Colò F, Girardis M, Pasqualucci A, Da Broi U, Pasetto A
Cattedra di Anestesia e Rianimazione, Università degli Studi di Udine.
Minerva Anestesiol. 1994 Jul-Aug;60(7-8):367-74.
To evaluate the effects of physiological ventilatory patterns on P(a-ET)CO2 gradient and on the alveolar dead space production during controlled mechanical ventilation.
Prospective and experimental comparison among three different ventilatory settings in three different groups of subjects.
General surgery's operating-theatre in university hospital.
Twenty-eight patients subdivided randomly in 3 groups differing for ventilatory setting. I group: constant tidal volume (VC = 8 ml.kg-1) and 3 different respiratory frequencies (f = 10, 12 and 14 breaths.min-1); II group: constant ventilation (112 ml.kg-1) but VC and f modified in three different ways; III group: inspiratory volume was set to give an end-tidal PCO2 (PETCO2) of about 35 mmHg. The cases were subdivided, on the basis of P(a-ET)CO2 distribution, in three groups: group with values larger than mean plus 1 standard deviation, group with values between +/- 1 standard deviation and group with values lower than mean minus 1 standard deviation. Moreover in two homogeneous groups for age.
General surgery but not important because measures were performed before surgical manoeuvres.
Anthropometrical data (age and body weight), PaCO2, PETCO2, heart rate, invasive arterial pressure, ventilatory parameters and airway pressure were collected for every subject and ventilatory setting; arterial to end-tidal difference P(a-ET)CO2 and P(a-ET)CO2.PaCO2(-1) were calculated during data analysis. The P(a-ETFCO2 and P(a-ET)CO2.PaCO2(-1) values were not significantly different among the three different ventilatory patterns both in the first and in the second group. P(a-ET)CO2 values were significantly correlated with age, body weight and airway pressure. These parameters were correlated significantly also with P(a-ET)CO2.PaCO2(-1) values.
Ventilatory setting, used in a normal physiological range, don't affect P(a-ET)CO2 difference during mechanical ventilation. Age, body weight and airway pressure of the patient must be considered to obtain a correct value of PaCO2 by the measure of PETCO2.
评估在控制机械通气期间生理通气模式对动脉血二氧化碳分压与呼气末二氧化碳分压（P(a - ET)CO2）差值以及肺泡死腔产生的影响。
在三组不同受试者中对三种不同通气设置进行前瞻性实验比较。
大学医院普通外科手术室。
28例患者随机分为3组，每组通气设置不同。I组：潮气量恒定（VC = 8 ml·kg-1），呼吸频率有3种不同设置（f = 10、12和14次/分钟）；II组：分钟通气量恒定（112 ml·kg-1），但潮气量和呼吸频率有三种不同的调整方式；III组：设置吸气量以使呼气末二氧化碳分压（PETCO2）约为35 mmHg。根据P(a - ET)CO2分布将病例分为三组：值大于均值加1个标准差的组、值在±1个标准差之间的组以及值小于均值减1个标准差的组。此外，按年龄分为两个同质组。
普通外科手术，但这不重要，因为测量在手术操作前进行。
收集每个受试者在每种通气设置下的人体测量数据（年龄和体重）、动脉血二氧化碳分压（PaCO2）、呼气末二氧化碳分压（PETCO2）、心率、有创动脉压、通气参数和气道压力；数据分析期间计算动脉血与呼气末二氧化碳分压差P(a - ET)CO2以及P(a - ET)CO2/PaCO2(-1)。在第一组和第二组中，三种不同通气模式下的P(a - ETFCO2和P(a - ET)CO2/PaCO2(-1)值无显著差异。P(a - ET)CO2值与年龄、体重和气道压力显著相关。这些参数也与P(a - ET)CO2/PaCO2(-1)值显著相关。
在正常生理范围内使用的通气设置在机械通气期间不影响P(a - ET)CO2差值。为通过测量PETCO2获得正确的PaCO2值，必须考虑患者的年龄、体重和气道压力。
