Analgesic Therapy with the Opioids Fentanyl and Morphine by Ambulance Personnel in Rural Areas: An Observational Study Over 7 Years.

Background: The treatment of severe pain is one of the basic procedures of emergency medicine. In rural regions, longer arrival times of the emergency doctor prevent the earliest possible treatment of pain. Since 2014, a project for independent analgesia by ambulance personnel has been introduced in our ambulance service area. Methods: Over a period of 7 years the mission protocols were recorded and statistically evaluated within the framework of an observational study. Among other things, the attendance and transport times, vital signs, pain level, symptom groups (body region) and classification according to disease or accident mechanism were recorded. Treatment data by medication, including dosages, were recorded for fentanyl (monotherapy), morphine (monotherapy) and a combination (change from morphine to fentanyl, additional application of esketamine, metamizole or butylscopolamine). Results: In 659 patients, the opioids fentanyl and morphine were used by the ambulance staff, 596 data sets could be evaluated. When an emergency physician was requested, the average time of presence at the scene was 34.8 +- 11.7 min, in cases of unavailability it was 29.0 +-9.8 min (p<0.0001). Analgesic therapy resulted in a reduction of pain from NRS 8.4 (+-1.3) to NRS 3.5 +-1.8 (p<0.0001). Pain intensity after treatment by emergency paramedics compared to emergency physicians was not significantly different with NRS 3.5 +- 1.7 versus NRS 3.6 +-1.9 (p=0.788). Fentanyl was used at a mean dose of 0.18mg +- 0.11 and morphine at a mean dose of 4.4mg +- 3.6mg. There was no clinically relevant decrease in oxygen saturation or respiratory rate in any of the treatment groups. Antagonisation of the opioid effect with naloxone was not necessary in any case. Conclusion: Analgesia with morphine and fentanyl by specially trained ambulance personnel according to defined rules of use is a safe and necessary procedure for patients, especially in rural regions.

Application of analgesics in emergency services in Germany: a survey of the medical directors.

ABSTRAC: BACKGROUND: Treatment of acute pain is an essential element of pre-hospital care for injured and critically ill patients. Clinical studies indicate the need for improvement in the prehospital analgesia. OBJECTIVE: The aim of this study is to assess the current situation in out of hospital pain management in Germany regarding the substances, indications, dosage and the delegation of the use of analgesics to emergency medical service (EMS) staff. MATERIAL AND METHODS: A standardized survey of the medical directors of the emergency services (MDES) in Germany was carried out using an online questionnaire. The anonymous results were evaluated using the statistical software SPSS (Chi-squared test, Mann-Whitney-U test). RESULTS: Seventy-seven MDES responsible for 989 rescue stations and 397 EMS- physician bases in 15 federal states took part in this survey. Morphine (98.7%), Fentanyl (85.7%), Piritramide (61%), Sufentanil (18.2%) and Nalbuphine (14,3%) are provided as opioid analgesics. The non-opioid analgesics (NOA) including Ketamine/Esketamine (98,7%), Metamizole (88.3%), Paracetamol (66,2%), Ibuprofen (24,7%) and COX-2-inhibitors (7,8%) are most commonly available. The antispasmodic Butylscopolamine is available (81,8%) to most rescue stations. Fentanyl is the most commonly provided opioid analgesic for treatment of a traumatic pain (70.1%) and back pain (46.8%), Morphine for visceral colic-like (33.8%) and non-colic pain (53.2%). In cases of acute coronary syndrome is Morphine (85.7%) the leading analgesic substance. Among the non-opioid analgesics is Ketamine/Esketamine (90.9%) most frequently provided to treat traumatic pain, Metamizole for visceral colic-like (70.1%) and non-colic (68.6%) as well as back pain (41.6%). Butylscopolamine is the second most frequently provided medication after Metamizole for "visceral colic-like pain" (55.8%). EMS staff (with or without a request for presence of the EMS physician on site) are permitted to use the following: Morphine (16.9%), Piritramide (13.0%) and Nalbuphine (10.4%), and of NOAs for (Es)Ketamine (74.1%), Paracetamol (53.3%) and Metamizole (35.1%). The dosages of the most important and commonly provided analgesic substances permitted to independent treatment by the paramedics are often below the recommended range for adults (RDE). The majority of medical directors (78.4%) of the emergency services consider the independent application of analgesics by paramedics sensible. The reason for the relatively rare authorization of opioids for use by paramedics is mainly due to legal (in)certainty (53.2%). CONCLUSION: Effective analgesics are available for EMS staff in Germany, the approach to improvement lies in the area of application. For this purpose, the adaptations of the legal framework as well as the creation of a guideline for prehospital analgesia are useful.

Planning as Inference in Epidemiological Dynamics Models.

In this work we demonstrate how to automate parts of the infectious disease-control policy-making process via performing inference in existing epidemiological models. The kind of inference tasks undertaken include computing the posterior distribution over controllable, via direct policy-making choices, simulation model parameters that give rise to acceptable disease progression outcomes. Among other things, we illustrate the use of a probabilistic programming language that automates inference in existing simulators. Neither the full capabilities of this tool for automating inference nor its utility for planning is widely disseminated at the current time. Timely gains in understanding about how such simulation-based models and inference automation tools applied in support of policy-making could lead to less economically damaging policy prescriptions, particularly during the current COVID-19 pandemic.

Prehospital point-of-care emergency ultrasound: a cohort study.

BACKGROUND: In the prehospital situation, the diagnostic armamentarium available to the rescue physician is limited. Emergency ultrasound has proven to be a useful diagnostic tool, providing crucial information for the management of critically ill and injured patients. The proportion of performed ultrasound scans in all patients attended to by the rescue service team, the quality of the findings and the ultrasound-related changes in management approach and patient transport were evaluated. METHODS: In this prospective 18-month observational study, we documented all missions performed by rescue physicians with special training in emergency ultrasound (expert standard). These data were than analysed with regard to the ultrasound examinations. The ultrasound protocols used comprised Focussed Assessment with Sonography for Trauma (FAST), Prehospital Lung Ultrasound (PLUS) and Focused Echocardiography in Emergency Life support (FEEL). The quality of prehospital examinations was assessed by comparing the findings and diagnoses at the emergency site with those established in hospital. The changes in patient management and transport were documented using a standardized protocol. RESULTS: A total of 99 (18.1%) emergency ultrasound examinations were performed during 546 callouts. The most common indications for prehospital emergency ultrasound were dyspnoea (n = 38; 38.4%), during cardiac arrest (n = 17/17.2%), fall (n = 12/12.1%) and high-speed trauma (n = 11/11.1%). The combinations of ultrasound examination protocols in the trauma group (n = 31; 31.3%) were: 1. FAST+FEEL+PLUS (n = 17; 54.8%). 2. FAST+PLUS (n = 11; 35.5%) 3. FAST alone (n = 3; 9.7%). In the non-trauma group (n = 68; 68.7%), the following combinations were used: 1. FEEL+PLUS (n = 36; 52.9%), 2. FEEL alone (n = 21/30.9%). 3. PLUS alone (n = 6/8.8%) 4. FAST alone (n = 2; 2.9%) 5. FAST+FEEL+PLUS (n = 2; 2.9%). 6. FAST+FEEL (n = 1/1.5%). The emergency ultrasound findings impaired left ventricular contractile function (sensitivity 89.4%), right ventricular stress (85.7%), lung interstitial syndrome (100%), ruling out pneumothorax (specificity 100%), ruling out intraabdominal fluid (97,1%) were verified at the receiving hospital using ultrasonography, CT scan or x-rays; the prehospital diagnosis was confirmed in 90.8% of cases, the difference between the prehospital and in-hospital findings were not significant(p-values from p = 0.688 to p = 0,99). Ultrasound-related changes in patient management occurred in 49.5% of patients; in 33.3%, these were transported-related. CONCLUSIONS: Emergency ultrasound was as often used in the prehospital situation as it is in hospital. The ultrasound findings correlated well with in-hospital diagnostic results. Significant pathology changed patient-management, without prolonging the mission time.

Influence of static magnetic fields on human myoblast/mesenchymal stem cell co­cultures.

The results of surgical repair of extensive muscle tissue defects are still of primary concern, leaving patients with residual cosmetic and functional impairments. Therefore, skeletal muscle tissue engineering attempts to grow functional neo­tissue from human stem cells to promote tissue regeneration and support defect closure. Despite intensive research efforts, the goal of stable induction of myogenic differentiation in expanded human stem cells by using clinically feasible stimuli, has not yet been reached to a sufficient extent. Therefore, the present study investigated the differentiation potential of static magnetic fields (SMFs), using co­cultures of human satellite cells and human mesenchymal stem cells (MSCs). It has previously been demonstrated that SMFs may act as a promising myogenic stimulus. Tests were performed on co­cultures with and without SMF exposure, using growth medium [high growth factor concentrations (GM)] and differentiation medium [low growth factors concentrations (DM)]. AlamarBlue® assay­based cell proliferation analysis revealed no significant difference between co­cultures with, vs. without SMF stimulation, regardless of growth factor concentrations in the cell culture medium. To determine the degree of differentiation in co­cultures under stimulation with SMFs, semi­quantitative gene expression measurements of the following marker genes were performed: Desmin, myogenic factor 5, myogenic differentiation antigen 1, myogenin, adult myosin heavy chain 1 and skeletal muscle α1 actin. In neither GM nor DM was a steady, significant increase in marker gene expression detected. Verifying the gene expression findings, immunohistochemical antibody staining against differentiation markers revealed that SMF exposure did not enhance myogenic maturation. Therefore, SMF treatment of human satellite cell/MSC co­cultures did not result in the desired increase in myogenic differentiation. Further studies are required to identify a suitable stimulus for skeletal muscle tissue engineering.

Project for the introduction of prehospital analgesia with fentanyl and morphine administered by specially trained paramedics in a rural service area in Germany.

BACKGROUND: In patients with serious illness or trauma, reduction of severe pain is a key therapeutic goal of emergency medical service (EMS) teams. In Germany, only physicians are allowed to use opioid analgesics. In the rural EMS area studied, the mean arrival time for paramedics is 8 minutes, 23 seconds, and for the rescue physician between 10 minutes, 30 seconds and 16 minutes, 59 seconds, depending on EMS site. In cases of parallel callouts, rescue-physician arrival times may be considerably longer. OBJECTIVE: During this project, we assessed the administration of the opioid analgesics morphine and fentanyl by specially trained paramedics with regard to analgesia quality and patient safety. MATERIALS AND METHODS: During the 18-month study period, specially trained paramedics administered morphine or fentanyl to patients with severe pain if indicated and if a rescue physician was not available in time. Besides basic documentation, pain intensity (using a numeric rating scale) and oxygen saturation were measured initially and at hospital handover. RESULTS: During the 18 months, 4,285 emergency callouts were attended to by the 13 specially trained paramedics of the district (total callouts during this period 21,423). In 77 patients (1.8%), fentanyl (n=53/68.8%) or morphine (n=24/31.2%) was administered. Based on the measurements obtained with the numeric rating scale at the start of treatment (7.9) and upon hospital handover (3.3), pain reduction was 4.52 overall (41.5%, P<0.001): 4.64 with fentanyl (42.9%, P<0.001) and 4.25 with morphine (43.2%, P<0.001). None of the patients had an oxygen saturation <95% at the time of handover, and no patient developed opioid-induced respiratory depression requiring treatment. CONCLUSION: The results of this study indicate that the administration of opioid analgesics by specially trained and qualified paramedics is safe and effective.

Effectiveness of various formulations of local anesthetics and additives for topical anesthesia - a prospective, randomized, double-blind, placebo-controlled study.

BACKGROUND: Topical anesthesia is used to control pain associated with many procedures in medicine. Today, the product most commonly applied for topical anesthesia in Germany is EMLA® (lidocaine/prilocaine). However, since prilocaine is a methemoglobin-inducing agent, there are limitations to its use, especially in neonates and infants. The aim of this study was to evaluate the effect of prilocaine and lidocaine as well as propylene glycol, a penetration enhancer, and trometamol, a buffer substance, in anesthetic creams. PATIENTS AND METHODS: Twenty-nine healthy adults participated in this study. Standardized creams with eight different compositions were applied and left for 20, 40 or 60 min. After exposure to standardized painful stimuli (blunt/sharp with pressures of 0.2, 0.4 or 0.8 N), subjects rated the experimental pain using a visual analog scale. RESULTS: Significant results were only found with an exposure time of 60 min and a stamp pressure of 0.8 N. At a concentration of 20%, lidocaine was more effective compared to placebo and equally effective compared to lidocaine/prilocaine in controlling pain. The analgesic effect of the cream containing lidocaine 10% and additional trometamol was significantly superior to that of placebo and non-inferior to that of lidocaine/prilocaine. In this study, the penetration enhancer propylene glycol did not accelerate the onset of the analgesic effect. In contrast, the addition of trometamol (Tris/THAM) accelerated the onset of the effect compared to the native formulation (at 0.4 and 0.8 N). In all of the adult subjects of this study, the minimum exposure time was 60 min for any of the tested topical anesthetic creams. CONCLUSION: The results of this study indicate that a cream containing 20% lidocaine, 38% trometamol and 10% propylene glycol may be used as an alternative to lidocaine/prilocaine with a comparable effect and without the need to extend exposure time.

The improved quality of postoperative analgesia after intrathecal morphine does not result in improved recovery and quality of life in the first 6 months after orthopedic surgery: a randomized controlled pilot study.

OBJECTIVE: In orthopedic surgery, it is well known that the use of intrathecal morphine (ITM) leads to an improved quality of postoperative analgesia. Little is known how this improved analgesia affects the long-term course after surgery. STUDY DESIGN: A randomized, double-blind trial. SETTING: Academic medical center. SUBJECTS: Forty-nine patients undergoing total hip or knee replacement surgery in spinal anesthesia. METHODS: Patients were randomly assigned to receive either 0.1 mg (n=16) or 0.2 mg (n=16) morphine sulfate intrathecally or physiological saline (n=17) added to 3 mL 0.5% isobaric bupivacaine for spinal anesthesia. As a function of the quality of the short-term postoperative analgesia, the effect on recovery and quality of life was evaluated at various time points up to 26 weeks after surgery. RESULTS: In both ITM groups, the additionally required postoperative systemic morphine dose was significantly reduced compared with the placebo group (P=0.004). One week after operation, patients with ITM reported significantly less pain at rest (P=0.01) compared to the placebo group. At discharge, in comparison with the 0.1 mg ITM and placebo group, the 0.2 mg ITM group showed a higher degree of impairment regarding pain, stiffness, and physical function of the respective joint (P=0.02). Over the further follow-up period of 6 months after surgery, recovery and the quality of life did not differ significantly between the three study groups (P>0.2). CONCLUSION: Morphine (0.1 mg) as adjunct to 0.5% bupivacaine for spinal anesthesia is effective to produce a pronounced postoperative analgesia with a beneficial analgesic effect up to 1 week after surgery. With this study design, the different quality of postoperative analgesia had no effect on quality of life and recovery in patients over the 6-month follow-up period. In the medium term, ITM may induce hyperalgesic effects.

Negative- versus positive-pressure ventilation in intubated patients with acute respiratory distress syndrome.

INTRODUCTION: Recent experimental data suggest that continuous external negative-pressure ventilation (CENPV) results in better oxygenation and less lung injury than continuous positive-pressure ventilation (CPPV). The effects of CENPV on patients with acute respiratory distress syndrome (ARDS) remain unknown. METHODS: We compared 2 h CENPV in a tankrespirator ("iron lung") with 2 h CPPV. The six intubated patients developed ARDS after pulmonary thrombectomy (n = 1), aspiration (n = 3), sepsis (n = 1) or both (n = 1). We used a tidal volume of 6 ml/kg predicted body weight and matched lung volumes at end expiration. Haemodynamics were assessed using the pulse contour cardiac output (PiCCO) system, and pressure measurements were referenced to atmospheric pressure. RESULTS: CENPV resulted in better oxygenation compared to CPPV (median ratio of arterial oxygen pressure to fraction of inspired oxygen of 345 mmHg (minimum-maximum 183 to 438 mmHg) vs 256 mmHg (minimum-maximum 123 to 419 mmHg) (P < 0.05). Tank pressures were -32.5 cmH2O (minimum-maximum -30 to -43) at end inspiration and -15 cmH2O (minimum-maximum -15 to -19 cmH2O) at end expiration. NO Inspiratory transpulmonary pressures decreased (P = 0.04) and airway pressures were considerably lower at inspiration (-1.5 cmH2O (minimum-maximum -3 to 0 cmH2O) vs 34.5 cmH2O (minimum-maximum 30 to 47 cmH2O), P = 0.03) and expiration (4.5 cmH2O (minimum-maximum 2 to 5) vs 16 cmH2O (minimum-maximum 16 to 23), P =0.03). During CENPV, intraabdominal pressures decreased from 20.5 mmHg (12 to 30 mmHg) to 1 mmHg (minimum-maximum -7 to 5 mmHg) (P = 0.03). Arterial pressures decreased by approximately 10 mmHg and central venous pressures by 18 mmHg. Intrathoracic blood volume indices and cardiac indices increased at the initiation of CENPV by 15% and 20% (P < 0.05), respectively. Heart rate and extravascular lung water indices remained unchanged. CONCLUSIONS: CENPV with a tank respirator improved gas exchange in patients with ARDS at lower transpulmonary, airway and intraabdominal pressures and, at least initially improving haemodynamics. Our observations encourage the consideration of further studies on the physiological effects and the clinical effectiveness of CENPV in patients with ARDS.

Early alveolar and systemic mediator release in patients at different risks for ARDS after multiple trauma.

Alveolar IL-8 has been reported to early identify patients at-risk to develop ARDS. However, it remains unknown how alveolar IL-8 is related to pulmonary and systemic inflammation in patients predisposed for ARDS. We studied 24 patients 2-6h after multiple trauma. Patients with IL-8 >200 pg/ml in bronchoalveolar lavage (BAL) were assigned to the group at high risk for ARDS (H, n = 8) and patients with BAL IL-8 <200 pg/ml to the group at low risk for ARDS (L, n = 16). ARDS developed within 24h after trauma in 5 patients at high and at least after 1 week in 2 patients at low risk for ARDS (p = 0.003). High-risk patients had also increased BAL IL-6, TNF-α, IL-1ß, IL-10 and IL-1ra levels (p<0.05). BAL neutrophil counts did not differ between patient groups (H vs. L, 12% (3-73%) vs. 6% (2-32%), p = 0.1) but correlated significantly with BAL IL-8, IL-6 and IL-1ra. High-risk patients had increased plasma levels of pro- but not anti-inflammatory mediators. The enhanced alveolar and systemic inflammation associated with alveolar IL-8 release should be considered to identify high-risk patients for pulmonary complications after multiple trauma to adjust surgical and other treatment strategies to the individual risk profile.

Skin impedance correlates to sedation grade, plasma propofol concentrations and bispectral index during a target-controlled infusion of propofol.

BACKGROUND AND OBJECTIVE: Sympathetic activity, measured as changes in electrical skin impedance, may be used to assess the adequacy of general anaesthesia. The aim of this prospective study was to evaluate electrical skin impedance in comparison with bispectral index values and the Observer's Assessment of Alertness and Sedation (OAAS) scale during propofol infusion. METHODS: Electrical skin impedance was measured with an electrosympathicograph. In 22 patients and eight healthy volunteers, anaesthesia was induced and maintained with propofol that was administered via a target-controlled infusion pump at increasing plasma concentrations. Bispectral index, electrosympathicograph and OAAS values were compared at six successive predicted target plasma concentrations (T 1-6: 0, 1.3, 1.7, 2.0, 2.4 and 2.8 microg ml(-1)). RESULTS: The changes in the electrical skin impedance measured with the assistance of the electrosympathicograph correlated with the changes in bispectral index values at each measurement time point and during the whole course (P < 0.0001), with the target plasma propofol concentrations (P < 0.0001), and with the OAAS scale (P < 0.0001). CONCLUSION: The observed correlations between electrical skin impedance, predicted plasma concentrations of propofol and OAAS scale appear to justify further investigation of skin impedance as a depth of anaesthesia monitor.

Complex myograph allows the examination of complex muscle contractions for the assessment of muscle force, shortening, velocity, and work in vivo.

BACKGROUND: The devices used for in vivo examination of muscle contractions assess only pure force contractions and the so-called isokinetic contractions. In isokinetic experiments, the extremity and its muscle are artificially moved with constant velocity by the measuring device, while a tetanic contraction is induced in the muscle, either by electrical stimulation or by maximal voluntary activation. With these systems, experiments cannot be performed at pre-defined, constant muscle length, single contractions cannot be evaluated individually and the separate examination of the isometric and the isotonic components of single contractions is not possible. METHODS: The myograph presented in our study has two newly developed technical units, i.e. a). a counterforce unit which can load the muscle with an adjustable, but constant force and b). a length-adjusting unit which allows for both the stretching and the contraction length to be infinitely adjustable independently of one another. The two units support the examination of complex types of contraction and store the counterforce and length-adjusting settings, so that these conditions may be accurately reapplied in later sessions. RESULTS: The measurement examples presented show that the muscle can be brought to every possible pre-stretching length and that single isotonic or complex isometric-isotonic contractions may be performed at every length. The applied forces act during different phases of contraction, resulting into different pre- and after-loads that can be kept constant - uninfluenced by the contraction. Maximal values for force, shortening, velocity and work may be obtained for individual muscles. This offers the possibility to obtain information on the muscle status and to monitor its changes under non-invasive measurement conditions. CONCLUSION: With the Complex Myograph, the whole spectrum of a muscle's mechanical characteristics may be assessed.

Ethanol-induced malfunction of neutrophils respiratory burst on patients suffering from alcohol dependence.

BACKGROUND: Polymorphonuclear, neutrophil granulocytes (PMN) play a major role in the control of infections, and people who abuse alcohol are susceptible to infections. Resistance against infections ensues intracellularly following initial phagocytosis of microorganisms with the oxygen-dependent respiratory burst, the key enzyme of which is the respiratory burst oxidase, whereby oxygen radicals are produced for microbial destruction. To date there is insufficient information available in connection with the process of impaired defence against infection in patients suffering from alcohol dependence. Therefore, our investigation was carried out to determine the influence of alcohol exposition on the formation of oxygen radicals and the respiratory burst. METHODS: 4.5 ml of whole blood was taken from 10 healthy adults and 10 patients suffering from alcohol dependence. An additional 3.5 ml of whole blood was taken from the alcoholic patients for determination of the blood alcohol concentration. The respiratory burst of PMN was tested using the Four-Colour-Continuous Flow Cytometer. Each experimental procedure consisted of 4 test samples [negative controls, Escherichia coli, FMLP-supplement (N-formyl-l-methionyl-l-leucyl-l-phenylalanin), PMA-supplement (phorbol-12-myristate-13-acetate)]. Differing concentrations of ethanol were also introduced to each of the tests performed (0.20 to 4.00 g/l). RESULTS: Ethanol revealed a marked decrease of burst activity in those patients suffering from alcoholism with increased alcohol concentration. A dependence between the burst activity and the ethanol concentration was seen to be statistically significant. This effect was only evident after stimulation with E. coli and FMLP in those patients with alcohol dependence. CONCLUSION: The results presented in this study show an impairment in the function of PMN in those patients addicted to alcohol due to the decrease in burst activity. In view of the results of the different stimuli, the second-messenger effects were not evident. A clarification of this phenomenon could well be assumed as an allosteric receptor effect on the burst oxidase, namely, a direct effect on the phagocytosis interaction between circulating granulocytes and causative organisms.

Unsaturated long-chain fatty acids induce the respiratory burst of human neutrophils and monocytes in whole blood.

BACKGROUND: It is increasingly recognized that infectious complications in patients treated with total parenteral nutrition (TPN) may be caused by altered immune responses. Neutrophils and monocytes are the first line of defence against bacterial and fungal infection through superoxide anion production during the respiratory burst. To characterize the impact of three different types of lipid solutions that are applied as part of TPN formulations, we investigated the unstimulated respiratory burst activation of neutrophils and monocytes in whole blood. METHODS: Whole blood samples were incubated with LCT (Intralipid(R)), LCT/MCT (Lipofundin(R)) and LCT-MUFA (ClinOleic(R)) in three concentrations (0.06, 0.3 and 0.6 mg ml-1) for time periods up to one hour. Hydrogen peroxide production during the respiratory burst of neutrophils and monocytes was measured by flow cytometry. RESULTS: LCT and LCT-MUFA induced a hydrogen peroxide production in neutrophils and monocytes without presence of a physiological stimulus in contrast to LCT/MCT. CONCLUSION: We concluded that parenteral nutrition containing unsaturated oleic (C18:1) and linoleic (C18:2) acid can induce respiratory burst of neutrophils and monocytes, resulting in an elevated risk of tissue damage by the uncontrolled production of reactive oxygen species. Contradictory observations reported in previous studies may in part be the result of different methods used to determine hydrogen peroxide production.

Assessment of precision and reproducibility of a new myograph.

BACKGROUND: The physiological characteristics of muscle activity and the assessment of muscle strength represent important diagnostic information. There are many devices that measure muscle force in humans, but some require voluntary contractions, which are difficult to assess in weak or unconscious patients who are unable to complete a full range of voluntary force assessment tasks. Other devices, which obtain standard muscle contractions by electric stimulations, do not have the technology required to induce and measure reproducible valid contractions at the optimum muscle length. METHODS: In our study we used a newly developed diagnostic device which measures accurately the reproducibility and time-changed-variability of the muscle force in an individual muscle. A total of 500 in-vivo measurements of supra-maximal isometric single twitch contractions were carried out on the musculus adductor pollicis of 5 test subjects over 10 sessions, with ten repetitions per session. The same protocol was performed on 405 test subjects with two repetitions each to determine a reference-interval on healthy subjects. RESULTS: Using our test setting, we found a high reproducibility of the muscle contractions of each test subject. The precision of the measurements performed with our device was 98.74%. Only two consecutive measurements are needed in order to assess a real, representative individual value of muscle force. The mean value of the force of contraction was 9.51 N and the 95% reference interval was 4.77-14.25 N. CONCLUSION: The new myograph is a highly reliable measuring device with which the adductor pollicis can be investigated at the optimum length. It has the potential to become a reliable and valid tool for diagnostic in the clinical setting and for monitoring neuromuscular diseases.

In vivo myograph measurement of muscle contraction at optimal length.

BACKGROUND: Current devices for measuring muscle contraction in vivo have limited accuracy in establishing and re-establishing the optimum muscle length. They are variable in the reproducibility to determine the muscle contraction at this length, and often do not maintain precise conditions during the examination. Consequently, for clinical testing only semi-quantitative methods have been used. METHODS: We present a newly developed myograph, an accurate measuring device for muscle contraction, consisting of three elements. Firstly, an element for adjusting the axle of the device and the physiological axis of muscle contraction; secondly, an element to accurately position and reposition the extremity of the muscle; and thirdly, an element for the progressive pre-stretching and isometric locking of the target muscle. Thus it is possible to examine individual in vivo muscles in every pre-stretched, specified position, to maintain constant muscle-length conditions, and to accurately re-establish the conditions of the measurement process at later sessions. RESULTS: In a sequence of experiments the force of contraction of the muscle at differing stretching lengths were recorded and the forces determined. The optimum muscle length for maximal force of contraction was established. In a following sequence of experiments with smaller graduations around this optimal stretching length an increasingly accurate optimum muscle length for maximal force of contraction was determined. This optimum length was also accurately re-established at later sessions. CONCLUSION: We have introduced a new technical solution for valid, reproducible in vivo force measurements on every possible point of the stretching curve. Thus it should be possible to study the muscle contraction in vivo to the same level of accuracy as is achieved in tests with in vitro organ preparations.