Effect of oral high frequency ventilation by jet or oscillator on minute ventilation in normal subjects.

Normal subjects were asked to breathe through an open ended tube while high frequency oscillations were superimposed on tidal breathing via a side arm, either an eight inch (20 cm) loudspeaker or a jet ventilator being used. Both systems were comfortable and well tolerated. Spontaneous minute ventilation fell by 19-46% at frequencies up to 33 Hz without a rise in transcutaneous PCO2. Maximum ventilatory savings occurred at 1.6 Hz with the jet ventilator (p less than 0.01) and at a frequency corresponding to respiratory system resonance with the loudspeaker. This suggests that during oral high frequency ventilation pulmonary gas exchange is improved and leads to more efficient carbon dioxide excretion for a given minute ventilation. This technique provides a practical and simple method of supplementing breathing in conscious subjects, and it may also have application in the management of patients with acute or chronic respiratory failure, where intubation and conventional ventilation might be avoided.     

高频喷射通气对吸入性损伤犬呼吸气流与气体交换的影响

目的观察犬吸入性损伤时呼吸气流对气体交换的影响。方法用三维粒子动态分析仪测定犬自主呼吸时吸气和呼气流速。将实验动物通入高压蒸气５秒后随机进行五种不同条件高频喷射通气，每种通气方式通气２０分钟，并根据公式Ｒｅ＝Ｖｒρ／η计算出雷诺数，同时采取动脉血标本，观察Ｐａ－ＣＯ２、ＰａＯ２、ＰＩＰ的变化。结果①自主呼吸时吸气为层流，呼气可能为层流，也可能为涡流；②高频喷射通气（ＨＦＪＶ）时呼气和吸气均为涡流；③高频双向喷射通气（ＨＦＴＪＶ）与ＨＦＪＶ相比，呼气流速显著增加（Ｐ＜０．０５），ＰａＣＯ２显著降低（Ｐ＜０．０５），呼气流速与ＰａＣＯ２呈负相关（ｒ＝－０．９２１６，Ｐ＜０．０５），同时吸气流速也有增加的趋势。结论ＨＦＪＶ可维持吸入性损伤犬正常通气，其机制可能与涡流有关。ＨＦＴＪＶ是在ＨＦＪＶ基础上增加了反向喷射气流，可以增进呼吸气体速度，促进ＣＯ２排除。     

高频喷射通气对吸入性损伤犬呼吸气流与气体交换的影响

目的观察犬吸入性损伤时呼吸气流对气体交换的影响。方法用三维粒子动态分析仪测定犬自主呼吸时吸气和呼气流速。将实验动物通入高压蒸气5秒后随机进行五种不同条件高频喷射通气,每种通气方式通气20分钟,并根据公式Re=Vrρ/η计算出雷诺数,同时采取动脉血标本,观察Pa-CO_2、PaO_2PIP的变化。结果①自主呼吸时吸气为层流,呼气可能为层流,也可能为涡流;②高频喷射通气(HFJV)时呼气和吸气均为涡流;③高频双向喷射通气(HFTJV)与HFJV相比,呼气流速显著增加(P<0.05),PaCO_2显著降低(P<0.05),呼气流速与PaCO_2呈负相关(r=-0.9216,P<0.05),同时吸气流速也有增加的趋势。结论 HFJV可维持吸入性损伤犬正常通气,其机制可能与涡流有关。HFTJV是在HFJV基础上增加了反向喷射气流,可以增进呼吸气体速度,促进CO_2排除。     

高频喷射通气对吸入性损伤犬呼吸气流与气体交换的影响

目的 观察犬吸入性损伤时呼吸气流对气体交换的影响。方法 用三维粒子动态分析仪测定犬自主呼吸时吸气和呼气流速。将实验动物通入高压蒸气５秒后随机进行五种不同条件高频喷射通气，每种通气方式通气２０分钟，并根据公式Ｒｅ＝Ｖｒｐ／η计算出雷诺数，同时采取动脉血标本，观察Ｐ２－ＣＯ２、ＰａＯ２、ＰＩＰ的变化。结果（１）自主呼吸时吸气为层流，呼气可有为层流，也可能为涡流；（２）高频喷射通气（ＨＦＪＶ）时呼气和吸     

Effects of negative extra-thoracic pressure ventilation on respiratory system and hemodynamics in normal dogs

The effects of negative extra-thoracic pressure ventilation (NETPV) on respiratory system and hemodynamics were examined in ten normal dogs. Changes of the parameters obtained during intermittent NETPV (INETPV), and NETPV with negative end-expiratory pressure (CNETPV) were compared with those during IPPV and CPPV. Animals' chests and upper abdomens were confined in an acryl box. In INETPV and CNETPV, the dogs were ventilated with the negative extra-thoracic pressure ventilator (Kimura, OKT-100). Positive and negative pressure ventilation was carefully matched for tidal volume and the increase in FRC obtained with PEEP and the end-expiratory negative extra-thoracic pressure (EENETP). EENETP of -11.6 cmH2O produced the same FRC change as PEEP of 10.6 cmH2O did. Gas exchanges did not differ in any modes. INETPV did not change any hemodynamic parameters without PAP. In CNETPV, heart rate increased, and CVP, cardiac index (CI) and stroke volume (SV) decreased significantly (P less than 0.05), but tmCVP and tmPCWP did not change. The decreases of CI and SV (100----89.1, 88.8%) in CNETPV were significantly smaller when compared with CPPV (100----78.8, 74.5%). In CPPV, meanBP, CVP, tmCVP, tmPCWP, CI, SV changed significantly. The mechanisms of the decrease of CI and SV by CNETPV seemed to be different from those by CPPV.     

Effects of continuous negative extrathoracic pressure ventilation (CNETPV) on gas exchange and hemodynamics in dogs with oleic-acid-induced pulmonary edema

To investigate usefulness of continuous negative extrathoracic pressure ventilation (CNETPV) as a method of respiratory care for pulmonary edema, we compared effects of CNETPV on gas exchange and hemodynamics with those of CPPV in dogs with oleic-acid-induced pulmonary edema. End-expiratory negative extrathoracic pressure was adjusted to obtain the same increase in functional residual capacity as that obtained with PEEP of 10 cmH2O. Transmural pressure was calculated by subtracting intrapleural pressure from intravascular pressure. Both CNETPV and CPPV improved gas exchange, and changes in PaO2 and venous admixture were similar with two ventilatory modes. During CNETPV, PvO2 and oxygen delivery were significantly greater than those in CPPV. CPPV did not alter transmural filling pressures but decreased cardiac output, whereas CNETPV increased transmural filling pressure and preserved cardiac output. These results indicate that CNETPV can offer comparable improvement in gas exchange with CPPV, when two ventilatory modes are matched for lung volume. In addition, these results suggest that CNETPV may be superior to CPPV because of less depression of cardiac output and greater oxygen delivery to organs.     

Effects of positive end-expiratory pressure on gas exchange in dogs with normal and edematous lungs.

The effects of positive end-expiratory pressure (PEEP) at 5, 10, 15, and 20 cm H2O on the distribution of ventilation-perfusion (VA/Q) ratios was determined in four normal dogs and in ten with oleic acid-induced acute hemorrhagic pulmonary edema. Tidal volume and frequency were held constant at all times with mechanical ventilation during intravenous pentobarbital and gallamine anesthesia. Normal dogs had little or no shunt, and no areas of low (less than 0.1) or high VA/Q (greater than 10.0) at zero end-expiratory pressure (intermittent positive-pressure breathing). In these animals increasing PEEP caused progressive depression of cardiac output, associated with an increase in ventilation to both high VA/Q and unperfused regions. PEEP greater than or equal to 10 cm H2O resulted in a reduction in Pao2 and an increase in PaCO2. In dogs with pulmonary edema, PEEP's of 5 and 10 cm H2O resulted in dramatic reductions in shunt, virtual obliteration of low VA/Q regions, and market improvement in Pao2. However, at 15 and 20 cm H2O PEEP's high VA/Q and dead space ventilation with CO2 retention again developed in all but the most severely affected (shunt greater than 40%) dogs.     

连续气流通气期间气道内压及流量对犬气体交换的影响

目的　观察不同气道压及气流量对连续气流通气 ( CFV)犬气体交换的影响。方法　选用健康杂种犬 9只 ,在全麻肌松下 ,以较低气道正压 ( Paw为 3 cm H2 O)三种不同气流量 ( 0 .6L· kg- 1· min- 1 ,0 .8L· kg- 1· m in- 1 ,1.0 L· kg- 1· min- 1 )进行 CFV,并与间歇正压通气 ( IPPV)及气道压为 0 cm H2 O时不同气流量 CFV相比较。每种通气方式维持 3 0分钟后抽取股动脉血 ,肺动脉血即混合静脉血作血气分析 ,并根据标准分流公式计算肺内分流率。结果　 CFV各组均能维持 Pa CO2 在正常范围。气道压为 3 cm H2 O时 ,各流量组均能维持 Pa CO2 在正常生理范围 ,且 Pa CO2 随气体流量加大而降低 ,Pa CO2 及 Q.s/ Q.t均显著低于气道压为 0 cm H2 O时对应值 ( P<0 .0 5 )。结论　 CFV时 ,维持较低气道正压能维持有效肺气体交换 ,通气流量大小与 Pa CO2 有较密切关系     

Hemodynamic effects of high frequency ventilation superimposed on intermittent positive pressure ventilation in dogs

The hemodynamic effects of high frequency ventilation (HFV) superimposed on intermittent positive pressure ventilation (IPPV) in seven dogs before and after thrombin infusion were investigated. HFV was superimposed on a Servo 900 B ventilator by a Siemens Elema HFV prototype unit. Mean arterial blood pressure, heart rate, central venous pressure, pulmonary artery pressure, cardiac output, right and left ventricular pressures, pleural pressure, arterial blood gases, and right and left ventricular ejection fractions were recorded. Measurements were done during IPPV alone and during HFV superimposed on IPPV. The HFV frequencies were 5, 15, and 20 Hz at a constant minute volume of 5 1. When HFV was started, the IPPV minute volume was reduced to one third of the initial volume. No significant changes in the measured parameters were observed during the different ventilatory modes either before or after thrombin infusion which doubled the pulmonary vascular resistance. It is concluded that high frequency ventilation superimposed on IPPV might be a ventilatory mode that offers cardiovascular stability and reduces the risk of barotrauma.     

Effects of negative extra-thoracic pressure ventilation on extravascular lung water volume and central blood volume in normal dogs

In negative extra-thoracic pressure ventilation (NETPV), lung water volume and central blood volume (CBV) could increase because of increased venous return and intensified negative interstitial pressure. The effects of NETPV on the extravascular lung water and CBV were examined in ten normal dogs by the double-indicator method using Na and cold water. The lung water volume measured by the method (EVTV) was compared with the lung water volume measured by the gravimetric method (EVLW) in 17 dogs. EVTV did not show any significant change in any ventilation modes compared with IPPV. CBV decreased from 21.9 ml.kg-1 to 19.2 ml.kg-1 in CPPV compared with IPPV (P less than 0.05). EVTV correlated well (r = 0.91, P less than 0.001) with EVLW. In normal dogs, NETPV did not change the lung water volume and CBV. NETPV dogs do not seem to have any disadvantage in respect of lung water volume compared with conventional positive pressure ventilations.     

支撑喉镜术中使用常频常压喷射通气的研究

目的：比较常频常压喷射通气和高频喷射通气在支撑喉镜术中的通气效果。方法：选择３２例ＡＳＡⅠ～Ⅱ级声带息肉患者，拟行支撑喉镜术，随机均分为两组，每组１６例：高频组和常频组。结果：采用６０次／分的频率、１６０ｋＰａ压力进行通气，术中ＰａＣＯ２明显升高（Ｐ＜０．０１）并形成高碳酸血症；采用２２次／分的频率、１６０ｋＰａ的压力进行通气，术中ＰａＣＯ２仅有升高趋势但无显著性差异（Ｐ＞０．０５），且其水平明显低于高频组（Ｐ＜０．０１））。两组患者术中的ＰａＯ２均明显升高且两组间无差异（Ｐ＞０．０５）。结论：无论是常频还是高频喷射通气都能满足机体对供氧的需要，而常频通气比高频通气更有利于二氧化碳排出，由此认为支撑喉镜术中宜采用常频常压喷射通气。     

Comparison of the haemodynamic effects of intermittent positive pressure ventilation with high frequency jet ventilation

The cardiorespiratory effects of intermittent positive pressure ventilation and high frequency jet ventilation with and without positive end expiratory pressure were compared in patients following valvular heart surgery (mitral and/or aortic). Twenty patients received intermittent positive pressure ventilation and high frequency jet ventilation with 0, 0.5 and 1.0 kPa positive end expiratory pressure. High frequency jet ventilation was well tolerated. The addition of 1.0 kPa positive end expiratory pressure was associated with preservation of the arterial oxygen tension without any increase in shunt or significant adverse haemodynamic effect. The results are discussed and compared with a previous study of high frequency jet ventilation following aortocoronary bypass graft surgery.     

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.     

叠加高频喷射通气与间歇性正压通气在鼻内窥镜鼻窦手术中的应用

目的 比较叠加高频喷射通气（SHFJV）与间歇性正压通气（IPPV）对功能性内窥镜鼻窦手术（FESS）患者外科术野质量的影响。
方法 选择行FESS的患者80例,男49例,女31例,年龄18～64岁,BMI 19～30 kg/m²,ASA Ⅰ—Ⅲ级。采用随机数字表法将患者分为两组：SHFJV组（SH组）和IPPV组（IP组）,每组40例。记录术中晶体液、胶体液、红细胞（RBC）、新鲜冰冻血浆（FFP）、出血量、尿量、血管活性药 （硝酸甘油、去甲肾上腺素）用量和手术时间。手术期间每15分钟记录HR、MAP、 心脏指数（CI）、心率血压乘积（RPP）和外科术野质量评分,记算平均值。记录插管即刻、鼻内窥镜置入后1、2 h、术毕时pH、PaO₂、PaCO₂、SpO₂、乳酸（Lac）、碱剩余（BE）、Hb。记录术后3 d内寒战、低血压、恶心呕吐、发热、 睡眠障碍、手术部位感染和肺部感染发生情况。
结果 与IP组比较,SH组晶体液、胶体液、RBC输注量、出血量、RPP明显减少（P<0.01）,外科术野质量评分明显降低（P<0.01）,置入后1、2 h pH明显降低,PaCO₂、BE和Hb明显升高（P<0.05）,术毕时PaCO₂、BE和Hb明显升高（P<0.05）,术后3 d内低血压、恶心呕吐发生率明显降低（P<0.05）。两组寒战、发热、睡眠障碍和肺部感染发生率差异无统计学意义。两组无一例手术部位感染。
结论 与间歇性正压通气比较,叠加高频喷射通气可减少功能性内窥镜鼻窦手术患者术中出血量,提高外科术野质量,减少术后低血压、恶心呕吐等并发症,可安全有效地用于临床。     

High-frequency ventilation. I. Distribution of alveolar pressure amplitudes during high frequency oscillation in the lung model

The pattern of intrapulmonary pressure distribution was studied during high-frequency ventilation in order to explain the inconsistent results reported in the literature. Methods. Pressure and flow velocity (hot-wire anemometry) were measured in different lung compartments: 1. In transalveolar chambers sealed to the perforated pleural surfaces of dried pig lungs; 2. In emphysema-simulating airbags sealed to the isolated bronchial trees of dried pig lungs; and 3. In transalveolar chambers sealed to the perforated pleural surfaces of freshly excised pig lungs. Results. 1. The pressure amplitudes change from one area to another and depending on the exciting frequency. 2. High-frequency oscillation is associated with an increase in pressure amplitude when the exciting frequency rises, whereas with conventional high-frequency jet ventilation the pressure amplitude is more likely to decrease with frequency. 3. During high-frequency jet ventilation the local pressure amplitude changes with the position of the tube in the trachea rather than with the exciting frequency. 4. When the volume of the measuring chamber is doubled the resulting pressure amplitude falls to half the control value. 5. The pressure amplitude and mean pressure measured in the transalveolar chamber vary more or less independently from the peak flow velocity. High-frequency ventilation is thus seen to be a frequency-dependant, inhomogeneous mode of ventilation that can essentially be homogenized by systematically changing the exciting frequency. The frequency-dependant response to different lung areas to excitation is likely to result from an intrabronchially-localized aerodynamic effect rather than the mechanical properties of the lung parenchyma.