James S. Kemp

Sudden death in infants sleeping on polystyrene-filled cushions

BACKGROUND Infants are at risk for both the sudden infant death syndrome (SIDS) and accidental suffocation. On postmortem examination, however, it is difficult to distinguish one from the other without information from the scene of death. Healthy infants are assumed to be able to turn their heads and, if not otherwise restrained, to obtain fresh air. We assessed this assumption in an investigation of infant deaths that occurred during sleep on cushions filled with polystyrene beads. METHODS We obtained data on 25 deaths from the U.S. Consumer Product Safety Commission. We also used mechanical and animal models to study physiologic aspects of ventilation relevant to these results, by simulating the effects on an infant of breathing into a cushion. We measured the effects of softness, malleability (molding of the cushion about an infants head), airflow resistance, and rebreathing of expired gases. RESULTS All 25 study infants were prone when found dead, and at least 88 percent were face down with nose and mouth obstructed by the cushion. SIDS was the diagnosis in 19 of the 23 infants who underwent autopsy. Our findings show, however, that the cushion would have limited movement of the infants head to obtain fresh air, and the amount of rebreathing we estimated to have occurred in the infants was lethal in a rabbit model. CONCLUSIONS Accidental suffocation by rebreathing was the most likely cause of death in most of the 25 infants studied. Consequently, there is a need to reassess the cause of death in the 28 to 52 percent of the victims of SIDS who are found with their faces straight down. Safety regulations setting standards for softness, malleability, and the potential for rebreathing are needed for infant bedding.

Physical Properties of Bedding That May Increase Risk of Sudden Infant Death Syndrome in Prone-Sleeping Infants

ABSTRACT: Soft bedding has been shown in epidemiologic studies to increase the risk for sudden, unexpected death in prone-sleeping infants. We compared the physical properties of conventional bedding to bedding from two sources: 7) bedding that covered the airways of victims of sudden infant death syndrome (SIDS) lying prone and face down at the time of death; and, 2) bedding associated with increased risk for SIDS in case-control studies (i.e. bedding filled with ti tree bark). Using simple mechanical models and the head from an infant mannequin, we measured the resistance to airflow, malleability, and capacity to limit CO2 dispersal of the bedding. We also describe a technique for quantifying bedding softness. The resistance and malleability were similar for the conventional bedding, the ti tree bedding, and the bedding from SIDS deaths (analysis of variance, p = 0.85 and 0.16). The ti tree bedding and the other bedding from SIDS cases differed from conventional bedding in two physical properties. Both groups were softer (p ≤ 0.005) and limited CO2 dispersal to a greater degree (p ≤ 0.009). The finding that increased capacity to limit CO2 dispersal is a consistent property of the bedding covering the airways of these SIDS victims and of bedding shown to be an epidemiologic risk factor for SIDS supports rebreathing of expired air as a mechanism underlying the association of certain kinds of bedding with SIDS.

Softness and potential to cause rebreathing: Differences in bedding used by infants at high and low risk for sudden infant death syndrome

OBJECTIVE This study was carried out to determine whether bedding used by infants, who are at either high or low risk for sudden infant death syndrome (SIDS), differs in physical properties favoring rebreathing of exhaled gases. STUDY DESIGN We compared softness and limitation of carbon dioxide dispersal by bedding, using a mechanical model. A questionnaire was used to describe sociodemographic risk factors and sleep practices; bedding was studied in homes with a model positioned where each infant was found sleeping that morning. RESULTS The groups differed with respect to five sociodemographic risk factors (p values all < or = 0.0001). In addition, infants at higher risk were more likely to have been placed to sleep prone (46%, p = 0.02) by parents who were less likely to be aware of the risk associated with the prone position (62% aware, p = 0.005). Infants at higher risk had softer bedding (p < 0.0001, 54.1+/-17.2 cm2 vs 33.7+/-7.7 cm2 in contact with model), which caused more limitation of carbon dioxide dispersal (p = 0.008; CO2 retained, 0.60%+/-0.15% vs 0.34%+/-0.05%). CONCLUSIONS A series of infants who are at high risk for SIDS because of sociodemographic factors more often sleep on bedding that has physical properties favoring rebreathing, and their parents are less often aware of the risk associated with prone sleeping.

Evaluation of Ventilatory efficiency during exercise in patients with idiopathic scoliosis undergoing spinal fusion

Study Design. A prospective evaluation of ventilatory function following spinal fusion in adolescent idiopathic scoliosis. Objectives. To prospectively evaluate pulmonary function, maximal oxygen uptake, and ventilatory efficiency during exercise in patients with adolescent idiopathic scoliosis before surgery and a minimum of 2 years postoperation. Summary of Background Data. For reasons that are unclear, patients with untreated adolescent idiopathic scoliosis tend to avoid aerobic exercise. Their reluctance may be the result of low ventilatory efficiency, as they often approach their ventilatory ceiling at maximum oxygen uptake despite forced vital capacities that are near normal. This inefficiency of ventilation with exercise may explain the reluctance of patients with scoliosis to pursue aerobic fitness. No study has evaluated the effect spinal fusion has on the ventilatory function of patients with scoliosis during exercise. Methods. Forty-two patients with adolescent idiopathic scoliosis (36 female and 6 male) at an average age of 14 ± 3 years (range 10–18 years) underwent spinal fusion. Twenty patients underwent a posterior spinal fusion alone, 20 an anterior spinal fusion alone, and 2 an anterior spinal fusion and posterior spinal fusion. The average Cobb measurement was 55° (range 40–85°). Pulmonary function values (forced vital capacity, total lung capacity, maximum voluntary ventilation), maximum oxygen uptake (VO2max), and ventilatory efficiency were obtained before surgery and a minimum of 2 years postoperation. Results. For all patients, forced vital capacity percent predicted decreased from 88.1% to 81.4% (P < 0.0001). Total lung capacity also declined from 90.5% to 88.5% but was not statistically significant (P = 0.189). Percent predicted maximum oxygen uptake (VO2max) declined from 93.6% to 85.1% (P = 0.00029). Ventilatory efficiency, as measured by VEmax/maximum voluntary ventilation, improved from 0.76 to 0.68 (P = 0.005), whereas measured by VEmax/FEV1 × 40 was unchanged from 0.69 to 0.70 (P = 0.172) postoperation. The choice of operative approach [anterior (n = 20) versus posterior (n = 20)] or whether rib graft was harvested (n = 33) versus iliac crest graft (n = 7) did not change these results. Conclusion. Improvement in ventilatory efficiency during exercise does not occur in the majority of patients with adolescent idiopathic scoliosis following spinal fusion and thus cannot be relied on to foster increases in aerobic activity.

Classification system for the Sudden Unexpected Infant Death Case Registry and its application.

Sudden unexpected infant deaths (SUID) accounted for 1 in 3 postneonatal deaths in 2010. Sudden infant death syndrome and accidental sleep-related suffocation are among the most frequently reported types of SUID. The causes of these SUID usually are not obvious before a medico-legal investigation and may remain unexplained even after investigation. Lack of consistent investigation practices and an autopsy marker make it difficult to distinguish sudden infant death syndrome from other SUID. Standardized categories might assist in differentiating SUID subtypes and allow for more accurate monitoring of the magnitude of SUID, as well as an enhanced ability to characterize the highest risk groups. To capture information about the extent to which cases are thoroughly investigated and how factors like unsafe sleep may contribute to deaths, CDC created a multistate SUID Case Registry in 2009. As part of the registry, the Centers for Disease Control and Prevention developed a classification system that recognizes the uncertainty about how suffocation or asphyxiation may contribute to death and that accounts for unknown and incomplete information about the death scene and autopsy. This report describes the classification system, including its definitions and decision-making algorithm, and applies the system to 436 US SUID cases that occurred in 2011 and were reported to the registry. These categories, although not replacing official cause-of-death determinations, allow local and state programs to track SUID subtypes, creating a valuable tool to identify gaps in investigation and inform SUID reduction strategies.

Keep Your Eyes on the Prize

No wonder you activities are, reading will be always needed. It is not only to fulfil the duties that you need to finish in deadline time. Reading will encourage your mind and thoughts. Of course, reading will greatly develop your experiences about everything. Reading keep your eyes on the prize is also a way as one of the collective books that gives many advantages. The advantages are not only for you, but for the other peoples with those meaningful benefits.

Potential to Prevent Carbon Dioxide Rebreathing of Commercial Products Marketed to Reduce Sudden Infant Death Syndrome Risk

Objective. Rebreathing of exhaled air is one proposed mechanism for the increased risk for sudden infant death syndrome among prone sleeping infants. We evaluated how carbon dioxide (CO2) dispersal was affected by a conventional crib mattress and 5 products recently marketed to prevent prone rebreathing. Setting. Infant pulmonary laboratory. Equipment. An infant mannequin with its nares connected via tubing to an 100-mL reservoir filled with 5% CO2. The sleep surfaces studied included: firm mattress covered by a sheet, Bumpa Bed, Breathe Easy, Kid Safe/Baby Air, Halo Sleep System, and Sleep Guardian. The mannequin was positioned prone face-down or near-face-down. The sleep surfaces were studied with the covering sheet taut, covering sheet wrinkled, and with the mannequin arm positioned up, near the face. Measurements. We measured the fall in percentage end-tidal CO2 as the reservoir was ventilated with the piston pump. The half-time for CO2 dispersal (t1/2) is an index of the ability to cause or prevent rebreathing. Results. Compared with the face-to-side control, 5 of 6 surfaces allowed a significant increase in t1/2 in all 3 prone scenarios. The firm mattress and 4 of the 5 surfaces designed to prevent rebreathing consistently allowed t1/2 above thresholds for the onset of CO2 retention and lethal rebreathing in an animal model (J Appl Physiol. 1995;78:740). Conclusions. With very few exceptions, infants should be placed supine for sleep. For infants placed prone or rolling to the prone position, significant rebreathing of exhaled air would be likely on all surfaces studied, except one.

Ventilatory control and supplemental oxygen in premature infants with apparent chronic lung disease

Objectives Our goal was to evaluate changes in respiratory pattern among premature infants born at <29 weeks gestation who underwent a physiological challenge at 36 weeks postmenstrual age with systematic reductions in supplemental oxygen and inspired airflow. Study design Subjects were all infants enrolled in the Prematurity and Respiratory Outcomes Project at St. Louis Childrens Hospital and eligible for a physiological challenge protocol because they were receiving supplemental oxygen or augmented airflow alone as part of their routine care. Continuous recording of rib cage and abdominal excursion and haemoglobin oxygen saturation (SpO2%) were made in the newborn intensive care unit. Results 37 of 49 infants (75.5%) failed the challenge, with severe or sustained falls in SpO2%. Also, 16 of 37 infants (43.2%) who failed had marked increases in the amount of periodic breathing at the time of challenge failure. Conclusions An unstable respiratory pattern is unmasked with a decrease in inspired oxygen or airflow support in many premature infants. Although infants with significant chronic lung disease may also be predisposed to more periodic breathing, these data suggest that the classification of chronic lung disease of prematurity based solely on clinical requirements for supplemental oxygen or airflow do not account for multiple mechanisms that are likely contributing to the need for respiratory support.

Sources of Methodological Variability in Phase Angles from Respiratory Inductance Plethysmography in Preterm Infants

RATIONALE Better phenotypic descriptions are needed for chronic lung disease among surviving premature infants. OBJECTIVES The purpose of this study was to evaluate the potential usefulness of respiratory inductance plethysmography in characterizing respiratory system mechanics in preterm infants at 32 weeks postmenstrual age. METHODS Respiratory inductance plethysmography was used to obtain the phase angle, Φ, to describe rib cage and abdominal dyssynchrony in 65 infants born between 23 and 28 weeks gestation, all of whom were studied at 32 weeks postmenstrual age. Up to 60 breaths were evaluated for each subject. Sources of intrasubject variability in Φ arising from our methods were explored using mechanical models and by evaluating interobserver agreement. MEASUREMENTS AND MAIN RESULTS The mean Φ from infants ranged from 5.8-162.9°, with intrasubject coefficients of variation ranging from 11-123%. On the basis of the mechanical model studies, respiratory inductance plethysmography recording and analysis software added <2.3% to the intrasubject variability in Φ. Potential inconsistencies in breaths selected could have contributed 8.1%, on average, to the total variability. The recording sessions captured 22.8 ± 9.1 minutes of quiet sleep, and enough breaths were counted to adequately characterize the range of Φ in the session. CONCLUSION Φ is quite variable during even short recording sessions among preterm infants sleeping quietly. The intrasubject variability described herein arises from the instability of the rib cage and abdominal phase relationship, not from the recording and analytical methods used. Despite the variability, Φ measurements allowed the majority (80%) of infants to be reliably categorized as having relatively synchronous or dyssynchronous breathing. Respiratory inductance plethysmography is easy to use and should prove useful in quantifying respiratory mechanics in multicenter studies of preterm infants.

Stability of Polysomnography for One Year and Longer in Children with Sickle Cell Disease

STUDY OBJECTIVES Serious morbidity may be linked to sleep disordered breathing (SDB) among children with sickle cell disease (SCD). We investigated the stability of polysomnography (PSG) results among children not having acute complications of SCD. METHODS Two PSGs were performed on a subsample of 63 children 4 to 18 years of age from the Sleep and Asthma Cohort Study. All had Hb SS or HbSβ(0) disease. Two PSGs were compared for 45 subjects. Excluded from comparison were 18 children who had begun transfusions or hydroxyurea, had an adenotonsillectomy between the PSGs, or had a pain crisis or the acute chest syndrome within 3 months of the second PSG. Sleep disordered breathing was identified using 2 thresholds for the apnea hypopnea index (AHI): ≥ 2 or ≥ 5 respiratory events per hour. RESULTS Ages were 12.3 yrs ± 4.0, BMI, 18.2 ± 3.2. Interval between PSGs was 581 ± 119 days (19.1 ± 3.9 months). Ten of 45 changed from ≥ 2 events per hour to < 2; 3 of 45 from < 2 to ≥ 2; 7 of 45 had ≥ 2 on both nights. Six of 45 changed from ≥ 5 to < 5, 2 of 45 from < 5 to ≥ 5, and 1 had ≥ 5 on both nights (McNemar χ(2), p = 0.09, and p = 0.29). CONCLUSIONS In the absence of acute SCD complications, overnight PSG usually remains stable or improves over a 12- to 30-month period. Only 6.7% subjects, or fewer, had AHI on a subsequent PSG that would re-classify the child as having SDB not identified in the earlier PSG.