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Typical flow diagram
The Single Chamber for Anesthetized Mouse is
used to make invasive Resistance and Compliance measurements on
mice and small rodents (neonatal rats). The animal is investigated
without surgical intervention. It is anesthetized so that the
esophageal and tracheal catheters can be inserted, and the animal
can recover after measurement. The basic arrangement of the apparatus
consists of a compact Plexiglas chamber. It performs two functions:
it acts as an operating table and has a cork plate fitted into
its base; after the animal preparation it is closed and serves
as a plethysmographic box. The chamber is jacketed with warm water
(37°C) from a thermostatic circulator passing through the
jacket and is closed by a jacketed cover; which is also thermostated
so that heat losses from the chamber are kept small. An intubation
or tracheal cannula is inserted in the animal and is connected
to a pneumotachometer. The pneumotachometer has to be placed as
close as possible to the cannula in order to ensure minimum dead
space. Incorporating it into the thermostated chamber also prevents
condensation of the moisture. The modular construction of the
pneumotachometer, permits easy dismantling after the experiment,
thus simplifying cleaning. There are only straight bores on the
pneumotachometer which can easily be cleaned; in addition the
transparent Plexiglas permits easy checking for cleanliness.
Other ports in the side walls allow connections to esophageal
catheter, blood pressure transducer, ECG amplifir, etc.
The oesophageal pressure (taken as the intrapleural
pressure) is measured using a fluid filled oesophageal catheter
and a P75 pressure transducer connected to a PLUGSYS Module TAM-A.
The respiratory flow is converted by means of the built in pneumotachometer
into a pressure difference and measured with a Validyne differential
pressure transducer DP 45-14. This is connected to the input of
a PLUGSYS CFBA module. The tidal volume is obtained by integrating
the respiratory flow signal; this operation is normally performed
by the evaluation software. From these three signals (oesophageal
pressure, respiratory flow, tidal volume) airway resistance as
well as dynamic compliance is calculated. This is done by computer
with suitable data acquisition hardware (HSE-HA PLUGSYS) and software
(HSE-HA PULMODYN).
The box is prepared for connecting an Anesthesia vaporizer as
well as an aerosol nebulizer which permits the administration
of aerosols through the intubated tracheal tube.
Ventilation using the MiniVent is also possible using a special
adapter.
From respiratory flow and esophageal pressure the HSE PULMODYN
software is used to evaluate the following parameter:
HUGO SACHS ELEKTRONIK-HARVARD
APPARATUS GmbH
Gruenstrasse 1 · D-79232 March-Hugstetten · GERMANY
Phone: +49 (0) 76 65 - 92 00-0 · Fax: +49 (0) 76 65 - 92
00-90