Operator's Manual

3.3 Theory of operation
Tempus Pro User/Operator Manual - 41-2001EN-00 – Page 33
Moisture and patient secretions are extracted from the sample, while maintaining the shape of the CO
2
waveform.
The 50 ml/min. sampling flow rate reduces liquid and secretion accumulation, decreasing the risk of
obstruction in the sample pathway in humid ICU environments.
Once inside the Microstream® CO
2
sensor, the gas sample goes through a micro-sample cell (15
microliters). This extremely small volume is quickly flushed, allowing for fast rise time and accurate CO
2
readings, even at high respiration rates.
The Micro Beam IR source illuminates the micro-sample cell and the reference cell. This proprietary IR light
source generates only the specific wavelengths characteristic of the CO
2
absorption spectrum. Therefore, no
compensations are required when different concentrations of N
2
O, O
2
, anaesthetic agents and water vapour
are present in the inhaled and exhaled breath. The IR that passes through the micro-sample cell and the IR
that passes through the reference cell are measured by the IR detectors. The microprocessor in the monitor
calculates the CO
2
concentration by comparing the signals from both detectors.
3.3.6 Temperature
Two channels of contact temperature are measured through two sockets on the Tempus. These sockets are
compatible with YSI type 400 probes only. A range of third-party YSI 400 series compatible transducers
may be used with the Tempus. These transducers may be re-usable or disposable.
The Tempus measures temperature by measuring the changing resistance in the tip of the transducer.
When a transducer is correctly attached to the Tempus and to the patient e.g. in the rectum or axilla, the
Tempus obtains a constant (“direct”) reading of resistance that equates to the temperature at that site.
There is no offset or reference body site. The device contains a self-checking system which checks the
thermometer against a known (internal) reference point (every second). If this cross-check fails at any time
the thermometer will be disabled and an error posted on the display.
The thermometer’s reading can be presented in ºC or ºF.
3.3.7 Invasive pressure
Two channels of invasive pressure are measured through a socket on the Tempus. An interface cable is
required to be attached to this socket, the interface cable splits into two ends, each of which can be
connected to a third-party pressure transducer (with a sensitivity of 5 µV/V/mmHg). A range of third-party
transducers (both reusable and disposable) are available. A list of compatible sensors is provided in section
14.8. A different interface cable is required to adapt the Tempus’ socket to the specific connectors of each
type of transducer.
The Tempus measures pressure by measuring the changing resistance in the transducer. When a
transducer is correctly attached to the Tempus and to the patient’s blood stream e.g. in the pulmonary
artery, the Tempus obtains a constant reading of resistance that equates to the systolic and diastolic
pressure. From this mean arterial pressure and heart rate are also calculated.
The option to use two additional channels invasive pressure measurement is provided by an external USB
IP Module. The 2 Channel IP Module can be located adjacent to the Tempus Pro or clipped onto a new
feature on the rear clip. There is no setup required to connect the USB device to the Tempus Pro, other
than plug the USB cable in. The Tempus Pro will automatically recognise that the module is attached.
3.3.8 Controls and indicators
The controls and indicators are divided into three types, items on a touchscreen, membrane buttons and
LED indicators. The Tempus Pro can be operated with or without gloves.
Note
Touchscreen and membrane buttons should be pressed once. As with all touchscreens if
your finger wavers or quivers, the Tempus Pro may register it as more than one press.
Note
To display ultrasound and video laryngoscopy images on the Tempus Pro's large colour
display, you can use third-party ultrasound probes and video laryngoscopy accessories. For
more information, see the Tempus Pro Ultrasound Supplement Guide and Tempus Pro
Laryngoscope Supplement Guide.