Timing of intravenous patient-controlled remifentanil bolus during early labour

Background: Remifentanil labour analgesia is superior to nitrous oxide but less potent than epidural analgesia. The short onset and offset times of effect suggest that the timing of the bolus in the contraction cycle could have importance. We hypothesised that administering a remifentanil bolus during contraction pause would improve analgesia in early labour. Methods: With permission from the ethical committee and the National Authority of Medicines, 50 parturients with uncomplicated singleton pregnancies and informed consent participated in a double blind cross‐over study. Intravenous doses of 0.4 μg/kg remifentanil with 1‐min infusion times were used during two study periods lasting six to eight contractions. Remifentanil and saline syringes were attached to two patient‐controlled devices, one of which administered the bolus immediately after a trigger and the other targeted to start 140 s before the next contraction. The parturients assessed contraction pain, pain relief, sedation and nausea. Oxygen saturation (SaO₂) pulse and blood pressure were recorded. SaO₂ <95% was the indication for oxygen supplement. Results: Forty‐one parturients were included in the analyses. Because of the period effect, pain and pain relief scores were analysed separately for each of the study periods. The mean pain and pain relief scores were similar during the two different dosing regimens. Side effects, the need for supplemental oxygen, SaO₂ and haemodynamics were similar. In a subgroup with long and regular contractions, however, delayed boluses were associated with lower pain scores. Conclusions: Administering a remifentanil bolus during the uterine contraction pause does not improve pain relief.     

Intravenous remifentanil vs. epidural levobupivacaine with fentanyl for pain relief in early labour: a randomised, controlled, double-blinded study

Background: We hypothesised that intravenous patient-controlled analgesia (IV PCA) with remifentanil could provide as satisfactory pain relief for labour as epidural analgesia.
Methods: Fifty-two parturients with singleton uncomplicated pregnancies were randomised to receive either IV PCA with remifentanil or epidural analgesia with 20 ml levobupivacaine 0.625 mg/ml and fentanyl 2 μg/ml in saline. The PCA dose of remifentanil was given over 1 min with a lockout time of 1 min. The dose was increased starting from the bolus of 0.1 μg/kg and following a dose escalation scheme up until the individual-effective dose was reached. The parturients assessed contraction pain (0–10), pain relief (0–4), sedation and nausea during 60 min.
Results: Forty-five parturients were included in the analysis. The median cervical opening was 4 cm before the study and 7 cm after the study. The median pain scores were 7.3 and 5.2 during remifentanil and epidural analgesia, respectively (P=0.009). The median pain relief scores were 2.5 and 2.8 (P=0.17). There was no difference between the groups in the proportion of parturients who discontinued due to ineffective analgesia, nor in the proportion of parturients who would have liked to continue the given medication at the end of the study. Sedation and low haemoglobin oxygen saturation were observed more often during remifentanil analgesia. Foetal heart rate tracing abnormalities were as common in both groups.
Conclusions: In terms of pain scores, epidural analgesia is superior to that provided by IV remifentanil. However, there was no difference in the pain relief scores between the treatments.     

雷米芬太尼静脉自控镇痛在产科的应用

目的 探讨雷米芬太尼静脉自控镇痛(PCIA)用于产科分娩镇痛的临床有效性和安全性.方法 60例健康初产妇随机分为雷米芬太尼PCIA镇痛组(Ⅰ组)和未予镇痛对照组(Ⅱ组),每组30例.观察分娩VAS评分、镇静评分、术后满意度评分及各产程时间、分娩方式、催产素使用及第一产程活跃期时间和官口扩张进程.并记录新生儿出生后1、5 min Apgar评分、胎心率(FHR)及不良反应.结果 与镇痛前和Ⅱ组相比,Ⅰ组镇痛后15 min、1 h、宫口开全和胎儿娩出时VAS评分降低、镇静评分升高(P<0.05).与Ⅱ组相比,Ⅰ组产后24 h满意度评分较高(P<0.05).两组FHR和新生儿出生后1、5 min Apgar评分均在正常范围.Ⅰ组产妇镇痛期眩晕发生率高于Ⅱ组(P<0.05).结论 雷米芬太尼PCIA用于分娩镇痛有效且无明显不良反应.     

The use of 0.25% isoflurane premixed in 50% nitrous oxide and oxygen for pain relief in labour

The addition of 0.25% isoflurane to 50% nitrous oxide in oxygen provides more effective pain relief in labour than 50% nitrous oxide alone. This study was carried out to determine whether self-administration by demand valve of 0.25% isoflurane in 50% nitrous oxide in oxygen premixed in cylinders at 13.7 MPa (IN2O) was practical and safe during labour. Two hundred and twenty-one mothers used IN2O in labour after 50% nitrous oxide had become inadequate for pain relief. Data on IN2O use was recorded during labour and details of the course of labour and opioid usage were taken from the clinical notes. The duration of IN2O use was 0.1-12.35 h (median 2.3). Thirty-two mothers (14.5%) required an epidural and intolerance to IN2O was seen in a maximum of 17 cases (7.7%). One hundred and twenty-six cases were primiparous and 93 parous with 151 deliveries being spontaneous and 70 interventional, of which 12 were by Caesarean section. Maternal blood loss was 20-1500 ml (median 200 ml). Apgar scores at 1 and 5 min were unaffected by IN2O use although a positive correlation was found between the use of opioids and the number of neonates with a 1-min score below 8 and the number requiring resuscitation. Six neonates had an Apgar score below 8 at 5 min, but their condition was adequately explained by factors other than the sedative technique used. Self-administered IN2O was found to be a safe and practical technique for sedation in labour when 50% nitrous oxide alone had become inadequate.     

Intraoperative remifentanil infusion does not increase postoperative opioid consumption compared with 70% nitrous oxide

BACKGROUND: Remifentanil is commonly used to replace nitrous oxide in general anesthesia to avoid the side effects of the latter. However, there are reports that intraoperative remifentanil infusion can lead to acute opioid tolerance. In this study, the authors tried to determine the dose of remifentanil comparable in efficacy to 70% nitrous oxide and to evaluate its effect on postoperative pain and morphine consumption after colorectal surgery using isoflurane anesthesia. METHODS: Sixty adult patients undergoing open colorectal surgery were randomly assigned to receive either remifentanil or 70% nitrous oxide along with isoflurane anesthesia. After morphine analgesia titration in the postanesthesia care unit, patient-controlled analgesia was commenced. Morphine consumption and pain were scored at rest and during cough or movement for 24 h. RESULTS: The mean remifentanil infusion rate was 0.17 mug . kg . min. The median visual analog pain score on arrival in the postanesthesia care unit was 1 (0-10) in the nitrous oxide group and 3 (0-9) in the remifentanil group (P < 0.05). Otherwise, there was no difference in pain scores at 5, 10, and 15 min and no difference in the total morphine consumption during the stay in the postanesthesia care unit. The two groups had similar total morphine consumption in the first 24 h and pain scores at rest and during movement. The incidence of postoperative nausea and vomiting was 10% in both groups. There was no difference in the sedation scores. CONCLUSION: The substitution of 70% nitrous oxide with remifentanil at a mean infusion rate of 0.17 mug . kg . minute for colorectal surgery did not affect postoperative opioid consumption.     

Intraoperative Remifentanil Infusion Does Not Increase Postoperative Opioid Consumption Compared with 70% Nitrous Oxide

Background: Remifentanil is commonly used to replace nitrous oxide in general anesthesia to avoid the side effects of the latter. However, there are reports that intraoperative remifentanil infusion can lead to acute opioid tolerance. In this study, the authors tried to determine the dose of remifentanil comparable in efficacy to 70% nitrous oxide and to evaluate its effect on postoperative pain and morphine consumption after colorectal surgery using isoflurane anesthesia.

Methods: Sixty adult patients undergoing open colorectal surgery were randomly assigned to receive either remifentanil or 70% nitrous oxide along with isoflurane anesthesia. After morphine analgesia titration in the postanesthesia care unit, patient-controlled analgesia was commenced. Morphine consumption and pain were scored at rest and during cough or movement for 24 h.

Results: The mean remifentanil infusion rate was 0.17 [mu]g [middle dot] kg-1 [middle dot] min-1. The median visual analog pain score on arrival in the postanesthesia care unit was 1 (0-10) in the nitrous oxide group and 3 (0-9) in the remifentanil group (P < 0.05). Otherwise, there was no difference in pain scores at 5, 10, and 15 min and no difference in the total morphine consumption during the stay in the postanesthesia care unit. The two groups had similar total morphine consumption in the first 24 h and pain scores at rest and during movement. The incidence of postoperative nausea and vomiting was 10% in both groups. There was no difference in the sedation scores.     

Maternal expectations and experiences of labour pain — options of 1091 Finnish parturients

A prospective survey of 1091 Finnish parturients was conducted in order to ascertain mothers' expectations for labour pain relief, to measure the actual pain during all three stages of labour and to question their satisfaction and the adequacy of pain relief on the third day following delivery. Antenatal expectations for pain relief were surveyed. Mothers were questioned on pain levels in the delivery room and 3 days after giving birth. Pain levels were ascertained using a visual pain score method. Antenatally, 90% of all parturients anticipated a need for pain relief during labour. In the delivery room over 80% of all parturients described their pain as very severe to intolerable, only 4% of the multiparous had low pain scores (0–2). After pain treatment 50% of multiparous women still had pain scores from 8 to 10, which reflects a lack of effective pain relief. Dissatisfaction with the childbirth experience was very low, and was associated with instrumental deliveries, but not with the usage of analgesia. 51% of all parturients complained of inadequate pain relief during childbirth, which, in multiparous women, was significantly associated with the second stage of labour.     

Maternal positioning affects fetal heart rate changes after epidural analgesia for labour

Adverse fetal heart rate (FHR) changes suggestive of fetal hypoxia are seen in patients with normal term pregnancies after initiation of epidural block for labour analgesia. It was our hypothesis that, in some parturients, these changes were a consequence of concealed aortocaval compression resulting in decreased uterine blood flow. We expected that the full lateral position compared with the wedged supine position would provide more effective prophylaxis against aortocaval compression. To test our hypothesis we studied the role of maternal positioning on FHR changes during onset of epidural analgesia for labour. Eighty-eight ASA Class I or II term parturients were randomized into two groups: those to be nursed in the wedged supine position and those to be nursed in the full lateral position during induction of an epidural block. External FHR monitoring was employed to assess the fetal response to initiation of labour epidural analgesia. Epidural catheters were sited with the parturients in the sitting position and the patients then assumed the study position. After a negative test dose, a standardized regimen of bupivacaine 0.25% was employed to provide labour analgesia. The quality and efficacy of the block were assessed using VAS pain scores, motor block scores and sensory levels. The results demonstrated that there was no difference in the quality of analgesia provided nor in the incidence of asymmetric blocks. There was no difference in the observed incidence of FHR changes occurring during the initiation of the epidural block. However, six of 38 women (15%) nursed in the wedged supine position had severe FHR decelerations compared with none in the patients nursed in the full lateral position (P < 0.05). We recommend the use of the full lateral position to nurse women in labour during the initiation of labour epidural analgesia.     

Obstetrical Analgesia Assessed by Free Fatty Acid Mobilisation

Two groups of six parturients each have been compared. One group received centrally acting analgesics, sedatives and intermittent nitrous oxide and the other group was given epidural anaesthesia. The serum free fatty acid (FFA) concentrations of the parturients in the former group increased steadily during labour, attaining peak values between 1050 and 1750 mumol/l at delivery. In parturients belonging to the epidural group, the serum FFA concentrations remained level or even fell towards the time of delivery. It is suggested that the increase in serum FFA reflects a stress induced adrenergic lipolysis which may be used to assiss the various methods for obstetrical analgesia. It is concluded that epidural anaesthesia is superior to the conventional methods of pain relief. Analyses of blood sampled from the unbilical veins show that the concentrations of FFA in the blood of the newborns do not reflect the corresponding maternal values. Thus, epidural anaesthesia does not seem to deprive the fetus of FFA during labour since the factor limiting its transfer appears to be independent of the concentration gradient over the placental membrane.     

Efficacy and side effects of intravenous remifentanil patient-controlled analgesia used in a stepwise approach for labour: an observational study

BackgroundRemifentanil has a suitable pharmacological profile for labour analgesia. In this prospective, observational study, intravenous patient-controlled analgesia with remifentanil, using stepwise bolus doses without background infusion, was examined during the first and second stages of labour. Outcomes were pain reduction, maternal satisfaction, maternal and neonatal side effects and remifentanil metabolism in the neonate.MethodsParturients with normal term singleton pregnancies were recruited. The initial remifentanil bolus dose was 0.15 μg/kg, increasing in steps of 0.15 μg/kg, with a 2-min lock-out. Pain scores using a 100 mm visual analogue scale, systolic and diastolic blood pressures, respiratory rate and maternal sedation were recorded every 15 min. Maternal oxygen saturation and heart rate were monitored continuously. Neonatal data included Apgar scores, clinical examination, naloxone use, resuscitation, umbilical cord blood gases and remifentanil concentrations.ResultsForty-one parturients were enrolled. Pain scores were significantly reduced in the first 3 h of patient-controlled analgesia use compared to baseline, and at the end of the first and second stages of labour (P < 0.05). Maximal pain reduction was 60% (P < 0.01). One patient had inadequate pain relief and converted to epidural analgesia. The mean highest dose of remifentanil was 0.7 μg/kg [range 0.3–1.05]. Ninety-three percent of patients were satisfied with their analgesia. The lowest oxygen saturation was 91% and the lowest respiratory rate was 9 breaths/min. Eleven parturients (27%) received supplemental oxygen due to oxygen saturations <92%. Maternal sedation was moderate, and neonatal data reassuring.ConclusionsRemifentanil intravenous patient-controlled analgesia provides adequate pain relief and high maternal satisfaction during the first and second stages of labour. Maternal sedation and respiratory depression may occur, but no serious neonatal side effects were recorded. Careful monitoring is mandatory.     

Single-shot spinal block for labour analgesia in multiparous parturients*

BACKGROUND: Intrathecal analgesia (ITA) is effective in late, rapidly progressing labour. In 1998, our hospital implemented the use of single-shot spinal block for pain relief in multiparous parturients. As part of a quality assurance programme, we assessed the analgesic efficacy, obstetric and neonatal outcomes and maternal satisfaction after this form of analgesia now in routine use in our labour ward. METHODS: Two hundred and twenty-nine consecutive multiparous parturients presenting for vaginal delivery and requesting analgesia were asked to participate in this prospective study. All parturients received our standard ITA: 2.5 mg bupivacaine (1 ml) + 25 microg fentanyl (0.5 ml) inserted via the L2-3 or L3-4 interspace. Routine monitoring included maternal vital signs, uterine contraction and fetal heart rate tracing. Pain scores (visual analogue scale (VAS) 0-10), sensory levels, motor block, side-effects and maternal satisfaction were recorded. Satisfactory analgesia was defined as a decrease in pain scores to three or less within 20 min after injection. The number of parturients requesting additional analgesia and the duration of spinal block (time from injection until request for additional medication after satisfactory analgesia had worn off) were recorded. RESULTS: Two hundred and nine parturients were included in the study. Satisfactory analgesia was achieved in 153 (73%) parturients. Fifty-five (26%) women requested additional analgesia: 38 (18%) because of unsatisfactory analgesia and 17 (8%) because analgesia ended before delivery. The duration of spinal block was 101 +/- 34 min. Pruritus occurred in 64%, fetal bradycardia in 7% and hypotension in 2% of deliveries. Pain relief was rated excellent by 65%, moderate by 20% and inadequate by 14% of the parturients. One hundred and sixty-nine (81%) women stated that they would like to have spinal analgesia again for pain relief during delivery. CONCLUSION: The majority of multiparous parturients found ITA adequate for pain relief during delivery. However, modifications are required in terms of improved timing, reliability and duration of analgesia.     

A double-blind randomised comparison of intravenous patient-controlled remifentanil with intramuscular pethidine for labour analgesia

In a prospective, double-blind, randomised controlled trial, we compared the efficacy of patient-controlled analgesia using remifentanil (25-30 μg per bolus) with intramuscular pethidine (50-75 mg) for labour analgesia in 69 parturients. Parturients receiving patient-controlled analgesia reported less pain than those receiving intramuscular pethidine throughout the study period (p < 0.001), with maximal reduction in visual analogue pain score at 2 h after commencement of analgesia (mean (SD) 20 (17) in the patient-controlled analgesia group and 36 (22) in the intramuscular pethidine group. The median (95% CI) time to the first request for rescue analgesics was significantly longer with patient-controlled analgesia (8.0 (6.8-9.2) h) compared with intramuscular pethidine (4.9 (3.8-5.4) h, p < 0.001). Maternal satisfaction scores were also higher with remifentanil compared with intramuscular pethidine (p= 0.001). There was no report of sedation, aponea or oxygen desaturation in either group, and Apgar scores were similar between groups. We conclude that patient-controlled analgesia with remifentanil provides better labour analgesia and maternal satisfaction than intramuscular pethidine. At this dose, maternal and fetal side effects were uncommon.     

Remifentanil in obstetric analgesia: a dose-finding study

IV patient-controlled analgesia (PCA) with remifentanil is a new approach in systemic opioid analgesia during labor. We determined the minimum effective dose of IV remifentanil by increasing the PCA bolus from 0.2 microg/kg with 0.2 microg/kg increments during a 60-min study period until the analgesia was considered adequate by the parturient. Twenty healthy parturients with singleton pregnancies participated in the study during the first stage of labor. Remifentanil hydrochloride was given IV via PCA over 1 min with a lockout time of 1 min. The parturient started the PCA bolus at the first subjective sign of uterine contraction. All 17 patients who completed the study reached adequate pain relief. The median effective PCA bolus was 0.4 microg/kg and consumption was 0.066 microg x kg(-1) x min(-1), with wide individual variation (0.2-0.8 microg/kg and 0.027-0.207 microg x kg(-1) x min(-1), respectively). The pain scores were reduced by a median of 4.2 (25th-75th percentiles, 3.1-5.2; P < 0.001) on an 11-point numeric scale. Although there was a wide individual variation in the dose required, remifentanil seems effective for labor analgesia. However, maternal oxygen desaturation, sedation, and reduced fetal heart rate beat-to-beat variability were observed frequently. There was wide individual variation in the dose required for effective labor analgesia. Potentially serious side effects, which were observed frequently during remifentanil analgesia, may limit remifentanil's use in obstetrics. IMPLICATIONS: We determined the minimum effective dose of patient-controlled IV remifentanil for labor analgesia. There was wide individual variation in the dose required for effective labor analgesia. Potentially serious side effects, which were observed frequently during remifentanil analgesia, may limit its use in obstetrics.     

Patient controlled analgesia for labour: a comparison of remifentanil with pethidine

We compared the analgesic efficacy and safety of remifentanil and pethidine via patient controlled analgesia for women in established uncomplicated labour. Women received either remifentanil 40 microg with a 2-min lockout (n = 20) or pethidine 15 mg with a 10-min lockout (n = 19). Visual analogue scores for pain during the study and for overall pain were similar for both groups (mean (SD) 6.4 (1.5) cm for remifentanil and 6.9 (1.7) cm for pethidine). The area under the curve for visual analogue scores of satisfaction with analgesia was higher for remifentanil than for pethidine (p = 0.001). Maternal arterial oxygen saturation was similar in both groups. Neurologic and Adaptive Capacity Scores at 30 min were higher for remifentanil than for pethidine (median (interquartile range [range]) 36 (34.5-37 [32-39]) vs 34 (33-35 [30-35]), respectively; p = 0.003).     

Effect-site concentration of remifentanil during patient-controlled analgesia in labour

BackgroundIntravenous remifentanil has been described for patient-controlled analgesia in labour. Recently, the application of target-controlled infusion pumps with Minto’s pharmacokinetic/pharmacodynamic model has been reported. Hypothetical effect-site remifentanil concentration during patient-controlled analgesia for labour has yet to be examined. The aim of this concept study was to explore characteristics of this parameter.MethodsWe performed a historical cohort study based on our previous randomised cross-over clinical trial and analysed hypothetical effect-site remifentanil concentration. Values at spontaneous vaginal delivery and Apgar scores were tested for correlation. The association between pain score and the corresponding effect-site remifentanil concentration before and after bolus administration, and their relative difference, was examined with a linear mixed-effects model, adjusted for other variables.ResultsA series of 23 parturients with uncomplicated singleton pregnancies were included. On average, effect-site remifentanil concentration was highest during the third quarter throughout our recordings (5.5 ng/mL; maximum 15.8 ng/mL). The mean (median) {IQR} [range] at spontaneous vaginal delivery (n=14) was 2.52 (1.32) {0.95–4.28} [0.65–6.88] ng/mL, all Apgar scores were >7, and no correlation was confirmed. A negative association between effect-site remifentanil concentration before bolus administration and pain score (scale 0–100) was observed (−3.9, 95% CI −5.16 to −2.61, P <0.01).ConclusionsThe residual value of hypothetical effect-site remifentanil concentration before uterine contraction, at the beginning of bolus administration, predicted lower pain scores. Monitoring effect-site remifentanil concentration may be potentially useful when remifentanil is administered for labour analgesia. However, our results need to be confirmed with a pharmacokinetic model optimized for pregnant patients.     

A prospective observational study of maternal oxygenation during remifentanil patient‐controlled analgesia use in labour

Numerous studies of remifentanil patient‐controlled analgesia during labour have shown high levels of maternal satisfaction, but concerns remain, especially over the side‐effects of sedation and respiratory depression. We conducted a prospective observational study of maternal oxygen desaturation during remifentanil patient‐controlled analgesia. Pulse oximetry values were recorded every eight s and later downloaded for analysis. A desaturation episode was defined as oxygen saturation < 90%. We collected 148 h of data in 61 women, during which we observed 176 desaturation episodes. These episodes occurred in 43 (70%) women. The median (IQR [range]) of the lowest saturation during each episode was 87 (85–89 [68–89])% with duration 16 (8–24 [8–104]) s. Supplementary oxygen reduced the time per hour spent with saturation < 90%, but not the depth or duration of individual episodes. Desaturation episodes were twice as common during the second stage of labour as compared with the first stage. Prior opioid administration, bolus size and use of nitrous oxide during patient‐controlled analgesia use were not found to influence frequency, depth or duration of desaturation episodes. Although these findings suggest desaturation occurs more frequently during remifentanil patient‐controlled analgesia than previously reported, the results are comparable with earlier oximetry studies of women who received nitrous oxide and pethidine during labour.     

Initial experiences with propofol (Disoprivan) for anesthesia induction in pediatric anesthesia

Propofol is a new intravenous anesthetic agent that provides smooth and rapid induction of anesthesia. A short elimination half-life guarantees rapid recovery. Since it has been reformulated as an emulsion in soya bean oil, anaphylactoid reactions are unlikely to occur. As compared to adults, there is very little experience with propofol in pediatric anesthesia. The aim of this study was to evaluate propofol as an induction agent in children with respect to cardiovascular and respiratory effects and to investigate the incidence of other side-effects. METHOD. In 25 ASA I children aged 3-12 years (6.4 +/- 2.7 SD) anesthesia was induced with a single dose of propofol, after standard premedication with atropine 0.01 mg/kg and Thalamonal 0.04 ml/kg. Anesthesia was maintained with halothane, nitrous oxide, and oxygen. Blood pressure (BP), heart rate (HR), and arterial oxygen saturation (SaO2) were measured before and each minute for 6 min after propofol administration. The incidence of side-effects during induction of anesthesia as well as during recovery and the postoperative period were recorded. RESULTS. Propofol 2.5 mg/kg produced rapid and smooth induction of anesthesia. Mean arterial pressure decreased after 1 min by 14.3% with a maximum of 16.8% after 3 min. HR was influenced differently by propofol; children with initially high HR had a decrease in HR, whereas in children with a low initial rate, HR increased transiently. After 1 min, no further changes occurred. Although no apnea was observed, respiration was shallow and depressed, as indicated by a decrease in SaO2. Two children complained of pain and 4 of discomfort at the site of the injection; 1 of these developed transient phlebitis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Remifentanil by patient-controlled analgesia compared with intramuscular meperidine for pain relief in labour

Background. The pharmacokinetics of remifentanil suggests thatit may be suitable for analgesia during labour. Methods. In an open pilot study, 36 women requesting meperidinefor analgesia were recruited early in labour and randomizedto receive either meperidine i.m. or remifentanil given as patient-controlledanalgesia (PCA). Pain severity, sedation and anxiety were assessedwith visual analogue scales and overall effective analgesiawas assessed by the woman and midwife. Results. The pain scores were lower in the remifentanil group:median pain score at 60 min was 72 mm for meperidineand 48 mm for remifentanil (P=0.004) and median maximumpain score during the first 2 h was 82.5 mm for themeperidine group and 66.5 mm for the remifentanil group(P=0.009). Both the midwives’ and the women’s assessmentsof overall effective analgesia were higher in the remifentanilgroup [Likert scale (5 = excellent to 1 = poor):     

The effects of subanesthetic concentrations of sevoflurane and nitrous oxide, alone and in combination, on analgesia, mood, and psychomotor performance in healthy volunteers.

We studied the effects of subanesthetic concentrations of sevoflurane and nitrous oxide, alone and in combination, on analgesia, mood, and psychomotor performance in human volunteers. We hypothesized that nitrous oxide and sevoflurane would produce both opposing and potentiating effects within the same study. Over the course of three sessions, 20 subjects inhaled 0%, 0.2%, or 0.4% end-tidal sevoflurane for a 68-min period that was divided into four 17-min blocks. During either the second or fourth block, 30% end-tidal nitrous oxide was added to the concentration of sevoflurane being inhaled. Pain response, psychomotor performance, and mood were evaluated during the second and fourth blocks. Pain ratings were higher when sevoflurane and nitrous oxide were administered together than when nitrous oxide was administered alone, which indicates that sevoflurane attenuated the analgesic effects of nitrous oxide. Sevoflurane increased self-reported ratings of sleepiness, and the addition of nitrous oxide decreased these ratings. Nitrous oxide potentiated psychomotor impairment that was induced by sevoflurane. The combination of sevoflurane and nitrous oxide produced both opposing and potentiating effects within the same study. The results suggest that nitrous oxide and sevoflurane may act through different neurochemical mechanisms on some end points, such as analgesia and sleepiness. IMPLICATIONS: Healthy volunteers inhaled subanesthetic concentrations of sevoflurane and nitrous oxide. Sevoflurane made nitrous oxide less effective as an analgesic, and nitrous oxide made sevoflurane less effective as a sedative. The two drugs may work at cross purposes on different end points of anesthesia.     

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.