Dye Dilution Technique
Indicator Dilution Techniques
Plasma Volume
Radioisotope Dilution Technique
Cardiac Output
Succinimides
Oligohydramnios
Polyhydramnios
Amniotic Fluid
Ultrasonography, Prenatal
Gestational Age
Pregnancy
The circulating plasma volume of the foetal lamb as an index of its weight and rate of weight gain (g/day) in the last third of gestation. (1/74)
In a series of foetal lambs weighing between 1,100 and 5,228 g, the circulating plasma volume was estimated by the dye dilution method, using Evans Blue, to test the possibility that the plasma volume could be used as an index of foetal weight in chronic studies. The data, analysed by the method of least squares regression, indicate that plasma volume and foetal weight are closely correlated (R-2 equals 0.922) and linearly so in the range of data studied. There was no evidence that the relation differed for singlets and twins. A single equation, Y equals 71.8 plus 10.11 X--where Y is the estimated weight and X the plasma volume, can be used to predict the weight from plasma volume in both. Some results of the application of the method in chronic studies are presented. (+info)The precision of a special purpose analog computer in clinical cardiac output determination. (2/74)
Three hundred dye-dilution curves taken during our first year of clinical experience with the Waters CO-4 cardiac output computer were analyzed to estimate the errors involved in its use. Provided that calibration is accurate and 5.0 mg of dye are injected for each curve, then the percentage standard deviation of measurement using this computer is about 8.7%. Included in this are the errors inherent in the computer, errors due to baseline drift, errors in the injection of dye and acutal variation of cardiac output over a series of successive determinations. The size of this error is comparable to that involved in manual calculation. The mean value of five successive curves will be within 10% of the real value in 99 cases out of 100. Advances in methodology and equipment are discussed which make calibration simpler and more accurate, and which should also improve the quality of computer determination. A list of suggestions is given to minimize the errors involved in the clinical use of this equipment. (+info)Evaluation of portable radionuclide method for measurement of left ventricular ejection fraction and cardiac output. (3/74)
Seventeen patients with coronary artery, valvular, or myopathic heart disease were studied to determine correlations of the cardiac output and ejection fraction when comparing the results obtained with a portable probe technique using 113mIn with those obtained with standard methods (cineangiographic, Fick, and dye dilution). With ejection fractions ranging from o.10 to 0.85, the coefficient of correlation was 0.90 when comparing cineangiographic and radionuclide techniques. Cardiac output determinations by the radionuclide technique also correlated well with standard methods (r equals 0.88). The radionuclide method shows promise as an accurate, safe, and simple method in the evaluation of cardiac function at the bedside. (+info)Fluorescein diffusion in the human optic disc. (4/74)
The characteristics of the transcapillary transfer of fluorescein dye in the optic disc of healthy individuals has been studied. A diffusible fluorescein dye and a nondiffusible reference substance, indocyanine green (ICG), which was assumed to remain in the capillaries, were injected into the circulatory system. The time courses of the concentrations of the two dyes in the optic disc were determined by simultaneously recording the fluorescence intensity of fluorescein and the infrared absorption by ICG with a fundus reflectometer. The difference between the fluorescein concentration curve and the reference ICG curve is a measure of the accumulation of fluorescein in the disc tissue. Our measurements indicate that fluorescein dye does not diffuse across the capillaries in the optic disc. The accumulation of fluorescein in the disc only starts at about one minute after the injection and seems to be due to diffusion of the dye from the surrounding choroid. The time constant of this diffusion process was found to be approximately one minute. (+info)Effect of propranolol on left ventricular function, segmental wall motion, and diastolic pressure-volume relation in man. (5/74)
Precise quantitation of the effects of the non-selective beta adrenergic blocking drug propranolol (3.15 mg/kg body weight) on left ventricular function, segmental wall motion, and diastolic pressure-volume relation in man has been performed. High fidelity left ventricular pressure measurements and simultaneous single-plane angiocardiograms were recorded on a video disc and volumes calculated by a light-pen computer system. Systolic segmental wall motion was computer analysed using the long axis-quadrasection method. Patients were transvenously atrially paced to maintain a constant heart rate. The haemodynamic effects of propranolol may vary depending upon the extent of pre-existing myocardial disease. In some patients ventricular function, as measured by ejection fraction, may be reduced. This reduction in ejection fraction appears to result from overall reduction in segmental wall motion, but also from accentuation of segmental wall abnormalities. These results are consistent with the thesis that beta adrenergic blocking drugs may inhibit compensatory sympathetic mechanisms. The diastolic effects of propranolol may include quite substantial increases in ventricular volumes in those patients with impaired cardiac function. With respect to the intact human ventricle, propranolol may increase diastolic volume for a given level of ventricular pressure. Thus, in a static sense, the ventricle in these patients could be viewed as being more compliant after propranolol administration. However, the fact that the length-tension relation, as measured by the slope of the logarithmic pressure versus volume plot is unaltered by propranolol, suggests that the muscle comprising the ventricle itself exhibits no alteration in its passive elastic properties. (+info)Use of a dynamic method in calibration of dye-dilution curves during cardiac surgery. (6/74)
A simplified dynamic method of calibration for dye-dilution curves is described. The method involves appropriate matching of the fluid volume in the mixing chamber, the blood withdrawal rate, and the calibration dose of dye. It was used to compare the observed versus calibrated pump output of a heart-lung machine with individual dye-dilution curves obtained from 15 patients during total cardiopulmonary bypass. The results indicate that the difference (range+14% to-8%) between the two is statistically insignificant. The method is rapid and relatively simple. It is particularly useful for cardiac output determination during unsteady clinical conditions because of the ability to calibrate dye curves at the time they are recorded. (+info)Cardiac output measurement by thermal dilution: reproducibility and comparison with the dye-dilution technique. (7/74)
Cardiac output estimates by the principle of thermodilution (COth) was compared with dye-dilution estimates (COdye) in pigs. For COth estimates a Swan-Ganz 7 F floating thermodilution catheter and a 9500 Edwards Computer, were used. The COdye estimates were obtained by the apparatus constructed by Zijlstra and Mook. The effect of the thermistor position in the pulmonary artery on the COth estimates was also investigated. The reproducibility of COth was examined by duplicate determinations. Based on 101 simultaneous estimates of COth and COdye the correlation was found COth = 1.020 COdye + 0.2378, r = 0.971 for cardiac outputs between 0.65 l/min and 11 l/min. For 111 duplicate determinations of COth between 2 and 9 l/min the coefficient of variation was 4.74%. The thermistor position in the pulmonary artery had no influence on the COth estimates provided an undamped pressure curve could be monitored from the tip of the catheter. Cardiac output can thus be measured rapidly with good accuracy also for low values by means of a blindly inserted thermistor catheter positioned without x-ray control and a computer with digital display. (+info)Studies of in vitro activities of voriconazole and itraconazole against Aspergillus hyphae using viability staining. (8/74)
The minimal fungicidal concentrations (MFCs) of voriconazole and itraconazole for five clinical isolates each of Aspergillus terreus, Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger were determined by a broth macrodilution method. Conidial suspensions as inocula were compared to hyphae as inocula since the invasive form of aspergillosis is manifested by the appearance of hyphal structures. In addition, cell viability staining with the dye FUN-1 was performed to assess time-dependent damage of hyphae exposed to various concentrations of the antifungal agents. With conidial inocula the MFC ranges of voriconazole were 0.5 to 4 microg/ml and those of itraconazole were 0.25 to 2 microg/ml, whereas the MFCs (2 to >16 microg/ml) with hyphal inocula were substantially higher (P < 0.01) for both itraconazole and voriconazole. Only minor differences between the tested antifungals were observed since 16 of 20 and 17 of 20 of the isolates of Aspergillus spp. tested appeared to be killed by voriconazole and itraconazole, respectively. The results of FUN-1 viability staining correlated closely to colony counts, but various time- and dose-dependent levels of viability of hyphae were also observed. In conclusion, our study demonstrates the importance of the type of inoculum used to test antifungals and the applicability of FUN-1 staining as a rapid and sensitive method for assaying the viability of hyphae. (+info)The dye dilution technique is a method used in medicine, specifically in the field of pharmacology and physiology, to measure cardiac output and blood volume. This technique involves injecting a known quantity of a dye that mixes thoroughly with the blood, and then measuring the concentration of the dye as it circulates through the body.
The basic principle behind this technique is that the amount of dye in a given volume of blood (concentration) decreases as it gets diluted by the total blood volume. By measuring the concentration of the dye at two or more points in time, and knowing the rate at which the dye is being distributed throughout the body, it is possible to calculate the cardiac output and blood volume.
The most commonly used dye for this technique is indocyanine green (ICG), which is a safe and non-toxic dye that is readily taken up by plasma proteins and has a high extinction coefficient in the near-infrared region of the spectrum. This makes it easy to measure its concentration using specialized equipment.
The dye dilution technique is a valuable tool for assessing cardiovascular function in various clinical settings, including during surgery, critical care, and research. However, it requires careful calibration and standardization to ensure accurate results.
Indicator dilution techniques are a group of methods used in medicine and research to measure various physiological variables, such as cardiac output or cerebral blood flow. These techniques involve introducing a known quantity of an indicator substance (like a dye or a radioactive tracer) into the system being studied and then measuring its concentration over time at a specific location downstream.
The basic principle behind these techniques is that the concentration of the indicator substance will be inversely proportional to the flow rate of the fluid through which it is moving. By measuring the concentration of the indicator substance at different points in time, researchers can calculate the flow rate using mathematical formulas.
Indicator dilution techniques are widely used in clinical and research settings because they are relatively non-invasive and can provide accurate and reliable measurements of various physiological variables. Some common examples of indicator dilution techniques include thermodilution, dye dilution, and Fick principle-based methods.
Plasma volume refers to the total amount of plasma present in an individual's circulatory system. Plasma is the fluid component of blood, in which cells and chemical components are suspended. It is composed mainly of water, along with various dissolved substances such as nutrients, waste products, hormones, gases, and proteins.
Plasma volume is a crucial factor in maintaining proper blood flow, regulating body temperature, and facilitating the transportation of oxygen, carbon dioxide, and other essential components throughout the body. The average plasma volume for an adult human is approximately 3 liters, but it can vary depending on factors like age, sex, body weight, and overall health status.
Changes in plasma volume can have significant effects on an individual's cardiovascular function and fluid balance. For example, dehydration or blood loss can lead to a decrease in plasma volume, while conditions such as heart failure or liver cirrhosis may result in increased plasma volume due to fluid retention. Accurate measurement of plasma volume is essential for diagnosing various medical conditions and monitoring the effectiveness of treatments.
The Radioisotope Dilution Technique is a method used in nuclear medicine to measure the volume and flow rate of a particular fluid in the body. It involves introducing a known amount of a radioactive isotope, or radioisotope, into the fluid, such as blood. The isotope mixes with the fluid, and samples are then taken from the fluid at various time points.
By measuring the concentration of the radioisotope in each sample, it is possible to calculate the total volume of the fluid based on the amount of the isotope introduced and the dilution factor. The flow rate can also be calculated by measuring the concentration of the isotope over time and using the formula:
Flow rate = Volume/Time
This technique is commonly used in medical research and clinical settings to measure cardiac output, cerebral blood flow, and renal function, among other applications. It is a safe and reliable method that has been widely used for many years. However, it does require the use of radioactive materials and specialized equipment, so it should only be performed by trained medical professionals in appropriate facilities.
Cardiac output is a measure of the amount of blood that is pumped by the heart in one minute. It is defined as the product of stroke volume (the amount of blood pumped by the left ventricle during each contraction) and heart rate (the number of contractions per minute). Normal cardiac output at rest for an average-sized adult is about 5 to 6 liters per minute. Cardiac output can be increased during exercise or other conditions that require more blood flow, such as during illness or injury. It can be measured noninvasively using techniques such as echocardiography or invasively through a catheter placed in the heart.
Blood volume refers to the total amount of blood present in an individual's circulatory system at any given time. It is the combined volume of both the plasma (the liquid component of blood) and the formed elements (such as red and white blood cells and platelets) in the blood. In a healthy adult human, the average blood volume is approximately 5 liters (or about 1 gallon). However, blood volume can vary depending on several factors, including age, sex, body weight, and overall health status.
Blood volume plays a critical role in maintaining proper cardiovascular function, as it affects blood pressure, heart rate, and the delivery of oxygen and nutrients to tissues throughout the body. Changes in blood volume can have significant impacts on an individual's health and may be associated with various medical conditions, such as dehydration, hemorrhage, heart failure, and liver disease. Accurate measurement of blood volume is essential for diagnosing and managing these conditions, as well as for guiding treatment decisions in clinical settings.
Succinimides are a group of anticonvulsant medications used to treat various types of seizures. They include drugs such as ethosuximide, methsuximide, and phensuximide. These medications work by reducing the abnormal electrical activity in the brain that leads to seizures.
The name "succinimides" comes from their chemical structure, which contains a five-membered ring containing two nitrogen atoms and a carbonyl group. This structure is similar to that of other anticonvulsant medications, such as barbiturates, but the succinimides have fewer side effects and are less likely to cause sedation or respiratory depression.
Succinimides are primarily used to treat absence seizures, which are characterized by brief periods of staring and lack of responsiveness. They may also be used as adjunctive therapy in the treatment of generalized tonic-clonic seizures and other types of seizures.
Like all medications, succinimides can cause side effects, including nausea, vomiting, dizziness, headache, and rash. More serious side effects, such as blood dyscrasias, liver toxicity, and Stevens-Johnson syndrome, are rare but have been reported. It is important for patients taking succinimides to be monitored regularly by their healthcare provider to ensure safe and effective use of the medication.
Oligohydramnios is a medical condition that refers to an abnormally low amount of amniotic fluid surrounding the fetus in the uterus during pregnancy. The amniotic fluid is essential for the protection and development of the fetus, including lung maturation and joint mobility. Oligohydramnios is often diagnosed through ultrasound measurements of the pocket depth of the amniotic fluid and is defined as an amniotic fluid index (AFI) of less than 5 cm or a single deepest pocket (SDP) of less than 2 cm after 24 weeks of gestation.
The condition can be caused by various factors, such as fetal growth restriction, maternal high blood pressure, placental insufficiency, rupture of membranes, and genetic disorders. Oligohydramnios may increase the risk of complications during pregnancy and childbirth, including preterm labor, fetal distress, and stillbirth. The management of oligohydramnios depends on the underlying cause and gestational age, and may include close monitoring, delivery, or treatment of the underlying condition.
Polyhydramnios is a medical condition characterized by an excessive accumulation of amniotic fluid in the sac surrounding the fetus during pregnancy, typically defined as an amniotic fluid index (AFI) greater than 24 cm or a single deepest pocket (SDP) measurement of more than 8 cm. It occurs in approximately 1-2% of pregnancies and can be associated with various maternal, fetal, and genetic conditions. If left untreated, polyhydramnios may increase the risk of premature labor, premature rupture of membranes, and other pregnancy complications. Proper diagnosis and management are essential to ensure a healthy pregnancy outcome.
Amniotic fluid is a clear, slightly yellowish liquid that surrounds and protects the developing baby in the uterus. It is enclosed within the amniotic sac, which is a thin-walled sac that forms around the embryo during early pregnancy. The fluid is composed of fetal urine, lung secretions, and fluids that cross over from the mother's bloodstream through the placenta.
Amniotic fluid plays several important roles in pregnancy:
1. It provides a shock-absorbing cushion for the developing baby, protecting it from injury caused by movement or external forces.
2. It helps to maintain a constant temperature around the fetus, keeping it warm and comfortable.
3. It allows the developing baby to move freely within the uterus, promoting normal growth and development of the muscles and bones.
4. It provides a source of nutrients and hydration for the fetus, helping to support its growth and development.
5. It helps to prevent infection by providing a barrier between the fetus and the outside world.
Throughout pregnancy, the volume of amniotic fluid increases as the fetus grows. The amount of fluid typically peaks around 34-36 weeks of gestation, after which it begins to gradually decrease. Abnormalities in the volume of amniotic fluid can indicate problems with the developing baby or the pregnancy itself, and may require medical intervention.
Prenatal ultrasonography, also known as obstetric ultrasound, is a medical diagnostic procedure that uses high-frequency sound waves to create images of the developing fetus, placenta, and amniotic fluid inside the uterus. It is a non-invasive and painless test that is widely used during pregnancy to monitor the growth and development of the fetus, detect any potential abnormalities or complications, and determine the due date.
During the procedure, a transducer (a small handheld device) is placed on the mother's abdomen and moved around to capture images from different angles. The sound waves travel through the mother's body and bounce back off the fetus, producing echoes that are then converted into electrical signals and displayed as images on a screen.
Prenatal ultrasonography can be performed at various stages of pregnancy, including early pregnancy to confirm the pregnancy and detect the number of fetuses, mid-pregnancy to assess the growth and development of the fetus, and late pregnancy to evaluate the position of the fetus and determine if it is head down or breech. It can also be used to guide invasive procedures such as amniocentesis or chorionic villus sampling.
Overall, prenatal ultrasonography is a valuable tool in modern obstetrics that helps ensure the health and well-being of both the mother and the developing fetus.
Gestational age is the length of time that has passed since the first day of the last menstrual period (LMP) in pregnant women. It is the standard unit used to estimate the age of a pregnancy and is typically expressed in weeks. This measure is used because the exact date of conception is often not known, but the start of the last menstrual period is usually easier to recall.
It's important to note that since ovulation typically occurs around two weeks after the start of the LMP, gestational age is approximately two weeks longer than fetal age, which is the actual time elapsed since conception. Medical professionals use both gestational and fetal age to track the development and growth of the fetus during pregnancy.
Pregnancy is a physiological state or condition where a fertilized egg (zygote) successfully implants and grows in the uterus of a woman, leading to the development of an embryo and finally a fetus. This process typically spans approximately 40 weeks, divided into three trimesters, and culminates in childbirth. Throughout this period, numerous hormonal and physical changes occur to support the growing offspring, including uterine enlargement, breast development, and various maternal adaptations to ensure the fetus's optimal growth and well-being.
Fetal diseases are medical conditions or abnormalities that affect a fetus during pregnancy. These diseases can be caused by genetic factors, environmental influences, or a combination of both. They can range from mild to severe and may impact various organ systems in the developing fetus. Examples of fetal diseases include congenital heart defects, neural tube defects, chromosomal abnormalities such as Down syndrome, and infectious diseases such as toxoplasmosis or rubella. Fetal diseases can be diagnosed through prenatal testing, including ultrasound, amniocentesis, and chorionic villus sampling. Treatment options may include medication, surgery, or delivery of the fetus, depending on the nature and severity of the disease.
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