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Biomedical subjects

A Loh

Publications and source records attributed to A Loh.

At least 19 recordsLinked to original sources
PubMed2006

Development and first validation of the shared decision-making questionnaire (SDM-Q).

OBJECTIVE: Due to a lack of valid German instruments measuring shared decision-making (SDM), a theory-driven questionnaire (SDM-Q) to measure the process of SDM was developed and validated. METHODS: As a theoretical basis steps of the SDM process were defined in an expert panel. Item formulation was then conducted according to the Delphi method. For the first validation on a mixed sample Rasch analysis was used to eliminate items not fitting the construct thus receiving a unidimensional scale. RESULTS: After eliminating 4 items the remaining 11 form a unidimensional scale with an acceptable reliability for person measures (0.77) and very good reliability for item difficulties (0.95). Analysis of subgroups revealed a different use of items in different conditions. Furthermore the scale showed high ceiling effects. CONCLUSION: A new theory-driven instrument to measure the process of SDM has been developed and validated by use of a rigorous method revealing first promising results. Yet the ceiling effects require the addition of more discriminating items, and the different use of items in different conditions demands an in depth analysis. PRACTICE IMPLICATIONS: While the concept of SDM is constantly receiving more attention in medical practice, its valid and reliable measurement remains challenging.

Decision Making↗
PubMed2006

[Effects of a shared decision making model in psychiatric and neurologic practice].

Involving patients in medical decisions is increasingly being advocated in medical fields other than psychiatry and neurology. A model of shared decision making might prove to be an ideal way of bridging the gap between patient-centred and evidence-based medicine. This report provides a survey of this shared decision making model and a discussion of its implications in the fields of mental health and neurology.

Adaptation, Psychological↗
PubMed2004

[Development and validation of assessment instruments for shared decision making].

The German Ministry for Health and Social Security is funding ten projects to introduce shared decision making into clinical practice. The medical problems the projects are focussing on were chosen from among various diseases (e. g. depression, multiple sclerosis, cancer). The ten projects achieved consensus on a core set of instruments for the measurement of process and outcome of the shared decision making. Instruments developed in German-speaking countries are currently not available. Thus, linguistic and cultural validation had to be performed for the core set instruments. The results of the data analysis as well as patient interviews demonstrate the need for improving these instruments. Therefore, the members of the methodological working group concentrated on the integration of these results in a new instrument. In a first step the construct of "shared decision making" was defined, followed by a definition of the process elements characterising shared decision making. Thereafter, items were developed on the basis of the process elements. The new instrument will now be validated for different diseases.

Decision Making↗
PubMed2004

[Development and evaluation of a training program in shared decision making for primary care of depressive patients].

Patient surveys show that many patients want broad information about their disease and treatment. Often they are interested to participate in the process of medical decision making, which could be realised with the concept of shared decision making where patient's values and needs are considered to the same extent as the treatment recommendations of evidence-based medicine. In depression care, it has been demonstrated so far that the active involvement of patients contributes to higher motivation for treatment. For enhancing patient's acceptance and motivation to avail themselves of medical treatment, a training program for general practitioners was developed and evaluated. It was the aim of the training to involve depressive patients in medical decision making. The training consists of depression-specific components (e. g. diagnosis, patient information, therapy) and general components (communication and shared decision making). The training was carried out in five sessions within a 6-month period (May to October 2003) embracing 20 h of training. Participants were 20 general practitioners in Southwest Germany. Physician's satisfaction with the training program is high. Especially in the fields of diagnosis and shared decision making the physicians clearly benefited. Transfer of shared decision making into daily routine was assessed as possible by the large majority of the trainees. Application of the training concept to other diseases and evaluation on the basis of daily routine is recommended. The training effects on medical care are presently being assessed in a randomised controlled trial.

Adult↗
PubMed2004

[Outcome of interactive training in detection and management skills for schizophrenic outpatient treatment by general practitioners].

THEORETICAL BACKGROUND: Of all outpatients with a diagnosis of schizophrenia, 30-40% refuse a psychiatrist's care. For this group of patients the general practitioner holds a key position for such different tasks as detection of prodromal schizophrenia or early warning signs of relapse and identification of risk variables for deteriorating outcome, gatekeeping (referral to specialists or other services), integration, and counseling of key relatives. Fifty percent of GPs are interested in disease-specific medical education programs. STUDY DESIGN AND METHODS: A control trial examined the changes that participating GPs intended to make in three main topics of the curriculum: (1) changing attitudes (pessimistic outcome expectation, low self-esteem), (2) enhancement of detection skills (prodromal schizophrenia, early warning signs of relapse, and risk factors for poor social and vocational integration), and (3) enhancement of management skills (dosing schemes, motivational interviewing). RESULTS: In the assessment 2 weeks after the training session, we found significant changes in favor of the trained group in detection and management skills and also improved self-confidence of GPs. CONCLUSIONS: Problem-oriented and case-based learning strategies should be preferred to lectures in training programs for psychiatric skills in primary care.

Adult↗
PubMed1998

Pharmacokinetic model of iodine-131-G250 antibody in renal cell carcinoma patients.

UNLABELLED: A model that describes the pharmacokinetic distribution of 131I-labeled G250 antibody is developed. METHODS: Previously collected pharmacokinetic data from a Phase I-II study of 131I-G250 murine antibody against renal cell carcinoma were used to develop a mathematical model describing antibody clearance from serum and the whole body. Survey meter measurements, obtained while the patient was under radiation precautions, and imaging data, obtained at later times, were combined to evaluate whole-body clearance kinetics over an extended period. RESULTS: A linear two-compartment model was found to provide good fits to the data. The antibody was injected into Compartment 1, the initial distribution volume (Vd) of the antibody, which included serum. The antibody exchanged with the rest of the body, Compartment 2, and was eventually excreted. Data from 13 of the 16 patients fit the model with unique parameters; the maximum, median and minimum values for model-derived Vd were 6.3, 3.7 and 2.11, respectively. The maximum, median and minimum values for the excretion rate were 8 x 10(-2), 2.4 x 10(-2) and 1.3 x 10(-2) hr(-1), respectively. Parameter sensitivity analysis showed that a change in the transfer rate constant from serum to the rest of the body had the greatest effect on serum cumulative activity and that the rate constant for excretion had the greatest effect on whole-body cumulative activity. CONCLUSION: A linear two-compartment model was adequate in describing the serum and whole-body kinetics of G250 antibody distribution. The median initial distribution volume predicted by the model was consistent with the nominal value of 3.81. A wide variability in fitted parameters was observed among patients, reflecting the differences in individual patient clearance and exchange kinetics of G250 antibody. By selecting median parameter values, such a model may be used to evaluate and design prolonged multiple administration radioimmunotherapy protocols.

Adult↗
PubMed1994

Hypercoagulable states in patients with leg ischaemia.

Hypercoagulable states are found in up to 10 per cent of patients with a history of unexplained venous thrombosis. To investigate the prevalence in arterial thrombosis, thrombophilia screening was performed on 124 patients who had previously undergone lower-limb revascularization, 45 claudicants and 27 controls. Of the patients who had undergone revascularization 40 per cent had a hypercoagulation abnormality (low levels of protein C, protein S and antithrombin III or presence of the lupus anticoagulant) in comparison with 27 per cent of claudicants and 11 per cent of controls (P < 0.01). Furthermore, patients who had suffered reocclusion after revascularization were significantly more likely to have a hypercoagulation abnormality than those who had not (P < 0.05), even if the occlusion had occurred more than 6 months previously. Lupus anticoagulant was the abnormality most frequently detected and, like low protein C levels, was found only in patients with peripheral vascular disease. It appears that hypercoagulable states are common in patients with arterial disease and may predispose to failure of revascularization.

Aged↗
PubMed1994

Detection of circulating cerebral emboli using Doppler ultrasound in a sheep model.

We describe a validation study of a new technique for detecting circulating pathological cerebral emboli. Theoretically one would expect solid emboli to be detectable as high intensity signals on the Doppler waveform, and such signals have been reported in humans with potential embolic sources. Pathological cerebral emboli (thrombi, platelet aggregates and atheroma) were introduced into the proximal carotid artery of an in vivo sheep model, and their passage detected in the cerebral circulation using Doppler ultrasound. All of 74 emboli, with a maximum dimension as small as 0.24 mm, were detected as short duration high intensity signals. Smaller pathological emboli could not be made but glass microspheres as small as 5-20 micron resulted in high intensity signals. A significant positive correlation was found between embolus size and relative intensity increase of the embolic signal. A significant positive correlation was also found between embolus size and duration of embolic signal. This study demonstrates that detection of circulating cerebral emboli is possible in vivo. This technique may allow selection of patients at particularly high risk of cerebral embolisation so that they can be given specific prophylactic treatment. Analysis of the Doppler signal may give information on the size of the embolus, although using current signal analysis it is impossible to distinguish between the signals produced by say a larger platelet embolus or a smaller thrombus embolus.

Animals↗
PubMed1994

Simplified technique for peritoneal dissection during laparoscopic hernia repair.

The use of a small rod (5-mm diameter, 20-cm length, code no. BN320, Aesculap Ltd., Sheffield, England) inserted extraperitoneally has been a useful tool in aiding peritoneal dissection during laparoscopic hernia repair. Experience gained in 100 such repairs using this instrument has helped to reduce the operating time in most instances.

Hernia, Inguinal↗
PubMed1994

Accuracy of intraoperative staging in colorectal cancer.

In 216 patients with colorectal adenocarcinoma 'operative' and 'final' staging using Duke's classification were compared. The overall 'accuracy' of operative staging was 66% with 17% of tumours understaged and 17% overstaged. The major error was found in nodal staging. If selective peroperative adjuvant therapy is to be considered, efforts should be directed to improve operative nodal staging. Any recommendation for adjuvant perioperative chemotherapy based on operative staging alone will result in a significant number of patients having unnecessary treatment.

Adenocarcinoma↗
PubMed1993

Microscopic air embolism during cerebral angiography and strategies for its avoidance.

Cerebral angiography is associated with a risk of neurological complications and air embolism may contribute towards this risk. To test this hypothesis, transcranial doppler ultrasonography was used to monitor the presence of air emboli in the middle cerebral arteries of 7 patients undergoing cerebral angiography. Doppler signals consistent with numerous air emboli were noted during each injection of radiographic contrast. This phenomenon was studied further in sheep. Radiographic contrast medium was injected into the carotid artery while a major carotid branch was insonated transorbitally. Embolic signals similar to those seen in patients were noted. Air was introduced at two points. First, at the time of drawing up the contrast into the syringe, especially with more viscous media. Standing the media before injection resulted in a highly significant reduction of air embolism, reducing the total mean duration of emboli from 1.32 (SD 0.60) s after immediate injection to 0.04 (0.05) s after ten minutes standing for iohexol 340 mg/mL (p < 0.001). Second, air was introduced at the time of injection, possibly by the formation of cavitation bubbles under pressure. This occurred most prominently with the less viscous contrast media and with saline, and was significantly reduced by slow injection (mean duration of emboli for saline 2.85 [2.43] s with fast injection compared with 0.32 [0.37] s with slow injection, p = 0.004). Air embolism may contribute towards neurological dysfunction after angiography. Measures should be taken to reduce this by allowing contrast media to stand prior to injection, and by flushing catheters with saline injected slowly.

Adult↗
PubMed1993

Infrapopliteal angioplasty for limb salvage.

Fourteen infrapopliteal angioplasties were performed in 13 patients with critical limb ischaemia. Clinical indications were rest pain, ulceration, gangrene or a critically ischaemic limb from a graft occlusion secondary to an infrapopliteal lesion. The average ankle-brachial ratio was 0.22 in non-diabetics. Technical success was achieved in all lesions with an average increase of Doppler ratios of 0.5. Of the 13 patients, 11 (85%) showed early clinical improvement (with average length of follow-up of 8 months, range 1-18 months). With the introduction of smaller lower profile catheters, hydrophilic and steerable wires and the advent of digital subtraction angiography, infrapopliteal angioplasty can now be performed successfully and with few complications. The presence of spasm should be aggressively treated with intra-arterial nitroglycerin or verapamil.

Aged↗
PubMed1993

PTFE bypass grafting to isolated popliteal segments in critical limb ischaemia.

Although the quality of the distal run-off has been considered as an important factor affecting the success of bypass grafting, reasonable results have nevertheless been reported for bypass grafts to a popliteal artery with no direct communication with the tibial or peroneal vessels (isolated popliteal segment, IPS). The use of autogenous vein has produced the best results in this situation with most authors finding polytetrafluoroethylene (PTFE) less satisfactory. Improved results have nevertheless been shown for femoropopliteal and femorotibial PTFE grafts by the incorporation of vein patches into the anastomoses. In this paper, the influence of this technique on the patency of PTFE grafts to IPS is evaluated. Thirty-three PTFE grafts to an IPS and 67 to the below knee (BK) popliteal artery with one or more run-off vessels were studied. All IPS grafts were carried out for limb salvage and in the BK popliteal group, 46 (69%) were for limb salvage and 21 (31%) were for severe claudication. Groups were matched in terms of age, smoking history and prevalence of diabetes mellitus. Cumulative patency rates of 84% at 1 year and 76% at 3 years were achieved in the IPS group compared to 90 and 81% for the BK popliteal group with one or more run-off vessels. Using the Taylor patch technique, comparable 3 year patency rates can be expected for PTFE grafts to IPSs and to BK popliteal arteries with patient tibial or peroneal run-off.

Aged↗
PubMed1993

Computerized detection of cerebral emboli and discrimination from artifact using Doppler ultrasound.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasound can detect circulating cerebral emboli. Monitoring of patients with potential embolic sources may allow identification of high-risk patients who can then be selected for prophylactic treatment. However, practical patient monitoring will require automated programs that can detect emboli and differentiate them from artifact. METHODS: A new off-line algorithm for the detection of emboli, which detects the characteristic relative power increase occurring with an embolus, was evaluated in both an animal model and in patients. (1) In a sheep model, solid embolic materials (thrombus, platelet aggregates, and atheroma) were introduced into the proximal carotid artery while the distal carotid artery or a major branch was insonated. The signals resulting from 77 emboli (mean size, 1.77 mm) were studied and compared with the Doppler signals resulting from artifact. (2) In patients, 100 embolic signals occurring in three patients were analyzed and compared with signals associated with artifact in the same patients. RESULTS: (1) In the sheep model, emboli resulted in a short-duration, high-intensity signal, but intensity increase alone did not distinguish between emboli and artifact. In contrast, the algorithm discriminated embolus from artifact with a sensitivity of 98.7% and a specificity of 98.0%. (2) In patient studies, embolic signals were differentiated from artifact with a sensitivity of 97.2% and a specificity of 97.0% by the algorithm. CONCLUSIONS: Using such an algorithm, detection of cerebral emboli and discrimination from artifact are possible with a high sensitivity and specificity. Incorporation of such an algorithm into an on-line system should make prolonged patient monitoring practical.

Algorithms↗