高频振荡通气在新生儿呼吸窘迫综合征中的临床应用

目的：探讨高频振荡通气（HFOV）作为新生儿呼吸窘迫综合征（RDS）初始治疗的疗效及安全性。方法回顾性分析2010年1月至2013年6月住院治疗、需机械通气的RDS患儿50例,2011年11月前以常频机械通气的25例患儿作为CMV组,2011年11月后以高频振荡通气的25例患者患者作为HFOV组。结果机械通气1h后,两组患儿吸入氧浓度（FiO2）、平均气道压（MAP）、动脉血二氧化碳分压（PCO2）动脉血氧分压（PO2）均较0h有不同程度改善,且在1h及6hHFOV组较CMV组改善更明显,差异有统计学意义（P〈0.05）;机械通气24h后HFOV组的PO2、MAP与CMV组比较,差异无统计学意义（P〉0.05）,PCO2差异有统计学意义（P〈0.05）。HFOV组患儿用氧时间与CMV组比较差异有统计学意义（P〉0.05）。两组气漏、颅内出血、心力衰竭、DIC发生率差异无统计学意义（P〉0.05）。两组患者休克发生率差异有统计学意义（P〈0.05）。HFOV发生休克症状的病人增多,但积极处理后可以缓解。结论 HFOV能更好更快的改善RDS患儿的氧合功能,缩短用氧时间,但24h后的疗效与CMV组比较无差别,未缩短使用呼吸机的时间。未明显增加并发症的发生,休克积极处理后可以纠正。HFOV可以作为治疗新生儿呼吸窘迫综合征的又一选择。     

High-frequency oscillatory ventilation in experimental lung injury: effects on gas exchange

OBJECTIVE: To compare ventilation-perfusion (V(A)/Q) distributions during improvement of oxygenation caused by high-frequency oscillatory ventilation (HFOV) and pressure-controlled mechanical ventilation with high PEEP levels (CMV) in experimental acute lung injury (ALI). DESIGN: Prospective, controlled animal study.SETTING: Animal research facility of a university hospital. INTERVENTIONS: Twelve pigs with oleic acid-induced ALI were randomised to HFOV ( n=6) or to CMV ( n=6) with a PEEP of 15 mbar for 1 h. The mean airway pressure was adjusted in both groups to achieve comparable improvements in arterial oxygen partial pressure (PaO(2)) and to avoid clinically relevant impairments of cardiac output, as assured by adequate mixed venous oxygen saturation and lactate levels. V(A)/Q distributions were determined by the multiple inert gas elimination technique (MIGET). MEASUREMENTS AND RESULTS: Arterial oxygen partial pressure improved during CMV with a mean airway pressure of 20 mbar ( p<0.05) whereas HFOV revealed comparable improvements with a mean airway pressure of 40 mbar ( p<0.05). Shunt decreased and blood flow to normal V(A)/Q areas increased due to CMV and HFOV ( p<0.05). The perfusion of low V(A)/Q areas remained unchanged. Statistical analysis did not reveal differences of PaO(2), shunt or blood flow to low V(A)/Q areas between the groups. CONCLUSIONS: In this model of acute lung injury CMV and HFOV improved gas exchange due to similar changes in V(A)/Q distribution. However, mean airway pressure had to be adjusted twofold higher during HFOV then during CMV to achieve comparable improvements in gas exchange.     

高频震荡通气联合肺表面活性物质治疗新生儿呼吸窘迫综合征临床观察

目的：探讨高频震荡通气（HFOV）联合肺表明活性物质（PS）治疗新生儿呼吸窘迫综合征（NRDS）的疗效。方法：对25例NRDS患儿采用常规通气（CMV）联合PS治疗（CMV组）,20例采用HFOV联合PS治疗（HFOV组）。结果：两组患儿在上机前,反映氧合功能的FiO2、OI、PaA三个参数统计学差异。HFOV组患儿经治疗2 h后FiO2和OI显著下降,Pa/A升高,CMV组患儿呈现相似的改变,但不如HFOV组显著,随着时间推移,两组之间差异更明显。HFOV组上机时间（74±10）h,CMV组上机（85±9）h,两组时间比较,有统计学意义（P〈0.05）。HFOV组存活率85.7%,CMV组存活率84%,有统计学意义（P〈0.05）。结论：高频震荡通气联合肺表明活性物质治疗新生儿呼吸窘迫综合征可改善氧合,减少上机时间,提高存活率。     

常频叠加高频振荡通气对肺损伤大鼠氧合及通气的影响

目的观察常频叠加高频振荡通气对急性肺损伤大鼠氧合和通气的影响。方法以15只Wistar大鼠为实验对象,给予机械通气,用生理盐水肺灌洗制作急性肺损伤大鼠模型,先后行常频机械通气(CMV参数:FiO2 100%、f 30 bpm、PEEP 6 cmH2O、I∶E 1∶2、MAP 12 cmH2O)、高频振荡通气(HFOV参数:FiO2 100%、f 11 Hz、Paw 12 cmH2O、Ti 33%)、常频叠加高频振荡通气(CMV+HFOV参数同前)各1 h,监测动脉血气。计算PaO2/FiO2、氧合指数(OI)、肺内血分流率(Qs/Qt)。结果损伤前、CMV、HFOV、CMV+HFOV各指标变化:(1)PaCO2分别为(41.04±3.94)mmHg、(100.5±28.73)mmHg、(82.06±22.87)mmHg及(54.01±19.32)mmHg,损伤后均显著高于损伤前(P<0.01);CMV+HFOV显著低于CMV、HFOV(P<0.01);CMV、HFOV两者差异无统计学意义(P>0.05)。(2)PaO2/FiO2分别为(467.9±47.71)mmHg、(105.3±25.39)mmHg、(131.2±67.72)mmHg、(216.3±76.84)mmHg,损伤后均显著低于损伤前(P<0.01);CMV+HFOV显著高于CMV、HFOV(P<0.01);CMV、HFOV两者差异无统计学意义(P>0.05)。(3)OI分别为1.88±0.30、8.84±2.15、6.16±3.19、4.60±1.71,损伤后均显著高于损伤前(P<0.01);CMV+HFOV、HFOV显著低于CMV(P<0.01);CMV+HFOV、HFOV两者差异无统计学意义(P>0.05)。(4)Qs/Qt分别为0.11±0.02、0.29±0.02、0.26±0.05及0.24±0.04,损伤后显著高于损伤前(P<0.01);各通气模式差异无统计学意义(P>0.05)。结论常频叠加高频振荡通气在促进肺损伤大鼠CO2排出及改善氧合方面优于单纯常频通气和单纯高频通气。     

Postnatal changes of extracellular volume, atrial natriuretic factor, and diuresis in a randomized controlled trial of high-frequency oscillatory ventilation versus intermittent positive-pressure ventilation in premature infants <30 weeks gestation

OBJECTIVES: High-frequency oscillatory ventilation (HFOV) with a high lung volume strategy is an experimental mode of ventilating preterm infants aimed at achieving maximal alveolar recruitment Higher mean airway pressures are used during HFOV than during intermittent positive-pressure ventilation (IPPV), and the intrathoracic volume increase is relatively constant. Both factors increase the risk to depress organ blood flow and diuresis. Our objective was to test the hypothesis that high lung volume HFOV attenuates the postnatal reduction of extracellular volume in preterm infants by reducing plasma atrial natriuretic factor and diuresis. DESIGN: Prospective, randomized, controlled clinical trial. SETTING: University hospital, Level III neonatal intensive care unit. PATIENTS: Premature infants <30 wks gestation requiring intubation for respiratory distress syndrome within the first 6 hrs of life; 15 infants (gestational age, 26 [24-29] wks, birth weight 814 [452-1340] g) were randomized to HFOV, 19 infants (gestational age 27 [24-39] wks, birth weight 930 [644-1490] g) to IPPV. INTERVENTIONS: The randomized mode of ventilation was assigned within 1 hr after intubation. During HFOV mean airway pressure was increased as long as oxygenation improved and no lung overinflation was seen on chest radiograph. IPPV rates were > or =60/min. MEASUREMENTS AND MAIN RESULTS: We measured extracellular volume (sucrose dilution) and atrial natriuretic factor on Day 1 and Day 3. Mean airway pressure, body weight, diuresis, and fluid intake were measured daily. During HFOV mean airway pressure was higher at 12 hrs (median 7 cm H2O vs. 4 cm H2O; p = .001) and 24 hrs (median 6 cm H2O vs. 3 cm H2O; p = .01). In both groups, extracellular volume decreased between Day 1 and Day 3 (HFOV from 428 +/- 126 mL to 344 +/- 145 mL [p = .003], IPPV from 466 +/- 108 mL to 414 +/- 124 mL [p = .01]) and diuresis increased (HFOV, from 2.5 +/- 1.7 to 4.6 +/- 0.9 mL/kg/hr [p = .001]; IPPV, from 2.8 +/- 1.6 to 4.2 +/- 1.0 mL/kg/hr [p = .01]). Plasma atrial natriuretic factor was not decreased in the HFOV group. CONCLUSIONS: High lung volume HFOV as primary mode of ventilation in preterm infants <30 wks gestation did not result in unwanted fluid retention and a decrease in diuresis in the first days of life.     

高频振荡通气在新生儿呼吸窘迫综合征治疗中的应用

目的 探讨高频振荡通气(HFOV)治疗新生儿呼吸窘迫综合征(NRDS)的疗效及安全性.方法 对NRDS 64例,随机分为常频机械通气(CMV)30例和高频振荡通气(HFOV)34例,比较两组患儿治疗前后的血气分析、吸入氧浓度(FiO2)、氧合指数(OI)及并发症等.结果 HFOV组患儿吸入氧分数明显低于CMV组,PaCO2及氧合指数迅速下降,pH及PaO2明显上升,HFOV组发生肺气漏及慢性肺部疾病(CLD)等并发症低于CMV组(P<0.05).结论 HFOV用于治疗新生儿呼吸窘迫综合征,是一种疗效肯定、安全性好的新型机械通气方法.     

Effects of high-frequency oscillatory ventilation on circulation in neonates with pulmonary interstitial emphysema or RDS

Objective: Mechanical ventilation may impair cardiovascular function if the transpulmonary pressure rises. Studies on the effects of high-frequency oscillatory ventilation (HFOV) on cardiovascular functions have yielded conflicting results. This study was done to compare alterations in left ventricular output and blood flow velocities in the anterior cerebral artery, internal carotid artery, and celiac artery using a Doppler ultrasound divice before and 2 h after initiating HFOV in neonates with respiratory distress syndrome (RDS) or pulmonary interstitial emphysema (PIE). Design: Prospective clinical study. Setting: Neonatal intensive care unit in a perinatal center. Patients: 18 critically ill infants (postnatal age 47 ± 12 h; mean ± SD) were studied before and during HFOV (piston oscillator). Indications for HFOV were severe respiratory failure due to PIE (n = 10) and severe surfactant deficiency (RDS, n = 8). In the RDS group, gestational age was 27 ± 6 weeks (range 26–31 weeks) and birthweight 1620 ± 380 g (range 850–1970 g). In the PIE group, gestational age was 28 ± 2 weeks (range 26–36 weeks) and birthweight 1740 ± 470 g (range 890–2760 g). Measurements and main results: During HFOV, mean airway pressure was maintained at the same level as during intermittent mandatory ventilation in both groups (RDS, 12 ± 2 cmH₂O; PIE, 10 ± 2 cmH₂O). Compared to intermittent mandatory ventilation, several of the 12 parameters studied changed significantly (p < 0.004) during HFOV. In the RDS group, the partial pressure of oxygen in arterial blood/fractional inspired oxygen (PaO₂/FIO₂) ratio increased from 56 ± 9 to 86 ± 7 and partial pressure of carbon dioxide in arterial blood (PaCO₂) decreased from 49 ± 4 to 35 ± 3 mmHg. In the PIE group, PaO₂/FIO₂ ratio increased from 63 ± 8 to 72 ± 7 and PaCO₂ decreased from 63 ± 7 to 40 ± 5 mmHg. In the PIE group, heart rate decreased (135 ± 15 before HFOV vs 115 ± 14 min^{− 1} during HFOV) and mean systolic blood pressure increased (before 43 ± 4 vs 51 ± 4 mmHg during HFOV) significantly, whereas these parameters did not change in the RDS group. Left ventricular output increased significantly in the PIE group (210 ± 34 before vs 245 ± 36 ml/kg per min during HFOV; p < 0.004), but not in the RDS group (225 ± 46 before vs 248 ± 47 ml/kg per min during HFOV; k < 0.05). Shortening fraction and systemic resistance did not change in either group. In the PIE group, mean blood flow velocities in the internal carotid artery (+ 59 %), anterior cerebral artery (+ 65 %) and celiac artery (+ 45 %) increased significantly but did not change in the RDS group. Conclusions: The results show that HFOV as used in this study, improves oxygenation, CO₂ elimination, and circulation in infants with RDS and PIE. However, systemic, cerebral, and intestinal circulation improved more in neonates with PIE than in those with RDS. This may be due to higher pulmonary compliance in infants with PIE when compared to those with RDS. Received: 15 May 1996 Accepted: 31 January 1997     

A prospective randomized comparison of conventional mechanical ventilation and very early high frequency oscillatory ventilation in extremely premature newborns with respiratory distress syndrome

Objective: To compare the effectiveness and safety of very early high-frequency oscillatory ventilation (HFOV) with conventional mechanical ventilation (CMV) in treatment of the respiratory distress syndrome (RDS) and to evaluate their impact on the incidence of chronic pulmonary disease and early and late morbidity of very low-birthweight neonates. Design: A prospective randomized clinical trial. Setting: Tertiary neonatal intensive care unit in the Perinatology Center in Prague. Patients: 43 premature newborns, delivered in the Department of Obstetrics in the Perinatology Center, were randomly divided into two groups (HFOV and CMV) immediately after delivery; 2 patients in each group died, 2 fulfilled crossover criteria from CMV to HFOV, and 2 were excluded because of congenital malformations. Nineteen patients treated with HFOV were therefore compared with 18 infants in the CMV group. Methods: The two contrasting modes of ventilation were introduced immediately after intubation. Maintenance of optimal lung volume in HFOV to optimize oxygenation and the therapeutic administration of surfactant after fulfilling defined criteria are important points of the strategy and design of the study. Measurements and main results: Except for a higher proportion of males in the HFOV group (p < 0.02), the basic clinical characteristics (gestational age, birthweight, Apgar score at 5 min, umbilical arterial pH), the two groups were similar. In the acute stage of RDS, infants treated with HFOV had higher proximal airway distending pressure with HFOV for 6 h after delivery (p < 0.05). For a period of 12 h after delivery lower values for the alveolar-arterial oxygen difference (p < 0.03) were noted. The number of patients who did not require surfactant treatment was higher in the HFOV group (11 vs 1, p < 0.001). In the HFOV group the authors found a lower roentgenographic score at 30 days of age (p < 0.03) and a lower clinical score in the 36th postconceptional week (p < 0.05), using these two scoring systems for assessing chronic lung disease according to Toce scale. The incidence of pneumothorax, pulmonary interstitial emphysema, intraventricular hemorrhage and retinopathy of prematurity in both groups was the same. Conclusions: HFOV, when applied early and when the clinical strategy of maintenance of optimal lung volume is used, improves oxygenation in the acute stage of RDS, reduces the need of surfactant administration, and can decrease the injury to lung tissue even in extremely immature newborns to whom surfactant is administered therapeutically. Received: 3 December 1997 Final revision received: 31 August 1998 Accepted: 1 September 1998     

Effects of open endotracheal suction on lung volume in infants receiving HFOV

Objective To describe the pattern and magnitude of lung volume change during open endotracheal tube (ETT) suction in infants receiving high-frequency oscillatory ventilation (HFOV). Design Prospective observational clinical study. Setting Tertiary neonatal intensive care unit. Patients and participants Seven intubated and muscle-relaxed newborn infants receiving HFOV. Interventions Open ETT suction was performed for 6 s at −100 mmHg using a 6-F catheter passed to the ETT tip after disconnection from HFOV. The HFOV was then recommenced at the same settings as prior to ETT suction. Measurements and results Change in lung volume (ΔV _L) referenced to baseline lung volume before suction was measured with a calibrated respiratory inductive plethysmography recording from 30 s before until 60 s after ETT suction. In all infants ETT suction resulted in significant loss of lung volume. The mean ΔV _L during suctioning was −13 ml/kg (SD 4 ml/kg) (p < 0.0001 vs. baseline, repeated-measures ANOVA), with a mean 76.5% (SD 14.1%) of this volume loss being related to circuit disconnection. After recommencing HFOV lung volume was rapidly regained with mean ΔV _L at 60 s being 1 ml/kg (SD 4 ml/kg) below baseline (p > 0.05, Tukey post-test). Conclusions Open ETT suction caused a significant but transient loss of lung volume in muscle-relaxed newborn infants receiving HFOV.     

High-frequency oscillatory ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease

Purpose

High-frequency oscillatory ventilation (HFOV) is usually considered not indicated for treatment of patients with chronic obstructive pulmonary disease (COPD) because of the theoretical risk of air trapping and hyperinflation. The aim of our study was to establish whether HFOV can be safely applied in patients with acute exacerbation of COPD and hypercapnic respiratory failure.

Methods

Ten patients (age, 63-83 years) requiring intensive care treatment who failed on noninvasive ventilation were studied. After initial conventional mechanical ventilation (CMV) of less than 72 hours, all patients were transferred to HFOV for 24 hours and then back to CMV. Arterial blood gases, spirometry, and hemodynamic parameters were repeatedly obtained in all phases of CMV and HFOV at different settings. Regional lung aeration and ventilation were assessed by electrical impedance tomography.

Results

High-frequency oscillatory ventilation was tolerated well; no adverse effects or severe hyperinflation and hemodynamic compromise were observed. Effective CO₂ elimination and oxygenation were achieved. Ventilation was more homogeneously distributed during HFOV than during initial CMV. Higher respiratory system compliance and tidal volume were found during CMV after 24 hours of HFOV.

Conclusions

Our study indicates that short-term HFOV, using lower mean airway pressures than recommended for acute respiratory distress syndrome, appears safe in patients with COPD while securing adequate pulmonary gas exchange.     

An in vitro assessment of gas trapping during high frequency oscillation

Our aim was to assess the influence of oscillatory frequency, inspiratory-to-expiratory (I:E) ratio and airway pressure on gas trapping during high frequency oscillatory ventilation (HFOV). A lung model was used, which had a high compliance (4.0 ml (cmH(2)O)(-1)) and resistance (160 cmH(2)O l(-1) s(-1)) resulting in a long time constant (0.64 s). To assess whether gas trapping occurred, the mean pressure within the lung model (equivalent to alveolar pressure) was compared to the mean airway pressure (MAP) measured at the manifold (manifold MAP) of the two oscillators used, the SLE 5000 (I:E ratio 1:1) and the Sensor Medics 3100A (tested at I:E ratios of 1:2 and 1:1). The effects were assessed of raising the MAP from 15 to 35 cmH(2)O, the oscillatory amplitude from 30 to 70 cmH(2)O and the frequency from 5 to 15 Hz (5 to 20 Hz SLE only). There were no significant trends for differences between the pressure within the lung model and the 'manifold' MAP to increase (i.e. no evidence of gas trapping), as MAP, amplitude or frequency was increased, regardless of which oscillator or I:E ratio was used. Increasing the pressure amplitude led to a progressive fall in the pressure within the lung model when an I:E ratio of 1:2 was used (p < 0.05). Our results suggest that significant gas trapping does not occur during HFOV even if there is high compliance and resistance.     

Pulmonary interstitial emphysema treated by high-frequency oscillatory ventilation

Twenty-seven low birth weight infants who developed pulmonary interstitial emphysema (PIE) and respiratory failure while on conventional ventilation were treated with high-frequency oscillatory ventilation (HFOV). The mean birth weight was 1.2 kg (range 0.55 to 2) with gestational age of 28 wk (range 25 to 34). Ten patients died, six of whom had documented sepsis with shock and were therefore excluded from analysis. All patients showed initial improvement on HFOV. Surviving patients showed continued improvement in oxygenation and ventilation at increasingly lower fraction of inspired oxygen and proximal airway pressure with resolution of PIE, while nonsurvivors progressively developed chronic respiratory insufficiency with continued PIE from which recovery was not possible. Overall survival in nonseptic patients was 80% (16 of 20). We found HFOV to be effective in the treatment of PIE and hypothesize that interstitial airleak is decreased during HFOV because adequate ventilation is provided at lower peak distal airway pressures.     

Setting positive end-expiratory pressure during jet ventilation to replicate the mean airway pressure of oscillatory ventilation

BACKGROUND: High-frequency ventilation can be delivered with either oscillatory ventilation (HFOV) or jet ventilation (HFJV). Traditional clinician biases may limit the range of function of these important ventilation modes. We hypothesized that (1) the jet ventilator can be an accurate monitor of mean airway pressure (P (aw)) during HFOV, and (2) a mathematical relationship can be used to determine the positive end-expiratory pressure (PEEP) setting required for HFJV to reproduce the P (aw) of HFOV. METHODS: In phase 1 of our experiment, we used a differential pressure pneumotachometer and a jet adapter in-line between an oscillator circuit and a pediatric lung model to measure P (aw), PEEP, and peak inspiratory pressure (PIP). Thirty-six HFOV setting combinations were studied, in random order. We analyzed the correlation between the pneumotachometer and HFJV measurements. In phase 2 we used the jet as the monitoring device during each of the same 36 combinations of HFOV settings, and recorded P (aw), PIP, and DeltaP. Then, for each combination of settings, the jet ventilator was placed in-line with a conventional ventilator and was set at the same rate and PIP as was monitored during HFOV. To determine the appropriate PEEP setting, we calculated the P (aw) contributed by the PIP, respiratory rate, and inspiratory time set for HFJV, and subtracted this from the goal P (aw). This value was the PEEP predicted for HFJV to match the HFOV P (aw). RESULTS: The correlation coefficient between the pneumotachometer and HFJV measurements was r = 0.99 (mean difference 0.62 +/- 0.30 cm H(2)O, p < 0.001). The predicted and actual PEEP required were highly correlated (r = 0.99, p < 0.001). The mean difference in these values is not statistically significantly different from zero (mean difference 0.25 +/- 1.02 cm H(2)O, p > 0.15). CONCLUSIONS: HFJV is an accurate monitor during HFOV. These measurements can be used to calculate the predicted PEEP necessary to match P (aw) on the 2 ventilators. Replicating the P (aw) with adequate PEEP on HFJV may help simplify transitioning between ventilators when clinically indicated.     

不同体位对 ARDS 患者机械通气效果的影响

目的：比较不同体位对ARDS患者机械通气效果的影响。方法选择2010年1月-2012年12月行机械通气治疗且无俯卧位机械通气禁忌证的ARDS患者40例,采用随机数字表法随机分为俯卧位通气组和仰卧位通气组,每组各20例。比较两组患者机械通气前后生命体征和动脉血气变化,治疗3d后平均气道压、平台压、气道阻力,机械通气时间和急诊科住院时间。结果组内比较,两组患者治疗后T、P、MAP、PaCO2均降低,差异均有统计学意义（P＜0．01）;PETCO2、pH值、PaO2、PaO2/FiO2均升高,差异均有统计学意义（P＜0．01）。组间比较,T、P、PETCO2、MAP、pH值、PaO2、PaCO2差异均无统计学意义（P＞0．05）;俯卧位通气组患者在俯卧位治疗3 d后PaO2/FiO2为（282±177;22）,高于仰卧位通气组治疗3 d后的（245±177;21）,差异有统计学意义（t＝6．18,P＜0．01）。治疗3 d后,俯卧位通气组患者平均气道压、平台压、气道阻力分别为（6．8±177;0．5）cmH2O,（17．1±177;2．0）cmH2O,（14．9±177;1．2）cmH2O/（L±183; s）,仰卧位通气组分别为（8．5±177;0．9）cmH2O,（20．6±177;2．3）cmH2O,（21．1±177;0．8）cmH2O/（L±183; s）,差异均有统计学意义（t值分别为7．38,5．13,18．83;P＜0．01）。俯卧位通气组患者机械通气时间和急诊科住院时间均短于仰卧位通气组,差异均有统计学意义（ t值分别为9．007,6．379;P＜0．01）。结论俯卧位通气可以更有效地改善氧合指数,纠正低氧血症,同时对患者气道影响较小,是较为理想的通气体位。     

High-frequency ventilation (HFV) in hyaline membrane disease —a preliminary report

Eight premature babies affected by hyaline membrane disease and needing mechanical respiratory support were ventilated by means of a VDR 1 (Bird Space Technology) respirator at 10 Hz during a mean time of 51 h. Before HFV 7 infants had been on conventional mechanical ventilation (CMV) and one on nasal CPAP. The values of mean airway pressure (MAP) and oxygenation index (PaO₂/FIO₂) on CMV and HFV were (mean and range): 1. CMV: MAP 15 (4–29) mm Hg, ox. index 15.47 (5.07–23.19) kPa; 2. HFV after 1 h: MAP 15 (10–19) mm Hg, ox. index 24.13 (9.07–46.12) kPa. Improved oxygenation allowed rapid reduction of FIO₂ in the following hours. Only 3 infants were weaned directly from VDR 1, 5 were switched back to CMV mainly because of technical failures of the respirator. The change from HFV to CMV was associated with a fall of PaO₂/FIO₂ from 35.99 (15.86–74.52) to 22.39 (7.33–31.46) kPa. The mean time of artificial ventilation (CMV+HFV) was 121 h (range 46–166). Except for 1 pneumothorax no medical complications were seen during HFV, and all patients survived. Despite impressive improvements in oxygenation it is cautioned against the use of the VDR 1 because of the high incidence of technical problems.     

高频振荡结合部分液体通气治疗急性呼吸衰竭兔的实验研究

目的探讨高频振荡通气（HFOV）结合高氟碳化合物（PFC）对重度蒸汽吸入性肺损伤导致的急性呼吸衰竭兔的呼吸功能及IL-10、IL-18的影响。方法将24只新西兰大白兔制成重度蒸汽吸入性肺损伤并急性呼吸衰竭模型，随机分为常规机械通气（CMV）组、HFOV组和HFOV＋PFC组，分别在治疗后1、2、3、4h取动脉血行血气分析，治疗4h后抽血处死动物，ELISA法测定血清中IL-10、IL-18水平，右肺中叶取标本，行病理学检查。结果3组兔伤后PaO2均降至60mmHg（1mmHg=0．133kPa）以下，各组伤前、伤后比较均有显著性差异（P〈0.01），组问比较差异无统计学意义（P〉0.05）。3组兔伤后PaCO2均升高，pH值均降低，各组伤前、伤后比较有显著性差异（P〈0.01），组间比较无差异（P〉0.05）。治疗1h时3组的PaO2均有上升，HFOV＋PFC组上升最为明显，HFOV＋PFC组明显高于HFOV组（P〈0.01），HFOV组明显高于CMV组（P〈0.01）。治疗4h后3组PaO2均有所改善，HFOV＋PFC组高于相应时相HFOV组（P〈0.01），HFOV组高于相应时相CMV组（P〈0．01）。治疗4h后3组兔pH值、PaCO2与致伤后比较差异无统计学意义（P〉0.05）；血清中IL-10水平：HFOV＋PFC组高于HFOV组（P〈0.01），HFOV组高于CMV组（P〈0．01）；血清中IL-18水平：HFOV＋PFC组低于HFOV组（P〈0.01），HFOV组低于CMV组（P〈0．01）；肺组织病理学检查发现HFOV组的损伤程度较CMV组减轻，HFOV＋PFC组损伤最轻，CMV组损伤最重。结论HFOV结合PFC可显著改善蒸汽吸人性损伤导致的急性呼吸衰竭兔的PaO2，并能在更短的时间内达到最佳气体交换状态，改善呼吸功能。还可提高血清中IL-10水平，降低血清中IL-18水平，从而减轻肺部炎症反应，减轻肺损伤，是治疗急性呼吸衰竭兔较好的方法。     

Hemodynamic effects of high-frequency oscillatory ventilation in severe pediatric respiratory failure

Objective To assess the hemodynamic effects of high mean proximal airway pressures (Paw) during high-frequency oscillatory ventilation (HFOV) in non-neonatal pediatrics patients with severe respiratory failure.Design Prospective and retrospective study.Setting Pediatric ICU in a university-affiliated hospital.Patients 8 non-neonatal pediatric patients with severe respiratory failure ventilated with HFOV at our institution between July 1991 and February 1994. All patients had a pulmonary artery catheter.Interventions HFOV.Measurements and results Higher Paw was required during HFOV to obtain adequate lung expansion during the first 24 h (median 20.9 cmH₂O, range 16.9–30.0 cmH₂O in CMV, versus median 30.0 cmH₂O, range 21.0–33.0 cmH₂O in HFOV,p=0.008), resulting in improved oxygenation as evaluated by alveolar-arterial oxygen difference (median of 557.2 mmHg, range 360.4–607.8 mmHg in CMV, versus median of 410.5 mmHg, range 282.9–550.2 mmHg after 24 h of HFOV,p=0.03). The only observed effect on the cardiovascular system was a decrease in heart rate (median of 162, range 129–178 in CMV, versus median of 142, range 104–195 after 24 h of HFOV,p=0.03). Oxygen delivery, cardiac index, mean systemic arterial blood pressure, and pulmonary and systemic vascular resistances did not change significantly before and after HFOV in the patients as a group, although in one case a decrease in cardiac index and oxygen delivery was observed.Conclusions High-Paw HFOV must be used cautiously, but seems to have no discernible adverse effects on the cardiovascular system in most patients.     

高频振荡通气联合肺表面活性物质对吸入性损伤肺组织天冬氨酸特异性半胱氨酸蛋白酶-3和p73的影响

目的 探讨高频振荡通气(HFOV)联合肺表面活性物质(PS)对吸人性损伤兔肺组织细胞凋亡的影响.方法 采用兔蒸汽吸人性损伤模型,将32只兔按不同通气治疗方式分为常规控制机械通气(CMV)组、HFOV组、CMV+PS组及HFOV+PS组4组,每组8只.治疗4 h后处死动物,取右肺中叶组织,分别检测天冬氨酸特异性半胱氨酸蛋白酶-3(caspase-3)、p73的含量及其mRNA表达水平.结果 ①HFOV组和HFOV+PS组肺组织caspase-3和p73的含量分别较CMV组和CMV+PS组明显减少,差异有统计学意义(P<0.05或P<0.01);加入外源性PS后,CMV+PS组和HFOV+PS组的caspase-3和p73含量也较相应未加入组明显减少,差异也有统计学意义(P均<0.05).②HFOV组和HFOV+PS组caspase-3 mRNA和p73 mRNA表达分别较CMV组和CMV+PS组明显减少,差异有统计学意义(P均<0.01);加入外源性PS后,CMV+PS组和HFOV+PS组肺组织caspase-3 mRNA和p73 mRNA的表达也明显低于相应未加入组,差异也有统计学意义(P均<0.05).结论 与CMV或CMV+PS比较,HFOV或HFOV+PS能减少吸入性损伤肺组织细胞中caspase-3、p73的含量及其mRNA表达,从而可能减少通气肺的肺细胞凋亡.     

Partial liquid ventilation: effects of positive end-expiratory pressure on perfluorocarbon evaporation from the lungs of anesthetized dogs

OBJECTIVE: Perfluorocarbons are eliminated during partial liquid ventilation mainly by evaporation via the airways. We examined whether this is affected by the level of end-expiratory airway pressure. DESIGN AND SETTING: Observational cohort animal study in the animal laboratory of a university hospital. SUBJECTS: Five foxhound dogs. INTERVENTIONS: The anesthetized dogs underwent partial liquid ventilation (5 ml/kg perfluorocarbon) at constant respiratory rate (17+/-1 breaths/min) and tidal volume (10 ml/kg). The level of end-expiratory airway pressure was varied repeatedly between 0, 5, and 10 cmH(2)O every 25 min. MEASUREMENTS AND RESULTS: Expired gas was collected in reservoirs to determine evaporative perfluorocarbon loss gravimetrically. Any increase in end-expiratory airway pressure increased while any decrease in end-expiratory airway pressure reduced evaporative perfluorocarbon loss. Mean initial elimination at an end-expiratory airway pressure of 5 cmH(2)O was 19.6+/-3.8 microl/kg per minute; this decreased by 28% at an end-expiratory airway pressure of 0 cmH(2)O and increased by 46% at an end-expiratory airway pressure of 10 cmH(2)O. At equal levels of end-expiratory airway pressure evaporation decreased linearly over time. CONCLUSIONS: Our results suggest that the level of end-expiratory airway pressure is a determinant of evaporative perfluorocarbon loss and may have relevance for maintenance dosing and instillation intervals during partial liquid ventilation.     

常规机械通气与高频振荡通气在胎粪吸入综合征中的应用

【目的】评价常规机械通气（CMV）与高频振荡通气（HFOV）治疗新生儿重症胎粪吸入综合征（MAS）的疗效。【方法】对本院2008年9月至2011年6月83例重症MAS新生儿予CMV或HFOV治疗。观察比较CMV与HFOV治疗前后肺功能变化及病情转归。【结果】CMV治疗组与HFOV治疗组动脉氧分压（Pa02）分别由治疗前的（47．95土14．44）mmHg、（62．16±23．03）mmHg上升为（82．84±19．82）mmHg、（81．69士23．84）mmHg（P〈0．05）。氧合指数（Pa02／Fi02）分别由治疗前的（218．30±70．98）（173．59±74．44）增加到（275．52±68．40）、（237．02±89．22）（P〈0．05）;动脉二氧化碳分压（PaC02）分剐由（51．42±12．43）mmHg、（48．95±12．11）mmHg下降到（40．11±7．87）mmHg、（41．89土12．69）mmHg（P〈0．05）。在颅内出血并发症中CMV治疗组高于HFOV治疗组（P〈0．05）。【结论】CMV与HFOV用于新生儿重症MAS疗效好,均能较快改善肺氧合功能,改善预后,HFOV在重症MAS应用中可作为CMV应用失败的补救方法,并发症较低。