Detection of compressed tracheal sound patterns with large amplitude variation during sleep

The objective of the present work was to develop automated methods for the compressed tracheal breathing sound analysis. Overnight tracheal breathing sound was recorded from ten apnoea patients. From each patient, three different types of tracheal sound deflection pattern, each of 10 min duration, were visually scored, viewing the compressed tracheal sound curve. Among them, high deflection patterns are of special interest due to the possible correlation with apnoea-hypopnoea sequences. Three methods were developed to detect patterns with high deflection, utilizing nonlinear filtering in local characterization of tracheal sounds. Method one comprises of local signal maximum, the second method of its local range, and the third of its relative range. The three methods provided 80% sensitivity with 57, 91 and 93% specificity, respectively. Method three provided an amplitude-independent approach. The nonlinear filtering based methods developed here offer effective means for analysing tracheal sounds of sleep-disordered breathing.

Prolonged spiking in the Emfit sensor in patients with sleep-disordered breathing is characterized by increase in transcutaneous carbon dioxide

A phenomenon of prolonged spiking in movement sensors, such as static-charge-sensitive bed or Emfit (electromechanical film) sensors, has been connected to an increase in carbon dioxide tension in wakefulness. Spiking is also a common finding in sleep studies. This made us hypothesize that carbon dioxide changes might also happen in sleep during prolonged spiking episodes in Emfit sheet. We examined four different kinds of breathing pattern episodes: normal breathing, episodes of repetitive apnea, episodes of repetitive hypopnea and episodes with prolonged spiking lasting at least 3 min. One hundred and fifteen episodes from 19 polysomnograms were finally admitted to the study according to the protocol. The changes in the transcutaneous carbon dioxide tension (TcCO(2)) were defined for different breathing patterns. During prolonged spiking episodes the TcCO(2) increased significantly and differed statistically from the TcCO(2) changes of normal breathing and periodic breathing patterns (episodes of apnea and hypopnea). The rise in TcCO(2) during prolonged spiking episodes might suggest that prolonged spiking is representing another type of breathing disturbance during sleep differing from periodic breathing patterns. The Emfit sensor as a small, flexible and non-invasive sensor might provide useful additional information about breathing during sleep.

Medroxyprogesterone in postmenopausal females with partial upper airway obstruction during sleep

The aim of the present study was to evaluate the degree and duration of respiratory stimulation caused by medroxyprogesterone acetate (MPA), and compare the effect of MPA to that of nasal continuous positive airway pressure (nCPAP) in sleep-disordered breathing. Ten postmenopausal females with predominantly partial upper airway obstruction during sleep had an overnight sleep study at baseline, on the fourteenth day of treatment with MPA and after a 3-week washout period. Six subjects on nCPAP were also studied 3 months later. At baseline, the overnight mean+/-SD end-tidal pressure of carbon dioxide (Pet,CO2) was 5.5+/-0.4 kPa the arterial oxygen saturation (Sa,O2) 93.0+/-1.2%, Sa,O2 nadir 80.0+/-6.7%, and frequency of oxygen desaturation > or = 4% (ODI4) per hour 2.2+/-1.3. MPA decreased Pet,CO2 by 0.8 kPa (14.5%, p<0.001). After washout, the mean Pet,CO2 remained at 0.5 kPa (9.1%, p<0.001) lower than at baseline. Sa,O2 did not change. Pet,CO2 was lower on MPA than on nCPAP (4.7+/-0.2 kPa versus 5.0+/-0.3 kPa; p=0.037) but Sa,O2 was similar. Apnoea/hypopnoea index tended to be lower on CPAP than on MPA. Medroxyprogesterone acetate at a daily dose of 60 mg improves ventilation in postmenopausal females with partial upper airway obstruction during sleep without compromising sleep. The ventilatory improvement is sustained for at least 3 weeks posttreatment. Medroxyprogesterone acetate was more efficient in decreasing the partial pressure of carbon dioxide but continuous positive airway pressure was superior in decreasing respiratory efforts.

Climacteric vasomotor symptoms do not predict nocturnal breathing abnormalities in postmenopausal women

OBJECTIVE

To study the association of climacteric vasomotor symptoms and nocturnal breathing abnormalities in a sample of healthy postmenopausal women.

METHODS

Out of 71 postmenopausal women who took part in a large sleep study, 65 women were included into the present study. Sleep was monitored with polysomnography and nocturnal breathing with a static-charge sensitive bed and a pulse oximeter. Climacteric vasomotor symptoms were scored daily for 14 days and levels of oestradiol and FSH were measured in the serum.

RESULTS

Altogether 21 (32.3%) women had some degree of breathing abnormalities during the study night. The occurrence of clinically significant sleep apnoea was low (1.5%) and of moderate type (OP-2). In contrast, increased respiratory resistance pattern, typical for partial upper airway obstruction, was frequent (16.9%). Seventy-eight per cent of the women had arterial oxyhaemoglobin desaturation events, but only in 4.6% of the women these events occurred more than 5 times/h of time in bed. Older women had more simple periodic breathing (P-1) and lower mean arterial oxyhaemoglobin saturation (SaO(2)). Body mass index (BMI) correlated with the apnoea frequency (OP-2) and inversely with the mean SaO(2). The severity of climacteric vasomotor symptoms or serum oestradiol concentration did not correlate with nocturnal breathing abnormalities.

CONCLUSIONS

Nocturnal breathing abnormalities, especially partial upper airway obstruction, are common in postmenopausal women, but climacteric vasomotor symptoms do not predict their occurrence or severity. Increasing age and high BMI are important determinants of nocturnal breathing abnormalities.

Estrogen replacement therapy and nocturnal periodic limb movements: a randomized controlled trial

OBJECTIVE

To evaluate the effect of estrogen replacement therapy on nocturnal periodic limb movements in a randomized, double-masked, placebo-controlled, crossover trial.

METHODS

Seventy-one healthy postmenopausal women volunteered in answer to a newspaper announcement; 62 women completed the follow-up. Frequency of nocturnal body movements was measured with the static-charge-sensitive bed and all-night polysomnographic recordings. Serum estradiol (E2) and FSH concentrations were also measured at baseline and after each treatment period. The power of the study setup was 94%.

RESULTS

Nearly half the women presented with episodes of periodic limb movements (30 of 62 women, or 48%, during placebo and 27, or 44%, during estrogen therapy). In 17 (27%) during placebo and 19 (31%) during estrogen therapy, frequency of periodic limb movements exceeded index level 5 per hour while subjects were in bed. Incidence or intensity of movements, movement durations, and movement intervals did not change with estrogen therapy. The arousal index was similar during the two treatments (medians = 1.7 for placebo and 1.3 for estrogen, P =.758). Variations in serum E2 concentration, age, and body mass index did not explain variations in movement activity.

CONCLUSION

Estrogen replacement therapy in doses used to control climacteric symptoms does not alter the incidence or intensity of nocturnal periodic limb movements.

Comparison of autonomic withdrawal in men with obstructive sleep apnea syndrome, systemic hypertension, and neither condition

Obstructive sleep apnea syndrome is characterized by obesity, nocturnal breathing abnormalities, arterial hypertension, and an increased number of cardiovascular events. Sympathetic activity is increased during nocturnal apneic episodes, which may mediate the cardiovascular complications of sleep apnea. We studied 15 male subjects with obstructive sleep apnea syndrome and associated hypertension, 54 subjects with mild to moderate essential hypertension, and 25 healthy normotensive men. Cardiovascular autonomic control was assessed using frequency domain measures of heart rate variability (HRV) during a controlled breathing test and during orthostatic maneuver. Compared with normotensive and hypertensive groups, total power and low- and high-frequency components of HRV during controlled breathing were significantly (analysis of variance, p<0.0001) lower in the obstructive sleep apnea syndrome. During the orthostatic maneuver, the change in total power of HRV was different between the 3 groups (analysis of variance, p = 0.004). The total power of HRV tended to increase in the normotensive (4.11+/-12.29 ms2) and in hypertensive (2.31+/-12.65 ms2) groups, but decreased (1.13+/-1.23 ms2) in the hypertensive group with obstructive sleep apnea syndrome. According to multivariate regression analysis, age and sleep apnea were the major independent determinants of HRV. This study found that an abnormal response to autonomic nervous tests characterizes hypertension in overweight subjects with obstructive sleep apnea syndrome. This could be due to autonomic withdrawal or supersaturation of the end-organ receptors by excessive and prolonged sympathetic stimulation. Our results also show the reduced response of orthostatic maneuver and controlled breathing in the hypertensive group compared with the normotensive group.

Distributed clinical neurophysiology

We have developed a consultation forum for clinical neurophysiology in Finland. The system connects local digital electroencephalography (EEG) recording and analysing networks using a high-speed asynchronous transfer mode (ATM) network. Clinicians can obtain a second opinion using interactive data and video consultations or using data-only consultations. In addition, the system can be used for off-line review of pre-recorded data. During a one-month evaluation, 66 EEG recordings were made altogether in Satakunta Central Hospital and consultations were required on 12 occasions. Nine of them were data-only consultations and three were data and video consultations. A data consultation lasted 15-20 min and a data and video consultation 35-45 min. Clinically, there were numerous benefits for the hospitals. The system established a link to a centre of excellence for second opinions or continuing education. It also helped with on-duty arrangements and enabled the construction of national data banks.

Detection of periodic leg movements with a static-charge-sensitive bed

We evaluated the performance of the static-charge-sensitive bed (SCSB), a non-invasive movement sensor, in detecting nocturnal periodic movement activity using simultaneous bilateral anterior tibialis electromyography (EMGat) as a reference. Two different study setups were used, one with 500 random record extracts, another with 10 continuous recordings. The inter-rater reliability between two independent scorers was 0.92 in scoring EMGat and 0.91 in scoring SCSB. In an epoch based analysis, depending on the study setup and scorer, the sensitivity of the SCSB to detect periodic leg movements was 0.81-0.94 whereas the specificity was 0.84-0.89. In a movement-by-movement analysis, despite incomplete concordance between the two methods the total number of movements per hour were comparable. Our findings support the use of the SCSB as a non-invasive alternative to anterior tibialis EMG recordings to reveal the presence of nocturnal periodic movement activity and estimate its frequency.

Sleep-related disorders in carpal tunnel syndrome

INTRODUCTION

Patients with carpal tunnel syndrome (CTS) often wake up at night due to pain and numbness of affected fingers and hand. We studied the sleep disorder caused by CTS.

SUBJECTS AND METHODS

34 consecutive patients referred for operative treatment of CTS answered to a sleep questionnaire and the results were compared to a stratified random sample of 1600 Finns aged 36-50 year, whose response rate to the mailed questionnaires was 75.2% (n = 1186). Six CTS patients underwent a polygraphic sleep study before and after operative treatment of CTS.

RESULTS

CTS patients reported suffering from poor sleep quality, fragmentary sleep and daytime sleepiness more often than controls. Before operative treatment of CTS there were more nocturnal body movements (p < 0.01) and awakenings lasted longer (p < 0.05) than after operation. During preoperative sleep studies no drop in median nerve conduction was detected during awakenings.

CONCLUSIONS

Patients with CTS suffer from fragmentary sleep. Although patients reported waking up for the pain or numbness of hands no impairment in median and ulnar nerve conduction could be observed during these awakenings. Operative treatment of hand entrapment significantly reduced the number of nocturnal movements.

Automatic SCSB analysis of motor and autonomic nervous functions compared with sleep stages

All-night recordings of respiration, ballistocardiogram, and body movements were obtained using the static charge-sensitive bed (SCSB) and automatically analysed data were compared with sleep stages. The mean sum of eight SCSB variability parameters was lowest in slow wave sleep (SWS), higher during stage 2 (S2), and highest in REM sleep. The sum scores of the parameters with the highest correlations with the EEG data were classified into quiet (QS), intermediate (IS) and active (AS) states. SCSB signals during wakefulness, stage 1 and REM sleep were mostly scored as AS, whereas in S2 and especially in SWS they were scored as QS or IS. The SCSB is an easy and inexpensive tool for conducting follow-up studies on sleep quality in natural environments.

Nocturnal breathing abnormalities in acromegaly after adenomectomy

OBJECTIVE

The incidence of sleep apnoea is increased in acromegaly. The aim of the study was to determine the occurrence of nocturnal breathing abnormalities and upper airway morphology in acromegalic patients some years after adenomectomy.

DESIGN

A case-control study.

PATIENTS

Eleven patients with treated acromegaly and two control groups: (1) sleep studies: 197 subjects randomly selected from the population, (2) cephalometry: 27 healthy subjects and 17 patients with obstructive sleep apnoea.

MEASUREMENTS

Nocturnal breathing was monitored with a static charge-sensitive bed. The upper airway soft tissues and bone morphology were assessed by cephalometric X-ray photography. The upper airway collapsibility was investigated with dynamic nasopharyngoscopy. Endocrinological investigations were also performed.

RESULTS

Nocturnal breathing abnormalities were present in all but one acromegalic patient (91%), which was far more frequent than in the general population (29.4%, P < 0.0001). Treated acromegaly was the most powerful predictor of breathing abnormalities, independent of the other significant predictors, age and body mass index. The predominant breathing abnormality was periodic breathing with symmetrically waxing and waning respiratory effort without a major body movement component. Episodes of complete obstruction with repetitive arousals were rare. Except for the longer soft palate, the cephalometric findings were similar to normal. In comparison to obstructive sleep apnoea, the treated acromegalic patients had rather prognathic than retrognathic mandibles. Fibreoptic endoscopy in the acromegalic patients revealed collapsible upper airways at the level of the soft palate, whereas at the base of the tongue little, if any, dynamic narrowing was observed.

CONCLUSION

Our study confirms that nocturnal breathing abnormalities are common in treated acromegaly, and may persist years after the removal of the GH secreting tumour. The breathing abnormalities and the upper airway morphology in acromegalic patients after adenomectomy are different from those observed in primary obstructive sleep apnoea, suggesting a different pathophysiology of the airway obstruction.

Upper airway obstruction in hypothyroidism

OBJECTIVES

To determine the occurrence and frequency of nocturnal upper airway obstruction in hypothyroidism.

DESIGN

A case-control study of patients with newly diagnosed hypothyreosis and euthyroid subjects who had been selected from the population register. The subjects underwent sleep recordings with a static-charge-sensitive bed (SCSB).

SETTING

Turku University Hospital and Research and Development Unit, Social Insurance Institution, Turku, Finland.

SUBJECTS

Twenty six consecutive patients underwent sleep recordings with SCSB and a pulse oximeter. One hundred and eighty-eight euthyroid subjects who were previously studied with the SCSB were used as controls.

MAIN OUTCOME MEASURES

In a multivariate analysis, hypothyroidism, gender, age, and body mass index (BMI) were considered as predictors for the occurrence of nocturnal breathing abnormalities.

RESULTS

Nocturnal breathing abnormalities were frequent in both groups. Fifty per cent of the hypothyroid patients and 29.3% of the control subjects had at least some episodes of partial or complete upper airway obstruction (P = 0.04). Severe obstruction with episodes of repetitive apnoea was present in 7.7% of the patients and in 1.5% of the controls. The multivariate analysis revealed that the presence of hypothyroidism did not significantly (P = 0.06), and independently of age, BMI or gender, predict nocturnal breathing abnormalities, whereas obesity (P < 0.0001) and male gender (P = 0.0001) were independent and significant predictors.

CONCLUSIONS

The incidence of nocturnal upper airway obstruction is increased in hypothyroidism, but is related to obesity and male gender rather than to hypothyroidism per se.

Relaxation training combined with increased physical activity lowers the psychophysiological activation in community-home boys

Resting electrical activity (EMG) in the frontalis, temporalis, trapezius and erector trunci muscles, as well as systolic and diastolic blood pressure (BP), were measured in boys in a community home, and in controls of the same age in an ordinary school. EMG in the community-home boys was significantly higher than in controls, whereas BP did not yield any difference. The community-home boys participated in a programme consisting of relaxation training and increased physical activity for 4 months. After this intervention, EMG in all muscle groups was decreased, and the level of EMG was also lower than the values measured in controls. Systolic and diastolic BP in the community-home boys was also lowered, but the decrease was not significant as compared to the control group. In conclusion, relaxation training and/or increased physical activity is effective in decreasing the elevated activation observed in community-home boys.

Orthostatic tolerance and aerobic capacity

The responses of heart rate and blood pressure to passive head-up tilting were assessed twice with an interval of 2 months in 100 healthy, middle-aged men. Then the subjects were randomly allocated into training or non-training groups. The intervention period of 4 months was successfully completed by 85 subjects. Mean, indirectly-determined oxygen uptake capacity increased in the training group only. The amplitude of the change in heart rate from supine to tilting and back again was used as the sign of orthostatic tolerance (OT). OT was similar in the training and non-training groups. When the subjects were grouped according to aerobic fitness, no differences in the OT could be observed. Changes in fitness during the intervention did not induce any changes in orthostatic tolerance. When the whole group was divided according to the OT or change in OT, no significant differences of changes in aerobic fitness were observed. It is concluded that in healthy, ambulatory, middle-aged men orthostatic tolerance and aerobic fitness are not correlated.

Fully rectified, integrated, band (FRIB-) EMG analysis in quantifying muscle activity. Development of a new field equipment

A new approach for the study of muscular activity applicable in field and laboratory conditions has been developed. The instrument is portable (375 g) and battery operated. The signals are obtained through a surface electrode attached to the skin above the muscle. A reference electrode is applied to a bony area close by. The third electrode, to remove 50 Hz disturbance, is attached at a distance from the muscle to be registered. A time domain band EMG signal is fully rectified and integrated. The isolation of the device is done with an optocoupler. The EMG activity to be thus registered is not hampered by other external or internal (ECG) electrical signals. The recordings can also be made when the person is working quite freely. The recorded values correlate linearly (up to r = 0.99) with the load of the muscle. The angular coefficients obtained with different loads correlate inversely with the strength of the persons. When muscle fatigue develops during a static loading, the registered EMG tends to decrease while simultaneously oscillating. During the recovery from the fatigued state the response to intermittent loadings indicates that the electrical activity pattern varies with time. With the method developed it is possible to detect locally increased electrical activity at rest or during muscle function testing, and it permits the followup of therapeutic measures.

Interseason Training and Aerobic Fitness of Motocross Racers

In brief: The excellent endurance capacities of ten members of the Finnish motocross team, studied before and after a three-month program stressing endurance and strength, showed further improvement with intense training. Before the program they had 12.2% body fat and maximal oxygen consumption of 64.7 ml· kg(-1)· min(-1) during bicycle ergometry. After the program, fat decreased 7.7%, weight decreased insignificantly, VO2 max increased 12.4%, and anaerobic thresholds (AT) increased 21%, averaging 37.3 ml· kg(-1)· min(-1) (56.1% of VO(2) max). Heart rates at the AT increased 11.7%. Most physiological variables improved more at the AT than at maximum.