Biomedical subjects

S Tufik

Publications and source records attributed to S Tufik.

At least 73 records · Page 4Linked to original sources

PubMed2000

Polysomnographic respiratory findings in patients with Arnold-Chiari type I malformation and basilar invagination, with or without syringomyelia: preliminary report of a series of cases.

Patients with craniocervical disorders (CCD) show a wide variety of symptoms and signs suggesting cerebellar and/or high cervical lesion. The anatomic localization of respiratory centers and their possible injury may explain the presence of respiratory disturbances in these diseases. The aim of this preliminary study was to evaluate the polysomnographic findings in a group of patients with CCD, most of them with Arnold-Chiari malformation type I, since sleep apnea has been referred to in isolated cases in the literature. Eleven patients (seven females and four males) with CCD diagnosed by magnetic resonance imaging referred from the neurosurgery unit were submitted to clinical history, physical examination with sleep questionnaires, and scored on the Epworth Sleepiness Scale. Full night polysomnography was performed in an Oxford SAC system where EEG, electro-oculography, electrocardiography, chin and leg electromyography, chest and abdominal efforts, airflow, and oximetry were recorded continuously. Nine patients presented with Arnold-Chiari type I malformation, of whom six showed associated syringomyelia. The other two had basilar invagination. Ninety percent of these patients complained of sleep problems (snoring, choking, and witnessed apneas) and 72% presented hypersomnolence (ESS >9). The polysomnographic findings showed sleep fragmentation in 81% of the patients and a reduction of rapid eye movement sleep in 63%. The apnea/hypopnea index was above 5 in 72%, with a predominance of central apnea. Patients with craniocervical disorders present a higher probability of displaying sleep respiratory disturbances. Their sleep complaints should be assessed and patients should be submitted to an overnight sleep recording in order to identify sleep apnea.

Adult↗

PubMed2000

Social stability attenuates the stress in the modified multiple platform method for paradoxical sleep deprivation in the rat.

The instrumental methods to induce paradoxical sleep (PS) deprivation are stressful. The modified multiple platform method (MMPM), in which animals are placed with new cohorts inside the water tanks, results in augmented ACTH and corticosterone (CORT) responses. We hypothesised that this increased response could be attributed to social instability. In addition, we tested a new environmental control, a grid (GR) placed on the tank floor. Animals were submitted to the MMPM for 4 days as socially unstable (UG--coming from several cages) or stable groups (SG--coming from one cage), placed either on narrow platforms or on the grid. All UG animals presented higher ACTH levels than their SG counterparts, including home-cage controls. CORT levels of manipulated animals were higher than controls only in the stable group. UG animals presented heavier adrenals than their SG counterparts. Only adrenals from SG animals placed on the grid were similar to cage controls. SG rats lost less weight than UG animals. While UG animals ate the same amount of chow as home-cage controls, SG animals ate more than control and UG animals. These results suggest that the stress of the MMPM can be attenuated in stable groups. The introduction of a grid on the tank floor may serve an adequate environmental control as far as stress-related variables are considered.

Adrenocorticotropic Hormone↗

PubMed2000

Cholinergic modulation of inhibitory avoidance impairment induced by paradoxical sleep deprivation.

1. Male Wistar rats were submitted to paradoxical sleep deprivation for 96 hr by a modified multiple platform technique. 2. Training of step-through inhibitory avoidance was performed immediately after the last day of paradoxical sleep deprivation. Twenty-four hr after training the animals were submitted to the retention test. 3. In Experiment 1, pilocarpine (4 mg/kg, i.p.) or atropine (4 mg/kg, i.p.) were administered daily during the paradoxical sleep deprivation period. Pilocarpine, but not atropine, reversed the impairment induced by PS deprivation. 4. In Experiment 2, pilocarpine (4, 8 and 12 mg/kg, i.p.) was injected 1 hr before training in order to verify if the reversal of memory impairment was an effect secondary to residual enhanced blood levels of pilocarpine during training. Acute treatment with pilocarpine, in any dose, did not reverse the impairment produced by paradoxical sleep deprivation 5. Activation of the cholinergic system during the period of deprivation is able to prevent memory deficits induced by paradoxical sleep deprivation.

Animals↗

PubMed2000

Randomized, double-blind clinical trial, controlled with placebo, of the toxicology of chronic melatonin treatment.

The objective of the present study was to assess the toxicology of melatonin (10 mg), administered for 28 days to 40 volunteers randomly assigned to groups receiving either melatonin (N = 30) or placebo (N = 10) in a double-blind fashion. The following measurements were performed: polysomnography (PSG), laboratory examinations, including complete blood count, urinalysis, sodium, potassium and calcium levels, total protein levels, albumin, blood glucose, triglycerides, total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL), urea, creatinine, uric acid, glutamic-oxalacetic transaminase (GOT), glutamic-pyruvate transaminase (GPT), bilirubin, alkaline phosphatase, gama-glutamic transaminase (GGT), T3, T4, TSH, LH/FSH, cortisol, and melatonin serum concentrations. In addition, the Epworth Somnolence Scale (ESS) and a sleep diary (SD) were also applied to the volunteers 1 wk before each PSG. In addition, the volunteers were asked about possible side effects (SE) that appeared during the treatment. The study was carried out according to the following timetable: Visit 0, filling out the term of consent and inclusion criteria; Visit 1, PSG, laboratory examinations, ESS, SD, melatonin serum concentrations; Visit 2, SD, melatonin serum concentrations, SE; Visit 3, melatonin serum concentrations, PSG, ESS, SE; Visit 4, laboratory examinations, SE, melatonin serum concentrations, SD; and Visit 5, PSG, ESS, SE. Analysis of the PSG showed a statistically significant reduction of stage 1 of sleep in the melatonin group. No other differences between the placebo and melatonin groups were obtained. In the present study we did not observe, according to the parameters analyzed, any toxicological effect that might compromise the use of melatonin at a dose of 10 mg for the period of time utilized in this study.

Administration, Oral↗

PubMed2000

A double-dissociation of behavioural and event-related potential effects of two benzodiazepines with similar potencies.

This study was designed to explore the role of benzodiazepine affinity to benzodiazepine binding site on acute psychomotor, subjective and memory effects, as well as auditory Event Related Potential (ERP) latencies, in healthy volunteers. Two benzodiazepines with similar affinity to benzodiazepine binding sites, or potency, were compared: the atypical compound lorazepam (2.0 mg), which has been reported to impair priming, and a standard benzodiazepine, flunitrazepam (0.6 mg, 0.8 mg, 1.0 mg). The study followed a placebo-controlled, double-blind, parallel-group design. Sixty subjects completed a test battery before treatment and at theoretical peak plasma concentration of drugs. Lorazepam and 1.0 mg of flunitrazepam led to comparable alterations on psychomotor, subjective and auditory episodic memory measures. A double-dissociation was found for lorazepam and the equipotent dose of flunitrazepam (1.0 mg): lorazepam was more deleterious than flunitrazepam in time taken to identify fragmented shapes. Lorazepam also impaired direct and indirect stem-completion in comparison to placebo, but this effect was abolished when time to identify shapes was used as a covariate. By contrast, 1.0 mg of flunitrazepam prolonged auditory ERP latencies to a greater extent than lorazepam. High affinity to the benzodiazepine binding sites does not seem to explain the consistent lorazepam-induced impairment of indirect stem-completion. Differences in impairment profile between the benzodiazepines employed may relate to the modality (visual or not) of the tasks used.

Adolescent↗

PubMed2000

Rapid eye movements during paradoxical sleep in patients with cerebrovascular disease.

Rapid eye movements that occur during paradoxical sleep are generated from the brainstem and are modulated by cerebral hemispheres. In an attempt to establish the participation of cerebral hemispheres on rapid eye movements, we carried out a quantitative study of eye movements density in patients bearing hemispheres vascular lesions. The polysomnographic recordings of 24 patients were compared to those of 24 healthy volunteers. Density of rapid eye movements was defined as the percentage of eye movements during the respective time of paradoxical sleep. Based on the present results, we concluded that: stroke patients with hemispheric lesions displayed increased density of rapid eye movements; there was no difference on the density of rapid eye movements according to the hemispheric lesion; higher density of rapid eye movements was observed in patients with anterior hemispheric lesion.

Adult↗

PubMed2000

Sleep patterns and sleep-related complaints of Brazilian interstate bus drivers.

Sleep-related complaints have become a highlight for physicians as well as public health administrators. Studies of sleep patterns and sleep-related complaints of shift workers have been useful in minimizing reduction in the quality of life due to the warping of the sleep-wake cycle. The objective of the present study was to assess patterns of sleep, sleep-related complaints as well as physical activity and scoring rates for depression and anxiety in interstate bus drivers. Data were obtained with a sleep questionnaire, with the Beck inventory for depression, and the State-Trait Anxiety Inventory (STAI). A total of 400 interstate bus drivers from the northern, southern, central-western and south-eastern regions of Brazil were interviewed. Sixty percent of the subjects interviewed presented at least one sleep-related complaint, 16% admitted to have dozed at the wheel while on duty, and 41% stated that they exercised on a regular basis. Other sleep disturbance complaints reported were: sleep latency 29'17"; physical fatigue, 59.8%; mental fatigue, 45.4%; sleepiness, 25.8%; irritability, 20.6%; insomnia, 37.5%, respiratory disturbances, 19. 25% and snoring, 20.75%. Scores for anxiety and depression were not in the pathological range. The present data reinforce the view that bus drivers are generally discontent with shift work and its effects on sleep. Consequently, it is very important to establish an appropriate work schedule for drivers, besides implementing photo-therapy and physical activities in order to minimize sleepiness when driving.

Anxiety↗

PubMed2000

Comparison of AutoSet and polysomnography for the detection of apnea-hypopnea events.

The use of the flow vs time relationship obtained with the nasal prongs of the AutoSettrade mark (AS) system (diagnosis mode) has been proposed to detect apneas and hypopneas in patients with reasonable nasal patency. Our aim was to compare the accuracy of AS to that of a computerized polysomnographic (PSG) system. The study was conducted on 56 individuals (45 men) with clinical characteristics of obstructive sleep apnea (OSA). Their mean (+/- SD) age was 44.6 +/- 12 years and their body mass index was 31.3 +/- 7 kg/m2. Data were submitted to parametric analysis to determine the agreement between methods and the intraclass correlation coefficient was calculated. The Student t-test and Bland and Altman plots were also used. Twelve patients had an apnea-hypopnea index (AHI) <10 in bed and 20 had values >40. The mean (+/- SD) AHI PSG index of 37.6 (28.8) was significantly lower (P = 0.0003) than AHI AS (41.8 (25. 3)), but there was a high intraclass correlation coefficient (0.93), with 0.016 variance. For a threshold of AHI of 20, AS showed 73.0% accuracy, 97% sensitivity and 60% specificity, with positive and negative predictive values of 78% and 93%, respectively. Sensitivity, specificity and negative predictive values increased in parallel to the increase in AHI threshold for detecting OSA. However, when the differences of AHI PSG-AS were plotted against their means, the limits of agreement between the methods (95% of the differences) were +13 and -22, showing the discrepancy between the AHI values obtained with PSG and AS. Finally, cubic regression analysis was used to better predict the result of AHI PSG as a function of the method proposed, i.e., AHI AS. We conclude that, despite these differences, AHI measured by AutoSettrade mark can be useful for the assessment of patients with high pre-test clinical probability of OSA, for whom standard PSG is not possible as an initial step in diagnosis.

Adolescent↗

PubMed2000

Catecholamine response to exercise in individuals with different levels of paraplegia.

The purpose of this study was to investigate the effect of the level of injury on the serum level of norepinephrine (Nor) and epinephrine (Epi) at rest and after maximal exercise in individuals with paraplegia. Twenty-six male spinal cord-injured subjects with complete paraplegia for at least 9 months were divided into two groups of 13 subjects each according to the level of injury, i.e., T1-T6 and T7-T12. Serum Nor and Epi concentrations were measured by HPLC-ECD, at rest (PRE) and immediately after a maximal ergospirometric test (POST). Statistical analysis was performed using parametric and non-parametric tests. Maximal heart rate, peak oxygen uptake, and PRE and POST Nor were lower in the T1-T6 than in the T7-T12 group (166 +/- 28 vs 188 +/- 10 bpm; 18.0 +/- 6.0 vs 25.8 +/- 4.1 ml kg(-1) min(-1); 0.54 +/- 0.26 vs 0.99 +/- 0.47 nM; 1.48 +/- 1. 65 vs 3.07 +/- 1.44 nM). Both groups presented a significant increase in Nor level after exercise, while only the T7-T12 group showed a significant increase in Epi after exercise (T1-T6: 0.98 +/- 0.72 vs 1.11 +/- 1.19 nM; T7-T12: 1.24 +/- 1.02 vs 1.89 +/- 1.57 nM). These data show that individuals with paraplegia above T6 have an attentuated catecholamine release at rest and response to exercise as compared to subjects with injuries below T6, which might prevent a better exercise performance in the former group.

Adolescent↗

PubMed2000

Altered sleep and behavioral patterns of arthritic rats.

The present study sought to evaluate concomitant alterations of behavioral and sleep patterns of arthritic rats. Rats were implanted with electrodes for polysomnographic recordings and submitted to the model of arthritis by a subcutaneous (s.c.) administration of Freund adjuvant in the posterior right paw and saline in the posterior left paw. The SHAM group was injected with saline in both paws, whereas the control group (CTL) was not submitted to any manipulation. Behavioral tests were carried out twice before induction of arthritis, on the second day of arthritis, and once a week afterwards until the eighth week. Body weight, colonic temperature, and measurements of the injured paw were carried out on the same days. Arthritic rats presented a reduction of total sleep time, increased latency to synchronized sleep, augmented number of episodes of synchronized sleep, reduction of sleep efficiency, more stage shifts, and increased total alert time. Moreover, these animals presented a lower pain threshold than control and SHAM animals. This reduction was observed on the second day of arthritis and remained so reduced until the end of the study. The data appear to indicate a relationship between altered sleep pattern and increased pain sensitivity in arthritic rats.

Analysis of Variance↗

PubMed1999

Treatment of periodic leg movements with a dopaminergic agonist in subjects with total spinal cord lesions.

OBJECTIVE: To investigate the effect of L-dopa on the PLM/h index of spinal cord injured subjects. SETTING: São Paulo, Brazil. METHODS: Thirteen male volunteers with spinal cord section between T7 - T12, and mean age of 31.6+/-8.3 years participated in the study. L-dopa or placebo were administered for 30 days, 1 h before the volunteers went to sleep, in a double blind, crossover design. Polysomnographic recordings were performed on ten occasions: Phase 1: Basal night, following an adaptation night at the sleep laboratory; phase 2: after 1, 7, 21 and 30 days of L-dopa administration; phase 3: first night of L-dopa or placebo withdrawal; phase IV: 1, 7, 21 and 30 days after placebo ingestion. RESULTS: The index of PLM/h on the first night of L-dopa or placebo withdrawal (phase III) was lower than on both the basal night and the first night of L-dopa treatment. At the time of polysomnographic analysis, volunteers were divided into two groups: index of PLM/h below five and those whose index was above five. Comparison between L-dopa and placebo treatments revealed that only those volunteers with an index above five revealed a reduction in PLM in L-dopa. CONCLUSION: These results indicate that despite the spinal cord lesions, L-dopa treatment is capable of minimizing PLM during sleep.

Adult↗

PubMed1998

Sleep deprivation induces brain region-specific decreases in glutathione levels.

Rats were deprived of sleep for 96 h by the platform technique and total glutathione (GSHtau) levels were measured in seven different brain areas. Glutathione levels were found to be significantly reduced in the hypothalamus of sleep-deprived animals when compared with large platform (-18%) or home cage (-31%) controls. Deprived rats also had reduced GSHtau levels in thalamus compared with home cage controls only. Glutathione levels did not differ among the three groups in any of the other brain areas examined. These results indicate that specific brain areas may be differentially susceptible to oxidative stress after sleep deprivation. The apparent vulnerability of the hypothalamus to these effects may contribute to some of the functional effects of sleep deprivation.

Animals↗

PubMed1998

Effects of haloperidol and GM1 ganglioside treatment on striatal D2 receptor binding and dopamine turnover.

Previous studies have shown that whereas exogenous GM1 ganglioside co-administration leads to an increase of haloperidol-induced behavioral supersensitivity, GM1 significantly attenuates the behavioral parameters of dopaminergic supersensitivity when administered after abrupt haloperidol withdrawal. In the present study, the effects of GM1 and haloperidol co-administration (5 mg/kg GM1 i.p. and 1 mg/kg haloperidol i.p., twice daily, for 30 days) as well as the effects of a 3 day treatment with GM1 were investigated in rats withdrawn from haloperidol administration by measuring striatal D2 dopamine receptor binding and dopamine turnover. The results showed that under these two experimental conditions GM1 modified neither the haloperidol-induced striatal D2 dopamine receptor up regulation nor the decrease in dopamine turnover produced by haloperidol withdrawal. These results suggest that the effects of GM1 on behavioral supersensitivity are not related to modifications in dopamine receptor number or affinity and in the synaptic availability of this catecholamine.

Animals↗

PubMed1998

Heterogeneous effects of rapid eye movement sleep deprivation on binding to alpha- and beta-adrenergic receptor subtypes in rat brain.

Quantitative receptor autoradiography was used to map alterations in binding to alpha1-, alpha2-, beta1- and beta2-adrenergic receptors throughout the brain of rats deprived of rapid eye movement sleep for 96 h. Binding of [3H]prazosin to alpha1 sites, while not significantly different in any of 46 brain regions examined, showed a clear overall tendency towards decreased values after sleep deprivation. [3H]UK-14,314-labeled alpha2 binding sites were not significantly affected by sleep deprivation in any of 91 brain regions analysed, despite a trend towards increased values. In contrast, beta-adrenergic binding was significantly reduced throughout the brain. Binding to beta1 sites labeled by [125I]iodopindolol in the presence of ICI-11855 was significantly reduced in 13 of 69 brain areas examined; binding to beta2 sites labeled by [125I]iodopindolol in the presence of CGP-20712A was likewise reduced throughout the brain and significantly so in 25 of the 72 brain areas analysed. Rank ordering of the binding changes indicated that reductions in beta1 vs beta2 binding were maximal in different brain areas. This pattern of results may reflect a particular configuration of effects specifically associated with sleep loss stress. The results are consistent with evidence of persisting noradrenergic cell activity during sleep deprivation. The observed heterogeneity of effects suggests that not all norepinephrine receptors are equally affected by rapid eye movement sleep deprivation.

Animals↗

PubMed1998

Serum level of serotonin during rest and during exercise in paraplegic patients.

The purpose of this study was to evaluate the serum level of serotonin (5-HT) during rest and response to exercise in subjects with spinal cord injury (SCI) with different levels of physical activity. Twenty-five male subjects with traumatic paraplegia, the neurological levels being between T1 and T12, volunteered for the study. They were divided into two groups matched for age, weight and time since injury, according to the level of physical activity: 14 inactive and 11 subjects regularly involved in sports activity and considered active. They all performed a maximal spiroergometric test with an arm crank ergometer. Two samples of blood were collected for 5-HT determination, during rest (PRE) and immediately after exercise test (POST). Serum 5-HT concentration was measured by high performance liquid chromatography using electrochemical detection (HPLC-ED). The results showed that peak oxygen uptake (VO2peak) was higher in the active group (27.08 +/- 2.60 vs 18.89 +/- 5.58 mL.kg-1.min-1, P < 0.001). There were no significant differences between the inactive and active groups for the 5-HT PRE (respectively 176.96 and 193.73 ng.mL - 1, P > 0.05) or POST values (275.44 vs 311.05 ng.mL-1, P > 0.05). Both groups showed an increment in 5-HT after maximal exercise, but only in the active group it reached statistical significance (Wilcoxon test, P < 0.02). Our results show that chronic paraplegic individuals have normal resting serum serotonin levels and normal response to exercise. The relationship between training status, mood elevation and 5-HT in SCI could not be established in the present study, and further investigation is needed to clarify this issue.

Adult↗

PubMed1998

Effect of aerobic training on ventilatory muscle endurance of spinal cord injured men.

The functional consequences of ventilatory muscle impairment of spinal cord injured (SCI) subjects has been evaluated through spirometric and maximal respiratory pressure tests. Nevertheless, underlying functional abnormalities may be evident only under dynamic conditions, such as with a ventilatory muscle endurance test (VME). In order to evaluate the VME of thoracic SCI men and the effect of physical training on it we evaluated 12 SCI subjects (Group I) and 12 able-bodied controls (Group II). The subjects were submitted to clinical evaluation, spirometry, maximum voluntary ventilation in 12 s (MVV-12 sec) and a test of VME-the highest time of sustained ventilation at 70% of the maximum voluntary ventilation in isocapnic conditions (MVV-70% time). Gr. II was evaluated before and after an arm cranking aerobic training program (30 min/session, three times/week, 6 weeks) with training target heart rate corresponding to ventilatory anaerobic threshold. On the initial evaluation, Gr. I subjects presented a significantly reduced forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and MVV-12 sec when compared to controls (P < 0.05). Also, the VME was severely reduced in Group I (median, ranges; 1.15, 0.61-12.22) when compared to Group II (14.60, 1.20-15.00) - P < 0.001. When Gr. I subjects were separated by the level of lesion, the VME was lower in high injured (T1-T7) than intermediate (T8-T10) and low injured patients (T11-T12)-P < 0.05. After aerobic training, Group I subjects incremented significantly the FVC (P < 0.05) and the VME (P < 0.001), so that MVV-70% time values post-training were not different from the initial values of the Gr. II. In conclusion, (i) the VME of thoracic SCI men was severely reduced when compared to able-bodied controls; (ii) a 6-weeks arm cranking aerobic training program was efficient to normalize the VME of SCI subjects.

Adult↗

PubMed1998

Increased ACTH and corticosterone secretion induced by different methods of paradoxical sleep deprivation.

The methods used to induce paradoxical sleep (PS) deprivation are believed to be stressful. In the present study, two methods were compared in regard to their ability to activate the hypothalamic-pituitary-adrenal (HPA) axis. Animals were placed on multiple large (MLP) or small (MSP) platforms or on single large (SLP) or small (SSP) platforms and blood sampled at the end of a 4-day period of PS deprivation (experiment 1) or on Days 1 (short-term) and 4 (long-term) of PS deprivation (experiment 2). ACTH and corticosterone (CORT) levels were determined by RIA. The results of experiment 1 showed that all experimental animals presented increased ACTH response, compared to controls. CORT levels, however, were only elevated in MSP animals, suggesting increased adrenal sensitivity. Experiment 2 showed that ACTH levels of MSP animals were higher than MLP and SSP animals, and that animals placed on the multiple platform tanks showed the highest ACTH levels on Day 4 of manipulation. CORT levels were elevated in the animals kept over small platforms, and these levels where higher on Day 1 than basal and further elevated on Day 4 of PS deprivation. These results indicate that the multiple platform technique induces a distinct activation of the HPA axis, and that PS deprivation may act as an additional stressor.

Adrenocorticotropic Hormone↗

PubMed1998

Assessment of ventilatory neuromuscular drive in patients with obstructive sleep apnea.

The presence of abnormalities of the respiratory center in obstructive sleep apnea (OSA) patients and their correlation with polysomnographic data are still a matter of controversy. Moderately obese, sleep-deprived OSA patients presenting daytime hypersomnolence, with normocapnia and no clinical or spirometric evidence of pulmonary disease, were selected. We assessed the ventilatory control and correlated it with polysomnographic data. Ventilatory neuromuscular drive was evaluated in these patients by measuring the ventilatory response (VE), the inspiratory occlusion pressure (P.1) and the ventilatory pattern (VT/TI, TI/TTOT) at rest and during submaximal exercise, breathing room air. These analyses were also performed after inhalation of a hypercapnic mixture of CO2 (delta P.1/delta PETCO2, delta VE/delta PETCO2). Average rest and exercise ventilatory response (VE: 12.2 and 32.6 l/min, respectively), inspiratory occlusion pressure (P.1: 1.5 and 4.7 cmH2O, respectively), and ventilatory pattern (VT/TI: 0.42 and 1.09 l/s; TI/TTOT: 0.47 and 0.46 l/s, respectively) were within the normal range. In response to hypercapnia, the values of ventilatory response (delta VE/delta PETCO2: 1.51 l min-1 mmHg-1) and inspiratory occlusion pressure (delta P.1/delta PETCO2: 0.22 cmH2O) were normal or slightly reduced in the normocapnic OSA patients. No association or correlation between ventilatory neuromuscular drive and ventilatory pattern, hypersomnolence score and polysomnographic data was found; however a significant positive correlation was observed between P.1 and weight. Our results indicate the existence of a group of normocapnic OSA patients who have a normal awake neuromuscular ventilatory drive at rest or during exercise that is partially influenced by obesity.

Adult↗