Effects of Ropivacaine Concentration on Analgesia After Ultrasound-Guided Serratus Anterior Plane Block: A Randomized Double-Blind Trial.

PURPOSE: Serratus anterior plane (SAP) block is effective for analgesia after breast surgery. Whether a higher local anesthetic concentration prolongs sensory block duration and improves postoperative analgesia remains unclear. The aim of this study was to compare the analgesic effects of SAP block with different concentrations of ropivacaine. PATIENTS AND METHODS: Sixty patients scheduled for breast surgery were enrolled in this randomized double-blind trial. SAP block was induced with 20 mL of 0.375%, 0.5%, or 0.75% ropivacaine in Group R0.375, Group R0.5, and Group R0.75, respectively. The primary endpoint was the area under the curve (AUC) of numerical rating scale (NRS) pain intensity scores at rest over time. The secondary endpoints were AUC of NRS pain intensity scores on movement over time, active sensory block duration, tramadol consumption, and the elapsed time between completion of surgery and the first administration of rescue analgesia. RESULTS: The AUC of NRS pain intensity scores at rest of Group R0.375 was significantly higher than that of Groups R0.5 and R0.75 (P=0.025, and P=0.001). The AUC of NRS pain intensity scores on movement of Group R0.375 was also significantly higher than that of Groups R0.5 and R0.75 (both P<0.001). At higher ropivacaine concentrations, the duration of SAP sensory block increased (P<0.001). Tramadol consumption and the elapsed time between completion of surgery and the first administration of rescue analgesia were similar in the three groups (P>0.05). CONCLUSION: A comparison of 0.5% and 0.75% ropivacaine showed no significant difference in postoperative analgesia, but both were superior to 0.375% ropivacaine, although higher ropivacaine concentration lengthened the duration of SAP block. Therefore, SAP block with 0.5% ropivacaine is recommended for postoperative analgesia in breast surgery.

Supplement of levosimendan to epinephrine improves initial resuscitation outcomes from asphyxial cardiac arrest.

BACKGROUND: Levosimendan exerted favorable effects on the initial outcome in the treatment of ventricular fibrillation cardiac arrest. This study investigated the efficacy of levosimendan in the treatment of asphyxia-induced cardiac arrest in rats. METHODS: Animals underwent asphyxial cardiac arrest/cardiopulmonary resuscitation, randomized to three treatment groups: epinephrine (10 µg/kg) supplemented with levosimendan (bolus 12 µg/kg and infusion for 1 h, EL group); epinephrine only (10 µg/kg, E group), or levosimendan only (bolus 12 µg/kg and infusion for 1 h, L group). The resuscitation success rate, wet-to-dry ratio of lung, and rate of alveolar and blood gas analysis were recorded. RESULTS: 10 rats in the EL group, 8 in the E group, and 2 in the L group showed an initial return of spontaneous circulation (P < 0.001); among them, 10, 4, and 2 rats survived at the end of a 60-min observation period from each group, respectively (P = 0.001). The coronary perfusion pressure in the EL group was higher than that of either the E or L group (P < 0.05). The lung wet-to-dry weight ratio and rate of damaged alveoli were lower in the EL group than the E group (P < 0.05). CONCLUSIONS: In the early stage of resuscitation for asphyxia-induced cardiac arrest in rats, levosimendan supplemented with epinephrine can significantly increase coronary perfusion pressure, reduce lung injury, and ultimately enhance the survival rate.

Epinephrine reversed high-concentration bupivacaine-induced inhibition of calcium channels and transient outward potassium current channels, but not on sodium channel in ventricular myocytes of rats.

BACKGROUND: Epinephrine is a first-line drug for cardiopulmonary resuscitation, but its efficacy in the treatment of bupivacaine-induced cardiac toxicity is still in question. We hypothesized that epinephrine can reverse cardiac inhibition of bupivacaine by modulating ion flows through the ventricular myocyte membrane channels of rats. The aim of this study was to observe and report the effects of epinephrine on high-concentration bupivacaine-induced inhibition of sodium (INa), L-type calcium (ICa-L), and transient outward potassium (Ito) currents in the ventricular myocytes of rats. METHODS: The ventricular myocytes were isolated from Sprague-Dawley rats (250-300 g) by acute enzymatic dissociation. The whole-cell patch clamp technique was used to record the ion channel currents in single ventricular myocytes both before and after administration of medications. RESULT: Administration of bupivacaine 100 µmol/L significantly reduced INa, (P < 0.05). However, administration of bupivacaine 100 µmol/L in conjunction with epinephrine 0.15 µg/ml had no effect in restoring INa to its previous state. Similarly, a sharp decline of ICa-L and Ito was observed after administration of bupivacaine 100 µmol/L (P < 0.05). In contrast to INa, ICa-L and Ito were significantly improved after the administration of the aforementioned combination of bupivacaine and epinephrine (P < 0.05). CONCLUSION: Epinephrine can reverse high-concentration bupivacaine induced inhibition of ICa-L and Ito, but not INa. Thus, epinephrine's effectiveness in reversal of bupivacaine-induced cardiac toxicity secondary to sodium channel inhibition may be limited.

Epinephrine administration in lipid-based resuscitation in a rat model of bupivacaine-induced cardiac arrest: optimal timing.

BACKGROUND AND OBJECTIVES: The medical community commonly uses lipid emulsion combined with epinephrine in local anesthetic-induced cardiac arrest, but the optimal timing of epinephrine administration relative to lipid emulsion is currently unknown and needs to be determined. METHODS: Thirty adult male Sprague-Dawley rats were subjected to bupivacaine-induced asystole and were then randomly divided into 3 groups. The temporal administration of epinephrine varied in each group: (1) immediately after the completion of the initial bolus of lipid emulsion therapy (postILE0); (2) immediately after cardiac arrest before the initial bolus of lipid emulsion (preILE); or (3) 1 minute after the completion of the initial bolus of lipid emulsion (postILE1). External chest compression was administered until the return of spontaneous circulation or the end of a 20-minute resuscitation period. RESULTS: The postILE0, preILE, and postILE1 groups displayed different survival rates (100%, 30%, and 40%; P = 0.003). After return of spontaneous circulation, the rate-pressure product of the postILE0 group was higher than that of the postILE1 group (P < 0.001). Wet-to-dry lung weight ratio of preILE and postILE1 groups was higher than that of the postILE0 group (P < 0.05). The rate of damaged alveoli of the postILE0 group was lower than those of the preILE (P = 0.001) and postILE1 (P < 0.001) groups. Concentrations of bupivacaine in the cardiac tissues of the postILE0 group were lower than that of the postILE1 group (P = 0.01). CONCLUSIONS: In the rat model of bupivacaine-induced cardiac arrest, the optimal timing for the administration of epinephrine to produce best outcomes of successful cardiopulmonary resuscitation is immediately after the completion of the lipid emulsion bolus. This optimal timing/therapeutic window is of paramount importance.

Measurement and reconstruction of three-dimensional configurations of specimen with tiny scattering based on digital holographic tomography.

Based on digital holographic tomography, a method for measuring the three-dimensional (3D) configuration of a transparent object with tiny scattering is proposed. By rotating a Michelson interferometer around static specimen, a series of the phase change distributions of reconstructed object beams carrying the structure information of specimen can be obtained at complete angle range, and the rotation of specimen can be avoided. In addition, phase multiplication of the interferometer can be used to improve the measurement sensitivity of specimen with tiny scattering. And then, as an example, the tomographic maps and 3D configurations of an ultrasonic standing wave field are measured according to the filtered-backprojection algorithm. The comparison between experimental and simulation results is provided to certify the feasibility and reliability of the proposed method.