Effect of the I/E ratio on CO2 removal during high-frequency oscillatory ventilation with volume guarantee in a neonatal animal model of RDS.
The objective of this study was to analyze the effect of I/E ratio on carbon dioxide (CO2) elimination during high-frequency oscillatory ventilation (HFOV) combined with volume guarantee (VG). Five 2-day-old piglets were studied before and after a bronchoalveolar lavage (BAL). The effect of an I/E ratio of 1:1 and 1:2 with (VG-ON) and without VG (VG-OFF) on PaCO2, as well as delta and mean airway pressures at the airway opening (∆Phf-ao, mPaw-ao) and at the tracheal level (∆Phf-t, mPaw-t) were evaluated at frequencies of 5, 8, 11, and 14 Hz. With the VG-ON, PaCO2 was significant lower with the I/E ratio of 1:2 at 5 Hz compared with the 1:1. mPaw-t was higher than mPaw-ao, with 1:1 I/E ratio, and on VG-ON, this difference was statistically significant.


CONCLUSIONS
"In this animal study and with this ventilator, the I/E ratio of 1:1 compared to 1:2 in HFOV and VG-ON did not produce a higher CO2 lavage as when HFOV was used without the VG modality. Even more, a lower PaCO2 was found when using the lower frequency and 1:2 ratio compared to 1:1. So in contrast to non-VG HFOV mode, using a fixed tidal volume, no significant changes on CO2 elimination are observed during HFOV when the I/E ratios of 1:1 and 1:2 are compared at different frequencies."


BACKGROUND
•The tidal volume on HFOV is determinant in CO 2 removal, and this is generated by delta pressure and the length of the inspiratory time. What is New: •HFOV combined with VG, an I/E ratio of 1:2 is more effective to remove CO 2 , and this is not related to the tidal volume.
Neonatology Division, Instituto de Investigación Sanitaria Gregorio Marañón, Hospital General Universitario Gregorio Marañón, University Complutense of Madrid, Madrid, Spain. msluna@salud.madrid.org.
Manuel
M
Sánchez-Luna
Neonatology Division, Instituto de Investigación Sanitaria Gregorio Marañón, Hospital General Universitario Gregorio Marañón, University Complutense of Madrid, Madrid, Spain.
Noelia
N
González-Pacheco
Medical and Surgical Research Unit, Instituto de Investigación Sanitatia Puerta de Hierro-Majadahonda, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain.
Martín
M
Santos
Anaesthesia and Critical Care Department, Instituto de Investigación Sanitatia Puerta de Hierro-Majadahonda, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain.
Ángel
Á
Blanco
Medical and Surgical Research Unit, Instituto de Investigación Sanitatia Puerta de Hierro-Majadahonda, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain.
Cristina
C
Orden
Division of Neonatology, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
Jaques
J
Belik
Medical and Surgical Research Unit, Instituto de Investigación Sanitatia Puerta de Hierro-Majadahonda, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain.
Francisco J
FJ
Tendillo
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D004195:Disease Models, Animal; D045853:Exhalation; D006612:High-Frequency Ventilation / Q000379:methods*; D001239:Inhalation; D055370:Lung Injury / Q000517:prevention & control*; D011659:Pulmonary Gas Exchange; D011897:Random Allocation; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control*; D013552:Swine; D013990:Tidal Volume
D002245:Carbon Dioxide
Carbon dioxide; High-frequency ventilation; Lung injury; Neonatal respiratory distress syndrome; Prematurity