Philippe Frascarolo

Preconditioning by Sevoflurane Decreases Biochemical Markers for Myocardial and Renal Dysfunction in Coronary Artery Bypass Graft Surgery: A Double-blinded, Placebo-controlled, Multicenter Study

Background Preconditioning by volatile anesthetics is a promising therapeutic strategy to render myocardial tissue resistant to perioperative ischemia. It was hypothesized that sevoflurane preconditioning would decrease postoperative release of brain natriuretic peptide, a biochemical marker for myocardial dysfunction. In addition, several variables associated with the protective effects of preconditioning were evaluated. Methods Seventy-two patients scheduled for coronary artery bypass graft surgery under cardioplegic arrest were randomly assigned to preconditioning during the first 10 min of complete cardiopulmonary bypass with either placebo (oxygen–air mixture only) or sevoflurane 4 vol% (2 minimum alveolar concentration). No other volatile anesthetics were administered at any time during the study. Treatment was strictly blinded to anesthesiologists, perfusionists, and surgeons. Biochemical markers of myocardial dysfunction and injury (brain natriuretic peptide, creatine kinase–MB activity, and cardiac troponin T), and renal dysfunction (cystatin C) were determined. Results of Holter electrocardiography were recorded perioperatively. Translocation of protein kinase C was assessed by immunohistochemical analysis of atrial samples. Results Sevoflurane preconditioning significantly decreased postoperative release of brain natriuretic peptide, a sensitive biochemical marker of myocardial contractile dysfunction. Pronounced protein kinase C &dgr; and &egr; translocation was observed in sevoflurane-preconditioned myocardium. In addition, postoperative plasma cystatin C concentrations increased significantly less in sevoflurane-preconditioned patients. No differences between groups were found for perioperative ST-segment changes, arrhythmias, or creatine kinase–MB and cardiac troponin T release. Conclusions Sevoflurane preconditioning preserves myocardial and renal function as assessed by biochemical markers in patients undergoing coronary artery bypass graft surgery under cardioplegic arrest. This study demonstrated for the first time translocation of protein kinase C isoforms &dgr; and &egr; in human myocardium in response to sevoflurane.

A comparison of the electrocardiographic cardiotoxic effects of racemic bupivacaine, levobupivacaine, and ropivacaine in anesthetized swine.

We sought, in this observer-blinded study, to determine the lethal dose for each of the local anesthetics levobupivacaine (L), racemic bupivacaine (B), and ropivacaine (R), and to compare their respective effects on the QRS interval of the precordial electrocardiograph after intracoronary injection. Anesthetized swine were instrumented with a left anterior descending artery coronary angiography catheter and injected with increasing doses of L, B, or R according to a randomized protocol. The doses administered were 0.375, 0.75, 1.5, 3.0, and 4.0 mg, with further doses increasing in 1-mg increments until death occurred. Plotting the mean maximum QRS interval as a function of the log10 mmol dose allowed the following cardiotoxicity potency ratios to be determined for a doubling of QRS duration—B:L:R = 2.1:1.4:1. The lethal doses in millimoles (median/range) for L and R were (0.028/0.024–0.031) and (0.032/0.013–0.032), respectively, and were significantly higher than for B (0.015/0.012–0.019) − (P < 0.05, n = 7 for all groups). The lethal dose did not differ between R and L. Thus, the cardiotoxicity potency ratios for the three anesthetics based on lethal dose were: 2.1:1.2:1. If the anesthetic potencies for B and L are similar, the latter should have less potential for cardiotoxicity in the clinical situation. Implications Animal experiments have shown levobupivacaine and ropivacaine to be less cardiotoxic than racemic bupivacaine. This in vivo study, using a validated swine model, compared the relative direct cardiotoxicities of these three local anesthetics. The lethal dose did not differ between levobupivacaine and ropivacaine, but was lowest for racemic bupivacaine.

Positive end-expiratory pressure during induction of general anesthesia increases duration of nonhypoxic apnea in morbidly obese patients.

Positive end-expiratory pressure (PEEP) applied during induction of anesthesia prevents atelectasis formation and increases the duration of nonhypoxic apnea in nonobese patients. PEEP also prevents atelectasis formation in morbidly obese patients. Because morbidly obese patients have difficult airway management more often and because arterial desaturation develops rapidly, we studied the clinical benefit of PEEP applied during anesthesia induction. Thirty morbidly obese patients were randomly allocated to one of two groups. In the PEEP group, patients breathed 100% O2 through a continuous positive airway pressure device (10 cm H2O) for 5 min. After induction of anesthesia, they were mechanically ventilated with PEEP (10 cm H2O) for another 5 min until tracheal intubation. In the control group, the sequence was the same but without any continuous positive airway pressure or PEEP. We measured apnea duration until Spo2 reached 90% and we performed arterial blood gases analyses just before apnea and at 92% Spo2. Nonhypoxic apnea duration was longer in the PEEP group compared with the control group (188 ± 46 versus 127 ± 43 s; P = 0.002). Pao2 was higher before apnea in the PEEP group (P = 0.038). Application of positive airway pressure during induction of general anesthesia in morbidly obese patients increases nonhypoxic apnea duration by 50%.

The effect of increased FIO(2) before tracheal extubation on postoperative atelectasis.

General anesthesia promotes pulmonary atelectasis, which can be eliminated by a vital capacity (VC) maneuver (inflation of the lungs to 40 cm H2O for 15 s). High-inspired oxygen concentration favors recurrence of atelectasis. Therefore, 100% oxygen before tracheal extubation may contribute to atelectasis. To evaluate whether the use of 100% oxygen before extubation increases the amount of postoperative atelectasis, we studied 30 adults scheduled for elective surgery of the extremities. Ten minutes before the presumed end of surgery, patients were randomly assigned to (a) a fraction of inspired oxygen (Fio2) = 1.0 (n = 10), (b) VC maneuver + Fio2 = 1.0 (n = 10), or (c) VC maneuver + Fio2 = 0.4 (n = 10). The amount of atelectasis was measured by computed tomography scan, and oxygenation was studied by arterial blood gas analysis. Data were analyzed by one-way analysis of variance with Bonferroni correction. Results are presented as mean ± sd;P < 0.05 was considered significant. In the VC maneuver + Fio2 = 0.4 group, postoperative atelectasis was smaller (2.6% ± 1.1% of total lung surface, P < 0.05) than in the Fio2 = 1.0 group (8.3% ± 6.2%) and in the VC maneuver + Fio2 = 1.0 group (6.8% ± 3.4%). Oxygen 100% at the end of general anesthesia promotes postoperative atelectasis. A safety margin in terms of oxygenation during tracheal extubation is essential, and further studies should therefore evaluate whether atelectasis formation could be prevented despite the use of 100% oxygen.

Videolaryngoscopy improves intubation condition in morbidly obese patients

Background and objective Tracheal intubation may be more difficult in morbidly obese patients (body mass index >35 kg m−2) than in the non‐obese. Recently, new video‐assisted intubation devices have been developed. After some experience with videolaryngoscopy, we hypothesized that it could improve the laryngoscopic view in this specific population and therefore facilitate intubation. The aim of this study was to assess the benefit of a videolaryngoscope on the grade of laryngoscopy in morbid obesity. Methods We studied 80 morbidly obese patients undergoing bariatric surgery. They were randomly assigned to one of two groups. One group was intubated with the help of the videolaryngoscope and in the control group the screen of the videolaryngoscope was hidden to the intubating anaesthesiologist. The primary end‐point of the study was to assess in both groups the Cormack and Lehane direct and indirect grades of laryngoscopy. The duration of intubation, the number of attempts needed as well as the minimal SPO2 reached during the intubation process were measured. Results Grade of laryngoscopy was significantly lower with the videolaryngoscope compared with the direct vision (P < 0.001). When the grade of laryngoscopy was higher than one with the direct laryngoscopy (n = 30), it was lower in 28 cases with the videolaryngoscope and remained the same only in two cases (P < 0.001). The minimal SPO2 reached during the intubation was higher with the videolaryngoscope but it did not reach statistical significance. Conclusions In morbidly obese patients, the use of the videolaryngoscope significantly improves the visualization of the larynx and thereby facilitates intubation.

Effect of high-and low-molecular-weight low-substituted hydroxyethyl starch on blood coagulation during acute normovolemic hemodilution in pigs

Background:Hydroxyethyl starches (HES) with lower impact on blood coagulation but longer intravascular persistence are of clinical interest. The current study aimed to investigate in vivo the isolated effect of molecular weight on blood coagulation during progressive acute normovolemic hemodilution. Methods:Twenty-four pigs were normovolemically hemodiluted up to a total exchange of 50 ml · kg−1 · body weight−1 of HES 650/0.42 or HES 130/0.42. Serial blood sampling was performed to measure HES plasma concentration and to assess blood coagulation. Concentration–effect relations were analyzed by linear regression, followed by the Student t test on regression parameters. Results:Blood coagulation was increasingly compromised toward hypocoagulability by acute normovolemic hemodilution with both treatments (P < 0.01). Significantly greater impact on activated partial thromboplastin time (P = 0.04) and significantly stronger decrease of maximal amplitude (P = 0.04), angle &agr; (P = 0.02), and coagulation index (P = 0.02) was seen after acute normovolemic hemodilution with HES 650/0.42 as compared with HES 130/0.42. Except for factor VIII (P = 0.04), no significant differences between both treatments were observed when relating antihemostatic effects to HES plasma concentrations (P > 0.05). A significantly lesser decrease of hemoglobin concentration has been found with HES 650/0.42 as compared with HES 130/0.42 (P < 0.01) in relation to HES plasma concentrations. Conclusion:High-molecular-weight HES (650/0.42) shows a moderately greater antihemostatic effect than low-molecular-weight HES (130/0.42) during acute normovolemic hemodilution. However, similar effects on hemostasis were observed with both treatments when observed antihemostatic effects were related to measured HES plasma concentrations. In addition, HES 650/0.42 may have a lower efficacy in immediately restoring plasma volume.

Validity of an Arterial Pressure Waveform Analysis Device: Does the Puncture Site Play a Role in the Agreement With Intermittent Pulmonary Artery Catheter Thermodilution Measurements?

OBJECTIVE The measurement of cardiac output is a key element in the assessment of cardiac function. Recently, a pulse contour analysis-based device without need for calibration became available (FloTrac/Vigileo, Edwards Lifescience, Irvine, CA). This study was conducted to determine if there is an impact of the arterial catheter site and to investigate the accuracy of this system when compared with the pulmonary artery catheter using the bolus thermodilution technique (PAC). DESIGN Prospective study. SETTING The operating room of 1 university hospital. PARTICIPANTS Twenty patients undergoing cardiac surgery. INTERVENTIONS CO was determined in parallel by the use of the Flotrac/Vigileo systems in the radial and femoral position (CO_rad and CO_fem) and by PAC as the reference method. Data triplets were recorded at defined time points. The primary endpoint was the comparison of CO_rad and CO_fem, and the secondary endpoint was the comparison with the PAC. MEASUREMENTS AND MAIN RESULTS Seventy-eight simultaneous data recordings were obtained. The Bland-Altman analysis for CO_fem and CO_rad showed a bias of 0.46 L/min, precision was 0.85 L/min, and the percentage error was 34%. The Bland-Altman analysis for CO_rad and PAC showed a bias of -0.35 L/min, the precision was 1.88 L/min, and the percentage error was 76%. The Bland-Altman analysis for CO_fem and PAC showed a bias of 0.11 L/min, the precision was 1.8 L/min, and the percentage error was 69%. CONCLUSION The FloTrac/Vigileo system was shown to not produce exactly the same CO data when used in radial and femoral arteries, even though the percentage error was close to the clinically acceptable range. Thus, the impact of the introduction site of the arterial catheter is not negligible. The agreement with thermodilution was low.

Single-injection or Continuous Femoral Nerve Block for Total Knee Arthroplasty?

BackgroundThe ideal local anesthetic regime for femoral nerve block that balances analgesia with mobility after total knee arthroplasty (TKA) remains undefined.Questions/purposesWe compared two volumes and concentrations of a fixed dose of ropivacaine for continuous femoral nerve block after TKA to a single injection femoral nerve block with ropivacaine to determine (1) time to discharge readiness; (2) early pain scores and analgesic consumption; and (3) functional outcomes, including range of motion and WOMAC scores at the time of recovery.MethodsNinety-nine patients were allocated to one of three continuous femoral nerve block groups for this randomized, placebo-controlled, double-blind trial: a high concentration group (ropivacaine 0.2% infusion), a low concentration group (ropivacaine 0.1% infusion), or a placebo infusion group (saline 0.9% infusion). Infusions were discontinued on postoperative Day (POD) 2. The primary outcome was time to discharge readiness. Secondary outcomes included opioid consumption, pain, and functional outcomes. Ninety-three patients completed the study protocol; the study was halted early because of unanticipated changes to pain protocols at the host institution, by which time only 61% of the required number of patients had been enrolled.ResultsWith the numbers available, the mean time to discharge readiness was not different between groups (high concentration group, 62 hours [95% confidence interval [CI], 51–72 hours]; low concentration group, 73 hours [95% CI, 63–83 hours]; placebo infusion group 65 hours [95% CI, 56–75 hours]; p = 0.27). Patients in the low concentration group consumed significantly less morphine during the period of infusion (POD 1, high concentration group, 56 mg [95% CI, 42–70 mg]; low concentration group, 35 mg [95% CI, 27–43 mg]; placebo infusion group, 48 mg [95% CI, 38–59 mg], p = 0.02; POD 2, high concentration group, 50 mg [95% CI, 41–60 mg]; low concentration group, 33 mg [95% CI, 24–42 mg]; placebo infusion group, 39 mg [95% CI, 30–48 mg], p = 0.04); however, there were no important differences in pain scores or opioid-related side effects with the numbers available. Likewise, there were no important differences in functional outcomes between groups.ConclusionsBased on this study, which was terminated prematurely before the desired sample size could be achieved, we were unable to demonstrate that varying the concentration and volume of a fixed-dose ropivacaine infusion for continuous femoral nerve block influences time to discharge readiness when compared with a conventional single-injection femoral nerve block after TKA. A low concentration of ropivacaine infusion can reduce postoperative opioid consumption but without any important differences in pain scores, side effects, or functional outcomes. These pilot data may be used to inform the statistical power of future randomized trials.Level of EvidenceLevel II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Is the effect of inguinal field block with 0.5% bupivacaine on postoperative pain after hernia repair enhanced by addition of ketorolac or S(+) ketamine?

Objective: The aim of the study was to assess whether coadministration of S(+) ketamine or ketorolac would enhance or prolong local analgesic effect of bupivacaine after inguinal hernia repair. Design: Prospective double-blind randomized study evaluating pain intensity after surgery under general anesthesia. Setting: Outpatient facilities of the University Hospital of Lausanne. Patient: Thirty-six ASA I-II outpatients scheduled for elective day-case inguinal herniorraphy. Intervention: Analgesia strategy consisted of a wound infiltration and an inguinal field block either with 30 mL bupivacaine (0.5%) or with the same volume of a mixture of 27 mL bupivacaine (0.5%) + 3 mL S(+) ketamine (75 mg) or a 28 mL bupivacaine (0.5%) + 2 mL ketorolac (60 mg). Postoperative analgesic regimen was standardized. Outcome Measures: Pain intensity was assessed with a Visual Analog Scale, a verbal rating score, and by pressure algometry 2, 4, 6, 24, and 48 hours after surgery. Results: The 3 groups of patients experienced the highest Visual Analog Scale pain score at 24 hours, which was different from those at 6 and 48 hours (P < 0.05). Apart from a significantly lower pain sensation (verbal rating score) in the ketorolac group at 24 and 48 hours and only at 48 hours with ketamine, there were no other differences in pain scores, pain pressure thresholds, or rescue analgesic consumption between groups throughout the 48-hour study period. Conclusion: The addition of S (+)-ketamine or ketorolac only minimally improves the analgesic effect of bupivacaine. This may be related to the tension-free hernia repair technique associated with low postoperative pain.

Benefits of Endoscopic Vein Harvesting

The purpose of this study was to evaluate and compare the benefits of endoscopic saphenous vein harvesting (EVH) with the traditional incision technique (TIT) for coronary artery bypass grafting (CABG) in respect to the technical procedure and clinical outcome. In a prospective nonrandomized, case-matched study the greater saphenous vein was harvested for CABG in 22 patients using the endoscopic technique and in 18 patients with the traditional method. Comparisons were made for the operating time, length of incision and vein harvested, graft quality, postoperative complications, and pain assessment. Patient demographics were well matched. EVH required smaller incisions than did the TIT (10.5 ± 6.6 vs. 31.2 ± 7.8 cm, respectively; p < 0.0001). Harvest time and vein quality were comparable in the two groups. Total vein operating time was shorter following the endoscopic technique (60 ± 24 vs. 100 ± 35 minutes, respectively; p < 0.0001). EVH had fewer complications (NS), and postoperative pain was significantly less (p= 0.0034). The major advantages of endoscopic vein harvesting are a significant reduction of postoperative pain and strikingly better cosmetic results. Wound complications seem to be less frequent.