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Biomedical subjects

R T Brouillette

Publications and source records attributed to R T Brouillette.

At least 37 records · Page 2Linked to original sources
PubMed1996

Face-straight-down and face-near-straight-down positions in healthy, prone-sleeping infants.

OBJECTIVE: To determine the frequency and physiologic consequences of the face-straight-down (FSD) position, a postulated mechanism for the sudden infant death syndrome in prone-sleeping infants. STUDY DESIGN: A survey of 151 infants, aged 1 to 7 months, in Montreal showed that 33% slept prone. Ten healthy prone-sleeping infants were studied in their homes at age 10 to 22 weeks. Infrared video and cardiorespiratory recordings were made on 3 consecutive nights in the prone (nights 1 and 3) and lateral (night 2) positions. RESULTS: Infants maintained the prone position during 17 of 19 studies, but only 4 of 9 infants maintained the lateral position. The FSD position was observed 27 times in 17 prone nights: median frequency, 0.6 times per night (interquartile range, 0 to 4), and median total duration, 3.3 minutes (0.8% of total sleep time). A related position, the face-near-straight-down (FNSD) position, occurred more often, 5.3 (1 to 10) time per prone night, for 22.4 minutes (5.8% of total sleep time). Most periods in the FSD and FNSD position had no physiologic consequences; however, 14% of FSD and 3% of FNSD episodes were associated with airway obstruction as indicated by snoring, paradoxical respiratory movements, apnea, and/or increased partial pressure of transcutaneous carbon dioxide. Spontaneous arousal and head turning terminated the FSD and FNSD episodes. CONCLUSION: The FSD and FNSD positions occur commonly in healthy prone-sleeping infants, and these positions can cause airway obstruction. We speculate that those infants with sudden infant death syndrome found in the FSD or FNSD position either have a congenital or an acquired defect in the arousal-head turning response or have encountered insurmountable environmental factors that prevent effective head turning.

Airway Obstruction↗
PubMed1996

Can sleep and wakefulness be distinguished in children by cardiorespiratory and videotape recordings?

Polysomnography, including EEG recording, is the standard method to diagnose obstructive sleep apnea (OSA) in children and adults. Diagnosis of OSA would be considerably simplified if it was shown that sleep could be distinguished from wakefulness without EEG recordings. Therefore, we compared sleep/wakefulness classification using a simplified cardiorespiratory-video (CRV) method with standard polysomnography in 20 children undergoing in-hospital evaluation for OSA. The channels for the simplified montage were chosen because they (1) were suitable for unattended, home recordings, (2) allowed the diagnosis of apneas, hypopneas, desaturation, and movement/arousals, and (3) did not require attachment to the head or face that might disturb the childs sleep. Sleep staging by the two methods was blinded to results of the other method. We evaluated 21,832 30-s epochs--1,092+/-111 (SD) per child. Across 20 subjects, 79.7+/-7.1% of the epochs were sleep. The simplified montage agreed with polysomnographic classification of sleep/wakefulness for 93.8+/-2.5% of the epochs. Of all sleep epochs, 97.7 (96.4, 98.1%) median (interquartile range), were correctly classified; sleep predictive value of the CRV method was 95.2+/-2.8%. Of all epochs classified as wakefulness by polysomnography, 80.1+/-12.8% were correctly classified by the CRV method. The wakeful predictive value was 88.7+/-2.6%. Kappa values averaged 0.8+/-0.1, indicating that agreement between the CRV method and polysomnography did not occur by chance and that the level of agreement was excellent. Thus, sleep can be distinguished from wakefulness in children being evaluated for OSA using a combination of cardiorespiratory and videotape recordings. These results suggest that the CRV method would be useful in a pediatric laboratory setting where EEG recordings are not always possible. They also suggest that overnight, unattended CRV recordings in a childs own home could correctly distinguish sleep from wakefulness.

Child↗
PubMed1996

Cardiorespiratory sleep studies for children can often be performed in the home.

We developed a portable recording system, suitable for unattended use in a patient's home, that quantitates the essential diagnostic elements of pediatric obstructive sleep apnea syndrome (OSAS): obstructive, mixed and central apneas and hyponeas; hemoglobin saturation, sleep vs. wakefulness; body and head positions; snoring: and sleep disturbance. The present paper reviews validation studies and summarizes two recent studies that demonstrate the unique advantages of performing clinical and research cardiorespiratory sleep studies in the child's home. Development of inexpensive, portable records that integrate audiovisual and physiologic information will make such home recordings more widely available.

Humans↗
PubMed1995

Home testing for pediatric obstructive sleep apnea syndrome secondary to adenotonsillar hypertrophy.

The objective of this study was to determine the accuracy and practicality of home testing for pediatric obstructive sleep apnea syndrome (OSAS) secondary to adenotonsillar hypertrophy. Twenty-one children aged 2-12 years and referred for possible OSAS were studied twice, once at home and once in the sleep laboratory. The home test consisted of two parts: 1) a cardiorespiratory recording of saturation (SaO2), pulse rate, pulse waveform, electrocardiogram, and respiratory inductive plethysmography; and 2) an 8-hour videotape recording of the sleeping child. In the laboratory, standard nocturnal polysomnography including electroencephalography was performed. Experiences with another 62 children who underwent home testing alone were also reviewed and are reported. At home, saturation, respiratory, and video data were obtained 96.4 +/- 13.3% (mean +/- SD) 99.4 +/- 1.6%, and 90.0 +/- 78% of the time, respectively. The sleep efficiency was greater at home than in the laboratory, 91.1 +/- 3.9% vs. 86.1 +/- 7.2%, with a mean difference of 5.0% (P < 0.01). The median environmentally induced movement/arousal index was lower in the home than in the laboratory, 0.0 (inter-quartile range, 0.0-0.3 vs. 2.4/hr (inter-quartile range 1.2-4.2), with a median difference of 2.4/h (P < 0.001). Study duration, apnea/hypopnea index, desaturation index, respiratory and spontaneous movement/arousal indices, and oxygen saturation during sleep were similar for home and laboratory studies. Although neither sleep state nor PCO2 (transcutaneous or end-tidal) was measured in the home, this information would have modified patient management in, at most, one case. In the second group of 62 children, exclusively studied at home, all studies were successfully recorded despite a wide range of sleep efficiencies, apnea/hypopnea indices, and desaturation indices. We conclude that home testing, using a simplified cardiorespiratory montage plus video recording, is accurate and of practical use in the routine evaluation of OSAS in patients with adenotonsillar hypertrophy.

Adenoids↗
PubMed1995

Use of nasal continuous positive airway pressure as treatment of childhood obstructive sleep apnea.

OBJECTIVE: To determine the safety and efficacy of nasal continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA) during childhood and the effects of growth and maturation on CPAP requirements. DESIGN: Retrospective study with use of a written questionnaire administered to pediatric practitioners treating sleep disorders. SETTING: Nine academic pediatric sleep disorders centers. RESULTS: Data were obtained for 94 patients. Three percent of patients receiving CPAP were less than 1 year, 29% were 1 to 5 years, 36% were 6 to 12 years, and 32% were 13 to 19 years of age; 64% were boys. The longest duration of CPAP use was 4 years. Indications for CPAP included OSA associated with obesity (27%), craniofacial anomalies (25%), idiopathic OSA persisting after adenoidectomy and tonsillectomy (17%), and trisomy 21 (13%). Continuous positive airway pressure was effective in 81 patients (86%), in one patient it was unsuccessful, and in 12 patients compliance was inadequate. The median pressure required was 8 cm H2O (range, 4 to 20 cm H2O); pressure requirements were independent of age or diagnosis. Twenty-two percent of patients eventually required a modification of CPAP levels. Complications of CPAP were minor. Sixty-four percent of centers reported difficulty in obtaining funding for CPAP. CONCLUSIONS: Continuous positive airway pressure is safe, effective, and well tolerated by children and adolescents with OSA. Experience in infants is limited. As pressure requirements change with patient growth, we recommend that CPAP requirements be regularly reevaluated over time. The marked center-to-center variability in CPAP use suggests that specific indications for this therapy require clarification.

Adolescent↗
PubMed1994

Diaphragm pacing: clinical and experimental results.

Over the last 26 years diaphragm pacing has been used in over 400 adults and 70 children to support ventilation and oxygenation. Diaphragm pacing can be useful for conditions in which the brain stem respiratory centers provide little or no stimulation to the respiratory muscles, i.e. central hypoventilation syndrome, Arnold-Chiari malformation/brain stem dysfunction, and high quadriplegia. Because the pacing systems are so portable, the greatest advantages accrue to those patients who require ventilatory support both while awake and asleep. Infants and children require tracheostomy to avoid upper airway obstruction and bilateral pacing to meet higher metabolic demands. The stimulus parameters most appropriate for pediatric patients have been characterized as low stimulus frequency, short inspiratory time, and moderate respiratory rate. Use of similar stimulus parameters in an immature animal model has resulted in preservation of diaphragmatic structure and function but transformation of the diaphragm from a mixed muscle to one with a uniform population of type 1, fatigue-resistant fibers (physiologic, histochemical, myosin isoform, and ultrastructural evidence). In 33 pediatric patients, representing 96 patient-years of use, there were 26 failures of the pacing systems requiring removal and/or replacement of the internal components. Mean time to failure was 56 months. Of our 36 patients who had diaphragm pacing systems implanted, 26 are alive and 22 are currently using the pacing systems. wo recent advances may further improve the long-term outcome of patients using diaphragm pacing. Smaller, better encapsulated receivers may improve system longevity and a new stimulus electrode may reduce the risk of diaphragmatic damage.

Adult↗
PubMed1994

Movement/arousals. Description, classification, and relationship to sleep apnea in children.

Movement/arousal has been described as a characteristic of adult obstructive sleep apnea syndrome (OSAS), but opinions differ as to whether or not OSAS in children increases the frequency of movement/arousal. The problem that we decided to address was the lack of a comprehensive definition and characterization of movement/arousals in children. We therefore quantified and classified movement/arousals during nocturnal polysomnography in 15 children 5.2 +/- 2.7 SD yr of age being evaluated for OSAS. Movement/arousals were defined by modifying the standard criteria for scoring arousals in adults. Median respiratory disturbance index was 4.4/h, with a range of 1 to 28/h. Videotape review was required to adequately distinguish technician-induced from spontaneous movement/arousals. Although movement/arousal durations varied from 1 s to prolonged awakenings, a high frequency of brief, 1- to 3-s movement/arousals occurred in all classification categories: respiratory, 44%; technician-induced, 33%; spontaneous, 36%. When comparing a 16-channel PSG montage with that of a seven-channel cardiorespiratory montage, we found that 84% of all movement/arousals could be detected using the abbreviated montage. In conclusion, we propose a simple classification system that distinguishes three types of movement/arousals: respiratory, technician-induced, and spontaneous. Our results further suggest that a simple montage using cardiorespiratory channels and videotaping would be suitable for home study and sensitive for identifying movement/arousals.

Analysis of Variance↗
PubMed1993

Transcutaneous and end-tidal carbon dioxide pressures should be measured during pediatric polysomnography.

Pediatric obstructive sleep apnea (OSAS) is characterized by partial airway obstruction, alveolar hypoventilation, and elevated arterial CO2 (PaCO2). Thus, a reliable, practical method of estimating CO2 is needed for pediatric polysomnography. Therefore, we measured both transcutaneous CO2 (PtcCO2) and end-tidal CO2 (PETCO2) in 15 pediatric polysomnographic evaluations. Sleep state, the highest PtcCO2, and the highest PETCO2 were recorded for 5,159 thirty-second epochs. Although PtcCO2 and PETCO2 were available for 78.5 and 73.0% of epochs, respectively, at least one estimator was available for 92% of the epochs. One infant who would not tolerate a nasal sampling catheter had no PETCO2 data. For 13 of 14 studies there was a relatively constant difference between PtcCO2 and PETCO2. The difference between PtcCO2 and PETCO2 was within 4 mm Hg in 63.9% of 3,072 epochs. Across 14 studies, mean PtcCO2 exceeded mean PETCO2 by 2.8 +/- 3.0 mm Hg, and it was within 4 mm Hg in 10 studies. In three subjects, PETCO2 was intermittently or consistently less than PtcCO2 because of tachypnea, increased physiologic dead space, or severe partial airway obstruction; in one subject PtcCO2 exceeded PETCO2 for undetermined reasons during one electrode application. The results of this study indicate that PtcCO2, as well as PETCO2, should be measured during pediatric polysomnography. By utilizing both PtcCO2 and PETCO2 there was a 70% reduction in the number of epochs that could not be assessed for hypoventilation. For an individual subject or electrode application there was a constant, and usually close, relationship, between PtcCO2 and PETCO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Monitoring, Transcutaneous↗
PubMed1992

Ultrasound screening of high-risk infants. A method to increase early detection of congenital dysplasia of the hip.

Congenital dysplasia of the hip (CDH) continues to be missed by routine physical screening examinations in the early months when treatment is most effective. Real-time ultrasonography (US) is valuable in the detection of CDH in the young infant. We performed a prospective study to evaluate one US screening strategy that targets a select "high-risk newborn" population at risk for CDH aiming to increase the early diagnosis of this condition. From 1772 consecutive births at one hospital, we identified 97 (5.5%) newborns with risk factors for CDH: breech delivery, 73 babies; family history, 26 babies; postural abnormalities, five babies; and oligohydramnios, four babies. Eleven newborns had two risk factors. We studied 69 of these newborns with US. There were four cases of CDH in this group. Three of these babies had completely normal pediatric physical examination results at the time of the US study (at 14, 75, and 100 days, respectively) despite dysplasia diagnosed by US. All were successfully treated with a harness as outpatients. We conclude that a screening program entailing identification and subsequent US of the hip of newborns with specific physical and historical risk factors for CDH increases early diagnosis. Further analysis suggests this approach is cost-effective.

Female↗
PubMed1990

Breathing control disorders in infants and children.

Pediatric breathing control disorders can be disastrous if not promptly recognized and treated. Diagnostic techniques and management options are discussed in the context of essential clinical features of five major entities: neonatal apnea, obstructive sleep apnea, central hypoventilation syndrome, "apparent life-threatening events," and sudden infant death syndrome.

Apnea↗
PubMed1990

Comparison of transthoracic impedance/heart rate monitoring and pulse oximetry for patients using diaphragm pacemakers.

Patients using diaphragm pacemakers have several respiratory-related problems placing them at high risk for death during sleep, including central hypoventilation, abnormal arousal responses, upper airway and/or tracheostomy obstruction, and, in the case of high quadriplegia, lack of motor response to airway obstruction. The recent death from airway obstruction of a patient using diaphragm pacemakers prompted us to re-evaluate both the need for home monitoring and the type of monitor to prescribe. We compared the performance of a transthoracic impedance/heart rate (TI/HR) monitor with that of a pulse oximeter in six patients with central hypoventilation syndrome whose treatment included diaphragm pacing. Polygraphic recordings of airflow, ECG, SaO2, transthoracic impedance, heart rate, and breath detection were obtained during brief tracheostomy occlusion during patient sleep. Although none of 13 occlusions was detected by the TI/HR monitor, the pulse oximeter identified 13 of 13 occlusions. Three reasons for TI/HR monitor failure included 1) the breath detection circuit consistently registered a breath with each obstructed, paced diaphragmatic contraction; 2) bradycardia did not occur during any airway occlusion; and 3) pacemaker stimuli were misinterpreted as additional heart beats, increasing apparent heart rate. Thus, pulse oximetry, but not TI/HR monitoring, can detect life-threatening airway obstruction in children using diaphragm pacemakers.

Adolescent↗
PubMed1990

Assessing clinical significance of apnea exceeding fifteen seconds with event recording.

Using event recording, we determined how often apnea exceeding 15 seconds in duration was associated with bradycardia and how often patients with apnea resumed breathing spontaneously. Of 1306 documented apnea events exceeding 15 seconds (54 patients), 926 lasted 16 to 20 seconds, 262 lasted 21 to 25 seconds, and 118 exceeded 25 seconds. Of these episodes, 75.3% were isolated and 14.9% were associated with pulse deceleration, 4.4% with irregular transthoracic impedance, and 5.4% with bradycardia. Event recording provided data supporting discontinuation of monitoring in 50 of 54 patients: 36 spontaneously resumed breathing before the auditory alarm and 14 had a decreased incidence of apnea with maturation. Follow-up of 51 patients (three not located) showed that none had subsequent apparent life-threatening events or sudden infant death syndrome. Our results in these older infants and children (median age 6.7 months) provide substantiation that such patients with apnea of less than 20 seconds without bradycardia do not require continued monitoring. Further, these data suggest that in selected older infants, longer isolated apnea may be well tolerated; however, hemoglobin saturation during sleep and the ability to resume breathing after the apnea alarm delay is prolonged should be verified. Our patient population had a wide age range and heterogeneity of diagnoses, and was typically free of symptoms, so these results should not be extrapolated uncritically to premature infants, infants with chronic lung disease, and patients with symptomatic apnea.

Age Factors↗
PubMed1990

Effects of continuous low-frequency pacing on immature canine diaphragm.

Although diaphragm pacing has been shown to be a practical method of supporting ventilation in children, its usefulness has been limited because of concern that continuous (24 h/day) diaphragm pacing would fatigue and damage the diaphragm. We examined the functional and structural effects of continuous low-frequency diaphragm pacing on the left hemidiaphragm of five immature dogs aged 65 +/- 2 (SD) days at onset of pacing. Stimulus parameters approximated those required to pace infants: frequency 11.1 Hz, inspiratory time 810 ms, and respiratory rate 20 breaths/min. Animals were paced 24 h/day for 24-28 days. Paced tidal volumes and airway occlusion pressures were unchanged at low (less than 15 Hz) stimulus frequencies but were reduced at high (greater than 20 Hz) stimulus frequencies. Although histologically the paced hemidiaphragms appeared normal, histochemical studies showed a conversion from a mixture of type I (54%) and type II (46%) fibers to a uniform population of type I fibers with high oxidative enzyme activity. Transformation of muscle type was also demonstrated by pyrophosphate gel electrophoresis; fast and slow isomyosin bands were noted in control specimens, whereas only slow isomyosin was identified in paced specimens. Thus, in immature dogs, continuous low-frequency pacing affects both function and structure of the diaphragm.

Action Potentials↗
PubMed1989

Favorable outcome of neonatal aortic thrombosis and renovascular hypertension.

Fifteen children with renovascular hypertension as a result of aortic thrombosis were followed for a mean of 26 months (range 5 to 58 months) to determine outcome. As neonates, all patients had hypertension and elevated plasma renin activity. Of 11 patients studied with radionuclide renography and scintigraphy, 10 had abnormal renal blood flow; three had complete absence of unilateral perfusion. On follow-up examination all children were normotensive; five children ages 5 to 24 months required antihypertensive medication. Of 15 children, 14 had normal statural growth; all had normal serum creatinine, plasma renin activity, and calculated glomerular filtration rate values. Patients with complete absence of renal perfusion unilaterally remained functionally anephric; children with less severe perfusion deficits had improved perfusion as shown by radionuclide renography and scintigraphy. We believe that many patients with aortic thrombosis and renovascular hypertension who have had aggressive antihypertensive therapy in the neonatal period will have good renal function and increased perfusion to the affected kidney 2 years later.

Aortic Diseases↗
PubMed1989

Assessing validity of infant monitor alarms with event recording.

We evaluated the performance of an event recorder system in a large, consecutive series of referred monitored patients to determine the relative incidence of true apnea and true bradycardia, false alarms, and alarms for movement or a loose lead. In addition, we developed an event classification system based on the reason for the event being recorded. The recorder stored transthoracic impedance and electrocardiogram signals on a floppy disk before, during, and after each monitor alarm. These events on 302 disks from 83 patients were analyzed and classified as true, false, or movement-loose lead. Of 14,131 events, only 8% were caused by apnea or bradycardia (true events). Of true events, 70% were triggered by apnea and 30% by bradycardia. These true events occurred in 48% of the patients. False alarms constituted 23%, and movement-loose lead 69%, of all events. Even when movement-loose lead events were excluded, nearly three of four events were found to be false. Event recording proved helpful clinically, allowing discontinuation of the monitor in 49% of patients, modification of monitor alarm settings, or reassurance and counseling for parents.

Apnea↗