Eric Wodey

Premedication in children: hypnosis versus midazolam

Background:  The main objectives of premedication in children are to facilitate the separation from the parents, to reduce preoperative anxiety, to smooth the induction of anesthesia and to lower the risk of postoperative behavioral disorders. The most common technique is sedative premedication with midazolam. Hypnosis enables a state of relaxation to be achieved and has never been evaluated as a premedication technique. The aim of the present study was to evaluate the efficacy of hypnosis on anxiety and perioperative behavioral disorders versus midazolam.

Effect of remifentanil with and without atropine on heart rate variability and RR interval in children.

Remifentanil can cause bradycardia either by parasympathetic activation or by other negative chronotropic effects. The high frequency (HF) component of heart rate variability (HRV) is a marker of parasympathetic activity. This study aimed to evaluate the effect of remifentanil on RR interval and on HRV in children. Forty children ASA I or II were studied after approval by the human studies committee and informed parental consent was obtained. After stabilisation at sevoflurane 1 MAC, they were randomly divided into two groups: one received a 20 μg.kg−1 atropine injection (AT + REMI) and the other ringer lactate solution (REMI). Three minutes later, a 1 μg.kg−1 bolus of remifentanil was administered over 1 min, followed by a continual infusion at 0.25 μg.kg−1.min−1 for 10 min increased to 0.5 μg.kg−1.min−1 for a further 10 min. A time varying, autoregressive analysis of RR sequences was used to estimate classical spectral parameters: low (0.04–0.15 Hz; LF) and high (0.15–0.45 Hz; HF) frequency, whereas the root mean square of successive differences of RR intervals (rmssd) was derived directly from the temporal sequence. Statistical analyses were conducted by means of the multiple correspondence analysis and with non parametrical tests. Remifentanil induced an RR interval lengthening, i.e. bradycardia, in both groups compared to pretreatment values and was associated with an increase of HF and rmssd only for the REMI group. The parasympathetic inhibition by atropine did not totally prevent remifentanils negative chronotropic effect. A direct negative chronotropic effect of remifentanil is proposed.

Axillary block in children: single or multiple injection?

The goal of this double‐blind prospective study was to compare the effect of a single injection versus multiple fractionated doses on the onset time and quality of motor and sensory block, obtained in 70 children anaesthetized with axillary block alone. The brachial plexus was identified with a peripheral nerve stimulator, and blocked with 0.5 ml·kg−1 of 1.5% lignocaine with adrenaline. In Group S (single injection), the total volume was injected after location of one nerve. In Group M (multiple fractionated doses), two nerves were located, including necessarily one nerve implicated in the surgical territory. Motor and sensory blocks were assessed according to Lanzs scale before surgery by a blinded observer. A block was considered complete if there was no feeling in at least three nerve territories at 30 min. No difference was found between groups for motor and sensory block quality. However the onset time of the block was faster after multiple fractionated doses (Group M, 25±7 min vs Group S, 29±4 min) and was faster in younger children (5–9 years: M=23±7 min vs S=28±5 min, 10–15 years: no difference). There was a significant difference in the quality of the sensory blockade of the musculocutaneous nerve: 18 versus 8 complete blocks, 10 versus 14 incomplete blocks, respectively for Group M versus Group S. No adverse effect was observed and analgesia was prolonged for more than 4 h. We can conclude that, unlike adults, fractionated doses in chilren bring no benefit to the quality of sensory and motor block. Selective block of the musculocutaneous nerve is recommended when a surgical procedure takes place in this territory.

Capillary refilling time and hemodynamics in neonates: a Doppler echocardiographic evaluation.

OBJECTIVE To evaluate the correlation of the capillary refilling time measured in neonates with the hemodynamic parameters obtained by Doppler echocardiography. DESIGN Prospective study. SETTING Neonatal intensive care unit (ICU) in a university hospital. PATIENTS Neonates without congenital cardiac disease admitted to the neonatal ICU (n = 100). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The clinical parameters obtained were: heart rate; blood pressure; mean airway pressure; cutaneous temperature; and capillary refilling time. The echocardiographic data included the measurement of aortic diameter, left atrial diameter, and shortening fraction. Pulsed-Doppler echocardiography was used to measure flow velocity values in the ascending aorta, in the pulmonary artery trunk, and in the patent ductus arteriosus. Cardiac index was calculated secondarily from the volumetric equation, including measured flow velocity in the ascending aorta, aortic diameter, and body weight. Shunt severity at this level was measured by analysis of the descending aortic flow. Thereafter, three groups were defined for analysis: group 1 with obliterated ductus arteriosus; group 2 with patent ductus arteriosus without a retrograde flow in the subdiaphragmatic aorta; and group 3 with patent ductus arteriosus and a retrograde flow in the subdiaphragmatic aorta. There was no correlation between the capillary refilling time and the following parameters: shortening fraction; mean airway pressure; body weight; left atrial diameter/ aortic diameter ratio; blood pressure; and heart rate. In group 1, the capillary refilling time was significantly linked to cardiac index (r2 = .54, p < .001). A lower correlation coefficient between capillary refilling time and cardiac index was found in groups 2 (r2 =.31, p < .001) and 3 (r2 =.41, p < .001). CONCLUSION The capillary refilling time was significantly linked to cardiac index in neonates.

The relationship between expired concentration of sevoflurane and sympathovagal tone in children.

In children, sevoflurane depresses parasympathetic tone during induction more than halothane. The effects of sevoflurane on parasympathetic activity could explain the difference in heart rate (HR) changes described between infants and children. In this study, we sought to determine the relationship between the end-tidal concentration of sevoflurane and sympathetic and parasympathetic tone in children by spectral analysis of RR intervals. Thirty-three children, ASA physical status I, who required elective surgery were studied. In 10 children (Group A), recordings were performed while gradually decreasing the inspired sevoflurane concentration from 8% to the beginning of clinical awakening. In 23 other children (Group B), recordings were performed while children were awake and at a steady-state of 1 and 2 minimum alveolar anesthetic concentration of sevoflurane. A time-varying autoregressive modeling of the interpolated RR sequences was performed, and spectral density in low-frequency (LF; 0.04–0.15 Hz) and high-frequency (HF; 0.15–0.55 Hz) bands was calculated. In Group A, HR slowing paralleled the decrease in expired sevoflurane concentration. Conversely, the decrease in expired concentration of sevoflurane led to an increase in systolic blood pressure (SBP), HF, LF, and LF/HF. The increase in LF/HF preceded the increase in HF. In Group B, the baseline HF power spectrum and normalized values HFnu (HFnu = HF/LF + HF) were significantly increased in children older than 3 yr. Changes in HR induced by sevoflurane were negatively correlated with baseline HF and HFnu (R2 = 0.6; P < 0.001). These results demonstrate that withdrawal of parasympathetic tone is the main determinant for the change in HR induced by sevoflurane.

Hypnosis and Dental Anesthesia in Children: A Prospective Controlled Study

Abstract The authors of this prospective study initially hypothesized that hypnosis would lower the anxiety and pain associated with dental anesthesia. Thirty children aged 5 to 12 were randomly assigned to 2 groups receiving hypnosis (H) or not (NH) at the time of anesthesia. Anxiety was assessed at inclusion in the study, initial consultation, installation in the dentists chair, and at the time of anesthesia using the modified Yale preoperative anxiety scale (mYPAS). Following anesthesia, a visual analogue scale (VAS) and a modified objective pain score (mOPS) were used to assess the pain experienced. The median mYPAS and mOPS scores were significantly lower in the H group than in the NH group. Significantly more children in the H group had no or mild pain. This study suggests that hypnosis may be effective in reducing anxiety and pain in children receiving dental anesthesia.

Epidural, intrathecal pharmacokinetics, and intrathecal bioavailability of ropivacaine

BACKGROUND:Ropivacaine is used by the epidural route for postoperative pain management with various neuraxial techniques. Given the widespread use of these techniques and the relative paucity of data on spinal disposition of local anesthetics, we evaluated through an experimental animal model, the spinal disposition of ropivacaine, allowing further studies of factors influencing their intrathecal bioavailability. METHODS:Sheep received an IV bolus dose of ropivacaine (50 mg), and 1 wk after, an intrathecal dose of ropivacaine (20 mg) followed 3 h later by epidural ropivacaine (100 mg). A simultaneous microdialysis technique was used to measure epidural and intrathecal drug concentrations after both epidural and intrathecal administrations. RESULTS:Absorption-time plots showed a large variability in the systemic absorption after both intrathecal and epidural administration, with an apparent faster systemic absorption after intrathecal administration. In the intrathecal space, the elimination clearance was around three-times higher than the distribution clearance. In the epidural space, the relative contribution of elimination and distribution to ropivacaine disposition was different, indicating a more pronounced influence of the distribution process. The intrathecal bioavailability after epidural administration was 11.1% ± 7.6%. CONCLUSIONS:Using an animal model, we showed that drug dispositions in the intrathecal and epidural compartments are different, and that the intrathecal bioavailability of ropivacaine after epidural administration is low, and highly variable.

Accuracy and limitations of continuous oesophageal aortic blood flow measurement during general anaesthesia for children: comparison with transcutaneous echography-Doppler

Background: Because it is noninvasive and easy to use, oesophageal Doppler ultrasonography appears to be a worthwhile alternative for continuous assessment of cardiac output measurement during anaesthesia. A new oesophageal Doppler‐echography device (Dynemo 3000™, Sometec, Paris, France) can simultaneously determine aortic diameter and aortic blood flow at the same anatomical level (DEeso). The purpose of this study was to assess the accuracy and the potential limitations of this device during general anaesthesia among 20 children, using transcutaneous Doppler‐echocardiography for comparison (DEtra).

Evaluation of the pediatric post anesthesia discharge scoring system in an ambulatory surgery unit

To optimize the care pathway for children scheduled for ambulatory surgery, a pediatric postanesthetic discharge scoring system (Ped‐PADSS) was developed from a score used in adults. The objective of this study was to evaluate this score prospectively on a cohort of children who had a day case surgical procedure.

Electrocardiographic and hemodynamic effects of intravenous infusion of bupivacaine, ropivacaine, levobupivacaine, and lidocaine in anesthetized ewes.

Background and Objectives: Neural blockade techniques are associated with a risk of acute cardiac toxicity after accidental intravenous (IV) injection of local anesthetics. The aim of this study was to compare electrocardiographic (ECG) and hemodynamic (HEM) effects induced by IV infusion of local anesthetics in an anesthetized ewe model. Methods: Thirty-two anesthetized ewes received IV bupivacaine (BUPI), ropivacaine (ROPI), or levobupivacaine (S-BUPI) at an equimolar dose, or lidocaine (LIDO) at a 3-fold higher rate (n = 8 in each group). RR, PR, QRS, and QT intervals (QTc), changes (&Dgr;) in systolic and diastolic arterial pressure (SAP and DAP), and in myocardial contractility (dP/dt), were assessed every 30 seconds for 7 minutes. From main ECG variables (RR, PR, QRS, QT), we proposed to use multiple correspondence analysis and hierarchical ascending classification to explore the structure of statistical dependencies among those measurements, and to determine the different patterns of ECG and HEM changes induced by infusion of BUPI, ROPI, S-BUPI, and LIDO. Results: Graphic representation of multiple correspondence analysis associated BUPI with the most pronounced modifications in ECG and HEM variables, followed by in decreasing order ROPI, S-BUPI, and LIDO. Comparisons of clusters identified by hierarchical ascending classification confirmed this classification for ECG variables. Ventricular tachycardia occurred only in the BUPI group. Conclusions: In our anesthetized ewe model, high dose IV infusion of BUPI induced the most marked changes in RR, PR, QRS, QT, QTc intervals, &Dgr;SAP, and &Dgr;dP/dt. ROPI altered ECG variables less than BUPI but more than S-BUPI. LIDO was associated with the smallest changes.