Sugammadex rapidly reverses moderate rocuronium- or vecuronium-induced neuromuscular block during sevoflurane anaesthesia: a dose-response relationship.

BACKGROUND: Sugammadex shows a dose-response relationship for reversal of neuromuscular block (NMB) during propofol anaesthesia. Sevoflurane, unlike propofol, can prolong the effect of neuromuscular blocking agents (NMBAs), increasing recovery time. This open-label, randomized, dose-finding trial explored sugammadex dose-response relationships, safety, and pharmacokinetics when administered for reversal of moderate rocuronium- or vecuronium-induced NMB during sevoflurane maintenance anaesthesia. METHODS: After anaesthesia induction with propofol, adult patients were randomized to receive single-dose rocuronium 0.9 mg kg⁻¹ or vecuronium 0.1 mg kg⁻¹, with maintenance doses as needed. Anaesthesia was maintained with sevoflurane. NMB was monitored using acceleromyography. After the last dose of NMBA, at reappearance of T(2), single-dose sugammadex 0.5, 1.0, 2.0, or 4.0 mg kg⁻¹ or placebo was administered. The primary efficacy variable was time from the start of sugammadex administration to recovery of T4/T1 ratio to 0.9. Safety assessments were performed throughout. RESULTS: The per-protocol population comprised 93 patients (rocuronium, n=46; vecuronium, n=47). A statistically significant dose-response relationship was demonstrated for mean recovery times of T4/T1 ratio to 0.9 with increasing sugammadex dose with both NMBAs: rocuronium, 96.3 min (placebo) to 1.5 min (sugammadex 4.0 mg kg⁻¹); vecuronium, 79.0 min (placebo) to 3.0 min (sugammadex 4.0 mg kg⁻¹). Plasma sugammadex concentrations indicated linear pharmacokinetics, independent of NMBA administered. No study drug-related serious adverse events occurred. Evidence of reoccurrence of block was reported in seven patients [sugammadex 0.5 mg kg⁻¹ (suboptimal dose), n=6; 2.0 mg kg⁻¹, n=1]. CONCLUSIONS: During sevoflurane maintenance anaesthesia, sugammadex provides well-tolerated, effective, dose-dependent reversal of moderate rocuronium- and vecuronium-induced NMB.

[Sugammadex. New pharmacological concept for antagonizing rocuronium and vecuronium]. / Sugammadex. Neues pharmakologisches Konzept zur Antagonisierung von Rocuronium und Vecuronium.

Up to now only acetylcholine esterase inhibitors, such as neostigmine, were available as antagonists of residual neuromuscular blocks. Sugammadex is a modified gamma-cyclodextrin that binds rocuronium and chemically similar aminosteroidal muscle relaxants, such as vecuronium. The underlying mechanism of action is new and differs completely from that of acetylcholine esterase inhibitors. This review summarizes data published so far within the framework of the licensing procedure about the efficacy, safety and side-effects of sugammadex and presents potential new anesthesiological concepts using this compound.

Clinical pharmacokinetics of rocuronium bromide.

A new aminosteroidal neuromuscular blocking agent, rocuronium bromide, has recently been introduced into clinical practice. Its main advantage over other currently used drugs of this kind is its fast onset of action, which could render rocuronium the muscle relaxant of choice for rapid facilitation of tracheal intubation. A further advantage of the new compound over vecuronium bromide is the less extensive formation of breakdown products, reducing the contribution of active metabolites to the neuromuscular blocking effects of the parent compound. Thorough knowledge of the pharmacokinetics of any new drug is highly desirable for the anaesthesiologist because absorption, distribution to the tissue, as well as elimination by biotransformation and excretion, are closely related to its effects. Due to its chemical relationship to other aminosteroidal neuromuscular blocking agents such as pancuronium bromide or vecuronium, rocuronium is expected to display pharmacokinetic behaviour similar to that of its predecessors. Hepatic and renal disease may prolong the effect of rocuronium, but to a lesser extent than seen with pancuronium or vecuronium, because the plasma clearance of rocuronium is not significantly influenced by dysfunction of the liver or kidneys. On the contrary, in elderly or hypothermic patients the reduction in plasma clearance results in a prolonged duration of the action of rocuronium. All information on the pharmacokinetics of this new nondepolarising neuromuscular blocking agent which has been made available to date is presented in this review, with a discussion of the significance of these data for clinical use of the drug.

Newer neuromuscular blocking agents: how do they compare with established agents?

Rapacuronium bromide (rapacuronium; ORG-9487) is a nondepolarising muscle relaxant (NMBA) with a low potency [90% effective dose (ED90) 1 mg/kg], which to some extent is responsible for its rapid onset of action. Because of the high plasma clearance (5.3 to 11.1 mg/kg/min) of rapacuronium, its clinical duration of action following single bolus doses up to 2 mg/kg in adults is short (i.e. <20 minutes). Rapacuronium forms a pharmacologically active 3-desacetyl metabolite, ORG-9488, which may contribute to a delay in spontaneous recovery after repeat bolus doses or infusions. After rapacuronium 1.5 mg/kg clinically acceptable intubating conditions are achieved within 60 to 90 seconds in the majority of adult and elderly patients undergoing elective anaesthesia. However, in a rapid-sequence setting. intubating conditions are less favourable after rapacuronium 1.5 to 2.5 mg/kg than after succinylcholine. The most prominent adverse effects of rapacuronium (tachycardia, hypotension and bronchospasm) are dose-related, and in particular pulmonary adverse effects are observed more frequently under conditions of a rapid-sequence induction in adults. Therefore, it seems worthwhile to consider only doses of rapacuronium < or = 1.5 mg/kg to facilitate rapid tracheal intubation, and to use succinylcholine or rocuronium rather than rapacuronium in a rapid-sequence setting. Rapacuronium, however, is a suitable alternative to mivacurium chloride (mivacurium) and succinylcholine for short procedures (e.g. ambulatory anaesthesia). Rocuronium bromide (rocuronium) is a relatively low-potent, intermediateacting NMBA. Its main advantage is the rapid onset of neuromuscular block whereby good or excellent intubating conditions are achieved within 60 to 90 seconds after rocuronium 0.6 mg/kg (2 x ED95), and within 60 to 180 seconds after smaller doses (1 to 1.5 x ED95). Larger doses of rocuronium (> or = 1 mg/kg) seem to be suitable for rapid-sequence induction under relatively light anaesthesia. However, it is still a matter of controversy whether, in the case of an unanticipated difficult intubation, the long duration of rocuronium administered in such large doses outweighs the many adverse effects of succinylcholine. Rocuronium has mild vagolytic effects and does not release histamine, even when administered in large doses. Rocuronium is primarily eliminated via the liver and its pharmacokinetic profile is similar to that of vecuronium bromide (vecuronium). Unlike vecuronium, rocuronium has no metabolite. Cisatracurium besilate (cisatracurium), the IR-cis, 1'R-cis isomer of atracurium besilate (atracurium) is approximately 4 times more potent than atracurium. The onset time of cisatracurium is significantly slower than after equipotent doses of atracurium. The recommended intubating dose is 0.15 to 0.2 mg/kg (3 to 4 times ED95). Over a wide range of clinically relevant doses the recovery properties of cisatracurium are affected by neither the size of the bolus dose nor by the duration of infusion. Unlike atracurium, cisatracurium does not trigger histamine release. Like atracurium, cisatracurium undergoes Hofmann elimination. In contrast to atracurium, cisatracurium does not undergo hydrolysis by nonspecific plasma esterases. Moreover, about 77% of the drug is cleared by organ-dependent mechanisms.

Factors influencing transcutaneous oxygen and carbon dioxide measurements in adult intensive care patients.

Transcutaneous PO2 (PtcO2) is suggested to reflect tissue oxygenation in intensive care patients, whereas transcutaneous PCO2 (PtcCO2) is advocated as a noninvasive method for assessing PaCO2. In 24 critically ill adult patients (mean Apache II score 14.2, SD 4.7) we investigated the impact of variables that are commonly thought to determine PtcO2 and PtcCO2 measurements. A linear correlation was found between PtcO2 and PaO2 (r = 0.6; p less than or equal to 0.0001) and between PtcO2 and mean arterial blood pressure (MAP; r = 0.42; p less than or equal to 0.003). Cardiac index (CI) correlated with tc-index (PtcO2/PaO2; r = 0.31; p less than or equal to 0.03). There was no relationship between PtcO2 and hemoglobin concentration (Hb) and the position of the oxygen dissociation curve (ODC). Stepwise multiple regression analysis demonstrated a significant influence of PaO2 and MAP on PtcO2. The contribution of CI, Hb and the ODC was not significant. Only 40% of the variability of a single PtcO2 measurement could be explained by PaO2 and MAP. A significant linear correlation was demonstrated between PtcCO2 and PaCO2 (r = 0.76; p less than or equal to 0.0001) but not between PtcCO2 and CI, MAP and arterial base excess (BEa). Stepwise multiple regression analysis revealed an influence of PaCO2 and of CI on PtcCO2; 66% of the variability of a single PtcCO2-value could be explained by PaCO2 and CI. Our data demonstrate that transcutaneous derived gas tensions result from complex interaction between hemodynamic, respiratory and local factors, which can hardly be defined in ICU-patients.

Dopamine and mucosal oxygenation in the porcine jejunum.

The effect of intravenously delivered dopamine on jejunal tissue oxygenation was studied in 12 pigs anesthetized with midazolam and sufentanil and mechanically ventilated. A small segment of the jejunal mucosa and serosa was exposed by midline laparotomy and antimesenteric incision. Mucosal and serosal tissue PO2, mucosal microvascular hemoglobin oxygen saturation, and mucosal hemoglobin concentration were measured by means of Clark-type oxygen electrodes and tissue reflectance spectrophotometry, respectively. In five animals electromyogenic potentials of the jejunal wall were recorded. Measurements were performed under baseline conditions and after intravenous infusion of 2, 4, 8, 16, 32, and again 2 micrograms.kg-1.min-1 of dopamine. The drug produced a dose-related increase in mucosal PO2 (from 26.5 Torr at baseline to 49 Torr at 32 micrograms of dopamine; P < 0.001) and mucosal hemoglobin oxygen saturation (from 55.1 to 70.1%; P < 0.03) but no change in serosal PO2 (from 70.6 to 65.5 Torr). In nine animals baseline mucosal PO2 and mucosal hemoglobin oxygen saturation showed rhythmic oscillations with a frequency of 2.5-5 cycles/min that could not be related to electromyogenic potentials. Dopamine decreased the oscillation amplitude of these two parameters (P < 0.001), and at doses > 16 micrograms.kg-1.min-1 they were no longer present. Dopamine therefore improves mucosal oxygenation of the porcine jejunum in a selective and dose-related manner. At higher doses the preexisting oscillatory pattern of mucosal oxygenation, which is most likely due to vasomotion, is impeded.

Conversion from glipizide to glyburide: long-term follow-up of a cost-impact survey focusing on the elderly.

The appropriate use of second-generation oral hypoglycemic agents is limited by the lack of definitive guidelines for their use in elderly diabetic patients and controversy over relative dosing equivalence. We previously conducted a survey to determine the feasibility and cost of converting diabetic patients from glipizide to glyburide. This new survey provides an extended, 24-month follow-up in 210 patients and focuses on findings in elderly patients. The mean final daily dose of glyburide (11.6 mg) was lower than the preconversion dose of glipizide (18.7 mg) (P < or = 0.0001). One hundred forty-one (67%) patients successfully continued glyburide for 24 months, including 103 (73%) patients who were 65 years of age or older. There was no apparent correlation between age and final dose of glyburide, ability to continue glyburide, or risk of stopping glyburide. The conversion program reduced the mean daily dose after switching from glipizide to glyburide, which was preserved throughout the observation period. The program also conferred a 49% savings in the projected 2-year expenditures for second-generation oral hypoglycemic agents.

Conversion from glipizide to glyburide: a prospective cost-impact survey.

Despite extensive clinical experience with second-generation oral hypoglycemic agents, the relative dosing equivalence of glyburide and glipizide remains controversial. A prospective survey was conducted to determine the feasibility and cost of converting noninsulin-dependent diabetic patients from glipizide to glyburide. A total of 211 patients previously stabilized on glipizide were converted to glyburide and returned to their respective clinics at least once during the following six months. The mean daily dose (+/- SD) of glipizide before conversion was 18.7 +/- 12.32 mg; the mean daily dose of glyburide after seven months was 9.9 +/- 6.52 mg (P less than 0.001, paired t test). Glyburide was well tolerated. The conversion program appeared to be successful and resulted in a 47% reduction in the mean daily dose after conversion from glipizide to glyburide, which, in turn, conferred a 43% savings in the projected yearly expenditures for second-generation oral hypoglycemics.

Employing vasopressin as an adjunct vasopressor in uncontrolled traumatic hemorrhagic shock. Three cases and a brief analysis of the literature.

Resuscitation of patients in hemorrhagic shock remains one of the most challenging aspects of trauma care. We showed in experimental studies that vasopressin, but not fluid resuscitation, enabled short-term and long-term survival in a porcine model of uncontrolled hemorrhagic shock after penetrating liver trauma. In this case report, we present two cases with temporarily successful cardiopulmonary resuscitation (CPR) using vasopressin and catecholamines in uncontrolled hemorrhagic shock with subsequent cardiac arrest that was refractory to catecholamines and fluid replacement. In a third patient, an infusion of vasopressin was started before cardiac arrest occurred; in this case, we were able to stabilize blood pressure thus allowing further therapy. The patient underwent multiple surgical procedures, developed multi-organ failure, but was finally discharged from the critical care unit without neurological damage.

Choice of the muscle relaxant for rapid-sequence induction.

Muscle relaxants are given as part of a rapid-sequence induction to facilitate tracheal intubation. Among all the muscle relaxants available, succinylcholine is the only one with a fast (approximately equal to 1 min) onset and a fast recovery. Therefore it is still the most frequently used muscle relaxant for rapid-sequence induction despite its well-known side-effects. The short duration of action of succinylcholine is, however, no substitute for aggressive airway management in the case of an unexpectedly difficult intubation in order to prevent life-threatening hypoxia. A preoperative assessment of the airway is mandatory in any patient and may indicate the need for using intubation techniques without a muscle relaxant. Rocuronium in large doses (i.e. > or = 1 mg kg-1) is an alternative to succinylcholine in a classical rapid-sequence setting under relatively light anaesthesia. With respect to rapid tracheal intubation, the timing and priming principles offer little advantage over the use of rocuronium in doses of 0.6 mg kg-1 in combination with an appropriate induction technique (i.e. including an opioid) or over the use of larger doses of rocuronium (> or = 1.0 mg kg-1) under relatively light anaesthesia, and may even be potentially harmful. In contrast to rocuronium, the use of rapacuronium in a rapid-sequence setting has been associated with dose-dependent respiratory side-effects that limit its usefulness in doses higher than 1.5 mg kg-1 for this indication.

[Succinylcholine--update]. / Succinylcholin-Update.

The action profile of succinylcholine is unmatched even 50 years after its introduction into anaesthestic practice. This is probably why succinylcholine, despite its many and partly life-threatening side-effects, is still considered to be indispensable by many anaesthetists and emergency doctors. The main indication for succinylcholine--the facilitation of endotracheal intubation in patients considered to be at an increased risk of aspiration of gastric fluid, e.g. patients undergoing a Caesarean section or presenting with an ileus--remains undisputed. Some of the side-effects of succinylcholine can be diminished by precurarisation. However, just like priming, this technique holds some considerable dangers (such as a clinically significant attenuation of the protective reflexes) and has become a matter of increasing controversy. Rocuronium (> or = 1 mg/kg) is currently the best alternative to succinylcholine for rapid sequence induction. The routine use of succinylcholine as a relaxant for intubation is questionable, mainly because there are a number of modern anaesthetic techniques (laryngeal mask airway) and new drugs (rocuronium, mivacurium, remifentanil) which make succinylcholine quite dispensable except for a few situations (e.g. re-positioning of fractures). In the case of an expected difficult airway no muscle relaxant should be given, because severe hypoxaemia in these patients probably can only be prevented by a professional airway management. Succinylcholine is no longer an option in elective paediatric anaesthesia. The drug, however, retains its value in critical situations where a rapid onset but a short duration of action is of prime importance.

[High altitude pulmonary edema at a medium height. A case report]. / Das Höhenlungenödem in mittlerer Höhe. Ein Fallbericht.

A 45-year-old, healthy, well-trained man climbed within 12 hours from 300 m above sea level to a shelter at 2500 m in the Tyrolean Alps. During the following 3 days he undertook ski tours to the surrounding mountains up to 3356 m. On the 4th day he suddenly suffered from headache, coughing and very severe dyspnoea even at rest, accompanied by loss of appetite and the feeling of suffocation. The following day he was rescued by a helicopter and taken to hospital. At the time of admission the patient was severely hypoxaemic (capillary PO2 = 25.7 mmHg), and the chest X-ray revealed signs of bilateral alveolar pulmonary edema localised predominantly in the right lung. High-altitude pulmonary edema (HAPE) was diagnosed because of the typical clinical course. Pulmonary gas exchange normalised within hours, and complete restitution was achieved within 2 days. The chest X-ray was normal on the 4th day after admission. HAPE is a non-cardiogenic pulmonary edema which develops in healthy individuals usually above 3000 m. Among the predisposing factors are rapid ascent, severe physical effort, diminished hypoxic ventilatory response and abnormal fluid balance. The treatment of choice is descent to a lower altitude, administration of oxygen and of nifedipine and expiratory positive airway pressure.

Laryngeal mask lubrication. A comparative study of saline versus 2% lignocaine gel with cuff pressure control.

We compared 2% lignocaine gel with saline as a lubricant for the laryngeal mask airway in 126 patients receiving positive pressure ventilation in whom cuff pressures were limited to 60 cmH2O and peak airway pressures to less than 17 cmH2O. The incidence of sore throat was similar for both groups and there were no emergence problems. There were significantly more intra- and postoperative complications in the lignocaine group (p < 0.05) but the frequency of sore throat was similar when the device was inserted at the first attempt. Positive pressure ventilation to normal end-tidal CO2 values was possible in all patients. Lignocaine gel is an unsuitable lubricant for the laryngeal mask airway. Cuff pressure limitation to 60 cmH2O does not necessarily impede ventilation and may be an important factor in reducing emergence and postoperative complications.

Laryngeal mask bite blocks--rolled gauze versus Guedel airway.

BACKGROUND: Biting on the silicone tube and pilot balloon of the laryngeal mask airway (LMA) may obstruct or damage them with the teeth and a bite block is recommended. The recommended bite block is a wad of gauze swabs rolled into a cylindrical shape and placed alongside the LMA. It is considered that this avoids irritating the posterior pharyngeal wall and damage to teeth whilst supporting the LMA tube when taped to it. The Guedel airway is commonly used as a bite block with the tracheal tube and many anaesthetists also use it with the LMA. The aim of the following study was to compare rolled gauze swabs with a Guedel airway as a bite block for the LMA. METHODS: We compared the Guedel airway with rolled gauze swabs as a bite block for the laryngeal mask airway (LMA) in 120 ventilated patients in whom cuff pressures were limited to 5.87 kPa (60 cm H2O) and anaesthesia management was standardised. RESULTS: In the Guedel airway group, there was a higher incidence of ventilatory problems (0 vs 4, P < 0.05), bleeding (0 vs 8, P < 0.01), hoarseness (0 vs 4, P < 0.05) and sore throat (2 vs 12, P < 0.01). CONCLUSION: 1. The Guedel airway is an unsuitable bite block for the LMA. 2. Cuff pressure limitation is compatible with adequate ventilation. 3. The combination of LMA and Guedel airway probably prevents either from sitting in the correct anatomical position.

Positive pressure ventilation with the laryngeal mask airway in non-paralysed patients: comparison of sevoflurane and propofol maintenance techniques.

We have compared anaesthetic maintenance and emergence characteristics of propofol and sevoflurane with the laryngeal mask airway (LMA) at commonly used doses in 185 ASA I-II patients, in a randomized, prospective study. Anaesthesia was induced with propofol 2.5-3.5 mg kg-1 and fentanyl 1-3 micrograms kg-1. Neuromuscular blocking agents were not used. All patients underwent positive pressure ventilation (PPV) with tidal volumes of 6-8 ml kg-1 to maintain normal end-tidal carbon dioxide concentration. Anaesthesia was maintained with 66% nitrous oxide in oxygen and infusion of propofol 6 or 8 mg kg-1 h-1, or 1% or 1.5% end-tidal sevoflurane. There were no failed insertion attempts and adequate ventilation was achieved in all patients. During emergence, there was a greater incidence of excitatory phenomena with 1% and 1.5% sevoflurane (95% confidence intervals (CI) 4-19%) compared with propofol (95% CI 0-4%). Sevoflurane 1.0% (95% CI 37-71%) was associated with the greatest overall incidence of respiratory and haemodynamic problems. This was significantly higher compared with propofol 6 mg kg-1 h-1 (95% CI 19-36%). Shorter times to LMA removal were observed with 1% and 1.5% sevoflurane compared with propofol (P < 0.0002). Postoperative problems did not differ between groups. We conclude that propofol 6-8 mg kg-1 h-1 and 1.5% sevoflurane were suitable for maintenance of anaesthesia for musculoskeletal surgery in non-paralysed ASA I-II patients undergoing PPV with the LMA. Emergence was more rapid with sevoflurane, but was associated with more excitatory phenomena.

Thiopental or etomidate for rapid sequence induction with rocuronium.

We have assessed the effect of the choice of i.v. induction agent on intubation conditions, 60 s after administration of rocuronium 0.6 mg kg-1. We studied 60 adult patients, allocated randomly to one of two groups. Anaesthesia was induced with alfentanil 10 micrograms kg-1 followed by thiopental 5 mg kg-1 (AT-R group; n = 30) or etomidate 0.3 mg kg-1 (AE-R group; n = 30). Both groups received rocuronium 0.6 mg kg-1. Laryngoscopy was started 60 s later and intubation conditions were evaluated according to a standard score, which considered ease of laryngoscopy, condition of the vocal cords and reaction to intubation. In the AT-R group, overall intubation conditions were scored as excellent in 20 patients, good in nine and fair in the remaining patient. In the AE-R group, overall intubating conditions were excellent in 24 and good in six patients. The difference between the two groups was not significant. Of the three components of the intubation score assessed, response to intubation stimulus was significantly less pronounced in group AE-R compared with group AT-R (P < 0.05): group AE-R, no reaction in 24 patients, slight diaphragmatic movement in five and mild coughing in one patient; group AT-R, no reaction in 13, slight diaphragmatic movement in 14, mild coughing in two and severe coughing in one patient. We conclude that etomidate as part of an induction regimen containing alfentanil and rocuronium attenuated the reaction to intubation to a greater extent than thiopental.

Pharmacodynamics and pharmacokinetics of rocuronium following continuous infusion in patients during intravenous anaesthesia.

After an initial bolus dose (0.6 mg kg-1), 10 patients received a continuous infusion of rocuronium, initially at 0.5 mg kg-1h-1, and then adjusted to maintain 90% twitch depression. Blood samples were analysed for 420 min after switching off the infusion. The dose required to maintain the block was 595 +/- 146 micrograms kg-1h-1, 7-9 times that reported for vecuronium under similar conditions. The pharmacokinetic parameters (volume of distribution at steady state, 309 +/- 80 ml kg-1, plasma clearance 4.5 +/- 1.96 ml kg-1 min-1, and elimination half-life 107 +/- 37 min) were similar to those previously reported after a large single bolus.

[The use of a transcutaneous pO2/pCO2 combination electrode during volume therapy in a child in shock]. / Die Verwendung einer transkutanen pO2/pCO2-Kombielektrode während der Volumentherapie bei einem schockierten Kleinkind.

We report a 1-year-old boy in hemorrhagic shock due to a large subgaleatic hematoma following severe head trauma (blood pressure (BP) 30/15 mmHg; heart rate (HR) 110; Hb 45 g/l; arterial pH 7.16; BE-20 mEq/l). The child was intubated and ventilated; initial FIO2 was 0.9. In an attempt to monitor the cardiovascular system noninvasively a transcutaneous oxygen/carbon dioxide combielectrode was placed on the chest. Initially we observed a large difference between arterial pO2 (paO2 = 166 mmHg) and transcutaneous pO2 (tcpO2 = 7 mmHg) and arterial pCO2 (paCO2 = 16 mmHg) and transcutaneous pCO2 (tcpCO2 = 55 mmHg), reflecting poor skin perfusion and severe tissue acidosis. Under aggressive volume replacement tcpO2 rose along with BP and tcpCO2 returned to near arterial values. Even after stabilization of gross hemodynamic parameters such as HR and BP and despite reductions in FIO2, tcpO2 continued to increase with further volume replacement, reflecting an existing volume deficit.

Comparison of ropivacaine 0.1% and 0.2% with bupivacaine 0.2% for single-shot caudal anaesthesia in children.

We compared analgesic efficacy and degree of motor block induced by ropivacaine 0.1% (R 0.1) and 0.2% (R 0.2) vs. bupivacaine 0.2% (B 0. 2) after caudal anaesthesia in children. Total and free plasma concentrations were measured after caudal injection. Duration of caudal analgesia (median/range) was significantly shorter in group R 0.1 (1.7 h/0.2-6 h) than in group R 0.2 (4.5 h/1.7-6 h) or group B 0. 2 (4 h/1-6 h) (P<0.05). Motor block in the first 2 h postoperatively was significantly less for both ropivacaine groups compared with bupivacaine (P<0.05). Peak plasma concentrations after ropivacaine 0.2% were higher and protein binding lower than after bupivacaine 0.2% (P<0.05). We conclude that caudal analgesia with ropivacaine 0.1% is less effective and of shorter duration than that of ropivacaine 0.2%, whereas ropivacaine 0.2% provides pain relief similar to bupivacaine 0.2%. Motor block in the early postoperative period is less with ropivacaine than with bupivacaine.