24-Hour Hypoxia and Pulmonary Hypertension in Patients with Idiopathic Pulmonary Fibrosis

Marcelo P. Rodrigues1, *, Carolina M. Vissoci2, Samuel P. Rosa3, Sandra B.C. Negreiros1
1 Department of Pulmonology, School of Medicine, Universidade de Brasília (UnB), Brasília, DF, Brazil
2 Student of Medicine. School of Medicine, UnB, Brasília, DF, Brazil
3 Department of Cardiology, Hospital de Base, Brasília, DF, Brazil

Article Metrics

CrossRef Citations:
Total Statistics:

Full-Text HTML Views: 4092
Abstract HTML Views: 2244
PDF Downloads: 1037
ePub Downloads: 796
Total Views/Downloads: 8169
Unique Statistics:

Full-Text HTML Views: 2222
Abstract HTML Views: 1263
PDF Downloads: 657
ePub Downloads: 517
Total Views/Downloads: 4659

Creative Commons License
© 2017 Rodrigues et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the SQSW 306, B, 603, Setor Sudoeste 70673-432 - Brasília, DF, Brazil, Tel: +55-61-8433-0879; E-mail:



The quantification of hypoxia based on resting partial pressure of arterial oxygen (PaO2) may underestimate hypoxia related to activities of daily living or sleep and thus not accurately reflect pulmonary hypertension (PH). The aim of the present study was to investigate the association of resting PaO2 with percent time of SpO2 below 90% (T90) and 88% (T88) in 24 hours. We also evaluated the capacity of hypoxia measures to predict PH in patients with idiopathic pulmonary fibrosis (IPF).


This cross-sectional study included 27 patients with IPF presenting PaO2 ≥ 55 mmHg and not receiving home oxygen therapy. All were submitted to blood gas measurement, 24-h oximetry, and transthoracic Doppler echocardiography to estimate systolic pulmonary artery pressure (SPAP). Patients were divided into three groups according to resting PaO2: 55-55.9 mmHg (A); 60-60.9 mmHg (B); ≥ 70 mmHg (C). PH was defined as “likely” if SPAP > 50 mmHg, and as possible for SPAP between 37 and 50 mmHg.


T90 and T88 in Groups A, B, and C were as follows: 59.9±29% and 44.1±34%; 49.3±34% and 29.9±31%; 17.1±25% and 8.8±18% respectively, with significant differences between the groups for both T90 (p ≤ 0.01) and T88 (p = 0.02). PaO2 was inversely correlated with T90 (r = -0.398; p = 0.04) and T88 (r = -0.351; p = 0.07). Hypoxia variables did not correlate with SPAP, and were not able to predict PH.


Percent time of SpO2 below 90% and 88% in 24 hours revealed periods of severe hypoxia even in patients with borderline-normal resting PaO2. However, none of the present hypoxia variables was capable of predicting PH.

Keywords: Hypertension, Pulmonary, Hypoxia, Idiopathic pulmonary fibrosis, Blood gas monitoring, Transcutaneous.