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Patient with Hypercapneic Respiratory Failure54 year old male smoker (1 ppd x 40 y)Increasing dyspnea, productive coughFHx and PMHx unremarkableMeds: nil

Physical exam: RR 28, HR 110, bilateral wheezes, obese (height 176 cm, wt 161kg, BMI 52)Blood work remarkable for WBC 20, bands 12%, neuts 63%, Hgb 160 g/L

Patient with Hypercapneic Respiratory FailureQ1: How would you interpret the CXR?Answer (Q1)

Patient with Hypercapneic Respiratory FailureABG: on 6 lpm in EDPO2 80PCO2 83pH 7.16HCO3 32sat 95%.Na 140Cl 100Q2: How would you interpret the ABG?Answer (Q2)

Patient with Hypercapneic Respiratory FailureQ3: With the information provided so far, what is your diagnosis?Acute exacerbation of COPDObesity Hypoventilation syndromeObstructive Sleep ApneaNeuromuscular diseaseAnswer (Q3)

Patient with Hypercapneic Respiratory FailureRepeat ABG after several days of NIMV shows the following on 4 lpm: PO2 69, PCO2 51, pH 7.42, HCO3 30.Q4: What is the next investigation that you would perform?CT chestPFTLevel I sleep studyEMG and nerve conduction studiesAnswer (Q4)

Patient with Hypercapneic Respiratory FailureQ5: How would you interpret the PFT?Obstructive defect with partial reversibilityObstructive defect with no reversibilityRestrictive defectnormalAnswer (Q5)

Patient with Hypercapneic Respiratory FailureQ6: In the context of a restrictive defect, how do you interpret the low DLCO adjusted for VA in this setting?Interstitial lung disease is causing the restrictive defectAn extrapulmonary problem is causing the restrictive defectAn extrapulmonary problem is causing the restrictive defect, complicated by a lung parenchymal problemI give up trying to understand DLCO adjusted for VA

Patient with Hypercapneic Respiratory FailureDLCO adjusted for VA in the setting of a restrictive defectExtrapulmonary cause of restrictive defect neuromuscular disease chest wall abnormality (including obesity) pleural thickening or effusion abdominal distensionPulmonary cause of restrictive defect interstitial lung disease extrapulmonary cause complicated by a co-existing lung problem (eg. atelectasis, scarring from recurrent aspiration, etc)normallowAnswer (Q6)

Patient with Hypercapneic Respiratory FailureCase SummaryPatient did not have COPDHypercapnea not explained by the relatively high FEV1Patient found to have OSA

Patient with Hypercapneic Respiratory Failureend of case

A 54 year old male, with a 40 pack year smoking history, presents to the ED with a 5 d history of increasing dyspnea and a cough productive of yellow sputum which is new. Denies chest pain, orthopnea, PND, hemoptysis.

Quite large, BP 150 / 70, HR 110, tachypneic. Faint bilateral wheeze on auscultation, some crackles at both bases, no asymmetry in percussion. Mild pedal edema.Answer (Question 1) CXR poorly inflated lungs, bibasilar, linear or plate-like atelectasis (presumed due to obesity), lungs otherwise clear. There appears to be enlargement of the cardiac sillhouette, although the heart shadow might only appear enlarged due to the low lung volumes.

The patient has an ABG done in the ED which reveals the following: --

Answer (question 2): most likely acute on chronic hypercapnea

Answer (question 3): acute bronchitis + one or more of exacerbation of COPD vs obesity hypoventilation syndrome, vs sleep apnea hard to sayTherapy with antibiotics, steroids, bronchodilators, NIMVThe patient is admitted to the pulmonary ward and improves with therapy.

Answer (question 4):PFTs should be done explain why

PFTs are shown on the next slide

Analysis of spirometry does not reveal an obstructive defectA Restrictive defect presentThe DLCO is normal after adjustment for VA lets explore this in some more detail in the next slide