There are a lot of variables to consider when choosing a warming cabinet, but for the most part you need your cabinet to do 2 things, and to do them well, consistently and reliably. Cabinets need to get and keep your fluids and blankets warm. Some facilities may also want the option to warm blood products, but that won't be necessary in most outpatient settings. Let's take a look at some of the features that will help ensure that your blankets and fluids are both warm — but not too warm — and available when you need them.
Warm blankets and fluids separately
If you're in the market to upgrade or replace your warming cabinets, the first and most important consideration is that they come with at least 2 different compartments, and that each has its own thermostat. Otherwise, you'll be wasting money. That's because it's essential that fluids and blankets be warmed separately. Blankets can and should be warmed to a higher temperature than fluids (see "How Warm Should Blankets Be?" on page 79), or else they'll provide little in the way of comfort and safety by the time they reach patients. You'll keep patients toasty and comfortable by aiming to have bedding temperatures about the same as patient temperatures.
Fluids, on the other hand, can end up cooking the proteins in blood if they're too warm. So how warm should they be? Look for manufacturers' recommendations. Every bag should tell you what temperature range to aim for and how long you can store the fluid at that temperature — typical specifications will be about 21 days at 96 to 98°F. The differences in recommendations stem mostly from the material used to house the fluids. The plastic in the bags is what denatures over time in a heated environment.
Worth noting: Some manufacturers recommend that cabinets be used solely to warm blankets and that fluids be warmed separately in infusion lines with the patient. There's an ongoing philosophical argument where this is concerned, but there's no reason not to store and warm fluids in cabinets. As noted, every IV bag manufactured in the United States says what temperature it can be warmed to, and how long it can be stored at that temperature. There's no statute or rule anywhere that says you must do otherwise. As long as you mark the date on the bag and stay within the specified time period (and let's face it, outpatient centers and hospitals almost never keep fluids warmed more than 3 days), it's easier and more convenient to use a warming cabinet.
Rapid warming time is another very important consideration. In any busy facility, you're bound to occasionally have days when you realize at 7 a.m. that you don't have enough IV fluids, or fluids for arthroscopic or infusion procedures. Fortunately, newer cabinets offer rapid warming times with uniform heating, so depending on the size of the load, when you suddenly realize you may be in danger of coming up short, you can still have the warm fluids you need by 9 a.m. (Larger loads may still take up to 6 hours or so to be adequately warmed.)
With older cabinets, you had to check the temperature readings once a week and enter those numbers in a log for the next time the surveyor came around. And of course no one knew for sure when those temperatures were really being recorded. Some newer cabinets can store temperature data for at least 2 years, in compliance with CMS regulations. Just press a button and the cabinet will store the date and time that you checked the temperature. That's a great convenience.
Cabinets with glass-window doors make it easy to see how your supplies are holding up without having to open the door and allow precious heat to escape. The wider the view, the better, so you never end up having to guess what's inside.
Doors and heating compartments that are fully insulated help keep the heat where it belongs — inside the cabinet. You don't want to spend extra money heating the area around the cabinet. Gasketed doors or doors with magnetic latches help make sure cabinets close and stay tightly sealed. Incidentally, most cabinets use fans to circulate air and ensure uniform heating, but one manufacturer touts its electrothermal cables, which it says eliminate the need for fans, lint traps and other moving parts. That's something to consider.
A large, bright LED display will let you quickly confirm set points and actual temperatures. It's helpful to be able to see at a glance and from a distance that internal temperatures are consistent with the temperatures you've set.
Some newer models have both audio and visual alarms that alert you if the chamber temperature gets too high or too low. That's crucial, since, as noted, temperatures need to stay within a specified range to ensure patient safety and fluid stability.
Since needs and loads may change over time, make sure shelving is customizable, like the shelving in a refrigerator. If your cabinet is staying put once you have it in place, which is likely to be the case, the priority is to make sure it has a good sturdy base, so there's no danger of its tipping over. But if the cabinet might be moved between locations, there are both countertop models and floor models that can be equipped with heavy-duty casters and wheels. Models with doors that hinge both left and right also promote mobility and flexibility by providing a wider range of possible locations. And of course you want to make sure any cabinet you buy meets UL standards.
Do you want or need to be able to access the same cabinet from both inside and outside the OR? Pass-through cabinets offer two-sided access to the same supplies.
DEGREES OF DIFFICULTY?
We know that blankets begin to lose heat once they're removed from warming cabinets and exposed to ambient air. In fact, if enough time passes, by the time they reach the patient, they won't deliver much in the way of the soothing warmth they're intended to provide.
So it might be tempting to overheat them. In fact, a study published in the Journal of PeriAnesthesia Nursing in 2013 argues that it's safe and practical to warm blankets in cabinets that have been set to a blistering 200°F (93°C).
Don't do it!
That's the word from both AORN and the ECRI Institute, a non-profit patient safety research organization in Plymouth Meeting, Pa. Instead, say both, the maximum temperature for blanket and linen warming cabinets should never exceed 130°F (54.4°C).
But what about the study? How could there be such a huge gap in recommendations? According to ECRI, in the best of all possible worlds, a blanket warmed in a cabinet set at 200°F might actually be safe. But there are far too many variables involved to assume that no harm will ever come from such a practice.
ECRI's recommendation is based on studies of multiple burn cases involving patients in hospitals where warming cabinets were set to 150°F or higher. In every burn case, blankets were either rolled or left folded when they were applied to the patients. In other words, patients are likely to be fine with hotter blankets if the blankets are fully unfolded before they come into contact with skin. But since there's no way to ensure that folded or rolled blankets will never be applied to patients, the practice can be a nasty burn waiting to happen.
Additionally, ECRI points out, blankets are sometimes applied to insensate or unconscious patients, who don't know and can't respond when they're too hot. In its investigation, ECRI uncovered cases involving sedated and anesthetized patients who were given folded or rolled blankets and who suffered second-degree burns with blistering.
While burns aren't completely impossible even at 130°F, says ECRI, they're highly unlikely. But the risk increases dramatically as temperatures rise above 130°F.
Further, ECRI points out, the clinical value of heating blankets above 130°F is negligible, because the physics of heat transfer and thermodynamics render hot blankets incapable of actively increasing a patient's core temperature. Passive warming with blankets can only reduce patient heat loss