Specifications

1General Description
Chapter 1 General Description
The BiPAP S/T System
The BiPAP S/T is a low-pressure, electrically driven ventilation system with electronic pressure control.
The unit’s pressure controls are adjusted to deliver pressure support for patient ventilatory assistance.
The BiPAP S/T System is primarily intended to augment patient ventilation by supplying pressurized air
through a patient circuit. It senses the patient’s breathing effort by monitoring airflow in the patient
circuit and adjusts its output to assist in inhalation or exhalation. This assistance is provided by the
administration of two levels of positive pressure. During exhalation, pressure is variably positive or near
ambient. The inspiratory level is variably positive and is always higher than the expiratory level.
The Respironics BiPAP S/T System responds to changes in patient flow rates that indicate movement to
inhalation and exhalation. It can perform reliably in sensing the patient’s breathing efforts, even with the
presence of most leaks in the patient circuit. Automatic adjustment of the trigger threshold in the
presence of leaks make the System ideal for mask-applied ventilation assistance.
The BiPAP S/T senses air flow in the patient circuit by using a flow transducer in conjunction with the
patient air outlet. The flow signal is composed of flow into the patient’s lungs and flow due to leaks in the
patient circuit. This flow data is continually processed and adjustments are automatically made to trigger
thresholds. The adjustments provide high sensitivity to inspiratory effort and rapid adjustment for
changing leaks while minimizing inspiratory pressure lockup or auto-triggering.
The System can operate in the following four modes. In all of the modes, the prescribed setting for each
functional control must be determined by the physician/technician based on appropriate patient testing
and monitoring of the necessary physiologic parameters.
Spontaneous (S) Mode
The unit cycles between the Inspiratory Positive Airway Pressure (IPAP) and Expiratory
Positive Airway Pressure (EPAP) levels in response to patient triggering. The patient
determines the respiratory rate.
Spontaneous/Timed (S/T) Mode
The unit cycles between the IPAP and EPAP levels in response to patient triggering. If
the patient fails to initiate an inspiration, the unit will cycle to IPAP based on a preset
interval determined by the Breaths Per Minute (BPM) control.
Timed (T) Mode
The unit cycles between the IPAP and EPAP levels based solely on the timing intervals as
determined by the rate (BPM) and inspiratory time (% IPAP) controls. The patient may
superimpose spontaneous respirations over the IPAP and EPAP levels.
Continuous Positive Airway Pressure (CPAP)
With the Function Selector Knob set in either the IPAP or EPAP position, the pressure set
on the corresponding dial will be delivered continuously.
Note: Occasionally, cosmetic changes may be made to a product that do not affect its performance
or specifications. These changes do not warrant reprinting the manual. Illustrations are for
reference only.