Aim-To assess the change in stress response in preterm babies changed
from patient triggered ventilation (PTV) to conventional mandatory ven
tilation (CMV) and vice versa; to determine outcome in relation to str
ess hormone concentrations. Methods-A randomised controlled study was
conducted in two district general hospital neonatal intensive care uni
ts. Thirty babies, treated initially with CMV, were randomly assigned
to remain on CMV or to change to PTV. A second group of 29 babies, tre
ated initially with PTV, were randomly assigned to remain on PTV or to
change to CMV. The babies were less than 32 weeks of gestation, venti
lated within 72 hours of birth, with clinical and radiological feature
s compatible with respiratory distress syndrome (RDS). Stress hormone
concentrations and clinical distress score were measured before and 20
minutes after allocation of mode of ventilation. Results-Babies chang
ed from CMV to PTV had significantly reduced adrenaline concentrations
(median change -0.4 nmol/l) compared with those who remained on CMV.
There was no increase in adrenaline in babies changed from PTV to CMV.
There were no significant changes in noradrenaline concentrations or
clinical distress score. Babies who died had significantly higher adre
naline and noradrenaline concentrations than those who survived. Concl
usion-A change in mode of ventilation significantly reduces adrenaline
concentrations. Raised catecholamine values are associated with a poo
r outcome.