During exercise non-invasive ventilation in chronic restrictive respiratory failure

BACKGROUND: Exercise intolerance limits chronic restrictive respiratory failure (CRF) patients from participating in daily activities. The specific modalities that could improve exercise tolerance in these patients remain to be established. OBJECTIVE: To investigate exercise endurance and associated physiological responses with non-invasive ventilation (NIV) during exercise in restrictive CRF patients. METHODS: Eighteen patients (63+/-11 years, total lung capacity (TLC)=59+/-16% of predicted value) performed maximal exercise in spontaneous breathing conditions (MWLE) and during two constant workload exercise (CWLE) tests at 75% Pmax, with or without NIV in random order. "NIV Responders" were defined by an increase in CWLE duration of more than 50% when using NIV. RESULTS: For the whole group, CWLE duration when using NIV increased from 5.6+/-4.6 to 9.6+/-8.1 min. Increase in CWLE duration correlated with reduction in heart rate and oxygen desaturation, and dyspnea relief during exercise. NIV responders (n=9) showed more severe lung restriction (TLC: 2.6+/-0.7 versus 3.5+/-1.1L; forced vital capacity: 1.0+/-0.16 versus 1.46+/-0.38 L). At the end of MWLE, responders had a lower Vt (0.60+/-0.09 versus 0.89+/-0.34 L), a higher dead-space ratio (0.51+/-0.06 versus 0.38+/-0.12) and lower oxygen pulse (4.5+/-1.2 versus 7.4+/-3.9 ml/beat). CONCLUSION: In severely restrictive patients, NIV during exercise significantly improved exercise duration and tolerance and increased alveolar ventilation. TRIAL REGISTRATION: The enrollment of the patients started before July 1, 2005.     

Noninvasive ventilation in the pediatric intensive care unit for children with acute respiratory failure

Noninvasive ventilation, a novel treatment to increase alveolar ventilation, is accomplished with either subatmospheric or positive pressure administered via an external interface. In adults with acute respiratory failure, noninvasive positive pressure ventilation (NPPV) is superior to standard therapy in preventing intubation and reducing mortality. The role of NPPV in pediatric-age patients with acute respiratory distress is not as well established. Early case reports showed that NPPV treatment does acutely improve both the clinical manifestations of respiratory distress and respiratory gas exchange in children with respiratory distress. However, it is not clear whether NPPV in this setting can prevent vs. delay endotracheal intubation. Other uses of NPPV in the pediatric intensive care unit include the treatment of upper airway obstruction, atelectasis, and exacerbations of neuromuscular disorders, and to facilitate weaning from invasive mechanical ventilation. Successful use of NPPV in young infants with respiratory distress is impeded by the lack of suitable size interfaces, and the response characteristics of commercially available bilevel ventilators. Despite these challenges, NPPV is a promising alternate to standard therapies in the treatment of acute respiratory distress in the pediatric-age patient.     

Titration of non-invasive positive pressure ventilation in chronic respiratory failure

Non-invasive ventilation (NIV) is widely used for acute and chronic respiratory failure. If arterial blood gas tensions do not improve, the level of support can be increased. However, there may be a limit above which increasing ventilatory support leads only to greater interface leak with no improvement in ventilation. The aim of this study was to establish whether there is such a limit. During a daytime study in 24 ventilated stable patients (10 with chronic obstructive pulmonary disease (COPD), 14 with chest wall deformity, CWD), inspiratory pressures up to 20 cm H(2)O and set tidal volumes up to 10 ml kg(-1) were associated with mask leak of <5 l min(-1). Although leak increased with higher levels of support, there was still an increase in minute ventilation. The mean (2 sd) tolerated pressure was 24 cm H(2)O (8-40) in both groups, and set tidal volume 12.7 ml kg(-1) (5.0-20.4) in CWD and 9.6 ml kg(-1) (3.9-14.8) in COPD. Measures of respiratory effort were significantly reduced at all levels with both forms of ventilatory support. There is debate about whether the therapeutic aim of NIV should be to reduce respiratory muscle effort, or to reverse nocturnal hypoventilation. We conclude that if the primary aim is to improve arterial blood gas tensions and this is not achieved, higher levels of ventilation can be obtained using greater pressure or volume, despite additional interface leak. If the aim is to abolish muscle effort completely, there is little to be gained by increasing the level of inspiratory pressure above 20 (CWD) or 25 (COPD) cm H(2)O.     

Effectiveness of noninvasive positive-pressure ventilation for patients with chronic stable hypercapnic respiratory failure]

The effectiveness of noninvasive positive pressure ventilation (NPPV) was evaluated in 20 patients with chronic stable hypercapnic respiratory failure. Patients were assigned to receive domiciliary long-term oxygen therapy (LTOT group, n = 11) or LTOT plus NPPV (NPPV group, n = 9). The primary endpoints were the health-related quality of life (HRQL), as assessed by the Medical Outcome Study Short Form 36 (SF 36) questionnaire, and the activities and instrumental activities of daily living (ADL and IADL), as assessed by the Groningen Activity Restriction Scale (GARS). Secondary endpoints were mortality, the number of acute exacerbation episodes that required endotracheal intubation, and the length of hospital stay. Significant improvement was observed in the SF 36 physical functioning subscale (30.6 +/- 19.9 to 41.1 +/- 21.6, p = 0.02) and GARS score (36.1 +/- 9.0 to 32.3 +/- 8.5, p = 0.02) of the NPPV group. One patient in the NPPV group and 7 patients in the LTOT group underwent endotracheal intubation (relative risk = 0.18, p = 0.03). Differences in length of hospital stay (8.2 +/- 4.1 days vs. 31.6 +/- 35.8 days, p = 0.07) and mortality rate (1/9 vs. 3/11, p = 0.59) for the NPPV and LTOT groups were not statistically significant. We conclude that the utilization of NPPV for patients with chronic respiratory failure is effective in preventing the deterioration of underlying disease and in improving the quality of life.     

Noninvasive ventilation in cystic fibrosis patients with acute or chronic respiratory failure.

The experience of using noninvasive ventilation (NIV) in 113 adult cystic fibrosis (CF) patients with chronic respiratory failure, during episodes of acute deterioration in respiratory function is reported. The patients aged 15-44 yrs were divided into three groups. Group A consisted of 65 patients (median forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) 0.7/1.4 L) who were on a lung transplant waiting list. Group B consisted of 25 patients (median FEV1/FVC 0.7/1.4 L) who were being evaluated for lung transplantation. Group C consisted of 23 patients (median FEV1/FVC 0.6/1.2 L) who were not being considered for lung transplantation. The mean duration of NIV support for groups A, B and C was 61 (range: 1-600) days, 53 (1-279) days and 45 (0.5-379) days respectively. Twenty-three patients in group A subsequently received lung transplantation and 12 of these patients had a median survival of 39 months postsurgery. Thirty-nine patients died and three awaited transplantation. Five patients in group B received a transplant four of whom survived; thirteen patients died and seven awaited transplantation. Twenty patients in group C died. Noninvasive ventilation improved hypoxia but failed to correct hypercapnia in these cystic fibrosis patients. Noninvasive ventilation is useful in the treatment of acute episodes of respiratory failure in cystic fibrosis patients with end-stage lung disease who have been accepted, or are being evaluated, for lung transplantation. For these patients, there is a possibility of prolonging life if they are successfully treated for their acute episode of respiratory failure until transplantation. In this group, treatment is not merely prolonging the process of dying.     

Sexuality in patients with noninvasive mechanical ventilation due to chronic respiratory failure.

In patients with chronic respiratory failure (CRF) noninvasive mechanical ventilation (NMV) improves quality of life. We studied some basic issues concerning sexuality in patients with NMV. In 383 patients with NMV for CRF (age, > 40 yr) physiologic data (lung function, blood gases, and exercise) were taken from within the 6 mo period before enrollment. The questionnaire was focused on sexuality after initiation of NMV. Of the patients, 54.3% sent back the questionnaire. NMV was used for 41.1 +/- 27.0 mo. A total of 34.1% of patients were sexually active. Compared with patients receiving NMV, control persons had a higher rate of sexual activity (84%, p < 0.0001) and masturbation rate (13 versus 40%). Sexually active patients had greater VC (2.1 versus 1.8 L), higher FEV(1) (1.4 versus 1.1 L), higher Pa(O(2)) at rest (64.0 versus 60.4 mm Hg), a higher maximal work load (72.0 versus 58.8 W), were younger, and most of them were married or had sexual partners. Changes in sexual activity after NMV initiation were reported to be as follows: "Nothing changed," 46.3%; "less active," 35.8%; "more active," 12.6%; and "fantasy increased," 10.5%. Increased sexual fantasy predominated in men. "Sexually active" patients with NMV had sexual intercourse 5.4 +/- 4.8 times per month. Sexuality in patients receiving NMV for CRF is markedly reduced compared with normal subjects. In half of the patients, sexual activity is influenced by initiation of NMV.     

Nasal versus full face mask for noninvasive ventilation in chronic respiratory failure.

This study was undertaken to determine the efficacy of nasal mask (NM) versus full face mask (FFM) for the delivery of noninvasive ventilation (NIV) in subjects with nocturnal hypoventilation. A total of 16 patients (11 males) were enrolled, all with nocturnal hypoventilation currently treated at home with NIV via pressure preset devices. Subjects underwent full polysomnography on three occasions; on the first night current therapy on NM was reviewed, followed by two experimental studies in randomised order using either NM or FFM. NIV settings and oxygen flow rate were the same under both conditions. Notably, 14 of the 16 subjects required the use of a chinstrap to minimise oral leak. Apnoea-hypopnoea indices were within normal limits under both conditions (1.7 +/- 3.4 NM versus 1.6 +/- 2.4 h FFM). The type of interface did not significantly affect gas exchange during sleep (minimum average arterial oxyhaemoglobin saturation total sleep time 93.4 +/- 2.1 NM versus 92.8 +/- 2.5% FFM, Delta transcutaneous carbon dioxide nonrapid eye movement sleep to rapid eye movement sleep (0.58 +/- 0.36 NM versus 0.50 +/- 0.40 kPa FFM). Sleep efficiency was significantly reduced on the FFM (78 +/- 9 NM versus 70 +/- 14% FFM), although arousal indices were comparable under both conditions (15.6 +/- 9.8 NM versus 15.8 +/- 8.8 h FFM). Full face masks appear to be as effective as nasal masks in the delivery of noninvasive ventilation to patients with nocturnal hypoventilation. However, a chinstrap was required to reduce oral leak in the majority of subjects using the nasal mask.     

无创正压通气支持对慢性呼吸衰竭患者血流动力学参数的影响

目的比较持续气道正压(CPAP)通气与双水平气道正压(BiPAP)通气对慢性阻塞性肺疾病(COPD)合并呼吸衰竭患者血流动力学参数的影响。方法COPD合并呼吸衰竭患者31例,其中男性24例,女性7例,年龄(67±4)岁。给予常规内科治疗的同时,进行CPAP和BiPAP无创正压机械通气(NPPV)各60min,使用胸腔阻抗法监测患者在鼻导管吸氧自主呼吸以及接受不同通气模式支持时血流动力学参数、通气参数和动脉血气的变化。结果与自主呼吸相比,患者在CPAP通气后心率(HR)和平均动脉压(MAP)略有下降,而在BiPAP通气时呈明显下降(P<0.05)。BiPAP通气时患者的心输出量(CO)、心脏指数(CI)、搏出量(SV)和每搏指数(SI)与CPAP时相近,但低于未进行NPPV时。NPPV支持后射血前时间(PEP)明显缩短,对左室射血时间(LVET)则影响不大。CPAP时的浅快呼吸指数(RR/VT)为81.2±4.7,显著高于BiPAP时的53.6±2.9(P<0.05)。所有患者在NPPV支持时的PaO2/FiO2较鼻导管吸氧时显著增高,PaCO2则有所降低。结论COPD呼吸衰竭患者接受NPPV支持尤其是BiPAP通气后,患者的VT显著增加,相应PaO2/FiO2也明显增高,而PaCO2呈逐步下降,患者RR/VT的降低则反映其呼吸肌做功的减少,氧耗量降低。血流动力学参数中CO、CI、SV等均较鼻导管吸氧时明显下降,但不同NPPV模式对上述参数的影响却无差异。CPAP与BiPAP通气时患者的PEP明显下降,说明患者的心脏收缩能力得到增强。     

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.     

双水平气道正压通气治疗慢性阻塞性肺疾病合并急性呼吸衰竭的临床研究

目的探讨经鼻面罩双水平气道正压（BiPAP）通气在慢性阻塞性肺疾病（COPD）合并急性呼吸衰竭早期的应用价值。方法将80例COPD合并急性呼衰患者分为2组，每组40例，在进行抗感染、对症等常规治疗的同时，分别给予持续静滴可拉明及经鼻面罩BiPAP通气治疗6小时，判断两组之间治疗前后生命体症及血气分析变化。结果两组治疗6小时后，机械通气组在血压、心率、呼吸频率方面改善均显著优于对照组（P〈0．01）；对照组pH值无改善，而机械通气组pH值显著改善，与对照组相比有显著差异（P〈0．01）；机械通气组和对照组治疗后均有PaO2上升和PaCO2下降，但机械通气组改善更明显，与对照组相比有显著差异（P〈0．01）。结论经鼻面罩BiPAP通气适合治疗COPD合并急性呼衰患者，其在改善临床症状和动脉血气指标方面均优于常规治疗，值得临床推广。