 Whenever a patient gets extubated in our MSICU, we conduct a routine extubation readiness test. This is standard of care in our ICU. If the patient fails this test, the patient stays on the ventilator. If he passes, he gets extubated. We wish to conduct a study during which we will monitor the electrical activity of the diaphragm during this test. If the patient passes the extubation readiness test, the study is complete. If he fails, he resumes on the ventilator. In our study, we would then use the measured signal of the diaphragm to guide the ventilator. This mode of ventilation is called NAVA. We do not currently use this mode of ventilation in the ICU, but could do so since it is FDA approved. However, we wish to use this protocol to gain more expertise with this mode of ventilation in the ICU in a controlled fashion. We wish to enroll 20 pediatric patients. Patients in the ICU are routinely on a variety of different models of ventilators. Usually, the respiratory therapist determines which ventilator will be used. All patients in this study would be on the Servo-I ventilator, which is an FDA approved ventilator and capable of monitoring electrical activity of the diaphragm and currently used in our MSICU. 