Biomedical subjects

Claude Ecoffey

Publications and source records attributed to Claude Ecoffey.

At least 19 recordsLinked to original sources

PubMed2006

An evaluation of a polyamine-deficient diet for the treatment of inflammatory pain.

Polyamines are thought to be involved in the regulation of numerous metabolic and electrophysiological processes in the nervous system. In this study we evaluated the effect of a synthetic polyamine-deficient diet on pain in a carrageenan (Car)-induced inflammatory rat model. Inflammation was induced with a unilateral subcutaneous injection of Car in a plantar hindpaw in rats fed without (control group) or with (deficiency group) a polyamine-deficient diet. Ipsilateral and contralateral hyperalgesia was evaluated using the Randall-Sellito pressure test. Heart rate changes were also recorded under general anesthesia. Then, the effects of a bupivacaine sciatic nerve block and subcutaneous injection of naloxone or ketamine were evaluated for Car-induced hyperalgesia. Data were analyzed using analysis of variance followed by unpaired Student's t-test (significance P < 0.05). Before Car injection, no significant difference was observed in response to mechanical stimuli between the control and the deficiency groups (n = 114 in pooled data). Car injection induced significant ipsilateral and contralateral hyperalgesia in the control groups, whereas a significant analgesic effect appeared in the deficient groups on both the ipsilateral and contralateral hindpaws. This analgesic effect was confirmed by the electrocardiogram recording that showed a significant increase in heart rate in the control group after Car injection compared with the deficiency group that showed a decrease in heart rate under general anesthesia. Bupivacaine sciatic nerve block had no significant effect on hypoalgesia phenomena induced by polyamine deficiency. Naloxone administration had no effect in the control group but reversed the analgesic effect in the deficiency group. Ketamine administration induced a significant analgesic effect in the control group and partly reversed the analgesic effect in the deficiency group. In conclusion, a synthetic polyamine-deficient diet had a significant general analgesic effect on Car-induced mechanical hyperalgesia. The mechanism of analgesic action remains to be elucidated.

Analgesia↗

PubMed2005

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. METHODS: Fifty children from 2 to 11 years of age were randomized into two groups: group H received hypnosis as premedication; group M were given 0.5 mg x kg(-1) midazolam orally, 30 min before surgery. Preoperative anxiety was evaluated using the Modified Yale Preoperative Anxiety Scale (mYPAS) score when arriving in the department (T1), when entering the operating room (T2), and when fitting the facemask (T3). Postoperative behavioral disorders were evaluated using the Posthospitalization Behavioral Questionnaire (PHBQ) at days 1, 7 and 14. RESULTS: The two groups showed no significant difference preoperatively with the PHBQ: (M) 21 (17-25) vs (H) 20 (8-25) and mYPAS score: (M) 28 (23-75) vs (H) 23 (23-78). The number of anxious children was less during induction of anesthesia in the hypnosis group (T3: 39% vs 68%) (P < 0.05). Postoperatively, hypnosis reduced the frequency of behavior disorders approximately by half on day 1 (30% vs 62%) and day 7 (26% vs 59%). CONCLUSIONS: Hypnosis seems effective as premedication in children scheduled for surgery. It alleviates preoperative anxiety, especially during induction of anesthesia and reduces behavioral disorders during the first postoperative week.

Abdomen↗

PubMed2005

Alkalinization of intracuff lidocaine: efficacy and safety.

When alkalinized lidocaine instead of air is used to fill the endotracheal tube (ETT) cuff, coughing, and bucking are decreased during extubation when ventilation is controlled with N2O. However, sodium bicarbonate (NaHCO3) used to transform lidocaine hydrochloride (L-HCl) to lidocaine base induces a pH increase that could be irritating for mucosa in the case of cuff rupture. Therefore, we determined, in a randomized controlled study with controlled patient ventilation without N2O, whether the smallest concentrations of NaHCO3 (1.4% versus 8.4%) reduced diffusion (in vitro evaluation) and other secondary clinical benefits. After pH determination of different solutions (2 mL of 2% L-HCl and 2 to 6 mL of 8.4%, or 1.4% NaHCO3), an in vitro lidocaine diffusion through the ETT cuffs was evaluated (2 mL of 2% L-HCl and 3 mL of 8.4% or 1.4% NaHCO3). Then, adult patients scheduled for total thyroidectomy surgery were consecutively enrolled (n = 20 for each group). The ETT cuff was filled with air (group air) or with alkalinized lidocaine (2 mL of 2% L-HCl) using 8.4% (group large dose) or 1.4% (group small dose) of NaHCO3. After tracheal extubation, sore throat was evaluated by visual analog scale as the main end-point of the study. Hoarseness, bucking, dysphonia, dysphagia, cough, restlessness, and postoperative nausea and vomiting were also evaluated. There was a slight tendency toward a slower release when a small concentration of NaHCO3 was used (i.e., 1.4%). Compared with group air, the alkalinized-lidocaine groups had a significant reduction in sore throat during the 24-h postoperative period (P < 0.0001). The difference was not significant between the two alkalinized lidocaine groups. This increase in ETT tolerance was confirmed by the analysis of secondary end-points. No laryngospasm, rupture of ETT cuff, or depression of the swallowing reflex were recorded. A decrease in sore throat during the postoperative period was recorded when the cuff was inflated with a small dose of alkalinized lidocaine (i.e., 40 mg of L-HCl and 1.4% of NaHCO3) rather than with air when ventilation was controlled without N2O.

Adult↗

PubMed2004

Effect of preoperative oral sustained-release morphine sulfate on postoperative morphine requirements in elective spine surgery.

Sustained-release morphine sulfate (SRMS) is a painkiller used in oncology. The purpose of our study was to assess its efficacy on postoperative morphine requirements in elective spine surgery. This was a placebo-controlled, randomized, double-blind study. Adults scheduled for spine surgery under general anesthesia were orally administered SRMS (30 mg) or a placebo 2 h before surgery. Primary endpoint was postoperative cumulated morphine consumption through patient-controlled analgesia (PCA) during the 12 h following extubation. Statistical analysis was performed using a sequential method, the triangular test. The study was stopped after the sixth analysis (51 patients had been included; placebo: 26, SRMS: 25). Age, weight, sex ratio, type of surgery, intra-operative sufentanil consumption, anesthesia duration and time to extubation were similar in the two groups. Morphine consumption through PCA during the 12 h following extubation was significantly lower in the SRMS group (mean +/- SD: 10.5 +/- 7.6 mg) compared with placebo group (15.6 +/- 6.0 mg, P = 0.016, sequential analysis). Corresponding unbiased median estimates were 10.6 and 15.8 mg in SRMS and placebo groups, respectively. Morphine consumption through PCA during the 24 h following extubation was also significantly lower in the SRMS group (15.9 +/- 12.7 mg) compared with the placebo group (23.8 +/- 10.9 mg, P = 0.032). Vigilance, nausea and respiratory rate 3 and 6 h after extubation were similar in the two groups. A preoperative oral administration of SRMS (30 mg) induces a 33% reduction of postoperative morphine requirements in patients scheduled for spine surgery without inducing side effects.

Analgesia, Patient-Controlled↗

PubMed2003

Base deficit in immediate postoperative period of coronary surgery with cardiopulmonary bypass and length of stay in intensive care unit.

OBJECTIVE: To assess the relationship between the base deficit value in the immediate postoperative period of coronary surgery for cardiopulmonary bypass and the length of stay in the ICU. DESIGN AND SETTING: Prospective descriptive study in the department of anesthesia and cardiovascular surgery of a university hospital. PATIENTS: 185 consecutive patients. INTERVENTIONS: Coronary artery bypass graft with cardiopulmonary by pass. MEASUREMENTS AND RESULTS: Thirty variables were determined during the pre-, intra-, and postoperative periods; a statistical univariate analysis was performed differentiating patients whose length of stay in the ICU was 2 days or less and those whose stay was more than 2 days. Secondly, a logistic regression model was performed on the variables shown to have a statistically significant difference in univariate analysis, with determination of the odd ratio. Fourteen variables had a statistically significant difference in univariate analysis and three of them highlighted by the logistic regression model: administration of catecholamines, base deficit value in the 1st h postoperatively, and age with odd ratios, respectively, of 3.15, 1.51, and 1.07). CONCLUSIONS: The value of base deficit measured during the 1st h after coronary surgery for cardiopulmonary bypass is correlated with the length of stay in ICU.

Acidosis↗

PubMed2003

A French survey of paediatric airway management use in tonsillectomy and appendicectomy.

BACKGROUND: There are no epidemiological data describing tracheal intubation and laryngeal mask airway (LMATM) use in paediatric anaesthesia. This analysis focused on the factors leading to the indication for an airway management procedure, i.e. tracheal intubation and laryngeal mask airway vs face mask during general anaesthesia for tonsillectomy and appendicectomy. METHODS: The data were recorded in the French survey of Practical Anaesthesia performed in 1996. Two main types of surgical procedures were selected: tonsillectomy and appendicectomy because of the number of patients and the need to use an invasive airway management technique. RESULTS: During a 1-year period, 627 anaesthetics for appendicectomy and 653 anaesthetics for tonsillectomy were recorded in the sample under consideration. Tracheal intubation or laryngeal mask airway was undertaken in 66% of tonsillectomies and 84% of appendicectomies. Univariate analysis showed that tracheal intubation/laryngeal mask were used significantly more often in older children, with long duration of anaesthesia, in nonambulatory procedures and in procedures performed at an academic centre. When these variables were included in a multivariate analysis, the duration of anaesthesia over 30 min was a factor linked to the use of tracheal intubation/laryngeal mask airway for the two types of surgery (P < 0.0001). For tonsillectomy, inpatients were 2.9 times more likely to be intubated (or have an laryngeal mask airway) than were outpatients. For appendicectomy, older children were 3.4 times more likely to be intubated (or have an laryngeal mask airway) than younger children. CONCLUSIONS: This large French survey shows that the use of tracheal intubation/laryngeal mask airway in this country is primarily related to a predicted long duration of anaesthesia.

Adolescent↗

PubMed2003

Informed consent for children.

PURPOSE OF REVIEW: Consent has always been an essential element in the physician-child/parent relationship, more importantly as an ethical duty than as a legal requirement, and continues to represent the most important form of communication between children and parents and physicians. RECENT FINDINGS: The main themes described in this review - the age of competence to give consent and the role of the parents in giving consent - constitute the complex situation of consent in paediatrics. Refusal by children and parents and consent by children for participation in clinical research studies are also discussed. SUMMARY: This review supports the moral viewpoint that minors with decision-making capacity, regardless of their age, should be involved in their healthcare decisions, even if the law is to have consent from parents or legal guardians.

Journal Article↗

PubMed2003

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

UNLABELLED: 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 (R(2) = 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. IMPLICATIONS: The effects of sevoflurane on parasympathetic activity could explain the difference in heart-rate changes described between infants and children during induction. This study describes the changes in heart rate and its variability induced by sevoflurane in children and shows that these changes are related to parasympathetic tone before the induction of anesthesia.

Anesthesia Recovery Period↗

PubMed2002

Spray-dryed bupivacaine-loaded microspheres: in vitro evaluation and biopharmaceutics of bupivacaine following brachial plexus administration in sheep.

Microspheres could be used as a drug delivery system to prolong the duration of action of bupivacaine and to reduce its systemic absorption leading to high plasma concentrations related to central nervous and cardiovascular toxicity. Bupivacaine-loaded microspheres were made by spray-drying using polylactide-co-glycolide polymers from different sources and with different bupivacaine-polymer ratio. The characterization of microspheres concerned the shape and size, the bupivacaine drug-content (DC) and the cumulative release profiles. We evaluated in sheep the bupivacaine pharmacokinetics: (i) after short intravenous infusion of 75 mg bupivacaine solution; and (ii) following brachial nerve plexus injections of 75 mg bupivacaine solution alone, with the addition of 75 microg epinephrine, with the addition of 150 microg epinephrine and of bupivacaine (750 mg)-loaded microspheres. Release profiles showed a biphasic pattern whatever the DC. After i.v. infusion the mean clearance value was 1.53+/-0.53 l/min and the mean elimination half-life was 120.5+/-73.1 min. Following brachial plexus nerve injection, bupivacaine C(max) were lower than 100 ng/ml following either solution or microspheres administration. Ninety percent of the 75 mg bupivacaine given as a solution were absorbed in 5.8+/-1.0 h (bupivacaine alone) compared to 24.6+/-1.2 h following microsphere administration.

Anesthetics, Local↗

PubMed2002

The addition of tramadol to lidocaine does not reduce tourniquet and postoperative pain during iv regional anesthesia.

PURPOSE: We conducted a prospective, randomized, double-blind study to determine whether the combination of tramadol with lidocaine 0.5% had an analgesic effect on tourniquet pain during iv regional anesthesia and also on postoperative pain. METHODS: Thirty patients scheduled for carpal tunnel decompression were included in the study. Each patient received 3 mg.kg(-1) of plain lidocaine 0.5% with 100 mg of tramadol (Group T) or 2 mL of isotonic saline (Group C). The mixture was injected into the isolated and exsanguinated arm. Pain was assessed using a linear visual analog scale and a verbal rate scale during the surgical procedure and the postoperative period (240 min) and subsequently at interview at 24 hr. Analgesic consumption was recorded. RESULT: There was no difference in the pain scales and analgesic request at any of the time periods studied. CONCLUSION: We conclude, therefore, that for carpal tunnel operation under iv regional anesthesia, the combination of tramadol and lidocaine is not more effective than lidocaine alone.

Adult↗

PubMed2002

Severe respiratory failure after infraclavicular block with 0.75% ropivacaine: a case report.

Upper extremity surgery is usually performed with an axillary block. There is a risk of pneumothorax and phrenic nerve block when interscalene or supraclavicular block are used in day case surgery, or in patients with chronic obstructive pulmonary disease. The infraclavicular block is a simple, reliable, and easy to learn method to block the brachial plexus. No clinically relevant respiratory effects have been reported with infraclavicular block. Nonetheless, we report a case of a chronic obstructive pulmonary disease patient who developed severe respiratory failure requiring tracheal intubation after an infraclavicular block.

Acute Disease↗

PubMed2002

Extrapolation of cardiac index from analysis of the left ventricular outflow velocities in children: implication of the relationship between aortic size and body surface area.

BACKGROUND: It has recently been reported in critically ill patients that a linear relationship exists between cardiac index (CI) measured with thermodilution and mean aortic blood flow velocity (MAFV). This hypothesis can be validated mathematically only if the aortic area (AA index) indexed to body surface area (BSA) remains constant and if the relationship between aortic diameter (PhiAo) and BSA is nonlinear. However, several other equations have described the relationship between BSA and, respectively, PhiAo and aortic area (AA) in children. The aim of this study was to determine if the relationships calculated between BSA and aortic size in children (without left ventricular outflow tract abnormality) could validate the hypothesis that MAFV and CI are well linked linearly, leading to its use to determine CI. METHODS: Two hundred and thirty-two measurements performed in 126 children and infants were retrospectively analysed. PhiAo was measured in the long axis view at the annulus using two-dimensional mode echocardiography with a 5-MHz transducer. Various linear and nonlinear relationships between BSA and, respectively, PhiAo, PhiAoindex, AA and AAindex were determined based on a nonlinear regression method with a model as follows: y=a(xc) + b. The comparisons between regressions were conducted based on the estimation error. RESULTS: The relationships between PhiAo and BSA appeared nonlinear and was well described by: PhiAo=2.96(BSA1/4) - 1.31 with a non-zero y-intercept and PhiAo=1.64(BSA1/2) with a zero y-intercept. In contrast, the relationships between AA and BSA were linear. The AAindex was not linked to BSA and can be considered as constant. The coefficient a of the equation appeared similar to those obtained mathematically with the relationship previously described between MAFV and CI. CONCLUSIONS: The hypothesis that CI can be extrapolated to the measurement of MAFV appears valid as regards the relationships calculated between aortic size and BSA in children without left ventricular outflow tract abnormality.

Adolescent↗

PubMed2002

Alkalinization of intracuff lidocaine improves endotracheal tube-induced emergence phenomena.

UNLABELLED: We sought to evaluate the effect of filling an endotracheal tube cuff with 40 mg lidocaine alone (Group L) or alkalinized lidocaine (Group LB) in comparison to an Air Control group (Group C) on adverse emergence phenomena in a randomized controlled study (n = 25 in each group). The incidence of sore throat was decreased for Group LB in comparison to Group L during the 24 postextubation hours. The difference between Group L and Group C remained significant in the two postextubation hours only. Plasma lidocaine levels increased when lidocaine was alkalinized (C(max) were 62.5 +/- 34.0 ng/mL and 3.2 +/- 1.0 ng/mL for Groups LB and L, respectively). Cough and restlessness before tracheal extubation were decreased in Group LB compared with Group L and in Group L compared with Group C. Nausea, postoperative vomiting, dysphonia, and hoarseness were increased after extubation in Group C compared with the liquid groups, and a better tolerance was recorded with Group LB compared with Group L. The increase of arterial blood pressure and cardiac frequencies during the extubation period was less in the liquid groups than in the control group and less in Group LB compared with Group L. We concluded that use of intracuff alkalinized lidocaine is an effective adjunct to endotracheal intubation. IMPLICATIONS: Use of 40 mg of alkalinized lidocaine, rather than lidocaine or air, to fill the endotracheal tube cuff reduces the incidence of sore throat in the postoperative period. This approach also decreases hemodynamic effects, restlessness, dysphonia, and hoarseness.

Anesthesia Recovery Period↗

PubMed2002

The effect of local anesthetics and amitriptyline on peroxidation in vivo in an inflammatory rat model: preliminary reports.

We studied the inhibition of peroxidation by local anesthetics in an inflammatory animal model. Inflammatory lipid peroxidation was assessed by the thiobarbituric assay in plasma from rats injected or not injected with carrageenan (Carra) and killed 1, 2, 4, 6, 12, and 24 h thereafter. Thiobarbituric acid reactive substances (TBARS) values in inflammatory animals were maximal 6 h after Carra administration. This result, in accordance with the evolution of paw edema width during time, supports that TBARS reflect the intensity of inflammation. Local anesthetics (bupivacaine, lidocaine, ropivacaine, or bupivacaine-loaded microspheres) or amitriptyline were injected in clinically relevant concentrations as a sciatic nerve block or intraperitoneally in inflamed animals. Ropivacaine did not exhibit any protective effect on Carra-induced lipid peroxidation in rats. With all the other drugs administered as a sciatic nerve block, the maximal TBARS increase was not observed at 6 h. Our conclusion is that bupivacaine (plain or encapsulated), lidocaine, and amitriptyline in clinically relevant concentrations administered via the sciatic nerve showed antioxidant properties toward lipid peroxidation induced by Carra inflammation. Intraperitoneal injection of those drugs gave the same effect as nerve block; this result suggests that their mechanism of action is not strictly limited to the nerve. IMPLICATIONS. We investigated the antioxidant effects of local anesthetics and amitriptyline in an inflammatory rat model. Amitriptyline exhibits antioxidant properties per se, whereas lidocaine and bupivacaine (plain or encapsulated) seem to inhibit the peroxidation process. This may have future application in limiting toxic oxygen metabolite production during the inflammatory process.

Amides↗

PubMed2002

Major complications of regional anesthesia in France: The SOS Regional Anesthesia Hotline Service.

BACKGROUND: Several previous surveys have estimated the rate of major complications that occur after regional anesthesia. However, because of the increase in the use of regional anesthesia in recent years and because of the introduction of new techniques, reappraisal of the incidence and the characteristics of major complications is useful. METHODS: All French anesthesiologists were invited to participate in this 10-month prospective survey based on (1) voluntary reporting of major complications related to regional anesthesia occurring during the study period using a telephone hotline service available 24 h a day and managed by three experts, and (2) voluntary reporting of the number and type of regional anesthesia procedures performed using pocket booklets. The service was free of charge for participants. RESULTS: The participants (n = 487) reported 56 major complications in 158,083 regional anesthesia procedures performed (3.5/10,000). Four deaths were reported. Cardiac arrest occurred after spinal anesthesia (n = 10; 2.7/10,000) and posterior lumbar plexus block (n = 1; 80/10,000). Systemic local anesthetic toxicity consisted of seizures only, without cardiac toxicity. Lidocaine spinal anesthesia was associated with more neurologic complications than bupivacaine spinal anesthesia (14.4/10,000 vs. 2.2/10,000). Most neurologic complications were transient. Among 12 that occurred after peripheral nerve blocks, 9 occurred in patients in whom a nerve stimulator had been used. CONCLUSION: This prospective survey based on a free hotline permanent telephone service allowed us to estimate the incidence of major complications related to regional anesthesia and to provide a detailed analysis of these complications.

Acute Disease↗

PubMed2001

Impedance cardiographic waveforms in children: Involvement in left ventricular ejection time determination during anesthesia.

OBJECTIVE: The physiologic basis of the impedance cardiographic (ICG) signal is still a matter of debate. An accurate determination of left ventricular ejection time (LVET) is needed to calculate stroke volume. In children, several shapes of the ICG signal are observed during anesthesia or in critical care. The aim of this study was to determine the relationship between the shape of the ICG signal and various morphologic and hemodynamic determinants obtained with Doppler echocardiography to highlight the effect of the various shapes in the accuracy of LVET determination. DESIGN: Prospective study. SETTING: Pediatric surgery in a university hospital. PATIENTS: 103 children, ASA physical status I or II. INTERVENTIONS: General anesthesia for elective surgery. Measurements: Electrocardiography, ICG, and Doppler echocardiography were recorded simultaneously. Classic hemodynamic variables, such as heart rate, LVET, stroke volume, or systemic vascular resistance, were measured or calculated. A mathematical model of the ICG signal was used to determine the shape of the ICG signal and its potential relationship to various morphologic and hemodynamic determinants. The ICG signal shape was then modeled with the normalized amplitudes (NHA) and phase (NHP) of the three harmonics of the fundamental signal. Analysis was performed with a multiple correspondence analysis. RESULTS: ICG method LVET did not significantly correlate with LVET determined with Doppler or with heart rate. NHA and NHP of the ICG signal were not significantly related to LVET determined with Doppler or to stroke volume. NHA were linked to heart rate and the relative length of the cardiac diastolic period. CONCLUSION: The absence of relationship between LVET determined with Doppler and the main variables defining the shape of the ICG signal highlight the relative limit of stroke volume determination with ICG method. The involvement of the arterial compliance in the ICG signal shape can be discussed in regard to the links between NHA and both heart rate and the relative length of the cardiac diastolic period, respectively.

Journal Article↗

PubMedDate not supplied

Sciatic nerve block with bupivacaine-loaded microspheres prevents hyperalgesia in an inflammatory animal model.

PURPOSE: The aim of this study was to evaluate the effect of different durations of local anesthetic neural blockade on hyperalgesia after carrageenan infiltration in a rat model. METHODS: Inflammation was obtained by injection of carrageenan in the righ hind paw. Hyperalgesia was determined by measuring the threshold of response to increasing mechanical stimuli on the contralateral and on the ipsilateral paw. The development of edema was measured. After identification of the sciatic nerve by nerve stimulation, blockade was performed either one hour before or after carrageenan infiltration. Animals were randomly assigned into three groups: without sciatic nerve block (control group; n = 20), block with bupivacaine (B) and block with bupivacaine-loaded microspheres (B-Ms) injection before or after carrageenan infiltration (n = 10 for each group). RESULTS: Carrageenan infiltration in the control group induced a severe ipsilateral and contralateral hyperalgesia. After blockade with B (duration = 2 +/- 0.5 hr) hyperalgesia was present and delayed only by the duration of the local anesthetic effect. A longer duration of block achieved with B-Ms (duration greater than five hours), was associated with the absence of development of both ipsilateral and contralateral hyperalgesia. No preemptive effect was recorded. CONCLUSION: B-Ms as a drug delivery system prolongs the duration of neural blockade and avoids hyperalgesia phenomena in this rat model of inflammation.

Anesthetics, Local↗

PubMedDate not supplied

Comparison of heart rate response to an epinephrine test dose and painful stimulus in children during sevoflurane anesthesia: heart rate variability and beat-to-beat analysis.

BACKGROUND AND OBJECTIVES: During regional anesthesia, various stimuli leading to an adrenergic response can occur. However, simulation of an epidural test dose by using intravenous administration of epinephrine (EPI) has always been compared with an intravenous saline infusion as the control. The aim of this study was to evaluate the possibility of distinguishing in children the effect on HR by an intravascular epinephrine infusion and a painful stimulus, using heart rate variability (HRV) and beat-to-beat analysis of HR. METHODS: Thirty American Society of Anesthesiologists physical status P I children who required elective surgery were studied. At 1 minimum alveolar concentration (MAC) of sevoflurane, electrocardiogram was recorded continuously. Systolic blood pressure (SBP) was measured every minute. Measurements were performed after an intravenous administration of 0.5 microg/kg of epinephrine and during a small skin surgical incision (SI). Time-varying auto-regressive modeling of the interpolated RR sequences was performed for estimating power spectrum (msec(2)). The HF bands were defined by (0.15-0.4 Hz). RESULTS: Median (range) age and weight of all children were 3.5 (1-10) years and 16 (9-30) kg. EPI produced a lower increase in HR than did SI. SBP increased significantly more than did after SI. T-wave amplitude increased significantly after EPI but not after SI. Sixty seconds after the first change in HR, a secondary decrease (in comparison to control value) can be detected with EPI in contrast to SI. HF spectral power increased significantly after EPI administration but decreased after SI. The sensitivity, specificity, and positive and negative predictive value were respectively for DeltaHR >10 beats per minuteof 56%, 26%, 43%, and 38%; for DeltaSBP >15 mm Hg of 60%, 86%, 81%, and 67%; and for DeltaT-wave amplitude >25% of 86%, 73%, 76%, and 84%. Using detection of the secondary decrease of HR, 60 seconds after the first change in HR, sensitivity, specificity, and positive and a negative predictive value were respectively 96%, 100%, 100%, and 96%. CONCLUSIONS: Detection of the secondary HR decrease, 60 seconds after the first change in HR, allows us to distinguish the effects of a painful stimulus from those related to the epinephrine test dose at 1 MAC of sevoflurane. This secondary HR decrease induced by epinephrine appears primarily because of a compensatory increase in parasympathetic tone.

Adrenergic Agonists↗