Inpatient comparison of wireless and wired pulse oximetry in neonates.

BACKGROUND: To compare oxygen saturation (SpO2) and heart rate (HR) recorded by a reference wired pulse oximeter to a wireless pulse oximeter in inpatient neonates. METHODS: Term infants born≥37 + 0 weeks and preterm infants born≤35 + 0 weeks gestation were enrolled and time-matched data pairs were obtained. The primary outcome was intraclass correlation coefficient and r-values between the two oximeters for heart rate and oxygen saturation. RESULTS: Thirty term and 20 preterm neonates were enrolled. There was a high degree of correlation between the two oximeters for HR (r = 0.926) among all 50 infants, and excellent interclass correlation (ICC = 0.961), but there were no bradycardia episodes in either term or preterm infants. There was a lesser degree of correlation for SpO2 values in the term and preterm groups (r = 0.242; 0.521, respectively) along with moderate interclass correlation (ICC = 0.719) but few episodes of hypoxemia≤90% occurred in enrolled subjects. CONCLUSIONS: There were no significant differences between the wireless and reference wired oximeters for assessing HR. There was less correlation between the two oximeters for monitoring SpO2 in both the term and preterm group. Wireless pulse oximetry may have practical advantages for use in inpatient neonates, but additional studies are needed that include bradycardia and desaturation events to delineate this question.

Caffeine decreases intermittent hypoxia in preterm infants nearing term-equivalent age.

OBJECTIVE: To determine whether intermittent hypoxia (IH) persisting after 36 weeks postmenstrual age (PMA) can be attenuated using caffeine doses sufficient to maintain caffeine concentrations >20 µg ml-1. STUDY DESIGN: Twenty-seven infants born <32 weeks were started on caffeine citrate at 10 mg kg-1 day-1 when clinical caffeine was discontinued. At 36 weeks PMA, the dose was increased to 14 or 20 mg kg-1 day-1 divided twice a day (BID) to compensate for progressively increasing caffeine metabolism. Caffeine concentrations were measured weekly. The extent of IH derived from continuous pulse oximetry was compared to data from 53 control infants. RESULT: The mean (s.d.) gestational age of enrolled infants was 27.9±2 weeks. Median caffeine levels were >20 µg ml-1 on study caffeine doses. IH was significantly attenuated through 38 weeks PMA compared with the control group. CONCLUSION: Caffeine doses of 14 to 20 mg kg-1 day-1 were sufficient to maintain caffeine concentrations >20 µg ml-1 and reduce IH in preterm infants at 36 to 38 weeks PMA.

The clinical utility of anthropometric measures to assess adiposity in a cohort of prematurely born infants: Correlations with MRI fat quantification.

OBJECTIVE: To correlate magnetic resonance imaging (MRI) of body fat in preterm infants at the time of hospital discharge with same-day anthropometric measures, and to assess the clinical utility of body mass index (BMI), waist circumference (WC), and WC/length ratio as indicators of visceral fat. STUDY DESIGN: MRI performed prior to NICU discharge in 25 infants born preterm at <32 weeks gestation. Total body fat and visceral fat were quantified using a commercial software program. The Pearson correlation coefficient (r, 95% C.I.) was used to describe strength of association between MRI fat and anthropometric measures. RESULTS: BMI and weight at discharge were strongly correlated with total body fat (r = 0.95 and 0.89 respectively; p < 0.001). Total body fat as a % of body weight was moderately correlated with weight (r = 0.53), WC (r = 0.52), and BMI (r = 0.47). Weight, BMI, and ponderal index all were found to correlate with total visceral fat (r = 0.65, 0.64, 0.55 respectively) but WC did not (r = 0.28). WC/length ratio was not correlated with any MRI fat measurements. CONCLUSIONS: BMI and weight at discharge both correlate with MRI fat measurements. Our findings do not support the usefulness of measuring WC or WC/length ratio in preterm infants at term-equivalent age.

Anthropometric trends from 1997 to 2012 in infants born at ⩽28 weeks' gestation or less.

OBJECTIVE: Postnatal growth failure is common after preterm birth, in particular for infants born at ⩽28 weeks' gestation, but it is unknown if growth-to-term equivalent age has improved over the years as neonatal intensive care in general, and infant nutrition in particular, have improved. The objective of the study was to evaluate anthropometric trends at NICU discharge for infants born at ⩽28 weeks' gestation using a large national database. STUDY DESIGN: Analysis of growth in weight, length, head circumference and body mass index (kg m2) in 23 005 infants born in 1997 to 2012 who survived to neonatal intensive care unit discharge at ⩽41 weeks' postmenstrual age. RESULTS: Discharge weight, length, head circumference and body mass index were converted to Z-scores using a reference database, and growth trends over the 16 years were summarized. Discharge results also were summarized for common neonatal morbidities, including chronic lung disease. Gestational age at birth and postmenstrual age at discharge were similar across the 16 years. Discharge weight, length and head circumference Z-scores were all below the median, but head circumference Z-scores consistently were closer to the median than were weight and length. In 1997 compared with 2012, the weight Z-score improved from -1.5 to -0.6; the length Z-score increased the least, from -1.68 to just -1.16; the head circumference Z-score improved from -0.68 to -0.30; and the body mass index Z-score increased from -0.66 to 0.19. Percent small-for-gestational age at birth was stable across the years at 8.4 to 9.3%, and the frequency of postnatal growth failure at discharge improved from 55.4% in 1997 to 19.6% in 2012. CONCLUSIONS: Growth-to-discharge progressively improved from 1997 to 2012, but Z-scores remained below the reference median for weight, length and head circumference. Length Z-scores were consistently significantly less than for weight, and body mass index Z-scores have been above the reference median since 2002. Prospective studies are needed to quantify anthropometric trends in relation to body composition and to current nutritional strategies.

Gene-environment interactions: implications for sudden unexpected deaths in infancy.

From the perspective of systems biology, genes and proteins interact to produce complex networks, which in turn interact with the environment to influence every aspect of our biological lives. Recent advances in molecular genetics and the identification of gene polymorphisms in victims of sudden infant death syndrome (SIDS) are helping us better to understand that SIDS, like all other human conditions in health and disease, represents the confluence of specific environmental risk factors interacting in complex ways with specific polymorphisms to yield phenotypes susceptible to sudden and unexpected death in infancy. Failure to consider both genetic and environmental risk factors will impede research progress.

Relationship between infant sleep position and motor development in preterm infants.

To determine whether motor development in premature infants varies according to sleep position, we evaluated 213 infants <1750 g birth weight enrolled in the Collaborative Home Infant Monitoring Evaluation (CHIME). At 56 weeks postconceptional age (PCA), sleep position was determined by maternal report, and the Bayley Scales of Infant Development 2nd Edition (BSID-II) were performed. Infants who slept supine were less likely than infants who slept prone to receive credit for maintaining the head elevated to 45 degrees (p = .021), and infants who slept nonprone were less likely than prone sleepers to receive credit for maintaining the head elevated to 90 degrees and lowering with control (p = .001). The Psychomotor and Mental Development Indices at 56 and 92 weeks PCA were not altered by usual sleep position at 56 weeks PCA. In summary, infants sleeping supine are less able to lift the head and lower with control at 56 weeks PCA, but global developmental status was unaffected. Supine sleeping has been associated with decreased risk for sudden infant death syndrome, but compensatory strategies while awake may be needed to avoid delayed acquisition of head control.

Telephone subsidy: an effective incentive for successful participation in home memory monitor study.

CONTEXT: The Collaborative Home Infant Monitoring Evaluation (CHIME) study enrolled healthy term infants and 3 groups of infants considered to be at increased risk for sudden infant death syndrome to evaluate apnea and bradycardia events in the home. Mother-infant pairs without a telephone were ineligible for enrollment. OBJECTIVE: To determine whether mother-infant pairs who were offered a telephone subsidy would agree to enroll in CHIME and achieve protocol compliance rates comparable with those of matched subjects able to afford telephones. DESIGN: Thirty-one telephone subsidy subjects were retrospectively compared with 55 control subjects matched for study group, site, birth weight, and maternal race, age, and education. SETTING: Collaborative Home Infant Monitoring Evaluation clinical research centers in Honolulu, Hawaii, and Toledo, Ohio. INTERVENTION: Provision of telephone subsidy to otherwise eligible enrollees for CHIME. MAIN OUTCOME MEASURES: Frequency of compliance with protocol requirements for follow-up evaluations and for extent of home monitoring. RESULTS: Subsidy subjects achieved protocol completion rates that were comparable with those of control subjects, for developmental assessments at 56 and 92 weeks postconceptional age (PCA), and for the polysomnogram. Unexpectedly, however, subsidy subjects were more likely to have a developmental assessment at 44 weeks PCA (P =.02), as well as a cry analysis (P =.04). They were also more likely to use the CHIME home monitor for more hours during weeks 2 through 5 (P =.004), have a higher percentage using the monitor for 10 or more hours per week during weeks 2 through 5 (P =.009), and have a higher total number of days of monitor use throughout 6 months (P <.001). Mean cost of the subsidy was $3.25 per day of monitor use, and monitor use per day was directly related to total cost of the subsidy (P =.02). CONCLUSIONS: Telephone subsidy is an effective financial incentive. At least within the context of the CHIME study, telephone subsidy enhanced access to health care, and in some categories it resulted in enhanced protocol compliance.

Cardiopulmonary monitoring at home: the CHIME monitor.

A new physiologic monitor for use in the home has been developed and used for the Collaborative Home Infant Monitor Evaluation (CHIME). This monitor measures infant breathing by respiratory inductance plethysmography and transthoracic impedance; infant electrocardiogram, heart rate and R-R interval; haemoglobin O2 saturation of arterial blood at the periphery and sleep position. Monitor signals from a representative sample of 24 subjects from the CHIME database were of sufficient quality to be clinically interpreted 91.7% of the time for the respiratory inductance plethysmograph, 100% for the ECG, 99.7% for the heart rate and 87% for the 16 subjects of the 24 who used the pulse oximeter. The monitor detected breaths with a sensitivity of 96% and a specificity of 65% compared to human scorers. It detected all clinically significant bradycardias but identified an additional 737 events where a human scorer did not detect bradycardia. The monitor was considered to be superior to conventional monitors and, therefore, suitable for the successful conduct of the CHIME study.

Cardiorespiratory events recorded on home monitors: Comparison of healthy infants with those at increased risk for SIDS.

CONTEXT: Home monitors designed to identify cardiorespiratory events are frequently used in infants at increased risk for sudden infant death syndrome (SIDS), but the efficacy of such devices for this use is unproven. OBJECTIVE: To test the hypothesis that preterm infants, siblings of infants who died of SIDS, and infants who have experienced an idiopathic, apparent life-threatening event have a greater risk of cardiorespiratory events than healthy term infants. DESIGN: Longitudinal cohort study conducted from May 1994 through February 1998. SETTING: Five metropolitan medical centers in the United States. PARTICIPANTS: A total of 1079 infants (classified as healthy term infants and 6 groups of those at risk for SIDS) who, during the first 6 months after birth, were observed with home cardiorespiratory monitors using respiratory inductance plethysmography to detect apnea and obstructed breathing. MAIN OUTCOME MEASURES: Occurrence of cardiorespiratory events that exceeded predefined conventional and extreme thresholds as recorded by the monitors. RESULTS: During 718 358 hours of home monitoring, 6993 events exceeding conventional alarm thresholds occurred in 445 infants (41%). Of these, 653 were extreme events in 116 infants (10%), and of those events with apnea, 70% included at least 3 obstructed breaths. The frequency of at least 1 extreme event was similar in term infants in all groups, but preterm infants were at increased risk of extreme events until 43 weeks' postconceptional age. CONCLUSIONS: In this study, conventional events are quite common, even in healthy term infants. Extreme events were common only in preterm infants, and their timing suggests that they are not likely to be immediate precursors to SIDS. The high frequency of obstructed breathing in study participants would likely preclude detection of many events by conventional techniques. These data should be important for designing future monitors and determining if an infant is likely to be at risk for a cardiorespiratory event.

Longitudinal assessment of hemoglobin oxygen saturation in healthy infants during the first 6 months of age. Collaborative Home Infant Monitoring Evaluation (CHIME) Study Group.

Limitations in home monitoring technology have precluded longitudinal studies of hemoglobin oxygen saturation during unperturbed sleep. The memory monitor used in the Collaborative Home Infant Monitoring Evaluation addresses these limitations. We studied 64 healthy term infants at 2 to 25 weeks of age. We analyzed hemoglobin oxygen saturation by pulse oximetry (SpO(2)), respiratory inductance plethysmography, heart rate, and sleep position during 35, 127 epochs automatically recorded during the first 3 minutes of each hour. For each epoch baseline SpO(2) was determined during >/=10 s of quiet breathing. Acute decreases of at least 10 saturation points and <90% for >/=5 s were identified, and the lowest SpO(2) was noted. The median baseline SpO(2) was 97.9% and did not change with age or sleep position. The baseline SpO(2) was <90% in at least 1 epoch in 59% of infants and in 0.51% of all epochs. Acute decreases in SpO(2) occurred in 59% of infants; among these, the median number of episodes was 4. The median lowest SpO(2) during an acute decrease was 83% (10th, 90th percentiles 78%, 87%); 79% of acute decreases were associated with periodic breathing, and >/=16% were associated with isolated apnea. With the use of multivariate analyses, the odds of having an acute decrease increased as the number of epochs with periodic breathing increased, and they lessened significantly with age. We conclude that healthy infants generally have baseline SpO(2) levels >95%. The transient acute decreases are correlated with younger age, periodic breathing, and apnea and appear to be part of normal breathing and oxygenation behavior.

Medical students' education in the ambulatory care setting: background paper 1 of the Medical School Objectives Project.

The present article is the first MSOP Background Paper. In planning the Medical School Objectives Project (MSOP), the Association recognized that certain changes in medical students' education were occurring already in some schools, and that it would be important to gain insight into and monitor these changes to provide ideas and information to help schools design curricular changes to foster students' achievements of the objectives and recommendations set forth in the MSOP Reports published in 1998 and reprinted in Academic Medicine. This background paper provides an overview of the strategies being developed by medical schools to carry out education in the ambulatory care setting. This report is based on site visits in 1997 to 26 U.S. medical schools conducted by two of the authors (CEH and GAK), who also used information from 12 additional schools that were not visited and consulted individuals responsible for the evaluation of five grant programs dedicated to national curriculum reform. The authors define and discuss in detail the use of the three main strategies that their research uncovered: (1) longitudinal preceptorships, (2) multispecialty clerkships, and (3) activities that are community oriented and population based to provide medical students the kinds of educational experiences they need to understand and practice in the ambulatory care setting. The authors then discuss issues and challenges related to the implementation of these curricular changes: curricular management issues; developing and maintaining a network of practicing physicians willing to serve as preceptors; evaluating curricular innovations; and assessing students' performances. The authors conclude with general observations about the need for ambulatory care education, the difficulties that have been--and continue to be--met and overcome to implement it, and the recommendation that relevant learning experiences should be incorporated into existing course work or clinical experiences.

Trends in clinical education of medical students: implications for pediatrics.

OBJECTIVES: To describe current educational imperatives and trends for curricular changes in the clinical education of medical students and to delineate the nature and extent of participation in these curricular trends by departments of pediatrics. METHODS: Site visits to 26 representative US medical schools and a review of detailed information from 12 additional schools. Evaluation of the core curriculum was developed by the Council on Medical Student Education in Pediatrics within the context of the major curricular trends observed. RESULTS: The major observed curricular trends emphasized community-based ambulatory experiences, continuity of care, integration, and population-based experiences. Supporting educational principles included student-directed learning and performance-based assessments. The 3 major curricular changes were early clinical experiences (longitudinal preceptorships), community-oriented/ population-based experiences, and multispecialty clerkships. The focus of the Council on Medical Student Education in Pediatrics objectives was the year 3 clerkship, and substantive participation by pediatric faculty in the overall curriculum was primarily related to the pediatric clerkship. CONCLUSIONS: Revising the clerkship-based Council on Medical Student Education in Pediatrics guidelines according to the new educational trends will extend clinical curricular opportunities for pediatrics beyond the traditional boundaries of the clerkship. The discipline of pediatrics will, as a consequence, be able to achieve enhanced partnership in the planning, conduct, and evaluation of a clinical curriculum for medical students that is relevant to child health issues and that extends across all 4 years.

Agreement among raters in assessment of physiologic waveforms recorded by a cardiorespiratory monitor for home use. Collaborative Home Infant Monitoring Evaluation (CHIME) Study Group.

There are numerous reports of cardiorespiratory patterns in infants on home monitors, but no data to determine whether "experts" agree on the description of these patterns. Therefore, we evaluated agreement among four experienced investigators and five trained technicians who assessed independently the same sample of physiologic waveforms recorded from infants enrolled in a multicenter study. The monitor used respiratory inductance plethysmography and recorded waveforms for apnea > or = 16 s or a heart rate < 80 beats/min for > or = 5 s. The investigators and technicians initially assessed 88 waveforms. After additional training, the technicians assessed another 113 additional waveforms. In categorizing waveforms as apnea present or absent, agreement among technicians improved considerably with additional training (kappa 0.65 to 0.85). For categorizing waveforms as having bradycardia present versus absent, the trends were the same. Agreement in measurement of apnea duration also improved considerably with additional training (intraclass correlation 0.33-0.83). Agreement in measurement of bradycardia duration was consistently excellent (intraclass correlation 0.86-0.99). Total agreement was achieved among technicians with additional training for measurement of the lowest heart rate during a bradycardia. When classifying apnea as including > or = 1, > or = 2, > or = 3, or > or = 4 out-of-phase breaths, agreement was initially low, but after additional training it improved, especially in categorization of apneas with > or = 3 or > or = 4 out-of-phase breaths (kappa 0.67 and 0.94, respectively). Although researchers and clinicians commonly describe events based on cardiorespiratory recordings, agreement amongst experienced individuals may be poor, which can confound interpretation. With clear guidelines and sufficient training raters can attain a high level of agreement in describing cardiorespiratory events.

Changes in sleep position during infancy: a prospective longitudinal assessment.

CONTEXT: Prone sleeping by infants has been associated with an increased risk of sudden infant death syndrome. OBJECTIVE: To document the prevalence of and identify risk factors for prone sleeping during the first 6 months of life. DESIGN: Prospective cohort study. SETTING: Eastern Massachusetts and northwest Ohio. STUDY PARTICIPANTS: A total of 7796 mothers of infants weighing 2500 g or more at birth. MAIN OUTCOME MEASURES: Maternal and infant characteristics related to prone sleeping at 1 month and 3 months of age. RESULTS: Between 1 month and 3 months of age, prone sleeping increased from 18% to 29%. At 1 month, prone sleeping was associated with the following maternal characteristics: non-Hispanic black or Hispanic race/ethnicity, younger age, less education, and higher parity. At 3 months, switching from nonprone to prone position was associated with mother's race/ethnicity of non-Hispanic black (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.2-2.3) or Hispanic (OR, 1.5; 95% CI, 1.1-2.2); younger maternal age (compared with mothers >34 years: 18-24 years, OR, 1.6; 95% CI, 1.2-2.2; <18 years, OR, 2.2; 95% CI, 1.2-4.3); increasing parity (compared with 1 child: 2 children, OR, 1.5; 95% CI, 1.2-1.8; > or =3 children, OR, 1.7; 95% CI, 1.4-2.2); and infant sex (male sex, OR, 1.4; 95% CI, 1.2-1.7). CONCLUSIONS: If infant sleeping practices in the study communities are representative of practices throughout the United States, a substantial number of infants who slept nonprone at 1 month sleep prone at 3 months.

Pediatric hypoventilation syndromes.

Hypoventilation syndromes are an uncommon but important group of respiratory control disorders in infants and children. Congenital central hypoventilation syndrome (CCHS) is the principal and most important example. No specific anatomical or biochemical mechanism has yet been identified. This article summarizes current knowledge regarding CCHS in infants and children, and emphasizes the most recent and most important publications. The most recent advances in CCHS pertain to its genetics, pathophysiology, diagnosis, and treatment and provide state-of-the-art information regarding advances in diaphragm pacing, responses to exercise, and long-term outcome. CCHS is now being recognized more frequently, treatment is more successful, and long-term outcomes are encouraging with timely diagnosis, state-of-the-art treatment, and comprehensive follow-up at an experienced pediatric referral center.

Infant polysomnography: reliability. Collaborative Home Infant Monitoring Evaluation (CHIME) Steering Committee.

Infant polysomnography (IPSG) is an increasingly important procedure for studying infants with sleep and breathing disorders. Since analyses of these IPSG data are subjective, an equally important issue is the reliability or strength of agreement among scorers (especially among experienced clinicians) of sleep parameters (SP) and sleep states (SS). One basic issue of this problem was examined by proposing and testing the hypothesis that infant SP and SS ratings can be reliably scored at substantial levels of agreement, that is, kappa (kappa) > or = 0.61. In light of the importance of IPSG reliability in the collaborative home infant monitoring evaluation (CHIME) study, a reliability training and evaluation process was developed and implemented. The bases for training on SP and SS scoring were CHIME criteria that were modifications and supplements to Anders, Emde, and Parmelee (10). The kappa statistic was adopted as the method for evaluating reliability between and among scorers. Scorers were three experienced investigators and four trainees. Inter- and intrarater reliabilities for SP codes and SSs were calculated for 408 randomly selected 30-second epochs of nocturnal IPSG recorded at five CHIME clinical sites from healthy full term (n = 5), preterm (n = 4), apnea of infancy (n = 2), and siblings of the sudden infant death syndrome (SIDS) (n = 4) enrolled subjects. Infant PSG data set 1 was scored by both experienced investigators and trained scorers and was used to assess initial interrater reliability. Infant PSG data set 2 was scored twice by the trained scorers and was used to reassess inter-rater reliability and to assess intrarater reliability. The kappa s for SS ranged from 0.45 to 0.58 for data set 1 and represented a moderate level of agreement. Therefore, rater disagreements were reviewed, and the scoring criteria were modified to clarify ambiguities. The kappa s and confidence intervals (CIs) computed for data set 2 yielded substantial inter-rater and intrarater agreements for the four trained scorers; for SS, the kappa = 0.68 and for SP the kappa s ranged from 0.62 to 0.76. Acceptance of the hypothesis supports the conclusion that the IPSG is a reliable source of clinical and research data when supported by significant kappa s and CIs. Reliability can be maximized with strictly detailed scoring guidelines and training.