac Limits to Exercise:
Maximum HR by Age
Oxygen Consumption: Fick Equation
• Fick Equation:
Q = VO2 / C(a-v)O2
VO2 = Q x 1.34(SaO2 - SvO2)(Hgb)
VO2 = SV x HR x 1.34(SaO2 - SvO2)(Hgb)
Heart disease
Heart disease
Muscle disease
Deconditioning
Lung disease
Anemia
CPET Cardiac Parameters
1. Maximum Heart Rate = HRmax
2. Heart Rate Reserve =
(Predicted HRmax – HRmax)/Predicted HRmax x 100%
Normal is < 15%
3. Heart Rate Response (HRR) =
Change in HR/Change in VO2
4. Oxygen Pulse = VO2 / HR ≈ SV
Fick Equation:
VO2 = SV x HR x C(a-v)O2
VO2 / HR = SV x C(a-v)O2
Oxygen Pulse: “. . .the amount of oxygen consumed by the body from the blood of
one systolic discharge of the heart.” Henderson and Prince. Am J Physiol 35:106, 1914
Abnormal Exercise Responses during CPET
Balady G J et al. Circulation. 2010;122:191-225
CPET Patterns of Cardiac and Pulmonary
Disease during Exercise
CARDIAC
MEASUREMENT
PULMONARY
SYMBOL
FINDINGS
Maximum Oxygen Consumption
VO2max
Maximum Heart Rate
HRmax
Reduced
Reduced
> 85% predicted < 85% predicted
Breathing Reserve
BR
> 30%
< 15%
Oxygen Saturation
SaO2
> 90%
< 90%
< 12 ml/beat
> 12 ml/beat
Oxygen Pulse VO2max/HR
Ventilatory Equivalent for CO2
VE/VCO2
< 30
> 30
Anaerobic Threshold/VO2max
AT (or VT)
< 40%
> 40%
Adapted from: Balady G J et al. Circulation. 2010;122:191-225
Our Patient
Our Patient: Pulmonary Function
Parameter
Patient
%Predicted
FVC
2.66L
69%
FEV1
2.24L
74%
FEV1%
84%
TLC
4.24L
79%
FRC
2.91L
96%
RV
1.57L
84%
DLCO
15.9
62%
Our Patient: CPET
Parameter
Patient
Normal
VO2max
22.3 ml/min/kg
30.2 (74%)
RER
1.1
>1.0
HRmax
98 beats/min
168 (58%)
VO2max/HR
13.9 ml/beat
10.5 (132%)
BR
(87-38)/87 = 56%
> 30%
VE/VCO2
27
< 30
SaO2
96%
> 92%
AT (or VT)
69%
> 40%
Our Patient: CPET
87
168
12
Our Differential Diagnosis for her Dyspnea:
1. Lung Disease
• Airways disease (Asthma)
• Interstitial Lung Disease
• Vocal Cord Dysfunction
• Thoracic Cage Abnormality (Paralyzed right hemidiaphragm)
2. Heart Disease
• Left ventricular diastolic dysfunction
• Valvular Heart Disease
• Pacemaker Malfunction
• Coronary Artery Disease
3.
4.
5.
6.
7.
8.
Pulmonary Vascular Disease (Pulmonary Hypertension, PE)
Peripheral (Myopathy/Malnutrition/Neuromuscular dysfunction)
Anemia
Thyroid Disease
Deconditioning
Perception/Anxiety