Nakagawa N K, Macchione M, Petrolino H M, Guimarães E T, King M, Saldiva P H, Lorenzi-Filho G
Faculdade de Medicina da Universidade de São Paulo, Brazil.
Crit Care Med. 2000 Feb;28(2):312-7. doi: 10.1097/00003246-200002000-00004.
To evaluate the effects of a heat and moisture exchanger and a heated humidifier on respiratory mucus and transportability by cilia and cough in patients undergoing invasive mechanical ventilation (up to 72 hrs).
Prospective, randomized, clinical study.
General intensive care unit and university research laboratory.
A total of 32 consecutive patients with acute respiratory failure, who were intubated and mechanically ventilated in the intensive care unit setting, were enrolled in the study.
Patients were randomly assigned to receive as a humidifying system a heat and moisture exchanger (HME) or heated humidified water (HHW) at the onset of mechanical ventilation (time 0). Respiratory mucus samples were collected by suction using a sterile technique at time 0, 24, 48, and 72 hrs of mechanical ventilation.
Eleven patients were excluded from this study because of either extubation or death before 72 hrs of mechanical ventilation, leaving 12 patients in the HME group and nine patients in the HHW group. Ventilatory variables including minute volume, mean airway pressure, positive end-expiratory pressure, Fio2, as well as Pao2/Fio2 ratio, fluid balance (last 6 hrs), furosemide, and inotrope administration (last 4 hrs) were recorded. In vitro mucus transportability by cilia was evaluated on the mucus-depleted frog palate model, and the results were expressed as the mucus transport rate. Cough clearance (an estimation of the interaction between the flow of air and the mucus lining the bronchial walls) was measured using a simulated cough machine, the results being expressed in millimeters. Mucus wettability was measured by the contact angle between a mucus sample drop and a flat glass surface. Mucus rheologic properties (mechanical impedance [log G*] and the ratio between viscosity and elasticity [tan delta]) were measured using a magnetic microrheometer at 1 and 100 cGy/sec deformation frequency. The two humidification groups were comparable in terms of the Acute Physiology and Chronic Health Evaluation II score, age, gender, ventilatory variables, fluid balance, use of inotropes, and furosemide.
Ours results indicate that air humidification with either HME or HHW at 32 degrees C (89.6 degrees F) has similar effects on mucus rheologic properties, contact angle, and transportability by cilia in patients undergoing mechanical ventilation, except for transportability by cough, which diminished after 72 hrs of mechanical ventilation in the HME group (p = .0441).
评估热湿交换器和加热湿化器对有创机械通气（长达72小时）患者呼吸道黏液以及纤毛转运能力和咳嗽的影响。
前瞻性、随机、临床研究。
综合重症监护病房和大学研究实验室。
共有32例急性呼吸衰竭患者连续入组本研究，这些患者在重症监护病房接受插管和机械通气。
在机械通气开始时（时间0），患者被随机分配接受热湿交换器（HME）或加热湿化水（HHW）作为湿化系统。在机械通气0、24、48和72小时时，采用无菌技术通过吸痰收集呼吸道黏液样本。
11例患者因在机械通气72小时前拔管或死亡被排除本研究，HME组剩余12例患者，HHW组剩余9例患者。记录通气变量，包括分钟通气量、平均气道压、呼气末正压、吸入氧浓度、氧合指数、液体平衡（最后6小时）、呋塞米及血管活性药物使用情况（最后4小时）。在去除黏液的蛙腭模型上评估纤毛对体外黏液的转运能力，结果以黏液转运速率表示。使用模拟咳嗽机测量咳嗽清除能力（评估气流与支气管壁衬里黏液之间相互作用的指标），结果以毫米表示。通过黏液样本液滴与平坦玻璃表面之间的接触角测量黏液润湿性。使用磁微流变仪在1和100 cGy/秒的变形频率下测量黏液流变学特性（机械阻抗[log G*]以及黏度与弹性之比[tan δ]）。两组在急性生理与慢性健康状况评分系统II评分、年龄、性别、通气变量、液体平衡、血管活性药物使用情况及呋塞米使用方面具有可比性。
我们的结果表明，在32摄氏度（89.6华氏度）下，使用HME或HHW进行空气湿化对机械通气患者的黏液流变学特性、接触角及纤毛转运能力具有相似影响，但咳嗽转运能力除外，HME组在机械通气72小时后咳嗽转运能力下降（p = 0.0441）。
