Page 702 - Clinical Application of Mechanical Ventilation

668 Chapter 19

In addition to these symptoms, the patient experienced vertigo and diplopia at times
and sought medical attention when diffuse upper motor weakness appeared. Her
bulbar weakness and generalized fatigue necessitated admission for close observa-
tion in the ICU. Clostridium botulism was cultured from the salsa and also found to
be present in the patient’s stool. Community and state health officials were contacted
for an antitoxin, and subsequently this case was reported to the Centers for Disease
Control and Prevention (CDCP) in Atlanta. Within 24 hours of admission the patient
received trivalent botulism antitoxin, but she encountered progressive deterioration
with concomitant respiratory compromise.

Indications

On examination, the patient exhibited no evidence of distress. She did, how-
ever, manifest bilateral ptosis (drooping of eyelids) with decreased facial expression.
Her neck was supple, lungs were clear, and her mental status appeared normal.
Pupillary light reflexes revealed sluggish reactions bilaterally. The tongue was
midline with evidence of slurred speech. Motor examination revealed diffuse
weakness of the upper extremities. Symmetrical fatigability of the biceps, del-
toids, and grips was also noted. Gait revealed mild weakness, and electromyo-
gram (EMG) studies showed decreased amplitude of repetitive nerve action
potentials.
The patient was admitted for close observation. Vital capacities and maximum
inspiratory pressure (MIP) were done Q2 hours to assess her ventilatory status. Her
white blood cell count was 6,900 on admission and 12,500 (normal 3.2 to 9.8 3
3
10 ) 48 hours later. Vital signs revealed blood pressure of 168/56 mm Hg, heart rate
of 88/min, temperature of 36.4°C, and respirations of 24/min. Her initial arterial
blood gases on room air revealed:
pH 7.46
PaCO 2 36 mm Hg
PaO 2 72 mm Hg
SaO 2 95%
-
HCO 24.5 mEq/L
3
f 24/min
F O 2 21%
I
Her vital capacity at 03:30 was 1.6 L (62% of predicted) with a MIP of
218 cm H O. By 08:00, the condition of the patient remained relatively unchanged
2
except that her MIP had decreased to 212 cm H O. Due to progressive fatigue of
2
respiratory muscles, by 10:00, she was nasally intubated with a size 7.5 ET tube to
facilitate mechanical ventilation.
In spite of normal PaCO , mechanical ventilation is indicated because of her
2
progressive muscle weakness (decreasing MIP), impending fatigue, and anticipated
progression of botulism poisoning.

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