Carlo Missant

I.V. and perineural dexamethasone are equivalent in increasing the analgesic duration of a single-shot interscalene block with ropivacaine for shoulder surgery: a prospective, randomized, placebo-controlled study

BACKGROUND Interscalene brachial plexus block (ISB) provides excellent, but time-limited analgesia. Dexamethasone added to local anaesthetics prolongs the duration of a single-shot ISB. However, systemic glucocorticoids also improve postoperative analgesia. The hypothesis was tested that perineural and i.v. dexamethasone would have an equivalent effect on prolonging analgesic duration of an ISB. METHODS We performed a prospective, double blind, randomized, placebo-controlled study. Patients presenting for arthroscopic shoulder surgery with an ISB were randomized into three groups: ropivacaine 0.5% (R); ropivacaine 0.5% and dexamethasone 10 mg (RD); and ropivacaine 0.5% with i.v. dexamethasone 10 mg (RDiv). The primary outcome was the duration of analgesia, defined as the time between performance of the block and the first analgesic request. Standard hypothesis tests (t-test, Mann-Whitney U-test) were used to compare treatment groups. The primary outcome was analysed by Kaplan-Meier survival analysis with a log-rank test and Coxs proportional hazards regression. RESULTS One hundred and fifty patients were included after obtaining ethical committee approval and patient informed consent. The median time of a sensory block was equivalent for perineural and i.v. dexamethasone: 1405 min (IQR 1015-1710) and 1275 min (IQR 1095-2035) for RD and RDiv, respectively. There was a significant difference between the ropivacaine group: 757 min (IQR 635-910) and the dexamethasone groups (P<0.0001). CONCLUSIONS I.V. dexamethasone is equivalent to perineural dexamethasone in prolonging the analgesic duration of a single-shot ISB with ropivacaine. As dexamethasone is not licensed for perineural use, clinicians should consider i.v. administration of dexamethasone to achieve an increased duration of ISB.

Levosimendan improves right ventriculovascular coupling in a porcine model of right ventricular dysfunction

Objective:Experimental data suggest that levosimendan has pulmonary vasodilatory properties which, in combination with its positive inotropic effects, would render it particularly attractive for the treatment of right ventricular dysfunction. To test this hypothesis, we developed an experimental model of right ventricular failure and analyzed the effects of levosimendan on ventriculovascular coupling between the right ventricle and pulmonary artery (PA). Design:Prospective, randomized, placebo-controlled animal study. Setting:University hospital laboratory. Subjects:Fourteen pigs (mean weight 36 ± 1 kg). Interventions:Pigs were instrumented with biventricular conductance catheters, a PA and right coronary artery flow probe, and a high-fidelity pulmonary pressure catheter. Right ventricular dysfunction was induced by repetitive episodes of ischemia/reperfusion in the presence of temporary PA constriction. Pigs were randomly assigned to receive levosimendan (120 &mgr;g·kg−1·min−1 for 10 mins followed by continuous infusion of 60 &mgr;g·kg−1·min−1 for 45 mins) or the placebo (control). Measurements and Main Results:Induction of right ventricular dysfunction resulted in a 42% decrease in contractility (reduction in slope of preload recruitable stroke work [Mw] from 2.5 ± 0.4 to 1.8 ± 0.5 mW·sec·mL−1; p = .02) and a 60% increase in right ventricular afterload (effective pulmonary arterial elastance [PA-Ea] from 0.6 ± 0.1 to 1.0 ± 0.3 mm Hg·mL−1; p < .01). Right ventriculovascular coupling, as assessed by the quotient of right ventricular end-systolic elastance (Emax) over PA-Ea, decreased from 1.23 ± 0.38 to 0.64 ± 0.21 (p = .03). Treatment with levosimendan improved right ventricular contractility (Mw from 1.9 ± 0.4 to 2.9 ± 0.5 mW·sec·mL−1; p < .01), lowered right ventricular afterload (PA-Ea from 1.1 ± 0.3 to 0.8 ± 0.3 mm Hg·mL−1; p = .02), and restored right ventriculovascular coupling to normal values (Emax/PA-Ea = 1.54 ± 0.51). Levosimendan also significantly increased coronary blood flow and left ventricular contractility (Mw from 7.2 ± 3.3 to 9.5 ± 2.9 mW·sec·mL−1; p = .01) but did not affect biventricular diastolic function. Conclusions:In an experimental model of acute right ventricular dysfunction, levosimendan improved global hemodynamics and optimized right ventriculovascular coupling via a moderate increase in right ventricular contractility and a mild reduction of right ventricular afterload.

Combined spinal-epidural anesthesia for cesarean delivery: dose-dependent effects of hyperbaric bupivacaine on maternal hemodynamics.

Hypotension remains an important side effect of spinal anesthesia for cesarean delivery. There is limited evidence that reducing the spinal dose has a favorable effect on maternal hemodynamic stability. We designed the present randomized trial to test the hypothesis that reducing the spinal dose of local anesthetics results in equally effective anesthesia and less maternal hypotension. Fifty term pregnant patients were randomly assigned to two study groups. In the HIGH-group combined spinal-epidural anesthesia was performed using 9.5 mg hyperbaric bupivacaine combined with 2.5 &mgr;g sufentanil. In the LOW-group combined spinal-epidural anesthesia was performed using 6.5 mg hyperbaric bupivacaine combined with 2.5 &mgr;g sufentanil. Demographic data, obstetrical data, visual analog scale score for pain, number of medical interventions for pain, maternal hemodynamics, and neonatal outcome were recorded. Patients in the HIGH-group experienced more pronounced and longer hypotensive periods as compared with the LOW-group. The mean lowest recorded systolic blood pressure was higher in the LOW-group (102 ± 16 versus 88 ± 16 in the HIGH-group; P < 0.05). More patients in the HIGH-group experienced hypotension compared with the LOW-group (68% versus 16%; P < 0.05). In the HIGH-group 15 patients required pharmacological treatment for hypotension compared with 5 in the LOW-group. Duration of effective anesthesia (block to cold sensation above or at T3) was longer in the HIGH-group as compared with the LOW-group (95 ± 25 versus 68 ± 18 min, respectively, P < 0.05). We conclude that small-dose spinal anesthesia (6.5 mg hyperbaric bupivacaine combined with sufentanil) better preserves maternal hemodynamic stability with equally effective anesthesia that is of shorter duration.

Remifentanil for fetal immobilization and maternal sedation during fetoscopic surgery: a randomized, double-blind comparison with diazepam.

Obstetric endoscopy procedures are routinely performed at our institution to treat selected complications of monochorionic twin gestation. We perform these procedures under combined spinal epidural anesthesia plus maternal sedation. In the absence of general anesthesia, fetal immobilization is not achieved. We hypothesized that remifentanil would induce adequate maternal sedation and provide fetal immobilization, which is equal or superior to that induced by diazepam. Fifty-four second trimester pregnant women were included in this randomized, double-blind trial. After combined spinal epidural anesthesia, maternal sedation was initiated using either incremental doses of diazepam or a continuous infusion of remifentanil. Maternal sedation, hemodynamics, side effects, and fetal hemodynamics and immobilization were evaluated before, during, and for 60 min after surgery. Remifentanil produced adequate maternal sedation with mild but clinically irrelevant respiratory depression (respiratory rate 13 ± 4 breaths/min and Pco2 38.6 ± 4 mm Hg at 40 min of surgery), whereas diazepam resulted in a more pronounced maternal sedation but no respiratory depression (respiratory rate 18 ± 3 breaths/min and Pco2 32.7 ± 3 mm Hg at 40 min of surgery). Compared with diazepam, fetal immobilization with remifentanil occurred faster and was more pronounced, resulting in improved surgical conditions; the number of gross body and limb movements was 12 ± 4 (diazepam) versus 2 ± 1 (remifentanil) at 40 min of surgery. Because of this, the mean (range) duration of surgery was significantly shorter in the remifentanil-treated patients, 60 (54–71) min versus 80 (60–90) min in the diazepam group. We conclude that remifentanil produces improved fetal immobilization with good maternal sedation and only minimal effects on maternal respiration.

Load-sensitivity of regional tissue deformation in the right ventricle: isovolumic versus ejection-phase indices of contractility

Objective: Doppler myocardial imaging is increasingly being used to evaluate regional and global cardiac function. Quantitative measurements of tissue deformation obtained during ejection as well as isovolumic contraction have been proposed as new indices of contractility; however, their load-sensitivity remains a matter of controversy. Maximum strain rate (SRmax) and isovolumic strain acceleration (ISAmax) were compared with regard to sensitivity for inotropic state, heart rate and loading conditions in the right ventricle (RV), using pressure-volume analysis as the reference method. Design: Prospective animal study. Setting: University hospital laboratory. Interventions: RV contractility was measured at baseline, after inotropic modulation with esmolol and dobutamine, at different atrial pacing rates and during controlled alterations of RV preload and afterload. Main outcome measures: RV contractility was assessed with the slope (Mw) of preload recruitable stroke work and longitudinal SRmax and ISAmax. Results: SRmax and ISAmax reflected the drug-induced changes in contractility, while only ISAmax increased with higher pacing rates. Acute lowering of RV preload did not affect either of the indices studied. In contrast, an increase in RV afterload consistently decreased SRmax (from 1.05 (SD 0.41) to 0.73 (SD 0.26) s-1,p = 0.03) but had variable effects on ISAmax and Mw. However, a significant correlation was found between proportional changes in ISAmax and Mw during high-afterload conditions (r2 = 0.89, p = 0.005). Conclusions: Both SRmax and ISAmax reflected changes in RV contractility. ISAmax was less sensitive to changes in RV afterload than SRmax and may therefore be a more robust index of global RV contractility.

Thoracic epidural anesthesia impairs the hemodynamic response to acute pulmonary hypertension by deteriorating right ventricular-pulmonary arterial coupling.

Objective: Thoracic epidural anesthesia is increasingly used in critically ill patients. This analgesic technique was shown to decrease left ventricular contractility, but effects on right ventricular function have not been reported. A deterioration of right ventricular performance may be clinically relevant for patients with acute pulmonary hypertension, in which right ventricular function is an important determinant of outcome. In the present study, we tested the hypothesis that thoracic epidural anesthesia decreases right ventricular contractility and limits its capacity to tolerate pulmonary hypertension. Design: Prospective, placebo‐controlled study using an established model of acute pulmonary hypertension. Setting: University hospital laboratory. Subjects: A total of 14 pigs (mean weight, 35 ± 2 kg). Interventions: After instrumentation with an epidural catheter, biventricular conductance catheters, a pulmonary flow probe, and a high‐fidelity pulmonary pressure catheter, seven pigs received thoracic epidural anesthesia and seven pigs served as control. Hemodynamic measurements were performed in baseline conditions and after induction of pulmonary hypertension via hypoxic pulmonary vasoconstriction (Fio2 of 0.15). Measurements and Main Results: Ventricular contractility was assessed using load‐ and heart rate–independent variables. Right ventricular afterload was characterized with instantaneous pressure–flow measurements. In baseline conditions, thoracic epidural anesthesia decreased left but not right ventricular contractility. In untreated animals, pulmonary hypertension was associated with an increase in right ventricular contractility and cardiac output. Pretreatment with thoracic epidural anesthesia completely abolished the positive inotropic response to acute pulmonary hypertension. As a result, ventriculo‐vascular coupling between the right ventricle and pulmonary–arterial system deteriorated, and cardiac output was significantly lower in animals with thoracic epidural anesthesia than in untreated controls during hypoxia‐induced pulmonary hypertension. Conclusions: Thoracic epidural anesthesia inhibits the native positive inotropic response of the right ventricle to increased afterload and deteriorates the hemodynamic effects of acute pulmonary hypertension.

Intrathecal clonidine prolongs labour analgesia but worsens fetal outcome: a pilot study

PurposeIntrathecal clonidine prolongs total duration of spinal bupivacaine analgesia. However, there are contradictory reports about its effect on maternal blood pressure and only limited data are available on fetal and neonatal outcome. In this study we evaluated the efficacy of spinal clonidine combined with ropivacaine and sufentanil and its effects on maternal and fetal outcome.MethodsFifty patients requesting combined spinal epidural analgesia for labour pain relief were randomly assigned to receive intrathecal ropivacaine 3 mg, sufentanil 1.5 μg with or without clonidine 30 μg. Onset time and duration of analgesia, visual analogue scores for pain, blood pressure, ephedrine requirements, heart rate, incidence of nausea, pruritus and motor blockade, umbilical artery pH, fetal heart rate abnormalities and Apgar scores were noted and analyzed.ResultsPatients receiving spinal clonidine had significantly longer lasting analgesia compared to patients treated without clonidine (122 ± 56 min vs 90 ± 36 min, P < 0.05). Clonidine-treated patients experienced a more pronounced decrease in mean arterial pressure as compared to patients treated without clonidine (25 ± 10% vs 15 ± 12%, P < 0.05). The groups also differed in ephedrine requirement (4.91 mg vs 0.75 mg, P < 0.05), number of new onset fetal heart rate abnormalities (28% vs 0%, P < 0.05) and umbilical artery pH (7.219 ± 0.096 vs 7.289 ± 0.085, P < 0.05).ConclusionIntrathecal clonidine prolongs spinal analgesia with ropivacaine and sufentanil at the expense of maternal hypotension, worse fetal well being and worse neonatal umbilical artery pH. We do not recommend routine administration of spinal clonidine 30μg to sufentanil and ropivacaine for labour pain relief.RésuméObjectifLa clonidine intrathécale prolonge la durée totale de la rachianalgésie avec bupivacaïne. Cependant, les résultats sont contradictoires au sujet de ses effets sur la tension artérielle maternelle et il n’y a que des données limitées sur l’évolution fœtale et néonatale. Nous voulions évaluer l’efficacité d’une rachianalgésie avec donidine, ajoutée à la ropivacaïne et au sufentanil, et ses effets sur l’évolution maternelle et fœtale.MéthodeCinquante patientes désirant une analgésie rachidienne et péridurale combinée pendant le travail ont été réparties au hasard et ont reçu 3 mg de ropivacaïne intrathécaie, 1,5 μg de sufentanil avec ou sans 30 μg de clonidine. Le délai d’installation et la durée de l’analgésie, les scores de douleur selon une échelle visuelle analogique, la tension artérielle, les besoins d’éphédrine, la fréquence cardiaque, l’incidence de nausées, le prurit et le blocage moteur, le pH de l’artère ombilicale, les anomalies de la fréquence cardiaque fœtale et l’indice d’Apgar ont été notés et analysés.RésultatsLanalgésie avec clonidine rachidienne a duré significativement plus longtemps comparée à l’analgésie sans clonidine (122 ± 56 min vs 90 ± 36 min, P < 0,05). Les patientes traitées à la clonidine, comparées aux patientes sans clonidine, ont présenté une baisse plus prononcée de la tension artérielle moyenne (25 ± 10 % vs 15 ± 12 %, P < 0,05). Des différences intergroupes ont aussi été notées quant aux besoins d’éphédrine (4,91 mg vs 0,75 mg, P < 0,05), au nombre d’anomalies de la fréquence cardiaque fœtale nouvellement installées (28 % vs 0%, P < 0,05) et au pH de l’artère ombilicale (7,219 ±0,096 vs 7,289 ± 0,085, P < 0,05).ConclusionLa clonidine intrathécaie prolonge la rachianalgésie avec ropivacaïne et sufentanil aux dépens de l’hypotension maternelle, d’une dégradation du bienêtre fœtal et d’une modification du pH néonatal de l’artère ombilicale. L’administration rachidienne régulière de 30 μg de donidine n’est pas recommandée comme supplément au sufentanil et à la ropivacaïne pendant le travail obstétrical.

Accuracy of cardiac output measurements with pulse contour analysis (PulseCO) and Doppler echocardiography during off-pump coronary artery bypass grafting.

Background and objective: During off‐pump coronary bypass grafting, surgical manipulation and dislocation of the heart may cause cardiovascular instability. Monitoring of cardiac output facilitates intraoperative haemodynamic management but pulmonary artery catheters are often considered too invasive. Pulse contour analysis and transoesophageal echocardiography could serve as alternatives, but there is controversy about their accuracies. We validated pulse contour analysis using a standard radial arterial catheter (PulseCOTM) and aortic Doppler flowmetry with transoesophageal echocardiography in patients undergoing off‐pump coronary bypass surgery. Pulmonary arterial thermodilution served as the reference technique. Methods: In 20 patients undergoing off‐pump coronary bypass, cardiac output was measured with bolus thermodilution (COTD), pulse contour analysis (COPC), and transoesophageal echocardiography (COecho) at fixed time intervals during the procedure. Data were compared using linear regression and Bland‐Altman analysis. At the end of the procedure, dobutamine was infused at a rate of 2.5 &mgr;g kg−1 min−1 in six patients to study the agreement between methods in quantifying changes in cardiac output. Results: Comparison between COPC and COTD showed a bias ± limits of agreement of −0.03 ± 1.30 L min−1 (mean error 29%). Doppler echocardiography was not always feasible when the heart was displaced from the oesophagus and had lower accuracy: bias ± limits of agreement vs. COTD was 0.45 ± 1.93 (mean error 43%). Increases in cardiac output induced by dobutamine were well quantified both by pulse contour analysis (COPC = 0.76 × COTD + 0.58; r2 = 0.65) and Doppler, although the latter tended to overestimate these changes (COecho = 1.58 × COTD − 0.13; r2 = 0.53). Conclusions: Calibrated pulse contour analysis using the PulseCO system is an acceptable technique to measure cardiac output non‐invasively in off‐pump coronary bypass patients. Doppler echocardiography performs less well and is not always feasible with transoesophageal echocardiography when the heart is displaced.

A randomised controlled trial of intravenous dexamethasone combined with interscalene brachial plexus blockade for shoulder surgery

We recruited patients scheduled for shoulder rotator cuff repair or subacromial decompression under general anaesthesia and interscalene brachial plexus blockade (30 ml ropivacaine 0.5%). We allocated 240 participants into four groups of 60 that were given pre‐operative saline 0.9% or dexamethasone 1.25 mg, 2.5 mg or 10 mg, intravenously. We recorded outcomes for 48 h. The median (IQR [range]) time to first postoperative analgesic request after saline was 12.2 (11.0–14.1 [1.8–48]) h, which was extended by intravenous dexamethasone 2.5 mg and 10 mg to 17.4 (14.9–21.5 [7.2–48]) h, p < 0.0001, and 20.1 (17.2–24.3 [1.3–48]) h, p < 0.0001, respectively, but not by dexamethasone 1.25 mg, 14.0 (12.1–17.7 [2.1–48]) h, p = 0.05. Postoperative analgesia was given sooner after rotator cuff repair than subacromial decompression, hazard ratio (95% CI) 2.2 (1.6–3.0), p < 0.0001, but later in older participants, hazard ratio (95% CI) 0.98 (0.97–0.99) per year, p < 0.0001.

Regional anesthesia outside the operating room: indications and techniques.

Purpose of review Regional anesthesia is not only performed in the operating room. There are indications for the use of these techniques for pain relief in the emergency department and for anesthesia support of procedures outside the operating room. In this review, we will provide an overview of the indications for the regional techniques performed in the out-of-operating room environment. Recent findings In the emergency department, patients may experience significant pain, and adequate analgesia is not always provided. Regional analgesia is effective and indicated for many trauma situations including hip fracture, reduction of shoulder dislocation, treatment of upper limb fractures and multiple rib fractures. Ultrasound guidance makes the performance of regional blocks more accessible and safer for use in the emergency department setting. For therapeutic procedures outside the operating room, regional anesthesia is possible for uterine artery embolization and for postoperative analgesia after implantation of cervical brachytherapy needles. Summary Regional anesthesia is a valuable option for analgesia in trauma patients, enabling improved pain control in the emergency department and has benefits in the anesthetic management of therapeutic procedures outside the operating room. For many blocks, ultrasound guidance is useful.