PubMed Health⌕ Search

Biomedical subjects

L Grote

Publications and source records attributed to L Grote.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Work of breathing in noninvasive proportional assist ventilation in patients with respiratory insufficiency].

BACKGROUND: The aim of the present study was to evaluate if Proportional Assist Ventilation (PAV), when applied noninvasively via face mask, can reduce ventilatory effort in patients with respiratory failure. We present preliminary results of an ongoing study. PATIENTS AND METHODS: In 5 patients with respiratory failure due to different underlying disorders (pulmonary fibrosis, bilateral diaphragm paralysis, COPD) we compared the transdiaphragmal pressure-time integral. PTdi (integral off Pdi dt) after 15 minutes of noninvasive PAV to the baseline values without ventilatory support. RESULTS AND CONCLUSION: Four patients showed reduction of PTdi to various extend. One patient who presented low diaphragmal activity at baseline due to diaphragmal paralysis showed a slight increase in PTdi during ventilation. Mean PTdi decreased by 26.7%. PaCO2 in the 5 patients showed no significant change after 15 minutes of ventilation, thus indicating that with noninvasive PAV patients can maintain constant ventilation with reduced effort.

Aged↗
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↗
PubMed1997

[Cardiorespiratory coupling in obstructive sleep apnea (OSA)].

Even if different mechanisms of various interactions during sleep are known, it is still unsolved by which mechanisms physiological reactions during sleep may start a pathophysiological course. Hypoxia, Hypercapnia and repetitive sympathetic elevations are well known elements in the control of the arterial resistance. Furthermore investigations in patients with sleep apnea showed changes of the pulsatile secretion pattern within the renin-angiotensin-system and the antinatriuretic peptides. These changes were reversible under nasal CPAP-therapy, nycturia as a frequent symptom disappeared. Nevertheless neither hypoxia nor intrathoracic pressure changes nor the arousals can assert the longterm influence on the blood pressure alone, a multifactorial confluence must be assumed. Further it is unclear how a tonic increase of the arterial blood pressure may occur in dependence of the REM- and NREM-sleep cycle changes as well as during daytime. First investigations in sleeping man seem to indicate, that a disturbance of the physiological coupling of breathing and circulation may present a pathogenetic element. Finally it remains open, whether the changes of the cardiorespiratory coupling during sleep of control persons and of patients with OSA are comparable, and whether they may be procured for an explanation of the pathogenesis of arterial and pulmonary hypertension. Further investigations in the control mechanisms of breathing and circulation related to the circuits of chemo- and baroreception, thresholds during wakefulness and sleep may be of decisive help to process the question, to what extent clinical states find a correlate in a disturbed cardiorespiratory coupling and, much more significantly, whether a disturbance in the physiological cardiorespiratory coupling appears already in early states of a disease. Sleep with ist complex physiology as well as with its characteristic pathophysiological phenomenon of sleep related breathing disorders has opened a new interdisciplinary field where tools like the polysomnography and electronic data analysis are used by physiologists, pathophysiologists as well as by physicians.

Adult↗
PubMed1997

[Respiratory function diagnosis during sleep: possibilities and limitations].

Diagnosis of the respiratory function during sleep is based on a continuous recording of all necessary signals. These are basically respiratory flow, respiratory effort and blood gases. In addition, sleep stages, body position and cardiovascular function have to be monitored to distinguish the different forms of sleep related breathing disorders as there are obstructive, mixed and central apnea and hypoventilation. The main evaluation is a simple counting of events and the calculation of an index related to total sleep time. These indices are of limited value because all information about the duration of the events is lost and about the severity which depends on the actual blood gas values. A computer assisted evaluation of respiration can overcome these limitations and allows to evaluate sleep stage dependencies in addition. Based on the duration of respiratory events only it was possible to distinguish patient groups which also provided different blood gas values at daytime. Determination of the critical closing pressure of the upper airways during sleep can help to quantify effects of body weight loss and other therapeutic interventions beside ventilation therapy in patients with sleep related breathing disorders. Quantitative characterisation of respiration during sleep is limited by the fact that most methods available induce changes in sleep or respiration itself. A study on healthy subjects proved an increased number of arousals during cardiorespiratory polysomnography. Therefore the added value obtained by quantitative methodology (pneumotachograph and esophageal pressure) must be weighted against non-invasive technology (inductive plethysmography). Non-invasive methods can provide comprehensive information about the respiratory function, especially if extensive computer-assisted evaluation is used. These evaluations still need further improvements. Nevertheless they can help to clarify the different types of respiratory regulation present in NREM-, REM-sleep and awake state.

Carbon Dioxide↗
PubMed1997

[Carotid baroreflex in sleep apnea patients].

15 patients (11 male, 9 female) with obstructive sleep apnoea syndrome (OSAS) and 10 healthy age- and weight-matched control subjects volunteered to participate in the study to test circadian variations of cardiac response to activation of carotid baroreceptors. Activation of carotid baroreceptors was evoked by applying a negative pressure to both left and right carotid sinus regions, using two small separate neck-suction capsules. All experiments were performed under standard conditions every two hours. The cardiac response to carotid baroreceptors activation was significantly reduced in OSAS Patients, to a greater degree in the group of hypertensive patients. A characteristic circadian rhythm of baroreceptor reactivity persisted in all OSAS patients. Thus, OSAS patients constitute a high-risk group for the development of cardiovascular diseases and pathological course of blood pressure during daytime.

Blood Pressure↗
PubMed1997

[Use of discontinuous long-term blood pressure measurement (Spacelabs 90207) in patients with sleep apnea--a comparison with intra-arterial data].

Circadian blood pressure (BP) profile is an important determinant of cardiovascular risk. Patients with Sleep-Related Breathing Disorders (SRBD) often suffer from arterial hypertension and an altered circadian blood pressure profile. The aim of this study was to compare intraarterial blood pressure recordings with DBPR (Discontinuous Blood Pressure Recorder using Spacelabs 90207) in 20 patients with mild to moderate arterial hypertension and mild to moderate SRBD. Our results of overnight measurements show that the mean arterial pressure seems to be the most reliable value (mean difference Spacelabs-Part: +1.7 mmHg). In contrast, the systolic BP was systematically underestimated (mean: -17.5 mmHg) while the diastolic value was systematically overestimated (mean: +9.3 mmHg) by Spacelabs. Our data show that neither systolic nor diastolic BP from the Spacelabs measurement reflected the real cardiovascular load. Since the mean arterial pressure proved to be the most reliable value, this value should be used to distinguish between dipper and non-dipper in circadian BP profiles. Further, reliable noninvasive continuous measurement of the BP is required to assess the real vascular load in patients with SRBD during the night.

Adult↗
PubMed1997

[Increased daytime tiredness, nocturnal hypertension and sleep apnea: studies in rural general practice].

Studies in a Rural General Practice: Sleep-Related Breathing Disorders (SRBD) and altered circadian blood pressure profile are related to increased cardiovascular risk. We investigated the prevalence and coincidence of both diseases in male patients from a general practice in a small community of 2500 people. Out of 409 selected patients (using a questionnaire regarding symptoms and findings of SRBD), 185 were monitored in an outpatient setting with an apnoea-screening system Mesam IV. Ambulatory blood pressure monitoring (Spacelabs 90207). Holter-ECG and actigraphy were also measured. Sixty patients had a Respiratory Disturbance Index (RDI) > 10. An indication for further sleep studies was seen in 40 patients; 36.5% of daytime hypertensives were "Non-Dipper", and 47.6% of normotensives were also "Non-Dipper". Excessive daytime sleepiness (EDS) is an important symptom of SRBD, and in this investigation we noticed a large number of patients without this symptom suffering from relevant SRBD. Therefore, absence of EDS alone is not indicative for the use of ambulatory monitoring.

Adult↗
PubMed1996

The effect of triazolam and flunitrazepam--two benzodiazepines with different half-lives--on breathing during sleep.

We performed a double-blind single-dose placebo/hypnotics crossover study randomized within groups to test the potential problems that a group of normal subjects, including subjects who snore, may face using hypnotic medications. Two benzodiazepine hypnotics--triazolam, 0.25 mg, and flunitrazepam, 2 mg tablets--were considered. Subjects were monitored with nocturnal polysomnography, including esophageal pressure (Pes) monitoring as a measure of respiratory efforts, and were given daytime performance tests. Results were analyzed for the total nocturnal sleep period and also by thirds of the night in consideration of the different half-lives of the studied drugs. Three specific respiratory variables were evaluated: mean breathing frequency for selected unit of time, "Delta Pes" (esophageal pressure at peak end-expiration minus Pes at peak end-inspiration) expressed in cm H2O, and the ratio of Delta Pes/Delta TI (inspiratory time), taken as an index of respiratory drive calculated for each respiratory cycle. There was no significant increase in either the respiratory disturbance index or the oxygen desaturation index (number of drops in arterial oxygen saturation of 4% or more per hour of sleep, as measured by pulse oximetry). There was a significant increase in mean breathing frequency with flunitrazepam compared with placebo, as well as a significantly larger percentage of time during sleep with Delta Pes above 10 cm H2O (taken as a cutoff point for normal respiratory effort) with both triazolam and flunitrazepam compared with placebo. These respiratory changes, even if significant, were minor but may become a liability in association with specific abnormalities.

Adult↗
PubMed1996

Assessment of the nocturnal blood pressure relative to sleep stages in patients with obstructive sleep apnea.

To determine the mean blood pressure relative to sleep stages, two nocturnal cardiorespiratory polysomnographs were recorded in 60 male patients with hypertension and obstructive sleep apnea (OSA). The mean age was 50.2 years, the BMI 32.0 kg/m2, the respiratory disturbance index (RDI) 44, and the blood pressure by the WHO protocol 158/98 mm Hg. A new evaluation program was used to determine the invasively measured mean arterial pressure (mean +/- SEM) and heart rate (mean +/- SEM) during sleep (mean total sleep time 361 +/- 48 min) referred to sleep stages 1 (99.5 +/- 1.5 mm Hg/67.6 +/- 1.1 bpm), 2 (98.7 +/- 1.6 mm Hg/66.6 +/- 1.1 bpm), 3 (97.6 +/- 1.8 mm Hg/67.4 +/- 1.3 bpm), and 4 (97.6 +/- 2.2 mm Hg/66.3 +/- 1.6 bpm) and to REM sleep (103.3 +/- 1.7 mm Hg/68 +/- 1.2 bpm) as 1 s mean values and to compare them with the waking state (98.3 +/- 1.6 mm Hg/83.6 +/- 1.1 bpm). There was no physiological fall in blood pressure in patients with pronounced OSA. Sleep-stage-specific analysis of invasive continuous blood pressure signals is the gold standard. The sleep structure is disturbed less than with other methods.

Adult↗
PubMed1996

[Spectral analysis of blood pressure in patients with sleep related respiratory disorders].

Spectral analysis is a helpful tool to investigate the interaction of blood pressure, respiration and sleep (6). The analysis of systolic pressure is most suitable for the documentation of compressed spectral arrays, since there are less disturbances than from the heart rate. The method used in this study allows the discrimination and quantitative evaluation of periodic blood pressure oscillations associated with apneic and breathing phases. It could be shown that the amplitude of the pulsus paradoxus increases during episodes of obstructive snoring. Heavy snore showed rather stable respiratory frequencies during the whole night which was not found that distinctly in patients with obstructive sleep apnea. The parallel analysis of blood pressure variations and sleep phases revealed different mechanisms in the regulation of REM- and non-REM sleep which transfer sleep related breathing disorders from a periodic pattern in a nonperiodic one and hereby influence at least the regulation of heart rate and blood pressure.

Adult↗
PubMed1996

Electrical stimulation of upper airway musculature.

Investigators have postulated that pharyngeal collapse during sleep in patients with obstructive sleep apnea (OSA) may be alleviated by stimulating the genioglossus. The effect of electrical stimulation (ES) of the genioglossus on pharyngeal patency was examined in an isolated feline upper airway preparation and in apneic humans during sleep. We found that stimulation of the genioglossus (n = 8) and of the hypoglossal nerve (n = 1) increased maximum airflow through the isolated feline upper airway in humans during sleep. Additional findings in the isolated feline upper airway suggest that such increases in airflow were due to decreases in pharyngeal collapsibility. The evidence suggests that improvements in airflow dynamics with electrical stimulation are due to selective recruitment of the genioglossus, rather than due to nonspecific activation of the pharyngeal musculature or arousal from sleep. The implications of these results for future therapy with ES are discussed.

Animals↗
PubMed1995

REM-sleep-hypertension in obstructive sleep apnea.

Previous investigations involving continuous blood pressure (BP) monitoring have shown an important alteration of the 24-hour BP profile in patients with obstructive sleep apnea syndrome (OSAS). We investigated the impact of REM sleep on the 24-hour BP cycle in 16 severe OSAS male patients (mean respiratory disturbance index = 66 +/- 16 events/hour of sleep), with hypertension (mean BP 162 +/- 21/105 +/- 11 mmHg World Health Organization (WHO) protocol). Two successive nights of polysomnography were performed, and arterial BP was monitored continuously during the second 24-hour period after brachial artery cannulation. During the daytime, subjects were kept awake and supine. At 3 p.m. BP was continuously monitored during quiet supine wakefulness for 20 minutes. Systolic, diastolic and mean BP and heart rate (HR) were analyzed and tabulated in mean values of 5 minute segments. Sleep/wake information were correlated with cardiovascular variables. Each uninterrupted REM sleep period was identified and comparison between the period of quiet supine wakefulness and REM sleep HR and BP values was performed. 8 OSAS patients presented a normal drop of the mean arterial BP during the nocturnal REM sleep periods compared to quiet supine wakefulness (mean value = -10.8 +/- 7.3 mmHg) ("dippers") while the other 8 subjects ("REM sleep non dippers"), revealed an elevated mean arterial BP during REM sleep (mean value = 18.9 +/- 10.9 mm Hg). The absence of the normal circadian BP dip seen during the nocturnal sleep period is considered as an indication of vascular risk. The REM sleep non dipping may play a role in this risk.

Adult↗
PubMed1995

Wet autoclave pretreatment for immunohistochemical demonstration of oestrogen receptors in routinely processed breast carcinoma tissue.

The immunohistochemical demonstration of oestrogen receptor (OR) was performed on 32 randomly selected and routinely processed breast carcinomas after wet autoclave pretreatment of sections. The autoclave method was compared to the OR status found on frozen sections as well as to alternative pretreatment methods such as enzymatic predigestion and microwave irradiation. Using four different monoclonal antibody clones (H222, LH1, CC4-5, 1D5.26), the OR status was evaluated for each of the various pretreatment methods applied. All cases with a high OR content on frozen sections (n = 11) also showed a high OR status on wet autoclave-pretreated paraffin tissues using antibody clones 1D5.26 and CC4-5; in cases with low OR content on frozen sections, no false-negative cases were recorded using only the antibody 1D5.26 neither after wet autoclave nor microwave pretreatment. In addition, with this antibody, OR was detectable after autoclave pretreatment in two cases which were considered to be OR-negative even on frozen sections. When the primary antibody was omitted, no false-positive cases were observed after wet autoclave pretreatment. Thus, in our hands, wet autoclave pretreatment, in combination with the antibody 1D5.26, offers a highly sensitive method for the immunohistochemical demonstration of OR in routinely formalin-fixed, paraffin-embedded sections of breast carcinomas.

Antibodies, Monoclonal↗