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Evaluation of Dyspnea. Variable Definitions Of Dyspnea. Unpleasant or uncomfortable respiratory sensations Difficult, labored, uncomfortable breathing Awareness of respiratory distress The sensation of feeling breathless or air hunger An uncomfortable sensation of breathing
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Variable Definitions Of Dyspnea • Unpleasant or uncomfortable respiratory sensations • Difficult, labored, uncomfortable breathing • Awareness of respiratory distress • The sensation of feeling breathless or air hunger • An uncomfortable sensation of breathing • ATS guidelines: subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity ATS. AJRCCM, 1999.
Variation In Symptoms of Dyspnea by Condition Manning. NEJM, 1995.
Respiratory Control Systems • Designed to maintain gas exchange equilibrium and acid base status • Abnormalities in this system -> dyspnea-> severe patient distress
Mechanisms Of Dyspnea: Respiratory Center Output • Chemoreceptors • Peripheral: carotid bodies, aortic arch • Sense changes in PO2, acidosis, hypercapnea • Central: medulla • pH and PCO2 changes • Hypercapnea • Potent stimulus of dyspnea • Hypoxia • Less potent stimulus than hypercapnea Manning. NEJM, 1995.
Mechanisms Of Dyspnea: Stimulation Of Mechanoreceptors • Mechanoreceptors • Upper airway • Pulmonary receptors • Limitations of movement exacerbate dyspnea • The sensation of dyspnea varies with activation • Chest wall receptors • Restricted motion exacerbates dyspnea • Redundant to pulmonary receptors Nausherwan. Chest, 2010.
Other Mechanisms Of Dyspnea • Mechanical loading • Changes in airway resistance, pulmonary or chest wall compliance • Neuromechanical dissociation • Air flow not equal to expected results of brain output • Impaired oxygen utilization or delivery • Anemia • Increased CO -> EDP-> pulmonary edema • Localized acidosis or resp muscle fatigue • Deconditioning • Poor cardiac and peripheral efficiency, early anaerobic metabolism and acidosis
Structural Approach • Respiratory • Controller: depth and rate of breathing • Ventillatory pump: movement of gas in and out of the alveolous • Gas exchanger: pulmonary vasculature, alveoli • Cardiac • Anemia • Deconditioning • Heart failure
Most Common Causes of Dyspnea • Asthma • COPD • ILD • Cardiac disease
Differential Diagnosis of Dyspnea • Cardiac • Heart failure • Coronary artery disease • Arrhythmia • Pericardial disease • Valvular heart disease • Pulmonary hypertension
Diagnosis of Dyspnea • Pulmonary • Chronis obstructive pulmonary disease • Asthma • Interstitial lung disease • Pleural effusion • Malignancy • Bronchiectasis
Diagnosis of Dyspnea • Non-cardiac/Non-pulmonary • Thromboembolic disease • Psychogenic • Deconditioning • Obesity • Anemia • GERD • Metabolic conditions • Cirrhosis • Thyroid disease • Neuromuscular • Chest wall • Upper airway
Approach To The Patient • History and physical • EKG • Echocardiogram • CXR/CT scan • Spirometry • Cardiopulmonary exercise testing
Differentiating Heart vs Lung Etiology • 1586 patients presenting with dyspnea • No clear heart failure Maisel. NEJM, 2002.
BNP Is Useful to Differentiate Heart Failure From Other Dyspnea Maisel. NEJM, 2002.
Case 1 • A 30 year old woman presents with progressive exercise tolerance for the last 3 months. She ran a marathon at age 26, but now has shortness of breath walking up 1 flight of stairs. She denies chest pain, orthopnea or PND but has intermittent mild ankle edema.
Case1 • Her blood pressure is normal and her exam is unremarkable. Her EKG and CXR are shown. What test should be ordered next? • A treadmill stress test • Pulmonary function testing • A blood test for BNP • A CT scan of the chest • An echocardiogram
Case 1 • What test should be ordered next? • A treadmill stress test • Pulmonary function testing • A blood test for BNP • A CT scan of the chest • An echocardiogram
Case 1 • An echocardiogram is performed.
Case 1 • The next best step is to: • Start sildenafil 20 mg TID • Send the patient for a right heart catheterization • Send tests for rheumatologic disease • Start an ACE Inhibitor
Most commonly associated with left sided heart failure Pulmonary hypertension is another common cause Right Sided Heart Failure
Patients Die From Right Heart Failure www.clarian.org/ADAM/doc/HealthIllustratedEncyclopedia/2/18131.htm www.mdconsult.com/das/patient/body/196982233-3/0/10041/35062.html
Pulmonary arterial hypertension Idiopathic Heritable Drug/toxin induced Associated (HIV, CTD, CHD, schistosomiasis) I′. PVOD, PCH PH from left heart disease Systolic dysfunction Diastolic dysfunction Valvular disease PH from lung disease or hypoxemia ILD COPD OSA Altitude CTEPH Multifactorial Hematologic Systemic (sarcoid, vasculitis) Metabolic (glycogen storage) Other (tumor) WHO Classification of PH
Localization of Abnormalities University of Michigan website Dijke. Nature Reviews Molecular and Cell Biology. 2007.
Pre-symptomatic/ Compensated Symptomatic/ Decompensating Declining/ Decompensated CO Symptom Threshold PAP Right Heart Dysfunction PVR PAP Time CO = PVR Progression of PAH
Targets for Therapies in Pulmonary Arterial Hypertension Humbert. NEJM, 2004.
Case 2 • A 68 year old HTN, diabetic female presents with progressive shortness of breath over the last 5 years. She can walk about 2 blocks before needing to rest.
Case 2 • The examination shows tachycardia and a normal blood pressure. There are bibasilar crackles and an S3 on exam.
Case 2 • There was trace LE edema. The EKG shows LVH. An echocardiogram shows LVH and severe diastolic dysfunction.
Case 2 • The next best step is: • A nuclear stress test • Aggressive blood pressure management • A coronary angiogram • Aggressive management of diabetes
Diastolic Heart Failure • Nearly ½ of all patients with heart failure • 65% 5 year mortality Shah. JAMA, 2008.
Typical Features Of Patients With Diastolic Heart Failure • Female: 62-66% • Elderly: mean age 72-74 • Comorbidities • CAD 36-53% • HTN 55-77% • AF 32-41% • DM 32-45% • CKD 23-26% • Obesity • Anemia
Mortality In Diastolic Heart Failure Is High Owan. NEJM, 2006.
Diastolic Heart Failure: Elevated LV Filing Pressures Nagueh. JASE, 2009.
What Does DHF Look Like On Echo? Nagueh. JASE, 2009.
Treatment • Treatment of comorbidities