Model-based stability assessment of ventilatory control in overweight adolescents with obstructive sleep apnea during NREM sleep.

Obstructive sleep apnea (OSA) involves the interplay of several different factors such as an unfavorable upper airway anatomy, deficiencies in pharyngeal muscle responsiveness, a low arousal threshold, and ventilatory control instability. Although the stability of ventilatory control has been extensively studied in adults, little is known about its characteristics in the pediatric population. In this study, we developed a novel experimental setup that allowed us to perturb the respiratory system during natural non-rapid eye movement (NREM) sleep conditions by manipulating the inspiratory pressure, provided by a bilevel pressure ventilator, to induce sighs after upper airway stabilization. Furthermore, we present a modeling framework that utilizes the noninvasively measured ventilatory responses to the induced sighs and spontaneous breathing data to obtain representations of the processes involved in the chemical regulation of respiration and extract their stability characteristics. After validation with simulated data, the modeling technique was applied to data collected experimentally from 11 OSA and 15 non-OSA overweight adolescents. Statistical analysis of the model-derived stability parameters revealed a significantly higher plant gain and lower controller gain in the OSA group (P = 0.046 and P = 0.007, respectively); however, no differences were found in loop gain (LG) and circulatory time delay between the groups. OSA severity and LG, within the 0.03-0.04-Hz frequency band, were significantly negatively associated (r = -0.434, P = 0.026). Contrary to what has been found in adults, our results suggest that in overweight adolescents, OSA is unlikely to be initiated through ventilatory instability resulting from elevated chemical loop gain.

Autonomic and metabolic effects of OSA in childhood obesity.

This study investigates the effects of exposure to intermittent hypoxia on cardiovascular autonomic control and metabolic function in obese children with obstructive sleep apnea (OSA). Each subject underwent: (1) a polysomnography; (2) morning fasting blood samples and a subsequent FSIVGTT; (3) noninvasive measurement of respiration, arterial blood pressure, and heart rate during supine and standing postures. Assessment of adiposity was performed using a DEXA scan. From these measurements, we deduced the pertinent sleep parameters, Bergman minimal model parameters and the parameters characterizing a minimal model of cardiovascular variability. Results suggest that intermittent hypoxia in OSA contributes independently to insulin resistance and autonomic dysfunction in overweight children.

Time-varying closed-loop modeling of autonomic control in pediatric obstructive sleep apnea syndrome during cold face stimulation.

Adults with obstructive sleep apnea syndrome (OSAS) are known to have impaired autonomic function but the corresponding effects in children appear to be more subtle. Model-based analysis of the cardiovascular response to cold face test (CFT) was used to quantify daytime autonomic dysfunction. The increase in transfer gain between respiration and RRI was not different between controls and OSAS. However, the transfer gain between "surrogate cardiac output" (pulse pressure+R-R interval) and systolic blood pressure (SBP) and the transfer gain between cardiac output and SBP both increased significantly in controls but not in OSAS during CFT. These findings suggest that the parasympathetic function remains relatively normal in pediatric OSAS, but cardiovascular sympathetic reactivity is impaired.

Cardio-respiratory Uncoupling in Congenital Central Hypoventilation Syndrome.

Congenital Central Hypoventilation Syndrome (CCHS) is a rare disorder with failure of automatic control of breathing, defined by lack of an appropriate ventilatory response to hypercarbia and hypoxia. However, more detailed evaluation of cardiorespiratory coupling has not been previously performed in those with CCHS. We postulate that those with CCHS have disjointed cardiorespiratory responses to ventilatory challenges due to their alterations in sympathetic modulation. Therefore, we performed ventilatory rebreathing challenges with hypercarbia and hypoxia on 5 subjects with CCHS (age 21.2 ± 5.3 years; 3 females) and 7 controls (age 20.0 ± 4.0 years; 4 females). We measured breath-to-breath respiratory parameters (airflow, PETco2, Sao2), ECG, and continuous non-invasive blood pressure. As previously shown, when compared to controls CCHS subjects lacked ventilatory responses to isocapnic hypoxia (p=0.004) and hyperoxic hypercarbia (p=0.002). During hypercapnia, both control and CCHS subjects had similar rates of decrease in R-R intervals (RRI; slope -1.3 ± 2.5 vs. -1.4 ± 1.1, n.s.) and increase in beat-to-beat averaged blood pressure (MBP; slope 1.2 ± 0.3 vs. 0.4 ± 0.1, n.s.) as PETco2increased. During hypoxia, both control and CCHS groups had similar rates of decrease in RRI (slope 14.2 ± 3.0 vs. 7.5 ± 3.9, n.s.) and increase in MBP (slope -1.11 ± 1.12 vs. -0.9 ± 0.8, n.s.) as Sao2decreased. We conclude that despite having a markedly diminished ventilatory response to hypercarbia and hypoxia, subjects with CCHS have normal cardiovascular responses to these challenges. We speculate that this indicates that chemoreceptors are functional.

Noninvasive assessment of cardiovascular autonomic control in pediatric obstructive sleep apnea syndrome.

Studies suggest that Obstructive Sleep Apnea Syndrome (OSAS) is causally related to abnormal cardiovascular autonomic control in adults, but this has not been established in pediatric OSAS. The goal of this study was to quantify autonomic system dysfunction, as manifested by cardiovascular response abnormalities, in children with OSAS. During wakefulness, we continuously measured the ECG, arterial blood pressure and airflow in each subject. These measurements were made during the following conditions: spontaneous breathingin the supine posture (baseline), spontaneous breathing in the standing posture (orthostatic stress); tracking of the subject's own prior spontaneous breathing pattern while supine (mental stress), and during a cold face challenge. Using spectral analysis and modeling techniques, we sought to computationally delineate the physiological mechanisms that mediate these abnormalities. Our preliminary results suggest that the autonomic effects of pediatric OSAS differ from those in adult in that parasympathetic activity remains relatively normal despite the elevated peripheral sympathetic drive.

Noninvasive assessment of cardiovascular autonomic control in pediatric obstructive sleep apnea syndrome.

Studies suggest that obstructive sleep apnea syndrome (OSAS) is causally related to abnormal cardiovascular autonomic control in adults, but this has not been established in pediatric OSAS. The goal of this study was to quantify autonomic system dysfunction, as manifested by cardiovascular response abnormalities, in children with OSAS. During wakefulness, we continuously measured the ECG, arterial blood pressure and airflow in each subject. These measurements were made during the following conditions: spontaneous breathing in the supine posture (baseline), spontaneous breathing in the standing posture (orthostatic stress); tracking of the subject's own prior spontaneous breathing pattern while supine (mental stress), and during a cold face challenge. Using spectral analysis and modeling techniques, we sought to computationally delineate the physiological mechanisms that mediate these abnormalities. Our preliminary results suggest that the autonomic effects of pediatric OSAS differ from those in adult in that parasympathetic activity remains relatively normal despite the elevated peripheral sympathetic drive.

Noninvasive assessment of cardiovascular autonomic control in congenital central hypoventilation syndrome.

The goal of this study was to quantify autonomic system dysfunction, as manifested by cardiovascular and respiratory response abnormalities, in patients with congenital central hypoventilation syndrome (CCHS). During wakefulness, we continuously measured the ECG, arterial blood pressure (ABP), airflow, end-tidal CO2 partial pressure (PETCO2), and arterial oxygen saturation (SatO2) in each subject. These measurements were made during spontaneous breathing in supine, sitting and standing postures, and also when each subject tracked his/her prior spontaneous breathing pattern while supine. We also performed the cold face test, hyperoxic hypercapnic rebreathing and the isocapnic hypoxic rebreathing challenges. Using spectral analysis and modeling techniques, we sought to computationally delineate the physiological mechanisms that mediate these abnormalities, as well as to determine the extent to which these abnormalities are related to peripheral or central chemoreflex dysfunction. Our preliminary results support the notion that sympathetic tone is markedly elevated in CCHS, and that differences in autonomic control from normal controls can be delineated by observing the responses to different stressors.

The expression of functional LPS receptor proteins CD14 and toll-like receptor 4 in human corneal cells.

PURPOSE: Gram-negative bacterial infections of the eye can lead to corneal bacterial keratitis, visual impairment, and blindness. Many of these pathologic changes may be mediated by bacterially derived products such as lipopolysaccharide (LPS). In this investigation, it has been established for the first time that human corneal cells are capable of expressing the functional LPS receptor complex proteins, CD14 and Toll-like receptor 4 (TLR4). METHODS: CD14 and TLR4 mRNA expression in human corneal cells was determined by RT-PCR and Northern blot analysis, and cell surface expression of these proteins was measured by flow cytometry. LPS-mediated corneal cell activation was determined by measuring intracellular calcium mobilization. Cellular cytokine and chemokine secretion in response to LPS was measured by ELISA. The expression and localization of CD14 in whole human cornea was determined by immunohistochemistry. RESULTS: Human corneal epithelial, stromal, and endothelial cells expressed CD14 mRNA and cell surface CD14. LPS binding to cornea CD14 resulted in a rapid intracellular calcium response and the secretion of multiple proinflammatory cytokines and chemokines. CD14 mRNA expression in corneal epithelial cells was upregulated by LPS. In addition to CD14, corneal epithelial cells expressed the functional LPS receptor-signaling protein TLR4, which was also augmented by LPS. CONCLUSIONS: The cornea expresses functional CD14 and TLR4 LPS receptor proteins. Understanding the function and biology of the corneal LPS receptor complex may lead to novel therapies for the management of ocular Gram-negative bacterial infections.

Home ventilator low-pressure alarms fail to detect accidental decannulation with pediatric tracheostomy tubes.

BACKGROUND: Positive-pressure ventilators are equipped with low-inspiratory-pressure alarms to protect patients from hypoventilation. Small uncuffed tracheostomy tubes have a high resistance, and may not trigger these alarms during decannulation. STUDY OBJECTIVE: To determine whether ventilator low-inspiratory-pressure alarms are effective in detecting tracheostomy decannulation. DESIGN: We connected tracheostomy tubes of varying inner diameters (3.0 to 6.0 mm) to a home ventilator and simulated decannulation using low (tidal volume [VT], 600 mL; peak inspiratory pressure [PIP], 25 cm H(2)O), medium (VT, 800 mL; PIP, 30 cm H(2)O), and high (VT, 1,000 mL; PIP, 35 cm H(2)O) ventilator settings. RESULTS: When the ventilator low-inspiratory-pressure alarm was set at 4 cm H(2)O below the desired PIP, it failed to alarm for simulated decannulation of tracheostomy tubes < 4.5 mm on low and medium settings, and < 4.0 mm on high settings. When the ventilator low-inspiratory-pressure alarm was set at 10 cm H(2)O below the desired PIP, it failed to alarm with tracheostomy tubes < 6.0 mm. CONCLUSION: We conclude that ventilator low-inspiratory-pressure alarms fail to alarm during simulated decannulation with small tracheostomy tubes commonly used in children. We speculate that low-inspiratory-pressure alarms set at 4 cm H(2)O below the desired PIP will detect more decannulation than when set at 10 cm H(2)O below the desired PIP.

Interleukin-18 expression and modulation in human corneal epithelial cells.

PURPOSE: The interferon-gamma-inducing factor Interleukin-18 (IL-18) is a recently described cytokine that appears to have multiple important pro-inflammatory effects including the induction of interferon-gamma (IFN-gamma) by activated T-cells. The expression of IL-18 by human cornea has not been previously reported. In the present study, we examine the possibility that human corneal epithelial cells are capable of producing this leukocyte-activating factor which may play an important role in IFN-gamma-dependent inflammation responses in the cornea. METHODS: Northern blot analysis and ELISA were used to investigate the in vitro expression of IL-18 mRNA and protein respectively in primary (HCEC) and transformed human corneal epithelial cells (HCET). To determine if IL-18 expression was modulated by pro-inflammatory mediators, cells were treated with lipopolysaccharide (LPS), phorbol 12-myristate 13-acetate (PMA) or synthetic double stranded RNA (poly dI : dC). IL-18 bioactivity was determined in a leukocyte interferon-gamma induction assay and IL-18 was immunolocalized in whole human cornea by immunohistochemistry using a specific anti-IL-18 antibody. RESULTS: IL-18 mRNA and bioactive protein was constitutively expressed by human corneal epithelial cells and upregulated by PMA, LPS and poly dI : dC. The constitutive expression of IL-18 protein immunoreactivity was also demonstrated in the epithelial cells of whole human cornea tissue. CONCLUSIONS: This is the first study demonstrating that corneal epithelial cells are capable of producing the IFN-gamma inducing factor IL-18. Increased bioactive corneal IL-18 production can be induced by a number of pro-inflammatory agents and may play an important role in initiating gamma-interferon-mediated inflammatory responses in the cornea.

Latex allergy in children on home mechanical ventilation.

STUDY OBJECTIVE: Determining the incidence of latex allergy in children receiving home mechanical ventilation. BACKGROUND: The prevalence of latex allergy in the general population ranges from 0.1 to 1.0%. However, in patients with spina bifida and other chronic medical conditions associated with repeated exposure to latex, the prevalence may be as high as 60%. Children receiving home mechanical ventilation are frequently exposed to latex products. Therefore, we hypothesized that these children would be at increased risk for latex allergy. DESIGN: Fifty-seven children receiving home mechanical ventilation (31 boys, 26 girls; mean [+/- SD] age, 7.8+/-6.6 years; range, 0.3 to 23.2 years) were enrolled. A radioallergosorbent test (RAST) for latex was administered and serum IgE levels were obtained in all patients. RESULTS: Seventeen patients (29.8%) were found to have a positive RAST for latex. Patients with latex allergy had required mechanical ventilation for an average of 6.1+/-4.1 years vs. 5.5+/-5.4 years (p = 0.69; not significant) in those without latex allergy. Eleven of 17 patients (64.7%) had elevated serum IgE levels in the group with latex allergy vs only 14 of 40 patients (35.0%) in the group with a negative latex RAST (p = 0.04; odds ratio, 3.4). CONCLUSION: We conclude that there is a high incidence of latex allergy in children requiring home mechanical ventilation. We speculate that screening all children receiving home mechanical ventilation may lead to the identification of patients with previously undiagnosed latex allergy and the prevention of untoward reactions from exposure to latex.

Should children with suspected obstructive sleep apnea syndrome and normal nap sleep studies have overnight sleep studies?

STUDY OBJECTIVES: Overnight polysomnography (ONP) is the "gold standard" for the diagnosis of sleep-disordered breathing, but it is expensive and time-consuming. Thus, daytime nap studies have been used as screening tests. If the findings of a nap study are normal or mildly abnormal, should ONP be performed? Do specific abnormalities in nap studies predict abnormal findings in ONP? To answer these questions, we conducted this study. DESIGN: Retrospective chart review. SETTING: Children's hospital. PARTICIPANTS: One hundred forty-three children with suspected obstructive sleep apnea syndrome secondary to isolated adenotonsillar hypertrophy, who had normal or mildly abnormal nap studies, and underwent ONP. MEASUREMENTS AND RESULTS: We compared daytime nap and overnight polysomnograms in 143 children (52 girls; mean [+/- SD] age, 5.6 +/- 3.1 years). Total sleep time was 1 h in daytime nap, and 5.1 +/- 1.3 h in ONP. The interval between the two studies was 5.9 +/- 4.8 months. The findings of 59% of the nap studies were mildly abnormal, while 66% of overnight studies were abnormal. No individual nap study parameter (including short obstructive apneas, hypopneas, hypoxemia, hypoventilation, snoring, paradoxical breathing, gasping, retractions) had good sensitivity at predicting abnormal overnight polysomnograms, but most had good specificity and positive predictive value. CONCLUSIONS: We conclude that individual nap study parameters are not very sensitive in predicting abnormal ONP findings. However, when nap study parameters are abnormal, the chance of obstructive sleep apnea syndrome is high.

Comparison of apnea identified by respiratory inductance plethysmography with that detected by end-tidal CO(2) or thermistor. The CHIME Study Group.

As part of the Collaborative Home Infant Monitoring Evaluation (CHIME) we compared apnea identified by a customized home monitor using respiratory inductance plethysmography (RIP) with simultaneously recorded polysomnography-acquired nasal end-tidal CO(2) (PET(CO(2))) and nasal/oral thermistor in 422 infants during overnight laboratory recordings to determine concordance between techniques, sources of disagreement, and capacity of RIP to detect obstructed breaths within an apnea. Among 233 episodes of apnea identified by at least one method as >/= 16 s, 120 were observed by the CHIME monitor, 219 by PET(CO(2)), and 163 by thermistor. The positive predictive value of the CHIME-identified apnea was 89.2% (95% CI 83, 95) and 73% (95% CI 65, 81) for PET(CO(2)) and thermistor, respectively. However, the sensitivity of the CHIME monitor in identifying events detected by the other methods was only approximately 50%. Among 87 apnea events identified by all three techniques, no two methods showed high agreement in measurement of apnea duration: RIP and PET(CO(2)) (ICC = 0.54), RIP and thermistor (ICC = 0.13), PET(CO(2)) and nasal thermistor (ICC = 0.41). Among the 179 breaths identified by RIP as obstructed, 79.9% were judged to be obstructed on the PET(CO(2)) and 80.4% were judged to be obstructed on the thermistor channel. Among 238 breaths identified on PET(CO(2)) as obstructed, 54.2% were determined to be obstructed by RIP. Among 204 breaths identified on thermistor as obstructed, 55. 4% were determined to be obstructed by RIP. Reasons for discrepancies in apnea detection among channels included body movement, partial airway obstruction, and obstructed breaths. Despite these limitations the CHIME monitor provides an opportunity to record physiological data previously unavailable in the home.

Sleep apnea treatment improves seizure control in children with neurodevelopmental disorders.

Seizure disorder and sleep apnea are common chronic disorders in children, but the relationship between sleep apnea and seizure control has not been studied in the pediatric population. This retrospective review included nine children with neurodevelopmental disorders who had well-documented sleep apneic episodes and seizure disorders. Seizure frequency was reduced in five patients (56%) in the first 12 months after sleep apnea treatment without changes in their antiepileptic medications. Sleep apnea can be one of the seizure precipitants in children with epilepsy. This study indicates the importance of identifying sleep apnea when treating children with intractable epilepsy, particularly in those who are at high risk.

A Comparison of Three Cytotoxicity Endpoints in the Corneal HCE-T Model.

The prediction of ocular irritation potential from in vitro assays still presents a problem, despite a number of validation trials. A study with coded cosmetic formulations, for which historic in vivo data were available, has been conducted with a human corneal multi-layered model system. This corneal model, the HCE-T model, was developed by using HCE-T cells, a transfected human corneal epithelial cell line. The relative effectiveness of three endpoints that provide a measure of cytotoxicity in the HCE-T model was evaluated. Cell viability immediately after exposure to the test materials was determined by using the MTT and Alamar Blue™ (AB) assays, and, 24 hours later, by using the MTT, AB and lactate assays. Viability measurements with the MTT, AB and lactate assays gave similar dose-response curves at the 24-hour endpoint. One formulation (an anti-dandruff shampoo) caused a less severe drop in viability in assays conducted immediately after the exposure than at the 24-hour time-point. There was little deterioration in viability with the other test materials. The ranking of the test formulations on the basis of relative loss of viability and release of lactate resulted in the same order as for the Modified Maximum Average Draize Test Score. Comparison of the HCE-T model cytotoxicity assay results with historic in vitro data from two different cytotoxicity assays, conducted by using fibroblast monolayer cultures and the same materials, indicated that the multi-layered corneal model had a greater predictive ability. The results of a blind trial with the lactate assay in two laboratories indicated that the techniques required were transferable between laboratories. The lactate results were reproducible between laboratories, even when cultures derived from different passage human corneal cells were tested, provided that the passage number was below 20.

Frequency, causes, and outcome of home ventilator failure.

STUDY OBJECTIVES: The safety of home ventilators has been questioned. We collected data to study the following: frequency of home ventilator failure, apparent causes for the failure or malfunction, and adverse consequences following the failure. STUDY DESIGN: Information on all requests to correct home ventilator failures reported to a home respiratory equipment vendor was collected prospectively between November 1991, and November 1992. PATIENTS: There were 150 ventilator-assisted patients aged 2 to 77 years; 44 were < or = 18 years. They received 841,234 h of home mechanical ventilation (average, 15.4 h/d per ventilator-assisted patient). RESULTS: There were 189 reports of home ventilator failure. Defective equipment or mechanical failure was found in only 39% (73 reports), equivalent to one home ventilator failure for every 1.25 years of continuous use. Other causes of ventilator failure included the following: improper care, damage, or tampering with the ventilator by caregivers (13%), functional equipment improperly used by caregivers (30%), and equipment functional but the patient's condition changed, mimicking ventilator failure (3%). No problem could be identified in 16%. The following actions were required: ventilator replacement (44%), repair of a defective part (6%), replacement of a functioning ventilator for psychological comfort (14%), ventilator adjustments made (21%), caregiver reeducation (7%), caregiver anxiety or distress reduced (3%), and no action required (4%). Hospitalization was required only in two cases (1%). No adverse outcomes, deaths, or serious injuries were associated with home ventilator failure. CONCLUSIONS: We conclude that in 150 patients requiring home mechanical ventilation, ventilator failure occurred relatively infrequently, and there were no adverse outcomes as a result of equipment failure at home. We speculate that equipment failure is not a frequent or serious problem for ventilator-assisted patients treated at home.

Comorbidity of hyperactivity-impulsivity-inattention and conduct problems: risk factors in social, affective, and academic domains.

Children showing a comorbid behavior pattern of hyperactivity-impulsivity-inattention and conduct problems (HIA + CP) were contrasted to children having only an internalizing and externalizing behavior pattern (I + E) and matched controls. Children displaying the HIA + CP behavior pattern were at greater risk on a number of outcome measures in social and academic domains beginning in Grade 3 and continuing into Grade 4. The most marked differences among the three groups were found on peer measures of rejection and friendship and teacher ratings of social skills. On average, almost two-thirds of the HIA + CP group were rejected by their peers compared to one-third of the I + E group and only 12.5% controls. Over 70% of the HIA + CP group had no reciprocated friendships from Grade 3 to Grade 4 compared to less than half of the I + E group and approximately one-fourth of controls. Contrary to much theorizing in the literature, the HIA + CP and I + E groups showed average levels of academic self-concept and did not differ from controls in on measures of social self-concept and academic self-concept and general self-esteem. These findings were interpreted in light of positive illusory biases and the established link between aggressive behavior and egotism. The current article offers partial support for Lynam's (1996) notion of the "fledgling psychopath."

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

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

Factors associated with the transition to nonprone sleep positions of infants in the United States: the National Infant Sleep Position Study.

CONTEXT: Studies have demonstrated strong associations between the prone sleep position (on the stomach) and sudden infant death syndrome (SIDS). In 1992, the American Academy of Pediatrics recommended that infants be placed to sleep laterally (on their side) or supine (on their back) to reduce SIDS risk, and in 1994, the national public education campaign "Back to Sleep" was launched. OBJECTIVE: To determine the typical sleep position of infants younger than 8 months in the United States, the changes that occurred after these recommendations, and the factors associated with the placement of infants prone or supine. DESIGN: Annual nationally representative telephone surveys. SETTING: The 48 contiguous states of the United States. PARTICIPANTS: Nighttime caregivers of infants born within the last 7 months between 1992 and 1996. Approximately 1000 interviews were conducted per year. MAIN OUTCOME MEASURES: The position the infant was usually placed in for sleep, and the position the infant was most commonly found in when checked during the night's sleep. RESULTS: Ninety-seven percent of respondents in each wave of the survey usually placed their infant to sleep in a specific position. Infants were placed in the prone position by 70% of caregivers in 1992, prior to the campaign, but only 24% in 1996. Supine and lateral placements increased during this time period, from 13% in 1992 to 35% in 1996 and from 15% in 1992 to 39% in 1996, respectively. Significant predictors of prone placement included maternal race reported as black (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.68-3.26), mother's age 20 to 29 years (OR, 1.28; 95% CI, 1.09-1.50), region reported as the mid-Atlantic (OR, 1.41; 95% CI, 1.12-1.78) or southern states (OR, 1.47; 95% CI, 1.22-1.70), mothers with a previous child (OR, 1.68; 95% CI, 1.43-1.97), and infants younger than 8 weeks (OR, 0.63; 95% CI, 0.46-0.85). Infants aged 8 to 15 weeks were significantly more likely to be placed nonprone over time compared with the other age groups. Most of the risk factors for prone were significantly related in the opposite direction to supine placement. CONCLUSIONS: The prevalence of infants placed in the prone sleep position declined by 66% between 1992 and 1996. Although causality cannot be proved, SIDS rates declined approximately 38% during this period. To achieve further reduction in prone sleeping, efforts to promote the supine sleep position should be aimed at groups at high risk for prone placement.

Caring and healing in the 21st century.

As the 21st century approaches, nurses must be prepared to offer new treatment methods when caring for children. The purpose of this article is to familiarize nurses with human caring theory and complementary and alternative medicine, and to offer a practical way of integrating these methods into nursing care. Nurses can learn to choose simple, conservative, noninvasive, nonintrusive healing methods that are met with little resistance by other health care professionals. Clinical implications of the Nurse's Tool Box suggest methods such as drawing, acupressure, guided imagery, storytelling, therapeutic touch, soft music, and humor as ways to help children heal. By tapping into certain frequency currents through the use of these tools, nurses may build, repattern, or facilitate human energies to replenish children's minds, bodies, and souls, creating wholeness and harmony. By understanding human caring theory and complementary and alternative medicine, and by using a practical approach to healing, nurses in the new century can mend children in ways they never have before.