NIHON KOHDEN Life Scope Smart Cable System (AUG 1998)

Category: Life Scope multi-parameter patient monitors product review


 

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In this knowledge-sharing record we reviewed why NIHON KOHDEN (日本光電 ) Smart Cables & Multi Connector Sockets are outdated, costly and only intended as a distraction to deflect attention away from the fact the manufacturer has lost the ability to make modular monitors. 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 hanging on to?

 

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

NIHON KOHDEN had identified five types of internal 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. Each socket selects only one channel of the hardware, except for Temperature allowing two channels of hardware to be selected.

Principle of Operation

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

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

In addition, the MULTI-parameter sockets double as serial ports without selecting any hardware. This is meaningful when facing the constraint of space but illogical when such constraint is not present.

 

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. Five types of internal analog hardware were found suitable for time-sharing two modified connector sockets, to differentiate them, they were colored yellow and known as MULTI sockets.

 

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.

 

Apart from the higher electronic density, the difference between a single parameter module and a multi-parameter module is the presence of a CPU processor in the latter; the output of a multi-parameter module is thus processed digital data. This new development of distributed processing made it possible for patient data to be stored and moved with the module. Digital modules can also be connected directly to a (proprietary) digital data-exchange network as a node.

 

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

Even occupying a 3-slot width of the module rack, the Saturn multi-parameter module (August 1998) was not big enough to hold all necessary connector sockets

 

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

The method selected by NIHON KOHDEN was to make use of coded measurement cables known as Smart Cables to share two modified connector sockets. The patient monitoring hardware were separated into two blocks in the Saturn module.

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

- ECG

- SpO2

- NIBP

(MULT-PARAMETER UNIT BLOCK with two MULTI-parameter sockets) The 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

Huge amount of hardware had to share 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, utilizing the MULTI-parameter 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.

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

 

The label for the yellow MULTI-parameter sockets on the Saturn module

 

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

 

The two MULTI-parameter sockets on the Saturn module are of course, 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 adding one or two satellite boxes containing two MULTI-parameter sockets each. As this is an analog solution, only a maximum of four MULTI-parameter sockets can be added this way.

Analog solution of up to four MULTI sockets added using external boxes

The image gives an impression of scalability but this is socket scalability, and not parameter scalability sought 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; it is the design a MULTI-parameter socket that does not come with its own IBP hardware is not capable of monitoring IBP.

A MULTI-parameter socket that does not come with its own IBP hardware is not capable of monitoring IBP

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.

Remember,

The sockets make use of their own IBP hardware when an IBP Smart Cable is plugged into the respective MULTI-parameter socket; 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.

The MULTI-PARAMETER SOCKETS HARDWARE RULE:

"Each functional yellow MULTI socket must always come with its own one-channel IBP amplifier hardware"

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 Smart Cables are coded measurement cables

 

There is mis-understanding in the market that there are active electronics in the Smart Cables. The marketing messages "New Modular Technology" and "The Module is in the cable!" are wild 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 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 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.

Clear Proof the IBP amplifier hardware is embedded inside the monitor, 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 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

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 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, however, gives the false illusion of a mighty MULTI socket when 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 use of Smart Cables is configured

 

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

Examples of hardware and serial kits 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 specific input unit or monitor

The input units or monitors making use of Smart Cables are still configured, and the manufacturer has no reason to continue its use. It is just dabbling with distortions and limitations.

There is no customer value created by time-sharing cheap connector sockets

 

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. 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.

 

Only share the expensive hardware, not the cheap sockets

 

 

 

The first and also the last two Modular Monitors made by NIHON KOHDEN

 

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

 

The 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 work on 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 platform meant NIHON KOHDEN was downgraded to be a manufacturer only capable of making configured patient monitors

 

To avoid being seen as a failure, the company tried to hide the fact NIHON KOHDEN had already given up development to make modular monitors. The modular Life Scope S and Life Scope M were still being actively promoted on brochures.

 

Since it could not be for sales improvement, its real purpose was to make believe the company is still capable of making modular monitors.

 

The failed modular monitors that still appeared in this brochure was to hide the truth from the market

With time, more prospects will learn about the truth behind the MULTI-parameter sockets and decline its illogical further use.

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