What Do These Overnight Pulse Oximetry Test Results Suggest?

Authors:
Shruti Singh, MD; Sara Z. Khan, MD; Dilbagh Singh, MD; Sameer Verma, MD; and Arunabh Talwar, MD
Division of Pulmonary, Critical Care, and Sleep Medicine, North Shore-Long Island Jewish Health System, New Hyde Park, New York

Citation:
Singh S, Khan SZ, Singh D, Verma S, Talwar A. What do these overnight pulse oximetry test results suggest? [published online August 23, 2019]. Consultant360.

A 65-year-old man was referred to a pulmonology clinic for evaluation of dyspnea, tiredness, and fatigue for the past year. He denied any appetite changes and was not involved in any physical activity like he had been before the onset of symptoms. He reported having a 10 pack/day history of smoking for 25 years but had quit smoking 5 years ago. He also had a history of hypothyroidism for which he was on levothyroxine.

At presentation, his vital signs were as follows: blood pressure, 121/82 mm Hg; heart rate, 74 beats/min; height, 165 cm; weight, 93 kg; body mass index (BMI), 34.1 kg/m². Cardiac examination revealed normal S₁ and S₂ heart sounds and no murmur. Lung examination revealed decreased air entry at the bases.

Laboratory test results were within normal limits, including the following values: hemoglobin, 16 g/dL; mean corpuscular volume, 92 µm³; platelet count, 200 × 10³/µL; hemoglobin A_1c, 6.1%; thyrotropin, 1.5 mIU/L; sodium, 143 mEq/L; potassium, 3.5 mEq/L; chloride, 102 mEq/L; and blood urea nitrogen, 18 mg/dL. His daytime arterial oxygen saturation (Sao₂) at rest was 95%. On walking, his Sao₂ dropped to 92%. It was decided to further evaluate his oxygen status during the nighttime with an overnight pulse oximetry test, the results of which are shown in Figure 1.

Figure 1. The patient’s results of an overnight pulse oximetry test.

Answer and discussion on next page.