24 tcpO2/tcpCO2 Module Section
This chapter provides information on transcutaneous monitoring of oxygen (tcpO2) and of carbon dioxide (tcpCO2). It also provides information on preparing the transducer for use, and applying the transducer to the patient. This chapter includes the following sections:
• Introduction to the tcpO2/tcpCO2 Parameter Module . . . . . . . . 24-2
• Activating the Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-7
• Preparing the transducer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-8
• TroubleshootingCalibration Failure . . . . . . . . . . . . . . . . . . . . . 24-16
• tcpO2/tcpCO2 Alarms and INOP Messages. . . . . . . . . . . . . . . . . 24-21
• Parameter Settings Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-24
• Accessories and Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-25
• Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-26
• Care and Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-29
tcpO2/tcpCO2 Module Section 24-1
Introduction to the tcpO2/tcpCO2 Parameter Module
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Introduction to the tcpO2/tcpCO2 Parameter Module
What does it |
The tcpO2/tcpCO2 module measures the partial pressure of the oxygen |
Measure? |
and carbon dioxide that diffuses transcutaneously (through the skin). |
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The oxygen measurement is valid for an infant patient who is not under |
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gas anesthesia. These partial pressures provide a measure of the oxygen |
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and carbon dioxide levels in the blood. |
How the |
The tcpO2/tcpCO2 transducer heats the skin. This has the effect of |
tcpO2/ |
increasing local blood perfusion so that oxygen and carbon dioxide can |
tcpCO2 |
diffuse to the skin surface more easily. |
Measureme |
The transducer contains an electrolyte solution which is held in place by |
nt Works |
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two gas-permeable membranes. The oxygen and carbon dioxide that |
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diffuses out of the skin passes through these membranes into the |
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electrolyte solution where electrochemical reactions take place. These |
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reactions generate electrical signals which are representative of the |
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amounts of oxygen and carbon dioxide present. The electrical signals |
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are measured by the module to enable the tcpO2/tcpCO2 values to be |
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displayed as numerics on the standard display. |
Correlation of Transcutane ous with Arterial Blood Gas Values
Transcutaneous measurements are not capable of replacing arterial blood gas monitoring. However, transcutaneous monitoring can be used to reduce the frequency of arterial sampling.
Transcutaneous values are representative of the carbon dioxide and oxygen levels in the blood. The values at tissue level will not be the same as those measured arterially because of the transcutaneous nature of the measurement. However, provided that the transducer is properly handled by following the procedures described in this chapter, the transcutaneous values will correlate with (track closely) the arterial values. For example, a drop in transcutaneous values will usually indicate that arterial values have dropped as well.
Note that transcutaneous values will not always correlate with blood samples taken from the capillary blood of the heel (heelsticks or astrups).
24-2 tcpO2/tcpCO2 Module Section
Introduction to the tcpO2/tcpCO2 Parameter Module
For information on “Correlation of transcutaneous with arterial blood gas values”, see references 5, 6 and 7 in Appendix on Analog Output)
Setting up The optimum application period for the transducer at one site on a patient the Module is dependent on the transducer temperature and on the sensitivity of the
patient's skin. Before calibrating the transducer, (see the section
Calibrating the tcpO2/tcpCO2 Transducer in this chapter) you should adjust the transducer temperature and also set the Site Timer.
Warning
Transducer The temperature should be selected according to the patient’s age, Temperature weight and physical condition.
Available temperatures for the transducer are 37.0°C, 41.0°C, 41.5°C, 42.0°C, 42.5°C, 43.0°C, 43.5°C, 44.0°C, 44.5°C and 45.0°C. Usually, a higher transducer temperature results in both a better correlation and also a shorter time delay between a change in arterial blood gas and its detection by the transducer. However higher temperatures also increase the risk of skin burns. A temperature between 42° and 44°C is preferred by most physicians.
Note—The tcpO2 / tcpCO2 module is equipped with a temperature limiter which prevents the sensor temperature from exceeding 46ºC. If the temperature limiter fails, the following INOP message is displayed on the monitor:
•tc EQUIP MALF.
Site Timer The Site Timer helps you to guard against the risk of skin burn by ensuring that the transducer is used at one site for no longer than a predefined period. The transducer can be set to operate for any of the following time periods: 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7 or 8 hours. The selection is visible in the task window next to “Site Time##, and the time remaining before the Site Timer expires appears next to “Time Left:”.
Site time settings should be adapted to the patient's skin sensitivity.
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tcpO2/tcpCO2 Module Section 24-3
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Introduction to the tcpO2/tcpCO2 Parameter Module
After the selected period of time has expired, an INOP message “tcCHANGE SITE” is displayed and the INOP tone is sounded. The Monitor can be configured either to switch off the transducer heating when the Site Time has expired, or to continue monitoring. This should be set as required by your hospital's policy, either by your biomedical engineering department or by the Philips Service Engineer.
If the choice Off is available along with the above site times, you can choose to disable the Site Timer so that no “CHANGE SITE” reminder is displayed and the transducer monitors (and heats) indefinitely. Availability of this choice will depend on your hospital's policy and can be set by your biomedical engineering department or the Philips Service Engineer.
Correction for Transcutaneous pCO2 values tend to be higher than arterial values (due tcpCO2 Values to the metabolic processes of the skin and the effect of heating on the
blood under the transducer). This effect can be compensated for by selecting the Severinghaus correction in a special Configuration Mode on the monitor. (This has been selected if “corr.” appears under the value for tcpCO2 in the Task Window - consult your biomedical engineering department or the Philips Service Engineer if you wish to add or remove this correction.)
•The front of the module has two keys:
–The O2/CO2 key for parameter setup. A light will appear above the key when you are in setup.
24-4 tcpO2/tcpCO2 Module Section
Introduction to the tcpO2/tcpCO2 Parameter Module
– The CAL key to start calibration procedures.
tcpO2 /tcpCO2 |
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M1018A |
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O2 /CO2 CAL
80 x 70
Symbols to Indicate Key Functions
The tcpO2/tcpCO2 Module
Note—The “T” on the front of the module indicates that this module transfers parameter settings from one monitor to another.
As detailed in the table below, some versions of this module now use symbols, instead of words, to indicate the function of some keys. If the monitor’s Reference Manual tells you, for example, to select the CAL key, you should press the key marked with the corresponding “calibration” symbol.
The design change also means that you will now find the module’s product number on the rear of the module’s housing, not on the front. Although the new modules do not show the letter “T” on the housing, all modules retain their capability to transfer parameter settings from one monitor to another.
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tcpO2/tcpCO2 Module Section 24-5
Introduction to the tcpO2/tcpCO2 Parameter Module
Symbol |
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Which Modules? |
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Cal |
calibrate |
SvO2 (M1021A), tcpO2/tcpCO2 (M1018A) |
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Mainstream CO2 (M1016A) |
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24-6 tcpO2/tcpCO2 Module Section
Activating the Transducer
Activating the Transducer
Follow the 24 hour activation procedure if:
•the electrolyte in your transducer has dried out (this occurs when the transducer has been out of use for a long period),
•or you are about to use a new transducer (new transducers are shipped dry).
Activate by following the Remembraning the Transducer procedure, then leave the transducer in a safe place for 24 hours, unplugged from the module and with the cap on. Remembrane the transducer again just before carrying out the calibration procedure.
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tcpO2/tcpCO2 Module Section 24-7
Preparing the transducer
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Preparing the transducer
1. Remembrane the
tcpO2/ tcpCO2
Transducer
There are three steps to preparing a transducer for application to a patient.
First, remembrane the transducer.
Then, calibrate the transducer (first checking the module settings - Site Time, Transducer Temp and Alarm Limits).
Finally, prepare a site and apply the transducer to your patient.
The procedure for carrying out these steps is described in the following three sections. Each section gives guidelines on when you should carry out each step. Follow the procedures carefully to ensure best results.
With normal use, the membranes will last approximately 1 week before a change is required. Change the membrane on the transducer if:
•you are about to use a new transducer,
•the transducer is to be used with a new patient,
•the membranes of the transducer are damaged (scratched or wrinkled),
•the transducer has been used for 5 days continuously,
•the transducer has been in storage for up to 28 days,
•you have a transducer which must be remembraned after activating for 24 hours (see previous page, Activating the Transducer), or
•calibration has failed twice.
1.Check that you have the Philips tc Accessory Kit containing an O- ring remover, absorbent paper, electrolyte solution and membrane replacers.
24-8 tcpO2/tcpCO2 Module Section
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