Flow limitation and dynamic hyperinflation.
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Humans↗
Biomedical subjects
M Kerkhofs
Publications and source records attributed to M Kerkhofs.
Operating characteristics of the negative expiratory pressure technique in predicting obstructive sleep apnoea syndrome in snoring patients.
BACKGROUND: This study examines the operating characteristics of the expiratory flow response to a negative pressure (NEP) applied to the mouth in the prediction of obstructive sleep apnoea syndrome (OSAS) in snoring patients. METHODS: Two hundred and thirty eight patients with normal spirometric values were studied. Full laboratory polysomnography was performed and an NEP of -5 cm H(2)O was applied in the sitting and supine positions. RESULTS: A significant correlation was found between the degree of flow limitation measured by NEP in both positions (expressed as the percentage of the expired tidal volume over which NEP induced flow did not exceed spontaneous flow) and the apnoea-hypopnoea index (AHI). This correlation was significantly higher in the supine position (p<0.0001) where an expiratory flow limitation cut off value of >/=27.5% of the tidal volume produced a sensitivity of 81.9% and a specificity of 69.1% in predicting OSAS. CONCLUSION: These findings show that the degree of instability of the upper airway measured by NEP is correlated with the severity of OSAS. NEP had moderate sensitivity and specificity and may be useful in predicting OSAS in a clinic based population.
Adult↗
[Frederic Bremer (1892-1982): a pioneer in sleep research].
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Animals↗
High leg motor activity in sleep apnea hypopnea patients: efficacy of clonazepam combined with nasal CPAP on polysomnographic variables.
The association of sleep apnea hypopnea syndrome (SAHS) with high leg activity in the same patient is a dilemma for the physician, as clonazepam, used to treat periodic leg movement syndrome (PLMS) can aggravate apneas, while nasal continuous positive airway pressure (nCPAP) can exacerbate PLMS. The present study aimed to compare nCPAP alone (n), nCPAP combined with clonazepam (n+c) and clonazepam alone (c) in patients with mild to moderate SAHS associated with high leg activity. Fourteen patients with an apnea hypopnea index (AHI) between 10 and 50 h(-1) and a leg movement index with regard to time in bed [LMI (TIB)] > 15 h(-1) on baseline polysomnography (b) were recorded on three consecutive nights with n, n+c and c, respectively. Leg movements were detected, using actigraphy, and were subsequently categorized into periodic, apnea- or hypopnea-related and nonperiodic movements (defined as neither periodic nor related to a respiratory event). The three treatments were successful in improving breathing [AHI b 26.1 (3.2) n 11.8 (2.4) n+c 5.0 (0.7) c 14.9 (1.8) h(-1)], leg activity [LMI (TIB) b 391 (4.8) n 22.5 (4.4) n+c 23.9 (3.9) c 22.6 (3.7) h(-1)] and sleep fragmentation [stage shift index b 373 (2.6) n 28.6 (1.6) n+c 25.6 (1.8) c 26.6 (1.6) h(-1)]. All types of movements were reduced, the effect being significant for respiratory events related and nonperiodic movements. Combination therapy was more effective than nCPAP alone in reducing the AHI and in improving sleep efficiency. We conclude that in patients with mild to moderate SASH associated with high leg activity, nCPAP improves nocturnal breathing and clonazepam reduces leg activity. More unexpectedly nCPAP is beneficial on leg activity and clonazepam on breathing, probably through a decrease in sleep fragmentation. The best results are obtained with combination therapy.
Analysis of Variance↗
The SleepStrip: an apnoea screener for the early detection of sleep apnoea syndrome.
Sleep apnoea svndrome (SAS) is a largely undiagnosed and prevalent disorder. It is associated with cardiovascular morbidity as well as excessive daytime sleepiness and poor quality of life. In the present study the SleepStrip, a novel screening device is introduced, which is low cost and easy to use and is aimed for widespread use. The results of three independent validation studies, which compared the SleepStrip score (Sscore) against "gold standard" polysomnographically-determined apnoea/ hypopnoea index (AHI), are reported both separately and combined. Four hundred and two patients suspected of SAS underwent full polysomnography recordings concomitantly with the use of the SleepStrip. For all samples combined, the correlation between AHI and Sscore was r=0.73, sensitivity and specificity values ranged from 80-86% and 57-86% respectively, and the area under the curve derived from receiver-operating characteristic curves ranged from 0.81-0.92 at varying AHI thresholds. Though not intended as a substitute for polysomnography, the SleepStrip may provide initial screening information, which may be useful in both clinical and experimental settings.
Adolescent↗
Compliance with nasal continuous positive airway pressure assessed with a pressure monitor: pattern of use and influence of sleep habits.
The aim of the study was to assess compliance with nasal continuous positive airway pressure (N-CPAP) at home in patients with obstructive sleep apnoea syndrome (OSAS) and to search for predictors of compliance. We studied a cohort of 106 consecutive patients (91 men, 15 women) with a median apnoea hypopnoea index of 62.4 (range 21-132) h(-1), equipped at home with a Rem+ Soft device (Sefam, France), including a pressure monitor and a real-time clock. During the third and fourth months of treatment, the patients used their machine a median of 88% of days (16-100%), with a mean effective use of 5.6 (1.3-11.2) h per effective day. Residual apnoea index on N-CPAP, as recorded by the monitor, was 1.5 (0.3-27.6) h(-1). Mean clock-time for starting with N-CPAP was 23 h 54 min (21 h 34-01 h 42). The mean effective use per effective day correlated negatively with the minimal (and the mean) level of oxyhaemoglobin saturation (r(s) = -0.24, P < 0.05) while the percentage of days the machine was used correlated negatively with the percentage of slow wave sleep (r(s) = -0.22, P < 0.05) at baseline polysomnography. In a subset of 30 subjects, earlier start on N-CPAP correlated with longer use of the device in 22 patients (median r--0.48). We conclude that a pressure monitor allows reporting on compliance in terms of regularity (% of days the machine is used) and length of sleep on N-CPAP (effective use per effective day). These compliance variables show modest correlations with baseline polysomnographic features. Late bedtime should be discouraged as it might decrease compliance.
Bias↗
Frédéric Bremer 1892-1982: a pioneer in sleep research.
Frédéric Bremer was one of the pioneer neurophysiologists who dedicated their career to understanding the neural mechanisms involved in the control of sleep-wake regulation. This paper follows his career and his major achievements. We found that Bremer's interest in sleep resulted from his unexpected observations after transecting the brain at the midcollicular level in the "encéphale isolé" preparation. The sleep-like behaviour of the animal, accompanied by slow waves in the cortex, convinced him that sleep resulted from cortical deafferentation. He was further convinced that deafferentation was the cause of sleep when he found that transecting the brain at the medullary level did not much affect the sleep-wake cycle. As we show, Bremer's views that sleep is a passive phenomenon imposed on the brain because of deafferentation was shared by most of his contemporaries. Years later Bremer admitted that he interpreted his experimental findings wrongly. He continued to investigate sleep using his preparations and made important contributions to understanding the relationships between the brainstem reticular formation and the basal forebrain hypnogenic centres, as well as the importance of light on these relationships.
Journal Article↗
Genetic control of 24-hour growth hormone secretion in man: a twin study.
The aim of this study was to delineate the contributions of genetic and environmental factors in the regulation of the 24-h GH secretion. The 24-h profile of plasma GH was obtained at 15-min intervals in 10 pairs of monozygotic and 9 pairs of dizygotic normal male twins, aged 16-34 yr. Sleep was polygraphically monitored. Significant pulses of GH secretion were identified using a modification of the computer algorithm ULTRA. For each significant pulse, the amount of GH secreted was calculated by deconvolution. A procedure specially developed for twin studies was used to partition the variance of investigated parameters into genetic and environmental contributions. A major genetic effect was evidenced on GH secretion during wakefulness (with a heritability estimate of 0.74) and, to a lesser extent, on the 24-h GH secretion. Significant genetic influences were also identified for slow wave sleep and height. These data demonstrate that human GH secretion in young adulthood is markedly dependent on genetic factors.
Adolescent↗
Shortened REM latency as a psychobiological marker for psychotic depression? An age-, gender-, and polarity-controlled study.
BACKGROUND: Previous reports suggest that the clinical dichotomy separating psychotic and nonpsychotic depression corresponds to different neurobiological profiles. The aim of the present study is to further investigate the psychobiological correlates of these two particular depressive subtypes. METHODS: Thyroid-stimulating hormone response to thyrotropin-releasing hormone postdexamethasone cortisol levels, and electroencephalgraphic sleep characteristics of 44 psychotic major depressive patients were compared to those of 44 nonpsychotic depressives matched for age, gender, and polarity. RESULTS: Some biological disturbances usually associated with depression (increased wakefulness, diminished rapid eye movement latency, hypercortisolism, blunted thyroid-stimulating hormone response to thyrotropin-releasing hormone stimulation) seemed to be significantly more pronounced in the psychotic depressed group as a reflection of greater illness severity; however, shortened REM latency was not influenced by severity and seemed to be more specifically related to the co-occurrence of psychotic and depressive symptoms. CONCLUSIONS: Our data provide further support for the validity of the clinical dichotomy separating psychotic and nonpsychotic major depression independently of severity.
Age Factors↗
The dexamethasone suppression test and sleep electroencephalogram in nonbipolar major depressed inpatients: a multivariate analysis.
BACKGROUND: The present study further examined relationships between postdexamethasone cortisol plasma values and sleep electroencephalogram (EEG) parameters. METHODS: The dexamethasone suppression test (DST) and polysomnographic recordings were performed in a sample of 300 inpatients with primary major depressive disorder (MDD) (102 men and 198 women, mean age 44 +/- 12 years, range 20-74 years) consecutively admitted to Erasme Hospital (Brussels, Belgium) between 1981 and 1992. RESULTS: The DST was abnormal in 40% of the sample. Postdexamethasone cortisol plasma values at 4:00 PM were significantly influenced by age, but not by gender. They were also significantly and positively correlated with weight loss, total scores on the Hamilton Depression Rating Scale, total scores on the Newcastle Scale, percentage of awakenings during sleep, and percent of stage 1. They were significantly and negatively correlated with percent of stage 2, slow-wave sleep, and REM sleep. Multiple regression analyses were conducted in two successive steps. First among clinical variables, only age and depressive symptom severity remained correlated with postdexamethasone plasma cortisol values. In the second step, with age and severity held constant, postdexamethasone plasma cortisol values were positively associated with amount of wake time and stage 1, and negatively with amount of slow-wave sleep. CONCLUSIONS: These findings provide further indirect support for an overarousal state in MDD with sympathoadrenal system hyperactivity and impaired sleep continuity. They also underline the importance of taking into account various clinical confounding factors in the interpretation of both DST and sleep EEG results.
Adult↗
Does sleep EEG data distinguish between UP, BPI or BPII major depressions? An age and gender controlled study.
Clinical characteristics and sleep EEG data of 14 unipolar (UPR), 14 bipolar I (BPI) and 14 bipolar II (BPII) patients, matched for age and gender, were investigated during a major depressive episode. We observed a remarkable similarity in the clinical characteristics of the three samples and, concerning sleep EEG data, a trend to a higher percentage of awakening among BPI patients. Pairwise comparisons of the three subgroups showed that only the Newcastle rating scale score reached significant difference between BPI and UPR groups. We observed trends regarding the difference of awakening both between BPI and BPII groups and between BPI and UPR groups, difference of percentage of REM sleep between BPI and BPII groups and difference of Sleep Period Time between BPII and UPR groups. We also observed that the distribution of REM latencies in the BPI subgroup was different from the two others.
Adult↗
Evidence against a role for the growth hormone-releasing peptide axis in human slow-wave sleep regulation.
A complex interrelationship exists between sleep and somatotropic activity. In humans, intravenous injections of growth hormone-releasing hormone (GHRH) given during sleep consistently stimulate slow-wave (SW) sleep, particularly when given in the latter part of the night. In the present study, the possible somnogenic effects induced under similar conditions by GH-releasing peptide (GHRP) were investigated in seven young healthy men. Bolus intravenous injections of GHRP-2 (1 microgram/kg body wt) or saline, in randomized order, were given after 60 s of the third rapid-eye-movement period. All GHRP injections were immediately followed by transient prolactin elevations and by GH pulses of a magnitude within or around the upper limit of the physiological range. Except for a nonsignificant tendency to increased amounts of wakefulness during the 1st h after the injection, no effects of GHRP-2 administration on sleep were detected. There was in particular no enhancement of SW sleep. Thus, in contrast to GHRH, late-night single injections of GHRP-2 at a dosage resulting in similar GH elevations have no stimulatory effects on SW sleep. The present data provide evidence against the involvement of the GHRP axis in human SW sleep regulation.
Adult↗
Genetic and environmental influences on prolactin secretion during wake and during sleep.
To delineate the contributions of genetic and environmental factors in the regulation of human prolactin (PRL) secretion, the 24-h profile of plasma PRL was obtained at 15-min intervals in 10 pairs of monozygotic and 10 pairs of dizygotic twins. Sleep was monitored polygraphically. PRL secretory rates were derived from plasma concentrations by deconvolution. Diurnal (24-h) variations were quantified by a regression curve to define nadir, acrophase, and amplitude. Pulses of PRL secretion were identified using a computerized algorithm. A procedure specifically developed for twin studies was used to partition the variance into genetic and environmental contributions. Significant genetic effects were identified for daytime PRL concentrations, rhythm amplitude, and overall wave-shape of the daily PRL profile. In contrast, environmental effects were dominant for mean concentrations during sleep, total secretory output during sleep, overall 24-h concentrations, and total 24-h secretion. However, when interindividual variations in sleep fragmentation were taken into account, the estimates of genetic variance for PRL concentrations and secretion during sleep approached statistical significance. Significant genetic influences were identified for slow-wave sleep (SWS). Because SWS is associated with increased nocturnal PRL secretion, it is possible that genetic effects on PRL secretion during sleep reflect genetic influences on SWS. In conclusion, genetic factors determine partially both the basal daytime concentrations of PRL and the temporal organization of PRL secretion over the 24-h cycle in normal young men.
Adult↗
EEG sleep in non-affective psychiatric disorders.
Several sleep complaints and disturbances have been documented in psychiatric disorders. These modifications of sleep in anxiety disorders, alcoholism, schizophrenia, dementia and eating disorders are reviewed and discussed. At the present time, there is no evidence for any specific sleep pattern in non-affective psychiatric disorders. The co-morbidity of sleep disorders like sleep apnoea, periodic leg movements and parasomnia in psychiatric illness is not very well known at the present time.
Journal Article↗
[Sleep apnea and nocturnal ventilatory assistance (nCPAP): 5-year experience in the conventional system].
The reimbursement of nasal continuous positive airway pressure (nCPAP) by the Belgian social security, via a conventional system, has made since 1991 this treatment available to an increasing number of patients having moderate to severe sleep apnoea hypopnoea syndrome (SAHS). We have reviewed our experience in prescribing domiciliary nCPAP from 1991 to 1995. Three hundred twenty-five subjects with SAHS, predominantly male (89%) and/or obese (77%) subjects, have benefited. Mean use of nCPAP machine, assessed by reading the time counter, amounted 4.7 h per 24 h, with only 23% of non-compliant patients (use < 3 h per 24 h). In 205 patients nCPAP was effective in controlling SAHS-related symptoms. Cure, with successful weaning from nCPAP, was obtained in 16 patients, as a result of marked weight loss in 13 of them. Forty-six non-compliant subjects were not allowed by the physician to go on, and 40 subjects left nCPAP because of intolerance. Finally, 10 patients abandoned nCPAP because of inefficacy, ascribed to some associated condition, being predominant, and 8 patients died. Our results suggest that domiciliary nCPAP is an effective treatment for SAHS in a majority of subjects, but that this kind of treatment is prescribed lifelong, unless there is a marked weight loss. The Belgian conventional system, as it requires a regular follow-up, contributes to keep non-compliance within acceptable limits.
Adult↗
Sleep EEG analysis by linear prediction: frequency changes of slow-wave activity within NREM and REM sleep episodes in healthy men.
The linear prediction method was applied to obtain a power spectra estimate of sleep EEG in 10 healthy young men. In order to analyze frequency changes of the slow-wave activity (EEG power in the delta band, 0.05-2.88 Hz), the delta mean frequency was computed for each 20-second sleep epoch. A mean delta mean frequency was calculated for each sleep stage in each individual. Our observations indicate that the delta mean frequency decreases during NREM periods and increases mainly at the onset of the REM episodes. This finding, in parallel with the detailed analysis of slow-wave power variations, leads to an additional description of sleep characteristics during transitions between the NREM-REM sleep episodes.
Adult↗
Sleep apnea after 1 year domiciliary nasal-continuous positive airway pressure and attempted weight reduction. Potential for weaning from continuous positive airway pressure.
STUDY OBJECTIVE: To assess the effect of 1 year of therapy for sleep apnea syndrome (SAS) combining domiciliary nasal-continuous positive airway pressure (N-CPAP) and attempted weight loss on the severity of disease and to evaluate the potential for weaning from continuous positive airway pressure (CPAP). METHODS AND PROCEDURES: Ninety-five patients having a baseline apnea hypopnea index (AHI) greater than 10/h were prescribed N-CPAP at home. Weight loss was attempted by dietary counseling and by single ring vertical gastroplasty in those patients with a body mass index (BMI) greater than 40 kg/m2. Subjects were asked to return after 1 year for a full-night polysomnography (PSG) without CPAP and the results were compared with baseline PSG. RESULTS: Thirty-nine patients compliant to CPAP were evaluated. Weight had decreased from 108.3 +/- 29.0 to 99.7 +/- 17.7 kg as a result of dietary counseling (n = 36) or gastroplasty (n = 3). A significant improvement was found in AHI (66.5 +/- 28.7-->50.3 +/- 38.4/h; p < 0.05), maximal duration of apnea or hypopnea (66 +/- 22-->47 +/- 18 s; p < 0.001), minimal oxyhemoglobin saturation (62 +/- 16-->78 +/- 7%; p < 0.001), and stage shift index (SSI) (76 +/- 29-->62 +/- 28/h; p < 0.05). The drop in AHI correlated with the reduction in BMI (r = 0.47; p < 0.01) and with the decrease in SSI (r = 0.50; p < 0.001). Weaning from CPAP was proposed to six patients and succeeded in four (three with 29, 93, and 94 kg weight loss, respectively, and one subject with a normal unchanged weight). CONCLUSION: In 39 patients with SAS, 1-year domiciliary N-CPAP combined with weight loss resulted in a significant improvement in breathing during sleep and in sleep fragmentation, as judged from PSG without CPAP. Four subjects were successfully weaned, three of whom had in parallel a substantial decrease in weight.
Body Mass Index↗
Relationship between the Newcastle scale and sleep polysomnographic variables in major depression: a controlled study.
In order to investigate the reliability of the endogenous concept of depressive illness with some sleep EEG parameters, we studied 39 male inpatients suffering from a nonbipolar major depressive episode (15 endogenous (MDDE) and 24 nonendogenous (MDDNE)) and 20 age and sex matched normal controls (C). All patients were diagnosed according to the Research Diagnostic Criteria (RDC) and the endogenous character of the episode was assessed with the Newcastle Endogenous Depression Diagnostic Index. We found significant differences for the following variables between the three groups (MDDE, MDDNE and C): sleep period time (SPT), REM latency, stage II, slow wave sleep (SWS), REM latency expressed as a continuous variable and REM latency expressed as a dichotomizing variable with a threshold of 50 min. These variables were used to compare the endogenous and the nonendogenous depressed patients and also the major depressed patients and the normal controls. Significant differences were observed between all depressed patients and control subjects for amount of SWS and REM latency which were both reduced in endogenous and nonendogenous depressed patients. No significant difference was observed between endogenous and nonendogenous depressed patients, except for the REM latency expressed with a threshold of 50 min (more frequently observed in endogenous depressed patients). Our data support the observation that SWS and REM latency are decreased in major depressive patients. However, in this age and sex controlled study, subtyping nonbipolar major depressive disorder for an endogenous character by the Newcastle Endogenous Depression Diagnostic Index (NEDDI) did not reveal further significant differences for sleep EEG variables, except for the shortening of the REM latency expressed as a dichotomizing variable.
Adult↗