Upload
jamie-tetlow
View
222
Download
1
Tags:
Embed Size (px)
Citation preview
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 248 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.
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 HistoryCongenital heart disease s/p ASD and MV repair, TV ring
Secondary pulmonary hypertensionBradycardia s/p pacemaker placement Right hemidiaphragm paralysis
(phrenic nerve injury) 2005Diastolic heart failure
Hepatitis CAsthma
MedicationsVITAMIN B COMPLEX, VALIUM, COUMADIN, CITALOPRAM, ATIVAN
Social History Education and Employment: Radiation therapist. Never smoker.
PHYSICAL EXAMINATION
Vital Signs P RR BP SpO2 Weight kg/lbBMI78 16 104/6897% on RA 59.320/130.8 21.43
Physical ExamConstitutional No apparent distress. Thin and well developed.Head / Face Normocephalic. ENT Normal. No mucosal lesions.Respiratory Normal to inspection and palpation. Lungs CTA.
Right hemidiaphragm diminished excursion to percussion.Cardiovascular RRR. Crisp MV Prosthetic HS. No MRG.Abdomen Soft, non-tender without organomegaly or masses.Back / Spine No kyphosis or scoliosis.Musculoskeletal No skeletal tenderness or joint deformity. Extremities No edema or cyanosis, no clubbing.Neurological Alert and oriented. Psychiatric No anxiety or depression.
Case 2 (Continued)
Our Patient: Resting Echocardiogram
Basic Workup of Exertional Dyspnea
Lung Disease Airways disease Interstitial Lung DiseaseNeuromuscular Disease Vocal Cord Dysfunction
PFTs
Chest Imaging (CXR, CT)
Methacholine Challenge
Testing
Heart DiseaseMyocardial Disease (Systolic, Diastolic)Valvular Heart DiseaseCoronary Artery Disease
EKG
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. Pulmonary Vascular Disease (Pulmonary Hypertension, PE)
4. Peripheral (Myopathy/Malnutrition/Neuromuscular dysfunction)
5. Anemia6. Thyroid Disease7. Deconditioning8. 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 RateReduced maximal Ventilation
Causes of dyspnea as assessed by Spirometry Echocardiography, &
EKG in 129 Danish SubjectsOnly 69% of patients were diagnosed by these 3 tests
* Heart Disease defined as AFib, LV systolicdysfunction 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
• Distinguish Cardiac vs Pulmonary vs Peripheral limitation
• Detection of exercise-induced bronchospasm (EIB)
2. Pulmonary rehabilitation• Exercise intensity/prescription• Response to participation
3. Pre-op evaluation and risk stratification• Lung resection
4. Prognostication of life expectancy• Congestive Heart Failure/Cardiomyopathy• Pulmonary Arterial Hypertension• Cystic Fibrosis
5. 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
– Respiratory muscle
dysfunction
– Impaired gas exchange
• Cardiovascular
– Reduced stroke volume
– Abnormal HR response
– Circulatory abnormality
– Blood abnormality
• Peripheral
– Inactivity/Atrophy/
Malnutrition
– Neuromuscular
dysfunction
– Reduced oxidative
capacity of skeletal muscle
• Perceptual
• Motivational
General Mechanisms of Exercise Limitation
• Pulmonary
– Ventilatory
– Respiratory muscle
dysfunction
– Impaired gas exchange
• Cardiovascular
– Reduced stroke volume
– Abnormal HR response
– Circulatory abnormality
– Blood abnormality
• Peripheral
– Inactivity/Atrophy/
Malnutrition
– Neuromuscular
dysfunction
– Reduced oxidative
capacity of skeletal muscle
• Perceptual
• Motivational
Figure 7. Flow-volume loops.
Balady G J et al. Circulation. 2010;122:191-225
Ventilatory Limits to Exercise: Expiratory Flow Rates and
MVV
Figure 6. V̇3 o2 kinetics.
Balady G J et al. Circulation. 2010;122:191-225
Oxygenation Limits to Exercise: Oxygen Deficit and
Debt
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
– Respiratory muscle
dysfunction
– Impaired gas exchange
• Cardiovascular
– Reduced stroke volume
– Abnormal HR response
– Circulatory abnormality
– Blood abnormality
• Peripheral
– Inactivity/Atrophy/
Malnutrition
– Neuromuscular
dysfunction
– Reduced oxidative
capacity of skeletal muscle
• Perceptual
• Motivational
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 diseaseDeconditioning
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
Adapted from: Balady G J et al. Circulation. 2010;122:191-225
MEASUREMENTSYMBO
L
CARDIACPULMONAR
Y
FINDINGS
Maximum Oxygen
ConsumptionVO2max Reduced Reduced
Maximum Heart Rate HRmax
> 85%
predicted
< 85%
predicted
Breathing Reserve BR > 30% < 15%
Oxygen Saturation SaO2 > 90% < 90%
Oxygen PulseVO2max/
HR
< 12
ml/beat
> 12
ml/beat
Ventilatory Equivalent
for CO2VE/VCO2 < 30 > 30
Anaerobic
Threshold/VO2max
AT (or
VT)< 40% > 40%
Our Patient
Our Patient: Pulmonary FunctionParamet
er
Patient %Predict
ed
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
Paramet
er
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
168
87
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. Pulmonary Vascular Disease (Pulmonary Hypertension, PE)
4. Peripheral (Myopathy/Malnutrition/Neuromuscular dysfunction)
5. Anemia6. Thyroid Disease7. Deconditioning8. Perception/Anxiety