H. Nomori et al., Pressure-controlled ventilation via a minitracheostomy tube: Experimental study using a mechanical lung model, SURG TODAY, 31(9), 2001, pp. 780-784
To obtain basic data on pressure-controlled ventilation (PCV) via a minitra
cheostomy tube (MTT), we conducted an experimental study using a mechanical
lung model. MTTs with internal diameters of 4.0, 4.5-, and 5.0 mm were use
d. To examine the effectiveness of PCV via an MTT for the lung with low com
pliance, the ventilated volumes were measured at compliances ranging from 1
0 to 50 ml/cmH(2)O. The alveolar pressures and ventilated volumes of the 4.
0-, 4.5-, and 5.0-mm MTTs were about 40%, 50%, and 60% of the values for th
e 8.0-mm endotracheal tube in the absence of air leakage, respectively, and
in the presence of air leakage they fell a further 20%. To obtain a ventil
ated volume of 500 ml, the inspiratory pressures needed were 40, 30, and 20
cmH(2)O for the 4.0-, 4.5-, and 5.0-mm MTTs, respectively. In the model of
low lung compliance (10 ml/ cmH(2)O), the ventilated volumes decreased to
40% of those seen in the normal compliance model (50 ml/ cmH(2)O) at each i
nspiratory pressure, due to greater air leakage. PCV via an MTT produced ac
ceptable ventilated volumes in the lung model with air leakage. However, ou
r results indicate that under conditions of low lung compliance, PCV via an
MTT is insufficient because of the greater air leakage.