NIHON KOHDEN Life Scope Smart Cable System (AUG 1998)

Category: Life Scope multi-parameter patient monitors product review. Clear and detailed explanation of the NIHON KOHDEN Life Scope Smart Cable design developed in the 1990s.

Smart things do not last

Smart is a magic word much touted in the market place; however, what was a latest smart phone just months ago is no longer that smart today. What then can be said about a smart piece of cable that is more than twenty years old? Common sense tells us they should have been dumped long time ago. For this reason, we are curious to examine a line of Smart Cables launched in August 1998 as accessories of a medical patient monitor which are still on life support today; one must wonder the unusual reason for its longevity and where on the Product Life Cycle curve are these Smart cables?

 

A "Smart Cable" as shown on Nihon Kohden America website in late 2014

 

The Smart Cables are each marked with a digital hexadecimal code on its yellow plug for identification to engage a similarly-colored yellow sockets known as MULTI-parameter (or MULTI) sockets.

 

 

The digital code is stored in a non-volatile EEPROM chip placed on a small flexible PC board electrically wired to the pins of the cable plug. The digital hexadecimal code in the EEPROM is programmed at the factory and cannot be changed by operator setting after production. 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 code stored in the plug of the measurement cable gives switching instruction to an engaged MULTI socket

Back in the 1990s,  NIHON KHODEN identified five types of analog hardware (IBP, Temperature, Cardiac Output, FiO2 and Thermistor Respiration) to form a hardware community that linked to only two shared-use sockets which are colored yellow. These yellow flexible community sockets are known as MULTI (short for multi-parameter) sockets. The hardware community, known as a MULTI-PARAMETER UNIT (MPU) which has more hardware than MULTI sockets, was a solution to reduce the number of physical sockets on a panel with limited space area.

 

 

The MULTI sockets demand the use of measurement cables that have valid NIHON KOHDEN digital hexadecimal parameter codes embedded in their connection plugs; this is a mandatory requirement because the sockets are shared for many parameters. The parameter code informs the monitor what internal hardware and software are needed to support a newly plugged-in measurement cable, since there will be more than one type of measurement cables. 

These measurement cables that come with yellow coded plugs are collectively cited as Smart Cables by the manufacturer and each embedded digital parameter code pinpoints the exact type of internal hardware needed by a particular measurement cable.

 

Each MULTI socket selects only one channel of the internal hardware, except for Temperature allowing two channels of hardware to be selected.

Note the hardware mentioned here (Temperature, IBP, Cardiac Output, Thermistor Respiration and FiO2) are linked to the yellow flexible socket from the inside, and not from the outside

 

An external measurement cable with a valid digital code in its plug can make use of corresponding internal hardware if available

Below image shows the MULTI-PARAMETER UNIT (MPU), complete with two yellow MULTI sockets for communal sharing. An external Smart Cable with a valid parameter code selects the needed hardware in the MPU using one of the two MULTI sockets.

 

The design dictates that all yellow MULTI sockets are capable of doing IBP monitoring, each MULTI socket therefore comes attached with a dedicated IBP hardware for its own use.

Principle of operation

A MULTI socket can only access its own dedicated IBP hardware, and makes use of it when an IBP measurement cable is plugged into it. For non-IBP monitoring, both MULTI sockets can access a common hardware pool of Temperature, Cardiac Output, Thermistor Respiration and FiO2 hardware in the MPU.

 

It is observed that the quantity of MULTI sockets in the MPU is not a number that can be decided at will, but corresponds exactly to the number of internal IBP hardware channels that are intended to be placed inside each MPU.

 

Given the large amount of hardware in the MPU block, more MULTI sockets should be added whenever possible, to make good use of the hardware that would otherwise be idling; this is achieved by using an external expansion box filled with more MULTI sockets (plus their dedicated IBP amplifier hardware).

However, the additional MULTI sockets are added using analog interface for integration, and this is limited to a maximum of four sockets to avoid signal deterioration caused by voltage drop and noise.

The MULTI sockets are additionally diverted to be serial ports to save on one physical socket

 

 

The design of the MPU was to minimize the number of physical sockets on a small module, to solve the problem of limited panel space area. By using the MULTI sockets as serial ports helped towards this objective, it was initially only for mainstream CO2 kit sets.

 

 

Shown above is the original label for the two MULTI sockets. It shows the sockets can be used for IBP, Temperature, Cardiac Output, FiO2, Thermistor Respiration, as well as mainstream CO2 serial kit sets. 

Professionally, many are therefore puzzled by the contents of the MULTI-parameter Unit but refrained from asking or faced with a wall of silence, why is this a design that has many internal hardware queuing up to share a limited number of low-cost sockets? The forgotten truth is because it was originally devised to solve the problem of limited panel space area not sufficiently big enough to mount all the necessary connector sockets. When panel space area is more than enough to accommodate all the necessary connector sockets, there is no need for the MPU and related (MULTI sockets/ Smart Cables).

 

It is a waste of money to adopt such a design when the need does not exist. Its continued use regardless of need cautioned us there is more than meets the eye, and a good reason to question its relevance.

 

The manufacturer does not discuss this, but users always know how many channels of internal IBP hardware are supplied

 

Knowing a functional MULTI socket always come with its own dedicated one-channel IBP hardware, a user can accurately tell the number of IBP monitoring hardware channels delivered with a monitor just by tallying the total number of available yellow MULTI sockets. For example, if your monitor is delivered with five MULTI sockets, you had unknowingly paid for five channels of built-in IBP amplifier hardware when you indeed only need one or two.

This being a design rule, and the key word is "functional" because a non-functional (fake) MULTI socket may not need to care about the capability to do IBP monitoring, such a socket can be found on the CardioLife TEC-5600 series defibrillators. The fake socket on said TEC-5600 series defibrillators is just a serial port dressed as a MULTI socket that cannot be used for any other parameter except mainstream CO2 kit sets.

Variations to the basic theme

There are variations to the basic theme, such as

a. doing without use of external expansion box,

b. increasing the number of MULTI-parameter sockets in the MPU,

c. reducing the hardware configured in the MPU.

One should know the overall cost is very high to share connector sockets using Smart Cables

 

The Smart Cables were originally devised only to resolve a product issue, and it is 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. However, putting a lot of hardware into the Saturn module also means more panel space needed for connector sockets.

The Saturn module was intended to be physically small in size

The solution from NIHON KOHDEN for panel space limitation of Saturn module was to introduce a MPU with many hardware sharing two sockets for common use (which are colored yellow).

 

The Saturn module turned to sharing two modified connector sockets as solution to the constraint of space for more sockets

In the Saturn module, the hardware are divided into two blocks, a CONVENTIONAL block and a MULTI-PARAMETER UNIT block.

CONVENTIONAL BLOCK

(These hardware make use of dedicated sockets and ordinary measurement cables)

- ECG

- SpO2

- NIBP

MPU BLOCK with two MULTI sockets

(These hardware only use Smart Cables for connections)

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

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

- Cardiac Output

- FiO2

- Thermistor Respiration

Also using the two MULTI sockets are self-contained mainstream CO2 serial kit sets utilizing the sockets as serial ports

Huge amount of configured hardware in the Saturn module

The MPU design has many hardware sharing only two multi-parameter sockets, this is to solve the problem of limited panel space. This, however, is only the first part of the solution.

More MULTI sockets are needed to make good use of the hardware that would otherwise be idling in the MPU. This is achieved by using an external expansion box filled with more MULTI sockets, each with its own dedicated IBP amplifier hardware.

This is a process of adding more sockets, not more monitoring parameters

The additional sockets are integrated using analog interface, and limited to a maximum of four sockets to avoid signal deterioration caused by voltage drop and noise.

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 placed inside the MPU of the Saturn module except for additional IBP amplifier which must always come with each MULTI sockets.

 

A MULTI socket can only make 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 common pool of Temperature, Cardiac Output, Thermistor Respiration and FiO2 hardware which are placed in the MPU of the Saturn module for sharing.

It is the hardware rule that all MULTI sockets must be capable of doing IBP monitoring, each socket has its own IBP hardware that is not shared

The extension Smart module is therefore a 2-channel IBP box integrating two MULTI sockets for use by the Saturn module. Remember, the analog interface limits the number of additional MULTI sockets to four, and that is two Smart modules.

The MULTI 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; we must remember this is for purpose of minimizing connector sockets on the Saturn module, as it does not make sense outside this context.

Keep in mind, a yellow MULTI-parameter socket is a high-cost serial port when it does not select any internal hardware

 

Staying from the initial arrangement, which was only for mainstream CO2 serial kit sets, the use of serial kit sets using the MULTI socket as serial port are later enthusiastically extended to BIS, 2nd-SpO2, APCO, NMT etc.

This is highly questionable given the fact constraint of panel space area no longer exists in later devices.

The use of Smart Cables for serial communication does give a false illusion of mighty MULTI 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 put it plainly, 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 MULTI sockets when there is no technical need. 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. They are connected as external devices to a monitor.

 

The AE-918P Neuro unit and recorder module are examples that cannot be made into serial kit sets to make use of the MULTI sockets

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

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

The role of the MULTI sockets on the satellite boxes is to compensate for the missing connector sockets on the Saturn module

The two bona fide 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 Life Scope S and Life Scope M monitors were not launched in the US market

The two genuine modular 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 work on the network infrastructure was stopped to avoid incurring unbearable losses.

The exchange of measurement data between main unit and modules was the problem

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 gave up solving 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

 

So, do you really think there are monitoring hardware embedded in the NIHON KOHDEN Smart Cables? This is just a myth and we are going to show you beyond any doubt, there is absolutely no active electronics in the Smart Cables.

The marketing messages "New Modular Technology" and "The Module is in the cable!" are just the wild imaginations of people without the necessary electronics knowledge.

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.

The continued repetitions of an assertion without offering any proof does not make it the truth!

This is just assertion without offering any proof

 

Chip makers need huge demand to justify each of their products, so which chip manufacturer is supplying NIHON KOHDEN the variety of analog chips given the extremely low volume in demand? If we were to open up the plug of a Smart Cable, what do we see? A small PC board is seen soldered 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 NIHON KOHDEN Smart Cable registered with US FDA as a medical device?

Make no mistake, 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 (just like any other manufacturers) 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 J and 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 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 clearly shown being linked internally 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 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 be converted to digital before going to the APU for digital processing. 

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

It is simple-minded to think the use of Smart Cables can actually upgrade a configured monitor to be modular

 

A MULTI socket by itself does not automatically mean all the five types of mentioned parameters are available for measurements; it still depends on which hardware are decided for placement inside the MPU for selection by Smart Cables. The amount of hardware in an MPU is not standardized but customized for each case.

Additional parameter capability can only be added using serial kit sets or via interfaces to external equipment.

When the MTU of a monitor 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 and external interfaces.

Examples of configured hardware and serial kits using Smart Cables

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

It is clear monitors with input units using Smart Cables are still configured monitors. The only advantage of using Smart Cables is to allow sharing of connector sockets (which are of negligible hardware cost), but the cost needed to make use of Smart Cables is far way higher. Customers are just being led into having an unrealistic expectation of what the Smart Cables and MULTI sockets can actually deliver.

 

 

There is no customer value created by sharing cheap connector sockets

 

Elaborate time-sharing applied to things that are expensive (high desirability, an asset), and it is 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. The legitimate resources for a patient monitor to time-share are obviously the analog amplifier hardware and not the connector sockets or switches; this way there would not have any idling costly hardware leading to inefficient use of valuable resources!

 

Time-sharing of a car (an asset) creates value for the customers but time-sharing of a cheap connector socket does not

The next picture shows another manufacturer time-sharing one channel bioamplifier 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.

 

This design only shares the expensive hardware, not the cheap sockets

 

 

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