[Interdisciplinary Perspectives on the Role of Aerosol Transmission in SARS-CoV-2 Infections]. / Interdisziplinäre Perspektiven zur Bedeutung der Aerosolübertragung für das Infektionsgeschehen von SARS-CoV-2.

The relevance of aerosols for the transmission of the Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2) is still debated. However, over time, in addition to distancing and hygiene rules, aerosol physics-based measures such as wearing face masks and ventilating indoor spaces were found to be efficient in reducing infections. In an interdisciplinary workshop "Aerosol & SARS-CoV-2" of the Association for Aerosol Research (GAeF) in cooperation with the German Society for Pneumology and Respiratory Medicine (DGP), the Professional Association of General Air Technology of the VDMA, the German Society for Virology (GfV), the Health Technology Society (GG) and the International Society for Aerosols in Medicine (ISAM) under the auspices of the Robert Koch Institute (RKI) in March 2021, the need for research and coordination on this topic was addressed. Fundamental findings from the various disciplines as well as interdisciplinary perspectives on aerosol transmission of SARS-CoV-2 and infection mitigation measures are summarized here. Finally, open research questions and needs are presented.

Bench testing of noninvasive ventilation masks with viral filters for the protection from inhalation of infectious respirable particles.

During the beginning of the SARS-CoV-2 pandemic, there was a shortage of masks and respirators for the protection of health care professionals. Masks for noninvasive ventilation (NIV) in combination with viral-proof filters, worn by healthcare workers, could serve as an alternative protection measure. We determined the simulated protection factor (SPF) of such devices in comparison to conventional surgical masks, N95, and FFP3 respirators. Masks and respirators were mounted on a ventilated mannequin head in a test-chamber. Isotonic saline containing 150 MBq 99mTC-DTPA (99mTc-diethylenetriamine pentaacetate (DTPA) was nebulized inside the box. The aerosol had a mass median aerodynamic diameter of 0.6 ± 0.4 µm. SPFs were measured using radioactive DTPA particles in the mannequin test system by calculating the ratio of unfiltered particles (Pu) and filtered particles (Pf) for each tested device (SPF = Pu/Pf). Simulated protection factors were 15.6 ± 3.6 for a ResMed AcuCare mask plus filter, 3.5 ± 0.2 for a ResMed Mirage Quattro FX mask plus filter, 9.5 ± 0.8 for a Loewenstein JOYCEclinc FF mask plus filter, 1.9 ± 0.2 for a surgical mask with a rubber band, 2.7 ± 0.7 for a surgical mask with ribbons, 2.3 ± 0.3 for an FFP3 respirator, and 3.6 ± 1.3 for an N95 respirator. The ResMed AcuCare and the Loewenstein JOYCEclinic FF mask were more effective than any other of the tested devices (p < 0.001). In conclusion, masks normally used for NIV with viral-proof filters can effectively filter respirable particles.

Hypoxic, anemic and cardiac hypoxemia: When does tissue hypoxia begin? / Hypoxische, anämische und kardial bedingte Hypoxämie: Wann beginnt die Hypoxie im Gewebe?

In case of hypoxemia, the oxygen content is often still in the lower normal range, so that there is no hypoxia in the tissue. If the hypoxia-threshold is reached in the tissue in hypoxic, anemic and also cardiac-related hypoxemia, identical counterregulations occur in the cell metabolism, regardless of the cause of hypoxemia. In clinical practice, this pathophysiologic fact is sometimes ignored, although depending on the cause of hypoxemia, assessment and therapy vary widely. While restrictive and generally accepted rules are specified in the transfusion guidelines for anemic hypoxemia, in the case of hypoxic hypoxia, the indication for invasive ventilation is made very early. The clinical assessment and indication are limited to the parameters oxygen saturation, oxygen partial pressure and oxygenation index. During the corona pandemic, misinterpretations of pathophysiology have become evident and may have led to unnecessary intubations. However, there is no evidence for the treatment of hypoxic hypoxia with ventilation. This review addresses the pathophysiology of the different types of hypoxia focusing on the problems associated with intubation and ventilation in the intensive care unit.

Conservative management of COVID-19 associated hypoxaemia.

This correspondence argues that happy hypoxaemic patients should not be intubated as long as they remain happy https://bit.ly/3csrpWO.

Conservative management of COVID-19 associated hypoxaemia.

Treat hypoxia, not hypoxaemia https://bit.ly/3hwPLCL.

Conservative management of COVID-19 associated hypoxaemia.

BACKGROUND: Invasive mechanical ventilation of hypoxaemic coronavirus disease 2019 (COVID-19) patients is associated with mortality rates of >50%. We evaluated clinical outcome data of two hospitals that agreed on a predefined protocol for restrictive use of invasive ventilation where the decision to intubate was based on the clinical presentation and oxygen content rather than on the degree of hypoxaemia. METHOD: Data analysis was carried out of patients with positive PCR-testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), typical history, and symptoms and pulmonary infiltrates who exhibited oxygen saturation values of <93%. RESULTS: We identified 78 patients who met the inclusion criteria. The oxygen saturation nadir was 84.4±6.5% for the whole group. 53 patients (68%) received nasal oxygen (group 1), 17 patients (22%) were treated with nasal high-flow continuous positive airway pressure (CPAP), noninvasive ventilation or a combination thereof (group 2), and eight patients (10%) were intubated (group 3). The Horovitz index was 216±8 for group 1, 157±13 for group 2 and 106±15 for group 3. Oxygen content was 14.5±2.5, 13.4±1.9 and 11.6±2.6 mL O2·dL-1 for the three respective groups. Overall mortality was 7.7%; the mortality of intubated patients was 50%. Overall, 93% of patients could be discharged on room air. CONCLUSION: Permissive hypoxaemia where decisions for the level of respiratory therapy were based on the clinical presentation and oxygen content resulted in low intubation rates, low overall mortality and a low number of patients who require oxygen after discharge.

Evaluation and discussion of handmade face-masks and commercial diving-equipment as personal protection in pandemic scenarios.

OBJECTIVE: Pandemic scenarios like the current Corona outbreak show the vulnerability of both globalized markets and just-in-time production processes for urgent medical equipment. Even usually cheap personal protection equipment becomes excessively expensive or is not deliverable at all. To avoid dangerous situations especially to medical professionals, but also to affected patients, 3D-printer and maker-communities have teamed up to develop and print shields, masks and adapters to help the medical personnel. In this study, we investigate three home-made respiratory masks for filter and protection efficacy and discuss the results and legal aspects. MATERIALS AND METHODS: A home-printed respiratory mask with a commercial filter, a scuba-diving mask with a commercial filter and a mask sewn from a vacuum cleaner bag were investigated with 99mTc-labeled NaCl-aerosol, and the respective filter-efficacy was measured under a scintigraphic camera. RESULTS: The sewn mask from a vacuum cleaner bag had a filter efficacy of 69.76%, the 3D-printed mask of 39.27% and the scuba-diving mask of 85.07%. CONCLUSION: Home-printed personal protection equipment can be a-yet less efficient-alternative against aerosol in case professional masks are not available, but legal aspects of their use and distribution have to be kept in mind in order to avoid compensation claims.

[Tremendous Increase of Home Care in Ventilated and Tracheostomized Patients - Reasons, Consequences, Solutions]. / Explosive Zunahme der häuslichen Krankenpflege bei Beatmeten und Tracheotomierten.

Since 2005, invasive long-term ventilation in Germany has increased significantly from around 1000 to 20 000 patients in Germany. Due to complex home care, the health care system incurs additional costs of around 4 billion euros per year. In addition, in the last 2 - 3 years more tracheostomized patients have been discharged home without ventilation (usually after stroke), and they receive the same complex home care. These patients have almost never been given the chance of a professional weaning trial by a weaning center. They are discharged from hospitals directly into the care. As a result, the quality of care is significantly worse than traditional care with structured discharge management via a weaning center. The solutions are difficult to find due to the interface problems between inpatient and outpatient care and the different organizational structures with different delivery systems. Possible solutions are shown, but most of them require a change in the law.

[Early pulmonary rehabilitation after long term mechanical ventilation]. / Pneumologische Frührehabilitation nach Langzeitbeatmung.

BACKGROUND: The term early rehabilitation is defined as a rehabilitation that begins in the early phase after acute illness and is statutory positioned in §â€Š39SGB V. Aim of this investigation is to describe the quality of outcome of pulmonary early rehabilitation. METHOD: Prospective census of functional parameters, status of ventilation and discharge-disposition in a specialized unit for early pulmonary rehabilitation over a period of one year. RESULTS: Out of 190 patients 179 (94.2 %) were previously invasively ventilated. During the treatment period of 39 ±â€Š17 days, FAM-Index increased from 84.4 ±â€Š19.8 to 118.5 ±â€Š23.3 (Ci 30.9 - 37.3, Cohen'd 1.58; p < 0.001), Barthel-Index from 30.5 ±â€Š13.8 to 58.3 ±â€Š16.2 (Ci 25.4 - 33.8, Cohen's d 1.4; p < 0.001) six minute walking distance from 12.9 ±â€Š40.1 m to 131.4 ±â€Š85.2 m (Ci 105.6 - 131.4 m, Cohn's d 1.78; p < 0.001). Patients were less likely to be receive further post-discharge rehabilitation if they were ventilated. CONCLUSION: Patients admitted to the early pulmonary rehabilitation unit were severely compromised, however quality of outcome was favourable and independent of the breathing status (spontaneously breathing vs. non-invasive ventilation or invasive ventilation). Finding discharge dispositions appeared to be more difficult if patients were ventilated.

Spontaneous-timed versus controlled noninvasive ventilation in chronic hypercapnia - a crossover trial.

Background: There is an ongoing debate about optimal ventilator modes and settings during noninvasive ventilation (NIV). Objectives: To compare the effect of spontaneous-timed (ST) and controlled NIV on carbon dioxide reduction in patients suffering from chronic hypercapnia. Methods: Night and daytime blood gas analysis, lung function tests and 6 minute walking distance tests (6MWD) were done before and after every 6-week treatment. Results: This randomized prospective crossover trial included 42 patients. Pooled data analysis showed a decrease of nocturnal CO2 from 54.8±5.9 mmHg to 41.6±5.5 mmHg during ST ventilation (p<0.01) and from 56.2±7.5 mmHg to 42.7±5.4 mmHg during controlled NIV (p<0.01) with no difference between treatment forms (p=0.30). Daytime CO2 levels decreased from 49.3±5.5 mmHg to 45.6±4.5 mmHg when spontaneous timed ventilation was applied (p<0.01) and from 52.2±6.8 mmHg to 44.9±21114.4 mmHg in case of controlled ventilation (p<0.01) The amount of CO2 reduction was 3.8±5.6 mmHg after ST mode and 7.3±6.8 mmHg controlled ventilation (p<0.05). Nocturnal ventilator use was 5.7±2.1 and 6.7±2.3 hours for ST and controlled ventilation respectively (p=0.02). There was no effect on walking distance and lung function. Conclusion: Controlled NIV showed improved compliance compared to ST ventilation. We observed similar CO2 reductions during nocturnal ventilation, however controlled ventilation achieved a higher reduction of daytime CO2 levels.

Cost-effectiveness of the COPD Patient Management European Trial home-based disease management program.

Purpose: Efficient management of COPD represents an international challenge. Effective management strategies within the means of limited health care budgets are urgently required. This analysis aimed to evaluate the cost-effectiveness of a home-based disease management (DM) intervention vs usual management (UM) in patients from the COPD Patient Management European Trial (COMET). Methods: Cost-effectiveness was evaluated in 319 intention-to-treat patients over 12 months in COMET. The analysis captured unplanned all-cause hospitalization days, mortality, and quality-adjusted life expectancy. Costs were evaluated from a National Health Service perspective for France, Germany, and Spain, and in a pooled analysis, and were expressed in 2015 Euros (EUR). Quality of life was assessed using the 15D health-related quality-of-life instrument and mapped to utility scores. Results: Home-based DM was associated with improved mortality and quality-adjusted life expectancy. DM and UM were associated with equivalent direct costs (DM reduced costs by EUR -37 per patient per year) in the pooled analysis. DM was associated with lower costs in France (EUR -806 per patient per year) and Spain (EUR -51 per patient per year), but higher costs in Germany (EUR 391 per patient per year). Evaluation of cost per death avoided and cost per quality-adjusted life year (QALY) gained showed that DM was dominant (more QALYs and cost saving) in France and Spain, and cost-effective in Germany vs UM. Nonparametric bootstrapping analysis, assuming a willingness-to-pay threshold of EUR 20,000 per QALY gained, indicated that the probability of home-based DM being cost-effective vs UM was 87.7% in France, 81.5% in Spain, and 75.9% in Germany. Conclusion: Home-based DM improved clinical outcomes at equivalent cost vs UM in France and Spain, and in the pooled analysis. DM was cost-effective in Germany with an incremental cost-effectiveness ratio of EUR 2,541 per QALY gained. The COMET home-based DM intervention could represent an attractive alternative to UM for European health care payers.

Impact of breathing pattern on work of breathing in healthy subjects and patients with COPD.

The impact of the respiratory pattern on respiratory muscle workload represents an unresolved controversy and is important for the treatment of patients with respiratory disorders and respiratory muscle failure. We designed this study to investigate the relationship of respiratory pattern and inspiratory workload. We measured esophageal pressure and inspiratory flow and calculated work of breathing, tidal volume and respiratory rate. Ten healthy subjects and 10 COPD patients participated and performed five different breathing patterns starting from respiratory rate 12 and tidal volume 1l or quiet breathing, respectively. They were instructed to increase respiratory rate by 50 and 100% as well as tidal volume by 50 and 100% while maintaining constant minute-ventilation. In healthy subjects Delta VT was the single best parameter to predict Delta WOB (R=0.958, R(2)=0.918, p<0.0001). The relationships of changes in tidal volume, respiratory rate and rapid shallow breathing index to changes in WOB were linear. In the COPD Delta VT was also the single best parameter to predict changes in work of breathing (R=0.777, R(2)=0.604, p<0.0001), however the relation of respiratory rate and rapid shallow breathing index to work of breathing was exponential (e-function) with lower indices generating higher workload. We conclude that rapid shallow breathing might be a strategy to compensate for burdensome respiratory mechanics. In COPD patients however we observed a critical threshold where any further increases in rapid shallow breathing index will be of no further benefit.

Exercise endurance before and after long-term noninvasive ventilation in patients with chronic respiratory failure.

BACKGROUND: Noninvasive mechanical ventilation (NIV) is known to reduce hypoventilation and improves respiratory and peripheral muscle endurance in patients with chronic respiratory failure (CRF) due to thoracic restriction. OBJECTIVES: To compare the effect of short-term NIV on endurance in patients with CRF due to thoracorestriction and chronic obstructive pulmonary disease (COPD) and to evaluate differences in spiroergometric data during exercise testing. METHODS: Thirty-five patients with CRF due to COPD and 24 patients with CRF due to thoracorestriction entered the trial. Constant work rate exercise testing at 75% of the maximal workload, pulmonary function and arterial blood gas testing were performed before and after 3 months of NIV. Measurements were compared between and within groups. RESULTS: The non-COPD group increased their exercise time significantly from 4.7 +/- 1.81 to 6.59 +/- 3.15 min (p = 0.0032). There was no change in the COPD group (4.57 +/- 2.19 min before and 5.39 +/- 3.09 min after NIV, p = 0.09). CO(2) levels at rest fell in both groups (COPD 52.30 +/- 7.77 to 46.06 +/- 4.61 mm Hg and non-COPD 47.82 +/- 5.19 to 43.79 +/- 4.15 mm Hg). While COPD patients increased their minute ventilation (13.47 +/- 2.73 to 14.88 +/- 2.67 l/min), non-COPD patients decreased their oxygen uptake from 6.27 +/- 1.61 to 5.54 +/- 1.35 ml/kg. CONCLUSIONS: NIV improved endurance only in the non-COPD group. This and the reduction in CO(2) are achieved by lowering energetic requirements. COPD patients though decreased their resting CO(2) by increased minute ventilation.

[TISS-28 in difficult to wean patients after long-term mechanical ventilation]. / Stellenwert des TISS-28-Scores in der schwierigen Entwöhnung vom Respirator.

PURPOSE: To compare the Therapeutic Intervention Scoring System (TISS) 28 in difficult to wean patients before and after transfer to a weaning center. PATIENTS AND METHODS: Using TISS-28, the authors investigated the difference between regular intensive care units (ICUs) and the respiratory ICU (RICU) of their hospital in difficult to wean patients after long-term mechanical ventilation (MV). Special emphasis was placed on the appropriateness of TISS-28 to cover the specific weaning activities. 63 tracheotomized patients ventilated for more than 14 days were included. RESULTS: In total, 15.9% of patients were not weaned, 20.6% of population was successfully weaned with noninvasive ventilation (NIV), and 63.5% of patients was successfully weaned without NIV. The transfer of patients from other ICUs to a weaning facility resulted in a significant reduction of total TISS-28 from 29.5 to 23.8 points (p<0.001) on average. CONCLUSION: The high weaning success rate in a specialized facility is associated with a significant reduction of TISS-28 scores. The use of TISS-28 in a weaning center for patients with prolonged MV to measure workload does not adequately mirror the efforts by physicians, nurses, physiotherapists, and other health-care personnel.

Short-term effect of controlled instead of assisted noninvasive ventilation in chronic respiratory failure due to chronic obstructive pulmonary disease.

BACKGROUND: Noninvasive positive-pressure ventilation (NPPV) unloads respiratory muscles. Spontaneous-breathing ventilation modes require patient effort to trigger the ventilator, whereas controlled modes potentially economize on patient triggering effort and thus achieve more complete respiratory muscle rest. Data on controlled NPPV have not been published to date. We hypothesize that controlled ventilation is feasible in patients with hypercapnic chronic obstructive pulmonary disease. METHODS: We measured blood gas values, respiratory muscle strength, spontaneous breathing pattern, and lung function before and after a 3-month period of NPPV in 305 patients (213 male, mean +/- SD age 61.3 +/- 8.6 y). The subjects used a controlled NPPV mode when they could tolerate it. RESULTS: Ninety-one percent of the patients were able to adapt to a controlled NPPV mode. In those patients, daytime P(CO(2)) decreased from 56.7 +/- 7.5 mm Hg to 47.5 +/- 6.6 mm Hg (p < 0.001) and P(O(2)) increased from 49.2 +/- 8.8 mm Hg to 56.2 +/- 8.5 mm Hg (p < 0.001). Their mean maximum inspiratory pressure increased from 42.3 +/- 16.9 cm H(2)O to 48.4 +/- 18.0 cm H(2)O (p < 0.001). Their mean vital capacity increased from 1.89 +/- 0.62 L to 1.99 +/- 0.67 L (p = 0.004). And their spontaneous breathing pattern became less rapid and shallow. CONCLUSIONS: Controlled NPPV is feasible in patients with hypercapnic chronic obstructive pulmonary disease. We observed improved blood gas values, lung function, and inspiratory muscle strength.

[Clinical Year in Review - advanced COPD]. / Clinical Year in Review - fortgeschrittene COPD ("chronic obstructive lung disease").

COPD is a frequent disease, affecting approximately one in four smokers. In older patients > 70 years of age, the proportion of individuals who never have smoked increases up to one in three individuals. Severe disease is present in 10%, and the limitation of performance is usually caused by airway obstruction, in a smaller portion of patients by the loss of alveolar surface (emphysema). After medical treatment with antiobstructive and anti-inflammatory drugs, oxygen remains a major therapy option. With it, hypercapnic patients benefit most from long-term therapy. Patients with predominant emphysema benefit most from high-flow (6-8 l/min) oxygen therapy during exercise. Permanent yellow or greenish sputum decoloration is suggestive of chronic bacterial colonization. This group of patients may benefit from a permanent inhalative therapy with antibiotics (mainly aminoglycosides). There is growing evidence from current literature to support this concept. If dyspnea is severe, especially during mild exercise, a subset of patients might benefit from the use of long-acting morphium. Goal of this therapy is to downregulate breathing control. Predominantly "pink puffers" seem to respond. A dose of 10-20 mg will usually be sufficient. Life-threatening hypercapnia is usually not observed with this form of therapy. Noninvasive ventilation is an option for patients with severe hypercapnia. Thereby, ventilatory pressure or inspiratory volume should be selected to effectively unload the respiratory muscles. This will increase quality of life. Life span is likely to be prolonged, however, comparative data where patients were effectively ventilated (as seen on the reduction of hypercapnia) are missing. A multicenter trial addressing this topic is currently being conducted in Germany. Independent of the severity of COPD, patients in general benefit from physical training with alternation of endurance and interval training being most effective. This will decrease the number of hospital admissions and probably mortality as well. Lung volume reduction surgery virtually treats lung hyperinflation. Bullectomy is still considered effective for isolated bullous emphysema as well as lobectomy, if this portion of the lung is without function. Shaving procedures are still associated with high rates of complications and should only be performed in selected cases. Effectiveness of endoscopic lung volume reduction surgery by implantation of plugs or valves cannot be assessed yet. First data are rather disappointing. Ultimate alternative remains lung transplantation with life expectancy ranging between 5-6 years independent of age. Indeed, consequent application of previously described measures might preserve a stable state over many years.

[How much pulmonary diagnostics does the family physician need?]. / Wie viel pneumologische Diagnostik muss der Hausarzt können? Spirometrie sollte Standard sein.

Spirometry plays the major role in pulmonary diagnostics in the family practice, but is still used much too rarely on patients with respiratory symptoms. Every patient with shortness of breath or a chronic, persistent cough should have spirometry performed. Needless to say, taking a selective medical history and auscultation of the lungs and heart are additional, important pillars for making a diagnosis. Measurement of the peak expiratory flow (PEF) can be especially helpful in emergencies. Pulse oxymetry also aids in the assessment of acute situations and additionally, can provide valuable information in the follow-up treatment of chronic respiratory diseases.

Effect of home mechanical ventilation on inspiratory muscle strength in COPD.

BACKGROUND: The mechanism responsible for chronic hypercapnic respiratory failure (HRF) in patients with COPD remains unclear. In this study, we tested the hypothesis that chronic HRF in patients with COPD is associated with low-frequency fatigue (LFF) of the diaphragm. METHODS: To test this hypothesis, we measured the twitch transdiaphragmatic pressure (Tw Pdi) elicited by stimulation of the phrenic nerves in 25 patients with chronic HRF (mean [+/- SD] Paco(2), 55.2 +/- 5.2 mm Hg) due to COPD before and 2 months after the initiation of noninvasive mechanical ventilation (NIV) [pressure-cycled ventilation with inspiratory positive airway pressure of 19.0 +/- 2.5 cm H(2)O]. We reasoned that had LFF been present, Tw Pdi should rise after effective NIV. RESULTS: The treatment compliance with NIV was good (median of machine usage was 7.1 h per night). Paco(2) decreased from 55.2 +/- 5.2 to 48.8 +/- 5.9 mm Hg (p < 0.001), and Pao(2) increased from 53.1 +/- 5.9 to 57.7 +/- 7.0 mm Hg (p = 0.007). Mean Tw Pdi at baseline was 11.1 +/- 6.6 cm H(2)O and after treatment was 11.7 +/- 7.2 cm H(2)O (not significant). Also, maximal static inspiratory mouth pressure did not change significantly (44.3 +/- 15.9 cm H(2)O vs 46.5 +/- 19.7 cm H(2)O). CONCLUSION: LFF of the diaphragm does not accompany chronic HRF in patients with COPD.

Health-related quality of life in patients with chronic respiratory failure after long-term mechanical ventilation.

STUDY OBJECTIVES: This study was aimed at assessing health-related quality of life (HRQL) in patients with chronic respiratory failure (CRF) and long-term survival following prolonged intensive care mechanical ventilation. DESIGN: Observational cohort study. SETTING: Patients with CRF who had been transferred to our specialized weaning centre due to prolonged mechanical ventilation (>14 days) and weaning failure. PATIENTS AND PARTICIPANTS: Out of 87 long-term survivors (>6 months), 73 patients (mean age: 60.3+/-13.6 years, chronic obstructive pulmonary disease (COPD, 43%), thoraco-restrictive (21%) or neuromuscular disorders (15%), various chronic diseases (22%)) returned the MOS 36-Item Short-Form Health Status Survey (SF-36) and the St. George's respiratory questionnaire (SGRQ). MEASUREMENTS AND RESULTS: The total ventilation time was 38.7+/-45.9 days. The time between discharge from ICU and HRQL assessment was 31.0+/-22.2 months. Physical health was markedly reduced compared to general population norm, but mental health was mildly impaired. HRQL was comparable to patients with stable CRF receiving non-invasive ventilation who did not need prolonged invasive MV. In addition, general HRQL was better in patients with restrictive respiratory disease compared to patients with neuromuscular diseases (P<0.05). Physiological parameters such as blood gases or lung function parameters were not correlated to any HRQL measurements. CONCLUSIONS: In patients with CRF surviving prolonged ventilation on ICU, the presence of CRF itself is the major determinant of HRQL. Here, the underlying cause of CRF is the major factor which determines the degree of HRQL impairment with patients suffering from restrictive ventilatory disorders reporting the best HRQL when compared to patients with COPD or neuromuscular diseases. Despite severe physical handicaps due to CRF mental health is only mildly compromised.