Characterization of heart rate and sleeping patterns in pre-term neonates
Gilbert Koch (1), Marc Pfister (1), Kerstin Jost (2), Alexandre N. Datta (3)
(1) Paediatric Pharmacology and Pharmacometrics, University of Basel, Children’s Hospital (UKBB), Basel, Switzerland (2) Department of Neonatology, University of Basel, Children’s Hospital (UKBB), Basel, Switzerland (3) Paediatric Neurology, University of Basel, Children’s Hospital (UKBB), Basel, Switzerland
Objectives: As a result of post-natal maturation sleeping patterns (SL) and circadian changes of heart rate (HR) are different in new-borns than in older children and adults. The goal of this model-based analysis was to characterize and compare SL and circadian changes of HR in pre-term neonates during their first 5 days of life.
Methods: SL and HR measurements were available from almost 100 pre-term neonates (GA < 32 weeks, birth weight < 1500 g) in their first 5 days of life. SL and HR were monitored daily during a continuous 3 hour interval. HR measurements were obtained by electromyography and sleeping behaviour was scored every 10 seconds as awake, active sleep or quiet sleep based on video recordings. For data analysis the average value from each minute interval was used. As dynamics of HR and SL followed oscillating patterns cosine functions with period length and amplitude as key parameters were applied. Non-linear mixed effect modelling was utilized to estimate individual and population behaviour.
Results: Individual SL and HR oscillations could be well described by the applied cosine functions. SL and circadian oscillations of HR in pre-term neonates had different population period lengths: 1.5 hrs and 2.5 hrs, respectively. Interestingly, HR showed a second, even faster oscillation with a period length of 15 mins, indicating that this endpoint has at least two overlying ultradian rhythms.
Conclusions: As a result of an immature “internal clock”, pre-term neonates show SL and HR oscillations that are not yet completely synchronized and have shorter period lengths than those observed in older children and adults.