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PubMed1994

[Pathogenesis and treatment of accommodative disturbance].

Using a computer-assisted infrared optometer with a pupillograph, we tried to obtain basic understanding of accommodative disturbance and its by investigating tonic (dark focus) level of accommodation and quasi-static accommodative response. In normal volunteers in whom either visual fatigue, general fatigue, or drunkeness was loaded intentionally, myopic shift of refraction, increased refractive fluctuation, and miosis were induced in all cases but the effect on amplitude of accommodative response was minimal. Subjects that worked at a computer terminal all day for 2 years, but not controls, developed myopic change at a statistically significant level. The effect on tonic level of accommodation of subject age, sustained near-vision tasks, and topical application of autonomic-related drugs was investigated. In subjects with severe eyestrain, myopic shift of tonic accommodation and prominent pupillary unrest were observed, suggesting increased parasympathetic excitation. One patient who was accidentally exposed to diisopropyl fluorophosphate, a potent cholinesterase inhibitor, showed a phenomenon similar to that mentioned above. Chaos attractors based upon the Shil'nikov phenomenon were introduced for evaluation of microfluctuation and pupillary unrest, as first applied by Sumida et al. Topical application of low-dose cyclopentolate hydrochloride was effective for treating accommodative abnormality in professional computed workers, who sometimes develop abnormal parasympathetic excitation. Based on quasi-static accommodation measurements, accommodative abnormality after head and neck injury, including whiplash injury, was divided into two completely different states: accommodative spasm and palsy. Since quasi-static accommodation was greatly affected by satellite ganglion block, sympathetic innervation from cervical ganglions may strongly influence accommodative response. Hyperthyroidism, which may be accompanied by sympathetic hyper-excitation, showed diminished accommodative response. In patients after refractive surgery by excimer laser, there was no difference in accommodative response before and after surgery, although tonic accommodation was slightly unstable after surgery. These findings suggest that the evaluation of tonic level or a similar state of accommodation and pupillary unrest will yield extremely valuable information in regard to various accommodative disturbances.

Accommodation, Ocular↗
PubMed1994

[Follow-up of fracture healing--indications and clinical relevance of direct radiographic magnification in comparison with conventional roentgen imaging].

Comparison of 83 magnification radiographs with corresponding conventional X-rays showed that direct radiographic magnification (DIMA) yielded additional information in 39 cases (47%), which had implications for the treatment in 19 cases (22.9%). In 11 cases callus was first visualized in magnification radiography; the earliest evidence of callus was found 14 days after surgery. Since magnification radiography means the region that can be examined is smaller, conventional radiographs were necessary in 32.5% of cases to find the position of the fracture in long bones. For statistical evaluation interobserver analysis was performed, anatomical and pathological structures being graded according to four levels. Magnification radiography proved superior in all structures examined. Magnification radiography can be recommended as an additional method to monitor fracture healing. Computed radiography was used together with magnification radiography to reduce the radiation dose and to perform image processing including simulation of conventional technique and edge enhancement. DIMA is a valuable tool in the evaluation of fracture stability and in the adjustment of distraction rates in limb-lengthening procedures.

Adult↗
PubMed1994

Craniosynostosis: diagnostic imaging with three-dimensional CT presentation.

PURPOSE: To measure diagnostic performance and preference of two three-dimensional CT reconstruction modalities (voxel-gradient and surface-projection) displayed two ways (conventional and unwrapped) in craniosynostosis confirmed by surgical inspection and histologic analysis of resected sutures. METHODS: High-resolution 2-mm contiguous CT sections were obtained and three-dimensional reconstruction images generated for 25 infants and children with skull deformities before surgical treatment of craniosynostosis. Two pediatric radiologists and two neuroradiologists first ranked images by their own preferences for diagnostic use. Then they diagnosed craniosynostosis from images presented in random order and blinded. The standard of reference was inspection during surgery and histologic evaluation of excised sutures. Finally, reviewers repeated their subjective preference tests. RESULTS: The least experienced radiologist had 100% sensitivity for all imaging modalities and specificities ranging from 43% to 83%. The two most experienced radiologists performed nearly identically, with sensitivities of 96% and specificities of 100%. After performing diagnostic tasks using all image types, all radiologists preferred conventional surface projections. CONCLUSION: Experienced readers can achieve nearly perfect diagnostic performance using the latest three-dimensional CT reconstruction images, making it a contribution to the diagnostic process. Although performance is nearly identical for all modalities, readers strongly prefer conventionally presented surface-projection images.

Algorithms↗
PubMed1994

[A new methodologic approach for determining right ventricular volumes from transesophageal echocardiography].

In order to develop a concept of right ventricular volume estimation accounting for variance in positioning of the transesophageal transducer, non-linear scale transformations of suitable measurements of areas and perimeters were used in a new modeling-approach. This type of modeling supposes self-similarity of ventricular dimensions, a mathematical concept generalizing the notion of proportionality. In a study using right ventricular casts, we were able to demonstrate the geometry of right ventricles complies with these assumptions. The resulting multivariate power law volume estimators were developed by non-linear data fitting by learning-analyses based upon angiographic reference volumes and two areas derived from non-orthogonal sections using a monoplane transducer in a first series of studies, and two orthogonal areas with corresponding perimeters using a biplane device in a second series. Correction factors for systolic and diastolic volumes were applied. By prospective test-analyses angiographic and TEE-derived volumes were compared to evaluate our volume estimator and good agreement was found. Trend was evaluated by correlation amounts to r = 0.95 (n = 22) in series 1 with monoplane transducer, and r = 0.9 (n = 20) in series 2 with biplane transducer. This approach is of use in monitoring right ventricular function in cases with unsuitable transthoracical windows, e.g., in cardiac surgery postoperatively.

Adult↗
PubMedDate not supplied

[Computer monitoring of hemodynamics during assisted circulation and extracorporeal detoxication in abdominal surgery].

Basic central and regional hemodynamic parameters have been studied using a computer monitoring system in 57 patients with acute abdominal surgical diseases during special extracorporeal procedures. Indications for regional assisted circulation (RAC) as well as regularities in hemodynamic changes during and after procedures have been established. The data of monitoring have shown that RAC and RAC in combination with hemosorption have in most cases a marked favourable effect on abdominal hemodynamics: mesenteric and portal blood flow is increased and consequently total hepatic flow is activated. The flow of portal blood leads to an increase in central venous pressure. Unfavourable tendencies have been established in changes of central hemodynamics during the procedures. They are: calculated intervals of the rates of central venous pressure increment and cardiac output decrement. This made it possible to optimize the use of extracorporeal procedures in patients with such diseases.

Abdomen↗
PubMedDate not supplied

[Documentation and computer-assisted evaluation of basic data in a geriatric clinic].

We analyzed data of our clinic by a computer program for discharge letters developed by us. Structure of patients, types of diseases, and success in rehabilitation were recorded. The average age of our patients was 80 years. The biggest group have been the 80-85 years old ones. Two-thirds have been female. Our department is divided into three sections. Admissions made to the section treating patients with acute diseases were made in two-thirds of the cases from surgeries and in one-third from accidents. The section where patients are rehabilitated received only patients who had been admitted before. Two-thirds of them were suffering from surgical diseases (especially orthopedic/traumatic problems). One-third from medical or neurological diseases--especially stroke. In the section for long-term treatment we transferred patients with chronic diseases, mainly from our own sections for acute care and rehabilitation. Twenty percent came from other departments and other hospitals. Discharge: Fifty-one percent of patients treated in the section for acute care were discharged. More than one-fourth were transferred to the section for long-term treatment. Thirteen percent died. Two-thirds of the rehabilitated patients were discharged home. Sixteen percent were treated long-term; about seven percent died. From our section for long-term treatment one-third of the patients were discharged home. Nineteen percent were discharged to nursing homes or other homes for seniors. Forty-one percent died. Younger patients could more likely be discharged without home nursing care and to a household with other members. More than fifty percent of patients of 80 years and older lived alone and required homecare.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1994

[Orbital volumetry as a planning principle for reconstruction of the orbital wall].

Before reconstruction of the orbital walls and other surgical procedures concerning the orbits leading to a modification of pathologically altered orbital volumes, it is useful to measure these volumes in order to allow preciser correction. Orbital volumetric studies on 22 patients and 6 dry skulls were performed using high resolution computer tomography. 14 patients presented enophthalmos of various origin, 3 patients fibrous dysplasia involving the orbits and 5 patients showed no orbital pathology. In 10 patients with unilateral posttraumatic enophthalmos an increase of the bony orbital volume of 20.1% in the average was found corresponding to an enophthalmos of 3.5 mm in the average. Correlation between the severity of the enophthalmos and the increase in orbital volume was found. Enophthalmos could not be correlated to the intraorbital fat volume, especially no atrophy of orbital fat could be demonstrated in these patients. Normal orbital volume measurements of patients and dry skulls were compared to those found in the literature. Planning of the surgery was therefore facilitated before correction of enophthalmos, reconstruction of bony orbital contour after tumor resection and in patients with fibrous dysplasia. Results suggest that the bony orbital enlargement, followed by a change in soft-tissue shape and position is the usual cause for posttraumatic enophthalmos. Changes in volume of soft-tissues themselves are less significant.

Cephalometry↗
PubMed1993

Clinical performance of a rule-based decision support system for mechanical ventilation of ARDS patients.

We developed a clinical decision support system--ventilation protocols--that managed tidal volume and ventilator rate settings during mechanical ventilation of patients with the Adult Respiratory Distress Syndrome (ARDS). We applied these protocols for a total of 10,903 hours in 40 ARDS patients. The clinical staff suspended the protocols for only 5% of the total application time due to medical procedures, surgeries, transient clinical problems not addressed by the protocols, or because of attending physician request. Of 3,148 instructions generated by the ventilation protocols, the clinical staff followed 2,932 (93%). The staff did not follow some instructions because of patient data errors, computer software and protocol logic errors, inability of the clinical staff to implement protocol instructions because of more pressing duties, and clinical staff objections to specific instructions. Sixty percent of the patients treated by the ventilation protocols survived. Our results demonstrate that the ventilation protocols provided a practical and safe decision support system for the mechanical ventilation of ARDS patients.

Clinical Protocols↗
PubMed1994

[Extraction of orbital foreign bodies using a new kind of image processing system].

We present a new localization system in orbital surgery. The procedure is based on the linkage of two methods. A preoperative thin-layer CT scan is taken and the image data are fed into a high-capacity computer which computes a three-dimensional model of the orbit. Intraoperatively, the volume model of the skull is linked to a mechanical arm for position measurement. Surgical instruments can be mounted to this arm. The computer then projects the position of the instrument into the volume model of the orbit, so that the surgeon can follow the movements of his instruments on the monitor. The surgeon has a means of checking position that comes close to constant intraoperative CT monitoring. Thereby the surgeon is able to localize even small foreign bodies without extensive explorations. We present six patients in whom orbital foreign bodies had to be extracted during the past 5 years. A 44-year-old man had an iron foreign body; the external wound was treated surgically elsewhere. Two patients (25 and 22 years old) had glass foreign bodies; in one of them the splinters were not seen using conventional X-ray. Choosing the exact level with the Hounsfield window, the foreign bodies could be demonstrated on the monitor. In three patients with orbital fractures and compression of the optic nerve, dislocated bone splinters were extracted. The localization of those splinters was easy using the imaging system, but would have been rather difficult by other means.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Arcuate keratotomy for the correction of spherical hyperopia in human cadaver eyes.

BACKGROUND: A new experimental surgical technique to correct spherical hyperopia by steepening of the central corneal curvature was performed on human cadaver eyes. METHODS: Ten eyes were used in the study. All were pretreated with glycerin to ensure a uniform corneal thickness between .55 and .65 mm on ultrasonic pachometry. A constant intraocular pressure of approximately 30 to 40 mm Hg was maintained in each eye by the injection of saline into the vitreous cavity. This was verified by pneumotonometry. A vertical blade diamond knife was set at 100% of the thinnest of four paracentral readings. Each eye underwent preoperative computed topography. One set of five eyes had 12 incisions made following a 5.75-millimeter diameter Mendez hexagonal marker that included unconnected T incisions at each junction (ie, "Hex T" pattern). The other set of five eyes had four arcuate incisions made following a 6-millimeter diameter zone marker; each incision was 60 degrees in arc. Immediately after surgery, computed topography was repeated. RESULTS: The hexagonal keratotomy set of eyes had an average steepening of the cornea of 0.80 D with a range of -1.05 to + 4.38 D. The arcuate keratotomy set had an average steepening of +2.12 D with a range of +1.27 to +3.27 D. CONCLUSIONS: This study suggests arcuate keratotomy may be a more effective procedure in the correction of spherical hyperopia when compared with hexagonal keratotomy. The amount of corneal steepening achieved in a cadaver eye model may not be the same as when performed in vivo.

Cornea↗
PubMedDate not supplied

[The brain in stereotaxic coordinates (a textbook for colleges)].

The present textbook is directed forward students of universities and medical colleges, young scientists and practicing doctors dealing with stereotaxic method. The Paxinos and Watson stereotaxic rat brain atlas (1982) is the basis of the textbook. The atlas has been transformed into computer educational program and seven laboratory works: insertion of the electrode into brain, microelectrophoresis, microinjection of drugs into brain, electrolytic destruction in the brain structures, local brain superfusion. The laboratory works are compiled so that they allow not only to study practical use of the stereotaxic method but to model simple problems involving stereotaxic surgery in the deep structures of brain. The textbook is intended for carrying by IBM PC/AT computers. The volume of the textbook is 1.7 Mbytes.

Animals↗
PubMed1993

[Surgical treatment of ventricular tachycardia].

Refractory ventricular tachycardia, resistant to antiarrhythmic drug therapy either because of inefficacy unwanted secondary effects or failure to comply with treatment, is not rare in the chronic phase of myocardial infarction. These considerations reinforce the value of curative therapeutic options, especially those related to antiarrhythmic surgery in these patients. Surgery is usually reserved for those with a ventricular aneurysm where the exclusion of arrhythmogenic zones may be performed with the scalpel, a cryoprobe, laser ... Procedures guided by peroperative endo end epicardial mapping, if possible simultaneous with computerised assistance, are more effective than procedures relying only on visual guiding. The clinical success rate is about 90% and the operative mortality tends to decrease (5 to 6%) with successive improvements to surgical technique. These satisfactory results show the reliability of this therapeutic approach applied to patients exposed to malignant arrhythmias.

Cryosurgery↗
PubMed1993

[Ambulatory continuous recording of pH and pressure in the esophagus].

Ambulatory simultaneous recording of oesophageal pressures and pH is a recently developed technique for evaluation of oesophageal function. The paper describes the experience gained with this technique at the Oesophagus Laboratory, department of Thoracic and Cardiovascular Surgery T, Odense University Hospital. A combined pH and pressure probe is positioned in the oesophagus and connected to a portable recorder. Data are digitised on-line and stored for later transfer to a computer. Analysis of pH-variations and contractile activity is performed automatically. Sections with normal and abnormal acid clearing are shown. A normal pressure response to reflux consists of frequent contractions of normal amplitude and propagation resulting in a stepwise clearing of acid from the oesophagus. Repetitive simultaneous contractions and periods of failed peristalsis are illustrated in sections from a patient with oesophagitis. Contractions of high amplitude and prolonged duration, as well as frequent non-propagating contractions in the distal oesophagus, are elements of a normal peristaltic pattern. The conventional manometric investigation performed under laboratory conditions still has first priority when esophageal dysmotility is suspected. In several instances, however, ambulatory recording of motility and pH may add valuable additional information.

Adult↗
PubMed1993

Selection of patients for surgery.

Patient selection for lumbar laminectomy has been reviewed. The clinical decision for laminectomy depends on the mainstays of history, physical examination, and radiologic examination. A computer model to assist in this difficult task has been presented; the model is yet to be clinically tested. Psychological and psychosocial criteria play an important role in the decision-making process in these patients.

Computer Simulation↗
PubMed1993

[Simulated surgery on a 3D model. Technic and applications].

Treatment planning for the correction of dentofacial deformities includes prediction tracing and model surgery. However, these conventional methods provide only limited information concerning the planned spatial displacement of skeletal structures. In cases of severe deformities we add simulated 3D model surgery in an individually processed life size polyurethane skull to our work-up. The basic steps of the 3D model surgery are described, the advantages outlined and the method discussed.

Computer-Aided Design↗
PubMed1993

[3D endoscopy].

With the aid of a 6 mm 0 degree stereo-endoscope supplied with a 100 Hz monitor and high-speed liquid crystal shutter, three-dimensional endoscopy of the upper airway was realized for the first time. The equipment used is based on alternating sequential projections of left and right eye images on a single tv screen. Two high-speed liquid crystal stereo switches (LCSS) are integrated in glasses and a rapid switching time of 100 microseconds is used. In a comparative study this innovative endoscopic technique was tested for its practicability in sinus surgery and endoscopy of the upper airway. With this equipment an excellent view was obtained of the pharynx, larynx and trachea. For sinus surgery, however, a stereoendoscope with smaller dimensions has to be developed.

Computer Graphics↗