Biomedical subjects

O Polo

Publications and source records attributed to O Polo.

At least 19 recordsLinked to original sources

PubMed1999

Classification of nasal inspiratory flow shapes by attributed finite automata.

In a significant proportion of individuals, the physiologic decrease of muscle tone during sleep results in increased collapsibility of the upper respiratory airway. At peak inspiratory flow, the pharyngeal soft tissues may collapse and cause airflow limitation or even complete occlusion of the upper airway (sleep apnea). While there are plenty of methods to detect sleep apnea, only a few can be used to monitor flow limitation in sleeping individuals. Nasal prongs connected to pressure sensor provide information of the nasal airflow over time. This paper documents a method to automatically classify each nasal inspiratory pressure profile into one without flow limitation or six flow-limited ones. The recognition of the sample signals consists of three phases: preprocessing, primitive extraction, and word parsing phases. In the last one, a sequence of signal primitives is treated as a word and we test its membership in the attribute grammars constructed to the signal categories. The method gave in practical tests surprisingly high performance. Classifying 94;pc of the inspiratory profiles in agreement with the visual judgment of an expert physician, the performance of the method was considered good enough to warrant further testing in well-defined patient populations to determine the pressure profile distributions of different subject classes.

Algorithms↗

PubMed1999

Effect of short-term transdermal estrogen replacement therapy on sleep: a randomized, double-blind crossover trial in postmenopausal women.

OBJECTIVE: To evaluate the effect of estrogen replacement therapy on sleep architecture, arousals, and body movements. DESIGN: A 7-month, prospective, randomized, double-blind, placebo-controlled crossover trial. SETTING: Departments of obstetrics and gynecology and a university sleep center in Turku, Finland. PATIENT(S): Seventy-one postmenopausal women, 4 of whom were excluded and 5 of whom withdrew from the study; the final study group consisted of 62 women. INTERVENTION(S): Two periods of treatment with either estrogen or placebo. MAIN OUTCOME MEASURE(S): Polysomnography for measurement of sleep and arousals and a static charge-sensitive bed for monitoring of movements and breathing. Self-reports of climacteric symptoms for 14 days. RESULT(S): Estrogen effectively alleviated hot flashes, sweating, sleep complaints, and headaches. Estrogen decreased the total frequency of movement arousals but increased alpha-arousals, especially during light non-rapid eye movement sleep (stage 1). Sleep latency, distribution of sleep stages, sleep efficiency, and total sleep time were similar during treatment with estrogen and placebo. Changes in serum E2 concentrations correlated with neither subjective nor objective sleep quality. CONCLUSION(S): Estrogen replacement therapy improves objective sleep quality by alleviating the frequency of nocturnal movement arousals. It also reduces climacteric symptoms, especially vasomotor symptoms. Estrogen replacement therapy does not seem to have any effect on sleep architecture.

Aged↗

PubMed1998

When does estrogen replacement therapy improve sleep quality?

OBJECTIVE: Our purpose was to evaluate the effect of estrogen replacement therapy on sleep complaints by postmenopausal women and to assess the predictive factors involved. STUDY DESIGN: Sixty-three postmenopausal women entered a 7-month prospective, randomized, double-blind, crossover study consisting of two 3-month treatments with estrogen and placebo with a 1-month washout period between. Eight Visual Analogic Scale statements about different sleep complaints, the Basic Nordic Sleep Questionnaire, scoring of climacteric symptoms, The Beck Depression Inventory, and serum estradiol and follicle-stimulating hormone level controls were the main outcome measures. RESULTS: Estrogen replacement therapy improved sleep quality, facilitated falling asleep, and decreased nocturnal restlessness and awakenings (p < 0.001). The subjects were less tired in the mornings and in the daytime (p < 0.001) when taking estrogen replacement therapy. Estrogen-induced sleep improvement was associated with alleviation of vasomotor symptoms (r range 0.27 to 0.55), alleviation of somatic symptoms (palpitations and muscular pain, r range 0.26 to 0.36), and alleviation of mood symptoms (r range 0.28 to 0.37) on estrogen replacement therapy. The severity of initial insomnia predicted only one estrogen-induced sleep improvement effect: the more the subjects experienced insomnia, the better the estrogen replacement therapy facilitated falling asleep (r = 0.26, p = 0.040). Estrogen-induced sleep improvement was also reported by the 15 climacterically asymptomatic subjects. In these subjects initial insomnia scores strongly predicted estrogen-induced sleep improvement (r range 0.50 to 0.75). CONCLUSIONS: Estrogen replacement therapy significantly diminished sleep complaints among postmenopausal women. Alleviation of climacteric symptoms was the most important predictive factor for the beneficial effect of estrogen replacement therapy on sleep complaints. The use of estrogen replacement therapy in women without self-reported climacteric symptoms could also be considered because women do not always recognize their climacteric symptoms or they ignore them.

Climacteric↗

PubMed1998

The effect of short-term estrogen replacement therapy on cognition: a randomized, double-blind, cross-over trial in postmenopausal women.

OBJECTIVE: To evaluate the effect of estrogen replacement therapy on cognitive functioning. METHODS: The study consisted of two 3-month treatment periods, one with estrogen and one with the placebo, in random order, separated by a 1-month wash-out period. The study group comprised 70 healthy postmenopausal women, aged 47-65 years, with previous hysterectomy. Sixty-two women completed the study. Cognitive speed and accuracy, attention, and memory were evaluated. Serum estradiol (E2) and FSH levels were controlled at the end of the estrogen, placebo, and wash-out periods. RESULTS: Most of the cognitive tests correlated with age: older women were slower and made more errors than younger women. Estrogen replacement therapy was not superior to the placebo in any test of cognitive performance. In two out of ten visual detection tasks, recognition thresholds were longer with estrogen than with the placebo (P < .001 and P = .004). On the most demanding test of working memory, the reaction times (P = .045) and error rates (P = .043) differed between treatments, yet this finding proved to be an effect of learning rather than treatment. There was no correlation between cognitive performance and serum E2 levels. CONCLUSION: Cognitive performance decreased with age. Short-term estrogen replacement therapy did not provide any advantage over the placebo in terms of improving the performance.

Aged↗

PubMed1998

Nocturnal body movements and hypoxemia in middle-aged females after lower abdominal surgery under general anesthesia: a study with the static-charge-sensitive bed (SCSB).

OBJECTIVE: The aim of this study was to evaluate the feasibility of the static-charge-sensitive-bed (SCSB) combined with pulse oximetry (SpO2) for postoperative monitoring and to determine variables which could be used for evaluating the quality of postoperative sleep and breathing. METHODS: The frequency of body movements and the perioperative breathing abnormalities were assessed using the SCSB and pulse oximeter in 15 female ASA-class I-II patients undergoing elective lower abdominal surgery under general anesthesia. Anesthesia and control of postoperative pain followed standard practice. The patients were monitored during one preoperative and three consecutive postoperative nights. Movements were analyzed according to their duration and time interval. The effect of opioids was evaluated by measuring arterial oxyhemoglobin saturation (SpO2) with pulse oximetry for one hour before and two hours after administration of standard doses of oxycodone. RESULTS: The total movement time per hour increased during the first postoperative night (p = 0.003). Conversely, periodic movement activity decreased significantly during the three postoperative nights (p = 0.05, p < 0.001, p = 0.007). The mean SpO2 decreased during the first postoperative night (95.5% vs. 94.2%, p = 0.002), but returned to the preoperative level during the following nights. No episodes of apnea with significant oxygen desaturation (a decrease in SpO2 > 5%) were observed. Opioid administration was associated with decreased mean SpO2 (94.8% vs. 93.6%, p = 0.02), but did not lead to clinically significant hypoxemia (lowest observed SpO2 89.8%). CONCLUSIONS: Postoperative periodic movement activity was suppressed, but sleep remained fragmented with frequent body movements. In our middle-aged non-obese females (ASA I-II), no severe postoperative hypoxemia was observed during the three-nights postoperative survey. Perioperative movement monitoring with the SCSB was a valuable tool in rejecting movement artefacts of SpO2 and in evaluating general sleep quality.

Abdomen↗

PubMed1997

Climacteric symptoms do not impair cognitive performances in postmenopause.

OBJECTIVE: To investigate whether information processing and attention performances are affected by climacteric vasomotor symptoms. METHODS: The study group comprised 66 healthy hysterectomized postmenopausal women. The subjects were divided into two subgroups (high symptomatic and low symptomatic) according to the quantity of climacteric vasomotor symptoms. Information processing was examined using CogniSpeed, a reaction time software that separates, for example, pure controlled processing and working memory from perceptual and motor components. Attention was examined by using visual and auditory tasks. The role of climacteric depression as a determinant of cognitive performance was evaluated by the Beck Depression Inventory and dividing subjects according to self-reported climacteric mood symptoms. The effects of serum oestrogen level and ageing on cognitive performances were also studied. RESULTS: Cognitive performances were similar in high symptomatic and low symptomatic women. On the Verification test younger women had shorter reaction times (P = 0.002) and on the Subtraction test they had fewer errors (P = 0.015) than older women. These tests required working memory and decision making. Accuracy in the tests of sustained and auditory attention worsened slightly with age. Cognitive performances neither correlated with scores on the Beck Depression scale nor with serum oestrogen level. Climacteric mood symptoms did not impair cognitive performance. CONCLUSIONS: Despite subjective complaints of memory impairment in association with climacteric vasomotor symptoms, our results did not support a direct cause-and-effect relationship. Thus, the minor deficits found in cognitive processing efficiency seem to be related rather to age than climacteric symptoms.

Aging↗

PubMed1997

Digital fluoroscopy before and after laser uvulopalatopharyngoplasty in obstructive sleep apnea. Importance of pharyngeal collapsibility and hyoid bone position.

PURPOSE: To study the changes in pharyngeal behavior after laser uvulopalatopharyhgoplasty (LUPPP). MATERIAL AND METHODS: The dynamic changes in the upper airway size were evaluated with digital fluoroscopy in 24 patients with obstructive sleep apnea (OSA) before and after LUPPP and in 16 normal controls, while they were awake and breathing normally. Cephalometric measurements were also made. The patients were classified into the categories of good and poor responders by means of a static-charge-sensitive bed. RESULTS: Following LUPPP, collapsibility at the velopharyngeal level was within the normal range m 15 of 17 good responders, but only in 2 of 7 poor responders (p = 0.0086). The minimum airway size at the same level showed a similar trend. In 3 of 7 poor responders the hyoid bone was positioned more caudally than in the good responders (p = 0.017). CONCLUSION: Digital fluoroscopy provides information on the change in upper airway behavior after LUPPP.

Adult↗

PubMed1997

The effect of laser-uvulopalatopharyngoplasty on the nasal and nasopharyngeal volume measured with acoustic rhinometry.

Nasal breathing is considered as an important factor in sleep apnea and snoring, and nasal obstruction can lead to an increased respiratory resistance and to inflammatory reactions in the nasal mucosa. Uvulopalatopharyngoplasty is an effective treatment for sleep apnea and snoring. Different operation techniques with minor variations have been introduced during the last few years. Uvulopalatopharyngoplasty with laser technique (LUPPP) has made it possible to perform the operation in local anesthesia. Acoustic rhinometry is a new method for the evaluation of the nasal cavities and the nasopharynx. We measured the volume of nasal cavities and nasopharynx of 29 patients using acoustic rhinometry before and 6 months after the LUPPP operation. There was a tendency to a better nasal patency in the turbinate area, but no change was found in the nasopharyngeal volume. Acoustic rhinometry is a useful tool for measuring the turbinate area, and this part of the nasal cavities seems to be influenced by the LUPPP operation, maybe due to a better ventilation or reduction of the inflammation of the nose. However, technical and methodological improvements are needed before reliable measurements are achieved from the nasopharynx area.

Acoustics↗

PubMed1996

Sleep in multiple pregnancy: breathing patterns, oxygenation, and periodic leg movements.

OBJECTIVES: Our goal was to study whether multiple pregnancy at the third trimester predisposes to breathing disturbances and arterial oxyhemoglobin desaturation during sleep. STUDY DESIGN: Nocturnal breathing, oxygenation, and movement activity were studied in 10 mothers: 8 with twins, 1 with triplets, and 1 with quadruplets. RESULTS: No obstructive and few central sleep apnea episodes were observed. Four subjects had episodes of increased respiratory resistance, but only one, the mother with quadruplets, was significantly affected. Arterial oxyhemoglobin saturation was always maintained above 90%. Periodic leg movements were present in all mothers, with a frequency range of 3.7 to 49.7 movements per hour. CONCLUSIONS: In spite of the large uterus in multiple pregnancy, nocturnal breathing and oxygenation are well maintained. Increased motor activity and frequent awakenings suggest poor sleep quality, which may be further compromised by intensive periodic leg movements.

Adult↗

PubMed1996

Respiratory and body movements as indicators of sleep stage and wakefulness in infants and young children.

Conventional polysomnographic (PSG) sleep staging to sleep staging based on a static-charge-sensitive bed (SCSB) recording in infants and young children was compared. The study consisted of whole-night clinical sleep studies in 22 children at 24 weeks (SD 24, range 1-79 weeks) of age. Most of the children presented with respiratory disturbances during sleep. From the SCSB record, sleep stages were differentiated according to regularity of breathing, presence of body movements, and most important, presence of high-frequency components of breathing (SCSB spikes). With both methods, three sleep/wake stages were distinguished: rapid eye movement (REM) sleep, non-rapid eye movement (NREM) sleep and wakefulness. The average interscorer reliability of the PSG sleep staging controlled in nine subjects was 88%. The average concordance between the two methods ranged from 82 to 85%, depending on the criteria used for scoring the SCSB. The mean sensitivity of the SCSB to detect NREM sleep ranged from 77 to 90% and the mean sensitivity to detect REM sleep ranged from 61 to 86%. The mean positive predictive value was 89-96% for NREM sleep and 54-67% for REM sleep. In conclusion, REM sleep is characterized by irregular breathing with superimposed fast respiratory movements. These changes are specific enough to allow distinction between episodes of NREM sleep, REM sleep and wakefulness with the non-invasive SCSB method in infants and young children. Incomplete concordance between PSG and SCSB score was most frequently observed during sleep stage transition periods, where the behavioural state and electrophysiological criteria disagreed. When combined with the PSG, the SCSB provides complementary information about the behavioural state of child.

Electroencephalography↗

PubMed1996

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.

Adult↗

PubMed1996

Effect of different levels of hyperoxia on breathing in healthy subjects.

We have recently shown that breathing 50% O2 markedly stimulates ventilation in healthy subjects if end-tidal PCO2 (PETCO2) is maintained. The aim of this study was to investigate a possible dose-dependent stimulation of ventilation by O2 and to examine possible mechanisms of hyperoxic hyperventilation. In eight normal subjects ventilation was measured while they were breathing 30 and 75% O2 for 30 min, with PETCO2 being held constant. Acute hypercapnic ventilatory responses were also tested in these subjects. The 75% O2 experiment was repeated without controlling PETCO2 in 14 subjects, and in 6 subjects arterial blood gases were taken at baseline and at the end of the hyperoxia period. Minute ventilation (VI) increased by 21 and 115% with 30 and 75% isocapnic hyperoxia, respectively. The 75% O2 without any control on PETCO2 led to 16% increase in VI, but PETCO2 decreased by 3.6 Torr (9%). There was a linear correlation (r = 0.83) between the hypercapnic and the hyperoxic ventilatory response. In conclusion, isocapnic hyperoxia stimulates ventilation in a dose-dependent way, with VI more than doubling after 30 min of 75% O2. If isocapnia is not maintained, hyperventilation is attenuated by a decrease in arterial PCO2. There is a correlation between hyperoxic and hypercapnic ventilatory responses. On the basis of data from the literature, we concluded that the Haldane effect seems to be the major cause of hyperventilation during both isocapnic and poikilocapnic hyperoxia.

Adult↗

PubMed1996

Upper airway size and collapsibility in snorers: evaluation with digital fluoroscopy.

This study addressed the question of whether there are any differences in the size and collapsibility of the upper airway measured by digital fluoroscopy, between snorers and controls whilst they were awake and breathing normally; and whether there are any correlations between these measurements and other clinical data. The dynamic changes of the upper airway size were evaluated using digital fluoroscopy in 33 patients and 16 normal controls. The measurements were compared with findings in an overnight sleep study, including a static-charge-sensitive bed (SCSB) and oximeter recordings. The minimum anteroposterior dimension at the velopharyngeal level was smaller in patients with partial upper airway obstruction than in controls (p<0.005); patients with complete obstruction did not differ from the controls. The velopharyngeal airways were also more collapsible in patients with severe partial obstruction (p<0.01) than in controls. At the oropharyngeal and hypopharyngeal levels, the dimensions and the collapsibilities were similar in patients and controls. The velopharyngeal collapsibility correlated with body mass index (p<O.001), whereas the airway size did not. The velopharyngeal collapsibility was more pronounced in patients with frequent episodes of arterial oxyhaemoglobin desaturation during sleep. Velopharyngeal collapsibility associated with high body mass index was the important determinant of nocturnal breathing disturbances. Digital fluoroscopy displays the dynamic changes of the upper airways throughout the respiratory cycle.

Adult↗

PubMed1996

Respiratory challenge induces high frequency spiking on the static charge sensitive bed (SCSB).

The static charge sensitive bed (SCSB) is a simple and noninvasive device used for the detection of sleep apnoea. In addition to episodes of apnoea or hypopnoea, heavy snorers commonly present with episodes of high frequency spiking on the SCSB. These spiking episodes have been claimed to represent partial upper airway obstruction during sleep, but the mechanism of their appearance is not known. We studied the SCSB spiking phenomenon in awake subjects during experimental respiratory challenge. One female and five male volunteers were studied whilst breathing freely, during hypoxia, hypercapnia and inspiratory and expiratory loading. Oxygen saturation, end-tidal carbon dioxide tension, minute ventilation, oesophageal pressure, electrocardiographic activity (ECG), blood pressure and the SCSB signals were monitored. During free breathing, the SCSB high frequency signal consisted of low amplitude complexes with close time relationship to the cardiac cycle. During respiratory challenge, spiking occurred. These spikes showed no time relationship to the cardiac cycle, but were time-linked to the onset of inspiration or expiration. Spike amplitude correlated with breathing frequency (r2 = 0.59; p < 0.005) and variation in oesophageal pressure (r2 = 0.57; p < 0.005). We conclude that during quiet, unobstructed breathing the static charge sensitive bed high frequency signal represents cardiac activity (ballistocardiogram), whereas during high-drive breathing high frequency spikes are produced. These spikes are respiratory in origin and are likely to represent fast components of respiratory movements. Our results support the use of static charge sensitive bed spiking as a noninvasive measure of breathing stimulation.

Adult↗

PubMed1996

The static-charge-sensitive bed in the monitoring of respiration during sleep in infants and young children.

The performance of the static-charge-sensitive bed (SCSB) in the monitoring of nocturnal breathing was studied in 22 infants and young children at the mean age of 24 weeks (SD 24, range 1-79 weeks). The conventional polysomnogram (PSG) was used as a reference method. Episodes of central apnoea were detected with high sensitivity by the SCSB. Episodes of obstructive apnoea and obstructive parts of mixed apnoea were not identified. When the SCSB recordings were scored with the airflow signal some mixed events were identified, but the detection of obstructive apnoea episodes remained poor. Partial upper airway obstruction increased the amount of SCSB spiking (high-frequency components of breathing), which may have diagnostic value. In conclusion, the SCSB enables simple, non-invasive detection of central apnoea episodes, periodic breathing and the behavioural state of the child.

Analysis of Variance↗

PubMed1995

Nocturnal hyperventilation in pregnancy--reversal with nasal continuous positive airway pressure.

A 41-year-old mother with a twin pregnancy had disabling hyperventilation with severe nocturnal symptoms at 25 weeks' gestation. The nocturnal attacks were relieved with nasal continuous positive airway pressure, which she successfully used throughout the rest of the pregnancy. Nasal continuous positive airway pressure could be an option to control severe pregnancy-induced hyperventilation.

Adult↗

PubMed1995

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.

Acromegaly↗

PubMed1995

Ventilatory response to isocapnic hyperoxia.

Breathing O2 for up to 1 h has been shown to either not influence or slightly increase (6-13%) minute ventilation. However, end-tidal PCO2 was not kept constant in these experiments. In nine healthy men, we studied the ventilatory, blood pressure, and heart rate responses to 30 min of normobaric hyperoxia (50% O2) at isocapnic conditions. Hyperoxia led to a 60% increase in mean minute ventilation (P = 0.002), largely due to an increase in mean tidal volume from 0.66 +/- 0.04 (SE) to 0.88 +/- 0.05 liter (P = 0.007). Fifteen minutes after the termination of hyperoxia, minute ventilation was still increased (P = 0.02) compared with baseline, although it was reduced compared with hyperoxia (P = 0.02). Arterial blood gas analyses in six subjects before and during hyperoxia showed an increase in arterial PO2 and O2 saturation but no change in arterial PCO2 or pH. Hyperoxia induced no changes in arterial blood pressure or heart rate. We conclude that 1) isocapnic hyperoxia stimulates respiration markedly, an effect that is approximately five times higher than previously measured; 2) the increase in ventilation induced by hyperoxia does not affect arterial blood pressure and heart rate; and 3) in experiments using hyperoxia, its effect on breathing and subsequently on PCO2 has to be taken into account.

Adult↗