Ventilatory muscle support in respiratory failure with nasal positive pressure ventilation

Long-term intermittent mechanical ventilation results in improvements in ventilatory performance and clinical status between ventilation sessions in patients with chronic respiratory failure. The application of intermittent positive pressure ventilation through a nasal mask (NPPV) is a simple, noninvasive method for the provision of chronic intermittent ventilatory support. We investigated the effects of NPPV on inspiratory muscle activity in three normal subjects and nine patients with acute or chronic ventilatory failure due to restrictive (four subjects) or obstructive (five subjects) respiratory disorders. NPPV resulted in reductions of phasic diaphragm electromyogram amplitude to 6.7 +/- 0.7 percent (mean +/- SEM) of values obtained during spontaneous breathing in the normal subjects, 6.4 +/- 3.2 percent in the restrictive group, and 8.3 +/- 5.1 percent in the obstructive group. Simultaneous decreases in activity of accessory respiratory muscles were observed. The reductions in inspiratory muscle activity were confirmed by the finding of positive intrathoracic pressure swings on inspiration in all subjects. With NPPV, oxygen saturation and PCO2 remained stable or improved as compared with values obtained during spontaneous breathing. These results indicate that NPPV can noninvasively provide ventilatory support while reducing inspiratory muscle energy expenditure in acute and chronic respiratory failure of diverse etiology. Long-term assisted ventilation with NPPV may be useful in improving ventilatory performance by resting the inspiratory muscles.     

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.     

Noninvasive ventilation and obstructive lung diseases.

The key role of noninvasive positive pressure ventilation (NPPV) is well documented in chronic obstructive pulmonary disease (COPD) patients with acute respiratory failure (ARF) since it may avoid endotrachal intubation in >50% of cases when used as the initial treatment. However, currently only minimal data is available to assess usefulness of NPPV in COPD patients on a long-term basis. Even if such studies are difficult to manage, there is clearly a need for prospective studies comparing long-term oxygen therapy (LTOT) and NPPV in the most severe COPD in a large amount of patients and on a real long-term basis of several years. Two randomized prospective studies are being completed in Europe and the first preliminary results show that NPPV is associated with a reduction of hospitalization for chronic respiratory failure decompensation. The main beneficial effect of long-term mechanical ventilation in COPD patients with chronic respiratory failure implies a correction of nocturnal hypoventilation that could persist beyond the ventilation period because of a temporary improvement in carbon dioxide sensitivity that is often blunted in these patients. A synthesis from the literature suggest to consider NPPV for severe COPD patients who present with chronic hypoxia and hypercapnia and develop an unstable respiratory condition. Instability may be appreciated on a clinical basis and confirmed by a progressive worsening of arterial blood gas tensions, leading to frequent cardiorespiratory decompensations with ominous ARF episodes. NPPV should also be considered after an ARF episode successfully treated by noninvasive ventilation but with the impossibility to wean the patient from the ventilator. Thus, noninvasive positive pressure ventilation could be proposed as a preventive treatment in severe chronic obstructive pulmonary disease patients with unstable respiratory condition associated with fluctuating hypercapnia before, during and after an acute respiratory failure episode, avoiding the need for a tracheotomy. Adjunction of noninvasive ventilation to exercise rehabilitation is under evaluation.     

2014~2015年度无创正压通气进展

无创正压通气(NPPV)在 COPD 急性加重(AECOPD)、急性心源性肺水肿(ACPE)、多种病因导致呼吸衰竭患者、需撤机患儿和婴幼儿中的应用呈稳步增长,而有创通气(IMV)使用有所下降,在“合适的患者”中应用 NPPV 作为一线治疗可获益,在有指征时,应及早应用。Meta 分析提示,对于 ALI/ARDS 患者,应用 NPPV 可降低气管插管率,对于急诊患者的院前治疗,支持早期应用 NPPV。部分研究结果支持在伴有慢性高碳酸血症的呼吸衰竭患者中应用较高强度的 NPPV 治疗,可降低病死率,能改善总体生存率、运动能力和生活质量评分。     

Noninvasive ventilation for acute respiratory failure: a prospective randomised placebo-controlled trial.

The aim of the present study was to clarify whether the known effects of noninvasive positive-pressure ventilation (NPPV) in patients with respiratory failure are real or due to placebo effects and whether early application of NPPV in the emergency department leads to rapid improvement of the patients condition and outcome. A prospective randomised placebo-controlled study was conducted in 20 patients with severe acute respiratory failure (ARF) secondary to an acute exacerbation of chronic obstructive pulmonary disease (COPD) or acute pulmonary oedema, not improving under conventional medical therapy and on the edge of intubation. Patients received either conventional medical therapy plus two-level NPPV (hi-level NPPV) or conventional medical therapy plus "placebo" NPPV. The main outcome measures involved the need for endotracheal intubation in the bi-level NPPV arm and in the placebo arm after crossing over to active NPPV. Morbidity, length of stay, mortality and the effect of the ventilatory mode on clinical, arterial-blood gas parameters, and the sternocleidomastoid muscles electromyogram (EMG) activity were also measured. The 10 patients in the active NPPV group rapidly improved and none needed intubation. Placebo NPPV resulted in no change in the clinical condition of patients that continued to worsen and the 10 patients were crossed over to active NPPV. Three patients were intubated. No differences in terms of morbidity, length of stay or mortality between the two groups were observed. Active NPPV (but not placebo NPPV) led to a rapid and significant improvement in the clinical parameters, pH and the carbon dioxide tension in arterial blood and to a decrease in respiratory frequency and sternocleidomastoid EMG activity. Early application of bi-level noninvasive positive-pressure ventilation in patients with severe acute respiratory failure, due to chronic obstructive pulmonary disease and acute pulmonary oedema, leads to a rapid improvement in clinical status and blood gases. Noninvasive positive-pressure ventilation had no placebo effect.     

Noninvasive Positive Pressure Ventilation in Acute Respiratory Failure of Chronic Obstructive Pulmonary Disease

Noninvasive positive pressure ventilation (NPPV) has reemerged as an effective strategy for reducing morbidity and mortality associated with acute exacerbations of chronic obstructive pulmonary disease (COPD). During acute respiratory failure, dynamic hyperinflation, intrinsic PEEP, and increased airway resistance result in a mechanical workload that exceeds inspiratory muscle capacity. NPPV provides augmentation of alveolar ventilation and respiratory muscle rest. Observational, cohort, and, more recently, randomized controlled trials have demonstrated the ability of NPPV to decrease the need for endotracheal intubation and decrease complications and mortality. NPPV performs better in COPD patients without significant comorbid illness. It should be initiated during COPD exacerbations if arterial pH is less than 7.35 or if the patient is severely distressed. Pressure support ventilation (10–20 cmH₂O) via face mask is likely the optimal technique and, when successful, results in rapid clinical improvement. Accepted for publication: 17 October 1996     

Nasal mask ventilation in acute respiratory failure. Experience in elderly patients.

Nasal mask ventilation (NMV) has been used successfully in chronic restrictive respiratory failure and more recently in acute exacerbations of chronic obstructive pulmonary disease (COPD). This study aimed to evaluate the possible role of NMV in acute respiratory failure (ARF) episodes when mechanical ventilation with endotracheal intubation is questionable. Thirty patients (age, 76 +/- 8.1 years) were treated by NMV during ARF episodes (COPD, 20; other chronic respiratory failure [CRF], 5; chronic heart failure [CHF], 4). All patients were hypoxemic (PaO2, 5.85 +/- 1.62 kPa) and hypercapnic (PaCO2, 8.63 +/- 1.89 kPa) with respiratory acidosis (pH, 7.29 +/- 0.08). In all cases, clinical or physiologic parameters indicated the need for mechanical ventilation, but endotracheal intubation was either not applied because of the age and the physiologic condition of the patients (17 cases) or was postponed (13 cases). NMV was performed using a volume-cycled ventilator and a customized nasal mask. Ventilation was continuous during the first 12 hours and the following nights and was then intermittent during the day. Twenty-one patients improved clinically, within a few hours. Progressive correction of arterial blood gases was observed: PaO2 increased during the first hour, but PaCO2 decreased more slowly. Eighteen patients were able to be successfully weaned from NMV. Twelve patients failed to improve despite NMV: eight of them died and four required endotracheal intubation. There was no difference in the success rate between patients in whom endotracheal ventilation was contraindicated or postponed. Clinical tolerance was satisfactory in 23 patients and poor in seven patients. A return to the respiratory condition was observed in the surviving patients with subsequent discharge from hospital. NMV therefore successfully treated respiratory distress initially in 60 percent of the 30 patients. These results suggest that NMV could be a possible alternative in the treatment of ARF, even in very ill patients, when endotracheal ventilation is controversial or not immediately required.     

Noninvasive ventilation during percutaneous gastrostomy placement in Duchenne muscular dystrophy

Noninvasive positive pressure ventilation (NPPV) is used for respiratory support in a number of diseases causing acute or chronic respiratory failure. We describe a novel use of NPPV to provide respiratory support during sedation for percutaneous placement of a gastrostomy tube in a patient with Duchenne muscular dystrophy (DMD). The patient had severe respiratory insufficiency, progressive dysphagia, and undernutrition. In addition to the case in this report, we have used NPPV to provide respiratory support to DMD patients during five other gastrointestinal endoscopies without complication. The technique is highly labor intensive and requires physicians and respiratory therapists familiar with NPPV. The primary risk associated with this technique is lack of definitive airway protection during the procedure, which must be balanced against the risks of intubation in an anesthetized patient with neuromuscular disease. The potential benefit to selected patients is substantial, such as initiation of gastrostomy tube feeding in our patient, with subsequent improvement in his quality of life and nutritional status. Pediatr. Pulmonol. 1997; 23:468–471. © 1997 Wiley-Liss, Inc.     

严重急性呼吸综合征所致呼吸衰竭及无创通气治疗

目的　回顾性总结严重急性呼吸综合征 (SARS)并发呼吸衰竭患者的血气特点 ,探讨应用无创正压通气 (NPPV)治疗的策略。方法　 2 0 0 3年 4月 2 2日～ 5月 1日 ,12 0例临床符合SARS诊断标准的患者入住北京地坛医院 (SARS专科医院 )的 4个病区 ,30例患者 (占 2 5 % )在病程中出现呼吸衰竭 ,达到急性肺损伤 (ALI)和 (或 )急性呼吸窘迫综合征 (ARDS)的诊断标准。 2 8例应用双水平气道正压通气 (BiPAP)。主要观察指标 :(1)住院期间的血气分析、脉搏容积血氧饱和度 (SpO2 )及呼吸频率 ,特别是上机前、上机后 1h及撤机后的结果 ;(2 )放射学检查或临床提示住院后新出现的气胸、纵隔气肿、心包积气及皮下气肿 ;(3)应用无创通气的天数 ;(4 )需气管插管行有创通气的患者数 ;(5 )患者的病死率 ;(6 )一线医务人员因护理治疗无创通气SARS患者而感染SARS的情况。结果统计 30例患者在整个病程中的动脉血二氧化碳分压 (PaCO2 )变化情况 ,16例 (5 3% )患者出现CO2 潴留 ,PaCO2为 4 5～ 5 6mmHg ,平均 (4 8± 4 )mmHg。NPPV治疗后动脉血氧分压 (PaO2 )、SpO2 、氧合指数及呼吸频率均显著改善 (P均 <0 0 1) ,但pH及PaCO2 的变化并不明显。 18例患者成功撤机 ,应用NPPV的时间为5～ 30d ,平均 (10± 6 )d。除 1例不能耐受BiPAP     

Esophageal perforation associated with noninvasive ventilation: a case report

Noninvasive positive-pressure ventilation (NIPPV) is widely used to treat acute respiratory failure, the goal being to avoid exposing patients to the morbidity associated with tracheal intubation. NIPPV may reduce the rates of intubation, morbidity, and mortality in selected patient subgroups. Although time-consuming for physicians and nurses, NIPPV is fairly easy to use, and few severe complications have been reported. Esophageal perforation is a well-recognized complication of tracheal intubation but has not been described in association with NIPPV. We report a case of fatal esophageal perforation associated with NIPPV after a surgical procedure.     

Sleep and long-term ventilation

The development of sleep-disordered breathing is common in patients with chronic respiratory insufficiency due to neuromuscular and restrictive disorders, as well as in those with COPD. Nocturnal hypoventilation and obstructive and central apneas result in daytime symptoms of hypersomnolence and fatigue, and contribute to abnormalities in awake gas exchange. Long-term mechanical ventilation, delivered invasively by tracheostomy or more recently by NPPV, has been shown to eliminate sleep-disordered breathing and correct abnormalities in nocturnal gas exchange, resulting in an improvement in sleep quality. Improved daytime symptoms and gas exchange, with the suggestion of a decrease in morbidity and mortality, support the use of long-term mechanical ventilation during sleep in selected patients with these disorders.     

无创正压通气在心外科术后患者中的应用

目的:回顾性研究无创正压通气(NPPV)对心外科体外循环(CPB)术后出现急性呼吸衰竭(ARF)患者的安全性和有效性。方法:回顾本院心外科全麻CPB术后成年患者(年龄>16岁)450例,其中24例在拔管后出现ARF,根据ARF的病因分为6例肺炎、7例心源性肺水肿、11例CPB相关性肺损伤,比较NPPV使用前、后1h的氧合指数、心率、呼吸次数和动脉血pH,并用患者围手术期的临床特征作为参数来分析NPPV失败的预测因素。结果:NPPV平均使用时间(12.33±11.97)h,氧合指数、心率、呼吸次数和动脉血pH在使用前、后1h均明显改善(均P<0.01)。NPPV使66.67%的患者避免再次气管插管,其中对心源性肺水肿和CPB相关性肺损伤的疗效满意,成功率分别是85.71%和90.91%;而肺炎的患者均失败。所有患者均无NPPV并发症。有意义的单因素预测因素是NPPV治疗后1h的PaO2/FiO2<200,初次机械通气的时间和肺炎,多因素分析显示肺炎是预测NPPV失败的独立因素(OR0.063;95%CI 0.008～0.501)。结论:心外科CPB术后患者拔管后出现ARF,NPPV可以有效改善肺部氧合,减低再次气管插管的需要,但要严格选择病例。     

无创机械通气治疗老年急性左心衰竭的疗效观察

目的探讨无创机械通气对老年急性左心衰竭患者的治疗效果及副反应。方法将42例符合入选标准的老年急性左心衰竭患者随机分为两组,对照组（19例）给予高浓度面罩酒精吸氧、常规强心、利尿、扩管、镇静治疗;治疗组（23例）在常规治疗的基础上,行双水平气道正压通气呼吸机辅助通气。观察两组患者治疗前后临床症状的改善情况,并监测患者治疗前及治疗后2小时动脉血气指标和心率、呼吸频率、射血分数、氧合指数,比较两组患者治疗结束时的病死率及气管插管率。结果治疗组治疗2小时后,患者临床症状迅速缓解,动脉血气指标和心率、呼吸频率、射血分数、氧合指数均明显改善,气管插管率及病死率较对照组低,两组比较差异有显著性（P〈0．05）。结论无创机械通气治疗老年急性左心衰竭起效迅速,能迅速纠正缺氧,改善心肺功能,减少气管插管率及病死率,副反应少,可作为抢救急性左心衰竭的重要手段之一。     

无创正压通气治疗慢性阻塞性肺疾病急性呼吸衰竭

无创正压通气已经广泛用于慢性阻塞性肺疾病急性加重期的治疗,主要适应证包括呼吸增快、动脉氧分压下降、二氧化碳分压升高和呼吸性酸中毒,颜面部畸形、严重意识障碍、呼吸心跳停止以及血流动力学不稳定是其主要禁忌证。无创正压通气能够减轻呼吸肌负荷、减轻呼吸肌疲劳,具有降低患者病死率和气管插管率的作用。无创正压通气治疗时给予足够的压力支持和治疗时间是取得治疗效果的重要保证。     

Noninvasive mechanical ventilation for post acute care

The increasing use of NPPV in both acute and chronic settings has added to ventilator options in the post acute setting. Some patients start NPPV during their acute presentation and continue use during their post acute stay. Others are difficult to wean from invasive mechanical ventilation, and, if selected carefully, can be extubated and weaned using NPPV. Still others may initiate NPPV in the post acute setting with the anticipation of long-term use. In any care settings, principles of patient selection and management in monitoring practices overlap considerably. Noninvasive ventilation has been shown to reduce morbidity, mortality, and hospital stay in the acute setting for selected patients, and almost certainly prolongs survival for patients with restrictive thoracic disorders in the chronic setting. Although efficacy studies have not been performed in the post acute setting, it is reasonable to anticipate that appropriate use of NPPV will yield similar benefits. Accordingly, clinicians working in the post acute setting must acquire skill and experience in the proper application of NPPV to optimally manage the increasing number of patients treated with NPPV in this expanding arena.     

无创正压通气在外科术后发生急性呼衰患者中过渡撤机的临床48例分析

目的比较无创正压通气(NPPV)和有创正压通气(IPPV)救治外科术后发生急性呼吸衰竭(ARF)的临床效果,评估NPPV在治疗中(过渡撤机)的作用。方法对48例外科术后发生ARF的患者先采用气管插管IPPV治疗72h后不能撤机者进行NPPV以过渡撤机,观察比较IPPV72h后与NPPV12h后两者HrBPR及动脉血气分析各指标。结果IPPV72h后与NPPV12h后,各指标HrBPRPaO2PaCO2均稳定,差异无显著性(P0.05)48例中,39例成功撤机,9例因并发心、脑、血液系统疾病重新气管插管或气管切开进行IPPV。结论在经过选择的外科术后发生ARF患者中经气管插管IPPV治疗72h后难以撤机者,实施NPPV以过渡撤机,可达到理想的通气支持治疗效果。     

Acute applications of noninvasive positive pressure ventilation

Noninvasive positive-pressure ventilation (NPPV) has been used increasingly to treat acute respiratory failure (ARF). The best indications for its use are ARF in patients with COPD exacerbations, acute pulmonary edema, and immunocompromised states. For these indications, multiple controlled trials have demonstrated that therapy with NPPV avoids intubation and, in the case of COPD and immunocompromised patients, reduces mortality as well. NPPV is used to treat patients with numerous other forms of ARF, but the evidence is not as strong for its use in those cases, and patients must be selected carefully. The best candidates for NPPV are able to protect their airway, are cooperative, and are otherwise medically stable. Success is optimized when a skilled team applies a well-fitted, comfortable interface. Ventilator settings should be adjusted to reduce respiratory distress while avoiding excessive discomfort, patient-ventilator synchrony should be optimized, and adequate oxygenation should be assured. The appropriate application of NPPV in the acute care setting should lead to improved patient outcomes and more efficient resource utilization.     

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.     

Sleep in restrictive and neuromuscular respiratory disorders

Thoracic restrictive disorders (i.e., chest wall deformities or neuromuscular diseases), may predispose to sleep-disordered breathing, poor sleep quality, and nocturnal hypoventilation. These disorders intensify the effects of reductions in both respiratory center output and central chemosensitivity and increases in upper airway resistance that occur with the onset of sleep. Normally, rapid eye movement (REM) sleep suppresses the activity of nondiaphragmatic breathing muscles, further reducing ventilation. Diaphragmatic or upper airway muscle weakness and reduced chest wall compliance in patients with thoracic restrictive disorders enhance the severity of sleep-disordered breathing during REM sleep, worsening gas exchange abnormalities and sleep fragmentation and impairing daytime functioning. Although daytime respiratory function and nocturnal oxygen saturation are not well correlated, some markers may be useful for identifying patients with thoracic restriction at risk for sleep-disordered breathing. Although some patients may respond to continuous positive airway pressure (CPAP) alone, noninvasive positive pressure ventilation (NPPV) is a more important part of disease management for patients with restrictive thoracic disorders. This technique improves nocturnal ventilation and sleep quality but may also contribute to sleep fragmentation in some patients. If the patient is an unsuitable candidate for or fails NPPV, tracheostomy mechanical ventilation should be considered.