Patient Safety Tip of the Week

March 17, 2009 More on MRI Safety

Many of our columns have highlighted the radiology suite as a site where many patient safety issues occur. In our October 16, 2007 Patient Safety Tip of the Week “Radiology as a Site at High-Risk for Medication Errors” we noted at least 14 factors that make adverse events more likely in the radiology suite. Undoubtedly there are many more contributing factors and conditions. Our September 16, 2008 Patient Safety Tip of the Week “More on Radiology as a High Risk Area” highlighted patient safety issues related to transportation to the radiology suite as well as numerous other safety issues related to radiology.

The MRI suite has virtually all the same potential risks that we see in the radiology suite plus a whole host of additional risks that are associated with the unique features of the MRI scanner and the special construction and design of the MRI suite to accommodate the scanner. In our Patient Safety Tip of the Week for February 19, 2008 “MRI Safety” we discussed Joint Commission’s Sentinel Event Alert “Preventing accidents and injuries in the MRI suite” and The American College of Radiology’s updated guidance document for safe MR practices published in the June 2007 issue of the American Journal of Radiology (Kanal et al 2007). These two document outline multiple safety issues related to MR imaging and provide numerous excellent recommendations about MRI safety. This month’s What’s New in the Patient Safety World column “Risk of Burns during MRI Scans from Transdermal Drug Patches” discusses the burns during MRI from drug patches, something we had previously discussed in our Patient Safety Tips of the Week for February 19, 2008 “MRI Safety” and May 13, 2008 “Medication Reconciliation: Topical and Compounded Medications”.

Now the American Society of Anestheiologists (ASA) has released its “Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging”. Don’t let the title fool you – you can learn a lot about MRI safety from this paper regardless of whether you are an anesthesiologist or other healthcare professional.

This ASA practice advisory is based as much on consensus and expert opinion as it is on hard evidence. Therefore the ASA notes that this advisory does not carry the same weight that would a standard, guideline, or absolute requirement. Nevertheless, the recommendations are practical and the advisory raises patient safety and environmental safety issues that all healthcare workers need to be aware of.

All staff should receive education about the general risks of the MRI suite, including the segmentation of the suite into 4 zones (see our Patient Safety Tip of the Week for February 19, 2008 “MRI Safety”), the health risks associated with this environment (eg. high decibel levels and the high-intensity magnetic fields), and information about the risks of ferromagnetic items and implantable devices that should not be brought into zones III or IV, and education about the protocols for responding to code blue situations in the MRI suite.

All anesthesia team members, like all other patients and personnel, must be screened for ferromagnetic materials, foreign bodies, or implantable devices before entering Zones III and IV. Think of all the ferromagnetic materials a typical physician might have on his or her body: stethoscopes, pens, watches, wallets, hairclips, nametags, pagers, cell phones, credit cards, batteries, eye glasses, PDA’s, and maybe even an iPod! These cannot be taken into zones III or IV.

The anesthesia team participates in screening the patient for patient-related risks. These include age-related risks and health-related risks, plus specific risks or contraindications related to the presence of ferromagnetic materials or implanted devices.

The anesthesia team needs to work with radiologists and all other relevant parties to ensure that equipment to be used in the MRI suite is safe for use in that suite. Caution must be taken with all monitoring equipment, particularly paying attention to leads and wires and especially loops that may become excessively heated when exposed to the magnetic fields.

The anesthesiologist needs to develop a plan for implementing anesthesia care before each individual case. Such a plan should be done in collaboration with other personnel who will be involved in the care of the patient, including the MRI technician, radiologist, radiology nurse, other clinical personnel accompanying the patient and even the facility biomedical engineer. They need to find the appropriate location of moveable equipment in relation to the gauss lines within the MRI suite. The plan should include where the optimal line of sight will be for both observing the patient and any monitors. The plan needs to have a contingency for emergencies. The latter would include how to summon assistance during an emergency, where emergency medications and equipment will be located, where the patient will be evacuated to (note that rescuscitation is begun as the patient is transported to the previously designated safe area outside Zone IV), and how emergency response personnel need to be prevented from entering Zone IV. The plan also needs to address the level of sedation or anesthesia anticipated and what to do if a higher level is needed or inadvertently achieved. The plan needs to specify how the intravenous drugs, oxygen, anesthetic gases, suction and waste management will be handled. In some cases where MRI-safe or MRI-conditional equipment is not available, special conduits called “wave guides” may have to be used for some of these management activities. When deep sedation is used or when direct observation of respiration cannot be performed during moderate sedation, monitoring of exhaled carbon dioxide should be considered (simply monitoring oxygen saturation by pulse oximetry is insufficient in such circumstances). It should also be remembered that the magnetic fields may interfere with interpretation of some monitoring tools, such as EKG, so some data must be interpreted with caution.

We’ve discussed surgical and neonatal fires in several columns on this website (see our Patient Safety Tips of the Week for December 7, 2007 Surgical Fires, January 29, 2008 “Thoughts on the Recent Neonatal Nursery Fire”, and April 29, 2008 “ASA Practice Advisory on Operating Room Fires”). The fire triangle consists of a fuel, a heat source, and an oxidyzer. So a patient who is receiving supplemental oxygen certainly could be at risk for a fire under certain circumstances during MRI scanning. We have already pointed out that burns may occur in association with ferromagnetic substances, implanted devices, or certain monitoring equipment. The magnetic current passing over leads or wires, particularly in certain looped configurations, may generate a tremendous amount of heat. Patient fires have been reported during MRI scanning, albeit rarely, so the same precautions and planning should be undertaken as would be done in the OR. Everyone needs to know their role in the event of a patient fire.

The entire staff must also be aware of the remote possibility of a “quench”. That is what happens when the magnet shuts down, catastrophically releasing gases (often under high pressure) and dissipating oxygen. The emergency protocol for a quench must be followed. If it is possible to rescue the patient and remove him/her from Zone IV, oxygen should be administered immediately.

Postanesthetic care should be consistent with all standards that would apply to postanesthetic care elsewhere in the institution.

There are a few issues we’d add to this otherwise excellent ASA practice advisory. First is the importance of determining up front whether the MRI is truly indicated, whether the potential benefits of performing the MRI outweigh the potential risks, and whether alternative safer imaging modalities might suffice. In many of the incidents we’ve seen occurring in ICU patients transported to the MRI suite or radiology suite, we’ve been surprised at how often the scan being done was really of marginal value.

Second is the need for a huddle/timeout before the procedure is performed. We should approach doing MRI on these critically ill patients in the same manner in which we approach patients going to the OR. A “huddle” or whatever else you’d like to call a pre-procedure briefing is very important in such cases. Not only do you need to know you have all the equipment needed, but you also need to know everyone’s role and have contingency plans for emergencies. This is where you ensure all parties know what to do if there is a fire or if there is a cardiopulmonary arrest or a “quench”. You discuss what location you will need to move the patient to in such events. You discuss the availability and location of equipment and medications you may need. You discuss the line of sight required and where the monitoring equipment will be deployed. You may need to discuss also how you will communicate (with both staff and patient) given the high noise levels associated with MRI scanning. You should probably even discuss the potential impact of the lighting levels in the various zones (and fact that you may not be able to wear your ferromagnetic glasses in Zones III and IV).

Third, really related to the above, is use of a checklist. To remember all the needs for the procedure (which vary be individual patient) and the contingencies you have to plan for is really too much to expect for any individual or group of individuals. That’s where the simple checklist comes in: it helps you to remember details you might otherwise overlook.

Fourth, you need to practice. We wonder how many MRI facilities, particularly hospital-based ones, actually simulate an emergency during MRI scanning. Looking for a topic for a FMEA (failure mode and effects analysis)? What better one than an emergency in your MRI suite?

References:

Joint Commission. Sentinel Event Alert. Preventing accidents and injuries in the MRI suite. Issue 38. February 14, 2008

http://www.jointcommission.org/SentinelEvents/SentinelEventAlert/sea_38.htm

Kanal E et al. ACR Guidance Document for Safe MR Practices: 2007. AJR 2007; 188: 1-27

http://www.acr.org/SecondaryMainMenuCategories/quality_safety/MRSafety/safe_mr07.aspx

Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging.

A Report by the American Society of Anesthesiologists Task Force on Anesthetic

Care for Magnetic Resonance Imaging. Anesthesiology. 110(3):459-479, March 2009

http://pdfs.journals.lww.com/anesthesiology/2009/03000/9.pdf

http://www.patientsafetysolutions.com

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