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Biomedical subjects

A P Verkaaik

Publications and source records attributed to A P Verkaaik.

14 recordsLinked to original sources
PubMed1995

Spontaneous coronary artery dissection during pregnancy and post partum.

This report describes a 35-year-old 40 week pregnant woman who was hospitalized with a diagnosis of acute anteroseptal myocardial infarction. She sustained another, infero-posterior, infarction 4 days later. Coronary arteriography performed after successful Cesearean section displayed primary dissections of the right as well as both left coronary arteries. Her subsequent clinical course was uneventful with medical therapy. This patient is the first non-surgically treated survivor of peripartal spontaneous coronary artery dissection with a myocardial infarction prior to delivery.

Adult↗
PubMed1994

High flow closed circuit anaesthesia.

We present an automatic closed circuit anaesthesia ventilator designed for routine clinical use. The ventilator combines the benefits of high flow systems and true closed circuits, without their disadvantages. The system can be used with any FiO2, with air or nitrous oxide as carrier gas. Servo controlled delivery of modern volatile anaesthetics is regulated on end-tidal value. The time constant for increase or decrease of concentrations is only a few minutes. There is no need to open the system at any time, nor is it necessary to increase the fresh gas flow. An automatic flush procedure prevents accumulation of unwanted gases. Operation is as easy as contemporary non-closed circuit ventilators. With this machine, closed circuit anaesthesia is possible from the beginning to the end of the procedure.

Absorption↗
PubMed1993

Multiple coronary artery dissections in a woman at term.

We report a case of acute myocardial infarction caused by multiple coronary artery dissections in a pregnant woman at term. When reinfarction elicited fetal distress, Caesarean section was performed under carefully administered extradural anaesthesia, with maternal and fetal survival.

Adult↗
PubMed1992

On-line oxygen uptake measurement (VO2): a computer feed-back controlled rebreathing circuit for long term oxygen uptake registration.

A totally closed feed back controlled anesthesia- and ventilation circuit has been developed feasible to be applied for artificial ventilation with tidal volumes as low as 5 ml at a rate of up to 60/min and for spontaneous ventilation with on-line measurement of physiological lung parameters (pressure, volume, flow). Oxygen inflow is regulated via actual-set value comparison, oxygen inflow is measured and recorded on-line (= oxygen uptake by the connected subject). On-line oxygen uptake (consumption) measurement furnishes a valuable, so far not available parameter to monitor changes in the oxygen transport chain to the tissue and to register physiological oxygen consumption values and derangement of metabolism. First results show that total body oxygen consumption of man in rest is lower than so far expected in the high weight and body surface area groups and that oxygen consumption is decreasing with length and age. Metabolic derangements such as in developing hyperthermia crisis are noticed in a very early stage when therapy is still possible before severe damage has occurred.

Adult↗
PubMed1992

Oxygen uptake and static lung compliance during automatic ventilation.

Oxygen uptake is an important parameter to control proper tissue oxygen delivery. Oxygen uptake is dependent on adequate lung function and easily disturbed by changes in lung compliance and related parameters such as the tidal volume controlling pressure support. Simultaneous on-line registration of oxygen uptake and lung compliance together with ventilatory pressures applied to achieve preset tidal volumes has been made possible using the computer feedback controlled closed circuit ventilatory system Physio-Flex (Physio Co, Hoofdorp, The Netherlands). The system guarantees for leakage free functioning (maximal leakage 7 mL gas loss/minute) and, therefore, patient oxygen consumption measurements with an accuracy of more than 95%. A specially developed membrane ventilation mode registers on-line flow and displaced volume automatically corrected for temperature, pressure and compressible volume. The current investigation has shown: Decrease oxygen consumption versus oxygen delivery supply dependency may be induced by reflectory decreases of heart rate and cardiac output; in this case a reactive pulmonary parameter change is preceding the event in form of a drop in compliance and corresponding changes in ventilatory pressures necessary to maintain the preset tidal volume. In contrast, decrease of oxygen uptake following changes in cardiac output due to acute hypovolemia has no effect on pulmonary function parameters. This can be diagnostically used as moderate changes of tidal volume also have no significant influence on pulmonary parameters. However, changes due to reduction in depth of anesthesia and relaxation have some influence and need to be excluded.

Adult↗
PubMed1992

Non-invasive, on-line measurement of oxygen consumption during anesthesia.

Oxygen consumption is usually derived from values measured by a thermodilution catheter, i.e. an invasive procedure, with associated risks and calculation errors. Closed circuit ventilation provides a reliable, non-invasive means of access to this parameter of metabolism. Routine application of closed circuit ventilation requires overcoming many, mainly technical, difficulties (e.g. leakage problems, valve malfunctions, and calculations of gas uptake). We developed a computerized closed circuit anesthesia ventilator without these problems. With this system non-invasively measured oxygen uptake is continuously presented on-line. We discuss three representative patients presenting for surgical repair of an abdominal aneurysm. Besides actual changes in metabolism and depth of anesthesia, success or failure of the operation is visible in the pre- and direct post-clamping period. With resuscitative therapeutic interventions, increase in oxygen consumption gives valuable information under changing conditions. We conclude that closed circuit anesthesia is a safe and valuable method for measurement of oxygen consumption.

Aged↗
PubMed1991

Propofol safely used in a neuroleptic malignant syndrome patient.

Anaesthetic regimens for patients with the poorly understood neuroleptic malignant syndrome (NMS) are not well outlined. In this case report, NMS and its questionable relation to malignant hyperpyrexia are outlined. Satisfactory use of total intravenous anaesthesia, based on propofol, in an NMS-susceptible patient is presented.

Anesthesia, Intravenous↗
PubMed1991

[A computer-controlled closed circle system for ventilation during anesthesia and intensive care and its possibilities for patient monitoring].

A computer feed back controlled anaesthesia- and intensive care ventilator has been developed with on-line and separate lung function measurement. The system design is built on the principle of a totally closed circuit (closed rebreathing respirometer) and an inspiratory "high flow", the gas being rotated through the closed circuit unidirectionally by a blower with 70 l/min. Ventilation is performed by metal membranes freely movable in membrane chambers with an internal part included into the closed circuit and an external part connected to pressurized air controlling inspiratory valves expiratory valves. The electronic valves are software controlled by the computer to exactly perform the desired preset ventilatory mode. Membrane movement are on-line measured capacitively and transformed into respective flow and volume values, whereby the compressibility of the system gas (on-line pressure recording) is taken into account. Volatile anaesthetic gases are feed back controlled to preset end expiratory values (MAC-controlled anaesthesia), circuit volume is maintained by N20-addition and oxygen is added to maintain the desired present inspiratory concentration measured with paramagnetic oxygen sensors. Ergonometric aspects led to the triangular from of the new anaesthesia and intensive care ventilator with the controlling service screen turnable to all three sides of the ventilator (high flexibility of the user) and all necessary equipment and material included into the "Anaesthesia workstation". All measured and present parameters are continuously displayed on the service (computer) screen and entered into the computer-memory in minute cycles with a memory capacity of 75 h anaesthesia. At any desired moment the memorized values can be transferred to IBM-compatible disc systems for storage or into the respective data management systems, thus at the end of anaesthesia, at the end of the working day or at the end of the week.

Anesthesia, Closed-Circuit↗
PubMed1990

Cardiovascular implementations of respiratory measurements.

Direct measurement of oxygen consumption (VO2) as an important on-line available parameter in patient monitoring has only very recently been accomplished with the development of the totally closed circuit anesthesia ventilator Physioflex. When the respiratory parameters measured with the same system and inspiratory oxygen concentration are in normal range adequate cellular oxygen supply is furthermore dependent on the following factors that influence oxygen delivery (DO2) to the tissue: the general factors, oxygen transport capacity of the blood and cardiac output and (local factors) distribution of tissue perfusion (including e.g. local occlusion, sludging, steal syndrome). In critically ill patients general impairment of oxygen delivery might occur as well as maldistribution. Studies were performed in experimental animals and patients to get some insight into the cardiovascular implementations of these respiratory measurements. Oxygen delivery has been manipulated (in pigs) by sodium nipride infusion (drop of blood pressure and cardiac output) to critical levels of oxygen supply. Endotoxin was infused with typical hemodynamic changes (first, hyperdynamic phase with increase of pulmonary artery pressure, decrease of mean arterial pressure and increase of cardiac output and, second, hypodynamic phase with low cardiac output). VO2 and oxygen delivery were controlled in a patient with a ruptured aneurysm, with impairment of oxygen transport capacity due to low hemoglobin but maintained circulating volume.

Anesthesia, Closed-Circuit↗
PubMed1990

Respiratory diagnostic possibilities during closed circuit anesthesia.

An automatic feed back controlled totally closed circuit system (Physioflex) has been developed for quantitative practice of inhalation anesthesia and ventilation. In the circuit system the gas is moved unidirectionally around by a blower at 70 l/min. In the system four membrane chambers are integrated for ventilation. Besides end-expiratory feed back control of inhalation anesthetics, and inspiratory closed loop control of oxygen, the system offers on-line registration of flow, volume and respiratory pressures as well as a capnogram and oxygen consumption. Alveolar ventilation and static compliance can easily be derived. On-line registration of oxygen consumption has proven to be of value for determination of any impairment of tissue oxygen supply when the oxygen delivery has dropped to critical values. Obstruction of the upper or lower airways are immediately detected and differentiated. Disregulations of metabolism, e.g. in malignant hyperthermia, are seen in a pre-crisis phase (increase of oxygen consumption and of CO2 production), and therapy can be started extremely early and before a disastrous condition has developed. Registration of compliance is only one of the continuously available parameters that guarantee a better and adequate control of lung function (e.g. atalectasis is early detected). The newly developed sophisticated anesthesia device enlarges tremendously the monitoring and respiratory diagnostic possibilities of artificial ventilation, gives new insights in the (patho)physiology and detects disturbances of respiratory parameters and metabolism in an early stage.

Airway Resistance↗
PubMed1990

Informative imaging of multiple parameters for the practice of the anesthesiologist.

The development of informative design principles is necessary to permit logical, informative and understandable computer-aided imaging of the flood of measured parameters the practising anesthesiologist is currently confronted with. The computer-assisted workplace, furthermore, can use the computer to close the loop from sensor to therapy through software directed feed back control mechanisms. The general principles of information design should be based on the rule of three derived from the limited visual integration capacity of the human brain. Thus multiple parameters should be logically grouped in blocks of three strictly distinct from each other in the visual display output. Alarm signalisations have to include two senses: visual and audible and should use the large range of variability that is possible to make them distinct from each other. The operational keyboard should be logically designed with grouping in three parts: 1. a group of buttons for activation of operational screen information that appear with never more than three at the same time; 2. buttons for presetting of wanted parameter values, of alarm limits and for introduction of patient data with adjoint but strictly separated OK-mode necessity to alert that change is being made. 3. a row of buttons separated from the normal operational keyboard area for emergency changes and computer feed back mode bypass, for example. The most illogical, unoverseeable and confusing computeraided workplace can be organized to a fully assisting anesthesia workplace if proper design is applied. The use of a users' manual should be rendered unnecessary even to a computer-naive user. This can be achieved through adequate informative design and operational information flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Closed-Circuit↗