Physiological effects and optimisation of nasal assist-control ventilation for patients with chronic obstructive pulmonary disease in respiratory failure

BACKGROUND: A study was undertaken to investigate the effects of non- invasive assist-control ventilation (ACV) by nasal mask on respiratory physiological parameters and comfort in acute on chronic respiratory failure (ACRF). METHODS: Fifteen patients with chronic obstructive pulmonary disease (COPD) were prospectively and randomly assigned to two non-invasive ventilation (NIV) sequences in spontaneous breathing (SB) and ACV mode. ACV settings were always optimised and therefore subsequently adjusted according to patient's tolerance and air leaks. RESULTS: ACV significantly decreased all the total inspiratory work of breathing (WOBinsp) parameters, pressure time product, and oesophageal pressure variation in comparison with SB mode. The ACV mode also resulted in a significant reduction in surface diaphragmatic electromyographic activity to 36% of the control values and significantly improved the breathing pattern. SB did not change the arterial blood gas tensions from baseline values whereas ACV significantly improved both the PaO2 from a mean (SD) of 8.45 (2.95) kPa to 13.31 (2.15) kPa, PaCO2 from 9.52 (1.61) kPa to 7.39 (1.39) kPa, and the pH from 7.32 (0.03) to 7.40 (0.07). The respiratory comfort was significantly lower with ACV than with SB. CONCLUSIONS: This study shows that the clinical benefit of non-invasive ACV in the management of ACRF in patients with COPD results in a reduced inspiratory muscle activity providing an improvement in breathing pattern and gas exchange. Despite respiratory discomfort, the muscle rest provided appears sufficient when ACV settings are optimised.


     

右美托咪定与吗啡用于慢性阻塞性肺病患者机械通气时对呼吸力学影响的比较

目的研究右美托咪定（dexmedetomidine,DEx）和盐酸吗啡对慢性阻塞性肺病急性发作期（acute exacerbation of chronic obstructive pulmonary disease, AECOPD）行机械通气患者呼吸力学的影响。方法入选AECOPD伴呼吸衰竭行机械通气患者40例;在同样的分钟通气量和呼气末正压的设置下,采用随机对照的方法分为两组（对照组、试验组）,每组20例,对照组使用吗啡进行镇静治疗,实验组使用盐酸DEX。记录两组患者急性生理功能和慢性健康状况评分系统Ⅱ（acute physiology and chronic health evaluation, APACHE Ⅱ）评分、脑电双频指数（bispectral index,BIS）评分、Ramsay镇静评分等指标。比较两组患者镇静前后生命体征、血气的变化和镇静后呼吸力学参数的变化。结果与对照组比较,实验组中平均动脉压（mean arterial pressure,MAP）和脉搏[（80±3）mmHg比（75±4）mmHg（1mmHg=0．133kPa）和（90±3）次/min比（79±3）次/min]降低（P〈0．01）,平均气道压mean airway pressure,Paw）、平台压（plateau pressure,eplat）[（7．5±0．7）cm H2O比（6．2±0．6）cm H2O（1cmH2O=0．098kPa）、（19．8±1．7）cmH20比（18．0±1．1）cmH2O]明显降低（P〈0．01）,峰食道压力（peak esophageal pressure,PPEAKES）、PPEAKEE与基准食道压力差（the peak esophageal manometry reference esophagus pressure difference, dPEs）[（-3．4±0．7）cmH2O比（-5．4±1．0）cmH2O、（-6．9±1．0）cmH2O比（-9．8±1．3）cmH2O]变大（P〈0．01）,吸气末屏气期间的跨肺压（ folding Screen the end of the suction gas during transpulmonary pressure, Ptp Plat）、肺静态顺应性（pulmonary static compliance,cst）[（25．5±2．3）cmH2O比（26．0±2．6）cmH2O、（20．5±1．9）cmH2O比（20．1±1-2）cmH2O]变化无统计学意义（P〉0．05）,气道阻力（airway resistance,Raw）[（20．3±3．9）cmH2O·L-1·s-1比（15．6±1．4）cmH2O·L-1·s-1]变小（P〈0．01）,患者呼吸功（patient work of breathing,WOBp）[（0．11±0．02）j/L比（0．16±0．04）j／L]明显增加[1（P〈0．01）,机械呼吸功（mechanical work of breathing,WOBv）[（0．49±0．10）g/L比（0．43±0．06）j／L]明显降低（P〈0．05）。机械通气时间、重症监护室（ICU）入住时间[（76±5）h比（64±3）h、（6．0±1．5）d比（4．6±0．9）d]减少（P〈0．05）。结论与吗啡比较,DEX能提高机械通气患者的镇静效果、降低Raw、提高肺顺应性,有利于实施保护性通气策略,同时降低呼吸负荷和呼吸做功,因而能降低呼吸氧耗。     

Haemodynamic effects of pressure support and PEEP ventilation by nasal route in patients with stable chronic obstructive pulmonary disease.

BACKGROUND--Intermittent positive pressure ventilation applied through a nasal mask has been shown to be useful in the treatment of chronic respiratory insufficiency. Pressure support ventilation is an assisted mode of ventilation which is being increasingly used. Invasive ventilation with intermittent positive pressure, with or without positive end expiratory pressure (PEEP), has been found to affect venous return and cardiac output. This study evaluated the acute haemodynamic support ventilation by nasal mask, with and without the application of PEEP, in patients with severe stable chronic obstructive pulmonary disease and hypercapnia. METHODS--Nine patients with severe stable chronic obstructive pulmonary disease performed sessions lasting 10 minutes each of pressure support ventilation by nasal mask while undergoing right heart catheterisation for clinical evaluation. In random order, four sessions of nasal pressure support ventilation were applied consisting of: (1) peak inspiratory pressure (PIP) 10 cm H2O, PEEP 0 cm H2O; (2) PIP 10 cm H2O, PEEP 5 cm H2O; (3) PIP 20 cm H2O, PEEP 0 cm H2O; (4) PIP 20 cm H2O, PEEP 5 cm H2O. RESULTS--Significant increases in arterial oxygen tension (Pao2) and saturation (Sao2) and significant reductions in arterial carbon dioxide tension (PaCO2) and changes in pH were observed with a PIP of 20 cm H2O. Statistical analysis showed that the addition of 5 cm H2O PEEP did not further improve arterial blood gas tensions. Comparison of baseline values with measurements performed after 10 minutes of each session of ventilation showed that all modes of ventilation except PIP 10 cm H2O without PEEP induced a small but significant increase in pulmonary capillary wedge pressure. In comparison with baseline values, a significant decrease in cardiac output and oxygen delivery was induced only by the addition of PEEP to both levels of PIP. CONCLUSIONS--In patients with severe stable chronic obstructive pulmonary disease and hypercapnia, pressure support ventilation with the addition of PEEP delivered by nasal mask may have short term acute haemodynamic effects in reducing oxygen delivery in spite of adequate levels of SaO2.     

有创与无创序贯机械通气治疗在心脏外科术后的应用

目的 探讨有创与无创序贯机械通气治疗在心脏外科术后ICU中的应用效果.方法 选取44例接受心脏外科手术的患者,术后均存在一定程度的脱机困难,将其分为两组:序贯治疗组,23例患者,常规治疗的基础上,以同步间歇指令通气方式行机械通气,待患者呼吸循环状态稳定后拔除气管插管,改双水平气道正压(BiPAP)支持通气方式并撤机;对照组,21例患者,以同步间歇指令通气+压力支持通气方式撤机.对照分析两组病例的通气、氧合指标、有创机械通气时间和总的机械通气时间,并发症发生率.结果 序贯治疗组和对照组患者有创机械通气时间分别是(2.3±0.8)d和(7.3±0.5)d,总机械通气时间分别是(4.2±0.5)d和(7.3±0.5)d,住ICU时间分别为(6.5±0.9)d和(10.3±0.4)d,呼吸机相关肺炎分别为6例(26.1%)和12例(57.1%),两组患者中,治疗组有2例患者二次插管(8.7%),而对照组有3例患者二次插管(14.3%).结论 心脏外科术后患者,如果存在脱机困难,可采用早期拔管,改用经鼻面罩呼吸机正压通气以缩短机械通气时间,减少呼吸机相关肺炎的发生.     

比例辅助通气对撤机阶段慢性阻塞性肺疾病合并呼吸衰竭患者通气参数的影响

目的观察比例辅助通气（PAV）与压力支持通气（PSV）对撤机阶段慢性阻塞性肺疾病（COPD）合并呼吸衰竭患者通气参数的影响。方法COPD合并呼吸衰竭患者15例,所有患者均为气管插管并接受机械通气支持1周以上者,在治疗过程中病情稳定准备撤机。随机选用PAV和不同水平的PSV[PSV水平为10cmH2O（PS10）和PSV水平为15cmH2O（PS15）,1cmH20=0．098kPa]辅助通气60min,应用PAV前采用最小平方拟合法（LSF）测定患者的呼吸系统弹性阻力（Ers）和气道阻力（Rrs）,设置容量辅助（VA）和流量辅助（FA）,辅助比例为80％。观察患者在不同通气条件下通气参数及动脉血气分析的变化。结果与低水平PSV（PS10）时相比,高水平PSV（PS15）与PAV时的潮气量显著增加[（443±12）ml与（532±34）ml、（464±23）ml,P〈0．05];PAV时的呼吸频率与气道峰压稍高于PS10时。但差异无统计学意义。PAV支持后,患者的气道闭合压由PS10时的（5．70±0．25）cmH2O降至（4．53±0．25）cmH2O（P〈0．05）,气道压力及吸气触发压力时间乘积也显著降低[由（0．42±0．04）cmH2O降至（0．32±0．03）cmH2O,P〈0．05];而氧合指数与动脉血二氧化碳分压均得到明显改善,与PS15时相近。PAV时的浅快呼吸指数较PS10时无明显改变。结论PAV通过采用正反馈调节机制,成比例地提供同步辅助,显著减少COPD呼吸衰竭患者的自主吸气做功,改善人机同步性。     

慢性阻塞性肺病病人术后无创正压通气的临床研究

目的比较术后常规治疗(SMT)加无创正压通气(NPPV)和单独应用常规治疗对伴有中、重度呼吸功能不全的慢性阻塞性肺病人的疗效。方法择期上腹部和胸腔手术病人24例，术前检查有慢性阻塞性肺病合并中度和重度呼吸功能不全，随机分成2组。对照组术后常规吸氧、静注氨茶碱、雾化吸入α     

慢性阻塞性肺疾病急性加重机械通气患者序贯HFNC与NPPV的疗效比较

目的:比较慢性阻塞性肺疾病急性加重（acute exacerbation of chronic obstructive pulmonary disease, AECOPD）患者以肺部感染控制窗（pulmonary infection control window, PIC-W）为切换点序贯经鼻高流量湿化氧疗（high-...     

Changes in the distribution of ventilation and perfusion associated with separation from mechanical ventilation in patients with obstructive pulmonary disease

A trial of separation from mechanical ventilation may induce an abnormal respiratory pattern and a maldistribution of ventilation-to-perfusion ratios (VA/Q), especially in patients with chronic obstructive pulmonary disease. This study was designed to assess the effects of three different modes of ventilation on the distribution of global and also regional VA/Q in eight patients with chronic obstructive pulmonary disease recovering from acute respiratory failure who remained dependent on mechanical ventilation after more than 5 days of attempted separation from the ventilator. VA/Q distribution was assessed using the multiple inert gas and isotopic scanning methods after 30 min each of controlled mechanical ventilation (CMV), 10 cmH2O inspiratory pressure support, and spontaneous breathing (SB). Controlled ventilation was provided at a respiratory rate ranging from 12 to 18 breaths per min and a tidal volume of 8 ml.kg-1. In comparison to CMV, SB resulted in a decrease in tidal volume (from 512 +/- 144 to 301 +/- 102 ml, P less than 0.01), and an increase in respiratory rate (from 15.5 +/- 3.2 to 27.3 +/- 15.0 breaths per min, P less than 0.05), which increased dead space (+7.1% of minute ventilation), cardiac output (+36%), and the perfusion to areas of low VA/Q (+8.9% of cardiac output) (P less than 0.05, P less than 0.001, and P less than 0.05, respectively). Isotopic scans revealed a horizontal craniocaudal difference of VA/Q in all modes, with the lowest VA/Q zones at the basal part of the lungs (mean basal VA/Q 0.58 in SB and 1.05 in CMV).(ABSTRACT TRUNCATED AT 250 WORDS)     

Physiological and radiological characterisation of patients diagnosed with chronic obstructive pulmonary disease in primary care

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is common although often poorly characterised, particularly in primary care. However, application of guidelines to the management of such patients needs a clear understanding of the phenotype. In particular, the British guidelines for the management of COPD recommend that the diagnosis is based on appropriate symptoms and evidence of airflow obstruction as determined by a forced expiratory volume in one second (FEV(1)) of <80% of the predicted value and an FEV(1)/VC ratio of <70%. METHODS: A study was undertaken of 110 patients aged 40-80 years who had presented to their general practitioner with an acute exacerbation of COPD. The episode was treated at home and, when patients had recovered to the stable state (two months later), they were characterised by full lung function tests and a high resolution computed tomographic (HRCT) scan of the chest. RESULTS: There was a wide range of impairment of FEV(1) which was in the normal range (>/=80%) in 30%, mildly impaired (60-79%) in 18%, moderately impaired (40-59%) in 33%, and severely impaired (<40%) in 19% of patients. A reduced FEV(1)/VC ratio was present in all patients with an FEV(1) of <80% predicted but also in 41% of those with an FEV(1) of >/=80% predicted. Only 5% of patients had a substantial bronchodilator response suggesting a diagnosis of asthma. Emphysema was present in 51% of patients and confined to the upper lobes in most (73% of these patients). HRCT evidence of bronchiectasis was noted in 29% of patients and was predominantly tubular; most (81%) were current or ex-smokers. A solitary pulmonary nodule was seen on 9% of scans and unsuspected lung malignancy was diagnosed in two patients. CONCLUSIONS: This study confirms that COPD in primary care is a heterogeneous condition. Some patients do not fulfil the proposed diagnostic criteria with FEV(1) of >/=80% predicted but they may nevertheless have airflow obstruction. Bronchiectasis is common in this group of patients, as is unsuspected malignancy. These findings should be considered when developing recommendations for the investigation and management of COPD in the community.     

慢性阻塞性肺病病人上腹部手术后鼻罩通气的应用

目的 探讨鼻罩通气在上腹部手术后的呼吸支持作用。方法 ５０例择其行上腹部手术病人,术前肺功能检查证实存在轻度中度阻塞性呼吸功能障碍,术后随机分成两组。（１）对照组：术后常规鼻导管吸氧;（２）鼻罩组：术后即开始以鼻罩行压力支持通气。观察两组病人术后通气功能及血气变化。结果 术后早期给予鼻罩通气,病人的氧合优于对照组,ＰａＣＯ２低于对照组,ＶＣ、ＦＥＶ１．０％及ＭＭＦ均明显高于对照组。结论 慢性阻塞肺     

Exercise in patients with chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) may incur exercise limitation by any one or combination of disturbances in breathing mechanics, oxygen transport, respiratory muscle metabolism or respiratory regulation and sensation. In spite of the increased ventilation demand/capacity ratio in these patients, the relationship between breathing mechanics, respiratory muscle fatigue, the adequacy of alveolar ventilation and the development of exertional dyspnoea is neither clearly defined nor predictable from data obtained with the patient at rest. The issue of oxygen transport during exercise has been complicated by confusion between arterial hypoxia and inadequate volume of oxygen transported to the tissues, which frequently may differ qualitatively and quantitatively. The cardiac output response to exercise in patients with COPD is therefore critical in determining oxygen transport. This response is also impossible to predict from resting lung mechanics, pulmonary arterial blood pressure, arterial oxygen tension or clinical disease profile. Without exercise testing, which includes measurement of all the variables mentioned, it is impossible to define clearly the cause of exercise-induced symptoms in patients with COPD. Exercise training with and without supplemental oxygen has been shown to improve exercise tolerance in these patients, but the precise mechanism of this improvement remains obscure.     

自我管理教育对无创通气治疗慢性阻塞性肺疾病患者的影响

目的探讨自我管理教育对无创通气治疗慢性阻塞性肺疾病患者的影响。方法成立自我管理教育团队,通过开展多种形式(集体教育活动、小组讨论和个别指导)的自我管理教育活动,对47例实施家庭无创通气治疗超过3个月的COPD患者,进行为期6个月的自我管理教育。结果患者PaCO2、PaO2干预前与干预后3个月、6个月比较,差异有统计学意义(均P<0.01);干预后3个月、6个月患者自我管理能力总分,面罩佩戴、管道消毒、滤纸更换、使用时间、用氧方法及时间、压疮预防、自我效能总分显著提高(均P<0.01);除家庭及朋友支持外,干预后3个月、6个月患者生活质量指数总分,各项目如活动能力、日常生活、健康感受及生活前景得分显著升高(均P<0.01)。结论自我管理教育可以提高COPD的自我管理能力和自我效能,从而减少急性加重的次数,改善患者的整体健康状况。     

Induction of sleep apnoea with negative pressure ventilation in patients with chronic obstructive lung disease.

BACKGROUND: Negative pressure ventilation provides intermittent non-invasive ventilatory assistance for patients with advanced chronic obstructive lung disease. Upper airway obstruction during sleep, a reported complication of the technique, may, however, limit its clinical applicability. METHODS: The effects of nocturnal negative pressure ventilation on ventilation and on indices of sleep quality were investigated in five patients with severe chronic obstructive lung disease (mean (SE) FEV1 31% (3%) predicted) who had completed three months of nightly negative pressure ventilation. Subjects underwent overnight polysomnography on consecutive nights, the first night serving as a control and negative pressure ventilation being provided on the second night. Ventilators were adjusted to result in maximum suppression of the peak phasic electromyogram signal from the diaphragm. RESULTS: Negative pressure ventilation resulted in substantial increases in episodes of obstructive apnoea and hypopnoea (mean (SE)/h 59.3 (19.8) v 3.2 (1.3) on control nights). Most obstructive events, however, were associated with under 3% oxygen desaturation, and the lowest recorded values for overnight oxygen saturation were similar on the two study nights. Negative pressure ventilation was also associated with significant increases in the frequencies of movement arousals and changes in sleep stage. CONCLUSIONS: Negative pressure ventilation applied during sleep to patients with advanced chronic obstructive lung disease may result in the development of recurrent episodes of apnoea and hypopnoea as well as altered sleep quality, which could limit its clinical applicability.     

Noninvasive positive pressure ventilation using a helmet in patients with acute exacerbation of chronic obstructive pulmonary disease: a feasibility study

BACKGROUND: Noninvasive positive pressure ventilation (NPPV) with a facemask (FM) is effective in patients with acute exacerbation of their chronic obstructive pulmonary disease. Whether it is feasible to treat these patients with NPPV delivered by a helmet is not known. METHODS: Over a 4-month period, the authors studied 33 chronic obstructive pulmonary disease patients with acute exacerbation who were admitted to four intensive care units and treated with helmet NPPV. The patients were compared with 33 historical controls treated with FM NPPV, matched for simplified acute physiologic score (SAPS II), age, PaCO2, pH, and PaO2:fractional inspired oxygen tension. The primary endpoints were the feasibility of the technique, improvement of gas exchange, and need for intubation. RESULTS: The baseline characteristics of the two groups were similar. Ten patients in the helmet group and 14 in the FM group (P = 0.22) were intubated. In the helmet group, no patients were unable to tolerate NPPV, whereas five patients required intubation in the FM group (P = 0.047). After 1 h of treatment, both groups had a significant reduction of PaCO2 with improvement of pH; PaCO2 decreased less in the helmet group (P = 0.01). On discontinuing support, PaCO2 was higher (P = 0.002) and pH lower (P = 0.02) in the helmet group than in the control group. One patient in the helmet group, and 12 in the FM group, developed complications related to NPPV (P < 0.001). Length of intensive care unit stay, intensive care unit, and hospital mortality were similar in both groups. CONCLUSIONS: Helmet NPPV is feasible and can be used to treat chronic obstructive pulmonary disease patients with acute exacerbation, but it does not improve carbon dioxide elimination as efficiently as does FM NPPV.     

Exercise in patients with chronic obstructive pulmonary disease.

Sporadic visits to the local doctor followed sometimes by changes in oral and inhaled bronchodilators and occasionally by the addition of steroids frequently does little to significantly improve symptoms and function in the disabled patient with COPD. As in other chronic diseases, the management of these patients is facilitated by a team approach in conjunction with general rehabilitation principles. The rationale and practical implementation of such a programme has recently been outlined by the American Association of Cardiopulmonary Rehabilitation. These are multifaceted programmes but a key component, as outlined above, is exercise training. In this brief review the various approaches available have been described. Controversy still reigns regarding the optimal modes of training and there are important differences among the several approaches. Two main groups can be delineated. One emphasises the detailed definition of the impaired physiology with therapeutic measures targeted to specific defects. There is good documentation that, conversely, unstructured programmes that use treadmill and free range walking and cycling also improve endurance for walking. Upper extremity training is of additional benefit. Programmes with as little as three sessions per week of 1-2 hours of low intensity activity have achieved success so we know that simple programmes can be helpful. Moreover, without the necessity for complex testing and training methods these programmes can be implemented with relatively low costs. Future investigations to examine the relationship between improved exercise capacity for walking and arm exercise on the one hand, and the ease of performance of activities of daily living on the other, will help to reinforce the effectiveness of exercise programmes.