Is the musculocutaneous nerve really in the coracobrachialis muscle when performing an axillary block? An ultrasound study.

BACKGROUND: In reference textbooks describing axillary block, the ulnar, radial, and median nerves are located in a common sheath surrounding the axillary artery. In contrast, the musculocutaneous nerve is described as lying outside this sheath in the coracobrachialis muscle. In a recent case report of ultrasound-guided axillary block, the musculocutaneous nerve was joined to the median nerve outside this muscle. Our study evaluated the prevalence of atypical musculocutaneous nerve localizations during axillary block. METHODS: All patients undergoing ultrasound-guided axillary block were included from December 2006 to December 2008. Before needle insertion, musculocutaneous, median, ulnar, and radial nerves were localized using ultrasound. Nerve stimulation confirmed atypical nerve localization. After injection of local anesthetics, musculocutaneous and median nerve anatomical relationships were observed. RESULTS: The musculocutaneous nerve was outside the coracobrachialis muscle in 83 of the 387 analyzed blocks (22%). It was near the axillary artery in 22 cases (6%). The musculocutaneous and median nerves appeared as a common neural structure in 61 cases (16%). After local anesthetic injection, a common trunk persisted in 16 of 61 cases (26%), musculocutaneous and median nerves separated in 37 cases (61%), and 2 roots of the median nerve appeared (with or without a separated musculocutaneous nerve) in 6 cases (10%). Two cases (3%) remained undefined. Ulnar nerve location of the 83 patients with atypical musculocutaneous nerve position differed from the ones with a classical musculocutaneous nerve localization. CONCLUSIONS: During axillary block, the musculocutaneous nerve is outside the coracobrachialis muscle in 1 of 5 patients. This atypical location should be considered during performance of axillary blockade to avoid repeated IM puncture.

Elastomeric pump reliability in postoperative regional anesthesia: a survey of 430 consecutive devices.

BACKGROUND: Postoperative analgesia via continuous perineural infusion of local anesthetics compares favorably with systemic analgesia. Elastomeric pumps increase patient satisfaction compared with electronic models. In in vitro investigations, infusions remained within 15% of their designated set rates. We assessed in vivo the infusion rate of elastomeric pumps in regional analgesia after orthopedic surgery. METHODS: All consecutive elastomeric pumps were retrospectively studied during a 10-mo period. Perineural catheters were inserted preoperatively and connected postoperatively to elastomeric pumps filled with ropivacaine 0.2%. Before infusion, elastomeric pumps and ropivacaine were stored at room temperature. Two models of pumps were randomly used: Infusor LV5 (Baxter, France) or Easypump (Braun, Germany), both set at 5 mL/h. Nurses weighed the devices at the bedside using a portable electronic scale several times a day until catheter removal. Weights over time allowed accurate deflation profile assessment and flow rate calculation. An unchanged weight over time indicated either an obstructed catheter or an ineffective device. RESULTS: After connection to the catheter, 88 devices did not deflate (80 Easypump of 300 and 8 Infusor of 130, P < 0.0001). One Easypump was impossible to deflate, even after disconnection from its catheter. In two cases, catheters were obstructed. In 21 cases, catheters were removed 11 to 72 h later without being tested for patency. In 24 cases, pumps correctly deflated after catheters were injected without difficulty with a local anesthetic bolus. The remaining 40 devices spontaneously started to deflate 6 to 43 h after their connection. These 88 elastomeric pumps were associated with higher maximal visual analog scale scores during the first postoperative night than devices showing immediate deflation after connection (34 +/- 21 mm vs 26 +/- 19 mm, P = 0.006). Flow rates were calculated over a mean period of 54 +/- 18 h (Easypump) and 49 +/- 19 h (Infusor). The flow rates differed from those set by manufacturers (5 mL/h +/- 15%) in 47% of Easypump and in 34% of Infusor devices (P = 0.01). CONCLUSIONS: In vivo reliability of elastomeric pumps is different than in vitro. In the event of early insufficient postoperative perineural analgesia, an absence of deflation of the elastomeric pump must be considered. We recommend weighing these devices every 3 h during the first 24 h of infusion.

The reduction of preoperative autologous blood donation for primary total hip or knee arthroplasty: the effect on subsequent transfusion rates.

UNLABELLED: We conducted this quality assurance observational study to examine the effects of a change in policy regarding preoperative autologous blood donation (PABD) and indications for perioperative blood transfusion in patients undergoing primary total hip or knee arthroplasty. Two successive time periods, each including 182 successive patients treated by the same medical team and with standardized anesthesia, were compared. The first study had the following standard transfusion policy: 3 U of PABD collected (n = 119) and liberal autologous transfusion (AT). The second study introduced a specific indication for PABD, on the basis of estimated red blood cell reserve and a life expectancy of more than 10 years; 2 U of PABD was collected (n = 81), and criteria were identical for AT and allogeneic transfusion. We mainly compared the incidence of AT; allogeneic and overall transfusions; the inclusion, admission, and discharge hematocrit values; and the wastage of PABD units. This novel policy increased the number of untransfused patients by a factor of 10 (5.5% vs 56.6%) (P < 0.0001), decreased the number of PABD patients by 30% with a 2.4-fold reduction in AT (30% vs 80%) (P < 0.0001), and did not change allogeneic requirements (13% vs 15%). Although fewer autologous units were collected (172 vs 426), the wastage was higher in Study 2 (46% vs 12%) (P < 0.0001). We conclude that incorporation of patients' individual factors improves the efficiency of transfusion for total hip and total knee arthroplasty surgeries. IMPLICATIONS: We compared two transfusion policies for primary total hip or knee arthroplasties: first, a standard preoperative autologous donation with a liberal autologous transfusion policy; and second, a more restrictive indication for autologous donation that was based on patients' individual factors, with identical criteria for autologous and allogeneic transfusion. We found that this change of policy reduced autologous donation and transfusion with no increase in allogeneic transfusion.