Medical Devices Sanity: NIHON KOHDEN Life Scope PT (BSM-1700 Series) Transport Monitor and Data Non-Continuity

Category: NIHON KOHDEN Life Scope TR (BSM-6000 series), Life Scope PT (BSM-1733, BSM-1753, BSM-1763, BSM-1773), Life Scope Telemetry, Life Scope J (BSM-9101) bedside monitor, Nihon Kohden SpO2 algorithm type, semi-quantitative Waveform, Host Monitor, MULTI connectors, discontinuous seamless monitoring, IntelliVue X2, patient monitoring

Life Scope PT transport monitors are derived from the bulky input units of Life Scope TR (BSM-6000 series) bedside monitors

These 5.5-inch transport monitors are adapted from the three types of multi-parameter Input Units designed initially for configured Life Scope TR (Life Scope BSM-6000 series) bedside monitors.

Both transport monitors and Input Units are now extended for use by Life Scope G9 (CSM-1901) bedside monitor, Life Scope G5 (CSM-1500 series) bedside monitors, and Life Scope G7 (CSM-1700 series) bedside monitors.

The transport monitors were realized by the addition of touch-screen, storage memory and rechargeable battery to the existing Input Units, doing away the need to attach it to a portable monitor during patient transfer; this means Life Scope PT transport monitor first act as an Input Unit to a Host Monitor, and upon detachment as input unit, becomes a transport monitor. The design is an attempt to imitate the Philips IntelliVue MMS X2, but with an unfavorable difference. This is because it is not a system design from scratch, the transport monitors when detached from the host monitors have no wireless link to the central monitor! This legacy flaw at the system level will be discussed in details later in this same article.

Configured Input Units made into Transport Monitors imitating Philips IntelliVue MMS X2

It is strange that before the Life Scope PT transport monitor, Nihon Kohden only exported three types of Input Units that can be used on Life Scope TR (BSM-6000) bedside monitors, but when it comes to the Life Scope PT transport monitor, there are now four models. The reason is due to the older version of Nihon Kohden SpO2 algorithm offered in the US market.

Refer to below image, the AY-663P Input Unit uses NIHON KOHDEN SpO2 algorithm while AY-653P Input Unit uses Nellcor OxiMax SpO2 algorithm, and the AY-633P Input Unit the Masimo SET SpO2 algorithm. Only input units using Nellcor and Masimo algorithms are available in the US market, so there should be a reason the prevailing version of NIHON KOHDEN SpO2 algorithm is not offered in the US market.

Similarly configured input units with different SpO2 algorithms; what are these yellow connection sockets?

The four models of Life Scope PT (BSM-1700 series) transport monitors are:

1. Life Scope BSM-1773 transport monitor (Nihon Kohden older version SpO2 algorithms)

2. Life Scope BSM-1763 transport monitor (Nihon Kohden current version SpO2 algorithms)

3. Life Scope BSM-1753 transport monitor (OEM SpO2 board supplied by Nellcor)

4. Life Scope BSM-1733 transport monitor (OEM SpO2 board supplied by Masimo)

Life Scope PT transport monitor with telemetry transmitter

The only difference among the four models is the SpO2 algorithms.

The four types of Life Scope PT transport monitors

The two models (BSM-1773 and BSM-1763) on left side of above table make use of Nihon Kohden SpO2 algorithms but they have different version of SpO2 algorithm. The SpO2 algorithm for the USA market and ex-USA market are not the same version, so it is a puzzle why the latest version should be refrained from use in the USA market by the manufacturer.

While NIHON KOHDEN is recognized for developing the non-invasive SpO2 measurement principle in the 1970s, the company is no longer in the forefront of non-invasive SpO2 technology. The two models on the right side of above table (BSM-1733, BSM-1753) are using SpO2 OEM boards supplied by Masimo and Nellcor respectively.

Some sales and marketing teams are very excited about the bigger screen of Life Scope PT in the market but overlooked their lack of knowledge why the configured multi-parameter Input Units of Life Scope TR (BSM-6000 series) bedside monitors are so different and big from the competitions that a 5.7 inch screen can just be mounted on one of the side!

Why are the Input Units of Life Scope TR so big and different from the competitions?

They should wonder why is the shown input unit so big and different from other competitors? The reason is because they are configured with much more internal hardware than any competitor in the market. Try holding it with one hand and see how heavy it is compared to other competitors in the market.

The shown input unit is in fact, heavily loaded with patient-monitoring hardware inside, and avoided for mention in product communication to the market, intentionally done to hide the fact the input units are not modular in design

Many internal hardware are not made clear in product communication to the market

The prominent feature of the AY-663P Input Unit (or Life Scope PT transport monitor) is the utilization of flexible MULTI (short for multi-parameter) sockets that are for frugal sharing use by a group of internal hardware, and these sockets are colored in yellow.

The yellow MULTI sockets can be utilized for IBP, Temperature, Cardiac Output, FiO2 and Thermistor-method Respiration, plus a variety of digital serial kit sets. There is no free lunch, so what cost are involved to achieve the flexibility of the yellow MULTI sockets? Ordinary measurement cables cannot be used on such flexible sockets, and the high price to pay includes mandatory use of custom measurement cables embedded with digital parameter codes in their yellow plugs. This is a necessary step because a flexible MULTI socket accepts more than one type of measurement cable; the parameter code in the plug is the mean to inform the monitor what internal hardware and software are needed when a measurement cable is being plugged in.

The end result of using flexible MULTI sockets for general use actually translates to lack of physical sockets for users, and they have no qualms about demanding it back! We need to ask what is the use of having socket flexibility when it creates a shortage of physical sockets for users?

# Why the peculiar MULTI-PARAMETER UNIT (MPU) design from the 1990s should never be deployed when out of context

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, so there are plenty of "company secrets" that should not be discussed with the distributors or customers.

Here are the relevant facts, and it was just a quest to find the solution for a small module with a front panel that did not have enough panel space to mount all the numerous connector sockets needed.

The special need that was searching 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 a small number of common sockets.

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 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.

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 a 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 therefore operating under constraint of limited sockets.

We need to view the MPU from the right perspective, to understand that it is illogical to use it 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.

It was a design to optimize use of only a fraction of needed physical sockets, and is therefore operating under constraint of 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 custom 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 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 Temperature hardware

# Note the hardware mentioned here (Temperature, IBP, Cardiac Output, Thermistor-method Respiration and FiO2) are linked to the flexible MULTI socket internally, and not from the outside

An external measurement cable with a valid digital code embedded in its plug selects the intended internal hardware (only 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 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 hardware pool comprising Temperature, Cardiac Output, Thermistor-method Respiration and FiO2 hardware in the MPU.

Given the large amount of idling hardware in the MPU block, more MULTI sockets can be added to make good use of these available hardware. As illustrated, this is achieved by using an external expansion box filled with additional MULTI sockets (each with its own dedicated IBP amplifier hardware). It is important at this point to note the purpose is to add more flexible sockets linking to the existing MPU, it is not to add more monitoring parameters.
This is a process of adding more flexible sockets, not more monitoring parameters

The additional MULTI sockets are integrated using analog interface, 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 more physical socket
A MULTI socket can be diverted to be a serial port by bypassing the internal analog hardware

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

Shown above is the original label for the two MULTI sockets. It shows each socket can be utilized for monitoring of IBP, Temperature, Cardiac Output, FiO2 and (Thermistor-method) Respiration, as well as diverted to be a serial port for mainstream CO2 serial kit sets.

The small module mentioned earlier was named 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 housing is meaningless

Unfortunately, the digital 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 digital modular monitors (shown below) developed by the manufacturer were failures, and they were withdrawn before FDA registration 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 only 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 panel space on the input panel, such as commonly integrating more than one signal onto a socket and using an external splitter to resolve back the original signals.

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

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

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.

In the AY-663P, AY-653P, AY-633P Input Units (or Life Scope PT transport monitors), 3 channels of IBP amplifiers, 2 channels of Temperature, one channel each of Thermistor Respiration, FiO2 and Cardiac Output are configured in the MPU for use by Smart Cables.

As the hardware in the AY-663P, AY-653P and AY-633P Input Units are extensive, they were designed to work with external expansion boxes (such as AA-674P expansion box or the expansion panel on the JA-674P Data Acquisition Unit) which can add two or four additional MULTI sockets to make use of the hardware already placed in the MPU of input units.

Users should first find out how many channels of internal IBP hardware are supplied, it is most likely more than what you need. Knowing a true yellow MULTI socket always come with its own dedicated one-channel IBP hardware, a user can accurately tell how many IBP monitoring hardware channels are supplied with any monitor, just by tallying the total number of available MULTI sockets. For example, if your monitor is delivered with five functional yellow MULTI sockets, you had unknowingly paid for five channels of built-in IBP amplifier hardware when you may indeed only need one or two.

The key word here is "true" because a fake multi-parameter socket does 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 yellow MULTI socket on said TEC-5600 series defibrillators is just a serial port dressed as a communal socket that cannot be used for any other parameter except mainstream CO2 kit sets.

The digital hexadecimal parameter code is programmed into a non-volatile EEPROM chip (Electrically Erasable Programmable Read-only Memory) mounted 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. It is not costly 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 non-volatile digital parameter code is embedded in the plug of the measurement cable

What was the reason the manufacturer had to return back a physical socket 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)

# How is it possible 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?
There are not enough physical sockets for users

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 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 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 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 result of sharing a flexible socket and the solution offered by Life Scope BSM-2303K was to return back one of the two missing physical sockets needed by users.
Market reality forced the manufacturer to return back one of the two missing sockets needed by users

# Only to be pressured to return back even more physical sockets to users for the later Life Scope VS bedside monitors

Undeterred, NIHON KOHDEN again launched the Life Scope VS bedside monitors in early 2011, with the BSM-3500 series monitors having two MULTI sockets while the BSM-3700 series monitors have three. The value captured by users for both models are again negative.

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 specified 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?

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

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 IBP hardware channels specified for this model is three, and therefore fixed at three flexible MULTI sockets.

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 must do something as long as there is still intention to export their monitors. How does such a dire shortage of connector sockets benefit a user?

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 outside of Japan; under pressure, NIHON KOHDEN had to offer options of AA-372P Smart Expansion Unit to return two missing physical sockets and AA-374P Smart Expansion Unit to return four. 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 rejection message from the market is consistent.

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

What An Impressive Magic Show

About 9 years after the launch of modular Life Scope S Bedside Station, a new Life Scope J (BSM-9101) purporting to be a modular bedside monitor was released for export.

Instead of working on a new measurement LAN as replacement, what we saw was a bizarre attempt to hide the missing technology platform essential for modular monitors. The Corporate Director spearheading the Life Scope J bedside monitor project was finally asked to step down from the board in 2006, and had to leave the company at the same time because of the seriousness of his incompetence (this happened before June 29, 2006).

From subsequent behavior, we know the manufacturer had already crossed the Rubicon, and there was no turning back on Life Scope J bedside monitor. Major ramifications from the market, however, cannot be avoided when the real situation is fully understood by the market.

Life Scope J (BSM-9101) Bedside Monitor was finally released in June 2007 (after what was an unusually long delay, apparently as a result of new information curtailment policy and staying vague).

The processing main unit for Life Scope J bedside monitor was MU-910R, complete with an AY-920PA Input Unit similar in structure to the Saturn module. It is important to ask when will they end this all?

Just like the Saturn multi-parameter module, the AY-920PA Input Unit contains huge amount of hardware and continued to use an internal MPU sharing four yellow flexible MULTI sockets. These four yellow MULTI sockets are of course not enough, additional sockets can be integrated to AY-920PA Input Unit using an external AA-910P expansion box. The interface between AY-920PA and AA-910P is analog, and the number of yellow sockets can be added was again limited to four to avoid signal degradation.

The patient monitoring hardware inside the AY-920PA Input Unit 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
- 2 channels of Temperature
- ECG
- SpO2
- NIBP

MPU BLOCK with four MULTI sockets
- 4 channels of IBP
- 6 channels of Temperature (3 MULTI sockets = 6-ch TEMP)
- Cardiac Output
- Thermistor-method Respiration
- FiO2
- <MULTI socklets as serial ports> Mainstream CO2, 2nd SpO2, BIS and NMT

Note:
Other options such as Sidestream CO2, Multi-gas, EEG etc., are connected using external device interface, and not via MULTI sockets.

# The configured Life Scope J Bedside Monitor was found masquerading as a modular monitor

The market communication was meticulously executed to portray Life Scope J (BSM-9101) bedside monitor as a modular monitor when the manufacturer is fully aware it is a true-blue configured monitor.
Life Scope J bedside monitor appears to be a modular monitor in this brochure image

In above brochure image, Life Scope J (on the right) shown using 12 yellow MULTI sockets was an impossible configuration; there was obvious intention to hide the fact only four MULTI sockets can be added using an external box. If 12 MULTI sockets are realized, it also means 12 channels of IBP; this is a monitor, not polygraph.
This is a fake configuration, since AY-920PA Input Unit can only make use of one AA-910P expansion unit

In the next picture, you can see the AY-920PA Input Unit was designed in a shape that when combined with the recorder make Life Scope J (BSM-9101) bedside monitor (left) closely resemble the Life Scope S (BSS-9800) bedside station with a 8-slot module rack filled with modules (right).
Life Scope J bedside monitor was configured while Life Scope S bedside station was modular

In other words, Life Scope J bedside monitor was specially designed in appearance to look like an updated version of the Life Scope S bedside station.

The components making up a Life Scope J (BSM-9101) bedside monitor system is shown in next picture. The connection from MU-910R Main Unit to AY-920PA Input Unit is using the same connector type utilized by BSS-9800 bedside station; the old modular racks can therefore theoretically be daisy-chained to the AY-920A Input Unit.

Why offer the module rack that caused the failure of both Life Scope S bedside station and Life Scope M bedside monitor? The shown module rack and old modules are not merchantable since there was no longer any new module under development!
Life Scope J Bedside Monitor is not a bona fide modular monitor

The purpose of the questionable module racks and old modules were there for the powerful association of Life Scope J with modular monitors in the minds of the intended audience (including foreign employees). It was a powerful way to get the audience to nod their heads when making claim that the Life Scope J is a modular monitor. It was a magic show.

Without offering a new network infrastructure for measurement data, connecting to the old module rack was just a pretense, and can no longer be feigned after they were discontinued without replacement.
There was no replacements for the discontinued module rack and modules

The Input Unit and expansion box of Life Scope J bedside monitor is only the equivalence of Life Scope S modular monitor's Saturn module and expansion boxes.
Life Scope J bedside monitor has to depend on external device interface for real expansion

Without a measurement LAN network, The Life Scope J (BSM-9101) Bedside Monitor main unit cannot reach any individual module, including the recorder. If you inspect the connection, the recorder can only be connected to the main unit by direct wire. External device interface on the AY-920PA Input Unit or on MU-910R Main Unit links to third party devices to add more monitoring parameters, in addition to using serial kit sets. It is just like any configured patient monitor in the market.

Life Scope TR Bedside Monitors

After Life Scope J monitor, NIHON KOHDEN went on to develop the Life Scope TR (BSM-6000 series) monitors; they are versions of Life Scope J bedside monitor using a built-in display, instead of an external display. The development team continued to shy away from the difficult task of working on a new measurement LAN to do away with the yellow MULTI sockets as camouflage. Life Scope TR was thus a decision to continue investing in weakness, throwing good money after bad. Life Scope G9, Life Scope G5 and Life Scope G7 bedside monitors inherit the input units from the Life Scope TR series bedside monitors.

In other words, the magic show continues.
Life Scope TR main unit can hold one input unit plus an attached expansion box

Compared to Life Scope J bedside monitor, there are more input units being offered for choice but no genuine scalability of patient-monitoring parameters.
Life Scope TR bedside monitors have more than one type of Input Unit to choose from

Since the Life Scope PT transport monitors are versions of Life Scope TR Input Units with a screen, so let's take a closer look at the AY-663P Input Unit shown below, it needs at least ten physical sockets for carefree use but the manufacturer can only provide three yellow MULTI sockets on a ratio of 3/10 availability ratio. This means only three of the ten connectable cables can plug into the input unit at any one time. The input unit is so short of physical sockets, why would anyone need such a skewed input unit? This is worse than the Life Scope VS bedside monitors, so the reaction from users is obvious.

A skewed input unit delivering pain of insufficient physical connection sockets

The BIS, Second SpO2, ETCO2 and NMT parameters are self-contained kit sets with processed digital serial data using the input unit only as a link to the monitor, they have no reason to queue for the scarce yellow MULTI sockets.

The next item to appear is an external box (AA-674P) which comes with four MULTI sockets, which is meant to add additional MULTI sockets to supplement the inadequate three on the AY-663P Input Unit.

Due to use of analog integration, the number of MULTI sockets that can be integrated to AY-663P Input Unit is limited to four sockets to avoid signal degeneration. The maximum number of MULTI sockets intended for use by AY-663P Input Unit is therefore seven.

The image below shows a Life Scope TR bedside monitor main unit (on the right) with the input unit (AY-663P) on the immediate left of its side. On the extreme left is the satellite box with four additional MULTI sockets (AA-674P) that can be integrated to the MPU of the AY-663P Input Unit.

The AA-674P box adds four physical connection sockets together with four channels of IBP hardware to AY-663P input unit

It is clear the three physical MULTI sockets on the AY-663P Input Unit are not enough for use, which means the customers have to buy the AY-663P Input Unit and AA-674P expansion box in one go. The act of adding four MULTI sockets using the AA-674P expansion box also adds another four IBP hardware to the three already configured in AY-663P Input Unit. Do you really need seven channels of IBP hardware? This is indeed quite rare a requirement, and you should not be buying more than what you need.

The limitation of four additional MULTI sockets also means it is not possible for the AY-663P Input Unit to make use of two AA-674P expansion boxes; be sure to ask for a field demonstration to verify the truth if any salesman insists on this possibility. By the way, that means eleven channels of IBP monitoring!

In the case of Life Scope PT transport monitor, the four additional MULTI sockets are made available on the JA-694PA DAU. In the case of Life Scope G5 bedside monitor, the AA-174P expansion unit can also be used.

Elaborat

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

Case study using Philips modular monitors

The AY-663P Input Unit together with AA-674P expansion box corresponds to a Philips MMS module with an extension. These are operating at the configured level, not modular, and the extension or expansion are made using analog interface.

The Philips MMS modules (initiated by Hewlett Packard) are however additionally capable of being linked to a real-time measurement LAN network using Ethernet

Remember the HP Agilent M3/M4 portable monitor?

While the Philips MMS modules can be upgraded using analog extensions, each also has an IP address for linking onto the digital Measurement Ethernet LAN network, allowing direct communication between the main unit and each module. Scalable monitoring is achieved by slotting individual modules into a module rack linked to the Measurement LAN Network; in the same way, expensive modules can be shared.

On the contrary, NIHON KOHDEN failed to realize a working digital Measurement LAN Network and the Life Scope TR Input Units do not have IP addresses for digital networking. There is no way to scale monitoring parameters or sharing expensive modules using digital networking, only via serial kit sets or linking to independent devices using custom interfaces.
The Philips MMS module (and extension) serves as the basic module and can be expanded using a digital measurement LAN

# It is wishful thinking to believe the use of Smart Cables and MULTI sockets upgrades a configured monitor to be modular

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". The manufacturer is saying the hardware are in the cable and therefore the design is modular in nature; we have explained the cable is just the code to select the hardware and software which are already embedded inside the monitor, and can reference the official block diagram details as proof. We show beyond any doubt, there is absolutely no need for active electronics in the Smart Cables.

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.

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 wild 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).

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

Upon inspection, the PC board confirms a cheap non-volatile digital EEPROM chip is being made used of 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. Do you really think they managed to put an active IBP amplifier inside?

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.

Rem

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

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 above block diagram means there is no reason for any amplifier hardware to be in the NIHON KOHDEN Smart Cables

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.

The huge amount of hardware inside the AY-663P Input Unit is the reason for its size
The patient monitoring hardware inside the AY-663P Input Unit 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
- 2 channels of Temperature
- ECG
- SpO2
- NIBP

MPU BLOCK with three MULTI sockets
- 3 channels of IBP (3 MULTI sockets = 3-ch IBP)
- 2 channels of Temperature (1 MULTI socket = 2-ch TEMP)
- Cardiac Output
- FiO2
- Thermistor-method Respiration
- <MULTI sockets as serial ports> BIS, 2nd SpO2, mainstream CO2, NMT

The hardware in the MPU block

In the AA-674P expansion box, each MULTI socket comes with its own IBP hardware and can access the common hardware pool in the MPU of AY-663P Input Unit.

The hardware in the AA-674P expansion box

Instead of using AA-674P expansion box, the additional four MULTI can also be arranged horizontally using the AA-174P expansion box. This is the version used by Life Scope G5 bedside monitor.

The hardware in the AA-174P expansion box are similar to AA-674P expansion box

Another way to add four MULTI sockets to the AY-663P Input Unit or Life Scope PT transport monitor is the use of the JA-694P Data Acquisition Unit. It is of course not possible to add more than four sockets in total due to the interface limitation.

A standalone BSM-1700 monitor can only have Telemetry or wired Ethernet link to the Central Monitor

Note a BSM-1700 monitor can only link to a central monitor using telemetry or wired Ethernet when not acting as an input unit. It is important to know the BSM-1700 transport monitor cannot communicate directly with a Central Monitor via WiFi. Though the BSM-1700 monitor can make use of a telemetry transmitter, there is no way to mount the optional ZS-900PK transmitter when the monitor is operating as an Input Unit to a host monitor.

Life Scope PT transport monitor has no user benefit in a stand-alone operation

A stand-alone BSM-1700 monitor (i.e. when not acting as input unit to a host monitor) can be connected to a Central Nurse Station via the LS-NET real-time data network using wired Ethernet provided by the SC-170R AC Cradle.

Shown below is how a BSM-1700 monitor resting on an SC-170R AC Cradle is connected to the LS-NET patient monitoring network. The Ethernet socket is at the rear of the cradle and it is mandatory to protect the patient with an Ethernet isolation unit when connecting to a network.

The SC-170R AC Cradle does not make sense outside of Japan

When a BSM-1700 monitor is placed on a SC-170R AC Cradle, its function is only an ordinary stand-alone monitor but the price of a purpose-built BSM-1700 is twice that of an ordinary monitor with equivalent monitoring capability. Apart from cost, there is another problem.

# Outdated Clinical Network Protocols with no indication the company is capable of fixing it soon

The failure of the two modular monitors (BSS-9800, BSM-9510) was a big setback to developments efforts, as many experienced engineers were being sidelined. The clinical network protocols, which define behaviors for communications on the network connecting bedside monitors and central monitors, is now only in maintenance mode and lacking new initiatives.

The Life Scope Real-time patient monitoring Ethernet Protocols only work when the monitors do not move from place to place. Before the SC-170R, the monitors were always fixed to each location and patient would only be transferred from one monitor to another. With the advent of the SC-170R, the assumption no longer holds true and the old protocols need a fundamental revamp to accommodate patients moving together with their monitors while maintaining links to a central monitor.

Thus, the SC-170R AC Cradle is only meaningful for telemetry use in Japan where there is government subsidy for monitors making use of telemetry, one of entry barrier for foreign competitors. The SC-170R AC Cradle provides the power for a BSM-1700 monitor placed on it, as well as charging its internal battery for transport use. There is no similar subsidy system for telemetry monitor outside of Japan.

This means although a BSM-1700 monitor placed on a SC-170R AC Cradle is easily released mechanically by a lever, the BSM-1700 monitor cannot be used as a "PICK AND GO" monitor due to the outdated LS-NET clinical networking protocols.

The manufacturer had reported there would be patient location confusion at the Central Nurse Station for such a setup.

Life Scope PT placed on a SC-170R AC Cradle causes confusion when used with a Central Monitor!

In the above monitoring setup with a Central Monitor, the Central Monitor would still remember the last bed locations even if the patients (together with the Life Scope PT monitor) had been swapped between BED ONE and BED TWO. This is serious matter.

Below shows part of the relevant Note to sales teams. There is no clear indication the company is capable of fixing it yet.

Instruction not to link the AC Cradle to a central monitor

*# The LS-NET patient monitoring protocols is far outdated without an overhaul*

What the LS-NET network protocols needs is an overhaul

What is the reason Philips IntelliVue MMS X2 has continued link with Central Monitor after leaving the Host Monitor?

The Philips IntelliVue MMS X2 is similarly a transformation of MMS (multi-measurement server module) into a compact monitor with display and battery, primary purpose to link an MMS module to a patient and follow the patient's movement. In fact IntelliVue MMS X2 was released much earlier than BSM-1700, so there was no reason the project leader of BSM-1700 was unaware of this important need.

IntelliVue MMS X2 was launched long before BSM-1700

When the IntelliVue MMS X2 is connected to a host monitor, it has the option of wired Ethernet or WiFi via the host monitor OR through its own wireless telemetry transceiver to link with the Central Station. To maintain network continuity when the IntelliVue MMS X2 changes from being a MMS to transport monitor, it must choose the wireless telemetry option only. When the IntelliVue MMS X2 is assigned to a telemetry transceiver at the Central Station, patient identity is by the telemetry transceiver, thus the host monitor is automatically paired to it. The IntellieVue MMS X2 and Host Monitor together are recognized as one telemetry device to the central station.

During patient transfer, the IntelliVue MMS X2 disconnects from host monitor and operates as an independent transport monitor but communication link between MMS X2 and central station is not broken since telemetry transceiver in inside the IntelliVue MMS X2.

In addition, consider the patient arrives at a new location, the new host monitor is now paired to the IntelliVue MMS X2's telemetry transceiver monitored at the central station. Such patient transfer is truly seamless at the system level.

The telemetry transceiver in the IntelliVue MMS X2 is the token for tracking the patient

The Phillips Telemetry System

The official name for current Philips telemetry system is IntelliVue Instrument Telemetry System (IIT) and this is a newer generation bi-directional communication system operating in groups of channels within the 2.4GHz ISM band utilizing frequency hopping algorithm.

Frequency hopping technology originated from electronic warfare and is a technique to avoid enemy eavesdropping or high-power CW jamming by continuously switching the transmitting frequency (and therefore the receiving frequency). In healthcare, there is no enemy determined to jam you in every move so you do not have to anticipate the enemy. It is an adapted version to improve real-time performance in a crowded band since the 2.4GHz ISM band is a real radio waves jungle today. In the US market, Philips also offers the same IIT system using the protected WMTS bands in line with FCC initiative. This is done easily by replacing the internal ISM adapter (for International market) with WMTS adapter.

The Life Scope PT monitor is limited by original design not to exactly follow Phillips after leaving a Host Monitor as input unit

Despite the fact BSM-1700 monitor has a wireless option using a ZS-900PK telemetry transmitter to link to the Central Station, the telemetry transmitter cannot be attached to the BSM-1700 when it is acting as an Input Unit to a host monitor. This is because the design to have BSM-1700 as a transport monitor to a Host Monitor was an after-thought, and there is difficulty to switch to telemetry after detaching from a Host Monitor.

The initial decision was to follow GE Marquette

The initial design was to follow GE Marquette way, transferring the input unit from Life Scope TR bedside monitor (BSM-6501 or BSM-6701) to a compact 10.4-inch Life Scope TR (BSM-6301) to fulfill the transport role.

The original way was to use Life Scope TR 10.4 inch model as transport monitor

This naturally extends to the Data Acquisition Unit (DAU) which is a repeater interface between input unit and monitor.

The BSM-6000 series main unit was designed long before Philips introduced the idea of turning input unit into a transport monitor

Thus, although the BSM-1700 monitor has a wireless option using a ZS-900PK telemetry transmitter to link to the Central Station, a telemetry transmitter cannot be attached to BSM-1700 when it is acting as an Input Unit to a host monitor as illustrated below.

A telemetry transmitter cannot be attached to a BSM-1700 series monitor when it is on the DAU

To attach a telemetry transmitter onto a BSM-1700 monitor requires the service of a qualified technical staff, it is therefore impossible for a BSM-1700 to change from being an Input Unit to a Transport Monitor with telemetry connectivity at short notice.

This means the telemetry transmitter can only be used on BSM-1700 monitor operating as a stand-alone monitor, which obviously will be an over-priced monitor and an unlikely installation.

BSM-1700 series monitors are not priced for stand-alone telemetry use

In the above image, the BSM-1700 monitor is equipped with a ZS-900PK telemetry transmitter linking to a Telemetry Central Monitor.

This is the misleading "continuous monitoring while wirelessly transmitting patient data and waveforms to a central monitor" mentioned in the brochure for use as a standalone monitor, which is meaningless to the target market outside of Japan.

Why is this description so out of context?

It is reminded the BSM-1700 does not have a built-in power unit and in telemetry mode cannot be charged directly from an AC outlet, the SC-170R AC Cradle or special external charger is additionally needed for its proper operation.

Legacy flaw exists at the system level when switching to follow Philips

The idea of turning the Input Unit on a host monitor into a Transport Monitor was not conceived yet when BSM-6000 series monitor was first designed, it was considerable time after Philips had introduced the IntelliVue MMS X2 that Nihon Kohden decided to copy the idea.

Life Scope PT has a serious problem of radio silence during patient transport when copying the Philips way. The image below illustrates a LIFE SCOPE BSM-1700 sitting on a Data Acquisition Unit (DAU) and connected to a Life Scope TR (BSM-6000) series host monitor. The BSM-1700 monitor in this setup is acting as an Input Unit only and master control is on the host monitor. The BSM-6000 monitor as host monitor not only provides DC Power to charge BSM-1700's internal battery, it also provides the Ethernet path (either wired or WiFi depending on BSM-6000 setting) to the Central Monitor.

Life Scope PT as Input Unit to a host monitor will turn into a transport monitor when detached

When BSM-1700 is removed from the host monitor, it can no longer use the latter's Ethernet path to the Central Monitor but it does not have its own path to the Central Monitor after leaving the host monitor. We had mentioned earlier that the BSM-1700 series monitors does not have independent WiFi ability.

# Radio silence means there can be no seamless monitoring at the central monitor

The communication link can only be re-established after the Transport Monitor is attached again to another Host Monitor as Input Unit. Upon re-attaching back to another host monitor, the patient data stored in the Life Scope PT during the transport period will then be synchronized to the Central Monitor.

Removing a BSM-1700 monitor as Input Unit on a DAU turns it offline to the Central Monitor

Critical central station surveillance is therefore not available for the BSM-1700 transport monitor during patient transfer from one host monitor to another. There is a critical missing specification at the system level.

The BSM-1700 relies on built-in memory to store the patient data during transport and only able to upload it to the Central Station via a Host Monitor after the transfer is completed.

Seamless data review though available at the Central Monitor, it does not equate seamless monitoring

The Central Station can be updated only after the BSM-1700 transport monitor is eventually linked to another Host Monitor as Input Unit. This synchronization will make the data on the Central Station seamless but it is not seamless monitoring.

As a comparison, Draeger does not need to change IP because their concept is not "from Input Unit to Transport Monitor".

>> See Draegar's "Pick And Go" Concept.

Watch out for the careless and dangerous use of estimated CO2 values as true values

Nihon Kohden lacks sidestream CO2 sampling expertise and buys OEM units to offer them as expensive standalone. The AG-400 CO2 unit as shown, for example, is technology from Oridion Medical. For monitoring such as post-surgery recovery, integration of the sidestream CO2 into the monitor is a mandatory requirement because an external unit requires additional power socket besides necessitating the use of a trolley.

For some unknown weakness, Nihon Kohden monitors have never been able to offer benefits of integrated sidestream CO2 measurement.

The inability to integrate the sidestream CO2 unit into the patient monitor main unit

The adoption of semi-quantitative mainstream CO2 measurement 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 semi-quantitative measurement is adopted, the method is not commonly seen and many are not aware of the risks of obtained CO2 readings from the semi-quantitative CO2 kit sets, and to make matter worse, the semi-quantitative measurements are also being made used of to display a flawed continuous CO2 waveform.

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

How to remove a relatively big disposable adapter from the two tiny transducers after use?

When the sensors become smaller, it also means the disposable adapter becomes relatively much bigger as seen in this below picture. When trying to remove the disposable adapter from the transducers, it is difficult to separate the two because of the latching mechanism. A small size transducer means anything that latches onto it must be even smaller.


It is not easy to separate the disposable adapter from the Cap-ONE transducers after use

When removing disposable adapter from the mini sensors, users tend to just pull from the cables and this action quickly weakens the joint holding the sensors and cables. The action will cause stress to the two joints and quickly degenerate the performance of the transducers. This means the transducers are unlikely to last.

Users just doing the inevitable

Shown below is another TG-900P etCO2 kit set (order code P903) that makes semi-quantitative CO2 measurements on 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 with traditional mainstream transducer

*# The manufacturer is not aware semi-quantitative CO2 measurements are only estimates and sell it as cheap alternative to quantitative type*

To save costs, the semi-quantitative kit sets do not make measurement during the inspiration phase. The important point is there is a measurement duty cycle and it is as shown; there is no way to know the actual CO2 measurements during the inspiration phase because CO2 measurements are not made.

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

Semi-quantitative measurement is also of low-accuracy type, performed using one IR detector instead of the usual two to save cost. This is reflected in the measurement tolerance.

Contrasting, quantitative measurement delivers high accuracy for critical care. To ensure the necessary high accuracy, quantitative measurement employed two IR detectors for simultaneous CO2 measurements at different wavelength for results comparison. CO2 measurements are also being made continuously.

Quantitative measurement employs two detectors to make continuous measurement 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 measurement using semi-quantitative method no longer holds true once CO2 is present during the inspiration phase.

In other words,

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

2. The true CO2 level = (measured CO2 value + x);

where x is the 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 thus impossible that any manufacturer using a semi-quantitative design can specify a measurement tolerance when there is an unknown in the equation

Struggling to specify an impossible measurement tolerance!

As seen from the duty cycle, there is no measurement being made during the inspiration phase, how does the manufacturer know the measured CO2 value is the true CO2 level? The specified measurement tolerance is conditional on this assurance and the CO2 value shown to users is therefore wrong and misleading!

Each semi-quantitative CO2 measurement is in fact only an estimation, because the manufacturer cannot be sure the x value is indeed zero. It is only assumed to be zero.

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

# Semi-quantitative methodology means cost-effective estimations and 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 as an estimation tool for obtaining the numerical value of End-tidal Carbon Dioxide level (etCO2).

Below picture shows the semi-quantitative method in the way it was intended for, estimating only the etCO2 numerical value for purpose of airway tube placement confirmation. It is not for continuous waveform display.

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

# The manufacturer ended up ignorantly displaying a flawed continuous CO2 waveform using semi-quantitative measurement kits that do not have ability to make continuous measurements

NIHON KOHDEN also allows data from semi-quantitative measurements to be displayed on screen with the non-measurement period reset to zero level. The insistence to display a continuous waveform using discontinuous measurement data from semi-quantitative mainstream CO2 estimation kits is unacceptable; the manufacturer is just subjecting the monitored patients and users to dangerous misinterpretation risks.

A zero CO2 reading on the waveform means zero measured value. No measurement can only mean a defective sensor, not by design!

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

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

Quantitative measurements confirming expiratory upstrokes do not always start from zero CO2 level

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 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. This sensor was designed for non-intubated adult CO2 monitoring, as well as neonatal CO2 monitoring. Nihon Kohden is thus offering an alternative to sidestream CO2 sampling methodology.

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!

These are common defects of a TG-970P CO2 sensor kit (P909). The design is impractical.

*The fragile miniaturized CO2 sensor are clearly of poor design, and easily broken*

The key point is, it does not last