Page 708 - Clinical Application of Mechanical Ventilation

674 Chapter 19

F O 2 100%
I
PIP of 24 cm H 2 O should mPaw 14.5 cm H O
be increased to 28 cm H 2 O 2
to achieve the estimated V T , The PIP/PEEP were changed to 28/6 cm H O and the f was changed to 50/min.
which may enhance alveolar 2
recruitment and oxygenation. At this PIP, the V has increased to 15.5mL. Also, blood gases and transcutaneous
T
gas tension showed:
pH 7.41
Since the initial f is 40/ PaCO 34 mm Hg
min (or 1.5 sec cycle time) 2
and the T INSP is 0.5 sec, the T EXP PaO 2 45 mm Hg
is 1.5 2 T INSP 5 1.5 2 0.5 HCO 21.1 mEq/L
-
sec 5 1 sec. The I:E ratio is 3
therefore 1:2. B.E. 22.7 mEq/L
SpO 2 86%
P O 2 28 mm Hg
tc
P CO 2 30 mm Hg
tc
Mode SIMV
PIP/PEEP 28/6 cm H O
2
f 40/min
The increase in PIP and T 0.5 sec
PEEP causes a higher mPaw INSP
(from 14.5 to 16.5 cm H 2 O). F O 2 100%
I
This may (1) lower the pro- mPaw 16.5 cm H O
duction of natural surfactant, 2
(2) cause patent ductus arte- An echocardiogram was performed at this time, and it confirmed a patent ductus
riosus (PDA), and (3) increase
the risk of barotrauma. Pre- arteriosus (PDA) with a right-to-left shunt and evidence of persistent pulmonary
and postductal saturations hypertension of the newborn. The patient was started on 0.2 mg/kg of indometha-
were measured, revealing a
preductal SpO 2 of 86% and a cin. Administration of indomethacin includes 3 doses, with the second being 12
postductal SpO 2 of 70%. hours after the first, and the third dose 24 hours after the second.

Twelve hours after the second indomethacin administration, the blood gases
showed:
pH 7.59
PaCO 2 27 mm Hg
PaO 2 66 mm Hg
-
HCO 24.9 mEq/L
3
B.E. 3.1 mEq/L
SpO 2 96%
P O 2 53 mm Hg
tc
P CO 2 28 mm Hg
tc
Mode SIMV
PIP/PEEP 28/6 cm H O
2
f 40/min
The PDA has partially T 0.3 sec
closed allowing a decrease of INSP
the right-to-left shunt. This F O 2 100%
I
lowers the peak inspiratory
pressure and improves gas mPaw 16.5 cm H O
2
exchange. The risk of baro-
trauma is therefore lowered. Over the course of the next 12 hours, the infant slowly began to wean from the
ventilator. The following results were obtained:
pH 7.38
PaCO 2 42 mm Hg
PaO 2 56 mm Hg

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