Systemic hypertension in sleep apnea syndrome. Relationship with sleep architecture and breathing abnormalities.

To examine the possible relationship between systemic HT and SAS we compared 21 hypertensive (HT+) and 29 normotensive (HT-) patients for morphologic characteristics, sleep disturbances and respiratory events monitored during a full night polysomnography. There was no significant difference between HT+ and HT- patients with respect to age, weight, BMI, sleep stage distribution and disorganization, apnea-hypopnea index (number of episodes per hour of sleep) and duration (minutes per hour of sleep) nor O2 saturation indices: mean nocturnal and minimum O2 saturation. We conclude therefore that HT in SAS patients is not directly related to morphologic characteristics, sleep disturbances and breathing abnormalities.

Abdominal muscle activity during CO2 rebreathing in sleeping neonates.

Comparison of the abdominal muscle response to CO2 rebreathing in rapid-eye-movement (REM) and non-REM (NREM) sleep was performed in healthy premature infants near full term. Eight subjects were studied at a postconceptional age of 40 +/- 1.6 (SD) wk (range 38-43 wk) during spontaneous sleep. Sleep stages were defined on the basis of electrophysiological and behavioral criteria, and diaphragmatic and abdominal muscle electromyographic activity was recorded by cutaneous electrodes. The responses to CO2 were measured by a modified Read rebreathing technique. The minute ventilation and diaphragmatic and abdominal muscle electromyographic activities were calculated and plotted against end-tidal CO2 partial pressure. Both the ventilatory and diaphragmatic muscle responses to CO2 decreased from NREM to REM sleep (P less than 0.05). Abdominal muscles were forcefully recruited in response to CO2 rebreathing during NREM sleep. In REM sleep, abdominal muscle response to CO2 was virtually absent or decreased compared with NREM sleep (P less than 0.05). We conclude that 1) the abdominal muscles are recruited during NREM sleep in response to CO2 rebreathing in healthy premature infants near full term and 2) the abdominal muscle recruitment is inhibited during REM sleep compared with NREM sleep, and this REM sleep-related inhibition probably contributes to the decrease in the ventilatory response to CO2 rebreathing in REM sleep.

Non-invasive measurement of haemodynamics during sleep apnoea.

Sleep apnoeas are accompanied by large variations in heart rate (HR) and blood pressure (BP). This nocturnal variability in BP may be involved in the increased cardiovascular morbidity of these patients. Due to the complex interaction between asphyxia, intrathoracic pressure, cardiac function and autonomic activation, the exact haemodynamic mechanisms are unclear. To evaluate the components of the BP surges at resumption of breathing (RB) a non-invasive beat-to-beat measurement was taken of cardiac output (CO) by the pulse contour analysis of the Finapres signal. Six male normotensive patients, free of medication (37-60 y, BMI 26.5-43.0 kg m-2) were studied during polysomnography (apnoea index: 22-69 h-1). Systolic blood pressure rose from 126.5 +/- 1.3 mmHg at beginning apnoea (P1) to 140.4 +/- 1.3 at RB (P < 0.01, ANOVA). During sleep Stages 2 and 3, stroke volume decreased during RB to 96% of P1 value (NS). Due to an opposite change in HR, CO tended to rise at RB to 106% of P1. Computed total peripheral resistance rose during RB to 105% of P1 value (P < 0.011. Therefore, it is concluded that the surge in BP at RB after apnoea is due to concomitant increases in CO and in TPR. Both rises are presumably a consequence of sympathetic nervous activation by the arterial chemoreceptors.

[Intraventricular hemorrhage and parenchymatous ischemia in the newborn at term. Report of five cases]. / Hémorragie intraventriculaire et ischémie parenchymateuse chez le nouveau-né à terme à propos de cinq cas.

Although intraventricular hemorrhage associated with cerebral ischemia without severe perinatal asphyxia is rare in full-term newborns, it can be severe, have early or late onset depending on the etiology and be of poor prognosis. Five full-term neonates (37 to 41 weeks of gestational age) without criteria of severe perinatal asphyxia were admitted to the intensive care unit for seizures: four were between seven and 11 days of age and one was only 12 h old. Clinical or electroclinical seizures recorded by continuous EEG monitoring were numerous, leading to status epilepticus in three babies. They were unilateral (at the level of the left hemisphere) in one infant and have not been recorded in the fourth case. Past-ictal EEG abnormalities were numerous rolandic or temporal slow or fast sharp waves of variable polarity. Cranial CT scans showed uni- or bilateral intraventricular hemorrhage with dilatation and subcortical or periventricular ischemic lesions with hemorrhage. Four out of the five infants died during the neonatal period.

[[Emergency pediatric EEG in mental confusion, behavioral disorders and vigilance disorders: a retrospective study]. / L'EEG d'urgence en pédiatrie dans les troubles de la vigilance, la confusion mentale et les troubles du comportement: étude rétrospective.

Recording of electroencephalogram (EEG) is of value to estimate vigilance states in children as in adults. In order to determine the diagnostic and prognostic value of emergency EEG in case of mental confusion, behavioral disorders and vigilance disorders in childhood, we conducted a retrospective study in 397 children (aged 2 months to 16 years). EEG was recorded less than 24 hours after an emergency consultation for acute confusion or acute behavioral disorder (n = 106) or after admission to the intensive care unit for comatose stage (n = 291). EEG gave diagnostic indications mainly in case of convulsive pathology or hepatic encephalopathy. In comatose children, we established a 4-stage EEG scale of increasing severity. This classification was compared to EEG scales already published in the literature and appeared very similar to that from Pampiglione and Harden, established in 150 children after cardiac arrest. A highly poor prognostic value was associated with burst-suppression post-anoxic patterns and with isoelectric records signaling brain death. Our classification of emergency EEG patterns is mainly helpful in these two situations, but does not exclude strict and repeated clinical and EEG follow-up in other cases, as a relatively preserved initial EEG may later deteriorate.

[Nocturnal continuous measurement of blood pressure in sleep apnea syndromes. Comparison between normotensive and hypertensive patients]. / Mesure continue nocturne de la pression artérielle au cours du syndrome d'apnées du sommeil. Comparaison entre sujets normotendus et sujets hypertendus.

Sleep apnea syndrome and systemic hypertension are frequently associated but their causal relationship is unclear. We compared the oscillations of systemic blood pressure and heart rate during polysomnography in 8 normotensive subjects (2 females) and 5 hypertensive (supine awake blood pressure: 165 +/- 7/96 +/- 5 mmHg) without treatment. Their ages (normotensive: 52.1 +/- 11.0 yrs, hypertensive: 51.2 +/- 6.4 yrs) and body mass indices (32.6 +/- 9.6 kg/m2 vs 33.2 +/- 5.2 kg/m2 respectively) were not statistically different. Systemic blood pressure was continuously monitored by a non invasive digital plethysmography (Finapres). Both groups had similar respiratory events indices (normotensive: 45.2 +/- 18.1/hr, hypertensive: 48.4 +/- 20.5/hr) and minimal oxygen saturations (79.4 +/- 9.1% vs 82.4 +/- 7.0% respectively). During apneas in slow-wave sleep were observed the minimal values for systolic and diastolic pressures which were significantly higher in hypertensive than in normotensive (138.2 +/- 9.6/83.2 +/- 16.1 mmHg vs 105.9 +/- 11.1/60.5 +/- 10.9 mmHg respectively). During resumption of ventilation maximal blood values were recorded which were also higher in hypertensive than in normotensive (185.0 +/- 13.8/113.2 +/- 21.5 mmHg vs 155.9 +/- 19.8/88.7 +/- 17.1 mmHg respectively) (p less than 0.05). Although absolute variations of blood pressure were similar, relative changes in systolic pressure were significantly higher in normotensive (p less than 0.05). Maximal heart rate was 76.8 +/- 6.2 bpm in normotensive and 76.6 +/- 3.9 bpm in hypertensive during resumption of ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Obstructive sleep apnea syndrome and heart failure]. / Syndrome d'apnées obstructives du sommeil et insuffisance cardiaque.

Heart failure has an increasing prevalence in middle age adults. The prognosis is very poor even with improved medical therapy and heart transplants. The outcome is related to the neurohumoral disease resulting from heart failure which leads to sympathetic activation that in turns worsens the prognosis. About half of the patients have sleep breathing disorders with variable proportions of central and obstructive apneas. Obstructive apneas are acutely deleterious to ventricular function. On the long run, they may be responsible for a worsening of the disease due to the permanent sympathetic activation seen in obstructive sleep apnea. It is therefore important to detect sleep apnea in patients and to apply a treatment. The best therapeutic procedure in obstructive events appears to be CPAP, provided hemodynamic status is closely monitored.

[Indications of electroencephalogram in the newborn]. / Indications de l'électroencéphalogramme en période néonatale. Recommandations du groupe de neurophysiologie clinique de l'enfant.

The electroencephalogram (EEG), an easy-to-use and non invasive cerebral investigation, is a useful tool for diagnosis and early prognosis in newborn babies. In newborn full term babies manifesting abnormal clinical signs, EEG can point focal lesions or specific aetiology. EEG background activity and sleep organization have a high prognostic value. Tracings recorded over long period can detect seizures, with or without clinical manifestations, and differentiate them from paroxysmal non epileptic movements. The EEG should therefore be recorded at the beginning of the first symptoms, and if possible before any seizure treatment. When used as a neonatal prognostic tool, EEG background activity is classified as normal, abnormal (type A and type B discontinuous and hyperactive rapid tracing) or highly abnormal (inactive, paroxysmal, low voltage plus theta tracing). In such cases, the initial recording must be made between 12 and 48 h after birth, and then between 4 and 8 days of life. Severe EEG abnormalities before 12 h of life have no reliable prognostic value but may help in the choice of early neuroprotective treatment of acute cerebral hypoxia-ischemia. During presumed hypoxic-ischemic encephalopathy, unusual EEG patterns may indicate another diagnosis. In premature newborn babies (29-32 w GA) with neurological abnormalities, EEG use is the same as in term newborns. Without any neurological abnormal sign, EEG requirements depend on GA and the mother's or child's risk factors. Before 28 w GA, when looking for positive rolandic sharp waves (PRSW), EEG records are to be acquired systematically at D2-D3, D7-D8, 31-32 and 36 w GA. It is well known that numerous and persistent PRSW are related to periventricular leukomalacia (PVL) and indicate a bad prognosis. In babies born after 32 GA with clinically severe symptoms, an EEG should be performed before D7. Background activity, organization and maturation of the tracing are valuable diagnosis and prognosis indicators. These recommendations are designed (1) to get a maximum of precise informations from a limited number of tracings and (2) to standardize practices and thus facilitate comparisons and multicenter studies.

[Heart failure and sleep respiratory disorders. Prevalence, physiopathology and treatment]. / Insuffisance cardiaque et troubles respiratoires du sommeil. Prévalence, physiopathologie et traitement.

Cheyne-Stokes respiration occurs during sleep in 40-45% of patients with NYHA class III and IV heart failure. Such patients experience repeated episodes of progressively diminishing ventilation associated with desaturation followed by periods of increasing-amplitude ventilation. The mechanism appears to be related to hyperventilation leading to hypocapnia which occurs near a critical threshold of apnea during sleep stages I and stage II and interrupts central ventilatory control. The total duration of the periodic respiration cycle would depend on the increased circulation time subsequent to lowered cardiac output. Brief periods of waking provoked by Cheyne-Stokes respiration, accentuating sympathetic nervous system activity, are an unfavorable prognostic factor in heart failure. Activation of the sympathetic system may be corrected by CPAP although the long-term effect on heart failure remains controversial. Other treatments, such as oxygen therapy or theophylline, combined with optimized treatment of heart failure, have been proposed.

[Sleep-related cardiac insufficiency and respiratory disorders. Prevalence, physiopathology, and treatment]. / Insuffisance cardiaque et troubles respiratoires du sommeil. Prévalence, physiopathologie et traitement.

Cheyne-Stokes respiration occurs during sleep in 40-45% of patients with NYHA class III and IV heart failure. Such patients experience repeated episodes of progressively diminishing ventilation associated with desaturation followed by periods of increasing-amplitude ventilation. The mechanism appears to be related to hyperventilation leading to hypocapnia which occurs near a critical threshold of apnea during sleep stages I and stage II and interrupts central ventilatory control. The total duration of the periodic respiration cycle would depend on the increased circulation time subsequent to lowered cardiac output. Brief periods of waking provoked by Cheyne-Stokes respiration, accentuating sympathetic nervous system activity, are an unfavorable prognostic factor in heart failure. Activation of the sympathetic system may be corrected by CPAP although the long-term effect on heart failure remains controversial. Other treatments, such as oxygen therapy or theophylline, combined with optimized treatment of heart failure, have been proposed.

Needs and costs of sleep monitoring.

Sleep disorders have a high prevalence in the general population: insomnia (10-20% of adults), sleep apnoea syndromes (4-6%). They are responsible for high costs of investigations and treatment modalities. The investigations are usually done in sleep laboratories at the expense of cost in personnel and long waiting lists. Remote monitoring could be an alternative to sleep laboratory studies. The first aim was to determine the need for sleep remote recording in sleep medicine in Europe, to improve health delivery and to reduce investigation costs. An enquiry was sent to 500 sleep medicine providers in Europe. Response rate was 11%. Analysis showed that the main diagnosis is obstructive sleep apnoea in adults. Currently 2/3 of sleep studies are performed in laboratory: In-lab studies: Average cost for the health care is 390 EURO/study. The range is from 700 in Finland and Germany and 180 in Greece, Belgium and Sweden are around the mean. Ambulatory studies with EEG: Average cost is around 120 EURO/study i.e. 30% of in-lab cost. The range is from 180 EURO in Portugal to 70 EURO in Germany. 50% of users are not satisfied with their current practice of ambulatory monitoring although they have a clear need for this technique to increase monitoring capacity (88%), reduce cost of investigation (85%), improve sleep quality (60%), and obtain better acceptance from the patient (76%). The expectations from ambulatory monitoring are: high diagnostic sensitivity (86%) high reliability of equipment (92%) low interference with patient's habits (94%) It is worth noting that 74% of users do not expect a fully automated interpretation of data. The indications cited are screening and follow-up of SAS, epilepsy, Periodic Leg Movements and also insomnia and narcolepsy. As a second aim, a validation study has been set-up for an ambulatory recorder. The reproducibility of the system has been evaluated in 14 patients by 2 consecutive home recordings and was satisfactory in terms of total sleep time and apnoea-hypopnea index. Nevertheless a failure rate of 7% was observed which should be improved by a better ergonomy of the system. The third aim was a socio-economical analysis in Paris, in order to define the actual standard mean cost of a polysomnography in the lab (500 EURO) and in ambulatory (238 EURO) i.e. less than one half of the laboratory cost. The monography of the health care process for sleep medicine in Paris showed a delay of more than 10 years for diagnosis of SAS in 25% of the patients and up to 5 physicians visited before referral to the sleep lab. In 48% of the cases the primary physician visited is a GP. In conclusion, there is a clear need for ambulatory monitoring of sleep disorders to decrease the burden of cost and long waiting lists which is not well satisfied with the current health care system and commercially available equipment.

Autonomic control of the cardiovascular system during sleep in normal subjects.

The autonomic control of heart rate and blood pressure during sleep is controversial: although it has been reported that vagal activity is more often lower in rapid eye movement sleep (REM) than in other stages of sleep (non-REM, NREM), the opposite has also been described. Initially, it was reported that baroreflex sensitivity (BRS) increases during sleep (REM and NREM), but in later studies, this was only partially confirmed. We therefore studied autonomic control of the cardiovascular (CV) system during sleep in 12 normal adults. The spectral components of the heart rate R-R interval, blood pressure (BP), and BRS were computed at low (LF) and actual breathing frequency (high frequency, HF). Analysis of sleep stage and a cycle-by-cycle stage II analysis were performed. CV variability is affected largely by sleep-stage and sleep-cycle organisation: NREM and the last cycle exhibit the greatest vagal activity and the lowest sympathetic activity. BRS estimation for both the LF and HF bands confirmed previous results obtained by pharmacological and spontaneous slope methods: BRS is greater during sleep than during nocturnal wake periods, and further increased in REM. BRS is frequency dependent: in NREM, the higher value of HF BRS compared to LF BRS favours the HF control of BP variability, whereas higher BRS HF and LF components contribute to the strongest control in REM. BRS variability exhibits no significant pattern during the night. Our results suggest that both sleep-cycle organisation and BRS estimation in the LF and HF bands should be considered in sleep studies of autonomic CV control.

Sleep-related abdominal muscle behavior during partial or complete obstructed breathing in prepubertal children.

We have evaluated the influence of nonrapid eye movement (NREM), REM sleep, and arousal on abdominal muscle contractions during snoring and/or obstructive apnea in 10 prepubertal children. All children were known habitual snorers and eight had a sleep apnea index above 10. During stage 3-4 non-REM sleep, non-apneic breathing with snoring was always associated with the presence of expiratory abdominal muscle electromyogram (EMG) discharges. During non-REM sleep apneas, abdominal muscle EMG discharges increased from the beginning to the end of each apnea. Termination of non-REM sleep apnea was marked by an "EEG arousal" in 12% of the apneic events and by a "movement arousal" in the other 88%. The highest abdominal muscle EMG discharge was always observed during the arousal response. During "phasic" REM sleep, abdominal muscle EMG discharges were absent during both nonapneic breathing (with or without snoring) and obstructive apneas. All REM sleep apneas ended with a "movement arousal," during which abdominal muscle EMG discharges were observed. Thus, abdominal muscle EMG discharges associated with "arousal" were seen independent of the immediately preceding sleep state.

The early diagnosis of periventricular leukomalacia in premature infants with positive rolandic sharp waves on serial electroencephalography.

OBJECTIVE: The objective of this study was to determine the specificity and the sensitivity of electroencephalography's positive rolandic sharp waves (PRSW) for the diagnosis of cystic and noncystic periventricular leukomalacia (PVL). METHODS: A retrospective study was performed on a population of 765 premature infants alive after 5 days who were divided into two groups; 166 infants born before 28 weeks (group 1) and 599 born between 28 and 32 completed weeks' gestation (group 2). Each infants underwent repeated ultrasound scanning and electroencephalography recordings during the first weeks of life. Magnetic resonance imaging was performed in infants with persisting hyperechoic periventricular densities on ultrasonography. RESULTS: A total of 83 (10.8%) newborns had PVL; 65 (8.5%) had cystic PVL PRSW, observed in 55 (7.2%) infants, always preceded the ultrasonic detection of cysts. PRSW were very specific markers of PVL in both groups (100% in group 1, 99.8% in group 2). PRSW sensitivity was found dependent on gestational age: 32.4% in group 1 in contrast to 87.8% in group 2. CONCLUSION: PRSW are an early and very specific marker of PVL in premature infants.