Choosing and Anesthesia Machine - What You Need to Know

Although the basics of anesthesia machines haven't changed a great deal over the last few years, several new features may make them safer, easier, and more efficient to use. If you're in the market for a new one, either because you are adding new procedures that require general anesthesia or because your old machine is antiquated, here's some advice on how to make your decision.

Purchase a machine with the proper safety features
If your facility performs surgical procedures requiring general anesthesia accompanied by muscle relaxation, you'll need to purchase a traditional hospital-grade anesthesia workstation. Here are the safety features you should look for:

A standing bellows ventilator:
All modern hospital-grade machines include either a hanging bellows or standing bellows ventilator incorporated into the mechanics of the machine. We would strongly recommend purchasing a machine with the latter variety, since a standing bellows collapses immediately if there is a leak in the machine, or if the patient becomes disconnected. A hanging bellows continues to refill even if there is a substantial leak. As an extra precaution, you may want to purchase a machine with a disconnect alarm to warn the anesthesiologist if a disconnect occurs.

Most modern machines have a standing bellows ventilator, but you may run into the hanging bellows variety if you are considering a refurbished machine. Regard this type with caution and carefully weigh the short-term financial benefits with the safety issues.

A fail-safe mechanism:
Make sure your machine also has a fail-safe mechanism, particularly when oxygen and nitrous oxide are being delivered. If the oxygen becomes depleted, the fail-safe mechanism will reduce the nitrous oxide flow to prevent a hypoxic gas mixture from being delivered to the patient. It will also assure that when the flow of nitrous oxide is increased, the flow of oxygen will be increased concurrently.

An oxygen sensor and backup gas cylinders:
Most modern machines will have an oxygen sensor to measure the percentage of oxygen delivered as well as a variety of gauges to alert the user when oxygen is running low. The machine should also include small E-cylinders of oxygen and/or nitrous attached to the back of the machine to serve as reserves if the main source becomes depleted.

Other features to consider include:
At least two vaporizer ports:
If you are doing adult and pediatric cases, it can be useful to have at least two vaporizer ports. Children need to be induced with halothane or sevoflurane; adults are most often induced via IV, and you may wish to maintain them with isoflurane.

Mobility:
If you think you'll be moving the machine from room to room fairly often, look for a unit with easy maneuverability, large lockable casters and a push handle to make it easy to move.

Storage space:
The anesthesia machine workstation you purchase should incorporate enough shelves and drawers for holding monitors and storing supplies such as endotracheal tubes, stylets, and tubing. It's also useful if the machine has an area to attach a suction regulator or has a built-in suction system.

The three features mentioned above will definitely make you and your staff more efficient. Some of the newer machines also have extra "bells and whistles," such as computer data ports, electronic gas delivery, and heat and moisture exchanging filters. In our opinion, these are personal preference items. We know of no clear pattern to suggest that these features do anything to improve patient outcomes.

If you don't have the budget to buy new anesthesia workstations, don't despair - you may not need to buy a full featured machine at all, and even if you do, you may be able to find a great deal on a refurbished unit.

If you'll be doing procedures that require general anesthesia without muscle relaxation, you may be able to get by with a dental anesthesia machine, or one of the many anesthesia machines that do not have ventilators. Regardless of your choice, assure that the workstation has the appropriate safety features to prevent the delivery of a hypoxic gas mixture.

Refurbished machines, which can cost one-half to one-third the price of a new machine, may be worth a look - even one that is five to 10 years old may serve your needs. If you decide to purchase a refurbished machine, you want to make sure the company selling it to you is reputable; it's a good idea to ask for a client reference list. Once you've decided on a machine, have a biomedical engineer evaluate if it is in good condition, upgradable, and intact.

Two possible drawbacks of purchasing a refurbished machine are that it may require more maintenance than a newer one (a new machine generally has to be serviced once a year); also, it may lack the bells and whistles that newer machines offer.

Just three other thoughts - these are not points specific to the anesthesia machine, but are important to consider if you are performing general anesthesia:

Design an appropriate medical gas system:
The medical gas system delivers oxygen, nitrous oxide and air from a central source to the machine. Depending on the gases that you are using, a couple of large oxygen and/or nitrous cylinders chained to the wall in the corner may work just fine. If you have the resources, you may want to upgrade and build a separate tank room, alarm panel, and piping from the tank room to an outlet in the operating room.

To remove waste gases, it's best to have a pump that actively gathers waste gas from the anesthesia machine and shuttles it to the atmosphere. Such a system may cost you $3,000 to $10,000, but it is well worth the cost. An active gas system ensures that waste gases are pushed out of the OR and ensures your patients' and staffs' safety. A less advisable way to scavenge waste gas is to punch a hole in the wall and, via tubing, passively shuttle waste gas from the machine to the exterior.

Keep the proper monitoring devices on hand:
These include an automated noninvasive blood pressure cuff, pulse oximeter, electrocardiogram, and end tidal carbon dioxide monitors. You may also want to purchase a safety gauge that measures circuit pressure to help troubleshoot a variety of clinical scenarios, such as bronchospasm, a kinked endotracheal tube, or changes in lung compliance.

Prepare for malignant hyperthermia:
Malignant hyperthermia (a rapid onset of extremely high fever with muscle rigidity) occurs in one in 15,000 patients. Even though the condition is rare, if you are using volatile anesthetics, you must have a malignant hyperthermia protocol in place, including the immediate availability of ice and dantrolene.

When preparing your facility for anesthesia and purchasing your anesthesia machines, the best piece of advice we have is to discuss all your options with your anesthesiologists. They are the best people able to assess the anesthetic needs of the patient and to discern the possibilities and limitations of the facility.

Four Machines to Consider

Yasmine Iqbal, Editor

Drager Narkomed Mobile
The Narkomed Mobile anesthesia system, from Dr?? ?ger Medical, is a full-featured anesthesia machine with a compact design (163 pounds). It is equipped with an integrated ventilator and a monitor that analyzes volume, pressure, and oxygen data. It also includes large casters to help it travel easily over all surfaces, and it can be folded up into an even more compact shape to allow for easy transport. Call Dr?? ?ger Medical at (800) 462-7566 or visit www.draeger.com.

Drager Julian
The Julian anesthesia machine is a compact unit (198 pounds) that features a single user interface for gas delivery, ventilation, and monitoring. Up to now, the anesthesiologist had to set the nitrous oxide and oxygen, or air and oxygen, separately to achieve the desired flow. The oxygen concentration depended on whether nitrous oxide or air was used as a carrier gas. The Julian allows the total flow to be changed with one rotary knob - once you set the oxygen concentration, it is maintained independent of the carrier gas. Call Dr?? ?ger Medical at (800) 462-7566 or visit www.draeger.com.

MIE Falcon
The Falcon, manufactured by MIE, is a full-sized machine, but at 300 pounds, it may be considerably smaller than most full-size units. You can use the Falcon for all types of general anesthesia, according to the company, and customize the machine with your choice of vaporizers, ventilators, shelving options, and monitoring systems. The cost varies from $32,000 to $40,000 for a fully loaded unit. The unit comes with a two-year warranty. Call MIE at (913) 367-9096 or visit www.mie.co.uk.

MIE Hawk
At 25 pounds, MIE's Hawk machine may be an interesting option for office-based surgery centers. It is specifically intended for the induction of anesthesia. The unit may be customized with a choice of four vaporizers. The cost of a completely equipped machine is around $10,000. The Hawk also comes with a two-year warranty. Call MIE at (913) 367-9096 or visitwww.mie.co.uk.