Page 603 - Clinical Application of Mechanical Ventilation

Neonatal Mechanical Ventilation 569

ECMO is contraindicated when mechanical ventilation has been used for more
ECMO candidates should than 2 weeks prior to the initiation of ECMO. This is because of the likelihood
have less than 2 weeks of
ventilator assistance, and have of the development of chronic lung disease, which ECMO cannot reverse (Short,
reversible lung disease.
1994). Additionally, candidates must have a reversible lung disease and should be
free of significant cardiac disease.

ECMO Criteria

Since ECMO therapy is reserved for candidates with an extremely high mortality rate
The mortality rate of
infants under conventional (80% or greater) under conventional ventilator care strategies, there are three ways
ventilator care strategies can to predict the occurrence of this mortality rate: (1) alveolar-arterial oxygen pressure
be predicted by three meth-
ods: P(A-a)O 2 , oxygen index, gradient [P(A-a)O or A-aDO ], (2) oxygen index, and (3) PaO or pH measurements.
2
2
2
PaO 2 or pH measurements.
Using the P(A-a)O . The P(A-a)O is measured and calculated with the patient on
2
2
100% oxygen:
P(A-a)O 5 barometric pressure 2 47 2 PaCO 2 PaO 2
2
2
P(A-a)O of 605 to 620 mm Hg (at 100% F O ) for 4 to 12 hours indicates a
2
2
I
need for ECMO therapy.
Using the Oxygen Index. The OI is determined as follows:
See Appendix 1 for
example. (mPaw * F O )
OI = I 2
PaO 2
Patients with an oxygen index of 0.35 to 0.6 for 30 minutes to 6 hours are inclusive
for ECMO therapy.
A study by Durand et al. (1990) described the use of the OI in addition to mPaw
to identify a select group of meconium aspiration patients for ECMO. Their conclu-
sions were that an OI greater than 0.4 and a mPaw of 20 cm H O or greater, may be
2
helpful in identifying patients who could benefit from ECMO.
Using the PaO or pH. A third criterion used is the presence of a PaO of 35 to 50 mm
2
2
Hg for 2 to 12 hours or a pH of ,7.25 for 2 hours with hypotension (Short, 1994).
Table 17-12 summarizes the parameters and critical values that may be used to
determine the need for ECMO therapy.

TABLE 17-12 Criteria for ECMO Therapy

Critical Value during
Parameter Mechanical Ventilation

Alveolar-arterial oxygen tension 605 to 620 mm Hg for 4 to
gradient (A-aDO ) on 100% F O 2 12 hours
2
I
Oxygen index (OI) 0.35 to 0.6 for 30 min to 6 hours
PaO 2 35 to 50 mm Hg for 2 to 12 hours

pH ,7.25 for 2 hours with hypotension
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