Abnormal hypoxemia after life-threatening events in infants born before term

Effects of Microcurrent on Oxygen Saturation by Controlling Rectus Abdominis Activity in Preterm Infant With Desaturation During Feeding: A Pilot Study

Objective: To determine whether a portable microcurrent therapy device (PMTD) of the rectus abdominis muscles is effective for treating desaturation during feeding in preterm infants and to evaluate the association between initial electrical activity of respiratory muscle and long-term development delay. Methods: Twenty preterm infants with desaturation during feeding were recruited. Respiratory muscle activity was quantified by calculating the root mean square (RMS) of the electromyography. All preterm infants received a 30 min PMTD application to the rectus abdominis and diaphragm daily for 2 weeks. RMS of diaphragm and rectus abdominis, feeding volume, frequency of desaturation during feeding at baseline (pre-PMTD) and 1, 2 week post-PMTD were measured. The number of days it took to treat desaturation after PMTD was measured. A Denver developmental screening test was performed and infants were divided into 3 groups: (1) normal; (2) caution; and (3) delayed at 3months after PMTD. Results: The desaturation during feeding of all the preterm infants subsided after PMTD and the mean days took to treat desaturation was 25.4 ± 14.2 days. The RMS of diaphragm, rectus abdominis, and frequency of desaturation during feeding were significantly decreased and the feeding volume was significantly increased after PMTD (p < 0.01). The mean treatment duration for desaturation was negatively correlated with RMS of rectus abdominis at baseline and 1 week post-PMTD, respectively (Pearson's correlation coefficient = -0.461,-0.514, p-value = 0.047, 0.029). RMS of rectus abdominis of Group 3 is lower than that of group 1 and 2 (p < 0.01). Conclusions: This pilot study showed that the microcurrent therapy of rectus abdominis is an efficient therapy for the treatment of preterm infants with desaturation during feeding, especially preterm infants with higher activity of the rectus abdominis. In preterm infants with lower rectus abdominis activity, longer time is required to treat desaturation by microcurrent therapy and developmental delay is observed at months post-treatment.

Home oxygen therapy after hospital discharge

Home oxygen therapy is increasingly prescribed for various conditions in the neonatal period, particularly for infants with bronchopulmonary dysplasia. Due to limited evidence on indication, minimal target oxygen saturation, monitoring, application and discontinuation of home oxygen therapy clinical practice varies widely throughout the world. International guidelines provide recommendations mostly on the basis of nonsystematic clinical observations. Most relevant points for the clinical management of home oxygen therapy include a minimal target oxygen saturation of equal to or greater than 93%, the provision of a home monitoring of oxygen saturation ideally with a memory function, and the conduct of continuous overnight oximetry or polysomnography during weaning from supplemental oxygen. This review summarizes relevant literature as well as existing guidelines and recommendations on home oxygen therapy to aid clinicians in the management of these patients and identifies areas for future research.

The impact of preterm adversity on cardiorespiratory function

NEW FINDINGS

What is the topic of this review? We review the influence of prematurity on the cardiorespiratory system and examine the common sequel of alterations in oxygen tension, and immune activation in preterm infants. What advances does it highlight? The review highlights neonatal animal models of intermittent hypoxia, hyperoxia and infection that contribute to our understanding of the effect of stress on neurodevelopment and cardiorespiratory homeostasis. We also focus on some of the important physiological pathways that have a modulatory role on the cardiorespiratory system in early life.

ABSTRACT

Preterm birth is one of the leading causes of neonatal mortality. Babies that survive early-life stress associated with immaturity have significant prevailing short- and long-term morbidities. Oxygen dysregulation in the first few days and weeks after birth is a primary concern as the cardiorespiratory system slowly adjusts to extrauterine life. Infants exposed to rapid alterations in oxygen tension, including exposures to hypoxia and hyperoxia, have altered redox balance and active immune signalling, leading to altered stress responses that impinge on neurodevelopment and cardiorespiratory homeostasis. In this review, we explore the clinical challenges posed by preterm birth, followed by an examination of the literature on animal models of oxygen dysregulation and immune activation in the context of early-life stress.

Home Oxygen Therapy for Children. An Official American Thoracic Society Clinical Practice Guideline

Background: Home oxygen therapy is often required in children with chronic respiratory conditions. This document provides an evidence-based clinical practice guideline on the implementation, monitoring, and discontinuation of home oxygen therapy for the pediatric population.

Methods: A multidisciplinary panel identified pertinent questions regarding home oxygen therapy in children, conducted systematic reviews of the relevant literature, and applied the Grading of Recommendations, Assessment, Development, and Evaluation approach to rate the quality of evidence and strength of clinical recommendations.

Results: After considering the panel’s confidence in the estimated effects, the balance of desirable (benefits) and undesirable (harms and burdens) consequences of treatment, patient values and preferences, cost, and feasibility, recommendations were developed for or against home oxygen therapy specific to pediatric lung and pulmonary vascular diseases.

Conclusions: Although home oxygen therapy is commonly required in the care of children, there is a striking lack of empirical evidence regarding implementation, monitoring, and discontinuation of supplemental oxygen therapy. The panel formulated and provided the rationale for clinical recommendations for home oxygen therapy based on scant empirical evidence, expert opinion, and clinical experience to aid clinicians in the management of these complex pediatric patients and identified important areas for future research.

Augmentation of respiratory muscle activities in preterm infants with feeding desaturation

Purpose

Frequent desaturation due to immature incoordination of suck-swallow-breathing in preterm infants can influence multiple organs such as the heart, lungs, and brain, which can then affect growth and development. Most notably in preterm infants, feeding desaturation may even affect pulmonary function during gavage feeding. Because respiratory muscle activities may reflect the work required during respiration, we evaluated the differences in these activities between full-term and preterm infants with feeding desaturation, and investigated the correlations with clinical variables.

Methods

Nineteen preterm infants with feeding desaturation (group 1) and 19 age-matched full-term infants (group 2) were evaluated. Oromotor function was evaluated using video recording. The root-mean-squre (RMS) envelope of the electromyography signal was calculated to quantify the activities of muscles involved in respiration. The differences in RMS between both groups and the correlation with clinical variables including gestational age (GA), birth weight (BW), and Apgar scores (AS) at 1 and 5 minutes after birth were evaluated.

Results

The RMS values of the diaphragm (RMS-D) and rectus abdominis (RMS-R) were significantly greater in group 1 compared to group 2, and the 1- and 5-min AS were significantly lower in group 1 compared to group 2. RMS-D and RMS-R were inversely correlated with GA, BW, 1- and 5-min AS in all infants.

Conclusion

This study showed that respiratory muscle activities were augmented during feeding in preterm infants compared to full-term infants. Additionally, respiratory muscle activities were inversely correlated with all clinical variables.

Screening for cardiopulmonary events in neonates: a review of the infant car seat challenge

The infant car seat challenge (ICSC), or period of observation in a car safety seat before discharge to monitor for episodes of apnea, bradycardia and desaturation, is one of the most common tests performed on preterm neonates in the United States. However, the utility of the ICSC to identify infants at risk for adverse cardiopulmonary events in the car seat remains unclear. Minimal evidence exists to guide clinicians in performance of this test including appropriate inclusion criteria and failure criteria. In this article, the origins of the ICSC are discussed as well as potential etiologies of desaturations and bradycardia in the car seat position. Current literature on implementation, inclusion and failure criteria, incidence of failure and data on the meaning of a 'passed' vs 'failed' ICSC are discussed. Emphasis is made on minimizing time in car seats and seated devices given concern over the risk of desaturations.

Early NICU discharge of very low birth weight infants: a critical review and analysis

Early neonatal intensive care unit (NICU) discharge has been advocated for selected preterm infants to reduce both the adverse environment of prolonged hospital stay and to encourage earlier parental involvement by empowering parents to contribute to the ongoing care of their infant, and thereby reducing costs of care. Randomized trials and descriptive experiences of early discharge programs are critically reviewed over the last 30 years, and the key elements necessary for successful early discharge are reviewed and defined. Early discharge is clearly achievable for a large number of infants. Variations in neonatal care practices are reviewed since these variations have been documented to influence NICU stay. Management of apnea of prematurity and feeding practices is documented to significantly influence NICU length of stay, as is timing of discharge based on institutional factors. Developmentally centered care, use of nutritional supplements pre- and postdischarge, hearing screening programs, evaluation for retinopathy of prematurity, evaluation for apnea and bradycardia events, and cardiopulmonary stability while in a car seat all influence timing of discharge. Programs of early hospital discharge with home nursing and neonatologist support have been successful in lowering the length of NICU stay. However, trends in length of stay in NICUs indicate that for infants >750 g at birth over the last decade there have been insignificant reductions in length of hospital stay. Thus, because of the increase in the percentage of low birth weight infants in the US, there remain opportunities to improve on variations in care that will be translated to fewer NICU days in hospitals for selected infants. Several professional guidelines are summarized, and standards of care as related to discharge of premature infants are reviewed.

Occurrence of oxygen desaturation events during preterm infant bottle feeding near discharge

AIMS

The purpose of this study was to examine the occurrence, severity, pattern, and moderators of oxygen desaturation during preterm infant bottle feeding near the time of discharge from the neonatal intensive care unit (NICU) when fed by mothers.

STUDY DESIGN

Twenty-two very low birthweight (VLBW) infants [birthweight 1155+/-293 g, gestational age (GA) 28.1+/-2.0, postconceptional age (PCA) 36.5+/-1.6 weeks] were videotaped being bottle-fed by their mothers. Most infants (86%) were discharged within 6 days of the study. Oxygen saturation was continuously monitored and infant feeding behaviors were coded. Oxygen desaturation events (SpO(2)<90%) were identified and analyzed.

RESULTS

Infants averaged 10.8 events during feeding (range 1-28, S.D. 8.9) and spent, on average, 20% of their feeding time (range 0-70%, S.D. 17.98%) with oxygen levels below 90%. One hundred forty of the desaturation events (59%) were classified as mild (SpO(2) 85-89), 47 events (20%) were classified as moderate (SpO(2) 81-84), and 51 events (21%) were classified as severe (SpO(2)</=80). Events were evenly distributed across infants' feeding time. Receiving supplemental oxygen, beginning the feeding with a higher baseline SpO(2), and being of older PCA predicted lower percentage of feeding time with SpO(2) below 90% (R(2)=0.57). Receiving supplemental oxygen and beginning the feeding with a higher baseline SpO(2) predicted less number of desaturation events during the feeding (R(2)=0.44). Despite similar baseline SpO(2) levels, infants who were on supplemental oxygen had 50% less oxygen desaturation events and spent 33% less time with SpO(2) less than 90%.

CONCLUSION

VLBW infants continue to have desaturation events during feeding when fed by their mothers near the time of discharge. Further research is needed to understand the effect of hypoxemia on the preterm infant's development of oral feeding skills, to study the effects of supplemental oxygen during feeding, and to further develop interventions to minimize desaturation during feeding.

Desaturation events in neonates during mechanical ventilation

This study examines the accuracy of oxygen saturation measured by Nellcor N200 pulse oximetry (SpO2) compared with arterial oxygen saturation (SaO2) measured through a three-wavelength fiberoptic umbilical catheter in 10 neonates who needed mechanical ventilation. Real-time SaO2 was validated with a reference method every 4 hours. Oxygen saturation readings (SaO2 and SpO2), along with pulse rate and pulsation, were recorded continuously every second through a computer. Concurrent care events and neonatal responses were recorded. Data were completed on 10 neonates who had an umbilical arterial catheter. Desaturation events (<90%) as measured by both SaO2 and SpO2 were described and compared. A total of 959 desaturation events occurred during an average of 51 hours of monitoring per subject. Of these events, 63% were associated with frozen SPO2 readings, and 18% of frozen readings occurred when SaO2 was <90%. Bias for SpO2 compared with SaO2 was +5.03%, with 5.6% of the readings outside the range of two standard deviations. However, 67% of the readings exceeded the 4% difference criterion between measurements. Future studies need to examine the desaturation events in relation to oxygenation status as measured by different methods.

Computerised audiovisual event recording for infant apnoea and bradycardia

Event recording, by differentiating between true and false events, has advanced the diagnosis and management of infants on home cardiorespiratory monitors; however, the pathogenesis of many events remains obscure. To clarify infant behaviours around the time of apnoea/bradycardia alarms, a computerised audiovisual event recording system (CAVERS) triggered by the apnoea/bradycardia recorder, has been developed. The audiovisual recording can begin up to 3 min before the alarm and can continue for up to 3 min after the alarm. CAVERS information is recorded for a total of 65 events in 13 infants. The CAVERS proves most helpful in documenting infant position and the wide variety of behaviours associated with bradycardic events. These behaviours range from sleep or quiet wakefulness to crying and generalised movements. Post-event activity is also highly variable. Interestingly, 20 of 65 events appear to terminate when the infant wakes to the audible monitor alarm. Nursing intervention is documented for 14 of 42 bradycardic events but only one of 23 apnoeic events. The CAVERS, by elucidating infant behaviours, provides information complementary to that given by cardiorespiratory event recording. It is suggested that infant monitors of the future should incorporate both audiovisual and cardiorespiratory data to elucidate optimally apparent life-threatening events, apnoeas and bradycardias.

When do infants need additional inspired oxygen? A review of the current literature

There is considerable uncertainty regarding the oxygen saturation threshold below which additional inspired oxygen should be given to infants with acute or chronic lung disease. In the absence of data from controlled studies, recommendations can only be based on reference values for healthy infants and on observational studies regarding the pathophysiological effects of acute and chronic hypoxia. Reference values for pulse oximeter saturations (SpO2) in term and preterm infants show that during normal breathing 95% of infants maintain SpO2 at or above 93-97%, depending on age. Studies of infants with chronic lung disease (CLD) show that (1) when SpO2 was kept at > or =93% by administration of home oxygen, rates of sudden infant death were reduced; (2) weight gain was significantly better when SpO2 was maintained at > or =93-95%, (3) increasing SpO2 from 82 to 93% by delivering low-flow oxygen resulted in a 50% reduction in pulmonary artery pressure, (4) O2 administration to mildly hypoxemic infants (SPO2 89%) caused a 50% decrease in airway resistance, and (5) low-flow oxygen reduced the frequency of intermittent hypoxemic episodes, even in infants who had values of > or =90% at rest. Based on these data, it is recommended that oxygen therapy should be considered in infants whose baseline SpO2 is <93%, and that SpO2 should be maintained at > or =95% when infants are managed at home.

Effect of exposure to 15% oxygen on breathing patterns and oxygen saturation in infants: interventional study

OBJECTIVE

To assess the response of healthy infants to airway hypoxia (15% oxygen in nitrogen).

DESIGN

Interventional study.

SETTINGS

Infants' homes and paediatric ward.

SUBJECTS

34 healthy infants (20 boys) born at term; mean age at study 3.1 months. 13 of the infants had siblings whose deaths had been ascribed to the sudden infant death syndrome.

INTERVENTION

Respiratory variables were measured in room air (pre-challenge), while infants were exposed to 15% oxygen (challenge), and after infants were returned to room air (post-challenge).

MAIN OUTCOME MEASURES

Baseline oxygen saturation as measured by pulse oximetry, frequency of isolated and periodic apnoea, and frequency of desaturation (oxygen saturation < or = 80% for > or = 4 s). Exposure to 15% oxygen was terminated if oxygen saturation fell to < or = 80% for > or = 1 min.

RESULTS

Mean duration of exposure to 15% oxygen was 6.3 (SD 2.9) hours. Baseline oxygen saturation fell from a median of 97.6% (range 94.0% to 100%) in room air to 92.8% (84.7% to 100%) in 15% oxygen. There was no correlation between baseline oxygen saturation in room air and the extent of the fall in baseline oxygen saturation on exposure to 15% oxygen. During exposure to 15% oxygen there was a reduction in the proportion of time spent in regular breathing pattern and a 3.5-fold increase in the proportion of time spent in periodic apnoea (P < 0.001). There was an increase in the frequency of desaturation from 0 episodes per hour (range 0 to 0.2) to 0.4 episodes per hour (0 to 35) (P < 0.001). In 4 infants exposure to hypoxic conditions was ended early because of prolonged and severe falls in oxygen saturation.

CONCLUSIONS

A proportion of infants had episodes of prolonged (< or = 80% for > or = 1 min) or recurrent shorter (< or = 80% for > or = 4 s) desaturation, or both, when exposed to airway hypoxia. The quality and quantity of this response was unpredictable. These findings may explain why some infants with airway hypoxia caused by respiratory infection develop more severe hypoxaemia than others. Exposure to airway hypoxia similar to that experienced during air travel or on holiday at high altitude may be harmful to some infants.

Hypoxemic events in spontaneously breathing premature infants: etiologic basis

Studies of severe hypoxemic events, defined as an arterial oxygen saturation < 80% greater than 4 s in spontaneously breathing infants, have been limited. The purpose of our study was to examine the distribution of respiratory events that lead to a fall in oximetrically measured oxygen saturation by using breathing patterns, heart rate, and validated pulse oximetry analysis. A total of 161 hypoxemic events were detected in 18 of 30 premature infants studied. Using an inductive plethysmographic based monitor, a total of 460 h of cardiorespiratory monitor recordings were analyzed. Hypoxemic events were categorized as being the direct result of apnea (duration longer than 15 s) or pauses (duration 4-14 s) with either unchanged or lower end-expiratory lung volumes compared with the preevent breaths. The breaths in the preevent period were analyzed for volume, timing, and thoracoabdominal coordination indices. Forty of the 161 events (25%) were associated with apnea of which 80% (31/40) had a mixed/obstructive basis. Ninety-four of the 161 severe hypoxemic events (58%) were associated with pauses with unchanged end-expiratory lung volume. Twenty-two of the 161 events (14%) showed pauses with lower end-expiratory lung volume. There were 5/161 events (3%) with severe hypoxemia in which no pause was observed. Comparison of the preevent periods in each category showed significant differences for only percent tidal volume from initial calibration and arterial oxygen saturation. Sixty-two percent (100/161) of severe hypoxemic events were preceded by hypopneic values of percent tidal volume. Seventy-five percent (40/161) of these hypoxemic events and their etiology would have gone undetected using respiratory monitoring from impedance pneumograms and ECGs. The varied basis for these events underscores the importance of analyzing detailed respiratory wave forms along with movement-free signal of arterial oxygen saturation and ECG, to formulate appropriate intervention strategies.

Intra-alveolar pulmonary siderophages in sudden infant death: a marker for previous imposed suffocation

Staining for iron showed previously overlooked intra-alveolar siderophages widely distributed in the lungs of two pairs of siblings, all of whom had hospital admissions for apparent life-threatening events (ALTEs) before dying suddenly at home. A mother and babysitter were convicted of their murder and manslaughter respectively. There were no siderophages in the lungs of a fifth infant whose death was included in the murder charge but who had no ALTEs. Bleeding from mouth or nose was observed during six of ten previous ALTEs suffered by these children and three unrelated infants in the same care. Such external hemorrhage is well described in imposed infant suffocation which may be one aspect of "Munchausen syndrome by proxy" child abuse. Our findings imply that there may also be intrapulmonary hemorrhage and that intra-alveolar siderophages can be a marker for previous abuse. Retrospectively we found diffusely distributed intra-alveolar siderophages in the lungs of seven of 158 infants with diagnoses of SIDS. Siderophages in such numbers demand an explanation and if this is not provided by clinical history or other necropsy findings should cause suspicion of previous imposed suffocation and infanticide and require further enquiry. The lungs should be stained for iron in all cases of sudden infant death.

Desaturation events during oral feedings with and without a nasogastric tube in very low birth weight infants

OBJECTIVE

To examine the desaturation events with the presence and absence of a nasogastric tube during an entire oral feeding in 20 very low birth weight (VLBW) infants.

DESIGN

Prospective, quasi-experimental, random assignment.

SETTING

Midwestern, university-affiliated, tertiary neonatal medical center.

PATIENTS

Twenty VLBW infants without severe neurologic problems or physical anomalies. On the day of the study, postnatal days were 17 to 82 days (49+/-18.91).

OUTCOME MEASURES

Desaturation events.

INTERVENTION

These infants were observed during oral feedings, once with a nasogastric tube and once without, at 9 am and 3 pm feedings within 1 day, decided in random order.

RESULTS

Fifteen infants experienced 166 desaturation events (<90%), 83 desaturation events without the nasogastric tube, and 83 events with the nasogastric tube present. Infants for whom desaturation events developed has a longer transition period from tube feedings to oral feedings (p<0.05), and started feedings with lower oxygen saturation (p<0.05). Nearly all desaturation events (97%) occurred with breathing pauses (11.32+/-6.67 seconds), a change in heart rate, and an increase in end-tidal CO2. The presence of a nasogastric tube increased the duration of desaturation by an average of 8 seconds (p<0.05).

CONCLUSION

Infants' oxygen saturation needs to be monitored with feedings, and feedings may need to be started with a baseline lowest saturation of 95% or higher, monitored with breathing and heart rate to prevent desaturation.