333 - Central Apnea Defined by Edi Signal Is Common in Stable, Spontaneously Breathing Preterm Infants

Publication Number: 333.4132

Katarzyna Piatek, Turku University Hospital; University of Turku, Turku, Varsinais-Suomi, Finland; Halidu Abdulai, Abo Akademi University, Turku, Varsinais-Suomi, Finland; Muhammad Shaher Yar, Abö Akademi University, Turku, Uusimaa, Finland; Pragati Manandhar, Abo Akademi University, Turku, Varsinais-Suomi, Finland; Vilhelmiina Parikka, University of Turku, Turku, Varsinais-Suomi, Finland; Hergys Rexha, Åbo Akademi University, Turku, Varsinais-Suomi, Finland; Sebastien Lafond, Åbo Akademi University, Turku, Varsinais-Suomi, Finland; Liisa Lehtonen, Turku University Hospital, Turku, Varsinais-Suomi, Finland; Hanna Soukka, University of Turku, Turku, Varsinais-Suomi, Finland

Background: Preterm infants at 34-36 weeks postmenstrual age (PMA) are often hospitalized primarily for apnea monitoring; however, current monitoring tools are insufficient. The signal of the electrical activity of the diaphragm (Edi signal) represents neural breathing pattern and may provide a more accurate method to monitor central apnea.

Objective: To quantify central apnea in stable, spontaneously breathing preterm infants ≥34 weeks PMA using the Edi signal and two apnea definitions.

Design/Methods: In a prospective observational study, we included preterm infants ≥34 weeks PMA who had presented clinical apnea and were off respiratory support and caffeine citrate. Infants with congenital malformations, IVH stage 3 – 4, or current infectious symptoms were excluded. We recorded 12 hours of continuous nighttime vital signs, including the Edi signal. The Edi integral represents the area under the curve of the Edi signal. Apnea was defined by two thresholds: (1) Edi integral < 0.15 μVs for ≥5 seconds (low threshold) and (2) Edi integral < 0.5 μVs for ≥5 seconds (high threshold). Central respiratory breaks < 5 seconds were excluded. Recordings were conducted using Edi catheters provided by Getinge under a written agreement. Raw data was shared with Getinge for product development purposes. A Python script was developed to automate apnea episode extraction, and data were analyzed using R ver. 4.4.

Results: We enrolled 99 infants with a mean gestational age of 32+4 weeks (SD 2+5) and mean birth weight of 1927 g (SD 712 g). Recordings were taken at a mean PMA of 35+5 weeks (SD 1), yielding 1130 hours of Edi signal data. At the low threshold, infants spent an average of 5.1% (SD 3.8%) of the recording in apnea, equating to a cumulative length of 3.1 minutes (SD 2.3) of apnea per hour. Mean apnea duration was 6.8 seconds (SD 0.4), with the longest episode lasting 41.7 seconds. At the high threshold, infants spent 8.7% (SD 6.4%) of the recording in apnea, averaging 5.2 minutes (SD 3.8) per hour. Mean apnea duration was 7.3 seconds (SD 0.6), with the longest episode at 160 seconds. Differences in cumulative and mean apnea duration between thresholds were statistically significant (t-test, p < 0.05).

Conclusion(s): Apnea episodes are common in stable, spontaneously breathing preterm infants, with significant variation in cumulative and mean apnea durations depending on the threshold used. Selecting appropriate Edi-based thresholds is essential for accurate apnea quantification. Shorter respiratory pauses may indicate periodic breathing. Further research is needed to explore the relationship between apnea and heart rate response.

Figure 1. Timeline of Milestones
Average Postmenstrual Age at Achievement of Clinical Milestones
The symbol n represents the number of infants for whom the milestone was relevant or the treatment was initiated. Clinical apnea is defined as apnea identified by the clinical team, marked by a heart rate below 80 beats per minute during sleep, and documented in medical records. Caffeine citrate was discontinued based solely on the clinical team’s decision, and infants became eligible for apnea recording 72 hours after discontinuation. However, for some infants, the team chose to restart the medication after the recording, following clinical assessment. In the unit, non-invasive ventilation options routinely available include HFNC, nCPAP, and NIV-NAVA. For invasive ventilation, we use NAVA, SIMV+PS, and HFO.

Figure 2. Apnea Count per Hour of Recording
Normalized apnea count for each patient under the low threshold criteria.

Figure 1. Timeline of Milestones
Average Postmenstrual Age at Achievement of Clinical Milestones
The symbol n represents the number of infants for whom the milestone was relevant or the treatment was initiated. Clinical apnea is defined as apnea identified by the clinical team, marked by a heart rate below 80 beats per minute during sleep, and documented in medical records. Caffeine citrate was discontinued based solely on the clinical team’s decision, and infants became eligible for apnea recording 72 hours after discontinuation. However, for some infants, the team chose to restart the medication after the recording, following clinical assessment. In the unit, non-invasive ventilation options routinely available include HFNC, nCPAP, and NIV-NAVA. For invasive ventilation, we use NAVA, SIMV+PS, and HFO.

Figure 2. Apnea Count per Hour of Recording
Normalized apnea count for each patient under the low threshold criteria.