Epidural hematoma after outpatient epidural anesthesia

Evaluation of epidural and peripheral nerve catheter heating during magnetic resonance imaging

BACKGROUND

Many epidural and peripheral nerve catheters contain conducting wire that could heat during magnetic resonance imaging (MRI), requiring removal for scanning.

METHODS

We tested 2 each of 6 brands of regional analgesia catheters (from Arrow International [Reading, Pennsylvania], B. Braun Medical Inc [Bethlehem, Pennsylvania], and Smiths Medical/Portex [Keene, New Hampshire]) for exposure to clinical 1.5- and 3-T MRI. Catheters testing as nonmagnetic were placed in an epidural configuration in a standard human torso-sized phantom, and an MRI pulse sequence applied at the maximum scanner-allowed radiofrequency specific absorption rate (SAR) for 15 minutes. Temperature and SAR exposure were sampled during MRI using multiple fiberoptic temperature sensors.

RESULTS

Two catheters (the Arrow StimuCath Peripheral Nerve and B. Braun Medical Perifix FX Epidural) were found to be magnetic and not tested further. At 3 T, exposure of the remaining 3 epidural and 1 peripheral nerve catheter to the scanner's maximum RF exposure elicited anomalous heating of 4°C to 7°C in 2 Arrow Epidural (MultiPort and Flex-Tip Plus) catheters at the entry points. Temperature increases for the other catheters at 3 T, and all catheters at 1.5 T were 1.4°C or less. When normalized to the body-average US Food and Drug Administration guideline SAR of 4 W/kg, maximum projected temperature increases were 0.1°C to 2.5°C at 1.5 T and 0.7°C to 2.7°C at 3 T, except for the Arrow MultiPort Flex-Tip Plus catheter at 3 T whose increase was 14°C.

CONCLUSIONS

Most but not all catheters can be left in place during 1.5-T MRI scans. Heating of less than 3°C during MRI for most catheters is not expected to be injurious. While heating was lower at 1.5 T versus 3 T, performance differences between products underscore the need for safety testing before performing MRI.

[Ambulatory and day surgery]

Ambulatory surgical care is intended to save healthcare expenditure from the economical viewpoint. From the patients point of view significant advantages as well as specific disadvantages of ambulatory surgery are known. The increase in the volume and complexity of procedures provided in an ambulatory setting are driven by improvements in anesthesia and surgical technique as well as by changes in financing and reimbursement. Therefore careful quality control and scientific evidence for the safety of increasingly used complex surgical procedures for higher risk patients is essential. Reducing the surgical trauma by minimally invasive surgical techniques and very good controllability by modern anesthesia concepts is making the management of the postoperative period crucial for successful ambulatory surgery. Most of the complications and common problems during the postoperative period, such as pain, nausea and vomiting, are not specific for ambulatory surgery, but management places an increasing burden of responsibility not only on general and specialised physicians, but also on other health professionals, patients, and family members.