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A 75-year-old man with a 120-pack-year smoking history has dyspnea on exertion(eg, when he walks more than 3 blocks or climbs 1 flight of stairs) butnot when he is at rest or asleep. His symptoms have progressively worsenedover the past 3 to 4 years and have been accompanied by a 20-lb weight loss.
A 75-year-old man with a 120-pack-year smoking history has dyspnea on exertion(eg, when he walks more than 3 blocks or climbs 1 flight of stairs) butnot when he is at rest or asleep. His symptoms have progressively worsenedover the past 3 to 4 years and have been accompanied by a 20-lb weight loss.PHYSICAL EXAMINATION
This thin man is not currently in respiratory distress; however, his respirationrate at rest is 20 breaths per minute, and he is using accessory musclesof respiration. Heart rate is 88 beats per minute with a regular rhythm andno murmurs; a parasternal lift is evident. The lungs show symmetric expansion;breath sounds are reduced and expiration prolonged, but there are nowheezes. There is 1+ bilateral edema of the ankles.DIAGNOSTIC STUDIES
Hemoglobin level is 16.2 g/dL and hematocrit is 52 mL/dL; white bloodcell count and platelet count are normal. Results of a chemistry panel arealso normal. A chest radiograph shows flattened diaphragms, diminished pulmonaryvascular markings, and replacement of the retrosternal air space. AnECG reveals right atrial and ventricular hypertrophy and incomplete rightbundle branch block.Spirometry shows a forced expiratory volume in 1 second to forced vitalcapacity ratio (FEV1:FVC) of 50%; the FEV1 is 30% of the normal value for aman of his age and height. Oxygen saturation on room air is 88% at rest and84% after the patient has walked for 1 minute.Under which of the following circumstances will oxygen therapy bemost beneficial for this patient?A. When he is short of breath, because oxygen can only palliate his symptomsand is not likely to provide any other benefit.B. At night when the patient is sleeping, to reduce his nocturnal hypercapnia.C. At rest, with exertion, and during sleep; using oxygen as much as possiblewill ameliorate his symptoms and improve his quality of life and survival.D. During exertion, to increase the distance he can walk; using oxygen atother times is unnecessary.E. While the patient is awake, to help lower his hematocrit.CORRECT ANSWER: C
This patient has severe chronic obstructive pulmonarydisease (COPD) (his FEV1 is less than 35% of thepredicted value) and has demonstrated hypoxemia bothat rest and with exertion. He meets the criteria for longtermoxygen therapy, which include a resting PaO2 of 55mm Hg or less or a resting oxygen saturation level of 88%or less. He also demonstrates exertional desaturation.If a patient with COPD has cor pulmonale, a hematocritgreater than 55 mL/dL, or congestive heart failure, itis recommended that oxygen be prescribed at rest, duringexercise, and during sleep. Data from oxygen therapy trialshave shownthat the morehours per daythat oxygen isadministered, thegreater the benefits,and that nocturnaloxygen(choice B) is notas helpful as oxygenadministeredall day long.1This patient'shematocritindicates thathe is likely polycythemic,andthe examination,chest film, andECG all revealsigns of cor pulmonale.Thus,this man qualifiesfor longterm,continuousoxygen therapyon several counts.In patients whose resting PaO2 is greater than 60mm Hg or whose oxygen saturation is greater than 90%,oxygen is recommended only if sleep or exercise desaturationis documented. Supplemental nocturnal oxygen iswarranted if these patients manifest such complications ofhypoxemia as pulmonary hypertension or cardiac arrhythmiaduring sleep.2Long-term oxygen therapy can provide multiple benefits,including increase in body weight, reversal of secondarypolycythemia, amelioration of heart failure symptomsresulting from cor pulmonale, enhanced neuropsychologicalfunction, and improved exercise capacity. Inpatients with exertional dyspnea, oxygen therapy can preventpreventtransient rises in pulmonary artery pressure, relievedyspnea, and improve exercise performance.Moreover, oxygen is one of the few COPD treatmentsthat improves survival. Studies have demonstratedan increase in survival among patients meeting the criteriafor long-term oxygen therapy who received oxygen,compared with those who did not; in addition, continuoustherapy was shown to be more beneficial than nocturnalor other part-time regimens.1 In trials of long-term oxygentherapy, the more hours per day oxygen was used, thegreater the increase in longevity.2Thus, choice C is the only correct one here. This patientis likely to reap numerous benefits from oxygen therapy,and these benefits will be maximized if oxygen isused continuously.Outcome of this case. Continuous, long-term oxygentherapy with both stationary and mobile systems ofdelivery was prescribed. At a 4-month follow-up visit, thepatient had remained out of the hospital and reported enhancedexercise capacity (ie, he was able to walk fartherbefore becoming short of breath).
Barnes PJ. Chronic obstructive pulmonary disease.
N Engl J Med.
Tarpy SP, Celli BR. Long-term oxygen therapy.
N Engl J Med.
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