Wireless patient monitoring and Efficacy Safety Score in postoperative treatment at the ward: evaluation of time consumption and usability

To evaluate objective time consumption and how nurses perceived introducing wireless patient monitoring (WPM) and a validated score on patient quality and safety, the Efficacy Safety Score (ESS), at a mixed surgery ward. After fulfilling a randomised controlled trial combining the ESS and WPM, we addressed time consumption and conducted a questionnaire survey among nurses who participated in the study. The questionnaire appraised the nurses' evaluation of introducing these tools for postoperative management. Of 28 invited nurses, 24 responded to the questionnaire, and 92% reported the ESS and WPM-systems to increase patient safety and quality of care. 67% felt the intervention took extra time, but objective workload measurements revealed reduced time to 1/3 using ESS and WPM compared to standard manual assessment. Improved confidence when using the systems was reported by 83% and improved working situation by 75%. In a test situation to measure time consumption, the ESS and pre-attached WPM-systems require less time than the conventional standard of care, and may allow for more frequent clinical monitoring at the post-surgical ward. The combination of the ESS and the WPM systems was perceived as positive by participating nurses and further clinical development and research is warranted.

Mental disorder prevalence in chronic pain patients using opioid versus non-opioid analgesics: A registry-linkage study

BACKGROUND

Chronic pain and mental disorders are leading causes of disability worldwide. Individuals with chronic pain are more likely to experience mental disorders compared to individuals without chronic pain, but large-scale estimates are lacking. We aimed to calculate overall prevalence of mental health diagnoses from primary and secondary care among individuals treated for chronic pain in 2019 and to compare prevalence among chronic pain patients receiving opioid versus non-opioid analgesics, according to age and gender.

METHODS

It is a population-based cohort study. Linked data from nationwide health registers on dispensed drugs and diagnoses from primary (ICPC-2) and secondary (ICD-10) health care. Chronic pain patients were identified as all patients over 18 years of age filling at least one prescription of an analgesic reimbursed for non-malignant chronic pain in both 2018 and 2019 (N = 139,434, 69.3% women).

RESULTS

Prevalence of any mental health diagnosis was 35.6% (95% confidence interval: 35.4%-35.9%) when sleep diagnoses were included and 29.0% (28.8%-29.3%) when excluded. The most prevalent diagnostic categories were sleep disorders (14% [13.8%-14.2%]), depressive and related disorders (10.1% [9.9%-10.2%]) and phobia and other anxiety disorders (5.7% [5.5%-5.8%]). Prevalence of most diagnostic categories was higher in the group using opioids compared to non-opioids. The group with the highest overall prevalence was young women (18-44 years) using opioids (50.1% [47.2%-53.0%]).

CONCLUSIONS

Mental health diagnoses are common in chronic pain patients receiving analgesics, particularly among young individuals and opioid users. The combination of opioid use and high psychiatric comorbidity suggests that prescribers should attend to mental health in addition to somatic pain.

SIGNIFICANCE

This large-scale study with nation-wide registry data supports previous findings of high psychiatric burden in chronic pain patients. Opioid users had significantly higher prevalence of mental health diagnoses, regardless of age and gender compared to users of non-opioid analgesics. Opioid users with chronic pain therefore stand out as a particularly vulnerable group and should be followed up closely by their physician to ensure they receive sufficient care for both their mental and somatic symptoms.

Cohort Description: Preventing an Opioid Epidemic in Norway - Focusing on Treatment of Chronic Pain (POINT) - A National Registry-Based Study

AIM

The POINT project aims to provide evidence to optimise chronic pain management, prevent adverse consequences of opioids, and improve chronic pain patients' pain relief, functional capacity, and quality of life. We describe the outline of the project and its work packages. More specifically, we describe a cohort of persons with chronic pain and a cohort of long-term opioid users identified from a national registry linkage.

DATA SOURCES

The project utilises data from nationwide healthcare and population registers in Norway. Using the Norwegian Prescription Database, we identified a cohort of persons who have been dispensed drugs reimbursed for chronic pain and a cohort of persons who used opioids long term from 2010 to 2019. Data from the Norwegian Registry for Primary Health Care and the Norwegian Patient Registry (2008-2019), Cancer Registry (1990-2018) Cause of Death Registry (2010-2019) and demographic and socioeconomic registers from Statistics Norway (2010-2019) were linked to the cohorts.

STUDY POPULATION

There were 568,869 participants with chronic pain. Sixty-three percent of the cohort was women, and the mean age was 57.1 years. There were 336,712 long-term opioid users (58.6% women; 60.9 years). In chronic pain and long-term opioid user cohorts, the most frequent musculoskeletal diagnosis was back pain diagnosed in primary care (27.6% and 30.7%). Psychiatric diagnoses were also common.

MAIN VARIABLES

Upcoming studies will utilise psychiatric and somatic diagnoses from the patient registers, drug use from the prescription register, causes of death, demographics, and socioeconomic status (eg, education, income, workability, immigrant status) as exposures or outcomes.

CONCLUSION AND FUTURE PLANS

The two cohorts have numerous pain-related diagnoses, especially in the musculoskeletal system, and noticeably frequent somatic and psychiatric morbidity. The POINT project also includes later work packages that explore prescriber and patient perspectives around safe and effective treatment of chronic pain.

Postoperative quality and safety using Efficacy Safety Score (ESS) and a wireless patient monitoring system at the ward: A randomised controlled study

BACKGROUND

Postoperative pain, side-effects and time to mobilisation are indicators for the quality of postoperative recovery. The aim of this randomised controlled study was to investigate if efficacy safety score (ESS) combined with a wireless patient monitoring system would improve these clinical outcomes for patients at a general surgical ward.

METHODS

The trial included 195 patients randomised to a standard care group (SC-Group) or intervention group (INT-Group) receiving continuous wireless monitoring of vital signs combined with ESS during the first 24 postoperative hours. The primary outcome was time to mobilisation. Secondary outcomes were average pain, doses of postoperative opioids, unscheduled interventions, side-effects, patient satisfaction and length of hospital stay (LOS).

RESULTS

Mean time to postoperative mobilisation was 10.1 hours for patients in the INT-Group compared to 14.2 hours in the SC-Group; this corresponds to an adjusted hazard ratio of 1.54 (95% confidence interval 1.04-2.28). INT-Group patients received a higher dose of oral morphine equivalents; 26 mg vs 15 mg, P < .001; reported lower intensity of pain on a 0-10 scale; 2.1 vs 3.3, P < .001; and had higher patient satisfaction on a 5-point scale; 4.9 vs 4.3, P < .001. The LOS was similar between the groups; 71 hours in INT-Group vs 77 hours in SC-Group, P = .58. No serious side-effects were registered in INT-Group, whereas two were registered in SC-Group.

CONCLUSIONS

Introducing ESS as a decision tool combined with a wireless monitoring system resulted in less pain, increased satisfaction and more rapid mobilisation for patients in this study.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT03438578.

Interpersonal problems as a predictor of pain catastrophizing in patients with chronic pain

Background and aims Pain catastrophizing has consistently been related to a variety of negative outcomes within chronic pain conditions, but competing models exist explaining the role of catastrophizing. According to the fear-avoidance model (FAM), catastrophizing is primarily related to the appraisal of pain (i.e. "intrapersonal"), whereas the communal coping model (CCM) suggests that catastrophizing is a strategy to elicit support (i.e. "interpersonal"). In order to examine the interpersonal nature of catastrophizing, this cross-sectional study examined interpersonal problems as a predictor of pain catastrophizing in a sample of patients (n = 97) with chronic pain. Methods Self-report data was taken from patients entering a multidisciplinary, inpatient rehabilitation program. The four quadrants of the Inventory of Interpersonal Problems circumplex model (Hostile-Dominant, Hostile-Submissive, Friendly-Submissive, Friendly-Dominant) were used as predictors of pain catastrophizing in a series of separate, hierarchical regression analyses. Results After controlling for relevant confounding variables such as demographics (gender, age), pain severity, psychiatric symptoms (anxiety/depression, fatigue, insomnia), adverse life experiences and perceived social support, higher levels of Hostile-Dominant interpersonal problems predicted higher levels of pain catastrophizing (p ≤ 0.01, d = 0.56). Conclusions The results add support to the notion that pain catastrophizing may serve a communicative functioning, as predicted by the CCM, with cold, dominant and controlling behaviors as a maladaptive interpersonal strategy to elicit support. It may thus be useful to consider the broader interpersonal context of the individual, and not only the patient's appraisal of pain, when conceptualizing the role of pain catastrophizing in patients with chronic pain. Implications Future psychosocial research and treatment of chronic pain could be informed by including interpersonal theory as a useful theoretical framework, which may help shed more light on how interpersonal problems relates to pain catastrophizing.

Randomized Controlled Trial of Adding Telephone Follow-Up to an Occupational Rehabilitation Program to Increase Work Participation

Purpose Transfer from on-site rehabilitation to the participant's daily environment is considered a weak link in the rehabilitation chain. The main objective of this study is to see if adding boosted telephone follow-up directly after completing an occupational rehabilitation program effects work participation. Methods A randomized controlled study included participants with chronic pain, chronic fatigue or common mental disorders on long-term sick leave. After completing 3½ weeks of acceptance and commitment therapy based occupational rehabilitation, participants were randomized to boosted follow-up or a control group before returning to their daily environment. The intervention was delivered over 6 months by on-site RTW coordinators mainly via telephone. Primary outcome was RTW categorized as participation in competitive work ≥1 day per week on average over 8 weeks. Results There were 213 participants of mean age 42 years old. Main diagnoses of sick leave certification were mental disorders (38%) and musculoskeletal disorders (30%). One year after discharge the intervention group had 87% increased odds (OR 1.87, 95% confidence interval 1.06-3.31, p = 0.031), of (re)entry to competitive work ≥1 day per week compared with the controls, with similar positive results for sensitivity analysis of participation half time (≥2.5 days per week). The cost of boosted follow-up was 390.5 EUR per participant. Conclusion Participants receiving boosted RTW follow-up had higher (re)entry to competitive work ≥1 day per week at 1 year when compared to the control group. Adding low-cost boosted follow-up by telephone after completing an occupational rehabilitation program augmented the effect on return-to-work.

Reward responsiveness in patients with chronic pain

BACKGROUND

It is proposed that changes in reward processing in the brain are involved in the pathophysiology of pain based on experimental studies. The first aim of the present study was to investigate if reward drive and/or reward responsiveness was altered in patients with chronic pain (PCP) compared to controls matched for education, age and sex. The second aim was to investigate the relationship between reward processing and nucleus accumbens volume in PCP and controls. Nucleus accumbens is central in reward processing and its structure has been shown to be affected by chronic pain conditions in previous studies.

METHODS

Reward drive and responsiveness were assessed with the Behavioral Inhibition Scale/Behavioral Activation Scale, and nucleus accumbens volumes obtained from T1-weighted brain MRIs obtained at 3T in 19 PCP of heterogeneous aetiologies and 20 age-, sex- and education-matched healthy controls. Anhedonia was assessed with Beck's Depression Inventory II.

RESULTS

The PCP group had significantly reduced scores on the reward responsiveness, but not reward drive. There was a trend towards smaller nucleus accumbens volume in the PCP compared to control group. There was a significant positive partial correlation between reward responsiveness and nucleus accumbens volume in the PCP group adjusted for anhedonia, which was significantly different from the same relationship in the control group.

CONCLUSIONS

Reward responsiveness is reduced in chronic pain patients of heterogeneous aetiology, and this reduction was associated with nucleus accumbens volume. Reduced reward responsiveness could be a marker of chronic pain vulnerability, and may indicate reduced opioid function.

Patients with chronic pain lack somatic markers during decision-making

Patients with chronic pain have impaired cognitive functions, including decision making, as shown with the Iowa gambling task (IGT). The main aim of this study was to elucidate whether patients’ decision making is associated with a lack of the anticipatory skin conductance response (SCR). An increase in anticipatory SCR before making unfavorable choices is known to guide decisions in healthy controls during the IGT. Since several brain regions involved in decision making are reported to have altered morphology in patients with chronic pain, the second aim was to explore the associations between IGT performance and brain structure volumes. Eighteen patients with chronic pain of mixed etiology and 19 healthy controls matched in terms of age, sex, and education were investigated with a computerized IGT during the recording of SCR, heart rate, and blood pressure. The participants also underwent neuropsychological testing, and three-dimensional T1-weighted cerebral magnetic resonance images were obtained. Contrary to controls, patients did not generate anticipatory SCRs before making unfavorable choices, and they switched between decks of cards during the late phase of the IGT significantly more often, and this was still observed after adjusting for depression scores. None of the other autonomic measures differed during IGT performance in either group or between groups. In patients, IGT scores correlated positively with total cortical grey matter volume. In controls, there was no such association, but their IGT scores correlated with the anticipatory SCR. It may be speculated that the reduction in anticipatory SCRs makes the chronic pain patients rely more on cortical resources during decision making.

Concomitant medication among persistent opioid users with chronic non-malignant pain

BACKGROUND

Recent guidelines for opioid treatment of chronic non-malignant pain discourage co-medication with benzodiazepines and benzodiazepine-related hypnotics, whereas co-medication with non-opioid analgesics and co-analgesics may offer a beneficial opioid sparing effect, and is recommended. The aim of this study was to describe 1-year periodic prevalence of co-medication with benzodiazepines, benzodiazepine-related hypnotics, non-opioid analgesics, co-analgesics and antidepressants in persistent opioid users with chronic non-malignant pain.

METHODS

The study is based on data from the Norwegian Prescription Database, covering all drugs dispensed to outpatients in 2008. Concomitant medication levels were compared between users in two definitions of persistent opioid use, all Norwegian adults dispensed opioids in 2008 and the Norwegian background population.

RESULTS

Of the Norwegian adult population studied, 1.2% met the criteria of persistent opioid use based on prescription pattern and prescription level. Sixty percent of persistent opioid users were dispensed a benzodiazepine or benzodiazepine-related hypnotic in amounts indicating regular use, with 15% dispensed a high amount of both classes. Sixty-two percent of persistent opioid users were dispensed one or more non-opioid analgesics, 47% an antidepressant and 33% were dispensed an antiepileptic drug.

CONCLUSION

Approximately 60% of persistent opioid users also receive benzodiazepines or benzodiazepine-related hypnotics in amounts indicating regular use. This is in conflict with recent guidelines for the treatment of chronic non-malignant pain and may indicate that these users are at an increased risk of developing problematic opioid use.

Differential patterns of opioid use: defining persistent opioid use in a prescription database

AIM

The aim of this study was to develop definitions to identify persons with clinically different patterns of persistent opioid use based on data from prescription databases.

METHODS

The study is based on data from the Norwegian Prescription Database using all dispensed opioid prescriptions during 2005-2008. Three definitions of persistent opioid use were developed using the following patient criteria: different levels of dispensed opioid amounts, number of prescriptions and the number of quarters out of the year in which prescriptions were dispensed. The three definitions each have some typical patient characteristics attached to them. The strict definition describes a typical patient using opioids to achieve a continuous serum concentration in the therapeutic range, the intermediate definition represents a typical patient using opioids daily but not around the clock and the wide definition describes a typical patient who uses opioids most of the days. To study whether the definitions accurately represent long-term use, the patient population was followed for 3 years, and the retention rate within each definition was measured.

RESULTS

The point prevalence of persistent opioid use in Norway (4,681,134 inhabitants) as defined by the strict, intermediate and wide definitions was 0.16% (n = 7663), 0.50% (n = 23,498) and 1.08% (n = 50,791), respectively, as of 31 December 2007. At the end of the 3-year study period, the retention within any of the definitions was 83%, 84% and 68% for patients who met the criteria of the strict, intermediate and wide definitions, respectively.

CONCLUSION

In the patient populations identified by the three definitions, a high rate of retention was observed, indicating that the proposed definitions can identify patients with long-term persistent use of opioids.

Patients with problematic opioid use can be weaned from codeine without pain escalation

BACKGROUND

Brief treatments for chronic non-malignant pain patients with problematic opioid use are warranted. The aims of the present study were to investigate (1) whether it is possible to withdraw codeine use in such patients with a brief cognitive-behavioural therapy (CBT), (2) whether this could be done without pain escalation and reduction in quality of life and (3) to explore the effects of codeine reduction on neurocognitive functioning.

METHODS

Eleven patients using codeine daily corresponding to 40-100 mg morphine were included. Two specifically trained physicians treated the patients with six CBT sessions, tapering codeine gradually within 8 weeks. Codeine use, pain intensity, quality of life and neuropsychological functioning were assessed at pre-treatment to the 3-month follow-up.

RESULTS

Codeine use was significantly reduced from mean 237 mg [standard deviation (SD) 65] pre-treatment to 45 mg (SD 66) post-treatment and to 48 mg (SD 65) at follow-up without significant pain escalation or reductions in quality of life. Moreover, neuropsychological functioning improved significantly on some tests, while others remained unchanged.

CONCLUSION

The promising findings of codeine reduction in this weaning therapy programme for pain patients with problematic opioid use should be further evaluated in a larger randomized control trial comparing this brief CBT with both another brief treatment and attention placebo condition.

Prescription pattern of codeine for non-malignant pain: a pharmacoepidemiological study from the Norwegian Prescription Database

BACKGROUND

Opioid prescription for pain relief is increasing. Codeine is the dominating opioid in several European countries, with Norway being among the highest codeine users.

AIM

To determine whether codeine is primarily used for acute pain or whether there is a prescription pattern indicating problematic opioid use.

METHODS

All pharmacies in Norway are obliged to submit data electronically to the Norwegian Prescription Database at the Norwegian Institute of Public Health on all dispensed prescriptions. Because all prescriptions are identified with a unique person identifier, it is possible to identify all prescriptions to one subject. All subjects who had prescription(s) of codeine dispensed to them in 2004, 2005 or 2006 are included in the study.

RESULTS

385 190 Norwegian persons had at least one prescription of codeine dispensed to them due to non-cancer pain in 2005, corresponding to a 1-year periodic prevalence of 8.3%. 223 778 (58%) received only one prescription in 2005, 121 025 (31%) received more than one prescription but <120 defined daily doses (DDDs), 30 939 (8%) received between 120 and 365 DDDs, 7661 (2%) between 365 and 730 DDDs, while only 1787 (0.5%) exceeded the maximum recommended dose of 730 DDDs. In the latter group, co-medication with benzodiazepines (65%) and carisoprodol (45%) was prevalent.

CONCLUSION

About one in 10 adult persons in Norway were dispensed codeine in 2005. A majority (58%) received codeine only once, most likely for acute pain, whereas a small minority (0.5%) had a prescription pattern indicating problematic opioid use.

A controlled comparison between single doses of intravenous and intramuscular morphine with respect to analgesic effects and patient safety

BACKGROUND AND AIM OF INVESTIGATION: Intramuscular (IM) administration has been considered to be safer than intravenous (IV) for opioids on wards, but a comparative knowledge of patient safety and analgesic potency following a single dose of IV and IM administration is lacking. This study was carried out to compare patient safety and analgesic efficacy of a single and high dose of morphine given IM or IV for post-operative pain management.

MATERIALS AND METHODS

Thirty-eight patients with post-operative pain following hip replacement surgery were given IM or IV morphine 10 mg at a specified pain level. The study was randomized and double blinded. Time to onset of analgesic effect (11-point numeric rating scale), respiratory function (p(a)CO2, p(a)O2, and respiratory rate), level of sedation (5-point verbal rating scale), and hemodynamic function were recorded.

RESULTS

In the IV group there was a slight but significant increase in p(a)CO2 after 5, 10, and 15 min compared with the IM group (5.2 vs. 4.8, 5.4, vs. 5.0 and 5.5 vs. 5.1 kPa, respectively). The IV group had a significantly faster onset of analgesic effect than the IM group (5 vs. 20 min). Between 5 and 25 min after morphine administration, pain status in the IV group was significantly improved compared with the IM group. Patients in the IV group were slightly more sedated than the IM group 5 and 10 min after morphine.

CONCLUSION

A 10 mg bolus dose of IV morphine given to patients with moderate pain after surgery does not cause severe respiratory depression, but provides more rapid and better initial analgesia than 10 mg given IM. IV morphine even at a dose as high as 10 mg IV is well tolerated if there is a certain level of pain at its administration. The safety of IV morphine on the general ward needs to be further explored in adequately controlled studies.

Clinical pharmacology of methadone for pain

BACKGROUND

This topical review addresses methadone's pharmacology, its application in malignant and non-malignant pain conditions, practical issues related to methadone for the treatment of pain and its influence on QTc time.

METHODS

Relevant papers were identified in PubMed and EMBASE.

RESULTS

Methadone is advocated by experts as a second line opioid when first line opioids fail to provide a satisfactory balance between pain control and side effects (opioid switching). Although randomized-controlled studies are lacking, current evidence suggests that switching to methadone in this situation reduces pain intensity. However, interindividual variability in its pharmacokinetics make its application challenging and metabolism by CYP 3A4 and 2B6 implies a substantial risk of drug-drug interactions. Several ways of switching to methadone have been presented, with a gradual switch during 3 days or 'stop and go' as the dominating strategies. Episodes of torsade de pointes arrhythmia during methadone treatment have been reported in patients with other risk factors for arrhythmia, while small prospective studies have reported a small, lasting and stable increase in QTc time. The extensive use of methadone for opioid replacement in addicts has added additional patient barriers to its use for pain control.

CONCLUSION

In spite of challenges related to the variable pharmacokinetics and concerns regarding increase in QTc time, current evidence indicates that opioid switching to methadone improves pain control in a substantial proportion of patients who are candidates for opioid switching. Measures must be instituted to secure that patients receiving methadone for pain are not considered opioid addicts.

Assessment of pain

Valid and reliable assessment of pain is essential for both clinical trials and effective pain management. The nature of pain makes objective measurement impossible. Acute pain can be reliably assessed, both at rest (important for comfort) and during movement (important for function and risk of postoperative complications), with one-dimensional tools such as numeric rating scales or visual analogue scales. Both these are more powerful in detecting changes in pain intensity than a verbal categorical rating scale. In acute pain trials, assessment of baseline pain must ensure sufficient pain intensity for the trial to detect meaningful treatment effects. Chronic pain assessment and its impact on physical, emotional, and social functions require multidimensional qualitative tools and health-related quality of life instruments. Several disease- and patient-specific functional scales are useful, such as the Western Ontario and MacMaster Universities for osteoarthritis, and several neuropathic pain screening tools. The Initiative on

METHODS

Measurement, and Pain Assessment in Clinical Trials recommendations for outcome measurements of chronic pain trials are also useful for routine assessment. Cancer pain assessment is complicated by a number of other bodily and mental symptoms such as fatigue and depression, all affecting quality of life. It is noteworthy that quality of life reported by chronic pain patients can be as much affected as that of terminal cancer patients. Any assessment of pain must take into account other factors, such as cognitive impairment or dementia, and assessment tools validated in the specific patient groups being studied.

Chronic non-malignant pain patients report as poor health-related quality of life as palliative cancer patients

BACKGROUND

Patients with chronic non-malignant pain (CNMP) conditions are known to report reduced health-related quality of life (HRQoL). The objective of this exploratory study was to compare HRQoL between patients admitted to a multidisciplinary pain centre, palliative cancer (PC) patients and national norms.

METHODS

HRQoL data from 288 patients with CNMP admitted to the multidisciplinary pain centre at Trondheim University Hospital were compared with 434 patients with advanced cancer included in a trial of comprehensive palliative care in the hospital palliative medicine unit and national norms. HRQoL was assessed using the EORTC QLQ-C30. Age- and gender-adjusted norm data were calculated and compared between the two groups.

RESULTS

Scores from both groups deviated from adjusted norm data on all scales, with poorer functioning and more symptoms. Compared with PC patients, CNMP patients reported a larger deviation (worse scores) on global quality of life, cognitive functioning, pain, sleep disturbances and financial difficulties. Deviations from norm data were similar for physical, social and emotional functioning, diarrhoea, dyspnoea and fatigue. PC patients reported worse scores on role functioning, nausea/vomiting, loss of appetite and constipation.

CONCLUSION

CNMP patients admitted to multidisciplinary pain centres report significantly reduced HRQoL, in addition to severe pain. They consider their HRQoL to be as poor as HRQoL reported from dying cancer patients and substantially poorer than national norms. Factors other than the biological severity of the disease seem to be of major importance for self-reported HRQoL.

Serum and cerebrospinal fluid morphine pharmacokinetics after single doses of intravenous and intramuscular morphine after hip replacement surgery

AIM

To compare the time course of morphine and metabolite concentrations in serum and cerebrospinal fluid (CSF) after intravenous and intramuscular administration after surgery.

METHODS

This was a randomized double-blind, double-dummy study in patients who had undergone hip replacement surgery. Morphine (M, 10 mg) was administered intravenously (IV) or intramuscularly (IM). Arterial blood and CSF samples (from a spinal catheter) were drawn simultaneously at 10, 30, 60, and 120 min after administration. Morphine and metabolites [morphine-3-glucuronide (M-3-G), morphine-6-glucuronide (M-6-G), and normorphine (NM)] were determined by a validated liquid chromatography-tandem mass spectrometry method.

RESULTS

Thirty-eight patients were included: 13 men and 25 women, 20 in the IV, 18 in the IM group. Serum concentrations of M after 10 min were consistently higher after IM than IV, concentrations of M-3-G and M-6-G after IM surpassed those of IV after 45 min. NM was not found. None of the metabolites was found in CSF. CSF morphine concentrations and CSF/serum concentration ratios were consistently higher after IV compared to IM. The mean AUC(CSF)/AUC(serum) (0-120 min) concentration ratios were 0.18 and 0.09 after IV and IM, respectively.

CONCLUSIONS

The uptake of morphine to the CSF was consistently higher after IV administration than after IM already after 10 min. The higher CSF concentration may be caused by an initially higher morphine blood/CSF gradient following IV morphine injection. The pharmacokinetic findings are compatible with a more rapid and extensive initial effect of IV morphine compared with IM.

Genetic variability and clinical efficacy of morphine

The individual variability of opioid pharmacology suggests that the patients' genetic disposition influences the response to opioids. Given the complexity of morphine pharmacology, variability may be caused by several genes. We review data which shows that variability in genes coding the enzyme metabolizing morphine (UGT2B7 gene), mu-opioid receptors (OPRM gene) and blood-brain barrier (BBB) transport of morphine by multidrug resistance transporters (MDR1 gene) influences the clinical efficacy of morphine. Furthermore, variability in an enzyme degrading catecholamines (COMT gene) alters the efficacy of morphine demonstrating that genetic variability in non-opioid systems may indirectly influence the clinical efficacy from morphine. Thus, results obtained so far strongly argue that opioid efficacy is partly related to inborn properties caused by genetic variability.

The 118 A > G polymorphism in the human mu-opioid receptor gene may increase morphine requirements in patients with pain caused by malignant disease

BACKGROUND

Dispositions for genes encoding opioid receptors may explain some variability in morphine efficacy. Experimental studies show that morphine and morphine-6-glucuronide are less effective in individuals carrying variant alleles caused by the 118 A > G polymorphism in the mu-opioid receptor gene (OPRM1). The purpose of the study was to investigate whether this and other genetic polymorphisms in OPRM1 influence the efficacy of morphine in cancer pain patients.

METHODS

We screened 207 cancer pain patients on oral morphine treatment for four frequent OPRM1 gene polymorphisms. The polymorphisms were the -172 G > T polymorphism in the 5'untranslated region of exon 1, the 118 A > G polymorphism in exon 1, and the IVS2 + 31 G > A and IVS2 + 691 G > C polymorphisms, both in intron 2. Ninety-nine patients with adequately controlled pain were included in an analysis comparing morphine doses and serum concentrations of morphine and morphine metabolites in the different genotypes for the OPRM1 polymorphisms.

RESULTS

No differences related to the -172 G > T, the IVS2 + 31 G > A and the IVS2 + 691 G > C polymorphisms were observed. Patients homozygous for the variant G allele of the 118 A > G polymorphism (n = 4) needed more morphine to achieve pain control, compared to heterozygous (n = 17) and homozygous wild-type (n = 78) individuals. This difference was not explained by other factors such as duration of morphine treatment, performance status, time since diagnosis, time until death, or adverse symptoms.

CONCLUSION

Patients homozygous for the 118 G allele of the mu-opioid receptor need higher morphine doses to achieve pain control. Thus, genetic variation at the gene encoding the mu-opioid receptor contributes to variability in patients' responses to morphine.

Influences on serum concentrations of morphine, M6G and M3G during routine clinical drug monitoring: a prospective survey in 300 adult cancer patients

BACKGROUND

In order to make treatment decisions physicians should have knowledge about the relations between patient characteristics and drug disposition. Dose, route of administration, gender, age and renal function are reported to influence the serum concentrations of morphine, morphine-6-glucurnide (M6G) and morphine-3-glucuronide (M3G) during chronic treatment of cancer pain. These factors, however, are not evaluated in studies with a sample size sufficient to explore predictive factors.

METHODS

Three hundred consecutive morphine users admitted because of a malignant disease were recruited. The relations of serum concentrations of morphine, M6G and M3G to patient characteristics (gender, age, weight, renal function, liver function, dose, route of administration) were explored, and regression analysis performed to investigate whether these characteristics predicted serum concentrations obtained during routine clinical drug monitoring.

RESULTS

Morphine dose was associated with serum concentrations of morphine (r = 0.69), M6G (r = 0.76) and M3G (r = 0.76). Oral morphine resulted in higher dose-adjusted M6G and M3G serum concentrations compared with s.c. morphine. Creatinine serum concentrations correlated with serum concentrations of M6G and M3G. Dose and route of administration predicted morphine serum concentrations, while dose and renal function predicted M6G and M3G serum concentrations. Age was an additional factor predicting M3G concentrations. Dose was the only factor that explained a clinically significant part of the observed variability.

CONCLUSION

Patient characteristics predict only minor parts of the variability of morphine, M3G and M6G serum concentrations observed during routine clinical drug-monitoring in cancer patients.

Randomized, double-blind, placebo-controlled study of the effect of rectal paracetamol on morphine consumption after abdominal hysterectomy

BACKGROUND

Paracetamol is widely used for postoperative analgesia. The effect is well documented in minor and moderate extensive surgery, but the effect of paracetamol as an adjunct to opioids in major abdominal surgery is less examined.

METHODS

Seventy-eight patients scheduled for elective, benign, and abdominal hysterectomy were included in a prospective, randomized, double-blind, parallel group, placebo-controlled study to evaluate the effect of rectal paracetamol in conjunction with intravenous patient-controlled analgesia (PCA) morphine. Paracetamol 1000 mg or placebo suppositories were given four times daily during the 60-h study period. I.V. morphine was administered via a PCA pump, limited to maximum of 12 mg h-1. Morphine consumption, pain and morphine-related adverse effects were recorded. A single-point analysis was comprised of serum concentrations of paracetamol and morphine.

RESULTS

Sixty patients were evaluated: 30 in each group. A 16.6% reduction in overall-accumulated morphine consumption in the treatment group (99.6 vs. 83.3 mg) was observed (NS, P = 0.06). Mean paracetamol serum concentration was 0.03 mmol l-1 (range: 0.01-0.06 mmol l-1). None of the patients had a paracetamol concentration within the therapeutic range for antipyretic efficacy. Patients with a higher paracetamol concentration had a lower concomitant morphine (P = 0.025) and morphine-6-glucuronide (P = 0.014) concentration 2 h after paracetamol administration.

CONCLUSION

A dosage of rectal paracetamol 1000 mg four times daily is too low, as all displayed a suboptimal serum paracetamol concentration. To study the effect of rectal paracetamol after major surgery we have to increase the dose, as higher serum concentrations of paracetamol may cause lower serum concentrations of morphine.

Epidural bupivacaine with sufentanil or fentanyl during labour: a randomized, double-blind study

BACKGROUND AND OBJECTIVE

Epidural analgesia with bupivacaine plus either sufentanil or fentanyl is widely used during labour, but it is not clear which opioid is to be preferred. The study compared these opioids at equianalgesic doses in terms of analgesia, onset time and side-effects.

METHODS

Ninety females in active labour were entered into the randomized, double-blind trial. A test dose of bupivacaine was given into the epidural space. Parturients in Group S received sufentanil 8 mL as a bolus dose, followed by an infusion at a rate of 5 mL h(-1) of a mixture containing sufentanil 1 microg mL(-1) and bupivacaine 1 mg mL(-1). Patients in Group F received fentanyl 8 mL as a bolus, followed by an infusion at 5 mL h(-1) of a solution containing fentanyl 3.5 microg mL(-1) and bupivacaine 1 mg mL(-1). Additional boluses of 5 mL were of the relevant solution were given if necessary.

RESULTS

In a ratio of 1.0:3.5 (sufentanil 1 microg versus fentanyl 3.5 microg), both groups reported the same analgesia with the same onset time. The onset time to obtain 50% of the initial visual analogue score was 10 and 11 min for Groups S and F, respectively. Mean visual analogue scores in Groups S and F respectively declined from 77 and 82 before epidural blockade, to 29 and 27 during the first stage of labour, and to 69 and 59 respectively during the second stage. Overall satisfaction among parturients was high (98 and 96%), particularly during the first stage (98 and 98%), and also to a large degree during the second stage of labour (74 and 79%). Furthermore, only a few extra bolus doses were required (mean 0.9 and 1.2, Groups S and F, respectively). All the females could stand on their own, and almost all (81% Group S; 79% Group F) could walk 20 m without help. There were no serious adverse effects. Moderate side-effects occurred equally often with the possible exception of less nausea and vomiting in the fentanyl group.

CONCLUSIONS

Epidural analgesia for ambulatory parturients with bupivacaine plus either sufentanil or fentanyl (ratio 1.0:3.5) provides good analgesia with a low frequency of modest side-effects. No clinical differences were found between the opioids.

Circadian distribution of oral opioid consumption in cancer patients

Diurnal variations are reported in pain perception, potency of placebo and in the pharmacokinetics of morphine. It is not established if such diurnal variation should be reflected in the routine prescription of analgesic drugs to cancer patients. One approach for investigating this question is to study the circadian rhythm of patients' requests for analgesics. We included 40 patients with malignant disease and intolerable pain despite treatment with weak opioids. Weak opioids were stopped and the patients' pain treatment was restricted for the next 2 days to strong oral opioids (ketobemidone) given on an as-needed basis. The number and times of all ketobemidone administrations were recorded. No significant diurnal variation in use of ketobemidone was observed. A descriptive curve that interpolates between successive observations displayed only slight circadian fluctuations of opioid consumption. Thus, the data reported in this paper does not support the necessity of considering chronopharmacological factors in the routine prescription of oral opioids.

Pain intensity and side effects during titration of morphine to cancer patients using a fixed schedule dose escalation

BACKGROUND

Considerable dose variations and frequent initial side effects have been postulated during start of morphine treatment to patients with pain caused by malignant disease. However, to our knowledge, only one previous study has reported effective doses in morphine naive cancer patients and no prospective evaluation has compared symptoms before with symptoms during morphine titration.

METHODS

We recruited 40 cancer patients with uncontrolled pain despite receiving codeine or dextropropoxyphen. Baseline data were obtained for two days before start of morphine titration using a fixed scheduled escalation of immediate-release (IR) morphine. When a stable morphine dose was achieved, IR morphine was replaced with slow-release (SR) morphine in equivalent doses. Intensity of pain and side effects were assessed daily. The daily consumption of morphine, rescue analgesics and rescue antiemetics were registered.

RESULTS

The mean titration time to achieve adequate analgesia was 2.3 days (range: 1-6) using a mean daily morphine dose of 97 mg (range: 60-180). Nausea was unaltered after start with morphine but an increased incidence of vomiting occurred (premorphine period 5%, IR morphine period 29%). Transient sedation delayed dose increment in 9 of the 40 patients but mean sedation scores were unaltered. Constipation scores increased while other side effect scores were unaltered. Eighty-two percent of the patients were satisfied or very satisfied with the pain treatment during introduction of morphine.

CONCLUSION

In cancer patients with uncontrolled pain on weak opioids, successful titration of morphine is achieved fast, with a three-fold morphine dose variation and with little increase in side effects.

Effects on cancer patients' health-related quality of life after the start of morphine therapy

To investigate the effects of morphine on cancer patients' health-related quality of life (HRQL), we prospectively studied 40 cancer patients with moderate or severe pain despite treatment with "weak" opioids. The patients were titrated to pain relief using immediate-release (IR) morphine and then switched to slow-release (SR) morphine in the same daily dosages. HRQL was measured by the European Organization for Research and Treatment of Cancer core quality-of-life questionnaire (EORTC QLQ-C30) before the start of morphine (baseline), after stabilization with IR-morphine, and 3 days after start of SR-morphine. The mean titrated daily morphine dosage was 97 mg (range, 60-180). The EORTC QLQ-C30 global health score increased after IR morphine titration (baseline score 40, IR morphine period score 49), but a significant difference from baseline did not persist during the SR morphine period (score 44). The other functional HRQL scores showed no significant fluctuations. After start of IR morphine, two of the HRQL symptom scores increased, nausea/vomiting and constipation, but these changes also did not persist during the SR morphine period. Intensity of pain was associated with a lower level of function and higher intensity of symptoms, but only with relatively small (not higher than 0.44) correlation coefficients. Compared to normative data from the general population, physical function, role function, social function, and global health were impaired in the study patients. The patients also suffered more fatigue, pain, nausea/vomiting, appetite loss, and constipation. In conclusion, in cancer patients with reduced HRQL, the start of morphine therapy had no major influence on aspects of HRQL other than pain.

Start of oral morphine to cancer patients: effective serum morphine concentrations and contribution from morphine-6-glucuronide to the analgesia produced by morphine

OBJECTIVE

To investigate the serum concentrations of morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) and the relationships between serum concentrations and clinical effects associated with start of morphine treatment in cancer patients.

METHODS

Forty patients with malignant disease and intolerable pain on weak opioids (codeine/dextropropoxyphen) were included. After a wash-out period, titration with immediate-release (IR) morphine was started. When a stable dose was achieved, the morphine treatment was changed to slow-release (SR) morphine in equivalent daily dosages. Clinical data and serum concentrations of morphine, M3G and M6G were obtained at the end of the IR and SR morphine treatment periods.

RESULTS

The mean trough serum morphine concentration associated with pain relief was 66 nmol/l. The corresponding mean concentrations of M6G and M3G were 257 nmol/l and 1943 nmol/l, respectively. Morphine serum trough concentrations showed a 33-fold variation. Seventy percent of the variation was predicted in a model including age, daily morphine dose and M6G/morphine ratio as independent variables. No associations were observed between side effects and serum concentrations of morphine and its metabolites.

CONCLUSION

In this study, a mean serum trough morphine concentration of 66 nmol/l was associated with satisfactory pain relief when disease progression required an increase in intensity of pain therapy from step II to step III in the World Health Organization pain ladder. An increased ratio of M6G to morphine serum concentrations predicted lower effective serum morphine concentrations at the time of satisfactory pain relief. This observation supports that M6G contributes to the pain control produced by oral morphine in patients with pain caused by malignant disease.

Enhanced responsiveness of the myocardial beta-adrenoceptor-adenylate cyclase system in the perfused rat heart (I)

Crude myocardial sarcolemmal membrane fractions were prepared from rat hearts subjected to total global ischemia with and without normoxic reperfusion, or global anoxic (N2) perfusion with and without normoxic reperfusion. The direct effects on beta-adrenoceptor number, G-protein levels and stimulation of the adenylate cyclase (AC) complex were assessed. In terms of AC activation, ischemia led to a marked increase (4-fold) in sensitivity to terbutaline (beta2-agonist) and phorbol ester (tetradecanoyl phorbol acetate = TPA) stimulation, whereas the dobutamine (beta1) responsiveness and Gpp(NH)p activation through G(s)alpha/G(i2)alpha remained unaltered. However, forskolin-elicited holoenzyme activity fell markedly during normoxic reperfusion. Ischemia did not change the beta1-adrenoceptor number, while beta2-receptor population increased by approximately 45%. Western blots of myocardial G(s)A and G(i2)alpha contents revealed that ischemia selectively diminished G(i2)alpha levels only by some 50-70%. Contrastingly, anoxia selectively increased the AC sensitivity (2-fold) to beta1-adrenergic stimulation. As subsequent to ischemia, anoxia also increased the sensitivity to TPA stimulation, however, only 2-fold. Gpp(NH)p activation was unchanged, while forskolin-enhanced activity gradually declined, also during ensuing normoxic reperfusion. Anoxia brought about a 75% enhancement in beta1-receptor number, while beta2-receptors remained unaffected. However, altered receptor number normalized on termination of normoxic reperfusion. Finally, anoxia led to a 50-60% decimation of myocardial G(i2)alpha levels, while G(s)alpha was only marginally reduced. Despite the fact that the ischemia and anoxia effectuated a similar deterioration of physiological heart parameters, myocardial contents of energy rich phosphate moieties and loss of G(i2)alpha, ischemia rendered the most profound increase in responsiveness of the sarcolemmal AC system.

[Self-evaluation of knowledge and competence with regard to the treatment of pain]

In a survey completed at our hospital, 519 doctors and nurses were asked to evaluate their own knowledge and competence with regard to the treatment of various types of pain, including non-pharmacologic treatment methods. A total of 473 responded to the questionnaire. In the study, cancer-related pain and pain from causes other than cancer were assessed in separate population groups. Of the doctors, 58% evaluated their knowledge of nociceptive pain as very good or fairly good. The corresponding findings for neuropathic pain were 31%, for psychological pain 27%, for social pain 25% and for spiritual and existential aspects of pain 22%. The nurses scored lower than the doctors on knowledge and competence in relation to nociceptive and neuropathic pain (32% and 18% respectively), and higher on treatment of the psychological and social aspects of pain (44% and 36% respectively). Many of the doctors and nurses evaluated their knowledge as fairly poor or very poor with regard to nonpharmacologic treatment methods. In both professions 80% answered that depression was seen fairly often or very often among these patients.

Postoperative epidural infusion of morphine and bupivacaine is safe on surgical wards. Organisation of the treatment, effects and side-effects in 2000 consecutive patients

BACKGROUND

There was an obvious need to improve the quality and safety of our postoperative pain treatment and to introduce an improved routine service on surgical wards.

METHODS

It was decided to use postoperative epidural infusion of morphine 0.04 mg/ml and bupivacaine 2.5 mg/ml (0.25%) 4-8 ml/h as pain relief after major surgery. An education programme was run emphasising the benefits, side-effects and the importance of regular monitoring of pain intensity, vital functions (respiratory rate, blood pressure, heart rate), motor function of the legs and the need for additional drugs in order to detect side-effects as well as lack of adequate analgesic effect. A detailed observation sheet was used collecting information every 2 h throughout the epidural treatment period in order to secure monitoring and adjustment of the treatment. Close contact was maintained with the wards.

RESULTS

We present a detailed analysis of our first 2000 postoperative patients, mainly after orthopaedic (46.1%), gastrointestinal (32.0%), urologic (8.7%) and vascular (8.5%) surgery. Duration of the treatment was less than 24 h in 41.4% and more than 48 h in 29.7%. Pain relief was adequate in most patients, best after vascular surgery in the lower extremities (mean VAS 0.15/10.0 (95% confidence interval 0.09-0.23)) and less after gastrointestinal (mean VAS 0.49/10 (0.43-0.54)) and thoracic surgery (mean VAS 0.59/10 (0.38-0.81)). The infusion was stopped due to respiratory depression in 3 patients (0.15%). Four (0.2%) had systolic blood pressure < 80 mmHg and had to be treated with vasopressors. A total of 56 (2.8%) patients were considered to be problem patients due to excessive sedation (0.4%), hypotension (0.7%), respiratory depression (1.6%) or lower extremity paralysis (0.05%). All patients had urinary catheter until 6 h after termination of the epidural treatment. One patient had the epidural catheter accidentally placed subarachnoidally and experienced severe respiratory depression. No permanent sequelae were recorded in the postoperative patients, but 2 traumatised patients developed epidural abscesses after 3 weeks of treatment, which resulted in lower extremity paralysis. Late response to the warning signs might have contributed to the irreversible paraplegia.

CONCLUSION

Our experience with this postoperative epidural analgesia regime is favourable. It has been easy to administer and monitor. Pain relief was excellent, side-effects were few and picked up by the established routines followed by the ward staff except in the 2 trauma patients who developed epidural abscesses. The staff on the surgical wards were motivated for this kind of work. Education and strict surveillance routines are mandatory in order to secure prompt action when warning signs develops (e.g. lower limb paralysis).

Personality profile among symptomatic and recovered patients with neck sprain injury, measured by MCMI-I acutely and 6 months after car accidents

The relationships between personality and psychiatric symptoms and long-lasting physical symptoms were assessed in 88 neck sprain patients injured in car accidents. The Millon Clinical Multiaxial Inventory (MCMI-I) was completed at time of occurrence (intake) and 6 months after the injury. The neck sprain patients were divided into three subgroups according to symptoms 6 months after the accident. In addition, the total neck sprain group was compared with three other subject groups. The results indicated that the three neck sprain subgroups did not differ on the MCMI-I neither at intake nor 6 months later. The total neck sprain patients group was significantly different from patients with major depression on all scales of the MCMI-I, but not significantly different compared to patients with localized musculoskeletal pain. Compared to a group of health personnel, there were only a few significant differences. The study does not support the view that premorbid personality traits can predict outcome for neck sprain patients.

Four years' treatment with ketamine and a trial of dextromethorphan in a patient with severe post-herpetic neuralgia

N-methyl-D-aspartate (NMDA) receptors are involved in the development of neuropathic pain. Ketamine, a non-competitive NMDA receptor antagonist, has in several case reports given pain relief but efficacy in dosages tolerated in long-term ketamine treatment is unknown. Another substance with an antagonist action at NMDA receptors and which is approved for peroral administration is dextromethorphan. In a randomized study dextromethorphan was no better than placebo for neuropathic pain but this does not exclude efficacy in selected patients. We report a patient with severe post-herpetic pain resistant to conventional pain treatment which was treated with ketamine for 4 years with good pain relief. The practical application of long-term treatment in different administration forms of ketamine is described. The patient also responded with pain relief in a double-blind trial with oral dextromethorphan.

[Patients with cancer-related pain and other chronic pain. Priorities and assessment]

In a survey completed at our hospital, 519 doctors and nurses were asked how pain treatment was estimated whether it received priority, and to what degree patients' pain syndromes were assessed. A total of 473 responded to the questionnaire. In the study cancer-related pain and pain from causes other than cancer were assessed in separate population groups. The responders considered that the staff gave higher priority to patients with cancer-related pain, than to patients with other pain. There was a discrepancy between the physicians' and the nurses' answers to the question whether optimal pain relief was obtained. In the cancer pain group, 94% of the physicians and 78% of the nurses assumed that optimal pain relief was obtained fairly often or very often. The corresponding figures in the non-cancer pain group were 53% for the physicians and 35% for the nurses. Only 46% assumed that a planned pain assessment was done as a routine. Physicians and nurses alike experienced great inadequacy in their work with patients in pain. This was expressed more clearly in connection with pain not caused by cancer.

Magnesium and reperfusion of ischemic rat heart as assessed by 31P-NMR

Isolated rat heart perfusion and high-resolution phosphate-31 nuclear magnetic resonance (31P-NMR) spectroscopy were used to elucidate the effects of Mg during reperfusion of the ischemic myocardium. After an ischemic period of 9 min, the hearts were reperfused with 0, 0.6, or 2.4 mM Mg during the entire 24-min reperfusion period or with 15 mM Mg during the first 12 min before returning to the physiological concentration of 0.6 mM during the last 12 min. Free intracellular Mg calculated by 31P-NMR rose during ischemia and fell gradually during reperfusion. The two groups reperfused with 15 mM Mg exhibited a significantly enhanced rate of recovery of adenosine triphosphate, creatine phosphate, intracellular pH, and coronary flow rate than the three other groups. Myocardial potassium was significantly higher, and inorganic phosphate was significantly lower at the end of the reperfusion period in these groups. The hearts reperfused with 0 mM Mg presented a significantly higher frequency of ventricular fibrillation (VF) than the other groups. It is concluded that reperfusion with high Mg improves the postischemic recovery of metabolism and function in the rat heart, whereas a Mg-free reperfusion solution increases the frequency of VF.

Direct effects of furosemide and amiloride on the perfused and ischaemic rat heart

The present study was undertaken in order to assess direct effects of furosemide and furosemide plus amiloride upon the perfused and ischaemic isolated rat heart. Furosemide in concentrations ranging between 4-400 mg/l in the perfusate increased coronary flow in a concentration dependent manner. There was no evidence for a negative inotropic effect of furosemide. However, very high doses of furosemide (400 mg/l) decreased the post-ischaemic values of left ventricular developed pressure, coronary flow rate, adenosine triphosphate, creatine phosphate and potassium, and increased the myocardial content of calcium and sodium. Furosemide 4 mg/l and 40 mg/l had no effect on post-ischaemic parameters compared to the control group except that furosemide 40 mg/l increased the recovery of coronary flow. Although amiloride 13.3 mg/l alone did not affect post-ischaemic recovery, the addition of this dose to furosemide 400 mg/l improved the post-ischaemic recovery of left ventricular developed pressure, coronary flow rate and adenosine triphosphate. The myocardial content of magnesium and potassium was higher indicating protection of amiloride by its magnesium- and potassium-sparing properties opposing ischaemic losses aggravated by the exposure to furosemide.

Effects of magnesium, ouabain and bumetanide on 86rubidium uptake in a human atrial cell line

1. The effects of extracellular magnesium concentrations (0, 0.6, 1.2 mM) on 86Rb (used as an analogue of potassium) uptake were investigated in the Girardi human atrial cell line in the presence and absence of drugs. 2. Increasing extracellular magnesium resulted in significantly higher 86Rb uptake. Compared to uptake in 0.6 mM (the physiological extracellular magnesium concentration), uptake of 86Rb was significantly higher in the 1.2 mM magnesium medium and significantly lower in the magnesium-free medium. 3. Ouabain (10(-3)M) and bumetanide (10(-4)M) were added to inhibit, respectively, the Na-K-ATPase and the Na-K-Cl co-transport system in the media containing the three magnesium concentrations. The ouabain-sensitive, bumetanide-sensitive and residual transport were found to be 58%, 29% and 13% of the total uptake in the medium containing 0.6 mM magnesium. 4. The ouabain-sensitive 86Rb uptake was inhibited significantly by reducing the magnesium concentrations to zero whereas the bumetanide-sensitive and residual uptake were not significantly affected by different magnesium concentrations. 5. At three different ouabain concentrations (10(-7) M, 10(-5) M, 10(-3) M) studied there was significantly greater uptake of 86Rb in 1.2 mM magnesium compared to uptake in 0 mM magnesium. 6. The present findings indicate that extracellular magnesium is important for 86Rb (potassium) transport in cardiac cells, and suggest that the main effect is on the Na-K-ATPase component of transport.

Prolonged diuretic administration and myocardial tolerance to ischaemia

Hearts from rats, which received high doses of furosemide alone or the same doses of furosemide plus amiloride in a diet with low magnesium content for 4 weeks, were isolated and perfused in the Langendorff mode. After 15 min. of normoxic control perfusion no differences were found between the two groups of hearts with respect to cardiac physiology. After 20 min. of subtotal, global ischaemia and 15 min. of reperfusion the furosemide plus amiloride hearts showed a significantly higher recovery of function (judged by pressure rate product and coronary flow rate) than furosemide hearts. However, the myocardial content of adenosine triphosphate, creatine phosphate, and electrolytes at the end of the experiment exhibited no difference between the two groups. In separate experiments it was found that the addition of amiloride to the furosemide regimen significantly raised and almost normalized the values of plasma magnesium and potassium. Myocardial calcium was lower, whereas the magnesium and potassium content in the hearts was not different from the furosemide group. It is concluded that the administration of amiloride to rats provided high doses of furosemide and marginal magnesium supplies afforded some protection upon the ischaemic heart.

Acquired magnesium deficiency and myocardial tolerance to ischemia

Isolated hearts from rats subjected to high and low dietary Mg for 4 weeks were perfused with buffers containing 0.8 and 0.3 mM Mg, these values reflecting the plasma Mg concentrations on the two intakes. After a 20 min period of subtotal, global ischemia the recovery values of cardiac function were significantly lower in hearts from Mg-depleted rats perfused with 0.3 mM Mg, whereas the control values of cardiac function of the two groups were nearly identical before the ischemic episode. An additional group of hearts from Mg depleted rats perfused with 0.8 mM Mg did not present higher values of post-ischemic cardiac function compared to those perfused with 0.3 mM Mg. Rats fed a low dietary Mg had lower concentrations of Mg in plasma, bone and skeletal muscle, but not in the heart. The only myocardial electrolyte difference was a higher Na in the low dietary Mg group. It is concluded that an acquired extracellular Mg deficiency may reduce the myocardial tolerance to ischemia. The rapid restoration to high extracellular Mg in a prolonged Mg deficiency state did not improve the myocardial tolerance to an immediate ischemic episode.

Acute extracellular magnesium deficiency and myocardial tolerance to ischemia

The present study was undertaken in order to assess the effects of an acute and purely extracellular depletion of Mg during subtotal global ischemia and/or during post-ischemic reperfusion in the isolated rat heart. Mg depletion during reperfusion only or during ischemia plus reperfusion induced a significant reduction in post-ischemic recovery of cardiac function. Mg depletion during ischemia alone induced only a minor reduction in inotropy and coronary flow. Myocardial ATP at the end of the experiment was lowered in the groups of hearts deprived of Mg during ischemia plus reperfusion or during reperfusion only. A secondary finding was the demonstration of positive chronotropic and negative inotropic effects of the removal of extracellular Mg in non-ischemic hearts. It is concluded that, in a minor to moderate ischemic injury as in the present study, acute removal of extracellular Mg may lead to impairment of post-ischemic cardiac function and metabolism.

Tissue electrolyte changes induced by high doses of diuretics in rats

High doses of furosemide administered orally to growing rats for 4 weeks induced a pronounced fall in the concentration of magnesium and potassium in plasma, of magnesium in bone and potassium in skeletal muscle, but did not cause any reduction of these ions in the myocardium. The only electrolyte change in the heart of furosemide exposed rats was a higher calcium concentration than in rats of the control group. The addition of amiloride to furosemide in the ratio 1:16 mg corrected and partly overcorrected for the losses of magnesium and potassium in plasma and skeletal muscle. It is concluded that long term amiloride administration prevented magnesium and potassium losses induced by furosemide and that the myocardium was relatively resistant to furosemide induced magnesium and potassium loss.

Tracheal tube cuff pressures. The effects of different gas mixtures

Changes in cuff pressure and volume of tracheal tubes were studied in 60 patients undergoing lower abdominal surgery under general anaesthesia with nitrous oxide and oxygen as the anaesthetic gas mixture. The cuffs were inflated with either anaesthetic gas mixture or air. Three different brands of tubes were used. The pressure in the air filled cuffs increased steadily throughout the procedure and reached level high enough to impede microcirculation in the tracheal mucosa within one hour. We conclude that filling the cuff with anaesthetic gas mixture is a simple and reliable way to achieve stable cuff pressure during anaesthesia.