Giorgio Torri

A Double-Blind Comparison of Ropivacaine, Bupivacaine, and Mepivacaine During Sciatic and Femoral Nerve Blockade

No study has evaluated the efficacy of ropivacaine in peripheral nerve block of the lower extremity.The purpose of this prospective, randomized, double-blind study was to compare ropivacaine, bupivacaine, and mepivacaine during combined sciatic-femoral nerve block. Forty-five ASA physical status I or II patients scheduled for elective hallux valgus repair with thigh tourniquet were randomized to receive combined sciatic-femoral block with 0.75% ropivacaine (ROPI, n = 15), 0.5% bupivacaine (BUPI, n = 15), and 2% mepivacaine (MEPI, n = 15). Time required for onset of sensory and motor block on the operated limb (readiness for surgery) and resolution of motor block, as well as onset of postsurgical pain and time of first analgesic requirement, were recorded. The three groups were similar with regard to demographic variables, duration of surgery, and measured visual analog pain scores. Onset of sensory and motor blockade was similar in Groups ROPI and MEPI and significantly shorter than in Group BUPI (P = 0.002 and P = 0.001, respectively). Resolution of motor block occurred later in Groups ROPI and BUPI than in Group MEPI (P = 0.005 and P = 0.0001, respectively). Duration of postoperative analgesia was significantly longer in Groups ROPI (670 +/- 227 min) and BUPI (880 +/- 312 min) compared with Group MEPI (251 +/- 47 min) (P = 0.0001), with a significant decrease in postoperative pain medication requirements (P < 0.05). We conclude that for sciatic-femoral nerve block, 0.75% ropivacaine has an onset similar to that of 2% mepivacaine and a duration of postoperative analgesia between that of 0.5% bupivacaine and 2% mepivacaine. Implications: Quick onset of block with prolonged postoperative analgesia is an important goal in peripheral nerve blockade. We evaluated the clinical properties of 0.5% bupivacaine, 2% mepivacaine, and 0.75% ropivacaine for sciatic-femoral nerve block and demonstrated that ropivacaine has an onset similar to that of mepivacaine but allows for postoperative analgesia between that of bupivacaine and mepivacaine. (Anesth Analg 1998;87:597-600)

Activation of coagulation and fibrinolysis during coronary surgery: on-pump versus off-pump techniques.

Background The authors studied the changes in selected hemostatic variables in patients undergoing coronary surgery with on-pump coronary artery bypass grafting (CABG) or off-pump coronary artery bypass surgery (OPCAB) techniques. Methods Platelet counts and plasma concentrations of antithrombin, fibrinogen, D dimer, &agr;2 antiplasmin, and plasminogen were measured preoperatively, 5 min after administration of heparin, 10 min after arrival in the intensive care unit, and 24 h after surgery in patients scheduled to undergo OPCAB (n = 15) or CABG (n = 15). To correct for dilution, hemostatic variables and platelet counts were adjusted for the changes in immunoglobulin G plasma concentrations and hematocrit, respectively. Results Adjusting for dilution, antithrombin and fibrinogen concentrations decreased to a similar extent in patients undergoing OPCAB or CABG (pooled means and 95% confidence limits of the mean: 95.5% of baseline, 93–98%, P = 0.002, and 91.7% of baseline, 88–95%, P = 0.0001), respectively, whereas &agr;2-antiplasmin concentrations were unchanged. Only CABG was associated with a reduction in platelet counts (76% of baseline, 66–85%, P = 0.0001), plasminogen concentrations (96% of baseline, 91–99%, P = 0.011), and increased D-dimer formation (476%, 309–741%, P = 0.004). Twenty-four hours after surgery, platelet counts were still lower in patients undergoing CABG (P = 0.049), but all the investigated variables adjusted for dilution were similar in the two groups. Conclusions Coronary surgery causes a net consumption of antithrombin and fibrinogen. A transient decrease in platelet counts, with plasminogen activation and increased D-dimer formation, however, is only observed with CABG. Twenty-four hours after surgery, the hemostatic profiles of patients in both groups are similar.

Small-dose clonidine prolongs postoperative analgesia after sciatic-femoral nerve block with 0.75% ropivacaine for foot surgery.

To evaluate the effects of adding small-dose clonidine to 0.75% ropivacaine during peripheral nerve blocks, 30 ASA physical status I and II patients undergoing hallux valgus repair under combined sciatic-femoral nerve block were randomly allocated in a double-blinded fashion to receive block placement with 30 mL of either 0.75% ropivacaine alone (group Ropivacaine, n = 15) or 0.75% ropivacaine plus 1 &mgr;g/kg clonidine (group Ropivacaine-Clonidine, n = 15). Hemodynamic variables, oxygen saturation, and levels of sedation, as well as the time required to achieve surgical block and time to first analgesic request, were recorded by a blinded observer. Time to surgical blockade required 10 min in both groups. Patients in the Ropivacaine-Clonidine group were more sedated than patients in the Ropivacaine group only 10 min after block placement. No differences in oxygen saturation and hemodynamic variables, degree of pain measured at first analgesic request, and consumption of postoperative analgesics were observed between the two groups. The mean time from block placement to first request for pain medication was shorter in group Ropivacaine (13.7 h; 25th–75th percentiles: 11.8–14.5 h) than in group Ropivacaine-Clonidine (16.8 h; 25th–75th percentiles: 13.5–17.8 h) (P = 0.038). We conclude that adding 1 &mgr;g/kg clonidine to 0.75% ropivacaine provided a 3-h delay in first request for pain medication after hallux valgus repair, with no clinically relevant side effects. Implications This prospective, randomized, double-blinded study demonstrated that, when providing combined sciatic-femoral nerve block for hallux valgus repair, the addition of 1 &mgr;g/kg clonidine to 0.75% ropivacaine prolongs the duration of postoperative analgesia by 3 h, with only a slight and short-lived increase in the degree of sedation and no hemodynamic adverse effects.

Unilateral bupivacaine spinal anesthesia for outpatient knee arthroscopy

Purpose: To compare unilateral and conventional bilateral bupivacaine spinal block in outpatients undergoing knee arthroscopy.Methods: One hundred healthy, premedicated patients randomly received conventional bilateral (n=50) or unilateral (n=50) spinal anesthesia with 8 mg hyperbaric bupivacaine 0.5%. A lateral decubitus position after spinal injection was maintained in unilateral group for 15 min. Times from spinal injection to readiness for surgery, block resolution, and home discharge were recorded.Results: Three patients in each group were excluded due to failed block. Readiness for surgery required 13 min (5 – 25 min) with bilateral and 16 min (15 – 30) with unilateral spinal block (P=0.0005). Sensory and motor blocks on the operated limb were T9 (T12 – T2) with a Bromage score 0/1/2/3: 0/2/0/45 in the unilateral group and T7 (T12 – T1) with Bromage score 0/1/2/3: 4/1/6/36 with bilateral block (P=0.026 andP=0.016, respectively). Vasopressor was required only in five bilateral patients (P=0.02). Two segment regression of sensory level and home discharge required 81±25 min and 281±83 min with bilateral block, and 99±28 min and 264±95 min with unilateral block (P=0.002 andP=0.90, respectively).Conclusion: Seeking unilateral distribution of spinal anesthesia provided more profound and longer lasting block in the operated limb, less cardiovascular effects, and similar home discharge compared with bilateral spinal anesthesia, with only a slight delay in preparation time.RésuméObjectif: Comparer le bloc rachidien unilatéral au bloc bilatéral traditionnel chez des patients ambulatoires qui subissent une arthroscopie du genou.Méthode: Cent patients sains ont reçu une prémédication et, de façon aléatoire, une rachianesthésie bilatérale traditionnelle (n=50) ou unilatérale (n=50) avec 8 mg de bupivacaïne hyperbare à 0,5 %. Après l’injection, les patients du groupe unilatéral ont été maintenus en décubitus latéral pendant 15 min. On a enregistré: le temps écoulé entre l’injection et le début de l’opération, le temps écoulé entre l’injection et le début de l’opération, le temps nécessaire à la résolution du bloc et le moment de la sortie du service.Résultats: Trois patients ont été exclus dans chaque groupe à cause de l’échec du bloc. II a fallu 13 min (5 – 25 min) de préparation à l’opération avec le bloc bilatéral et 16 min (15 – 30) avec le bloc unilatéral (P=0,0005). Les blocs sensitif et moteur sur le membre opéré ont été de T9 (T12 – T2) avec des scores de 0/1/2/3: 0/2/0/45 à l’échelle de Bromage dans le groupe unilatéral et de T7 (T12 – T1) et des scores de Bromage de 0/1/2/3: 4/1/6/36 avec le bloc bilatéral (P=0,026 et P=0,016, respectivement). Des vasopressures ont été nécessaires chez cinq patients seulement du groupe bilatéral (P=0,02). Le temps nécessaire à la régression de deux segments du bloc sensitif et au congé a été de 81±25 min et de 281±83 min avec le bloc bilatéral, et de 99±28 min et 264 ±95 min avec le bloc unilatéral (P=0,002 et P=0,90, respectivement).Conclusion: La rachianesthésie unilatérale, comparée à la rachianesthésie bilatérale, produit un bloc plus profond et plus long dans le membre opéré, moins d’effets cardiovasculaires, un séjour hospitalier de durée similaire et seulement un léger délai de préparation à l’intervention.

Frequency of hypotension during conventional or asymmetric hyperbaric spinal block

BACKGROUND AND OBJECTIVES The purpose of this randomized, double-blind study was to evaluate if use of an asymmetric spinal block affects the incidence of hypotension during spinal anesthesia. METHODS With Ethical Committee approval and patient consent, 120 patients undergoing lower limb surgery were placed in the lateral position with the side to be operated on dependent, and received 8 mg 0.5% hyperbaric bupivacaine through a 25-gauge Whitacre spinal needle. Patients were randomized to one of two groups: (a) local anesthetic was injected with barbotage through a cranially directed needle orifice, then patients were immediately turned to supine (conventional, n = 60); (b) local anesthetic was injected without barbotage with the needle orifice turned toward the dependent side, then the lateral position was maintained for 15 minutes (unilateral, n = 60). A blind observer recorded noninvasive hemodynamic variables, as well as loss of cold and pinprick sensation and motor block on both sides. RESULTS In the unilateral group, 31 patients (52%) showed a unilateral loss of cold sensation and 48 patients (80%) had no motor block on the nondependent side for the duration of the study, whereas all conventional patients had bilateral distribution of spinal block (P < .0001). The onset time and two-segment regression of sensory block on the dependent side were more rapid in the conventional group (18 +/- 7 minutes and 60 +/- 18 minutes) than in the unilateral group (22 +/- 8 minutes and 67 +/- 19 minutes) (P < .05 and P < .05, respectively). The incidence of hypotension (SAP decrease >30% from baseline) was higher in the conventional (22.4%) than unilateral group (5%) (P < .01). The maximum percentage changes from baseline values of systolic arterial blood pressure and heart rate were greater in conventional group (-28% +/- 16% and -19% +/- 10%) than in unilateral group (-8% +/- 16% and -12% +/- 18%) (P < .0001 and P < .01, respectively). CONCLUSIONS Achieving an asymmetric distribution of spinal block by injecting a small dose of 0.5% hyperbaric bupivacaine through a Whitacre spinal needle into patients placed in the lateral position for 15 min reduces the incidence of hypotension during spinal anesthesia.

Regional anaesthesia for outpatient knee arthroscopy: a randomized clinical comparison of two different anaesthetic techniques

Background: The purpose of this prospective, randomized study was to evaluate the time required to perform anaesthesia, achieve surgical block and fulfil standardized discharge criteria in outpatients receiving knee arthroscopy with either spinal anaesthesia or combined sciatic‐femoral nerve block.

Minimum local anesthetic volume blocking the femoral nerve in 50% of cases: a double-blinded comparison between 0.5% ropivacaine and 0.5% bupivacaine.

Recent studies demonstrated that ropivacaine was nearly 40% less potent than bupivacaine in the first stage of labor, but contrasting results have been reported. We, therefore, conducted a prospective, randomized, double-blinded study to determine the effects of the ropivacaine/bupivacaine potency ratio on the minimum volume of local anesthetic required to produce effective block of the femoral nerve in 50% of patients. Fifty adults premedicated with IV midazolam, 0.05 mg/kg, undergoing elective knee arthroscopy received femoral nerve blocks with a multiple-injection technique with a nerve stimulator (contractions of vastus medialis, vastus intermedius, and vastus lateralis were elicited with a 0.5-mA stimulating current). Patients randomly received either 0.5% ropivacaine (n = 25) or 0.5% bupivacaine (n = 25). The anesthetic volume was decided according to Dixon’s up-and-down method, starting from 12 mL and being equally divided among the three elicited twitches. Successful nerve block was loss of pinprick sensation in the femoral nerve distribution with concomitant block of the quadriceps muscle within 20 min after injection, as assessed by a blinded observer. Positive or negative responses determined a 3-mL decrease or increase for the next patient, respectively. According to the up-and-down sequences, the minimum local anesthetic volume providing successful nerve block in 50% of cases was 14 ± 2 mL in the ropivacaine group (95% CI: 12–16 mL) and 15 ± 2 mL (95% CI: 13–17 mL) in the bupivacaine group (P = 0.155). We conclude that the volume of 0.5% ropivacaine required to produce effective block of the femoral nerve in 50% of patients is similar to that required when using 0.5% bupivacaine. IMPLICATIONS Considering the risk for drug-related systemic toxicity, the equipotency ratio between ropivacaine and bupivacaine is crucial for daily practice. Despite the 40% reduction in the analgesic potency of ropivacaine reported during epidural analgesia for labor pain, results of this prospective, randomized, double-blinded study demonstrated that the same volume of 0.5% ropivacaine or 0.5% bupivacaine is required to produce an effective block of the femoral nerve in 50% of cases.

Perioperative care for the older outpatient undergoing ambulatory surgery.

As the number of ambulatory surgery procedures continues to grow in an aging global society, the implementation of evidence-based perioperative care programs for the elderly will assume increased importance. Given the recent advances in anesthesia, surgery, and monitoring technology, the ambulatory setting offers potential advantages for elderly patients undergoing elective surgery. In this review article we summarize the physiologic and pharmacologic effects of aging and their influence on anesthetic drugs, the important considerations in the preoperative evaluation of elderly outpatients with coexisting diseases, the advantages and disadvantages of different anesthetic techniques on a procedural-specific basis, and offer recommendations regarding the management of common postoperative side effects (including delirium and cognitive dysfunction, fatigue, dizziness, pain, and gastrointestinal dysfunction) after ambulatory surgery. We conclude with a discussion of future challenges related to the growth of ambulatory surgery practice in this segment of our surgical population. When information specifically for the elderly population was not available in the peer-reviewed literature, we drew from relevant information in other ambulatory surgery populations.

Intraoperative epidural anesthesia and postoperative analgesia with levobupivacaine for major orthopedic surgery: a double-blind, randomized comparison of racemic bupivacaine and ropivacaine ☆

STUDY OBJECTIVE To compare the onset time and duration of epidural anesthesia, and the quality of postoperative analgesia produced by levobupivacaine, racemic bupivacaine, and ropivacaine. DESIGN Prospective, randomized, double-blinded study. SETTING Inpatient anesthesia at a University Hospital. PATIENTS 45 ASA physical status I, II, and III patients, undergoing elective total hip replacement. INTERVENTIONS After standard intravenous midazolam premedication and infusion of 500 mL of Ringers acetate solution, patients were randomly allocated to receive epidural block with 0.5% levobupivacaine (n = 15), 0.5% bupivacaine (n = 15), or 0.5% ropivacaine (n = 15). Postoperatively, after pinprick sensation recovered at T(t), a patient-controlled epidural infusion was provided with 0.125% levobupivacaine, 0.125% bupivacaine, or 0.2% ropivacaine, respectively (baseline infusion rate 5 mL/hr; incremental bolus 2 mL, lockout time: 20 min). Intravenous ketoprofen was also available for rescue analgesia if required. MEASUREMENTS AND MAIN RESULTS The onset time of sensory block was 31 +/- 16 minutes with levobupivacaine, 25 +/- 19 minutes with bupivacaine, and 30 +/- 24 minutes with ropivacaine (p = 0.98), after a median (range) volume of 15 (10-18) mL in Group Levobupivacaine, 14 (10-18) mL in Group Bupivacaine, and 15 (10-18) mL in Group Ropivacaine (p = 0.85). Six patients in the ropivacaine group (40%) showed an intraoperative Bromage score <2 as compared with only three patients of Group Levobupivacaine (20%) and no patient of Group Bupivacaine (p = 0.02). Recovery of pinprick sensation at T(t) occurred after 214 +/- 61 minutes with levobupivacaine, 213 +/- 53 minutes with bupivacaine, and 233 +/- 34 minutes with ropivacaine (p = 0.26). A similar degree of pain relief was observed in the three groups without differences in local anesthetic consumption and need for rescue analgesia. Motor blockade progressively resolved without differences among the three groups. CONCLUSIONS Levobupivacaine 0.5% produces an epidural block of similar onset, quality, and duration as the one produced by the same volume of 0.5% bupivacaine, with a motor block deeper than that produced by 0.5% ropivacaine. When prolonging the block for the first 12 hours after surgery with a patient-controlled epidural infusion, 0.125% levobupivacaine provides adequate pain relief after major orthopedic surgery, with similar recovery of motor function as compared with 0.125% bupivacaine and 0.2% ropivacaine.

Clinical assessment of target-controlled infusion of propofol during monitored anesthesia care

PurposeTo determine the plasma concentrations of propofol required to achieve different levels of sedation during monitored anesthesia care.MethodsSixty ASA 1-11, 18–65 yr-old patients, received a target-controlled continuousiv infusion of propofol. The target plasma concentration of propofol (Cpt) was initially set at 0.4 μ·g·ml−1. Two minutes after calculated equilibrium between plasma and effect-site concentrations, the Cpt of propofol was increased by 0.2 μg·ml−1 steps until the patient showed no reaction to squeezing the trapezius. The level of sedation was assessed immediately before each increase in propofol Cpt using the Observer’s Assessment of Alertness/Sedation (OAA/S) scale.ResultsThe Cpt of propofol required to induce lethargic response to name was 1.3 μg·ml−1 (5° and 95° percentiles: 1.0 – 1.8 μg·ml−1), to obtain response after loud and repeated calling name was 1.7 μg·ml−1 (1.2 – 2.2 μg·ml−1), to obtain response after prodding or shaking was 2.0 μg·ml−1(1.6 – 2.6 μg·ml−1), to obtain response after squeezing the trapezius was 2.4 μg·ml−1 (1.8 – 3.0 μg·ml−1). Patients showed no response after squeezing the trapezius at 2.8 μg·ml−1 (2.0 – 3.6 μg·ml−1). Correlation between Cpt propofol and sedation scores were r =0.76, P< 0.0001.ConclusionsTarget-controlled infusion of propofol provided easy and safe management of intraoperative sedation, allowing fast and predictable deepening in the level of sedation, while minimizing systemic side effects of intravenous sedation due to the minimal risk of overdosing the drug.RésuméObjectifDéterminer les concentrations plasmatiques de propofol nécessaire pour fournir différents niveaux de sédation monitorés.MéthodeSoixante patients ASA 1–11 de 18–65 ans ont reçu une perfusion continue de propofoliv à cible contrôlée. La concentration plasmatique ciblée de propofol (Cpc) était d’abord de 0,4 μg·ml−1. Deux minutes après avoir atteint l’équilibre entre la concentration plasmatique et celle du site d’effet, la Cpc de propofol a été augmenté par paliers de 0,2μg·ml−1 jusqu’à ce que le patient ne réagisse plus à une pression sur le trapèze. Le niveau de sédation a été évalué immédiatement avant chaque augmentation de la Cpc de propofol à l’aide de l’échelle de cotation de la vigilance par l’observateur/sédation (CVO/S).RésultatsLa Cpc de propofol nécessaire pour induire une réaction léthargique du patient à l’appel de son nom était de 1,3 μg·ml−1(5° et 95° percentiles: 1,0 – 1,8 μg · ml−1, pour obtenir une réaction après l’appel du nom répété et à voix forte était de 1,7 μg·ml−1 (1,2–2,2 μg·ml−1), pour réagir à une poussée ou une secousse, 2.0 μg·ml−1 (1.6 -2.6μg·ml−1), et pour réagir à une pression sur le trapèze, 2,4μg·ml−1 (1,8 – 3,0μg·ml−1). Les patients n’ont pas réagi à la pression sur le trapèze avec une concentration de 2,8 μg·ml−1 (2,0 – 3,6μg·ml−1). La corrélation entre la Cpc de propofol et les niveaux de sédation a été aussi observée, r = 0,76, P < 0,0001.ConclusionLa perfusion de propofol à cible contrôlée fournit une ligne de conduite facile et sûre pour la sédation peropératoire, permettant l’approfondissement rapide et prévisible de la sédation tout en réduisant les effets secondaires généraux de la sédation intraveineuse causés par le risque minimal d’une surdose de médicament.