Upgrading or Investing? How to choose your new Multi-parameter Monitor

Keith Simpson BVSc, MRCVS, MIET(Electronics) - Clinical Director
Courtney Scales DipVN, NCert(Anaesth) RVN
Joel Huey BA (Hons) - Content Editor

Choosing a new multiparameter monitor for your practice is not a light undertaking. This type of equipment will inevitably come with significant financial investment and will need to serve the practice well for several years to justify the cost.

There may be a tendency to think that all multiparameter monitors are the same, however, this is not the case. Features, performance, reliability, suitability, and price all vary between different manufacturers and models. There may also be some factors that should be taken into account if opting for a human-based monitor rather than one designed for veterinary use. These will be explained later.

This blog is intended to highlight the required considerations when choosing the best-suited multiparameter for your practice. The following specifications will help you work through these options:

1. 1. Species Range
2. 2. Portability
3. 3. Required parameters
4. 4. Connectivity and Data Access
5. 5. Cost

Species range
This has an impact on the type of monitor you will require as there is a factor of patient size and physiological parameters, which some monitors may not be able to interpret e.g., high heart rates (HR) in smaller animals >300bpm.

Dogs and Cats
If your normal caseload is dogs and cats, then most monitors, even if they are essentially human machines, will cover the respiratory rate (RR) and HR ranges encountered with them.

Exotics
If your caseload includes exotics species, consider the range of the physiological parameters being measured. A lot of exotic patients tend to weigh between grams to kilograms, so consideration must be given to the ability of the monitor to work with patients of this size.

For example, a 250g African Grey parrot under anaesthesia, would need a machine capable of monitoring HRs in excess of 300bpm and possibly up to 600bpm, depending on the demeanour of the patient. Additionally, when monitoring the end-tidal carbon dioxide (ETCO₂) content, then a sidestream device with the lowest possible sidestream rate would be required. Current technology allows sidestream rates as low as 50ml/min and this is just low enough to enable reliable results from a patient weighing 250g. Higher sidestream rates of 120-200mls/min would not be suitable for patients under 2kg. It is important to note that mainstream capnography is not generally suitable for smaller (<1kg) exotic patients.

Check the lower weight range of other measuring modalities such as non-invasive blood pressure (NIBP) and pulse oximetry. Achieving a reliable blood pressure reading from an oscillometric device in patients under 5kg may be difficult, therefore check the specifications for the lowest weight range supported by the monitor you are considering. Pulse oximetry in exotic species is possibly less important than with other species, particularly as most patients tend to be on enriched oxygen supplies and have unique physiology rendering oxygen saturation less helpful than with most mammals.

However, appreciating that the variation in exotic species is huge, if you are looking for a monitor to use in a zoo environment, then performance is needed not only on the smaller patients but also on larger patients. If this is the case, opt for a monitor with a sidestream capnograph. This will allow monitoring of patients from a few hundred grams up to several hundred kilograms.

<

Temperature monitoring is an important aspect of exotic anaesthesia monitoring. Many patients are too small to be monitored by a standard 5mm diameter probe, so check if the monitor you are considering has smaller probes for the smaller patients (1.2mm probes). 

Equine
The monitoring of equine anaesthesia tends to be different from that of small animal anaesthesia. Greater emphasis is placed on monitoring invasive blood pressure (IBP) than in small animals, and it may be advantageous if your monitor has more than one channel of IBP monitoring. The heart rate of an anesthetised horse is around 30bpm, and this is typically monitored by an ECG with leads placed in the jugular furrow and at the xiphisternum. Ensure the ECG leads that come with the machine are long enough to allow this. Small animal leads that are 1-1.5m long will not be suitable.

Also, check the terminations on the ECG cable for means of attachment. Working horses and small ponies often have very thick hair that will require shaving if sticky pads are to be used. Therefore, check that the ECG cable can use different connectors, including standard crocodile clips which work best with most horses. Another point to check is that the monitor can support heart rates as low as 30bpm as many human machines will give persistent warnings at this rate. Also, the T-wave in horses is often large and spikey and often misinterpreted as an r-wave, leading to double counting. It is helpful if the monitor has the ability to reject those conditions and give normal readings.

Pulse oximetry is important in horses due to their physical conformation and physiology, which often results in low partial pressure of arterial oxygen (PaO₂) values. In the absence of arterial blood gas analysis, a reliable saturation figure is a must. Pulse oximetry in horses requires either a transmission clip that will fit on the tongue or a reflectance probe that can be placed against the nasal septum, the gingiva or in the prepuce. Larger probes are not necessarily better than smaller probes and when using any probe on a horse’s tongue, care should be taken to avoid stray light interference. If the monitor supports both types of probes, then that will provide the greatest flexibility for situations when the tongue is not accessible.

Temperature monitoring in horses can be especially useful considering the increased distances involved in running a temperature probe from the monitor to the rectum. A probe length of 3m is a minimum to avoid difficulties in running the cable across the patient or operation site. smaller patients (1.2mm probes).

Portability and Battery Power
It is worthwhile giving some thought to where you will be using your monitor. Is it likely to stay in one place or could it be moved from theatre to imaging? Would you like to use your monitor cage-side during recovery? Will the monitor mount on the cage door and is there good visibility of the patient if so? Would you consider taking it to a different theatre upstairs or even to a branch surgery? Answers to these questions can directly influence the choice you make.

Give some thought to where the monitor will sit. Is there room on top of the existing anaesthetic machine? Will it be stable and safe there? If the option of a trolley or mobile stand (like a ‘drip stand’) is considered, is there room in the theatre for this extra equipment? Otherwise, a wall-mounted unit may be the best solution.

Many monitors come with a range of mounting options that can be specified at the time of ordering. Additionally, some monitors may also be able to stream their data to an additional larger screen in the operating theatre.

It is also worthwhile factoring in battery life. If the monitor is taken into imaging, where perhaps there is no convenient power source, the monitor may have to run on battery power. Additionally, it is advantageous that a monitor can be charged and used at the same time.  

Required Parameters
Which patient parameters do you want to monitor? They include:

• • ECG
• • Temperature
• • Pulse oximetry
• • Capnography
• • Sidestream
• • Mainstream
• • Blood pressure
• • NIBP (oscillometric)
• • IBP (arterial catheterisation)
• • Inspired/Expired agent values

Some multiparameter monitors will have a few of these options, some will have all, and others offer total flexibility in choosing the ones you need. The options that suit you will depend on your patient load, the skill set of the people using the monitor and, to some extent, your budget.

It is worth taking a look at these parameters in turn to give some indication of the usefulness of each.

ECG
This is a simple monitoring modality which, usually requires the placement of 3 or 4 cables at strategic points on the patient:

A 3-cable ECG will only give you one channel at a time (Leads I-III). This is normally Lead II, but some monitors allow you to select the channel you wish to view. For example, you may have placed red, green and yellow cables on your patient and be viewing a Lead II trace (Red-Green), but you may be able to change this to a Lead I trace (Red-Yellow), or a Lead III trace (Red-Green). For monitoring purposes, showing only one lead at a time is often all that is needed and usually, Lead II is the most informative.

A 4-cable ECG often allows the viewing of all Leads I-III simultaneously if required. The additional black cable forms a reference or grounding probe. Viewing six channels (Leads I-III and aVF, aVR, aVL) is usually not required during an anaesthetic, and is reserved for diagnostic ECG cases.

If using an ECG for diagnostic purposes, confirm that the monitor can provide an output that allows the ECG to be printed or saved externally if necessary.

Another consideration is the support of an oesophageal ECG probe. These are usually available in a range of sizes for use in animals from 1-2kg, up to large dogs or even horses. Ask your supplier if these are available and what patient ranges are available.

Temperature Monitoring
As previously mentioned in the Equine section, ensure the suitability of the probe in terms of length and size relative to the patient range that you will be using the monitor for.

Oesophageal probes often have a temperature sensor embedded in them allowing ECG and temperature measurements to be taken without the inconvenience of multiple cables across the operating table.

Pulse oximetry
Pulse oximetry is an extremely useful monitoring tool and is found in the majority of multiparameter monitors. The patient caseload may dictate which type of probe will suit you best.

Some pulse oximeter technology is now being used to indicate the requirement for or the success of intravenous fluid therapy for your patient. You may see Pleth Variability Index (PVI) and Perfusion index (PI) on some monitors, and whilst these are significant advances in technology, assess whether you will use these advanced features:

• • PVI is useful for hypovolaemic patients, but bear in mind that this is only relevant to patients receiving mechanical ventilation.    The feature is not recommended for use in spontaneously breathing patients.

Otherwise, heart rate range and reliability are the main criteria to consider. Many monitors show an indication of the reliability of the saturation figure based on an algorithm, looking at the quality of the red and infra-red signals obtained. For example, this can be helpful if your monitor shows a SpO₂ of 89% but also a reduced confidence indicator, meaning that the poor reading is probably due to either bad positioning, inadequate blood flow or stray light interference.

Capnography
There are two methods of capnography – mainstream or sidestream:

• • Mainstream capnography is where a small cube-like sensor is connected to the end of the endotracheal (ET) tube and the inhaled/exhaled gases pass through the sensor.
• • Sidestream capnography is where a small sampling line takes some of the inhaled/exhaled gas to the monitor and performs the analysis inside the unit.

If your patient caseload is mainly dogs and cats, then you’re in the fortunate position of being able to use either type. With mainstream capnography, low dead space connectors are available for smaller patients, but this still limits the lower patient size to about 1kg. The upper limit of mainstream capnography is that these connectors can usually only be used in systems with 15mm ET tube connectors, precluding their use in large animals. Sidestream connectors have the benefit of being suitable for most small animal caseloads, including small exotic species.

If you have a wide range of patients, check whether the monitor can support both types of capnograph as it will be more cost-effective to do this than have separate monitors for sidestream and mainstream capnography.

Blood Pressure
Blood pressure monitoring is used in conscious patients and those under anaesthesia, therefore consider if this feature will be used outside of the operating theatre, or whether the unit would be a dedicated theatre unit. Size and portability may affect your decision if the unit is to be used for both.

For routine small animal caseloads, NIBP is the most common method. IBP may be required when in use with horses, or for small animals in the intensive care environment.

When choosing an IBP monitor for intensive care, it can be useful to have more than one channel so that arterial and central venous pressure can be monitored concurrently.

Inspired/Expired agent values
This technology allows the inspired and expired volatile agent to be measured, which allows the assessment of the patient’s alveolar agent concentration. This can be compared to Minimum Alveolar Concentration (MAC) to aid in the management of the patient’s anaesthesia depth. This can be an expensive module as the technology is quite advanced. It is important to consider if staff are adequately trained to interpret this feature.

As it also often provides information on circuit oxygen concentration, it is valuable with the use of low-flow anaesthesia.

Connectivity and Data Access
It may be advantageous to have a remote link to the monitor, particularly if you want to use the monitor for ‘remote’ patient monitoring.

Remote patient monitoring does not necessarily mean monitoring from a great distance, but instead simply viewing several monitors simultaneously at a nurse’s workstation or a central point in the recovery ward, ICU or during CT imaging.

Consider the aspect of whether the data can be extracted from the monitor and used elsewhere e.g. can an anaesthetic record be produced or can the monitor be connected to a PC to allow this? Is data transmission in real-time or only on recorded data? The ability to send full anaesthetic monitoring or full diagnostic ECG data to a PC for storage and report generation is a huge benefit in the use of the monitor and opens the possibilities for improved monitoring, staff training and ongoing management of patients.

Check the specifications of the monitor to see if these features are offered, either as part of the package or as an option. Also, consider the software required. Is this free or licensed, are there any ongoing costs associated with this feature and will the software run on a PC and a Mac?

Lightning Multi-Parameter wirelessly connected to large screen

Cost
There are running costs associated with monitor consumables, such as airway adaptors for mainstream capnography units, sampling lines for sidestream capnography units, cuffs for NIBP systems, transducers for IBP systems and possibly maintenance contract costs.

What may look like a reasonably priced monitor at the point of purchase may turn out to have many running costs. Also, consider the repair costs once the monitor is out of warranty. Will that be an on-site repair or a return to base? If it is a return to base, is there an option of a loan unit? If there is, is that free or another additional cost?

It is worthwhile investigating how easy is it to get replacement parts and what are the predicted costs of them e.g. a new pulse oximeter probe, as you don’t want to discover a year down the line that the probe you need costs £500 and will take 4-6 weeks to arrive.

Problems with using human-based multiparameter monitoring machines.
Ex-hospital machines or re-badged and/or modified human machines are available to the veterinary market. In many cases, they function well however they may have limitations, such as:

1. ECG Performance
The standard HR range for human machines is 30-250bpm, and in some patients, especially exotic species, they will report erroneous readings e.g. a human machine with a heart rate limit of 300bpm may report a HR of 382bpm as 189bpm - exactly half. There are often pre-programmed arrhythmia or rate alarms that are unsuitable and non-specific for veterinary patients.

2. Sidestream capnography performance
The standard sidestream sampling rate is usually 120ml/min or 200ml/min, limiting its use to patients >3-5kg. In patients <5kg, avoid monitors with a sidestream sampling rate >120ml/min.
It is also likely that they will be unable to support some fast RR in veterinary patients e.g. rabbits. Their tidal volume is also small, and with a high sampling rate, will produce a capnogram that may look like a distorted, squashed mole-hill with unreliable results.

3. Pulse oximeter performance
A limiting factor will again be a limited HR range (up 250-300bpm, but also equine HRs <30bpm).
Additionally, they may not be able to function with small signals, such as a cat tongue.

4. Temperature performance
Human machines often have a temperature range of 25-45°C, which hinders their use in reptiles.
The industry standard YSI-400 probes, which are freely available from many suppliers may not be suitable for a non-UK machine or older machine. Check which type of temperature sensor is used with the machine you are considering.

5. NIBP performance
Poor results are seen in patients <5kg and in patients under anaesthesia where they are often hypotensive rather than hypertensive, it may also reduce performance.
Also, ensure that the machine supports a lower range of cuff sizes (usually human neonatal cuffs). Buying and using smaller cuffs than the machine is designed for is unlikely to result in accurate or reliable results.

6. Size
These machines are traditionally larger and bulkier than their veterinary counterparts as their purpose was initially indented to be fixed in either theatre or in bedside positions, which impacts their portability.

7. Replacement Parts
Some human machines, especially ex-NHS machines, are typically more than 5 years old, sometimes more, and their release from service indicates their continued use versus performance and maintenance costs is no longer viable and parts or servicing may be challenging to source.

Conclusion

Whilst this blog has not set out to suggest a particular multiparameter, we do have a range of monitors that are suitable for a wide species range, from mice to horses!

If you require any help or advice in identifying the best multiparameter suited to your practice, please contact us.

Multi-parameter Introduction Videos 

Introduction to the Vetronic Lightning Multi-Parameter Monitor

Getting started with the Mindray uMEC12 Multi-Parameter Monitor

Our Multi-Parameter options

Vetronic Lightning Multi-Paramter Monitor with software included

The Lightning is designed to suit your practice needs now and grow along with them, with the ability to be retrofitted with extra parameters as, and when, you require them. If cost is an issue, you can select the basic parameters you require right now, and then purchase additional parameters as it becomes financially sensible to do so. And you do not need to worry about this weighing your exceptionally light and portable monitor down. These parameters are all internal fittings, which we will fit for you in-house. Most of the standard parameters do not require extra plug-in hardware.

Free, in-depth software - The Lightning software is not only extremely advanced in its capabilities, but it is also completely free, along with any future advancements or software updates, and it can be simply installed on any existing practice PC.

Lightning has been designed to fit the needs of small animal practitioners, large animal practitioners and research establishments alike.

With a monitoring range catering for exotic species, the Lightning monitor is capable of measuring heart rates up to 600bpm (ECG) and 450bpm (Pulse-Oximetry). A dual-channel invasive blood pressure module allows simultaneous monitoring of arterial and venous lines and the dual-channel temperature module provides two temperature values (as well as the difference or delta value).

Find out more here
Or Read our buyers guide 'Unrivalled advantages of the Lightning multi-parameter monitor

Edan X12 Multi-Parameter Monitor

The Edan X12 Multi-Parameter is an ultra-slim, lightweight patient monitor. Designed to meet the demands of modern veterinary practices, this monitor features a crystal-clear, tilted touchscreen display, ensuring optimal visibility from all angles. Its highly responsive touch interface facilitates swift response for quick and easy usability. A comprehensive, yet uncomplicated, dashboard offers comprehensive data visualization options, enabling customizable range settings and alarms, while a simple night mode minimizes disruption during patient monitoring.

Furthermore, the X12 has been developed with a focus on user-friendliness, making it easy to use and understand for all practitioners, reducing training time. This innovative device empowers veterinary professionals to dedicate more time to patient care.

The Edan X12 Multi-Parameter Monitor covers a wide array of vital parameters, including ECG, NIBP, SPO2, Temperature, and Sidestream CO2. Setting it apart from most small animal multiparameter monitors, the Edan X12 offers a low side stream capnography sampling rate of just 50ml/minute - meaning your capnography traces and end-tidal carbon dioxide readings are more reliable for interpretation.

Mindray uMEC12 Multi-Parameter Monitor

This neatly packaged monitor has a 12.1inch high-resolution touchscreen, is lightweight and has up to 4 hours of continuous monitoring and 120 hours trend / 48 hours waveforms reviewing.