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3rd Annual Update on Vital Signs Monitors
Expert advice on what you need to look for in your next vital signs monitor purchase.
Bill Meltzer
Publish Date: June 9, 2008   |  Tags:   Anesthesia
Ask 10 anesthesia providers what they look for in a vital signs monitor and you're likely to get 10 different answers. When considering a new monitor, experts say you should ask yourself three questions:
  • Does the monitor help bring patients through the procedure more safely?
  • Does it spot trouble more quickly and accurately?
  • Does it present the data in a user-friendly way?


Here's a review of the key developments in monitoring technology and the features your providers care about the most. Plus, we've compiled "A Reference Guide to Monitors" on pages 66-67.

Improved pulse oximetry
Measuring pulse oximetry - changes in the oxygen content of arterial hemoglobin - is the monitoring feature most prone to be "thrown off" by external factors. Some monitors are more likely than others to temporarily produce inaccurate pulse oximetry readings and false alarms, says Alexander Liu, MD, of Van Nuys, Calif. Three common factors that can disrupt a pulse oximetry wave form monitor are a patient's sudden movement, low perfusion and electronic "chatter" from the other equipment in the room, says Dr. Liu.

To correct the problem, providers generally lean one of two ways - they either favor a stand-alone pulse oximeter that only performs the one function or they opt for a multi-function monitor that has corrective software installed that keeps the pulse oximetry reading on course. Dr. Liu prefers an oximetry-only monitor. "They do a great job and they cost about $500," he says. On the other hand, Hadad Miriliakbari, MD, of New York says it's wiser to shop for a multi-function monitor with strong pulse oximetry performance than to configure multiple instruments. "The more integrated," he says, "the better."

Regardless of the chosen means of pulse oximetry, providers consider these to be must-have features:
  • Real-time SPO2 saturation readings. They should have a standard accuracy deviation of no more than about a couple percentage points under most OR conditions.
  • Programmable alarm limits. These reduce the chances of a false alarm during a case.
  • Convenient sensors. Depending on the manufacturer, pulse sensors are available for forehead, fingertip, or ear placement. Different providers have different preferences.


User-friendly readouts
A common complaint about monitors is that the displays are sometimes hard to read. "As monitors first got more compact a few years ago, we lost a bit in terms of visual ease, but today the readouts are easier to adjust and view than ever before," says Dr. Liu, who has used a variety of new and old monitoring equipment in the four facilities he covers. Keep in mind that the anesthesia provider doesn't just say in one spot the whole time and not every monitor is easily visible from anywhere in the OR. "If the monitor doesn't have displays I can customize to make adjustments such as larger readouts when I'm across the room, I don't want it," says Arthur Lemon, MD, of Raleigh, NC.

Dr. Lemon finds that subtle variations in the readability of displays makes a major difference in terms of case times and user eye fatigue. For example, he strongly monitors color-coded readouts, a feature that more and more companies have incorporated into their monitors. The multi-colored readouts serve a very practical purpose - they let the provider's eye immediately find the desired reading (EKG, for example) and return his attention to the patient more quickly.

Outpatient-friendly monitors
With the development of new surgical techniques, new anesthetic agents and shifting economics, the vital signs monitor market has continued to evolve further and further to gearing products specifically toward the outpatient surgical market. These changes take on several forms.
  • Smaller, more portable design. In the outpatient surgical world - especially in the ASC and office surgery realm - faster OR set-up and turnover is crucial. Most companies now use compact design and portability as selling points for their monitors. Says Dr. Lemon, "The monitors are getting more and more compact. Nowadays, practices dictate that you must be able to set up the monitor quickly and easily wherever you are working on a patient - be it an OR, a procedure room or an office suite."
  • Monitors designed for conscious sedation procedures. If your facility performs a lot of its cases under regional anesthesia, twilight and IV sedation, you may want to look into a monitor geared toward this type of anesthesia. The characteristics of a good conscious sedation monitor, according to Los Angeles MD Harris Norton, include easy-to-read measurements of pulse oximetry, pulse rate and end tidal CO2; push-button controls and an adjustable alarm system. He advises, "These are lower risk, shorter procedures in many cases. You rarely need to monitor temperature during conscious sedation, so you can live without the temperature readout to save money."
  • Improved gas analysis. Improved capnography (the measurement of carbon dioxide concentrations in respiratory gases) is helping make anesthesia more efficient and safer.


"Even the most basic of the monitors out on the market now have the ability to detect respiratory agents and a variety of anesthetic gases," says Adam Dorin, MD, of Chevy Chase, Md "This is clearly a good tool for providers."

However, the more sophisticated monitors provide more information about specific anesthesia gas concentrations. Why is this valuable? "Our goal is always to use the lowest necessary concentrations of anesthetic agents. Any tool that helps you become a more efficient clinician is beneficial to the practice," says Dr. Novosad.

Integration with adjunct monitors
Vital signs monitors are increasingly being made to work side-by-side with the various adjunct monitoring technologies that have taken hold: including consciousness monitoring and nerve monitoring.

"Traditionally, we relied on vital signs and our own clinical experience to determine the appropriate amount of anesthesia. Now we integrate other measurement tools to make fine-tuned adjustments to the specific amount of anesthesia needed for each patient," says Dr. Novosad.

The result? A higher percentage of fast-tracked cases, fewer and less severe post-operative side effects, shorter PACU stays and more predictable post-op recovery, says Brent Burke, MD, of Indianapolis, Ind.

Click here for "A Reference Guide to Monitors".

Contact Bill Meltzer at [email protected] or 610.240.4918, ext 13.

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