In Reply: —We appreciate the interest of Drs. Brull et al.  and Dr. Shankar in our case report1and we welcome their comments. Obviously, however, the fact that these two groups have not yet experienced any severe complication during ultrasound-guided blocks is by no means proof that their suggestions can eliminate this risk. As well as long series, reports of incidents can be helpful in improving patient safety. Thousands and thousands of safe blocks were performed before the pivotal report of Albright2about deaths related to intravascular injection of local anesthetics, and 4 more years elapsed before the test dose technique of Moore and Batra3was described. Ultrasound guidance is a recent step in regional anesthesia, and not all problems have yet been reported, discussed, and resolved. For example, the reports of inadvertent, painless, and uncomplicated intraneural injections during ultrasound-guided blocks have opened a new field of discussions in regional anesthesia.

However, we agree with most of the recommendations of Drs. Brull et al.  and Dr. Shankar because they are logical. According to their comments, we can list some propositions to try to improve patients’ safety during ultrasound-guided blocks.

First, as mentioned by Dr. Shankar, ultrasound is only a tool—a new tool for anesthesiologists. We have the obligation to learn and to train to use this new tool efficiently and safely.

Second, basic safety rules have to be respected, such as the respect of aseptic techniques in ultrasound-guided blocks, and even under ultrasound, patients should remain awake or only judiciously sedated.

Third, a preliminary large scout scan to visualize the nerves and neighboring structures, including a color flow study, is required. This is probably the better way to find the precise puncture site and to avoid unintentional vascular punctures.

Fourth, visualization of the needle tip is probably more important than visualization of the whole length of the needle. All needles are not created equal with regard to ultrasound,4and in our experience, we found that the tip of Tuohy-like needles is more often identified on the ultrasound monitor. Therefore, we prefer the use of such needles; however, this is not sufficient.

Fifth, VadeBoncouer et al.  5recently reported that an intravascular injection in the subclavian artery was detected in real-time by a grayish blush on the ultrasound monitor upon injection of the first milliliter of local anesthetic. Close observation of the monitor during injection is of course recommended, but the possibility of detecting an intravenous injection is not reported.

Sixth, visualization of the hypoechoic fluid bolus on the ultrasound monitor after 1 ml injectate is today the crucial safety point. If a real-time discernible extraneural hypoechoic image is not evident after injection of 1 (or 2) ml local anesthetic, that means that the needle tip is not located where we think it is, and injection should not be allowed. This is the new version of Moore and Batra’s test dose.

Finally, the relative merits of the in-plane versus  the out-plane approach are a matter of controversy between anesthesiologists, but as highlighted by Dr. Shankar, these two complicated blocks were performed by residents. That means that after the pioneer’s age of artists individually skilled in ultrasound-guided blocks, we have to concentrate a large part of our efforts in teaching our residents; this is not a matter of controversy.

*Hôpital de Bicêtre, Université Paris Sud, Le Kremlin Bicêtre, France.

Zetlaoui PJ, Labbe JP, Benhamou D: Ultrasound guidance for axillary plexus block does not prevent intravascular injection. Anesthesiology 2008; 108:761
Albright GA: Cardiac arrest following regional anesthesia with etidocaine or bupivacaine. Anesthesiology 1979; 51:285–7
Moore DC, Batra MS: The components of an effective test dose prior to epidural block. Anesthesiology 1981; 55:693–6
Maecken T, Zenz M, Grau T: Ultrasound characteristics of needles for regional anesthesia. Reg Anesth Pain Med 2007; 32:440–7
VadeBoncouer TR, Weinberg GL, Oswald S, Angelov F: Early detection of intravascular injection during ultrasound-guided supraclavicular brachial plexus block. Reg Anesth Pain Med 2008; 33:278–9