Thorsten Schäfer

Adaptive servo-ventilation in patients with coexisting obstructive sleep apnoea/hypopnoea and Cheyne-Stokes respiration.

OBJECTIVEnThe coexistence of obstructive (OSAS) and central sleep apnoea (CSA) and Cheyne-Stokes respiration (CSR) is common in patients with and without underlying heart diseases. CPAP has been shown to improve CSA/CSR by about 50%, but recent data suggest maximal suppression of CSA is important in improving clinical outcomes in heart failure patients. Adaptive servo-ventilation (ASV) effectively suppresses CSA/CSR in heart failure, but only few trials have considered patients with coexisting OSAS and CSA/CSR.nnnMETHODSnProspective, observational pilot study to evaluate the efficacy of a new ASV device, the BiPAP AutoSV, in 10 male consecutive patients with coexisting OSAS and CSA/CSR with and without heart failure over eight weeks. Six had stable heart failure.nnnMEASUREMENTS AND RESULTSnThe total AHI improved from 48.9+/-20.6/h to 8.7+/-7.4, the obstructive AHI from 15.8+/-16.2/h to 2.6+/-2.5/h and the central AHI from 33.1+/-10.8/h to 6.1+/-5.9/h (all p<0.01). Furthermore, there was a significant improvement in sleep profile and respiratory related arousals. The six patients with cardiovascular disease, including three with congestive heart failure, showed similar improvements in all parameters.nnnCONCLUSIONSnBiPAP AutoSV was effective in reducing all types of respiratory disturbances in coexisting OSAS and CSA/CSR with and without heart failure. Further studies comparing the long-term clinical efficacy of this device against CPAP are warranted.

Combined adaptive servo-ventilation and automatic positive airway pressure (anticyclic modulated ventilation) in co-existing obstructive and central sleep apnea syndrome and periodic breathing

BACKGROUNDnThe co-existence of obstructive and central sleep apnea/hypopnea syndrome (OSAS) and periodic breathing is common in patients with and without underlying heart diseases. While automatic continuous positive airway pressure (APAP) has proven to effectively treat OSAS, the adaptive servo-ventilation (ASV) sufficiently improves periodic breathing. This is the first trial on a device which combines both treatment modes.nnnMETHODSnPilot study on a two-week treatment in patients with co-existing obstructive and central and periodic breathing disturbances during sleep. Twelve consecutive patients (9 male, 3 female, age 56.9+/-10.6 years, BMI 32.4+/-5.5 kg/m(2)) were treated with a new algorithm which combines APAP and ASV (also called anticyclic modulated ventilation (ACMV), SOMNOventCR, Weinmann, Hamburg, Germany). Seven suffered from arterial hypertension, coronary heart disease and mitral regurgitation, none from congestive heart failure.nnnRESULTSnThe total apnea-hypopnea index (AHI) improved from 43.8+/-24.0/h to 2.1+/-2.4 (p<0.01), the obstructive AHI from 12.8+/-14.3/h to 0.3+/-0.6/h (p<0.01) and the central AHI from 31.0+/-17.5/h to 1.7+/-2.0/h (p<0.01). Moreover, there was a significant improvement in the total number of arousals, respiratory induced arousals, oxygen saturation and sleep profile.nnnCONCLUSIONnThe algorithm combining automatic continuous positive airway pressure (CPAP) and ASV normalizes all types of co-existing obstructive and central apnea/hypopnea and periodic breathing.

Breathing and locomotion in patients with Parkinson's disease

Abstract. The phase relationship between respiration and locomotion was examined in ten patients with Parkinsons disease (PD, mean age 65, range 51–79xa0years) and in six healthy subjects (mean age 63, range 58–68xa0years). Locomotion was measured by means of pressure sensors attached below the subjects feet. Respiration was measured using respiratory inductive plethysmography. The data were recorded with a battery-driven portable device. We determined the coordination degree as the portion of steps which occurred within 12/50 bins of the respiratory cycle. The mean degree of coordination of PD patients was 45.0%±11.9%, for the healthy subjects 85.1%±10.8% (P<0.001). Three healthy subjects showed a 2:1 ratio between step and breathing rate, three a 3:2 ratio. Two PD patients showed a coordination of 4:1 and 3:1, respectively, with a larger scatter than in controls. In the other eight patients steps were almost equally distributed over the entire respiratory cycle. We conclude that in patients with PD the coordination between locomotion and breathing is reduced.

Comparison of manual titration and automatic titration based on forced oscillation technique, flow and snoring in obstructive sleep apnea

BACKGROUNDnContinuous positive airway pressure (CPAP) treatment in obstructive sleep apnea syndrome (OSAS) requires pressure titration usually performed during attended in-hospital polysomnography. This manual titration procedure is not well standardized. The aim of the study was to ascertain whether a new automatic titration device is as effective as standard manual titration in determining constant CPAP pressure.nnnMETHODSnWe included 38 patients with a newly diagnosed OSAS. Participants were randomly assigned to attended in-laboratory manual titration and automatic titration in two consecutive nights. Fixed CPAP pressure was set at the optimal pressure determined during the second night. The follow-up period was 6 weeks. Main outcomes were apnea/hypopnea index (AHI) and Epworth sleepiness scale (ESS).nnnRESULTSnAHI (manual: baseline 40.5+/-21.5/h vs. treatment 6.4+/-3.3/h (p<0.001); automatic: 53.3+/-28.1/h vs. 7.8+/-3.3/h (p<0.001)) and ESS (manual: 11.3+/-4.7 vs. 8.8+/-5.1 (ns); automatic: 11.5+/-5.6 vs. 7.0+/-3.8 (p<0.05)) showed a similar improvement in both groups. Pressure recommendation by the device and the technician, although not statistically different (8.7+/-2.9 vs. 9.0+/-3.3 mbar), corresponded only in 50% of the patients.nnnCONCLUSIONSnAutomatic titration effectively predicts constant CPAP pressure for long-term treatment when performed during an attended polysomnography. Careful evaluation of raw data and polysomnography recording is mandatory before choosing a fixed CPAP pressure after automatic titration.

Evaluation of a System for Transcutaneous Long-Term Capnometry

Background: The measurement of CO₂ partial pressure (PCO₂) is of great importance. Former systems of transcutaneous capnometry combining the measurement of oxygen partial pressure (PO₂) and PCO₂ had their limitations due to skin irritations caused by the heating-up of the sensor and a short application time of 4 h. Objectives: To evaluate for the first time combined monitoring of transcutaneous PCO₂ (tcPCO₂) and oxygen saturation applying a lower temperature (sensor temperature 42°C) and a new sensor technology in healthy individuals during sleep. Methods: Twenty-nine healthy individuals [12 males, age 35.2 ± 17.0 years, body height: 170.2 ± 12.0 cm (mean ± SD), weight: 76.3 ± 15.8 kg, body mass index 26.5 ± 5.4] were monitored for more than 6 h at night with the TOSCA 500 instrument (Radiometer, Basel, Switzerland). tcPCO₂ was continuously monitored and its correlation with selective measured capillary PCO₂ values (PcapCO₂) was monitored at 0.00 and 4.00 h. Results: At 0.00 h, PcapCO₂ was 37.1 ± 5.1 mm Hg and tcPCO₂ was 43.4 ± 6.6 mm Hg (p < 0.001). At 4.00 h, PcapCO₂ was 37.0 ± 5.6 mm Hg and tcPCO₂ was 43.5 ± 5.4 mm Hg (p < 0.001). PcapCO₂ and tcPCO₂ were positively and significantly correlated (0.00 h: r = 0.5, p < 0.02 and 4.00 h: r = 0.72 and p < 0.001) at both time points. In the course of the night, there was no significant drift in the tcPCO₂ values. Conclusion: The investigated system enables stable measurement of tcPCO₂ without relevant drift in healthy individuals and does not require recalibration. tcPCO₂ is highly suitable as a measure of PcapCO₂ because the two parameters are highly correlated and there is no inconvenience to the patient.

Oxygen supply and respiratory-like activity in the isolated perfused brainstem of the adult guinea pig.

In isolated brainstem preparations of mature guinea pigs the respiratory network remains functional only if perfused internally via the basilar artery with Krebs solution equilibrated with 95% O2/5% CO2. In order to determine the oxygen availability in this preparation, we measured tissue partial oxygen pressures at the level of respiratory-related neurons using oxygen-sensitive microelectrodes. To estimate oxygen consumption we studied the effects of ischemia and cyanide-induced blockade of oxidative metabolism in relation to the respiratory-like rhythmic activity recorded from the hypoglossal nerve. The pO2 profiles obtained from 9 stepwise measurements from the ventral to the dorsal surface decreased from 423 +/- 32 (SE) mmHg on the ventral surface to 219 +/- 64 mmHg at 1900 microns and stabilized near this value up to a depth of 5000 microns. In the superfused preparation without internal perfusion pO2 was 0 mmHg within the first 500 microns. An interruption of perfusion resulted in a rapid (less than 2 min) decrease of tissue pO2 to 0 mmHg. During the ischemic period, respiratory-like neural activity exhibited first an increase in frequency and tonic discharge, followed by a marked decrease in both parameters. Cyanide added to the perfusate caused an immediate increase of tissue pO2 and the drop of tissue pO2 associated with ischemia was abolished. We conclude that there is a considerable oxygen consumption but no hypoxic or anoxic core in the isolated perfused brainstem at the level of the respiratory-related neurons.

Brain Stem Chemosensitivity; Its Implication in Central Respiratory Regulation

Central brain stem chemosensitivity plays an essential role in acid-base regulation. The site of the chemosensitive neuronal elements has not yet been clearly established. To address this question, we used an in vitro adult guinea pig isolated brain stem preparation, maintained in survival conditions by intrabasilar and bath perfusions of Krebs solution saturated with 95% O2 and 5% CO2. Hypercapnic stimulation, produced by modifying the CO2 concentration of the medium perfusing brain stem structures via the basilar perfusion system, increased the respiratory burst frequency recorded from the hypoglossal nerve. Hypercapnia evoked by ventral surface superfusion increased the respiratory burst amplitude. These data suggest that chemosensitive neuronal elements could be located at the ventral surface as well as in the deeper brainstem structures. However, their characteristics may be different.

Variability of CO2-sensitivity during sleep.

The hypercapnic ventilatory response (HCVR) in man varies markedly during sleep. Rebreathing tests during well-defined sleep/wake states in adults showed that the HCVR was significantly reduced in all stages of sleep compared with wakefulness, falling to less than 50% of wakefulness during NREM sleep and less than 30% during REM sleep1.

Schlafmedizin und lebensqualität

Die Schlafmedizin hat sich in den vergangenen dreißig Jahren zu einem Querschnittsfach entwickelt, das eng mit einer Reihe „klassisch“ medizinischer Fächer verknüpft ist. Hierzu zählen die Neurologie und Psychiatrie, wie auch die Innere Medizin, Pneumologie und Pädiatrie, aber auch operative Fächer wie die Hals-Nasen-Ohrenheilkunde und die Mund-Kiefer-Gesichtschirurgie. Schlafmedizin widmet sich der Erforschung, Vorbeugung, Erkennung und Behandlung von