[Application of electrical impedance equipment in evaluating local lung volume during different PEEP ventilation and at different respiratory rate].
OBJECTIVE
To evaluate the applicability of electrical impedance equipment in assessing local lung volume during different PEEP ventilation and at different respiratory rate in neonatal piglets.


METHODS
Electrical impedance measurements (EIM) were performed on 6 healthy newborn piglets (age 4 +/- 1 d, weight 1.66 +/- 0.31 kg) using 8 electrodes distributed to 4 quadrants of the lung (left, right, upper, lower). Tidal impedance and functional residual impedance changes during PEEP levels of 2, 4, 6 and 8 cm H2O and frequencies ranging from 0.5 to 15 Hz were investigated.


RESULTS
The sum of regional tidal impedance obtained from four quadrants, significantly reflected tidal volume (VT) measured by a pneumotachograph during both frequency and PEEP changed (r2 = 0.98). A decrease of PEEP 4 to 2 cm H2O caused a significant increase in total tidal impedance (TTI) as well as in VT (P < 0.01 and P < 0.05); whereas an increase in frequency from 0.5 to 15 Hz was associated with a significant decrease in both TTI and VT (P < 0.05 and P < 0.01). Increased frequency had a balancing effect on air distribution, whereas higher PEEP did not result in more homogeneous ventilation. Minimal impedance values (FRI) (surrogate variable for FRC) showed that total FRI significantly decreased with increasing PEEP level.


CONCLUSIONS
EIM demonstrated good applicability to assess changes in thoracic gas volume. It is highly suggested that this method could be considered and further studied as a non-invasive bedside method to monitor continuously regional lung ventilation of neonates under any mode of mechanical ventilation.
Huang
Qi-wei
QW
Department of Neonatology, Children's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai 200040, China.
Simbruner
Geoge
G
D000818:Animals; D000831:Animals, Newborn; D017097:Electric Impedance; D008176:Lung Volume Measurements / Q000379:methods; D011175:Positive-Pressure Respiration; D056152:Respiratory Rate; D013552:Swine