A paravenous approach for the saphenous nerve block.

BACKGROUND AND OBJECTIVES: This study assesses a paravenous approach for saphenous nerve block at approximately the level of the tibial tuberosity, and compares it with the conventional technique of blind subcutaneous infiltration between the tibial tuberosity and the gastrocnemius muscle. METHODS: In dissections of 5 cadavers, the saphenous nerve was found very close to the saphenous vein bilaterally. Subsequently, in 20 volunteers, a bilateral saphenous nerve block was performed with 5 mL mepivacaine on each side. Randomly assigned, the block was performed by blind subcutaneous injection using a 23-gauge needle of 2.5 cm on one side and by a paravenous subcutaneous approach on the other. RESULTS: The paravenous approach produced a saphenous nerve block in all 20 volunteers whereas the blind subcutaneous approach was successful in only 6 (33%) (P <.05). Seven volunteers had a painless minor hematoma at the paravenous site and 2 had a hematoma at the classical site. CONCLUSION: The saphenous nerve can be blocked effectively by a paravenous approach using only 5 mL of local anesthetic solution. This approach is advantageous because of its easily identifiable landmark.

Doxacurium block is not influenced by age.

STUDY OBJECTIVE: To determine the influence of aging on the efficacy and safety of doxacurium. DESIGN: Open, randomized, phase III study. SETTING: Inpatient ophthalmic surgery clinic at a university medical center. PATIENTS: 30 elderly patients (65 years or older) compared with a control group of 30 younger patients (18 to 64 years). INTERVENTIONS: An elective ophthalmological surgical intervention of more than 2 hours' expected duration with general anesthesia with isoflurane. MEASUREMENTS AND MAIN RESULTS: Neuromuscular function after a bolus dose of doxacurium was monitored electromyographically. No significant difference was observed in maximum block achieved or onset time. Clinical duration of neuromuscular block was similar in both groups. Hemodynamic changes were clinically unimportant. CONCLUSION: The use of doxacurium in elderly patients is possible with no need for dose adjustment. Doxacurium might be a good choice for patients with cardiac disease who are scheduled for long surgical procedures.

Transition time: a new parameter coinciding with fair intubating conditions.

With rocuronium optimal intubating conditions are earlier achieved than the adductor pollicis muscle onset time. Using the transition time we defined a better parameter for clinical relaxation. The onset of relaxation was determined in 20 patients. After a stable response was achieved with a 0.1 Hz single twitch stimulation 0.60 mg/kg rocuronium was injected. The three different stades during the onset of relaxation were determined. These are the lag time, transition time (transition between second and third phase) and onset time. Whether the transiton time corresponds with optimal intubating conditions was evaluated in 40 other patients. The median transition time was 67.4 (P25:52.5, P75:76.3) seconds with a corresponding relaxation of 76.2 (P25:81.4, P75:70.7)%. The intubating conditions were significantly better at a relaxation level corresponding with the transition time. We conclude that the transition time approximates the intubating time and corresponds with fair intubating conditions. This parameter can be preferred to define the moment with optimal intubating conditions.

[Postoperative analgesia following surgical correction of hypospadias]. / Analgésie post-opératoire après une opération de l'hypospadias.

The authors describe the different forms of postoperative pain therapy which can be applied after a surgical repair of hypospadias. Hereby we chose for the caudal analgesia. It is effective, easy to perform and is seldom associated with complications. An overview is given of the technique, the points for attention and the different products which can be injected. Systemic analgesia and penile nerve blockade are often less effective and should only be applied in case caudal analgesia can not be administered.

Evaluation of the onset and intubation conditions of rocuronium bromide.

Rocuronium 0.6, 0.75, or 0.9 mg kg-1, was given after supramaximal train-of-four stimulation of the ulnar nerve, measuring the compound action potential of the hypothenar muscles, Intubation conditions, onset time, recovery to 25% and recovery index of the three doses of rocuronium bromide were determined in 60 ASA I or II consenting patients, who were receiving propofol, alfentanil and N2O/O2 for ophthalmic surgery. Intubation conditions were randomly assessed either 45 s or 60 s after injection. In general, intubation conditions were excellent or good; in only three patients were poor conditions obtained, always at 45 s. For total intubation score a borderline difference was found in favour of the 60 s subgroups. No difference could be shown between the three dose groups. The onset time was longer (P < 0.01) in the 0.6 mg kg-1 group, compared to that in the 0.9 mg kg-1 group. The recovery to 25% and spontaneous recovery index were shorter in the 0.6 mg kg-1 group (P < 0.01).

The influence of sufentanil and/or clonidine on the duration of analgesia after a caudal block for hypospadias repair surgery in children.

The aim of this study was to evaluate whether the addition of clonidine, or sufentanil, or both, to a bupivacaine solution for a caudal block prolonged the period of analgesia after operation in children. Sixty ASA class I or II boys, aged between 8 months and 13 years, admitted for hypospadias repair were enrolled into a prospective randomised study. After induction of general anaesthesia and endotracheal intubation the children were allocated into four groups. Group I received 0.5 mL kg(-1) bupivacaine 0.25% caudally, in addition group II received 1 microg kg(-1) clonidine, group III 0.5 microg kg(-1) sufentanil and group IV 0.5 microg kg(-1) clonidine and 0.25 microg kg(-1) sufentanil. The concentrations of clonidine and sufentanil in group IV were halved to reduce possible side-effects with higher dosages. Analgesia and side-effects were assessed 2, 4, 6, 8 and 12 h after operation. No significant differences were found among the four groups for the pain scores at 2, 4, 6, 8 and 12 h. All groups had a similar frequency of vomiting and a comparable appetite and quality of night rest during the first 24 h following the operation. There was no significant difference in the requirement for additional doses of analgesics. The addition of sufentanil, or clonidine, or both, to bupivacaine for caudal administration provides no additional clinical benefit over bupivacaine alone.

The influence of isoflurane on a continuous infusion of mivacurium.

Sixty surgical patients were studied to evaluate the neuromuscular effects of mivacurium 0.15 mg.kg-1 (2 x ED95) for tracheal intubation. After intubation the patients were randomly allocated to receive alfentanil with either propofol (starting with 9 mg.kg-1 h-1, reducing to 6 mg.kg-1 h-1 after 20 min) or isoflurane (0.5% end-tidal). In addition, all the patients were given a continuous infusion of mivacurium 10 micrograms.kg-1 min-1 after tracheal intubation which was adjusted to maintain 90% depression of T1. Following mivacurium 0.15 mg.kg-1 T1 decreased below 25% in all but four patients. Mean (SD) percentage maximum block attained was 92.9% (12.5) after 309 (89)s. Tracheal intubation was completed 232 (155) s after administration of the relaxant and intubating conditions were graded as 'excellent' or 'good' in 56 patients. Although the mean (SD) mivacurium infusion rate for maintaining T1 at 10% was higher in the propofol group, 4.8 (2.1) compared with 4.4 (2.0) micrograms.kg-1 min-1 in the isoflurane group, this was not significantly different (p > 0.05). The mean (SD) recovery index was prolonged in the isoflurane patients, 757 (508)s, compared to those receiving propofol, 466 (219)s (p < 0.05).

The onset of neuromuscular block at the masseter muscle as a predictor of optimal intubating conditions with rocuronium.

After an intubating dose of rocuronium satisfactory intubating conditions are achieved before the onset time at the adductor pollicis. We examined the possibility that measurement of the relaxation of the masseter muscle is a more appropriate guide when determining the intubating time. Simultaneous accelerometry with a 0.1-Hz single twitch stimulation of the chin and thumb was performed in 20 patients after 0.6 mg kg-1 rocuronium. We observed a significantly more brief mean lag time and onset time at the masseter muscle (22.5 and 61 vs. 32.5 and 160 s). The corresponding mean relaxation at the onset time was also significantly more pronounced at the masseter muscle (99.6 vs. 97.6%). A mean onset time at the masseter muscle of 61 s as produced by rocuronium corresponds clinically with excellent or good intubating conditions. From these results, we suggest that measurement of the onset time of muscle relaxation at the masseter muscle appears to be a better predictor of good intubating conditions than measurements made using the adductor pollicis muscle after administration of rocuronium.

Postoperative residual curarization with cisatracurium and rocuronium infusions.

BACKGROUND AND OBJECTIVE: Monitoring of neuromuscular blockade still often relies on clinical judgement. Moreover, there are substantial national differences in the use of agents to 'reverse' their effects. We investigated the recovery characteristics and incidence of postoperative residual curarization after cisatracurium and rocuronium infusions for long duration interventions without systematic antagonism. METHODS: In 30 patients undergoing major surgery, we measured infusion dose requirements for rocuronium and cisatracurium during propofol anaesthesia. Infusions were discontinued at the beginning of surgical closure; spontaneous recovery of neuromuscular function was awaited in both groups. Neostigmine (50 microg kg(-1)) was administered only when a patient started to wake without a train-of-four ratio (TOF) of 0.9. RESULTS: In the cisatracurium and rocuronium groups, four (27%) and one (7%) patients, respectively, had a TOF ratio > or = 0.9 at the end of surgery. The TOF ratio in each group at that time was 51 +/- 32% for cisatracurium and 47 +/- 31% for rocuronium (P = 0.78). Six patients (40%) in the cisatracurium group and seven (47%) in the rocuronium group required neostigmine. The TOF ratio at the time of reversal was 63 +/- 7% for cisatracurium and 40 +/- 19% for rocuronium (P = 0.01). The time interval between the end of surgery and a TOF ratio of 0.9 was 10 +/- 9 min for cisatracurium and 18 +/- 13 min for rocuronium (P = n.s.). CONCLUSIONS: Patients receiving a cisatracurium or rocuronium infusion have a high incidence of postoperative residual curarization when the block is not antagonized. When 'reversal' is not attempted, cisatracurium seems to be safer than rocuronium.

Comparison of spontaneous frontal EMG, EEG power spectrum and bispectral index to monitor propofol drug effect and emergence.

BACKGROUND: The aim of this study was to investigate the accuracy of frontal spontaneous electromyography (SEMG) and EEG spectral edge frequency (SEF 95%), median frequency (MF), relative delta power (RDELTA) and bispectral index (BIS) in monitoring loss of and return of consciousness and hypnotic drug effect during propofol administration at different calculated plasma target concentrations. METHODS: Propofol was administered by using a target-controlled infusion at different propofol steady-state concentrations. All variables were measured simultaneously at specific calculated concentrations and endpoints. RESULTS: Loss of consciousness was accurately monitored by BIS, SEMG and SEF 95%, and propofol drug effect by BIS only. Return of consciousness was predicted by BIS, MF and SEF 95%. Due to the biphasic EEG pattern of propofol and the lack of reproducible data at specific propofol concentrations, the clinical usefulness of SEF 95%, MF and RDELTA was very limited. SEMG was useful to detect loss and return of consciousness, but without predictive value. CONCLUSIONS: The BIS might be an accurate measure to monitor depth of anaesthesia and hypnotic drug effect. Other neurophysiologic measures have limited value to monitor depth of anaesthesia and hypnotic drug effect.