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 an identification digital hexadecimal code on its yellow plug to engage a similarly-colored yellow sockets known as MULTI-parameter (or MULTI) sockets.

 

 

The digital code is stored in an EEPROM chip mounted on a small flexible PC board electrically wired to the pins of the cable plug. The hexadecimal code in the EEPROM is inserted at the factory and not allowed to change after production. It is actually 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 that can be linked from the inside onto flexible common-use sockets which are colored yellow. These flexible sockets are known as multi-parameter sockets or MULTI in short.

 

The identified hardware are IBP amplifier, Temperature, Cardiac Output, FiO2 and Thermistor Respiration. To make use of these internal hardware, an external cable with a valid digital code on its plug needs to be inserted into one of the multi-parameter sockets. These measurement cables with embedded codes in its plugs are collectively cited as Smart Cables by the manufacturer and the codes are also known as parameter-selection codes. Each multi-parameter 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

The configured hardware using the Smart Cables are grouped into an electronic block known as MULTI-PARAMETER UNIT (MPU), complete with a small number of yellow MULTI-parameter sockets. The number of flexible yellow sockets in the MPU cannot be arbitrary, but must correspond to the number of IBP hardware channels that are intended.

It is the design rule that all yellow MULTI-parameter sockets must be able to do IBP monitoring, each socket therefore comes with its own exclusive IBP hardware to adhere to this rule. The term "exclusive" means the IBP hardware attached to each yellow socket is not intended for sharing by other multi-parameter sockets.

Principle of operation

A MULTI-parameter socket makes use of its own exclusive IBP hardware when a measurement cable with an IBP code is plugged into it. For non-IBP monitoring, the socket can access a common pool of Temperature, Cardiac Output, Thermistor Respiration and FiO2 hardware in the MULTI-Parameter Unit, which are designed for sharing by all MULTI sockets.

 

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

However, the additional multi-parameter sockets are added using analog interface, and limited to a maximum of four to avoid signal deterioration caused by voltage drop and noise.

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 MULTI-parameter sockets for availability to users? The truth is because it was originally devised to solve the problem of limited panel space to mount many needed connector sockets! When panel space is enough to accommodate all the necessary connector sockets, it is just a waste of money to adopt this design; clearly, its continued use regardless of need indicates there is more than meets the eye.

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

 

Knowing a functional MULTI-parameter socket always come with its own exclusive 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-parameter sockets. For example, if your monitor is delivered with five functional yellow MULTI-parameter sockets, you had paid for five built-in IBP hardware channels 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-parameter 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-parameter 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 MULTI-parameter Unit with many hardware sharing two yellow sockets for common use.

 

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 normal block and a MULTI-parameter Unit.

ORDINARY BLOCK

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

- ECG

- SpO2

- NIBP

MULTI-PARAMETER UNIT with two yellow 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-parameter 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. However, this is only part of the solution.

More multi-parameter sockets are of course needed to make good use of the hardware that would otherwise be idling in the MPU. This is done by using an external expansion box filled with multi-parameter sockets, each with its own IBP amplifier hardware.

Analog solution of adding more sockets, not more monitoring parameters

The additional sockets are added using analog interface, and limited to a maximum four 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 configured in the Saturn module except for additional IBP amplifier which must always come with each MULTI-parameter sockets.

 

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 common pool of Temperature, Cardiac Output, Thermistor Respiration and FiO2 hardware already embedded in the the MULTI-parameter Unit of Saturn module.

It is the hardware rule that all MULTI-parameter socket must be able to do IBP monitoring, each socket has its own IBP hardware that is not shared

The extension Smart module is therefore a 2-channel IBP box adding two multi-parameter sockets for use by the Saturn module. Remember, the analog interface limits the number of Smart modules that can be added to the Saturn module to two, making a total of four additional multi-parameter sockets.

The 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; we must remember this is for purpose of minimizing connector sockets on the Saturn multi-parameter 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

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 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 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 manuals

The Saturn module, together with two satellite boxes adding 4 channels of IBP to the Saturn module is shown below. 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 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 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 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 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-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

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

 

Additional monitoring parameter capability can be added to a configured monitor using serial kit sets or via interfaces to external equipment, but these are realized by the system software of the monitor and not by the type of connector sockets or cables.

 

With the use of a MTU block, 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 by Smart Cables.

 

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. It is just a magic show and illogical for practical use; we are therefore justified to look for the real motive behind its continued use.

 

 

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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