Daytime Measurements Underestimate Nocturnal Oxygen Desaturations in Pulmonary Arterial and Chronic Thromboembolic Pulmonary Hypertension

Abstract

Background: Nocturnal hypoxemia is important in precapillary pulmonary hypertension (pPH) as it worsens pulmonary hemodynamics. Whether daytime oxygen saturation (Sp<smlcap>o</smlcap>₂) predicts nocturnal hypoxemia in pPH patients has not been conclusively studied. Objectives: To investigate the prevalence of nocturnal hypoxemia in comparison to daytime Sp<smlcap>o</smlcap>₂ and disease severity in ambulatory patients with pulmonary hypertension. Methods: Consecutive patients diagnosed with pPH classified as either pulmonary arterial (PAH) or chronic thromboembolic pPH (CTEPH) had daytime resting and exercise Sp<smlcap>o</smlcap>₂ (at the end of a 6-min walk test); thereafter, they underwent overnight pulse oximetry at home. Functional class, pro-brain natriuretic peptide (pro-BNP) and the tricuspid pressure gradient were assessed. Results: Sixty-three patients [median (quartiles) age 62 (53; 71), 43 females] with PAH (n = 44) and CTEPH (n = 19) were included. The resting Sp<smlcap>o</smlcap>₂, exercise Sp<smlcap>o</smlcap>₂, and mean nocturnal Sp<smlcap>o</smlcap>₂ were 95% (92; 96), 88% (81; 95), and 89% (85; 92), respectively. Forty-nine patients (77%) spent >10% of the night with Sp<smlcap>o</smlcap>₂ <90% (desaturators), and 33 (52%) spent >50% of the night with Sp<smlcap>o</smlcap>₂ <90% (sustained desaturators). The positive predictive values of daytime Sp<smlcap>o</smlcap>₂ >90% for being a nocturnal nondesaturator or sustained nondesaturator were 25 and 53%, respectively. Nocturnal Sp<smlcap>o</smlcap>₂ was negatively correlated with the tricuspid pressure gradient, but not with functional class, 6-min walk test, or pro-BNP. Conclusions: Nocturnal hypoxemia is very common in PAH and CTEPH despite often normal daytime Sp<smlcap>o</smlcap>₂ and reflects disease severity. Nocturnal pulse oximetry should be considered in the routine evaluation of pPH patients and research should be directed toward the treatment of nocturnal desaturation in pPH.

Wrist Actigraphy Predicts Outcome in Patients with Pulmonary Hypertension

“…This underscores the severe activity limitation in the everyday life of patients affected by pulmonary arterial or chronic thromoembolic PH [13]. In line with previous studies, more than a third of our patients had sleep-disordered breathing with mainly central apnoea/Cheyne-Stokes respiration and low nocturnal oxygen saturation [14,36,37]. However, these disturbances did not result in a subjectively perceived excessive daytime sleepiness.…”

Effect of Oxygen and Acetazolamide on Nocturnal Cardiac Conduction, Repolarization, and Arrhythmias in Precapillary Pulmonary Hypertension and Sleep-Disturbed Breathing

“…[1][2][3] SDB is relevant because it impairs quality of life. 2 Oxygen deprivation in pulmonary vascular cells during SDB further triggers pulmonary vasoconstriction with increase in pulmonary vascular resistance maintaining a vicious cycle.…”

“…2 Oxygen deprivation in pulmonary vascular cells during SDB further triggers pulmonary vasoconstriction with increase in pulmonary vascular resistance maintaining a vicious cycle. 3,4 Remodeling of the right ventricle (RV) in response to increased aft erload together with hypoxemia and consecutive myocardial ischemia may aff ect myocardial autonomic activity, lead to conduction and repolarization abnormalities, and represent an arrhythmogenic substrate. 5-7 Cardiac arrhythmias are important infl uencing factors to morbidity and mortality in patients with pulmonary hypertension (PH) and result in clinical deterioration and compromised cardiac function.…”

Altitude Travel in Patients With Pulmonary Hypertension: Randomized Pilot-Trial Evaluating Nocturnal Oxygen Therapy

“…We and others have demonstrated that SDB including nocturnal oxygen desaturation and periodic breathing are highly prevalent in patients with right heart failure due to PH of various etiologies and are associated with reduced quality of life, impaired exercise capacity, and hemodynamics ( 3 , 34 – 36 ): 39% of 43 PH patients studied at our center had ≥ 10 events/h of Cheyne–Stokes respiration/central sleep apnea (CSR/CSA), and the majority of them (68%) spent more than 10% of the night time with a low arterial SpO 2 (<90%). With the current study, we have shown that SDB in PH are even more pronounced at altitude.…”