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Biomedical subjects

I Murat

Publications and source records attributed to I Murat.

At least 19 recordsLinked to original sources
PubMed2006

Reflex pupillary dilatation in response to skin incision and alfentanil in children anaesthetized with sevoflurane: a more sensitive measure of noxious stimulation than the commonly used variables.

BACKGROUND: Estimation of analgesia in anaesthetized children is often imprecise, and consequently, anaesthesiologists commonly evaluate children's response to surgical stimulation by movement or haemodynamic changes. In adults reflex pupillary dilatation has been demonstrated to be a very sensitive measure of noxious stimulation, correlated with opioid concentrations. The autonomic nervous control changes with age, raising the hypothesis that mechanisms involved in pupillary autonomic functions regarding both sympathetic and parasympathetic components may also differ between adults and children. In this pilot study, we tested the hypothesis that the pupillary reflex dilatation might allow assessment of noxious stimulation and analgesic effect of alfentanil in children under sevoflurane anaesthesia, as an alternative to haemodynamic and bispectral measures. METHODS: After sevoflurane induction, 24 children were maintained in steady-state conditions at 1.5 MAC of sevoflurane in O(2)-N(2)O (50-50). An intense noxious stimulation was provided by standardized skin incision on the lower limb. A bolus of alfentanil (10 microg kg(-1)) was administered either 1 min (n=16) or 2 min (n=8) after skin incision. Haemodynamic values, bispectral index (BIS) and pupillary diameter (PD) were recorded just before stimulation and at 30-60 s intervals during 4 subsequent minutes. RESULTS: In all children PD increased significantly after noxious stimulation [+200 (40)%, at 60 s]. In contrast, mean heart rate and blood pressure increased only 11 (7)% and 10 (8)% respectively, 60 s after stimulation. BIS did not change significantly. In all children, alfentanil injection induced a rapid decrease of PD and restored pre-incision values in 2 min. CONCLUSION: PD is a more sensitive measure of noxious stimulation than the commonly used variables of heart rate, arterial blood pressure and BIS in children anaesthetized with sevoflurane.

Adolescent↗
PubMed2005

Tolerance and analgesic efficacy of a new i.v. paracetamol solution in children after inguinal hernia repair.

BACKGROUND: A new intravenous (i.v.) formulation of paracetamol and propacetamol (prodrug of paracetamol) were compared to determine tolerance and relative analgesic efficacy during the first 6 h after inguinal hernia repair performed under general anesthesia combined with ilioinguinal block in children. METHODS: A total of 183 ASA I or II in-patients, aged 1-12 years, admitted for unilateral inguinal hernia repair were randomized to receive in a double-blind design either i.v. paracetamol 15 mg.kg(-1) (n = 95) or propacetamol 30 mg.kg(-1) (n = 88) for postoperative pain relief as soon as pain intensity was greater than 30 on a 100 mm visual analog scale. All patients were evaluated for efficacy and tolerance. Efficacy was evaluated between 15 min and 6 h after the start of the 15 min infusion. RESULTS: The most frequently reported adverse event was injection site pain, which was significantly reduced in the new formulation group (i.v. paracetamol 14.7% vs propacetamol 33.0% of children, P = 0.005). No significant difference was obtained between treatments on pain relief (PR), pain intensity difference (PAID) from baseline, and objective pain scale intensity difference (OPSD). Also, treatment effects did not differ significantly for maximum values and weighted sums of PR, PAID (investigator and child rated), OPSD, time to first request for rescue medication, proportion of children requesting rescue medication, and investigators' global treatment satisfaction. CONCLUSION: A single infusion of i.v. paracetamol 15 mg.kg(-1) produced analgesia similar to a single infusion of propacetamol 30 mg.kg(-1) following inguinal hernia repair in children. Paracetamol i.v. 15 mg.kg(-1) was better tolerated at the injection site than propacetamol.

Acetaminophen↗
PubMed2004

Agitation and changes of Bispectral Index and electroencephalographic-derived variables during sevoflurane induction in children: clonidine premedication reduces agitation compared with midazolam.

BACKGROUND: This double-blind randomized study was undertaken to assess agitation, Bispectral Index (BIS) and EEG changes during induction of anaesthesia with sevoflurane in children premedicated with midazolam or clonidine. METHODS: Children were allocated randomly to receive rectal midazolam 0.4 mg kg(-1) (n=20) or oral clonidine 4 microg kg(-1) (n=20) as premedication. Rapid induction of anaesthesia was achieved with inhalation of sevoflurane 8% in nitrous oxide 50%-oxygen 50%. After tracheal intubation, the children's lungs were mechanically ventilated and the inspired sevoflurane concentration was adjusted to achieve an end-tidal fraction of 2.5%. The EEG and BIS were recorded during induction until 10 min after tracheal intubation. The EEG was analysed using spectral analysis at five points: baseline, loss of eyelash reflex, 15 s before the nadir of the BIS (BIS(nadir)), when both pupils returned to the central position (immediately before intubation), and 10 min after intubation. RESULTS: Agitation was observed in 12 midazolam-treated and five clonidine-treated patients (P=0.05). At baseline, EEG rhythms were slower in the clonidine group. Induction of anaesthesia was associated with similar EEG changes in the two groups, with an increase in total spectral power and a shift towards low frequencies; these changes were maximal around the end of the second minute of induction (BIS(nadir)). When the pupils had returned to the central position, fast EEG rhythms increased and BIS was higher than BIS(nadir) (P<0.05). In both groups, agitation was associated with an increase in slow EEG rhythms at BIS(nadir). CONCLUSIONS: Compared with midazolam, clonidine premedication reduced agitation during sevoflurane induction. During induction with sevoflurane 8% (oxygen 50%-nitrous oxide 50%), the nadir of the BIS occurred at the end of the second minute of inhalation. Agitation was associated with a more pronounced slowing of the EEG rhythms at BIS(nadir) compared with inductions in which no agitation was observed. The BIS may not follow the depth of anaesthesia during sevoflurane induction in children.

Adjuvants, Anesthesia↗
PubMed2003

[Airway protection in children with a full stomach].

Recent surveys have reevaluated the risk of aspiration of gastric content during anesthesia in pediatric patients. Emergency, bowel obstruction and inadequate depth of anesthesia are the main high-risk situations. Airway protection requires the placement of cuffed tracheal tube. Cuffed tubes were considered as non-useful in children aged less than 6 to 8 years. They are however more frequently employed even in infants. Internal diameter of cuffed tubes should be reduced compared to uncuffed tubes. It is recommended to monitor cuff pressure if nitrous oxide is used during anesthesia. Crash induction is described with special reference to pediatric specificities.

Anesthesia, Inhalation↗
PubMed2003

Perioperative infusions in paediatric patients: rationale for using Ringer-lactate solution with low dextrose concentration.

To assess the usefulness of Ringer-lactate solution with 0.9% dextrose, fluid therapy during surgery in paediatric patients was reviewed. From the literature, the need for intravenous (i.v.) infusion and water could be established. The need for sodium was also evident and use of normonatraemic i.v. solutions should be recommended to avoid hyponatraemia. Little data were found about the value of the other electrolytes. Dextrose requirements have been the subject of debate for the last two decades. The choice of dextrose concentration is a compromise between avoiding hypoglycaemia and hyperglycaemia. Four clinical trials assessing the use of Ringer-lactate solution with 0.9 or 1% dextrose in paediatric patients suggest that it is appropriate for routine infusion in paediatric patients during the perioperative period. However, fluid therapy during surgery has rarely been studied, probably because it is inexpensive, rarely leads to problems and is used in very different clinical settings. Development of consensus clinical guidelines on the use of electrolyte infusions in paediatric surgery would be helpful.

Blood Glucose↗
PubMed2003

Remifentanil infusion for cleft palate surgery in young infants.

BACKGROUND: The residual depressant effect of opioid is a major concern in infants scheduled for cleft palate repair. Remifentanil is associated with a fast and predictable recovery, independent of age. METHODS: About 40 infants in the 2-12 month age range were prospectively enrolled in this open study, to receive either remifentanil (infusion starting at 0.25 microg x kg(-1) x min(-1)) or sufentanil as part of a balanced anaesthesia regimen. Isoflurane was maintained at an endtidal concentration of 1.2% in oxygen and nitrous oxide and the opioid dosing was titrated to autonomic responses. Postoperative pain relief was provided by morphine infusion. Morphine administration started intraoperatively in the remifentanil group. RESULTS: Consistent haemodynamic stability was achieved throughout surgery in both groups. Infants of the remifentanil group required, on average, lower concentrations of isoflurane than children of the sufentanil group (1.2 +/- 0.2% vs 1.7 +/- 0.3%, P < 0.001). The median time from last suture to tracheal extubation was 12.5 min (5-25 min) in the remifentanil group and 15.0 min (10-30 min) in the sufentanil group. There was no evidence of hyperalgesia or enhanced morphine consumption in the remifentanil group compared with the sufentanil group. Postoperative pain scores were even lower in the remifentanil group, compared with the sufentanil group, soon after arrival in the postanaesthesia care unit. CONCLUSIONS: Remifentanil-based anaesthesia appeared well suited for primary cleft palate repair in young infants.

Analgesics, Opioid↗
PubMed2002

Non-invasive assessment of cardiovascular autonomic activity induced by brief exposure to 50% nitrous oxide in children.

BACKGROUND: The use of the equimolecular mixture of oxygen and nitrous oxide is widely recommended for relief of pain in children undergoing minor procedures. Although the benefits and adverse effects of the clinical use of nitrous oxide seem well known, its effects on the autonomic nervous system have never been studied in children. The aim of this study was to evaluate changes in autonomic cardiovascular activity induced by brief exposure to 50% nitrous oxide in children. This study was based on non-invasive continuous recordings of RR-interval and non-invasive arterial pressure. Vascular and cardiac sympathetic activity and cardiac parasympathetic activity were investigated using spectral analysis of systolic arterial pressure variability (SAPV) and RR-interval variability (RRIV). In addition, the sensitivity of the spontaneous baroreflex (SBR) was assessed using the sequences and the cross-spectral analysis methods. METHODS: Sixteen non-pre-medicated pre-pubertal children undergoing middle-ear surgery, were studied. Data analysis was performed at three points: baseline, when the end-tidal concentration of nitrous oxide was stabilized at 50%, and after withdrawing nitrous oxide. Low (0.04-0.14 Hz) and high frequency (0.2-0.6 Hz) components of the spectral power of RRIV and SAPV, and SBR sensitivity were calculated using these 2-min data epochs. RESULTS: Our results show that brief exposure to 50% nitrous oxide in children results in: (1) absence of effect on mean AP and SAPV; (2) attenuation of the low frequency component of heart rate variability with a shift of the sympathetic-parasympathetic cardiac balance toward a parasympathetic predominance; and (3) absence of alteration of spontaneous baroreflex sensibility. CONCLUSIONS: Unlike the results demonstrated in adults, our findings show very few cardiovascular effects of nitrous oxide in children. Furthermore, whereas in adults nitrous oxide is associated with an excitatory cardiovascular profile, in children this agent seems to be associated with a depressant cardiovascular profile. The rapid return to baseline after discontinuation of administration and the absence of baroreflex changes are positive attributes for the use of nitrous oxide in children.

Anesthetics, Inhalation↗
PubMed2001

Adverse events of premixed nitrous oxide and oxygen for procedural sedation in children.

In France, administration of premixed 50% nitrous oxide and oxygen for procedural sedation is under close supervision by the French Drug Agency before final approval for use. We have examined the frequency of adverse events in children sedated with 50% nitrous oxide and oxygen over a broad range of non-specialised facilities. A mean of 0.33% (SD 0.10) children had major adverse events. Thus, premixed 50% nitrous oxide and oxygen seems to be a safe option for procedural sedation in children.

Adolescent↗
PubMed2001

Analgesic effect of low-dose intrathecal morphine after spinal fusion in children.

BACKGROUND: This study was designed to assess the postoperative analgesic effect of low-dose intrathecal morphine after scoliosis surgery in children. METHODS: Thirty children, 9-19 yr of age, scheduled for spinal fusion, were randomly allocated into three groups to receive a single dose of 0 (saline injection), 2, or 5 microg/kg intrathecal morphine. After surgery, a patient-controlled analgesia device (PCA) provided free access to additional intravenous morphine. Children were monitored for 24 h in the postanesthesia care unit. RESULTS: The three groups were similar for age, weight, duration of surgery, and time to extubation. The time to first PCA demand was dose-dependently delayed by intrathecal morphine. The first 24 h of PCA morphine consumption was 49 +/- 17, 19 +/- 10, and 12 +/- 12 mg (mean +/- SD) in the saline, 2 microg/kg morphine, and 5 microg/kg morphine groups, respectively. Pain scores at rest were significantly lower over the whole study period after 2 and 5 microg/kg intrathecal morphine than after saline, but there was no difference between intrathecal doses. Pain scores while coughing and the incidence of side effects were similar in the three groups. CONCLUSIONS: These data demonstrate that low-dose intrathecal morphine supplemented by PCA morphine provides better analgesia than PCA morphine alone after spinal fusion in children. The doses of 2 and 5 microg/kg seem to have similar effectiveness and side-effect profiles, whereas a reduction of intraoperative bleeding was observed in patients who received 5 microg/kg but not 2 microg/kg intrathecal morphine.

Adolescent↗
PubMed2001

Sedation and analgesia for procedures outside the operating room in children.

There has been a dramatic increase in the number of procedures that are conducted in children in which sedation is now considered beneficial. In many institutions, however, resources and personnel have not been recruited to address this increase in demand. In most institutions, anaesthesiology departments are not able to provide anaesthesia for all procedures that are performed outside the operating theatre, and alternative solutions are needed. Recent research includes attempts to decrease the time required to induce sedation and to recover from it, and development of new organizational models to improve the safety of procedural sedation.

Journal Article↗
PubMed2000

Comparison of remifentanil versus regional anaesthesia in children anaesthetised with isoflurane/nitrous oxide. International Remifentanil Paediatric Anaesthesia Study group.

We compared the efficacy and safety of a remifentanil (0.25 microg x kg(-1) x min(-1)-based balanced anaesthetic technique with a bupivacaine-based regional anaesthetic technique in an open label, multicentre study in 271 ASA physical status 1 or 2 children aged 1-12 years. Subjects requiring major intra-abdominal, urological or orthopaedic surgery were randomly allocated to receive either intravenous remifentanil (group R; n = 185) or epidural bupivacaine (group B; n = 86) with isoflurane/nitrous oxide for their anaesthesia. The majority of children in both groups (85% in group R, 78% in group B) showed no defined response to skin incision, and although the mean increase in systolic blood pressure (+11 mm Hg) was significantly greater in group R than in group B, this change did not represent a serious haemodynamic disturbance. More children in group R (31%) required interventions to treat hypotension and/or bradycardia than those in group B (12%), but these were easily managed by administration of fluids or anticholinergic drugs. Adverse events, mainly nausea and/or vomiting, occurred in 45% of group R and 42% of group B (NS). The adverse event profile of remifentanil in this study was typical of a potent mu-opioid receptor agonist. Remifentanil was as effective as epidural or caudal block in providing analgesia and suppressing physiological responses to surgical stimuli in children aged between 1 and 12 years undergoing major abdominal, urological, or orthopaedic surgery under isoflurane/nitrous oxide anaesthesia.

Analgesia, Epidural↗
PubMed2000

Assessment of autonomic cardiovascular changes associated with recovery from anaesthesia in children: a study using spectral analysis of blood pressure and heart rate variability.

Recovery from anaesthesia is associated with large changes in cardiovascular autonomic activity, which are poorly documented in children. This study was undertaken to investigate the cardiovascular autonomic activity in anaesthetized and recovering children, using a noninvasive approach based on spectral analysis of heart rate (HR) and blood pressure (BP) variability. Ten children (aged 5-13 years) undergoing major surgery were studied. Continuous HR and BP were recorded using a noninvasive device during deep anaesthesia and recovery. Spectral analysis was used to determine the main oscillatory components of HR and BP signals. For each power spectrum, the frequency components were identified as follows (i): the low frequency (LF) component (0.04-0.14 Hz) both parasympathetically and sympathetically mediated for HR and corresponding to vasomotor sympathetic modulation for BP; and (ii) the high frequency (HF) component (0.2-0.6 Hz) parasympathetically mediated for HR, and reflecting mechanical influence of ventilation on cardiac output for BP. In addition, the LF : HF ratio for HR, reflecting the cardiac sympathovagal balance, was calculated. Under deep anaesthesia, HR variability and BP variability were very low and mainly due to mechanical influence of intermittent positive pressure ventilation. Conversely, the recovery period was associated with a marked increase of HR and BP overall variability. Compared to anaesthesia, spectral analysis of HR and BP revealed that the LF component of BP and HR spectra increased 40-fold during recovery; the LF : HF ratio of HR was also increased during recovery (0.1 +/- 0.1 versus 1.3 +/- 1.2, P=0.008). The results of this study demonstrate that the recovery period is associated with an increase of cardiovascular sympathetic drive in children after major surgery.

Adolescent↗