Heart Rate Variability
Begum et al., 2009
Bystrova 2009????
Cong et al., 2009
Cong et al. 2012
Cong et al., 2012
Updated 6/26-2010 & 10/8/2013
PT, pretest incubator-testKC-posttest incubator one day. 60 min
of KC, 30 min of incubator. %LF of HR was 41.4 pretest to
48.3KC(sig); %HF of HR was 45.9 pretest to 33.5KC (sig).
LF/HF ratio of HR did not change over periods. Total power of
HR was 635pretest to 268 KC to 618posttest (sig decrease in
KC, sig increase after KC). Many other sig differences in
spectral analysis of RR,SaO2 and cerebral oxygenation.
PT, HR used as pain index. LF and HF increased during
Heelstick; LF was higher in KC at baseline and at heel stick than
in incubator baseline and heelstick; HF was higher in KC
baseline than incubator baseline; LF/HF ratio was sig lower
during KC recovery than incubator recovery.
PT, R cross over trial of 15 and 30 mins of KC vs. incubator and
HRV was better stabilized during KC.
PT, Case study of VLBW twins who got 15 and 30 mins of KC
heelstick compared to incubator heel stick and LF/HF ratio was
lower in the long and short KC conditions compared to incubator
Feldman, Eidelman 2003
Feldman et al., 2013
Field & Diego, 2008
Harrison, 2010
McCain et al., 2005
PT, RCT, vagal tone for 10 min B4 KC then 10min at 37 wks.
More rapid maturation of vagal tone in KCs. VAGAL TONE
PT, quasi-exp 10 year follow-up of 2002 study with 73 infants who
got 1 hours of CK per day for 14 consecutive days vs infants
without kc. Respiratory sinus arrhythmia was measured and
was increased in postpartum period. Respiratory sinus arrhythmia
was dynamically interrelated with maternal behavior over the first
ten years of life and led to improved physiology, executive
functions and mother-child reciprocity at 10 years.
FT, Case Study of congenital heart defect infant and measured HF
power before, during and after feedings before KC began and after
14 days of KC and then again at two and four weeks after end of
KC. Parasympathetic power improved over time.
PT, HRV case study at 35 weeks. Sympathetic control
Remains high even during deep sleep in KC; parasympaThetic control increases during SSC as compared to incubator
time. Decrease in LF and HF during KC
McCain , L-H et al., 2005
HRV and KC Outcomes of our case study:
1. Clear state differences between open air crib and KC
2. Clear difference in the number of valid segments. T test on the # of valid HRV segments
in open air crib vs KC was highly significant (t = , p = )
3. First to report HRV during KC sleep in non-ventilated infants
Morgan et al (bergman)2011
FT, HRV of 2 day old infants sleeping with mom and when
sleeping in cot. Significantly higher LF (sympathetic control) in
separation than in KC. This indicates central anxious autonomic arousal
during separation (stress).
Schrod & Walter, 2002
PT, HRV showed greater increase in low frequency than high
frequency activity after being returned to horizontal position,
suggesting a relative increase in sympathetic versus vagal
activation. Prolonged head-up positioning has no undesirable
effects in preterm infants with stable circultation including very
immature infants of 25 weeks gestation”(pg. 259
Smith
PT, Smith, SL. 2003. Heart period variability of intubated very-low-birth-weight infants
during incubator care and maternal holding. Am J Critical Care 12 (1), 54-64. 14 preterm infants
tested at mean of 34 postnatal days who were on mechanical ventilation (BPD babies) served as own
controls and were randomly assigned to 2 hrs of intermittent KC for 2 consecutive days followed by
2 days of incubator care or vice versa. Multiple 300 second epochs of 5Hz data was analyzed. Mean
interbeat interval (time domain assessment) was 332 ms during KC, 368 ms during incubator. No
differences in low frequency, high frequency, low/high frequency ratio power (Frequency domain
assessment) between KC and incubator existed (pg. 60). Mean LF for KC was 124.6 ms2 (R=51.971.4 ms2), LF for incubator was 70.3 before KC, 71.4 after KC and 51.9-61.7 ms2 during incubator
period. INCREASE IN LF DURING KC. Mean HF power was similar for KC (8.8) and incubator
(6.1 ms2). LF/HF ratio was 6.7ms2 during KC and was between 6.8 – 8.1 ms2 during incubator.
Gestationally older infants (32-34 weeks corrected age) had increased power (but not significantly
different) in the low and high frequency regions than 28-29, 30-31 wk infants. Significantly higher
temp and significantly higher FiO2 during KC than incubator, and lower (but not sig) SaO2, but the
data are not given as these are reported in another study and just mentioned here. PT, Cross-over
design, HRV, T, SaO2,FiO2
Smith, SL, Doig AK, Dudley Wn. 2004. Characteristics of heart period variability in intubated
very low birthw eight infants with respiratory disease. Biol Neonate 86(4), 269-274. 16 infants.
HF did not improve with GA, LF did increase with age. LF and HF were not different between
awake and sleep states. Parasympathetic tone did not improve with gestational age and the
intensive care environment may stimulate a sympathetic response in these infants and disrupt
normal parasympathetic development. NICU is DISRUPTIVE
Smith SL Doig AK, Dudley WN 2005. Impaired parasympathetic response to feeding in
ventilated preterm babies. Arch dis child Fetal Neonatal Edi 90, F505-F508
Understanding HRV
LFA = low frequency activity. Predominantly sympathetic, but reflects the influence of both
sympathetic and parasympathetic on HR and reflects activity of baroreceptor reflex. values are
0.02-0.20Hz
RFA – respiratory frequency activity = predominantly parasympathetic. Same as High Frequency
(0.2-2.0Hz). Parasympathetic activity is vagal activity.
L/R (or LF/HF) – you read the R or HF value as a “1” and then the L/R ratio shows how much
sympathetic there is to the parasympathetic “1”.
Verklan M, Padhye N. 2004. Spectral analysis of heart rate variability: an emerging tool for
assessing stability during transition to extrauterine life. JOGNN 33(2), 256-265.
Intervening Variables:
1. Respiratory distress.Infants with acute respiratory distress should be excluded from HRV study
as they have significantly greater peripheral vascular resistance even in the horizontal position
(Waldman et al., 1979). Waldman S, Krauss AN, Auld PAM. 1979. Baroreceptors in preterm
infants. Their relationship to maturity and disease. Dev Med Child Neurol 21, 714-722.
2. Prone position increases sympathetic influence, not parasympathetic influence. Yet, Ariagno
et al., 2003 found that time domain analysis (interbeat interval) of HRV showed significantly
lower variability in prone, but only during QS, not AS. Frequency domain analysis (LF:HR ratio)
of HRV showed no differences between prone and supine sleeping positions. The reduced HRV
potentially increases the vulnerability to SIDS in preterm infants at 44 and 52 wks PCA (Ariagno
RL, Mirmiran M, Adams, MM, Saporito AG, Dubin AM, Baldwin RB. 2003. Effect of position
on sleep, heart rate variability, and QT intervals in preterm infants at 1 and 3 months corrected
age.Pediatr 111(3), 622-625.
Prone position reduces HRV and variability in SaO2. Maynard V, Bignall S, Kitchen S. 2000.
Effect of positioning on respiratory synchrony in non-ventilated preterm infants. Physiother Res
Int 5(2), 96-110.
3. Supine position. Goto K, Mirmiran M, Adams MM et al., 1999. More awakenings and
heart rate variability during supine sleep in preterm infants. Pediatr 103, 603-609.
4. Gestational Age (see Smith articles)
5. Feeding Palmer ED. 1976. Vasovagal reflexes occur with feeding. Am. J. Gastroenterol,
66 (6), 513-522.
6. Sleep. Dominance of HF of HR has been reported during quiet sleep state (Porges SW,
Doussard-Roosevelt JA, Stifter CA, McClenny BD, Riniolo TC. 1999. Sleep state and
vagal regulation of heart period patterns in the human newborn: an extension of
polyvagal theory. Psychophysiology 36, 14-21; Villa mP, Calcagnini G, Pagani J, Paggi
B, Massa F, Ronchetti R. 2000. Effects of sleep stage and age on short-term heart rate
variability during sleep in healthy infants and chidren. CHEST, 117, 460-466) even
though Smith 2003 did not find this and Begum 2009 did not find this.
7. Feeding bradycardia - Verrappan article. Parasympathetic did not increase with enteral
feedings as expected and LF decreased during and after feeding suggesting the
anticipated effect of inhibition of sympathetic ne system in response to gut stimulus.
Critilly ill VLBW infants have an overriding sympathetic response but may not have
adequate parasympathetic nervous system tone development.(Smith et al., 2005).
8. Digestion. Digestion increases parasympathetic tone so be sure infants are through
digesting when do HRV
9. Behavioral State. In sleep, sympathetic tone increases, when active, parasympathetic
tone in increases.
10. Upright position (head tilt at 30 degrees) increases sympathetic influences in the
sympathetic-vagal balance (Schrod & Walter 2002 on KC bib). 60 degree head-up tilt in
1 mo and 3 months. Tilt provoked a reflex tachycardia followed by a bradycardia and
settling to a stable HR level. Prone sleeping damps some physiologic responses.
(Galland, Hayman, Taylor, Bolton, Sayers, & Williams, 2000. Factors affecting heart rate
variability and heart rate responses to tilting in infants aged 1 and 3 months. Pediatric
Research, 48(3), 360-368). The upright body position and upright head position causes
gravitational pooling of blood and thereby activating baroreceptors (Tachtsidis I, Elwell
CE, Le CW, Leung TS, Smith M, Delpy DT. 2003. Spectral characteristics of
spontaneous oscillations in cerebral hemodynamics are posture dependent, Adv Exp Med
Biol 540: 31-36; Schrod & Walter, 2002), which then causes an increase in
SYMPATHETIC activity and a DECREASE in CEREBRAL OXYGEN delivery
(Begum et al., 2009, p. 23)
11. Increasing age during the first weeks of life increases occur in sympathetic activity as
evidenced by increase in LF responses even in preterm infants. On day 1 sympathetic
response is 26% increased but by day 8 the increase in sympathetic response is 70-80%
(Schrod et al., 2002 on KC bib) and this finding is confirmed by Chatow. Chatow U,
Davidson S, Reichman BL, Akselrod S. 1995. Development and maturation of the
autonomic nervous system in preterm and fullterm infants using spectral analysis of heart
rate fluctuations. Pediatr Res 37, 294-302.
12. . Temperature. Increased environmental air temperature increases infant central and
peripheral body temps with a concurrent increase in low frequency power (Davidson et al.,
1997). In kc infant’s body temperature warms up and suggests increased activity in the
sympathetic nervous system. Davidson S, Reina N, Shefi O, Hai-Tov U, Akselrod S. 1997.
Spectral analysis of heart rate fluctuations and optimum thermal management for low birth
weight infants. Med Biol Eng Comput 35, 619-625. Increase in body temp causes increase in
LF of HR (Smith 2003; Devidson et al, 1997 above). The increase in body temperature
during KC influenced the increased LF of HR during KC in Begum et al., 2009 study
“AN increase in LF of HR and a decrease in LF of regional cerebral oxygenation can be
understood as activation of the central nervous system and brain function during KC.(Begum, et
al., 2009, p. 23).
A decrease in total power of HR, Sao2 and regional cerebral oxygenation occurred during KC
(Begum et al., 2009); because total power is an index of total variance and changes in TP during
KC indicate changes in total variance. A drop occurred and this meant better physiologic stability
during KC. The decrease might be due to increased sleep, decreased activity (Porges SW,
McCabe PM, Yongue BG. 1982. Respiratory-heart rate interaction and psycho-physiological
implications for pathophysiology and behavior. In Caccioppor JT, Petty R, Eds., Perspectives in
Cardiovascular Psychophysiology. NY Guilford Press.; Ludington-Hoe et al., 2006).
Arai YC, Ueda W, Ushida T, Kandatsu N, Ito H, & Komatsu, T. (2009). Increased heart rate
variability correlation between mother and child immediately pre-operation. Acta
Anaesthesiology Scandinavica, 53(5): 607-610. (Co-synchrony)
EFFECT OF MASSAGE on HRV
Smith, S.L., Lux, R., Haley, S, Slater M, Beechy J. et al., (2013). The effect of massage on heart
rate variability in preterm infants. J. Perinatology 33(1), 59-64. Masked RCT of 17 massage and
20 control 29-32 week medically stable PTs. Licensed massage therapists did the treatment two
times per day for 4 weeks. Weekly HRV was analyzed using SPSS GEE (generalized estimating
equations). HRV improved in massage infant but not in the control infants. Massaged males had
greater improvement than massaged females. HRV in massaged infantswas on a trajectory
comparable to term-born infants by study completion. Massage may improve infant response to
exogenous stressors. Massage improves autonomic nervous system development.