Remifentanil

Effects of remifentanil on processing of auditory stimuli: a combined MEG/EEG study

Remifentanil (Ultiva(®)) is a potent ultra-short acting mu-opioid receptor agonist used for perioperative pain treatment and anaesthesia. So far, it is not known how sensitive the cognitive processing of auditory perception elicited by the mismatch negativity (MMN) paradigm is to opioids. The present exploratory study investigated how the opioid remifentanil modulates different stages of auditory processing as reflected in the MMN(m) and P3a(m). We recorded electroencephalography (EEG) and magnetoencephalography (MEG) during auditory stimulation under remifentanil or placebo infusion in 20 healthy participants. For the MMN, a gender effect was found for tones deviating in frequency (± 10%) from the standard tone. Remifentanil increased the amplitude of the frequency MMN at F3 in females but not in males. No effect of treatment was found for the MMN(m) or the novel P3a(m). These results suggest that while the bottom-up stimulus change detection system for auditory stimuli appears to be relatively insensitive to opioids, the automatic attention switch caused by the change detection seems to be modulated by the opioid system in females. The multiple deviant paradigm including novel sounds is a promising tool for investigating pharmacological manipulation of different stages of auditory processing. Furthermore, combining the two techniques will yield more specific information about the drug effects on MMN(m).

Remifentanil produces cross-desensitization and tolerance with morphine on the mu-opioid receptor

Remifentanil is a powerful mu-opioid (MOP) receptor agonist used in anaesthesia with a very short half-life. However, per-operative perfusion of remifentanil was shown to increase morphine consumption during post-operative period to relieve pain. In the present study, we aimed to describe the cellular mechanisms responsible for this apparent reduction of morphine efficacy. For this purpose, we first examined the pharmacological properties of both remifentanil and morphine at the MOP receptor, endogenously expressed in the human neuroblastoma SH-SY5Y cell line, to regulate adenylyl cyclase and the MAP kinase ERK1/2 pathway, their potency to promote MOP receptor phosphorylation, arrestin 3-CFP (cyan fluorescent protein) recruitment and receptor trafficking during acute and sustained exposure. In the second part of this work, we studied the effects of a prior exposure of remifentanil on morphine-induced inhibition of cAMP accumulation, activation of ERK1/2 and analgesia. We showed that sustained exposure to remifentanil promoted a rapid desensitization of opioid receptors on both signalling pathways and a pretreatment with this agonist reduced signal transduction produced by a second challenge with morphine. While both opioid agonists promoted Ser(375) phosphorylation on MOP receptor, remifentanil induced a rapid internalization of opioid receptors compared to morphine but without detectable arrestin 3-CFP translocation to the plasma membrane in our experimental conditions. Lastly, a cross-tolerance between remifentanil and morphine was observed in mice using the hot plate test. Our in vitro and in vivo data thus demonstrated that remifentanil produced a rapid desensitization and internalization of the MOP receptor that would reduce the anti-nociceptive effects of morphine.

Quality of surgical field during endoscopic sinus surgery: a systematic literature review of the effect of total intravenous compared to inhalational anesthesia

BACKGROUND

Adequate surgical field visualization is imperative for successful outcomes in endoscopic sinus surgery (ESS). The type of anesthetic administered can alter a patient's hemodynamics and impact endoscopic visualization during surgery. We review the current evidence regarding the effect of total intravenous anesthesia (TIVA) compared to inhalational anesthesia (INA) on visualization of the surgical field during ESS.

METHODS

A systematic review of the literature was performed. Ovid MEDLINE, Scopus, and Cochrane databases were searched from 1946 to January 2012. Citations from the primary search were reviewed and filtered to identify all relevant abstracts in English. Articles meriting full review included prospective controlled trials enrolling adult patients undergoing ESS that were randomized to a group receiving INA or TIVA with outcome measures focused on surgical field visualization.

RESULTS

Seven eligible trials fulfilled inclusion criteria. Four of the 7 demonstrated a statistically significant improvement in surgical field grade during ESS when receiving TIVA compared with INA. However, detailed INA concentrations were often not provided. High levels of INA may have been administered; therefore, side effects of INA rather than effects of an ideal INA administration were possibly represented. Analgesic administration also varied widely among the anesthetic groups, further complicating interpretation of study results. The lack of power and the heterogeneity of the studies precluded a formal meta-analysis.

CONCLUSION

Although several studies reported that TIVA improves surgical conditions in ESS, there are significant limitations. These findings prevent any definite recommendation at this point, emphasizing the need for further high-quality studies.

Low-Dose Remifentanil Infusion during Ventilator Weaning and Tracheal Extubation in Postoperative Intensive Care Unit Patients Sedated with Propofol-Remifentanil: A Randomised Clinical Trial

Discontinuation of sedatives for ventilator weaning and extubation can be associated with hyperdynamic responses, including hypertension and tachycardia. We examined the effects of a maintained low dose of remifentanil infusion on cardiovascular responses and coughing during extubation in postoperative intensive care unit patients sedated with propofol-remifentanil.

Fifty patients who required mechanical ventilation after major abdominal surgery were randomised into remifentanil group (n=25) or control group (n=25). Sedation during mechanical ventilation was maintained with remifentanil and propofol via a target-controlled infusion system. These drugs were titrated to the target sedation range, bispectral index values of 60 to 75 and Richmond Agitation Sedation Scale values of −3 to −2. When weaning was initiated, propofol was stopped in both groups. In the control group, remifentanil infusion was also stopped; in the remifentanil group, remifentanil infusion was maintained until extubation at a target effect site concentration of 1.0 ng/ml. Extubation was performed if the patient's respiratory, haemodynamic states were stable and if the patient was able to follow commands. Heart rate, mean arterial pressure and cough severity were evaluated.

The mean arterial pressure, heart rate and cough severity did not differ between the two groups during extubation. The time from stopping of propofol infusion to extubation was significantly longer in the remifentanil group compared to that in the control group (P=0.020).

Maintaining a low-dose remifentanil infusion during ventilator weaning delayed tracheal extubation without any differences in haemodynamic changes or coughing in postoperative intensive care unit patients.

Pharmacology in the elderly and newer anaesthesia drugs

In developed countries, a growing proportion of patients presenting for anesthesia and surgery are elderly. Despite this, and the fact that aging is known to be associated with alterations in drug pharmacokinetics and dynamics, there is little detailed information about the impact of aging on the pharmacology of commonly used anesthetic agents. In this review, we discuss existing current knowledge on the physiological changes that occur with age and the way these changes affect the pharmacokinetics and dynamics of anesthetic agents. Also, an overview of up-to-date PK-PD modeling concepts and their usefulness and limitations in modern anesthesiologic practice with respect to the elderly population is given. Finally, newer agents such as sugammadex, remifentanyl, ropivacaine and desflurane are discussed in detail with emphasis on current evidence concerning dosing, safety and efficacy of their use in the elderly.

Delayed awakening following inadvertent high-dose remifentanil infusion in a 13 year old patient

We report the case of a 13 year old patient who received 3.0 mg of remifentanil during a 50-minute surgical procedure as a result of a dosage miscalculation. The patient failed to awaken at the conclusion of the procedure and showed signs of opioid overdose. She recovered spontaneously two hours later.

A comprehensive LC-MS-based quantitative analysis of fentanyl-like drugs in plasma and urine

Fentanyl, norfentanyl, alfentanil, sufentanil, remifentanil and 3-methylfentanyl are potent, short-acting, synthetic narcotic analgesics that are not revealed in standard opiate immunoassays. In this article, a fully validated analytical method for the determination of these fentanyl-type compounds in plasma and urine is presented, consisting of a liquid-liquid extraction followed by a LC-MS/MS analysis using electrospray ionisation in the positive ionisation mode. Fentanyl-d(5) and norfentanyl-d(5) were used as internal standards. The lower LOQ in plasma and urine was 0.1 ng/mL for fentanyl, norfentanyl, alfentanil, remifentanil and 3-methylfentanyl, and 0.2 ng/mL for sufentanil. The method proved linear over a concentration range of 0.2-50 ng/mL for sufentanil and 0.1-50 ng/mL for all other analytes, with correlation coefficients of 0.998 or better. The analytical procedure showed excellent selectivity and precision (all CVs below 15%) for all analytes. Accuracy was good, except for sufentanil, where deviations of more than 15% from nominal concentrations were observed. No matrix effects were observed, and stability of stock and internal standard solutions was within acceptability limits.

Optimal effect-site concentration of remifentanil for preventing development of hypertension during tracheal intubation with inhaled desflurane induction

BACKGROUND

The aim of the present study was to determine the effect-site concentration of remifentanil needed to prevent haemodynamic instability during tracheal intubation with inhaled desflurane induction.

METHODS

One hundred American Society of Anesthesiologists I and II female patients were randomized to receive an effect-site concentration of remifentanil of 0, 1, 2, 3, or 4 ng/ml. Induction of anaesthesia was started with intravenous injection of propofol 2 mg/kg. Ninety seconds after the completion of propofol injection, rocuronium (0.8 mg/kg) and remifentanil were administered simultaneously with 3% desflurane inhalation. Tracheal intubation was attempted 150 sec after the commencement of remifentanil administration.

RESULTS

A probit model of remifentanil concentration was predictive of successful intubation without development of hypertension (P for goodness-of-fit = 0.419). The effect-site concentration of remifentanil needed to achieve successful intubation without development of hypertension in 95% of the patients was 3.3 ng/ml (95% confidence interval, 2.6-4.8 ng/ml).

CONCLUSIONS

The effect-site concentration of remifentanil of 3.3 ng/ml is effective in blunting the haemodynamic response in 95% of the patients when 2.0 mg/kg of propofol induction was followed by 3% desflurane inhalation.

Comparison of the effectiveness of lidocaine and salbutamol on coughing provoked by intravenous remifentanil during anesthesia induction

BACKGROUND

Coughing is a side effect of opioids that is rarely studied. Here, we evaluated the incidence of remifentanil induced coughing during anesthesia induction in an attempt to identify its risk factors and to examine the preventive effects of lidocaine and salbutamol.

METHODS

A total of 237 patients scheduled to undergo general anesthesia were allocated randomly into three groups. Group C received no medication, while Group L received 2% lidocaine at 0.5 mg/kg intravenously 1 minute prior to remifentanil infusion and Group S inhaled one metered aerosol puff of salbutamol 15 minutes prior to entering the operating room. Remifentanil was infused at 5 ng/ml by target controlled infusion and coughing was measured for five minutes and graded as none, mild, moderate, or severe based on the number of coughs.

RESULTS

The incidences of coughing were 30.4%, 25.3%, and 35.4% in Groups C, L, and S, respectively. The incidences, onset times, and severity of coughing did not differ significantly among groups. In addition, multivariate analysis showed that non-smoking and a lower body weight were risk factors of remifentanil-induced coughing (odds ratio, 8.13; P = 0.024, 1.11, and 0.004, respectively).

CONCLUSIONS

The incidence of remifentanil-induced coughing was 30%. A total of 0.5 mg/kg lidocaine and 1 metered aerosol puff of salbutamol did not prevent coughing. Non-smoking and low body weight were found to be risk factors of remifentanil-induced coughing.

Remifentanil versus fentanyl for esophagogastroduodenoscopy in children

OBJECTIVES

We compared sedation by propofol combined with either fentanyl or remifentanil in pediatric outpatients undergoing diagnostic esophagogastroduodenoscopy.

PATIENTS AND METHODS

Forty-two children scheduled for esophagogastroduodenoscopy in our institution were randomly assigned to receive 2 mg/kg propofol plus either 1 μg/kg bolus of fentanyl (group F; n = 20) or 0.5 μg/kg bolus of remifentanil (group R; n = 22). Cardiorespiratory parameters, sedation level, adverse effects related to the drugs and/or to the procedure, ease of performance for the endoscopist, and time to awakening were analyzed.

RESULTS

There were no clinically significant changes in hemodynamics. Apnea periods >20 seconds and decreases in SaO2 <90% occurred more frequently in group R (31.8% vs 0%, P < 0.01, and 27.3% vs 5.0%, P > 0.05, respectively). Children in group R had significantly shorter average time to awakening: 9.5 ± 5.6 vs 16.5 ± 10.5 minutes (P = 0.01), and received a significantly lower total dose of propofol (P = 0.034). Adverse effects within the first 24 hours postprocedure occurred less frequently in group R (P = 0.03).

CONCLUSIONS

Remifentanil in combination with propofol provides good analgesic and sedative effects, which were shorter lasting compared with fentanyl-based sedation, and caused fewer delayed adverse effects. The use of remifentanil was associated with respiratory depression, emphasizing the need for experienced anesthesiologists.

Advances in labor analgesia

The pain of childbirth is arguably the most severe pain most women will endure in their lifetimes. The pain of the early first stage of labor arises from dilation of the lower uterine segment and cervix. Pain from the late first stage and second stage of labor arises from descent of the fetus in the birth canal, resulting in distension and tearing of tissues in the vagina and perineum. An array of regional nerve blocks, systemic analgesic, and nonpharmacologic techniques are currently used for labor analgesia. Nonpharmacologic methods are commonly used, but the effectiveness of these techniques generally lacks rigorous scientific study. Continuous labor support has been shown to decrease the use of pharmacologic analgesia and shorten labor. Intradermal water injections decrease back labor pain. Neuraxial labor analgesia (most commonly epidural or combined spinal-epidural) is the most effective method of pain relief during childbirth, and the only method that provides complete analgesia without maternal or fetal sedation. Current techniques commonly combine a low dose of local anesthetic (bupivacaine or ropivacaine) with a lipid soluble opioid (fentanyl or sufentanil). Neuraxial analgesia does not increase the rate of cesarean delivery compared to systemic opioid analgesia; however, dense neuraxial analgesia may increase the risk of instrumental vaginal delivery.

Remifentanil versus fentanyl compared in a target-controlled infusion of propofol anesthesia: quality of anesthesia and recovery profile

PURPOSE

The aim of the present study was to compare the clinical properties of fentanyl versus remifentanil in a target-controlled infusion (TCI) of propofol anesthesia regimen with bispectral index (BIS) monitoring.

METHODS

Forty consenting patients scheduled for elective septorhinoplasty were prospectively studied as one of two groups: fentanyl (group F) or remifentanil (group R). After loading boluses of fentanyl 3 microg kg(-1) or remifentanil 1 microg kg(-1) were administered, the continuous infusion of fentanyl or remifentanil was started at a rate of 0.03 or 0.15 microg kg(-1) min(-1), respectively. Propofol infusion was then commenced with a 3 microg ml(-1) effect site concentration (Ce) by means of a TCI device. The Ce propofol was adjusted to keep BIS at 50 +/- 10.

RESULTS

The general mean value of propofol Ce for group F and group R was 4.0 and 3.5 microg ml(-1), respectively. As to the recovery profile, the eye opening time (mean, 6.7 vs. 4.6 min), extubation time (mean, 7.3 vs. 4.7 min), and orientation time (mean, 7.6 vs. 4.9 min) were found to be significantly longer in group F than in group R.

CONCLUSION

We concluded that in propofol-based TCI anesthesia under BIS supervision for septorhinoplasty operations, remifentanil was better than fentanyl, especially with respect to emergence from total intravenous anesthesia (TIVA). Furthermore, the durations of anesthesia and operation were rather short, which indicates that fentanyl can be safely used.

The incidence of cough induced by remifentanil during anesthetic induction was decreased by graded escalation of the remifentanil concentration

BACKGROUND

It is well known that opioids induce coughing. Many drugs such as lidocaine and ketamine are used to effectively prevent the coughing induced by opioids and this has been revealed to be effective. In this study, we evaluated the preventive effect of a graded escalation of the remifentanil concentration using a target controlled infusion pump and we compared this with the effect of lidocaine.

METHODS

One hundred fifty ASA I and II patients who were scheduled for elective surgery were randomly divided into 3 groups. The patients were pretreated with 2% lidocaine 1 mg/kg (Group L) or saline (Group S) and remifentanil infusion (an effect site concentration of 4.0 ng/ml) was followed 1 minute later by using a target controlled infusion pump. Group R was pretreated with saline and this was followed by remifentanil infusion (effect site concentration of 2.0 ng/ml at first and then it was reset to 4.0 ng/ml). We evaluated the incidence, severity and onset time of cough after remifentanil infusion.

RESULTS

The incidence of coughing was significantly decreased in Group R (6 cases, 12%) and Group L (7 cases, 14%), as compared to that of Group S (17 cases, 34%) (P < 0.05), but there was no significant difference between Group R and Group L. The groups showed no significant difference in the severity and the onset time of coughing.

CONCLUSIONS

This study demonstrated that administering graded escalation of the remifentanil concentration suppresses remifentanil-induced coughing as effectively as lidocaine 1 mg/kg pretreatment.

Alfentanil is comparable to remifentanil in preventing withdrawal movement following rocuronium injection

STUDY OBJECTIVE

To evaluate and compare the efficacy and related side effects of alfentanil and remifentanil in preventing the withdrawal movement associated with rocuronium injection.

DESIGN

Prospective, randomized, blinded, placebo-controlled clinical trial.

SETTING

Operating room of a university hospital.

PATIENTS

115 ASA physical status I and II adult patients.

INTERVENTIONS

Patients were randomly allocated to one of three study groups. Group C received saline, Group A received alfentanil 10 microg/kg, and Group R received remifentanil one microg/kg, each in a volume of three mL. Treatments were injected over 30 seconds, followed by thiopental sodium. At 90 seconds after the start of the study drug injection, rocuronium 0.6 mg/kg was injected over 10 seconds.

MEASUREMENTS

Cough, breathholding, and thoracic muscle rigidity were observed while injecting the study drug. Each patient's response to the rocuronium injection was graded on a 4-point scale in a blinded manner.

MAIN RESULTS

During injection of the study drug, Group R showed a significantly higher frequency of cough than Group A (24% vs. 2%; P < 0.05). One Group R patient presented with apnea. Frequency of withdrawal movement in Groups A and R were significantly lower than that in Group C (6% and 0% vs. 63%; P < 0.0001) but there was no significant difference between the two groups.

CONCLUSION

When administered 90 seconds before rocuronium injection, alfentanil showed a comparable effect to that of remifentanil in attenuating rocuronium-associated withdrawal movement, and a lower frequency of side effects such as cough.

Remifentanil decreases mandibular bone marrow blood flow during propofol or sevoflurane anesthesia in rabbits

PURPOSE

The purpose of this study was to investigate the effect of remifentanil on the blood flow in rabbit oral tissues during propofol or sevoflurane anesthesia.

MATERIALS AND METHODS

Thirty-two male tracheotomized Japanese white rabbits were anesthetized with propofol (P group) or sevoflurane (S group) under mechanical ventilation. Animals were further divided into 4 groups: adenosine triphosphate (ATP) treatment in the P group (P-ATP) (n = 8), remifentanil treatment in the P group (P-Remi) (n = 8), ATP treatment in the S group (S-ATP) (n = 8), and remifentanil treatment in the S group (S-Remi) (n = 8). Blood pressure, heart rate, common carotid artery blood flow (CABF), lingual mucosal blood flow (LMBF), and mandibular bone marrow blood flow (BMBF) were measured during each period before and during infusion of ATP or remifentanil.

RESULTS

Mean arterial pressure (MAP), CABF, LMBF, and BMBF showed a significant decrease in all 4 groups during infusion of the drug. Similarly, LMBF and BMBF showed significant decreases in both the ATP and remifentanil groups, whereas the decreases in MAP and CABF measured as percent change were greater in the ATP groups than in the remifentanil groups. A significant correlation was observed between CABF and BMBF in the S-Remi group. In both the P and S groups, the correlations between MAP and LMBF or BMBF were relatively strong when ATP was administered.

CONCLUSIONS

Our findings suggest that infusion of remifentanil during propofol or sevoflurane anesthesia reduces BMBF and LMBF, as does deliberate hypotension by use of ATP, without a major decrease in MAP.

The effect of remifentanil for reducing myoclonus during induction of anesthesia with etomidate

BACKGROUND

Myoclonic movement is a common problem during induction of anesthesia with etomidate. We investigated the influences of pretreatment with remifentanil on etomidate induced myoclonus.

METHODS

Ninety ASA class I patients were divided randomly into three groups. Group NS received normal saline 2 ml as placebo (n = 30), group R0.5 and group R1.0 were pretreated with remifentanil 0.5 microgram/kg (n = 30) or 1.0 microgram/kg (n = 30) 1 minute before induction with etomidate 0.3 mg/kg. Orotracheal intubation was performed after administration of rocuronium 0.5 mg/kg. We assessed the incidence, onset, duration and intensity of myoclonus. Mean arterial pressure (MAP), heart rate (HR) and bispectral index (BIS) were recorded during induction.

RESULTS

Twenty five patients developed myoclonus in group NS (83.3%), 3 patients in group R0.5 developed myoclonus (10%), as did 5 patients in group R1.0 (16.7%). Moderate to severe myoclonus of grade 3 and 4 were found 66.7% of patients in group NS, whereas no patients in both remifentanil pretreated groups developed this grade of myoclonus. The duration of myoclonus was reduced significantly in the remifentanil groups: 93.8 +/- 59.5 sec in group NS, 49.3 +/- 34.9 sec in group R0.5, 36.0 +/- 27.0 sec in group R1.0 (P < 0.05). HR was decreased by pretreatment with remifentanil prior to induction, while MAP and HR were decreased after induction with etomidate (P < 0.05). BIS changes were not different among the three groups. The dose dependent differences between the two remifentanil doses were not noticed.

CONCLUSIONS

Pretreatment with remifentanil significantly reduced the incidence, duration and intensity of etomidate induced myoclonus.

The effects of desflurane and propofol-remifentanil on postoperative hepatic and renal functions after right hepatectomy in liver donors

Various volatile anesthetics have been used in hepatectomy in living donors, and their effects on major organs have been extensively evaluated. However, the impact of total intravenous anesthesia (TIVA) on postoperative liver and renal functions after large liver resections has been less extensively investigated than that of volatile agents. The aim of this study was to compare the postoperative hepatic and renal functions between volatile anesthesia with desflurane and TIVA with propofol-remifentanil in living donors undergoing right hepatectomy. Seventy adult patients were randomly allocated into 2 groups: the desflurane group (n = 35) and TIVA group (n = 35). Aspartate aminotransferase, alanine aminotransferase, prothrombin time (PT), albumin, total bilirubin (TB), blood urea nitrogen (BUN), creatinine (Cr), BUN/Cr ratio, estimated glomerular filtration rate (GFR), platelet count, and hemoglobin levels were analyzed in the preoperative period, immediately after the operation, and on the first, second, third, fifth, seventh, and thirtieth postoperative days (PODs). Most of the liver function test results were not significantly different between the 2 groups. However, PT (international normalized ratio) and TB were significantly greater on POD 5 in the TIVA group. Among the renal function tests, Cr was significantly higher and estimated GFR was significantly lower on POD 1 in the TIVA group. The platelet counts and hemoglobin levels were similar between the 2 groups. In conclusion, the results of our study suggest that living related donors for liver transplant may have a better outcome following anesthesia with desflurane. However, further testing will be necessary to prove this hypothesis.

The place for short-acting opioids: special emphasis on remifentanil

Pain is among the worst possible experiences for the critically ill. Therefore, nearly all intensive care patients receive some kind of pain relief, and opioids are most frequently administered. Morphine has a number of important adverse effects, including histamine release, pruritus, constipation, and, in particular, accumulation of morphine-6-glucuronide in patients with renal impairment. Hence, it is not an ideal analgesic for use in critically ill patients. Although the synthetic opioids fentanyl, alfentanil, and sufentanil have better profiles, they undergo hepatic metabolism and their continuous infusion also leads to accumulation and prolonged drug effects. Various attempts have been made to limit these adverse effects, including daily interruption of infusion of sedatives and analgesics, intermittent bolus injections rather than continuous infusions, and selection of a ventilatory support pattern that allows more spontaneous ventilation. However, these techniques at best only limit the effects of drug accumulation, but they do not solve the problem. Another type of approach is to use remifentanil in critically ill patients. Remifentanil is metabolized by unspecific blood and tissue esterases and undergoes rapid metabolism, independent of the duration of infusion or any organ insufficiency. There are data indicating that remifentanil can be used for analgesia and sedation in all kinds of adult intensive care unit patients, and that its use will result in rapid and predictable offset of effect. This may permit both a significant reduction in weaning and extubation times, and clear differentiation between over-sedation and brain dysfunction. This article provides an overview of the use of short-acting opioids in the intensive care unit, with special emphasis on remifentanil. It summarizes the currently available study data regarding remifentanil and provides recommendations for clinical use of this agent.

The effect of lidocaine on remifentanil-induced cough

This study was performed to investigate the incidence of remifentanil-induced cough and evaluate the efficacy of lidocaine on its prevention. Five-hundred patients, aged 18-70 years, were randomly allocated into two groups to receive either lidocaine 0.5 mg x kg(-1) or 0.9% normal saline intravenously 1 min before remifentanil administration at a target effect-site concentration of 4 ng x ml(-1). Any episode of cough was classified as coughing and graded as mild (1-2), moderate (3-4) or severe (5 or more). We found that the overall incidence of cough was significantly higher in the saline group (69 patients; 27.6%) than that in the lidocaine group (38 patients; 15.2%) (p < 0.001). The results of logistic regression indicated that age and smoking were associated with remifentanil-induced cough. This study demonstrated that intravenously administered lidocaine 0.5 mg x kg(-1) effectively suppresses remifentanil-induced cough without possible systemic lidocaine toxicity.

Remifentanil-induced spike activity as a diagnostic tool in epilepsy surgery

OBJECTIVES

To assess the value of remifentanil in intraoperative evaluation of spike activity in patients undergoing surgery for mesial temporal lobe epilepsy (MTLE).

MATERIALS AND METHODS

Twenty-five patients undergoing temporal lobectomy for medically intractable MTLE were enrolled in the study. Electrocorticography (ECoG) recordings were performed on the intraventricular hippocampus and from the anterior inferior temporal and lateral neocortex before and after a 300 microg intravenous bolus of remifentanil. Spike activity was quantified as spike-count per minute.

RESULTS

A significant increase (P < 0.005) in spike activity was observed after administration of remifentanil in 23 of 25 patients (92%). Furthermore, two patients who did not have any spike activity on the baseline ECoG developed spikes after administration of remifentanil.

CONCLUSIONS

The results suggest that remifentanil can enhance spike activity in the epileptogenic zone and reveal otherwise concealed epileptogenic tissue in patients with MTLE. Thus, remifentanil may prove to be an important diagnostic tool during surgical treatment for intractable focal epilepsy.

Prevention of withdrawal movement associated with injection of rocuronium in children: comparison of remifentanil, alfentanil and fentanyl

BACKGROUND

We compared the efficacy of remifentanil, alfentanil and fentanyl in reducing withdrawal movement associated with the injection of rocuronium in children.

METHODS

In total, 164 ASA physical status I or II pediatric patients, aged 1-14 years, were randomly assigned to four treatment groups: group C received saline; group R, remifentanil 1 microg/kg; group A, alfentanil 10 micro/kg; and group F, fentanyl 2 microg/kg. Treatments were injected over 30 s, followed by thiopental 5 mg/kg. At 90 s after the start of the study drug injection, rocuronium 0.6 mg/kg was injected over 10 s. The patient's response to the injection of rocuronium was graded on a four-point scale in a double-blinded manner.

RESULTS

The incidence of withdrawal movement was 89.5% in group C, 70.3% in group F, 36.3% in group A and 7.2% in group R. The incidence of generalized movement (grade 4) was 86.9% in group C, 58.5% in group F, 15.9% in group A and 2.4% in group R.

CONCLUSION

Remifentanil, alfentanil and fentanyl all reduced the incidence of withdrawal movement when administered 90 s before the injection of rocuronium compared with saline. Remifentanil was the most effective, followed by alfentanil. Fentanyl was less effective but significantly different from the saline in reducing withdrawal movement in children.

Antibacterial activity of remifentanil and mixtures of remifentanil and propofol

STUDY OBJECTIVE

To investigate the antibacterial activity of glycine, which is contained in remifentanil, when combined with propofol.

DESIGN

Prospective study.

SETTING

Departments of anesthesiology and microbiology of a university hospital.

MEASUREMENTS

Growth of the microorganisms Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans in propofol 1%; saline dilutions of remifentanil at one-, 10-, and 100-microg/mL concentrations; and 1:1 mixtures of propofol with remifentanil solutions was determined.

MAIN RESULTS

Remifentanil inhibits bacterial growth in a concentration-dependent manner. The antibacterial effects were more pronounced with Staphylococcus aureus and Pseudomonas aeruginosa at cultures obtained at the fifth hour. The inhibition of bacterial growth was less influenced with Escherichia coli and Candida albicans.

CONCLUSIONS

Propofol and remifentanil mixtures decreased bacterial growth, and combinations may reduce the infectious complications from accidentally contaminated propofol.

Ambulatory anesthesia for the obese patient

PURPOSE OF REVIEW

Obese patients are more and more frequently proposed for elective surgery, including acts specifically aimed at curing this condition, i.e. bariatric surgery. Many of these acts present characteristics compatible with ambulatory treatment, but anesthesiologists are reluctant to treat the morbidly obese as outpatients due to lack of data on the safety of this approach. The purpose of this review is to present the information that could be found in the literature on the safety and feasibility of ambulatory procedures in obese patients, and outline the specificity of this population.

RECENT FINDINGS

During the last few years, the risks of perioperative complications in this population have been estimated more precisely, specifically respiratory events. A better knowledge of the pharmacology of anesthetic drugs in this population allows optimization of general anesthesia protocols and the interest of regional anesthesia has also been outlined. A first study on gastric banding has demonstrated the suitability of the ambulatory setting for such a procedure.

SUMMARY

Ambulatory care in the obese patient is both feasible and well suited to this population provided a few specificities are taken into account.

Drug development in anaesthesia: industrial perspective

PURPOSE OF REVIEW

In this review, we summarize the new drugs in development in the anaesthesia field.

RECENT FINDINGS

There are some interesting approaches, including pro-drugs of propofol such as Aquavan (MGI Pharma, Bloomington, Minnesota, USA) and novel 'soft-drug' sedatives and hypnotics (e.g. CNS-7259X and TD-4756) as well as a novel approach to terminate the action of steroidal neuromuscular blockers (sugammadex). There is also significant activity in the field of novel analgesics. Particularly addressing the fields of sedatives, hypnotics and neuromuscular blockers, however, there is relatively little drug discovery activity currently. Part of the reason for this may be that the mechanisms of action of anaesthetics are not fully understood. This cannot be the whole story, however, since attractive new targets have recently been identified. For example, an agent with selective actions at the beta3-containing subunit of the gamma-amino butyric acid-A receptor is likely to have the hypnotic effects of propofol without the cardiac depressant side-effects.

SUMMARY

We consider the main reason for low activity is the perception in industry that there is little need for new drugs in anaesthesia because the needs are well addressed by existing agents. If this is not the case then anaesthesiologists need to be more effective in communicating their requirements.

Experience with remifentanil in neonates and infants

Remifentanil is a relatively new synthetic opioid, which is not licensed worldwide for neonates and infants. Because of its unique pharmacokinetic properties with a short recovery profile, it could be the ideal opioid for neonates and infants, who are especially sensitive to respiratory depression by opioids. Therefore, we conducted a MEDLINE search on all articles dealing with the use of remifentanil in this important subgroup of patients. Most experience with remifentanil in neonates and infants is as maintenance anaesthesia during surgery. In approximately 300 neonates and infants, remifentanil proved to be an effective and safely used opioid for this indication. However, very limited data exist on remifentanil for analgesia and sedation of mechanically ventilated paediatric intensive care patients. Further research with remifentanil in neonates and infants should focus on this group of patients because remifentanil, with its very short context-sensitive half-life, could result in shorter extubation times compared with commonly used opioids such as morphine or fentanyl.

Pretreatment with remifentanil to prevent withdrawal after rocuronium in children

BACKGROUND

Pain from rocuronium injection is a common side-effect reported to occur in 50-80% of the patients. This randomized, double-blind, placebo-controlled study was designed to evaluate the efficacy of pretreatment with i.v. remifentanil on prevention of withdrawal response during rocuronium injection in paediatric patients.

METHODS

After obtaining parental consents, 70 paediatric patients were randomly allocated into two groups to receive either i.v. remifentanil 1 mug kg(-1) (remifentanil group, n=35) or i.v. saline 5 ml (saline group, n=35). Anaesthesia was induced with thiopental sodium 2.5% (5 mg kg(-1)) and the test drug was injected over 30 s. One minute after the test drug injection, rocuronium 1% (0.6 mg kg(-1)) was injected over 5 s and the response was recorded. Mean arterial pressure (MAP) and heart rate were recorded on arrival in the operating theatre, before and 1 min after the tracheal intubation.

RESULTS

The overall incidence of withdrawal movements was significantly higher in the saline group (33 patients; 94%) than that in the remifentanil group (8 patients; 23%) (P<0.001). No patient in the remifentanil group showed generalized movement, whereas 51% of patients in the saline group did. Remifentanil prevented significant increase in MAP after intubation.

CONCLUSION

This study demonstrated that pretreatment with remifentanil 1 microg kg(-1) provided a safe and simple method for reducing the incidence of rocuronium-associated withdrawal movement with haemodynamic stability in children.

Effects of a loading dose of morphine before i.v. morphine titration for postoperative pain relief: a randomized, double-blind, placebo-control study

BACKGROUND

I.V. morphine titration (MT) allows adjustment of the dose needed for pain relief in the post-anaesthesia care unit (PACU). However, MT has limitations such as a delay to achieve pain relief. We thus assessed the effect of a fixed intraoperative loading dose of morphine administered before titration.

METHODS

One hundred patients who were undergoing major orthopaedic surgery were included in a double-blind, randomized study comparing a loading dose of morphine (0.15 mg kg(-1)) with placebo administered intraoperatively. MT was then administered in the PACU followed by patient-controlled analgesia (PCA) over 24 h. Data are expressed as mean (sd).

RESULTS

The initial VAS [41 (36) vs 52 (35), NS] was not decreased in the morphine group. The VAS was lower in the morphine group in the PACU and PCA periods. The time to achieve effective pain relief was not decreased in the morphine group. The total dose of morphine administered in the PACU (including the loading dose) was significantly increased in the morphine group (+31% in mg kg(-1), P<0.05). Morphine requirements during the PCA period were not different between groups. The incidence of sedation was increased and a severe episode of ventilatory depression occurred in the morphine group.

CONCLUSIONS

A loading dose of morphine administered at the end of surgery slightly decreased the VAS but did not reduce the time to pain relief or morphine consumption within the first 24 h. This slight improvement in analgesia was obtained at the expense of morphine-related adverse events.

Spotlight on remifentanil: its analgesic and sedative use in the intensive care unit

Remifentanil (Ultivatrade), a 4-anilidopiperidine derivative of fentanyl, is an ultra-short-acting micro-opioid receptor agonist indicated to provide analgesia and sedation in mechanically ventilated intensive care unit (ICU) patients. Analgesia-based sedation with remifentanil is a useful option for mechanically ventilated patients in the ICU setting. Its unique properties (e.g. organ-independent metabolism, lack of accumulation, rapid offset of action) set it apart from other opioid agents. Remifentanil is at least as effective as comparator opioids such as fentanyl, morphine and sufentanil in providing pain relief and sedation in mechanically ventilated ICU patients. Moreover, it allows fast and predictable extubation, as well as being associated with a shorter duration of mechanical ventilation and quicker ICU discharge than comparators in some studies. In addition, remifentanil is generally well tolerated in this patient population. Thus, remifentanil is a welcome addition to the currently available pharmacological agents employed in the management of mechanically ventilated ICU patients.

Sedation in the intensive care unit with remifentanil/propofol versus midazolam/fentanyl: a randomised, open-label, pharmacoeconomic trial

Introduction

Remifentanil is an opioid with a unique pharmacokinetic profile. Its organ-independent elimination and short context-sensitive half time of 3 to 4 minutes lead to a highly predictable offset of action. We tested the hypothesis that with an analgesia-based sedation regimen with remifentanil and propofol, patients after cardiac surgery reach predefined criteria for discharge from the intensive care unit (ICU) sooner, resulting in shorter duration of time spent in the ICU, compared to a conventional regimen consisting of midazolam and fentanyl. In addition, the two regimens were compared regarding their costs.

Methods

In this prospective, open-label, randomised, single-centre study, a total of 80 patients (18 to 75 years old), who had undergone cardiac surgery, were postoperatively assigned to one of two treatment regimens for sedation in the ICU for 12 to 72 hours. Patients in the remifentanil/propofol group received remifentanil (6- max. 60 μg kg^-1 h^-1; dose exceeds recommended labelling). Propofol (0.5 to 4.0 mg kg^-1 h^-1) was supplemented only in the case of insufficient sedation at maximal remifentanil dose. Patients in the midazolam/fentanyl group received midazolam (0.02 to 0.2 mg kg^-1 h^-1) and fentanyl (1.0 to 7.0 μg kg^-1 h^-1). For treatment of pain after extubation, both groups received morphine and/or non-opioid analgesics.

Results

The time intervals (mean values ± standard deviation) from arrival at the ICU until extubation (20.7 ± 5.2 hours versus 24.2 h ± 7.0 hours) and from arrival until eligible discharge from the ICU (46.1 ± 22.0 hours versus 62.4 ± 27.2 hours) were significantly (p < 0.05) shorter in the remifentanil/propofol group. Overall costs of the ICU stay per patient were equal (approximately €1,700 on average).

Conclusion

Compared with midazolam/fentanyl, a remifentanil-based regimen for analgesia and sedation supplemented with propofol significantly reduced the time on mechanical ventilation and allowed earlier discharge from the ICU, at equal overall costs.