Accutorr PLUS Service Manual Rev B Dec 2008

Table of Contents

Contents... vii Foreword ... vii Notes and Precautions ... viii Notes... ix Precautions ... x Theory of Operation... 1 - 1 Major Functional Blocks of the Accutorr Plus... 1 - 2 CPU/NIBP Module Assembly with LCD Display... 1 - 3 Software Overview ... 1 - 3 CPU Hardware Controls ... 1 - 4 NIBP Hardware functions ... 1 - 4 Main pressure transducer circuitry ... 1 - 4 Over pressure transducer circuitry ... 1 - 4 Five A/D channels ... 1 - 5 Pulse Channel Filter ... 1 - 5 Inflation Pump ... 1 - 5 Bleed Valve ... 1 - 5 Dump Valve ... 1 - 5 Cuff Inflation Requirements ... 1 - 5 Pulse Acquisition Requirements ... 1 - 6 Artifact Rejection Requirements ... 1 - 6 Parameter determination Requirements ... 1 - 6 Major Hardware Components ... 1 - 6 CPU ... 1 - 6 Flash Memory ... 1 - 6 Battery Backed Up Static RAM ... 1 - 6 Nonvolatile RAM ... 1 - 6 Micromanager ... 1 - 7 Battery Backup Voltage Regulator Circuitry ... 1 - 7 Real Time Clock ... 1 - 7 Recorder Interface ... 1 - 7 Communication Block ... 1 - 8 Backlight LED Driver ... 1 - 8 LCD Trend Display ... 1 - 8 Temperature Interface ... 1 - 9 SpO2 Interface ... 1 - 9 SpO2 Processor Circuit Boards ... 1 - 11 SpO2 General Theory Of Operation... 1 - 11 Nellcor® Nell-3 SpO2 Circuit Board Theory of Operation ... 1 - 11 Nellcor® Nell-3 Interface Board Theory of Operation ... 1 - 12 Masimo SET® Technology... 1 - 12 Masimo® Interface Board Theory of Operation ... 1 - 12 Main Power Supply... 1 - 14 Description ... 1 - 14 Power Supply Output Voltages... 1 - 14 Lithium Ion Battery and Charger ... 1 - 14 LED and Tone Module... 1 - 16

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Table of Contents

Keypad Control ... 1 - 17 Specifications... 2 - 1 Performance Specifications... 2 - 1 NIBP Measurement Cycle Time ... 2 - 1 Pulse Rate ... 2 - 2 Maximum Cuff Pressure ... 2 - 2 Inflation Source... 2 - 2 Leak Rate ... 2 - 2 Cuff Vent Rate ... 2 - 2 Temperature (Predictive) ... 2 - 2 Nellcor® SpO2 ... 2 - 3 Masimo® SpO2 ... 2 - 3 Battery ... 2 - 5 Real-Time Clock ... 2 - 5 Safety Characteristics... 2 - 6 Risk (Leakage) Currents ... 2 - 6 Dielectric Withstand ... 2 - 6 Ground Resistance ... 2 - 6 Type of Protection Against Electric Shock... 2 - 6 Degree of Protection Against Electric Shock ... 2 - 6 Physical Characteristics... 2 - 7 Environmental Characteristics ... 2 - 7 Electrical Ratings ... 2 - 8 Agency Compliance ... 2 - 8 Electromagnetic Compatibility ... 2 - 9 Repair Information ... 3 - 1 Introduction ... 3 - 1 Safety Precautions ... 3 - 2 General Troubleshooting Guidelines ... 3 - 3 Troubleshooting Tips ... 3 - 3 Exchange Program ... 3 - 3 Test Equipment Required... 3 - 4 Troubleshooting (Problem Isolation) ... 3 - 5 Error Codes ... 3 - 5 Isolating the Problem, System Level ... 3 - 6 Isolating the Problem within the Main Unit... 3 - 7 Isolating the Problems with Optional Accessory Modules ... 3 - 7 Clinical Issues with AccuTemp IR Ear Thermometer Applications... 3 - 7 Multiple Temperature Measurements ... 3 - 7 How the AccuTemp IR Measures Arterial Temperature (Adults/Pediatrics) ... 3 - 8 Troubleshooting ... 3 - 9 Maintenance ... 3 - 9 Disassembly Instructions... 3 - 10 Removal of the Rear Housing ... 3 - 10 Removal of the Front Bezel ... 3 - 10 Removal of the Keyboard Assembly ... 3 - 10 Removal of the LED/Tone board... 3 - 10

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Removal of the CPU / NIBP board ... 3 - 11 Removal of the Power Supply Assembly ... 3 - 12 Removal of the LCD Display (Advanced Model) ... 3 - 13 Removal and replacement of the Internal Li-Ion Battery ... 3 - 13 Removal of the AC Input Receptacle Assembly ... 3 - 13 Thermal Printer (optional module) ... 3 - 13 Thermometer, Predictive (optional module) ... 3 - 13 AccuTemp IR, Infrared Thermometer (optional module) ... 3 - 14 AccuTemp IR Mounting Cradle ... 3 - 14 Interconnect Cables Run List ... 3 - 15 Interface Specifications, Connectors and Functions. ... 3 - 15 Connector to LED / Tone PCB, J-2 ... 3 - 15 Power Supply Header, J-502 ... 3 - 17 J-2 Keypad Connector ... 3 - 17 J-4 Speaker Connector ... 3 - 18 Recorder Connector, J-5 ... 3 - 18 Thermometer Connector, J-4 ... 3 - 19 SpO2 Connector, J-7 ... 3 - 19 NIBP Pump Connector, J-505 ... 3 - 20 LED Backlight Connector, J-651 ... 3 - 20 Communication Connector, J-603 ... 3 - 20 LCD Connector, J-8 ... 3 - 20 Power Supply Connectors... 3 - 21 AC input connector, J-2 ... 3 - 21 DC output connector, J-3 ... 3 - 21 Battery connector, J-4 ... 3 - 22 Replacement Parts and Isometric Drawings... 4 - 1 Introduction ... 4 - 1 Available Replacement Parts And Sub-Assemblies... 4 - 1 Product Variations And Options ... 4 - 1 Exchange Program ... 4 - 2 Replacement Parts Pricing Information ... 4 - 2 Ordering Information ... 4 - 2 Isometric Drawings and Parts Lists... 4 - 3 Accessory Modules and Mounting Parts Lists... 4 - 10 Recorder Module Replacement Parts List ... 4 - 10 Predictive Temperature Module Replacement Parts List ... 4 - 10 Universal Rolling Stand (P/N ACCTROLLSTD, Assembly Parts List) ... 4 - 11 Mounting Options ... 4 - 12 Calibration ... 5 - 1 Introduction ... 5 - 2 Status and Error Code Table ... 5 - 2 Error Codes ... 5 - 2 Precautions And Guidelines ... 5 - 4 Test Equipment And Special Tools Required ... 5 - 4 Power-up Sequence, Internal Testing... 5 - 4 Service Diagnostics ... 5 - 5

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Introduction (Hidden Key)... 5 - 5 Software Version Test (0a, 0b) ... 5 - 6 Keypad Test ... 5 - 7 LED Test (2a, 2b)... 5 - 8 Communication Test (3a, 3b)... 5 - 8 Recorder Test (4) ... 5 - 8 Pump Test (5)... 5 - 9 Bleed Rate Test (6a, 6b) ... 5 - 9 Leak Test (7) ... 5 - 10 Over Pressure Test (8a, 8b, 8c) ... 5 - 10 Pulse Channel DC Offset Test (9a, 9b, 9c) ... 5 - 11 Pulse Channel Average Noise Test (10a, 10b, 10c)... 5 - 11 Main Pressure Transducer Verification Test (11a, 11b, 11c) ... 5 - 11 Verification of Accutorr Plus Pneumatic Performance using an NIBP Simulator (11d)... 5 - 12 Overpressure Transducer Verification <12c, 12a, 12b> ... 5 - 13 Main Pressure Transducer Calibration... 5 - 14 Overpressure Transducer Calibration ... 5 - 15 Predictive Thermometer Verification And Calibration... 5 - 16 Water Bath Method ... 5 - 16 Temperature Verification Test, Infrared Thermometer (Applicable Only To Units Equipped With A Temperature Option) ... 5 - 16 Low Battery Sensing ... 5 - 17 Setting the Current Time ... 5 - 18 NIBP Normal Operation... 5 - 19 Trend Memory Initialization ... 5 - 19 SpO2 Normal Operation (Accutorr Plus model with SpO2) ... 5 - 20 Preventive Maintenance... 6 - 1 Introduction ... 6 - 1 Limitations Of Physiological Simulators ... 6 - 1 Preventive Maintenance Schedule ... 6 - 2 Mechanical and Physical Visual Inspection (One Year Interval) ... 6 - 2 Electrical Safety and Performance Checks (One Year Interval)... 6 - 2

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Contents

Introduction

Contents 1.0 Theory of Operation ... 1-1 2.0 Specifications ... 2-1 3.0 Repair Information ... 3-1 4.0 Replacement Parts and Isometric Drawings ... 4-1 5.0 Calibration ... 5-1 6.0 Preventive Maintenance ... 6-1 On the first page of each chapter a table of contents for that chapter is provided. This is a Service Manual for the Accutorr Plus monitor. There are no Operating Instructions in this manual. Complete operating instructions and listing of available accessories are published in the Accutorr Plus Operating Instructions- P/N 0070-00-0692-02 (English) and P/N 0070-00-0695 (international languages).

Foreword This Service Manual (P/N 0070-00-0691) is intended as a guide, for technically qualified personnel, to use during repair and calibration procedures for the Accutorr Plus (part number 0998-00-0444-9XX). Use this Accutorr Plus Service Manual ONLY for the monitor part numbers listed below. This manual provides specific information that may not be applicable to other part numbers. The part number (P/N) and serial number are necessary for positive identification of the correct parts. They are located on the rear panel label of the Accutorr Plus unit.

MONITOR PART NUMBER (P/N)

MONITOR CONFIGURATION

0998-00-0444-91A

Basic (NIBP only) (IEC, English)

0998-00-0444-91G

Basic (NIBP only) (IEC, German)

0998-00-0444-91P

Basic (NIBP only) (IEC, Spanish)

0998-00-0444-91F

Basic (NIBP only) (IEC, French)

0998-00-0444-91T

Basic (NIBP only) (IEC, Italian)

0998-00-0444-93A

Advanced (Nellcor®) (IEC, English)

0998-00-0444-93G

Advanced (Nellcor®) (IEC, German)

0998-00-0444-93P

Advanced (Nellcor®) (IEC, Spanish)

0998-00-0444-93F

Advanced (Nellcor®) (IEC, French)

0998-00-0444-93T

Advanced (Nellcor®) (IEC, Italian)

0998-00-0444-94A

Advanced (Masimo®) (IEC, English)

0998-00-0444-94G

Advanced (Masimo®) (IEC, German)

0998-00-0444-94P

Advanced (Masimo®) (IEC, Spanish)

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Introduction

Notes and Precautions

MONITOR PART NUMBER (P/N)

MONITOR CONFIGURATION

0998-00-0444-94F

Advanced (Masimo®) (IEC, French)

0998-00-0444-94T

Advanced (Masimo®) (IEC, Italian)

Notes and Precautions NOTES are a general information statement concerning the Accutorr Plus. A CAUTION is provided to alert the user to use special care necessary for the safe and effective use of the device. They may include actions to be taken to avoid effects on patients or users that may not be potentially life threatening or result in serious injury, but about which the user should be aware. Cautions are also provided to alert the user to adverse effects on this device of use or misuse and the care necessary to avoid such effects. Please read and adhere to all notes and precautions listed here and in the appropriate areas throughout this manual.

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Notes

Introduction

Notes NOTE:

See the serial and product number label on the rear panel of the unit for part number identification. This manual also includes information on the optional Recorder and Predictive Temperature modules and Infrared Temperature module.

NOTE:

This manual does not provide operating instructions. Consult the Operating Instructions Manual for proper operation of this monitor.

NOTE:

Unauthorized servicing may void the remainder of the warranty. Check with the factory or with a local authorized representative to determine the warranty status of a particular instrument.

NOTE:

Do not change Room Number and /or Bed Letter on the Accutorr Plus during the transmission of temperature data.

NOTE:

The AccuTemp IR thermometer should be at room temperature when it is used. If it has been in a very warm or very cold environment it may need time for the thermometer temperature to equalize to ambient temperature.

NOTE:

Special care should be taken to insure that the front panel and glare screen are not scratched.

NOTE:

New batteries are shipped in a discharged state for safety reasons. A new battery must be charged for 4 hours for Li-Ion before first use. The monitor may be used with AC mains power during the charge cycle but battery operation could be limited during this time.

NOTE:

Mindray DS USA, Inc. maintains a policy of continuous development for product improvement and reserves the right to change materials, specifications, and prices without notice.

NOTE:

When replacing a Keyboard, you must replace the Graphic Panel.

NOTE:

Monitors with Nellcor and Masimo SpO2 do not report SpO2 Runtime and Boot Software Versions.

NOTE:

The Accutorr Plus always displays time in a 24 hour format.

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Introduction

Precautions

Precautions CAUTION:

Li-lon batteries used in this device may present a risk of fire or chemical burn if mistreated. Do not disassemble, heat above 100°C (212°F), or incinerate. Replace battery with P/N: 0146-000069 only. Use of another battery may present a risk of fire or explosion.

CAUTION:

Dispose of used battery properly. Keep away from children. Do not disassemble and do not dispose of in fire.

CAUTION:

Soldering and solder removal equipment must be low voltage operated and grounded to avoid static charge and stray current induced component damage. Maximum wattage: 25 W.

CAUTION:

The Inside Of This Instrument Contains Static Sensitive Components. Use correct static protection safeguards.

This publication may have been updated to reflect product design changes and/or manual improvements. This manual is correct to the best of our knowledge at the time of publication and reflects the product variations shown in this manual. You may contact Technical Support to confirm that the manual is applicable for your unit. Updated manuals are available for sale.

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1.0

Theory of Operation

1.1 Major Functional Blocks of the Accutorr Plus ... 1-2 1.2 CPU/NIBP Module Assembly with LCD Display ... 1-3 1.3 SpO2 Processor Circuit Boards ... 1-11 1.4 Main Power Supply ... 1-14 1.5 LED and Tone Module ... 1-16 This section of the manual explains the basic architecture of the Accutorr Plus. It is an overview, not a detailed circuit analysis. It is intended to be a tool, that if used properly, will lead to an understanding of the functions executed by a major functional block, and thus enabling a logical isolation and resolution of malfunctions. The Accutorr Plus is offered in many functional configurations, including the options licensed and manufactured by third parties. The third party circuits will be treated solely as “black box” devices, with only the relevant input, output and power sources described. The Theory of Operation section describes only the highest configuration level. Units built with fewer or different options may not use all of the capabilities of the Accutorr Plus, yet the over-all theories will remain constant.

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Major Functional Blocks of the Accutorr Plus

1.1

1-2

Theory of Operation

Major Functional Blocks of the Accutorr Plus •

CPU/NIBP Module Assembly with LCD Display

•

Interface and SpO2 Processor Board

•

Main Power Supply and Battery Charger Assembly

•

LED/Tone Module Assembly

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Theory of Operation

1.2

CPU/NIBP Module Assembly with LCD Display

CPU/NIBP Module Assembly with LCD Display The Accutorr Plus CPU/NIBP module controls the functions of the NIBP, temperature probes, and SpO2 module; transmits output data to the recorder; and provides a serial I/O port connection for PC communication. The CPU/NIBP module distributes power from the power supply, which includes power and control signals to the LED/Tone module, to the remaining components of the system such as the recorder and SpO2 modules. The CPU/NIBP module also supplies separate power to the LED backlight and provides trend data to the display. The CPU/NIBP circuit board is comprised of both software and hardware. The following is a summary of the software control exercised and the major hardware affected. This is for informational purposes only, and both software and hardware controls may be changed at any time without notice.

1.2.1

Software Overview The software performs the following functions: 1. Initializes hardware and software modules • • •

Microcontroller ports and communication (serial) interfaces Software entry points and variables Read configuration from NVRAM

2. Performs power up diagnostic •

Microcontroller, FLASH, and STATIC RAM test

3. Performs NIBP functions • • • • • • • • • • • • • • • • •

Accutorr Plus Service Manual

Start measurement Repeat measurement Over pressure limit Enter or exit test mode Abort measurement Enter or exit calibration mode Update alarm limits Report alarm status Report data Determine inflation pressure Perform controlled cuff deflation Monitor DC and AC pressure and acquire pulsations Reject artifacts Decide on termination point and exhaust cuff pressure Smooth pulsation data Determine systolic, mean, diastolic pressure and heart rate Check alarm conditions

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CPU/NIBP Module Assembly with LCD Display

Theory of Operation

4. Transmits/Receives data to/from Infrared/Predictive Temperature modules 5. Manages Recorder functions 6. Manages Keypad interface 7. Provides RS232 communication to PC for software download 8. Supports Service Diagnostics 9. Supports Nurse Call feature 10. Checks error conditions • •

Maintain watchdog timer Run-time diagnostic

11. Transmits/Receives data to/from SpO2 module, if present 12. Controls LCD view angle

1.2.2

CPU Hardware Controls 1. Microcontroller executes the above software functions, including: • • • • •

NIBP Recorder Temperature module, PTM or IR SpO2 LCD

2. Battery Back Up Circuitry for Power Savings • •

Static memory Non-volatile RAM for configuration and future serial number

3. Flash ROM for Program Storage and Execution 4. Static RAM for Data Storage 5. RS232 level translation for PC Download and second interface for CIS/HIS 6. Real time clock with 16K of Lithium backed up NV RAM

1.2.3

NIBP Hardware functions

1.2.3.1

Main pressure transducer circuitry A pressure transducer and amplifier combination is provided to acquire the cuff pressure signal.

1.2.3.2

Over pressure transducer circuitry An over pressure transducer, independent of the main pressure transducer. Over pressure limits are set according to the patient size.

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1.2.3.3

CPU/NIBP Module Assembly with LCD Display

Five A/D channels All channels are at 12-bit resolution and digitized at 101 Hz: 1. DC pressure 2. AC pressure (pulse) 3. Hardware over pressure transducer 4. Hardware over pressure cooperator reference 5. Battery voltage monitoring, when the Accutorr is in battery operation

1.2.3.4

Pulse Channel Filter A high-pass filter is provided to isolate the pulsatile component from the DC cuff pressure. This pulsatile component is digitized as the pulse channel. The gain of this AC coupled channel is programmable in a manner consistent with the specified range of pulse amplitudes.

1.2.3.5

Inflation Pump A pump capable of inflating the cuff within the specified time limit.

1.2.3.6

Bleed Valve A valve and control system capable of bleeding down the cuff pressure.

1.2.3.7

Dump Valve A valve to rapidly discharge the residual cuff pressure at the end of the measurement cycle.

1.2.3.8

Cuff Inflation Requirements The cuff is initially inflated to a software-determined pressure dependent upon patient size. In timer mode, it should be a predetermined increment, traditionally 50 mmHg (40 mmHg for Neonates) (determined by the CPU), above the previous systolic reading, after the first measurement. The software detects error conditions in the pneumatic system such as disconnected cuffs or kinked hoses. To reduce the possibility of over inflating the cuff, the pump may be driven at a lower speed when pressurizing small neonatal cuffs. This is achieved by pulse width modulating the pump control signal. Further control of the neonatal inflation rate may be achieved by using the bleed valve to relieve some portion of the pump's delivery.

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CPU/NIBP Module Assembly with LCD Display

1.2.3.9

Theory of Operation

Pulse Acquisition Requirements Pulse amplitudes from 0.06 mmHg to 12 mmHg are recognized. Pulse rates can range from 30 bpm to 250 bpm. The software discriminates pulses from the digitized pulse channel signal, and characterizes the pulses for amplitude, DC pressure, and pulse period. False triggering, due to the dicrotic notch or noise, is minimized.

1.2.3.10

Artifact Rejection Requirements The software provides means of artifact rejection, both during acquisition and during subsequent processing of the pulse array. Means of rejecting artifacts include attention to the timing and amplitude of pulses relative to adjacent pulses. If motion artifact is detected during acquisition, the software may cause temporary suspension of the bleed down process until a quiescent patient condition returns.

1.2.3.11

Parameter determination Requirements Pulses that are deemed acceptable after artifact processing are entered in the pulse array. Heart rate is taken to be the average rate of the pulse array data. Pulse periods differing excessively from the median are ignored. Pulses that do not appear to fit the amplitude envelope are removed. The systolic, diastolic, and mean pressures are then calculated in accordance with standard algorithms. A fair amount of data manipulation and computation is required in the parameter determination. The results are reported no more than one second from the termination of the pulse acquisition phase.

1.2.4

Major Hardware Components

1.2.4.1

CPU A microcontroller (min. 16MHz) with three (3) serial communication controllers (SCC), a serial communication port (SCP), programmable chip select lines (to minimize glue logic), a IDMA controller, and parallel I/O ports for discrete signals.

1.2.4.2

Flash Memory 512K x 16 Flash ROM used for program storage and execution. A Flash ROM is used also for downloading new revisions of software via the CPU's serial I/O lines (SCC).

1.2.4.3

Battery Backed Up Static RAM 512K x 16 static ram is used for data storage, trend information, etc. This memory is used for data storage. Therefore, a battery back up is provided.

1.2.4.4

Nonvolatile RAM Nonvolatile ram is used for configuration and serial number information. This memory requires a battery back up.

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1.2.4.5

CPU/NIBP Module Assembly with LCD Display

Micromanager This device provides a number of features that are useful for management of this board. They are listed as follows:

1.2.4.6

A.

ON/STANDBY capability through keyboard control

B.

Watchdog timer

C.

Conversion of CMOS SRAM to pseudo nonvolatile memory

Battery Backup Voltage Regulator Circuitry Implements regulation of the STANDBY VOLTAGE from the main power supply to 4V +/- 0.2V dc with a current draw of 821 uA max.

1.2.4.7

Real Time Clock This device provide seconds, minutes, hours, date of the month, month, and year with leap year compensation. The device is memory mapped to be pointed to as software requires. Also, provisions for running this device include main power supply and battery operation in order for the RTC to keep time when the system is not powered. A lithium battery is included, having a minimum of 10 years of operation, for configuration and clock data retention during battery changes and main battery failure. Accuracy is +/- 1 minute/week.

1.2.4.8

Recorder Interface IDMA capability for writing 8-bit buffered parallel data to the recorder. Handshaking signals to specify new line to be printed, request for next byte of data.

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CPU/NIBP Module Assembly with LCD Display

1.2.4.9

Theory of Operation

Communication Block The module provides the following interfaces and functions: •

RS-232E drive from TTL levels. RS-232E driver for CIS/HIS that will provide minimum of 9V signal level.

•

IC based DC/DC converter capable of converting VCC to 12VDC, with leakage current when off < 100uA. High frequency operation to limit emitted fields. Capable of providing an output current of 125 mA @ 12Vdc, with an efficiency of 80% or higher.

•

Signal driver for an external isolated relay that will be used for Nurse Call, provided on pins of the 9-pin RS-232 connector.

The RS-232E interface required is implemented using a Maxim, MAX236 Multi-Channel Transceiver (U602). This chip was chosen because it has a minimum ±9 volt output signal level. Communication is to support a 5 wire interface, 4 signals and a ground. The signals are described below: SIGNAL

DESCRIPTION

INPUT/OUTPUT

RXD

Received Data from DCE to DTE device

Input

TXD

Transmitted Data from DTE to DCE device

Output

RTS

Request to send from DTE to DCE device

Output

CTS

Clear to Send from DCE device

Input

GND

Signal Ground

Input

All RS-232 signals are ESD protected by a U603, an SM14M24C Transient Voltage Suppressor array. The +12 VT dc power required by the Nurse Call cable is supplied from the onboard DC/DC converter. The MAX236 receivers are controlled by logic signal CSTAT*. Logic 0 enables the receivers; otherwise, they are tri-stated. The RS-232 signals appear on connector J603, a dual row 14 pin header which will have a mating 14 pin pendant ribbon cable attached. The other end of the ribbon cable assembly is a 9 pin panel mount ‘D’ connector.

1.2.4.10

Backlight LED Driver The LED driver module is implemented with Linear LT3474, step-down 1A LED driver. It can source constant current maximum up to 1A. The current can be programmed by setting the voltage at Vadj pin (pin 13) through resistors R42 and R14. The switching frequency is programmed to 300KHz for best duty cycle (i.e, 96%) for higher efficiency. The typical LED drop voltage of 3.5V is achieved by programming the constant output LED current of 71mA. The Vadj is sourced from external voltage source (i.e., +5V VCC) by external resistor divider.

1.2.4.11

LCD Trend Display DAC control provided from the LED/Tone Board controls the LCD View Angle.

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1.2.4.12

CPU/NIBP Module Assembly with LCD Display

Temperature Interface The board provides a Serial Interface to either Temperature module.

1.2.4.13

SpO2 Interface The board provides a Serial Interface to SPO2 and reset control of the module.

FIGURE 1-1 CPU Block Diagram

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CPU/NIBP Module Assembly with LCD Display

Theory of Operation

FIGURE 1-2 NIBP Block Diagram

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1.3

SpO2 Processor Circuit Boards

SpO2 Processor Circuit Boards The Accutorr Plus can be equipped with one of two optional technologies: •

Nellcor® SpO2 system

•

Masimo® SpO2 system

Each technology uses proprietary sensors and interface cables. There are no “adapters” possible or available.

1.3.1

SpO2 General Theory Of Operation Regardless of manufacturer, SpO2 determination is based on the relative attenuation of a red and an infrared light source. A sensor from the instrument contains two sets of LEDs to illuminate a portion of the body (for example, a fingertip) and a single photo sensor detects the light returned. The LEDs are alternately pulsed, red and infrared. Since hemoglobin is the carrier of oxygen in the blood and the relative attenuation of the light sources is proportional to the amount of oxygen carried by the hemoglobin, a relative level of saturated hemoglobin can be determined. Since we are measuring the ratio of red and infrared return from the circulatory system, the detection method is substantially independent of skin color or total skin attenuation. Since the blood flow has a pulsatile characteristic, a pulse rate can also be computed from this information.

1.3.2

NOTE:

There is no calibration possible for the determination of the SpO2% or of the pulse rate derived. As mentioned above, we are measuring a ratio of intensity of two light sources to determine the % of saturated hemoglobin. The determination is based on proprietary software interpretation of the reflected light ratios, and it is validated against strict clinical trials where fresh arterial blood is examined with a clinical blood gas analyzer. Once the software is finalized, the SpO2 monitor accuracy is fixed and there are no possible adjustments.

NOTE:

The wavelengths of the light emitted are nominally 660nm and 890nm with the energy not exceeding 15mV.

Nellcor® Nell-3 SpO2 Circuit Board Theory of Operation The Nell-3 is a complete SpO2 detection and determination circuit, proprietary of Nellcor® Puritan Bennett. Patient data is processed for serial transmission to the host system.

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