Oronasal versus Nasal Masks for Non-Invasive Ventilation in COPD: A Randomized Crossover Trial.

PURPOSE: The impact of oronasal and nasal masks on the quality of nocturnal non-invasive ventilation (NIV) needs to be clarified. This trial was designed to compare the impact of oronasal and nasal masks on the objective quality and subjective acceptance of nocturnal NIV in COPD-patients. PATIENTS AND METHODS: In a randomized crossover trial, 30 COPD-patients with well-established high-intensity NIV (mean inspiratory/expiratory positive airway pressure 26±3/5±1 cmH2O, mean respiratory back-up rate 17±1/min) were ventilated for two consecutive nights on oronasal and nasal masks, respectively. RESULTS: Full polysomnography, nocturnal blood gas measurements, and subjective assessments were performed. There was a tendency towards improved sleep efficiency (primary outcome) when an oronasal mask was worn (+9.9%; 95% CI:-0.2%-20.0%; P=0.054). Sleep stages 3/4 were favored by the oronasal mask (+12.7%; 95% CI: 6.0%-19.3%; P=<0.001). Subjective assessments were comparable with the exception of items related to leakage (P<0.05 in favor of nasal masks). The mean transcutaneous PCO2 value for oronasal masks (47.7±7.4 mmHg) was comparable to that of nasal masks (48.9±6.6 mmHg) (P=0.11). There was considerable diversity amongst individual patients in terms of sleep quality and gas exchange following mask exchange. Subjective mask preference was not associated with sleep quality, but with nocturnal dyspnea. Over 40% of patients subsequently switched to the mask that they were not previously accustomed to. CONCLUSION: In general, oronasal and nasal masks are each similarly capable of successfully delivering NIV in COPD-patients. However, the individual response to different interfaces is extremely heterogeneous, while subjective mask preference is independent from objective measures, but associated with dyspnea. TRIAL REGISTRATION: German Clinical Trials Registry (DRKS00007741).

Obesity hypoventilation syndrome treated with non-invasive ventilation: Is a switch to CPAP therapy feasible?

BACKGROUND AND OBJECTIVE: Obesity hypoventilation syndrome (OHS) can be treated with either continuous positive airway pressure (CPAP) or non-invasive ventilation (NIV) therapy; the device choice has important economic and operational implications. METHODS: This multicentre interventional trial investigated the safety and short-term efficacy of switching stable OHS patients who were on successful NIV therapy for ≥3 months to CPAP therapy. Patients underwent an autotitrating CPAP night under polysomnography (PSG); if the ensuing parameters were acceptable, they were sent home on a fixed CPAP for a 4-6-week period. It was hypothesized that blood gas analysis, PSG parameters and lung function tests would remain unchanged. RESULTS: A total of 42 OHS patients were recruited, of whom 37 patients were switched to CPAP therapy. All patients had a history of severe obstructive sleep apnoea syndrome; chronic obstructive pulmonary disease (COPD) (Global Initiative for Obstructive Lung Disease (GOLD) I/II) was present in 52%. Regarding the primary outcome, 30 of 42 patients (71%, 95% CI: 55-84%) maintained daytime partial pressure of carbon dioxide (PaCO2 ) levels ≤45 mm Hg after the home CPAP period. There was no further impairment in quality of life, sleep parameters or lung function. Interestingly, 24 patients (65%) preferred CPAP as their long-term therapy, despite the high pressure levels used (mean: 13.8 ± 1.8 mbar). After the CPAP period, 7 of 37 patients were categorized as CPAP failure, albeit only due to mild hypercapnia (mean: 47.9 ± 2.7 mm Hg). CONCLUSION: It is feasible to switch most stable OHS patients from NIV to CPAP therapy, a step that could significantly reduce health-related costs. The auto-adjusted CPAP device, used in combination with the analysis of the PSG and capnometry, is a valid titration method in OHS patients.

Continuous non-invasive PCO2 monitoring in weaning patients: Transcutaneous is advantageous over end-tidal PCO2.

BACKGROUND AND OBJECTIVE: Continuous partial pressure of carbon dioxide (PCO2 ) assessment is essential for the success of mechanical ventilation (MV). Non-invasive end-tidal PCO2 (PetCO2 ) and transcutaneous PCO2 (PtcCO2 ) measurements serve as alternatives to the gold standard arterial PCO2 (PaCO2 ) method, but their eligibility in critical care is unclear. METHODS: The present study therefore performed methodological comparisons of PaCO2 versus PetCO2 and PtcCO2 , respectively, in weaning patients receiving invasive MV via tracheal cannulas. PetCO2 and PtcCO2 were recorded continuously, while PaCO2 was analysed at baseline, and after 30 and 60 min. Using the Bland-Altman analysis, a clinically acceptable range was defined as a mean difference of ±4 mm Hg between PaCO2 and non-invasive strategies. RESULTS: A total of 60 patients (COPD (n = 30) and non-COPD (n = 30)) completed the protocol. Mean PCO2 values were 42.4 ± 8.6 mm Hg (PaCO2 ), 36.5 ± 7.5 mm Hg (PetCO2 ) and 41.7 ± 8.7 mm Hg (PtcCO2 ). Mean differences between PtcCO2 and PaCO2 were -0.7 ± 3.6 mm Hg (95% CI: -1.6/0.3 mm Hg; 95% limits of agreement: -7.8 to 6.4 mm Hg), and between PetCO2 and PaCO2 -5.9 ± 5.3 mm Hg (95% CI: -7.2/-4.5 mm Hg; 95% limits of agreement: -16.2 to 4.5 mm Hg). Underestimation of PaCO2 by PetCO2 was most pronounced in COPD patients. CONCLUSION: Our data therefore support PtcCO2 as a suitable means for monitoring PCO2 in patients undergoing invasive MV. This is in contrast to PetCO2 , which clearly underestimated PaCO2 , especially in patients with COPD.

Low-Volume Whole-Body Vibration Training Improves Exercise Capacity in Subjects With Mild to Severe COPD.

BACKGROUND: The objective of this study was to investigate the benefits of a low-volume out-patient whole-body vibration training (WBVT) program on exercise capacity in comparison with a calisthenics training program in subjects with COPD. METHODS: In this single-center randomized controlled trial, 29 subjects with mild to severe COPD were randomized to WBVT or to calisthenics training, including relaxation and breathing retraining in combination with calisthenics exercises. Both groups equally exercised for a duration of 3 months with 2 sessions of 30 min/week. Outcome parameters were 6-min walk distance (6MWD, primary outcome), 5-repetition sit-to-stand test, leg press peak force, Berg balance scale, St George Respiratory Questionnaire, and COPD assessment test. RESULTS: Twenty-seven subjects completed the study (WBVT, n = 14; calisthenics training program, n = 13). Baseline characteristics between groups were comparable. Subjects in the WBVT group significantly improved median (interquartile range) 6MWD (+105 [45.5-133.5] m, P = .001), sit-to-stand test (-2.3 [-3.1 to -1.3] s, P = .001), peak force (28.7 [16.7-33.3] kg, P = .001), and Berg balance scale (1.5 [0.0-4.0] points, P = .055). Changes in 6MWD, sit-to-stand test, and leg press peak force were also found to be significantly different between groups in favor of the WBVT group. Only the between-group difference of the COPD assessment test score was in favor of the calisthenics training group (P = .02). CONCLUSIONS: A low-volume WBVT program resulted in significantly and clinically relevant larger improvements in exercise capacity compared with calisthenics exercises in subjects with mild to severe COPD. (ClinicalTrials.gov registration DRKS9706.).

The role of NIV in chronic hypercapnic COPD following an acute exacerbation: the importance of patient selection?

Recently, clear benefits have been shown from long-term noninvasive ventilation (NIV) in stable chronic obstructive pulmonary disease (COPD) patients with chronic hypercapnic respiratory failure. In our opinion, these benefits are confirmed and nocturnal NIV using sufficiently high inspiratory pressures should be considered in COPD patients with chronic hypercapnic respiratory failure in stable disease, preferably combined with pulmonary rehabilitation. In contrast, clear benefits from (continuing) NIV at home after an exacerbation in patients who remain hypercapnic have not been shown. In this review we will discuss the results of five trials investigating the use of home nocturnal NIV in patients with prolonged hypercapnia after a COPD exacerbation with acute hypercapnic respiratory failure. Although some uncontrolled trials might have shown some benefits of this therapy, the largest randomized controlled trial did not show benefits in terms of hospital readmission or death. However, further studies are necessary to select the patients that optimally benefit, select the right moment to initiate home NIV, select the optimal ventilatory settings, and to choose optimal follow up programmes. Furthermore, there is insufficient knowledge about the optimal ventilatory settings in the post-exacerbation period. Finally, we are not well informed about exact reasons for readmission in patients on NIV, the course of the exacerbation and the treatment instituted. A careful follow up might probably be necessary to prevent deterioration on NIV early.

Hot Topics in Noninvasive Ventilation: Report of a Working Group at the International Symposium on Sleep-Disordered Breathing in Leuven, Belgium.

During the last few decades, attention has increasingly focused on noninvasive ventilation (NIV) in the treatment of chronic respiratory failure. The University of Leuven and the University Hospitals Leuven therefore chose this topic for a 2-day working group session during their International Symposium on Sleep-Disordered Breathing. Numerous European experts took part in this session and discussed (1) NIV in amyotrophic lateral sclerosis (when to start NIV, NIV and sleep, secretion management, and what to do when NIV fails), (2) recent insights in NIV and COPD (high-intensity NIV, NIV in addition to exercise training, and NIV during exercise training), (3) monitoring of NIV (monitoring devices, built-in ventilator software, leaks, and asynchronies) and identifying events during NIV; and (4) recent and future developments in NIV (target-volume NIV, electromyography-triggered NIV, and autoregulating algorithms).

Impact of intelligent volume-assured pressure support on sleep quality in stable hypercapnic chronic obstructive pulmonary disease patients: a randomized, crossover study.

BACKGROUND: Noninvasive positive-pressure ventilation (NPPV) using intelligent volume-assured pressure support (iVAPS) combines volume- and pressure-preset NPPV and therefore uses a variation of inspiratory positive airway pressures. OBJECTIVES: The effect of iVAPS on sleep quality in stable hypercapnic patients with chronic obstructive pulmonary disease (COPD) has not been determined. METHODS: In this randomized, open-label, two-treatment, two-period, crossover study, patients were randomized to receive high-intensity (HI)-NPPV and then iVAPS or iVAPS and then HI-NPPV. Patients were studied in hospital for 2 consecutive nights, employing full polysomnography (PSG), transcutaneous partial pressure of CO2 (PtcCO2) monitoring, blood gas analysis and a visual analog scale (VAS)-based sleep questionnaire. After discharge, patients used HI-NPPV and iVAPS at home, each for 6 weeks. They had to answer a VAS question concerning sleep every morning, and were telephoned weekly and asked additional questions. At the end of each treatment period, they were visited at home for the determination of blood gases and treatment adherence, and to change the NPPV mode. RESULTS: Fourteen patients were enrolled. In-hospital PSG measurements showed no difference in sleep quality between iVAPS and HI-NPPV. At home, patients reported more restful sleep during iVAPS than HI-NPPV (p = 0.04). Blood gases during spontaneous breathing at home did not differ with iVAPS and HI-NPPV, and there was a greater decrease in PtcCO2 during iVAPS than during HI-NPPV (p = 0.003). CONCLUSION: Although sleep quality in hospital was not different between iVAPS and HI-NPPV, COPD patients with chronic hypercapnic respiratory failure reported a trend towards more restful sleep at home with iVAPS. In addition, nocturnal hypercapnia was effectively treated with iVAPS.

Home mechanical ventilation for COPD: high-intensity versus target volume noninvasive ventilation.

BACKGROUND: High-intensity noninvasive ventilation (HI-NIV) is the most effective means of improving several physiological and clinical parameters in subjects with chronic hypercapnic COPD. Whether the newer hybrid mode using target tidal volume noninvasive ventilation (target V(T) NIV) provides additional benefits remains unclear. METHODS: Subjects with COPD successfully established on long-term HI-NIV were switched to target V(T) NIV. Optimal target V(T) settings according to nocturnal transcutaneous P(CO2) measurements were achieved following a randomized crossover trial using 8 mL/kg ideal body weight and 110% of individual V(T) during HI-NIV, respectively. The following parameters were compared at the beginning of the trial while subjects were on HI-NIV, and after 3 months on optimal target V(T) NIV: sleep quality by polysomnography, overnight gas exchange, subjects' tolerance, overnight pneumotachygraphic measurements during NIV, health-related quality of life (severe respiratory insufficiency questionnaire), exercise capacity (6-min walk test), and lung function. RESULTS: Ten of 14 subjects completed the study. There were no differences between HI-NIV and target V(T) NIV in any of the above-mentioned parameters. Specifically, the mean overnight transcutaneous P(CO2) was equivalent under each form of ventilation (both 45 ± 5 mm Hg, P = .75). CONCLUSIONS: Switching subjects from well-established HI-NIV to target V(T) NIV shows no clinical benefits in chronic hypercapnic COPD. In particular, sleep quality, the control of nocturnal hypoventilation, daytime hypercapnia, overnight ventilation patterns, subjects' tolerance, health-related quality of life, lung function, and exercise capability were all similar in subjects who underwent HI-NIV and target V(T) NIV. Nevertheless, target V(T) NIV might offer some physiological advantages in breathing pattern and might be beneficial in some individual patients. (German Clinical Trials Register [www.drks.de] Registration DRKS00000450.).

Techniques for the measurement and monitoring of carbon dioxide in the blood.

The relationship between an elevated partial pressure of carbon dioxide (Pco2) and reduced alveolar ventilation resulting from respiratory failure primarily affecting the respiratory pump was first reported during the 1952 Copenhagen polio epidemic. Several methods for Pco2 estimation, such as blood gas analyses, capnography, and transcutaneous Pco2 measurements, have since been developed to assess alveolar ventilation. The clinical setting in which CO2 measurement is valuable includes acute and chronic respiratory failure, transport, cardiopulmonary resuscitation, patient-controlled analgesia, and procedural sedation. The techniques that are currently available differ considerably regarding their accuracy, capacity to facilitate continuous assessment, side effects, availability, and their ability to assess additional information. Importantly, each technique has its own spectrum of indications and applications. Therefore, the different techniques are not competitive but, rather, complementary. As a consequence, it is reasonable to combine different techniques depending on specific clinical scenarios. This review summarizes the physiological background, historical development, instrument-specific technical aspects, and current recommendations for the clinical application of Pco2 assessment.

Minute ventilation during spontaneous breathing, high-intensity noninvasive positive pressure ventilation and intelligent volume assured pressure support in hypercapnic COPD.

BACKGROUND: High-intensity noninvasive positive pressure ventilation (HI-NPPV) is an effective treatment option in patients with stable hypercapnic chronic obstructive pulmonary disease (COPD). However, the effect of HI-NPPV compared with spontaneous breathing (SB) on minute ventilation (MV) in patients receiving long-term treatment remains to be determined. This study compared MV during HI-NPPV and SB. In addition, the ability of intelligent volume assured pressure support (iVAPS) to increase MV to the same extent as HI-NPPV was determined. METHODS: Daytime pneumotachographic measurements were performed during SB, HI-NPPV and iVAPS. RESULTS: Twenty-seven stable hypercapnic COPD patients (mean FEV1 34 ± 15% predicted) who had been treated with HI-NPPV for a median of 22 months (interquartile range 8.5-84 months) were enrolled. Mean MV was 9.5 ± 1.7 L/min during SB and 12.1 ± 2.8 L/min during HI-NPPV, an increase of 2.5 L/min (95% CI [1.5-3.6] p < 0.001), or 26%. MV during iVAPS was 11.7 ± 3.6 L/min, an increase of 1.8 L/min (95%CI [0.7-3.0], p = 0.003) compared with SB. There was no difference in MV between HI-NPPV and iVAPS (p = 0.25). CONCLUSION: Long-term HI-NPPV increased MV by an average of 26% compared with SB in stable hypercapnic COPD patients. A similar increase in MV was observed during use of iVAPS.

Oxygen supplementation in noninvasive home mechanical ventilation: the crucial roles of CO2 exhalation systems and leakages.

BACKGROUND: When supplemental oxygen is added to noninvasive ventilation using a non-ICU ventilator, it is usually introduced with a preset flow into the circuit near the ventilator; however, the impact of different CO2 exhalation systems and leaks on the actual FIO2 and gas exchange has not been elucidated. METHODS: In a randomized, open-label, 4-treatment (2-by-2), 4-period crossover design, 4 daytime measurements (60 min each) were performed in 20 subjects receiving home mechanical noninvasive ventilation plus supplemental oxygen (≥ 2 L/min) inserted near the ventilator: active valve circuit or leak port circuit with or without artificial leakage (4 mm inner diameter). Oxygen concentration near the ventilator, oxygen concentration at the mask, and blood gases were measured. RESULTS: Overall, oxygen concentration at the mask (29 ± 5%) was lower than oxygen concentration at the ventilator (34 ± 4%), with a mean difference of 5.1% (95% CI 4.2-5.9%, P < .001)%. With the leak port circuit, oxygen concentration at the mask decreased by 3.2% (95% CI 2.6 to 3.9%, P < .001), compared to the active valve circuit. When artificial leakage was introduced into the circuit, oxygen concentration at the mask decreased by 5.7% (95% CI 5.1 to 6.4%, P < .001)%, PaO2 by 10.4 mm Hg (95% CI 3.1 to 17.7 mm Hg, P = .006), and PaCO2 increased by 1.8 mm Hg (95% CI 0.5 to 3.1 mm Hg, P = .008). CONCLUSIONS: The use of a leak port circuit and the occurrence of leak around the interface significantly reduced oxygen concentration at the mask and negatively impacted gas exchange in subjects receiving home noninvasive ventilation and supplemental oxygen. (German Clinical Trials Registry, www.drks.de, DRKS00000449).

Noninvasive ventilation in COPD: impact of inspiratory pressure levels on sleep quality.

BACKGROUND: Although high-intensity noninvasive positive pressure ventilation (HI-NPPV) is superior to low-intensity noninvasive positive pressure ventilation (LI-NPPV) in controlling nocturnal hypoventilation in stable hypercapnic patients with COPD, it produces higher amounts of air leakage, which, in turn, could impair sleep quality. Therefore, the present study assessed the difference in sleep quality during HI-NPPV and LI-NPPV. METHODS: A randomized, controlled, crossover trial comparing sleep quality during HI-NPPV (mean inspiratory positive airway pressure 29 ± 4 mbar) and LI-NPPV (mean inspiratory positive airway pressure 14 mbar) was performed in 17 stable hypercapnic patients with COPD who were already familiar with HI-NPPV. RESULTS: Thirteen patients (mean FEV(1) 27% ± 11% predicted) completed the trial; four patients refused to sleep under LI-NPPV. There was no significant difference in sleep quality between the treatment groups (all P > .05), with a mean difference of -3.0% (95% CI, -10.0 to 3.9; P = .36) in the primary outcome, namely non-rapid eye movement sleep stages 3 and 4. However, nocturnal Paco(2) was lower during HI-NPPV compared with LI-NPPV, with a mean difference of -6.4 mm Hg (95% CI, -10.9 to -1.8; P = .01). CONCLUSIONS: In patients with COPD, high inspiratory pressures used with long-term HI-NPPV produce acceptable sleep quality that is no worse than that produced by lower inspiratory pressures, which are more traditionally applied in conjunction with LI-NPPV. In addition, higher pressures are more successful in maintaining sufficient alveolar ventilation compared with low pressures. Thus, HI-NPPV is a very promising new approach, but still requires large, longer-term trials to determine the impact on outcomes such as exacerbation rates and longevity. TRIAL REGISTRY: German Clinical Trials Register (DRKS); No.: DRKS00000520; URL: www.drks.de.

High-intensity versus low-intensity non-invasive ventilation in patients with stable hypercapnic COPD: a randomised crossover trial.

RATIONALE: The conventional approach of low-intensity non-invasive positive pressure ventilation (NPPV) produces only minimal physiological and clinical benefits in patients with stable hypercapnic chronic obstructive pulmonary disease (COPD). OBJECTIVES: To determine whether the novel approach of high-intensity NPPV is superior to low-intensity NPPV in controlling nocturnal hypoventilation. METHODS: A randomised controlled crossover trial comparing 6 weeks of high-intensity NPPV (using controlled ventilation with mean inspiratory pressures of 28.6+/-1.9 mbar) with low-intensity NPPV (using assisted ventilation with mean inspiratory pressures of 14.6+/-0.8 mbar) was performed in 17 patients with severe stable hypercapnic COPD. RESULTS: Two patients refused low-intensity NPPV and two patients dropped out while on low-intensity NPPV. Thirteen patients (mean forced expiratory volume in 1 s (FEV(1)) 0.76+/-0.29 l) completed the trial. High-intensity NPPV produced higher pneumotachographically-measured expiratory volumes, with a mean treatment effect of 96 ml (95% CI 23 to 169) (p=0.015). This resulted in a mean treatment effect on nocturnal arterial carbon dioxide tension (Paco(2)) of -9.2 mm Hg (95% CI -13.7 to -4.6) (p=0.001) in favour of high-intensity NPPV. Daily use of NPPV was increased in high-intensity NPPV compared with low-intensity NPPV, with a mean difference of 3.6 h/day (95% CI 0.6 to 6.7) (p=0.024). In addition, compared with baseline, only high-intensity NPPV resulted in significant improvements in exercise-related dyspnoea, daytime Paco(2), FEV(1), vital capacity and the Severe Respiratory Insufficiency Questionnaire Summary Score. CONCLUSIONS: High-intensity NPPV is better tolerated by patients with severe chronic hypercapnic COPD and has been shown to be superior to the conventional and widely-used form of low-intensity NPPV in controlling nocturnal hypoventilation. High-intensity NPPV therefore offers a new promising therapeutic option for these patients.

High-intensity non-invasive positive pressure ventilation for stable hypercapnic COPD.

BACKGROUND: The objective of the present analysis is to describe the outcomes of high-intensity non-invasive positive pressure ventilation (NPPV) aimed at maximally decreasing PaCO(2) as an alternative to conventional NPPV with lower ventilator settings in stable hypercapnic COPD patients. METHODS: Physiological parameters, exacerbation rates and long-term survival were assessed in 73 COPD patients (mean FEV(1) 30+/-12 %predicted) who were established on high-intensity NPPV due to chronic hypercapnic respiratory failure between March 1997 and May 2006. RESULTS: Controlled NPPV with breathing frequencies of 21+/-3 breath/min and mean inspiratory/expiratory positive airway pressures of 28+/-5/5+/-1 cmH(2)O led to significant improvements in blood gases, lung function and hematocrit after two months. Only sixteen patients (22%) required hospitalisation due to exacerbation during the first year, with anaemia increasing the risk for exacerbation. Two- and five-year survival rates of all patients were 82% and 58%, respectively. The five year survival rate was 32% and 83% in patients with low (< or =39%) and high (> or =55%) hematocrit, respectively. CONCLUSION: High-intensity NPPV improves blood gases, lung function and hematocrit, and is also associated with low exacerbation rates and a favourable long-term outcome. The current report strongly emphasises the need for randomised controlled trials evaluating the role of high-intensity NPPV in stable hypercapnic COPD patients.

Transcutaneous PCO2 monitoring during initiation of noninvasive ventilation.

BACKGROUND: To assess the efficacy of transcutaneous Pco2 (Ptcco2) measurements for monitoring alveolar ventilation in patients requiring noninvasive positive-pressure ventilation (NPPV). METHODS: In a prospective study on method agreement pairs of Paco2 and Ptcco2 (SenTec Digital Monitor; SenTec AG; Therwil, Switzerland), measurements were performed every 10 min during the establishment of NPPV over a 4-h period in 10 patients (8 patients with COPD) presenting with acute-on-chronic hypercapnic respiratory failure, thus providing 250 pairs of measurement. RESULTS: Mean (+/- SD) Paco2 decreased from 67.2 +/- 11.9 mm Hg (Ptcco2, 65.5 +/- 13.9 mm Hg) to 54.6 +/- 8.8 mm Hg (Ptcco2, 47.8 +/- 8.8 mm Hg), and mean pH increased from 7.36 +/- 0.03 to 7.44 +/- 0.04. Following Ptcco2 assessment, Ptcco2 in the ensuing 2-min period was the strongest predictor for Paco2 compared to Ptcco2 in the ensuing 5-min period and to real-time measurements. Ptcco2 was highly correlated with Paco2 (r = 0.916; p < 0.001), as determined by linear regression analysis. The mean difference between Paco2 and Ptcco2 was 4.6 mm Hg, and the limits of agreement (bias +/- 1.96 SDs) ranged from -3.9 to 13.2 mm Hg, following the Bland and Altman analysis. Retrospective drift correction produced an even higher correlation (r = 0.956; p < 0.001) with lower limits of agreement (-1.7 to 7.5 mm Hg). CONCLUSIONS: Ptcco2 measurements provide a sensitive, continuous, and noninvasive method for monitoring alveolar ventilation in patients who are receiving short-term NPPV therapy. Drift correction of Ptcco2 measurements improves the accuracy of Ptcco2 monitoring compared to the "gold standard" Paco2 assessment. A lag time of approximately 2 min is present for reliable Ptcco2 values compared to Paco2 values. However, individual variance between Paco2 and Ptcco2 cannot be excluded. TRIAL REGISTRATION: www.uniklinik-freiburg.de/zks/live/uklregister/Oeffentlich.html Identifier:UKF001271.

When should home mechanical ventilation be started in patients with different neuromuscular disorders?

BACKGROUND AND OBJECTIVES: Current international consensus guidelines identify a number of indicators for the establishment of home mechanical ventilation (HMV) for patients with neuromuscular diseases but do not address the possible clinical differences between each of the underlying disorders. This study assessed the differences in the physiological parameters of patients with neuromuscular disease commenced on HMV for the treatment of symptomatic chronic hypercapnic respiratory failure. METHODS: Patients commenced on HMV for the treatment of symptomatic chronic hypercapnic respiratory failure over a 9-year period were studied. Physiological parameters at the time of referral for HMV, impact of HMV and survival were analysed. RESULTS: The study recruited 66 patients with neuromuscular disease. Thirty-one patients had rapidly progressive disease: amyotrophic lateral sclerosis (ALS, n = 19), Duchenne muscular dystrophy (DMD, n = 12) and 35 patients had slowly progressive disease. Mean FVC at HMV onset was 40.3 +/- 17.5% predicted in all patients, but was >50% predicted in eight patients (12%). ALS patients were more hypercapnic (P = 0.03) and more hypoxaemic (P < 0.001), but had better FEV(1) at HMV onset, compared with DMD patients (P = 0.005). Maximal inspiratory mouth occlusion pressure (PImax) was 3.0 +/- 1.6 kPa in all patients, but values were lower compared with international consensus guidelines (5.88 kPa). Median survival in DMD, slowly progressive diseases and ALS was 132, 82 and 16 months, respectively (P < 0.001). CONCLUSIONS: Blood gases and lung function parameters vary substantially between patients with differing underlying neuromuscular disorders when commenced on HMV for the treatment of symptomatic chronic hypercapnic respiratory failure. In contrast, PImax is equally reduced in all patients and more severely reduced compared with consensus guidelines. The specific underlying neuromuscular disease has a major impact on outcome. Specific selection criteria are needed for the use of HMV in the different diseases that comprise neuromuscular disorders.