Theory Of Operation; Pneumatic System - Respironics ESPRIT Service Manual

Chapter 3. Theory of Operation

Pneumatic System

REF 580-1000-02 G
The Esprit mechanical ventilator is a microprocessor-controlled device that can
deliver air, oxygen, or a mixture of air and oxygen to the patient's lungs in a
predetermined manner to augment or replace the work normally performed by
the patient's respiratory system. It uses electromechanical control circuits,
flow and pressure monitors, and software programs to deliver breaths as a flow
or pressure controller.
The Esprit Ventilator includes a graphic user interface (GUI), internal blower,
and inspiratory module that mixes air and oxygen. The ventilator can operate
from a 40 to 90 psig (276 to 620 kPa) medical grade oxygen source for
enriched oxygen operation. It also includes multiple communications
interfaces and an internal power supply that can run from a 100 to 240 V AC
50/60 Hz or 24 V DC power sources.
Schematic diagrams of the Esprit Ventilator are available upon request.
The Esprit Ventilator pneumatic system consists of these subsystems (see
Figure 3-1):
• Internal blower (air source)
• Oxygen regulator (oxygen source)
• Inspiratory module
• Heated exhalation filter assembly
• Exhalation valve assembly
• Expiratory flow sensor
The internal blower generates the air pressure necessary for breath delivery,
eliminating the need for an external source of medical-grade compressed air.
An internal regulator regulates wall oxygen pressure. The ventilator mixes air
and oxygen in the inspiratory module before delivery to the patient.
Based on operator settings, the central processing unit (CPU) controls the air
valve, oxygen valve, and exhalation valve through stepper motor controller
printed circuit boards (PCBs). As flow is delivered to the patient, the air and
oxygen flow sensors and two pressure sensors provide feedback to the CPU.
The pressure relief and safety valves in the inspiratory module provide for
patient safety in the event of an over-pressure condition or any component or
system failure that could interfere with the patient's ability to breathe when
connected to the ventilator.
Esprit® Ventilator Service Manual © Respironics, Inc.
3-1