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Biomedical subjects

J Mühling

Publications and source records attributed to J Mühling.

At least 91 records · Page 5Linked to original sources
PubMed1998

[Results of surgical therapy of orbital abnormalities].

Dystopies of the bony orbit are caused mainly by craniosynostosis, facial clefts and encephaloceles. This article presents the results of the surgical correction of orbital hypertelorism in 24 patients. Using this operation technique, the bony interorbital distance was decreased from an average of 47.6 mm to 22.8 mm. However, the distance between the soft tissues was not reduced by the same amount as the distance between the bony orbits. The intercanthal distance decreased from an average of 58.5 mm to 44.5 mm, whereby an additional refixation of the medial palpebral ligament resulted in a reduction of the intercanthal distance to 40.8 mm. A strabismus divergens was seen preoperatively in 18 patients, postoperatively only in 8 patients. Four of the latter had to undergo operative correction of the diplopia. We conclude that the operative technique is not reserved only for complex cases of hypertelorism because it shows satisfactory functional and aesthetic results with a low complication rate.

Adolescent↗
PubMed1998

[Acute kidney failure. Non-invasive diagnosis of acute kidney failure in operative intensive care patients].

UNLABELLED: Acute renal failure is a common and severe complication in ICU. Renal laboratory examinations like creatinine and urea are late signs of renal dysfunction: Most of the functional abilities are reduced and there is no time for therapeutical interventions. The aim of this study was to find some earlier sensitive parameters of renal dysfunction and the order of appearance, the cause of acute renal failure and the value of the measured parameters. METHODS: After agreement of the local ethic committee, 21 patients of the ICU were investigated. They were divided into two groups: 1st (n = 14) with no signs of renal dysfunction and were regarded as control group and 2nd (n = 7) were examined until the beginning of acute renal failure. For five days the glomerular filtration rate, proteinuria (immunoglobulin G, Tamm-Horsfall protein, alpha-1- and beta-2 microglobulin, lysozyme), the brush border enzymes angiotensinase A and the lysosomal enzyme N-acetyl-beta-d-glucosaminidase were daily measured and compared with clinical standards like the excretion of albumin, the clearances of creatinine and urea and the fractional excretion of sodium. RESULTS: Both groups were comparable with respect to drug therapy, APACHE-II-score (with the exception of the last day before ARF), and infusion therapy. There were differences in tubular functions between the 2 groups. Patients developing renal insufficiency showed an increased excretion of alpha-1-microglobulin, and decreased excretions of Tamm-Horsfall-protein, angiotensinase A as well as a low renal blood flow. Significant differences were also detectable in glomerular functions (glomerular filtration rate), albumin, and immunoglobulin G. DISCUSSION: Only a short time interval (1 to 2 days) between tubular and glomerular damage were detectable in patients with renal insufficiency. Renal failure must be due to circulatory problems because of the nearly simultaneous increase of tubular and glomerular parameters after RPF decreased. The parameters alpha 1-microglobulin, angiotensinase A and Tamm-Horsfall-protein gave early indications for the acute renal failure. They showed satisfactory sensitivity and specificity, but the positive predictive value was poor.

Acute Disease↗
PubMed1998

[Odontogenic focus as the etiology of cerebral ischemia].

Recent studies have shown that acute infections, especially of the respiratory tract, are an important risk factor for cerebral ischemia. Additionally we know that chronic dental infections may be a risk for myocardial infarction and artherosclerosis. However, the connection between stroke and dental infections has hardly been examined so far. Therefore we performed a case-control study using a standardized questionaire and examination. We investigated 66 patients consecutive to a acute cerebral ischemia/stroke and 60 age- and sex-matched nonstroke neurological patients as a control group. Dental status was determined by a so called total dental index (TDI) which reflects primarily caries, periodontitis, periapical lesions, devital and missing teeth as well as by a panoramic index (PI). Specifically, older patients with cerebrovascular ischemia tended to have a significantly worse dental status and had more severe periodontitis and periapical lesions than control subjects. A predefined poor dental status was associated with cerebrovascular ischemia independent from other vascular risk factors and social status. In conclusion, poor dental health, mainly resulting from chronic dental infections, may be associated with an increased risk for cerebrovascular ischemia. The results must now be verified in larger studies. As chronic dental infections are a common and also easily treatable factor, their identification as a risk factor for stroke would be quite important in the field of preventive medicine.

Adult↗
PubMed1998

Treatment of oral leukoplakia by topical application of 5-aminolevulinic acid.

A new therapy for the treatment of oral leukoplakia by 5-aminolevulinic acid (ALA) and photodynamic therapy (PDT) is presented. ALA, a precursor in the biosynthesis of haeme, induces the production of the endogenous photosensitizer protoporphyrin IX which can be used for PDT. Twelve patients, who had been suffering from leukoplakia of the oral mucosa for several years, were treated by ALA-mediated PDT. ALA was used as a topical photosensitizer and 20% ALA cream was applied to the leukoplakia lesion of the oral mucosa for two hours and then light activated at 630 nm, 100 mW/cm2 and 100 J/cm2. Five patients showed complete response to the treatment, four patients showed a partial response and in three patients treatment was unsuccessful. One patient with partial response was retreated, after which the lesion disappeared.

Administration, Topical↗
PubMed1998

Preoperative planning and intraoperative navigation in skull base surgery.

Experience with the commercially available, 3-D navigation systems Viewing Wand (ISG, Mississauga, Ontario, Canada) and SPOCS (Aesculap, Germany) in skull base surgery is presented. Having meanwhile been tested in over 60 clinical trials, the systems achieved an accuracy of < or = 2.7 mm which, at the moment, we deem sufficiently acceptable to proceed with their clinical evaluation. There was no difference in intraoperative accuracy between the mechanical and the optical navigation systems. The systems proved to be very helpful in identifying the extent of the tumours and in visualizing the proximity of vital structures. 3-D-planning, simulation and intraoperative navigation especially facilitates surgery in anatomically complicated situations, without risk of damaging neighbouring structures. The SPOCS (Surgical Planning and Orientation Computer System) revealed a considerably improved flexibility in handling and a better integration into the surgical procedure in comparison with the relatively inflexible and space-demanding Viewing Wand arm. Especially, the 'offset' function of the SPOCS offers the possibility of a virtual elongation of the instrument and thus, in combination with the on-line visualization of the corresponding images, of a 'look ahead' operation. By using computer-assisted simulation and navigation systems, we can expect quality improvement and risk reduction. More extensive and radical interventions seem possible.

Computer Simulation↗
PubMed1998

Heterogeneity of myocardial edema in isolated pig hearts after perfusion with different types of cardioprotective solutions.

The extent and distribution of myocardial edema induced by perfusion with cardioprotective solutions is of great interest. Domestic pig hearts (n = 12) were perfused in situ after aortic cross clamping either with Bretschneider's cardioplegic solution (HTK, 4 degrees C, n = 3), with a heparinized Krebs-Henseleit solution containing 30 mmol/L 2,3 Butanedionemonoxime (BDM, 4 degrees C, n = 3) or with heparinized pig blood (HPB, 24 degrees C, n = 3). After a three-hours storage period, magnetic resonance tomography (MRI) was carried out. The acquired T1-weighted data were used for the subsequent three-dimensional reconstruction based on the "Heidelberg ray-tracing technique". The small myocardial tissue blocks (n = 216) were excised from these hearts for dry weight measurements for 9 preselected regions in duplicate including ventricular papillary muscle, ventricular free wall, ventricular septum, apex, and atrial tissue. In control hearts (n = 3), dry weight was measured immediately after explantation (no MRI). The results of dry-weight measurements and three dimensional visualization were compared. Dry-weight measurements revealed that considerable myocardial edema is induced by any of the experimental procedures. The effects were most pronounced after BDM perfusion. Regardless how the edema was induced, there were significant differences of the water content within the heart: the water content in the heads of the papillary muscles and in the interventricular septum was always smaller than that of the free left- and right-ventricular walls. The heterogeneity of myocardial edema and its spatial distribution pattern could be qualitatively visualized. The experimental data (biophysical data and 3D visualization) clearly show a heterogeneity of myocardial edema induced by different types of cardioprotective solutions. As the presence of myocardial edema represents one of the crucial events in the pathophysiology of myocardial dysfunction occurring during myocardial infarction, ischemia, heart transplantation, and extracorporeal circulation, the present study represents an interesting contribution towards intravital detection and distribution of myocardial edema.

Animals↗
PubMed1998

CT-based 3D-planning for dental implantology.

A system for 3D-planning for dental implantology is described. Since exact knowledge of the position of the nervus alv. inf. is critical, we present an algorithm for automated detection of this nerve, which requires only very little initial user interaction. To allow interactive implant placement on comparatively low-cost pc hardware we developed hybrid visualization techniques, which refrain from using large texture memory and raster engines.

Algorithms↗
PubMed1997

[Robotics in oral and maxillofacial surgery. Possibilities, chances, risks].

Robot systems are being tested in stereotactic neurosurgical interventions, orthopedic surgery of the hip or knee and advancal endoscopic systems for minimally invasive surgery. In contrast to most industrially manufactured products, objects for medical treatment are characterized by plasticity as well as by complex and individual forms. Thus, features of robots in this field have to be further developed in terms of advanced sensory and specific micromotoric systems. Safety and cooperation between surgeon and robot on the patient in the operating room have to be guaranteed. Extensive three-dimensional diagnosis, computer-aided planning and simulation of the intervention as well as sensory systems that monitor the actual performance of the operation are mandatory parts of this concept. In our interdisciplinary study, we aim to examine whether a robot-given a complete preoperative planning and simulation procedure-is able to perform certain surgical operations more precisely than the surgeon. Examples are drilling with depth control, shaping of bone surface by milling, sawing with defined depth in cranial osteotomies, defined preparation of implant sites and the positioning and insertion of dental and other surgical implants, whereby autonomous employment of the robot is not that which is aspired to in these interventions but rather the interactive support of the surgeon.

Humans↗
PubMed1997

[Perfusion changes in hemodilution. The effect of extensive isovolemic hemodilution with gelatin and hydroxyethylstarch solutions on cerebral blood flow velocity and cutaneous microcirculation in humans].

OBJECTIVE: Quantifying the influence of extreme isovolemic hemodilution (NH) with different colloids on cerebral blood flow velocities (transcranial Doppler sonography) and cutaneous microcirculatory blood flow (laser Doppler flowmetry) in healthy, non-premedicated volunteers was the aim of this study. METHODS: In seven volunteers (randomized cross-over design) 20 ml/kg blood was withdrawn within 30 min and simultaneously replaced with 6% hydroxyethyl starch (200,000/0.5, HES) or 3% gelatin (GEL). Thirty minutes later, the autologous blood was retransfused (RT) within 30 min. Due to a severe allergic reaction to gelatin in one volunteer, only 6 GEL-NH were evaluated. Recorded parameters were: mean blood flow velocities (Vm-MCA) as well as the pulsatility index (PI) and the resistance index (RI) over the middle cerebral artery. In addition laser Doppler flux (FLUX), cell velocity (SPEED), mean arterial pressure (MAP), heart rate (HR), hemoglobin (Hb) and hematocrit (Hc) were monitored. RESULTS: NH resulted in a withdrawal volume of 1498 +/- 85 ml (HES) and 1493 +/- 95 ml (GEL), (mean +/- SD) and induced a decrease in hemoglobin from 40.9 to 29.0% (HES) and from 39.8 to 30.0% (GEL). RT increased Hc to 34.2% (HES) and 34.5% (GEL). MAP and HR showed no significant alterations in both groups. Following NH, Vm-MCA rose almost the same way in either case (26% HES), 21% (GEL), but decreased continuously again during RT. After completing RT, only in the HES group Vm-MCA still remained higher than baseline values (14% HES, only 3% GEL). Similar inverse regression lines were found for the two groups between Hc and Vm-MCA: [Vm-MCAHES (cm/s) = -1.27 x Hc + 110.9; r = 0.98, P < 0.001 and Vm-MCAGEL (cm/s) = -1.32 x Hc + 110.9; r = 0.91, P < 0.001]. Furthermore, as a result of NH, FLUX and SPEED increased about 61% and 38% in the HES group and remained on higher values in comparison with starting positions (21% FLUX, 13% SPEED). However, the results in the GEL group were of a different kind: FLUX and SPEED increased stupendously to 291% and 114% combined with NH, but both were reduced by RT on a large scale (39 and 27% below baseline values). Whereas RI showed no group differences, there was a remarkable drop in PI during RT (17% HES, 12% GEL). CONCLUSION: The two plasma expanders studied show a close inverse correlation between the alterations of blood flow velocities in the middle cerebral artery and systemic hemoglobin and hematocrit values. In both groups the change in blood flow velocities is comparable. For the first time the results of relative changes in blood flow velocities following hemodilution and retransfusion in healthy volunteers are described that correspond closely by relative cerebral blood flow alterations found in animal studies as well. Moreover, a non-linear correlation of cutaneous microcirculation was shown by means of HES, but also by GEL. Obviously, there was the GEL group to be responsible for pronounced differences in cutaneous circulation.

Adult↗
PubMed1997

[Effect of hydroxyethyl starch solution on kidney function in surgical intensive care patients].

Hydroxyethyl starch is commonly used in resuscitation, anaesthesia and intensive care medicine. Increasing creatinine values in patients treated with hydroxyethyl starch have been described in some case reports. These have also been some clinical signs such as pain in the renal region, and swelling of kidney parenchyma, but no differential and sensitive parameters of renal function have supported these possible side effects of hydroxyethyl starch. Twenty-five patients were randomly allocated to a control and a treatment group. In the treatment group, patients received 12 ml per kg body-weight hydroxyethyl starch 10% (200/0.5) daily. A non-invasive diagnostic spectrum of renal function was performed. Specific tubular proteins (alpha 1-microglobulin, Tamm-Horsfall protein), glomerular parameters (immunoglobulin G, albumin), and the brush border enzyme acetyl-beta-glucosaminidase, were examined. Additionally, renal blood flow and glomerular filtration rate, Apache-II-score, breathing therapy, infusions, transfusion, and all medical interventions were documented. Both groups were comparable with regard to drug therapy. Apache-II-score, and fluid management. There were differences in tubular function between the two groups. Patients undergoing HES therapy showed increased excretion of alpha 1-microglobulin. Tamm-Horsfall-protein and of brush border enzyme acetyl-beta-glucosaminidase. No significant differences were detectable in glomerular functions (glomerular filtration rate, renal blood flow), albumin, and IgG. Correlates of tubular damage after hydroxyethyl starch therapy were seen in intensive care patients. Many influences of intensive therapy act on renal function, and further studies with larger cohorts are necessary. With regard to the documented localisation of the tubular damage in the HES group, colloid therapy with hydroxyethyl starch in renal dysfunction should be monitored carefully by means of sensitive markers.

Acute Kidney Injury↗
PubMed1997

Early maxillary orthopedics in a child with an oblique facial cleft.

OBJECTIVE: Oblique facial clefts are extremely rare. In view of their variability, surgical treatment cannot be standardized. To date, early maxillary orthopedics in the treatment of oblique facial clefts have not been reported. The case described here presents a newborn child with a Tessier 3 cleft. Because of the enormous width of the alveolar cleft, a narrowing of the segments was regarded as prerequisite for definitive lip closure. To bring the segments together, an actively working plate with a forward pull was designed. CONCLUSION: After a period of 4 weeks, proper alignment and proximity of the segments were achieved, so that definitive lip closure and plastic reconstruction of the remaining soft tissue defect could be easier performed.

Abnormalities, Multiple↗
PubMed1997

[Outcome of profile-improving operations in craniofacial abnormalities].

In 52 children with craniosynostosis, we studied the effect of fronto-orbital advancement onto the forehead profile and the growth tendency of the forehead and midface. As a reference, the following kephalometric data were used: SN line. N-Spna line, SNA angle, N-tf line (as an indicator of the forehead profile) and the tf-TF line (as an indicator of the forehead size). The operation was carried out at an mean age of 10.5 months. Follow-up with X-ray control covered a period of 37.2 months on average. In patients with brachycephalus the SNA line was reduced and the post-operative growth tendency was the most unfavorable. Also the forehead profile (N-tf-line) did not become normal after the operation in patients with brachycephalus. Besides this, the increase in the forehead size indicated a new growth-tendency disorder. In all children with brachycephalus as well as in most children with oxycephalic growth tendency, sagittal midface growth was inhibited (NSA angle) while vertical midface growth was normal (N-Spna line). The success of fronto-orbital advancement was dependent on the kind of growth disorder, the location, and the age when the operation was carried out. Only early operative treatment could interrupt the pathological growth tendency even in cases with a major development disorder.

Cephalometry↗
PubMed1996

Craniofacial growth characteristics after bilateral fronto-orbital advancement in children with premature craniosynostosis.

The standardized bilateral fronto-orbital advanced method of osteotomy established at the University of Wuerzburg is applied in all forms of craniosynostosis except scaphocephalus. The intention behind early operation is to halt progression of the disorder and to institute the physiological direction that growth should take. The preoperative severity of the disorder, the particular symptoms of the various malformations concerned, and the postoperative course of growth were analyzed and assessed both clinically and cephalometrically using the retrospective evaluations of the file data of 131 children with various forms of craniosynostosis. In contrast to linear craniectomy and so-called lateral canthal advancement, which have sometimes been thought to lead to undesirable postoperative growth development, only 11 relapses requiring renewed operation were found postoperatively in our own study of 131 children. It became evident that the greater the severity of the malformation, the more probable it was that a relapse would occur. Fronto-orbital advancement can only affect the pathological growth pattern to a limited degree, especially when craniosynostosis is related to a syndrome. Cephalometric evaluation confirmed the limited potential for growth in the area of the anterior skull base and in the mid-face in the presence of syndrome-related brachycephaly and severe facio-craniosynostoses. In such clinical cases, compensatory growth of maxillary hypoplasia cannot be expected after fronto-orbital advancement.

Cephalometry↗
PubMed1996

Volume replacement with gelatin or hydroxyethylstarch solutions does not impair somatosensory evoked potential monitoring: a haemodilution study in conscious volunteers.

The influence of haemodilution with colloids on somatosensory evoked potentials in non-premedicated volunteers is reported. In seven volunteers (randomized crossover design), blood (20 mL kg-1 within 30 min) was removed and simultaneously replaced by gelatin 3% or hydroxyethylstarch 6%. After 30 min, blood was retransfused within 30 min. Median and posterior tibial nerve somatosensory evoked potentials were recorded from the cortex, second cervical vertebra, Erb's point and 1st lumbar vertebra, respectively. One volunteer experienced a severe allergic reaction to gelatin, therefore only six gelatin trials were evaluated. Haemodilution decreased the haematocrit from 39.8 +/- 1.6% (mean +/- SD) to 31.1 +/- 2.0% (gelatin) and from 40.7 +/- 1.7% to 29.8 +/- 1.5 % (hydroxyethylstarch), respectively. Retransfusion increased haematocrit to 34.4 +/- 0.9% (gelatin) and to 34.2 +/- 1.3% (hydroxyethylstarch). Neither haemodilution with gelatin nor haemodilution with hydroxyethylstarch or retransfusion influenced evoked potentials. In conclusion, the treatment of blood loss up to 30% of estimated blood volume with gelatin or hydroxyethylstarch will not affect somatosensory evoked potential monitoring provided normovolaemic conditions are maintained.

Adult↗
PubMed1996

[Effects of different kinds of ventilation and positioning measures on blood flow velocity in the middle cerebral artery].

OBJECTIVE: Aim of the present study was to quantify the influence of varying respiratory parameters and different body positionings on transcranial Doppler sonography (TCD) values. With the approval of the local ethics committee, 34 patients without neurological deficits scheduled for an operation in supine position (n = 15) and in the so-called "rabbit-position" (RP, n = 19) were chosen for a prospective randomised investigation. METHODS: Prior to induction of anaesthesia, during the study and after extubation, the systolic (Vs), diastolic (Vd) and mean (Vm) of blood flow velocities as well as pulsatility (Vs - Vd)/Vm of the middle cerebral artery were determined by TCD. In addition mean arterial pressure and heart rate were monitored. Pulmonary airway pressures were observed during anaesthesia and CO2-partial pressure and central venous pressure (CVP) were determined by central venous line and blood samples. Anaesthesia was initiated with 5 mg/kg thiopental and continued with 0.8-1.2 vol% isoflurane in N2O/O2 = 2:1. After positioning all variables were recorded at 10-minute intervals with an inspiratory:exspiratory (I:E) ratio of 1:2, positive endexspiratory pressures (PEEP) of 0 and 10 cm H2O and an I:E ratio of 1:1 with 0 and 10 cm H2O PEEP. The respirator was adjusted to maintain an endtidal pCO2 of 40 mmHg. RESULTS: Neither different positioning of the patients, nor the alteration of respiratory parameters affected TCD variables in a significant way. No significant alterations were detected between the two groups of patients. Rising PEEP resulted in a minor but significant increase in CVP by an average of 3 cm H2O in both groups. The respective positions produced different respiratory pressures. These were in the "RP-group", with and without PEEP, at an approximately 5 cm H2O higher level. All other parameters did not vary significantly. CONCLUSION: The findings of this study show that a positioning of patients in a so-called "rabbit position" during anaesthesia does not alter the rate of blood flow velocity in the middle cerebral artery. Moreover, the modification of important respiratory parameters, especially a rise of PEEP to 10 cm H2O, had no significant influence on TCD values.

Adult↗
PubMed1996

Isovolaemic haemodilution with hydroxyethylstarch has no effect on somatosensory evoked potentials in healthy volunteers.

BACKGROUND: An animal study in anaesthetized baboons demonstrated that somatosensory evoked potentials (SSEP) can be affected by extreme haemodilution. This might lead to misinterpretation and reduce the value of intraoperative SSEP monitoring when colloids are administered. In the present study, the effect of haemodilution (HD) and subsequent retransfusion of autologous blood on SSEP was determined in healthy non-premedicated volunteers. METHOD: Acute isovolaemic HD served as a model for blood loss immediately replaced with colloids. In 12 volunteers, 20 ml/kg.bw blood was withdrawn within 30 minutes and simultaneously multaneously replaced with 6% hydroxyethylstarch (HES). 30 minutes later, the autologous blood was retransfused within 30 minutes. Recording sites and parameters were: 1. Median nerve SSEP: cortical, cervical (C2), Erb's point; 2. Posterior tibial nerve SSEP: cortical, cervical (C2), lumbar (L1). In addition to SSEP latency and amplitude, median and tibial nerve central conduction times, spinal conduction time and nerve conduction velocity were determined. Serial SSEP measurements were made before, during and after HD and retransfusion every 15 minutes. RESULTS: HD consisting of a withdrawal volume of 1550 +/- 155 ml (mean +/- SD) induced a decrease in haematocrit from 42.0 +/- 3.1% to 29.6 +/- 1.6% (P < 0.001). Following retransfusion, haematocrit increased to 35.0 +/- 2.1% (P < 0.001). Neither HD nor retransfusion influenced SSEP parameters. CONCLUSION: We conclude from our data that the therapy of blood loss up to 30% of estimated blood volume with HES does not affect SSEP monitoring as long as normovolaemia is maintained.

Adult↗