Page 690 - Clinical Application of Mechanical Ventilation

656 Chapter 19

CASE 10: MYASTHENIA GRAVIS

INTRODuCTION

G.L. was a 72-year-old Caucasian male (6'1", 74-Kg) with a history of myasthenia
gravis for 25 years, but it had been in remission until about 6 months ago. His last
hospitalization was 2 months ago because of ongoing shortness of breath, fatigue,
inability to complete a sentence without taking a breath, chronic cough, malaise,
yellow sputum production, and difficulty in swallowing. The diagnosis was pneumo-
nia and he required mechanical ventilation for 17 days. He was eventually weaned
off mechanical ventilation and discharged. During that hospitalization, he had
repeated guaiac positive stool samples indicative of the presence of occult blood in
the feces.
He had been home for 4 weeks and continued to have shortness of breath, fa-
A barium study is done to tigue, muscle weakness, orthopnea, and he had to sleep sitting up in his recliner.
evaluate the cause of guaiac
positive stools. He came to the outpatient radiology clinic for barium and chest radiograph stud-
ies. Upon arrival to the radiology department he was extremely short of breath,
and after his exams were completed he was referred to the emergency room. The
patient declined to be seen and went home with his wife.
Within 5 min of arrival at home the patient suffered a respiratory arrest. His wife
A chest radiograph is
done to evaluate the residual reported that he just stopped breathing and turned blue. The paramedics arrived
effects of pneumonia.
and attempted to intubate but were unsuccessful after three attempts. While being
transported to the ER, the patient had some spontaneous respirations but poor dia-
phragmatic movement.
The initial blood gas analysis done upon arrival to the ER revealed the following
The blood gas report results:
indicates that the primary
problem is acute ventilatory pH 6.95
failure imposed on chronic
ventilatory failure. PaCO 2 143 mm Hg
PaO 2 115 mm Hg
SaO 2 96%
-
HCO 30 mEq/L
3
Mode Ambu bag and mask
PaCO 2 indicates that FO 2 Estimated to be 100%
I
the bag/mask system in the Notes Poor ventilation
ambulance was not ventilat-
ing the patient.
Indications

The patient was intubated in the ER and bagged at a frequency of 20/min and an
-
HCO 3 is elevated as F O of 100%. Vital signs included: blood pressure 138/40 mm Hg, heart rate
a compensatory mechanism I 2
of the patient’s preexisting 60/min, temperature 95.2°F, SpO 97%, and Glasgow coma score 15. Bilateral
2
ventilatory failure. breath sounds were present. A chest radiograph (Figure 19-6) showed proper ET
tube position, good thoracic expansion, and barium particles in the left lower lobe.

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