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Abstract
AIMS To describe the relation between oscillatory amplitude changes and arterial blood gas (ABG) changes in preterm infants receiving high frequency oscillatory ventilation, using a multiparameter intra-arterial sensor (MPIAS).
METHODS Continuous MPIAS ABG data were collected after amplitude changes and stratified according to Fio 2: high (> 0.4) or low (< 0.3). For each amplitude change, the maximum change (from baseline) in Paco 2 and Pao 2 over the following 30 minutes was determined. In total, 64 oscillatory amplitude changes were measured in 21 infants (median birth weight 1040 g; gestation 27 weeks).
RESULTS All amplitude increases produced Paco 2 falls (median −0.98 and −1.13 kPa for high and low Fio 2 groups respectively). All amplitude decreases produced Paco 2 rises (median +0.94 and +1.24 kPa for high and low Fio 2 groups respectively). About 95% of the change in Paco 2 was completed in 30 minutes. Amplitude changes did not affect Pao 2when Fio 2 > 0.4. When Fio 2 < 0.3, amplitude increases produced a Pao 2 rise (median = +1.1 kPa; P < 0.001) and amplitude decreases a fall (median = −1.2 kPa; P < 0.001).
CONCLUSIONS After oscillatory amplitude changes, the speed but not the magnitude of the Paco 2 change is predictable, and a rapid Pao 2 change accompanies the Paco 2 change in infants with mild lung disease and a low Fio 2.
Key messages
Key messages
A 3 cm H2O change in oscillatory amplitude results in a median change in Paco 2 of about 1.0 kPa (but the range of effect is wide)
Following changes in oscillatory amplitude:
the speed and direction of change in Paco 2 is predictable;
about 95% of the change in Paco 2 is completed within 30 minutes;
Pao 2 is unaffected if lung disease is severe;
if lung disease is mild/improving, rapid changes in Pao 2 occur (up to 4.7 kPa)
- arterial
- blood gas monitoring
- lung
- oscillatory amplitude
- prematurity
- ventilation