Life Scope VS (BSM-3500 and BSM-3700 series) bedside monitors from NIHON KOHDEN

Category: Product Review of NIHON KOHDEN Life Scope VS (Venus) series bedside monitors and related. The Life Scope VS series consists of BSM-3521, BSM-3552, BSM-3562, BSM-3572, BSM-3733, BSM-3753, BSM-3763 and BSM-3773.

 

Nihon Kohden Life Scope BSM-3000 series bedside monitors were launched for export in early 2011, the 12.1-inch display range is known as LIFE SCOPE VS BSM-3500 series patient monitors while the 15-inch display range is known as the LIFE SCOPE VS BSM-3700 series patient monitors. Both ranges target mid-acuity sites and use touchscreen display as user interface. The BSM-3500 series was however, only belatedly launched in the USA market in 2016.

 

Configured Life Scope VS (BSM-3000) series models

There are four models with 12.1-inch display (Life Scope BSM-3500 series):

a. Life Scope BSM-3532 bedside monitor

b. Life Scope BSM-3552 bedside monitor

c. Life Scope BSM-3562 bedside monitor

d. Life Scope BSM-3572 bedside monitor

 

The difference among the monitors is the SpO2 algorithm; there are two versions of Nihon Kohden SpO2 algorithm, and the model with the latest version is refrained from sales in the USA market for undisclosed reasons.

 

 

Another four models form the 15-inch Life Scope BSM-3700 series:

a. Life Scope BSM-3753 bedside monitor

b. Life Scope BSM-3755 bedside monitor

c. Life Scope BSM-3763 bedside monitor

d. Life Scope BSM-3773 bedside monitor

The Failed Attempt

To Make Flexible Sockets Relevant

 

The distinctive feature of Life Scope VS bedside monitors is the utilization of two flexible MULTI (short for multi-parameter) sockets for the 12.1-inch models and three flexible MULTI sockets for the 15-inch models. The flexible MULTI sockets are specially colored yellow for easy identification. 

 

Each flexible yellow MULTI socket is capable of measuring

1. IBP

2. 2-Channels of TEMP

3. Cardiac Output

4. Acting as a serial port (accepting BIS, mainstream CO2 and NMT kit sets)

 

Since there are only two channels of TEMP hardware and one channel Cardiac Output hardware internally, the two MULTI sockets on Life Scope BSM-3500 series and the three MULTI sockets on Life Scope BSM-3700 series cannot simultaneously be used for TEMP or Cardiac Output. Note one MULTI socket is connected up to two channels of TEMP.

 

Whether the MULTI socket should be performing the role of (1), (2), (3) or (4) depends on the type of code embedded in the measurement cable being utilized. A flexible MULTI socket must by definition accept more than one type of measurement cable; the parameter code embedded in the plug of a measurement cable is the method adopted to differentiate the cables, and inform the monitor what internal hardware or software are needed for support when a measurement cable is being plugged in. These measurement cables with codes embedded are known as Smart Cables.

 

There is no free lunch, the trade-off is flexibility vs. sufficiency. The consequence of using flexible sockets for general use actually translates to insufficient physical sockets for users, and the deprived users are screaming to have their missing sockets back. How can there be any customer value from socket flexibility when its use creates a shortage of physical sockets for users?

 

What does this mean?

The manufacturer made the grave mistake of rationalizing the flexible MULTI sockets are exhibiting characteristics similar to what modular monitors offer, only to learn painfully from market rejections flexible sockets are actually poor man's sockets. It was unnecessary lessons, and to be expected if you truly understand the working principles.

This MULTI-PARAMETER UNIT (MPU) design from the 1990s

was a trade-off of flexibility vs. sufficiency

 

Veiled in secrecy, NIHON KOHDEN does not explain to the market how they could make sockets that are flexible enough for a total five types of internal hardware, as well as being diverted for use as serial ports for self-contained kit sets. Almost the entire sales and marketing people employed in Japan Head Office have no engineering background, how could any one discuss anything of substance with the distributors or customers (except for prices and deliveries)?

 

Why did the manufacturer forget that these flexible yellow sockets were originally designed for frugal use should be the biggest challenge for the sales teams. 

Here are the historical facts, and the company was looking for a solution to solve the problem of a new type of digital multi-parameter module with only a small front panel that did not have enough space to mount all the needed connection sockets.

 

The small panel space needing a solution

The problem was not unique to NIHON KOHDEN, with the most common and straight-forward solution in the market being to integrate more than one signal onto a socket and using an external splitter to get back the original individual signals.

 

An example of getting back original P1 and P2 from an integrated signal

The thought-provoking solution from NIHON KOHDEN was, however, to frugally share a small number of common sockets. So far, time-sharing of connector sockets is only done by Nihon Kohden and avoided by all other manufacturers of patient monitors.

 

That was in the 1990s,  and NIHON KHODEN development team managed to identify five types of analog hardware (Temperature, IBP, Cardiac Output, Thermistor-method Respiration, FiO2) that could form a hardware group frugally sharing just two flexible sockets for common 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 sockets together made up the MULTI-PARAMETER UNIT (MPU), and was a peculiar design to minimize the number of physical sockets needed on a front panel with a limited space area; thus, the MPU has the special characteristic of possessing more hardware than physical sockets. It is a design to optimize a few physical sockets for frugal sharing, and is therefore operating under constraint of limited sockets.

 

The small module mentioned earlier was named Saturn multi-parameter module and the outcome of the MPU solution is as shown below.

 

The MPU must be viewed from the right perspective, that it is illogical to use when there is no lack of panel space, because we should typically be optimizing use of relatively expensive hardware instead of cheap sockets. In other words, connector sockets which are in abundant supply should not be artificially made a scarce resource; it was a trade-off of flexibility vs. sufficiency, it works in this case because the starting point is not having enough space for sufficient sockets.

 

It was a design to have flexibility over sufficiency, taking advantage of the space constraint for limited sockets

To access each type of hardware, an external measurement cable with a digital parameter code stored in its plug needs to be inserted into one of the two MULTI sockets. 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. Thus, the Smart Cables are mandatory to operate the yellow flexible MULTI sockets.

The digital hexadecimal parameter code is programmed into a non-volatile EEPROM chip (Electrically Erasable Programmable Read-only Memory) mounted on a small flexible PC board and wired to the plug of a Smart Cable at the factory; users cannot change the code after production using settings on the monitors. The Smart Cables are priced highly by the manufacturer, and only the common IBP cable can be sourced from China suppliers at a reasonable price.

 

A non-volatile code is embedded in the plug of a Smart Cable

Each yellow MULTI socket can only link to one channel of the internal hardware, except for Temperature which can accommodate up to two.

 

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

 

 

The hardware mentioned here are linked to the flexible MULTI socket internally,

and not from the outside

 

The hardware are Temperature, IBP, Cardiac Output, Thermistor-method Respiration and FiO2; if specified, the included hardware are placed internally in the MPU before leaving the factory, just like any configured monitor.

 

An external measurement cable with a valid digital code embedded in its plug selects the intended internal hardware (available only if already pre-installed at factory)

 

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 therefore 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 its when an IBP measurement cable is plugged into it. For non-IBP monitoring, both MULTI sockets can access the common sharing pool comprising Temperature, Cardiac Output, Thermistor-method Respiration and FiO2 hardware in the MPU.

 

Given the large amount of hardware idling in the MPU, more physical sockets are needed to make good use of these valuable hardware; yet, only physical sockets in the form of MULTI sockets can access the MPU. The arrangement to add more physical sockets is thus achieved using external expansion boxes filled with two or more MULTI sockets (each with its own dedicated IBP amplifier hardware). It is important at this point to be clear the purpose is to add more physical sockets linking to the existing MPU, and not to add more monitoring parameters.

 

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

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

 

The Saturn module is housed in a 8-slot module rack, with two expansion boxes next to it; altogether there were six MULTI sockets (with six channels of IBP hardware) available for use in this arrangement. It is possible to use the Saturn module alone, but the two MULTI sockets would not be enough.

 

The MPU block without the module rack is meaningless

  

 

A MULTI socket can additionally switch to be a pass-through path

for digital serial data packet

 

Again, like a configured monitor, the MPU can accept use of serial kit sets for capability extension (supported by necessary software). This is done via the parameter code, whose execution means to bypass the internal analog hardware and go directly for digital processing. As is common knowledge, the identity of a serial kit set is contained in the header of the data packet; it will not be processed if the system software does not support it.

 

Using a parameter code, the MULTI socket can switch to be a transit point for any digital serial signal

The purpose of MPU was to solve the problem of limited panel space area, and by using MULTI sockets as serial port does help in furthering the reduction of physical sockets on the front panel. The initial design was to save on one physical socket and meant only for use by the mainstream CO2 serial kit sets.

 

Original label for the MULTI sockets when they were first used

 

Shown above is the original label for the two yellow MULTI sockets. It shows each socket can be utilized for monitoring of IBP, Temperature, Cardiac Output, FiO2 and Thermistor-method Respiration, as well as a pass-through path for mainstream CO2 kit sets.

 

The digital network connecting the main unit to the module racks is known as the measurement network and is illustrated as follows. To add more module rack to the network, it was done using a cascading cable.

 

 

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

 

Do not confuse the failed measurement LAN network with the clinical monitoring network (LS-NET), which is for data exchanges between bedside monitors and central nurse stations.

 

The first two genuine modular monitors were failure

After the decision to stop development work on the measurement LAN network, a younger team of engineers with lessor experience took over key positions. The younger team proved risk-averse and decided to keep the MPU, using the expansion sockets to simulate scalability. This was unexpected, because they did it only to avoid taking the risk of 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. It means all current Life Scope monitors do not have a measurement network to address individual measurement device, which is what that makes a modular monitor different from a configured monitor.

 

The MPU was only a compromise to accommodate limited space area and should never be misrepresented as an innovation; without the module rack, the MPU is meaningless and there is no demand in the market for socket flexibility. In marketing, we first establish there must be a sizeable demand from market research before a product is actually created to meet the detected demand; this process was deliberately bypassed.

 

 

Variations to the basic theme

There are variations to the basic theme, such as

1. doing without use of external expansion box, 

2. increasing the number of multi-parameter sockets in the MPU,

3. reducing the hardware configured in the MPU.

We also found a standalone yellow MULTI socket that does not have any IPB amplifier attached, such a socket can be found on the CardioLife TEC-5600 series defibrillators. The naked yellow MULTI socket on said TEC-5600 series defibrillators is just a serial port dressed as a flexible socket and the system software only supports TG-900P mainstream CO2 serial kit set (P903). 

 

It is important to note the Life Scope VS series was not designed for using expansion units, this was an after-thought and adaptation following massive complaints from users.

 

Smart Cables and the yellow flexible MULTI sockets

do not make a modular monitor

 

A yellow flexible 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 specified must be placed in the MPU before leaving the factory.

 

Additional monitoring parameter capability can be added to an MPU using serial kit sets, supported by system software. However, not all patient monitoring parameters can be added using self-contained serial kit sets. For example, the AE-918P Neuro Unit or strip chart recorder cannot be linked to MPU as a serial kit set.

 

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 configured hardware placed in each MPU varies, so is the system software support for serial kits and external devices. A summary of a few monitors using one to three flexible MULTI sockets are shown in below table. They are just like any configured monitor.

Examples of monitors making use of Smart Cables and MULTI sockets

 

The costs needed to make use of Smart Cables are high, and the customers are paying to be led into having an unrealistic expectation of what the Smart Cables and MULTI sockets can actually deliver.

 

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.

Remember, the constant iteration of the same assertion while avoiding to provide any proof does not make it the truth!

This is just assertion without offering any proof

 

Which chip manufacturer is willing to take a big loss to supply NIHON KOHDEN the variety of analog chips given the extremely low volume in demand? When we opened up the plug of a Smart Cable, we found a small PC board being soldered to some pins of the yellow plug (as shown below).

 

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

 

Upon inspection, the board confirms a cheap non-volatile digital EEPROM chip is being made used to custom code each Smart Cable.

 

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

The same thing can be found in the plug of a compatible IBP cable from China suppliers, they just copied the 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.

 

 

The older manuals (before June 2007) have the details

The details are no longer shown on later manuals, so we take a look at Life Scope BSM-2301 bedside monitor which was launched in 2001; the Service Manual is clear on the design, and 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 obviously do not provide such details, since it was launched in April 2008 after Life Scope J monitor.

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 socket, and to make use of either hardware, a Smart Cable with the correct 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 socket indicating PRESS/ CO2/ RESP, i.e. no TEMP. This block diagram clearly shows there is no reason for any amplifier hardware to be embedded in a NIHON KOHDEN Smart Cable.

 

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

 

The block diagram also shows the path of the serial data packet, bypassing the internal analog hardware and going straight to the digital APU (Analog-block Processing Unit).  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.

 

 

The weak arguments for using the yellow flexible MULTI sockets

have begun to fall apart

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)

 

The key issue is one multi-purpose socket cannot concurrently

do the jobs of three fixed-purpose sockets

  

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

 

1. Invasive Blood Pressure

2. Thermistor-method Respiration

3. Mainstream CO2 (using self-contained 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 bordering on frivolity.

 

It is obviously unwarranted stress and inconvenience for the users, what is wrong with the conventional way of using three dedicated sockets for the job? If MULTI socket is such a superior proposal, why is the Temperature socket a dedicated one?

 

This is compromised usage, like a poor man affording only one physical socket for three types of use

 

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 (dedicated sockets)

- 1-ch TEMP

- ECG

- SpO2

- NIBP

MPU BLOCK (one MULTI socket)

- 1-ch IBP

- Thermistor-method Respiration

- [MULTI socket as serial port] Mainstream CO2 Kit Sets

The reality is the absence of two physical sockets for users. However, one of the parameter for the yellow MULTI socket is thermistor-method respiration, which is for use in the operating room to overcome electrical noise interference; this parameter is therefore not for use in the ward. The real shortage felt by users is one missing physical socket, and they are not hesitating to demand it back. Imagine the initial wonder of a flexible socket turned into an outrage for being shortchanged!

 

Users do not want to be shortchanged with a poor man's socket

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

 

The manufacturer quietly conceded the MULTI socket of Life Scope BSM-2301K

was indeed a poor man's socket

 

The MPU of the Life Scope BSM-2301K was not designed to take on expansion, and any additional MULTI socket will load (disturb) 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 additional yellow socket offered for Life Scope BSM-2303K, noting there was a need to recognize and use the same IBP Smart Cable.

With a new socket for IBP, the existing 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 thermistor transducer.

 

It was ironical, a solution relying on an extra dedicated socket for IBP; there are now two IBP amplifier hardware in the monitor, which was not the original intention. It was clear the complaints was the market rejection of sharing a flexible socket, and the solution offered by Life Scope BSM-2303K was to return back one missing physical socket demanded by users.

 

Market rejection forced the manufacturer to return back the missing socket demanded by users

More physical sockets had to be returned

for later Life Scope BSM-3000 series bedside monitors

  

Undeterred, NIHON KOHDEN again launched the Life Scope VS bedside monitors with the BSM-3500 series monitors (12.1-inch display) having two yellow flexible MULTI sockets while the BSM-3700 series monitors (15-inch display) have three yellow flexible MULTI sockets. The value captured by users for both models are again negative. 

 

The patient monitoring hardware inside the Life Scope BSM-3500 series (12-inch) bedside monitors 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

- ECG

- SpO2

- NIBP

MPU BLOCK with two MULTI sockets

- 2 channels of IBP

- 2 channels of TEMP  [1 MULTI socket = 2-ch TEMP]

- Cardiac Output

- [MULTI sockets as serial ports] BIS, APCO, mainstream CO2 and NMT

Note:

Other third party parameter options are connected using the external device interface, not by using the MULTI sockets.

 

Hardware in the MPU of BSM-3500 series bedside monitors

The patient monitoring hardware inside the Life Scope BSM-3700 series (15-inch) bedside monitors are similarly arranged.

CONVENTIONAL BLOCK

- ECG

- SpO2

- NIBP

MPU BLOCK with three MULTI sockets

- 3 channels of IBP

- 2 channels of TEMP [1 MULTI socket = 2-ch TEMP]

- Cardiac Output

- [MULTI sockets as serial ports] BIS, APCO, mainstream CO2 and NMT

 

Hardware in the MPU of BSM-3700 series bedside monitors

As seen, the difference between the BSM-3500 series and the BSM-3700 series is the addition of one yellow MULTI socket, and of course it also means an additional IBP amplifier hardware.

 

In below picture, 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 availability ratio. The manufacturer cannot provide more than two MULTI sockets because the IBP hardware channels intended for this model is only two, and therefore fixed at 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. This means the manufacturer only wants to place 3 channels of IBP hardware in the MPU of the BSM-3700 series monitors and ignore the user's pain; this kind of forceful approach can only happen in a protected Japanese market where bargaining power of users is low. It is another matter for the export markets, the manufacturer had to respond to the complaints as long there is still interest to export their monitors.

 

How does such a dire shortage of connector sockets benefit a user?

 

These monitors are in dire shortage of physical sockets, and the values captured by users are 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!

 

NIHON KOHDEN reluctantly had to offer two options for solution, the AA-372P Smart Expansion Unit returns two missing physical sockets while the AA-374P Smart Expansion Unit returns four missing physical sockets. The AA-374P expansion unit with four sockets is shown in below picture. 

 

Life Scope VS series bedside monitors were not designed for expansion, although we were not surprised to find expansion units from Life Scope TR belatedly being offered as solution to the intense demand from users for more physical sockets. There are modifications done to the original items since the model names (AA-372P, AA-374P) are different; the makeshift solution makes the bedside monitor look awkward, resembling a product prototypes still undergoing tests.

 

The manufacturer found a way to return back the missing physical sockets

If you look at the below picture, it is as good as going back to using dedicated sockets, but at a high cost. The rejection messages from the market are consistent and enough for the manufacturer to drop the flexible sockets for future products.

 

This picture tells us the manufacturer is returning back to users four missing physical sockets

 

The Life Scope VS monitors were originally not designed for socket expansion, there should be limitations and users may have to pay additional attention to correct socket selections as a result.

 

The yellow MULTI sockets are a burden to the users

 

Manufacturers make their profits by providing product benefits to users but the yellow flexible MULTI sockets are not a benefit to the users.

 

What benefit can it offer users when necessary physical sockets had gone missing?

 

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 switch.

 

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

 

This design optimizes the use of expensive hardware, not the cheap sockets

Beware the Lurking Dangers of

Reading Estimated CO2 values presented as Actual CO2 values

 

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

 

The cap-ONE TG-920P CO2 sensor kit (P907) has very small sensors because of the adoption of semi-quantitative measurements; the method is not commonly seen and many are not aware of the risks of CO2 readings from the semi-quantitative CO2 kit sets. To make matter worse, the semi-quantitative measurements are also being fed to display a flawed continuous CO2 waveform on screen to users.

 

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

 

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

- Life Scope patient monitors

- Vismo patient monitors

- Cap-STAT OLG-2800

- CardioLife defibrillators

- Neurofax EEG machines etc.

 

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

Semi-quantitative CO2 measurements are not

a cheap alternative to quantitative CO2 measurements

  

To save costs, the semi-quantitative kit sets do not make measurement during the inspiration phase. The measurement duty cycle is as shown in below image.

 

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

 

Semi-quantitative measurements are also of low-accuracy type, performed using one IR detector instead of the usual two to save cost.

 

Contrasting, quantitative measurements delivers high accuracy for critical care. To ensure the necessary high accuracy, quantitative measurement employ two IR detectors for simultaneous CO2 measurements at different wavelength for results comparison. CO2 measurements are also being made continuously, which means it can be fed to display a waveform on screen.

 

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

NIHON KOHDEN specification for TG-901T CO2 sensor kit shows even the specified low accuracy of CO2 measurements using semi-quantitative method no longer holds true once CO2 is present during the inspiration phase. This is because the actual CO2 levels can be much higher.

 

In other words, it is an acknowledgement that:

 

1. The measured CO2 value is not the true CO2 level,

 

2. The true CO2 level = [measured CO2 value + x]

where x is an unknown CO2 value carried forward from the inspiration phase. Only when x = zero will the measured CO2 value reflect the true CO2 level.

 

It is unprofessional to specify a measurement tolerance

when there is an unknown in the equation

 

This is not professional specifications

 

As seen from the duty cycle, there is no measurement being made during the inspiration phase, how do the users verify the measured CO2 value is the true CO2 level?

 

The specified measurement tolerance is conditional on this assurance and the CO2 values shown to users are therefore wrong and misleading! Each semi-quantitative CO2 measurement is in fact only an estimation, because the users have no way to tell if the value of x is indeed zero. It is only assumed to be zero by the manufacturer.

In addition, since the users are not alerted on screen that there is no CO2 measurement being made during the inspiration phase, they are unknowingly made to take on unnecessary risks.

 

 

Semi-quantitative measurements

are for selective uses with known risks

 

The design cannot be used in a general way, only on a selective basis with known risks. For example, semi-quantitative methodology can be used to estimate the value of etCO2 for airway tube placement confirmation. It cannot be a feed for continuous waveform display.

 

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

It is a flawed continuous CO2 waveform when fed by a source

that does not have the ability to make continuous measurements

 

The manufacturer ended up carelessly displaying a flawed continuous CO2 waveform using semi-quantitative measurement kits that do not have ability to make continuous measurements. This is unacceptable, as the manufacturer is subjecting the monitored patients and users to dangerous misinterpretation risks.

 

When there is no measurement being made during the inspiration phase, the displayed CO2 level is forced by the manufacturer to a clean zero by design. Is the manufacturer aware that a zero CO2 reading on the waveform means zero measured value, not that you are not measuring? This is basic professional knowledge.

 

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

 

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

The dangerous assumption

that expiratory upstrokes always start from zero CO2 level

 

Below image confirms it is dangerous to assume the CO2 level during the inspiration phase is always zero.

 

Dangerous assumption the manufacturer is making

 

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

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

 

What you should also know about fully-quantitative type

miniaturized mainstream CO2 sensors

 

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

 

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

 

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

 

Common defects of a TG-970P CO2 sensor kit (P909), reflecting an impractical design.

The fragile miniaturized CO2 sensors are clearly of poor design,

and easily broken

 

The key point is, it does not last

The mandatory need for network isolation units when networking

Life Scope VS bedside monitor connecting to a real-time LAN network is a danger to the patient, and mandatory to observe patient electrical safety by using a network isolation unit to protect the vulnerable patients.

 

NIHON KOHDEN network isolation transformer

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

For telemetry networking, the ZS-900P Telemetry Transmitter is optionally required. This is required specification for the Japanese domestic market due to government subsidy but unpopular outside of Japan because of cost.

 

Telemetry networking is not popular outside of Japan due to absence of government subsidy

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