Comparison of the efficacy of esmolol and alfentanil to attenuate the hemodynamic responses to emergence and extubation

Study Objective: To define the ability of esmolol and alfentanil to control the hemodynamic changes associated with extubation and emergence.

Design: Randomized, double-blind, placebo-controlled study.

Setting: General surgery operating rooms at a university hospital.

Patients: Forty-two ASA physical status I and II patients without history of cardiac or pulmonary disease undergoing surgery not involving the cranium or thorax.

Interventions: Patients were given either a bolus dose of normal saline followed by an infusion of normal saline, a bolus dose of alfentanil 5 μg/kg followed by an infusion of normal saline, or a bolus dose of esmolol 500 μg/kg followed by an infusion of esmolol 300 μg/kg/min.

Measurements and Main Results: Emergence and extubation resulted in significant increases in heart rate (HR) and blood pressure (BP) in the placebo group. Alfentanil controlled the responses to emergence but prolonged the time to extubation (p < 0.05). Esmolol significantly controlled the responses to emergence and extubation (p < 0.05).

Conclusions: Emergence and extubation after inhalation general anesthesia result in significant increases in BP and HR in healthy patients. An esmolol bolus dose and subsequent infusion significantly attenuated these responses. A small bolus dose of alfentanil minimized the responses to emergence but prolonged the time to extubation and was no longer protective at that point.     

Time to peak effect of neostigmine at antagonism of atracurium- or vecuronium-induced neuromuscular block

Study Objective: (1) To determine the time to peak effect of neostigmine (time to peak antagonism) during atracurium- or vecuronium-induced neuromuscular block; and (2) to determine the effect on time to peak effect of neostigmine during atracurium-induced neuromuscular block, when the dose of neostigmine is increased from 35 μg/kg to 70 μg/kg.

Design: Prospective, randomized clinical study.

Setting: Gynecologic operating room suite at a university hospital.

Patients: 45 ASA I and II women admitted for gynecologic laparotomy.

Interventions: Anesthesia was performed with thiopental sodium, fentanyl, halothane, nitrous oxide, and atracurium or vecuronium. Train-of-four (TOF) stimulation and mechanomyography were used to monitor neuromuscular transmission. Neostigmine was administered while a constant degree of neuromuscular block was maintained at a twitch height at a point between 4% and 11% of the control twitch height, using a continuous infusion of atracurium or vecuronium. The patients were randomized to three groups, with 15 patients in each group. Group 1 received atracurium block antagonized with neostigmine 35 μg/kg; group 2 received vecuronium block antagonized with neostigmine 35 μg/kg; and group 3 received atracurium block antagonized with neostigmine 70 μg/kg.

Measurements and Main Results: The degree of neuromuscular block at antagonism was similar in the three groups. Time to peak effect (mean ± SD) on TOF ratio was significantly longer in Group 1 (9.7 ± 3.0 minutes) versus Group 2 (6.6 ± 1.4 minutes; (p < 0.05). The time to peak effect on TOF ratio during atracurium-induced block was reduced from 9.7 ± 3.0 minutes to 6.3 ± 2.0 minutes when the dose of neostigmine was increased from 35 μg/kg to 70 μg/kg (p < 0.05). The peak effect on TOF ratio was significantly greater in Group 3 compared with Group 1 (p < 0.05), while it was similar in groups 1 and 2.

Conclusion: The time to peak effect of neostigmine 35 μg/kg is about 6 to 10 minutes when antagonizing a constant degree of atracurium- or vecuronium-induced neuromuscular block at a twitch height at a point between 4% and 11%. Even though the time to peak effect was longer with atracurium than with vecuronium, clinically significant differences between the antagonizing effect of atracurium versus vecuronium block were not demonstrated. The time to peak effect during atracurium-induced block decreased when the dose of neostigmine was increased from 35 μg/kg to 70 μg/kg.     

Effect of Low-Dose Positive Inotropic Drugs on Human Internal Mammary Artery Flow

Background. Dobutamine (a β-receptor agonist), enoximone (a type III selective phosphodiesterase inhibitor), and epinephrine (an - and β-mimetic) frequently are used in the perioperative management of patients undergoing coronary artery bypass grafting.

Methods. We performed a double-blind clinical study to compare the effects on internal mammary artery free flow of low doses of these three positive inotropic drugs. Thirty patients in whom the left internal mammary artery was used for coronary artery bypass grafting were randomized into three groups. Internal mammary artery free flow and hemodynamic measurements were evaluated before and 10 minutes after the intravenous infusion of dobutamine (3 μg · kg⁻¹ · min⁻¹), enoximone (200 μg/kg), or epinephrine (0.05 μg · kg⁻¹ · min⁻¹).

Results. A significant increase in free flow occurred only in the dobutamine group (33 ± 7.5 and 42.2 ± 7.9 mL/min before and after drug infusion, respectively; p = 0.013). Comparison of the increase in flow between the groups, however, showed no difference. These drugs, at doses designed to produce a positive inotropic effect, caused little increase in the free flow of the internal mammary artery.

Conclusions. The use of dobutamine, enoximone, and epinephrine as low-dose positive inotropic treatments in the perioperative and postoperative periods of coronary artery bypass grafting should depend on their positive inotropic effects rather than their vasodilative effects on the arterial grafts.     

Cytostatic Lung Perfusion by Use of an Endovascular Blood Flow Occlusion Technique

Background. Different modalities of cytostatic lung perfusion were compared regarding plasma and tissue drug concentrations to assess the efficacy of an endovascular blood flow occlusion technique.

Methods. A cytostatic lung perfusion study with doxorubicin hydrochloride was performed on large white pigs (n = 12). Plasma and tissue concentrations of doxorubicin were compared for isolated lung perfusion with open cannulation (ILP), blood flow occlusion perfusion with open cannulation of the pulmonary artery alone (BFO), and intravenous drug administration (IV). In a fourth group, thoracotomy-free BFO perfusion was performed by endovascular balloon catheterization of the pulmonary artery (endovascular BFO). The 3 animals in this group were used to compare the doxorubicin-perfused pulmonary tissue with the contralateral nonperfused lobes after 1 month.

Results. The mean lung tissue doxorubicin concentration at the end of perfusion was 19.8 ± 1.6 μg/g after ILP, 27.6 ± 2.2 μg/g after BFO (p = not significant), and 3.0 ± 0.8 μg/g after IV perfusion (p < 0.01). Whereas doxorubicin was not detectable in the plasma in the ILP group, concentrations ranged from not detectable to 0.44 μg/mL in the BFO group and from 0.31 to 0.84 μg/mL in the IV group (p < 0.05). Mean myocardial tissue concentration was not significantly different after BFO than IV perfusion (1.1 ± 0.5 μg/g and 1.8 ± 0.1 μg/g, respectively). In the endovascular BFO group, balloon-blocked pulmonary artery perfusion was successfully performed in all animals, and after 1 month, lung tissue showed no cytostatic-induced histologic changes.

Conclusions. Compared with ILP, BFO cytostatic lung perfusion produced an insignificantly higher lung-tissue concentration, corresponding to a sixfold to ninefold higher level than after IV perfusion. Plasma drug levels during BFO perfusion were lower than during IV perfusion. Endovascular BFO may be a promising technique for repeated cytostatic lung perfusion.     

Efficacy of intracoronary versus intravenous FGF-2 in a pig model of chronic myocardial ischemia

Background. Therapeutic angiogenesis in ischemic myocardium has been shown to be a feasible and effective strategy to improve regional blood flow and myocardial function. However, the optimal mode of growth factor administration still needs to be established.

Methods. Using a pig model of chronic myocardial ischemia, we evaluated the efficacy of intravenous and intracoronary infusion of FGF-2 at 2 and 6 μg/kg compared with a vehicle control. Improvement in myocardial perfusion and function was assessed by angiography, colored microspheres, and function and perfusion magnetic resonance imaging.

Results. Intracoronary 6-μg/kg FGF-2 increased angiographic collaterals (p = 0.046) and increased regional blood flow to the ischemic area from 0.36 ± 0.07 to 0.59 ± 0.08 mL/min/g at stress (vs control, p = 0.032). Also, after 6 μg/kg intracoronary FGF-2, ejection fraction, regional wall motion, and thickening improved significantly by 9.9% ± 1.9%, 126% ± 39%, and 13.8% ± 3.6%, respectively. Intravenous FGF-2 and intracoronary 2 μg/kg FGF-2 were ineffective.

Conclusions. A single 6-μg/kg intracoronary treatment with FGF-2 resulted in significant improvement in collateralization and regional and global function of chronically ischemic myocardium. Single intravenous infusion of FGF-2 was not effective in this model.     

The induction, maintenance, and recovery characteristics of spinal versus general anesthesia in elderly patients

Study Objective: To compare the induction and recovery profiles of three combinations of general anesthesia when used as an alternative to spinal anesthesia for elderly patients.

Design: Randomized, prospective, open-label study.

Setting: Large referral hospital.

Patients: 100 [ASA physical status I, II, and III] patients over 60 years of age undergoing brief transurethral surgery.

Interventions: In Groups Propofol-Propofol (P-P), Propofol-Isoflurane (P-I), and Propofol-Desflurane (P-D), anesthesia was induced with fentanyl (1 to 2 μg/kg IV) and propofol (1.0 to 2.0 mg/kg IV) and maintained with 70% nitrous oxide in oxygen and either a propofol infusion (75 to 150 μg/kg/min) or isoflurane (end-tidal 0.7% to 1.2%) or desflurane (end-tidal 1% to 4%), respectively. After induction, a laryngeal mask airway was placed and spontaneous ventilation was maintained. In Group Spinal (S), 1.5 ml 4% lidocaine (60 mg), in an equal volume of 10% dextrose, was administered intrathecally.

Measurements and Main Results: Induction and recovery characteristics were compared. Induction with propofol was technically easier and significantly (medp < 0.0001) faster (4.6 ± 1.7 min, 4.7 ± 2.2 min, and 3.8 ± 1.4 min for Groups P-P, P-I, and P-D, respectively) than induction of spinal anesthesia (9.3 ± 3.4 min). During the induction period, mean arterial blood pressure and heart rate were significantly higher in Group S. Emergence, extubation, and orientation times were similar among the general anesthesia treatment groups. In Group S, patient-generated pain scores were lower (p < 0.05) and recovery room admission longer (p < 0.001). Time to return to baseline digit symbol substitution test (DSST) scores was marginally improved in Groups P-P and P-D when compared to Group P-I. Postoperative nausea, sleepiness, anxiety, and coordination were unaffected by the treatment modality.

Conclusion: General anesthesia with propofol and desflurane facilitates shorter induction and recovery times without adversely affecting patient comfort. Therefore, this technique may be preferable to spinal anesthesia for elderly patients undergoing short transurethral surgical procedures.     

Insulin improves functional and metabolic recovery of reperfused working rat heart

Background. Glucose, insulin, and potassium solution improves left ventricular function in refractory pump failure. Direct effects of insulin on the heart cannot be determined in vivo. We hypothesized that insulin has a direct positive inotropic effect on the reperfused heart.

Methods. Isolated working rat hearts were perfused with buffer containing glucose (5 mmol/L) plus oleate (1.2 mmol/L). Hearts were subjected to 15 minutes of ischemia and reperfused with or without insulin (100 μU/mL) for 40 minutes. Epinephrine (1 μmol/L) was added for the last 20 minutes.

Results. Hearts recovered 51.1% of preischemic cardiac power in the absence and 76.4% in the presence of insulin (p < 0.05). Whereas oleate oxidation remained unchanged, glucose uptake and oxidation increased during reperfusion with epinephrine (p < 0.01). This increase was significantly greater when hearts were reperfused in the presence of insulin (p < 0.01). Insulin also prevented an epinephrine-induced glycogen breakdown during reperfusion (p < 0.05).

Conclusions. Insulin has a direct positive inotropic effect on postischemic rat heart. This effect is additive to epinephrine and occurs without delay. Increased rates of glucose oxidation and net glycogen synthesis are more protracted.     

Effects of diltiazem on renin-aldosterone and ACTH-adrenocortical function during upper abdominal surgery

Study Objective: To observe the effects of continuous intravenous infusion of diltiazem on the renin-aldosterone system and ACTH-adrenocortical axis responses during surgical stimulation.

Design: Randomized study of intravenous diltiazem.

Setting: Operating room at the Hyogo Medical College Hospital.

Patients: Twenty-three patients undergoing upper abdominal surgery were divided into two groups: the control group (n = 10) and the diltiazem group (n = 13). All the patients were without any complications and classified as ASA physical status I.

Interventions: Patients in the diltiazem group received an infusion of 10 μg/kg/ min for 90 to 120 minutes following skin incision.

Measurements and Main Results: Plasma adrenocorticotropic hormone, plasma aldosterone and cortisol concentrations, and plasma renin activity were determined with radioimmunoassay before the induction of anesthesia at 10, 30, 60, and 90 minutes after skin incision and at the end of anesthesia. Renin activity did not change significantly. Maximal increases in plasma adrenocorticotropic hormone, aldosterone, and cortisol observed 90 minutes after skin incision were 355 ± 95 pg/ml, 118 ± 30 pg/ml, and 14.2 ± 2.3 μg/dl in the control group versus 246 ± 41 pg/ml, 119 ± 25 pg/ml, and 15.0 ± 1.8 μg/dl in the diltiazem group, respectively, and there were no significant differences between these groups. Adrenocorticotropic hormone was significantly lower in the diltiazem group compared with that in the control group 60 minutes after the start of surgery (p < 0.05). There was marked natriuresis (40 ± 25 μEq/min vs 470 ± 147 μEq/min at the 90-minute mark) and diuresis (0.16 ± 0.13 ml/min vs. 2.53 ± 0.88 ml/min) in the diltiazen group.     

Effects of prostaglandin E1 on the cardiovascular response to tracheal intubation

Study Objective: To evaluate the efficacy of prostaglandin E, in attenuating the hypertensive response to laryngoscopy and intubation.

Design: Controlled, comparative, and randomized study.

Setting: Induction of anesthesia for elective surgery at a university hospital.

Patients: Thirty normotensive patients (ASA physical status I) undergoing elective surgery divided into three groups. Each group consisted of ten patients.

Interventions: Anesthesia was induced with thiopental sodium 5 mglkg intravenously, and tracheal intubation was facilitated with vecuronium 0.2 mglkg. Either 0.3 μglkg of prostaglandin E₁, 0.6 μg/kg of prostaglandin E₁, or saline (control) was injected 15 seconds before starting direct laryngoscopy (within 30 seconds), which was attempted 2 minutes after administration of thiopental sodium and vecuronium.

Measurements and Main Results: Patients receiving saline showed a significant increase in mean arterial pressure and rate-pressure product associated with tracheal intubation. These increases following tracheal intubation were significantly less in prostaglandin E₁-treated patients than in the control group (p < 0.05).

Conclusions: A single rapid intravenous administration of prostaglandin E₁ is a practical pharmacologic and safe method to attenuate the hypertensive response to tracheal intubation. The use of 0.6 μglkg of prostaglandin E₁ as a supplement during induction is recommended for reducing the pressor response to intubation on the basis of rate-pressure product and mean arterial pressure , following intubation as an index.     

Clinical evaluation of leukocyte-depleted blood cardioplegia for pediatric open heart operation

Background. Blood cardioplegia (BCP) is widely used for myocardial protection during open heart operation. However, BCP may have a chance to induce neutrophil-mediated myocardial injury during aortic cross-clamping. We clinically evaluated the myocardial protective effect of leukocyte-depleted blood cardioplegia (LDBCP) for initial and intermittent BCP administration in pediatric patients.

Methods. Fifty patients undergoing open heart operation for congenital heart disease between January 1997 and March 1999 were reviewed. Twenty-five were administered LDBCP for myocardial protection during ischemic periods (LDBCP group), and the remaining 25 were given BCP without leukocyte depletion (BCP group).

Results. The difference in plasma concentrations of malondialdehyde between coronary sinus effluent blood and arterial blood just after reperfusion in the LDBCP group (1.68 ± 0.56 μmol/L) was significantly lower than that in the BCP group (2.35 ± 0.62 μmol/L; p < 0.01). The LDBCP group showed significantly lower plasma concentrations of human heart fatty acid-binding protein at 50 minutes after reperfusion (LDBCP group, 103.5 ± 38.7 IU/L; BCP group, 144.8 ± 48.8 IU/L; p < 0.01) and the peak value of creatine kinase-MB during the first 24 postoperative hours (LDBCP group, 17.0 ± 8.5 IU/L; BCP group, 26.0 ± 11.6 IU/L; p < 0.01) than did the BCP group. The maximum dose of catecholamine was significantly smaller in the LDBCP group (LDBCP group, 3.20 ± 2.18 μg · kg⁻¹ · min⁻¹; BCP group, 5.60 ± 2.83 μg · kg⁻¹· min⁻¹; p < 0.01).

Conclusions. These results suggest the usefulness of LDBCP for protection from the myocardial injury that can be induced by BCP administration during aortic cross-clamping.     

Patient-controlled drug administration during local anesthesia: A comparison of midazolam, propofol, and alfentanil

Study Objective: To evaluate the perioperative effects of alfentanil, midazolam, and propofol when administered using a patient-controlled analgesia (PCA) device during local anesthesia.

Design: Randomized, single-blind comparative study.

Setting: Outpatient surgery center at a university teaching hospital.

Patients: Ninety outpatients undergoing minor elective surgical procedures with local anesthetic infiltration were assigned to one of three treatment groups.

Interventions: After premedication with midazolam 1 mg intravenously (IV) and fentanyl 50 μg IV, patients were allowed to self-administer 2 ml bolus doses of either alfentanil 250 μg/ml, midazolam 0.4 mg/ml, or propofol 10 mg/ml at minimal intervals of 3 minutes to supplement a basal infusion rate of 5 ml/hr.

Measurements and Main Results: The total intraoperative dosages of alfentanil, midazolam, and propofol were 2.7 ± 1.1 mg, 4.7 ± 2.7 mg, and 114 ± 42 mg, respectively, for procedures lasting 48 ± 28 minutes to 51 ± 19 minutes (means ± SD). Propofol produced more pain on injection (39% vs. 4% and 6% in the alfentanil and midazolam groups, respectively). Episodes of arterial oxygen saturation less than 90% were more frequent with alfentanil (28%) than with midazolam (3%) or propofol (13%). Using the visual analog scale, patients reported comparable levels of discomfort, anxiety, and sedation during the operation in all three treatment groups. Postoperative picture recall was significantly decreased with midazolam versus alfentanil and propofol. Finally, postoperative nausea was reported more frequently in the alfentanil group (29%) than in the midazolam (10%) or propofol (18%) groups, contributing to a significant prolongation of the discharge time in the alfentanil-treated patients.

Conclusions: When self-administered as adjuvants during local anesthesia using a PCA delivery system, alfentanil, midazolam, and propofol were equally acceptable to patients. However, propofol and midazolam were associated with fewer perioperative complications than was alfentanil.     

Pretreatment with sedative-hypnotics, but not with nondepolarizing muscle relaxants, attenuates alfentanil-induced muscle rigidity

Study Objective: To evaluate and compare the efficacy of various pretreatment agents to attenuate or prevent opioid-induced muscle rigidity using a well-established, previously described clinical protocol.

Design: Prospective, controlled, single-blind, partially randomized study.

Setting: Large medical center.

Patients: ASA physical status I–III patients undergoing elective surgical procedures of at least 3 hours' duration.

Interventions: The effect of pretreatment with nondepolarizing muscle relaxants (atracurium 40μg/kg or metocurine 50,μg/kg), benzodiazepine agonists (diazepam 5 mg or midazolam 2.5 mg), or thiopental sodium 1 mg/kg on the increased muscle tone produced by alfentanil 175 ,μg/kg was compared with a control group (given no pretreatment).

Measurements and Main Results: Rigidity was assessed quantitatively by measuring the electromyographic activity of five muscle groups (biceps, intercostals, abdominals, quadriceps, and gastrocnemius). Rigidity also was rated qualitatively by attempts to initiate and maintain mask ventilation, attempts to flex an extremity, and the occurrence of myoclonic movements. Pretreatment with the two nondepolarizing muscle relaxants had no effect on the severe muscle rigidity produced by high-dose alfentanil. Whereas thiopental was only mildly effective, the benzodiazepines midazolam and diazepam significantly attenuated alfentanil rigidity (p < 0.05).

Conclusion: This study suggests that benzodiazepine pretreatment is frequently, but not always, effective in preventing opioid-induced muscle rigidity.     

Effect of low fresh gas flow rates on inspired gas composition in a circle absorber system

Study Objective: To determine the effects of fresh gas f ow on inspired gas composition during low flow anesthesia.

Design: Randomized trial with 2-hour observation periods in patients assigned to one of three groups.

Setting: Inpatient surgery clinic at a medical center.

Patients: Thirty-six patients undergoing abdominal surgery with low flow anesthesia. Interventions: Fresh gas flow was given at a starting rate of 5 L/min for 6 minutes. Thereafter, the fresh gas flow setting was nitrous oxide (N₂O) 1 L/min and oxygen (O₂) 0.6 L/min (Group 1), N₂O 0.5 L/min and O₂ 0.5 L/min (Group 2), and with a moderate surplus of N₂O and O₂ with respect to the patient's O₂ consumption (Group 3).

Measurements and Main Results: The inspired O₂ concentration (FIO₂) was measured using a paramagnetic technique, and N₂O levels were measured with infrared sensors; the inspired nitrogen concentration (FIN₂) was calculated by the following formula: (FIN₂) = 1 - FIO₂ - FIN₂O, where FIN₂O is the inspired N₂O concentration. After 1 hour of anesthesia, FIO₂ was significantly lower in Group 1 than in Groups 2 and 3 (p < 0.01), and FIN₂ was significantly higher in Groups 2 and 3 than in Group 1 (p < 0.01). After 2 hours of anesthesia, (FIN₂) returned to normal in Group 2 but continued to increase in Group 3. FIN₂O was close to 0.7% only in Group 1.

Conclusions: The same initial period of denitrogenation is not adequate to denitrogenate the circle system in all cases. The lower the fresh gas flow, the longer the initial period of denitrogenation should be. Various levels of fresh gas flow for low-flow anesthesia have been suggested, but none guarantees adequate control of inspired gas composition unless f owmeters are continuously adjusted.     

Determination of the analgesic dose–response relationship for epidural fentanyl and sufentanil with bupivacaine 0.125% in laboring patients

Study Objective: To establish the analgesic effective doses as defined as a visual analog pain scale (VAS) of at least 10 for 95% of parturients (ED₉₅) receiving either epidural fentanyl or sufentanil with bupivacaine 0.125% for labor analgesia.

Design: Double-blind, randomized controlled study.

Setting: Two tertiary-care teaching hospitals.

Patients: 100 female patients, at full-term pregnancy, in active early labor (<5 cm cervical dilation) and requesting obstetric anesthesia services for labor analgesia.

Interventions: Patients were randomized and equally distributed to receive one of ten epidural dosing regimens of bupivacaine 0.125% alone or with either fentanyl 25, 50, 75, or 100 μg or sufentanil 5, 10, 15, 20, or 25 μg in a 10-ml bolus after a 3-ml test dose of bupivacaine 0.25%.

Measurements and Main Results: VAS scores were obtained from each parturient using a 10-cm plastic VAS slide rule at times 0, 1, 5, 10, 15, 20, 25, and 30 minutes, and then again when the patient requested additional analgesia. Analgesic duration and demographic and obstetric data also were obtained. Using a log-probit dose–response analysis, analgesic success as defined as a VAS of at least 10 with each opioid dose was plotted and an ED₉₅ value of 8 μg and 50 μg was established for sufentanil and fentanyl, respectively, in bupivacaine 0.125%. No statistical difference was detected for analgesic duration or incidence of side effects between analgesic groups.

Conclusions: Epidural analgesia with fentanyl and sufentanil in bupivacaine 0.125% behaves in a dose–response fashion allowing for the determination of equipotent dose of each.     

Spontaneous movements associated with rocuronium injection: The effects of prior administration of fentanyl

Study Objective: To determine if prior injection of fentanyl decreases the incidence of spontaneous movements during rocuronium administration.

Design: Prospective, randomized, double-blind, placebo-controlled study.

Setting: University orthopedic surgical center.

Patients: 122 ASA physical status I and II patients scheduled for elective orthopedic surgery.

Interventions: Patients randomly received 2 ug/kg of fentanyl or the equivalent volume of NaCl 0.9% 45 seconds prior to induction of anesthesia. Induction was performed with propofol 2.5 mg/kg followed by rocuronium 0.8 mg/kg 60 seconds later. Spontaneous movements were scored as follows: a) limited to the hand, b) limited to the elbow, and c) involving the whole arm, including the shoulder.

Measurements and Main Results: Prior injection of fentanyl (2 ug/kg) significantly decreased the incidence of spontaneous movements limited to the hand: 5% versus 20% (p < 0.05); limited to the elbow: 1 % versus 25% (p < 0.05); and involving the whole arm: none versus 12% (p < 0.05). No erythema or any change in the skin surrounding the point of injection of the involved arm was observed. Twenty-four hours later, no vein induration was present and no patient complained of any residual pain.

Conclusion: Prior injection of fentanyl significantly decreases the incidence of spontaneous movements associated with rocuronium administration.     

Clonidine added to bupivacaine-epinephrine-sufentanil improves epidural analgesia during childbirth

Background and Objectives. A double-blind study was conducted to assess the efficacy and the side effects of a low dose of clonidine added to an epidural injection of bupivacaine and epinephrine, with or without sufentanil. Methods. One hundred healthy parturients (ASA 1) were randomly allocated into four groups according to the type of epidural analgesia administered. The bupivacaine/epinephrine (BE) group received a 10-mL standard injection of bupivacaine (B) 1.25 mg/mL and epinephrine (E) 1.25 μg/mL. In the bupivacaine/epinephrine/sufentanil (BES) group, 7.5 μg sufentanil (S) was added to the BE mixture. For the bupivacaine/epinephrine/clonidine (BEC) group, 50 μg clonidine (C) was added to the BE mixture, whereas for the bupivacaine/epinephrine/sufentanil/clonidine (BESC) group, both sufentanil and clonidine were added to BE. Fetal heart rate was monitored by continuous cardiotocography. Duration of analgesia, method of delivery, and neonatal outcome (measured using APGAR score, peripheral oxygen saturation, and neurologic adaptive capacity score) and side effects of clonidine were observed. The parturients were routinely asked for their global appreciation of the epidural analgesia technique by visual analog score, 2 hours postpartum. Results. The overall quality and duration of analgesia were superior in the BESC group compared with the other groups, as was the global appreciation by the parturient. The frequency of side effects in the clonidine groups was comparable, with the exception of hypotension and sedation. Hypotension was easily treated by fluids or ephedrine and caused no fetal distress. The level of sedation was mild, and all parturients aroused immediately after verbal commands. Conclusion. The addition of a low dose of clonidine to an epidural injection of bupivacaine with epinephrine and sufentanil provides better analgesia during labor, while keeping the side effects minimal and of minor clinical importance.     

Onset and recovery of neuromuscular blockade after two doses of rocuronium in children

Study Objective: To determine if 450 μg/kg (1.5 times the ED₉₅) of rocuronium would result in a comparable onset with a shorter duration of action when compared with 600 μg/kg (2 times the ED₉₅).

Design: Randomized, single-blind study.

Setting: Teaching hospital.

Patients: 85 ASA physical status I and II children ages 2 through 12, undergoing elective surgery with an inhalation induction using halothane.

Interventions: Group 1 received 600 μg/kg rocuronium, and Group 2 received 450 μg/kg rocuronium.

Measurements and Main Results: The two groups were compared using a Student’s t-test, with p < 0.05 significant. The time of onset, or time to 95% suppression of neuromuscular twitch with standard errors, was 140 ± 13 seconds (range 46 to 365 sec) in Group 1 and 148 ± 13 seconds (range 82 to 345 sec) in Group 2 (NS = not significant). The times to 25% return of twitch from baseline (T₂₅) in Groups 1 and 2 were 28 ± 1.5 minutes (range 14 to 45 min) and 26 ± 1.6 minutes (range 10 to 55 min), respectively (NS). The differences between these two doses in onset of, and recovery from, block were not found to be statistically significant. The results, however, excluded 5% of the higher dose group and 31% of the lower dose group who did not achieve 95% suppression of twitch. Time to maximal suppression of neuromuscular blockade, however, was not statistically significant for the 85 patients with a time of 270 ± 28 seconds (range 91 to 605 sec) with a mean maximal suppression of 98.7% in Group 1 and 313 ± 25 seconds (range 91 to 899 sec) with a mean maximal suppression of 93.1% in Group 2.

Conclusion: The two doses of rocuronium did not differ statistically in onset or duration. Rocuronium at 600 μg/kg offers more reliability than 450 μg/kg in achieving adequate muscle relaxation, and the lower dose may result in a significantly large number of patients who may have inadequate intubating conditions.     

Retransfusion of pericardial blood does not trigger systemic coagulation during cardiopulmonary bypass

Objective: During cardiopulmonary bypass (CPB), systemic coagulation is believed to become activated by blood contact with the extracorporeal circuit and by retransfusion of pericardial blood. To which extent retransfusion activates systemic coagulation, however, is unknown. We investigated to which extent retransfusion of pericardial blood triggers systemic coagulation during CPB. Methods: Thirteen patients undergoing elective coronary artery bypass grafting surgery were included. Pericardial blood was retransfused into nine patients and retained in four patients. Systemic samples were collected before, during and after CPB, and pericardial samples before retransfusion. Levels of prothrombin fragment F₁₊₂ (ELISA), microparticles (flow cytometry) and non-cell bound (soluble) tissue factor (sTF; ELISA) were determined. Results: Compared to systemic blood, pericardial blood contained elevated levels of F₁₊₂, microparticles and sTF. During CPB, systemic levels of F₁₊₂ increased from 0.28 (0.25–0.37; median, interquartile range) to 1.10 (0.49–1.55) nmol/l (p = 0.001). This observed increase was similar to the estimated (calculated) increase (p = 0.424), and differed significantly between retransfused and non-retransfused patients (1.12 nmol/l vs 0.02 nmol/l, p = 0.001). Also, the observed systemic increases of platelet- and erythrocyte-derived microparticles and sTF were in line with predicted increases (p = 0.868, p = 0.778 and p = 0.205, respectively). Before neutralization of heparin, microparticles and other coagulant phospholipids decreased from 464 μg/ml (287–701) to 163 μg/ml (121–389) in retransfused patients (p = 0.001), indicating rapid clearance after retransfusion. Conclusion: Retransfusion of pericardial blood does not activate systemic coagulation under heparinization. The observed increases in systemic levels of F₁₊₂, microparticles and sTF during CPB are explained by dilution of retransfused pericardial blood.     

Ketorolac or fentanyl to supplement local anesthesia?

Study Objective: To evaluate the usefulness of ketorolac in the treatment of intraoperative pain refractory to the administration of local anesthetic alone.

Design: Intraoperative acute-pain treatment model consisting of awake, nonsedated patients who randomly received either an opioid or a study drug in a double-blind fashion.

Setting: University medical center.

Patients: Eighty patients who underwent breast biopsy, lumpectomy, or central venous catheter placement.

Interventions: Patients received either ketorolac 1 mg/kg intravenously (IV) up to a total dose of 60 mg or fentanyl 3 μg/kg IV up to a total dose of 250 μg to supplement the local anesthetic.

Measurements and Main Results: Verbal pain evaluation and the visual analog scale (VAS) were used for perioperative measurement of pain. Heart rate (HR), blood pressure, and respiratory rate (RR) were recorded before and after analgesic drug injections at 10-minute intervals, both intraoperatively and while the patient was in the postanesthesia care unit (PACU). Speed of recovery was quantified by p-deletion and digit substitution tests on admission to the PACU and at 30-minute intervals until discharge. The frequency of nausea, vomiting, and pruritus were recorded. There were no differences between the groups in perioperative verbal pain evaluation, VAS scores, HR, systolic blood pressure, diastolic blood pressure, or RR. Patients who received ketorolac exhibited a significantly lower frequency of intraoperative and postoperative medication administration intraoperatively, than those who received fentanyl. No additional pain medication was required by patients in the PACU in either group.

Conclusions: Ketorolac is a useful alternative to fentanyl for the treatment of intraoperative pain refractory to the administration of local anesthetic alone during monitored anesthesia care. A decided advantage of ketorolac over fentanyl is the absence of nausea and vomiting in the intraoperative and postoperative periods.     

S100β correlates with neurologic complications after aortic operation using circulatory arrest

Background. Astrocyte protein S100β is a potential serum marker for neurologic injury. The goals of this study were to determine whether elevated serum S100β correlates with neurologic complications in patients requiring hypothermic circulatory arrest (HCA) during thoracic aortic repair, and to determine the impact of retrograde cerebral perfusion (RCP) on S100β release in this setting.

Methods. Thirty-nine consecutive patients underwent thoracic aortic repairs during HCA; RCP was used in 25 patients. Serum S100β was measured preoperatively, after cardiopulmonary bypass, and 24 hours postoperatively.

Results. Neurologic complications occurred in 3 patients (8%). These patients had higher postbypass S100β levels (7.17 ± 1.01 μg/L) than those without neurologic complications (3.63 ± 2.31 μg/L, p = 0.013). Patients with S100β levels of 6.0 μg/L or more had a higher incidence of neurologic complications (3 of 7, 43%) compared with those who had levels less than 6.0 μg/L (0 of 30, p = 0.005). Retrograde cerebral perfusion did not affect S100β release.

Conclusions. Serum S100β levels of 6.0 μg/L or higher after HCA correlates with postoperative neurologic complications. Using serum S100β as a marker for brain injury, RCP does not provide improved cerebral protection over HCA alone.