Prone position improves lung mechanical behavior and enhances gas exchange efficiency in mechanically ventilated chronic obstructive pulmonary disease patients

Pronation might favorably affect respiratory system (rs) mechanics and function in volume-controlled, mode-ventilated chronic obstructive pulmonary disease (COPD) patients. We studied 10 COPD patients, initially positioned supine (baseline supine [supine(BAS)]) and then randomly and consecutively changed to protocol supine (supine(PROT)), semirecumbent, and prone positions. Rs mechanics and inspiratory work (W(I)) were assessed at baseline (0.6 L) (all postures) and sigh (1.2 L) (supine(BAS) excluded) tidal volume (V(T)) with rapid airway occlusion during constant-flow inflation. Hemodynamics and gas exchange were assessed in all postures. There were no complications. Prone positioning resulted in (a) increased dynamic-static chest wall (cw) elastance (at both V(Ts)) and improved oxygenation versus supine(BAS), supine(PROT), and semirecumbent, (b) decreased additional lung (L) resistance-elastance versus supine(PROT) and semirecumbent at sigh V(T), (c) decreased L-static elastance (at both V(Ts)) and improved CO(2) elimination versus supine(BAS) and supine(PROT), and (d) improved oxygenation versus all other postures. Semirecumbent positioning increased mainly additional cw-resistance versus supine(BAS) and supine(PROT) at baseline. V(T) W(I)-sub-component changes were consistent with changes in rs, cw, and L mechanical properties. Total rs-W(I) and hemodynamics were unaffected by posture change. After pronation, five patients were repositioned supine (supine(POSTPRO)). In supine(POSTPRO), static rs-L elastance were lower, and oxygenation was still improved versus supine(BAS). Pronation of mechanically ventilated COPD patients exhibits applicability and effectiveness and improves oxygenation and sigh-L mechanics versus semirecumbent ("gold standard") positioning. IMPLICATIONS: By assessing respiratory mechanics, inspiratory work, hemodynamics, and gas exchange, we showed that prone positioning of mechanically ventilated chronic obstructed pulmonary disease patients improves oxygenation and lung mechanics during sigh versus semirecumbent positioning. Furthermore, certain pronation-related benefits versus preprone-supine positioning (reduced lung elastance and improved oxygenation) are maintained in the postprone supine position.     

Expiratory flow-volume curves in mechanically ventilated patients with chronic obstructive pulmonary disease

BACKGROUND: Forced expiratory flow-volume curves are commonly used to assess the degree of airflow obstruction in patients with chronic obstructive pulmonary disease (COPD). In mechanically ventilated subjects, expiratory airways obstruction can only be estimated from relaxed expirations. The aim of this study was to quantify the degree of airways obstruction from relaxed expiratory flow-volume curves in mechanically ventilated patients with COPD. METHODS: As measure of airflow obstruction, the effective time constant during the last 50% of expired volume (tau) was calculated. For bedside monitoring, tau was recalculated as the slope of the flow during the last 50% of expired volume (SF50). In order to study reproducibility, the variables were calculated from consecutive breaths and at different levels of end-expiratory lung volume (EEV). The SF50 and the tau-were correlated with the forced expiratory volume in 1 s (FEV1) measured prior to the start of ventilatory support. RESULTS: Twenty-seven patients were studied with a FEV1 expressed as percentage predicted of 31 +/- 12% (mean +/- SD). The SF50 amounted to 19 +/- 10 degrees. A positive linear correlation was established between SF50 and the FEV1, (%pred), (r = 0.90, P < 0.0001). The tau showed an exponential relationship with FEV1 (%pred), (r2 = 0.78). From 5 consecutive breaths the mean variation coefficient of SF50 was 5 +/- 2%. Changes of delta EEV from 0.05 to 1.00 L did not affect the SF50-values. In 12 patients, mechanically ventilated for respiratory diseases other than COPD, mean tau and SF50 were significantly different from the COPD-patients (P < 0.0001). CONCLUSIONS: This study indicates that relaxed expiratory flow-volume curves can be used to assess airflow obstruction in mechanically ventilated patients with COPD. This information can be used to adapt ventilatory settings.     

Effects of positive end-expiratory pressure (PEEP) or prolonged inspiration time on lung mechanics, gas exchange and hemodynamics in differential pulmonary ventilation

In the case of patients with unilateral lung disorders one must anticipate a further increase in the intake volume of the more elastic lung and a decrease in intake volume of the less elastic lung when the inspiratory pressure is increased or the inspiratory time is extended within the framework of mechanical ventilation. Therefore, differential pulmonary ventilation lends itself for the treatment of unilateral damage of the lung by enabling the selective application of a positive end-expiratory pressure or an inverse inspiratory time. For a better understanding of the overlapping pathophysiologic reactions, the changes in lung mechanics, haemodynamics and gas exchange were measured on the healthy lung with unilateral application of a positive and expiratory pressure or an increased inspiratory time. Thirteen male and female patients, who had to undergo intracranial surgery were ventilated with two synchronized servoventilators using a Carlens tube. The positive end expiratory pressure varied in the right lung in spans of 6 cm each, 0-12 cm H2O, inspiratory time varied 34-70%. The left lung was ventilated with a 35% inspiratory time and an end expiratory pressure of 0. The respiratory intake volume was divided up into 45% (left lung) and 55% (right lung) based on the physiological difference in size between the left and right lung. Our results show that a directed unilateral application of a positive end expiratory pressure or an increased inspiratory time does not have any relevant damaging effects on the other lung. It can be expected that in the case of non-differentiated mechanical ventilation the ensuing unequal distribution of alveolar ventilation and perfusion with consecutive increase of intrapulmonary shunt volume can be decreased by the discriminate treatment of each lung.     

The effects of continuous positive pressure ventilation on pulmonary oedema,gas exchange and lung mechanics

Canadian Journal of Anesthesia/Journal canadien d'anesthésie - The effect of continuous positive pressure ventilation was studied in 23 dogs in whom pulmonary oedema was induced by rapid...     

Effects of lung recruitment maneuver and positive end-expiratory pressure on lung volume,respiratory mechanics and alveolar gas mixing in patients ventilated after cardiac surgery

BACKGROUND: It is unclear whether positive end-expiratory pressure (PEEP) is needed to maintain the improved oxygenation and lung volume achieved after a lung recruitment maneuver in patients ventilated after cardiac surgery performed in the cardiopulmonary bypass (CPB). METHODS: A prospective, randomized, controlled study in a university hospital intensive care unit. Sixteen patients who had undergone cardiac surgery in CPB were studied during the recovery phase while still being mechanically ventilated with an inspired fraction of oxygen (FiO2) 1.0. Eight patients were randomized to lung recruitment (two 20-s inflations to 45 cmH2O), after which PEEP was set and kept for 2.5 h at 1 cmH2O above the pressure at the lower inflexion point (14+/-3 cmH2O, mean +/-SD) obtained from a static pressure-volume (PV) curve (PEEP group). The remaining eight patients were randomized to a recruitment maneuver only (ZEEP group). End-expiratory lung volume (EELV), series dead space, ventilation homogeneity, hemodynamics and PaO2 (oxygenation) were measured every 30 min during a 3-h period. PV curves were obtained at baseline, after 2.5 h, and in the PEEP group at 3 h. RESULTS: In the ZEEP group all measures were unchanged. In the PEEP group the EELV increased with 1220+/-254 ml (P<0.001) and PaO2 with 16+/-16 kPa (P<0.05) after lung recruitment. When PEEP was discontinued EELV decreased but PaO2 was maintained. The PV curve at 2.5 h coincided with the curve obtained at 3 h, and both curves were both steeper than and located above the baseline curve. CONCLUSIONS: Positive end-expiratory pressure is required after a lung recruitment maneuver in patients ventilated with high FiO2 after cardiac surgery to maintain lung volumes and the improved oxygenation.     

Propofol induces bronchodilation in mechanically ventilated chronic obstructive pulmonary disease (COPD) patients

The aim of this study was to evaluate the effects of propofol administration (2 mg · kg^-1 i.v.) on the airways resistances and respiratory mechanics of patients affected by COPD exacerbation, requiring mechanical ventilation. Twenty patients required anaesthesia for diagnostic or therapeutic procedures. Fourteen consecutive patients were divided at random into two groups: Group P received propofol and Group C (control) received only Intralipid 10%; an additional group of six patients received i.v. flunitrazepam (0.03 mg · kg^-1). Lung mechanics (dynamic and static compliance, peak inspiratory pressure, intrinsic positive and expiratory pressure, minimal and maximal resistances of the respiratory system) were evaluated in basal conditions and 3 and 6 min after propofol, Intralipid or flunitrazepam administration. We did not observe significant variations of the evaluated variables after Intralipid or flunitrazepam (Groups C and F), while in patients who received propofol (Group P), we observed the following modifications: dynamic compliance increased from 2.3 ± 0.3 to 2.8 ± 0.4 ml · kPa^-1 (P<0.05), peak inspiratory pressure decreased from 3.3 ± 0.7 to 2.8 ± 0.4 kPa (P <0.05), minimal resistances of the respiratory system (that mainly reflect airways resistances) decreased from 1 ± 0.2 to 0.7 ± 0.2 kPa · 1^-1 · s^-1 (P <0.01). Our results suggest that propofol induces bronchodilation in mechanically ventilated COPD patients, and that this effect is not related specifically to the induction of general anesthesia.     

呼气末正压通气对腹腔热灌注化疗患者呼吸力学及肺功能的影响

目的探讨不同呼气末正压通气对腹腔热灌注化疗患者呼吸力学及肺功能的影响。方法选择择期行腹膜癌热灌注化疗的患者90例,男55例,女35例,年龄40~70岁,ASAⅠ~Ⅲ级。随机分为三组,每组30例。A组为容量控制通气(VCV)组,VT10 ml/kg;B组为VCV+低PEEP组,VT6ml/kg,PEEP 5cm H_2O;C组为VCV+高PEEP组,VT6ml/kg,PEEP 10cm H_2O;术中调整RR维持PETCO2 35~45 mm Hg。于气管插管后5 min(T_1)、腹腔热灌注化疗开始前(T2)、化疗结束时(T_3)、气管拔管前(T4)记录气道峰压(Ppeak)、气道平台压(Pplat)和平均气道压(Pmean),计算动态肺顺应性(C_(dyn))。并取桡动脉血进行血气分析,计算氧合指数(OI)、呼吸指数(RI)、肺泡-动脉血氧分压差(A-aDO_2)及死腔率(VD/VT)。记录术后7d内肺部相关并发症情况。结果与A组比较,T_1~T_4时B、C组Ppeak、Pplat、A-aDO_2和RI明显降低,OI和VD/VT明显升高(P0.05);T_2~T_4时B、C组Pmean明显降低,Cdyn和PaO_2明显升高(P0.05)。与T_1比较,T_2~T_4时A组Ppeak、Pplat和Pmean明显升高,C_(dyn)明显降低(P0.05);T_3时B组Ppeak和Pplat明显升高(P0.05),T_2~T_4 Pmean明显升高(P0.05),T3、T4时C_(dyn)明显降低(P0.05);T_2~T_4时C组Ppeak、Pplat和Pmean明显升高(P0.05),T_3、T_4时Cdyn明显降低(P0.05)。与T0时比较,T2~T4时三组PaO_2和OI明显降低,A-aDO_2、RI和VD/VT明显升高(P0.05)。术后7d内B、C组肺部感染、低氧血症和肺不张的发生率明显低于A组(P0.05)。结论小潮气量(6ml/kg)联合PEEP(5cm H_2O)通气可以显著改善腹膜癌患者术中热灌注期间肺功能,降低围术期肺部并发症的发生风险。     

盐酸戊乙奎醚对慢性阻塞性肺病病人呼吸力学参数的影响

目的研究应用盐酸戊乙奎醚对慢性阻塞性肺病(chronic obstructive pulmonary dis-ease,COPD)病人气管内插管应用呼吸机后呼吸力学参数的影响。方法COPD病人66例随机均分为两组:盐酸戊乙奎醚组(Ⅰ组):气管插管应用呼吸机前静注盐酸戊乙奎醚1mg;对照组(Ⅱ组):不给予任何支气管扩张药物。分别观察并监测气管内插管应用呼吸机后1、4和6h的呼吸力学参数(气道压力、气道阻力和胸肺顺应性)。结果Ⅰ组各个时间点的气道峰压、气道平台压以及气道阻力明显低于Ⅱ组(P<0.05),而胸肺顺应性明显高于Ⅱ组(P<0.05)。结论盐酸戊乙奎醚可明显降低COPD病人气管内插管后的气道压力和气道阻力,增加胸肺顺应性。     

Influences of pleural effusion on respiratory mechanics,gas exchange,hemodynamics, and recruitment effects in acute respiratory distress syndrome

Background

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) cause substantial morbidity and mortality despite improvements in the understanding of lung injury and advances in treatment. Recruitment maneuver (RM) with high sustained airway pressures is proposed as an adjunct to mechanical ventilation to maintain alveolar patency. In addition, RM has been advocated to improve pulmonary gas exchange. However, many factors may influence responses to RM and the effect of pleural effusion (PLE) is unknown.

Method

There were four groups in this study (n = 6 in each group). Group A was the control group, group B was the PLE group, group C was ARDS with RM, and group D was ARDS with PLE and RM. RM was performed in groups C and D, consisting of a peak pressure of 45 cm H₂O with positive end-expiratory pressure of 35 cm H₂O sustained for 1 min. Arterial blood gas, systemic and pulmonary hemodynamics, lung water, and respiratory mechanics were measured throughout.

Result

After the induction of ALI/ARDS, there were significant decreases in partial pressure of oxygen in arterial blood, mean arterial pressure, systemic vascular resistance, and lung compliance. There were also significant increases in the alveolar–arterial O₂ tension difference, partial pressure of arterial carbon dioxide, mean pulmonary arterial pressure, pulmonary vascular resistance, and lung water. The RM improved oxygenation, which was attenuated by PLE.

Conclusions

ALI/ARDS leads to poor oxygenation and hemodynamics. RM results in improved oxygenation, but this improvement is attenuated by PLE.     

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。     

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。     

盐酸戊乙奎醚对慢性阻塞性肺病患者血流动力学和微循环的影响

目的 观察盐酸戊乙奎醚对慢性阻塞性肺病(COPD)患者血流动力学和微循环的影响.方法 40例慢性阻塞性肺病患者均给予气管插管呼吸机辅助呼吸,随机分为两组,盐酸戊乙奎醚组(Ⅰ组):每12小时静注盐酸戊乙奎醚1 mg;氨茶碱组(Ⅱ组):氨茶碱持续泵入0.6 mg·kg-1·min-1.分别监测用药后2、4和6 h的BP、FIR和体温、血乳酸(ABL)含量、尿量.结果 两组患者血流动力学差异无统计学意义.与Ⅱ组比较,用药后4、6 hⅠ组体温升高(P＜0.05),ABL含量降低(P＜0.05),尿量增多(P＜0.05).结论 盐酸戊乙奎醚应用于COPD患者不会引起血流动力学的改变;对微循环有明显改善.     

Lung collapse and gas exchange during general anesthesia: effects of spontaneous breathing, muscle paralysis, and positive end-expiratory pressure

Lung densities (atelectasis) and pulmonary gas exchange were studied in 13 supine patients with no apparent lung disease, the former by transverse computerized tomography (CT) and the latter by a multiple inert gas elimination technique for assessment of the distribution of ventilation/perfusion ratios. In the awake state no patient had clear signs of atelectasis on the CT scan. Lung ventilation and perfusion were well matched in most of the patients. Three patients had shunts corresponding to 2-5% of cardiac output, and in one patient there was low perfusion of poorly ventilated regions. CT scans after 15 min of halothane anesthesia and mechanical ventilation showed densities in dependent lung regions in 11 patients. A shunt was present in all patients, ranging from 1% in two patients (unchanged from the awake state) to 17%. Ventilation of poorly perfused regions was noted in nine patients, ranging from 1-19% of total ventilation. The magnitude of the shunt significantly correlated to the size of dependent densities (r = 0.84, P less than 0.001). Five patients studied during spontaneous breathing under anesthesia displayed both densities in dependent regions and a shunt, although of fairly small magnitude (1.8% and 3.7%, respectively). Both the density area and the shunt increased after muscle paralysis. PEEP reduced the density area in all patients but did not consistently alter the shunt. It is concluded that the development of atelectasis in dependent lung regions is a major cause of gas exchange impairment during halothane anesthesia, during both spontaneous breathing and mechanical ventilation, and that PEEP diminishes the atelectasis, but not necessarily the shunt.     

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     

The effect of incremental positive end-expiratory pressure on right ventricular hemodynamics and ejection fraction

The effects of incremental positive end-expiratory pressure (PEEP) on right ventricular (RV) function were evaluated in 36 (n = 36) ventilated patients. Positive end-expiratory pressure was increased from 0 (baseline) to 20 cm H2O in 5-cm H2O increments and RV hemodynamics and thermally derived right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVI), and right ventricular end-systolic volume index (RVESVI) were computed. Right ventricular contractility was determined from the analysis of RV systolic pressure-volume relations. Right ventricular ejection fraction declined from 42 +/- 8% at baseline to 30 +/- 9% at 20 cm H2O PEEP. Right ventricular end-diastolic volume index declined between 0 and 5 cm H2O PEEP (103 +/- 42 to 92 +/- 34 ml.m-2) and then increased to 113 +/- 40 at 20 cm H2O PEEP. Right ventricular end-systolic volume index increased from 60 +/- 31 ml.m-2 at baseline to 79 +/- 34 ml.m-2 at 20 cm H2O PEEP. The slope (E) of the relation of RV peak systolic pressure to RV end-systolic volume index decreased from 0.26 mm Hg.m2.ml-1 between PEEP of 0-15 cm H2O to 0.05 mm Hg.m2.m-1 at PEEP greater than 15 cm H2O. It is concluded that low levels of PEEP have a predominant preload reducing effect on the RV. Above 15 cm H2O PEEP, RV volumes increase and E decreases, consistent with increased RV afterload and a decline in RV contractility.     

静脉注射盐酸戊乙奎醚或多索茶碱对慢性阻塞性肺疾病患者非开胸手术时呼吸力学的影响

目的 评价静脉注射盐酸戊乙奎醚或多索茶碱对慢性阻塞性肺疾病(COPD)患者非开胸手术时呼吸力学的影响.方法 择期行非开胸手术的COPD患者135例,年龄55～86岁,体重44～78 g,ASA分级Ⅱ或Ⅲ级,采用随机数字表法,将其随机分为3组(n=45):对照组(c组)、盐酸戊乙奎醚组(P组)和多索茶碱组(D组).麻醉诱导:静脉注射芬太尼4μg/kg、异丙酚1.5 mg/kg和顺阿曲库铵0.2 mg/kg,气管插管后行机械通气,维持PErCO2 40mm Hg.气管插管后5 rin时P组静脉注射盐酸戊乙奎醚0.01 mg/kg,D组静脉注射多索茶碱4 mg/kg,C组静脉注射等容量生理盐水.麻醉维持:静脉输注异丙酚5mg·kg-1·h-1和顺阿曲库铵0.2 mg·kg-1·h-1,间断静脉注射芬太尼.术中维持听觉诱发电位指数15～20.于给药前即刻、给药后30、45和60min时,记录气道峰压、气道平台压、肺顺应性和气道阻力.结果 与C组比较,给药后各时点P组和D组气道峰压、气道平台压和气道阻力均降低,肺顺应性升高(P＜0.05);P组和D组各时点呼吸力学各参数比较差异无统计学意义(P＞0.05).结论 静脉注射盐酸戊乙奎醚和多索茶碱均可改善COPD患者非开胸手术时的呼吸力学,有利于通气.

Abstract：

Objective To investigate the effects of intravenous penehyclidine hydrochloride or doxofylline on respiratory mechanics during non-thoracotomy in patients with chronic obstructive pulmonary disease (COPD).Methods One hundred and thirty-five ASA Ⅱ or Ⅲ patients with COPD, aged 55-86 yr, weighing 44-78 kg,scheduled for elective non-thoracotomy under general anesthesia, were randomly divided into 3 groups ( n = 45 each): control group (group C), penehyclidine hydrochloride group (group P) and doxofylline group (group D).Anesthesia was induced with fentanyl 4 μg/kg, propofol 1.5 rg/kg and cis-atracurium 0.2 mg/kg. The patients were tracheal intubated and mechanically ventilated. PETCO2 was maintained at 40 mm Hg. At 5 rin after tracheal intubation, penehyclidine hydrochloride 0.01 mg/kg was injected intravenously in group P, and doxofylline 4 mg/kg was injected intravenously in group D. The equal volume of normal saline was injected intravenously in group C. Anesthesia was maintained with propofol 5 mg· kg- 1 · h- 1, eis-atracurium 0.2 mg· kg- 1 · h- 1, and intermittent iv boluses of fentsnyl. The auditory evoked potential index was maintained at 15-20 during operation. The peak airway pressure, airway plateau pressure, lung compliance and airway resistance were recorded immediately before administration, and at 30, 45 and 60 rin after administration. Results Compared with group C, the peak airway pressure, airway plateau pressure and airway resistance were significantly decreased, while the lung compliance was significantly increased at each time point after administration in groups P and D ( P ＜ 0.05 ). There was no significant difference in the parameters of respiratory mechanics at each time point between group P and group D ( P ＞ 0.05). Conclusion Both intravenous penehyclidine hydrochloride and doxofylline can improve respiratory mechanics during non-thoracotomy in patients with COPD.     

Effects of positive end-expiratory pressure, tidal volume and perflubron doses on gas exchange during partial liquid ventilation

The efficacy of gas exchange during partial liquid ventilation (PLV) may be affected by positive end-expiratory pressure (PEEP), tidal volume (TV) and perflubron (PFOB) dose. The purpose of the present study was to clarify which factors were important for improving gas exchange during PLV. Fourteen rabbits were anesthetized and tracheostomized. Lung was introduced with intravenous oleic acid combined with saline lung lavage. After obtaining control data, PFOB 7.5 ml.kg-1 was instilled into the trachea, and ventilation settings were changed sequentially [1. TV: 10 ml.kg-1 (mTV), 2. mTV with PEEP, 3. TV: 15 ml.kg-1 (hTV), 4. hTV with PEEP]. PEEP level was set to the lower inflection point. The PFOB dose was increased to 15 ml.kg-1 and measurements were repeated under each ventilation setting. PEEP increased PaO2 in all ventilation settings. In hTV ventilation settings, incremental dose of PFOB significantly increased PaO2. The PaO2 values of all hTV ventilation settings were significantly higher than those of corresponding ventilation setting of mTV. Pulmonary compliance was significantly decreased with PEEP in hTV ventilation in addition to 15 ml.kg-1 PFOB. The results suggested that adequate gas tidal volume was the most important factor for improving gas exchange during PLV. However, PEEP or larger dose of PFOB should be avoided because they may decrease pulmonary compliance.     

Differential ventilation and selective positive end-expiratory pressure: effects on patients with acute bilateral lung disease

Eleven patients with acute respiratory failure due to diffuse, bilateral lung disease were treated according to a new ventilation concept. The patients were intubated with a double-lumen catheter and positioned in the lateral decubital posture. With two synchronized ventilators, each lung received half of the tidal volume (VT), in accordance with its presumed perfusion (differential ventilation--DV), and the end-expiratory pressure was increased locally in the dependent lung (selective PEEP). DV with and without selective PEEP was compared with conventional ventilation with free distribution of VT, with and without PEEP applied to both lungs. The major findings were that DV with a selective PEEP of 12 cmH2O to the dependent lung decreased venous admixture by 38% (P less than 0.01) in comparison with conventional ventilation with no PEEP. Furthermore, it was found that selective PEEP, in contrast to general PEEP, had no deleterious effect on cardiac output. Consequently, DV with selective PEEP increased arterial oxygen tension by 23% (P less than 0.05) compared with general PEEP and by 46% (P less than 0.001) in comparison with conventional ventilation with no PEEP.