title: Optimization of pressure settings during adaptive servo-ventilation support using real-time heart rate variability assessment: initial case report.
abstract: Adaptive servo-ventilation (ASV) therapy is a recent non-invasive positive pressure ventilation therapy that was developed for patients with heart failure (HF) refractory to optimal medical therapy. However, it is likely that ASV therapy at relatively higher pressure setting worsens some of the patients' prognosis compared with optimal medical therapy. Therefore, identification of optimal pressure settings of ASV therapy is warranted.
  
  
  
  We present the case of a 42-year-old male with HF, which was caused by dilated cardiomyopathy, who was admitted to our institution for evaluating his eligibility for heart transplantation. To identify the optimal pressure setting [peak end-expiratory pressure (PEEP) ramp test], we performed an ASV support test, during which the PEEP settings were set at levels ranging from 4 to 8 mmHg, and a heart rate variability (HRV) analysis using the MemCalc power spectral density method. Clinical parameters varied dramatically during the PEEP ramp test. Over incremental PEEP levels, pulmonary capillary wedge pressure, cardiac index and high-frequency level (reflecting parasympathetic activity) decreased; however, the low-frequency level increased along with increase in plasma noradrenaline concentrations.
  
  
  
  An inappropriately high PEEP setting may stimulate sympathetic nerve activity accompanied by decreased cardiac output. This was the first report on the PEEP ramp test during ASV therapy. Further research is warranted to determine whether use of optimal pressure settings using HRV analyses may improve the long-term prognosis of such patients.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. te.imamu@gmail.com.
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Imamura
authors.affiliation: Second Department of Internal Medicine, Toyama University, 2630 Sugitani Toyama-shi, Toyama, 930-0194, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nitta
authors.affiliation: Second Department of Internal Medicine, Toyama University, 2630 Sugitani Toyama-shi, Toyama, 930-0194, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kinugawa
mesh_terms: D015415:Biomarkers / Q000097:blood; D006328:Cardiac Catheterization; D006321:Heart / Q000294:innervation*; D006333:Heart Failure / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D063087:Noninvasive Ventilation / Q000009:adverse effects / Q000379:methods*; D009638:Norepinephrine / Q000097:blood; D011669:Pulmonary Wedge Pressure; D013564:Sympathetic Nervous System / Q000378:metabolism / Q000503:physiopathology*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D009638:Norepinephrine
keywords: Case report; Heart failure; Non-invasive positive pressure ventilation; Peak end-expiratory pressure