Use of analgesics in France, following dextropropoxyphene withdrawal

Background

In 2009, the European Medicines Agency recommended withdrawal of dextropropoxyphene (DXP); in March 2011 it was withdrawn from the market in France. Up until that time the combination dextropropoxyphene-paracetamol (DXP/PC) was widely used for analgesia. At withdrawal, French regulators recommended that DXP/PC be replaced by other step 2 analgesics, i.e. tramadol, codeine, or opium-containing drugs, or by PC for a weak level of pain. To investigate prescribing behaviours after DXP/PC withdrawal, dispensations of analgesics before and after withdrawal were analysed.

Methods

Aggregated dispensation data of analgesics prescribed between January 2009 and December 2012 in the Rhône-Alpes region were obtained from the general health insurance claims data; changes in analgesic dispensation over time were analysed with the ATC/DDD methodology. Pre (Jan-June 2009) and post-withdrawal (Jan-June 2012) changes of DDDs where computed for each analgesic step.

Results

The dispensations of DXP/PC experienced a two-step decrease until 2011. Over the withdrawal period 2009-2012, there was a 14% decrease in the overall use of analgesic (from 109 to 94 DDDs), while the use of step 2 analgesics declined by 46% (− 22 DDDs, from 47 to 25 DDDs). This latter decline included a cessation of use of DXP/PC (29 DDDs in 2009) that were only in part (+ 7 DDDs, from 18 to 25 DDDs) compensated by increased use of codeine, tramadol and opium, in monotherapy or combined with PC. For step 1 analgesics, use increased with 9%, mostly PC (+ 8 DDDs, from 31 to 39 DDDs). Step 3 analgesics dispensations remained largely unchanged over this period (around 3 DDDs).

Conclusions

In the Rhône-Alpes region, DXP/PC withdrawal was accompanied in part by an increased use of same level analgesics, and in part by an increased use of PC in monotherapy. The extent of DXP/PC use before withdrawal, and the increased use of PC after DXP withdrawal, underline the complexity of pain management.

Far-field mapping of the longitudinal magnetic and electric optical fields

In this Letter, we demonstrate the experimental mapping of the longitudinal magnetic and electric optical fields with a standard scanning microscope that involves a high-numerical-aperture far-field objective. The imaging concept relies upon the insertion of an azimuthal or a radial polarizer within the detection path of the microscope that acts as an optical electromagnetic filter aimed at transmitting selectively to the detector the signal from the magnetic or electric longitudinal fields present in the detection volume, respectively. The resulting system is thus versatile, noninvasive, and of high resolution, and shows high detection efficiencies. Magnetic optical properties of physical and biological micro- and nano-structures may thus be revealed with a far-field microscope.

[Acute renal replacement therapy in pediatrics]

In pediatric intensive care unit, the available modalities of acute renal replacement therapy include intermittent hemodialysis, peritoneal dialysis and continuous renal replacement therapies. No prospective studies have evaluated to date the effect of dialysis modality on the outcomes of children. The decision about dialysis modality should therefore be based on local expertise, resources available, and the patient's clinical status. Poor hemodynamic tolerance of intermittent hemodialysis is a common problem in critically ill patients. Moreover, many pediatric intensive care units are not equipped with dedicated water circuit. Peritoneal dialysis, a simple and inexpensive alternative, is the most widely available form of acute renal replacement therapy. However, its efficacy may be limited in critically ill patients. The use of continuous renal replacement therapy permits usually to reach a greater estimated dialysis dose, a better control of fluid balance, and additionally, to provide adequate nutrition.

Cerebral oxygen saturation is improved by xenon anaesthesia during carotid clamping

INTRODUCTION

The cerebral protective effect of xenon anesthesia could be of interest during carotid surgery. The purpose of this study was to compare the effects of xenon on cerebral oxygen saturation with those of propofol during carotid clamping.

METHODS

After approval of Research Ethics Board and patient informed consent, 74 patients scheduled for carotid endarterectomy were enrolled. Patients were not randomized but were well matched by preoperative characteristics. Patients in the Xenon group were the ones scheduled for surgery in the operative theater equipped with the xenon anesthesia system. Anesthesia was started with a target control infusion of propofol and remifentanil. Patients were then divided into the control group (37 patients) with anesthesia maintained with target control infusion propofol and remifentanil and the Xenon group with anesthesia maintained with xenon (target inspired concentration of 60%) and target control infusion remifentanil. Remifentanil and xenon or propofol were stopped at the end of skin closure.

RESULTS

A cerebral oxygen saturation decrease below 55% was less frequently observed in the Xenon group during carotid cross-clamping (7/37 patients vs 15/37; p=0.01). Compared with values observed before clamping, the decrease in cerebral oxygen saturation during clamping was significantly less important in the Xenon group (12±11% vs 17±14%, p=0.04). Blood pressure and heart rate were not different between groups during carotid clamping.

CONCLUSIONS

This pilot study suggests that xenon anesthesia may be associated to higher cerebral oxygen saturation values when compared to propofol anesthesia during cross-clamping for carotid endarterectomy.

[Organization of anaesthesia for children in a non-paediatric hospital]

The author reviews the guidelines and the possible organization of anaesthesia and surgery in a non-paediatric hospital.

The learning process of the hydrolocalization technique performed during ultrasound-guided regional anesthesia

BACKGROUND

Because poor echogenicity of the needle remains a safety issue, we decided to analyze the learning process of the hydrolocalization technique (Hloc) performed to continuously identify needle-tip anatomical position during many ultrasound-guided regional anesthesia procedures.

METHODS

Ten senior anesthesiologists naïve to the Hloc agreed to participate in the study. They were requested to perform 40 out-of-plane (OOP) approach ultrasound-guided axillary blocks (AB) each using the Hloc. The Hloc, which is a needle-tip localization principle, was performed by means of repetitive injections of a small amount of a local anesthetic solution (0.5-1 ml) under an ultrasound beam. Details of the learning process and skill acquisition of the Hloc were derived from the following parameters: the duration of block placement, a measure of the perceived difficulty of needle-tip visualization, a measure of block placement difficulty, and the amount of local anesthetics solution required for the technique.

RESULTS

Four hundred ABs were performed. The success rate of an ultrasound-guided AB was 98%. The Hloc was successful in all patients. Skill acquisition over time of the Hloc was associated with a significant reduction of both the duration and the perceived difficulty of ABs placement. Apprenticeship data revealed that 20 blocks were required to successfully place AB within 5 min in most cases using the Hloc.

CONCLUSION

The Hloc performed during the OOP approach of ultrasound-guided regional anesthesia is a simple technique with a relatively short learning process feasible for efficient placement of ABs.

Local anaesthetic use for the iliac crest-donor site: pharmacokinetic and pharmacodynamic evaluations

During orthopaedic surgery of the limb, we performed a prospective, double blind controlled study on three parallel groups in 30 patients to evaluate the pharmacokinetic and pharmacodynamic effect of infiltration of the iliac crest bone graft harvest site with 20 ml of bupivacaine (100 mg), ropivacaine (150 mg) or saline as control group (n = 10 in each group). Then, in a sheep model of iliac crest infiltration, we compared the pharmacokinetics of single administration of plain bupivacaine (100 mg) and bupivacaine (500 mg)-loaded microspheres. In the clinical control group, pain from the iliac crest was worse than pain from the primary surgical site. Pain from the iliac crest was significantly reduced during the first 12 postoperative hours in local anaesthetic groups compared to the control group. However, during this period, pain from the primary surgical site was increased compared to the control group. Finally, there was no difference between the three groups in the average intake of PCA morphine. There was no significant pharmacokinetic and pharmacodynamic difference between plain bupivacaine and ropivacaine. The maximal plasma concentration (Cmax) of ropivacaine and bupivacaine were 964 (282) ng ml(-1) and 638 (366) ng ml(-1), respectively. In the sheep model, it was clearly shown that the release of bupivacaine from microspheres was controlled and prolonged despite the largest dose of bupivacaine used (500 mg; n = 4). Wound infiltration of iliac crest harvest site with local anaesthetic is an easy technique for postoperative analgesia. However, this effect lasts only 12 hours without reducing the morphine consumption due to an increase of pain from the primary surgical site. The local anaesthetic infiltration produced a significant peak of plasma level, which could be dangerous if another infiltration or regional anaesthetic technique was associated with it. Experimentally, as a drug delivery system, the use of local anaesthetic-loaded microspheres could be an interesting alternative.

Variation of bispectral index under TIVA with propofol in a paediatric population

BACKGROUND

In this prospective observational study, we aim to explore the relationship between age and bispectral index (BIS) values at different plasma concentrations of propofol.

METHODS

Fifty children aged from 3 to 15 yr were included. Anaesthesia was induced using a target-controlled infusion of propofol with the Kataria pharmacokinetic model together with a bolus of remifentanil followed by a continuous infusion rate at 0.2 microg kg(-1) min(-1). Target plasma propofol concentration was initially stabilized to 6 microg ml(-1) and continued for 6 min. The target was then decreased and stabilized to 4 microg ml(-1) and then to 2 microg ml(-1). BIS values, plasma propofol concentration, and EEG were continuously recorded. In order to explore the relationship between variations in propofol concentration and the EEG bispectrum, we used a multiple correspondence analysis (MCA). Results are shown in median (range).

RESULTS

We found no statistical difference between BIS values with propofol 6 microg ml(-1) [23 (12-40)] and 4 microg ml(-1) [28 (9-67)]. At 2 microg ml(-1), BIS was significantly different [52 (24-71)], but a significant correlation between the age of children and BIS values was found (r2=0.66; P<0.01). There was little change in children's position between 6 and 4 microg ml(-1) in the structure model of the MCA. From 4 to 2 microg ml(-1), the position of children moved only on axis 2.

CONCLUSIONS

These results showed the difficulty to interpret BIS values because of the absence of significant change for higher plasma propofol concentration variation or because of the link with age for the lower plasma concentration.

Effect of epinephrine on epidural, intrathecal, and plasma pharmacokinetics of ropivacaine and bupivacaine in sheep

BACKGROUND

Local vasoconstriction induced by epinephrine added to epidural local anaesthetics has been shown to improve their quality and duration of action in several clinical reports. There are several assumptions on the mechanisms. This study was designed to evaluate the influence of epinephrine on transmeningeal uptake of epidurally administered ropivacaine and bupivacaine by measuring local anaesthetic concentrations in the epidural and intrathecal spaces and in plasma.

METHODS

Ropivacaine (50 mg) and bupivacaine (30 mg) were administered epidurally in sheep with and without epinephrine (75 microg). A microdialysis technique was used to simultaneously measure epidural and intrathecal drug concentrations. Resulting dialysate and plasma concentrations were used to calculate pharmacokinetic parameters for ropivacaine and bupivacaine.

RESULTS

Co-administration of epinephrine decreased epidural clearance for ropivacaine [0.6 (sd 0.1) vs 0.4 (0.1) ml min(-1)] but not significantly for bupivacaine [1.2 (0.4) vs 0.8 (0.3) ml min(-1)]. The resultant increase in epidural area under the concentration-time curves (31% for ropivacaine and 52% for bupivacaine) was also observed in the intrathecal space (21% increase for ropivacaine and 37% for bupivacaine). There was no significant influence of epinephrine on ropivacaine plasma pharmacokinetics. Plasma Cmax for bupivacaine was decreased.

CONCLUSIONS

These results show that epinephrine decreases the clearance and distribution processes involved in epidural disposition of ropivacaine and bupivacaine, leading to an increased uptake into the intrathecal space with an apparent more pronounced effect for bupivacaine.

[Psoas compartment block with general anaesthesia: descriptive study of 93 cases]

OBJECTIVES

During many years the approach to the lumbar plexus has been the anterior paravascular technique described as a "3-1" block by Winnie. The posterior approach results in a complete block of the principal nerves of the lumbar plexus. The goal of the study was to evaluate the performance of the psoas compartment block with general anaesthesia.

STUDY DESIGN

Prospective, descriptive, non randomized study.

PATIENTS AND METHODS

Ninety-three patients scheduled for hip surgery were studied after informed consent. Demographic data, technical aspects of the puncture, complications, and intra- and postoperative analgesics were recorded.

RESULTS

The block was performed by resident alone, senior alone, both in respectively 44%, 45, and 11% of cases. The mean duration of the procedure was 6+/-3 min for the residents, 5+/-2 min for the seniors, and 9+/-4 min for both. The transverse process was reach in 72% of cases during the first approach, after reorientation of the needle in the others cases, except 3 failures of attempt. The lumbar plexus was assessed within 60-90 mm of depth, with a median of 75 mm. The motor response was mainly a femoral response; the minimal intensity of stimulation was ranged between 0.3 and 1 mA, with a median of 0.6 mA. The duration of analgesic block was 16.5+/-4.5 hours, with a median of 18 hours. The morphine use during the first postoperative 24 hours was 8+/-8 mg, with a median of 5.6 mg. No neurologic complication was recorded at discharge from the hospital.

CONCLUSION

The psoas compartment block with general anaesthesia have shown it feasibility and efficiency on intra- and postoperative analgesia during hip surgery.

[Regional organization for intensive care in children, need for maintenance of competence in paediatric anaesthesia and intensive care]

The recent French text concerning the medical care both of the child and the teenager classifies the establishments either in specialized centers or in proximity centers according to their level in the management of children and teenagers, the competences of their medical teams, their organization in permanence of care and the volume of acts they carry out and pathologies they treat by class of age. This grid of the paediatric activities implies a new organization both in paediatric surgery and in paediatric ENT and consequently in the anaesthetic organization. Anaesthetic competences necessary to the achievement of this mission and the means of maintaining these later are analyzed and compared with some foreign experiments.

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 microg.kg(-1) atropine injection (AT + REMI) and the other ringer lactate solution (REMI). Three minutes later, a 1 microg.kg(-1) bolus of remifentanil was administered over 1 min, followed by a continual infusion at 0.25 microg.kg(-1).min(-1) for 10 min increased to 0.5 microg.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 remifentanil's negative chronotropic effect. A direct negative chronotropic effect of remifentanil is proposed.

Local anesthetics in pediatric anesthesia: an update

For several decades, bupivacaine has enjoyed great clinical popularity as the first choice local anesthetic in pediatrics. However, introduction of ropivacaine and levobupivacaine, the two newer and presumably safer (thought to be less cardio- and neurotoxic than bupivacaine) local anesthetics, has challenged the position of bupivacaine as a gold standard for prolonged duration of analgesia. This review article summarized the metabolism, the criteria of choice and the safety use of new agents.

Impact of age on both BIS values and EEG bispectrum during anaesthesia with sevoflurane in children

BACKGROUND

The aim of this study was to evaluate the potential relationship between age, BIS (Aspect), and the EEG bispectrum during anaesthesia with sevoflurane.

METHODS

BIS and raw EEG were recorded at a steady state of 1 MAC in 100 children, and during a decrease from 2 to 0.5 MAC in a sub-group of 29 children. The bispectrum of the EEG was estimated using MATLAB software. For analysis, the bispectrum was divided into 36 frequencies of coupling (P(i))--the MatBis. A multiple correspondence analysis (MCA) was used to establish an underlying structure of the pattern of each individual's MatBis at 1 MAC. Clustering of children into homogeneous groups was conducted by a hierarchical ascending classification (HAC). The level of statistical significance was set at 0.05.

RESULTS

At 1 MAC, the BIS values for all children ranged from 20 to 74 (median 40). Projection of both age and BIS value recorded at 1 MAC onto the structured model of the MCA showed them to be distributed along the same axis, demonstrating that the different values of BIS obtained in younger or older children are mainly dependent on their MatBis. At 1 MAC, six homogeneous groups of children were obtained through the HAC. Groups 5 (30 months; range 23-49) and 6 (18 months; range 6-180) were the younger children and Group 1 (97 months; range 46-162) the older. Groups 5 and 6 had the highest median values of BIS (54; range 50-59) (55; range 26-74) and Group 1 the lowest values (29; range 22-37).

CONCLUSION

The EEG bispectrum, as well as the BIS appeared to be strongly related to the age of children at 1 MAC sevoflurane.

Contralateral effect of amitriptyline and bupivacaine for sciatic nerve block in an animal model of inflammation

BACKGROUND

Using a carrageenan inflammation rat model, we evaluated two experimental approaches to prolong sciatic nerve block on contralateral hyperalgesia. Method. We performed ipsilateral sciatic nerve block on the inflamed hind paw with bupivacaine-loaded microspheres suspended in dexamethasone (bupivacaine 12.5 mg) and with amitriptyline (6.25 and 12.5 mg) as ultralong-acting local anaesthetics. Bupivacaine (1.25 mg) was used as long-acting local anaesthetic and saline was used as a control. The sixth group received amitriptyline 6.25 mg intraperitoneally (n=10 for each group).

RESULTS

The duration of ipsilateral nerve block was 2 h for bupivacaine, 7 h for amitriptyline 6.25 mg, 11 h for amitriptyline 12.5 mg and 21 h for bupivacaine-loaded microspheres in suspension with dexamethasone. Whereas contralateral hyperalgesia was not observed during block produced by bupivacaine-loaded microspheres, contralateral hyperalgesia was observed with sciatic nerve block using amitriptyline.

CONCLUSIONS

Because of the differential effect observed on the contralateral side, the mechanism underlying the prolongation of ipsilateral block with amitriptyline may not result only from a prolonged Na(+) channel blockade but might be explained by a local toxic effect or lack of systemic actions.

[A case of anaphylactic shock with tranexamique acid (Exacyl)]

A 72-year-old male patient was scheduled for coronary artery bypass graft surgery because of severe three-vessel disease. Induction of anaesthesia was uneventful. Following bolus infusion of tranexamic acid (Exacyl), the patient presented clinical signs consistent with anaphylactic shock. Surgery was postponed and the patient recovered without sequaelae. Allergological investigations (cutaneous tests, serum IgE concentrations, in vitro histamine-release tests) suggest that this is the first reported case of anaphylactic shock to tranexamic acid. Several weeks later, the patient underwent surgery with a similar anaesthetic regimen and the clinical course was uneventful.

Alkalinization of intra-cuff lidocaine and use of gel lubrication protect against tracheal tube-induced emergence phenomena

BACKGROUND

We sought to determine the benefits of using alkalinized lidocaine 40 mg to fill the cuff of a tracheal tube (ETT) in combination with water-soluble gel lubrication to prevent post-intubation sore throat.

METHODS

The work included an in vitro study of the diffusion of alkalinized lidocaine solution through the low-pressure, high-volume cuff of an ETT. We also performed a randomized controlled study (n=20 patients in each group) that included a group who received an alkalinized lidocaine-filled ETT cuff with lubrication of the tube using water-soluble gel (Group G), and two control groups who received an alkalinized lidocaine-filled cuff with ETT lubrication with water (Group W) or an air-filled cuff with ETT lubrication with water (Group C).

RESULTS

Water-soluble gel lubrication (Group G) produced a lower incidence of sore throat during the 24-h post-extubation period than lubrication with water alone in the cuffs filled with alkalinized lidocaine (Group W), and compared with the air control group. The ability of lidocaine to pass through the cuff of an ETT when water-soluble gel and/or water alone was used as a lubricant was similar, as determined by lidocaine plasma concentrations (C(max) 45 ng x ml(-1)). Cough and restlessness before tracheal extubation were decreased in patients with the alkalinized lidocaine-filled cuffs compared with the air-filled cuffs. After extubation, nausea, vomiting, dysphonia and hoarseness were greater for patients with air-filled cuffs compared with the lidocaine-filled cuffs. No significant difference between the groups was recorded in arterial blood pressure and heart rate. In vitro data suggest that the lower the NaHCO(3) injection volume, the greater the release of lidocaine across a low-pressure, high-volume cuff.

CONCLUSIONS

These data show benefits of using an alkalinized lidocaine-filled ETT cuff in combination with water-soluble gel lubrication in preventing post-intubation sore throat.

[Airway equipment and its maintenance for a non difficult adult airway management (endotracheal intubation and its alternative: face mask, laryngeal mask airway, laryngeal tube)]

The airway equipment for a non difficult adult airway management are described: endotracheal tubes with a specific discussion on how to inflate the balloon, laryngoscopes and blades, stylets and intubation guides, oral airways, face masks, laryngeal mask airways and laryngeal tubes. Cleaning and disinfections with the maintenance are also discussed for each type of airway management.

[Laryngeal mask airway in paediatrics: when? How?]

Since its introduction in 1981 by Brain, the laryngeal mask airway has achieved increased popularity in pediatrics. Despite widespread use, the definitive role of the laryngeal mask airway has yet to be established. We attempt to clarify the role of the laryngeal mask airway in airway management during anaesthesia by discussing the advantages and disadvantages as well as the indications and contra-indications of its use. The use in failed or suspected difficult endotracheal intubation was also described. Finally, we review the techniques of insertion, details of misplacement, the removal and complication associated with the use of laryngeal mask airway. Cleaning, pre-use checking and maintenance were also discussed.

Effect of dexamethasone on motor brachial plexus block with bupivacaine and with bupivacaine-loaded microspheres in a sheep model

BACKGROUND AND OBJECTIVE

It has been suggested that dexamethasone potentiates the sensory block produced by bupivacaine when both drugs are loaded in microspheres. The aim of the study was to evaluate the effect of dexamethasone on the brachial plexus block obtained with plain bupivacaine and bupivacaine-loaded microspheres.

METHODS

Dexamethasone alone (Group 5) or added to plain bupivacaine (75 mg) with (Groups 3 and 4) and without pH correction (Group 2) was compared with plain bupivacaine (75 mg; Group 1). The effect of a small dose of dexamethasone (0.42 mg) was then evaluated on the brachial plexus block obtained with bupivacaine (750 mg) as bupivacaine-loaded microspheres (Group 6). Dexamethasone was added either in the suspending medium (Group 7) or incorporated with bupivacaine into microspheres (Group 8). The motor block was evaluated in a plexus brachial sheep model.

RESULTS

Dexamethasone alone did not produce any motor block. When added to plain bupivacaine without pH correction, complete motor block could not be obtained. When the pH was corrected, addition of dexamethasone to plain bupivacaine seemed to delay the onset of motor block and did not prolong its duration, and it had no effect on the pharmacokinetics of bupivacaine. With bupivacaine-loaded microspheres, the duration of complete motor block was reduced when a small dose of dexamethasone was added in the suspending medium. However, the duration of motor block was significantly prolonged when dexamethasone was incorporated with bupivacaine into microspheres.

CONCLUSIONS

Despite the delayed onset of motor block, the incorporation of dexamethasone in bupivacaine-loaded microspheres dramatically increases the duration of action (700 +/- 485-5160 +/- 2136 min), which could be clinically relevant when such a drug-delivery system will be available.

Limits of corrected flow time to monitor hemodynamic status in children

OBJECTIVE

Doppler corrected flow time (i.e., corrected left ventricular ejection time) as a noninvasive tool for assessing hemodynamic changes has been previously reported for adult patients. Its use in paediatrics seems to be worthwhile but no data concerning its accuracy are presently available in this population. The purpose of this work was to study the relationships between corrected flow time (FT) and indices of systemic vascular resistance (SVR) and of myocardial contractility in healthy children.

METHODS

Twenty healthy children performed a graded maximal bicycle exercise in order to induce physiological hemodynamic alterations. Hemodynamic parameters were measured with an echocardiography-Doppler at rest and within a few minutes of post exercise. Cycle time (RR), mean aortic flow velocity, mean systolic velocity (MSV), FT, peak velocity (PV), and stroke distance were measured on the Doppler aortic velocity waveform. Cardiac index (CI) and SVR were calculated from the classical volumetric equation. Corrected FT was calculated by using Bazett's formula (FTb = FT/square root(RR)) and a simplified formula FTc = FTmeasured + [1.29 x (HR - 60)].

RESULTS

Post exercise, SVR, RR, FT, decreased, while CI, PV and MSV increased and stroke distance remained unchanged. After multiple regression analysis no significant correlation between SVR and FTb and SVR or FTc was noted. A significant correlation appeared between FTb and, respectively, PV (r = -0.83; p < 0.001), stroke distance (r = 0.78; p < 0.001) and RR (r = -0.52; p = 0.0016). A significant correlation was also shown between FTc and, respectively, PV (r = -0.71; p < 0.001) and stroke distance (r = 0.63; p < 0.001) but not with RR.

CONCLUSIONS

These results show that the use of Bazett's formula correct FT could lead to hemodynamic misinterpretations, because it does not rule out all the heart rate effect. Moreover, in healthy children corrected FT appears as an inaccurate index to monitor physiological afterload alterations, because of the involvment of other hemodynamic factors such as contractility in its variation.

Pilot study on the effect of tourniquet use on sufentanil pharmacokinetics

STUDY OBJECTIVE

To test our hypothesis that sequestration of sufentanil can occur during surgery when a pneumatic tourniquet is used.

DESIGN

Prospective, randomized study.

SETTING

Operating room and recovery room of a university hospital.

PATIENTS

16 ASA physical status I and II patients scheduled for orthopedic surgery with pneumatic tourniquet use.

INTERVENTION

Patients were randomized to three groups. Sufentanil was given intravenously at 0.5 microg kg(-1) bolus at the same time that a constant infusion was started at 0.5 microg kg h(-1). In Group 1, continuous infusion of sufentanil was stopped when the tourniquet was released (n = 6). In Group 2, continuous infusion of sufentanil was stopped 15 minutes after tourniquet release (n = 6). In Group 3, as a control group, the sufentanil bolus was started after tourniquet inflation (n = 4).

MEASUREMENTS

Plasma sufentanil concentrations were determined by radioimmunoassay. To compare pharmacokinetic results, a simulation of the sufentanil plasma concentrations was achieved.

MAIN RESULTS

Exsanguination and inflation of the pneumatic tourniquet had no significant effect on pharmacokinetic results. In 75% of patients, a significant increase in sufentanil plasma concentration occurred between 30 and 60 minutes after tourniquet deflation in all three groups, probably as a result of patient mobilization. One respiratory distress event occurred in a Group 2 patient following extubation at 55 minutes after the end of the sufentanil infusion. The rebound of sufentanil concentration was higher in Group 2; it may be due to a reduced effect of the restoring circulation in the ischemic leg by a prolonged infusion after tourniquet deflation.

CONCLUSIONS

Using a pneumatic tourniquet induces transient changes in the pharmacokinetics of sufentanil. These changes may have clinical relevance during the first hour after tourniquet release.

Hypercapnia during transperitoneal and retroperitoneal endoscopic spinal surgery: a prospective study

STUDY OBJECTIVE

To evaluate the effect of carbon dioxide (CO(2)) pneumoperitoneum and retropneumoperitoneum insufflation on CO(2) excretion.

DESIGN

Prospective study.

SETTING

Operating room and recovery room in a teaching hospital.

PATIENTS

29 patients scheduled for orthopedic spine fusion surgery.

INTERVENTIONS

Patients received either transperitoneal insufflation (n = 12) or retroperitoneal insufflation (n = 17).

MEASUREMENTS AND MAIN RESULTS

Increases in the partial pressure of end-tidal CO(2) (PetCO(2)) and arterial CO(2) tension (PaCO(2)) during retropneumoperitoneum exceeded those obtained during pneumoperitoneum. Furthermore, PetCO(2) increased faster during retroperitoneum and did not reach a plateau. Finally, 76% of the patients in this group required ventilatory adjustment due to high PetCO(2) levels.

CONCLUSIONS

This study may focus attention on the need for continuous ventilatory adjustments during transperitoneal endoscopic surgery.

[Prevention of pain on injection with propofol in children: comparison of nitrous oxide with lidocaine]

INTRODUCTION

Injection pain caused by propofol is an important disadvantage, especially in children, incompletely reduced by adding lidocaine intravenously. Nitrous oxide's analgesic effects, well known, have never been evaluated on pain due to propofol.

OBJECTIVE

To compare the effects of nitrous oxide with lidocaine on pain on injection caused by propofol in children.

STUDY DESIGN

Double blind, randomised, prospective study.

PATIENTS AND METHODS

48 children aged more than 5 were randomly allocated to one of the 2 groups: N2O group, breathed 50% N2O + 50% O2 than received propofol only and Lido group breathed 100% O2 and received a mixture of propofol with lidocaine. The possible pain was scored during injection by a behavioural scale and once again in the recovery room by the child himself with a VAS.

RESULTS

There was no significant difference in behavioural pain scores among the 2 groups; pain was assessed as being moderate or severe in 6/24 patients in N2O group and 10/24 in Lido group (behavioural scores > 1). Significantly more children in the N2O group had low VAS scores compared with the Lido group (no child/24 scored a VAS > 4 and 7/23 in the Lido group) demonstrating that N2O amnesic effects would omit the memory of pain caused by propofol.

CONCLUSION

The use of nitrous oxide is an easy, cheap and efficient method to reduce the incidence of pain injection of propofol and his amnesic effects can provide real advantages in paediatric anaesthesia.

Infraclavicular block with lateral approach and nerve stimulation: extent of anesthesia and adverse effects

BACKGROUND AND OBJECTIVES

The infraclavicular approach to the brachial plexus is little used despite theoretical advantages of the technique. Using a vertical paracoracoid approach, we assessed the extent of the sensory block and the incidence of adverse effects.

METHODS

After obtaining informed consent, 100 patients undergoing surgical procedures distal to the elbow were evaluated. The block was performed using a peripheral nerve stimulator. The puncture site was located in the infraclavicular fossa; the direction of the insulated needle was perpendicular to the skin. Motor response was sought in the hand or wrist at < or = 0.6 mA. A total of 40 mL of 1.5% mepivacaine was administered as a single injection. The sensory block was evaluated every 5 minutes for 30 minutes before surgery in the cutaneous distribution of terminal branches of the brachial plexus.

RESULTS

When one considers the cutaneous distributions of the median, ulnar, radial, and musculocutaneous nerves, the success rate was 89% for surgery without need for additional peripheral nerve blocks or general anesthesia. In contrast, cutaneous areas innervated by the axillary and medial cutaneous nerves were rarely anesthetized. We were unable to demonstrate a correlation between the intensity of the stimulation and the success of the block. On the other hand, a correlation was found between tourniquet sensation and the absence of anesthesia of the medial cutaneous nerve of the arm. Local anesthetic toxicity, Horner's syndrome, and vascular puncture were respectively observed in 1%, 4%, and 5% of cases. The depth of the needle introduction was correlated with the body mass index (P <.001; r =.63).

CONCLUSION

Single injection infraclavicular block, using a vertical paracoracoid approach, appears suitable for surgery distal to the elbow. Selective anesthesia of the medial cutaneous nerve is useful in improving tolerance of the tourniquet.