慢性阻塞性肺病稳定期与支气管哮喘缓解期肺通气功能比较

目的：比较慢性阻塞性肺病稳定期和支气管哮喘缓解期肺通气功能。方法：用肺功能仪逐项对二者进行肺通气功能测定并进行分析。结果：二者的肺容积、分钟通气量及小气道功能有显著性差异。结论：慢性阻塞性肺病稳定期仍表现为阻塞性通气障碍，而支气管哮喘缓解期患者通气功能正常。     

肺开放通气治疗急性呼吸窘迫综合征临床疗效分析

目的:通过大潮气量、高呼吸末正压(PEEP)肺开放策略,探索容量辅助控制通气、小潮气量、呼吸末正压治疗下,难以纠正的急性呼吸窘迫综合征(ARDS)低氧血症的策略。方法:容量辅助控制通气,潮气量为6mL/kg～8mL/kg,PEEP为10cmH2O～15cmH2O,FO2<60%机械通气过程中,提高PEEP20cmH2O～30cmH2O,潮气量(VT)15mL/kg,氧浓度为100%,开放通气2min～3min。低氧血症纠正,恢复基础通气模式和参数。结果:PEEP20cmH2O～30cmH2O,潮气量(VT)15mL/kg肺开放治疗ARDS有效率达96.87%(31/32)。结论:肺开放通气,促使萎陷肺泡开放,改善通气血流比例,提高PaO2,有效纠正低氧血症,为治疗ARDS的有效策略。     

间歇负压通气对实验犬通气和血流动力学的影响

目的：观察间歇负压通气时通气压力对实验犬的通气和血流动力学的影响。方法：通过实验犬股静脉插入Swan-Ganz漂浮导管,比较不同负压水平时实验犬的潮气量和血流动力学的变化。结果：间歇负压通气能够增加实验犬潮气量,但对血流动力学无影响。结论：间歇负压通气是一种安全、无创和有效的通气方式。     

不同潮气量机械通气对重症患者心脏舒张功能的影响

目的比较不同潮气量水平通气对重症患者心脏舒张功能的影响。方法统计重庆市北部新区第一人民医院重症医学科2008~2013年进行机械通气的患者208例,在双水平正压通气(BIPAP)模式下,调整吸气压使潮气量(VT)分别维持于6、8、10、15mL/kg水平,其他呼吸机支持条件不变,以上各种条件维持30min后测量中心静脉压(CVP)及血流动力学,心脏彩超监测左室射血分数(LEVF)。根据心脏指数(CI)分为心功能正常组(CI≥2.2L·min-1·m-2)和心功能低下组(CI<2.2L·min-1·m-2),通气过程中若出现心率、血压明显下降或者恶性心律失常,则立即调整呼吸机参数。为排除PEEP(呼气末正压)的影响,各组PEEP均设定在5cmH2O水平。结果在相同呼吸模式条件下,CI、胸内血容量指数(ITBVI)、舒张早期频谱幅度/舒张末期频谱幅度(E/A)比值随着潮气量水平的升高而减小,平均气道压(Pmean),体循环血管阻力指数(SVRI)随着潮气量水平升高而升高,差异有统计学意义(P<0.05)。而心率(HR)、LEVF在各组潮气量水平间无明显变化。心功能正常组在相同呼吸模式、相同呼吸支持条件下的CI、ITBVI、Pmean均无明显差异。心功能低下组患者中,8mL/kg潮气量水平组CI较高,而在6、10、15mL/kg潮气量水平组,CI较低,差异有统计学意义(P<0.05)。结论在机械通气过程中应设置潮气量于6~8mL/kg,对血流动力学无明显影响,适用于心功能正常和心功能低下患者。     

肺保护性机械通气和传统机械通气治疗新生儿急性呼吸衰竭临床观察

目的观察传统机械通气和肺保护性机械通气治疗新生儿急性呼吸衰竭的临床情况。方法选择40例急性呼吸衰竭新生儿患儿，随机分为两组，A组用传统机械通气，B组用肺保护性机械通气。A组潮气量（VT）10～12ml／kg，气道峰压（PIP）〈25cmH2O，呼气末正气（PEEP）（5．0±1．5）cmH2O，呼吸频率（RR）60次／min；B组VT为5～8ml／kg，PEEP为（7．6±1．5）cmH2O，RR为40～60次／分。结果转归比较：两组所有病人均治愈。呼吸机参数比较：两组在维持SaO2在90％以上且PaCO2〈8．0kPa的呼吸机各项参数，A组的VT（10．11±1．20）ml／kg、PIP（24．01±2．10）cmH2O、PEEP（7．50±1．50）cmH2O，两组VT、PIP差异有非常显著性（P〈0．01），两组PEEP的差异无显著性（P〉0．05）。血气比较：pH值A组7．35±0．10，B组7．25±0．15；PaCO2为A组（6．90±0．72）kPa，B组（93．0±2.8）kPa；两组pH、PaCO2、SaCO2（％）值比较差异均无显著性（P均〉0．05）。两组并发症比较：A组肺损伤4例，循环系统并发症3例，B组无。结论传统策略和肺保护性策略通气均能治愈新生儿急性呼吸衰竭，但后者并发症较少。在维持PH、PaCO2、PaO2、SaO2基本相同的情况下，肺保护性通气的呼吸机参数VT和PIP较传统通气明显降低。     

阻塞性通气功能障碍患者肺切除术后肺功能评价

本文探讨阻塞性通气功能障碍患者肺叶切除术后肺功能及动脉血气的改变。由于术后肺组织代偿功能成退,肺功能随肺切除范围顺序递减的幅度比肺功能正常者的幅度增大,特别是MVV更显著,PaO_2术后明显下降,与术前比较有明显差异(P<0.05)。最大通气量测定配合动脉血气分析可对大部分手术病例的手术指征和安全性作出较于靠的评价。     

慢性阻塞性肺疾病机械通气治疗呼吸参数的变化及意义

目的 通过慢性阻塞性肺疾病（COPD）患者机械通气治疗中呼吸参数的变化，进一步探讨机械通气的作用。方法 42例COPD合并慢性呼吸衰竭急性加重的患者应用无创或有创机械通气（CPAP、SIMV模式）治疗，比较机械通气前后呼吸参数的变化及其意义。结果 42例患者机械通气后所选定的呼吸参数均有不同程度的好转改变，无创通气及有创通气治疗后呼吸频率（RR）、呼出潮气量（EVT）、分钟通气量（MV）、平均气道压（MAP）与治疗前比较差异均有显著性（P〈0.01）。结论 无创或有创机械通气治疗COPD合并慢性呼吸衰竭急性加重的患者，有助于呼吸肌疲劳的改善，克服气道阻力和肺顺应性降低，从而使各项呼吸参数均得到改善。     

肺功能锻炼对阻塞性通气功能障碍肺癌患者肺功能及手术耐受性的影响

目的探讨肺功能锻炼对不同程度阻塞性通气功能障碍肺癌患者肺功能及手术耐受性的影响。 方法对103例肺功能不能耐受手术的阻塞性通气功能障碍（轻度26例,中度53例,重度24例）肺癌患者进行肺功能强化训练,持续训练时间5~7d。于锻炼前、后对患者主要肺功能指标［包括肺活量（VC）、肺活量百分比（VC%）、用力肺活量（FVC）、用力肺活量百分比（FVC%）、第1秒用力呼气容积（FEV1）、第1秒用力呼气容积百分比（FEV1%）、最大自主通气量百分比（MVV%）、最大呼气流量百分比（PEF%）、第1秒钟用力呼气容积与用力肺活量比值（FEV1/FVC）、最大中期呼气流量百分比（MMEF%）］进行检测,并记录患者术后并发症发生情况。 结果本研究入选轻、中、重度通气功能障碍组患者经肺功能强化训练后,发现其肺功能指标VC、VC%、FVC、FVC%、FEV1、FEV1%、MVV%及PEF%均较入选时明显改善（P<0.05）;所有患者锻炼前、后其FEV1/FVC均无显著变化（P>0.05）;中度障碍组患者锻炼后其MMEF%较锻炼前明显改善（P<0.05）。轻、中、重度障碍组分别有19例（73.08%）、34例（64.15%）、8例（33.33%）患者达到手术要求并施以手术治疗,轻、重度障碍组和中、重度障碍组手术率间差异均具有统计学意义（P<0.05）。61例手术患者术后共有27例（44.26%）出现并发症,与呼吸功能正常的对照组术后并发症发生率（20.00%）间差异具有统计学意义（P<0.05）。 结论肺功能锻炼能有效提高阻塞性通气功能障碍肺癌患者手术耐受性,但患者术后风险仍明显高于通气功能正常肺癌患者。     

胸外负压机械辅助通气的临床应用──附22例报告

采用胸外负压呼吸机对２２例以慢性阻塞性肺疾病为主的呼吸功能不全患者进行胸外负压辅助通气，同时进行血气分析监测，其中４例置Ｓｗａｎ－Ｇａｎｚ导管行血流动力学监测。结果发现胸外负压辅助通气对血气分析有明显改善，对血流动力学影响较小。文中对胸外负压辅助通气的临床应用进行了讨论。     

慢阻肺呼吸衰竭患者机械通气后BiPAP的应用

目的：了解双相气道正压通气（ＢｉＰＡＰ）辅助通气在慢性阻塞性肺病（ＣＯＰＤ）呼吸衰竭（呼吸）患者机械通气撤机后的应用价值。方法：观察７例ＣＯＰＤⅡ型呼衰患者机械通气撤机后应用ＢｉＰＡＰ辅助通气，采用自主呼吸（Ｓ）模式，每天两次，每次１小时，通气过程中监测血气变化另选４例，１２例次监测潮气量（ＶＴ）、呼吸频率（Ｒ）、动态血氧饱和度（ＳａＯ２）、血压、心电图、呼气末二氧化碳分压（ＰｅｔＣＯ２）。结果：     

Negative- versus positive-pressure ventilation in intubated patients with acute respiratory distress syndrome

ABSTRACT: INTRODUCTION: Recent experimental data suggest that continuous external negative-pressure ventilation (CENPV) results in better oxygenation and less lung injury than continuous positive-pressure ventilation (CPPV). The effects of CENPV on patients with acute respiratory distress syndrome (ARDS) remain unknown. METHODS: We compared 2 h CENPV in a tankrespirator ("iron lung") with 2 h CPPV. The six intubated patients developed ARDS after pulmonary thrombectomy (n = 1), aspiration (n = 3), sepsis (n = 1) or both (n = 1). We used a tidal volume of 6 ml/kg predicted body weight and matched lung volumes at end expiration. Haemodynamics were assessed using the pulse contour cardiac output (PiCCO) system, and pressure measurements were referenced to atmospheric pressure. RESULTS: CENPV resulted in better oxygenation compared to CPPV (median ratio of arterial oxygen pressure to fraction of inspired oxygen of 345 mmHg (minimum-maximum 183 to 438 mmHg) vs 256 mmHg (minimum-maximum 123 to 419 mmHg) (P < 0.05). Tank pressures were -32.5 cmH2O (minimum-maximum -30 to -43) at end inspiration and -15 cmH2O (minimum-maximum -15 to -19 cmH2O) at end expiration. NO Inspiratory transpulmonary pressures decreased (P = 0.04) and airway pressures were considerably lower at inspiration (-1.5 cmH2O (minimum-maximum -3 to 0 cmH2O) vs 34.5 cmH2O (minimum-maximum 30 to 47 cmH2O), P = 0.03) and expiration (4.5 cmH2O (minimum-maximum 2 to 5) vs 16 cmH2O (minimum-maximum 16 to 23), P =0.03). During CENPV, intraabdominal pressures decreased from 20.5 mmHg (12 to 30 mmHg) to 1 mmHg (minimum-maximum -7 to 5 mmHg) (P = 0.03). Arterial pressures decreased by approximately 10 mmHg and central venous pressures by 18 mmHg. Intrathoracic blood volume indices and cardiac indices increased at the initiation of CENPV by 15% and 20% (P < 0.05), respectively. Heart rate and extravascular lung water indices remained unchanged. CONCLUSIONS: CENPV with a tank respirator improved gas exchange in patients with ARDS at lower transpulmonary, airway and intraabdominal pressures and, at least initially improving haemodynamics. Our observations encourage the consideration of further studies on the physiological effects and the clinical effectiveness of CENPV in patients with ARDS.     

Physiological effects of constant versus decelerating inflation flow in patients with chronic obstructive pulmonary disease under controlled mechanical ventilation

OBJECTIVE: To study the cardiorespiratory effects of inspiratory flow rate and waveform in COPD patients. DESIGN: Prospective physiological investigation with randomized allocations of experimental conditions. SETTING: A 14-bed medical ICU in a 1000-bed university hospital. PATIENTS AND PARTICIPANTS: Ten COPD intubated, sedated and paralyzed patients with chronic obstructive pulmonary disease (COPD), mechanically ventilated for acute respiratory failure. INTERVENTIONS: In volume-controlled mode, three inflation flow rates of 0.40, 0.70, and 1.10 l/s for 20 min with a constant (CF) or a decelerating (DF) inflation flow profile. Each patient received all six experimental conditions in a random order. Tidal volume and respiratory frequency were similar during the experimental conditions. MEASUREMENTS AND RESULTS: Arterial blood gases, hemodynamics ( n=8), and respiratory mechanics were measured with zero end expiratory pressure. Between flow rates the median (25th-75th percentiles) values of PaO(2)/FIO(2) were 232 (132-289), 253 (161-338), 231 (163-352) for CF and 253 (143-331), 249 (164-360), 231 mmHg (187-351), for DF, respectively; the maximal airway pressures were 25.6, 28.3, 34.6 cmH(2)O for CF and 21.7, 29.6, 34.8 cmH(2)O for DF, respectively, the mean airway pressures were 8.9, 6.1, 5.4 cmH(2)O for CF and 9.1, 7, 6.5 cmH(2)O for DF, respectively. CONCLUSIONS: Changing the ventilator in volume-controlled mode with a DF or CF profile has no significant cardiorespiratory effect in intubated COPD patients mechanically ventilated for acute respiratory failure.     

呼气负压技术检测呼气流速受限在慢性阻塞性肺疾病中的应用

目的:应用呼气负压技术(NEP)检测慢性阻塞性肺疾病(COPD)患者的呼气流速受限(EFL)。方法:94例COPD患者在坐位及卧位时应用NEP方法检测EFL,即在患者潮气呼吸时于患者口部施加一个-5cmH2O的负压,通过比较施加负压前后的潮气流速-容积曲线来检测EFL。采用EFL五分法与经典的一秒钟用力呼气量(FEV1)方法进行比较。结果:55例COPD患者在坐位及卧位时均存在EFL;23例患者仅于卧位时存在EFL;16例患者坐位及卧位均无EFL。EFL五分法与经典FEV1方法判断肺功能损害程度较一致。EFL五分法与COPD患者的主观呼吸困难分级有更好的相关性。结论:①COPD患者在平静呼吸时EFL普遍存在;②NEP提供了一种简便、快速、无创的方法来检测EFL;③EFL五分法与COPD患者的呼吸困难分级有很好的相关性。     

Tidal volume delivery during high-frequency oscillatory ventilation in adults with acute respiratory distress syndrome

OBJECTIVE: a) Characterize how ventilator and patient variables affect tidal volume during high-frequency oscillatory ventilation; and b) measure tidal volumes in adults with acute respiratory distress syndrome during high-frequency oscillatory ventilation. DESIGN: Observational study. SETTING: Research laboratory and medical intensive care unit. PATIENTS: Test lung and patients with acute respiratory distress syndrome. INTERVENTIONS: Using a previously validated hot wire anemometer placed in series with a Sensormedics 3100B high-frequency ventilator, an endotracheal tube, and a test lung, tidal volume was measured at different combinations of frequency (4, 6, 8, 10, and 12 Hz), pressure amplitude (50, 60, 70, 80, and 90 cm H2O), mean airway pressure (20, 30, and 40 cm H2O), test lung compliance (10, 30, and 50 mL/cm H2O), endotracheal tube internal diameter (6, 7, and 8 mm), bias flow (20, 30, and 40 L/min), and inspiratory/expiratory ratio (1:2 and 1:1). In patients, tidal volume was measured at baseline ventilator settings and at baseline frequency +/-2 Hz and baseline pressure amplitude +/-10 cm H2O. MEASUREMENTS AND MAIN RESULTS: Measured tidal volumes were 23-225 mL during high-frequency oscillatory ventilation of the test lung. A 2-Hz increase in frequency and a 10-cm H2O increase in pressure amplitude caused a 21.3% +/- 4.1% decrease and 21.4% +/- 3.4% increase in tidal volume, respectively. Decreasing endotracheal tube internal diameter from 8 mm to 7 mm and from 7 mm to 6 mm caused a 15.3% +/- 1.7% and 18.9% +/- 2.1% reduction in tidal volume, respectively. Increasing bias flow from 20 L/min to 30 L/min increased tidal volume by 11.2% +/- 3.9%. Further increases in bias flow, changes in compliance, and changes in mean airway pressure had little effect. Tidal volumes measured in acute respiratory distress syndrome patients were 44-210 mL. A 2-Hz increase in frequency was associated with a 23.1% +/- 6.3% decrease in tidal volume. In contrast to the test lung data, a 10-cm H2O increase in pressure amplitude resulted in only a 5.6% +/- 4.5% increase in tidal volume. CONCLUSIONS: Tidal volumes are not uniformly small during high-frequency oscillatory ventilation. The primary determinant of tidal volume in adults with acute respiratory distress syndrome during high-frequency oscillatory ventilation with the Sensormedics 3100B is frequency. Test lung findings suggest that endotracheal tube internal diameter is also an important determinant of tidal volume.     

机械通气对急性肺损伤大鼠细胞凋亡的影响

目的 研究不同潮气量及不同呼气末正压(PEEP)水平对急性肺损伤(AU)大鼠支气管和肺组织细胞凋亡的影响,并初步探讨细胞凋亡在呼吸机相关性肺损伤(VILI)中的作用机制.方法 选用40只SD大鼠,制作ALI模型,随机(随机数字法)分为:(1)小潮气量组(LV组),潮气量8 mL/kg,不加PEEP;(2)大潮气量组,潮气量30 mL./kg,不加PEEP;(3)小潮气量+ 2PEEP组(LV2P组),潮气量8 mL/kg,同时给PEEP 2 cmH2O(1 crnH2O =0.098 kPa);(4)小潮气量+5PEEP组(LV5P组),潮气量8 mL/kg,同时给PEEP 5 cmH2O;(5)小潮气量+8PEEP组(LV8P组),潮气量8 mL/kg,同时给PEEP 8 cmH2O.通气2h后处死动物,留取肺标本.用脱氧核糖核苷酸末端转移酶介导的末端标记法(TUNEL)分析肺组织中的细胞凋亡情况,用免疫组化法检测肺组织中caspase-3蛋白的表达及分布.结果 大潮气量组支气管和肺组织细胞凋亡的明显增加(P＜0.01),caspase-3蛋白酶表达最强.采用PEEP后,支气管和肺组织细胞凋亡减少,capase-3蛋白酶表达弱阳性,以LV5P组最为显著(P＜0.01).结论 小潮气量对肺组织有保护作用,采用PEEP后保护作用更加明显,细胞凋亡在VILI的发生中有重要作用.     

Influence of respiratory rate on gas trapping during low volume ventilation of patients with acute lung injury

OBJECTIVE: Reduction in tidal volume (Vt) associated with increase in respiratory rate to limit hypercapnia is now proposed in patients with acute lung injury (ALI). The aim of this study was to test whether a high respiratory rate induces significant intrinsic positive end-expiratory pressure (PEEPi) in these patients. DESIGN: Prospective crossover study. SETTING: A medical intensive care unit. INTERVENTIONS AND MEASUREMENTS: Ten consecutive patients fulfilling criteria for severe ALI were ventilated with a 6 ml/kg Vt, a total PEEP level at 13+/-3 cmH(2)O and a plateau pressure kept at 23+/-4 cmH(2)O. The respiratory rate was randomly set below 20 breaths/min (17+/-3 breaths/min) and increased to 30 breaths/min (30+/-3 breaths/min) to compensate for hypercapnia. External PEEP was adjusted to keep the total PEEP and the plateau pressure constant. PEEPi was computed as the difference between total PEEP and external PEEP. The lung volume retained by PEEPi was then measured. RESULTS: Increase in respiratory rate resulted in significantly higher PEEPi (1.3+/-0.4 versus 3.9+/-1.1 cmH(2)O, p<0.01) and trapped volume (70+/-43 versus 244+/-127 ml, p<0.01). External PEEP needed to be reduced from 11.9+/-3.4 to 9.7+/-2.9 cmH(2)O ( p<0.01). PaO(2) was not affected but the alveolar-arterial oxygen tension difference slightly worsened with the high respiratory rate (p<0.05). CONCLUSIONS: An increase in respiratory rate used to avoid Vt reduction-induced hypercapnia may induce substantial gas trapping and PEEPi in patients with ALI.     

Aspiration of dead space allows isocapnic low tidal volume ventilation in acute lung injury. Relationships to gas exchange and mechanics

OBJECTIVE: In acute lung injury (ALI) mechanical ventilation damages lungs. We hypothesised that aspiration and replacement of dead space during expiration (ASPIDS) allows normocapnic ventilation at higher end-expiratory pressure (PEEP) and reduced tidal volume (V(T)), peak and plateau pressures (Paw(peak), Paw(plat)), thus avoiding lung damage. SETTING: University Hospital. PATIENTS: Seven consecutive sedated and paralysed ALI patients were studied. Interventions and measurements: Single breath test for CO(2) and multiple elastic pressure volume (Pel/V) curves recorded from different end-expiratory pressures guided ventilatory setting at ASPIDS. ASPIDS was studied at respiratory rate (RR) of 14 min(-1) and then 20 min(-1) with minute ventilation maintaining stable CO(2) elimination. RESULTS: Alveolar and airway dead spaces were 24.3% and 31.3% of V(T), respectively. Multiple Pel/V curves showed a shift towards lower volume at decreasing PEEP, thus indicating that patients required a higher PEEP. At ASPIDS, PEEP was increased from 8.9 cmH(2)O to 12.6 cmH(2)O and VT reduced from 11 ml/kg to 8.9 ml/kg at RR 14 min(-1) and to 6.9 ml/kg at RR 20 min(-1). A significant decrease in Paw(peak) (36.7 vs 32 at RR 14 min(-1) and 28.7 at RR 20 min(-1)) and Paw(plat) (29.9 vs 27.3 at RR 14 min-1 and 24.1 at RR 20 min-1) were observed. PaCO(2) remained stable. No intrinsic PEEP developed. No side effects were noticed. CONCLUSIONS: ASPIDS allowed the use of higher PEEP at lower V(T) and inflation pressure and constant PaCO(2). Multiple Pel/V curves gave insight into the tendency of lungs to collapse.     

探讨不同体位喉罩充气容积与气囊内压的变化

目的探讨仰卧位与俯卧位喉罩套囊不同充气容积时气囊内压的变化。方法择期行腰椎手术的患者40例(男24例,女16例),年龄22⁶7岁,体重5067岁,体重50⁷0 kg,BMI<30 kg/m2,ASA分级Ⅰ70 kg,BMI<30 kg/m2,ASA分级Ⅰ^Ⅱ级。麻醉诱导后置入4号Supreme喉罩,分别测量仰卧位(A组)与俯卧位(B组)套囊充气容量范围为5Ⅱ级。麻醉诱导后置入4号Supreme喉罩,分别测量仰卧位(A组)与俯卧位(B组)套囊充气容量范围为5³0 ml(每5 ml递增)时套囊内压及气道峰压并记录相对应的实际潮气量。记录喉罩拔出过程中恶心呕吐、呛咳、误吸、低氧血症和喉罩四周血迹程度的情况;术后24 h内患者咽喉疼痛、声音嘶哑、吞咽困难等发生情况。结果充入相同容量的气体时,A组的气道峰压和气囊内压要明显低于B组(P<0.05)。仰卧位套囊充气容量为1530 ml(每5 ml递增)时套囊内压及气道峰压并记录相对应的实际潮气量。记录喉罩拔出过程中恶心呕吐、呛咳、误吸、低氧血症和喉罩四周血迹程度的情况;术后24 h内患者咽喉疼痛、声音嘶哑、吞咽困难等发生情况。结果充入相同容量的气体时,A组的气道峰压和气囊内压要明显低于B组(P<0.05)。仰卧位套囊充气容量为15²5 ml时,气囊内压为(23.5±3.1)25 ml时,气囊内压为(23.5±3.1)^(46.3±4.5)cmH2O,有92.5%(46.3±4.5)cmH2O,有92.5%¹00%的患者实际潮气量达到90%设定潮气量;充气容量为30 ml时,气囊内压为(64.5±5.5)cmH2O,大于推荐的60 cmH2O气囊内压。俯卧位套囊充气容量为15100%的患者实际潮气量达到90%设定潮气量;充气容量为30 ml时,气囊内压为(64.5±5.5)cmH2O,大于推荐的60 cmH2O气囊内压。俯卧位套囊充气容量为15²0 ml时,气囊内压为(31.8±3.7)20 ml时,气囊内压为(31.8±3.7)^(50.2±3.0)cmH2O,有95%(50.2±3.0)cmH2O,有95%¹00%的患者实际潮气量达到90%设定潮气量;充气容量为25 ml时,气囊内压为(67.0±6.6)cmH2O,大于推荐的60 cmH2O。喉罩拔出过程中所有患者均未发生恶心呕吐、呛咳、误吸,有1例拔出喉罩后有低氧血症,有2例拔出喉罩后,喉罩带血;术后24 h所有患者均未有声音嘶哑及吞咽困难,有1例术后有咽喉疼痛。结论俯卧位喉罩所需的充气容量明显减少,且在相同充气容积时俯卧位的囊内压明显高于仰卧位,在临床工作中需根据实际体位选择最合适的充气容量。     

Effects of nasal continuous positive airway pressure (NCPAP) on breathing pattern in spontaneously breathing premature newborn infants

OBJECTIVE: The aim of the study was to assess the influence of nasal continuous positive airway pressure (NCPAP) on breathing pattern in preterm newborns. DESIGN: Prospective study. SETTING: Neonatal intensive care unit. PATIENTS: Ten premature newborn infants on NCPAP (gestational age range from 27 to 32 weeks, mean birth weight 1300+/-460 g) admitted in our neonatal intensive care unit (NICU) for respiratory distress syndrome. METHODS: Breathing patterns and changes in lung volumes level were obtained using respiratory inductive plethysmography (RIP), at random CPAP levels (0, 2, 4, 6 and 8 cmH2O). Raw data were analysed for end-expiratory lung volume level (EELV-level), tidal volume (Vt), respiratory rate, phase angle and labour breathing index (LBI). RESULTS: CPAP increased EELV-level by 2.1+/-0.3xVt from 0 to 8 cmH2O ( p<0.01). Vt increased by 43% from CPAP of 0 cmH2O to CPAP of 8 cmH2O ( p<0.01). We also found that CPAP lowered the phase angle (from 76+/-21 degrees at CPAP of 0 cmH2O to 30+/-15 degrees at CPAP of 8 cmH2O; p<0.01 ) and LBI (from 1.7+/-0.8 at CPAP of 0 cmH2O to 1.2+/-0.3 at CPAP of 8 cmH2O; p<0.05). CONCLUSION: NCPAP improves the breathing strategy of premature infants with respiratory failure, as reflected by improved thoraco-abdominal synchrony, increased Vt and reduction of the LBI. This effect is associated with an increase in EELV-level with CPAP level. However, further investigations are necessary to establish the best CPAP level that ensures both safety and efficiency.     

Experimental results of using the "open lung concept"

Several elements of the "open lung concept", like ventilation with small tidal volumes, were incorporated into various ventilatory strategies. Our study demonstrates how the whole concept can be applied in an animal model using a standardized protocol with the following possible results. Eighteen pigs weighing between 30 and 45 kg were anaesthetized, tracheotomized and ventilated. Acute lung injury was induced by surfactant washout. Blood gases were monitored via a continuous arterial sensor system (Trendcare system). After washout, the ventilatory pattern of the American "ARDS Network study" was applied (PEEP = 9 cmH2O, volume controlled mode with a tidal volume of 6 ml/kg body weight and a respiratory rate of 25 breaths per minute). Afterwards, the opening pressure and the pressure at which the lung collapses were titrated. Both levels were used as the basis for adjusting the recruitment pressure and PEEP, which was necessary to keep the lung open. The respiratory rate was chosen in such a way that at a low intrapulmonary pressure difference between inspiration and expiration as well as normocapnia was reached. After induction of an acute lung injury by surfactant washout, the oxygenation index (OI) dropped from 556 +/- 54 to 176 +/- 89 mmHg. In the "ARDS Network" mode, OI increased to 285 +/- 49 mmHg. After alveolar recruitment with a peak pressure of 53 +/- 7 cmH2O and application of a median PEEP of 17 +/- 3 cmH2O, oxygenation returned close to baseline. A pCO2 of 33 +/- 4 mmHg resulted after using a respiratory rate of 39 breaths per minute. The median tidal volume was 8 ml/kg body weight. Despite a short arterial systolic blood pressure drop of 23 +/- 11 mmHg during recruitment, no significant difference was detectable afterwards compared to the baseline. Using low tidal volumes alone, complete reopening was not achieved in an experimentally induced acute lung injury. After recruitment manoeuvres, it was possible to reopen the lung and keep it open by application of a sufficient PEEP.