[Effect of intermittent ventilation on pulmonary hypertension in chronic respiratory failure]

Intermittent non-invasive (or nocturnal mechanical ventilation) eliminates symptoms of hypoventilation and improves gas exchange in patients with chronic respiratory failure. Performing right heart catheterisation we studied the influence of nocturnal mechanical ventilation on pulmonary hemodynamics. We investigated 20 patients with restrictive thoracic diseases (Post-TBC: n = 9, scoliosis: n = 11, PaCO2: 59.8 +/- 7.6 mmHg) and 13 patients with COPD (n = 13, PaCO2: 58.5 +/- 7.8 mmHg). All patients were mechanically ventilated in controlled mode. During the study the medication was not changed; COPD patients with long-term oxygen maintained this therapy. Right-heart catheterisation was performed immediately before and after 1 year nocturnal mechanical ventilation. In patients with thoracic restriction NMV induced a marked reduction of pulmonary artery pressure (PAP) from 33.2 +/- 10.0 mmHg before to 24.8 +/- 6.2 mmHg after 1 year nocturnal mechanical ventilation. In the COPD group PAP increased from 25.3 +/- 6.0 mmHg before to 27.5 +/- 6.0 mmHg after 1 year nocturnal mechanical ventilation. In contrast to the COPD group in patients with chronic respiratory failure due to thoracic restriction nocturnal mechanical ventilation causes substantial reduction in pulmonary artery pressure after a one year application.

[Scintigraphic demonstration of aspiration in long-term ventilation patients with tracheotomy]

The main complication of enteral feeding in prolonged mechanical ventilation via tracheostomy is the subsequent aspiration pneumonia. We used a scintigraphic method for the detection of enteral feeding aspiration and compared the results with clinical evidence of aspiration. The study population consisted of 62 consecutive tracheotomised patients (16 females, age: 64.1 +/- 11.1 years). The swallowing test was done in an upright or semirecumbent body position with the patients spontaneously breathing. The standard feed consisted of a liquid, semiliquid and solid meal which was labelled by 100 MBQ 99 TC. Scintigraphic aspiration (SA) was defined as positive if radioactivity was detected in the bronchial system. Clinical aspiration (CA) was defined as positive if there was cough, choking and distress after swallowing; furthermore, when receiving enteral feeding during suctioning or bronchoscopy. Both clinically significant aspiration (CA) and scintigraphic aspiration (SA) were found to be identical in 10 of 62 (16%) patients. CA, but not SA: 4/62 (6.5%). SA, but not CA (Subclinical aspiration): 4/62 (6.5%). Nor CA neither SA: 44/62 (71%) patients. Radiolabelled feed can be used as a feasible marker to detect aspiration. The test is a useful screening test and strategy to minimize aspiration. The scintigraphic method failed to identify all tracheotomised patients with clinically significant aspiration. However, scintiscanning did suggest that some patients had subclinical aspiration.

[Withdrawal from the respirator (weaning) in long-term ventilation. The results in patients in a weaning center]

BACKGROUND AND OBJECTIVE

Patients subjected to an increased load and with a decreased capacity of their respiratory muscles may be difficult to wean from mechanical ventilation. Using a weaning strategy with a focus on unloading respiratory muscles may be successful even after long-term mechanical ventilation. In a prospective uncontrolled study, we examined the outcome of our weaning protocol.

PATIENTS AND METHODS

Under prolonged mechanical ventilation in outlying intensive care units (44.3 +/- 38.1 days) 232 patients (64.8 +/- 12.7 years, 149 males, 83 females) with the following underlying diagnoses were investigated: chronic obstructive pulmonary disease (54.3%), neuromuscular diseases (16%), thoracic restriction (10.8%), chronic left heart failure (7.3%), postsurgical ventilatory failure (6.9%) and miscellaneous conditions (4.7%). Our weaning strategy was focused on type of mechanical ventilation, endotracheal tubes, non-invasive interface, oxygen supply and transport capacity, body position and home mechanical ventilation, if an increased load or a decreased capacity of the respiratory muscles remained after weaning.

RESULTS

Altogether 65% of the patients (n = 152) were weaned in a mean duration of 7.5 days. Intermittent home mechanical ventilation followed in 45 patients (19.4%). In our hospital died 64 patients (27.6%). After a stay of 19.7 +/- 12.2 days in our hospital 72.4% of the patients (n = 168) were discharged. The postdischarge 3-month mortality of the cohort was 36.5%.

CONCLUSION

Applying our weaning strategy about 65% of the patients requiring long-term mechanical ventilation were successfully weaned. Weaning was achieved in approximately one fifth of the time previously spent on mechanical ventilation. However, the 3-month mortality of the investigated cohort was 36.3%.

[Current value of intrapleural fibrinolysis in the treatment of exudative fibrinous pleural effusions in pleural empyema and hemothorax]

Intrapleural administration of fibrinolytic agents has been in use for fifty years; it has, however, been of clinical importance only for the last twenty years. Parallel to clinical reports procoagulant and fibrinolytic activities in pleural effusions are studied. Most types of pleural injury are characterised by fibrin deposition in the pleural space promoted by concurrent local abnormalities of pathways of fibrin formation and its clearance. Many of the studies of intrapleural fibrinolytics are uncontrolled and retrospective or small and are therefore of limited statistical value. Only five of the studies which are presented in the table are controlled and comparative studies. Intrapleural fibrinolytic therapy was used in exudative fibrinous multi-loculated pleural effusions, pleural empyemas and haemothorax. The global success rate of the studies cited were between 44% and 100%, in most cases more than 80%. The great differences in success rates are due to variations in the pleural diseases and stages of the clinical course, different success criteria, different dosages of fibrinolytic agents, different durations of clamped chest tube drainage and different starting points of therapy during the hospital course. The number of patients enrolled in each study ranged from 8 to 98, the number of children ranged from 2 to 9. Intrapleural fibrinolytic treatment is associated with rare adverse effects. There is no significant systemic fibrinolytic activity of intrapleural fibrinolysis. Intrapleural administration of streptokinase has been reported to lead to antibody formation. Hence, intrapleural fibrinolytic therapy is a useful adjunct in the management of exudative fibrinous multi-loculated pleural effusions, pleural empyemas and haemothorax. There is an increased volume of pleural fluid drainage during the treatment phase, and intrapleural fibrinolysis may reduce the need for more invasive surgical procedures. On the basis of the data of literature we recommend to use a single daily dose of 250,000 U streptokinase or 100,000 U urokinase in 50-100 ml normal saline instilled into a chest tube and to maintain dwell times of 2 to 4 hours. Therapy can be continued up to 2 weeks. The pleural space can be drained by large bore chest tubes or small drainage catheters, both radiologically guided, without preference for one method.

[Daytime mechanical ventilation in chronic ventilatory insufficiency]

BACKGROUND

Nocturnal hypoventilation is associated with chronic ventilatory insufficiency (CVI). Noninvasive mechanical ventilation (NIV) performed overnight relieves symptoms of hypoventilation and improves daytime blood gases in CVI. In order to test whether the efficacy of NIV depends on its being applied during sleep we conducted a prospective case controlled study comparing daytime mechanical ventilation (DV) in awake patients with nocturnal mechanical ventilation (NV) given in equal quantities.

PATIENTS AND METHODS

We enrolled 34 clinically stable patients (age: 56.1 +/- 12.1 years, 20 female) with CVI due to both restrictive lung and chest wall disorders and neuromuscular disease. Using a prospective case-control design, matched subjects were allocated alternately to DV and NV.

RESULTS AND CONCLUSIONS

There were no significant differences between the groups in the improvement of the measured parameters; (e.g. PaCO2; DV: from 57.6 +/- 4.3 to 44.0 +/- 4.6 mm Hg, NV: from 55.5 +/- 3.5 to 45.0 +/- 4.1 mm Hg, p < 0.0001). We conclude that in many respects, when compared to NV, DV in awake patients is equally effective for the treatment of CVI.

[Evaluation of daily activity in patients with COPD]

BACKGROUND

Recently we could show that the daily activity in patients with hypercapnic respiratory failure as judged by the total amount of movements per day increased by 120% after 3 months of non-invasive mechanical ventilation. This study was designed to evaluate the reproducibility of the result of a movement detector in measuring daily activity of patients with COPD.

PATIENTS AND METHODS

25 outpatients (11 females, 56 +/- 12 years old) with stable non-hypercapnic COPD (FEV1 = 47 +/- 9% predicted) were examined twice during a 7 days lasting interval, one month apart using a pedometer.

RESULTS AND CONCLUSIONS

The repeatability of the activity counts in the non-hypercapnic COPD patients was high (1st study period: 3,781 +/- 2,320 movements/d, 2nd study period: 3,626 +/- 2,149 movements/d) and in these patients activity correlated significantly with FEV1 (r = 0.54, p = 0.006).

[Continuous flow apnoeic ventilation via intratracheal oxygen insufflation]

BACKGROUND

In patients with disturbed gas-exchange (e.g. COPD) intratracheal oxygen insufflation (ITO2) improves oxygenation and reduces the minute ventilation. We use a bronchoscopic technique of intratracheal catheter placement in unintubated patients. In a patient with a pink-puffer emphysema after endoscopical insertion of the catheter ITO2 induced a "continuous flow apnoeic ventilation" (CFAV).

CASE REPORT

A patient (female, 58 years) with a pink-puffer emphysema was admitted to the ICU with acute on chronic respiratory failure due to acute laryngitis. Because of laryngitis associated upper airway obstruction a non-invasive mechanical ventilation could not be performed. The ensuing high flow ITO2 (10 l/min) induced a CFAV characterized by no chest wall movement and adequate ventilation as reflected by stable, elevated PaCO2 (between 118 and 125 mm Hg), which could be maintained for 4 hours. After an ensuing short-term invasive mechanical ventilation and the administration of high dose glucocorticoids the patient was successfully extubated and the clinical status improved continuously.

CONCLUSION

In a patient with an acute on chronic respiratory failure due to end-stage emphysema ITO2 induced CFAV and stabilized the clinical status. Especially in patients with end-stage emphysema, who are likely to be difficult to be weaned from the respirator ITO2 may be a feasible technique in order to bridge an emergency situation.

[Importance of blood transfusion in anemic patients with COPD and unsuccessful weaning from respirator]

BACKGROUND

Imbalance of load-capacity relationship in severe COPD may lead to ventilatory failure. Additionally, in such patients, anemia may aggravate the ventilatory load. In this retrospective study we investigated whether anemia patients undergoing long-term ventilation benefit from transfusion.

CASE REPORTS

We studied 5 anemic patients (hemoglobin: 8.7 +/- 0.8 g/dl) with COPD in whom trials of weaning from the ventilator had been unsuccessful. After transferral to our regional weaning centre, blood was transfused to increase the hemoglobin value to approximately 12 g/dl or higher. Subsequently, all patients could be successfully weaned within a short period.

CONCLUSION

We conclude that in difficult to wean anemic patients blood transfusion should be considered and may lead to successful weaning.

Scintigraphy for evaluating early aspiration after oral feeding in patients receiving prolonged ventilation via tracheostomy

OBJECTIVE

In tracheotomised patients the incidence of aspiration is difficult to determine because investigators often apply different criteria. In this study a scintigraphic method was used to visualise feeding aspiration directly and the results were compared with clinical evidence of aspiration.

DESIGN

Prospective study in difficult-to-wean patients with tracheostomy.

SETTING

Respiratory ICU.

PATIENTS AND METHODS

The study population consisted of 62 consecutive patients (16 females, age: 64.1+/-11.1 years). All patients were tracheotomised and had previously been long-term ventilated in other ICUs due to weaning failure. The scintigraphic test was performed during spontaneous breathing. The standard nutrition consisted of a liquid, semi-liquid and solid meal which was labelled with 100 MBq 99mTc-human serum albumin.

MEASUREMENTS AND RESULTS

Scintigraphic aspiration (SA) was defined as positive if radioactivity was detected in the bronchial system using a scintillation camera. Furthermore, aspiration was proven clinically (CA). CA and SA yielded identical results in 54 of the 62 patients [10 positive (16%) and in 44 negative (71%)]. CA, but not SA, was seen in 4/62 (6.5%) and SA, but not CA, was found in 4/62 (6.5%) patients.

CONCLUSIONS

Our data re-emphasise that aspiration in tracheotomised patients is common (in our study approximately 30%). The scintigraphic method failed to identify all tracheotomised patients with clinically significant aspiration; however, it did suggest that some patients had subclinical aspiration.

[Relevance of deep venous thrombosis of the leg in patients with acute exacerbated COPD]

BACKGROUND

Acute exacerbation of chronic obstructive pulmonary disease (COPD) is associated with dyspnoea and, consequently, reduced mobility. Immobility is a recognised risk factor for deep venous thrombosis (DVT), but few data exist regarding the prevalence of DVT in acute exacerbation of COPD. Real-time B-mode ultrasonography (US) is a noninvasive screening-method for the diagnosis of DVT. We therefore used US to investigate the prevalence of DVT in patients with an acute exacerbation of COPD.

METHODS

In a prospective cohort study 196 patients with COPD were studied (110 men, 86 female, age: 66.9 +/- 9.1 years, weight: 63.5 +/- 12.7 kg, forced expiratory volume in 1 second [FEV1]: 0.7 +/- 0.21, FEV1% of vital capacity [VC]: 37 +/- 6) in a respiratory intensive care unit on the day of admission. Patients with reduced mobility due to other diseases were excluded. All US were performed by one experienced person with a 5 MHz linear scanner. The veins of the lower extremity were subdivided into 3 segments: 1. The common femoral, 2. superficial femoral veins including the long saphenous vein and 3. the popliteal vein.

RESULTS

In 21 of 196 COPD patients (10.7%) DVT were demonstrated; 18 of these were asymptomatic. Bilateral DVT were not found. In 6 patients additional diagnoses were obtained. There was no difference between patient with and without DVT with respect to age, hemoglobin, PO2, PCO2, pH, FEV1, VC or dyspnoea scale.

CONCLUSIONS

DVT in the lower extremity, which was not detectable on clinical examination, was relatively common in patients with an acute exacerbation of COPD. All measured clinical variables (age, weight, dyspnoe-scale, lung function, hemoglobin and hematocrit and blood gases) failed to predict patients more likely to have DVT.

[Value of orally administered retard morphine for therapy of severe pulmonary emphysema of the pink-puffer type. A pilot study]

BACKGROUND AND OBJECTIVE

In severe "pink puffer" emphysema the patients' physical capacity is limited by dyspnoea despite maximal application of established treatment. This pilot study investigated the effect of retarded morphine, taken orally for 10 days, on ventilation, dyspnoea, walking capacity and wakefulness.

PATIENTS AND METHODS

Twenty clinically stable patients (11 men, 9 women, mean age 68.5 [50-81] years) with "pink puffer" emphysema were studied over a period of 10 days in a prospective, non-controlled trial of cross-over design. Criteria for inclusion in the study were: 1-second forced expiratory volume (FEV1) < 1 I, vital capacity < 50% and normocapnia. In addition to their existing therapy patients received either no further therapy or retarded morphine. Morphine dosage was increased to maximally 3 x 30 mg daily, depending on effectiveness and side effects, dyspnoea at rest and immediately after a 6-min walk (assessed with Borg's visual analog scale), maximal walking capacity were determined, as well as blood gases, respiratory minute volume and the respiratory drive (airway occlusion pressure [P0.1]), responsiveness of the respiratory pathways to CO2 and wakefulness (concentration, fatigue, interest in surroundings).

RESULTS

Twelve patients completed the study (group A). In the remaining patients (group B) the test had to be stopped prematurely because of undesirable side effects or an exacerbation of the underlying infection. In group A, morphine (mean dosage: 49.2 +/- 28.4 mg/d) caused a reduction of PaO2, dyspnoea on activity, the resting minute respiratory volume, respiratory drive and CO2 response, and an increase in PaCO2, HCO3- and the 6-min walking distance. Morphine did not produce a change in subjectively evaluated vigilance and the blood pH.

CONCLUSION

After strict patient selection oral morphine produced a reduction of exercise dyspnoea and an increase in walking capacity in half of the patients with severe pulmonary emphysema. There also occurred a slight rise in PaCO2 without any relevant respiratory acidosis or significant decrease in wakefulness.

Blood transfusion and lung function in chronically anemic patients with severe chronic obstructive pulmonary disease

OBJECTIVE

To study in anemic patients with chronic obstructive pulmonary disease (COPD) whether blood transfusion reduces minute ventilation and work of breathing (WOB).

DESIGN

We prospectively evaluated the minute ventilation and WOB in 20 anemic adults (hemoglobin of <11 g/dL). Ten patients had severe COPD and ten patients were without lung disease. Measurements were made before and after receiving red blood cell transfusion; post-transfusion measurements were made 24 to 36 hrs after the last transfusion.

SETTING

The study was performed in the intensive care unit of a tertiary referral center for home mechanical ventilation and for patients considered difficult to wean from mechanical ventilation.

PATIENTS

Twenty clinically stable patients (12 female, eight male) with chronic anemia were studied. Ten patients with COPD (mean forced expiratory volume in 1 sec: 0.55+/-0.1 [SD] L) were compared with ten patients without lung disease. All participants had adequate renal and left ventricular function.

INTERVENTIONS

Patients received 1 unit of packed red blood cells for each g/dL that their hemoglobin value was less than an arbitrarily defined target value of 11.0 to 12.0 g/dL. Each unit was transfused over 2 hrs and < or =3 units in total was given.

MEASUREMENTS AND MAIN RESULTS

Esophageal pressure was measured from a catheter which was positioned in the middle of the esophagus. Flow was measured using a pneumotachygraph connected to a mouthpiece while a nose clip closed the nostrils during the measurements. From these data, respiratory rate, minute ventilation, and inspiratory resistive WOB were computed. Arterial blood gas values, oxygen saturation, hemoglobin, and hematocrit were also measured, and oxygen content was calculated before and 24 to 36 hrs after transfusion. In patients with COPD, hemoglobin increased from 9.8+/-0.8 to 12.3+/-1.1 g/dL due to a mean transfusion of 2.2+/-0.4 (SD) units of red blood cells. There was a reduction in the mean minute ventilation from 9.9+/-1.0 to 8.2+/-1.2 L/min (p < .0001); correspondingly, WOB decreased from 1.03+/-0.24 to 0.85+/-0.21 WOB/L (p< .0001). The capillary P(CO2) increased from 38.1+/-6.0 to 40.7+/-6.8 torr (5.1+/-0.8 to 5.8+/-0.9 kPa) (p < .05). Similarly, capillary P(O2) changed from 56.9+/-8.9 to 52.8+/-7.0 torr (7.6+/-1.2 to 7.0+/-0.9 kPa) (p < .05). In anemic patients without lung disease, minute ventilation, WOB, and the capillary blood gas values did not change after increase of the hemoglobin by a similar degree.

CONCLUSIONS

We conclude that red blood cell transfusion in anemic patients with COPD leads to a significant reduction of both the minute ventilation and the WOB. In these patients, transfusion may be associated with unloading of the respiratory muscles, but it may also result in mild hypoventilation.

[Therapeutic strategies in respiratory insufficiency in amyotrophic lateral sclerosis. Possibilities and limits]

In the final stage of amyotrophic lateral sclerosis (ALS) the majority of patients develop chronic respiratory failure due to respiratory muscle weakness. The interaction between the patient with ALS and the physician should be characterized by continuous communication, especially with respect to the prospect of ventilatory failure and for support. The patient and his family must be informed thoroughly about the natural history and the prognosis of ALS, depending on the individual disease process. Already in the early stage of the disease coping strategies should be discussed so that imminent respiratory emergencies can be handled. If ALS patients are not informed about the acute respiratory insufficiency they run the risk of having to be intubated and mechanically ventilated over a long term. If dyspnea and hypersecretion dominate the final stage of ALS, the therapeutic strategy consists of the administration of morphine, insufflation of oxygen and bronchoscopic suction. Mechanical ventilation should only be initiated in the exceptional case. However, if dyspnea occurs in the early stage of the disease, when there is no bulbar paralysis and peripheral muscle function is intact, then noninvasive mechanical ventilation via mask may improve the quality of life substantially. Nevertheless, invasive mechanical ventilation via a tracheostomy should be avoided.

[Evolutionary quality assurance. A new concept for improving process and outcome quality]

BACKGROUND

The concept evolutionary quality assurance is a new, non-mandatory, open peer review process for in-patients settings.

METHOD

Ten medical charts (with radiographs) from participating hospitals were randomly chosen and assessed using a prespecified questionnaire (total 134). Individual inadequacies had to be justified on a case by case level. Reviewer and reviewee are known by names, allowing subsequent discussions on content between reviewer and reviewee prior to a final judgement. The final analysis was performed anonymously and communicated to the participants after completion of the process. Patients had to give their consent to the review process. The report, however, is not part of the medical patient file, so that access is not warranted. For the first cycle, all lung clinics and departments throughout Germany were asked to participate. 35 chest hospital (approximately 50%) agreed to participate.

RESULTS

Data analysis revealed that almost all detected inadequacies were apparent, i.e. discussions on the discordant interpretation of diagnostic and therapeutic strategies rarely occurred (0.25%). Final analysis of the evaluation performance of reviewers judged less than 5% and 14% judged more than 30% of all quality inadequacies.

CONCLUSIONS

The quality assurance process is comparably cheap and can be implemented without delay, because standards for reference values are not required. The structure allows adaptation in all areas of clinical medicine.

Blood transfusion facilitating difficult weaning from the ventilator

We report a case series of five anaemic patients (haemoglobin: 8.7 +/- 0.8 g.dl-1) with chronic obstructive lung disease in whom trials of weaning from the ventilator were unsuccessful. After transfer to our regional weaning centre, blood was transfused to increase the haemoglobin value to 12 g.dl-1 or higher. Subsequently, all patients were weaned successfully. We conclude from our experience that in anaemic patients with chronic obstructive lung disease there should not be a fixed transfusion threshold. In anaemic patients in whom difficulty in weaning from the ventilator is experienced, blood transfusion should be tailored to the individual patient's needs. Transfusion in those with chronic obstructive airways disease may lead to successful weaning.

CYP2D6 genotype and phenotyping by determination of dextromethorphan and metabolites in serum of healthy controls and of patients under psychotropic medication

Fourteen drug free healthy volunteers and 22 psychiatric patients under psychotropic medication were phenotyped for their individual CYP2D6 activity using dextromethorphan as a probe drug. A solution containing 20 mg dextromethorphan was administered and blood was taken 60 min later for determination of dextromethorphan and metabolites in serum. For comparison, urine was collected over 8 h after ingestion of 20 mg dextromethorphan in a separate test. The CYP2D6 phenotype was determined from the ratio of dextromethorphan to dextrorphan. For genotyping, mutant alleles of the CYP2D6 gene were identified using allele-specific polymerase chain reactions. Genotyping revealed five poor metabolizers of CYP2D6. The others were extensive metabolizers. The ratio of dextromethorphan to dextrorphan ranged from 0.01-2.53 in serum and from 0.0007-4.252 in urine. Probit analysis of serum ratios revealed a bimodal distribution with an antimode at 0.126. According to this antimode, control subjects exhibited identical phenotypes and genotypes, whereas patients under paroxetine, moclobemide or metoprolol who had been genotyped as extensive metabolizers were poor metabolizer phenotypes. Administration of tricyclic antidepressants did not change the CYP2D6 phenotype. The serum assay was more rapid and more accurate than the standard urine approach. Therefore the determination of dextromethorphan and metabolites in serum could be advantageous to measure individual CYP2D6 activities in vivo and thus optimize the dosing of drugs metabolized by CYP2D6.

[Nasal strips without effect on obstructive sleep apnea and snoring]

Recently a nose plaster (NP, Breathe-Right) has been increasingly used in the treatment of obstructive sleep apnoea (OSA) and snoring. Hence, we examined the use of the NP as a treatment of both OSA and snoring without OSA. The NP has a elastic spine that increases the diameter of the nostril and is thought to reduce the degree of OSA and snoring. According to the polysomnographic data two groups were differentiated: Group A (30 patients with OSA, apnoea index > 10/h, 26 men) and Group B (20 snorers, without OSA, 13 men). After the diagnostic polysomnography the efficacy of the NP was measured with a cardiorespiratory polygraph on the 2 following nights. In the group A the polygraphic data (apnoea index, time of apneas, desaturation index, time of desaturations, mean and nadir SaO2) were studied; in group B the snoring index (snoring events/hour) was measured. A questionnaire scored quality of sleeping, daytime condition and the quality of nose breathing. In neither group were the recorded polygraphic findings different with the NP although with the NP an improved nose breathing was scored in both groups. In group A 90% of the patients scored the daytime sleepiness unchanged and 10 of 30 patients described an improved quality of sleep. In group B there was no change in the frequency of snoring events with the NP. Neither the degree of OSA nor of snoring without OSA were changed by the NP, which can therefore not be considered a treatment of these conditions. However, the majority of the study population were impressed by the symptomatic improvement in nose breathing.

Evaluation of a movement detector to measure daily activity in patients with chronic lung disease

This study was designed to evaluate the performance of movement detectors (pedometers) in measuring daily activity of patients with chronic lung disease. Three groups of subjects were studied: group 1: 25 patients with stable nonhypercapnic chronic obstructive pulmonary disease (COPD) (forced expiratory volume in one second (FEV1) = 47+/-9% predicted) studied twice, one month apart; group 2: 25 patients with chronic respiratory failure studied before and three months after nasal nocturnal mechanical ventilation; and group 3: 25 normal healthy subjects studied once. The median level of activity in the healthy subjects (group 3) was three times greater than in either group of patients (groups 1 and 2). Activity levels were not correlated with age, sex or employment status. The repeatability of the activity counts in the nonhypercapnic COPD patients was high (intraclass correlation coefficient=0.94) and in these patients activity correlated significantly with FEV1 (r=0.54, p=0.006). In the respiratory failure patients, daytime arterial carbon dioxide pressure (Pa,CO2) improved following nasal nocturnal mechanical ventilation (NMV) (pre NMV: 8.5+/-1.2 kPa; post NMV: 6.2+/-0.5 kPa), health status improved (p<0.004) and daily movement count doubled (p<0.0001). This increase correlated with change in Pa,CO2 (r-0.53, p=0.006), but not with improved health status. We conclude that motion detectors may provide repeatable measures of daily activity that are related to physiological impairment and improvement following treatment. Activity counts appear to be complementary to estimates of exercise limitation obtained using health questionnaires.

[Changes in the time spent awake in obstructive sleep apnea and snoring--results of a pilot study]

Continuous positive airway pressure (CPAP) therapy reduces sleeping time per day and daytime sleepiness in obstructive sleep apnoea (OSA) and heavy snoring. Due to sleep fragmentation the OSA and heavy snoring are associated with a daytime sleepiness and increased necessity of sleep. In this pilot study the effect of CPAP-therapy on daytime sleepiness and sleep time during 24 hours were assessed in patients with OSA or heavy snoring (daytime sleepiness, none or slight apnoea with AHI < 10/h and benefit of CPAP). We studies 42 patients with OSA (AHI: 34.5 +/- 23.6) and 15 patients with heavy snoring: inclusion criteria: Patients with OSA (AHI > 10/h, ESS-Score > 8) and heavy snoring (AHI < 10/h, ESS-Score > 8) who were treated with nCPAP. Before and 2 months after initiation the CPAP-therapy all patients completed diary cards recording the sleeping time/day for 1 month; additionally they scored sleepiness using the Epworth sleepiness scale (ESS-score ranged from 0 to 24, the higher the score the worse the sleepiness) before and 2 months after initiation the CPAP-therapy. In the whole study population nCPAP-therapy reduced the sleeping time significantly by a mean period of 46 minutes per 24 hours (from 8.3 +/- 1.3 to 7.5 +/- 1.2 hours, p < 0.001) and improved the ESS score from 13.7 +/- 4.6 to 6.1 +/- 3.6 (p < 0.0001). In respect of the change of sleeping time/day and of the sleepiness score there was no significant difference between the OSA and heavy snoring group. With CPAP the AHI in OSA patients was reduced from 34.5 +/- 23.6/h to 3.2 +/- 3.2/h. Due to the improvement of sleep-related breathing disorders CPAP therapy reduced the mean sleeping time/day by approximately 10% and the daytime sleepiness score both in patients with OSA and heavy snoring compared to the pretreatment period.

[Ergometry separates sleep apnea syndrome from obesity-hypoventilation after therapy positive pressure ventilation therapy]

In contrast to the obstructive sleep apnoea syndrome (OSA) the obesity-hypoventilation syndrome (OHS) is characterized by persistent hypercapnia during the day. After positive pressure ventilation (PPV) patients with OHS the daytime blood gases normalize after a short time. The aim of this study was to investigate whether blood gases at the end of a standardized exercise test separate both OSA and OHS after 3 months of PPV. Fourteen patients with OHS (12 males, 53.2 +/- 9.5 years, BMI: 41.7 +/- 9.6 kg/m2, PCO2: 50.7 +/- 4.5 mmHg) and 28 patients with severe OSA (27 males, 54.5 +/- 8.3 years, BMI: 35.7 +/- 4.9 kg/m2, PCO2: 37.3 +/- 3.3 mmHg) were studied. Blood gases before and after 4 minutes constant load exercise test were measured. The exercise level for patients with OSA was 2/3 of the predicted maximal work load. Since in OHS the load tolerance was compromised, the exercise test was performed at 2/3 of the maximal exercise level which was investigated before. The identical exercise load was done before and 3 months after beginning the PPV. Compared to the OSA-group the load tolerance of the OHS-group was lower (112 +/- 20 Watt [2/3 of predicted maximal work load] versus 81 +/- 26 Watt [39.9 +/- 8.3% of predicted maximal work load], p < 0.0001). Both before and after 3 months of PPV all patients with OHS showed an exercise induced increase of PCO2 (Before PPV: from 50.7 +/- 4.5 to 56.6 +/- 5.8 mmHg; after PPV: from 39.1 +/- 2.7 to 45.6 +/- 2 mmHg, each p < 0.0001). Correspondingly the PCO2 decreased significantly. In OSA neither before nor after 3 months PPV the blood gases changed significantly during the exercise test. We conclude that the OHS associated hypercapnia during exercise is further on a reliable indicator for the diagnosis despite the daytime normocapnia during rest after PPV. However after PPV the PCO2-values of patients with OHS at rest are in the normal range.

Daytime mechanical ventilation in chronic respiratory insufficiency

Chronic respiratory insufficiency (CRI) is associated with nocturnal hypoventilation. Treatment with noninvasive mechanical ventilation (NIMV) performed overnight relieves symptoms of hypoventilation and improves daytime blood gases in CRI. In order to test whether the efficacy of NIMV depends on it being applied during sleep, we conducted a prospective case-controlled study comparing daytime mechanical ventilation (dMV) in awake patients with nocturnal mechanical ventilation (nMV) given in equal quantities. We enrolled 34 clinically stable patients (age 56.1+/-12.1 yrs, 20 females, 14 males) with CRI due to restrictive lung and chest wall disorders and neuromuscular disease. Using a prospective case-control design, matched subjects were allocated alternately to dMV and nMV. After 1 month of NIMV there was considerable symptomatic improvement in both dMV and nMV patients. There were no significant differences between groups in the improvement in daytime arterial carbon dioxide tension (Pa,CO2) (dMV from 7.5+/-0.6 to 5.7+/-0.6 kPa; nMV from 7.2+/-0.5 to 5.8+/-0.5 kPa, p<0.0001) and during the unassisted spontaneous night-time ventilation in terms of transcutaneous Pa,CO2 (dMV from 8.4+/-1.2 to 6.6+/-0.7 kPa; nMV from 8.2+/-1.2 to 6.8+/-0.5 kPa, p<0.0001). We conclude that in many respects, when compared to nocturnal mechanical ventilation, daytime mechanical ventilation in awake patients is equally effective at reversing chronic respiratory insufficiency. Since long-term safety issues were not addressed in this study, we recommend that nocturnal mechanical ventilation should remain the modality of choice for noninvasive mechanical ventilation.

How important is the differentiation between apnea and hypopnea?

Apnea and hypopnea during sleep are often viewed as different expressions of the same sleep-related breathing disorder. In our point of view, both symptoms are two different entities which can occur in the same patient. We discuss the hypothesis that sleep apnea is a disorder associated with recurrent arousals and chronic activation of the sympathetic nervous system, leading to daytime sleepiness and disturbances in the autonomic system. Hypoventilation results from reduced alveolar ventilation and is associated with hypercapnia. In rare cases it is caused by genuine disorders of the breathing center, like Odine's curse. In most cases, hypoventilation is secondary to an underlying disease and a strategy of the body, to avoid respiratory muscle failure. Treatment trials of hypoventilation of the respiratory muscles by stimulating the breathing center failed to be beneficial. However, unloading treatment with long-term oxygen and/or home mechanical ventilation improves arterial blood gases, physical activity and prognosis.

[Work of breathing in differentiation of various forms of sleep-related breathing disorders]

BACKGROUND

In contrast to the obstructive sleep apnoea syndrome (OSA) the obesity-hypoventilation syndrome (OHS) is characterised by persistent hypercapnia during the day and predominant hypoventilation during sleep. In this study we wanted to know whether work of breathing (WOB) in a sitting and supine position separates both groups.

PATIENTS AND METHODS

OSA population: 20 men, 50.5 +/- 9.2 years, Body Mass Index (BMI: 54.1 +/- 6.9 kg/m2, pO2: 65.6 +/- 6.6 mmHg, pCO2: 40.6 +/- 3.1 mmHg, OHS-group: 14 patients, 13 men age: 53.1 +/- 9.3 years, BMI: 53.1 +/- 9.3 kg/m2, pO2: 51.8 +/- 10.5 mmHg, pCO2: 53.8 +/- 9.2 mmHg. The control group consisted of 10 normal weighted subjects. The intrathoracic pressures were assessed by an oesophageal catheter; at the same time, the minute ventilation (VE) and the breathing frequency (fb) were measured via a pneumotachygraph. The area under the pressure-volume loop was correlated to WOB. After reaching steady state VE, fb, and WOB were determined in sitting and supine position.

RESULTS

In the OSA-group the apnoea index (AI) was 48.6 +/- 17.7/h and the respiratory disturbance index (RDI) was 66.3 +/- 19.4/h. The forced expiratory volume (FEV1) was 77.3 +/- 23% pred. and the vital capacity (VC) was 76.3 +/- 18.6% pred.; 7 out of 20 patients suffered from chronic bronchitis. In the OHS-group the AI was 21.5 +/- 19/h and the RDI 44.3 +/- 28.2/h. The majority of OHS patients had an airway obstruction (FEV1: 55.8 +/- 17.5% pred., VC: 58.8 +/- 12.8% pred.); 12 out of 14 patients suffered from chronic bronchitis. Compared to the OSA population WOB in the OHS group was significantly higher both in the sitting (0.67 +/- 0.28 J/I versus 1.04 +/- 0.32 J/I, p < 0.001) and supine positions (1.23 +/- 0.25 J/I versus 1.91 +/- 0.43 J/I, p < 0.001). Compared to the sitting position VE and fb did not change significantly in both groups lying supine.

CONCLUSIONS

Compared to the OSA group at the same BMI the WOB of the OHS population was significantly increased in the sitting and supine position. The main reason for these findings may be the increased airway obstruction due to chronic bronchitis. Both populations did not change the breathing patterns during the different positions.

[Bronchial hyperreactivity and nCPAP therapy]

In patients with obstructive sleep apnoea (OSA) nCPAP may irritate the mucous membranes of the upper airways. We investigated in this study whether nCPAP can induce bronchial hyperreactivity (BHR). Forty-one patients (33 men, mean age 52.6 years) were treated with nCPAP due to OSA. All of them were tested for BHR with histamine ("pari-provo-Test") before and six weeks after initiation of the nCPAP therapy. Thirty-five of the patients showed BHR neither before nor after the beginning of CPAP. Six patients developed a BHR of moderate degree (PD20: 50-100 micrograms) during the study; four of these six patients were not symptomatic. The two other patients complained about more colds than usual or about noctumal cough. Both of them received inhaled steroids and a moistening system. Nobody of the enrolled patients was obliged to finish CPAP therapy due to BHR. Four patients had already a BHR before nCPAP therapy began. Most of the patients did not acquire a BHR during the first 6 weeks after nCPAP therapy had started. A BHR bronchial may develop, but in the majority it remains without clinical relevance. In patients with a BHR and OSA, the benefits of nCPAP therapy excel the potential adverse effects.

[Is SnorEx also ApneaEx? A study with a new intra-oral prosthesis as a form of therapy of obstructive sleep apnea syndrome]

In recent years different kinds of dental devices have been advocated for treating sleep apnoea. In this study we report on our results with a kind of prosthesis ("Snor-Ex", DEPITA, 29336 Nienhagen) designed to relieve upper airway obstruction in sleep in pulling forward the tongue by a truss pad positioned in the posterior area of the tongue. We performed the study to test the effectiveness of the device in reducing the number of obstructive events.

PATIENTS

23 patients with OSA (22 male, age: 53.7 +/- 8.6 years, Body mass index: 31.1 +/- 3.9 kg/m2, Apnoea index: 33.5 +/- 18.4, Respiratory disturbance index: 45.6 +/- 19.7, mean apnoea duration: 20.4 +/- 4.4 sec) were included.

STUDY DESIGN

Before the study was started, polysomnography was performed and the OSA associated symptoms/claims were standardised with the help of visual analogue scales (VAS). The prosthesis were made by the dental laboratory. Between the 28th and 42nd day after beginning with the study the patients had to come to the hospital for control. The effect of the therapy was documented only by a further polysomnography in patients who could sleep for at least 2.5 hours with the prosthesis. The effects of the device on changing OSA-associated symptoms and snoring were reevaluated by the above mentioned VAS. During the control the patients were divided into non-responders (NR) and responders (R) according to the results.

RESULTS

The NR prevail in the study with 75% (17/23). They are characterised by inacceptable loco-regional side effects of the prosthesis, missing improvement of the state of daytime wellbeing and constant obstructive events. Only 25% of the patients are R. They locally tolerated the prosthesis, which is the precondition for long-term therapy. The severity of OSA diminished. Snoring also diminished significantly.

CONCLUSION

According to our results the insufficient acceptance and the low effectivity of the SnorEx-prosthesis preclude large-scale indication for OSA patients. The prosthesis should not be prescribed without contacting a sleep lab.

[Predictive value of laryngoscopy with reference to the severity of obstructive sleep apnea]

The diagnosis of sleep-related breathing disorders is based primarily upon targeted history-taking and upon night-time polysomnography. Diagnostic measures should be completed by laryngopharyngoscopy (LPS). Frequently in cases of relevant obstructive sleep-related breathing disorders, a collapse of the pharyngeal lumen may be detected already in the waking state: either during spontaneous breathing or through adequate provocation (snoring manoeuvre). Furthermore, endoscopy of the upper airways will yield indirect clues as to nocturnal snoring and possible obstructive apnoeas. Although the predictive value of LPS regarding the degree of obstructive sleep-related breathing disorders seems low compared with polysomnography, it appears reasonable to perform it to exclude further relevant ENT findings. With LPS, local and regional obstacles of the kind of the intended positive pressure ventilation (narrowing of the nasal ducts, septum deviation and hyperplasia of the turbinates) are demonstrable which may warrant surgical correction. LPS, which has a low complication rate, facilitates interdisciplinary cooperation in the care for patients suffering from obstructive sleep-related breathing disorders.

[A new portable monitor for long-term cough recording]

Cough is a common symptom of pulmonary diseases. For a number of reasons it would be of interest to have information about the frequency of coughs over a given period of time. So far, the cough recorders which are available are either too expensive or unwieldy. Hence, we developed a cough recorder linked to a portable, commercially available actigraph (about the size of a pack of cigarettes) that records coughing as an acoustic signal and ventral thorax movement. The signals are filtered via a band pass and sampled by a peak detektor with different time constants to separate the impulse character of the cough signal from the background noise level. The cough recorder registers coughing cumulatively over a period of one minute and has a storage time of one week. Since the acoustic signals are essential for the interpretation of the recordings, the analogue circuit was subjected to a separate validation programme. For this purpose, the distinction between active coughs of 10 volunteers (total number of coughs 550) and background noises (male and female voices and other defined noises, total number of noises 336) was tested. The complete assembly was then tested over night on 7 hospitalised patients with chronic cough. An infrared video camera system was used to make a reference recording of the overnight coughing. The results show that nearly every cough of the 10 volunteers was recorded (r = 0.99). 97.1% of the background noise was correctly interpreted. The complete recorder assembly correctly recorded 98.9% of the coughs (total 870) in the 7 patients. 4.8% of the background noise was erroneously registered as coughing. Summing up, it can be said that the portable cough recorder affords accurate recording of coughing over a period of one week, correctly distinguishing coughing from background noise.

[Pressure versus volume constant ventilation in chronic ventilatory insufficiency]

BACKGROUND

Volume controlled intermittent ventilation (IPPV) via face mask is a treatment of proven efficacy for chronic respiratory failure (CRF). Pressure support ventilation has recently been introduced in the treatment of CRF. In this study we investigated whether pressure constant ventilation (PCV) via face mask could be an adequate long term alternative to IPPV.

PATIENTS AND METHODS

We studied 30 (24 male, age: 52.2 +/- 15.9 years) patients with CRF. We measured the following parameters at baseline, after 1, 2 and 6 months, respectively: blood gas analysis, oxygen saturation, vital capacity, forced exspiratory volume, breathing frequency, tidal volume, inspiratory mouth occlusion pressure, maximal inspiratory pressure, subjective symptom scores and ventilator acceptance scores. In all patients, we attempted to treat with IPPV over 1 month, followed by 1 month's trial of PCV. If PCV, compared to IPPV, was adequate, PCV was continued for a follow-up period of 4 months' duration. If patients deteriorated after PCV they were treated the following 4 months with IPPV.

RESULTS

In 28 out of 30 patients CRF improved concerning subjective and objective parameters. After IPPV 18 out of 28 patients changed to PCV, with an equal quality of treatment (PCV-responder). Ten patients were PCV-nonresponders since compared to IPPV the subjective scores deteriorated and the PaCO2 increased again. In all patients of either therapy group, subjective and objective parameters remained constant for another 4 months period. At baseline the PCV-nonresponders had significantly higher degree of hypercapnia and oxygen desaturation; no other parameters were found to be of predictive value concerning the efficacy of PCV.

CONCLUSIONS

PCV proved to be an alternative to IPPV in the treatment of chronic respiratory insufficiency in approximately 60% of the patients with CRF. However there is a subgroup with more severe CRF at baseline in whom PCV is inadequate.

[Anemia increases work of breathing in patients with lung disease]

BACKGROUND

Pulmonary diseases with marked disorders in gas exchange or chronic overload of the respiratory pump needs increased ventilatory requirements. Additionally in these patients anemic may aggravate the ventilatory load. We thereby evaluated whether in these patients treatment of anemia (red blood cell transfusion: RBCT) leads to an improvement of the ventilatory load in comparison to the anemic patients without pulmonary disease.

PATIENTS AND METHODS

We examined 21 patients with an anemia (Hb < 11 g%, 12 men). Fifteen patients had a pulmonary disease (group A), 6 patients suffered from anemia without pulmonary disease (group B). Subsequently within 8 hours the patients got 2 to 3 RBCT. We studied the patients on the day of admission and 24 to 36 hours after transfusion. The patients kept bed rest for spontaneous breathing 1 hour prior to the actual examination without supplemental oxygen. Hemoglobin, hematocrit, respiratory rate, respiratory minute volume and arterial blood gases were measured. On the following day we repeated the same procedures.

RESULTS AND CONCLUSIONS

Anemia in patients with an increased ventilatory requirement causes an additional increase of work of breathing. In these patients-in contrast to patients without compromised lungs-2.2 red blood cell transfusions lead to an impressive reduction of VE (about 20%) and correspondingly also to a reduction of WOB.

[Endoscopic placement of an intratracheal oxygen catheter--description of a new method]

BACKGROUND

In patients with disturbed gas-exchange intratracheal oxygen insufflation improves oxygenation and reduces the minute ventilation. Until now the intratracheal oxygen insufflation was performed using a tracheostomy or a percutaneous transtracheal technique. We studied the acceptance and efficacy of the intratracheal oxygen insufflation using a bronchoscopic technique of intratracheal catheter placement.

PATIENTS AND METHODS

Five COPD-patients (4 men, 55.2 +/- 10.3 years; FEV1: 0.9 +/- 0.31 = 30.3 +/- 5.5% debit, pO2: 56.2 +/- 10.3 mmHg, pCO2 +/- 43.1 +/- 4.8 mmHg). Procedure of catheter placement: Through a nasally passed bronchoscope a guide wire was inserted into the proximal part of one bronchus. When positioned at the point 2 to 3 cm proximal to the carina, the bronchoscope was marked with plaster at the nasal ostium in order to measure this distance. After removing the endoscope, the oxygen catheter was inserted proximal to the carina using the guide wire. Before and during the intratracheal oxygen insufflation (flow: 3 l/min) minute ventilation, tidal volume, breathing frequence, blood gases and the subjective scores (using a visual analogue scale) were measured.

RESULTS

Apart from one patient with a tolerable spontaneous declining urge to cough irritation the catheter was tolerated well during the study. Whereas pCO2 remained stable during the ITO2 (before ITO2: 43.1 +/- 4.8 mmHg; after 1 hour ITO2: 44.3 +/- 4.8 mmHg), the oxygenation improved (pO2: 56.2 +/- 10.3; 81.4 +/- 19.6 mmHg) and the minute ventilation decreased (7.5 +/- 1.8; 5.4 +/- 1.3 l/min) by approximately 28%.

CONCLUSION

The bronchoscopic application of the intratracheal oxygen catheter was characterized by high acceptance, low invasiveness and immediate function. Furthermore, the minute ventilation and work of breathing respectively decreased to a relevant degree.

[Increased physical activity due to intermittent self-ventilation in chronic respiratory insufficiency]

BACKGROUND

Nocturnal mechanical ventilation (NMV) can reduce symptoms of hypoventilation and improve gas exchange in patients with chronic respiratory failure but there is no data concerning the impact of nocturnal mechanical ventilation on daily activity. We prospectively measured daily activity as judged by total steps per day.

PATIENTS AND METHODS

Thirty stable patients (17 men, mean age 55.2 years, pCO2: 62.3 +/- 9.0 mmHg) with chronic respiratory failure.

DIAGNOSIS

Kyphoscoliosis (n = 11), COLD (n = 7), neuromuscular diseases (n = 6), post-tbc sequelae (n = 6). Applying a pedometer over a 7 day period before and 3 months after initiating nocturnal mechanical ventilation the steps per day were counted. We also obtained arterial blood gases and applied the St. George's Respiratory Questionnaire (scoring range from 0 = complete health to 100 = worst possible).

RESULTS AND CONCLUSIONS

The daily activity in patients with hypercapnic respiratory failure as judged by the total amount of steps per day increased by 120% after 3 months of nocturnal mechanical ventilation (from 1606.9 +/- 1341.3 to 3535 +/- 1813.8 steps per day, p < 0.0001). This was associated with a significant improvement in daytime blood gases and quality of life (QoL) as judged by questionnaire (total score: from 61.3 +/- 14.9 to 48.3 +/- 18.7, p = 0.0006). However no correlation between steps per day and QoL was found.

Endoscopic placement of a tracheal oxygen catheter: a new technique

OBJECTIVE

In patients with chronic obstructive pulmonary disease (COPD), intratracheal oxygen insufflation (ITO) is an established therapeutic approach. We developed a new endoscopic technique of intratracheal catheter placement. The aim of this pilot study was to demonstrate its short-term feasibility in acutely extubated patients with moderate to severe COPD who require oxygen therapy.

DESIGN

A guide wire was inserted through a nasally passed bronchoscope and was positioned such that its tip was placed intratracheally. Using a "Seldinger technique", the tracheal catheter was then inserted over the wire to a point 2-3 cm proximal to the carina and positioned under direct vision from the bronchoscope inserted through the contralateral nose. After catheter insertion, the guide wire was removed. The patients scored catheter-associated local discomfort using a visual analogue scale. In a randomly assigned, crossover design, the effectiveness of the endoscopically (e) inserted ITO catheter was assessed by measuring the capillary blood gases, respiratory rate (RR), tidal volume (Vt) and minute ventilation (MV) after 1 h breathing room air without eITO and 1 h after eITO (flow: 3 l/min).

MEASUREMENTS AND RESULTS

The eITO catheter was placed in all patients without complications and with only minimal discomfort in two patients (spontaneously reversible cough). Compared to breathing room air, capillary O2 pressure increased (from 54.7 +/- 9.4 to 82.8 +/- 21.8 mmHg) whereas Vt (from 458.7 +/- 86.8 to 358.3 +/- 75.1 ml) and MV (from 7.7 +/- 1.5 to 5.5 +/- 1.1 l/ min) decreased significantly (each p < 0.0001) with eITO in all patients. The capillary CO2 pressure and RR did not change.

CONCLUSIONS

Acutely extubated patients in whom oxygen therapy is indicated may profit from eITO. This new technique works immediately and is thus an effective short-term intervention of potential value in the intensive care unit.

[Value of various intra- and extraoral therapeutic procedures for treatment of obstructive sleep apnea and snoring]

BACKGROUND

Recently intra- and extraoral devices are increasingly used in order to treat obstructive sleep apnea (OSA) and snoring. We examined the value of some devices according to the literature and our own results.

PATIENTS AND METHODS

The mandibular advancing devices aim at increasing upper airway diameter. The active part of the tongue extending device (SnorEx) is a stamp connected to a piston which exerts pressure at the base of the tongue causing its forward displacement; we studied 23 patients. The principle of an optically stimulating system ("eye-cover", Snore-Stop) consists of a microphone and light diods which are integrated in the eye-cover. After detecting acoustic signals (for example snoring) optical stimuli are generated in front of the eyes, which are thought to induce arousals causing a change of body position and the reduction of the snoring and apneas; we measured 24 patients. The principle of the tongue-retainer (Snore-Master) is the fixation of the tongue in a ventral position, which is thought to enlarge the mesopharyngeal area; we studied 14 patients. The nose plaster (Breathe-Right) contains an elastic spine that pulls the alae nasi cranial. This manipulation is thought to increase the diameter of the nostril and reduce the airway resistance. We measured 30 patients with obstructive sleep apnea and 20 snoring subjects without obstructive sleep apnea.

RESULTS

Regarding the mandibular advancing due to different appliance designs and study protocols variable success rates have been documented. In patients with mild to moderate obstructive sleep apnea a reduction of the sleep related breathing disorder could be shown. Non compliance (NC) to the tongue extending device was 75% (17/23). Non-compliance-patients were characterized by unacceptable local-side-effects of the prosthesis, lacking improvement of symptoms and of the respiratory disturbance index. Both tongue-retainer and -extensor are characterized by a high incidence of local side effects. Neither the eye-cover nor the nose plaster could improve the severity of obstructive sleep apnoe or snoring. In contrast to another study we could not show a significant effect of the tongue-retainer.

CONCLUSIONS

Neither the nose plaster nor the optical stimulating device influenced the degree of obstructive sleep apnea and snoring. There are conflicting data regarding the tongue retainer. The high rate of non-compliant subjects and the low efficacy of the tongue extending prosthesis precludes large-scale use of this treatment modality in patients with obstructive sleep apnoe and snoring. In selected individuals suffering from a mild to moderate degree of obstructive sleep apnea with CPAP-inefficiency and -incompliance the mandibular advancing principle may be an therapeutic alternative to CPAP.

[Optical stimulation method (Snore-Stop) and tongue retainer (Snore-Master) without relevance in therapy of obstructive sleep apnea and snoring]

Recently intra- und extraoral devices are increasingly used in order to treat obstructive sleep apnea and snoring. We examined the value of an optically stimulating system ("eye-cover", Snore-Stop) and a tongue-retainer (Snore-Master) as treatment of the obstructive sleep apnoe or snoring. In case of the eye-cover is a microphone integrated, which detects acoustic signals (e.g. snoring). After detection of snoring optical stimuli are generated in front of the eyes. This is intended to induce an arousal of the patient, without awaking him, causing a change of body position and this reduces the snoring or apneas. For the examination of the eye-cover in 26 patients (23 men, 55.6 +/- 10.3 years) polygraphic studies were performed while sleeping one night with the eye-cover and one night without, respectively. Visual analogue scales (VAS) were used in order to measure quality of life and sleep and the adverse effects of the device. To examine the tongue-retainer 14 patients (13 men, aged 52.9 +/- 11.8 years) were measured polygraphically. Again the subjective scores were assessed using the VAS. The principle of the tongue-retainer is to create a hollow space in front of the teeth, in which the tongue is positioned. Fixation of the tongue in this ventral position is thought to enlarge the mesopharyngeal area in order to reduce the upper airway obstruction. For both devices the index of snoring, the apnea-hypopnea-index, the index of desaturation, the mean and minimal SaO2 and SaO2 < 90 % in % of the night did not change significantly. Furthermore the subjective perception of the patients concerning their quality of sleep and life did not change. Moreover, despite of an adequate adaptation-period the use of the tongue-retainer was associated with considerable adverse effects. Neither the eye-cover nor the tongue-retainer could improve the severity of obstructive sleep apnoe or snoring.

A new tongue advancement technique for sleep-disordered breathing: side effects and efficacy

We examined the efficacy and the acceptance of an oral device (SnorEx) causing a forward displacement of the tongue for the treatment of sleep-disordered breathing (SDB). Twenty-three consecutive subjects with SDB were investigated. Noncompliance (NC) of use of the oral appliance was observed in 74% (17 of 23) of the subjects. NC patients were characterized by unacceptable local side effects of the prosthesis, lacking improvement of indicators of daytime well-being, and a missing reduction of the respiratory disturbance index (RDI). The device was tolerated without side effects in 26% (6 of 23) of the subjects. In these compliant (C) subjects the RDI, EDS, and snoring improved significantly (p < 0.05) compared with baseline values. After 6 mo using the device, five of the six C patients were still using it. We conclude that the high rate of noncompliance and the low efficacy of the SnorEx prosthesis preclude large-scale use of this treatment modality in patients with SDB and snoring since the local side effects are the principal cause of NC. No useful predictive parameter of treatment compliance or treatment success was found. Thus, this dental appliance should be prescribed only for selected patients failing other treatment modalities seen by an experienced sleep-disorders specialist.

Comparison of two different modes for noninvasive mechanical ventilation in chronic respiratory failure: volume versus pressure controlled device

The most commonly used mode of noninvasive mechanical ventilation (NMV) is volume-controlled intermittent positive pressure ventilation (IPPV). Pressure support ventilation has recently become increasingly popular, but its merits have not been clearly defined. In an open, nonrandomized follow-up study, we evaluated two modes of NMV, volume-controlled (IPPV) and pressure-controlled ventilation (PCV) over 6 months in 30 consecutive patients (24 males and 6 females, aged 49 +/- 19 yrs) with chronic respiratory failure (CRF). The baseline assessments comprised both physiological and subjective data. In all cases, nasal IPPV was initially administered for 1 month, followed by a second month of nasal PCV. Thereafter, responders or nonresponders to PCV were defined according to the patients' subjective symptom score and/or the recurrence of hypercapnia. During the IPPV phase, in all but two patients the subjective and objective parameters improved significantly. During the following 1 month PCV phase, stabilization was maintained in 18 patients ("responders"), while 10 patients were defined as "nonresponders". In nonresponders, hypercapnia increased (arterial carbon dioxide tension (Pa,CO2): 5.7 +/- 0.4 to 6.6 +/- 0.5 kPa; p < 0.05) and symptom scores decreased. Compared with responders, nonresponders had a lower mean nocturnal arterial oxygen saturation (Sa,O2) (p < 0.05) and a higher daytime Pa,CO2 (p < 0.05) at baseline. We con clude that the majority of patients suffering from chronic respiratory failure who are initially satisfactorily ventilated with intermittent positive pressure ventilation may also be adequately maintained with pressure-controlled ventilation. However, there is a subgroup with more severe chronic respiratory failure at baseline, in whom pressure-controlled ventilation is inadequate. After 4 weeks of treatment with pressure-controlled ventilation, the subjective scores and the arterial carbon dioxide tension values reliably distinguished between long-term responders and nonresponders to pressure-controlled ventilation.

Benzodiazepine receptor antagonist (flumazenil) does not affect sleep-related breathing disorders

Benzodiazepine drugs may impair breathing during sleep, leading to the development of sleep-disordered breathing or, in subjects with sleep apnoea, an increase in the severity of pre-existing apnoeas. Flumazenil is a selective benzodiazepine-antagonist. We hypothesized that endogenous ligands of benzodiazepine receptors might contribute to the pathogenesis of obstructive sleep apnoea syndrome (OSAS) and that the intensity of OSAS could, therefore, be reduced by flumazenil. Ten male patients (mean age 55 yrs, mean body mass index 42.4 kg.m-2, mean apnoea index (AI) 53.5 and mean respiratory disturbance index (RDI) 74.2) were investigated. None of the patients had been treated for OSAS prior to the study. The study design was randomized, single-blind, placebo-controlled and cross-over. On the first or second study night, patients were randomly assigned to receive i.v. flumazenil (2 mg) or placebo (0.9% NaCl) between 01:00 and 01:30 h. Comparing the polysomnographic results of the placebo night and the flumazenil night in all 10 patients, no significant differences were found regarding obstructive events or sleep architecture. Accordingly, the data concerning sleep-disordered breathing and sleep stages during the 30 min period prior to and the 30 min period following the administration of flumazenil did not differ. It is concluded that endogenous ligands of the benzodiazepine receptor play no role in the pathogenesis of obstructive sleep apnoea syndrome, since respiratory and sleep data are not altered by flumazenil. Therefore, attempts to treat obstructive sleep apnoea syndrome with flumazenil do not seem to be warranted.

[Intermittent self-ventilation after respirator weaning]

BACKGROUND

Weaning from the mechanical ventilator often proves to be difficult after prolonged ventilation due to excessive load or decreased capacity of the respiratory muscles. In the present retrospective study we examined the impact of the nocturnal mechanical ventilation during the "post-weaning-period" of long-term ventilated patients.

PATIENTS AND METHODS

We studied 43 patients (23 men, 59.1 +/- 14.6 years) with chronic respiratory failure who were transmitted from external ICUs after a mechanical ventilation period of 57.5 +/- 60.3 days. The weaning regime consisted of an individually adapted volume-cycled ventilation. If the patients were hypercapnic (pCO2 > 48 mm Hg) after the first 24-hour-period of spontaneous breathing without supplemental oxygen nocturnal mechanical ventilation was initiated.

RESULTS AND CONCLUSIONS

In a retrospective study we could show that the decision to initiate invasive or noninvasive nocturnal mechanical ventilation after successful weaning primarily depends on the question whether a chronic hypercapnic respiratory failure persisted also after weaning from long-term mechanical ventilation. In about 40% of unselected patients nocturnal mechanical ventilation stabilized the weaning success whereas 60% of the patients did not need any further nocturnal mechanical ventilation.

[Intermittent self-ventilation in torsion scoliosis. Possibilities and limits]

BACKGROUND

In patients with hypercapnic respiratory failure due to restrictive lung diseases home mechanical ventilation leads to improvement of daytime blood gases and symptoms. In this paper we regard the possible pitfalls and complications associated with intermittent mechanical ventilation in patients with kyphoscoliosis.

PATIENTS AND METHODS

From 1990 to 1994 we treated 30 patients suffering from severe kyphoscoliosis with home mechanical ventilation.

RESULTS AND CONCLUSIONS

1. As our cases show in the prehospital phase before initiating home mechanical ventilation there is still room for the outpatient pneumologists to improve their knowledge and awareness of symptoms and treatment of chronic respiratory failure. 2. In the subsequent inpatient phase and specialised center must be aware and experienced in regarding possible problems inherent with home mechanical ventilation. 3. After discharge during chronic home mechanical ventilation a good cooperation between the center, patient, relatives, general services and general pulmolgists is necessary. The centers should offer training courses for the caring persons and general pneumologists.

Long-term lung sequelae following accidental chlorine gas exposure

Acute exposure to sublethal doses of chlorine gas resulted in persistent pulmonary symptoms in 3 patients who had no past history of respiratory disease. The patients complained of intermittent dyspnea in association with respiratory irritants and physical exertion for more than 2.5 years postexposure. Four months after the accident bronchoalveolar lavage showed an inflammatory cell reaction, whereas 16 months later the differential cytology proved nearly normal. Moderate to severe nonspecific bronchial hyperresponsiveness was assessed in intervals of 4, 20 and 30 months after the accident. All patients showed the typical features of the reactive airways dysfunction syndrome defined as an asthma-like occupational illness after an acute exposure to highly concentrated respiratory irritants. We conclude that a single high exposure to chlorine gas may lead both to acute respiratory injury and to long-term reactive airway dysfunction with typical symptoms of inflammatory changes of the airways and nonspecific bronchial hyperresponsiveness.

[Effectiveness of intermittent self-ventilation after ventilator weaning]

The essential cause for long-term mechanical ventilation with unweanability from respirator is chronic failure of the inspiratory muscles. Principally two different causes exist for chronic respiratory failure: Primary pulmonary diseases with overload or load imbalance of primarily uncompromised respiratory muscles, and neuromuscular diseases with a significant decrease in respiratory muscle capacity. Intermittent nocturnal ventilation (INV) leads to recovery by unloading the respiratory pump. In the present retrospective study we examined the value of INV in the "post-weaning-phase" for previously unweanable, long term ventilated patients. In two years (1993 and 1994) 43 patients who had been ventilated for 57.5 +/- 60.3 days in outward intensive care units (ICU) in a predominantly assisted mode we could wean from the respirator within 8.4 +/- 5.5 days by means of consequently applying an individually adapted, volume cycled weaning regime. In all patients, on admission to our ICU and before discharge blood gases, P0.1, Pimax, breathing frequency and tidal volume were measured during spontaneous breathing. After weaning in about 40% of our patients we decided to initiate INV with intermittent positive pressure ventilation (IPPV). The indication for INV after weaning depended on whether a chronic hypercapnic respiratory failure continued to be demonstrable. In this group of patients, INV was the essential stabilizing factor for continuous weaning success, as the respiratory muscles recovered during the ensuing inpatient phase and the daytime PaCO2 normalised. In most of our patients (14 out of 18) INV could be performed non-invasively via breathing masks. Only 4 out of 18 patients continued to be long-term ventilated invasively via tracheostomy. The remaining patients (25 out of 43) showed normoventilation at daytime during the ensuing inpatient phase so they did not need INV. At the time of the patients' referral to our ICU, there was no predictive value regarding the ultimate indication for INV after weaning from respirator.