Anesthesia monitor considerations

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Reliable anesthesia monitoring equipment is one of the foundations of excellent patient care, making a quality multiparameter monitor an indispensable tool for a trained clinical team.
By practicing anesthesia and monitoring in a controlled environment, your team can build anesthesia skills without risking patients.
Photo courtesy Midmark Animal Health

Reliable anesthesia monitoring equipment is one of the foundations of excellent patient care, making a quality multiparameter monitor an indispensable tool for a trained clinical team. It can help provide a quick assessment of patient status and rapidly alert you to changes in condition to help avert trouble. A reliable monitor can also guide intervention when needed and streamline anesthetic recordkeeping.

There are many different monitor brands and models to choose from, and while they may look alike on the surface, there are some key considerations to keep in mind that explain the significant price ranges you may see. Carefully choosing a monitor that supports exceptional patient care delivery will pay dividends for years to come.

Anesthesia parameters

The first decision to make is which vital signs your multiparameter monitor should include. The Small Animal Anesthesia Monitoring Guidelines, established by the American College of Veterinary Anesthesiologists, recommend monitoring ventilation, circulation, oxygenation, and temperature. Stated another way, in the 2020 Anesthesia and Monitoring Guidelines for Dogs and Cats, the American Animal Hospital Association (AAHA) recommends monitoring respiratory function, cardiovascular function, cardiac rhythm, and temperature to mitigate risk during anesthesia. Thus, a complete anesthesia monitor would include capnography, non-invasive blood pressure (NIBP), pulse oximetry (SpO2), electrocardiography (ECG), and temperature.

Emergency specialty hospitals and university teaching hospitals might also look for units capable of monitoring invasive blood pressure (IBP) or anesthetic gases, but these are not commonly used in general practice.

While pulse rate, respiration rate and oxygenation can be confirmed manually, blood pressure and ventilation cannot be adequately assessed without the aid of an electronic monitor. Considered the “anesthesia disaster early warning system,” capnography reveals both patient ventilation, as well as issues with anesthesia equipment and endotracheal tube placement.

In a review of more than 2,000 human anesthetic cases, it was determined capnography would have detected over half of the anesthetic incidents on its own.1 Using capnography is a practical way to quantify hypoventilation, which studies have shown to be one of the most common anesthetic complications.2

The best technologies for veterinary medicine include either a low flow (< 50 ml/min sample rate) side-stream system, with no water trap, or a solid-state mainstream technology, with no internal moving parts. Older models required this technology to be built into monitors, but now there are external, durable, “plug-and-play” connections that can be added on, interchanged, and swapped out, depending on the use case.

The technology used in a multiparameter monitor for measuring non-invasive blood pressure will determine whether its accuracy can be trusted. Since the algorithms used will vary by manufacturer, choosing a monitor designed for veterinary use will have an impact on its performance. Validation criteria from the American College of Veterinary Internal Medicine (ACVIM) Hypertension Consensus Panel and the Veterinary Blood Pressure Society (AHCP-VBPS) have been used to review the known literature to develop general conclusions for the proper use and interpretation of NIBP devices. Research3,4 from May 2020 established the number of blood pressure technologies that meet the validation criteria for anesthetized dogs is few, and for anesthetized cats is even fewer.

Placement of anesthesia tech

Depending on the number of monitors in your practice and whether you plan to share across care areas, consider workflow and mobility. While it may seem a smaller monitor is better for portability, the benefits are lost if the monitor is dropped in transit. Mounting a larger monitor to a mobile stand makes it easier to safely move the unit from one point of care to another, while providing added flexibility and mobility options.

In a high-use procedure area, such as a surgery suite or dental suite, wall-mounting your monitor and anesthesia solutions together can free floor space and can still be easily accessed. However, if you need to share one monitor between surgical areas, it is best to create a mobile central system that includes the monitor and anesthesia delivery solution. This ensures you can bring optimal monitoring to the point of care.

Balancing quality

Monitors used on people must follow strict quality and manufacturing standards set by the U.S. Food and Drug Administration (FDA), but these regulations are not enforced in the veterinary space. Find out if the manufacturer of the monitor you are considering uses a quality design and manufacturing system. You can do this by asking them directly, or by examining the labels on the monitor that indicate they have passed quality thresholds like ISO, CE, and UL-equivalent electrical safety testing.

Consider the advantages of choosing quality monitors designed for veterinary use. Monitors designed for animals will include blood pressure algorithms enhanced with advanced motion artifact suppression to increase reliability when veterinary patients move, pant, or shiver. ECG algorithms will also be designed to reduce double-counting, and alarm limits will be pre-set to veterinary-specific ranges. This will help improve accuracy and reliability, ensuring the best care is provided for animal patients.

Additionally, ask about parameter kits, both standard and optional, to ensure a wide array of blood pressure cuff sizes, pulse oximeter sensors, and ECG clips to match the variety of breeds and species you see.

Finally, some veterinary monitor manufacturers have conducted immersive research into the anesthetic care delivery journey and include credentialed veterinary clinicians on their product development teams to ensure your needs are met.

Monitor efficiency, safety features

This may seem obvious, but ease of use is important. If the device causes user frustration or confusion, it will not be used correctly, leading to wasted resources and potentially impacting patient safety. Although monitors may come with user manuals, quick-start guides, or in-service support, these are not always helpful in the midst of a busy, chaotic day. Look for a monitor with an aesthetically appealing interface that is easy to read without straining to see the all-important vital information it is communicating. A touchscreen, intuitive interface and menu that are easy to navigate will simplify usage and increase efficiency in training new staff. The ability to save settings to your preference and between multiple users will also streamline your process.

Some monitoring devices are designed with built-in ECG and CO2 catalogs. When a waveform is in question, you can quickly scroll through this integrated reference library of common anesthetic waveforms to identify arrhythmias or ventilation challenges represented by the corresponding patient, allowing for faster intervention and resolution. This is where ease of use meets patient safety.

AAHA highlights the use of checklists in their 2020 guidelines5 to reduce the risk of anesthesia-related adverse events, yet many practices do not use them consistently, if at all. The newest anesthetic monitors include an on-screen pre-procedure equipment checklist that highlights the steps needed to support safer, more efficient procedures. An effective checklist should contain at least half a dozen items to inspect. An ambiguous “check equipment” task increases the risk that steps will be missed, which may compromise the patient’s safety. One of the common elements of such a checklist would be to confirm that fresh soda lime is being used. A more advanced feature might include an actual pop-up reminder on the monitor screen that alerts you to discard and replace the CO2 absorbent in the anesthesia machine.

Anesthetic recordkeeping

When your patient is under general anesthesia, vital signs should be evaluated continuously and recorded in the anesthetic record every five to 10 minutes. This anesthetic record becomes part of the patient’s medical record and legal documentation. Streamlining documentation can enhance clinical decision support, reduce the risk of manual data entry errors, and may help improve patient safety and outcomes.

Some monitors have built-in printers that can print waveforms and tabular readings, but more advanced monitors streamline this process for a paperless practice by allowing transfer via USB, ethernet cable, or through a wireless connection. Consider a monitor that can transfer ECG waveforms and parameter trends, plot the periodic readings in a digital anesthetic record and allow the addition of notes.

Training and support

Many monitor purchases include some level of training and support. Indeed, a reliable manufacturer will want to ensure you get the most out of your monitoring equipment so you can continue to provide the best possible care.

Choose a manufacturer that understands the value clinical education and support can have on care delivery and patient outcomes. Can you access clinical support when you need it? Do they have a dedicated clinical team comprised of credentialed veterinary technicians who can help if you have an equipment question or need expert advice on a technical issue? Will they help with a simple adjustment or recommend an accessory replacement before requiring you to ship your entire monitor for repair? When it needs repair, do they provide loaners? Beyond offering a simple in-service, do they offer RACE-approved in-clinic anesthesia CE designed to ensure your clinical team is prepared to deliver the best possible care for your patients?

Finally, research the brand and manufacturer. Ask your colleagues, referral hospitals and professors whether it is widely used and trusted. Has there been continual innovation over the years with successive improvements creating a family of monitors that grows with a practice while preserving consistency among cross-compatible peripheral accessories? Are they committed to animal health as evidenced by thought leadership and dedication to anesthesia monitoring education and long-term customer relationships?

In the end, selecting a multiparameter anesthetic monitor that will serve you reliably for years to come with quality, ease of use, and safety requires diligence in evaluating not just the monitor itself, but the company that stands behind it.

Mandi Gerigk, BAS, CVT, is the supervisor of Animal Health Clinical Specialists for Midmark. Andrew Schultz, Jr., MBA, former director of Monitoring and Critical Care for Midmark and the company’s current director of Animal Health Business Development and Clinical Services, contributed to this article.

References

  1. R.K. Webb, J.H Van Der Walt, et al., Which Monitor? An Analysis of 2000 Incident Reports, Anaesth Intens Care 1993; 21: 529-542. https://journals.sagepub.com/doi/10.1177/0310057X9302100508
  2. Redondo, J., Rubio, et al., (2007). Normal Values and Incidence of Cardiorespiratory Complications in Dogs During General Anaesthesia.
    A Review of 1281 Cases. Transboundary and Emerging Diseases, 54(9), 470-477. https://pubmed.ncbi.nlm.nih.gov/17931219
  3. Skelding A, Valverde A. Non-invasive blood pressure measurement in animals: Part 1 – Techniques of measurement and validation of non-invasive devices. Can Vet J. 2020;61(4):368-374. https://pubmed.ncbi.nlm.nih.gov/32255821/
  4. Skelding A, Valverde A. Review of non-invasive blood pressure measurement in animals: Part 2 – Evaluation of the performance of non-invasive devices. Can Vet J. 2020 May;61(5):481-498. https://pubmed.ncbi.nlm.nih.gov/32355347
  5. Grubb T, Sager J, Gaynor J, et al. 2020 AAHA Anesthesia and Monitoring Guidelines for Dogs and Cats, J Am Anim Hosp Assoc 2020; 56 https://pubmed.ncbi.nlm.nih.gov/32078360
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