Selecting the best set of gas chromatography-derived fatty acids to discriminate between two finishing diets using linear discriminant analysis.

Linear discriminant analysis (LDA) was investigated as a method for identifying the type of finishing diet fed to bulls (n=169) based on gas chromatography fatty acid (FA) analysis. The bulls were fed ad libitum a high concentrate diet comprised of a cereal-soybean meal based concentrate plus straw offered separately (HC) or a total mixed ration made of cereal, soybean meal, maize silage and straw (TMR). Eleven variables (10 FA and one FA ratio) were selected as statistically significant predictors out of 41 variables tested. The Mahalanobis squared distance between the HC and TMR groups was 3.386 and F-test of the distance was highly significant (P>0.001). In cross-validated classification matrices, 18 cases were misclassified in the HC group and 16 cases were misclassified in the TMR group. As a result, 79.9% of original grouped cases were classified correctly. We concluded that it was possible to classify beef samples according to their finishing diets using LDA.

Orexin receptor antagonism, a new sleep-enabling paradigm: a proof-of-concept clinical trial.

The orexin system is a key regulator of sleep and wakefulness. In a multicenter, double-blind, randomized, placebo-controlled, two-way crossover study, 161 primary insomnia patients received either the dual orexin receptor antagonist almorexant, at 400, 200, 100, or 50 mg in consecutive stages, or placebo on treatment nights at 1-week intervals. The primary end point was sleep efficiency (SE) measured by polysomnography; secondary end points were objective latency to persistent sleep (LPS), wake after sleep onset (WASO), safety, and tolerability. Dose-dependent almorexant effects were observed on SE , LPS , and WASO . SE improved significantly after almorexant 400 mg vs. placebo (mean treatment effect 14.4%; P < 0.001). LPS (­18 min (P = 0.02)) and WASO (­54 min (P < 0.001)) decreased significantly at 400 mg vs. placebo. Adverse-event incidence was dose-related. Almorexant consistently and dose-dependently improved sleep variables. The orexin system may offer a new treatment approach for primary insomnia.

Uvulopalatopharyngoplasty with an ultrasound scalpel or laser: is there a difference?

Uvulopalatopharyngoplasty (UPPP) is used for treatment of the obstructive sleep apnoea syndrome, mainly in the lower range of the apnoea-hypopnea index or partial upper airway obstruction. Significant severe pain after UPPP is associated in the area having surgery and therefore less pain causing methods should be investigated. In this study, we compared laser-assisted and ultrasound scalpel-performed UPPP. Sleep apnoea patients (n = 40) recruited to the study were divided into two groups. UPPP was performed with either laser-assisted or an ultrasound scalpel. Perioperative bleeding, operating room time and duration of operation together with histological injury of soft palate were analysed. A postoperative follow-up questionnaire included a self analysis of pain, dietary intake and pain drug consumption. In the same follow-up form, filled in by patients themselves, possible side effects and adequacy of pain medication together with any postoperative haemorrhage events were recorded during 10-day study period after UPPP. The ultrasound scalpel group had significantly fewer haemorrhagic events (P = 0.037) during postoperative follow-up time after UPPP when compared to laser-assisted group. The pain values of all 40 patients were significantly higher in the morning than in the afternoon (P < 0.001) or evening (P < 0.001). Pain increased up to the fifth postoperative day (visual analogue scale, VAS = 46). The significant relief of pain to the mild level (VAS < 30 mm) occurred at ninth and tenth postoperative day. The ultrasound scalpel used as a surgical method in UPPP did not offer significant comprehensive benefits in this study compared to laser-assisted UPPP. Exclusively, postoperative haemorrhage events were minor, paralleling findings of previous studies where ultrasound scalpel had been used for tonsillectomy. We conclude that the ultrasound scalpel is comparable to laser-assisted UPPP.

Transcutaneous carbon dioxide profile during sleep reveals metabolic risk factors in post-menopausal females.

The risks of metabolic syndrome and sleep-disordered breathing increase around the time of the menopause. We have previously shown that features of the nocturnal transcutaneous carbon dioxide (TcCO2) profile are associated with metabolic variables such as cholesterol, glycosylated haemoglobin A1C (GHbA1C) and blood pressure in patients with sleep apnoea. In the present study, we investigated whether these metabolic variables can be predicted using noninvasive TcCO2 measurements during sleep in generally healthy post-menopausal females. 22 post-menopausal females underwent an overnight polygraphic sleep study that involved the continuous monitoring of arterial oxygen saturation (S(a,O2)) and TcCO2. Body composition, GHbA1C, plasma cholesterol and blood pressure were measured prior to the sleep study. Nocturnal TcCO2 features were the most important predictors of lipoprotein cholesterols, triglycerides and blood pressure levels. A longer sleep period and higher TcCO2 levels were linked with lower GHbA1C, and fragmented sleep with lower high-density lipoprotein cholesterol. Neither nocturnal S(a,O2) indices nor the apnoea/hypopnoea index had a predictive power. The results suggest that nocturnal TcCO2 events revealed metabolic risk factors already present in healthy post-menopausal females.

Replication of restless legs syndrome loci in three European populations.

BACKGROUND: Restless legs syndrome (RLS) is associated with common variants in three intronic and intergenic regions in MEIS1, BTBD9, and MAP2K5/LBXCOR1 on chromosomes 2p, 6p and 15q. METHODS: Our study investigated these variants in 649 RLS patients and 1230 controls from the Czech Republic (290 cases and 450 controls), Austria (269 cases and 611 controls) and Finland (90 cases and 169 controls). Ten single nucleotide polymorphisms (SNPs) within the three genomic regions were selected according to the results of previous genome-wide scans. Samples were genotyped using Sequenom platforms. RESULTS: We replicated associations for all loci in the combined samples set (rs2300478 in MEIS1, p = 1.26 x 10(-5), odds ratio (OR) = 1.47, rs3923809 in BTBD9, p = 4.11 x 10(-5), OR = 1.58 and rs6494696 in MAP2K5/LBXCOR1, p = 0.04764, OR = 1.27). Analysing only familial cases against all controls, all three loci were significantly associated. Using sporadic cases only, we could confirm the association only with BTBD9. CONCLUSION: Our study shows that variants in these three loci confer consistent disease risks in patients of European descent. Among the known loci, BTBD9 seems to be the most consistent in its effect on RLS across populations and is also most independent of familial clustering.

The effect of estrogen plus progestin treatment on sleep: a randomized, placebo-controlled, double-blind trial in premenopausal and late postmenopausal women.

OBJECTIVE: In this prospective randomized, placebo-controlled and double-blind study, the objective was to investigate the effects of estrogen-progestin treatment (EPT) on sleep in pre- and postmenopausal women. DESIGN: Seventeen premenopausal (aged 45-51 years) and 18 postmenopausal (aged 58-70 years) women were studied in a sleep laboratory for two nights (one night for adaptation and one study night) before and after 6 months of treatment with EPT or placebo. During the treatment period, premenopausal women received cyclic EPT or placebo and the postmenopausal women continuous EPT or placebo. Polysomnography and questionnaires were used to evaluate sleep and well-being. RESULTS: At the end of the treatment period, premenopausal women receiving EPT had more awakenings from stage 1 sleep (p = 0.047) and postmenopausal women with EPT had a greater total number of awakenings (p = 0.031) than the corresponding placebo group. Further, sleepiness decreased less in the premenopausal EPT group than in the placebo group (p = 0.031). In postmenopausal women, EPT decreased and placebo slightly increased slow wave activity during the second non-rapid eye movement sleep episode (p = 0.046). CONCLUSIONS: In premenopausal and late postmenopausal women, EPT had only random and marginal effects on sleep. Although the limited findings were mostly unfavorable for EPT, one cannot conclude that EPT deteriorates sleep. Further, neither middle-aged cycling premenopausal women nor older postmenopausal women benefit from estrogen-progestin treatment in terms of their sleep quality.

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.

Parameter estimation of a respiratory control model from noninvasive carbon dioxide measurements during sleep.

A new method for estimating the parameters of a human gas exchange model is presented. Sensitivity analysis is used both to inspect the relative importance of the model parameters and to speed up the par-ameter estimation process. Multistart optimization is used to compensate for the effects of partial and noisy measurements. The validity of the method is first investigated with a test problem for which par-ameter identifiability is shown. The method is then applied to the estimation of sleep-related changes in the respiratory control system from the end-tidal and transcutaneous carbon dioxide measurements on human subjects. The results show that it is possible to gain insight into the behaviour of the rather complex physiological system using only a few noninvasive measurements and tractable computations.

Model-based analysis of mechanisms responsible for sleep-induced carbon dioxide differences.

This work describes a comprehensive mathematical model of the human respiratory control system which incorporates the central mechanisms for predicting sleep-induced changes in chemical regulation of ventilation. The model integrates four individual compartments for gas storage and exchange, namely alveolar air, pulmonary blood, tissue capillary blood, body tissues, and gas transport between them. An essential mechanism in the carbon dioxide transport is its dissociation into bicarbonate and acid, where a buffering mechanism through hemoglobin is used to prevent harmfully low pH levels. In the current model, we assume high oxygen levels and consider intracellular hydrogen ion concentration as the principal respiratory control variable. The resulting system of delayed differential equations is solved numerically. With an appropriate choice of key parameters, such as velocity of blood flow and gain of a non-linear controller function, the model provides steady-state results consistent with our experimental observations measured in subjects across sleep onset. Dynamic predictions from the model give new insights into the behaviour of the system in subjects with different buffering capacities and suggest novel hypotheses for future experimental and clinical studies.

Efficacy of pergolide in treatment of restless legs syndrome: the PEARLS Study.

OBJECTIVE: To evaluate the short- and long-term safety and efficacy of pergolide therapy for restless legs syndrome (RLS) in a double-blind, placebo-controlled, randomized trial (Pergolide European Australian RLS [PEARLS] study). METHODS: We randomized 100 patients with idiopathic RLS were randomized to pergolide, 0.25 to 0.75 mg, in the evening or placebo for 6 weeks (phase 1); thereafter, patients with response on the Patient Global Impression (PGI) scale continued on double-blind pergolide or placebo, and nonresponders received open-label pergolide up to 1.5 mg/d for 12 months of treatment (phase 2). Sleep efficiency (SE) and periodic limb movements during sleep (PLMS) arousal index were monitored by centrally evaluated polysomnography (PSG). The severity of RLS was assessed using the validated International RLS Scale (IRLS). RESULTS: In phase 1 (change from baseline to week 6), pergolide reduced PLMS arousal index vs placebo (mean +/- SD, -12.6 +/- 10.0 vs -3.6 +/- 15.9; p = 0.004), and SE did not improve (mean +/- SD, +11.3 +/- 11.9% vs +6.1 +/- 18.6%; p = 0.196). Pergolide improved RLS severity score (-12.2 +/- 9.9 vs -1.8 +/- 7.5 placebo; p < 0.001) and was associated with a higher PGI response (68.1% vs 15.1%; p < 0.001) and improvements in periodic limb movements (PLM) index, PGI improvement scale, Clinical Global Impression improvement, and IRLS (all p < 0.001), patient-reported SE (p = 0.019), and quality of sleep (p < 0.001). After 12 months (phase 2), double-blind pergolide maintained improvements in PLMS arousal index and PLM index. Placebo patients switched to open-label pergolide in phase 2 exhibited marked improvements in these measures that were maintained at 12 months. Pooled results from the blinded and open-label pergolide groups demonstrated improvements at 12 months in the PLMS arousal index (p = 0.028) and PLM index (p < 0.0001) compared with placebo. Nausea and headache were more frequent with pergolide than with placebo treatment. CONCLUSIONS: Pergolide substantially improves periodic limb movement measures and subjective sleep disturbance associated with restless legs syndrome. Low-dose pergolide was well tolerated and maintained its efficacy in the long term.

Sleep-disordered breathing and hormones.

Sleep-disordered breathing (SDB) is not only a problem of the upper airway but is a systemic condition with endocrine and metabolic interactions. The accumulating body of evidence shows that SDB induces changes in the serum levels or secretory patterns of several hormones. Conversely, various endocrine disorders and hormone therapies may induce, exacerbate or alleviate SDB. Much of the understanding of the interactions between hormones and sleep-disordered breathing derive from intervention studies with nasal continuous positive airway pressure therapy. Better understanding of hormones and breathing may open new perspectives in developing strategies to prevent, alleviate or cure sleep-disordered breathing and its systemic consequences.

Effect of medroxyprogesterone on arterial blood gases, leptin and neuropeptide Y in postmenopausal females.

Natural progesterone, a potent respiratory stimulant, stimulates leptin production in premenopausal females. Leptin and its counterpart neuropeptide Y (NPY) have recently been linked with respiration. The effect of medroxyprogesterone acetate (MPA) on arterial blood gases, serum leptin and NPY was evaluated in this study. Fourteen postmenopausal females with respiratory impairment, due mostly to chronic obstructive pulmonary disease, were recruited for a randomised, double-blind, placebo-controlled crossover trial. Arterial blood gases, serum leptin and NPY concentrations were measured at baseline and after 14 days of treatment with placebo and MPA, separated by a 6-week washout period. Thirteen patients completed the trial. The mean+/-SD carbon dioxide tension in arterial blood (Pa,CO2) was 5.4+/-0.6 kPa at baseline, and decreased by 0.8+/-0.3 kPa during treatment with MPA. The oxygen tension in arterial blood (Pa,O2) and pH did not change. At baseline, the mean base excess was 0.6+/-1.9 mmol x L(-1) and the mean bicarbonate (HCO3-) concentration was 25.1+/-1.6 mmol x L(-1). With MPA, base excess decreased by 2.2+/-1.2 mmol x L(-1) and HCO3- by 1.9+/-1.0 mmol x L(-1) from baseline. The mean concentrations of serum leptin (19.8+/-9.9 microg x L(-1) at baseline, 19.7+/-9.8 microg x L(-1) with MPA) or NPY (94.0+/-18.3 pmol x L(-1) at baseline, 85.1+/-41.2 pmol x L(-1) with MPA) did not change. However, the reduction in Pa,CO2 correlated with the reduction of serum leptin concentration. Medroxyprogesterone acetate effectively decreased the carbon dioxide tension in postmenopausal females with chronic respiratory impairment. The results suggest that a decrease in the carbon dioxide tension of > or = 0.9 kPa is necessary for a reduction in serum leptin concentration.

Effect of medroxyprogesterone on pulmonary arterial pressure, exhaled nitric oxide, ECG and arterial blood gases.

OBJECTIVES: To evaluate the effect of medroxyprogesterone acetate (MPA) therapy on pulmonary arterial pressure (PAP), exhaled nitric oxide (NO), electrocardiogram (ECG), and on arterial blood gases (ABG). DESIGN: A double-blind randomized placebo-controlled cross-over trial. SETTING: University hospital in Turku, Finland. SUBJECTS: Fourteen postmenopausal women with respiratory impairment. INTERVENTIONS: A 2-week placebo and a 2-week MPA period (60 mg day -1) followed by 6-week placebo or MPA washout periods. MAIN OUTCOME MEASURES: The systolic PAP was estimated by Doppler echocardiography. PAP, ECG, NO and ABG were monitored at baseline, after 2-week placebo and MPA periods, and after 3- and 6-week placebo and MPA washout periods. RESULTS: The mean PaCO2 at baseline was 5.4 +/- 0.6 kPa (mean +/- SD). The average decrease of PaCO2 on MPA was -0.8 +/- 0.3 kPa (P < 0.001) and 0.3 +/- 1.0 kPa (P = 0.007) at the 3-week washout. The mean systolic PAP at baseline was 44.3 +/- 14.5 mm Hg. MPA did not change PAP until the 6-week washout, when the average increase of + 6.9 +/- 19.8 mm Hg (P = 0.002) was observed. No changes occurred in PaO2, exhaled NO or the ECG axes. The PR interval was shorter only on MPA (15.9 +/- 27.0 ms, P = 0.020) whereas the QRS duration remained shorter up to 3-week washout (3.9 +/0 5.5 ms, P = 0.008 and 4.0 +/- 14.3 ms, P = 0.032). The systolic and diastolic BP and the heart rate did not change. CONCLUSIONS: Despite prolonged decrease in PaCO2, short-term MPA had no effect on exhaled NO and did not decrease systolic PAP in postmenopausal women with respiratory impairment. MPA shortened the PR interval and the QRS duration, the latter effect being sustained at least up to 3 weeks.

Adjustment of the human respiratory system to increased upper airway resistance during sleep.

A cardiorespiratory model incorporating control of the human upper airway during sleep is described. Most previous models have not considered the possibility that the upper airway could be a limiting factor for gas exchange. Our model was developed to also predict certain pathophysiological phenomena in the cardiorespiratory system that characterize heavy snoring or sleep apnea. We started by adapting our collapsible upper airway model to include the impact of nasal passage and larynx, and extended the model with equations for gas exchange in the lungs. A feedback loop both to the respiratory pump and the upper airway dilator muscles was included. The model enabled successful breath-by-breath simulations of obstructive events of the upper airway. Although the model incorporates several physiologically relevant components of the system, the simulation results suggest that only few parameters suffice to predict the key adjustments that the cardiorespiratory system is known to make in patients with heavy snoring.

Sleep-related disordered breathing during pregnancy in obese women.

STUDY OBJECTIVES: This study was designed to evaluate sleep-related disordered breathing in obese women during pregnancy. Obesity is known to predispose to sleep-related breathing disorders. During pregnancy, obese mothers gain additional weight, but other mechanisms may counteract this effect. DESIGN: A case-control study to compare sleep-related breathing in obese pregnant women (mean prepregnancy body mass index [BMI] > 30 kg/m(2)) with pregnant women of normal weight (mean BMI, 20 to 25 kg/m(2)). SETTING: University teaching hospital with a sleep laboratory. PARTICIPANTS: We recruited 11 obese women (BMI, 34 kg/m(2); mean age 31 years) and 11 control women (BMI, 23 kg/m(2); mean age 32 years). INTERVENTIONS: Overnight polysomnography was performed during early (after 12 weeks) and late (after 30 weeks) pregnancy. MEASUREMENTS AND RESULTS: During pregnancy, obese mothers gained 13 kg and control women gained 16 kg. Sleep characteristics did not differ between the groups. During late pregnancy, the women in both groups slept more poorly and slept in supine position less. During early pregnancy, their apnea-hypopnea indexes (1.7 events per hour vs 0.2 events per hour; p < 0.05), 4% oxygen desaturations (5.3 events per hour vs 0.3 events per hour; p < 0.005), and snoring times (32% vs 1%, p < 0.001) differed significantly. These differences between the groups persisted in the second polysomnography, with snoring time further increasing in the obese. Preeclampsia and mild obstructive sleep apnea were diagnosed in one obese mother. One obese mother delivered a baby showing growth retardation (weight - 3 SD). CONCLUSIONS: We have shown significantly more sleep-related disordered breathing occurring in obese mothers than in subjects of normal weight, despite similar sleeping characteristics.

Aetiology and treatment of sleep disturbances during perimenopause and postmenopause.

The sudden and predictable cessation of ovarian endocrinological function at menopause results in a marked decrease of endogenous estrogen and progestogen secretion. In addition to cessation of menstruation, a wide range of biological functions, including sleep, are affected. Sleep disturbances are more common in women than in men and their incidence increases with age. There are 2 distinct mechanisms by which menopause is known to affect sleep quality. One is menopausal insomnia, which can be considered as part of the symptomatology of the climacterium. Another is sleep-disordered breathing, where impairment of sleep quality is secondary to sleep apnoea or partial upper airway obstruction during sleep. The former is effectively controlled with conventional estrogen replacement therapy, whereas the latter could potentially be improved with progestogens. Many age-related conditions without a direct link with the menopause should also be considered when treating postmenopausal sleep disorders.

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.

A model of a snorer's upper airway.

In snorers, the physiologic decrease of postural muscle tone during sleep results in increased collapsibility of the upper airway. Measurement of nasal pressure changes with prongs is increasingly used to monitor flow kinetics through a collapsing upper airway. This report presents a mathematical model to predict nasal flow profile from three critical components that control upper airway patency during sleep. The model includes the respiratory pump drive, the stiffness of the pharyngeal soft tissues, and the dynamic support of the muscles surrounding the upper airway. Depending on these three components, the proposed model is able to reproduce the characteristic changes in flow profile that are clinically observed in snorers and non-snorers during sleep.

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.

Analysis of inspiratory flow shapes in patients with partial upper-airway obstruction during sleep.

STUDY OBJECTIVE: To study the spectrum of inspiratory flow signal shapes in patients with partial upper airway obstruction during sleep. DESIGN: We identified seven different inspiratory flow shapes and determined their frequencies in two groups of patients (10 postmenopausal women and 19 men after surgical treatment for sleep apnea) and in 9 control subjects. SETTING: Sleep research unit, Department of Physiology, University of Turku, Finland. MEASUREMENTS AND RESULTS: Nasal flow was recorded with nasal prongs. The shape analyses were performed with an automated attribute grammar recognizer. The inspiratory flow-shape distributions differed significantly between patients and control subjects. The flow shapes were also different between postmenopausal women and men after uvulopalatopharyngoplasty. CONCLUSIONS: The differences in the inspiratory flow-shape distributions between the control subjects and the two patient groups suggest that the upper airways behave differently in the three study groups. Automated inspiratory flow-shape analysis seems to be a promising tool to distinguish patient groups with different upper airway function to be treated with different treatment alternatives. The physiologic correlates of each flow-shape class remain to be elucidated.