Medical Devices Sanity: 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.

Launched in early 2011, the configured LIFE SCOPE VS (BSM-3500 and BSM-3700) series patient monitors targets mid-acuity sites with the configured BSM-3500 series using a 12.1 inch touchscreen display while the configured BSM-3700 series uses a 15-inch touchscreen display. (The BSM-3500 series was belatedly launched in the USA market in 2016).

Configured Life Scope VS (BSM-3000) series models

There are four models for the 12.1-inch configured BSM-3500 series, namely

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; the latest international version is refrained from use in the USA market for undisclosed reasons.

Another four models are for the 15-inch configured BSM-3700 series, namely

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 prominent feature of Life Scope VS bedside monitors is the utilization of flexible MULTI-parameter sockets that are colored in yellow. These yellow MULTI sockets do not accept ordinary measurement cables but only measurement cables that have NIHON KOHDEN parameter codes embedded in their plugs (which are also colored in yellow). The end result of using these flexible connector sockets means a good amount of needed connector sockets are removed from the monitor, which is undesirable. In reality, there is no benefit from using these flexible Multi-parameter sockets since shortage of connector sockets implies inflexibility!

The Concept of a MULTI-PARAMETER UNIT (MPU)

NIHON KOHDEN had earlier identified five types of analog hardware that can be linked from the inside onto the MULTI-parameter sockets and to make use of these hardware, a cable with the correct code on its plug must be inserted into one of the MULTI-parameter sockets. These cables with coded plugs are collectively cited as Smart Cables by the manufacturer and the codes are also known as parameter codes. Each MULTI-parameter socket selects only one channel of the hardware, except for Temperature allowing two channels of hardware to be selected.

To repeat, the hardware mentioned here (namely Temperature, IBP, Cardiac Output, Thermistor Respiration and FiO2) are linked to the yellow connector socket internally, and not from the outside.

A measurement cable with the correct code in its plug can make use of any of the internally configured hardware shown here

The configured hardware using the Smart Cables are grouped into a block known as MULTI-PARAMETER UNIT (MPU), complete with a small number of yellow MULTI-parameter sockets. The number of flexible yellow sockets in the MPU is not arbitrary, but corresponds to the number of IBP hardware channels that are configured inside.

Principle of operation

Variations to the basic theme

There are variations to the basic theme, such as doing without use of external expansion box, or increasing the number of MULTI-parameter sockets in the MULTI-parameter Unit, or reducing the hardware configured in the Multi-parameter Unit.

In the Life Scope 3500 series bedside monitors which has two MULTI-parameter sockets each, two channels of IBP amplifiers, two channels of Temperature and one channel of Cardiac Output are configured for use by Smart Cables.

In the Life Scope 3700 series bedside monitors which has three MULTI-parameter sockets each, three channels of IBP amplifiers, two channels of Temperature and one channel of Cardiac Output are configured for use by Smart Cables.

NIBP, SpO2, ECG and two channels of Temperature are configured for both Life Scope VS series monitors using dedicated measurement cables. They are not part of the MULTI-parameter Unit.

Take note the Life Scope VS series was not designed to make use of expansion units, this was an after-thought and adaptation following users complaining strongly the yellow Multi-parameter sockets on Life Scope VS monitors are not enough for use. The manufacturer should make clear the limitations of the adapted external sockets?

The digital hexadecimal code is stored in an EEPROM chip mounted on a small flexible PC board electrically wired to the pins of the cable plug. It is not difficult to make the Smart Cables but they are being priced highly by the manufacturer; only the common IBP cable can be sourced from China suppliers at a reasonable price.

A parameter code is stored in the plug of the measurement cable

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

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

The MULTI-parameter sockets are additionally diverted to serve as digital serial ports

This is the part that involves using external monitoring hardware, but they are all self-contained units supplying a processed digital output to the yellow connector socket.

As explained earlier, the design of MULTI-parameter Unit was to solve the problem of limited panel space, further reduction of sockets by using the MULTI-parameter sockets as serial ports will help towards the design objective. This being an easy task since there is no need for additional internal analog hardware and the digital serial signals from the serial kit sets just go straight to the monitor main unit.

Currently, mainstream CO2, 2nd SpO2, BIS and NMT hardware are self-contained digital serial kits using the MULTI-parameter sockets only as a link to the monitor, saving on connector sockets. We must be clear when use of MULTI-parameter sockets as serial ports is not to solve the problem of limited panel space, the cost cannot be justified.

Shown below is the original label for the yellow MULTI socket, indicating the five specific hardware and also serving as serial port for mainstream CO2 serial kits; the purpose of this arrangement was to minimize the number of sockets being used on a limited panel space.

The original label for the yellow MULTI-parameter sockets when they were first used

The use of Smart Cables does not upgrade the Life Scope VS bedside monitors from configured to modular

A yellow MULTI-parameter socket by itself does not automatically mean all the five types of mentioned parameters are available for measurements; it still depends on whether what hardware are actually being placed inside for selection.

Additional parameter capability can be added using self-contained serial kit sets or via interfaces to external equipment.

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

Configured hardware in Life Scope VS bedside monitors using Smart Cables

It is the built-in hardware that determine the parameter capability; and in the case of serial kit sets, the system software. This of course, is the same description as a configured patient monitor

Actual internal hardware and system support for serial kits varies for each multi-parameter unit

It is obvious Life Scope VS bedside monitors making use of Smart Cables are still configured monitors.

The only advantage of using Smart Cables is to allow sharing of connector sockets, which are of negligible hardware cost; the cost needed to make use of Smart Cables is however, far higher. It does not make logical sense for use on Life Scope VS bedside monitors, and we should look out for the ulterior motivation behind its use.

BEWARE the Captured Value from using Smart Cables is negative for users

Users of the left monitor (BSM-3500 series with 2 channels of IBP) requires five connection sockets for carefree use but the manufacturer using Smart cables can only provide two MULTI-parameter sockets for time-sharing.

As only two IBP channels are specified for the Life Scope BSM-3500 series bedside monitors, the monitors cannot have more than two yellow MULTI-parameter sockets since each functional MULTI-parameter socket comes with its own one-channel IBP hardware.

Similarly, the Life Scope BSM-3700 series bedside monitors are specified for 3-channels of IBP monitoring, the manufacturer can only provide three MULTI-parameter sockets for sharing use even though users of the right monitor requires six connection sockets for unconstrained use.

It is obvious the yellow MULTI-parameter sockets are not enough for use by design. How does such deliberate shortage of connector sockets benefit the users?

Users of the two monitors must endure pains of insufficient connector sockets to gain use of two or three flexible sockets

Manufacturers make their profits by providing product benefits to users but the yellow MULTI-parameter sockets have no benefit. The first vehement complaint from users is the yellow MULTI-parameter sockets on the monitor are not enough for use.

What benefit can it offer users when necessary connector sockets go missing?

If you are still harboring the misconception there are monitoring hardware embedded in the NIHON KOHDEN Smart Cables, we show beyond the slightest doubt, there is absolutely no active electronics in the Smart Cables.

The marketing messages "New Modular Technology" and "The Module is in the cable!" are mere imaginations of people without the necessary electronics knowledge.

What do the manufacturer mean by this statement?

It started with the Life Scope TR (BSM-6000) series monitors in the USA market and gradually adopted officially for International markets. These are precise statements.

The continued repetitions of an assertion without offering any proof does not make it the truth!

This is just assertion without offering any proof

Chip makers need huge demand to justify each of their products, so which chip manufacturer is supplying NIHON KOHDEN the variety of analog chips given the extremely low volume in demand? If we were to open up the plug of a Smart Cable, what do we see? A small PC board is seen attached to some pins of the yellow plug.

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

The board confirms a cheap digital EEPROM chip is being used to code the Smart Cable.

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

If we were to open up the plug of a compatible IBP cable from China suppliers, what do we see? It is the same thing, a plug with a digital code defined by NIHON KOHDEN.

Under US FDA rule, a cable is only a cable if it does not change the signal that passes through it. A Smart Cable with a hexadecimal code is just a cable and does not change a signal passing through it, but if it has an amplifier it becomes a medical device and requires FDA registration. Can you find any stand-alone Smart Cables registered with US FDA as a medical device?

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 and not the passive Smart Cable.

Irrefutable Proof the IBP amplifier hardware is configured internally, an important fact withdrawn from later monitor manuals

The Life Scope BSM-2301 bedside monitor was launched before the Life Scope TR bedside monitors, and the Service Manual is clear on the design; manuals for later models stop providing such information. The major move to curb details in manuals started from Life Scope J (BSM-9101) Bedside Monitor, launched before the Life Scope TR bedside monitors.

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

Can you see the IBP amplifier and thermistor respiration hardware are internal components of the Life Scope BSM-2301 monitor?

The MULTI-parameter socket doubles as a serial port without any need for internal monitoring hardware, only as a link to the monitor. In the block diagram below, the processed digital serial data from a CO2 kit set goes straight to the digital microcontroller APU (Analog-block Processing Unit) and is forwarded to the DPU. For a parameter using the internal analog hardware, the analog signal needs to pass through an Analog-Digital converter before going to the APU for digital processing.

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

You should know by now the IBP amplifier hardware inside the monitor is the reason a BSM-3500 series bedside monitor can do two channels of IBP monitoring, it is the same reason BSM-3700 series bedside monitor can do three channels of IBP monitoring.

Knowing that the design dictates every functional MULTI-parameter socket to come with its own mandatory one-channel IBP hardware, we can confidently conclude there are two configured IBP amplifier hardware inside the BSM-3500 series bedside monitor and three configured IBP amplifier hardware in the BSM-3700 series bedside monitor. With this knowledge, the rest of the hardware are easily arrived at after confirming all parameters that can be measured by each monitor.

First we filter out the parameters using self-contained serial kit sets, and they are BIS, APCO, mainstream CO2 and NMT for the Life Scope VS bedside monitors.

The patient monitoring hardware inside the Life Scope BSM-3500 series (12-inch) bedside monitors can easily concluded to be:

NORMAL BLOCK

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

- ECG

- SpO2

- NIBP

MULTI-PARAMETER UNIT with two yellow sockets

(These hardware only use Smart Cables for connections)

- 2 channels of IBP (2 MULTI sockets = 2-ch IBP)

- 2 channels of TEMP (1 MULTI socket = 2-ch TEMP)

- Cardiac Output

< Self-contained kit sets using Multi-parameter sockets as serial ports>

- BIS, APCO, mainstream CO2 and NMT

Notes:

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

The hardware in the MULTI-PARAMETER UNIT of BSM-3500 series monitor

Similarly, the patient monitoring hardware inside the Life Scope BSM-3700 series (15-inch) bedside monitors are concluded as:

NORMAL BLOCK

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

- ECG

- SpO2

- NIBP

MULTI-PARAMETER UNIT with three yellow sockets

(These hardware only use Smart Cables for connections)

- 3 channels of IBP (3 MULTI sockets = 3-ch IBP)

- 2 channels of TEMP (1 MULTI socket = 2-ch TEMP)

- Cardiac Output

< Self-contained kit sets using Multi-parameter sockets as serial ports>

- BIS, APCO, mainstream CO2 and NMT

The hardware in the MULTI-PARAMETER UNIT of BSM-3700 series monitor

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

There was no proper viability assessment done to pick the Smart Cables as a product selling point, and it is leading customers into having an unrealistic expectation of what the Smart Cables can actually deliver. The apparent flexibility of the MULTI sockets is in reality an adoption with negative captured value for the users.

Origin of the MULTI-PARAMETER UNIT design

In the 1990s, when developing the first digital modular monitor, the development team encountered a problem of insufficient front panel space for connector sockets on the first digital multi-parameter module being made. The Smart Cables were originally devised only to resolve a product issue.

At the time NIHON KOHDEN was responding to an important emerging trend of using a high-density digital multi-parameter module as basic building block for modular monitors. In analog modular monitors, only single parameter modules were produced by NIHON KOHDEN. When designing the first digital modular monitor, the company discovered the critical care market had already moved to using a digital multi-parameter module with higher density of electronic components as a basic building block for modular monitors.

NIHON KOHDEN wanted to follow the trend by offering the first digital multi-parameter module, and the first digital multi-parameter module made by the company was named the Saturn module. However, putting a lot of hardware into the Saturn module also means more panel space needed for connector sockets.

The Saturn module was intended to be physically small in size

The solution from NIHON KOHDEN for panel space limitation of Saturn module was to introduce a MULTI-parameter Unit with many hardware sharing two yellow sockets for common use.

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

In the Saturn module, the hardware are divided into two blocks, a normal block and a MULTI-parameter Unit.

ORDINARY BLOCK
(These hardware make use of dedicated sockets and ordinary measurement cables)
- ECG
- SpO2
- NIBP

MULTI-PARAMETER UNIT with two yellow sockets
(These hardware only use Smart Cables for connections)
- 2 channels of IBP (2 MULTI sockets = 2-ch IBP)
- 4 channels of Temperature (2 MULTI sockets = 4-ch TEMP)
- Cardiac Output
- FiO2
- Thermistor Respiration
<Self-contained kit sets using Multi-parameter sockets as serial ports>
- Mainstream CO2

Huge amount of configured hardware in the Saturn module

The MULTI-parameter Unit design has many hardware sharing only two MULTI-parameter sockets, this is to solve the problem of limited panel space.

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

Analog solution of adding more sockets, not monitoring parameters

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

The image gives an impression of scalability but this is scalability of connector sockets, and not the scalability of monitoring parameters that is being sought after by the market. All necessary hardware are already configured in the Saturn module except for additional IBP amplifier which must always come with each MULTI-parameter sockets.

A MULTI-parameter socket makes use of its own IBP hardware when a Smart Cable with an IBP code is plugged into it; for the other four parameters, the sockets are linked to the common pool of Temperature, Cardiac Output, Thermistor Respiration and FiO2 hardware already embedded in the the MULTI-parameter Unit of Saturn module.

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

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

The MULTI-parameter sockets were additionally allowed to be diverted to act as a costly digital serial ports so that mainstream CO2 digital serial kit sets can also use it; we must remember this is for purpose of minimizing connector sockets on the Saturn multi-parameter module, as it does not make sense outside this context.

The mainstream CO2 comes in the form of a self-contained serial kit set, and has no need for the MULTI-parameter Unit.

Keep in mind, a yellow MULTI-parameter socket is a high-cost serial port when it does not select any internal hardware

MULTI-parameter socket poorly utilized as a costly serial port

The initial arrangement was only for mainstream CO2 serial kit sets, but later extended enthusiastically to BIS kit set, 2nd-SpO2 kit set, APCO kit set, NMT kit set etc., whose motivation is highly questionable given this greatly increases the interface cost compared to a plain serial port.

The use of Smart Cables for serial communication does give a false illusion of mighty MULTI-parameter sockets but the capabilities are in reality coming from the system software.

Make no mistake, the serial kit sets are self-contained and whether a particular kit set is supported depends on the system software, not on the type of connector sockets being used.

There is no difference if you connect digital serial data to the monitor using Smart Cables or ordinary serial cables

This is how you connect the BIS processor kit to a yellow MULTI socket

Using Smart Cables for serial interface means an unnecessary jump in demand for more yellow MULTI-parameter sockets and there is no technical need for the serial kit sets to use the yellow MULTI-parameter sockets. Putting things into perspective, most patient monitoring parameters cannot be made into self-contained serial kits; for example, the AE-918P Neuro Unit or a strip chart recorder cannot be linked to a yellow MULTI-parameter socket as serial kit as shown. They are connected as external devices to a monitor.

The AE-918P Neuro unit and recorder module are examples that cannot make use of the yellow MULTI sockets

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

The Saturn module, together with two satellite boxes adding 4 channels of IBP to the Saturn module is shown below. The four MULTI-parameter sockets on the satellite boxes can also access the MPU of the Saturn module. Together, six IBP channels and six shared-use MULTI-parameter sockets are available to the users.

The sockets on the satellite boxes compensate for the missing connector sockets on the Saturn module

The use of Smart Cables before the Life Scope VS monitors

Preceding Life Scope VS bedside monitors was the Life Scope BSM-2300K series monitors, let's see how the sole yellow MULTI socket was actually being used in this series.

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

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

a. Invasive Blood Pressure

b. Thermistor Respiration

c. Digital self-contained mainstream CO2 serial kit sets.

The MULTI-parameter socket does not mean flexibility because you can only do one of the above parameter at any one time. Using three dedicated sockets is a far superior proposal; why suffer pain of two missing sockets to gain use of one flexible socket? It is illogical because the manufacturer just wants to use the Smart Cables.

Life Scope-i does not have enough connector sockets

The use of a MULTI-parameter socket is self-contradictory from the start. We have to ask why is the monitor avoiding the use of MULTI-parameter socket to access the Temperature hardware if sharing a socket is preferred capability? This is a slap on the face for anyone proposing use of Smart Cables on a bedside monitor!

The two blocks of patient monitoring hardware in the Life Scope BSM-2301 bedside monitor are:

ORDINARY BLOCK

(The hardware make use of dedicated sockets and ordinary cables)

- 1-ch TEMP

- ECG

- SpO2

- NIBP

MULTI-PARAMETER UNIT with one yellow socket

(The hardware only use Smart Cables for connections)

- 1-ch IBP

- Thermistor Respiration

<Kit sets using yellow Multi-parameter socket as serial port>

- Mainstream CO2

The reality is the shortage of two connector sockets, and the flood of complaints from users insisting the single MULTI-parameter connector socket on the BSM-2301K was not enough. The manufacturer was pressured to respond with an updated model (BSM-2303K) with an isolated MULTI-parameter socket added. The isolation was done so as not to disturb existing Multi-parameter Unit with an additional MULTI-parameter socket. It means the additional MULTI-parameter socket is not a functional one and only could make use of the IBP amplifier hardware that comes with it.

The isolated MULTI-parameter socket was intended solely for IBP monitoring, effectively relieving the existing functional MULTI-parameter socket to only measure either Thermistor Respiration or act as serial port for the mainstream CO2 kit set. The solution was only partial, and it reduced two missing sockets to one missing socket; a total solution would have been just using dedicated sockets as there is no need for socket sharing. There was no need for the Smart Cables.

There was no actual demand for additional IBP channel, but the BSM-2303 bedside monitor was camouflaged as an upgraded monitor with 2 channels of IBP.

Under pressure, an additional isolated MULTI-parameter socket acting solely as an IBP amplifier had to be introduced

As expected, the MULTI-parameter sockets on Life Scope VS bedside monitors are not enough!

Electrically, the manufacturer can add more MULTI-parameter sockets using an external box that comes with MULTI-parameter sockets. The link is an analog interface, not digital; as such, only a maximum of four MULTI-parameter sockets can be added, limited by signal deterioration caused by voltage drop and noise pickup.

Life Scope VS bedside monitors were launched without options of expansion units; the situation is similar to Life Scope BSM-2301K bedside monitor, but the customers are desperate to have their sockets back!

As seen in below picture, the expansion units from Life Scope TR are offered to overcome the man-made problem. The makeshift solution makes the bedside monitor look awkward, resembling a product prototypes.

Like the BSM-2301K, the Life Scope VS monitors were not designed for extension socket boxes, are the MULTI-parameter sockets on the expansion units fully functional? Field demonstration to verify all claims must be done for proper assessment of suitability for use.

Socket boxes from Life Scope TR are offered as solution when complaints from users became overwhelming!

Why design monitors with shortage of connector sockets in the first place?

Elaborate time-sharing are applied to things that are expensive (high in demand, an asset), and not worth the efforts for things that are cheap (high in supply, a commodity) like a connector socket or a switch! It only makes sense to see productive efforts being made to time-share a CPU, a car, a hotel room, a yacht, an airplane but not a calculator, a pencil or a pair of scissors.

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.

Only share the expensive hardware, not the cheap sockets

*WATCH OUT* the dangerous use of uncertain semi-quantitative CO2 measurements and displaying a flawed CO2 waveform

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 reason, Nihon Kohden monitors could not offer integrated sidestream CO2 unit.

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 (order code 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

Do the users know semi-quantitative CO2 measurements are only estimations??

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.

This is because actual CO2 value will be more.

It is impossible for users to know if measurements are reliable when they cannot tell if CO2 is present during inspiration!

Measurements are invalid when CO2 is present during inspiration, but CO2 is not measured during this period

As seen from the duty cycle, there is no measurement being made during the inspiration phase, how does the manufacturer assure measurement accuracy? The specified measurement tolerance has no meaning for the users!

It should be clear each semi-quantitative CO2 measurement is only an estimation since its accuracy is rendered uncertain by the inability to confirm if CO2 is present during the inspiration phase.

Since the users are also not alerted on screen there is no CO2 measurement being made during the inspiration phase, they are unknowingly made to take on 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 a simple 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

Do you think the manufacturer is aware they are 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

As seen from the two true CO2 traces below, expiratory upstrokes do not always start from zero CO2 level!

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 sensor

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), implying the design is impractical

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

The Key point is, it does not last

Beware the mandatory need for network isolation units when connecting Life Scope VS bedside monitors to a Central Nurse Station

For hardwired Ethernet networking, a Life Scope VS bedside monitor equipped with a non-isolated Ethernet LAN interface when connecting to a real-time LAN network is a danger to the patient. It is mandatory to observe patient electrical safety by using a network isolation unit to protect the 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 lack of government subsidy