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N Netzer

Publications and source records attributed to N Netzer.

At least 19 recordsLinked to original sources
PubMed2001

Overnight pulse oximetry for sleep-disordered breathing in adults: a review.

Pulse oximetry is a well-established tool routinely used in many settings of modern medicine to determine a patient's arterial oxygen saturation and heart rate. The decreasing size of pulse oximeters over recent years has broadened their spectrum of use. For diagnosis and treatment of sleep-disordered breathing, overnight pulse oximetry helps determine the severity of disease and is used as an economical means to detect sleep apnea. In this article, we outline the clinical utility and economical benefit of overnight pulse oximetry in sleep and breathing disorders in adults and highlight the controversies regarding its limitations as presented in published studies.

Adult↗
PubMed1998

Blood flow of the middle cerebral artery with sleep-disordered breathing: correlation with obstructive hypopneas.

BACKGROUND AND PURPOSE: Epidemiological data link heavy snoring to an increased risk for stroke, an association often ascribed to hypertension and/or sleep apnea. The aim of this study was to determine whether obstructive hypopneas, central apneas, or obstructive apneas during sleep alter blood flow of the middle cerebral artery (MCA). METHODS: Doppler sonography of the MCA was performed in conjunction with nightly polysomnography in 11 men and one woman. RESULTS: A significant decline in blood flow occurred in 76% (169/223) of obstructive hypopneas and in 80% (98/123) of obstructive apneas, compared with only 14% (13/96) of central apneas (P<.0001). While duration of events was not significantly different, MCA blood flow reductions were associated only with the duration of the obstructive hypopneas (P< or =.01) and not with the duration of central (P=.17) or obstructive (P=.07) apneas. The magnitude of fall in arterial oxygen saturation from baseline correlated with a reduced blood flow with obstructive hypopneas but not with obstructive or central apneas. CONCLUSIONS: With obstructive hypopneas and obstructive apneas, MCA blood flow is more often decreased in comparison to central apneas. MCA blood flow reductions occur with longer obstructive hypopneas and with those hypopneas with greater falls in oxygen saturation. These observations indicate pathophysiology relevant to an increased risk for stroke in heavy snorers and patients with obstructive hypopneas and apneas.

Adult↗
PubMed1997

Monitoring high-intensity endurance training using neuromuscular excitability to recognize overtraining.

The minimal rectangular current pulse that produces a single contraction of reference muscles at different pulse durations has been recommended as a marker of the neuromuscular excitability (NME) of skeletal muscles. NME is improved in well-trained, non-fatigued endurance athletes and deteriorates after prolonged heavy exercise and high-volume overtraining. The hypothesis was tested that a deterioration in NME also indicates an early stage in the overtraining process during high-intensity endurance training. Six subjects participated for 40-60 min per day in a 6-week, 6-days-per-week, intensive, steady-state and interval training program using a cycle ergometer. Training was stopped each day on volitional exhaustion. On day 7 of each week training was of low intensity for about 30-40 min. Submaximum and maximum power output were significantly increased after 3 weeks, but there was no further improvement, rather a deterioration after week 6 compared to week 3. Even after 2 weeks of regeneration no supercompensation was evident, rather a decrease in maximum power output. NME was slightly improved after 3 weeks, but deteriorated after 6 weeks, and was again normalized after 2 weeks of regeneration. The discrepancy between normalization of NME and still-deteriorated performance ability after 2 weeks of regeneration reflects additional significant, and probably central mechanisms that explain persistent performance incompetence. Deterioration in NME may indicate an early stage in the overtraining process during high-volume as well as high-intensity endurance overtraining, but normalization does not necessarily indicate sufficient regeneration.

Adult↗
PubMed1997

Training and overtraining: an overview and experimental results in endurance sports.

Overtraining can be defined as "training-competition > > recovery imbalance", that is assumed to result in glycogen deficit, catabolic > anabolic imbalance, neuroendocrine imbalance, amino acid imbalance, and autonomic imbalance. Additional non-training stress factors and monotony of training exacerbate the risk of a resulting overtraining syndrome. Short-term overtraining called overreaching which can be seen as a normal part of athletic training, must be distinguished from long-term overtraining that can lead to a state described as burnout, staleness or overtraining syndrome. Persistent performance incompetence, persistent high fatigue ratings, altered mood state, increased rate of infections, and suppressed reproductive function have been described as key findings in overtraining syndrome. An increased risk of overtraining syndrome may be expected around 3 weeks of intensified/prolonged endurance training at a high training load level. Heavy training loads may apparently be tolerated for extensive periods of time if athletes take a rest day every week and use alternating hard and easy days of training. Persistent performance incompetence and high fatigue ratings may depend on impaired or inhibited transmission of ergotropic (catabolic) signals to target organs, such as: (I) decreased neuromuscular excitability, (II) inhibition of alpha-motoneuron activity (hypothetic), (III) decreased adrenal sensitivity to ACTH (cortisol release) and increased pituitary sensitivity to GHRH (GH release) resulting in a counter-regulatory shift to a more anabolic endocrine responsibility, (IV) decreased beta-adrenoreceptor density (sensitivity to catecholamines), (V) decreased intrinsic sympathetic activity, and (VI) intracellular protective mechanisms such as increased synthesis of heat-shock proteins (HSP 70) represent a complex strategy against an overload-dependent cellular damage.

Adrenal Glands↗
PubMed1997

[Sleep and respiration at an altitude of 6,400 m (Aconcagua, Argentina].

UNLABELLED: Persons at extreme altitudes are known to experience disturbances in the regulation of ventilation and sleep structure. However, except for simulated studies using the decompression chamber, only single events of sleep or ventilation were measured so far in field studies up to an altitude of 5800 m. Modifying a portable sleep lab (Vitalog HMS 5000), we were able to conduct 7 channel polygraphy on our ascent to the Aconcagua up to an altitude of 6400 m. METHODS: In 6 climbers (age 38-62 y, 1 f, 6 m), ECG, EOG, SaO2, chest and abdominal movements, breathing and snoring sounds, body position, nasal and oral airflow were measured 4 weeks prior to the expedition at an altitude of 500 m, at base camp (4200 m) and in 3 climbers at 6400 m (2nd base camp) at the Aconcagua mountain. All participants had a repeat study at 500 m altitude 4 weeks after the expedition. RESULTS: The total number of obstructive apnoeas and hypopnoeas (OA/H) at night increased at an altitude of 4200 m in the mean of all 6 climbers from 36 to 67.7 compared to 500 m altitude, Central Apneas and Cheyne stokes (CA/CS) increased from 6.7 to 45.2. At 6400 m altitude the OA/H fell to 3 and 4 respectively in 2 climbers and CA to 1 and 2 respectively. In one climber, suffering from recurrent snoring with oxygen desaturation at 500 m altitude level, the number of OA/H and CA/CS increased further to 201 and 322, respectively, at 6400 m. Total sleep time including the REM position increased in all 6 climbers by 10% at base camp in comparison to an altitude of 500 m. Whereas the total sleep time remained constant in the 3 climbers at 6400 m altitude, the REM position declined by 10% in comparison to base camp (4200 m). However, significant fluctuations between individuals were noticed. CONCLUSION: Although significant alterations in sleep and breathing are noticeable at altitudes above 300 m, the respiratory drive in healthy subjects provides for a regular ventilation at high frequency at the extreme altitude above 6000 m. Sleep-related breathing disturbances at low altitude appear to be amplified at high altitudes.

Adult↗
PubMed1997

[Physical training of patients with sleep apnea].

PURPOSE: It is a common question of sleep apnoea patients in the sleep lab whether they stand a chance to decrease the symptoms and severity of their disease by physical exercise. As far as we know, there is no data about this specific question until now, even though this has been subject to speculation. A few studies, however, report on an improvement of the respiratory drive (and chemoreceptor sensitivity) after physical exercise in athletes. The aim of this study was to prove whether physical exercise in sleep apnoea patients could improve the symptoms of their disease in an open trial. METHODS: 11 Patients with mild to severe sleep apnoea syndrome (1 f, 10 m, mean age 53.8x) took part in a 6-month period of physical exercise twice a week 2 h each time under the instructions of physical therapists. Before and after the 6mo period a full PSG without CPAP or BIPAP, a bicycle exercise test with lactate profile, echocardiography, blood test, and body weight and body height measurement was performed. Statistical analysis was done using Wilcoxon ranked test and multiple regression analysis. RESULTS: There was no significant bodyweight reduction in all patients after the 6mo period of physical training, no significant difference in either basal SaO2 nor mean SaO2 and no significant improvement in physical status by the p at 4 mmol lactate on the lactate profile. Echocardiographic changes were not found; there was no significant change in the blood pressure profiles during the bicycle test. No cardiopulmonary problems including exercise-induced high blood pressure were reported during the training period. There was, however, a significant decrease of the RDI (p < 0.05), but no significant change in the REM-sleep % of total sleep time (TST) and the TST itself. CONCLUSIONS: There was an improvement of the sleep apnoea syndrome correlated to a decrease of the RDI in the studied patient population due to a possible increase in the respiratory drive or a stabilised muscle tone ine the upper airways after physical exercise, as reported by other authors, because weight reduction could not be the reason in our patients. Our trial showed that the exercise does not increase the severity of symptoms of sleep apnoea by changing the REM/non REM ratio or for any other reasons. A physical training programme for sleep apnoea patients as an additional treatment should therefore be considered.

Adult↗
PubMed1997

[Technical differences in various CPAP and BiLevel CPAP devices].

PURPOSE: Since the first presentations of CPAP by Sullivan 1983 und BiPAP by Sanders 1990 as a successful treatment in obstructive sleep apnoea syndrome, many CPAP and BiLevel-CPAP devices have been developed by several companies around the world. Although all devices work on the same principle of continuous positive airway pressure delivered through nasal or facemasks, there are, however, significant technical differences between these devices, mainly due to different size and different maximum speed of the turbines. As far as we know, the only study concerning this technical difference in the devices was conducted by Raschke in 1995, who found significant differences in the pressure stability of the devices using a very complicated measurement model on volunteers who were breathing on the different devices. We intended to study the technical differences of the devices using a more simple technique in static conditions, but with very exact measurement. METHODS: We measured pressure stability on different inspiration flows and different pressure levels of 8 CPAP's and 4 BiLevel-CPAP's under static conditions using the "Höntzsch Exact ASD-G Messrohr ms 20201-18" flow-measurement device and the "Thommen HM 18.0020.A" pressure-measurement devixe. We measured the noise emission by these devices at different frequency levels using the "Brüel and Kjer Dual Channel Real Time Frequency Analyzer", and measured the speed to reach the adjusted pressure level with the "Multimeter Phillips PM 2518X" and "Oszillograph Phillips PM3350" using the voltage change due to different working of the electric engines at different turbine speeds. We also investigated the different construction of the devices by opening them and analysing the materials used in the devices. RESULTS: The real pressure levels at an adjusted pressure of 10 mbar and at an inspiration flow of 1 Liter/sec range from 8.7 mbar to 15.6 mbar in CPAP's and from 9 mbar to 9.7 mbar in BiLevel devices. At higher inspiration flows the differences are larger, at lower flows smaller. The maximum noise emission in the 10 Hhz spectrum at a distance of 100 cm from the device at an adjusted pressure level of 10 mbar ranged from 29.6 dB to 39.9 dB in CPAP's and 30.4 dB to 42.2 dB in BiLevel-CPAP's. The time to reach an adjusted pressure level of 10 mbar after closing the airway of the device ranged from 0.26 to 0.66 sec in CPAP's and from 0.46 to 0.80 sec in BiLevel devices. CONCLUSION: There are significant technical differences in the different CPAP and BiLevel devices due to different construction of the turbines and electrical engines of these devices. This should be considered when prescribing a device for a sleep apnoea patient. Not every device is suitable for every patient, and quality differences should be considered by all persons involved in the production and prescribing process.

Airway Resistance↗
PubMed1997

[The clinical use of an individually fitted nasal mask ("Freiburg Respiratory Mask") within the scope of a case report of controlled BiPAP ventilation].

PURPOSE: Noninvasive mechanical ventilation with nasal or face mask using either BiPAP or IPPV (intermittent positive pressure ventilation) modes is meanwhile the standard type of mechanical ventilation instead of endotracheal intubation or tracheostomy in many patients with chronic and acute respiratory failure. However, problems occur very often in noninvasive mechanical ventilation due to mask problems with leakage of air out of the mask or erasions and necrosis of the skin by constant pressure through the mask frame. Hence, some clinical work groups developed customized molded masks mostly in cooperation with dentistry labs. These masks, however, are often very expensive and take several weeks to be manufactured. Our aim was to develop an inexpensive (less than 600 USS) and easy-(in one day)-to-produce customized nasal mask, the so-called "Freiburg nasal mask". We wish to show by a case report the clinical efficacy of this customized mask in severe respiratory failure. CASE AND METHOD: A 52 y old women (BMI 19, nonsmoker) suffering from a severe hypercapnic respiratory failure (PCO2 over 100 mmHg) due to a severe kyphoscoliosis as result of a postpoliosyndrome and already on controlled nasal BiPAP with a standard respironics nasal mask, was referred to our clinic as an emergency case. After not succeeding to normalise blood gases and clinical status of the patient in mechanical ventilation on BiPAP mode and additional 2 lit/min of oxygen insufflation via the mask (patient was refusing invasive ventilation) for 12 days due to mask leakage and mask discomfort we made a mould of the patients face. Using this mould in a vacuum process the two EVA polymers Erkoflex and Erkodent were combined to build up the customized mask over the mould on the same day. In the first three days using the customized mask in the patient PCO2 decreased below 70 mmHg, on the 8th day after starting with the customized mask, blood gases almost normalised. Patient compliance in using the BiPAP device increased from 8 h a day to 16 h a day. CONCLUSION: This case shows that sometimes due to leakage of air in standard nasal masks noninvasive mechanical ventilation may fail in patients with severe respiratory failure. Therefore, in these patients customized moulded nasal or face masks should be used instead of standard masks. We think that the Freiburg nasal mask is an example of an easy to produce and nonexpensive customized mask and may be used in such patients, as this case report shows.

Equipment Design↗
PubMed1996

"Open-word" questions: an effective tool in gauging education of patients with COPD.

For evaluation of the success of patient education in patients suffering from chronic obstructive pulmonary disease (COPD), multiple-choice tests are commonly used. Using these tests, however, only passive knowledge can be examined. We attempted to evaluate, with the help of "open-word" questions and keywords, as used in examinations of students of arts, the active knowledge achieved by 12 patients who had been participants in one of our indepth courses of patient education. The results of this "open-word" test were compared with the results of multiple-choice tests with 91 participants. The average results of the "open-word" tests, with 36% correct answers, were remarkably worse than those of the multiple-choice tests with 80% correct answers. In our opinion, this allows the conclusion that the active knowledge attained in the patient-education courses is clearly lower than the passive knowledge achieved, and that, on the other hand, multiple-choice tests cannot be considered as the exclusive method to evaluate the success of patient education because their questions may quite often prove to be too easy.

Female↗
PubMed1995

[Nasal BiPAP (bilevel positive airway pressure) respiration with controlled respiratory mode in neuromuscular diseases and severe kyphoscoliosis].

The BiPAP-System is a useful ventilatory support for patients with severe sleep apnea and need for high inspiratory pressure. Using the BiPAP as a full ventilatory support is new due to the recent addition of a timed control modus and individual control of inspiratory time. We used the new BiPAP ST-System in one young men with Duchenne-disease, one man with heredo ataxia (Friedreich), one women with spinal muscular atrophy, one man with central sleep apnea due to brainstem infarction as well as two women and one men with severe kyphoscoliosis. All patients had a significant hypoventilation and hypoxemia at night, which was documented by polysomnography. Mechanical ventilation at night with nasal BiPAP increased the baseline oxygen saturation (SaO2) by an average of 11.9% in all seven patients. The frequency of desaturations below 90% diminished by an average of 81%. The lowest SaO2 measured increased by 28% in all seven patients combined. Rhinitis due to the dryness of the inspired air were noticed in only two patients. Two other patients needed adaptation to the customized mask. The nasal BiPAP-System using the T-mode is a useful device to support ventilation at night and thus it could replace ventilatory support by the IPPV-mode in many patients.

Adult↗
PubMed1993

[Efficiency of portable sleep apnea screening instruments].

Diagnosis of a sleep apnoea syndrome in severely snoring patients with diurnal sleepiness is growing in importance in the consulting rooms of general practitioners, internists, ENT specialists and pneumologists. However, time and cost reasons limit the diagnostic procedures conducted by practitioners to outpatient screening. Two different systems are presently available in Germany. The MESAM system (Madaus, Freiburg) records by means of a microphone and various electrodes the oxygen saturation, heart rate, snoring and sleeping position of the patient. The Apnoe-Check System (Medanz, Starnberg) determines the nasal and oral respiratory flow by means of a mask fitted with thermistors. Evaluation is accomplished in the case of MESAM via a conventional personal computer whereas with the Apnoea Check System the apnoeas and their duration can be read off direct from a writer. The cost ratio of these systems is approximately 3:1 (MESAM:Apnoea Check). Wie compared both systems by parallel measurements on 19 female and male patients and controlled the results obtained by measurements with a CO2 infrared absorption spectrometer in our sleep lab. A total of 3201 nocturnal events were recorded via MESAM and 1488 via the Apnoe-Check System. The highest number of apneas was recorded by MESAM in a patient with severe sleep apnea syndrome, namely, 546 apnoeas in one night. The lowest number of apnea events was experienced by a healthy male with 33 apneas in a night. With the Apnoe Check the maximum of nocturnal events was 255, the minimum being 8 events in one patient. In 64.6% of all nocturnal events there was time congruence for both systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian Rhythm↗