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Chapter 12: Mechanical Ventilation

A 75-year-old man is admitted to the ICU with COPD exacerbation, and he required invasive mechanical ventilation. The patient is started on intravenous corticosteroids and bronchodilators. The patient has been stable on A/C volume control mode with VT of 500 mL, a rate of 12 breaths/min, a PEEP of 8 cm H2O, and an Fio2 of 50% with oxygen saturation of 98%. On his second day, the nurse notice sudden oxygen desaturation, agitation, and oral gurgling. Clinically, the patient seems agitated and uncomfortable. There are diminished breathing sounds bilaterally. There is no evidence of subcutaneous emphysema. The respiratory therapist also noticed a sudden change in his ventilator parameters. His ventilator parameters before and after the event are as follows:

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Ventilator Parameters Before After
Peak pressure 35 cm H2O 25 cm H2O
Plateau pressure 25 cm H2O 15 cm H2O
Airway resistance 10 cm H2O/L/sec 2 cm H2O/L/sec
Respiratory rate 16 breaths/min 24 breaths/min
O2 saturation 98% 85%
End-tidal CO2 40 mmHg 20 mmHg
Exhaled tidal volume 450 mL 150 mL

What is the most likely diagnosis?

A. Pneumothorax

B. Rupture of the ET cuff

C. Exacerbation of the COPD

D. Pulmonary edema

B. Rupture of the ET cuff

The change in the ventilator parameters described in this patient is consistent only with ET tube cuff leak. The sudden decrease in the peak and plateau pressures and airway resistance is consistent with this problem. The sudden decrease in the end-tidal carbon dioxide and the oxygen desaturation represent reduction in the effective tidal volume. The large gradient between the inspired and exhaled tidal volumes supports the diagnosis. In pneumothorax and pulmonary edema (change in lung compliance), there is usually a sudden increase in the peak and plateau pressures (choices A and D, respectively). Choice C is not correct because, in a patient with COPD exacerbation and bronchospasm, there is usually an increase in the gradient between peak and plateau pressures.

A 65-year-old man with a past medical history of severe COPD and forced expiratory volume during the first second (FEV1) of 0.70 Liter is admitted with progressive dyspnea, wheezing, and excessive accessory respiratory muscle use due to an upper respiratory viral infection. The patient did not show any improvement on noninvasive ventilation and he required intubation and mechanical ventilation. Two hours later, his physical examination reveals the following:

  • Vital signs: temperature of 98.5°F, pulse of 125 beats/min, blood pressure (BP) of 80/45 mmHg, RR of ...

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