Automatic CPAP titration with different self-setting devices in patients with obstructive sleep apnoea.

Autotitrating continuous positive airway pressure (CPAP) devices automatically adjust the pressure according to upper airway obstructions. The aim of this study was to compare the treatment effects of different automatic CPAP devices (AutoSet, Horizon and Virtuoso) with conventional CPAP in patients with obstructive sleep apnoea independently of financial manufacturer support. Twelve male patients with obstructive sleep apnoea were submitted to a crossover study protocol with overnight polysomnography for 6 consecutive nights. After diagnostic polysomnography, the CPAP pressure was manually titrated. Over the next 4 nights, the patients were treated with any one of the three automatic CPAP devices or fixed CPAP in random order. The apnoea/hypopnoea index on the diagnostic night was 67.3+/-21.7 events h(-1), and was significantly reduced to 0.7+/-1.2, 3.0+/-2.9, 2.3+/-2.5 and 12.0+/-13.6 events x h(-1) with the fixed CPAP, AutoSet, Horizon and Virtuoso devices respectively. An apnoea/ hypopnoea index of <5 events h(-1), an indicator of optimal treatment, was achieved in all patients with fixed CPAP and in 10 patients using the Autoset and Horizon devices, but in only six of the 12 using the Virtuoso. The mean pressure was significantly lower with the AutoSet and Virtuoso devices, but not with the Horizon as compared to fixed CPAP. The maximum pressure was significantly higher with the Horizon. It is concluded that automatic continuous positive airway pressure devices produce a significant reduction in apnoea/hypopnoea index; however, there is considerable difference in the efficacy of the various devices.

[Cardiac arrhythmias in sleep apnea. Increased cardiovascular risk caused by nocturnal arrhythmia?]. / Herzrhythmusstörungen bei Schlafapnoe. Erhöhtes kardiovaskuläres Risiko durch nächtliche Arrhythmien?

In sleep-disordered breathing (SDB), the greatest clinical relevance attaches to obstructive sleep apnea on account of its high prevalence and its concomitance with diseases of the cardiovascular system. The high mortality rate of untreated patients is believed to be due to the consequences of these latter diseases. Thus, for example, in addition to systemic arterial hypertension, elevated rates of such disorders as pulmonary hypertension, right heart insufficiency, coronary heart disease, myocardial infarction and stroke are also found. Up until quite recently bradycardic and tachycardic arrhythmias occurring during sleep have been held responsible of the increased mortality rate of these patients. Till the mid-eighties the prevalence of bradycardic arrhythmias was reported to be more than 30%. However, the importance of cardiac arrhythmias has been overestimated, as is supported in particular by current studies on large non-selected samples showing a much lower prevalence of apnea-related arrhythmias. In the differential diagnosis, however, consideration must be given to SDB in patients with nocturnal arrhythmias and heart rate variations.

Heart block in patients with obstructive sleep apnoea: pathogenetic factors and effects of treatment.

Heart block during sleep has been described in up to 10% of patients with obstructive sleep apnoea. The aim of this study was to determine the relationship between sleep stage, oxygen desaturation and apnoea-associated bradyarrhythmias as well as the effect of nasal continuous positive airway pressure (nCPAP)/nasal bi-level positive airway pressure (nBiPAP) therapy on these arrhythmias in patients without electrophysiological abnormalities. Sixteen patients (14 males and two females, mean age 49.6+/-10.4 yrs) with sleep apnoea and nocturnal heart block underwent polysomnography after exclusion of electrophysiological abnormalities of the sinus node function and atrioventricular (AV) conduction system by invasive electrophysiological evaluation. During sleep, 651 episodes of heart block were recorded, 572 (87.9%) occurred during rapid eye movement (REM) sleep and 79 (12.1%) during nonrapid eye movement (NREM) sleep stages 1 and 2. During REM sleep, the frequency of heart block was significantly higher than during NREM sleep: 0.69+/-0.99 versus 0.02+/-0.04 episodes of heart block x min(-1) of the respective sleep stage (p<0.001). During apnoeas or hypopnoeas, 609 bradyarrhythmias (93.5%) occurred with a desaturation of at least 4%. With nCPAP/ nBiPAP therapy, apnoea/hypopnoea index (AHI) decreased from 75.5+/-39.6 x h(-1) to 3.0+/-6.6 x h(-1) (p<0.01) and the number of arrhythmias from 651 to 72 (p<0.01). We conclude that: 1) 87.9% of apnoea-associated bradyarrhythmias occur during rapid eye movement sleep; 2) the vast majority of heart block episodes occur during a desaturation of at least 4% without a previously described threshold value of 72%; and 3) nasal continuous positive airway pressure or nasal bi-level positive airway pressure is the therapy of choice in patients with apnoea-associated bradyarrhythmias.

[Cardiorespiratory polygraphy in differential diagnosis of respiratory insufficiency in patients after coronary artery bypass operation]. / Die kardiorespiratorische Polygraphie zur Differentialdiagnostik der respiratorischen Insuffizienz bei Patienten nach koronarer Bypass-Operation.

BACKGROUND: In intensive care medicine it is well established how to diagnose respiratory insufficiency caused by cardiopulmonary diseases. However, there is no consensus how to diagnose respiratory insufficiency which may be caused by extrapulmonary disturbances of the respiratory apparatus. PATIENTS AND METHODS: In 5 patients we performed postoperatively a cardio-respiratory polygraphy for 12 to 13 hours using Polymesam. This unit allows to record airflow, respiratory movements of the chest and abdomen, arterial oxygen saturation, heart rate, body position and EKG. RESULTS: The present case-series-study demonstrates that patients after arterio-coronary bypass surgery may present respiratory insufficiency caused by extrapulmonary disturbances of the respiratory apparatus (central and obstructive apnea and hyoponea). The respiratory insufficiency occurs during nighttime even when supplemental oxygen (2 to 3 1/min) is delivered. CONCLUSION: We conclude that the cardiopulmonary polygraphy for assessing respiratory insufficiency in patients after coronary bypass surgery is important, in order to avoid severe arterial hypoxemia which may produce cardiovascular instability in these patients.

[Primary alveolar hypoventilation in adulthood]. / Primäre alveoläre Hypoventilation im Erwachsenenalter.

BACKGROUND: Central alveolar hypoventilation in an adult is characterized by dysfunction of the respiratory center in the brainstem and is very rare, seen mostly secondary to neurological lesions of the brainstem. CASE DESCRIPTION: We report a 48-year-old man with primary alveolar hypoventilation associated with marked cardiac arrhythmias and hemodynamic changes. Arterial blood gas analysis revealed daytime hypoxemia and hypercapnia not explained by normal pulmonary results. All night polysomnography showed sleep fragmentation following repetitive central apneas and hypoventilation with marked hypoxemia and the lowest saturation in REM sleep. Severe nocturnal hypoxemia was accompanied by marked hypercapnia. Premature ventricular complexes occurred associated with nocturnal hypoxemia in NREM sleep while sinus arrest of up to 11.3 s were only seen associated with hypoxemia in REM sleep. Pulmonary arterial pressures were normal when the patient was awake with marked increases in pulmonary arterial pressures associated with hypoventilation and changes in arterial oxygen saturation with the patient was asleep. CONCLUSION: Nasal positive pressure ventilation was effectively able to treat central apneas and hypoventilation, nocturnal hypoxemia and cardiac arrhythmias were no longer observed. Also, daytime arterial blood gases were normal with nocturnal nasal mechanical ventilation.

[Work of breathing in noninvasive proportional assist ventilation in patients with respiratory insufficiency]. / Atemanstrengung unter nichtinvasiver Proportional Assist Ventilation (PAV) bei Patienten mit respiratorischer Insuffizienz.

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.

[Complications of nasal CPAP therapy. Consequences for general practice]. / Komplikationen bei der nasalen CPAP-Therapie. Konsequenzen für die Praxis.

BACKGROUND: The prevalence of the obstructive sleep apnea syndrome is about 5% in the entire population. The amount of treatment-indications grows for this particular sleep-related breathing disorder due to the increasing usage of diagnostic screening tests. In most cases, the positive-pressure ventilation, PPV (nCPAP, nBiPAP) is considered as a highly effective form of treatment, in comparison to other treating methods. The residential polysomnographic supervised adjustment of the treatment is optimally applied to most of the patients. Due to the increasing number of the treated patients, the reports about the appearance of short-termed side effects during the adjustment of the PPV become more frequent. PATIENTS AND RESULTS: We report on 9 patients who showed complications during the initial stage of treatment. The most common one, during the nCPAP-therapy, was the increase of central apneas. Because of this complication, a rapid optimization of the respiratory pressure or a change to a nBiPAP-therapy was necessary in 5 of the patients. 2 of the patients showed cardiac arrhythmias, some of which were severe. One patient produced a remarkable central hypoventilation during the initial phase of a nCPAP-therapy. The nBiPAP-titration combined with right-heart-catheter monitoring could demonstrate in another patient a possible cardiac decompensation through an increased ventilatory pressure. CONCLUSION: The risk of a positive-pressure ventilation is higher in patients with accompanying cardiac, pulmonary, neuropsychiatric and/or otorhinolaryngologic disorders. Considering the various predisposing factors of the patients we suggest an intensive apparative monitoring as well as stuff-supervision during the introduction to a respiratory treatment. If complications appear, a rapid improvement of the ventilatory pressure or a change to another respiratory treatment is indicated.

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.

[Nasal continuous positive airway pressure (nCPAP) therapy in obstructive sleep breathing disorders]. / Die nasale "continuous positive airway pressure (nCPAP)"-Therapie bei obstruktiven schlafbezogenen Atmungsstörungen.

The therapeutic efficacy and the incidence of significant side effects of nasal continuous positive airway pressure (nCPAP) treatment was investigated in 1140 patients with sleep-related apnoea (1089 men, 51 women; mean age 53.2 +/- 9.2 [16-84] years). All had been treated for the condition with nCPAP at the Marburg University Medical Polyclinic between 1986 and 1992. The mean number of attacks of apnoea and/or hypopnoea per hour of sleep ("respiratory disturbance index", RDI) was 45.8 +/- 25.6 before treatment and 3.5 +/- 4.8 under nCPAP. 21.1% of patients had an apnoea index of no more than 10/h. 11.6% an RDI of no more than 15/h. The average airway pressure was 8.7 (3-18) cm H2O. The treatment was successful in 1023 patients and these decided to continue the treatment long-term. The RDI could not be lowered under 10/h in 63 patients, while 4 patients declined ambulant treatment despite the demonstrated efficacy of nCPAP. Three patients developed acute left ventricular failure in the initial phase of the treatment, while in another 16 patients long-persisting central hypoventilation was shown to occur. These data show that treatment with nCPAP can be employed for all degrees of severity of obstructive sleep apnoea. However, because of the potentially life-threatening side effects, the introduction of the treatment must be undertaken in the sleep laboratory under continuous monitoring.

Intrathoracic pressure changes and cardiovascular effects induced by nCPAP and nBiPAP in sleep apnoea patients.

The effect of nasal continuous positive airway pressure (nCPAP) and nasal bi-level positive airway pressure (nBiPAP) on intrathoracic pressure and haemodynamics during wakefulness was studied in a group of nine patients with severe sleep apnoea. No patient took cardiovascular medication. Patients were studied with a Swan Ganz catheter, an arterial line and an oesophageal balloon. nCPAP and nBiPAP were applied in the following pressure sequence: 5, 10 and 15 cm H2O of CPAP and 10/5 and 15/10 cm H2O of nBiPAP. Measurements were made at the end of a 5-min period at each pressure level. Intrathoracic pressure was noted to increase to a level of approximately 50% of the pressure delivered at the mask. At a CPAP of 10 cm H2O and above, as well as at BiPAP of 10/5 or higher, there was a decrease in cardiac output (CO) and cardiac index (CI). CI fell below the normal value in two of the patients. Transmural pulmonary artery pressure (PPAtm) decreased at a CPAP of 15 cm H2O and at both BiPAP levels. Transmural right atrial pressure (PRAtm) decreased at both BiPAP levels. There were no differences in CO, CI, PPAtm and PRAtm between nCPAP and nBiPAP at equal inspiratory pressures. SaO2 increased during BiPAP 15/10 cm H2O, whereas heart rate and arterial blood pressure did not change significantly. The data presented here are consistent with the literature on positive end-expiratory pressure (PEEP) applied via intratracheal tube and are likely to be due to a reduced venous return. It is concluded that nasally applied positive pressure may have acute negative effects on cardiac function in patients with sleep apnoea.

[Errors and risks in administration of nasal respiratory therapy of obstructive sleep apnea]. / Fehler und Gefahren bei der Einleitung der nasalen Beatmungstherapie obstruktiver Schlafapnoen.

Over a period of 1 year we observed in our sleep laboratory in 502 patients with sleep related breathing disorders several side effects of positive airway pressure treatment, furthermore we observed in 5 patients unexpected dangerous complications due to the application of CPAP and BIPAP. We observed mask leakages which lead to insufficient positive airway pressure-therapy and an occurence of short central apnoeas during NREM sleep after arousal or wakefulness periods. Finally we observed in 5 patients during treatment with CPAP and BIPAP an unexpected appearance of long central apnoeas up to 110s and central hypoventilations up to 5 min accompanied by excessive hypoxaemia (SaO2 < 20%) and cardiac arrhythmias. We conclude that in the treatment of obstructive sleep apnoeas we have to expect in 1-2% complications of the positive airway pressure treatment itself. To avoid life endangered complications the first night application should be done only in conventional sleep laboratories.

[Parameters for determining the effective treatment pressure in nCPAP therapy of sleep apnea]. / Parameter zur Ermittlung des effektiven Behandlungsdrucks der nCPAP-Therapie bei Schlafapnoe.

We evaluated the accuracy of single parameters from the polysomnography in establishing the effective nCPAP treatment pressure in order to possibly economize pressure adjustment. In four patients (pts) a standard polysomnography was performed. 67 segments of 30-60s in duration, showing different typical types of breathing disturbances or normal breathing were selected. The segments were divided into 5 horizontal parts consisting of only one of the following signals: SaO2, snoring, mask pressure, esophageal pressure (Poes) and respiratory movements (RC + Abd). A second investigator then classified these 335 one lead recordings without knowing the complete segment. The classification based on the complete segment compared to that based on only one parameter gave an identical result in 44.8% (SaO2), 61.2% (Poes), 64.2% (RC + Abd), 80.6% (sonoring) and 82.1% (mask pressure) respectively. 97% of the complete segments were classified identically by both investigators. Each of the studied parameters alone was not adequate in establishing the correct pressure level. SaO2 corresponds least, mask pressure and snoring best to the classification based on all parameters.