Respiratory Effects of Adaptive Servoventilation Therapy in Patients with Heart Failure and Cheyne-Stokes Respiration Compared to Healthy Volunteers

Abstract

Background: Nocturnaladaptive servoventilation (ASV) therapy is now frequently used to treat Cheyne-Stokes respiration (CSR), which is highly prevalent in patients with moderate-to-severe heart failure (HF) and characterized by periodical breathing (hyperventilation). Objectives: This study analyzed and compared the acute effects of a novel ASV device on carbon dioxide pressure (pCO₂) and oxygen saturation (SaO₂) in HF patients with CSR and healthy volunteers. The influence of being asleep or awake on the ASV algorithm was also determined. Methods: All subjects underwent ASV (PaceWave™, ResMed) for 1 h. Transcutaneous pCO₂ (PtcCO₂) and SaO₂ were assessed transcutaneously, while wakefulness was analyzed using EEG recordings. Assessments were made 30 min before and after ASV, and during 1 h of ASV. Results: Twenty HF patients (19 male; age 79 ± 12 years) and 15 volunteers (13 male, age 25 ± 4 years) were included. When awake, ASV was associated with a trend towards a decrease in PtcCO₂ and an increase in SaO₂ versus baseline in HF patients (34.4 ± 3.2 to 33.7 ± 3.8 mm Hg and 93.8 ± 2.6 to 94.9 ± 2.6%, respectively) and volunteers (39.5 ± 3.0 to 38.2 ± 3.8 mm Hg and 96.9 ± 1.3 to 97.8 ± 0.9%). While asleep during ASV, PtcCO₂ increased to 36.3 ± 3.8 mm Hg and SaO₂ decreased to 93.8 ± 2.6% in HF patients, with similar changes in volunteers (PtcCO₂ 41.7 ± 3.0 mm Hg, SaO₂ 97.1 ± 1.2). All comparisons were statistically significant (p ≤ 0.05, except the PtcCO₂ decrease in both groups when awake). Conclusions: ASV therapy might result in hyperventilation when subjects are awake, but while asleep, PtcCO₂ increased to mid-normal values, effects that would be favorable in HF patients with CSR.

Heart Failure Results in Inspiratory Muscle Dysfunction Irrespective of Left Ventricular Ejection Fraction

“…Twitch esophageal pressure (twPes) and twPgas were simultaneously recorded using balloon catheters (Cooper Surgical, Trumbull, CT, USA) transnasally inserted into the stomach and the distal esophagus, as previously described [8, 33]. Balloon catheters were connected to a differential pressure transducer (DPT-100 TM ; UT Medical Products, Athlone, Ireland) and an amplifier (ADInstruments, Oxford, UK) [7, 8, 33]. Pressure data for twPgas, twPes, and twPdi (defined as twPes – twPgas) were continuously displayed using LabChart TM software (ADInstruments, Oxford, UK) [11, 27] (online suppl.…”

“…Subjects were also instructed to repeatedly perform a maximum sniff maneuver (a short, sharp inspiratory maneuver). The best of 5 consecutive efforts was used for analysis [7, 8, 33].…”

Improving Nocturnal Hypoxemic Burden with Transvenous Phrenic Nerve Stimulation for the Treatment of Central Sleep Apnea

“…Figure 2 displays the percentage reduction in CAI from baseline for each patient. The oxygen desaturation index (4%) decreased from a median of 41 [30,56] events per hour to 19 [8,37] in the treatment group and increased from 33 [25,50] events per hour to 39 [26,57] in control (between groups p < .001). Marked or moderate improvement in the patient global assessment quality of life instrument was noted by 60% (35/58) treatment versus 6% (4/72) control subjects (p < .001) and daytime sleepiness decreased 2.5 [− 7, − 1] points in treatment compared with increasing 1.0 [− 2, 2] points in control based on the Epworth Sleepiness Scale (p < .001).…”

“…For this approach TPNS may make a difference in addressing the pathophysiology of CSA, including hypoxia, more profoundly than mask-based therapy have the ability to. In this context it has been shown that positive airway pressure therapies have adversely impacted blood pressure and sympathetic nerve activity in heart failure patients [25]. Further investigations on phrenic nerve stimulation and effects on the sympatho-vagal system are needed using direct microneurography to assess physiologic interactions.…”

A Paradigm Shift in the Treatment of Central Sleep Apnea in Heart Failure

“…Increased ventilation due to pressure support from ASV might worsen respiratory alkalosis, with a consequent increase in potassium excretion, thus predisposing to fatal arrhythmia. Although this is not supported by data demonstrating that ASV acutely improves alkalosis 7 and reduces appropriate defi brillator shocks, 19 ASV has been shown to increase alkalosis during wakefulness, 20 and the long-term eff ects of ASV on alkalosis and electrolyte balance in patients whose CSA is chronically suppressed is not clear. Unfavorable hemodynamics in those with pulmonary hypertension and right ventricular dysfunction, device-patient dyssynchrony with increased sleep fragmentation, or adverse eff ects of positive pressure on cardiac remodeling are also possible.…”