Biomedical subjects

K Kehl

Publications and source records attributed to K Kehl.

At least 19 recordsLinked to original sources

PubMed2005

Monitor position in laparoscopic surgery.

BACKGROUND: One of the key problems in laparoscopy is the ergonomic positioning of the monitor. In this study we tested task performance and muscle strain of subjects in relation to monitor position during laparoscopic surgery. METHODS: Eighteen subjects simulated laparoscopic suturing by threading tiny pearls with a curved needle. This was repeated in three monitor positions (15 min each): frontal at eye level (A), frontal in height of the operating field (B), and 45 degrees to the right side at eye level (C). Subjects were not allowed to turn their heads during these sessions. After the test they were asked for their preferred monitor position. During all tests the electromyographic (EMG) activity of the main neck muscles was recorded and the number of pearls was counted. RESULTS: The EMG activity was significantly lower for position A compared to positions C and B (p < 0.05). No significant difference was found between positions B and C. The number of threaded pearls as an indicator for task performance was highest for position B. The difference was statistically significant compared to position C (p = 0.0008) but not between positions A and C (p = 0.0508) or A and B (p = 0.0575). When asked for the preferred monitor position, nine subjects chose two monitors in the frontal positions A and B. No subject preferred the monitor at the side position (C). CONCLUSION: Regarding EMG data, the monitor positioned frontal at eye level is preferable. Reflecting personal preferences of subjects and task performance, it should be of advantage to place two monitors in front of the surgeon: one in position A for lowest neck strain and the other in position B for difficult tasks with optimal task performance. The monitor position at the side is not advisable.

Computer Terminals↗

PubMed1996

[Transcranial Doppler ultrasound as monitoring during carotid operation].

We describe our method of transcranial Doppler (TCD) monitoring during carotid endarterectomy (CE) procedures. During a period of 35 months we performed 257 CE with TCD monitoring. Critical flow values during crossclamping of the internal carotid artery (ICA) and the necessity of insertion of an intraluminal shunt were taken in consideration with regard to the choice of surgical procedure: TEA (with or without patching) or eversion endarterectomy. The critical flow values were around 10-15 cm/s, no pulsatility signs were detected. Further advantages of the TCD monitoring are: detection of microemboli, control of the potential collateralisation of the external carotid artery and the control of efficacy and accurate positioning of the intraluminal shunt. We comment our results of cerebral monitoring and consider it as a useful tool for optimizing the postoperative results of carotid surgery.

Aged↗

PubMed1991

[Necrosis-Q in the mapping ECG].

In this study 57 test persons 15 healthy ones, 42 patients with myocardial infarction with disturbances of the wall excursion) were examined by means of the mapping ECG, the classical ECG and the echocardiography. Considering the healthy test persons the normal values of the Q-deflections were established for every individual lead of the mapping ECG and of this the borderline values for the necrosis-Q (Q less than Q(m-1 s] were derived. The topographic coordination was performed with the help of a computer-aided picture of the thoracic surface. The determination of the localization of an echocardiographically proved disturbance of the wall excursion by means of the mapping ECG on the basis of the borderline values stated for the Q-deflections was carried out with an efficiency of 0.810 and by means of the classical ECG with an efficiency of 0.690. The information of the Q-deflections in the mapping ECG about the presence of an echocardiographically provable disturbance of the wall excursion is possible with an efficiency of 0.833. For the diagnosis of an infarction all infarction-typical parameters should always be used simultaneously. The clinical significance of the diagnostics of myocardial infarction by means of the mapping ECG lies in the exact localisation, the gradual valuation of the size of the infarction, in the recognition of changed potential distribution pattern as sign of the activity of a coronary heart disease with the complication of a myocardial infarction and the establishment of smaller as well as nontransmural myocardial infarctions with non-invasive methods.

Diagnosis, Computer-Assisted↗

PubMed1990

[Mini-mapping ECG].

63 patients with clearly defined myocardial infarction and an echocardiographically evident akinesia and hypokinesia, respectively, were examined by means of the echocardiography, the conventional ECG (12 leads) and the classical mapping ECG (69 leads). From the latter a mini-mapping ECG (12 chest electrodes) was led. IN 20% of the cases we did not find an accordance between the classical mapping ECG and the mini-mapping ECG in the localization of an echocardiographically proved disturbance of the excursion of the heart wall. In these cases small circumscribed myocardial lesions were concerned which were located particularly postero-inferiorly, the proof of which restricted itself to a thoracic surface less than 54-108 cm2 in the classical mapping ECG. But in larger lesions of the myocardium already the conventional ECG shows correct diagnostic statements. The coordination of the myocardial infarctions to the individual parts of the heart can be performed on the basis of a topographic mapping ECG card. A quantitative estimation of the electrocardiographic findings is not possible with the mini-mapping-ECG. The diagnostic valency of the mini-mapping-ECG is to be arranged only in the third place after the classical mapping ECG and the conventional ECG!

Coronary Disease↗

PubMed1990

[Gradual evaluation of repolarization disorders with ECG mapping].

143 test persons, (31 healthy persons, 30 borderline cases and 82 patients with chronic coronary heart disease) were examined at rest and on submaximal exertion by means of a mapping ECG (72 electrodes) and their findings were valuated depending upon the severity of the chronic coronary heart disease. The significance of the individual mapping ECG parameters in gradually valuating the disturbances of repolarisation was stated by correlation to the severity of the chronic heart disease and decreased in following order: 1. relative surfaces, 2. total surface with ST decrease in mV, 3. maximum decrease of ST, 4.4. sum of the decrease of ST in mV, 5. sum of negative area integrals of ST and 6. the minimum quotient of increase. The extension of a myocardial ischaemia could be stated with the total area by means of decreases of ST and its maximum by means of the maximal decrease of ST. The severity of the coronary heart disease could be gradually estimated with the "relative surfaces" of the mapping ECG at rest in mild to moderate degrees of severity and under submaximal exertion in all degrees of severity of the coronary heart disease. In a gradual evaluation of the mapping ECG the extension, the intensity, localisation and kind of the disturbance of the myocardium must be considered with regard to the dipole behaviour and to the potential decrease of the cardioelectric field as well as to the degree of severity of the disease.

Coronary Disease↗

PubMed1985

[Comparison between classical ECG and ST mapping].

In a group of patients with chronic ischaemic heart disease whose diagnoses were ascertained by the clinic, by the electrocardiogram after resting and after work, by the coronarography and/or by the complication of the ischaemic heart disease (myocardial infarction), we compared the findings of the classical ECG with those ones of the ST-mapping. In 32% the ST-mapping brought an increased evidence. A correspondence of 100% we found in the certainly normal and certainly pathological findings. The maxima of the repolarisation disturbances withdrew from the proof of the Wilson derivations at rest at 54.8% and under submaximal strain at 79.3%, changed in 25.8% their position under load and during the load the emigrated in 16.5% out of the precordial leads after Wilson. The evaluated sums of the partial surfaces of the ST-mapping have a higher correlation to the severity of the ischaemic heart disease, permit a better differentiation between the individual degress of severity and render possible an exacter judgment of the prephase of the ischaemic heart disease than it is possible with the usual ECG. In 25.8% of all examinations after work repolarisation disturbances limited to small myocardiac areas could be proved only by means of the mapping. The localisation of lesions of the myocardium is better possible by means of the ST-mapping above all dorsally/caudally than by means of the classical ECG.

Arrhythmias, Cardiac↗

PubMed1977