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

It was a quest back in the 1990s to find the solution for a small module with limited panel space area to mount all the numerous connection sockets needed.

The special need that was looking for a solution

The problem was not unique to NIHON KOHDEN, with the most common solution in the market being to integrate more than one signal onto a socket and using an external splitter to obtain back the original individual signals. The interesting solution from NIHON KOHDEN was, however, to share sockets.

At that time, NIHON KOHDEN development team managed to identify five types of analog hardware (IBP, Temperature, Cardiac Output, FiO2 and Thermistor-method Respiration) to form a hardware group frugally sharing just two sockets that are flexible for group use. The two flexible sockets are known as MULTI (short for multi-parameter) sockets and are specially colored yellow for easy identification.

 

The hardware group and flexible sockets together made up the MULTI-PARAMETER UNIT (MPU), and was only a peculiar design to minimize the number of physical sockets needed on a front panel that had limited space area; thus, the MPU has the unusual characteristics of having more hardware than physical sockets. In other words, it is a design to optimize use of only a fraction of needed physical sockets, and is operating under constraint of limited sockets.

 

We need to view the MPU from the right perspective, to understand that  it is illogical to use when there is no lack of panel space, because we should typically be optimizing the use of expensive hardware instead of the cheap connection sockets.

The MPU was a design to optimize use of only a fraction of needed physical sockets, and is operating under constraint of limited sockets

The flexibility of the yellow MULTI sockets does not come free, and the high price to pay is the mandatory use of custom measurement cables embedded with digital parameter codes in their yellow connection plugs. This is a necessary step because a flexible MULTI socket can expect more than one type of measurement cable; the parameter code is the mean to inform the monitor what internal hardware and software are needed to support each measurement cable that is being plugged in. 

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 and software needed by a particular measurement cable. This is of course no longer smart by today's standard.

 

 

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

As an exception, a MULTI socket can link up to two channels of internal Temperature hardware

 

# Note the hardware mentioned here (Temperature, IBP, Cardiac Output, Thermistor-method 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 group sharing. An external Smart Cable with a valid parameter code selects the needed hardware in the MPU using one of the two MULTI sockets.

 

Based on the fact both MULTI sockets must be capable of doing IBP monitoring, and the logic that IBP hardware should not be more than the number of MULTI sockets, the IBP hardware are not placed in the common pool for sharing; instead, each MULTI socket comes with its own dedicated IBP hardware.

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.

 

Given the large amount of hardware in the MPU block, more MULTI sockets are needed to make good use of the hardware that would otherwise be idling. As illustrated, this is achieved by using an external expansion box filled with more MULTI sockets (plus their dedicated IBP amplifier hardware). It is important at this point to note the purpose is to add more flexible sockets, and not more monitoring parameters.

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

The additional MULTI sockets are added using analog interface for integration, and has to be 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-method Respiration, as well as mainstream CO2 serial kit sets.

 

The small module mentioned earlier was named the Saturn multi-parameter module and the outcome of the MPU solution is as shown below. The Saturn module is housed in a 8-slot module rack, with two expansion boxes next to it; in this arrangement, there were a total of six MULTI sockets (with six channels of IBP hardware) available for use. It is possible to use the Saturn module alone, but the two MULTI sockets would not be enough and at least four MULTI sockets were needed to be practical.

The MPU block without the module rack is meaningless

Unfortunately the digital measurement LAN network for data communication between module rack housing and main unit was unstable with plenty of performance issues, and had to be finally given up for good. This means the first two digital modular monitors (shown below) developed by the manufacturer were failures, and they were withdrawn before FDA registrations in the biggest US market.

 

Note the failed LAN network is not referring to the real-time clinical LAN network for data-exchanges between bedside monitors and central nurse stations. 

 

After the decision to stop development work on the digital measurement LAN network, a younger team of risk-averse engineers took over key positions and decided to keep the MPU, and using the expansion sockets to simulate scalability. This is desperate and unprofessional behavior, because they did it to avoid working on a new measurement LAN; at the same time, they also knew they could get away with it in Japan given the low bargaining power of users in the domestic market.

 

The MPU was just a compromise to accommodate limited panel space area and should never be mistaken as an innovation; without the module rack, the MPU is meaningless and most importantly, there is no demand for socket flexibility outside of Japan.

Professionally, many are puzzled by the behaviors of the MPU but refrained from asking or faced with a wall of silence. The situation was so acute that at one point we had regular telephone calls and letters from undergraduates around the world (excluding Japan) hoping to understand the principle behind the MULTI sockets; we of course could not help them in any way then. When we have ample panel space area, there is no need for such a compromise and the use of an MPU (with its Smart Cables and MULTI sockets) actually becomes a burden and is a waste of money. Its continued use regardless of need is the very reason for its eventual failure.

 

Besides, there are other cheaper and practical ways to solve the problem of insufficient space area on the input panel, such as commonly integrating more than one signal onto a socket and using an external splitter to resolve the signals.

Example of resolving an integrated signal back to original P1 and P2

So far, time-sharing of sockets is only done by NIHON KOHDEN, and avoided by all other manufacturers of patient monitors.

 

Users should first find out how many channels of internal IBP hardware are supplied, it may be much more than what you need

Knowing an authentic 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 functional MULTI sockets, you had unknowingly paid for five channels of built-in IBP amplifier hardware when you indeed only need one or two.

The key word here is "authentic" 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.

 

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 unstable measurement LAN network 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 completely withdrawn from the market due to insufficient processing power.

There are two real-time LAN networks needed by modular monitors, the clinical LAN network linking patient monitors to the Central Nurse Station proved stable but the measurement LAN network linking the modules to the main units of BSS-9800 bedside station/ BSM-9510 bedside monitor was unstable and full of performance issues. This latter unreliable LAN network was abandoned by NIHON KOHDEN without replacement.

There are two real-time LAN network needed by Life Scope S modular monitors

Shown below is the real-time measurement LAN network allowing direct data communication between main unit and individual modules.

NIHON KOHDEN gave up trying to solve the LAN network performance issues between main unit and modules

# Failure to succeed in the measurement data-exchange network infrastructure meant NIHON KOHDEN is no longer a manufacturer capable of making modular patient monitors

With the use of an MTU block, 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 for selection by Smart Cables.

 

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 through the system software of the monitor and has nothing to do with the type of sockets or cables being used.

 

Putting things into perspective, most patient monitoring parameters cannot be added using self-contained serial kit sets. As shown, the AE-918P Neuro Unit or strip chart recorder are examples, and they are not linked using a MULTI socket, but as any external third-party device.

 

When an MPU is not equipped with FiO2 hardware internally, no amount of MULTI sockets is going to provide this measurement capability. The amount of hardware placed in each MPU varies, so is the system support for serial kits and external devices (and powered separately).

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 and external interfaces, the system software. This of course, is the same description as a configured patient monitor

Actual internal hardware composition and system support for serial kits varies for each MPU

Input units and monitors using Smart Cables and MULTI sockets are therefore still configured monitors. It is precisely to forestall the market from making this conclusion that we began to see wild claims of "proprietary Smart Cables technology miniaturizes circuitry found in traditional modules and embed that capability into the cable", which we will refute with details next.

 

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. The customers are paying for the unnecessary higher costs, only to be led into having an unrealistic expectation of what the Smart Cables and MULTI sockets can actually deliver.

# There is no patient-monitoring hardware embedded in the NIHON KOHDEN Smart Cables and this makes a big difference as to how you appraise a monitor that comes with MULTI sockets

We are going to show you beyond any doubt, there is absolutely no active electronics in the Smart Cables. Messages such as "New Modular Technology" and "The Module is in the cable!" are just the wild imaginations of people without the necessary electronics knowledge. These are unsubstantiated marketing messages and the manufacturer should not have condoned it.

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 wild assertion without offering any proof

 

Chip makerIf we were to open up the plug of a Smart Cable, what so which chip manufacturer is taking a big loss to supply NIHON KOHDEN the variety of analog chips given the extremely low volume in demand? s need huge demand to justify each of their products, do we see? A small PC board is seen being 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 non-volatile 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 embedded with a non-volatile digital 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 definitely requires FDA registration. Can you find any stand-alone NIHON KOHDEN Smart Cable registered with US FDA as a medical device? We do not.

 

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.

 

Below service screen shows the MPU knows what cable is being inserted by reading the parameter codes in the plugs. MP1 is identified as an IBP measurement cable, MP2 as a Temperature measurement cable, while MP3 has blank reading (no sign of any measurement cable). The "loop check" shows error for MP1 and MP2 because the two measurement cables do not have any transducer attached.

 

 

Remember, three things are needed to make it work. Each MULTI socket always come with an IBP amplifier, so an IBP measurement cable always work as long as it has an IBP transducer. However, it is not the case when you test the other parameters, internal hardware may or may not be present depending on specifications.

 

# Irrefutable proof the IBP amplifier hardware is located internally, an important fact no longer acknowledged in later monitor manuals

 

The Life Scope BSM-2301 bedside monitor was launched in 2001, 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, which was launched in June 2007. The Life Scope TR bedside monitors also do not provide details, as it was launched in April 2008 (after Life Scope J monitor).

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

 

The block diagram also tells us the MULTI socket of Life Scope BSM-2301 monitor cannot measure Temperature because there is no Temperature hardware internally linked to it, and the sole Temperature amplifier hardware is dedicated to an external jack. The observation is confirmed by the label for the yellow MULTI sockets indicating PRESS/ CO2/ RESP, i.e. no TEMP.

This manual confirms the IBP amplifier and thermistor-method respiration hardware are internal components of the Life Scope BSM-2301 monitor

The MULTI socket when used as a serial port bypasses the internal analog hardware, going straight to the digital APU (Analog-block Processing Unit) and onward to the DPU.  For a parameter using the internal analog hardware, the analog signal needs to be converted to digital before it can go to the APU for digital processing.

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

##  It is perfectly clear there is absolutely no need for any amplifier hardware to be embedded in any of the NIHON KOHDEN Smart Cables  ##

 

Sharing cheap connection sockets does not make economic sense

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). The legitimate resources for a patient monitor to time-share are obviously the analog amplifier hardware and not the 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 optimizes the use of expensive hardware, not the cheap sockets

 

 

What was the reason the manufacturer had to return a physical socket back to users in the case of Life Scope BSM-2300K series bedside monitors?

In 2001, a popular Life Scope BSM-2301K (also known as Life Scope i) was launched and many customers bought it for standalone applications not restricted by system compatibility. It was popular because the Life Scope BSM-2300K series range of monitors were the first in the industry to adopt the new-generation type 8.4-inch high-resolution touchscreen introduced by the electronics industry. The new touchscreen display was a huge jump in touchscreen technology and made for highly-intuitive operation, hence its popularity. The company tried to attribute its popularity to the use of Smart Cables and a flexible MULTI socket. Let's see if this is true.

The portable 8.4-inch Life Scope i (BSM-2301K)

It does not make sense that one flexible socket can do the jobs of three fixed-purpose sockets

To insist the use of Smart Cables, the Life Scope BSM-2301K monitor has a yellow MULTI socket flexible enough for three types of measurements, namely:

 

a. Invasive Blood Pressure

b. Thermistor-method Respiration

c. Mainstream CO2 serial kit sets.

 

Without any use of Smart Cables, all IBP, Thermistor-method Respiration and mainstream CO2 are freely available for carefree use via their respective dedicated sockets. The use of Smart Cables makes things unnecessarily complicated and requires deliberate operator attention and choice to choose one among three (IBP, Thermistor-method Respiration and mainstream CO2), but why introduced a need to choose? 

 

This is obviously unwarranted stress and inconvenience, what is wrong with the conventional way of each doing their own job using three dedicated sockets? If MULTI socket is such a superior proposal, why is the Temperature socket a dedicated one?

Life Scope-i does not have enough physical sockets

The patient monitoring hardware in the Life Scope BSM-2301 bedside monitor are divided into a conventional block and an MPU block. The conventional block uses dedicated sockets and ordinary measurement cables while the MPU block makes use of Smart Cables with different parameter code for different hardware.

CONVENTIONAL BLOCK

- 1-ch TEMP

- ECG

- SpO2

- NIBP

MPU BLOCK with one MULTI socket

- 1-ch IBP

- Thermistor-method Respiration

- <MULTI socket as serial port> Mainstream CO2 Kit Sets

The reality is the shortage of two physical sockets for users, and an avalanche of complaints from the market. Imagine the initial wonder of the flexible socked turned to anger!

Users do not want a poor man's socket

 

The manufacturer was pressured to respond with an updated model, Life Scope BSM-2303K. The solution from new model BSM-2303K was to add a new yellow socket only for IBP.

 

The MPU of the Life Scope BSM-2301K was not designed to take on expansion, and any additional MULTI socket could load the operation of existing MPU, causing it to malfunction. An additional MULTI socket not linked to the MPU is just an independent socket with its own dedicated IBP amplifier hardware. Such was the socket offered for Life Scope BSM-2303K, noting there was a need to recognize the IBP Smart Cable.

 

With a new socket for IBP, the existing yellow MULTI socket can move away from doing IBP monitoring, and just focus on being a serial port for mainstream CO2 or being an amplifier for respiration monitoring using a thermistor transducer. It should be further noted that thermistor respiration

 

It was ironical, a solution relying on an extra dedicated socket for IBP; it was clear the complaints was the result of sharing a flexible socket and the solution offered by BSM-2303K was to return back one of the two missing sockets needed by users.

Market reality forced the manufacturer to return back one of the two missing sockets needed by users

Returning back even more physical sockets to users for Life Scope VS series bedside monitors

Undeterred, NIHON KOHDEN again launched the Life Scope VS series bedside monitors in early 2011, with the BSM-3500 series monitors having two MULTI sockets while the BSM-3700 series monitors have three MULTI sockets.

 

The use of Smart Cables and MULTI sockets has unintentional negative captured value for the users, as can be seen from below illustration. Users of the left monitor (BSM-3500 series with 2 channels of IBP) requires five physical connection sockets but only two yellow shared-use sockets are provided for a 2/5 sharing ratio. The manufacturer cannot provide more than two MULTI sockets because the IBP hardware channels specified for this model is only two, and therefore limited to two flexible MULTI sockets. 

 

Without any use of Smart Cables, all five parameters are freely available for carefree use via their respective dedicated sockets. The use of Smart Cables just makes things unnecessarily complicated and requires deliberate operator attention and a conscious efforts to choose two among the five. This is unwarranted attention, stress and inconvenience. What is wrong with using five dedicated sockets, which is a far superior norm since all parameters are available for connections at any time without hesitation. What user benefit is the manufacturer trying to provide?

 

Similarly, users of the right monitor (BSM-3700 series with 3 channels of IBP) requires six physical connection sockets for carefree use but the manufacturer insists three shared-use sockets are enough. The manufacturer cannot provide more than three MULTI sockets because the IBP hardware channels specified for this model is only three, and therefore limited to three flexible MULTI sockets. 

 

This kind of forceful approach can only happen in a protected Japanese market when users bargaining power is low. It is another matter for the export markets. How does such a dire shortage of connector sockets benefit a user?

These monitors are in dire shortage of physical connection sockets for use, the value captured by users is therefore negative

As expected, users soon found out the small number of MULTI sockets on Life Scope VS bedside monitors are not enough for use. The situation for Life Scope VS series bedside monitors is the same as Life Scope BSM-2301K bedside monitor, customers want their physical sockets back because they need it!

 

These are market forces encountered outside of Japan, and the manufacturer was forced to return back two or four missing physical sockets. The AA-374P expansion unit with four sockets is shown in below picture.

 

If you look at the below picture, it is as good as going back to using dedicated sockets, but at a high cost. The market situation is clear and consistent.

This picture tells us some users want back all their missing physical sockets!

  

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