Hervé Bouaziz

Major complications of regional anesthesia in France: The SOS Regional Anesthesia Hotline Service.

Background Several previous surveys have estimated the rate of major complications that occur after regional anesthesia. However, because of the increase in the use of regional anesthesia in recent years and because of the introduction of new techniques, reappraisal of the incidence and the characteristics of major complications is useful. Methods All French anesthesiologists were invited to participate in this 10-month prospective survey based on (1) voluntary reporting of major complications related to regional anesthesia occurring during the study period using a telephone hotline service available 24 h a day and managed by three experts, and (2) voluntary reporting of the number and type of regional anesthesia procedures performed using pocket booklets. The service was free of charge for participants. Results The participants (n = 487) reported 56 major complications in 158,083 regional anesthesia procedures performed (3.5/10,000). Four deaths were reported. Cardiac arrest occurred after spinal anesthesia (n = 10; 2.7/10,000) and posterior lumbar plexus block (n = 1; 80/10,000). Systemic local anesthetic toxicity consisted of seizures only, without cardiac toxicity. Lidocaine spinal anesthesia was associated with more neurologic complications than bupivacaine spinal anesthesia (14.4/10,000 vs. 2.2/10,000). Most neurologic complications were transient. Among 12 that occurred after peripheral nerve blocks, 9 occurred in patients in whom a nerve stimulator had been used. Conclusion This prospective survey based on a free hotline permanent telephone service allowed us to estimate the incidence of major complications related to regional anesthesia and to provide a detailed analysis of these complications.

Continuous peripheral nerve blocks in hospital wards after orthopedic surgery: a multicenter prospective analysis of the quality of postoperative analgesia and complications in 1,416 patients.

Background:Continuous peripheral nerve block (CPNB) is the technique of choice for postoperative analgesia after painful orthopedic surgery. However, the incidence of neurologic and infectious adverse events in the postoperative period are not well established. This issue was the aim of the study. Methods:Patients scheduled to undergo orthopedic surgery performed with a CPNB were prospectively included during 1 yr in a multicenter study. Efficacy of postoperative analgesia, bacteriologic cultures of the catheter, and acute neurologic and infectious adverse events were evaluated after surgery in 1,416 patients at arrival in the postanesthesia care unit, at hour 1, and every 24 h up to day 5. Risk factors for adverse events were determined using logistic regression. Results:The median duration of CPNB was 56 h. Both general anesthesia and CPNB were performed in 73.6% of the patients. Postoperative analgesia was effective in 96.3%, but an increase in pain scores was noted at hour 24 (P = 0.01). Hypoesthesia or numbness occurred in 3% and 2.2%, respectively, and paresthesia occurred in 1.5%. Three neural lesions (0.21%) were noted after continuous femoral nerve block. Two of these patients were anesthetized during block procedure. Nerve damage completely resolved 36 h to 10 weeks later. Cultures from 28.7% of the catheters were positive. Three percent of patients had local inflammatory signs. The bacterial species most frequently found were coagulase-negative staphylococcus (61%) and gram-negative bacillus (21.6%). A Staphylococcus aureus psoas abscess (0.07%) was reported in one diabetic woman. Independent risk factors for paresthesia/dysesthesia were postoperative monitoring in intensive care, age less than 40 yr, and use of bupivacaine. Risk factors for local inflammation/infection were postoperative monitoring in intensive care, catheter duration greater than 48 h, male sex, and absence of antibiotic prophylaxis. Conclusion:CPNB is an effective technique for postoperative analgesia. Minor incidents and bacterial colonization of catheters are frequent, with no adverse clinical consequences in the large majority of cases. Major neurologic and infectious adverse events are rare.

Angiotensin converting enzyme inhibition prevents the increase in aortic collagen in rats.

Four groups of 4-week-old spontaneously hypertensive rats were treated during 4 months with the angiotensin converting enzyme inhibitor quinapril at 1 mg/kg per day (Q1) or 10 mg/kg per day (Q10), hydralazine at 15 mg/kg per day (H), or placebo (P). In the first set of experiments, blood pressure was measured in conscious rats, and plasma and aortic angiotensin converting enzyme activities were evaluated. In the second set of experiments, histomorphometric parameters of the thoracic aorta were evaluated. Mean blood pressure was lower in the Q10 and H groups (136 +/- 16 and 149 +/- 11 mm Hg) compared with the P group (190 +/- 23 mm Hg) (P < .01). The Q1 group showed mean blood pressure values (171 +/- 15 mm Hg) lower than the P group (P < .05) but significantly higher than the Q10 and H groups (P < .01 and P < .05, respectively). Aortic medial cross-sectional area was significantly lower in the H and Q10 groups (455 +/- 61 and 487 +/- 57 x 10(3) microns 2) than in the P group (636 +/- 72 x 10(3) microns 2) (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

An Evaluation of the Cutaneous Distribution After Obturator Nerve Block

In 1973, Winnie et al. introduced the inguinal paravascular three-in-one block, which allegedly provides anesthesia of three nerves—the femoral, lateral cutaneous femoral, and obturator nerves—with a single injection. This concept was undisputed until the success of the obturator nerve block was reassessed by using evidence of adductor weakness rather than cutaneous sensory blockade, the latter being variable in its distribution and often absent. We performed this study, therefore, to evaluate the area of sensory loss produced by direct injection of local anesthetic around the obturator nerve. A selective obturator nerve block with 7 mL of 0.75% ropivacaine was performed in 30 patients scheduled for knee surgery. Sensory deficit and adductor strength were evaluated for 30 min by using sensory tests (cold and light-touch perception) and the pressure generated by the patient’s squeezing a blood pressure cuff placed between the knees. Subsequently, a three-in-one block was performed, and the sensory deficit was reassessed. The obturator nerve block was successful in 100% of cases. The strength of adductors decreased by 77% ± 17% (mean ± sd). In 17 patients (57%), there was no cutaneous contribution of the obturator nerve. The remaining 7 patients (23%) had an area of hypoesthesia (cold sensation was blunt but still present) on the superior part of the popliteal fossa, and the other 6 (20%) had sensory deficit located at the medial aspect of the thigh. The three-in-one block resulted in blockade of the lateral aspect of the thigh in 87% of cases, whereas the anteromedial aspect was always anesthetized. By use of magnetic resonance imaging in eight volunteers, we demonstrated that the obturator nerve has already divided into its two branches at the site of local anesthetic injection. However, the injection of blue dye after having simulated the technique in five cadavers showed that the fluid regularly spread to both branches. We conclude that after three-in-one block, a femoral nerve block may have been assessed as an obturator nerve block in 100% of cases when testing the cutaneous distribution of the obturator nerve on the medial aspect of the thigh.

The lateral approach to the sciatic nerve at the popliteal fossa: one or two injections?

UNLABELLED It has not been proven whether one or multiple nerve stimulations and injections provide a higher rate of complete sensory block in both major sciatic nerve sensory distributions below the knee when a popliteal sciatic nerve block is performed using the lateral approach. This prospective, randomized, single-blinded study compared the success rate of the sciatic nerve block using this approach when one or both major components of this nerve (i.e., tibial nerve and common peroneal nerves) are stimulated in 50 patients undergoing foot or ankle surgery. In Group 1 STIM, 24 patients received a single injection of 20 mL of a mixture of 2% lidocaine and 0.5% bupivacaine with 1:200,000 epinephrine after foot inversion had been elicited. In Group 2 STIM (n = 26), 10 mL of the same solution was injected after stimulation of each sciatic nerve component. For patients with complete sensory motor block, there was no difference in onset between groups. However, Group 2 STIM showed a greater success rate compared with the Group 1 STIM (2 STIM: 88% vs 1 STIM :54%; P = 0.007). When two stimulations were used, the onset time of anesthesia in the cutaneous distribution of the common peroneal nerves was shorter than in the tibial nerve (17.5 vs 30 min; P < 0.0001). We conclude that a two-stimulation technique provides a better success rate than a single-injection technique when a popliteal sciatic nerve block is performed using the lateral approach with 20 mL of local anesthetic. IMPLICATIONS A better success rate is achieved with a double stimulation technique than with a single injection for the sciatic nerve block via the lateral approach at the popliteal fossa when 20 mL of local anesthetics is used.

Reduction of Blood Loss and Transfusion Requirement by Aprotinin in Posterior Lumbar Spine Fusion

UNLABELLED Aprotinin reduces blood loss in many orthopedic procedures. In posterior lumbar spine fusion, blood loss results primarily from large vein bleeding and also occurs after the wound is closed. Seventy-two patients undergoing posterior lumbar spine fusion were randomly assigned to large-dose aprotinin therapy or placebo. All patients donated three units of packed red blood cells (RBCs) preoperatively. Postoperative blood loss was harvested from the surgical wound in patients undergoing two- and/or three-level fusion for reinfusion. The target hematocrit for RBC transfusion was 26% if tolerated. Total (intraoperative and 24 h postoperative) blood loss, transfusion requirements, and percentage of transfused patients per treatment group were significantly smaller in the aprotinin group than in the placebo group (1935 +/- 873 vs 2809 +/- 973 mL per patient [P = 0.007]; 42 vs 95 packed RBCs per group [P = 0.001]; 40% vs 81% per group [P = 0.02]). Hematological assessments showed an identically significant (a) intraoperative increase in both thrombin-antithrombin III complexes (TAT) and in activated factor XII (XIIa) and (b) decrease in activated factor VII (VIIa), indicating a similar significant effect on coagulation in patients of both groups (P = 0.9 for intergroup comparisons of postoperative VIIa, XIIa, and TAT). Intraoperative activation of fibrinolysis was significantly less pronounced in the aprotinin group than in the placebo group (P < 0.0001 for intergroup comparison of postoperative D-dimer levels). No adverse drug effects (circulatory disturbances, deep venous thrombosis, alteration of serum creatinine) were detected. Although administered intraoperatively, aprotinin treatment dramatically reduced intraoperative and 24-h postoperative blood loss and autologous transfusion requirements but did not change homologous transfusion in posterior lumbar spine fusion. IMPLICATIONS In our study, aprotinin therapy significantly decreased autologous, but not homologous, transfusion requirements in posterior lumbar spine fusion.

Comparative ventricular electrophysiologic effect of racemic bupivacaine, levobupivacaine, and ropivacaine on the isolated rabbit heart

BACKGROUND Numerous local anesthetics have an asymmetric tetrahedron carbon, which confers stereoselective differences between the isomers. The authors attempted to quantify the depressant effect of racemic bupivacaine, levobupivacaine, and ropivacaine on myocardial ventricular conduction and on myocardial contractility. METHODS The authors studied the pharmacokinetics (outflow concentration) and pharmacodynamics (QRS widening) of the three drugs infused in an isolated rabbit heart preparation. All data were fitted simultaneously with use of mixed-effect modeling, thus allowing precise statistical comparison between the three drug parameters. The rate dependence of QRS widening was fitted separately. RESULTS Racemic bupivacaine, levobupivacaine, and ropivacaine induced a calculated maximum increase in QRS duration in the ratio 1:0.4:0.3. Css50, the dose which caused half the maximum increase in QRS duration at steady state, was similar for all three drugs (22 micrometer free concentration). A rate dependence of QRS widening was observed, which was in the ratio 1:0.5:0.25 for racemic bupivacaine, levobupivacaine, and ropivacaine, respectively. CONCLUSIONS In the isolated rabbit heart, racemic bupivacaine, levobupivacaine, and ropivacaine induce an increase in QRS duration in the respective ratio of 1:0.4:0.3, which was rate dependent in approximately the same ratio.

Infraclavicular block with lateral approach and nerve stimulation: Extent of anesthesia and adverse effects

Background and Objectives The infraclavicular approach to the brachial plexus is little used despite theoretical advantages of the technique. Using a vertical paracoracoid approach, we assessed the extent of the sensory block and the incidence of adverse effects. Methods After obtaining informed consent, 100 patients undergoing surgical procedures distal to the elbow were evaluated. The block was performed using a peripheral nerve stimulator. The puncture site was located in the infraclavicular fossa; the direction of the insulated needle was perpendicular to the skin. Motor response was sought in the hand or wrist at ≤ 0.6 mA. A total of 40 mL of 1.5% mepivacaine was administered as a single injection. The sensory block was evaluated every 5 minutes for 30 minutes before surgery in the cutaneous distribution of terminal branches of the brachial plexus. Results When one considers the cutaneous distributions of the median, ulnar, radial, and musculocutaneous nerves, the success rate was 89% for surgery without need for additional peripheral nerve blocks or general anesthesia. In contrast, cutaneous areas innervated by the axillary and medial cutaneous nerves were rarely anesthetized. We were unable to demonstrate a correlation between the intensity of the stimulation and the success of the block. On the other hand, a correlation was found between tourniquet sensation and the absence of anesthesia of the medial cutaneous nerve of the arm. Local anesthetic toxicity, Horner’s syndrome, and vascular puncture were respectively observed in 1%, 4%, and 5% of cases. The depth of the needle introduction was correlated with the body mass index (P < .001; r = .63). Conclusion Single injection infraclavicular block, using a vertical paracoracoid approach, appears suitable for surgery distal to the elbow. Selective anesthesia of the medial cutaneous nerve is useful in improving tolerance of the tourniquet.

Sedation with sufentanil and midazolam decreases pain in patients undergoing upper limb surgery under multiple nerve block.

Multiple nerve blocks may be painful and a source of discomfort. We assessed the efficacy of sufentanil 5 &mgr;g combined with midazolam 1 mg in decreasing pain in outpatients after a midhumeral multiple nerve stimulation technique. Visual analog scores for pain were significantly lower in those patients who received sedation before the block, both at the time of block performance (14 ± 1 vs 27 ± 2 mm, P < 0.0001) and at discharge (11 ± 1 vs 24 ± 2 mm, P < 0.0001). We conclude that the association of sufentanil and midazolam produced minimal sedation while significantly reducing pain experienced by patients undergoing multiple nerve stimulation. Implications In a prospective trial of 168 patients, the use of sedation significantly reduced pain during a multiple-nerve stimulation block. The combination of sufentanil and midazolam produced either minimal or no sedation and allowed the performance of the block in awake and cooperative patients. Light sedation may improve patient acceptance of this technique

Carotid Artery Mechanical Properties of Dahl Salt-Sensitive Rats

We evaluated the mechanical properties of the carotid artery in anesthetized Dahl rats with or without long-term treatment with the diuretic compound indapamide. The mechanical properties of the carotid artery were evaluated by establishing pressure-volume curves in situ in vivo before and after total relaxation of arterial smooth muscle by potassium cyanide. Dahl salt-sensitive and salt-resistant rats were fed either a low (0.4%) or high (7%) NaCl diet for 5 weeks. In each group, half the rats received for the same period of time oral treatment with indapamide (3 mg/kg per day). Blood pressure, heart rate, and pressure-volume curves were studied at the end of the 5-week period. In untreated Dahl salt-sensitive rats, the pressure-volume curve of the carotid artery was shifted to the right compared with that in untreated Dahl salt-resistant rats. The finding was observed even after potassium cyanide and regardless of the NaCl diet (P < .01 between Dahl salt-sensitive and -resistant rats). Indapamide was able to prevent the development of hypertension in Dahl salt-sensitive rats receiving a high NaCl diet (185 +/- 7 versus 146 +/- 8 mm Hg in untreated and treated Dahl salt-sensitive rats with a high NaCl diet, P < .0005). In the other groups, indapamide had no effect on blood pressure. Indapamide treatment increased carotid arterial static compliance in Dahl salt-sensitive rats with a high or low NaCl diet and to a lesser extent in Dahl salt-resistant rats. The increase was observed even after total relaxation of carotid arterial smooth muscle by potassium cyanide.(ABSTRACT TRUNCATED AT 250 WORDS)