Pain after orthopaedic surgery: differences in patient reported outcomes in the United States vs internationally. An observational study from the PAIN OUT dataset

BACKGROUND

A previous PAIN OUT study found that American orthopaedic-surgical patients rated 'worst pain' higher than did similar European patients. This study aims to confirm these findings in a larger, international patient sample, explore whether risk factors for greater postoperative pain exist disproportionately in the American population, and confirm the findings for one procedure.

METHODS

Surveyors collected patient reported outcomes (PROs) and perioperative pain management practices using PAIN OUT methodology. Most PROs used 11-point numerical rating scales (0=null, 10=worst possible). Risk factors included: female gender, younger age, high BMI, chronic pain, and opioid use before surgery. Initial analysis used a mixed patient cohort. A secondary analysis used only patients undergoing total knee replacement (TKR). Inference was based primarily on effect size using Cohen's d.

RESULTS

13,770 patients in 13 European and non-European countries (international ) and 564 patients from the United States (US) contributed data on the 1st postoperative day. Three of 11 PROs differed between the cohorts: 'worst pain' {US 7.5 (2.5) vs international 5.6 (2.8); d=0.66 [confidence interval (CI) 0.58-0.75]}; proportion 'receiving information about treatment options' [US 0.86 vs international 0.66; d=0.53 (CI 0.39-0.66)]; reporting adverse effects and their severity [US 0.87 vs international 0.73; d=0.52 (CI 0.38-0.66)]. Risk factors did not differ between the two cohorts. PROs and management patterns in TKR patients were similar to the mixed cohort.

CONCLUSIONS

Three PROs differed between international and US patients, with higher 'worst pain' for US patients. Neither risk factors, nor patient mix accounted for the observed differences for 'worst pain'.

CLINICAL TRIAL REGISTRATION

NCT 02083835.

Pain perception and assessment

Our inability to measure pain effectively is a major barrier to progress in pain research and advancement in clinical interventions for pain. Historically, the mind-body dichotomy has constrained our thinking about pain and its quantification. One line of work has pursued pain as the sensory end product of nociception: pain is the realization of signals of tissue injury arriving at the cortex. At the other extreme, some clinicians contend that pain is ''what the patient says it is''. In other words, it is a purely mental and entirely subjective phenomenon. Research on functional brain imaging, psychophysiological research and recent neurophysiological research on animal models provide confluent evidence that both of these positions are misleading oversimplifications. Pain is the emergent product of massive, parallel, distributed processing in the brain that engages structures involved in emotion and cognition as well as in sensation. To advance pain measurement, our research team has examined Sokolov's defense response in human subjects experiencing repeated, brief painful electrical shocks delivered to a fingertip through a tiny electrode. Sokolov proposed that threatening events elicit a hypothalamically-orchestrated pattern of arousal that prepares the organism to cope with threat. Measures of sympathetic nervous system arousal and brain evoked potentials in our subjects reveal a stable pattern of this sort when we subject the data to structural equation modeling. When subjects undergo equally intense shocks delivered through a large electrode, they experience a strong vibration-like, unpleasant sensation that causes discomfort but not nociception. The non-painful shock elicits broad levels of arousal equal to those obtained with painful shocks in subjects, but structural equation modeling demonstrates that such arousal does not conform to the defense response pattern. Moreover, multivariate measures of sympathetic arousal and evoked potentials can discriminate painful from non-painful stimuli more accurately than can subjective pain reports. These observations suggest that pain may have a unique psychophysiological signature. More importantly, perhaps, this approach suggests that the combination of psychophysiological research and multivariate statistics provides an avenue for advancing pain research outside of the mind-body dichotomy.

Sensory and affective dimensions of phasic pain are indistinguishable in the self-report and psychophysiology of normal laboratory subjects

This study evaluated the discriminant validity of subjects differentially scaling the sensory and affective dimensions of pain. It sought to determine (1) whether subjects can differentially scale sensory and affective aspects of phasic laboratory pain in the absence of task demand bias that fosters apparent differential scaling; (2) whether psychophysiologic responses to painful stimuli can predict pain report (PR); and (3) whether such responses contribute more to affective than to sensory judgments. Fifty-six men and 44 women repeatedly experienced varied painful electrical fingertip stimuli at low, medium, and high intensities. On half of the trial blocks, subjects made sensory judgments; on the remainder they made affective judgments. Response measures included PR, pupil dilation, heart rate, respiration rate, skin conductance response (SCR), and late near field evoked potentials. Subjects did not rate the stimuli differently when making sensory versus affective judgments. The psychophysiologic variables, principally the SCR, accounted for 44% of the variance in the PR. Psychophysiologic response patterns did not differentiate affective and sensory judgment conditions. Noteworthy sources of individual differences included baseline PR levels and the linear effects of SCR on PR.

A passion of the soul: an introduction to pain for consciousness researchers

Pain is an important focus for consciousness research because it is an avenue for exploring somatic awareness, emotion, and the genesis of subjectivity. In principle, pain is awareness of tissue trauma, but pain can occur in the absence of identifiable injury, and sometimes substantive tissue injury produces no pain. The purpose of this paper is to help bridge pain research and consciousness studies. It reviews the basic sensory neurophysiology associated with tissue injury, including transduction, transmission, modulation, and central representation. In addition, it highlights the central mechanisms for the emotional aspects of pain, demonstrating the physiological link between tissue trauma and mechanisms of emotional arousal. Finally, we discuss several current issues in the field of pain research that bear on central issues in consciousness studies, such as sickness and sense of self.

Requirement of sequences outside the conserved kinase domain of fission yeast Rad3p for checkpoint control

The fission yeast Rad3p checkpoint protein is a member of the phosphatidylinositol 3-kinase-related family of protein kinases, which includes human ATMp. Mutation of the ATM gene is responsible for the disease ataxia-telangiectasia. The kinase domain of Rad3p has previously been shown to be essential for function. Here, we show that although this domain is necessary, it is not sufficient, because the isolated kinase domain does not have kinase activity in vitro and cannot complement a rad3 deletion strain. Using dominant negative alleles of rad3, we have identified two sites N-terminal to the conserved kinase domain that are essential for Rad3p function. One of these sites is the putative leucine zipper, which is conserved in other phosphatidylinositol 3-kinase-related family members. The other is a novel motif, which may also mediate Rad3p protein-protein interactions.

Suffering: the contributions of persistent pain

Pain is a perceived threat or damage to one's biological integrity. Suffering is the perception of serious threat or damage to the self, and it emerges when a discrepancy develops between what one expected of one's self and what one does or is. Some patients who experience sustained unrelieved pain suffer because pain changes who they are. At a physiological level, chronic pain promotes an extended and destructive stress response characterised by neuroendocrine dysregulation, fatigue, dysphoria, myalgia, and impaired mental and physical performance. This constellation of discomforts and functional limitations can foster negative thinking and create a vicious cycle of stress and disability. The idea that one's pain is uncontrollable in itself leads to stress. Patients suffer when this cycle renders them incapable of sustaining productive work, a normal family life, and supportive social interactions. Although patients suffer for many reasons, the physician can contribute substantially to the prevention or relief of suffering by controlling pain. Suffering is a nebulous concept for most physicians, and its relation to pain is unclear. This review offers a medically useful concept of suffering that distinguishes it from pain, accounts for the contributory relation of pain to suffering by describing pain as a stressor, and explores the implications of these ideas for the care of patients.

Phasic pupil dilation response to noxious stimulation in normal volunteers: relationship to brain evoked potentials and pain report

Pupillary response to noxious stimulation was investigated in men (n = 11) and women (n = 9). Subjects experienced repeated trials of noxious electrical fingertip stimulation at four intensities, ranging from faint to barely tolerable pain. Measures included pupil dilation response (PDR), pain report (PR), and brain evoked potentials (EPs). The PDR began at 0.33 s and peaked at 1.25 s after the stimulus. Multivariate mixed-effects analyses revealed that (a) the PDR increased significantly in peak amplitude as stimulus intensity increased, (b) EP peaks at 150 and 250 ms differed significantly in both amplitude and latency across stimulus intensity, and (c) PR increased significantly with increasing stimulus intensity. Men demonstrated a significantly greater EP peak amplitude and peak latency at 150 ms than did women. With sex and stimulus intensity effects partialled out, the EP peak latency at 150 ms significantly predicted PR, and EP peak amplitude at 150 ms significantly predicted the PDR peak amplitude.

Measurement in pain therapy: is pain relief really the endpoint?

Pain is not an isolated symptom. Severe pain creates fatigue, impairs concentration, compromises mood, degrades sleep and diminishes overall activity level. The goal of intervention for chronic pain must include alleviating the functional impairment that pain produces as well as its discomfort. Evaluating treatment outcome requires: (1) quantification of both pain intensity and pain-related impairment; and (2) review of how the relationship between these variables changes as a function of treatment. Simply tracking pain intensity level as an indicator of pain relief is insufficient and can lead to misinterpretation of the effects of an intervention.

Evidence for a subsurface ocean on Europa

Ground-based spectroscopy of Jupiter's moon Europa, combined with gravity data, suggests that the satellite has an icy crust roughly 150 km thick and a rocky interior. In addition, images obtained by the Voyager spacecraft revealed that Europa's surface is crossed by numerous intersecting ridges and dark bands (called lineae) and is sparsely cratered, indicating that the terrain is probably significantly younger than that of Ganymede and Callisto. It has been suggested that Europa's thin outer ice shell might be separated from the moon's silicate interior by a liquid water layer, delayed or prevented from freezing by tidal heating; in this model, the lineae could be explained by repetitive tidal deformation of the outer ice shell. However, observational confirmation of a subsurface ocean was largely frustrated by the low resolution (>2 km per pixel) of the Voyager images. Here we present high-resolution (54 m per pixel) Galileo spacecraft images of Europa, in which we find evidence for mobile 'icebergs'. The detailed morphology of the terrain strongly supports the presence of liquid water at shallow depths below the surface, either today or at some time in the past. Moreover, lower-resolution observations of much larger regions suggest that the phenomena reported here are widespread.

Episodic plate separation and fracture infill on the surface of Europa. Galileo Imaging Team

Images obtained by the Voyager spacecraft revealed dark, wedge-shaped bands on Europa that were interpreted as evidence that surface plates, 50-100 km across, moved and rotated relative to each other. This implied that they may be mechanically decoupled from the interior by a layer of warm ice or liquid water. Here we report similar features seen in higher resolution images (420 metres per pixel) obtained by the Galileo spacecraft that reveal new details of wedge-band formation. In particular, the interior of one dark band shows bilateral symmetry of parallel lineaments and pit complexes which indicates that plate separation occurred in discrete episodes from a central axis. The images also show that this style of tectonic activity involved plates < 10 km across. Although this tectonic style superficially resembles aspects of similar activity on Earth, such as sea-floor spreading and the formation of ice leads in polar seas, there are significant differences in the underlying physical mechanisms: the wedge-shaped bands on Europa most probably formed when lower material (ice or water) rose to fill the fractures that widened in response to regional surface stresses.

Hypnotic analgesia: a constructivist framework

Hypnotic analgesia remains an enigma. Recent neuroscience studies demonstrate that widespread distributed processing occurs in the brains of individuals experiencing pain. Emerging research and theory on the mechanisms of consciousness, along with this evidence, suggest that a constructivist framework may facilitate both pain research and the study of hypnosis. The authors propose that the brain constructs elements of pain experience (pain schemata) and embeds them in ongoing consciousness. The contents of immediate consciousness feed back to nonconscious, parallel distributed processes to help shape the character of future moments of consciousness. Hypnotic suggestion may interact with such processing through feedback mechanisms that prime associations and memories and thus shape the formation of future experience.

Pain and the choice to hasten death in patients with painful metastatic cancer

Unrelieved pain has been cited as an important reason why cancer patients may seek to hasten their deaths. We interviewed 48 patients with painful metastatic cancer to ascertain their interest in various active and passive modes of hastening death. Ninety percent of these patients supported the general right of terminally ill patients to passive modes of hastening death and 80% supported the right to active modes such as assisted suicide and euthanasia. If they developed severe pain that could not be relieved, 80% would instruct their physician write a "do not attempt resuscitation" order, 40%-50% would want to receive suicide information or a lethal prescription from their physician, and 34% would request a lethal injection from their physician. Current pain and depression levels were not associated with interest in hastening death, but current somatic symptom burden was significantly associated with this interest.

Comparative efficacy of patient-controlled administration of morphine, hydromorphone, or sufentanil for the treatment of oral mucositis pain following bone marrow transplantation

A total of 119 bone marrow transplant patients suffering from oral mucositis pain were enrolled in a randomized, double-blind, parallel-group trial comparing the efficacy of patient-controlled analgesia with morphine, hydromorphone and sufentanil. Patient ratings of pain and side-effects on visual analog scales were gathered daily from the start of patient-controlled analgesia (PCA) therapy until the discontinuation of opioid treatment either because of resolution of oral mucositis pain, intolerable side-effects, inadequate pain control, or complications related to transplantation. Of the 119 enrolled subjects, 100 met the evaluable criteria of developing oral mucositis and remaining on the study for at least 2 days. Multivariate analysis of the outcome measures indicated that the analgesia achieved in all three opioid groups was nearly equivalent, while measures of side-effects, especially for the combination of sedation, sleep and mood disturbances, were statistically lower in the morphine group than in hydromorphone or sufentanil groups. Patients in the hydromorphone group exhibited the most variability in pain control. Event analysis also indicated significant differences in time to treatment failure between the three groups, with the morphine arm exhibiting clear superiority. The proportion of patients discontinued because of inadequate pain relief was much higher in the sufentanil group (7/36) as compared to the hydromorphone (0/34) or the morphine group (1/30). The daily opioid consumption pattern showed a continual dose escalation during the first week of therapy for all groups, coincident with worsening mucositis. Morphine consumption reached a plateau by day 5, whereas hydromorphone and sufentanil consumption continued to rise until days 7 and 9, respectively. Sufentanil dose requirement increased by approximately 10-fold compared to morphine and hydromorphone, whose requirements increased only 5-fold, suggesting the possibility of development of acute pharmacological tolerance in some patients with this phenylpiperidine opioid. This study provides support for the recommendation that morphine is the opioid of first choice when patient-controlled analgesia is employed for the treatment of severe oropharyngeal pain in bone marrow transplantation (BMT) patients.

Differences among patients in opioid self-administration during bone marrow transplantation

The distinctive features of individual patients, here termed individual differences, are inescapable aspects of day-to-day patient pain management, but classically designed research studies ignore such differences. This paper introduces statistical pattern visualization methodology for the study of complex individual differences in clinical settings. We demonstrate the application of such methods in patients undergoing bone marrow transplantation (BMT) and suffering severe oral mucositis as a consequence of the aggressive BMT preparative regimen. Oral mucositis produces severe pain and patients often require parenteral opioid medication for several weeks. Unfortunately, the opioid can cause side-effects that limit drug use for pain control. Patients differ in severity and duration of oral mucositis, analgesic response to opioids, and side-effects. We identified and classified individual differences in patterns of drug use, pain control and side-effects in 33 BMT patients who received opioid drug via patient-controlled analgesia (PCA) systems for 7 days or more. These systems allowed bolus dosing and also provided a basic level of analgesic protection through continuous drug infusion. Continuous infusion levels increased or decreased in response to patient bolus self-administration. We employed statistical smoothing (moving average) techniques to remove random variation from the individual data sets and created three-way (trivariate) plots of change over time in drug use, pain and an opioid side-effect (impairment of concentration). The patterns apparent in these plots indicated that 24.2% of patients used PCA optimally (increases in drug use associated with reductions in pain and little or no side-effect), an additional 30.3% manifested a potentially optimal pattern limited by side-effect that worsened with dosing, and 36.4% used PCA suboptimally (modest pain control plus side-effects). In addition, for each subject we created a summary measure for the simultaneous change in three variables: the distance of each day's trivariate score from the origin of a three dimensional plot. This summary measure correlated significantly with the changing severity of patients' oral mucositis over time (r = 0.502). This study demonstrates how interactive graphic techniques can provide a basis for examining changes over time among multiple, correlated variables associated with a single individual. It illustrates the application of such techniques and demonstrates that individual subject data sets merit examination in cases where clinical data reflect human performance.

rqh1+, a fission yeast gene related to the Bloom's and Werner's syndrome genes, is required for reversible S phase arrest

In eukaryotic cells, S phase can be reversibly arrested by drugs that inhibit DNA synthesis or DNA damage. Here we show that recovery from such treatments is under genetic control and is defective in fission yeast rqh1 mutants. rqh1+, previously known as hus2+, encodes a putative DNA helicase related to the Escherichia coli RecQ helicase, with particular homology to the gene products of the human BLM and WRN genes and the Saccharomyces cerevisiae SGS1 gene. BLM and WRN are mutated in patients with Bloom's syndrome and Werner's syndrome respectively. Both syndromes are associated with genomic instability and cancer susceptibility. We show that, like BLM and SGS1, rqh1+ is required to prevent recombination and that in fission yeast suppression of inappropriate recombination is essential for reversible S phase arrest.

Hydromorphone analgesia after intravenous bolus administration

This study investigated the analgesic effects of three intravenous bolus doses of hydromorphone (10, 20, 40 micrograms/kg) on experimental pain measures in normal humans. Ten healthy male volunteers participated in four study sessions, one for each of the hydromorphone doses as well as a placebo (saline). They received the four treatments in counterbalanced order under double-blind conditions and with study days at least 1 week apart. During each session subjects underwent repeated electrical tooth pulp stimulation at intensities sufficient to elicit a rating of 'strong pain' before drug administration. Subjective pain reports (PRs) and dental evoked potential amplitude measures (EPs) served as analgesic effect indicators. We observed dose-dependent analgesia as measured by both PR (P = 0.009) and EP (P = 0.017). Area under the PR versus time curve as well as the EP versus time curve decreased in a log dose-dependent fashion. Although the peak effect was poorly defined, the onset of analgesia was rapid, within 5 min, and maximum analgesic effect was seen between 10 and 20 min after maximum plasma hydromorphone concentration. However, within sessions we found a poor correspondence between hydromorphone plasma concentration and effect. Compared to pain report data from other human studies done in our laboratory, hydromorphone has a shorter time to peak effect compared to morphine, and overall, hydromorphone hydrochloride is approximately five times as potent as morphine sulfate on a milligram basis.

Clinical analgesic equivalence for morphine and hydromorphone with prolonged PCA

A morphine to hydromorphone equivalence ratio of 7:1 has become the accepted standard, but evidence supporting it comes from single dose studies performed before the advent of patient controlled analgesia (PCA). We compared morphine and hydromorphone use with PCA in bone marrow transplantation patients who required opioids for the control of severe oral mucositis over several days or weeks. An exploratory analysis of clinical records from 102 patients (981 patient days) who used PCA opioids for varying periods of up to 50 days suggested a morphine to hydromorphone use ratio of 3:1. To clarify this observation, we studied a subset of patients under matched conditions. During a 7 day window in which mean oral mucositis severity did not vary across drug use groups and pain scores did not vary over time, patients in both groups gave equal pain relief satisfaction scores. Thirty-six patients who used morphine and 21 who used hydromorphone contributed data on pain, satisfaction with pain control, and drug consumption. We observed an average morphine/hydromorphone ratio of 3:1. This differs markedly from historical single dose studies used in published dose equivalency recommendations implying that other equivalency ratios in clinical use may be inappropriate.

Galileo's First Images of Jupiter and the Galilean Satellites

The first images of Jupiter, Io, Europa, and Ganymede from the Galileo spacecraft reveal new information about Jupiter's Great Red Spot (GRS) and the surfaces of the Galilean satellites. Features similar to clusters of thunderstorms were found in the GRS. Nearby wave structures suggest that the GRS may be a shallow atmospheric feature. Changes in surface color and plume distribution indicate differences in resurfacing processes near hot spots on Io. Patchy emissions were seen while Io was in eclipse by Jupiter. The outer margins of prominent linear markings (triple bands) on Europa are diffuse, suggesting that material has been vented from fractures. Numerous small circular craters indicate localized areas of relatively old surface. Pervasive brittle deformation of an ice layer appears to have formed grooves on Ganymede. Dark terrain unexpectedly shows distinctive albedo variations to the limit of resolution.

Effects of combining propofol and alfentanil on ventilation, analgesia, sedation, and emesis in human volunteers

BACKGROUND

Propofol and alfentanil frequently are administered together for intravenous sedation. This study investigated pharmacokinetic and pharmacodynamic interactions between propofol and alfentanil, at sedative concentrations, with specific regard to effects on ventilation, analgesia, sedation, and nausea.

METHODS

Ten male volunteers underwent steady-state infusions on 3 separate days consisting of propofol alone, alfentanil alone, or a combination of the two. Target plasma concentrations for propofol were 150, 300, and 600 ng/ml for 1 h at each concentration; for alfentanil it was 40 ng/ml for 3 h. Assessment included serial measurements of (1) ventilatory function (minute ventilation, carbon dioxide production, end-tidal carbon dioxide, ventilatory response to rebreathing 7% CO2); (2) analgesia (subjective pain report in response to graded finger shock and evoked potential amplitude); (3) sedation (subjective rating, observer scores, and digit symbol substitution test); (4) nausea (visual analog scale, 0-100 mm).

RESULTS

During combination treatment, propofol plasma concentration was 22% greater than during propofol alone using replicate infusion schemes (P < 0.009). End-tidal carbon dioxide was unchanged by propofol, and increased equally by alfentanil and alfentanil/propofol combined (delta end-tidal carbon dioxide 7.5 and 6.2 mmHg, respectively). Analgesia with propofol/alfentanil combined was greater than with alfentanil alone. (Pain report decreased 50% by PA vs. 28% for alfentanil, P < 0.05). Sedation was greater with propofol/alfentanil combined than with alfentanil or propofol alone (digit symbol substitution test 30 for propofol/alfentanil combined vs. 57 for alfentanil, and 46 for propofol, P < 0.05). Nausea occurred in 50% of subjects during alfentanil, but in none during propofol/alfentanil combination treatment.

CONCLUSIONS

The combination of propofol and alfentanil produced greater sedation and analgesia than that with either drug alone. Propofol offset the emetic effects of alfentanil. Equivalent depression of the carbon dioxide response curve, and elevation of end-tidal carbon dioxide occurred with propofol/alfentanil combined and alfentanil.

Use of patient-controlled analgesia for pain control for children receiving bone marrow transplant

We report 2 years' experience managing 39 preteen (ages 4-12 years) children with patient-controlled analgesia (PCA) for pain associated with bone marrow transplantation (BMT). We prescribed morphine or hydromorphone PCA (starting bolus 20 micrograms/kg morphine or 2 micrograms/kg hydromorphone) with or without continuous infusion (CI), for a period of 6-74 days. The duration of PCA use (median 19 days) depended upon severity of mucositis or other painful conditions. The peak morphine use was on the 11th day after BMT. We prescribed CI opioids in addition to PCA, either at night or around the clock, in 52% of patients. Ninety-five percent of children successfully mastered PCA to control pain associated with BMT. We observed no instances of drug misuse, parental tampering, accidental overdose, or difficulty weaning from opioids. We conclude that opioid PCA, with or without CI, over several days or weeks is safe and effective for preteen children suffering BMT-related pain.

Clinical management of dying patients

Dying is universal, and death should be a peaceful time. Myriad comfort measures are available in the last weeks before life ends. Discussions about end-of-life issues often suffer from lack of informed opinion. Palliative care experts have identified specific somatic and psychological sources of distress for dying patients and their loved ones. Pain, shortness of breath, nausea and vomiting, and fear of abandonment contribute substantially to both physical and psychological discomfort toward the end of life. Simple, effective methods exist for relieving those symptoms. Knowledge about the natural events associated with dying and an informed approach to medical and psychological interventions contribute to systematic and successful comfort care. We describe the origin of physical and psychological distress at the end of life and provide strategies for alleviating many of the discomforts.

First Images of Asteroid 243 Ida

The first images of the asteroid 243 Ida from Galileo show an irregular object measuring 56-kilometers by 24 kilometers by 21 kilometers. Its surface is rich in geologic features, including systems of grooves, blocks, chutes, albedo features, crater chains, and a full range of crater morphologies. The largest blocks may be distributed nonuniformly across the surface; lineaments and dark-floored craters also have preferential locations. Ida is interpreted to have a substantial regolith. The high crater density and size-frequency distribution (-3 differential power-law index) indicate a surface in equilibrium with saturated cratering. A minimum model crater age for Ida-and therefore for the Koronis family to which Ida belongs-is estimated at 1 billion years, older than expected.

Galileo Multispectral Imaging of the North Polar and Eastern Limb Regions of the Moon

Multispectral images obtained during the Galileo probe's second encounter with the moon reveal the compositional nature of the north polar regions and the northeastern limb. Mare deposits in these regions are found to be primarily low to medium titanium lavas and, as on the western limb, show only slight spectral heterogeneity. The northern light plains are found to have the spectral characteristics of highlands materials, show little evidence for the presence of cryptomaria, and were most likely emplaced by impact processes regardless of their age.

Samarium-153-EDTMP in bone metastases of hormone refractory prostate carcinoma: a phase I/II trial

Samarium-153-ethylenediaminetetramethylene phosphoric acid (EDTMP), a bone-seeking radiopharmaceutical, was given to prostate cancer patients in a dose escalation protocol for pain palliation to determine the maximally tolerated dose. Fifty-two patients with hormone refractory prostate cancer with bony metastases were treated with doses beginning at 0.5 mCi/kg (18.5 MBq/kg), escalating in 0.5-mCi (18.5 MBq) increments to 3.0 mCi/kg (111 MBq/kg). Pain response after treatment was assessed as well as hematologic and serum chemistry parameters. Pain palliation with a mean duration of 2.6 mo was present in 74% of the patients. Toxicity was exclusively hematologic at the highest dose levels. No infectious or bleeding complications occurred, with 45 of the 52 (86%) patients demonstrating complete hematologic recovery. Patients receiving higher doses had significantly greater reductions in serum prostate specific antigen and serum prostatic acid phosphatase levels. The patients receiving greater doses also showed a trend toward improved survival.

Lunar Impact Basins and Crustal Heterogeneity: New Western Limb and Far Side Data from Galileo

Multispectral images of the lunar western limb and far side obtained from Galileo reveal the compositional nature of several prominent lunar features and provide new information on lunar evolution. The data reveal that the ejecta from the Orientale impact basin (900 kilometers in diameter) lying outside the Cordillera Mountains was excavated from the crust, not the mantle, and covers pre-Orientale terrain that consisted of both highland materials and relatively large expanses of ancient mare basalts. The inside of the far side South Pole-Aitken basin (>2000 kilometers in diameter) has low albedo, red color, and a relatively high abundance of iron- and magnesium-rich materials. These features suggest that the impact may have penetrated into the deep crust or lunar mantle or that the basin contains ancient mare basalts that were later covered by highlands ejecta.

Concentration-related effects of morphine on cognition and motor control in human subjects

Morphine and other opioid analgesics may interfere with normal cognition and motor function when the drugs are used for long-term treatment of pain. We used individually tailored steady-state drug infusions to identify the nature and extent of cognitive and motor effects of the mu-receptor-selective opioid morphine in healthy volunteers. The tailored infusions allowed evaluation of cognitive and motor effects at three sequential, constant plasma concentrations of morphine in each subject. Compared with functional assessments obtained in a separate saline infusion day, infusions of morphine to plasma concentrations in the usual therapeutic range for analgesia caused significant impairments of some but not all elements of cognitive and motor function. The time needed to encode and process serially presented verbal information increased and the ability to maintain low consistent levels of force decreased during the morphine infusion. We also assessed verbal recall 3 hours after the morphine and saline infusions. Delayed recall of information presented during the morphine infusion was significantly impaired. Our results demonstrate that morphine can interfere with cognitive and motor performance at plasma drug concentrations within the usual therapeutic range.

Images from Galileo of the Venus Cloud Deck

Images of Venus taken at 418 (violet) and 986 [near-infrared (NIR)] nanometers show that the morphology and motions of large-scale features change with depth in the cloud deck. Poleward meridional velocities, seen in both spectral regions, are much reduced in the NIR In the south polar region the markings in the two wavelength bands are strongly anticorrelated. The images follow the changing state of the upper cloud layer downwind of the subsolar point, and the zonal flow field shows a longitudinal periodicity that may be coupled to the formation of large-scale planetary waves. No optical lightning was detected.

Patient-controlled analgesic administration. A comparison of steady-state morphine infusions with bolus doses

The authors have shown previously that bone marrow transplant (BMT) patients who self-administered bolus doses of morphine gained equal oral mucositis pain relief while using less drug compared with similar patients receiving morphine by staff-controlled continuous infusion. In a follow-up study they compared the efficacy and side effects of morphine in two groups of marrow transplant patients who controlled their own analgesic administration either by conventional bolus-dose, patient-controlled analgesia (PCA) or by adjusting the rate of continuous morphine infusion to increase or decrease their plasma morphine concentration. Patients controlling their morphine infusion rates (pharmacokinetically based patient-controlled analgesia [PKPCA] group) obtained more relief from oral mucositis pain than did patients using conventional PCA. Patients in the PKPCA group used more morphine than PCA patients and achieved superior pain relief without significant increases in side effects (e.g., nausea, mood changes, sedation). The authors conclude that PKPCA improves the management of prolonged, severe pain in marrow transplant patients and that this approach to patient-controlled analgesia may be useful in other types of persistent pain.

Steady-state infusions of opioids in human volunteers. I. Pharmacokinetic tailoring

We report a method for controlling and adjusting plasma opioid concentration to preselected target values in individual human subjects in order to study analgesic and other effects of opioids at steady state. The method employs a computer-controlled infusion pump and an algorithm that utilizes individual subject pharmacokinetic parameters predetermined with tailoring bolus opioid doses. We used this approach to produce 3-step increases in plasma concentrations of alfentanil, fentanyl and morphine in each of 15 subjects. We maintained each plasma concentration plateau for 70 min, measured plasma opioid concentrations achieved during the infusions and analyzed the results for bias and precision of the individually tailored infusions. Our results show that pharmacokinetically tailored opioid infusions produce stable plasma opioid concentrations within 10 min for alfentanil and morphine; with each drug overall prediction error was 20% or less. Fentanyl was somewhat more difficult to control by this method than were the other 2 opioids. We conclude that individual tailoring of opioid infusions minimizes the impact of individual pharmacokinetic differences on achieving preselected plasma opioid concentrations and provides an accurate means of controlling steady-state drug concentrations for studies of concentration-effect relationships and comparisons of side-effect intensities produced by equianalgesic plasma opioid concentrations.

Profiles of opioid analgesia in humans after intravenous bolus administration: alfentanil, fentanyl and morphine compared on experimental pain

This report examines the relationship of plasma drug concentration to analgesic effect following bolus doses of alfentanil, fentanyl and morphine and assesses individual differences in analgesic response among volunteers. We predicted that the 3 opioids would yield disparate analgesic profiles because their physicochemical and pharmacokinetic characteristics differ. Ten healthy volunteers received intravenous bolus doses of either alfentanil, fentanyl, morphine or normal saline on different days. We stimulated their teeth electrically and measured brain evoked potential (EP) and pain report (PR) repeatedly over 2 h to assess analgesic effect. Concurrently, we drew 18 blood samples to assess opioid plasma concentrations during the test period. The relationship between opioid plasma concentration and analgesic effect was well defined for alfentanil but ambiguous for morphine. Fentanyl exhibited a marked hysteresis. We observed noteworthy individual differences in analgesic response with all 3 drugs but these differences were greatest for morphine and least for alfentanil. Inter- and intrasubject variability in analgesic response across drugs is related to the physicochemical properties of the drugs tested.

Steady-state infusions of opioids in human. II. Concentration-effect relationships and therapeutic margins

We used computer-controlled individually tailored infusions to study relationships between plasma drug concentration and opioid effects, and to evaluate the therapeutic margins of alfentanil, fentanyl and morphine in human subjects. In order to compare the 3 drugs, we infused each opioid to 3 different steady-state target plasma concentrations during separate 8 h test periods so that concentration-effect curves could be defined for each opioid and subject. Dental electrical stimulation produced a consistent degree of baseline experimental pain, and we measured the influence of increasing plasma opioid concentrations on pain intensity and the magnitude of pain-related evoked potentials. We also quantified ventilatory function and subjective side-effects during baseline (no drug), at the 3 target plasma concentrations with each drug. Finally, we measured actual plasma opioid concentrations during each phase of the infusion period. This procedure allowed us to calculate for each opioid the plasma concentration required to produce a 50% decrease in reported pain intensity and evoked potential amplitude (IC50). Subsequent calculation of side-effect magnitudes at the analgesic IC50s permitted direct comparisons of therapeutic margins between alfentanil, fentanyl and morphine. We found a robust relationship between plasma drug concentration and analgesic, ventilatory, and subjective-effect magnitudes for each opioid in this study. We conclude that the magnitudes of individual side-effects associated with equianalgesic, steady-state plasma concentrations of these 3 mu receptor-selective opioids do not differ across drugs.

Prolonged morphine self-administration and addiction liability. Evaluation of two theories in a bone marrow transplant unit

The technology for patient intravenous self-administration of morphine has been successfully implemented in postoperative and other clinical settings and can be used with terminal patients who experience pain. The question of whether patients who use such instrumentation will be vulnerable to over-medication or development of addiction has not been addressed. This report reviews two competing theories that bear upon this question and tests their predictions about self-administration of morphine for pain relief using data obtained from patients in a bone marrow transplant unit. The first, Opponent Process Theory, predicts escalating drug use and the development of addictive behavior in patients who self-administer morphine. The second, Control Theory, predicts that patients will self-regulate pain effectively by administering morphine without developing problems of medication abuse or addiction. Patients self-administering morphine for 2 weeks were compared to controls who received the drug via routine staff-controlled continuous infusion procedures. Self-administering patients used significantly less morphine than controls and still achieved the same amount of pain control; moreover, they terminated drug use sooner than controls. The predictions based upon Opponent Process Theory were not supported in these marrow transplant patients, but Control Theory accounted well for the outcomes. These results support the assumption that self-administration of opioids in a medical setting does not put patients at risk for over-medication or addiction.

Assessment and management of donor pain following marrow harvest for allogeneic bone marrow transplantation

We studied the time course and intensity of pain of multiple bone marrow aspirations in 30 healthy adult marrow donors receiving acetaminophen with codeine for analgesia immediately after marrow harvesting for allogeneic bone marrow transplantation. Upon discharge, donors were supplied with acetaminophen (315 mg) plus codeine (30 mg) tablets and instructed to use one or two tablets up to every 4 h as needed for pain control. Donors used analgesic medication for a mean (+/- SE) of 3.3 +/- 0.5 days (range = 1-13 days) and reported less than complete pain relief. Subjects reported more pain at time of medication than between doses, indicating that the analgesic was at least partially effective. Male donors tended to report more pain and use more analgesic than did females. We conclude that donors self-regulate their analgesic usage to achieve maximal relief and that incomplete relief with acetaminophen plus codeine may be due to limited efficacy of this analgesic preparation. Our findings suggest that donor pain management may be improved by use of more powerful analgesics.