Page 671 - Clinical Application of Mechanical Ventilation

Case Studies 637

Patient Management

Initially, the patient’s respiratory status was stable but it began to deteriorate on
the second day. The ventilator settings were changed to accommodate the patient’s
needs. The ventilator settings were: CMV mode, f 35/min, V 720 mL, F O 100%,
2
T
I
20 cm H O PEEP. The peak inspiratory pressure was 80 cm H O, and the plateau
2
2
pressure was 70 cm H O. The blood gas results were:
2
pH 7.27
PaCO 2 43 mm Hg
PaO 2 72 mm Hg
-
HCO 19 mEq/L
3
SpO 2 92%
Mode CMV
f 35/min
V T 720 mL
F O 2 100%
I
PEEP 20 cm H O
2
PIP 80 cm H O
2
P PLAT 70 cm H O
2
Because of the increasing pressure requirement, pressure-controlled ventilation
In PCV, the initial pres- (PCV) was started to minimize the occurrence of volume- or pressure-induced lung
sure may be set at 10 cm H 2 O
below the peak inspiratory injuries. The pressure on PCV was initially set at 70 cm H O (10 cm H O below
2
2
pressure on CMV. the peak inspiratory pressure on CMV). Other ventilator parameters for PCV were:
inspiratory time 1 sec, f 35/min, F O 100%, 20 cm H O PEEP. The blood gases on
2
2
I
these settings were as follows:
pH 7.31
PaCO 2 41 mm Hg
PaO 2 56 mm Hg
-
HCO 20 mEq/L
3
SpO 2 88%
Mode PCV
PIP 70 cm H O
2
f 35/min
F O 2 100%
I
PEEP 20 cm H O
2
The inspiratory time was then increased to 2 sec to keep the PaO in the 70s. The
2
In PCV, the minute vol- I:E ratio was changed to 4:1 to provide longer inspiratory time. Subsequently, the
ume is primarily determined
by the pressure, inspiratory minute volume was increased with these settings and the pressure was lowered to
time, and lung compliance. 50 cm H O. Blood gases on these settings were satisfactory. The minute volume of
2
the patient was trended carefully during the use of PCV.
The patient was placed on a Roto-bed and was administered neuromuscular and
In ARDS, a lung protec- sedative agents to minimize agitation and oxygen consumption. For proper airway
tion strategy includes use of
low pressure and volume. management, a tracheostomy was performed because extended mechanical ventila-
tion was anticipated.

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