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Thinking of Buying...Anesthesia Workstations
From ventilators to vaporizers, separating your wants from your needs.
Bryan Sieber
Publish Date: October 27, 2008   |  Tags:   Anesthesia

The ideal anesthesia workstation? Ask 10 different anesthesia providers and you'll probably get 10 different descriptions. The key is to separate your wants from your needs. For example, you might want a slave monitor to place over a patient's chest during induction and intubation; then, you wouldn't have to look over your shoulder just as you finally visualize the vocal cords of an overweight patient with a small mouth, short chin and no noticeable neck. Unfortunately, we all live with budget constraints, so what do we really need?

A workstation should be as compact and lightweight as possible while being able to provide reliable service for many years with little required maintenance. It should be wired to provide sufficient electrical outlets to power necessary accessory items such as a gas analyzer, an appropriately sized monitor or a notebook computer. Any workstation needs to securely hold at least three E-sized gas cylinders for oxygen, air and nitrous oxide.

It should be easily transportable with caster wheels equipped with deflector devices on each one so that when a cord or other line is encountered on the floor in the path of the moving machine, it won't endanger anyone. The workstation should also provide a single mechanism that locks the wheels to prevent it from rolling away.

What else do you need your workstation to have?
Monitors. Though I've never had a problem with a built-in monitor, I prefer a freestanding add-on. It seems to me that the aftermarket monitors are more flexible, more reliable and offer better display options than the built-ins. If an add-on monitor misbehaves, you can switch it out with another one until your bio-med department or sales rep has time to correct the problem.

Look for a nice touchscreen monitor. With these you don't have to scroll through four or five lists of options to get the item you want. A touchscreen lets you see a history of vital signs, silence the alarms or print in a matter of two or three touches with your finger. Pop-ups also make it easy to quickly change the displays. For example, on the EKG tracing, a pop-up might appear that lets you change the leads, or increase or decrease the gain. Touch the breaths-per-minute display and you can adjust the alarms for minimum number of breaths per minute, increase or decrease the range of display or set the type of agent selection from automatic to manual. This comes in handy when you decide to change agents during a procedure, such as from isoflurane to sevoflurane. This type of monitor is available from many manufacturers.

The monitor I use has a permanent display, or tool bar, at the bottom of the screen that lets me activate or deactivate the blood pressure cuff and call up the vital signs from the time that the patient was connected to the monitors. It also has a calculator and volume control. Ideally the monitor would be in the range of 20 to 25 inches on the diagonal with the capability to color-code all the displays independently. Any screen pop-ups that enter the monitor display should not be allowed to obscure the view of the EKG leads, blood pressure or oximeter displays at any time. There should be a "main screen" icon that immediately returns the screen to a normal display. It also helps to have a wide volume range for the warning beeper and the audible indicator for the EKG-pulse oximeter; at times the operating room can become quite noisy from saws, drills and sometimes even the surgeon's favorite music.

Ventilation. The ventilator system should have a dedicated control screen. Besides being quiet, the ventilator should offer an adjustable tidal volume control for all sizes of patients, a wide range of inspiratory to expiratory ratios, variable positive end-expiratory pressure control and the option to ventilate the patient by setting the peak inspiratory pressure. Alarms should sound for apnea, anesthesia circuit leak, loss of ventilatory pressure, negative pressure while in the positive pressure mode, low oxygen concentration, tachypnea or a peak inspiratory pressure over the set value. The control screen should present you with a digital reading of the expired volume, a waveform and digital readings for peak positive inspiratory pressure as well as negative inspiratory pressure. The "pop-off" valve and the switch to change from hand ventilation to mechanical ventilation should be located in close proximity to the hand ventilation bag.

Personally, I like workstations that let the ventilator area swing out from the rest of the machine. When the patient is aligned 90 degrees from the anesthesia machine, I can break away the ventilator portion of the workstation and keep the monitors and controls in a more convenient profile while keeping the anesthesia circuit a reasonable length.

Some newer machines boast new pressure support settings, but I can't think of a good reason why pressure support ventilation should be used at all in an outpatient setting. Most outpatient surgery is done on patients in ASA classes of 1 to 3 and under certain weight limits. If the patient needs more help than that, maybe he shouldn't be heading home that same day. If possible, I like to keep my patients breathing on their own, even if intubated with an endotracheal tube. That way, I can judge their level of pain other than just by their heart rate and blood pressure.

I also can't think of a good reason to use simultaneous intermittent mandatory ventilation (SIMV) in the operating room. SIMV is usually used to wean patients who have a poor pulmonary history off the ventilator when it would probably be more prudent to have these patients go to an ICU. I don't think that the patient would tolerate the assistance from the ventilator very well and this could lead to patient bucking and movement during the procedure. Bottom line: If you're giving a good, balanced anesthesia, the patient should be able to breathe on his own.

  • Lights. Your machine should have a soft light source that broadcasts light onto the flat desk area where the anesthesia provider creates his record for the procedure. This light would also illuminate the gas flowmeters and the anesthesia agent vaporizers. Ideally, this light would be controlled by a rheostat to go from dim to full illumination. Barring that, perhaps there could be a brighter light on an adjustable arm that could be manipulated into any position needed.
  • Waste gases. Ideally, waste gasses would exit through a vacuum line equipped with an easily accessible valve. Too often the control for limiting the amount of suction to the machine is located out of the anesthesia provider's reach. You should be able to easily open the vacuum valve at the end of the delivery of anesthesia to efficiently remove the anesthetic gases from the patient's lungs and facilitate a quick recovery.
  • Oxygen sensor. This should be located in an area that is easy to access for calibration. Carbon dioxide absorber canisters should be extremely accessible and easy to change. Modules for non-invasive blood pressure, EKG, arterial blood pressure, central venous pressure and BIS should be of a type that can be easily replaced with a standby module if suspected faulty.
  • A retractable shelf. This is to hold a notebook computer that you'd connect to the facility's server and use to retrieve a patient's history, lab results, orders and so on. There should also be Internet access available to find up-to-date information regarding anesthetics and co-existing diseases or other syndromes.
  • Vaporizers. There should be space for at least three anesthesia agent vaporizers to be mounted to the machine. At least one position should have an electrical outlet for a desflurane vaporizer for the heating unit located in the vaporizer. Of course, a lockout device should be fitted so that only one anesthetic vaporizer can be in use at any given time. In this same general area, there should be gauges indicating the pressure for oxygen, air, and nitrous oxide coming from the central gas supply of your facility as well as any opened gas cylinders.

Set it and forget it
Maybe some of the bells and whistles offered on newer machines are just that, but you shouldn't be so reluctant to change that you forgo an easier way to ensure that the patient ends up comfortable and stable in the recovery room. The less time you spend trying to make the machinery work the way you want, the more time you'll have to devote to your patient and make any needed adjustments.

Anestar Plus and Spectrum OR Monitor
(800) 288-2121
Price: $50,000 or less, depending on options
FYI: The machine features a unique integrated breathing system with automatic compliance compensation for pressure controlled and pressure support ventilation, but doesn't feature SIMV. Its breathing system warms and humidifies the patient's air so he can breathe more easily while eliminating condensation and rainout. The Spectrum OR is controlled by a knob and has the ability to incorporate different aftermarket options such as a brainwave-monitoring feature, says the company.

(412) 787-8383
Price: Not disclosed
FYI: Designed as a workflow-oriented workstation, Apollo's open platform architecture lets it custom fit a variety of workflow environments. The Infinity Patient Monitoring System and Innovian Anesthesia Information System can be integrated with Apollo to create a harmonized graphical user interface across all the hospital's devices and provide fast access to patient data, vital signs and lab results. The new management resource will save customers on investment and maintenance costs, says the company.

GE Healthcare
S/5 Aespire
(800) 345-2700
Price: Aespire 100: low $20,000s, Aespire 7900: mid to upper $30,000s
FYI: Advanced breathing system has a small volume (2.7 liters), allowing for faster washing in and out of agents when the clinician changes settings, says GE. The breathing system can be removed in one piece and disassembled without any tools. The Aespire 100 and 7100 machines offer pressure and volume control, while the Aespire 7900 adds pressure support and SIMV. Each is lightweight with a small footprint, intuitive user interface, electronic PEEP and alarm management, says the company. Also features optional suction control integrated with the canister attaching to the base of the machine. The Cardio Cap 5 monitor, sold separately, uses a ComWheel and "quick keys" to interact with the menus. Optional gas and agents analysis can be built-in.

Prima SP3
(800) 328-6216
Price: Less than $40,000
FYI: Touted by the company as a "traditional anesthesia machine" that does the basics for less, the Prima SP3 offers advanced ventilation, including volume, pressure, pressure support, SIMV and SMMV. The ventilator has a built-in, 8.4-inch color touchscreen. Its integrated bellows limits potential connection leaks and Selectec mounting lets the user interchange vaporizers from machine to machine. Specifically designed for low-flow anesthesia (50 to 70ml/min), the 2.5-liter compressible volume absorber is equipped with mass flow sensors in lieu of disposable sensors, thus eliminating the cost of replacements, says Keomed. The heated absorber also reduces the effects of moisture so that the sensors don't require drying out, says the company.

Oceanic Medical
Magellan 2200
(913) 974-2000
Price: Model 1: $28,605, Model 2: $45,676, Model 3: $15,056
FYI: Built for use in battlefield environments, the Magellan is portable and rugged, says Oceanic. The Magellan is the only anesthesia device to have passed ruggedness testing known as MIL SPEC 810. The Model 2 ($45,676) can operate on electricity from any outlet in the world, a backup battery or direct current from an automobile battery. It can even operate as a fully pneumatic device, says the company. You can also completely bypass the ventilator and still safely deliver an anesthetic agent.

Paragon Service
Platinum SC430 Anesthesia System
(800) 448-0814
Price: $32,900
FYI: The Platinum SC430 combines sophisticated ventilation features with ease of use, says Paragon. Standard ventilation modes include volume mode, pressure mode and pressure support mode. The AV-S ventilator features an ascending bellows and an 8.4-inch color touchscreen. Electronic PEEP, pressure limiter and spirometry are also standard. Other standard features include ultra low-flow capabilities; O2, N2O and air dual flowmeters; double vaporizer manifold; work surface lighting; integrated electrical outlets; writing tray; auxiliary oxygen flowmeter; scavenger and high pressure hoses. The Sigma Delta vaporizer doesn't require scheduled service for rebuilds.

Spacelabs Medical
BleaseSirius Anesthesia System
(800) 522-7025
Price: Not disclosed
FYI: The BleaseSirius machine features open architecture, large work surfaces, storage and maneuverability, says the company. It has a small footprint, strategically placed handles and a central brake that lets it move and lock into place easily. Monitors fit onto side brackets, leaving the top shelf open for storage. Frame, ventilator and mounting options make the system highly customizable. Lockable drawers keep the high-capacity storage areas safe. Wireless connectivity and WinDNA make patient data easily accessible. Monitor features user-preset display configurations. A maintenance-free vaporizer features a 10-year warranty, says the company.