GLP-1 Restores Altered Insulin and Glucagon Secretion in Posttransplantation Diabetes

OBJECTIVE

Development of posttransplantation diabetes (PTDM) is characterized by reduced insulin secretion and sensitivity. We aimed to investigate whether hyperglucagonemia could play a role in PTDM and to examine the insulinotropic and glucagonostatic effects of the incretin hormone glucagon-like peptide 1 (GLP-1) during fasting and hyperglycemic conditions, respectively.

RESEARCH DESIGN AND METHODS

Renal transplant recipients with (n = 12) and without (n = 12) PTDM underwent two separate experimental days with 3-h intravenous infusions of GLP-1 (0.8 pmol/kg/min) and saline, respectively. After 1 h of infusion, a 2-h hyperglycemic clamp (fasting plasma glucose + 5 mmol/L) was established. Five grams of arginine was given as an intravenous bolus 10 min before termination of the clamp.

RESULTS

Fasting concentrations of glucagon (P = 0.92) and insulin (P = 0.23) were similar between the groups. In PTDM patients, glucose-induced glucagon suppression was significantly less pronounced (maximal suppression from baseline: 43 ± 12 vs. 65 ± 12%, P < 0.001), while first- and second-phase insulin secretion were significantly lower. The PTDM group also exhibited a significantly lower insulin response to arginine (P = 0.01) but similar glucagon and proinsulin responses compared with control subjects. In the preclamp phase, GLP-1 lowered fasting plasma glucose to the same extent in both groups but reduced glucagon only in PTDM patients. During hyperglycemic clamp, GLP-1 reduced glucagon concentrations and increased first- and second-phase insulin secretion in both groups.

CONCLUSIONS

PTDM is characterized by reduced glucose-induced insulin secretion and attenuated glucagon suppression during a hyperglycemic clamp. Similar to the case in type 2 diabetes, GLP-1 infusion seems to improve (insulin) or even normalize (glucagon) these pathophysiological defects.

Characteristics of methadone-related fatalities in Norway

There are currently over 7000 patients enrolled in opioid maintenance treatment (OMT) programs in Norway. A rise in methadone-related deaths proportional to increasing methadone sales over the period 2000-2006 has been observed, but the causative factors for these fatalities have been elusive. In the present study, individual characteristics, methadone concentrations and additional toxicological findings were analyzed. Methadone intoxication deaths (n = 264) were divided into 3 groups according to toxicological findings in whole blood: group 1 - methadone detected alone, or together with one additional drug at low or therapeutic levels, or a low concentration of ethanol (<1 g/L) (n = 21); group 2 - multiple additional drugs/substances detected below lethal levels (n = 175); group 3 - one or more additional drugs/substances detected at lethal levels, or ethanol >3 g/L (n = 55). Methadone blood concentrations in decedents who had been enrolled in OMT were higher than for decedents not in treatment, in all groups. Blood methadone concentrations around 1 mg/L were present in fatal multi-drug intoxications in OMT patients. Results suggest that some patients may be at risk of dying when combining therapeutic concentrations of methadone with other psychoactive substances. Somatic disease was a common finding among deceased OMT patients. Concentrations in methadone users not enrolled in OMT were predominantly between 0.3 and 0.4 mg/L and were not related to the presence of other drugs. However, methadone concentrations below 0.1 mg/L may be associated with intoxication following methadone use, both alone and in combination with other drugs. Younger male users (mean age 34 years) seemed to have a higher susceptibility to methadone intoxication.

Methadone-related deaths in Norway

INTRODUCTION

The use of methadone in opioid maintenance treatment (OMT) is potentially associated with a number of adverse effects and the risk of fatal toxicity. Increased methadone availability may lead to an increase in methadone-related deaths. We have investigated methadone-related deaths in Norway over the period 2000-2006.

MATERIALS AND METHODS

Methadone-positive samples over the period 2000-2006 were identified from forensic toxicological investigations, and demographic and toxicological data were retrieved. The cases were cross-linked with the Norwegian Cause of Death Registry and regional OMT registers.

RESULTS

A total of 312 individuals had died after taking methadone over the period 2000-2006, predominantly men with a mean age of 36. In 85% of cases (n=264), the deceased had died of a methadone-related intoxication, most often in combination with other drugs, including benzodiazepines, cannabis and other opioids. Only 22% of the deceased had been in OMT at the time of death. A larger proportion of OMT patients had died of causes other than intoxications compared to those not in OMT (30% vs. 8%, respectively), most commonly related to disease.

CONCLUSIONS

One methadone-related death occurred, on average, every week over the time period investigated. Only 22% of the deceased were registered in opioid maintenance treatment (OMT) programs. The findings underline the need to control diversion of medication from OMT programs.

Frequency and irregularity of heart rate in drivers suspected of driving under the influence of cannabis

BACKGROUND

Delta 9-tetrahydrocannabinol (THC) is the major active component of cannabis. Cardiovascular effects of THC have previously been reported: tachycardia after intake, but also bradycardia at higher doses. The purpose of this study was, firstly, to investigate the frequency and irregularity of heart rate in a group of cannabis users in their natural surroundings. We also compared THC-positive drivers with a regular pulse with THC-positive drivers with an irregular pulse.

METHODS

The division of Forensic Toxicology and Drug Abuse (DFTDA) at the Norwegian Institute of Public Heath analyzes blood samples from all drivers suspected of driving under the influence of drugs. We studied pulse rate and regularity in 502 THC-positive drivers who tested negative for other substances. As a control group, we randomly selected 125 drug-negative cases from the database of the DFTDA; no alcohol, narcotics, or medicinal drugs of abuse were detected.

RESULTS

The Delta9-THC-positive drivers had a higher mean pulse rate than the control group [82.8 beats/min (SD 16.3) versus 75.6 beats/min (SD 9.2)] and more cases with tachycardia were detected in the Delta9-THC-positive group (19.4% versus 1.6%). There was only one driver with an irregular heart beat in the control group, while there were nine among the Delta9-THC-positive drivers. The drivers with an irregular pulse were over-represented amongst those with the lowest blood Delta9-THC concentrations.

CONCLUSION

This report represents a large study of subjects in a real-life situation and includes observations on pulse frequency, regularity, and blood Delta9-THC concentration. A substantial fraction of Delta9-THC-positive drivers had tachycardia, but there was no correlation between blood Delta9-THC concentration and pulse rate in the present study. We had no further diagnostic information on the cause of the pulse irregularities, but our results indicate that occasional users of cannabis tend to have irregular heart rates at low THC concentrations and at low pulse rates.

Drug screening of hair by liquid chromatography-tandem mass spectrometry

Hair has become an important matrix for drug analysis, complementary to blood and urine as a matrix. A prolonged detection window makes hair analysis suitable for the detection of exposure to illegal and medicinal drugs for periods up to 12 months. In the present study, a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for drug screening in hair was developed and validated. To 20 mg of hair, 0.45 mL of acetonitrile/25 mM formic acid (5:95 v/v) and 50 microL of deuterated internal standards were added, and the sample was incubated in a water bath at 37 degrees C for 18 h. LC separation was achieved with a Zorbax SB-Phenyl column (2.1 x 100 mm, 3.5-microm particle). Mass detection was performed by positive ion mode electrospray LC-MS-MS and included the following drugs/metabolites: nicotine, cotinine, morphine, 6-monoacetylmorphine, codeine, amphetamine, methamphetamine, 3,4-methylenedioxymeth-amphetamine, cocaine, benzoylecgonine, 7-aminonitrazepam, 7-aminoclonazepam, 7-aminoflunitrazepam, oxazepam, diazepam, alprazolam, zopiclone, zolpidem, carisoprodol, meprobamate, buprenorphine, and methadone. Within- and between-assay relative standard deviations varied from 2.0% to 12% and 2.7% to 15%, respectively. The accuracies were in the range of -24% to 16%, and recoveries ranged from 25% to 100%. The LC-MS-MS method proved to be simple and robust for the determination of drugs in hair. It has been used for authentic samples in our laboratory in the past year.

[Anaesthetics and breast feeding]

Many women undergo anaesthetic procedures related to childbirth or during the period of lactation. Most anaesthetic drugs are lipophilic and are thus excreted into breast milk. This article summarises available knowledge regarding anaesthetics, their excretion into breast milk and possible effects on the suckling infant. The consequences of such an exposure are discussed in terms of whether breast-feeding should be allowed or not after anaesthetic procedures.

Blood alcohol concentrations in apprehended drivers of cars and boats suspected to be impaired by the police

OBJECTIVE

According to the Norwegian Road Traffic Act, car drivers are not allowed to operate a vehicle with a blood alcohol concentration (BAC) above 0.2 g/kg. Depending on the size of the boat or ship, boat drivers/captains/first mates are not allowed to conduct the boat with a BAC above 0.8 g/kg when driving small boats (length less than 15 m) and above 1.5 g/kg when running larger vessels/ships. The new Sea Act of June 2005 states that captains/first mates cannot conduct a ship if he/she has a BAC above 0.2 g/kg. Our aim was to determine the current median BAC in a large population of car and boat drivers in Norway. Our other aim was to study if median BAC was higher in boat drivers than in car drivers who were suspected by the police to be impaired. Furthermore, we wanted to investigate if the BAC levels were differently distributed by gender or age within and between these two groups.

METHODS

The Norwegian Institute of Public Health analyzes blood samples from all car/boat drivers suspected of driving under the influence of alcohol and non-alcoholic drugs. In the present study, samples submitted between 01.05 and 01.09 in 2002-2004 were included. Drivers, who in addition tested positive for drugs or abuse substances other than ethanol were excluded.

RESULTS

There were 321 boat drivers and 3,061 car drivers who were suspected to be under the influence of ethanol only. The median BAC in boat drivers (1.76 g/kg [range 0.02-3.54]) was significantly higher compared to that in car drivers (1.54 g/kg [range 0.00-4.27]). In the car driver group, the mean BAC did not differ significantly between men and women. The median level of BAC was significantly higher in men than in women in the boat driver group (1.77 g/kg with CI 1.69-1.85 vs. 1.27 g/kg with CI 0.78-1.76).

CONCLUSIONS

Alcohol impairment of car drivers is known to be considered the most important contributing cause of car crash injuries. Driving a boat may demand the same degree of performance skills as driving a car. The median BAC in apprehended boat drivers was considerably high in the present study. The median BAC was also high in car drivers despite strict legislation. The population of drivers of cars in our study, however, is from previous studies known to contain a large proportion of heavy drinkers. Less is known about the drinking habits in boat drivers, and caution is needed in generalizing from our results. However, our results indicate the possible need for stricter legislation and more frequent police control that will hopefully prevent serious accidents caused by ethanol drinking at sea.

[Determination of buprenorphine in urine]

Buprenorphine is one of the drugs used for treatment of opioid-dependent patients enrolled in rehabilitation programs in Norway. Buprenorphine is metabolized in the liver by cytochrome P450 to the active metabolite norbuprenorphine, and further to buprenorphine-glucuronide and norbuprenorphine-glucuronide. The Division of Forensic Toxicology and Drug Abuse at the Norwegian Institute of Public Health has during the past 5 years received an increasing number of urine samples for buprenorphine analysis. All urine samples with question of buprenorphine have since August 2005 been analysed with a new method, which analyses the glucuronides of buprenorphine and norbuprenorphine in urine. This method is fast and simple and saves time and resources in our routine laboratory.

Relationship between methadone and EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) in urine samples from Norwegian prisons

BACKGROUND

Methadone maintenance treatment is a widely used therapy in the rehabilitation of opioid addiction the world over. Methadone is metabolised in the body to a number of inactive metabolites, but primarily to 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). The Division of Forensic Toxicology and Drug Abuse (DFTDA) of the Norwegian Institute of Public Health carries out drug analysis of urine samples from inmates of prisons throughout Norway. Methadone and EDDP in the urine are also tested for upon request. The results are stored in a secure database at the DFTDA.

OBJECTIVES

The aims of the present study were (1) to observe variations in methadone and EDDP concentrations in urine in relation to urine pH in a large set of urine samples obtained from prison inmates and (2) to analyse samples testing methadone-positive/EDDP-negative and investigate whether such results could occur naturally, without sample tampering.

METHODS

All urine samples that tested positive for methadone over the period 2004-2005 were collected from the DFTDA database, and the relation between methadone and EDDP excretion in urine, and urinary pH was determined. Samples that tested positive for methadone but negative for EDDP were picked out and studied individually.

RESULTS

A total of 1539 urine samples (cases) had tested positive for methadone in our database for the period 2004-2005. There was a strong correlation between the concentration of methadone in urine and urine pH in these samples, with higher concentrations of methadone present at lower pH levels. Cases that tested positive for methadone but negative for EDDP were rare - a total of five (0.3% of all cases tested). These cases were studied in more detail.

CONCLUSION

Methadone excretion in urine is dependent on urinary pH. Methadone-positive/EDDP-negative results may suggest sample tampering in some, but not all, cases.

Rapid Quantification of Buprenorphine-Glucuronide and Norbuprenorphine-Glucuronide in Human Urine by LC-MS-MS

A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed and validated for the determination of buprenorphine-glucuronide (BUP-G) and norbuprenorphine-glucuronide (NBUP-G) in human urine. The method included a dilution step followed by filtration through a Mini-Uniprep Filter and direct injection onto the LC column. The analytes were quantified in multiple reactions monitoring mode using one transition ion. Norbuprenorpine-d(3) (NBUP-d(3)) was used as the internal standard. The concentration ranges were 6-161 ng/mL for BUP-G and 12-295 ng/mL for NBUP-G. Recoveries determined after filtration for the analytes were 75%. The between-day precision of the method was in the range of 4.8-11%. The limits of quantification were found to be 4.6 ng/mL for BUP-G and 11.8 ng/mL for NBUP-G. Approximately 1000 samples from law enforcement, prison inmates, probation services, and hospitals were analyzed by the presented method. The ratios of drug glucuronides versus creatinine were calculated for a selection of samples (n = 151), where there was information on treatment with buprenorphine between 16 and 20 mg/day. The majority (86%) of the samples had a ratio of BUP-G/creatinine below 570 microg/g, and 76% of the samples had NBUP-G/creatinine lower than 1060 microg/g. The LC-MS-MS method proved to be robust and specific for the determination of BUP-G and NBUP-G in urine.

[Khat--a new drug of abuse in Norway]

BACKGROUND

The stimulating drug, Khat, is a drug of abuse that has become known in Norway due to increased immigration from East-Africa, especially Somalia.

METHOD

Review of recent literature.

RESULTS

Khat is present in leaves from the tree Catha Edulis and is taken by chewing the leaves. The biologically active compounds are cathinone, cathine and norephedrine. Analysis of cathinone in urine can be performed at the Norwegian Institute of Public Health. The effects of khat are similar to, but weaker than those of amphetamine. Khat stimulates the central nervous system causing increased alertness, euphoria and occasionally psychosis, and increases activity in the peripheral sympathetic nervous system leading to palpitations, increased blood pressure, large pupils and red eyes. Tannin in khat damages teeth and causes constipation. With increased use of khat in the society it is important for the clinician to have some knowledge of the effects of khat.

[Cannabis and cannabinoids as drugs]

BACKGROUND

Cannabis has been used throughout human history. Delta (9)-tetrahydrocannabinol (THC) is the primary psychoactive component of cannabis. THC metabolises to 11-OH-THC and further to THC-acid, which is an inactive metabolite. We present an overview of the pharmacokinetics and pharmacodynamics of cannabinoids.

MATERIAL AND METHOD

This article is based on selected literature with an emphasis on the pharmacodynamics of cannabinoids.

RESULTS AND INTERPRETATION

It has been demonstrated that mammalian tissues express cannabinoid receptors (CB1, CB2 and most probably CB3) and endogenous ligands for these. Knowledge of these receptors has lead to the development of components that stimulate (CB-agonists) or block their function (CB-antagonists). This opens up for the study of any potential therapeutic effects of cannabinoids. Research on a possible therapeutic potential of cannabinoids should however not overshadow the well-documented negative effects of cannabis; i.e. impaired cognitive functions, intoxication and an increased risk for development of psychosis and psychotic symptoms.

[Routines upon suspicion of driving under influence]

Norway was the first country in the world to introduce an act, in 1936, that prohibits driving with a blood alcohol concentration (BAC) above 0.5 g/kg. This Norwegian Road Traffic Act was expanded in 1959 to include illegal drugs and other medicinal psychoactive drugs. Upon suspicion of drugged driving, a clinical test for impairment (CTI) is performed and blood samples are taken. The Norwegian police have been allowed to request blood analysis for illegal and prescribed drugs affecting driving performance, even by force if drug influence is suspected. There is currently no legal limit for drugs other than alcohol. The Division of Forensic Toxicology and Drug Abuse (DFTDA) at the Norwegian Institute of Public Health analyse blood samples from all drivers suspected of drugged driving in Norway. Based on results of the blood sample analysis and the CTI, the DFTDA makes a preliminary conclusion of the probability of impairment comparable to BAC above 0.5 g/kg. Then the prosecuting authority decides whether to charge the suspected driver. The impairment has to be proven to the court in each individual case. The court decision is based on the outcome of the CTI, the blood sample analyses, other information that may be given and in most cases an expert witness statement. The sentences can be conditional or unconditional imprisonment, depending on the BAC or the degree of drug impairment and withdrawal of the driving licence for a period of at least 2 years..

[Cannabis affects driving skills]

Delta (9)-tetrahydrocannabinol (THC), the most important psychoactive substance in cannabis, is frequently detected in blood from apprehended drivers suspected for drugged driving. Both experimental and epidemiological studies have demonstrated the negative effects of THC upon cognitive functions and psychomotor skills. These effects could last longer than a measurable concentration of THC in blood. Culpability studies have recently demonstrated an increased risk of becoming responsible in fatal or injurious traffic accidents, even with low blood concentrations of THC. It has also been demonstrated that there is a correlation between the degree of impairment, the drug dose and the THC blood concentration. It is very important to focus on the negative effect of cannabis on fitness to drive in order to prevent injuries and loss of human life and to avoid large economic consequences to the society.

Relationship between THC concentration in blood and impairment in apprehended drivers

OBJECTIVE

The most important psychoactive ingredient in cannabis, Delta (9)-tetrahydrocannabinol (THC) is one of the most frequently detected substances in blood samples from suspected impaired drivers in Norway. There is growing concern over possible links between the use of cannabis and increased risk of motor-vehicle crashes. Experimental studies have provided useful information on the role of THC and dose-effect relations with respect to psychomotor performance. The main purpose of the present study was to investigate whether a physician's judgment on impairment in a real-life setting among suspected drugged drivers, was related to blood THC concentration.

METHODS

In Norway a police physician performs a clinical test for impairment (CTI) shortly after apprehension. The Norwegian Institute of Public Health analyze blood samples from all drivers suspected of driving under the influence of non-alcoholic drugs. In the present study 589 samples from approximately 30,000 cases of suspected drug impaired driving from the period 1997-99, contained THC as the only drug. In 456 of these cases a conclusion of the CTI was available.

RESULTS

230 (54%) drivers were considered not impaired and 226 (46%) impaired. Impaired drivers had higher blood THC concentration than the drivers who were judged as not impaired (median; 2.5 ng/mL (range; 0.3-45.3 ng/mL) vs 1.9 ng/mL (range; 0.32-24.8 ng/mL), (p < 0.05). Furthermore, drivers with blood THC concentrations above 3 ng/mL had an increased risk for being judged impaired compared to drivers with lower concentration ranges.

CONCLUSION

The relationship between the concentration of THC in blood and risk of being assessed impaired found in this cross-sectional study of suspected drugged drivers, supports findings from previous experimental studies of concentration related effects of THC on psychomotor performance and driving skills.

The role of the veno-arteriolar reflex (VAR) in the pathogenesis of peripheral oedema in patients with chronic critical limb ischaemia (CLI)

BACKGROUND AND AIMS

Relatively many patients with chronic critical limb ischaemia (CLI) have oedema in the afflicted limb. Previous studies in these patients indicate derangement in the Starling forces governing transcapillary fluid balance. An impaired veno-arteriolar reflex (VAR) may cause an increase in capillary pressure and hence increased filtration pressure resulting in oedema. The aim of the present study was to investigate VAR in patients with CLI to come to a better understanding of the pathogenesis of ischaemic oedema.

MATERIAL AND METHODS

Sixteen patients (mean age of 78+/-9.4 years) with unilateral CLI and oedema were included. There were two control groups of similar age, one consisted of 8 patients with unilateral CLI but without oedema and the other of 9 healthy subjects. Laser Doppler fluxmeters were used to evaluate the foot skin microcirculation, with the limbs in supine as well as in the dependent position, simultaneously in 4 different areas: the pulp of the first toe (Sitel), at the level of the second metatarsal body (Site 2), at the anterolateral part of ankle (Site 3) and the pulp of the first toe of the contralateral limb (Site 4) as reference. Laser Doppler flux (LDF) values (expressed in perfusion unit, PU) were recorded with the foot dependent (PUd), in the horizontal position (PUh), and the orthostatic response (OR) was calculated at all measuring sites as PUd/PUh.

RESULTS

In none of the measured sites there was a significant difference in OR between the limbs with CLI and oedema and the limbs with CLI but without oedema. The median OR of CLI limbs at site 1 [2.5 (0.61-8.96)] was greater than at sites 2 [0.99 (0.46-2.38), p < 0.01] and 3 [0.95 (0.68-10.31), p < 0.04] respectively, while the differences in OR between site 2 and 3 were not significant. The median OR in the limbs of healthy controls at sites 1, 2 and 3 were 0.58 (0.37-1.43), 0.54 (0.28-1.33) and 0.51 (0.34-0.91), respectively. There were no significant differences in OR between sites 1, 2 and 3 of the control group. The OR of CLI at site 1, 2 and 3 were significantly greater than the corresponding sites in the healthy subjects (p < 0.001, p < 0.008, p < 0.001).

CONCLUSIONS

The VAR is disturbed in limbs with CLI, both in the ones with and without oedema. There were regional differences in the OR in these ischaemic feet but there were no differences in OR between those with and without oedema. Thus, disturbances in VAR may play a role in the development of ischaemic oedema, but is probably not the only causative factor.

The concentration of protein-compounds in interstitial tissue of patients with chronic critical limb ischaemia and oedema

BACKGROUND

Many of chronic critical limb ischaemia (CLI) patients have distal leg and foot oedema. Previous electronmicroscopic studies have shown that chronic severe ischaemia may cause hypoxic damage of the capillary endothelium, including morphological changes i.e. multiplicated/thickened basal lamina, and formation of interendothelial gaps. To assess the functional consequences of these morphologic derangements, where proteins can leak through, we investigated the composition of the interstitial fluid in oedematous ischaemic limbs.

PATIENTS AND METHODS

Nine female and 3 male patients with a mean age of 79 +/- 7.9 years were included. All had unilateral CLI and peripheral pitting oedema. Leg and foot volume was measured with water displacement volumetry. Blister suction technique was used to collect subcutaneous interstitial fluid. The concentration of albumin, transferrin, immunoglobulin G and alpha 2-macroglobulin in plasma and blister fluid was measured by immunoturbidimetry. Nine patients, 8 women and 1 man with a mean age of 83 +/- 5.5 years with a proximal femur fracture served as an age-matched control group.

RESULTS

The mean concentration of albumin in blister fluid was significantly lower in the patients, whereas the mean concentration of alpha 2-macroglobulin in blister fluid did not differ between patients and controls. Mean ratio between concentrations in blister and serum of albumin, transferrin and immunoglobulin G in the limbs with CLI and oedema were significantly lower than respective values in the control group. However, there was no significant difference in the ratio of alpha 2-macroglobulin between these groups.

CONCLUSION

A higher transcapillary concentration gradient for proteins in CLI limbs signifies an increase in the net osmotic pressure gradient across the capillary wall, which may be a potential oedema limiting factor.

Patterns of skin flowmotion in the lower limbs of patients with chronic critical limb ischaemia (CLI) and oedema

OBJECTIVE

To study flowmotion (FM) in lower limbs with critical limb ischaemia (CLI) and oedema and to elucidate FM patterns when skin viability is threatened.

MATERIAL AND METHODS

Fourteen patients with unilateral CLI and oedema and two control groups were included - one consisting of 10 healthy participants and the other nine patients with unilateral CLI without oedema. Laser Doppler was used to evaluate the foot skin microcirculation simultaneously at four different areas, with the limbs in supine and dependent position. FM was expressed using fast Fourier transformation (FFT) as low frequency (LF) and high frequency (HF) waves and their respective FFT-powers.

RESULTS

All patients with CLI, both with and without oedema, showed HF waves in both diseased and contralateral limbs. These were absent in healthy controls. There were no regional differences in frequency in the critically ischaemic feet (with and without oedema) and between ischaemic and their contralateral feet. Changing the position of ischaemic limbs from supine to dependency had no significant effect on the frequency, while a significant increase of the median FFT-powers of LF and HF waves at the pulp of the first toe was observed. This manoeuvre resulted in decrease of the median FFT-powers of LF in healthy controls.

CONCLUSIONS

HF waves are associated with CLI. Ischaemia also appears to influence the FFT-power of each frequency domain. Ischaemic oedema does not seem to affect the pattern of FM in the foot of patients with CLI.

Vascular and stromal features in the skin of the lower limb in patients with chronic critical limb ischaemia (CLI) and oedema

OBJECTIVE

peripheral oedema is often observed in limbs affected by chronic critical limb ischaemia (CLI) and is mainly subcutaneous in distribution. Previous work has shown that capillary filtration coefficient (CFC) in limbs with CLI and oedema was twice as great as that in the contralateral limb. These changes might be due to morphological changes. Transmission electron microscopy (TEM) was used to examine the morphological features of the capillary walls and surrounding stromal tissues in the skin of these limbs.

MATERIAL AND METHODS

eight patients with unilateral CLI and peripheral pitting oedema (four men, four women, a mean age of 81+/-6.9 years) was studied. Skin biopsies were taken from the pulp of the first toe, interdigital space between the first and second digits and dorsal part of forefoot just prior to amputation.

RESULTS

stromal oedema and dilated capillaries were most prominent in the distal part of the foot. Some of the capillaries were filled with blood cells and some were empty. The endothelium of the dilated vessels was elongated and distended. In some patients a number of capillaries were collapsed with degenerate endothelial cells. <<<<Gaps>>>>, i.e. large openings, were found between the elongated oedematous endothelial cells. The basal lamina was thickened in all patients. Stromal haemorrhage and degeneration were seen in approximately 50% of patients.

CONCLUSION

CLI causes ultrastructural changes in the capillary endothelium and surrounding stroma. The presence of large gaps between endothelial cells as well as an increased capillary pressure may enhance transcapillary transudation, and are most likely the causative factors in the formation of the ischaemic oedema. The stromal haemorrhage as well as degeneration probably signifies a terminal stage of CLI.

Transcapillary forces and the development of oedema in the lower limb of patients with chronic critical limb ischaemia (CLI)

OBJECTIVE

factors regulating transcapillary fluid transport were investigated to elucidate the causes of oedema in CLI.

MATERIAL

sixteen patients, 6 men and 10 women (mean age of 79+/-10.3 years) with unilateral CLI and peripheral pitting oedema.

METHODS

measurements were performed in both limbs. Interstitial fluid was collected by applying blister suction cups on the dorsolateral part of the foot and colloid osmotic pressure of this fluid (COP if) was measured in a colloid oncometer. Plasma colloid osmotic pressure (COP pl) was obtained from venous blood. Interstitial fluid pressure (P if) was measured by wick-in-needle technique.

RESULTS

mean COP if in the limbs with CLI was 2.3 S.D. 0.5 mmHg, significantly lower than in the limbs without CLI (3.1 S.D. 0.7 mmHg, p<0.0001). Mean COP pl was 21.1 S.D. 1.8 mmHg, which was lower than in healthy controls. Mean plasma albumin concentration was 30 S.D. 6 g/l which was lower than the reference values. Mean P if in the limbs with CLI was 0.7 S.D. 1.6 mmHg, significantly higher than in the limbs without CLI (-1.4 S.D. 1.4 mmHg, p<0.0001). The calculated mean reabsorption pressure (P r) in the limbs with CLI was 19.6 S.D. 1.7 mmHg, significantly higher than in the contralateral limbs (16.7 S.D. 2.1 mmHg, p<0.001).

CONCLUSION

a low plasma albumin concentration in patients with CLI agrees with the reduction in COP pl but cannot explain the oedema formation, since it is unilateral. The high P r may cause a high transcapillary filtration pressure, resulting in a relatively great net filtration and subsequent oedema formation.

Alterations in capillary permeability in the lower limb of patients with chronic critical limb ischaemia and oedema

BACKGROUND

Oedema formation in lower limbs of patients with chronic critical limb ischaemia (CLI) is a common clinical feature. The rate of fluid filtration through the capillary wall depends on the capillary permeability, i.e. capillary filtration coefficient (CFC). In order to elucidate the pathogenesis of this ischaemic oedema, CFC was measured in the limbs with CLI and oedema and was compared with CFC measurements both in the contralateral sides and in the lower limbs of a control group.

PATIENTS AND METHODS

Eleven women and 4 men, with a mean age of 75 +/- 8.8 years, with unilateral CLI and leg and foot oedema were included. Leg and foot volume was measured with water displacement volumetry (WDV). CFC was measured in both limbs by strain-gauge plethysmography using a double-stranded mercury in silicone strain gauge around the middle portion of the foot. As a control group, 8 patients, 5 women and 3 men, with a mean age of 77 +/- 7.6 years with a proximal femur fracture were included and the CFC in this group was measured in the foot of the non-fractured limb.

RESULTS

Mean CFC in the limbs with CLI and oedema was 0.0036 +/- 0.001 ml/min.100 ml.mmHg, significantly greater than both the contralateral limbs (0.0019 +/- 0.0003 ml/min.100 ml.mmHg, p < 0.01) and mean CFC in the control limbs (0.0017 +/- 0.0002 ml/min.100 ml.mmHg, p < 0.003). There was a mean volume difference of 13 +/- 9% between limbs with CLI and contralateral sides measured by WDV. There was no significant correlation between total leg-foot volume and CFC (p > 0.05).

CONCLUSION

CFC in the ischaemic limb was twice as great as both the contralateral side and the limbs of the control group. It is therefore concluded that an increased CFC is probably one of the important factors in the development of this ischaemic oedema.

The distribution of oedema in the lower limb of patients with chronic critical limb ischaemia: a study with computed tomography

BACKGROUND

A substantial number of patients with chronic critical limb ischaemia (CLI) have considerable oedema at the distal leg and foot of non deep venous thrombosis origin. The primary aim of the present study was to quantify the distribution of oedema in the different tissues of the leg and foot by applying computed tomography and planimetry. The interstitial fluid hydrostatic pressure (Pif) in the subcutaneous tissue was measured to evaluate the effect of oedema on local tissue pressure.

PATIENTS AND METHODS

Six men and 12 women with unilateral CLI and peripheral pitting oedema were included. Cross sectional areas (CSA) of subcutaneous tissue, muscle and bone were measured by computer tomography combined with planimetry to assess the distribution of oedema within the soft tissues. Pif was measured by "wick-in-needle" technique.

RESULTS

The median total CSA of soft tissue, subcutaneous and muscle tissues at the foot level were respectively 17%, 34% and 9% greater in the limbs with CLI compared to the contralateral limb (p < 0.001). At ankle level these differences were 13%, 30% and 4%, respectively (p < 0.001). At the level of the calf these differences were not significant. Mean Pif in the limbs with CLI was 0.3 mmHg, significantly higher than in limbs without CLI (-1.8 mmHg), (p < 0.003).

CONCLUSION

The study verified oedema of considerable magnitude at the ankle and foot. The great part of the oedema was located within the subcutaneous tissue, which was associated with a relatively moderate, but significant increase in Pif confirming the high compliance of the subcutaneous tissue. The combination of the excessive fluid and increased Pif in the interstitial tissue might aggravate the microcirculation. The aetiology of oedema formation is probably multifactorial.

Oedema in the lower limb of patients with chronic critical limb ischaemia (CLI)

OBJECTIVE

approximately 70% of patients with chronic critical limb ischaemia (CLI) show clinical signs of oedema in the distal leg and foot. The primary aim of the present investigation was to quantify this oedema. In addition we investigated whether oedema formation could be due to deep venous thrombosis (DVT).

METHODS

fifteen patients with unilateral CLI and oedema were studied, four males and 11 females, with a mean age of 77+/-10.3 years. Water displacement volumetry (WDV) was used to measure limb volume. Colour duplex ultrasound (CDU) and venous occlusion plethysmography (VOP) were applied to exclude functionally significant DVT. Blood chemistry was analysed to screen for some causative factors of generalised oedema formation.

RESULTS

the mean volume of the limbs with CLI was 9% greater than the contralateral limbs (1279+/-325 ml vs. 1179+/-298 ml). None of the patients had functionally significant DVT. The mean plasma albumin concentration was reduced at 28.5+/-6.6 g/l.

CONCLUSION

a significantly reduced plasma albumin concentration cannot be regarded as a causative factor, since the oedema is unilateral. The aetiology of oedema formation is probably multifactorial, and further investigations are under progress to elucidate relevant pathogenetic factors.