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Abstract & Commentary
Source: Miller AH, et al. Ultrasound guidance versus the landmark technique for the placement of central venous catheters in the emergency department. Acad Emerg Med 2002;9:800-805.
Ultrasound guidance (USG) for the placement of central venous catheters (CVC) has been recognized as a helpful adjunct in anesthesia and surgical literature since 1984, but has received little notice in the emergency medicine (EM) literature. To clarify the EM role of this emerging technique, Miller and colleagues compared USG to the traditional landmark technique (LMT) for insertion of CVC in ED patients without obtainable peripheral access.
The authors analyzed 122 cases of non-pregnant adults ages 30-60 seen during a six-month period in the ED of Parkland Hospital in Dallas. All had acute conditions requiring CVC, such as severe bleeding, hypotension, shock, or volume contraction. A subcategory of "difficult stick" cases included those with intravenous (IV) drug abuse, abnormal anatomy, peripheral vascular disease, coagulopathy, or morbid obesity. EM residents ("users") in years 1-3 performed all CVC insertions, under observation by EM faculty designated as "experienced users" based on prior insertion of at least 25 CVCs. Each user received two hours of hands-on training by radiology faculty. The ultrasound machine employed a 7.5 MHz linear probe covered in a sterile sheath with sterile gel to image the target vein and nearby artery for venous puncture with a large-bore needle. With either USG or LMT, time to first flash of blood into the syringe was recorded, along with number of puncture attempts and local complications. Seldinger technique was followed for each insertion. Vascular sites included femoral, internal jugular, and subclavian veins.
Time to first flash of blood was 115 seconds for USG, vs 512 seconds for LMT (p < 0.0001). Number of CVC attempts was 1.55 vs 3.54 for USG vs LMT, respectively (p < 0.0001).
Complication rate was similar with both techniques at 12% and 14% (p = 0.71) and included arterial puncture, hematoma, and pneumothorax. For "difficult stick" patients, USG by resident physicians was successful in 92%, compared to 66% success for LMT (p = 0.08). Among experienced users (faculty) attempting CVC in "difficult stick" cases, time to first flash was 57 vs 180 seconds, while number of attempts was 1.36 vs 2.67, respectively, for USG vs LMT. The authors conclude that USG results in quicker CVC access rates, fewer puncture attempts, and greater success in "difficult stick" cases than traditional LMT methodology.
Commentary by Michael Felz, MD
The statistical superiority of USG in time to flash (400 seconds less) and number of attempts (two fewer) is impressive to me and suggests that, regardless of one’s level of experience in CVC placement, ultrasound is an attractive adjunct for those of us placing central lines. I can recall, with fresh agony, dozens of tough access patients in which my residents and I labored for 15-30 minutes, probing for a central vein. Other possible benefits include lessened patient discomfort and decreased expense secondary to fewer discarded CVC kits.
The authors correctly indicate that some time (3-10 minutes) would be required to position the ultrasound machine and place a sterile sheath on the probe. This is a minor factor unless such machines are not available readily in one’s institution or ED. For my practice, four conclusions seem reasonable based on the Miller study: 1) USG would be useful to delineate exact juxta-arterial position of target central veins prior to CVC attempts, with or without adequate LMT palpation; 2) USG could be a "real time" image for needle guidance directly into the vein lumen; 3) USG could prove definitive after numerous unsuccessful LMT attempts at CVC; and 4) difficult peripheral access patients might be managed more successfully by USG methods of CVC before turning to alternative approaches such as cutdown procedures.
When it comes to central venous access, perhaps a picture is worth a thousand words—and about 400 seconds, in terms of quicker line insertion. Ultrasound can offer visual gains for those tricky central veins.
Dr. Felz, Associate Professor, Department of Family Medicine, Medical College of Georgia, Augusta, GA, is on the Editorial Board of Emergency Medicine Alert.