Statistical modeling of heart rate variability to unravel the factors affecting autonomic regulation in preterm infants

\u3cp\u3eAnalyzing heart rate variability (HRV) in preterm infants can help track maturational changes and subclinical signatures of disease. We conducted an observational study to characterize the effect of demographic and cardiorespiratory factors on three features of HRV using a linear mixed-effects model. HRV-features were tailored to capture the unique physiology of preterm infants, including the contribution of transient pathophysiological heart rate (HR) decelerations. Infants were analyzed during stable periods in the incubator and subsequent sessions of Kangaroo care (KC) - an intervention that increases comfort. In total, 957 periods in the incubator and during KC were analyzed from 66 preterm infants. Our primary finding was that gestational age (GA) and postmenstrual age (PMA) have the largest influence on HRV while the HR and breathing rate have a considerably smaller effect. Birth weight and gender do not affect HRV. We identified that with increasing GA and PMA, overall HRV decreased and increased respectively. Potentially these differences can be attributed to distinct trajectories of intra- and extrauterine development. With increasing GA, the propensity towards severe HR decelerations decreases, thereby reducing overall variability, while with increasing PMA, the ratio of decelerations and accelerations approaches unity, increasing overall HRV.\u3c/p\u3

A strategy to reduce critical cardiorespiratory alarms due to intermittent enteral feeding of reterm neonates in intensive care

\u3cp\u3eBACKGROUND: Many preterm infants require enteral feeding as they cannot coordinate sucking, swallowing, and breathing. In enteral feeding, milk feeds are delivered through a small feeding tube passed via the nose or mouth into the stomach. Intermittent milk feeds may either be administered using a syringe to gently push milk into the infant's stomach (push feed) or milk can be poured into a syringe attached to the tube and allowed to drip in by gravity (gravity feed). This practice of enteral feeding is common in neonatal intensive care units. There is, however, no evidence in the literature to recommend the use of one method of feeding over the other.\u3c/p\u3e\u3cp\u3eOBJECTIVE: The aim of this study was to investigate which of the two methods of feeding is physiologically better tolerated by infants, as measured by the incidence of critical cardiorespiratory alarms during and immediately after feeding.\u3c/p\u3e\u3cp\u3eMETHODS: We conducted a prospectively designed observational study with records of all feeding episodes in infants of gestational age less than 30 weeks at birth and with a minimum enteral intake of 100 mL/kg/day. In total, 2140 enteral feeding episodes were noted from 25 infants over 308 infant-days with records for several characteristics of the infants (eg, gestational age), feeding (eg, the position of infants), and of nursing-care events before feeding (eg, diapering). Logistic regression with mixed effects was used to model cardiorespiratory alarms for the push and gravity methods of feeding.\u3c/p\u3e\u3cp\u3eRESULTS: After adjustments were made for all confounding variables, the position of infants was found to be statistically significant in changing the outcome of critical alarms for the two methods of feeding (P=.02). For infants in the lateral position, push feeds led to 40% more instances of one or more critical cardiorespiratory alarms in comparison with the gravity method. Both methods of feeding created a statistically comparable number of alarms for infants in the prone position.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: This study provides objective data that may assist in optimizing enteral feeding protocols for premature infants. The incidence of critical cardiorespiratory alarms for infants in the lateral position can be lowered by the use of gravity instead of push feeding. No differences were observed between the two types of feeding when infants were in the prone position.\u3c/p\u3

Patient room lighting influences on sleep, appraisal and mood in hospitalized people

\u3cp\u3eIrregular 24 h light/dark cycles with night-time light exposure and a low amplitude are disruptive for sleep, mood and circadian rhythms. Nevertheless such lighting conditions are quite common in medical care facilities. A controlled clinical trial among 196 cardiology ward patients (mean age 66.5 ± 13.1 years SD) investigated how a patient room lighting intervention affects sleep, appraisal and mood across hospitalization. Patients were either assigned to a standardly-lit room or to a room with an interventional lighting system offering a dynamic 24 h light/dark cycle with low nocturnal light exposure and 2 h of bright light (1750 lux) during daytime. Measures included wrist actigraphy and questionnaires assessing alertness, sleep quality, anxiety, depression and lighting appraisal. The median length of hospitalization was 5 days in both study arms. Subjective scores on sleep, alertness, anxiety and depression did not differ between arms. Lighting appraisal in intervention rooms was better as compared to standardly-lit rooms, both in patients (P < 0.001) and staff (P < 0.005). Actigraphic sleep duration of patients improved by 5.9 min (95% CI: 0.6–11.2; P = 0.03 intervention × time effect) per hospitalization day with interventional lighting instead of standard lighting. After 5 days of hospitalization, sleep duration in the lighting intervention rooms increased by 29 min, or a relative 7.3%, as compared to standardly-lit rooms. A 24 h lighting system with enhanced daytime brightness and restricted nocturnal light exposure can improve some aspects of appraisal and objective sleep in hospital patients. More clinical research is needed to establish the best lighting strategy to promote healing and wellbeing within healthcare settings.\u3c/p\u3