Effect of positioning on the breathing pattern of preterm infants

Higher awakening threshold of preterm infants in prone position may be a risk factor for SIDS

AIM

The supine sleeping position in the prevention of sudden infant death syndrome in preterm infants is poorly understood. We aimed to investigate the effect of sleep posture on cardiorespiratory parameters and movement patterns in preterm infants close to discharge.

METHODS

This observational study included neonates born in 2022 at the University Hospital Schleswig-Holstein, Lübeck, Germany. Motion sensor data, heart rate, respiratory rate and oxygen saturation were recorded for infants with postconceptional age 35-37 weeks during sleep in the prone and supine positions.

RESULTS

We recorded data from 50 infants, born at 31 (24-35) weeks of gestation (mean(range)), aged 5.2 ± 3.7 weeks (mean ± SD), of whom 48% were female. Five typical movement patterns were identified. In the prone position, the percentage of calm, regular breathing was higher and active movement was less frequent when compared to the supine position. The percentage of calm irregular breathing, number of apnoeas, bradycardias, desaturations and vital sign changes were not influenced by position.

CONCLUSION

The prone position seems to be associated with a higher arousal threshold. The supine position appears advantageous for escape from life-threatening situations such as sudden infant death syndrome.

Transition to a Safe Home Sleep Environment for the NICU Patient

Of the nearly 3.8 million infants born in the United States in 2018, 8.3% had low birth weight (ie, weight <2500 g) and 10% were born preterm (ie, gestational age of <37 weeks). Ten to fifteen percent of infants (approximately 500 000 annually), including low birth weight and preterm infants and others with congenital anomalies, perinatally acquired infections, and other diseases, require admission to a NICU. Every year, approximately 3600 infants in the United States die of sudden unexpected infant death (SUID), including sudden infant death syndrome (SIDS), unknown and undetermined causes, and accidental suffocation and strangulation in an unsafe sleep environment. Preterm and low birth weight infants are 2 to 3 times more likely than healthy term infants to die suddenly and unexpectedly. Thus, it is important that health care professionals prepare families to maintain their infant in a safe home sleep environment as per recommendations of the American Academy of Pediatrics. Medical needs of the NICU infant often require practices such as nonsupine positioning, which should be transitioned as soon as medically possible and well before hospital discharge to sleep practices that are safe and appropriate for the home environment. This clinical report outlines the establishment of appropriate NICU protocols for the timely transition of these infants to a safe home sleep environment. The rationale for these recommendations is discussed in the accompanying technical report "Transition to a Safe Home Sleep Environment for the NICU Patient," included in this issue of Pediatrics.

Transition to a Safe Home Sleep Environment for the NICU Patient

Of the nearly 3.8 million infants born in the United States in 2018, 8.3% had low birth weight (<2500 g [5.5 lb]) and 10% were born preterm (gestational age of <37 completed weeks). Many of these infants and others with congenital anomalies, perinatally acquired infections, and other disease require admission to a NICU. In the past decade, admission rates to NICUs have been increasing; it is estimated that between 10% and 15% of infants will spend time in a NICU, representing approximately 500 000 neonates annually. Approximately 3600 infants die annually in the United States from sleep-related deaths, including sudden infant death syndrome International Classification of Diseases, 10th Revision (R95), ill-defined deaths (R99), and accidental suffocation and strangulation in bed (W75). Preterm and low birth weight infants are particularly vulnerable, with an incidence of death 2 to 3 times greater than healthy term infants. Thus, it is important for health care professionals to prepare families to maintain their infant in a safe sleep environment, as per the recommendations of the American Academy of Pediatrics. However, infants in the NICU setting commonly require care that is inconsistent with infant sleep safety recommendations. The conflicting needs of the NICU infant with the necessity to provide a safe sleep environment before hospital discharge can create confusion for providers and distress for families. This technical report is intended to assist in the establishment of appropriate NICU protocols to achieve a consistent approach to transitioning NICU infants to a safe sleep environment as soon as medically possible, well before hospital discharge.

Effects of Different Body Positions and Head Elevation Angles on Regional Cerebral Oxygen Saturation in Premature Infants of China

BACKGROUND

To investigate the effects of different body positions and head elevation angles on regional cerebral oxygen saturation in premature infants using near-infrared spectroscopy (NIRS).

METHODS

This was a prospective study of premature infants hospitalized. The position was changed each feeding cycle (2-3 h), in order: 15° prone, 15° supine, 0° prone, and 0° supine position. Regional cerebral oxygen saturation (rSO₂) was measured after each position period using NIRS, over 7 days.

FINDINGS

Thirty-three premature infants were included in the analysis. Among them, 22 (66.7%) were male, and 11 (33.3%) were female. When placing the premature infants in the prone position, the regional cerebral oxygen saturation (rSO₂) values were higher at head elevation 15° compared with 0° (main effect P < 0.001). When placing the premature infants in the supine position, rSO2 was higher at a head elevation of 15° compared with that at 0° (main effect P < 0.001). When placing the premature infants with a head elevation of 15°, rSO2 in the prone position was higher than that of the supine position (main effect P < 0.001). There was no difference between the prone and supine positions when placing the premature infants with the head elevation at 0° (P > 0.05).

DISCUSSION

Higher cerebral rSO2 can be achieved when placing premature infants in the prone or supine position, with a 15° head elevation angle.

APPLICATION TO PRACTICE

Using a specific body position and head angle could improve the regional cerebral oxygen saturation of premature infants.

Systematic review and meta-analysis suggest that Kangaroo position protects against apnoea of prematurity

AIM

The aim of this study was to determine whether the Kangaroo position decreased apnoea events in preterm newborns compared with conventional care in incubator.

METHODS

We conducted a systematic review of clinical trials published in English, French, Spanish and Portuguese. A comprehensive literature search was realised until 2017. The main outcome was apnoea events. Data were extracted and combined in a fixed-effects model. The quality of the evidence was assessed according to the GRADE framework (grading the quality of evidence and the strength of recommendations).

RESULTS

Four original clinical trials were selected. These trials were conducted in India and Nepal, between 2005 and 2016. The systematic review comprised 416 preterm newborns. Three studies were randomised controlled trials and one was quasi-experimental. Meta-analysis showed a statistically significant reduction in apnoea episodes (relative risk [RR] 0.41; 95% confidence interval [CI] 0.22, 0.78). The result remained significant when only the three clinical trials were analysed (RR 0.43; 95% CI 0.23, 0.83). Quality analysis indicated moderate quality because of lack of an appropriate method of randomisation in one study.

CONCLUSION

The Kangaroo position could have protective effect against apnoea events in preterm infants, decreasing the associated risk of death or long-term disability.

When does prone sleeping improve cardiorespiratory status in preterm infants in the NICU?

Study Objectives

Preterm infants undergoing intensive care are often placed prone to improve respiratory function. Current clinical guidelines recommend preterm infants are slept supine from 32 weeks’ postmenstrual age, regardless of gestational age at birth. However, respiratory function is also related to gestational and chronological ages and is affected by sleep state. We aimed to identify the optimal timing for adopting the supine sleeping position in preterm infants, using a longitudinal design assessing the effects of sleep position and state on cardiorespiratory stability.

Methods

Twenty-three extremely (24–28 weeks’ gestation) and 33 very preterm (29–34 weeks’ gestation) infants were studied weekly from birth until discharge, in both prone and supine positions, in quiet and active sleep determined by behavioral scoring. Bradycardia (heart rate ≤100 bpm), desaturation (oxygen saturation ≤80%), and apnea (pause in respiratory rate ≥10 s) episodes were analyzed.

Results

Prone positioning in extremely preterm infants reduced the frequency of bradycardias and desaturations and duration of desaturations. In very preterm infants, prone positioning only reduced the frequency of desaturations. The position-related effects were not related to postmenstrual age. Quiet sleep in both preterm groups was associated with fewer bradycardias and desaturations, and also reduced durations of bradycardia and desaturations in the very preterm group.

Conclusions

Cardiorespiratory stability is improved by the prone sleep position, predominantly in extremely preterm infants, and the improvements are not dependent on postmenstrual age. In very preterm infants, quiet sleep has a more marked effect than the prone position. This evidence should be considered in individualizing management of preterm infant positioning.

Body positioning for spontaneously breathing preterm infants with apnoea

BACKGROUND

It has been proposed that body positioning in preterm infants, as compared with other, more invasive measures, may be an effective method of reducing clinically significant apnoea.

OBJECTIVES

To determine effects of body positioning on cardiorespiratory parameters in spontaneously breathing preterm infants with clinically significant apnoea.Subgroup analyses examined effects of body positioning of spontaneously breathing preterm infants with apnoea from the following subgroups.• Gestational age < 28 weeks or birth weight less than 1000 grams.• Apnoea managed with methylxanthines.• Frequent apnoea (> 10 events/d).• Type of apnoea measured (central vs mixed vs obstructive)

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group (CNRG) to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 10), MEDLINE via PubMed (1966 to 14 November 2016), Embase (1980 to 14 November 2016) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 2016 November 14). We also searched clinical trials databases and conference proceedings for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

Randomised and quasi-randomised controlled clinical trials with parallel, factorial or cross-over design comparing the impact of different body positions on apnoea in spontaneously breathing preterm infants were eligible for our review.

DATA COLLECTION AND ANALYSIS

We assessed trial quality, data extraction and synthesis of data using standard methods of the CNRG. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence.

MAIN RESULTS

The search conducted in November 2016 identified no new studies. Five studies (N = 114) were eligible for inclusion. None of the individual studies nor meta-analyses showed a reduction in apnoea, bradycardia, oxygen desaturation or oxygen saturation with body positioning (supine vs prone; prone vs right lateral; prone vs left lateral; right lateral vs left lateral; prone horizontal vs prone head elevated; right lateral horizontal vs right lateral head elevated, left lateral horizontal vs left lateral head elevated).

AUTHORS' CONCLUSIONS

We found insufficient evidence to determine effects of body positioning on apnoea, bradycardia and oxygen saturation in preterm infants. No new studies have been conducted since the original review was published. Large, multi-centre studies are warranted to provide conclusive evidence, but it may be plausible to conclude that positioning of spontaneously breathing preterm infants has no effect on their cardiorespiratory parameters.

Influence of prone positioning on premature newborn infant stress assessed by means of salivary cortisol measurement: pilot study

Objective

This study sought to assess the influence of prone positioning on the stress of newborn premature infants through the measurement of the salivary cortisol concentration and the evaluation of physiological and behavioral responses before and after changes in body positioning.

Methods

Saliva samples were collected from newborn infants at two different times: the first (corresponding to the baseline) after a period of 40 minutes during which the infants were not subjected to any manipulation and were placed in the lateral or supine position, and the second 30 minutes after placement in the prone position. Variables including heart rate, respiratory rate, peripheral oxygen saturation, and the Brazelton sleep score were recorded before, during, and at the end of the period in the prone position.

Results

The sample comprised 16 newborn premature infants (56.3% male) with a gestational age between 26 and 36 weeks, postnatal age between 1 and 33 days, birth weight of 935 to 3,050g, and weight at the time of intervention of 870 to 2,890g. During the intervention, six participants breathed room air, while the remainder received oxygen therapy. The median salivary cortisol concentration was lower in the prone position compared to baseline (0.13 versus 0.20; p=0.003), as was the median Brazelton sleep score (p=0.02). The average respiratory rate was lower after the intervention (54.88±7.15 versus 60±7.59; p=0.0004). The remainder of the investigated variables did not exhibit significant variation.

Conclusion

Prone positioning significantly reduced the salivary cortisol level, respiratory rate, and Brazelton sleep score, suggesting a correlation between prone positioning and reduction of stress in preterm infants.

The longitudinal effects of persistent periodic breathing on cerebral oxygenation in preterm infants

OBJECTIVES

Periodic breathing is common in preterm infants, but is thought to be benign. The aim of our study was to assess the incidence and impact of periodic breathing on heart rate (HR), oxygen saturation (SpO2), and brain tissue oxygenation index (TOI) over the first six months after term-equivalent age.

STUDY DESIGN

Twenty-four preterm infants (27-36 weeks gestational age) were studied with daytime polysomnography in quiet sleep (QS) and active sleep (AS) and in both the prone and supine positions at 2-4 weeks, 2-3 months, and 5-6 months post-term corrected age. HR, SpO2, and TOI (NIRO-200 spectrophotometer) were recorded. Periodic breathing episodes were defined as greater than or equal to three sequential apneas each lasting ≥3 s.

RESULTS

A total 164 individual episodes of periodic breathing were recorded in 19 infants at 2-4 weeks, 62 in 12 infants at 2-3 months, and 35 in 10 infants at 5-6 months. There was no effect of gestational age on periodic breathing frequency or duration. Falls in HR (-21.9 ± 2.7%) and TOI (-13.1 ± 1.5%) were significantly greater at 2-3 months of age compared to 2-4 weeks of age.

CONCLUSIONS

The majority of preterm infants discharged home without clinical respiratory problems had persistent periodic breathing. Although in most infants periodic breathing was not associated with significant falls in SpO2 or TOI, several infants had significant desaturations and reduced cerebral oxygenation especially during AS. The clinical significance of this on neurodevelopmental outcome is unknown and warrants further investigations.

Effect of body position on preterm newborns receiving continuous positive airway pressure

AIM

To evaluate the effect of body position on the cardiorespiratory indicators of preterm newborns receiving nasal continuous positive airway pressure (CPAP).

METHODS

Analytical, observational, prospective, cross-sectional, randomised crossover study was carried out on sixteen newborns that received nasal CPAP. The infants had a mean gestational age of 29.7 ± 2 weeks and birthweight of 1353 ± 280 g. Cardiorespiratory indicators (respiratory rate, heart rate and oxygen saturation) were evaluated in each infant in the supine, prone and right and left lateral decubitus positions at intervals of 10 min over a period of 60 min.

RESULTS

The cardiorespiratory indicators were similar and within the normal range in the four decubitus positions. There was no difference in respiratory or heart rate between body positions. Although they showed desirable values, oxygen saturation was significantly lower in left lateral decubitus (96.6 ± 1.7%) when compared to the supine (97.1 ± 1.3%) and prone positions (97.4 ± 1.1%) (p = 0.00) and was also significantly lower in right lateral decubitus (96.9 ± 1.4%) when compared to the prone position (p = 0.00).

CONCLUSION

We found no preferential decubitus position for preterm newborns receiving nasal CPAP, the supine position may be a choice, but the left and right lateral positions were less advantageous in terms of oxygen saturation.

Positioning effects on lung function and breathing pattern in premature newborns

OBJECTIVE

To compare breathing patterns and lung function in the supine, lateral, and prone positions in oxygen-dependent preterm infants.

STUDY DESIGN

Respiratory function in preterm infants receiving nasal continous positive airway pressure therapy for mild respiratory failure was evaluated by respiratory inductive plethysmography. Infants were randomized to supine, left lateral, and prone positions for 3 hours. A nest provided a semiflexed posture for the infants placed in the left lateral position, similar to the in utero position. Tidal volume (Vt), phase angle between abdominal and thoracic movements, rib cage contribution to Vt, and dynamic elevation of end-expiratory lung volume were measured.

RESULTS

Fraction of inspired O2 was similar in the 3 positions for 19 infants (mean gestational age, 27±2 weeks; mean birth weight, 950±150 g; mean postnatal age, 17±5 days). However, arterial O2 saturation and Vt were higher in the left lateral and prone positions than in the supine position (P<.05). The phase angle between abdominal and thoracic movements was lower and rib cage contribution to Vt was higher in the left lateral and prone positions than in the supine position (P<.05). Dynamic elevation of end-expiratory lung volume was greater in the supine position than in the left lateral and prone positions (P<.05).

CONCLUSION

In oxygen-dependent preterm infants, both the left lateral and prone positions improve lung function by optimizing breathing strategy. In the neonatal intensive care unit, the left lateral position can be used as an alternative to the prone position for mild respiratory failure.

Physical therapy observation and assessment in the neonatal intensive care unit

This article presents the elements of the Observation and Assessment section of the Infant Care Path for Physical Therapy in the Neonatal Intensive Care Unit (NICU). The types of physical therapy assessments presented in this path are evidence-based and the suggested timing of these assessments is primarily based on practice knowledge from expert therapists, with supporting evidence cited. Assessment in the NICU begins with a thorough review of the health care record. Assessment proceeds by using the least invasive methods of gathering the behavioral, developmental, physiologic, and musculoskeletal information needed to implement a physical therapy plan of care. As the neonate matures and can better tolerate handling, assessment methods include lengthier standardized tests with the psychometric properties needed for informing diagnosis and intervention planning. Standardized tests and measures for screening, diagnosis, and developmental assessment are appraised and special considerations for assessment of neonates in the NICU are discussed.

Physical therapy intervention in the neonatal intensive care unit

This article presents the elements of the Intervention section of the Infant Care Path for Physical Therapy in the Neonatal Intensive Care Unit (NICU). The types of physical therapy interventions presented in this path are evidence-based and the suggested timing of these interventions is primarily based on practice knowledge from expert therapists, with supporting evidence cited. Physical therapy intervention in the NICU is infant-driven and focuses on providing family-centered care. In this context, interventions to facilitate a calm behavioral state and motor organization in the infant, address positioning and handling of the infant, and provide movement therapy are presented.

Positioning for acute respiratory distress in hospitalised infants and children

BACKGROUND

Because of the association of prone positioning with sudden infant death syndrome (SIDS) it is recommended that young infants be placed on their backs (supine). However, the prone position may be a non-invasive way of increasing oxygenation in participants with acute respiratory distress. Because of substantial differences in respiratory mechanics between adults and children and the risk of SIDS in young infants, a specific review of positioning for infants and young children with acute respiratory distress is warranted.

OBJECTIVES

To compare the effects of different body positions in hospitalised infants and children with acute respiratory distress.

SEARCH METHODS

We searched Cochrane Central Register of Controlled Trials (CENTRAL 2012, Issue 3), which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to April week 1, 2012), EMBASE (2004 to April 2012) and CINAHL (2004 to April 2012).

SELECTION CRITERIA

Randomised controlled trials (RCTs) or pseudo-RCTs comparing two or more positions in the management of infants and children hospitalised with acute respiratory distress.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from each study. We resolved differences by consensus or referral to a third review author. We analysed bivariate outcomes using an odds ratio and 95% confidence interval (CI). We analysed continuous outcomes using a mean difference and 95% CI. We used a fixed-effect model unless heterogeneity was significant, in which case we used a random-effects model.

MAIN RESULTS

We extracted data from 53 studies. We included 24 studies with a total of 581 participants. Three studies used a parallel-group, randomised design which compared prone and supine positions only. The remaining 21 studies used a randomised cross-over design. These studies compared prone, supine, lateral, elevated and flat positions.Prone positioning was significantly more beneficial than supine positioning in terms of oxygen saturation (mean difference (MD) 1.97%, 95% CI 1.18 to 2.77), arterial oxygen (MD 6.24 mm Hg, 95% confidence interval (CI) 2.20 to 10.28), episodes of hypoxaemia (MD -3.46, 95% CI -4.60 to -2.33) and thoracoabdominal synchrony (MD -30.76, 95% CI -41.39 to -20.14). No adverse effects were identified. There were no statistically significant differences between any other positions.As the majority of studies did not describe how possible biases were addressed, the potential for bias in these findings is unclear.

AUTHORS' CONCLUSIONS

The prone position was significantly superior to the supine position in terms of oxygenation. However, as most participants were ventilated preterm infants, the benefits of prone positioning may be most relevant to these infants. In addition, although placing infants and children in the prone position may improve respiratory function, the association of SIDS with prone positioning means that infants should only be placed in this position while under continuous cardiorespiratory monitoring.

Body positioning for spontaneously breathing preterm infants with apnoea

BACKGROUND

It has been proposed that the use of body positioning may be a more effective way to reduce clinically significant apnoea than the use of more invasive measures.

OBJECTIVES

To determine the effect of body positioning on cardiorespiratory functioning in spontaneously breathing preterm infants with clinically significant apnoea.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2011), MEDLINE (1966 to March 2011), EMBASE (1988 to March 2011) and CINAHL (1988 to March 2011), abstracts of conference proceedings and citations of published articles.

SELECTION CRITERIA

All studies in which infants or their sequence of body positioning was randomised or quasi-randomised. We included cross-over studies.

DATA COLLECTION AND ANALYSIS

We performed assessment of trial quality, data extraction and synthesis of data using standard methods of the Cochrane Neonatal Review Group.

MAIN RESULTS

Five studies (N = 114) were eligible for inclusion. None of the individual studies or the meta-analyses showed a reduction in apnoea, bradycardia, oxygen desaturation or oxygen saturation with body positioning (supine versus prone; prone versus right lateral; prone versus left lateral; right lateral versus left lateral; prone horizontal versus prone head elevated; right lateral horizontal versus right lateral head elevated and left lateral horizontal versus left lateral head elevated).

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine the role of body positioning on apnoea, bradycardia, oxygen desaturation and oxygen saturation. Large randomised controlled trials are needed to determine the effect of body positioning on cardiorespiratory function in spontaneously breathing preterm infants.

Influência da posição prona na oxigenação, frequência respiratória e na força muscular nos recém-nascidos pré-termo em desmame da ventilação mecânica

OBJETIVO: Verificar a influência do posicionamento do recém-nascido prematuro sobre a força da musculatura respiratória, oxigenação e frequência respiratória. MÉTODOS: Estudo transversal com amostra pareada de recém-nascidos com idade gestacional inferior a 34 semanas, intubados, em processo final de desmame de ventilação mecânica. Foram excluídos aqueles com malformações, síndromes genéticas, doenças neuromusculares, traqueostomizados e em pós-operatório de cirurgias abdominais ou torácicas. As medidas de pressão inspiratória máxima foram aferidas utilizando-se manovacuômetro digital; a frequência respiratória através da observação das incursões respiratórias das crianças em um minuto e a saturação de oxigênio por oxímetro, nas posturas prona e supino. Os testes estatísticos aplicados foram Kruskal-Wallis, o teste t de Student e o coeficiente de correlação de Pearson, sendo significante p<0,05. RESULTADOS: Foram estudadas 45 crianças com síndrome do desconforto respiratório. A idade gestacional média foi de 30,4 semanas e o peso médio ao nascer de 1522g. Os valores de saturação de oxigênio foram mais elevados (p<0,001) e os de pressão inspiratória máxima mais baixos (p<0,001) na posição prona. Os valores de frequência respiratória foram semelhantes nas duas posições estudadas (p=0,072). CONCLUSÕES: Observaram-se menores valores de pressão inspiratória além de aumento da saturação de oxigênio na posição prona quando comparada à supino. Em relação à frequência respiratória, não foi observada variação entre as posturas prona e supino.

Effects of prone and supine position on cerebral blood flow in preterm infants

We evaluated the effect of prone and supine position on cerebral blood flow (CBF) in stable preterm infants. CBF, PO(2), and PCO(2) were measured in the two positions. Peripheral oxygenation increased and CBF decreased in prone position. We speculate that CBF autoregulation may compensate for increased peripheral oxygenation, by decreasing CBF.

Effect of position on oxygen saturation and requirement in convalescent preterm infants

AIMS

To document the effect of position on oxygen saturation and changes in oxygen requirement in convalescent preterm infants.

METHODS

Twelve infants born ≥24 and ≤32 weeks gestation, extubated and without congenital anomaly were studied using nap polysomnography in prone and supine, twice weekly until discharge. Mean oxygen saturation (SpO(2)), minimum SpO(2) , mean minimum SpO(2) and time with SpO(2) < 90% were measured in active sleep.

RESULTS

Eight male and four female infants [median gestation 28 (24-31) weeks and median birthweight 1059 (715-1840) g] had 39 studies. For 21 of 39 studies, the infant was on respiratory support. Four infants had chronic lung disease (CLD). SpO(2) varied with postmenstrual age (PMA) (p = 0.003) but not with position (p = 0.36), and PMA did not influence the effect of position on SpO(2) (p = 0.19). SpO(2) was lower for those with CLD (p < 0.0001) and those on respiratory support (p < 0.001), but there was no effect of position (p = 0.97 and p = 0.67, respectively). From 36 weeks PMA, a change to supine did not increase oxygen requirement.

CONCLUSION

In preterm infants, PMA and residual respiratory disease have greater effects on oxygenation than position. A supine sleep position is not disadvantageous for preterm infants at discharge.

Interventions for apnoea of prematurity: a personal view

AIM

To review treatments for apnoea of prematurity (AOP).

METHODS

Literature Review and description of personal practice.

RESULTS

Provided that symptomatic apnoea has been ruled out, interventions to improve AOP can be viewed as directed at one of three underlying mechanisms: (i) a reduced work of breathing [e.g. prone positioning, nasal continuous positive airway pressure (CPAP)], (ii) an increased respiratory drive (e.g. caffeine), and (iii) an improved diaphragmatic function (e.g. branched-chain amino acids). Most options currently applied, however, have not yet been shown to be effective and/or safe, except for prone, head-elevated positioning, synchronized nasal ventilation/CPAP, and caffeine.

CONCLUSION

Treatment usually follows an incremental approach, starting with positioning, followed by caffeine (which should be started early, at least in infants <1250 g), and nasal ventilation or CPAP via variable flow systems that reduce work of breathing. From a research point of view, we most urgently need data on the frequency and severity of bradycardia and intermittent hypoxia that can yet be tolerated without putting an infant at risk of impaired development or retinopathy of prematurity.

Effects of body position on thermal, cardiorespiratory and metabolic activity in low birth weight infants

BACKGROUND

Low birth weight (LBW) infants sleeping prone are known to exhibit many physiological differences from those sleeping supine, including lower energy expenditure (heat production) and higher surface temperature. This apparent increase in heat storage suggests that heat loss may be inhibited in the prone position which, in turn, might influence cardiorespiratory activity.

AIMS

To determine the effects of body position (prone vs. supine) on absolute surface temperature profile (heat storage), central-peripheral (C-P) thermal gradients (vasomotor response), cardiorespiratory activity and metabolic gas exchange in growing LBW infants.

METHODS

Six-hour continuous recordings of absolute surface temperature profiles, cardiorespiratory activity and O2 and CO2 exchange, along with minute-to-minute assessment of behavioral sleep states were performed in 32 healthy growing LBW infants (birth weight 805-1590 g, gestational age 26-35 weeks and postconceptional age at study 33-38 weeks). Each infant was randomly assigned to the prone or supine position for the first 3 h of the study and then reversed for the second 3 h. Surface temperatures were recorded from 4 sites (forehead, flank, forearm and leg) and averaged each minute. Central (forehead and flank)-to-peripheral (forearm and leg) and forehead-to-environment (H-E) thermal gradients were calculated from the surface temperatures. Corresponding sleep states were aligned with minute averages obtained from the temperature and cardiorespiratory measurements. Data were then sorted for prone and supine positions during quiet (QS) and active sleep (AS) and compared using paired t-tests.

RESULTS

In the prone position during both AS and QS, infants had higher forehead, flank, forearm and leg surface temperatures, narrower C-P gradients, higher heart rates and respiratory frequency, and lower heart rate and respiratory variability. Despite similar environmental temperatures, the H-E gradient was higher in the prone position. In the prone position infants demonstrated lower O2 consumption and CO2 production and a higher respiratory quotient.

CONCLUSIONS

Despite thermoregulatory adjustments in cardiorespiratory function, infants sleeping prone have relatively higher body temperature. The cardiorespiratory responses to this modest increase in temperature indicate that thermal and metabolic control of cardiac and respiratory pumps seem to work in opposition. The consequences of any attendant changes in blood gas activity (e.g. hypocapnia and/or increased mixed venous oxygen concentration) due to this override of metabolic control remains speculative.

Placing preterm infants for sleep: first prone, then supine

Perspective on the paper by Kassim et al (see page 347)

Prone versus supine positioning in the well preterm infant: effects on work of breathing and breathing patterns

Premature infants with respiratory distress oxygenate better and have improved breathing synchrony when they are nursed in the prone position. We investigated whether work of breathing (WOB) is decreased in the prone position in healthy premature infants nearing discharge from the neonatal intensive care unit. Nineteen convalescing premature infants in room air were studied in both supine and prone position. Positioning order was randomized. Mean birth weight was 1358 +/- 332 (SD) g, gestational age 29.7 +/- 2.1 weeks, weight at study 1757 +/- 248 g, and age at study 33.6 +/- 1.4 days. Calibrated respiratory inductance plethysmography (RIP) was used to measure tidal volume; an esophageal catheter estimated pleural pressure. Inspiratory, elastic, and resistive WOB were calculated and were unaffected by prone versus supine positioning (P = 0.46, 0.36, and 0.87, respectively). Similarly, respiratory rate, tidal volume, minute ventilation, and lung compliance did not differ between positions. These data suggest that sleep position recommendations for healthy premature infants discharged home without oxygen should be no different than for term infants.

Body and head position effects on regional lung ventilation in infants: An electrical impedance tomography study

OBJECTIVE

To determine the effects of body and head positions on the spatial distribution of ventilation in nonintubated spontaneously breathing and mechanically ventilated infants using electrical impedance tomography (EIT).

DESIGN AND SETTING

Prospective study in a neonatal intensive care unit.

PATIENTS

Ten spontaneously breathing (gestational age 38 weeks, postnatal age 13 days) and ten mechanically ventilated infants (gestational age 35 weeks, postnatal age 58 days).

INTERVENTIONS

Supine and prone postures with different head positions (midline and rotated to the left and right side).

MEASUREMENTS AND RESULTS

The distribution of ventilation in the chest cross-section was repeatedly determined from EIT data in each body/head position studied. During spontaneous breathing the tidal volumes in the left lung region were reduced in the supine posture with the head turned to the left as well as in the prone posture with the head rotated to either side when compared with the supine posture with the head in the midline position. During mechanical ventilation the tidal volumes in the left lung region were unaffected by the body and head position except for the prone posture combined with the leftward head rotation which reduced them. In both types of ventilation the tidal volumes in the right lung region were unaffected by the change in body/head position.

CONCLUSION

The results indicate that the spatial distribution of ventilation is influenced by the body and head position in spontaneously breathing infants. Prone posture with the leftward head rotation has the most prominent effect which is detectable even during mechanical ventilation.

Lung-function tests in neonates and infants with chronic lung disease: tidal breathing and respiratory control

This paper is the fourth in a series of reviews that will summarize available data and critically discuss the potential role of lung-function testing in infants with acute neonatal respiratory disorders and chronic lung disease of infancy. The current paper addresses information derived from tidal breathing measurements within the framework outlined in the introductory paper of this series, with particular reference to how these measurements inform on control of breathing. Infants with acute and chronic respiratory illness demonstrate differences in tidal breathing and its control that are of clinical consequence and can be measured objectively. The increased incidence of significant apnea in preterm infants and infants with chronic lung disease, together with the reportedly increased risk of sudden unexplained death within the latter group, suggests that control of breathing is affected by both maturation and disease. Clinical observations are supported by formal comparison of tidal breathing parameters and control of breathing indices in the research setting.

Positioning for acute respiratory distress in hospitalised infants and children

BACKGROUND

Because of the association between prone positioning and sudden infant death syndrome SIDS) it is recommended that young infants be placed on their backs (supine). However, the supine position might not be the most appropriate position for infants and children hospitalised with acute respiratory distress. Positioning patients has been proposed as a non-invasive way of increasing oxygenation in adult patients with acute respiratory distress. But, because of substantial differences in respiratory mechanics between adults and children and the risk of SIDS in young infants, a specific review of positioning for infants and young children with acute respiratory distress is warranted.

OBJECTIVES

To compare the effects of different body positions in hospitalised infants and children with acute respiratory distress.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2004); MEDLINE (January 1966 to October Week 3, 2004); EMBASE (1980 to week 24, 2004); and CINAHL (1982 to October Week 3, 2004).

SELECTION CRITERIA

All randomised or systematically-allocated controlled clinical trials comparing two or more positions in the management of infants and children hospitalised with acute respiratory distress.

DATA COLLECTION AND ANALYSIS

Data were extracted from each study independently by two authors. Differences were resolved by consensus or referral to a third author. Continuous outcomes were analysed using a weighted mean difference and 95% confidence interval. No bivariate outcomes were available. All but one included study reported crossover data therefore this data was used for meta-analysis. Fixed-effect models were used unless heterogeneity was significant (p value equal to or less than 0.1), in which case a random-effects model was used.

MAIN RESULTS

Forty-nine papers were selected for this review of which 21 studies (22 publications) were included. These studies compared prone, supine, lateral, elevated, and flat positions. Prone positioning was significantly more beneficial than supine positioning in terms of oxygen saturation, partial pressure of arterial oxygen, oxygenation index, thoraco-abdominal synchrony, and episodes of desaturation. There were no statistically significant differences between any other positions.

AUTHORS' CONCLUSIONS

The prone position was significantly superior to the supine position in terms of oxygenation. However, as most patients included in the meta-analysis were ventilated, preterm infants the benefits of prone positioning may be most relevant to these infants. In addition, although placing infants and children in the prone position may improve respiratory function, the association of sudden infant death with prone positioning means that infants should only be placed in this position if continuous cardiorespiratory monitoring is used.

Prone or supine for infants with chronic lung disease at neonatal discharge?

OBJECTIVE

To determine whether infants with chronic lung disease (CLD), ready for neonatal unit discharge, maintain cardiorespiratory stability while sleeping supine.

METHODS

Subjects were 15 infants born < 32 weeks gestational age (GA) and ready for discharge from the regional tertiary neonatal intensive care unit. Polysomnography recordings of sleep state, heart rate, arterial oxygen saturation, respiratory effort and nasal/oral airflow were taken prone and supine for up to 3 h post feed with the first position randomly allocated. The main outcome measures were oxygen saturation and apnoea hypopnoea index (AHI).

RESULTS

Seven infants (median GA 27 weeks, birthweight 945 g) had CLD and eight infants (median GA 29 weeks, birthweight 1160 g) did not. CLD infants were more mature at study than non-CLD infants (median 39 vs 36 weeks, P = 0.019). Neither oxygen saturation nor AHI were position dependent and no group differences were noted with respect to CLD status. There was a significant interaction of GA and sleep position with less-mature infants spending less time in quiet sleep (QS) in supine position (P = 0.006). These less-mature infants also had a higher AHI (P = 0.033). As expected, the AHI and arousal index (AI) were higher in active sleep (P < or = 0.001, P = 0.013, respectively) and mean oxygen saturation was lower (P = 0.001).

CONCLUSIONS

The supine position appears appropriate for very preterm infants with CLD going home from the neonatal unit. Respiratory instability on neonatal discharge is more likely to be associated with immaturity than CLD.

Effect of posture on respiratory function and drive in preterm infants prior to discharge

Our objective was to determine the effect of posture on respiratory function and drive in prematurely born infants immediately prior to discharge. Twenty infants (6 oxygen-dependent), median gestational age 29 weeks (range, 25-32), were studied at a median postconceptional age (PCA) of 36 weeks (range, 33-39). On 2 successive days, infants were studied both supine and prone; each posture was maintained for 3 hr. The order on each day in which postures were studied was randomized between infants. At the end of each 3-hr period, tidal volume (Vt), inspiratory (Ti) and expiratory (Te) time, respiratory rate, and minute ventilation were measured. In addition, respiratory drive was assessed by measuring the pressure generated in the first 100 msec of an imposed airway occlusion (P(0.1)), and respiratory muscle strength was assessed by recording the maximum inspiratory pressure (Pimax) generated against an occlusion which was maintained for at least five breaths. Overall, tidal volume was higher (P < 0.05), but respiratory rate (P < 0.05), P(0.1) (P < 0.05), and Pimax (P < 0.05) were lower in the prone compared to the supine position. There were no significant differences in Ti or Te between the two postures. In oxygen-dependent infants only, minute volume was higher in the prone position (P < 0.05). In conclusion, posture-related differences in respiratory function are present in prematurely born infants studied prior to neonatal unit discharge.

Treatment of apnea of prematurity

In the last decade, knowledge regarding the neurodevelopment and functional aspects of the respiratory centers during postnatal maturation has increased substantially. However, an increase in such knowledge has not provided a basis for change in practice. The diagnosis of apnea of prematurity (AOP) is one of exclusion. All causes of secondary apnea must be ruled out before initiating treatment for AOP. Treatment will depend on the etiology as well as effectiveness and tolerability of the treatment by the patient. The primary goal of any treatment of AOP is to prevent the frequency of apnea lasting >20 seconds, and/or those that are shorter, but associated with cyanosis and bradycardia. The clinical management of AOP is not much different today than it was two decades ago, with pharmacologic and nonpharmacologic treatment options remaining the mainstay of therapy. Methylxanthines are still the most widely used pharmacologic agents. Due to the wider therapeutic index of caffeine and ease of once daily administration, it should be the preferred agent. Doxapram, or nonpharmacologic treatment measures such as nasal continuous positive airway pressure, may be considered in infants who are unresponsive to methylxanthine treatment alone. Treatment should be continued until there is complete resolution of apnea, and for some time thereafter. The choice of method for weaning treatment remains one of individual physician preference. Discharge from hospital after apnea requires close monitoring and some infants will require home apnea monitors. The decision to provide a home apnea monitor should be individualized for each patient, depending on the effectiveness of treatment and clinical response.

Survey of sleeping position recommendations for prematurely born infants on neonatal intensive care unit discharge

Prematurely born infants are at increased risk of sudden infant death syndrome, particularly if slept prone. Yet, some prematurely born infants are slept prone despite the high risk age for sudden infant death syndrome and this may reflect the advice given by neonatal unit staff. The aim of this study was to determine neonatal units' recommendations regarding sleeping positions for premature infants prior to and after discharge. A questionnaire survey was sent to all 224 neonatal units in the United Kingdom, of which 81% responded. Analysis of their responses demonstrated that 43% of units started to sleep infants supine 1 to 2 weeks prior to discharge, but oxygen-dependent infants were slept non-supine until an older age. Non-supine sleeping was recommended by 40% of units for infants with Pierre Robin syndrome or gastro-oesophageal reflux. All units advised supine sleeping at discharge, but 29% additionally recommended side sleeping and only 58% positively discouraged prone sleeping. Written information was given to parents by 70% of the units, but few provided information which was specifically about prematurely born infants.

CONCLUSION

The worrying lack of consistency in recommending non-prone sleeping emphasises that evidence-based guidelines for the sleeping position of convalescent prematurely born infants are required.

Nasal CPAP for neonates: what do we know in 2003?

Despite the acknowledged clinical usefulness of nasal CPAP, uncertainties regarding aspects of its application remain. Clinical indications for the application of nasal CPAP vary greatly between institutions. Furthermore, defining the optimal nasal CPAP system is complicated by the multiplicity of nasal CPAP devices and techniques available to the clinician. This review aims to identify what we know about nasal CPAP and what important questions remain.

Facilitating infant adaptation: the nursery environment

The physical and social environment of the nursery is a direct and indirect influence on the development of premature infants. Qualities in the environment affect physiological stability and provide sensory experience that is relevant to brain development. Adaptation of the prematurely born infant to the unexpected surroundings of the neonatal intensive care unit can be facilitated when the infant's developmental needs are understood and characteristics of the environment are adapted accordingly. The need for environmental change is revealed by the infant's behaviour, that is, his interactions with the environment. The environment also affects the behaviour of caregivers, who like the baby need to be able to do their best in this challenging situation.

Cardiorespiratory stability of premature and term infants carried in infant slings

OBJECTIVE

Parents in industrialized societies make increasing use of infant slings to carry their infants. This study was conducted to determine whether infants who are carried in slings are at risk of experiencing clinically relevant changes in cardiorespiratory measurements.

METHODS

In a 3-period crossover trial, 24 preterm and 12 term newborns were continually monitored while being carried horizontally or vertically in a sling or lying in a pram. Oxygen saturation, heart rate, nasal airflow, abdominal breathing, and movements were recorded.

RESULTS

Infants who were carried in slings were not at risk of clinically relevant changes of oxygen saturation or heart rate. The 90% confidence interval of oxygen saturation in both infant sling positions remained within a +/-2% interval around the average oxygen saturation in the pram. However, a significant decrease of oxygen saturation was observed while infants were carried in a sling with a mean oxygen saturation of 96.3% (standard deviation [SD]: 1.8) in the vertical and 96.1% (SD: 2.0) in the horizontal sling position compared with the mean oxygen saturation in the pram (97.1%; SD: 1.5). The degree and the incidence of desaturations and bradycardia did not change while the infants were carried. Both types of episodes were seen only in preterm infants.

CONCLUSION

The use of carrying slings is not associated with an increased risk of clinically relevant cardiorespiratory changes in term and preterm infants.

Neuromotor development and the physiologic effects of positioning in very low birth weight infants

OBJECTIVE

To provide a comprehensive literature review of neuromotor development and related physiologic effects of positioning in very low birth weight infants.

DATA SOURCES

MEDLINE, CINHAL, Health Star, Current Contents, and the Australian Medical Index (1966-2000) databases were searched. Unpublished studies (e.g., dissertations, conference proceedings) and all relevant references listed in articles also were examined.

STUDY SELECTION

One hundred and eighty theoretical writings, research studies, and clinical papers related to neuromotor development, the physiologic effects of positioning, and interventions to minimize or prevent short- and long-term effects of positioning in very low birth weight infants were reviewed.

DATA EXTRACTION

Studies were assessed for scientific rigor, evidence of theoretical foundation, and clinical relevance. Comparisons were made across data sources to determine the most reliable, valid, and consistent findings.

DATA SYNTHESIS

Three compelling results emerged: (a) The development of posture and mobility in newborn infants requires an optimal balance between active and passive muscle tone, (b) the prone position is physiologically more beneficial for the preterm infant than supine and lateral positions, and (c) the prone position can lead to short- and long-term postural and associated developmental problems.

CONCLUSION

Use of empirically tested postural interventions appropriate for an infant's gestational age, health status, and overall organizational capacity is recommended.

Decreased activity and oxygen desaturation in prone ventilated preterm infants during the first postnatal week

OBJECTIVE

To compare the effects of supine and prone positions on oxygen saturation (SpO(2)), desaturation episodes (SpO(2) < 90% and >or= 20 seconds), and motor activity in ventilated preterm infants during their first postnatal week.

DESIGN

With use of a crossover design, we randomly assigned infants to a supine/prone or prone/supine position sequence. Infants were placed in each position for 2 hours. A stabilization period of 10 minutes before observation of each position was allowed. During the protocol, care procedures were kept minimal and ventilator settings remained unchanged.

SETTING

Neonatal intensive care units at 2 tertiary care centers in Taiwan.

SAMPLE

The sample consisted of 28 infants receiving mechanical ventilation who were 25 to 36 weeks' gestation, without known congenital abnormalities, within 7 postnatal days of birth, and were not receiving sedation.

RESULTS

When prone, infants had higher SpO(2), fewer episodes of oxygen desaturation, and less motor activity than when supine. No significant differences in duration of SpO(2) less than 90%, 85%, and 80% were found between the 2 positions. Seventy-four percent of desaturation episodes were associated with vigorous motor activity and crying.

CONCLUSION

The prone position results in less motor activity and may stabilize oxygenation for ventilated preterm infants. This may conserve energy and decrease complications of hypoxia for sick preterm infants.

Body position-dependent changes in cerebral hemodynamics during apnea in preterm infants

The objective of the present study was to evaluate sleeping position-dependent effects on cerebral hemodynamics during apnea in preterm infants. To this end, polygraphic studies were performed on 15 stable preterm infants lying prone and lying supine. Changes in cerebral blood volume (DeltaCBV) and in cerebral hemoglobin oxygenation ((Delta)cHbD) in association with apnea were measured by near infrared spectroscopy. For comparison, apnea in the prone position was matched for duration to apnea in the supine position. A total number of 98 pairs of apnea were compared. The mean duration of apnea was 8.2+/-3 s. In both positions there was a predominance of decrease in CBV and cHbD in association with apnea. The mean decrease of cHbD (-1.57+/-1.82 micromol/l) and of CBV (-0.120+/-0.137 ml/100g brain) in the supine position was significantly pronounced compared to prone position (DeltacHbD: -1.18+/-1.77 micromol/l, DeltaCBV: -0.080+/-0.095 ml/100 g brain). The degree of DeltaCBV and DeltaHbD did not correlate with postconceptional or postnatal age (r2<0.01). In both positions there was a similar small decrease of SaO2 in association with apnea. In the supine position heart rate decreased slightly during apnea, whereas in the prone position no change in heart rate could be observed. The present study revealed a position-dependent different impact of apnea on cerebral hemodynamics. With regard to cerebral blood volume and oxygenation in association with apnea no negative effects of prone sleeping position could be observed in preterm infants.

Effect of positioning on respiratory synchrony in non-ventilated pre-term infants

BACKGROUND AND PURPOSE

Body position can play an important role in an infant's recovery from respiratory disease, but few studies have accounted for sleep state which is known to have a direct influence on the control of respiratory muscles as well as on metabolic and circulatory changes. The purpose of this study was to examine the influence of body position on respiratory function in pre-term infants whilst accounting for sleep state.

METHOD

Thoraco-abdominal motion was assessed using respiratory inductance plethysmography (RIP) to provide measures of relative rib cage (RC) and abdominal (AB) movement in ten non-ventilated pre-term infants. Continuous measurements of oxygen saturation (SaO2), pulse and heart rate (HR), were made and sleep state was recorded using behavioural criteria and electro-oculogram (EOG) measurements.

RESULTS

The results showed a significant increase in HR in supine, but no significant difference in SaO2 as a function of position, compared to the prone position where a significant reduction was found in thoraco-abdominal asynchrony for both groups and a reduction in variability in both HR and SaO2. Intra-subject variability of thoraco-abdominal motion as a function of position demonstrated no significant difference on return to supine or on return to prone, illustrating good repeatability of measures.

CONCLUSIONS

Prone positioning of pre-term infants recovering from respiratory disease may improve respiratory function. As measured, the improvement in respiratory synchrony in prone position brings pre-term infants' breathing pattern into line with that expected in term infants.

Effects of the supine and prone position on diaphragm thickness in healthy term infants

BACKGROUND

The physiological basis underlying the decline in the incidence of sudden infant death syndrome (SIDS) associated with changing the sleep position from prone to supine remains unknown.

AIMS

To evaluate diaphragm thickness (t(di)) and shortening in healthy term infants in the prone and supine positions in order to determine whether changes in body position would affect diaphragm resting length and the degree of diaphragm shortening during inspiration.

METHODS

In 16 healthy term infants, diaphragm thickness at the level of the zone of apposition on the right side was measured using ultrasonography. Heart rate (HR), breathing frequency (f), and transcutaneous oxyhaemoglobin saturation (SaO(2)) were recorded simultaneously during diaphragm imaging with the infants in the supine and prone positions during quiet sleep.

RESULTS

At end expiratory (EEV) and at end inspiratory lung volumes (EIV), t(di) increased significantly in the prone position. The change in t(di) during tidal breathing was also greater when the infant was prone. SaO(2), HR, and f were not significantly different at EEV and at EIV in both positions.

CONCLUSION

In healthy term infants, placed in the prone position, the diaphragm is significantly thicker and, therefore, shorter, both at EEV and EIV. Diaphragm shortening during tidal breathing is greater when the infant is prone. In the prone position, the decreased diaphragm resting length would impair diaphragm strength, and the additional diaphragm shortening during tidal breathing represents added work performed by the diaphragm. This may compromise an infant's capacity to respond to stressful situations when placed in the prone position and may contribute to the association of SIDS with prone position.

Back to sleep: is there room in that crib for both AAP recommendations and developmentally supportive care?

This article offers one institution's approach to implementation of the recommendations for infant sleep positioning as set forth by the American Academy of Pediatrics. The guidelines are directed toward healthy infants in the first year of life, a population not always encountered by the neonatal nurse. The guidelines focus on supine sleep position and the minimization of additional bedding, both of which can be challenging when contrasted with accomplishing supportive positioning and the goals of developmentally supportive care for ill or preterm infants. A multidisciplinary task force was formed to consider this challenge. The outcome is an evidence-based policy that is presented as an example for other clinicians. The policy addresses the following major components: sleep position with specific clinical exceptions, the use of bedding materials, play position during awake states, and parent education with preparation for discharge. The article also outlines the process by which the task force plans to implement and evaluate necessary practice changes.

Effects on oxygen saturation levels of handling premature infants within the concepts of kinaesthetic infant handling: pilot study

Preterm infants are exposed to many stressors within the neonatal intensive care environment. Since these are associated with medical and developmental problems, a reduction of stress factors is desirable. Handling is a very common occurrence and is associated with stress. Kinaesthetic infant handling (KIH) offers practical guidance on handling for nurses and has been widely implemented in Germany, although there is no direct experimental evidence to support its use. The findings of this pilot study suggest a beneficial effect on the SpO2 for infants who were handled using KIH. Since this was a pilot study with a small sample size, caution has to be exercised with this finding. Therefore, the main purpose of the study was: (1) to identify the weaknesses and strengths of the chosen study design; and (2) to perform a power analysis in order to determine a sufficient sample size for the full experiment.

More awakenings and heart rate variability during supine sleep in preterm infants

OBJECTIVE

The Task Force of The American Academy of Pediatrics (1996) recommends the nonprone sleeping position for asymptomatic preterm infants to prevent sudden infant death syndrome. The mechanism by which the nonprone sleeping position reduces the rate of sudden infant death syndrome is unclear for full-term infants and the precise effect of sleeping position on sleep and cardiorespiratory characteristics has never been addressed in preterm infants. The purpose of the present study was to clarify the effect of sleeping position on sleep and cardiorespiratory characteristics in preterm infants at an age when they are ready for discharge.

STUDY DESIGN

Sixteen asymptomatic preterm infants were studied in both supine and prone sleeping positions at 36.5 +/- 0.6 weeks' postconceptional age using videosomnography. Sleep, respiratory, and heart rate characteristics were compared between the two positions using each infant as his/her own control.

RESULTS

More awakenings (ie, arousals >/=60 seconds) were seen during all sleep states in the supine sleeping position but overall the total sleep and percent sleep state were not affected by sleeping position. After each feeding, the first quiet sleep was significantly shorter, with more heart rate variability and awakenings in the supine position. There were no significant differences in the occurrence of arousals (<60 seconds) or the incidence or severity of apnea and periodic breathing. No clinically significant apnea (>/=15 seconds), bradycardia, or oxygen desaturations were seen.

CONCLUSION

In 36-week-postconceptional age preterm infants, the supine sleeping position had less quiet sleep and was associated with greater heart rate variability during the first sleep cycle after the feeding. More awakenings were seen during all sleep states in the supine position. These data support the American Academy of Pediatrics recommendation for "Back to Sleep" for asymptomatic preterm infants because more awakenings and lower threshold for arousal may provide some benefit for the infant responding to a life-threatening event. However, further studies are needed to address positional effect on the physiologic measures in preterm infants at older ages (later stages of development). Precisely what constitutes the most healthy or advantageous sleep for newborn infants remains an important question.

Effect of nursing in the head elevated tilt position (15 degrees) on the incidence of bradycardic and hypoxemic episodes in preterm infants

OBJECTIVE

We investigated whether nursing in the head elevated tilt position (HETP), compared with the horizontal position, has any effect on the incidence of bradycardic and hypoxemic episodes in preterm infants.

METHODS

Twelve spontaneously breathing preterm infants with idiopathic recurrent apnea were studied in a randomized controlled crossover trial. Nine infants were treated with aminophylline. Each spent a total of 24 hours in the horizontal prone position and a total of 24 hours in HETP (prone, 15 degrees). The position was changed in random order every 6 hours. Thoracic impedance, heart rate, and arterial oxygen saturation were recorded continuously. The frequency of isolated hypoxemia (arterial saturation <80%), of isolated bradycardia (heart rate <90 beats per minute), and of mixed events was analyzed and compared without knowledge of the allocated position.

RESULTS

In total, there were significantly fewer bradycardic and/or hypoxemic episodes (28.2%) in HETP compared with the horizontal position (mean difference, 13.35 episodes/24 hours; 95% confidence interval [CI]: 5.9- 20.8). The decrease was largest for isolated hypoxemic episodes (48.5%; mean difference, 11.74 episodes/24 hours; 95% CI: 6.1-17.4). Isolated bradycardic episodes (mean difference, 2.27 episodes/24 hours; 95% CI: -0.78-5.31) and mixed events were not decreased significantly in HETP.

CONCLUSIONS

Nursing in a moderately tilted position (15 degrees) reduces hypoxemic events in preterm infants. This intervention is easy to apply, quickly reversible, and can be combined with drugs such as aminophylline.

Characteristics of hypoxemic episodes in very low birth weight infants on ventilatory support

OBJECTIVE

To characterize hypoxemic episodes in very low birth weight infants with mechanically ventilated lungs and to describe their natural history and the effect of body position.

STUDY DESIGN

Tidal volume, respiratory rate, oxygen saturation, heart rate, and body movement were continuously recorded in 10 very low birth weight infants who exhibited episodes of hypoxemia during mechanical ventilation (birth weight, 810 +/- 133 gm; postconceptional age at study, 30 +/- 1.6 weeks). Frequency of hypoxemic episodes was compared in both prone and supine positions.

RESULTS

Seventy-eight percent of hypoxemic episodes began in association with body movement as well as heart rate acceleration. Thereafter the spontaneous and delivered minute ventilation both decreased during the first 15 seconds of hypoxemia. The former decrease was due to a significant decrease in frequency of spontaneous respiration, whereas the latter was associated with a significant decrease in delivered tidal volume. Minute ventilation returned to normal before recovery of oxygenation. A change in body position from supine to prone significantly decreased the frequency of hypoxemic episodes.

CONCLUSION

Hypoxemic episodes in infants who are on ventilatory support are characterized by (1) movement and cardioacceleration at initiation; (2) a decrease in both spontaneous and delivered minute ventilation, and (3) a lower incidence in the prone position. We speculate that spontaneous movement during sleep can trigger cardiopulmonary reflex responses that initiate and propagate these episodes.

The influence of sleeping position on functional residual capacity and effective pulmonary blood flow in healthy neonates

Variation in body position has been shown to affect respiratory function in adults and neonates with and without respiratory illness. At present it remains unclear why respiratory function should be affected by different body positions. We hypothesized that the effect of body weight on the relatively compliant chest wall of the newborn infant in the prone position would cause a reduction in functional residual capacity (FRC) and a compensatory improvement in ventilation/perfusion matching as measured by effective pulmonary blood flow. To evaluate this, a paired crossover study was performed on 12 normal newborn infants. The inert gas (argon) rebreathing method adapted for neonates was used to measure FRC. Simultaneously effective pulmonary blood flow (Qpeff) was determined using Freon 22 and a mass spectrometer with computerized analysis. The babies were studied in three different positions in random order: prone, supine and right lateral decubitus. The means (95% confidence intervals) of the three groups of FRC were 23.8 (19.2 to 28.4), 23.8 (20.2 to 27.5), and 24.3 (19.5 to 29.2) ml/kg, respectively (P = 0.59) and for Qpeff were 104 (91 to 116), 108 (95 to 122), 109 (97 to 122) ml/ kg-min, respectively (P = 0.11). Thus no significant differences were demonstrated. In nine of the babies, a repeat supine measurement was taken at the end of the study to assess repeatability of the method. In these nine babies alone the results were 22.7 (19.1 to 26.3) and 22.1 (18.6 to 25.6) ml/kg for FRC, and 102 (89 to 116) and 98 (90 to 107) ml/kg-min for Qpeff. The coefficients of repeatability were 4.7 ml/kg for FRC (21%) and 30 ml/kg-min for Qpeff (30%).

Vulnerability of respiratory control in healthy preterm infants placed supine

OBJECTIVE

We tested the hypothesis that healthy preterm infants have attenuated ventilatory responses to hypercapnia, associated with a decreased rib cage contribution to ventilation, in the supine versus prone position.

STUDY DESIGN

We elicited hypercapnic ventilatory responses from 19 healthy preterm infants (postconceptional age 35 +/- 1 weeks) who were being prepared for hospital discharge. The O2 saturation was continuously monitored. Before and during CO2 rebreathing, ventilation was measured with a nasal mask pneumotachygraph and was derived from chest wall motion as determined by respiratory inductance plethysmograph. This measuring method allowed us to compare both ventilation and the percentage rib cage contribution to ventilation between supine and prone positions. Statistical analysis employed analysis of variance with repeated measures.

RESULTS

The supine position was associated with a higher respiratory rate (p < 0.02) and lower O2 saturation (p < 0.007) than the prone position. The increase in ventilation in response to hypercapnia was lower in the supine than in the prone position. This was statistically significant for the respiratory inductance plethysmograph (p < 0.008) but not the pneumotachygraph (p = 0.077), and was associated with a smaller rib cage contribution to ventilation in the supine than in the prone position (p < 0.0001).

CONCLUSION

Respiratory control may be vulnerable when healthy preterm infants are placed supine. Widespread avoidance of the prone position may not be appropriate for such patients.