Transvenous phrenic nerve stimulation for the treatment of central sleep apnea reduces episodic hypoxemic burden

Study objectives: To determine the effect of transvenous phrenic nerve stimulation (TPNS) on the composition of the nocturnal hypoxemic burden in patients with CSA.Methods: We analysed oximetry data from baseline and follow-up overnight polysomnograms (PSG) in 134 CSA patients with implanted TPNS randomised (1:1) to neurostimulation (treatment group; TPNS on) or no stimu-lation (control group; TPNS off) from the remede over bar System Pivotal Trial. The hypoxemic burden was quantified using a battery of metrics, including the oxygen desaturation index (ODI), the relative sleep time spent below 90% SpO2 (T90) due to acute episodic desaturations (T90desat) and due to non-specific and non-cyclic drifts of SpO2 (T90non-specific). Mean change from baseline is provided.Results: TPNS titrated to reduce respiratory events significantly reduced the ODI in the treatment group by -15.85 h-1 +/- 1.99 compared to the control group, which increased 1.32 h-1 +/- 1.85 (p 0001) and shortened the relative T90 duration by-3.81 percentage points +/- 1.23 vs. 0.49 percentage points +/- 1.14 increase (p = 0.012). This shortening of T90 was primarily accomplished by reducing the brief cyclic desaturations (T90desaturation: -4.32 percentage points +/- 0.98 vs. 0.52 percentage points +/- 0.91, p = 0.0004) while notable non-specific drifts in SpO2 remained unchanged (T90non-specific: 0.18 percentage points +/- 0.62 vs.-0.13 percentage points +/- 0.57, p = 0.72).Conclusions: TPNS appears to significantly reduce the nocturnal hypoxemic burden due to sleep-disordered breathing, but a considerable nocturnal hypoxemic burden from other sources remains. Further investigations are warranted to identify the best strategy to reduce the nocturnal hypoxemic burden beyond preventing res-piratory events.