Abstract 9309: Daily Respiratory Rate Trends are Significantly Elevated Prior to HF Admissions
Introduction: Implantable devices are capable of monitoring respiration by measuring intra-thoracic impedance. Respiratory rate (RR), one of the vital signs, increases with activity, stress, worsening heart failure (HF) and other diseases. We hypothesize that RR is increased in the days leading up to a HF admission compared with those observed at a random time in HF patients.
Methods: HF patients indicated for ICD or CRT-D were implanted with INCEPTATM and followed for 9 months. The device trended daily maximum (max), median (med) and minimum (min) RR up to a year. We retrospectively compared changes in averaged daily RRs (ΔRR) between a baseline and an event window (28-32 and 1-5 days before an index time respectively). The index time was defined as the day of first HF hospital admission in patients who had a HF admission (HF group) and the day of 6-month follow-up (6MFU) in patients who completed the study without a HF admission (control group). Patients who had fewer than 3 valid data points during either of the 5-day windows were excluded. Wilcoxon rank sum test was used to detect non-zero difference in ΔRR between groups.
Results: Of the 121 patients enrolled, 100 had sufficient data for the analysis (10 with HF admissions). The figure boxplot shows all 3 RRs were significantly elevated prior to HF admissions. ΔRR (breath/minute) was significantly larger prior to a HF admission in the HF group, than observed prior to the 6MFU in the control group (max ΔRR: 2.4± 2.9 vs. -0.05± 1.8, p = .006; med: 2.2± 2.7 vs. 0.02± 1.1 p = .004; min 1.5±1.9 vs. 0.05±1.2, p = .04).
Conclusions: This study showed a significantly larger change in daily RR trends prior to a HF admission than was observed at a random time in patients who did not decompensate. Ambulatory daily RR trends may be a valuable addition to standard management for HF patients.
- © 2012 by American Heart Association, Inc.