9/1/2001

This female patient was born prematurely at 24 weeks gestation and has a history of BPD, sepsis, pneumonia, and oxygen toxicity. She spent the first 6 months of her life in the neonatal ICU on a ventilator, after which time she was discharged to home with a tracheostomy and remained ventilator dependent. The patient is now approximately 1 year old. She was recently readmitted to Children's Hospital of Dallas with a chief complaint of respiratory distress and was later diagnosed with pseudomonas and viral pneumonia. At that time the patient was admitted to the PICU and placed on the Servo 300 ventilator (Siemens). The patient displayed a low oxygen saturation despite the administration of an FIO2 of 0.50. She was stabilized on the Servo 300 at the following settings: Pressure Control: 18 cmH2O; SIMV: 14; Pressure Support: 14 cmH2O; PEEP: 7 cmH2O; FIO2: 0.50 (Table 1). VBGS on the Servo were: pH: 7.43; PCO2: 50 mmHg; PO2: 55 mmHg; HCO3: 33; BE: 7.8 (Table 2).

The patient was trialed on different portable ventilators including the Achieva (Mallinckrodt) and the LTV1000 (Pulmonetic Systems). The Achieva does not allow Pressure Control ventilation in the SIMV mode. As such, the Achieva ventilator had to be set in the Assist Control mode in the Pressure Control setting. The patient was unable to tolerate ventilation on the Achieva as evidenced by an increase in her work of breathing, decreased SpO2, increased EtCO2, and decreased PO2. The patient was placed back on the Servo 300 at the previous settings.

After stabilization, the physician ordered a trial of the LTV1000. Note that the LTV reads both Pressure Control and Pressure Support from a baseline of 0; while the Servo 300 reads pressures from zero or the PEEP setting, whichever is greater. On the Servo, when the Pressure Control is set to 18 with a PEEP of 7, the "ventilating pressure'' is 18, the PIP is 25 cmH2O. In order to achieve an equivalent "ventilating pressure'' on the LTV, the Pressure Control must be set to 25 when the PEEP is set to 7.

The patient remained stable on the LTV1000, maintaining her EtCO2 in the mid 50 mmHg range. The LTV1000 has additional features, which allow adjustment of the ventilator to facilitate patient comfort or clinical need, including variable Rise Time, Flow Termination and Time Termination. Initially, the Rise Time was set at profile 5, the Flow Termination at 25% of Peak Inspiratory Flow, and the Time Termination was set at 0.7 seconds (Table 3). VBGS 10 hours after initiation of the LTV1000 revealed a pH: 7.38,. PCO2: 54 mmHG; PO2: 61 mmHg; HCO3: 32., BE: 6.3 (Table 4).

After approximately 14 hours on the LTV1000, the patient began to display signs of sepsis including tachypnea, with respirations ranging from 60-70 bpm, increased oxygen demand, and an increase in the work of breathing. To meet the patient's demand for increased inspiratory flow, the Rise Time profile was adjusted from a setting of 5 to a setting of 3, which decreased the time required to reach the Pressure Control and Pressure Support settings. The Flow Termination was increased from 25% of Peak Inspiratory Flow to 30% of Peak Inspiratory Flow to better anticipate the patient's expiration. These changes resulted in improved patient comfort, reducing her spontaneous respiratory rate from 60-70 bpm to 35-45 bpm, and reducing her work of breathing.

Once this patient recovers sufficiently to be discharged back to the home, she will be transitioned to the LTV950 on low flow oxygen. The LTV950 is similar to the LTV1000, but it does not have a high pressure, internal oxygen blender. The LTV950 does offer continuous flow, Pressure Control and Pressure Support Ventilation.

This patient was able to be successfully transitioned from the Servo 300 ventilator and was successfully maintained on the LTV1000 ventilator. The pulmonary medical staff attributed this to the fact that, unlike the other portable ventilators tried, the LTV1000 has continuous flow, is flow triggered, permits Pressure Control and Pressure Support ventilation in the SIMV mode, and has adjustable Rise Time and Flow Termination features.