PURPOSE: Nocturnal pulse oximetry (NPO) is used to evaluate patients for hypoxia and determine candidacy for supplemental oxygen. In addition, NPO can provide the oxygen desaturation index (ODI) which correlates with the apnea-hypopnea index (AHI) in patients with sleep apnea. Our hypothesis is that patients who would be prescribed supplemental oxygen because of hypoxia on NPO may have underlying sleep apnea. We investigated the prevalence of increased ODI, a surrogate for AHI, in patients with and without nocturnal hypoxia.
METHODS: We reviewed 310 nocturnal pulse oximetry (NPO) done over a 3 year period. Inclusion criteria were: 1) Duration of valid data > 4 hours, 2) No supplemental oxygen or ventilatory support, 3) Age > 18, and 4) Artifact and pulse search duration < 15% the study time. We reviewed the studies for occurrence of desaturation below 89% (Sat<89%) and ODI4 defined as number of four percent desaturation events per hour of study time.
RESULTS: 110 studies met the inclusion criteria. Ordering physicians were primary care (50%) and pulmonologists (40%).There were 49 men and 61 women with a mean age of 62 +/- 17.8 years. The overall prevalence of ODI4 > 5 events/hour was 34.5%. We compared patients with Sat<89% (n=54) to those without (n=56). The prevalence of ODI4 > 5 events/hour was significantly different between the two groups (57% in the hypoxia group vs. 12%, P<0.0001) (Table 1).
CONCLUSION: Patients with nocturnal hypoxia on NPO have a significantly higher percentage of ODI4 > 5 events/hour compared to those without. This may indicate a high prevalence of sleep apnea in these patients and underscores the importance of examining the ODI from NPO.
CLINICAL IMPLICATIONS: Correction of nocturnal hypoxia is beneficial to patients; however, it does not address sleep apnea that may be present in more than half of patients with hypoxia. The ODI from NPO provides clinically significant information pertinent to sleep apnea. Considering the cardiovascular and neurocognitive effects of sleep apnea, patients with elevated ODI on NPO deserve further evaluation.
DISCLOSURE: Fidaa Shaib, No Financial Disclosure Information; No Product/Research Disclosure Information