Quantifying physiological vital sign differences in newborns from 34+0/7 weeks of gestation and establishment of vital sign reference ranges for the late preterm population

Abstract

BackgroundTo ensure continued adaptation to extra-uterine life, all newborns have their physiological vital signs monitored intermittently post birth until discharge; these are tracked against predefined 'normal' reference ranges. Ascertaining an evidence base for 'normal' reference ranges is important for the early detection of deterioration in this population, who are at risk of not adapting to the extra-uterine environment due to being born prior to term. AimThe studies in this thesis aim to determine physiological vital sign reference ranges for well newborns between 34 +0/7 and 36 +6/7 weeks of gestation. ObjectivesThe objectives of the studies in this thesis were to: systematically summarise the evidence in peer-reviewed literature on physiological vital sign reference ranges for well newborns greater than or equal to 34 weeks of gestation; to review contemporary neonatal and midwifery textbooks and publicly available grey literature (i.e. organisational websites, hospital policies and early warning tools) for vital sign reference ranges pertaining to well newborns of ≥ 34 +0/7 weeks of gestation; to determine whether there are differences in vital signs in gestational age groups; and, if differences are identified, to establish physiological vital sign reference ranges for the well late preterm group and validate the reference ranges. Research DesignA systematic review of literature was initially undertaken followed by a scoping review of textbooks and grey literature to identify vital sign reference ranges for newborns ≥ 34 +0/7 weeks of gestation. Quantitative research methods were used to meet the remaining study objectives. Study One was conducted as a single site prospective observational study of 30 newborns, comprised of three gestational age groups: late preterm (34 +0/7 -36 +6/7 ), early term (37 +0/7 -38 +6/7 ), and term (39 +0/7 -40 +6/7 ). This involved continuously recording heart rate, respiratory rate, and peripheral oxygen saturation for up to six hours and periodic monitoring of temperature and blood pressure to determine whether physiological vital signs differed between the groups. The results of Study One informed the design of Study Two. This involved a shorter recording time of up to two hours and periodic monitoring of ii 0 Abstract temperature and blood pressure on 120 well, late preterm newborns in a single site prospective observational study. The reference ranges established in Study Two underwent validation in Study Three, in which a cross-sectional design was used to validate the data with data from the medical records of a group of late preterm newborns. ResultsThe searches of literature resulted in primary studies (n = 10), textbooks (n = 7) and grey literature (n = 11). Inconsistencies in and a dearth of vital sign ranges for gestational age groups other than term were identified. Details of how reference ranges were calculated were only provided in the peer reviewed literature.Study One generated a combined total of 284,542 heart rate values, 275,826 respiratory rate values...

Physiological vital sign reference ranges for well late preterm newborns calculated during a typical 2 h newborn period between 2 h and 7 days of life

“…We did not find significant heart rate differences between sex and mode of birth. This finding is similar to our pilot study (Paliwoda et al 2020) which used continuous data recording for up to 6 h (males 122.2 bpm (95% CI 118.6-125.9), females 129.9 bpm (95% CI 125.4-134.4)). Similarly, (Sadoh and Sadoh 2012) did not report differences between the sexes using intermittent data collection over 3 min intervals, with male (133 bpm, range 95-189) and female (133 bpm, range 90-172) heart rates being similar.…”

“…Exploratory analysis of sex and mode of birth Exploratory analyses of sex and mode of birth were undertaken due to suggestive findings of Study One, and the previous work of others (Rosvik et al 2009, Tveiten et al 2016, Paliwoda et al 2020. Exploratory analysis for sex and mode of birth is reported in table 6.…”

“…A search of peer-reviewed and grey literature revealed little guidance for reference ranges for gestations other than term. It appears from the literature that normal physiological vital sign measurements, such as heart rate, respiratory rate and temperature, applied to the late preterm are based on term newborn values (Paliwoda et al 2018, Paliwoda 2020). These values have been applied to early warning tools and adopted by healthcare facilities.…”

“…These values have been applied to early warning tools and adopted by healthcare facilities. While this may be due to the lack of empirical evidence for preterm 'normal' ranges (Paliwoda 2020), it may result in over-treatment or delayed identification of subtle early signs of deterioration. A recent pilot study demonstrated that heart rate was significantly different between gestational age groups with late preterm heart rates 13.4 bpm (95% CI 6.5-20.4) higher on average than term newborns (Paliwoda et al 2020).…”

“…While this may be due to the lack of empirical evidence for preterm 'normal' ranges (Paliwoda 2020), it may result in over-treatment or delayed identification of subtle early signs of deterioration. A recent pilot study demonstrated that heart rate was significantly different between gestational age groups with late preterm heart rates 13.4 bpm (95% CI 6.5-20.4) higher on average than term newborns (Paliwoda et al 2020). This paper reports on a larger study to calculate physiological vital sign reference ranges for well late preterm newborns during a period of typical newborn behaviours such as sleeping, crying, being awake and alert, hygiene cares, feeding and cuddling.…”