NIHON KOHDEN Life Scope G5 bedside monitor

Category: NIHON KOHDEN (日本光電) Life Scope monitoring system. This is a review of the Life Scope G5 bedside monitors, which are renamed as a product line of the new Genesis  family products. The market must know that the Life Scope G5 bedside monitors are not digital modular monitors and the reasons are clearly explained in this article.

 

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LIFE SCOPE Genesis G5 series Bedside Monitors is a direct replacement for Life Scope TR series Bedside Monitor

The Life Scope G5 series bedside monitors are released as part of new Genesis family series and there are two models:

1. CSM-1501 bedside monitor has a 12.1-inch panel PC

2. CSM-1502 bedside monitor has a 15.6-inch panel PC

It is not brand-new as one may be led to believe. The Life Scope G5 bedside monitors are in reality the Life Scope TR (BSM-6000 series) bedside monitors with the LCD display unit updated to a panel PC. The new web browsing capability of Life Scope G5 bedside monitor comes from the panel PC.

Before Life Scope G9, none of the Life Scope patient monitors (including Central Monitors) had ever been able to access external servers for images of Ultrasound, CT, MRI, Laboratory test results, clinical decision support etc. Life Scope G5 bedside monitor is the next after Life Scope G9 to offer a web browser for clinical data servers access, thanks to the panel PC.

Life Scope G5 series bedside monitor makes use of the same Input Unit as Life Scope TR series

Similar to Life Scope TR, a Life Scope G5 bedside monitor uses the AY-663P or Life Scope PT bedside monitor as an Input Unit. When a transport monitor is needed, Life Scope PT transport monitor acts as input unit when placed on the Life Scope G5 main unit, and becomes an independent transport monitor when it is detached from the Life Scope G5 main unit.

When a transport monitor is not required, the AY-663P Input Unit is being used instead. Both Life Scope PT transport monitor and AY-663P Input Unit can be expanded with additional four connector sockets using the AA-174P expansion box; it works for Life Scope PT only when it is acting as an input unit. There are four models of Life Scope PT (BSM-1700) transport monitor to select from. The AY-663P Input Unit can also be substituted with AY-653P Input Unit (using Nellcor OxiMax SpO2 algorithm) or AY-633P Input Unit (using Masimo SET SpO2 algorithm).

Note AY-663P Input Unit is refrained from use in the US market, and in its place Life Scope PT (BSM-1773) transport monitor can be selected to be the input unit if NIHON KOHDEN SpO2 algorithm is intended. There are four models of Life Scope PT transport monitor, and the BSM-1773 model has the version of SpO2 algorithm specially for the US market.

Although Life Scope G5 bedside monitors could still make use of the Data Acquisition Units, this configuration is now done using new Life Scope G7 bedside monitors. It means Life Scope G5 using a data acquisition is more expensive than Life Scope G7 using a data acquisition unit. 

Next comes the interesting part; there is very little knowledge why the configured AY-663P, AY-653P and AY-633P multi-parameter Input Units of Life Scope G5 bedside monitor are so different and big?

 

What are inside the Input Units of Life Scope G5 that each has to be so big?

If you look at the Life Scope PT transport monitors, they are the same input units upgraded with a touch-screen and battery, so we will just examine the input units here.

The shown input unit is really heavily loaded with monitoring hardware, and are avoided for mention in communication to the market, intentionally done to hide the fact the input units are in fact configured. The manufacturer wants the market to imagine the input unit possess scalable capability to add monitoring parameters.

 

Many internal hardware are intentionally not made clear in product communication to the market

The prominent feature of the AY-663P Input Unit (or Life Scope PT transport monitor) is the utilization of yellow MULTI-parameter sockets. The MULTI-parameter sockets do not accept ordinary measurement cables but only cables embedded with codes defined by NIHON KOHDEN.

NIHON KOHDEN had identified five types of internally configured hardware that can be linked to the MULTI-parameter sockets and to make use of these hardware, a cable with the correct code must be plugged into one of the MULTI-parameter sockets. These coded cables are collectively cited as Smart Cables by the manufacturer and the codes are also known as parameter codes. Each socket selects only one channel of the hardware, except for Temperature allowing two channels of hardware to be selected.

 

A coded measurement cable can make use of any of the internally configured hardware shown here

The configured hardware are grouped into a block known as MULTI-parameter Unit. Since the number of IBP monitoring channels correspond to the number of MULTI-parameter sockets, each MULTI-parameter socket comes with its own IBP hardware. A MULTI-parameter socket makes use of its own IBP hardware when a measurement cable with a IBP code is plugged into it; it is the design that if a MULTI-parameter socket does not come with its own one-channel IBP hardware, it does not have the ability to perform IBP monitoring.

Remember,

A functional MULTI-parameter socket always come with its own one-channel IBP hardware.

This being a hardware rule, and the key word is "functional" because a non-functional MULTI-parameter socket may not need to care about the capability to do IBP monitoring, such as a socket found on the CardioLife TEC-5600 series defibrillators solely for mainstream CO2 kit sets.

Principle of operation

Given the large amount of hardware in the MULTI-parameter Unit block, it may be necessary to add more MULTI-parameter sockets; this is done by using an external expansion box filled with MULTI-parameter sockets with associated IBP amplifier hardware.

The additional sockets are added using analog interface with a limit set at a maximum of four MULTI-parameter sockets. The limitation is to avoid signal deterioration caused by voltage drop and noise.

There are variations from the basic theme, such as doing without use of external expansion box, or increasing the number of MULTI-parameter sockets in the MULTI-parameter Unit, or reducing the hardware configured in the Multi-parameter Unit.

In the AY-663P, AY-653P, AY-633P Input Units (or Life Scope PT transport monitors), 3 channels of IBP amplifiers, 2 channels of Temperature, one channel each of Thermistor Respiration, FiO2 and Cardiac Output are configured for use by Smart Cables.

NIBP, SpO2, ECG and two channels of Temperature are configured using dedicated measurement cables

The digital hexadecimal code is stored in an EEPROM chip mounted on a small flexible PC board electrically wired to the pins of the cable plug. It is not difficult to make the Smart Cables but they are being priced highly by the manufacturer; only the common IBP cable can be sourced from China suppliers at a reasonable price.

A parameter code is stored in the plug of the measurement cable

One MULTI-parameter socket can select two Temperature hardware channels.

Each MULTI-parameter socket can take two channels of Temperature measurements

The MULTI-parameter sockets are additionally allowed to be diverted as costly digital serial ports; the mainstream CO2, 2nd SpO2, BIS and NMT hardware are supplied as self-contained digital serial kits using the MULTI-parameter sockets only as a link to the monitor.

The original label for the yellow MULTI socket indicated the five specific hardware plus mainstream CO2 serial kits using it as a serial port.

 

The original label for the yellow MULTI-parameter sockets when they were first used

 

The use of Smart Cables is configured monitoring

A yellow MULTI-parameter socket by itself does not automatically mean all the five types of mentioned parameters are available for measurements; it still depends on whether what hardware are actually being placed inside for selection.

When a model is not equipped with FiO2 hardware internally, no amount of yellow MULTI sockets is going to provide this measurement capability. The amount of configured hardware linked to each multi-parameter socket varies, so is the system support for serial kits.

Examples of configured hardware using Smart Cables

In other words, it is the built-in hardware that determine the parameter capability; and in the case of serial kit sets, the system software. This of course, is the same description as a configured patient monitor

 

Actual internal hardware and system support for serial kits varies for each multi-parameter unit

This means Life Scope G5 bedside monitors making use of Smart Cables are still configured monitors.

The value captured by users using the Smart Cables is negative

Take a closer look at the AY-663P Input Unit shown below, it needs at least ten sockets for carefree use but the manufacturer can only provide three yellow MULTI-parameter sockets for time-sharing use. This means only three of the ten connectable cables can plug into the input unit at any one time. The input unit is so short of connector sockets, why would anyone need such a skewed input unit?

The reason AY-663P Input Unit cannot come with more MULTI-parameter sockets is because only three IBP amplifier hardware are specified for said input unit. Since each MULTI-parameter socket comes with its own one-channel IBP hardware, the manufacturer cannot provide more than three MULTI-parameter sockets. Notice the two channels of Temperature hardware in the shown input unit are not making use of the yellow MULTI-parameter sockets for connections, this is to provide relief to the three yellow MULTI-parameter sockets which are not enough for use.

A skewed input unit delivering pain of not having enough connector sockets

The BIS, Second SpO2, ETCO2 and NMT parameters are using self-contained kit sets with processed digital serial data using the input unit only as a link to the monitor, they have no reason to queue for the scarce yellow MULTI-parameter sockets.

What value can the users capture from using input units that come with deficiency of connector sockets? The first vehement complaint from users is always the yellow MULTI sockets are not enough for use!

Next comes the fascinating offer to add more yellow MULTI-parameter sockets to supplement the three already on the AY-663P Input Unit. Electrically, the manufacturer can add more MULTI-parameter sockets to the AY-663P Input Unit using an external box (AA-174P) which comes with four MULTI-parameter sockets.

The link from AA-174P expansion box to AY-663P is an analog interface, not digital; as such, only a maximum of four MULTI-parameter sockets can be added. The limitation is due to signal deterioration caused by voltage drop and noise pickup.

AA-174P box adds not only four MULTI-parameter sockets to the AY-663P Input Unit, but also four channels of IBP hardware

It is obvious the AY-663P Input Unit can never be sold without the AA-174P expansion box, the manufacturer should have designed an input unit with enough connector sockets in the first place, but there is a reason for wanting to do it. The purpose is to imitate the process of scalability of patient-monitoring parameters when MULTI-parameter sockets are being shown visually added to the input unit, but the manufacturer is adding sockets and not patient-monitoring parameters. A bedside monitor using AY-663P Input Unit and AA-674P expansion box is not modular in design.

Someone had got it all wrong! What we are seeing here is scalability of the MULTI-parameter connector sockets, it is not what the market wants

 

We should be clear, the scalability of patient-monitoring parameters is the one that is being sought after by the market, not scalability of usable connector sockets. The act of adding four MULTI-parameter sockets using the AA-174P expansion box also means adding four channels of IBP hardware to what are already configured in the AY-663P Input Unit; do you need seven channels of IBP hardware? This is how Life Scope G5 bedside monitor got its maximum ability to do seven channels of IBP monitoring; it is either three channels of IBP monitoring using AY-663P alone or seven channels of IBP monitoring using both AY-663P and AA-174P, but the AY-663P Input Unit can never be sold alone because of the massive deficit of connector sockets.

Users are told the AY-663P Input Unit must be supplied with AA-174P expansion box as standard to meet the number of sockets needed, but this is not the real reason and users are unknowingly accepting seven mandatory built-in IBP hardware. What is parameter scalability in this odd arrangement?

The limitation of only four MULTI-parameter sockets can be added means it is not possible for the AY-663P Input Unit to make use of two AA-174P expansion boxes. This is also a configuration including 11 channels of IBP hardware!

Elaborate time-sharing are applied to things that are expensive (high in demand, an asset), and not worth the efforts for things that are cheap (high in supply, a commodity) like a connector socket or a switch! It only makes sense to see productive efforts being made to time-share a CPU, a car, a hotel room, a yacht, an airplane but not a calculator, a pencil or a pair of scissors.

 

Time-sharing of a car (an asset) creates value

The next picture shows Philips time-sharing one channel bio-amplifier hardware between IBP and Temperature measurements, and there was no sharing of connector socket; this is exactly the opposite of what Nihon Kohden is doing. The said manufacturer merely ensures physically it is not possible to make use of both the PRESS and the TEMP socket at the same time.

 

Only share the expensive hardware, not the cheap sockets

Philips modular monitors

The AY-663P Input Unit input unit with AA-174P expansion box corresponds to a Philips MMS module with an extension. These are operating at the configured level, not modular.

The Philips MMS modules (initiated by Hewlett Packard) are however additionally capable of being linked to a real-time measurement data network using Ethernet

   

HP Agilent M3/M4 portable monitor

While the Philips MMS modules can be upgraded using extensions, each MMS module also has an IP address for linking onto the Measurement Ethernet network. Scalable monitoring is achieved by slotting individual modules into a module rack linked to the Measurement Network; in the same way, expensive modules can be shared.

On the contrary, NIHON KOHDEN failed to realize a workable Measurement Network and the Life Scope TR Input Units do not have IP addresses for networking. There is no way to scale monitoring parameters or sharing expensive modules, only using serial kit sets and externally-powered devices.

The Philips MMS module (and extension) serves as the basic module and can be expanded using a measurement LAN

In case you are thinking we are not aware there are monitoring hardware being embedded in the NIHON KOHDEN Smart Cables, we had not missed it. This is a wrong understanding in the market and we can prove there are no active electronics in the Smart Cables.

The marketing messages "New Modular Technology" and "The Module is in the cable!" are mere imaginations.

What do the manufacturer mean by this statement? 

It started with the Life Scope TR (BSM-6000) series monitors in the USA market and gradually adopted officially for International markets. These are precise statements.

This is just assertion without showing any proof

 

Chip makers need huge demand to justify each of their products, so which chip manufacturer has been supplying NIHON KOHDEN the variety of analog chips given the extremely low volume in demand? If we were to open up a Smart Cable plug, what do we see? A small PC board is seen attached to some pins of the yellow plug.

 

A small PC Board is soldered to some pins of the yellow connection plug

 

The PC board confirms a cheap digital EEPROM chip is being used to code the Smart Cable.

 

A cheap digital EEPROM chip was what we found inside the yellow Smart Cable plug

If we were to open up the plug of a compatible IBP cable from China suppliers, what do we see? It is the same thing, a plug with a digital code defined by NIHON KOHDEN.

Under US FDA rule, a cable is only a cable if it does not change the signal that passes through it. A Smart Cable with a hexadecimal code is just a cable and does not change a signal passing through it, but if it has an amplifier it becomes a medical device and requires FDA registration. Can you find any stand-alone Smart Cables registered with US FDA as a medical device?

When the Smart Cables are used with serial kit sets, such as mainstream CO2 kit sets or the NMT AF-101P kit set, the registration is for the active serial kit set and not the passive Smart Cable.

Irrefutable proof the IBP amplifier hardware is configured internally, an important fact withdrawn from later monitor manuals

 

The Life Scope BSM-2301 bedside monitor was launched before the Life Scope TR bedside monitors, and the Service Manual is clear on the design; manuals for later models stop providing such information. The major move to curb details in manuals started from Life Scope J (BSM-9101) Bedside Monitor, launched before the Life Scope TR bedside monitors.

In below BSM-2301 service manual, you can see the IBP and thermistor respiration are internal hardware inside the Life Scope BSM-2301 monitor. These hardware are linked to the MULTI-parameter socket, and to make use of either hardware, a Smart Cable with the correct code must be plugged into the MULTI socket.

 

Can you see the IBP amplifier and thermistor respiration hardware are internal components of the Life Scope BSM-2301 monitor?

The MULTI-parameter socket doubles as a serial port without any need for internal monitoring hardware, only as a link to the monitor. In the block diagram below, the processed digital serial data from a CO2 kit set goes straight to the digital microcontroller APU (Analog-block Processing Unit) and is forwarded to the DPU.  For a parameter using the internal analog hardware, the analog signal needs to pass through an Analog-Digital converter before going to the APU for digital processing. 

Relevant page in the combined Service Manual for BSM-2301A, BSM-2301K, BSM-2303K, BSM-2304A

You should know by now the three IBP amplifier hardware inside the AY-663P Input Unit or Life Scope PT transport monitor is the reason they can each perform three channels of IBP monitoring.

Knowing there are three built-in IBP amplifier hardware inside the AY-663P Input Unit easily allows us to conclude the rest of the configured hardware after confirming all parameters that can be measured by the input unit.

The huge amount of hardware inside the AY-663P Input Unit

 

First we filter out the parameters using self-contained serial kit sets, and they are mainstream CO2, 2nd SpO2, BIS and NMT hardware for the AY-663P Input Unit.

We can conclude the patient monitoring hardware in the AY-663P Input Unit to be:

(NORMAL BLOCK) The hardware using dedicated sockets and ordinary measurement cables:

- 2 channels of Temperature

- ECG

- SpO2

- NIBP

(MULTI-PARAMETER UNIT BLOCK with three MULTI-parameter sockets) The hardware only use Smart Cables for connections:

- 3 channels of IBP (3 MULTI-parameter sockets = 3-ch IBP)

- 2 channels of Temperature (1 MULTI-parameter socket = 2-ch TEMP)

- Thermodilution Cardiac Output

- FiO2

- Thermistor Respiration

These hardware in the Multi-parameter Unit of AY-663P is the reason for its size

In the AA-174P expansion box, the four MULTI-parameter sockets make use of their own IBP hardware when an IBP Smart Cable is plugged in; for the other four parameters, the sockets are linked to the Temperature, Cardiac Output, FiO2 and Thermistor Respiration hardware already embedded in the Multi-parameter Unit of AY-663P Input Unit.

The hardware in the AA-174P expansion box

It is such a big mistake to pick the Smart Cables as a product selling point. There is no proper viability assessment and is only leading customers into having an unrealistic expectation of what the Smart Cables can actually deliver. The apparent flexibility of the MULTI sockets is in reality an adaptation with negative captured value for the users.

In the 1990s, when developing the first digital modular monitor, the development team encountered a problem of insufficient front panel space for connector sockets on the first digital multi-parameter module being made. The Smart Cables were originally devised only to resolve a product issue.

At the time NIHON KOHDEN was responding to an important emerging trend of using a high-density digital multi-parameter module as basic building block for modular monitors. In analog modular monitors, only single parameter modules were produced by NIHON KOHDEN. When designing the first digital modular monitor, the company discovered the critical care market had already moved to using a digital multi-parameter module with higher density of electronic components as a basic building block for modular monitors.

 

NIHON KOHDEN wanted to follow the trend by offering the first digital multi-parameter module, and the first digital multi-parameter module made by the company was named the Saturn module.

Responding to new trend in the 1990s using a multi-parameter module with higher electronic density as a basic building block for modular monitor

Nihon Kohden intended a module rack integrated physically with the main unit to form a limited footprint just big enough to stack the display monitor on top of it (see below illustration). The physical size of the Saturn module was therefore constrained; in addition, the multi-parameter module must work in combination with other parameter modules like recorder, sidestream CO2, BIS, EEG, Flow/ PAW, SvO2 in the module rack.

The Saturn module was intended to be physically small in size

The elegant but expensive solution from NIHON KOHDEN for the physical size limitation of the Saturn module was to modify two connector sockets for sharing use. The method selected by NIHON KOHDEN was to make use of coded measurement cables known as Smart Cables to share two modified connector sockets for five types of suitable hardware, namely IBP, Temperature, Thermodilution Cardiac Output, Thermistor Respiration and FiO2.

The Saturn module turned to sharing two modified connector sockets for five types of suitable hardware

The patient monitoring hardware were separated into two blocks in the Saturn module.

(NORMAL BLOCK) The hardware using dedicated connector sockets and ordinary cables:

- ECG

- SpO2

- NIBP

(MULTI-PARAMETER UNIT) The hardware sharing the two adapting MULTI-parameter sockets in this block only use Smart Cables for connections:

- 2 channels of IBP (2 MULTI-parameter sockets = 2-ch IBP)

- 4 channels of Temperature (2 MULTI-parameter sockets = 4-ch TEMP) 

- Cardiac Output

- FiO2

- Thermistor Respiration

Huge amount of configured hardware sharing two modified connector sockets as a compromise

The adapting MULTI-parameter sockets were additionally allowed to be diverted to act as a costly digital serial ports so that mainstream CO2 digital serial kit sets can also use it; this being an easy task since no internal analog hardware is being involved.

The mainstream CO2 comes in the form of a self-contained serial kit set with digital processed output, utilizing the MULTI socket only as a link to the monitor.

Remember this is for purpose of minimizing connector sockets on the Saturn multi-parameter module, as it does not make sense outside this context.

A yellow MULTI-parameter socket is a high-cost serial port when it does not select any internal hardware

MULTI-parameter socket poorly utilized as a costly serial port

The initial arrangement was only for mainstream CO2 serial kit sets, but later extended enthusiastically to BIS kit set, 2nd-SpO2 kit set, APCO kit set, NMT kit set etc., whose motivation is highly questionable given this greatly increases the interface cost compared to a plain serial port.

The use of Smart Cables for serial communication does give a false illusion of mighty MULTI-parameter sockets but the capabilities are in reality coming from the system software.

 

Make no mistake, the serial kit sets are self-contained and whether a particular kit set is supported depends on the system software, not on the type of connector sockets being used.

To reiterate, there is no difference if you connect digital serial data to the monitor using Smart Cables or ordinary serial cables

 

This is how you connect the BIS processor kit to a yellow MULTI socket

Using Smart Cables for serial interface means an unnecessary jump in demand for more yellow MULTI-parameter sockets and there is no technical need for the serial kit sets to use the yellow MULTI-parameter sockets. Putting things into perspective, most patient monitoring parameters cannot be made into self-contained serial kits; for example, the AE-918P Neuro Unit or a strip chart recorder cannot be linked to a yellow MULTI-parameter socket as serial kit as shown. They are connected as external devices to a monitor.

 

The AE-918P Neuro unit and recorder module are examples that cannot make use of the yellow MULTI sockets

The MULTI PARAMETER UNIT is an official term found in the service manual

 

The two yellow MULTI-parameter sockets on the Saturn module are not enough for use

 

For such a huge amount of hardware in the Saturn module, more sockets are badly needed. The shortage of sockets could be improved by linking more external MULTI-parameter sockets to the hardware in the MULTI-parameter Unit of the Saturn module. As this is an analog solution, only a maximum of four MULTI-parameter sockets can be added this way.

Analog solution of adding up to four MULTI-parameter sockets using external boxes

The image gives an impression of scalability but this is scalability of connector sockets, and not the scalability of monitoring parameters that is being sought after by the market. All necessary hardware are already configured in the Saturn module except for additional IBP amplifiers which must be tied to the number of available MULTI-parameter sockets.

The Saturn module only has two yellow MULTI-parameter sockets, it is impossible to perform more than two channels of IBP monitoring; this means IBP hardware must always correspond to the number of MULTI-parameter sockets available and each MULTI-parameter socket comes with their own IBP hardware. A MULTI-parameter socket makes use of its own IBP hardware when a Smart Cable with an IBP code is plugged into it; for the other four parameters, the sockets are linked to the Temperature, Cardiac Output, Thermistor Respiration and FiO2 hardware already embedded in the MULTI-parameter Unit of Saturn module.

A functional MULTI-parameter socket always come with its own one-channel IBP hardware

What you are seeing is making use of space external to the Saturn module to compensate up to four missing sockets on the Saturn module. The extension Smart module is therefore a 2-channel IBP box with two MULTI-parameter sockets.

The Saturn module, together with two satellite boxes adding 4 channels of IBP to the Saturn module is shown in the next picture. The four MULTI-parameter sockets on the satellite boxes can also access the MPU of the Saturn module. Together, six IBP channels and six shared-use MULTI-parameter sockets are available to the users.

The sockets on the satellite boxes compensate for the missing connector sockets on the Saturn module

 

The two Modular Monitors that made use of the Saturn module were failures

The two modular monitors that could make use of the first Multi-parameter Module (Saturn module) made by NIHON KOHDEN were Life Scope S (BSS-9800) bedside station and Life Scope M (BSM-9510) bedside monitor; the software supporting the network infrastructure exchanging digital measurement data between the Saturn module and main units was unfortunately, not reliable and both modular monitors ended up as failures.

Life Scope S (BSS-9800) bedside station was a digital modular monitor

 

Lower-end Life Scope M bedside monitor was using a (6-slot) built-in module rack. The Life Scope M (BSM-9510) bedside monitor has lower processing power compared to the Life Scope S bedside station.

From the US FDA records, you could tell that Life Scope S and Life Scope M monitors were not launched in the US market

 

The two monitors were found lacking before they could be marketed in the USA market.

The cause of the failure for Life Scope S and Life Scope M modular monitors was the problematic network infrastructure needed by modular monitors for data exchange between modules and main unit. This resulted in Life Scope S bedside station functioning only as a limited monitor while the Life Scope M bedside monitor had to be withdrawn from the market due to insufficient processing power.

There were two digital real-time data network infrastructures used by BSS-9800 Life Scope S bedside station. The software supporting the Ethernet network linking patient monitors to the Central Nurse Station proved stable but the software supporting the network linking the modules to the main units of BSS-9800 bedside station/ BSM-9510 bedside monitor was unreliable and further development of the network infrastructure was stopped to avoid incurring unbearable losses.

The exchange of measurement data between main unit and modules was problematic

 

The product failures were huge financial losses incurred at a time when the company was already suffering badly from poor sales due to the lack of digital technology know-how.

NIHON KOHDEN could not solve the communication problem between main unit and modules

 

Failure to succeed in the measurement data-exchange network infrastructure meant NIHON KOHDEN was downgraded to be a manufacturer only capable of making configured patient monitors.

WATCH OUT the dangerous use of uncertain semi-quantitative CO2 measurements and displaying a flawed CO2 waveform

Nihon Kohden lacks sidestream CO2 sampling expertise and buys OEM units to offer them as expensive standalone. The AG-400 CO2 unit as shown, for example, is technology from Oridion Medical. For monitoring such as post-surgery recovery, integration of the sidestream CO2 into the monitor is a mandatory requirement because an external unit requires additional power socket besides necessitating the use of a trolley.

 

For some unknown reason, Nihon Kohden monitors have never been able to offer benefits of integrated sidestream CO2 measurements.

 

The inability to integrate the sidestream CO2 unit into the patient monitor main unit

The adoption of semi-quantitative mainstream CO2 measurement was to reduce cost and its simplicity also help in miniaturization of the transducers. The first solution offered by Nihon Kohden was the mainstream cap-ONE TG-920P CO2 sensor kit (order code P907) that can be used on non-intubated patients.

 

The cap-ONE TG-920P CO2 sensor kit (order code P907) has very small sensors because semi-quantitative measurement is adopted, the method is not commonly seen and many are not aware of the risks of obtained CO2 readings from the semi-quantitative CO2 kit sets, and to make matter worse, the semi-quantitative measurements are also being made used of to display a flawed continuous CO2 waveform.

 

Nihon Kohden cap-ONE P907 (TG-920P) mainstream CO2 sensor kit

How to remove a relatively big disposable adapter from the two tiny transducers after use?

 

When the sensors become smaller, it also means the disposable adapter becomes relatively much bigger as seen in this below picture. When trying to remove the disposable adapter from the transducers, it is difficult to separate the two because of the latching mechanism. A small size transducer means anything that latches onto it must be even smaller.

It is not easy to separate the disposable adapter from the Cap-ONE transducers after use

 

When removing disposable adapter from the mini sensors, users tend to just pull from the cables and this action quickly weakens the joint holding the sensors and cables. The action will cause stress to the two joints and quickly degenerate the performance of the transducers. This means the transducers are unlikely to last.

 

Users just doing the inevitable

 

Shown below is another TG-900P etCO2 kit set (order code P903) that makes semi-quantitative CO2 measurements on a traditional mainstream CO2 sensor. The TG-901T3 kit set (order code P906) is the same thing but using a non-coded connection plug. The medical devices from same manufacturer that make use of semi-quantitative CO2 kit sets for patient CO2 measurements and waveform include:

- Life Scope patient monitors

- Vismo patient monitors

- Cap-STAT OLG-2800

- CardioLife defibrillators

- Neurofax EEG machines etc.

 

Nihon Kohden semi-quantitative CO2 kit sets with traditional mainstream transducer

 

Do the users know semi-quantitative CO2 measurements are only estimations?

    

To save costs, the semi-quantitative kit sets do not make measurement during the inspiration phase. The important point is there is a measurement duty cycle and it is as shown; there is no way to know the actual CO2 measurements during the inspiration phase because CO2 measurements are not made.

Semi-quantitative means there is a duty cycle, and measurements are not continuous

 

Semi-quantitative measurement is also of low-accuracy type, performed using one IR detector instead of the usual two to save cost. This is reflected in the measurement tolerance.

 

Contrasting, quantitative measurement delivers high accuracy for critical care. To ensure the necessary high accuracy, quantitative measurement employed two IR detectors for simultaneous CO2 measurements at different wavelength for results comparison. CO2 measurements are also being made continuously.

 

Quantitative measurement employs two detectors to make continuous measurement at different wave-lengths to compare readings for high accuracy

NIHON KOHDEN specification for TG-901T CO2 sensor kit shows even the specified low accuracy of CO2 measurement using semi-quantitative method no longer holds true once CO2 is present during the inspiration phase.

This is because actual CO2 value will be more.

It is impossible for users to know if measurements are reliable when they cannot tell if CO2 is present during inspiration!

  

Measurements are invalid when CO2 is present during inspiration, but CO2 is not measured during this period

 

As seen from the duty cycle, there is no measurement being made during the inspiration phase, how does the manufacturer assure measurement accuracy? The specified measurement tolerance has no meaning for the users!

It should be clear each semi-quantitative CO2 measurement is only an estimation since its accuracy is rendered uncertain by the inability to confirm if CO2 is present during the inspiration phase.

Since the users are also not alerted on screen there is no CO2 measurement being made during the inspiration phase, they are unknowingly made to take on unnecessary risk.

 

Semi-quantitative methodology means cost-effective estimations and the design cannot be used in a general way, only on a selective basis with known risks

 

For example, semi-quantitative methodology can be used as a simple estimation tool for obtaining the numerical value of End-tidal Carbon Dioxide level (etCO2).

 

Below picture shows the semi-quantitative method in the way it was intended for, estimating only the etCO2 numerical value for purpose of airway tube placement confirmation. It is not for continuous waveform display.

A hand-held semi-quantitative etCO2 estimation tool (with SpO2) for airway tube placement confirmation

 

 

How can you properly display a continuous CO2 waveform when your semi-quantitative measurement kits do not have the ability to make continuous measurements?

 

NIHON KOHDEN also allows data from semi-quantitative measurements to be displayed on screen with the non-measurement period reset to zero level. The insistence to display a continuous waveform using discontinuous measurement data from semi-quantitative mainstream CO2 estimation kits is unacceptable; the manufacturer is just subjecting the monitored patients and users to dangerous misinterpretation risks.

 

A zero CO2 reading on the waveform means zero measured value. No measurement can only mean a defective sensor, not by design!

Note the end tidal CO2 (etCO2) value shown is also not alerted as "estimated etCO2" only.

 

A flawed CO2 waveform with non-measurement intervals reflected as zero measured CO2 value

As seen from the two true CO2 traces below, expiratory upstrokes do not always start from zero CO2 level!

 

Quantitative measurements confirming expiratory upstrokes do not always start from zero CO2 level

  

Check the latest updated table to make sure you only use quantitative method for critical measurements and true CO2 waveform display on screen.

 

Use only quantitative method for waveform display; the quantitative TG-950P (P905) shown here was already discontinued.

 

 

How about fully-quantitative type miniaturized mainstream CO2 sensor?

 

The TG-907P CO2 Sensor kit (order code P909) shown in above table is declared as using quantitative method. This sensor was designed for non-intubated adult CO2 monitoring, as well as neonatal CO2 monitoring. Nihon Kohden is thus offering an alternative to sidestream CO2 sampling methodology.

 

The miniaturized CO2 sensor is easily broken by the bigger and stronger adapter

 

In addition to the dead space problem, they had not foreseen miniaturized mainstream CO2 sensors could be easily broken by the disposable adapters. This happened because the disposable adapters are now relatively bigger and stronger!

These are common defects of a TG-970P CO2 sensor kit (P909). The design is impractical.

 

 

The fragile miniaturized CO2 sensor is clearly of poor design, and easily broken

 

 

Key point is, it does not last

Beware the mandatory need for network isolation units when connecting Life Scope G5 bedside monitors to a Central Nurse Station

 

For hardwired Ethernet networking, a Life Scope G5 bedside monitor equipped with a non-isolated Ethernet LAN interface when connecting to a real-time LAN network is a danger to the patient. It is mandatory to observe patient electrical safety by using a network isolation unit to protect the patient.

NIHON KOHDEN network isolation transformer

When an isolated monitor with an non-isolated Ethernet port is connected to a hardwired network, it is no longer a medical device unless the above-shown network isolation transformer is introduced between the monitor and network. If the network isolation transformer is not installed, dangerous electric shocks can be delivered to a monitored patient through the wired Ethernet network. Such dangerous electric shocks are potentially lethal and no hospital should ignore this mandatory requirement.