Page 676 - Clinical Application of Mechanical Ventilation

642 Chapter 19

B.E. 22.7 mEq/L
Hb 11.4 g %
CaO 2 17.7 vol %
SaO 2 90.5%
SpO 2 87%
Mode A/C
f 12/min
V T 1,000 mL
F O 2 60%
I
PEEP 5 cm H O
2
In an effort to minimize the effects of oxygen toxicity, the ventilator was adjusted
by increasing the PEEP to 8 cm H O to increase the PaO without raising the F O
I
2
2
2
over 60%.
Patient Management

Cardiac output and This patient was recovered from surgery in the ICU on mechanical ventilation, in
pulmonary capillary wedge
pressures are used to monitor an effort to minimize any postsurgical complications associated with continued
the adequacy of circulating blood loss, and to guard against the development of respiratory distress.
blood volume.
Following the rapid infusion of over 20 units of blood to cover his losses, assess-
ments with hemodynamic measurements including cardiac output and pulmonary
capillary wedge pressures (PCWP) helped to assure adequate perfusion to the tis-
sues. Oxygenation, under the conditions presented, may be complicated by the
use of stored blood used for volume replacement. Of particular importance is the
fact that stored blood contains limited amounts of 2,3 diphosphoglycerate (DPG),
which effectively shifts the oxyhemoglobin dissociation curve to the left. Thus,
stored blood reduces the unloading of oxygen at the tissues, causing hypoxia, necro-
sis, and possibly sepsis if not managed properly. As a result, the patient’s PaO was
2
closely monitored to maintain adequate oxygenation and saturation. He was also
monitored for clinical signs of tissue hypoxia with arterial-venous oxygen content
difference [C (a-v) O ]. At that time, follow-up blood gases revealed these results:
2
pH 7.47
PaCO 2 34 mm Hg
PaO 2 124 mm Hg
-
HCO 24.1 mEq/L
3
B.E. 21.7 mEq/L
Hb 11.4 g %
CaO 2 15.5 vol %
SaO 2 95.7%
SpO 2 94%
Mode A/C
f 12/min
V T 1,000 mL
F O 2 60%
I
PEEP 8 cm H O
2

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