TOSCA 500 Operating Manual
LINDE MEDICAL SENSORS AG
TOSCA 500 Operating Manual
OPERATING MANUAL TOSCA 500
Publ. No: 520.81.001/0 Issued: 10/2004 Part No.: 520 0910
TOSCA 500 The TOSCA 500 Operating Manual is intended to provide the necessary information for proper operation of the TOSCA 500 system. General knowledge of transcutaneous measurement and pulse oximetry and an understanding of the features and functions of the TOSCA 500 system are a prerequisite for proper use. Do not operate the TOSCA 500 system without completely reading and understanding these instructions.
Your local contact for sales and service of TOSCA 500:
Linde Medical Sensors AG Austrasse 25 CH-4051 Basel Switzerland Tel.: +41 61 278 81 11 Fax: +41 61 278 81 81 email: [email protected]
The equipment has been designed and manufactured to meet the requirements of the following safety standards: IEC 60601-1 (1998), IEC 60601-1-2 (2001), IEC 60601-1-4 (1996), EN865 (1997), EN475 (1995), IEC 60601-2-23 (1999), IEC 60601-2-49 (2001), IEC 60601-3-1 (1996), CSA C22.2 No 601.1-M90 and UL 60601-1 (2003).
This equipment is fully in conformance with the requirements of the Council Directive 93/42 EEC of June 14, 1993 concerning Medical Devices.
Masimo patents of the integrated Masimo SET technology USA Patents and international equivalents, 5482036, 5490505, 5632272, 5685299, 5758644, 5769785, 6002952, 6036642, 6067462, 6157850 and 6206830. USA and international patents pending.
TOSCA 500 No implied license Possession or purchase of this device does not convey any express or implied license to use the device with replacement parts which would, alone, or in combination with this device, fall within the scope of one or more of the patents relating to this device. TOSCA is a trademark of Linde Medical Sensors. Masimo SET is a federally registered trademark of Masimo Corporation. Signal IQ, APOD and FastSat are trademarks of Masimo Corporation. All rights reserved. The information contained in this publication may not be used for any purpose other than that for which it was originally supplied. The publication may not be reproduced in part or in whole without the written consent of Linde Medical Sensors. In order to maintain and improve standards of manufacturing, methods of functioning and to increase reliability, Linde Medical Sensors equipments are periodically reviewed. For this reason, the contents of this publication are subject to change without notice. Copyright © 2004, Linde Medical Sensors AG.
QUALITY, RELIABILITY AND SAFETY This equipment has been designed with an emphasis on QUALITY, RELIABILITY AND SAFETY, but Linde Medical Sensors AG will accept responsibility for these aspects only when the following conditions are met: – Electrical installations of the room or building in which the equipment is to be used must comply with regulations specified by the country in which the equipment is to be used. – The equipment is used in accordance with the instructions for use provided by Linde Medical Sensors. – All modifications and repairs to the equipment are carried out by Linde Medical Sensors or by authorized service technicians. – Modifications must not be carried out unless they conform with approved Engineering Service Information issued according to the appropriate Linde Medical Sensors procedure. – Equipment installation must be carried out in accordance with local requirements regarding responsibility and warranty. – Only original sensors and accessories of Linde Medical Sensors must be used. Other sensors and accessories may cause improper monitor performance.
TABLE OF CONTENTS 1
SAFETY INFORMATION ... 8
2 2.1 2.2 2.3 2.4 2.4.1 2.4.2
INTRODUCTION...10 Intended use ...10 TOSCA 500 monitor ...10 TOSCA sensor 92 ...11 Concept of operation...11 Transcutaneous PCO2 ...11 Oxygen saturation SpO2 ...13
3 3.1 3.2 3.2.1 3.2.2 3.2.3 3.3 3.3.1 3.3.2
CLINICAL APPLICATION ...15 Indications ...15 Points to be regarded during monitoring ...15 General...15 Transcutaneous PCO2 measurement ...15 SpO2 measurement ...16 Limitations ...18 Transcutaneous PCO2 measurement ...18 SpO2 measurement ...19
4 4.1 4.1.1 4.1.2 4.1.3
DESCRIPTION OF THE MONITOR ...20 Overview...20 Front panel ...20 Underside ...21 Rear panel...22
5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.7.1 5.7.2 5.8
OPERATION...24 Initial setup of the system ...24 Precautions ...24 Setup for operation ...26 Sensor preparation ...29 Sensor application ...30 Patient monitoring ...32 Removal of the sensor ...34 Removal of the sensor from the clip ...35 Removal of the sensor and the clip from the ear ...35 Operation with a printer ...36
6 6.1 6.1.1 6.1.2
DISPLAY MODES ...37 STATUS display ...37 Description ...37 Parameter settings ...38
TOSCA 500 6.2 6.2.1 6.2.2 6.3 6.3.1 6.3.2 6.4 6.4.1 6.4.2
TREND display ...38 Description ...39 Parameter settings ...39 PLETHYSMOGRAM display...41 Description ...41 Parameter settings ...41 HEATING POWER display...42 Description ...42 Parameter settings ...43
7 7.1 7.2 7.2.1 7.2.2 7.2.3 7.2.4 7.2.5 7.2.6 7.2.7 7.2.8 7.3
SYSTEM PARAMETERS / MESSAGES...44 Parameter settings ...44 Description of parameters...45 Alarm parameters...45 PCO2 parameters ...47 Special PCO2 parameters...49 SpO2 / PR parameters...51 Configuration...52 User settings ...54 Print settings ...56 Print messages...58 Default parameter settings ...59
8 8.1 8.2 8.2.1 8.2.2 8.2.3 8.3
ALARMS - MESSAGES ...60 Description of the alarm functions ...60 Alarm messages...63 Physiological alarm messages – high priority ...63 Technical alarm messages – medium priority...64 Operating alarm messages – low priority...65 Monitoring messages ...65
9 9.1 9.2 9.3
TROUBLESHOOTING...67 During Monitoring - Application...67 During Calibration ...67 Monitor / Sensor ...68
10 10.1 10.2 10.3 10.4
MAINTENANCE...69 Routine maintenance...69 Check of monitor and sensor functions ...70 Battery Refresh Charge ...71 Disposal of equipment ...71
DECONTAMINATION ...72 Requirements ...72
TOSCA 500 11.2 11.3 11.4 11.5
Decontamination procedures ...72 Risks...73 DOs and DON’Ts ...73 Equipment requiring service...73
12 12.1 12.2 12.3 12.4
SPECIFICATIONS...74 TOSCA 500 monitor ...74 TOSCA sensor 92 ...76 System Performance ...77 Environmental conditions ...78
13 13.1 13.2 13.3 13.4 13.5
ELECTROMAGNETIC COMPATIBILITY DECLARATION ...79 Electromagnetic emissions ...79 Electromagnetic immunity...80 Electromagnetic immunity, RF portable equipment...81 Recommended separation distances ...82 Cables length...83
ACCESSORIES AND ORDERING INFORMATION ...84
A APPENDIX - EXTERNAL CONNECTIONS...85 A.1 Overview...85 A.2 Connecting to the Systems Connector...85 A.2.1 Systems Connector pinouts ...86 A.3 Communication protocol...87 A.4 EasyLink ...87 A.5 VueLink ...90 A.5.1 Messages ...92 A.5.2 VueLink Task Window example ...93 A.6 MonLink ...94 A.6.1 Serial port configuration ...94 A.6.2 Communication protocol...94 A.6.3 Legend of codes...96 A.7 Analog outputs...97 A.7.1 Calibration of an analog recording system...97 A.8 Nurse call...97 A.9 Connection to external battery...97
The instructions regarding precautionary measures given in this operating manual must be followed carefully. It is mandatory that these instructions are read prior to installation of the monitor.
Definition – A "WARNING !" indicates that there is a risk of injury to the patient or user. – A "CAUTION !" refers to a condition that may lead to damage or malfunction of the equipment. – A “Note” provides additional information.
WARNING The TOSCA 500 system is to be operated by qualified personnel only. This manual, accessory directions for use, all precautionary information, and specifications should be read before use. Explosion and flammability hazards: Do not use the monitor in the presence of flammable anesthetics or other flammable substance in any combination with air, oxygen-enriched environments, or nitrous oxide. Do not use the equipment in a hyperbaric environment. Do not use TOSCA 500 monitor and sensor on patients undergoing magnetic resonance imaging (MRI) scanning. Induced current could potentially cause burns. The TOSCA 500 monitor may affect the MRI image, and the MRI unit may affect the accuracy of the measurement. Electrical shock hazard. Do not remove the monitor cover. Only a qualified operator may perform maintenance procedures specially described in this manual. Failure of operation: If TOSCA 500 monitor fails any part of the setup procedures, remove the monitor from the operation until qualified service personnel have corrected the situation. Patient safety: If a sensor is damaged in any way, discontinue use immediately. As with all medical equipment, carefully rout patient cabling to reduce the possibility of patient entanglement or strangulation. The TOSCA 500 tcPCO2 monitoring is not a device for blood gas analysis. It is recommended that, prior to any decisive therapeutic measures, an accurate arterial blood gas analysis is carried out. The use of the TOSCA 500 monitoring system cannot replace a permanent supervision of the patient by medical personnel. The TOSCA 500 pulse oximetry should NOT be used as an apnea monitor. The pulse oximetry should be considered an early warning device. As a
trend towards patient’s deoxygenation is indicated by pulse oximetry, blood samples should be analyzed by a laboratory co-oximeter to completely understand the patient’s condition. Interfering substances to SpO2 measurement: Carboxyhemoglobin may erroneously increase readings. The level of increase is approximately equal to the amount of carboxyhemoglobin present. Dyes, or any substance containing dyes, that change usual arterial pigmentation may cause erroneous readings. CAUTIONS Certain types of mobile telecommunication equipment could potentially interfere with equipment operation. Mobile telecommunication equipment should not be used within five meters of the monitoring equipment. This unit needs special precautions regarding EMC and needs to be installed and put into service according to the EMC information provided in the section 13 of this document. The equipment can be used during defibrillation, but the readings may be inaccurate during defibrillation, but will rapidly recover. When this equipment is used with a defibrillator, the user must precisely follow the instructions given in the defibrillator operating manual. To ensure protection of patient, operator and equipment from the effects of defibrillation and diathermy / electro surgery, cables manufactured by Linde Medical Sensors must be used. The equipment is protected against electrostatic discharge. The tcPCO2 display may be temporarily affected during discharge to chassis ground but will rapidly recover. For use during electro surgery the monitor, sensor and their cables must be physically separated from the electrosurgical equipment. The sensor must not be placed in the electrical pathway between cutting and counter electrode. Electro surgery will produce, at most, a minimal transient disturbance in the reading and will not affect the system calibration. If any function fails to operate correctly, consult an authorized service technician. When the equipment has been wetted accidentally it must be wiped dry externally and allowed to dry thoroughly before further use.
The Linde TOSCA 500 system is used for noninvasive monitoring of transcutaneous PCO2 (tcPCO2), functional oxygen saturation SpO2 and pulse rate, using a single sensor applied to the ear lobe in adult and pediatric patients.
TOSCA 500 monitor
The Linde TOSCA 500 system combines the best technologies of Linde transcutanous PCO2 with the Masimo SET® for SpO2 and pulse rate. The integrated calibration unit allows a fully automatic calibration and provides also a storage facility for the sensor. These features ensure that the sensor is always READY TO USE.
High quality standard TOSCA 500 is a compact and portable unit which operates by AC power and, for transport, by internal or external (e.g. car) battery. The monitor is microprocessor based and incorporates most advanced circuit design and user friendly software. The monitor is equipped with an extensive built-in self-check program ensuring a reliable and safe system performance.
Easy operation All settings and adjustments are made with a few function and control keys which are arranged in a straightforward and easily understandable manner.
Display The values of the three parameters tcPCO2, SpO2 and PR (pulse rate) are displayed on three clearly visible, bright LED windows. Additionally the trend can be displayed on the middle screen during patient monitoring. Together with the pulse rate value, a bar graph indicates the pulse waveform. In the center, a wide backlit LCD window serves to guide the user through the selection of parameters and to show text messages during alarm and fault situations. Four different display modes are available during operation: "Status", "Trend", "Plethysmogram" and "Heating power".
Patient safety The monitor fulfills the requirements of the Medical Device Directive 93/42/EEC. The inputs are fully isolated and filtered so that the monitor can be used with defibrillators and diathermy apparatus. Particular emphasis has been placed on the reliability of the sensor heating circuitry, which incorporates full te mperature control redundancy based on the proven dual thermistor approach. In order to prevent excessively long exposure of the sensor to the skin, a built-in site timer alerts the user when the preset application time has elapsed.
Storage of patient results The TOSCA 500 monitor incorporates a memory to store automatically all measured patient results for the last 72 hours using the FIFO (First In First Out) principle. Data are stored whenever values are displayed e.g. during patient monitoring. The memory will indicate blank
spaces for those time intervals in which no values are displayed e.g. while the sensor is placed in the calibration/storage chamber or while the monitor is turned off. The results can be downloaded to a printer or to a personal computer (PC).
Communication interface The TOSCA 500 monitor is equipped with a "Parallel Interface" and a "Systems Connector". The "Parallel Interface" is used for connecting a printer. The "Systems Connector" allows the connection to any patient monitoring system or to a computer. The protocol is selectable through the menu of the system parameters.
TOSCA sensor 92
The TOSCA sensor 92 employs the most advanced technology for combining two measurement methods. It determines transcutaneous PCO2 , oxygen saturation and pulse rate at the ear lobe. The sensor is heated to a constant temperature to achieve local arterialization of the skin, which is required for the transcutaneous measurement. The increased perfusion of the ear lobe produced in this way serves also to augment the pulse oximetric signal strength.
Sensor memory The TOSCA sensor contains an electronic memory to store PCO2 calibration values and other relevant sensor data (such as date of last sensor preparation or light intensities of LEDs). By evaluating these data on the monitor, an irregularity of the sensor characteristics or the need for a new sensor preparation is detected. In addition, the memory feature allows the operator to change the sensor from one monitor to another without the need for a new preparation.
Easy remembraning For fast and easy new preparation ("remembraning") of the sensor, a convenient "fit & click" preparator is provided which allows a reproducible sensor preparation within seconds. A message is displayed when the sensor needs to be remembraned. This is required once every 14 days. A specially designed thin golden plate protects the sensor measurement surface from mechanical damage to the membrane. This enhances the function time of the sensor and ensures a high reliability of the measurement.
Concept of operation
Principle of measurement Transcutaneous measurement of PCO2 makes use of the fact that carbon dioxide gas is able to diffuse through body tissue and skin and can be detected by a sensor at the skin surface. By warming up the sensor, a local hyperemia is induced, which increases the supply of arterial blood to the dermal capillary bed below the sensor.
The transcutaneous PCO2 value (tcPCO2) has to be interpreted primarly as the PCO2 partial pressure prevailing at the level of the arterialized skin tissue. In general, this value correlates well with the corresponding arterial PCO2 partial pressure. The PCO2 part of the TOSCA sensor consists of a Stow-Severinghaus type electrode. PCO2 is measured by determining the pH of an electrolyte solution. A change in pH is proportional to the logarithm of the PCO2 change. The pH is determined by measuring the potential between a miniature glass pH electrode and an Ag/AgCl reference electrode. The electrolyte is provided within a thin hydrophilic spacer, which is placed over the sensor surface and is coupled to the skin via a highly gas permeable hydrophobic membrane.The membrane is protected with a thin golden plate to eliminate any mechanical damage to the measuring site. The sensor is calibrated in a gas of a known CO2 concentration. The slope (change of potential with PCO2) is preset in the sensor memory. The electrical power needed to heat the sensor to a constant temperature depends to a small fraction on the local tissue perfusion. At constant ambient temperature, deviations of the heating power from a stored reference value ("relative heating power") may indicate changes in perfusion.
PCO2 Temperature corrections In general, a high correlation between transcutaneous PCO2 (tcPCO2) and arterial PCO2 (PaCO2) is found in patients of all ages. However, due to the elevated temperature of the sensor, the transcutaneous PCO2 is higher than the arterial value. It has therefore become a common practice to apply a correction to the transcutaneous value to provide a monitor readout which corresponds as close as possible to arterial PCO2. The shift of tcPCO2 towards higher values is attributed to two main factors. First, the elevated temperature raises local blood and tissue PCO2 by approx. 4.5% /°C (‘anaerobic‘ factor). Secondly, the living epidermal cells produce carbon dioxide, which contributes to the capillary CO2 level by a constant amount (metabolic constant). This metabolic contribution may change with age, skin thickness and other variables. A generally accepted estimation is that skin metabolism raises the transcutaneous PCO2 by approx. 5 mmHg. Taking into account both effects, the relationship between tcPCO2 and PaCO2 can be expressed by the following equation: tcPCO2 = 10exp [0.019 (T-37)] ⋅ PaCO2 + 5mmHg or tcPCO2 = F T ⋅ PaCO2 + C M whereby: FT = temperature correction factor CM = metabolic constant The theoretical basis of this algorithm is described by J. W. Severinghaus in his paper "Transcutaneous blood gas analysis", Respiratory Care 1982, 27(2): 152-159. The correction of tcPCO2 is combined with the sensor calibration, i.e. the sensor is calibrated to a value which is adjusted to compensate for both effects. The correction parameters F T and C M can be selected by the operator as described in section 7.2.3. In the AUTO mode, F T is automatically adjusted to the sensor temperature according to the above equation. In this case, it is recommended to use C M = 5 mmHg.
Alternatively, specific values for both correction parameters may be used (for example F T = 1.5 and C M = 0 at a sensor temperature of 42°C). In this case, F T is not automatically adjusted to the sensor temperature. When selecting F T = 1 and C M = 0, no correction is applied. For calculating the PCO2 calibration values, the barometric pressure is taken into account in both cases.
PCO2 "In vivo" correction In addition to the temperature correction, the tcPCO2 value can be adjusted based on the result of an arterial blood gas analysis. This possibility is provided for special applications or when a systematic difference between tcPCO2 and PaCO2 is clearly established by several arterial blood gas measurements. When this correction is made, it must be checked periodically and adapted in cases of changes.
Oxygen saturation SpO2
General description Pulse oximetry is a continuous and non-invasive method of measuring the level of arterial oxygen saturation in blood. The measurement is taken by attaching the sensor at the ear lobe of the patient. The sensor collects signal data from the patient and sends it to the monitor. The monitor displays the calculated data in three ways: – as a percent value for arterial oxygen saturation (SpO2 – as a pulse rate (PR) and – as a plethysmographic waveform
Principle of measurement Pulse oximetry is governed by the following principles: – Oxyhemoglobin (oxygenated blood) and deoxyhemoglobin (non-oxygenated blood) differ in their absorption of red and infrared light (spectrophotometry). – The amount of arterial blood in tissue changes with the pulse (photoplethysography). Therefore, the amount of light absorbed by the varying quantities of arterial blood changes as well. The TOSCA 500 uses a two -wavelength pulsatile system to distinguish between oxygenated and deoxygenated blood. Signal data is obtained by passing red (658 nm wavelength) and infrared (880 nm wavelength) light through a capillary bed (the ear lobe) and measuring changes inlight absorption during the pulsatile cycle. The TOSCA sensor 92 utilizes red and infrared light-emitting diodes (LEDs) that pass light through the site to a photodiode (photodetector). The photodetector receives the light, converts it into an electronic signal and sends it to the TOSCA 500 monitor for calculation. TOSCA sensor 92
Once the TOSCA monitor receives the signal from the sensor, it utilizes Masimo SET signal extraction technology for calculation of the patient’s functional oxygen saturation and pulse rate.
Functional vs. fractional saturation The TOSCA 500 measures and displays functional saturation: the amount of oxygenated hemoglobin expressed as a percentage of the hemoglobin that can transport oxygen. The TOSCA does not measure fractional saturation: oxygenated hemoglobin expressed as a percentage of all measured hemoglobin, including measured dysfunctional hemoglobin such as carboxyhemoglobin or methemoglobin. To convert fractional saturation to functional saturation, the fractional saturation measurements must be converted according to: Functional saturation =
100 −(% carboxyhem oglobin + % methemoglo bin)
Masimo SET® The TOSCA 500 system incorporates the Masimo Signal Extraction Technology for SpO2 measurement. The Masimo SET’s signal processing differs from conventional pulse oximeters. Conventional pulse oximeters assume that arterial blood is the only blood moving (pulsating) in the measurement site. During patient motion, however, the non-arterial blood also moves, which causes conventional pulse oximeters to read low values because they cannot distinguish between the arterial and venous blood movement (sometimes referred to as noise). Masimo SET utilizes parallel engines and adaptive digital filtering. Adaptive filters are powerful because they are able to adapt the varying physiologic signals and/or noise and separate them by looking at the whole signal and breaking it down to its fundamental components. The Masimo SET signal processing algorithm, Discrete Saturation Transform (DST), reliably identifies the noise, isolates it and, using adaptive filters, cancels it. It then reports the true arterial oxygen saturation for display on the monitor. Although venous saturation is not displayed, TOSCA 500 with Masimo SET measures and calculates the values of both the arterial and venous oxygen saturation. This is referred to as stereo saturation measurement, since it separates the arterial from the venous information instead of mixing them together as is done with conventional pulse oximeters. The pulse oximetric signal strength (Perfusion Index "PI") is displayed on the status and plethysmogram screen. The Perfusion Index "PI” is a qualitative indicator of tissue perfusion and the value is defined as the ratio of the amplitudes of the pulsatile and the non-pulsatile infrared signals, expressed in percent.
The need to monitor simultaneously carbon dioxide tension and arterial oxygen saturation exists in various fields of medicine, such as: – anesthesia / preoperative monitoring – intensive / critical care – diagnostic procedures such as bronchoscopy – sleep studies and apnea testing – exercise testing – pulmonary stress testing – respiratory research Monitoring of transcutaneous PCO2 and SpO2 with TOSCA 500 is of particular value in following up the immediate effect of any therapeutic measures which have a direct or indirect influence on the patient’s degree of oxygenation and ventilatory efficiency. The information on trends provided by TOSCA 500 permits an instantaneous qualitative assessment of the effect of the therapy. Monitoring with TOSCA 500 allows, in general, a more rapid detection of hypoxemic events and of critically high or low levels of carbon dioxide tension, as compared to conventional arterial blood gas analysis. Also, it can be of assistance in deciding the timing of arterial blood gas sampling, and may therefore considerably reduce the frequency of sampling.
Points to be regarded during monitoring
Monitoring during surgery For use during electro surgery the monitor, sensor and their cables are to be physically separated from the electrosurgical equipment. The sensor must not be placed in the electrical pathway between cutting and counter electrode. Electro surgery will produce, at most, a minimal transient disturbance in the reading but it will not affect the system calibration.
Transcutaneous PCO2 measurement
Recommended sensor temperature and application time The quality of the correlation between arterial and transcutaneous PCO2 has been found to be similar at sensor temperatures between 41°C and 45°C. With decreasing sensor temperature, however, the in vivo response time to rapid arterial PCO2 changes increases. It is recommended to use a sensor temperature of 42°C, which has been found to be tolerated by the skin for up to twelve hours. When higher sensor temperature is used, the exposure time should be shorter (see specification, section 12.2).
Note The sensitivity of the skin to heat may not only be diffe rent from patient to patient, but may also vary in an individual patient. In particular, any clinical situation resulting in reduced skin blood flow will increase the sensitivity to heat and the risk of skin burn. Also, excessive mechanical pressure against the sensor will provoke such a condition.
Arterialization The TOSCA 500 provides the feature to obtain a stable value of PCO2 very shortly after sensor application. Reliable transcutaneous measurement requires good gas diffusion through the body tissue and skin. This is achieved by warming up the skin with the heated TOSCA sensor. This process, the arterialization of the capillary blood flow, is accelerated by increased temperature. QUICKSTART increases automatically the preset sensor temperature of 2°C (maximum sensor temperature is 44°C) during the initial 20 minutes after sensor application. This provides a fast stable PCO2 value. The following options can be selected in the parameter settings of TOSCA 500: – QUICKSTART is the best method to obtain a fast reliable PCO2 reading. It is recommended for “spot checks“ and for patients with low perfusion e.g. hypothermic patients, patients with vasoconstrictions, circulatory centralization (shock). – Normal is for patients in normal hermodynamic stable conditions. See section 7.2.2 for parameter settings.
tcPCO2 in anaesthesia There are no measurable interferences in nitrous oxide, halothane, isoflurane and enflurane with the transcutaneous PCO2 measurement (see section 12.3)
SpO 2 measurement
At high saturation, the oxyhemoglobin dissociation curve becomes almost flat, so that small changes in the measured SpO2 represent large changes in PO2. Pulse oximetry is therefore of limited use in quantitating the degree of hyperoxemia. The shape of the oxyhemoglobin dissociation curve can differ from patient to patient. Therefore, the SpO2 alarm limits should be selected specifically for each patient after comparing SpO2 readings with arterial PO2 data obtained by laboratory analysis. The stability of the SpO2 readings may be a good indicator of signal validity. Although stability is a relative term, experience will provide a good feeling for changes that are artifactual or physiological and the speed, timing, and behavior of each. The stability of the readings over time is affected by the averaging mode being used. The longer the averaging time, the more stable the readings tend to be become. This is due to a dampened response as the signal is averaged over a longer period of time than shorter average times. However, longer average times delay the response of the oximeter and reduce the measured variations of SpO2 and PR.
Pulse rate values The pulse rate display on TOSCA 500 may differ slightly from the heart rate displayed on the ECG monitor due to the differences in averaging times. There may also be a discrepancy between cardiac electrical activity and peripheral arterial pulsation. Significant differences may indicate a problem with the signal quality due to physiological changes in the patient or
one of the instruments or application of the sensor. The pulsation from intraaortic balloon support can be additive to the pulse rate displayed on TOSCA 500.
Signal IQ The Signal IQ is a Signal Identification and Quality indicator and a special feature of the Masimo SET technology and displayed on the plethysmogram display of the TOSCA 500. The signal IQ is a visual indicator of the plethysmogram signal quality and an alert when the displayed SpO2 value is not based on adequate signal quality. The signal IQ can be used to identify the occurrence of a patient’s pulse and the associated signal quality of the measurement. With motion, the plethysmographic waveform is often distorted and may be obscured by artifact. The Signal IQ, shown as a vertical line, coincides with the peak of an arterial pulsation. Even with a plethysmographic waveform obscured by artifact, the TOSCA 500 locates the arterial pulsation. The pulse tone (when enabled) coincides with the vertical line of the Signal IQ. The height of the vertical line of the signal IQ indicates the quality of the measured signal. – High vertical bar indicates a good quality signal – Low vertical bar indicates a low quality signal When the signal quality is very low the accuracy of the SpO2 measurement may be comprised, and a “Low Signal IQ” message is displayed. When this message appears proceed with caution and check the following: – Assess the patient – Check the sensor and ensure proper sensor application. – Determine if an extreme change in the patient’s physiology and blood flow at the ear lobe occurred, (e.g. an inflated blood pressure cuff, severe hypotension, vasoconstriction in response to hypothermia, medication, or a spell of Rynaud’s syndrome). After performing the above and if the “Low Signal IQ” message is displayed frequently or continuously it may be considered to verify the oxygen saturation value by a co-oximetry analysis.
Low perfusion (PI) The Perfusion Index (PI) is a relative assessment of the pulse strength at the monitoring site. The PI is defined as the ratio of the amplitudes of the pulsatile (AC) and the non-pulsatile (DC) infrared signals, expressed in percent. The TOSCA 500 displays this value on the status display. The PI is a relative number and varies from patient to patient, as physiologic conditions vary. A low value indicates weak pulse strength and a high value strong pulse strength. The message of “Low Perfusion Index” is displayed when there are very low amplitude arterial pulsations . CAUTION: If the message “Low Perfusion Index“ is frequently displayed, assess the patient and, if indicated, verify oxygenation status through other means. If the accuracy of any measurement does not seem reasonable, first check the patient’s vital signs by alternate means and check the monitor for proper functioning.
FastSat The FastSat enables rapid tracking of arterial oxygen saturation changes. It is a special feature of the Masimo SET technology. Rapid changes in arterial oxygen saturation are typically “smoothed out“ by pulse oximeter averaging algorithm, yielding blunted readings. FastSat captures and reports these rapid oxygen saturation changes. FastSat feature is automatically enables when an averaging of 2 or 4 seconds is selected; see section 7.2.4 for parameter definition.
Sensitivity The sensitivity level enables the clinician to tailor the response of the TOSCA 500 to the needs of the particular patient situation. The sensitivity level can be selected in the parameter menu of TOSCA 500 and includes the options of: APOD, Normal and Max. The APOD (Adaptive Probe Off Detection) technology is a special feature of the Masimo SET technology. It is a suite of complex and powerful signal processing algorithm that carefully analyzes the incoming signal to determine if the TOSCA sensor is on or off the patient. The following sensitivity levels can be selected in the parameter settings of TOSCA 500: – APOD is the least sensitive in picking up on patients with low perfusion. – Normal sensitivity provides the best combination of sensitivity and sensor-off detection performance and is recommended for the majority of patients – Max sensitivity is reserved for the sickest patients, where obtaining a reading is most difficult. Max sensitivity is designed to interpret and display data for even the weakest of signals, and is recommended during procedures and when clinician and patient contact is continuous. If low perfusion combined with movement inhibits the TOSCA 500 monitor from readings, switch from APOD to Normal or Max sensitivity, see section 7.2.4 for parameter settings.
Transcutaneous PCO2 measurement
Under the following clinical situations there is, according to current knowledge, limited or no correlation between transcutaneous and arterial PCO2: – profound peripheral vasoconstriction – circulatory centralization (shock) – hypothermia during surgery – use of vasoactive drugs The Perfusion Index "PI” value may be used to qualify the above listed situations. (Reference: "Use of a peripheral perfusion index derived from the pulse oximetry signal as a non invasive indicator of perfusion", Critical Care Medicine 2002, Vol. 30, No 6, 1210-1213). – skin anomalies – skin edema It should be regarded that transient skin edema at the ear lobe may occur during the early recovery phase after anesthesia, or when a patient is in the Trendelenburg position.
TOSCA 500 3.3.2
CLINICAL APPLICATION SpO 2 measurement
Like the transcutaneous technique, pulse oximetry relies on the existence of intact transport mechanisms of arterial blood to the measurement site. Whenever such transport is impaired to the extent that a sufficiently large pulse signal cannot be detected, SpO2 monitoring is no longer feasible. Such a condition may occur in cases of circulatory centralization (shock), peripheral vasoconstriction, venous congestion or generally at low local tissue perfusion. Furthermore, the pulse oximetric measurement may not be valid under the following conditions: – excessive ambient light – severe electrical interference – excessive patient movement (such as shivering) – significant levels of dysfunctional hemoglobin (e.g. COHb and metHb) – presence of intravascular dyes – skin pigmentation – venous pulsation at the frequency of the patient’s arterial pulse – very low hemoglobin levels
Warning The TOSCA 500 monitoring system is not a device for blood gas analysis. It is recommended that, prior to any decisive therapeutic measures, an accurate arterial blood gas analysis is carried out. The use of the TOSCA 500 monitoring system cannot replace a permanent supervision of the patient by medical personnel.