Intern Boot Camp Dyspnea

1. Intern Boot CampDyspnea Joshua Sapkin, MD Associate Program Director LAC+USC Internal Medicine Residency Program

2. Lecture Goals • Review the various etiologies of dyspnea by organ system • Review the most common cardiac and pulmonary etiologies of hypoxia • Utilize the A:a gradient to determine the correct pathophysiology responsible for a patient’s hypoxia • Appreciate the systematic approach that should be taken to evaluate a dyspneic patient • Appreciate the roles, including limitations, of various diagnostic tests

3. Etiologies • Cardiac • Pulmonary • Mixed cardiac and pulmonary • Psychiatric (e.g. anxiety, panic disorder)

4. Cardiac Etiologies • Congestive heart failure • Systolic dysfunction • Diastolic dysfunction • Valvular heart disease • Hypertrophic obstructive cardiomyopathy • Cardiac tamponade • Tension pneumothorax • Intracardiac right to left shunting • Arrhythmias • Bradydarrhythmias • Tachyarrhythmias

5. Pulmonary Etiologies • V/Q mismatch • Shunt • Diffusion barrier • Hypoventilation • Altitude

6. V/Q Mismatch • The most common pathophysiology leading to hypoxemia. • Atelectasis • Chronic bronchitis • Pneumonitis • Pneumothorax • Pleural effusion • Pulmonary edema

7. Shunt • Pulmonary embolus • Acute lung injury • ARDS • Hepatopulmonary syndrome • Right to left intracardiac shunts

8. Hypoventilation • Opiate analgesics • Benzodiazepines • Barbiturates • Asthma • Emphysema • Central disorders

9. Diffusion Barriers • Interstitial lung disease • Medication induced, e.g. nitrofurantoin, sulfasalazine, amiodarone, • Illicit drugs, e.g. heroin • Cryptogenic organizing pneumonia • Lymphocytic interstitial pneumonia • Non-specific interstitial pneumonitis • Lymphangioleiomyomatosis • Connective tissue disease • Sarcoidosis • Infectious • Hypersensitivity pneumonitis

10. Other Etiologies • Severe kyphoscoliosis • Neuromuscular disorders, e.g. myasthenia gravis • Altitude • Carbon monoxide poisoning • Severe anemia (usually fairly acute)

11. Question 1 Which of the pathophysiologies responsible for dyspnea is not associated with an increased A:a gradient: • V/Q mismatch • Shunt • Diffusion barrier • Hypoventilation

12. Alveolar:arterial gradient A-a gradient = predicted pO2 – observed PO2 PAO2 = (FIO2 X 713) – (PaCO2/0.8) at sea level PAO2 = 150-(PaCO2/0.8) at sea level on room air “Poor man’s” A:a gradient (ABG must be performed on room air): 140-pCO2-pO2 Normal= {Age÷ 4} ₊ 4

13. Case 1 The nurse calls you because your patient who had a left subclavian central venous catheter placed 1 hour ago is complaining of shortness of breath. The patient is a 55 year old man who was admitted for left leg cellulitis that was refractory to oral antibiotics.

14. Case 1 Which of the following diagnoses is most likely? A. Pneumocystis Jaroveci pneumonia B. Pulmonary embolus C. Intrapulmonary hemorrhage D. Pneumothorax

15. Case 1 Upon arriving at the patient’s bedside, you find him in mild respiratory distress. Vital signs: Blood Pressure: 144/82. Heart rate 100. Respirations: 24. Temperature: 98.2. Oxygen saturation 94% on room air. P.E. HEENT: Anicteric. No conjunctival pallor. Neck: No JVD. Cardiac: Tachycardic. Chest: Trachea midline. Lungs clear to auscultation Abdomen: Non-tender, non-distended. No organomegaly.

16. Be careful of the pulse oximeter

17. Case 1 What is the next best step in the management of this patient? A. Chest X-ray B. V/Q scan C. HRCT of the lungs D. Echocardiogram

18. Case 1

19. Case 1 Why are vital signs called “vital” signs? • They are a necessary component of the medical documentation in order to bill health insurances (vital for reimbursement) • They are important clues to the patient’s diagnosis (vital for establishing a diagnosis). • The nurses consider them essential pieces of information before paging a physician (vital for paging a physician) • They reflect physiologic processes that are essential to sustaining life.

20. Case 1 All of the following measures would be appropriate a this time EXCEPT: A. Check the patient’s blood pressure in the supine and sitting position. B. Ensure the patient has two large bore peripheral IV sites. C. Contact the GI fellow who performed the procedure. D. STAT General Surgery consult E. Ask the nurse if he/she would like to join you for a drink at Barbara’s Brewery after work.

21. Case 1

22. Case 2 The nurse pages you because your patient has a respiratory rate of 6 and an oxygen saturation of 85% on room air. He is a 42 year-old man with history of IVDU who was admitted for multiple abscesses and cellulitis affecting both upper extremities. He had been off the ward for 3 hours. His nurse noticed that he seemed under the influence of a substance upon returning to his room about 1 hour ago. P.E. Height: 5’ 9” Weight: 140 lbs. Vital Signs: Blood pressure: 100/62. Heart Rate: 110 Respirations: 6. Temperature: 99.0. Pulse oximeter 85% on room air. General: The patient does not respond to verbal or painful stimuli. HEENT: Pinpoint pupils. Sluggish response to light. There is dried food at the borders of the mouth. Neck: No JVD. Tachycardic . No murmurs, rubs or gallops. Chest: No deformities. There are decreased breath sounds over the right lower lung field.

23. Case 2 The next best step in the management of this patient is: A. Naloxone intravenously B. Sternal rub C. Call the airway team D. Ventilate the patient using a bag valve mask (BVM).

24. Case 2 The ABG prior to hyperventilating the patient revealed the following: 7.58/60/58/24/85% What is the calculated A:a gradient? What is the expected calculated A:a gradient?

25. Case 2 What is the calculated A:a gradient? 140-pCO2-pO2 = 140-60-58=22 What is the expected calculated A:a gradient? Age 42: [42÷4] ₊ 4= 14

26. Case 2

27. Case 3 A 67 year-old woman is found to have an oxygen saturation of 88% by her nurse 4 days after undergoing bilateral total knee arthroplasties. Vital Signs: BP 120/72. Pulse 100. Respirations 20. Temperature 99.4. Exam is significant for inspiratory rales over bilateral bases. ABG: 7.46/35/64/20/88%

28. Case 3 Which piece of data provides the best evidence that this woman does not have a partial small bowel obstruction? A. Her cholecystectomy was performed 20 years ago. B. The timing and duration of her symptoms C. The results of her abdominal series D. Her abdominal exam

29. Case 3

30. Case 3 Which of the following statements is true regarding pulmonary emboli? A. V/Q scan is the gold standard for establishing this condition. B. A confirmatory CT angiogram should be performed before starting anticoagulation. C. The D-dimer test is a highly sensitive and specific test for this condition. D. The ECG usually demonstrates evidence of right heart strain during an acute pulmonary embolus.

31. Case 4 A 75 year old woman with essential hypertension left ventricular hypertrophy (hypertensive heart disease), diabetes and long history of smoking undergoes surgical repair of a 7 cm aneurysm of the descending aorta. She develops hypoxia on post-operative day #1 requiring 4 liters of oxygen via nasal cannula to maintain her oxygen saturations above 90%. Exam is significant for elevated jugulovenous pressure, scattered expiratory wheezes, decreased breath sounds over the bases and 1+ pitting edema over bilateral lower extremities.

32. Case 4 Which piece of history is most pertinent to establishing the cause of her hypoxia? A. Her net fluid intake/output over the past 24 hours. B. The number of pack-years she has smoked in her lifetime. C. The length of the surgery. D. The total amount of opiate analgesics administered since surgery.

33. Case 4 All of the following diagnostics can help distinguish between a pulmonary and cardiac cause of dyspnea EXCEPT: A. B type natriuretic peptide B. Chest x-ray C. Oxygen Extraction Ratio VO2/DO2 x 100 D. Pulmonary capillary wedge pressure