Page 696 - Clinical Application of Mechanical Ventilation

662 Chapter 19

to ventilatory failure. By 10:30 a.m., the patient’s vital capacity had dropped
Bilateral breath sounds to 0.7 L (20% of predicted) and maintaining adequate oxygenation was be-
suggests proper endotracheal
intubation. This sign should coming more difficult. Consequently, a decision was made to perform elective
coincide with absence of
respiratory distress, presence intubation. Family members were informed of the decision and the respiratory
of adequate SpO 2 , and stable therapist gathered the necessary equipment for a controlled intubation. The pa-
vital signs.
tient was mildly sedated and orally intubated with a size 7.5 ET tube without
difficulty. Bilateral breath sounds were heard and a portable chest radiograph
was ordered.

Initial Settings

Following intubation and confirmation of proper tube placement, the patient was
placed on volume-controlled ventilation in assist/control mode (A/C), backup fre-
quency of 12, tidal volume of 600 mL (approx. 12 mL/Kg), and F O of 40%.
2
I
PEEP was not initiated at that time. ABGs revealed the following:
pH 7.36
PaCO 2 43 mm Hg
PaO 2 53 mm Hg
SaO 2 86%
-
HCO 23.7 mEq/L
3
Mode A/C
f 12/min
Spont f 17 min
V T 500 mL
F O 2 40%
I
The ventilator settings were changed accordingly to a backup frequency of 14/min,
F O of 50%, and PEEP of 5 cm H O. Follow-up ABGs showed:
I
2
2
pH 7.45
PaCO 2 42 mm Hg
PaO 2 73 mm Hg
SaO 2 94%
-
HCO 28 mEq/L
3
Mode A/C
f 14/min
V T 500 mL
F O 2 50%
I
PEEP 5 cm H O
2
The patient remained relatively stable and was monitored closely for signs of respi-
ratory distress, difficulty breathing, or ventilator dyssynchrony. The ventilator peak
flow was adjusted to meet the patient’s inspiratory demand without compromise
to alveolar ventilation. By the third ventilator day, the F O was increased to 60%
I
2
and the PEEP was increased to 8 cm H O. These changes were made to prevent
2

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