支气管收缩期间通过气管内气体吹入和胸部振动进行通气支持。

Department of Anesthesia, University of Pennsylvania Medical School, and Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia 19104, USA.

Crit Care Med. 2000 Jul;28(7):2533-9. doi: 10.1097/00003246-200007000-00057.

OBJECTIVE

To determine whether chest wall vibration with tracheal gas insufflation during bronchoconstriction maintains gas exchange at lower airway and intrathoracic pressures than those that occur during positive pressure ventilation.

DESIGN

Prospective study.

SETTING

Experimental laboratory.

SUBJECTS

Six anesthetized, paralyzed mongrel dogs (mean weight, 24.7+/-3.8 kg).

INTERVENTIONS

Dogs were ventilated by two methods: mechanical ventilation (7 breaths/min, 25 mL/kg tidal volume); and tracheal oxygen insufflation at 0.15 L x kg(-1) x min(-1) delivered with external chest wall vibration (29 Hz, 2 mm amplitude) of the dependent hemithorax. Bronchoconstriction was induced by methacholine infusion adjusted to double and quadruple the baseline airway resistance. Proximal mean airway pressure was kept equal for both modes of ventilation.

MEASUREMENTS AND MAIN RESULTS

Airway pressure and flow, esophageal pressure, hemodynamic variables (cardiac output, systemic and pulmonary arterial pressures, pulmonary artery occlusion pressure) and gas exchange variables (PaO2, PaCO2, pH, shunt fraction, VO2) were measured. Peak airway pressure was lower (p < .05) with insufflation and vibration than with mechanical ventilation by 83.6% at baseline resistance, by 76.9% at twice baseline resistance, and by 76.8% at four times baseline resistance. Peak esophageal pressure was lower (p < .05) during insufflation with vibration by 68.5% at baseline resistance, by 87.5% at twice baseline resistance, and by 107% at four times baseline resistance. During insufflation with vibration, mild hypercapnia (PaCO2 58+/-3 torr (7.7+/-0.4 kPa) and pH 7.28+/-0.02) developed with moderate bronchoconstriction; more profound respiratory acidosis (PaCO2 137+/-41 torr (18.2+/-5.5 kPa) and pH 6.87+/-0.11) developed with severe bronchoconstriction.

CONCLUSIONS

Tracheal gas insufflation with chest vibration supports gas exchange with permissive hypercapnia only during moderate, not severe, bronchoconstriction. Gas exchange was achieved at lower airway and intrathoracic pressures than those that developed during mechanical ventilation. The alveolar hypoventilation that occurred during insufflation with vibration indicates impaired CO2 elimination and suggests increased resistance to CO2 transport. This ventilation technique may confer therapeutic advantages over mechanical ventilation in the treatment of asthma.

目的

确定在支气管收缩期间，气管内吹气联合胸壁振动能否在低于正压通气时的气道和胸内压水平维持气体交换。

设计

前瞻性研究。

地点

实验实验室。

对象

6只麻醉、麻痹的杂种犬（平均体重24.7±3.8千克）。

干预措施

通过两种方法对犬进行通气：机械通气（7次/分钟，潮气量25毫升/千克）；以及以0.15升·千克⁻¹·分钟⁻¹的速率进行气管内输氧，并对非下垂半侧胸壁进行外部胸壁振动（29赫兹，振幅2毫米）。通过输注乙酰甲胆碱诱导支气管收缩，使基线气道阻力加倍和四倍。两种通气模式下近端平均气道压保持相等。

测量指标及主要结果

测量气道压力和流量、食管压力、血流动力学变量（心输出量、体循环和肺动脉压、肺动脉闭塞压）以及气体交换变量（动脉血氧分压、动脉血二氧化碳分压、pH值、分流分数、氧耗量）。在基线阻力时，吹气联合振动时的峰值气道压比机械通气时低（p<0.05）83.6%，在两倍基线阻力时低76.9%，在四倍基线阻力时低76.8%。在吹气联合振动期间，基线阻力时峰值食管压低（p<0.05）68.5%，两倍基线阻力时低87.5%，四倍基线阻力时低107%。在吹气联合振动期间，中度支气管收缩时出现轻度高碳酸血症（动脉血二氧化碳分压58±3托（7.7±0.4千帕），pH值7.28±0.02）；重度支气管收缩时出现更严重的呼吸性酸中毒（动脉血二氧化碳分压137±41托（18.2±5.5千帕），pH值6.87±0.11）。