Reducing pain and distress related to needle procedures in children with cancer: A clinical practice guideline.

BACKGROUND: Children with cancer often undergo long treatment trajectories involving repeated needle procedures that potentially cause pain and distress. As part of a comprehensive effort to develop clinical practice guidelines (CPGs) to address pain prevention and management in children with cancer, we aimed to provide recommendations on the pharmacological and psychological management of procedure-related pain and distress. METHODS: Of the international inter-disciplinary CPG development panel (44 individuals), two working groups including 13 healthcare professionals focused on procedural pain and distress. Grading of Recommendations Assessment, Development and Evaluation methodology was used, including the use of systematic literature reviews to inform recommendations and the use of evidence to decision frameworks. At an in-person meeting in February 2018, the guideline panel discussed these frameworks and formulated recommendations which were then discussed with a patient-parent panel consisting of 4 survivors and 5 parents. RESULTS: The systematic reviews led to the inclusion of 48 randomised controlled trials (total number of participants = 2271). Quality of evidence supporting the recommendations ranged from very low to moderate. Strong recommendations were made for the use of topical anesthetics in all needle procedures, for offering deep sedation (DS)/general anesthesia (GA) to all children undergoing lumbar puncture, for the use of DS/ GA in major procedures in children of all ages, for the use of hypnosis in all needle procedures and for the use of active distraction in all needle procedures. CONCLUSION: In this CPG, an evidence-based approach to manage procedure-related pain and distress in children with cancer is presented. As children with cancer often undergo repeated needle procedures during treatment, prevention and alleviation of procedure-related pain and distress is of the utmost importance to increase quality of life in these children and their families.

Effectiveness of a hospital-based postnatal parent education intervention about pain management during infant vaccination: a randomized controlled trial.

BACKGROUND: Parents have reported that they want to learn how to reduce pain in infants during vaccinations. Our objective was to compare different levels of intensity of postnatal education about pain mitigation on parental self-reported use of interventions at future infant vaccinations. METHODS: We conducted a longitudinal, 3-group parallel, add-on, randomized controlled trial on the postnatal ward of a hospital. New mothers, unaware of the hypothesis, were randomly assigned to 1 of 3 intervention groups and 3 follow-up groups (i.e., 9 groups, 3 × 3). The 3 intervention groups were control (general immunization information), pain pamphlet (pain mitigation information), and pain pamphlet and pain video (pain mitigation information). Both pain mitigation education groups also received general immunization information. The 3 follow-up groups were 2-, 4- and 6-month infant vaccinations. Mothers reported use of breastfeeding, sucrose and topical anesthetics during infant vaccinations in a telephone survey. RESULTS: Of 3420 participants, follow-up was available for 2549 (75%): 36.1%, 34.2% and 29.7% reported on pain mitigation practices at 2-, 4- and 6-month vaccinations, respectively (p = 0.9). Maternal characteristics did not differ (p > 0.05): mean age, 33.6 years; 58% were primipara. Utilization of any intervention (breastfeeding, sucrose or topical anesthetics) was 53.2%, 61.4% and 63.0% for control, pain pamphlet, and pain pamphlet and pain video groups, respectively (p < 0.001); both pain education groups had higher utilization than the control group, but did not differ from one another. Uptake differed among intervention groups at 2 and 4 months but not at 6 months. INTERPRETATION: Hospital-based postnatal education increased parental use of pain interventions at infant vaccinations and can be added to existing education. TRIAL REGISTRATION: ClinicalTrials.gov, no. NCT01937143.

The minimally effective dose of sucrose for procedural pain relief in neonates: a randomized controlled trial.

BACKGROUND: Orally administered sucrose is effective and safe in reducing pain intensity during single, tissue-damaging procedures in neonates, and is commonly recommended in neonatal pain guidelines. However, there is wide variability in sucrose doses examined in research, and more than a 20-fold variation across neonatal care settings. The aim of this study was to determine the minimally effective dose of 24% sucrose for reducing pain in hospitalized neonates undergoing a single skin-breaking heel lance procedure. METHODS: A total of 245 neonates from 4 Canadian tertiary neonatal intensive care units (NICUs), born between 24 and 42 weeks gestational age (GA), were prospectively randomized to receive one of three doses of 24% sucrose, plus non-nutritive sucking/pacifier, 2 min before a routine heel lance: 0.1 ml (Group 1; n = 81), 0.5 ml (Group 2; n = 81), or 1.0 ml (Group 3; n = 83). The primary outcome was pain intensity measured at 30 and 60 s following the heel lance, using the Premature Infant Pain Profile-Revised (PIPP-R). The secondary outcome was the incidence of adverse events. Analysis of covariance models, adjusting for GA and study site examined between group differences in pain intensity across intervention groups. RESULTS: There was no difference in mean pain intensity PIPP-R scores between treatment groups at 30 s (P = .97) and 60 s (P = .93); however, pain was not fully eliminated during the heel lance procedure. There were 5 reported adverse events among 5/245 (2.0%) neonates, with no significant differences in the proportion of events by sucrose dose (P = .62). All events resolved spontaneously without medical intervention. CONCLUSIONS: The minimally effective dose of 24% sucrose required to treat pain associated with a single heel lance in neonates was 0.1 ml. Further evaluation regarding the sustained effectiveness of this dose in reducing pain intensity in neonates for repeated painful procedures is warranted. TRIAL REGISTRATION: ClinicalTrials.gov : NCT02134873. Date: May 5, 2014 (retrospectively registered).

Impact of prenatal education on maternal utilization of analgesic interventions at future infant vaccinations: a cluster randomized trial.

Analgesic interventions are not routinely used during vaccine injections in infants. Parents report a desire to mitigate injection pain, but lack the knowledge about how to do so. The objective of this cluster-randomized trial was to evaluate the effect of a parent-directed prenatal education teaching module about vaccination pain management on analgesic utilization at future infant vaccinations. Expectant mothers enrolled in prenatal classes at Mount Sinai Hospital in Toronto were randomized to a 20-30minute interactive presentation about vaccination pain management (experimental group) or general vaccination information (control group). Both presentations included a PowerPoint (Microsoft Corporation, Redmond, WA, USA) and video presentation, take-home pamphlet, and "Question and Answer" period. The primary outcome was self-reported utilization of breastfeeding, sugar water, or topical anaesthetics at routine 2-month infant vaccinations. Between October 2012 and July 2013, 197 expectant mothers from 28 prenatal classes participated; follow-up was obtained in 174 (88%). Maternal characteristics did not differ (P>0.05) between groups. Utilization of one or more prespecified pain interventions occurred in 34% of participants in the experimental group, compared to 17% in the control group (P=0.01). Inclusion of a pain management module in prenatal classes led to increased utilization of evidence-based pain management interventions by parents at the 2-month infant vaccination appointment. Educating parents offers a novel and effective way of improving the quality of pain care delivered to infants during vaccination. Additional research is needed to determine if utilization can be bolstered further using techniques such as postnatal hospital reinforcement, reminder cards, and clinician education.

Pharmacology of milrinone in neonates with persistent pulmonary hypertension of the newborn and suboptimal response to inhaled nitric oxide.

OBJECTIVES: Persistent pulmonary hypertension of the newborn is a common problem with significant morbidity and mortality. Inhaled nitric oxide is the standard care, but up to 40% of neonates are nonresponders. Milrinone is a phosphodiesterase III inhibitor which increases the bioavailability of cyclic adenosine monophosphate and has been shown to improve pulmonary hemodynamics in animal experimental models. The primary objective was to investigate the pharmacological profile of milrinone in persistent pulmonary hypertension of the newborn. Secondary objectives were to delineate short-term outcomes and safety profile. SUBJECTS AND METHODS: An open label study of milrinone in neonates with persistent pulmonary hypertension of the newborn was conducted. Patients received an intravenous loading dose of milrinone (50 µg/kg) over 60 mins followed by a maintenance infusion (0.33-0.99 µg/kg/min) for 24-72 hrs. Physiologic indices of cardiorespiratory stability and details of cointerventions were recorded. Serial blood milrinone levels were collected after the bolus, following initiation of the maintenance infusion to determine steady state levels, and following discontinuation of the drug to determine clearance. Echocardiography was performed before and after (1, 12 hrs) milrinone initiation. INTERVENTIONS: Milrinone. MEASUREMENTS AND MAIN RESULTS: Eleven neonates with a diagnosis of persistent pulmonary hypertension of the newborn who met eligibility criteria were studied. The median (SD) gestational age and weight at birth were 39.2 ± 1.3 wks and 3481 ± 603 g. The mean (± sd) half-life, total body clearance, volume of distribution, and steady state concentration of milrinone were 4.1 ± 1.1 hrs, 0.11 ± 0.01 L/kg/hr, 0.56 ± 0.19 L/kg, and 290.9 ± 77.7 ng/mL. The initiation of milrinone led to an improvement in PaO2 (p = 0.002) and a sustained reduction in FIO2 (p < 0.001), oxygenation index (p < 0.001), mean airway pressure (p = 0.03), and inhaled nitric oxide dose (p < 0.001). Although a transient reduction in systolic arterial pressure (p < 0.001) was seen following the bolus, there was overall improvement in base deficit (p = 0.01) and plasma lactate (p = 0.04) with a trend towards lower inotrope score. Serial echocardiography revealed lower pulmonary artery pressure, improved right and left ventricular output, and reduced bidirectional or right-left shunting (p < 0.05) after milrinone treatment. CONCLUSIONS: The pharmacokinetics of milrinone in persistent pulmonary hypertension of the newborn is consistent with published data. The administration of intravenous milrinone led to better oxygenation and improvements in pulmonary and systemic hemodynamics in patients with suboptimal response to inhaled nitric oxide. These data support the need for a randomized controlled trial in neonates.

Pediatric analgesic clinical trial designs, measures, and extrapolation: report of an FDA scientific workshop.

Analgesic trials pose unique scientific, ethical, and practical challenges in pediatrics. Participants in a scientific workshop sponsored by the US Food and Drug Administration developed consensus on aspects of pediatric analgesic clinical trial design. The standard parallel-placebo analgesic trial design commonly used for adults has ethical and practical difficulties in pediatrics, due to the likelihood of subjects experiencing pain for extended periods of time. Immediate-rescue designs using opioid-sparing, rather than pain scores, as a primary outcome measure have been successfully used in pediatric analgesic efficacy trials. These designs maintain some of the scientific benefits of blinding, with some ethical and practical advantages over traditional designs. Preferred outcome measures were recommended for each age group. Acute pain trials are feasible for children undergoing surgery. Pharmacodynamic responses to opioids, local anesthetics, acetaminophen, and nonsteroidal antiinflammatory drugs appear substantially mature by age 2 years. There is currently no clear evidence for analgesic efficacy of acetaminophen or nonsteroidal antiinflammatory drugs in neonates or infants younger than 3 months of age. Small sample designs, including cross-over trials and N of 1 trials, for particular pediatric chronic pain conditions and for studies of pain and irritability in pediatric palliative care should be considered. Pediatric analgesic trials can be improved by using innovative study designs and outcome measures specific for children. Multicenter consortia will help to facilitate adequately powered pediatric analgesic trials.

The effect of distant reiki on pain in women after elective Caesarean section: a double-blinded randomised controlled trial.

INTRODUCTION: Approximately 25% of all babies in North America are delivered via Caesarean section (C-section). Though a common surgical procedure, C-section recovery can be painful. Opioids, specifically codeine, are commonly used to ease pain; however, its active metabolite, morphine, passes into breast milk, and may produce unwanted side effects in neonates; therefore, alternatives to opioids are being sought. Reiki is an ancient Japanese form of healing where practitioners transfer healing energy through light touch and positive healing intention. Although 1.2 million Americans use reiki to reduce pain or depression, there is a lack of strong evidence supporting its effectiveness. A recent systematic review showed existing studies to be of poor methodological quality, with the common limitation of lack of blinding. To overcome this issue, the authors used distant reiki to assess its effectiveness in reducing pain following an elective C-section. METHODS: In this randomised, double-blinded study, women who underwent an elective C-section were allocated to either usual care (control, n=40) or three distant reiki sessions in addition to usual care (n=40). Pain was assessed using a visual analogue scale (VAS). The primary endpoint was the Area Under the VAS-Time Curve (AUC) for days 1-3. Secondary measures included: the proportion of women who required opioid medications and dose consumed, rate of healing and vital signs. RESULTS: AUC for pain was not significantly different in the distant reiki and control groups (mean ± SD; 212.1 ± 104.7 vs 223.1 ± 117.8; p=0.96). There were no significant differences in opioid consumption or rate of healing; however, the distant reiki group had a significantly lower heart rate (74.3 ± 8.1 bpm vs 79.8 ± 7.9 bpm, p=0.003) and blood pressure (106.4 ± 9.7 mmHg vs 111.9 ± 11.0 mmHg, p=0.02) post surgery. CONCLUSION: Distant reiki had no significant effect on pain following an elective C-section. Clinical Trial Registration Number ISRCTN79265996.

Safety and efficacy of ketorolac in children after cardiac surgery.

OBJECTIVE: To evaluate the nephrotoxic and opioid-sparing effects of ketorolac in children after cardiac surgery. DESIGN: A retrospective cohort study. SETTING: A Cardiac Critical Care Unit in a university-affiliated children's hospital. SUBJECTS: Children less than 18 years of age who underwent low-risk cardiac surgery from July 2002 to December 2005. RESULTS: Among 248 children studied, 108 received ketorolac and 140 did not. The ketorolac group was older, included a larger proportion of atrial septum defect repairs and a smaller proportion of ventricular septum defect repairs compared to the control group. The median change in serum creatinine did not differ between the ketorolac group and the control group (% change [IQR]); 12% [1-25] increase versus 12% [-3 to 31] increase, P = 0.86. On postoperative day 0 or 1, the ketorolac group received less opioids than control group. There was no difference in duration of mechanical ventilation or in length of stay between groups. CONCLUSION: Ketorolac started in the first 12 h after a low-risk cardiac surgery in children is not associated with a measurable difference in renal function. The data suggest that ketorolac may be effective in reducing the exposure to opioids. Further studies are required to define subsets of children after cardiac surgery who could safely benefit from ketorolac therapy to reduce pain.

Effect of iron content on the tolerability of prenatal multivitamins in pregnancy.

BACKGROUND: Gastrointestinal irritability can deter pregnant women from starting or continuing prenatal multivitamin supplementation. In a previous study, suboptimal tolerability was observed among pregnant women taking a large tablet (18 mm x 8 mm x 8 mm) multivitamin with high elemental iron content (60 mg as ferrous fumarate). The objective of the present study was to compare rates of adherence and reported adverse events among pregnant women who were randomized to commence supplementation with a small-tablet prenatal multivitamin, containing either low or high iron content. METHODS: Pregnant women who called the Motherisk Program (Hospital for Sick Children, Toronto) and had not started taking or had discontinued any multivitamin due to adverse events were included in this prospective, randomized, open-label, 2-arm study. Women were randomized to take a small-size (16 mm x 9 mm x 4 mm), low elemental iron content (35 mg as ferrous fumarate) multivitamin ('35 mg' group); or a small-size (5 mm radius, 5 mm thickness), high elemental iron content (60 mg as ferrous sulphate) multivitamin ('60 mg' group). Follow-up interviews documented pill intake and adverse events. Rates of adherence and adverse events were compared between groups using chi-squared tests and Kaplan-Meier survival curves. RESULTS: Of 167 randomized women, 92 in the '35 mg' group and 75 in the '60 mg' group were included in the analysis. Despite ideal conditions and regular follow-ups, mean adherence based on pill intake recall, in both groups was approximately 50%. No statistically significant difference was detected in proportions of women who actually started taking either multivitamin. Among those who started, no difference was detected in rates of adherence or reported adverse events. CONCLUSION: The present results suggest that iron content is not a major determinant of adherence to prenatal multivitamins. Combined with our previous study, tablet size may be the more definitive factor affecting adherence.

Development and validation of the pediatric nausea assessment tool for use in children receiving antineoplastic agents.

STUDY OBJECTIVE: To develop and validate an instrument to assess nausea intensity in children aged 4-18 years. DESIGN: Prospective, descriptive study. SETTING: Tertiary-quaternary, university-affiliated pediatric hospital. PATIENTS: Four pediatric inpatient groups (177 patients): group 1 (107), those receiving cancer chemotherapy; group 2 (24), those receiving cancer chemotherapy before hematopoietic stem cell transplantation; group 3 (23), those with cancer who were not receiving cancer chemotherapy; and group 4 (23), those without cancer. INTERVENTION: We developed a scale with a standard script for administration, the Pediatric Nausea Assessment Tool (PeNAT). Revisions were made after face validity testing with clinicians and parents, and pilot testing with 15 inpatients undergoing chemotherapy. MEASUREMENTS AND MAIN RESULTS: The PeNAT scores were obtained 4-24 hours after chemotherapy in groups 1 and 2. Dietary intake scores and number of emetic episodes were recorded for the 4 hours before PeNAT administration for all patients in group 2 and 36 patients in group 1. Parents of a subset of patients made an independent assessment of their child's nausea and pain intensities immediately before PeNAT administration. Reliability was evaluated in groups 1 and 2 by correlating the first and second (obtained 1 hr after the first) PeNAT scores. Construct validity was evaluated by comparing PeNAT scores in groups 1-4. Criterion-related validity was evaluated by correlating PeNAT scores with emetic episodes and dietary intake. Convergent and discriminant validity were evaluated by correlating PeNAT scores with parental assessments of nausea and pain. Significant differences in PeNAT scores were noted among the study groups (p=0.035). Moderate correlation was noted between the first and second PeNAT scores (Spearman rho = 0.649). The PeNAT scores correlated modestly with emetic episodes (Spearman rho = 0.322) but not with dietary intake (Spearman rho = -0.217). Children's PeNAT scores correlated moderately with their parents' assessment of nausea (Spearman rho = 0.442), whereas little correlation was seen between children's PeNAT scores and parents' assessment of pain (Spearman rho = 0.167). CONCLUSION: The PeNAT is a new instrument that can be used by children to assess nausea intensity.

Summary proceedings from the neonatal pain-control group.

Recent advances in neurobiology and clinical medicine have established that the fetus and newborn may experience acute, established, and chronic pain. They respond to such noxious stimuli by a series of complex biochemical, physiologic, and behavioral alterations. Studies have concluded that controlling pain experience is beneficial with respect to short-term and perhaps long-term outcomes. Yet, pain-control measures are adopted infrequently because of unresolved scientific issues and lack of appreciation for the need for control of pain and its long-term sequelae during the critical phases of neurologic maturation in the preterm and term newborn. The neonatal pain-control group, as part of the Newborn Drug Development Initiative (NDDI) Workshop I, addressed these concerns. The specific issues addressed were (1) management of pain associated with invasive procedures, (2) provision of sedation and analgesia during mechanical ventilation, and (3) mitigation of pain and stress responses during and after surgery in the newborn infant. The cross-cutting themes addressed within each category included (1) clinical-trial designs, (2) drug prioritization, (3) ethical constraints, (4) gaps in our knowledge, and (5) future research needs. This article provides a summary of the discussions and deliberations. Full-length articles on procedural pain, sedation and analgesia for ventilated infants, perioperative pain, and study designs for neonatal pain research were published in Clinical Therapeutics (June 2005).

Pain, opioid tolerance and sensitisation to nociception in the neonate.

Pain is commonplace in newborn infants. Opioid analgesics have become increasingly used to reduce different types of pain in neonates, including pain from surgery, medical procedures and chronic conditions. Adverse effects of opioids include respiratory depression, hypotension and tolerance. These adverse effects can be minimised by utilising specific administration techniques and constant monitoring. Recent studies have demonstrated that untreated pain can have long-term effects on infant pain behaviours months beyond the events, thus, opioid analgesics may have a beneficial role that extends beyond the immediate painful event(s).

Tobramycin pharmacokinetics in children with febrile neutropenia undergoing stem cell transplantation: once-daily versus thrice-daily administration.

STUDY OBJECTIVE: To describe the pharmacokinetic disposition of tobramycin in children undergoing stem cell transplantation (SCT) after intravenous administration either every 24 hours or every 8 hours, and to use this information to create initial dosing guidelines for administration every 24 hours in this patient population. DESIGN: Pharmacokinetic analysis of a randomized controlled trial. SETTING: The Hospital for Sick Children, Toronto, Ontario, Canada. PATIENTS: Sixty children (< 18 yrs) with febrile neutropenia undergoing stem cell transplantation. INTERVENTION: Patients were randomized to receive intravenous tobramycin either every 24 hours (29 patients) or every 8 hours (31 patients). Initially, they received either 2.5 mg/kg/dose every 8 hours or weight-based doses by age group (< 5 yrs, 9 mg/kg/dose; 5 to < 12 yrs, 8 mg/kg/dose; > or = 12 yrs, 7 mg/kg/dose) every 24 hours. MEASUREMENTS AND MAIN RESULTS: Serum tobramycin concentrations were obtained at 2 and 8 hours after the first dose. Initial guidelines for dosing every 24 hours were derived using the parameters from all patients to achieve a maximum serum concentration (Cmax) of 20-22.5 mg/L and a drug-free interval (time during dosing interval when the tobramycin concentration was < 1 mg/L) of at least 4 hours. After the first tobramycin dose, the elimination rate constant (kel) and volume of distribution (Vd) observed in the every-8-hour group (23 patients) were 0.34 +/- 0.09 hours(-1) and 0.48 +/- 0.21 L/kg, respectively. The kel and Vd in the every-24-hour group (22 patients) were 0.43 +/- 0.12 hr(-1) and 0.43 +/- 0.26 L/kg, respectively. Tobramycin Vd varied with age. Initial doses of tobramycin every 24 hours recommended to achieve the target parameters are 10 mg/kg/dose for patients aged 6 months to less than 9 years, 8 mg/kg/dose for those aged 9 to less than 12 years, and 6 mg/kg/dose for those aged 12 years or older. CONCLUSION: Children undergoing SCT who receive tobramycin every 24 hours should receive an initial dose based on age. Further validation of the proposed dosing guidelines is required.

Randomized controlled trial of once- versus thrice-daily tobramycin in febrile neutropenic children undergoing stem cell transplantation.

BACKGROUND: The benefits of aminoglycoside antibiotics, such as tobramycin, administered as a once-daily dose to manage febrile neutropenia, have been demonstrated in many patient populations. However, toxicity and safety data are lacking for pediatric stem cell transplant recipients, who are at especially high risk for aminoglycoside-related toxicity and infectious morbidity. In particular, the relative nephrotoxicity and efficacy of tobramycin administered as a single daily dose or as three daily doses among this patient population is not known. METHODS: We conducted a randomized, double-blind controlled study of tobramycin dosing among children 18 years or younger who had fever and neutropenia while undergoing stem cell transplantation. From October 2000 through November 2002, 60 children were randomly assigned to receive intravenous tobramycin, as either a single daily dose (n = 29) or every 8 hours (n = 31), in combination with either piperacillin or ceftazidime (intravenous). Tobramycin doses were adjusted to achieve pharmacokinetic targets. The primary outcome was nephrotoxicity, as represented by the maximal percent increase in serum creatinine concentration throughout the episode of febrile neutropenia relative to the baseline serum creatinine concentration. Efficacy was a secondary outcome and was defined as survival of the episode without modification of the antibacterial regimen. All statistical tests were two-sided. RESULTS: In a modified intent-to-treat analysis, the mean maximal percent increase in serum creatinine concentration was 32% (N = 26) in the once daily dose group and 51% (N = 28) in the every 8 hours dose group (difference = 19%, 95% confidence interval [CI] = 0% to 38%; P =.054). Among patients evaluable for efficacy, 12 (46%) of 26 patients in the once daily dose group and five (19%) of 27 patients in the every 8 hours dose group survived the episode of febrile neutropenia without requiring antibacterial treatment modification (difference = 27%, 95% CI = 4% to 52%; P =.03). There was one death in each group. CONCLUSIONS: In febrile neutropenic children undergoing stem cell transplantation, tobramycin may be less nephrotoxic and more efficacious when administered as a once daily dose than when administered every 8 hours.

High dose alfentanil pre-empts pain after abdominal hysterectomy.

This study tested the hypothesis that high dose systemic alfentanil administered before and during abdominal hysterectomy would pre-empt post-operative pain to a greater extent than administration of either low dose alfentanil or no alfentanil perioperatively. Patients (ASA 1 or 2) were randomly assigned to group 1 (n = 15), no opioid; group 2 (n = 15), low dose alfentanil; or group 3 (n = 15), high dose alfentanil. Anaesthesia was induced in group 1 with midazolam and thiopentone and was maintained with isoflurane and 70% N2O in O2. Anaesthesia was induced in group 2 with midazolam, thiopentone and i.v. alfentanil (30 microg kg(-1)), and was maintained with isoflurane, 70% N2O in O2, and bolus doses of i.v. alfentanil (10-20 microg kg(-1)) every hour. Anaesthesia was induced in group 3 with midazolam and i.v. alfentanil (100 microg kg(-1)), and was maintained with 70% N2O in O2, and an infusion of i.v. alfentanil (1-2 microg kg(-1) min(-1)). Blood samples were drawn at 30 and 120 min after surgery and assayed for plasma alfentanil. Morphine consumption and VAS pain scores were consistently lowest in group 3 over the 48 h study period. A composite measure of pain and morphine consumption was significantly lower in group 3 than group 2 up to 6 h after surgery, and significantly lower than group 1 up to 12 h. No adverse effects were observed. A 6-month follow-up did not reveal any significant differences among the three groups. It is concluded that intra-operative high dose alfentanil anaesthetic pre-empts post-operative pain after abdominal hysterectomy, but the effects are small and of short duration. Surgical procedures carried out under general anaesthesia using standard (and even high) doses of opioids intraoperatively provide suboptimal protection from the injury barrage brought about by incision and subsequent noxious surgical events.