Dafina Tanase

Evaluation of Vascular and Interventional Procedures with Time–Action Analysis: A Pilot Study

PURPOSE To provide an objective method to measure the efficiency of vascular and interventional procedures. MATERIALS AND METHODS The time-action analysis method is defined for peripheral vascular and interventional procedures. A taxonomy of actions is defined, geared specifically toward these procedures. The actions are: start-up/wrap-up, exchange, navigate, image, diagnose, treat, handle material, wait, compress puncture site, and unclassified. The recording method and analysis techniques are described. To show the type of data that can be obtained, the time-action analysis of 30 procedures is presented. RESULTS The results provide a detailed picture of the time spent on various actions. Of all actions, the most time is spent on compressing the puncture site (18.5%), whereas the highest frequency of actions are for exchange of catheters, guide wires, and sheaths (20.4 times per procedure). Radiation exposure can be analyzed in detail, which can yield directions for possible reduction. For instance, 5.2%-8.3% of the total radiation exposure occurs during preparation of imaging to adjust the position of the patient table and set the image intensifier diaphragm. CONCLUSION Time-action analysis provides an objective measurement method to monitor and evaluate vascular and interventional procedures. Potential applications and limitations of the technique are discussed.

Multi-parameter sensor system with intravascular navigation for catheter/guide wire application

Interventional radiology is a medical speciality, which uses medical tools such as guide wires and catheters to diagnose and treat vascular diseases. To navigate these tools to the place of intervention, X-ray imaging is extensively used, creating an important health risk to the medical staff and to the patient. To reduce the radiation dose, an electromagnetic navigation system is currently being developed. Once the correct position has been attained with the guide wire, the catheter can be brought into place. In many cases, the intervention radiologist requires a number of measurements to assess the situation and the treatment required. To achieve this, a multi-sensor chip has been developed for blood flow, pressure and oxygen saturation level, with dimensions suitable for catheter applications. The localisation system and the measurement system will be presented in this paper.

Silicon sensors for use in catheters

To reduce the amount of trauma during medical procedures, so-called minimally invasive procedures are being used. In vascular interventions, catheters are used in the blood vessels. In order to Increase the amount of information a physician has available during these interventions, sensors are needed. To this end, a multiple parameter sensor to measure blood pressure, flow, oxygen saturation and temperature, and a sensor to determine the age of blood clots using colour are developed. In addition, a system to reduce the amount of ionising radiation needed during the positioning of catheters is developed. The special environment puts high demands on the packaging. It needs to protect the sensor from the body, the body from the sensor but allow the parameter to be measured access to the sensor. To overcome the uncertain positioning of the sensor within the vessel, a special sensor catheter needs to be designed.

Oxygen-tension measurements - the first step towards prevention and early detection of anastomotic leakage

Many patients still die every year as a result of anastomotic leakage after surgery. The medical world needs an objective aid to detect leakage during surgery and during the critical recovery period. We propose a miniature measurement system to detect adequate tissue oxygenation pre-and postoperatively (continuously for 7 days) on the colon. The sensor chip should include an oxygen-saturation sensor, an oxygen-tension sensor, a carbon dioxide tension sensor and a temperature sensor. The work presented here focuses on the measurements done with the oxygen-tension and temperature sensors. In-vitro measurements were carried out to test the sensor system and initial in-vivo tests were performed on a rat kidney, during an ischemia-reperfusion experiment.

Catheter navigation system for intravascular use

Minimally invasive intravascular interventions are performed with the aid of guide wires and catheters. When inserted into the cardiovascular system, the location of these tools is monitored using X-ray imaging techniques. However, a high radiation dose during the medical procedures, creates an important health risk for clinicians and assistant. In order to reduce the radiation dose, a relevant X-ray image is taken during the medical intervention and is augmented, at successive moments during the procedure, with a virtual indicator for the position and orientation of the guide wire tip. The location of the tip is determined by means of an electromagnetic system, composed of coils, outside the patient, and a three-dimensional sensor on the tip of the guide wire. This way, the need to continuously use radiation is eliminated. Furthermore, the standard intravascular procedure is not changed and the cost of the system is kept low.

Tissue-Viability Monitoring Using an Oxygen-Tension Sensor

Many patients still die every year as a result of anastomotic leakage after surgery. An objective aid to monitor the anastomotic site pre- and postoperatively and detect leakage at an early stage is needed. We propose a miniature measurement system to detect adequate tissue oxygenation pre- and postoperatively (continuously for 7 days) on the colon. The complete sensor chip should include an oxygen-tension sensor (pO2), a carbon dioxide tension sensor (pCO2) and a temperature sensor. The work presented here focuses on the measurements done with the oxygen-tension and temperature sensors. In-vitro measurements have been initially performed to test the sensor system and in-vivo tests were carried out on the kidney and the intestines of male wistar rats. The results obtained so far have shown the suitability of this technique for clinical application, therefore sensor-system miniaturisation is presently underway.

A DFA Framework for Hybrid Microsystems

This paper presents a framework for Design For Assembly of hybrid microsystems. Hybrid microsystems are microsystems, mainly semi-conductor based, which offer diverse functionality, and which are realised by integrating elements (die, parts) from different material and technology domains. From macro-domain mechanical products, it is known that the design of these products is of major importance for the performance of the assembly process. The paper addresses the question which aspects of assembly-oriented design are relevant for hybrid microsystems. A Design For Assembly (DFA) framework is presented, which distinguishes two main levels of design decisions: the integration approach level and the process and technology level. The framework is illustrated on the basis of a product case: an optode for medical applications.

3D position and orientation measurements with a magnetic sensor for use in vascular interventions

In minimal-invasive intravascular procedures high ionising-radiation doses are employed to monitor the medical instruments during an intervention, creating an important health risk to the medical staff. To reduce the high doses, a magnetic-based navigation system to guide the medical tools to the intervention place without the use of X-rays is being developed. The system consists of a 3D magnetic source and a 3D magnetic sensor that is placed at the tip of the medical tool. The magnetic field generated by the source is measured by the sensor and converted by means of a mathematical algorithm into the position and orientation of the sensor with respect to the magnetic source. 1D measurements that were performed using a patient model are extended to 3D position and orientation measurements.

Multi-parameter Catheter Sensor System with Intravascular Navigation

Interventional radiology is a medical speciality, which uses medical tools such as guide wires and catheters to diagnose and treat vascular diseases. To navigate these tools to the place of intervention, x-ray imaging is extensively used, creating an important health risk to the medical staff and to the patient. To reduce the radiation dose, an electromagnetic navigation system is currently being developed. Once the correct position has been attained with the guide wire, the catheter can be brought into place. In many cases, the intervention radiologist requires a number of measurements to assess the situation and the treatment required. To achieve this, a multi-sensor chip has been developed for blood flow, blood pressure and blood oxygen satuiation, with dimensions suitable for catheter applications. The localization system and the measurement system will be presented in this paper.

MICROSENSORS FOR MULTIPLE-PARAMETER MEDICAL MEASUREMENTS

Often in medical applications a single measurement does not give sufficient information to the clinicians. IC technology allows the combination of several sensors in a small volume for instantaneous multi-measurements at a single location. This paper presents two multi-parameter sensors for catheter applications, with initial experimental results, along with the packaging issue - an important aspect for biomedical sensors.