Julian Alvarez

Potential clinical utility of polymerase chain reaction in microbiological testing for sepsis

Objectives: To evaluate the potential improvement of antimicrobial treatment by utilizing a new multiplex polymerase chain reaction (PCR) assay that identifies sepsis-relevant microorganisms in blood. Design: Prospective, observational international multicentered trial. Setting: University hospitals in Germany (n = 2), Spain (n = 1), and the United States (n = 1), and one Italian tertiary general hospital. Patients: 436 sepsis patients with 467 episodes of antimicrobial treatment. Methods: Whole blood for PCR and blood culture (BC) analysis was sampled independently for each episode. The potential impact of reporting microorganisms by PCR on adequacy and timeliness of antimicrobial therapy was analyzed. The number of gainable days on early adequate antimicrobial treatment attributable to PCR findings was assessed. Measurements and Main Results: Sepsis criteria, days on antimicrobial therapy, antimicrobial substances administered, and microorganisms identified by PCR and BC susceptibility tests. Results: BC diagnosed 117 clinically relevant microorganisms; PCR identified 154. Ninety-nine episodes were BC positive (BC+); 131 episodes were PCR positive (PCR+). Overall, 127.8 days of clinically inadequate empirical antibiotic treatment in the 99 BC+ episodes were observed. Utilization of PCR-aided diagnostics calculates to a potential reduction of 106.5 clinically inadequate treatment days. The ratio of gainable early adequate treatment days to number of PCR tests done is 22.8 days/100 tests overall (confidence interval 15–31) and 36.4 days/100 tests in the intensive care and surgical ward populations (confidence interval 22–51). Conclusions: Rapid PCR identification of microorganisms may contribute to a reduction of early inadequate antibiotic treatment in sepsis.

Stimulating popliteal catheters for postoperative analgesia after hallux valgus repair.

Stimulating catheters have been recently introduced in clinical practice. We assessed the efficacy of stimulating and nonstimulating catheter placement for pain control and local anesthetic requirements after hallux valgus repair with continuous sciatic popliteal nerve block in this comparative, randomized, blinded-to-observer study of 48 patients. A stimulating catheter was placed in groups S-125 and S-0625. The same catheter was inserted without stimulation in group NS-125. An infusion of 0.125% levobupivacaine was given in groups S-125 and NS-125, whereas 0.0625% levobupivacaine was used in group S-0625. All patients received an infusion of the test drug at a basal rate of 3 mL/h, with the possibility of an additional bolus of 3 mL every hour. Verbal analog scale (VAS) scores for pain were assessed between 6–8 h and between 19–23 h postoperatively. Multiple attempts were required for catheter insertion in all patients in groups S-125 and S-0625. Lower median (range) VAS scores for pain (0–100 points) were found in group S-125 at 6–8 h postoperatively when compared with groups S-0625 and NS-125: 5 (0–17.5) versus 60 (15–80) and 70 (25–80), respectively (P < 0.05); and lower VAS scores for pain were also found in group S-125 at 19–23 h when compared with group NS-125: 0 (0–0) and 7.5 (0–10), respectively (P < 0.05). Fewer patients required IV opioid analgesia in group S-125 than in groups S-0625 and NS-125: 0, 5, and 7 patients, respectively (P < 0.05). We conclude that efficacy in pain control was increased with stimulating catheter placement.

Infraclavicular brachial plexus block effects on respiratory function and extent of the block

Background and Objectives. Axillary block is devoid of severe respiratory complications. However, incomplete anesthesia of the upper limb is the main disadvantage of the technique. Theoretically, the more proximal infraclavicular approach would produce a more extensive block without the risk of pneumothorax. However, neither its effects on respiratory function nor a detailed characterization of the extent of neural block has been assessed. The goal of this study was to evaluate the possible changes in respiratory function and also the extent of the block after infraclavicular block. Methods. We performed an infraclavicular block with a mixture of 40 mL 1.5% plain mepivacaine and 4 mL 8.4% sodium bicarbonate in 20 patients. Forced expiratory volumes were measured before and 15 minutes after the injection of local anesthetic, and sensory and motor block were evaluated at 10 and 20 minutes. Results. We did not find significant differences from baseline in the forced expiratory volumes in any of the patients. Axillary and musculocutaneous nerve distributions had the lowest rate of sensory block at 20 minutes. Conclusions. Infraclavicular block does not produce a reduction in respiratory function.

A comparison of single versus multiple injections on the extent of anesthesia with coracoid infraclavicular brachial plexus block.

Single-injection coracoid infraclavicular brachial plexus block produces inconsistent anesthesia of the upper limb. In this study, we sought to determine the number of injections needed to provide a reasonably complete anesthesia of the upper limb with this approach. Seventy-five patients were randomly assigned to receive a coracoid block guided by nerve stimulator with 42 mL of 1.5% mepivacaine with a single-injection (Group 1), dual-injection (Group 2), or triple-injection (Group 3) technique. No search for a specific motor response was performed in any group. Sensory and motor block was assessed 5 and 20 min after the end of the injection of local anesthetic. Significantly less complete anesthesia to pinprick in the distributions of the axillary, musculocutaneous, radial, ulnar, and medial cutaneous forearm nerves was found in Group 1 at 20 min. Significantly less complete paralysis for arm, wrist, and hand movements was found in Group 1 at 20 min. No significant difference was found between Groups 2 and 3. We conclude that dual and triple injection of local anesthetic guided by nerve stimulator increases the efficacy of coracoid block when compared with a single-injection technique.

Hemodynamic effects of levosimendan compared with dobutamine in patients with low cardiac output after cardiac surgery

INTRODUCTION AND OBJECTIVES Levosimendan is an inotropic agent that is effective in the treatment of heart failure. However, experience with levosimendan in patients with reduced cardiac output following cardiopulmonary bypass is limited. The objective of this study was to compare the short-term hemodynamic effects of levosimendan with those of dobutamine in managing low cardiac output after cardiac surgery. METHODS Forty-one patients who had low cardiac output after cardiopulmonary bypass were randomly assigned to dobutamine (n=20), 24-hour infusion of 7.5 microg/kg per min, or levosimendan (n=21), at a loading dose of 12 microg/kg followed by 24-hour infusion of 0.2 microg/kg per min. The following parameters were determined during a 48-hour observation period: arterial, central venous, pulmonary arterial and pulmonary capillary wedge pressure, cardiac index, heart rate, stroke volume, and systemic and pulmonary vascular resistance. RESULTS Although both dobutamine and levosimendan improved the cardiac index, the increase was significantly greater with levosimendan (2.4 [0.2] l/min per m2 vs 2.9 [0.3] l/min per m2, respectively, at 24 h; P<.05). Moreover, levosimendan significantly reduced systemic and pulmonary vascular resistance, and significantly decreased systemic arterial, pulmonary arterial, pulmonary capillary wedge, and central venous pressure. CONCLUSIONS Both dobutamine and levosimendan are effective in managing postoperative low cardiac output. However, levosimendan induces non-specific systemic, venous and pulmonary vasodilation which can result in hypotension as a adverse event. In these patients, it is advisable to omit or reduce the loading dose.

What is the minimum effective volume of local anesthetic required for sciatic nerve blockade? A prospective, randomized comparison between a popliteal and a subgluteal approach

For sciatic nerve blockade, no study has defined the optimal volume of local anesthetic required to block the nerve. The current, prospective, randomized investigation was designed to find a minimum volume of 1.5% mepivacaine required to block the sciatic nerve using the subgluteal and posterior popliteal approaches. A total of 56 patients undergoing foot surgery were randomly assigned to receive sciatic nerve block by means of a posterior subgluteal (group subgluteal, n = 28) or a posterior popliteal (group popliteal, n = 28) approaches. All blocks were performed with the use a nerve stimulator (stimulating frequency, 2 Hz, intensity 1.5-0.5 mA) and a perineural stimulating catheter. In all patients, plantar flexion of the foot was elicited at <0.5 mA, to maintain consistency among groups. The volume of local anesthetic used in each patient was based on the modified Dixon’s up-and-down method. Complete anesthesia was defined as complete loss of pinprick sensation in the sciatic nerve distribution with concomitant inability to perform plantar or dorsal flexion of the foot 20 min after injection. The mean volume of local anesthetic required to block the sciatic nerve was 12 ± 3 mL in the subgluteal group and 20 ± 3 mL in the popliteal group (P < 0.05). The ED95 for adequate block of the sciatic nerve was 17 mL in the subgluteal group and 30 mL in the popliteal group. The authors conclude that a larger volume of local anesthetic is necessary to block the sciatic nerve at a more distal site (popliteal approach) as compared with a more proximal level (subgluteal approach).

Restricted infraclavicular distribution of the local anesthetic solution after infraclavicular brachial plexus block

Background and Objectives The distribution of local anesthetic after different approaches for brachial plexus anesthesia could be responsible for the varying rates of side effects, such as phrenic block, hoarseness, and Horner’s syndrome associated with each approach. We compared the distribution of local anesthetic within the neurovascular space in infraclavicular block with that of interscalene and supraclavicular block. Methods In a prospective analysis using fluoroscopy, we studied the distribution of a solution of local anesthetic containing radiologic contrast medium in 18 patients. Six patients received an interscalene block, another 6 patients received a perpendicular supraclavicular block, and another 6 patients, a perpendicular coracoid block. Results Distribution of the anesthetic solution in the interscalene and supraclavicular groups extended to both supraclavicular and infraclavicular spaces in all patients. This distribution was significantly different (P < .05) compared with that of the infraclavicular group. In this group, the solution remained below the clavicle in every patient. Conclusions Spread of the local anesthetic from the infraclavicular space after infraclavicular coracoid block appears to be limited to below the level of the clavicle. Conversely, local anesthetic solution passes below the clavicle in all patients given interscalene or supraclavicular blocks. Reg Anesth Pain Med 2003;28:33-36.

Median versus musculocutaneous nerve response with single-injection infraclavicular coracoid block

Background and Objectives Local anesthetic injection after elicitation of a distal motor response with a nerve stimulator is believed to produce a more clinically efficient infraclavicular coracoid block than after elicitation of a proximal motor response. The aim of this study was to investigate whether elicitation of a median or of a musculocutaneous-type nerve response influenced the quality of anesthesia. Methods Randomized, prospective, single-blind study. One hundred thirty patients received a coracoid block with 40 mL plain mepivacaine 1.5% after stimulation of median nerve fibers (group 1) or musculocutaneous nerve fibers (group 2). Patients were assessed for sensory and motor block at 5 and 20 minutes. Results Significantly higher rates of complete anesthesia at 20 minutes were found in the cutaneous distributions of the radial and ulnar nerves in group 1. Significantly higher rates of complete paralysis were found for elbow extension, wrist flexion, and finger and thumb movements in group 1 at 20 minutes. Differences in the extent of anesthesia and paralysis were more remarkable at 5 minutes than at 20 minutes. Conclusions Elicitation of a median nerve response improved the efficacy of infraclavicular coracoid block when compared with a musculocutaneous nerve response. Complete paralysis and complete anesthesia of the upper limb were low in both groups.

Minimally Invasive Surgical Implantation of Left Ventricular Epicardial Leads for Ventricular Resynchronization Using Video-Assisted Thoracoscopy

BACKGROUND AND OBJECTIVES Cardiac resynchronization via left ventricular or biventricular pacing is an option for selected patients with ventricular systolic dysfunction and widened QRS complex. Stimulation through a coronary vein is the technique of choice for left ventricular pacing, but this approach results in a failure rate of approximately 8%. We describe our initial experience with minimally invasive surgical implantation of left ventricular epicardial leads using video-assisted thoracoscopy. PATIENTS AND METHOD A total of 14 patients with congestive heart failure, NYHA functional class 3.2 (0.6) and mean ejection fraction 22.9 (6.8)% were included in this study. Left bundle branch block, QRS complex >140 ms and abnormal septal motion were observed in all cases. Epicardial leads were implanted on the left ventricular free wall under general anesthesia using video-assisted thoracoscopic surgery. RESULTS Lead implantation was successful in 13 patients. Conversion to a small thoracotomy was necessary in one patient. All patients were extubated in the operating room. None of the patients died during their hospital stay. Follow-up showed reversal of ventricular asynchrony and significant improvement in ejection fraction and functional class. CONCLUSIONS Minimally invasive surgery for ventricular resynchronization using video-assisted thoracoscopy in selected patients is a safe procedure that makes it possible to choose the best site for lead implantation and provides adequate short- and medium-term stimulation.

Is ultrasound guidance superior to conventional nerve stimulation for coracoid infraclavicular brachial plexus block

Background and Objectives: In different peripheral nerve blocks, it has been speculated that needle guidance by ultrasound improves onset time and success rate compared with the more frequently used nerve stimulation-guided technique. In the present study, we tested the hypothesis that ultrasound guidance improves onset time of coracoid infraclavicular brachial plexus block (IBPB) when compared with a nerve stimulation-guided technique. Methods: Seventy patients scheduled for hand or forearm surgery were randomly assigned to receive coracoid IBPB using either ultrasound guidance (group U, n = 35), or nerve stimulation (group S, n = 35). Patients were assessed for sensory and motor block every 5 mins after injection of local anesthetic. Onset time, the primary end point, was defined as the time required for complete sensory and motor block. Time required to perform the block, success rate, and time to resolution of motor blockade were also recorded (secondary end points). Results: Onset of complete sensory and motor blockade was similar in the 2 groups (17 mins [8 mins] in group U and 19 mins [8 mins] in group S; P = 0.321). Time required to perform the block was shorter in group U (3 mins [1 min]) as compared with group S (6 mins [2 mins]; P < 0.0001). No differences were observed in success rate (89% in group U and 91% in group S; P = 0.881) and time to resolution of motor blockade (237 mins [45 mins] in group U and 247 mins [57 mins] in group S; P = 0.418). Conclusions: The present investigation demonstrates that ultrasound guidance and nerve stimulation provide similar onset time, success rate, and duration of motor blockade for coracoid IBPB; however, ultrasound guidance reduces the time required to perform the block.