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Biomedical subjects

T Penzel

Publications and source records attributed to T Penzel.

At least 19 recordsLinked to original sources
PubMed2000

Vigilance stages and performance in OSAS patients in a monotonous reaction time task.

OBJECTIVES: To develop improved methods for objective assessment of daytime vigilance. This is important in the diagnosis and therapy control of sleep disorders associated with excessive daytime sleepiness (EDS). METHODS: Twenty-one patients with EDS due to obstructive sleep apnea were recorded during a daytime 90 min reaction time (RT) test in a monotonous situation. Two EEG, two EOG and a submental EMG channel were recorded simultaneously. The recordings were divided into short, stationary segments of variable length (0.5-2 s) and classified into 7 stages using our previously described system, which includes additional stages for drowsiness. RESULTS: The duration of RT was linearly correlated to the vigilance state (P<0.05). The appearance of slow eye movements (SEM) was more consistently related to performance impairment than EEG changes. CONCLUSIONS: Our system can provide a better tracking of vigilance changes than the standardized sleep stage scoring. A 1-2 h test is useful in the assessment of the performance of a subject suffering from EDS. We found that SEMs indicate more sensitive and consistent EDS-related performance impairment than changes in EEG activity.

Adult↗
PubMed2000

The relationship between normal lung sounds, age, and gender.

Auscultation is one of the most important noninvasive and feasible methods for the detection of lung diseases. Systematic changes in breathing sounds with increasing age are of diagnostic importance. To investigate these changes, we recorded lung sounds taken from four locations in the posterior thorax of 162 subjects, together with airflow. The data were analyzed according to age, sex, and smoking habit. In order to describe the power spectrum of the lung sounds, we calculated mean and median frequency, frequency with the highest power, and a ratio (Q) of relative power of the two frequency bands of 330 to 600 Hz and 60 to 330 Hz. Linear regression analysis was used as a measurement of age-dependence of these variables. Significant differences in Q were found in men versus women (p < 0.05), but not in smokers versus nonsmokers. Within the groups, a small but significant correlation existed between Q and age (r(2) </= 0.1, p < 0.05). For both men and women, a slight increase of the relative power in the frequency band of 330 to 600 Hz was recorded with increasing age. However, on the basis of large individual variations, these small changes (DeltaQ approximately 5%, SD(Q) >/= +/- 5%) have no clinical significance and need not to be considered in the automatic detection of lung diseases by analyzing lung sounds.

Adult↗
PubMed1999

Respiratory arousals in mild obstructive sleep apnea syndrome.

The objective of the study is to identify patients with mild sleep apnea by counting not only apneas and hypopneas, but also mild respiratory events, which do not fulfill apnea or hypopnea criteria, but result in an arousal (Type-R arousal). Arousals related to body movements (Type-M arousal) were separately counted. The influence of nasal continuous positive airway pressure (nCPAP) on respiratory and movement arousals was analyzed. Daytime sleepiness before and after nCPAP and its relationship to arousal types was investigated using the Multiple Sleep Latency Test (MSLT) and a standardised questionnaire. Twenty-two patients with a mean age of 43.6 +/- 9.2 years underwent polysomnographic evaluation on a baseline night, and during three nights with nCPAP. On the baseline night, subjects presented with a mean RDI of 10.5 +/- 7.2/h, an apnea index (AI) of 1.2 +/- 1.5/h, a hypopnea index (HI) of 9.3 +/- 6.6/h, a R index of 5.2 +/- 5.9/h, and a M index of 9.7 +/- 5.6/h. Use of nCPAP lowered the RDI (p < 0.001) and the R index (p < 0.01). Mean sleep latency in the MSLT increased with nCPAP (p < 0.05) and the patient's subjective well being improved (p < 0.01). Correlation analysis revealed a relationship between Type-R arousals and RDI and HI (r = 0.5, p < 0.01) as well as between questionnaire scores and mean sleep latency. The decrease of Type-R indicates the positive effect of nCPAP. Arousal analysis and detection of mild respiratory events associated with arousals are helpful in investigating the sleep structure and in objectifying clinical symptoms and treatment success in patients with mild OSAS.

Adult↗
PubMed1999

A randomized controlled study of pergolide in patients with restless legs syndrome.

BACKGROUND: Open clinical trials indicate that low doses of pergolide, a long-acting D1 and D2 dopamine agonist, lead to a reduction in the symptoms of restless legs syndrome (RLS) with subjective improvement in sleep quality. OBJECTIVE: To assess the therapeutic efficacy of pergolide in improving sleep and subjective measures of well-being in patients with idiopathic RLS using polysomnography and clinical ratings. METHODS: In a randomized, double-blind, placebo-controlled crossover design we enrolled 30 patients with idiopathic RLS according to the criteria of the International RLS Study Group. All patients were free of psychoactive drugs for at least 2 weeks before the study. Patients were monitored using polysomnography, clinical ratings, and sleep diaries at baseline and at the end of a 4-week pergolide or placebo treatment period. The initial dosage of 0.05 mg pergolide was increased to the best subjective improvement paralleled by 20 mg domperidone tid. RESULTS: At a mean dosage of 0.51 mg pergolide as a single daily dose 2 hours before bedtime, there were fewer periodic leg movements per hour of time in bed (5.7 versus 54.9, p < 0.0001), and total sleep time was significantly longer (373 versus 261 minutes, p < 0.0001). Ratings of subjective sleep quality, quality of life, and severity of RLS were improved significantly without relevant adverse events. CONCLUSION: Pergolide given as a single low-to-medium bedtime dose in combination with domperidone provides a well-tolerated and effective treatment of sensorimotor symptoms and sleep disturbances in patients with primary RLS.

Adult↗
PubMed1999

Does short-term treatment with modafinil affect blood pressure in patients with obstructive sleep apnea?

OBJECTIVE: To investigate the effects of modafinil, a central nonamphetamine awakening substance, on blood pressure and heart rate in hypersomnolent patients with obstructive sleep apnea. DESIGN: This double-blind, randomized, placebo-controlled crossover trial was performed over 2 days and 3 nights in a single-center study of hospitalized patients from a referred care center. Twenty-six otherwise healthy men (age range, 30 to 60 years) with mild to moderate obstructive sleep apnea were recruited by the outpatient department of the Marburg University Sleep Laboratory. Patients were given 200 mg oral modafinil in the morning and 100 mg at midday. Placebo was given in the same manner in a crossover design. Mean arterial (radial) blood pressure was monitored continuously during nocturnal sleep and during a series of standardized daytime physical and psychologic performance tests. RESULTS: The difference in the main end point between the treatment with modafinil and placebo was 1.17+/-0.83 (mean +/- SE) mm Hg (95% confidence interval: -0.56 to 2.91 mm Hg). The maximal differences in blood pressure values occurred under loaded conditions (systolic blood pressure, ergometry: 5.62+/-1.13 mm Hg; mental stress test: 6.19+/-1.33 mm Hg). CONCLUSION: Short-term administration of modafinil did not elicit a significant response with regard to the main end point. However, cardiovascular effects during mental and physical load were observed. Longterm studies that include subjects with hypertension are necessary to investigate the clinical relevance of the cardiovascular effects of modafinil.

Adult↗
PubMed1999

Vigilance transitions in reaction time test: a method of describing the state of alertness more objectively.

Electrophysiological recordings are considered a reliable method of assessing a person's alertness. The aim of this study was to show, firstly, that changes in alertness during a Reaction Time Test (RTT) can be determined with certain adaptive scoring stages but not with R&K scoring and secondly, that the different adaptive stages can explain findings in reaction time. In 17 male patients (50.8+/-9.7 years, Body-Mass Index (BMI) 31.9+/-5.1 kg/m2) diagnosed with Obstructive Sleep Apnea Syndrome (OSAS) (Respiratory Disturbance Index (RDI) 53.3+/-24.1 /h sleep) a 90 min daytime vigilance test was performed twice, after the diagnostic polysomnographic investigation and after two nights spent with nCPAP. After a computerised adaptive segmentation analysis, a visual rule-defined classification system categorised alertness into one of 12 adaptive scoring stages. 6 of the 12 stages are described by the alertness conditions comparable to WAKE and NREM1.4 stages are nearly classified as NREM2-4, Rapid Eye Movement (REM) and Movement Time (MT), and one stage reflects the increase of alertness from drowsiness. The typical stage of an alert subject increased significantly from a median of 65.9% before therapy to 80.8% in the second investigation. The percentages of clearly drowsy stages decreased significantly. In contrast, there were no significant changes in the percentages of sleep stages according to R&K criteria for both investigations. According to R&K criteria 178 of 398 failed reactions (Reaction time >10 s) occurred in stage WAKE. According to adaptive scoring, only 12 failed reactions appeared in the alert stage. During the other failed reactions the electrophysiological recordings showed decreases in alertness. Neither the visual assessment nor the descriptive statistical results of R&K scoring were helpful to interpret the patient's alertness condition. In contrast, the patients' increases in alertness with nCPAP could be described by the adaptive scoring stages. This method could be a very useful procedure, when an expert opinion is necessary. It also has an actual context to the discussion of the effectiveness of CPAP in the treatment of OSAS.

Adult↗
PubMed1999

Quality control of polysomnographic sleep data by histogram and entropy analysis.

OBJECTIVE AND METHODS: Sixteen polysomnographic recordings from 8 European sleep laboratories were analyzed. The histogram analysis was used to introduce quality control of all-night EEG recordings. RESULTS: It was found that the header information does not always provide the real saturation values of the recording equipment. The entropy measure was used for the quantitative analysis of the dynamic range of routinely used polysomnographic recorders. It was found that the recording equipment provides EEG data with entropy in the range of 8-11 bits. CONCLUSION: In the all-night sleep EEG were observed non-linearities. It is recommended that the equipment provide the saturation values in order to apply automated overflow detection.

Humans↗
PubMed1999

Sleep-related breathing disorder is an independent risk factor for systemic hypertension.

The exact influence of sleep-related breathing disorder (SRBD) on blood pressure control remains unknown. We investigated the influence of different degrees of SRBD on daytime blood pressure and its association to documented hypertension by examining 1,190 consecutive patients referred for diagnosis of SRBD. The protocol includes clinical interview, physical examination, office blood pressure measurement, cholesterol, and blood gas analysis. Unattended home monitoring of nocturnal breathing was performed for assessment of SRBD activity (respiratory disturbance index [RDI]). RDI was independently and linearly associated with systolic blood pressure (unstandardized coefficient [B] = 0.07 +/- 0.03, p = 0.03), diastolic blood pressure (B = 0.07 +/- 0.02, p = 0 < 0.001), and heart rate (B = 0.10 +/- 0.02, p < 0.001) at rest. The relative risk for hypertension (blood pressure >/= 160/95 mm Hg) increased with SRBD severity (odds ratio [OR], 4.15 for RDI >/= 40 versus < 5 [95% CI, 2.7 to 6.5]). This relative risk was also elevated in younger (</= 50 yr) compared with older patients (> 50 yr) (OR, 7.15 versus 2.70 for RDI >/= 40 versus < 5). These cross-sectional clinical data suggest a relationship between SRBD severity and systolic blood pressure, diastolic blood pressure, and heart rate after control for confounders such as body mass index (BMI), age, alcohol/nicotine consumption, cholesterol level, and daytime PO(2) and PCO(2). SRBD is an independent risk factor for systemic hypertension with an increased likelihood in subjects </= 50 yr of age.

Age Factors↗
PubMed1999

Arousal in patients with gastro-oesophageal reflux and sleep apnoea.

Nocturnal gastro-oesophageal reflux has been observed in patients with obstructive sleep apnoea (OSA). Negative intrathoracic pressure during apnoeas and arousal have been suggested as the underlying mechanisms. In order to evaluate this hypothesis, the coincidence and sequence in time of arousal, apnoea and reflux events were analysed. Fifteen patients with OSA or heavy snoring were studied by means of standard polysomnograpy with parallel recording of 24-h oesophageal pH. Reflux events during the day were present in all patients, five of whom had symptoms of reflux. In three of these and in five other patients, a total of 69 nocturnal reflux events were found. In 68 events, arousal was found with the reflux event. Only one reflux without arousal was found (sleep stage 2). Seventeen events occurred during wakefulness after sleep onset. The percentage of time with a pH of <4 during wakefulness after sleep onset was significantly higher than the percentage of time with a pH of <4 during total sleep time (p<0.05). In 37 of the 52 reflux events which occurred during sleep, either an apnoea or a hypopnoea was found prior to the event. The investigation of sequence in time did not prove a causal relation between respiratory events and reflux events. The results indicate that gastro-oesophageal reflux and obstructive sleep apnoea are two separate disorders, which both have a high prevalence in obese patients.

Adult↗
PubMed1998

Sleep fragmentation and daytime vigilance in patients with OSA treated by surgical maxillomandibular advancement compared to CPAP therapy.

Impaired vigilance is a frequent daytime complaint of patients with obstructive sleep apnoea (OSA). To date, continuous positive airway pressure (CPAP) is a well established therapy for OSA. Nevertheless, in patients with certain craniofacial characteristics, maxillomandibular advancement osteotomy (MMO) is a promising surgical treatment. Twenty-four male patients with OSA (pretreatment respiratory disturbance index (RDI) 59.3 SD +/- 24.1 events/h) participated in this investigation. The mean age was 42.7 +/- 10.7 years and the mean body mass index was 26.7 +/- 2.9 kg/m2. According to cephalometric evaluation, all patients had a narrow posterior airway space, more or less due to severe maxillary and mandibular retrognathia. All patients except two were treated first with CPAP for at least 3 months and afterwards by MMO. Two patients only tolerated a CPAP trial for 2 nights. Polysomnographic investigation and daytime vigilance were assessed before therapy, with CPAP therapy and 3 months after surgical treatment. Patients' reports of impaired daytime performance were confirmed by a pretreatment vigilance test using a 90-min, four-choice reaction-time test. The test was repeated with effective CPAP therapy and postoperatively. Daytime vigilance was increased with CPAP and after surgical treatment in a similar manner. Respiratory and polysomnographic patterns clearly improved, both with CPAP and after surgery, and showed significant changes compared to the pretreatment investigation. The RDI decreased significantly, both with CPAP (5.3 +/- 6.0) and postoperatively (5.6 +/- 9.6 events/h). The percentages of non-rapid eye movement Stage 1 (NREM 1) sleep showed a marked decrease (with CPAP 8.2 +/- 3.6% and after MMO 8.2 +/- 4.4% vs. 13.3 +/- 7.4% before treatment), whereas percentages of slow wave sleep increased significantly from 8.0 +/- 6.1% before therapy to 18.2 +/- 12.8 with CPAP and 14.4 +/- 7.3% after MMO. The number of awakenings per hour time in bed (TIB) was significantly reduced after surgery (2.8 +/- 1.3), compared to both preoperative investigation (baseline 4.2 +/- 2.0 and CPAP 3.4 +/- 1.5). Brief arousals per hour TIB were reduced to half with CPAP (19.3 +/- 20.0) and after MMO (19.7 +/- 13.6), compared to baseline (54.3 +/- 20.0). We conclude that the treatment of OSA by MMO in carefully selected cases has positive effects on sleep, respiration and daytime vigilance, which are comparable to CPAP therapy.

Adult↗
PubMed1998

Expiratory flow limitation and intrinsic positive end-expiratory pressure in obesity.

Breathing at very low lung volumes might be affected by decreased expiratory airflow and air trapping. Our purpose was to detect expiratory flow limitation (EFL) and, as a consequence, intrinsic positive end-expiratory pressure (PEEPi) in grossly obese subjects (OS). Eight OS with a mean body mass index (BMI) of 44 +/- 5 kg/m2 and six age-matched normal-weight control subjects (CS) were studied in different body positions. Negative expiratory pressure (NEP) was used to determine EFL. In contrast to CS, EFL was found in two of eight OS in the upright position and in seven of eight OS in the supine position. Dynamic PEEPi and mean transdiaphragmatic pressure (mean Pdi) were measured in all six CS and in six of eight OS. In OS, PEEPi increased from 0.14 +/- 0.06 (SD) kPa in the upright position to 0.41 +/- 0.11 kPa in the supine position (P < 0.05) and decreased to 0.20 +/- 0.08 kPa in the right lateral position (P < 0.05, compared with supine), whereas, in CS, PEEPi was significantly smaller (<0.05 kPa) in each position. In OS, mean Pdi in each position was significantly larger compared with CS. Mean Pdi increased from 1.02 +/- 0.32 kPa in the upright position to 1.26 +/- 0.17 kPa in the supine position (not significant) and decreased to 1. 06 +/- 0.26 kPa in the right lateral position (P < 0.05, compared with supine), whereas there were no significant changes in CS. We conclude that in OS 1) tidal breathing can be affected by EFL and PEEPi; 2) EFL and PEEPi are promoted by the supine posture; and 3) the increased diaphragmatic load in the supine position is, in part, related to PEEPi.

Adult↗
PubMed1998

Circadian reactions to nCPAP treatment.

To determine possible effects of apnea attacks on the spontaneous behavior of the circadian system (body temperature, sleeping behavior, vigilance), 11 patients with obstructive sleep apnea (OSA) were observed before therapy over a 24 h period under a special constant routine (bed-rest study) and again during therapy with nCPAP (nasal continuous positive airway pressure). Clinical indicators (polysomnographical, subjective sleep quality, etc.) indicated successful therapy. During the bed-rest study with nCPAP therapy, the 24 h amplitude of core temperature was found to be greater than the amplitude measured before therapy. Also, therapy decreased sleep disturbances at night and reduced daytime sleeping times. Consequently, the level of subjective vigilance was higher during the daytime during therapy. OSA attacks do not only impair sleep; they disturb the whole circadian system. This may also impair recuperation and sleep. Further research should test whether measurements of the spontaneous circadian system could have additional diagnostic value and whether the stabilization of the circadian system has therapeutic value.

Adult↗
PubMed1997

[Effect of noninvasive ventilation on work of breathing in obesity].

BACKGROUND: Noninvasive ventilation with nose- or face-masks has been increasingly used in the past. The objective of mechanical ventilation is in addition to improve gas exchange to reduce breathing work. While improvement on breathing work has been shown mainly on normal-weight patients with different respiratory diseases, there is no existing data about the effect of noninvasive ventilation on the breathing work of patients with massive obesity. PATIENTS AND METHODS: Assisted mask-ventilation with bilevel positive airway pressure (BiPAP) was carried out on 5 overweight control subjects (overweight controls), 7 overweight patients with obstructive sleep apnea (OSA), 6 patients with obesitas-hypoventilation syndrome (OHS), and 7 overweight patients with chronic obstructive lung disease (COLD). Inspiratory pressure assist (IPAP) was set to 12 or 16 cm H2O, exspiratory pressure (EPAP) was set to 5 cm H2O. All, subjects were massive overweight (body mass index [BMI] 42.2 +/- 5.8; range 31.8 to 55.4 kg/m2). Respiratory muscle activity was measured as esophageal pressure change (delta Pes) and transdiaphragmatic pressure change (delta Pdi) and calculated as pressure time integral. RESULTS: With noninvasive ventilation respiratory muscle activity was significantly (p < 0.05) reduced in all groups at least 40% compared to baseline values during spontaneous respiration. CONCLUSIONS: Noninvasive ventilation via face masks can efficiently reduce work of breathing in subjects with massive obesity.

Adult↗
PubMed1997

Influence of noninvasive positive pressure ventilation on inspiratory muscle activity in obese subjects.

Noninvasive positive pressure ventilation (NPPV) can improve ventilation in obese subjects during the postoperative period after abdominal surgery. Compared to nasal continuous positive airway pressure (nCPAP), NPPV was superior in correcting blood gas abnormalities both during the night-time and during the daytime in a subgroup of patients with the obesity hypoventilation syndrome (OHS). However, as it is unknown, if and to what extent NPPV can unload the respiratory muscles in the face of the increased impedance of the respiratory system in obesity, this is what was investigated. Eighteen obese subjects with a body mass index > or = 40 kg x m(-2) were investigated during the daytime, which included five healthy controls (simple obesity (SO)), seven patients with obstructive sleep apnoea (OSA) and six patients with the obesity hypoventilation syndrome (OHS). Assisted PPV was performed with bi-level positive airway pressure (BiPAP), applied via a face mask. Inspiratory positive airway pressure (IPAP) was set to 1.2 or 1.6 kPa and expiratory positive airway pressure (EPAP) was set to 0.5 kPa. Inspiratory muscle activity was measured as diaphragmatic pressure time product (PTPdi). Comparison of spontaneous breathing with BiPAP ventilation showed no significant difference in breathing pattern, although there was a tendency towards an increase in tidal volume (VT) in all three groups and a decrease in respiratory frequency (fR) in patients with OSA and OHS. End-tidal carbon dioxide (PET,CO2) with BiPAP was unchanged in SO and OSA, but was decreased in OHS. In contrast, inspiratory muscle activity was reduced by at least 40% in each group. This was indicated by a decrease in PTPdi with BiPAP 1.2/0.5 kPa from mean+/-SD 39+/-5 to 20+/-9 kPa x s (p<0.05) in SO, from 42+/-7 to 21+/-8 kPa x s (p<0.05) in OSA, and from 64+/-20 to 38+/-17 kPa x s (p<0.05) in OHS. With BiPAP 1.6/0.5 kPa, PTPdi was further reduced to 17+/-6 kPa x s in SO, and to 17+/-6 kPa x s in OSA, but not in OHS (40+/-22 kPa x s). We conclude that noninvasive assisted ventilation unloads the inspiratory muscles in patients with gross obesity.

Adult↗
PubMed1997

Effect of angiotensin converting enzyme inhibition [Cilazapril] on blood pressure recording in hypertensive obstructive sleep apneic patients.

We investigated the efficacy of an Angiotensin Converting Enzyme [ACE] inhibitor on daytime and night-time blood pressure in 55 male hypertensive patients with moderately severe to severe obstructive sleep apnea. We resolved to determine if treatment oriented towards the reduction of hypertension would be successful, despite persistent repetitive hypoxemia and sleep-disordered breathing. The study was a randomized, double-blind, single daily dose, placebo-controlled protocol, with 8 days drug intake (placebo or 2.5 mg Cilazapril) and monitoring on the final day of drug administration. Subjects underwent continuous 24-h arterial blood pressure monitoring during baseline and treatment conditions. Polysomnography was performed at night during the 24-h arterial monitoring period. Cilazapril (2.5 mg) lowered systolic, diastolic and mean blood pressure, despite persistence of repetitive obstructive apneas during sleep and the associated repetitive hypoxemia. The lowering of blood pressure occurred without a significant change in heart rate, and was noted during nocturnal sleep, performance testing and graded exercise.

Adult↗