Increase In Body Surface Area Research Articles

Comparison of right ventricular volumes by transthoracic and transesophageal echocardiography in patients with right ventricular volume overload

AbstractAssessment of right ventricular volume and function is important in most congenital heart diseases before and after corrective or palliative surgery. Since transthoracic echocardiography is often substituted by transesophageal echocardiography in the perioperative setting, it is useful to compare transesophageal echocardiography with transthoracic echocardiography as performed preoperatively. We compared right ventricular volumes as calculated using these two methods from a four-chamber view in 21 children and adults with atrial septal defect. For right ventricular end-diastolic volumes of less than 70 ml, and end-systolic volumes of less than 40 ml, a close correlation was found between the techniques (r=0.99 and r=0.91, respectively), with a small degree of underestimation by transesophageal echocardio­graphy. For values larger than 70 nil and 40 ml, respectively, correlation decreased (r=0.41 for end-diastolic volumes and r=0.48 for end-systolic volumes) and underestimation of volume by transesophageal echocardiography increased. Underestimation of right ventricular end-diastolic volumes increased with increasing body surface area (r=0.74), and with progressive right ventricular enlargement (r=0.63). In patients with a body surface area of more than 1m2, the largest end-diastolic right ventricular length determined by transthoracic echocardiography was significantly longer than that derived by transesophageal echocardiography (p<0.001), whereas in smaller patients there was no significant difference between the two methods (p>0.1). If right ventricular volumes determined by transthoracic echocardiography using a four-chamber view are substituted by those obtained with transesophageal echocardiography in serial haemodynamic evaluation of patients with atrial septal defect, different correlation equations and, consequently, a different degree of underestimation by transesophageal echocardiography must be considered for large and small volumes. This increasing underestimation of larger right ventricular volumes seems to be based on foreshortening of the long cross-sectional axis of the right ventricle as seen in the transesophageal four-chamber view.

Medical abortion with oral methotrexate and vaginal misoprostol

To evaluate the safety and efficacy of oral methotrexate and vaginal misoprostol for medical abortion. A prospective multicenter trial involved 300 women up to 49 days' gestation seeking elective abortion. Subjects received methotrexate 50 mg orally followed 5-6 days later by misoprostol 800 micrograms vaginally. The misoprostol dose was repeated if abortion did not occur. Complete abortion occurred in 273 of 299 women (91.3%; 95% confidence interval [CI] 87.5, 94.2%); one woman was lost to follow-up. Abortion occurred within 8 days of the methotrexate in 233 women (77.9%; 95% CI 72.8, 82.5%); the remaining 13.4% of women who aborted did so after a delay of 23.5 +/- 9.8 days (median 23 days, range 10-45). Vaginal bleeding lasted an average of 15 and 11 days in immediate and delayed-success abortions, respectively. Complete abortion rates decreased linearly with increasing body surface area. After methotrexate and misoprostol administration, nausea was reported in 37% and 33%, vomiting in 11% and 18%, diarrhea in 12% and 18%, and subjective fever or chills in 15% and 31% of subjects, respectively. Oral methotrexate followed by vaginal misoprostol is effective for abortion and represents an acceptable alternative to intramuscular methotrexate in regimens for medical abortion.

Relationship between body size, fill volume, and mass transfer area coefficient in peritoneal dialysis.

A peritoneal dialysate fill volume of 2 L has become the standard of clinical practice, but the relationships between body size, fill volume, and mass transfer area coefficient (KoA) have not been well established. These relationships were studied in 10 stable peritoneal dialysis patients who underwent six peritoneal equilibration studies (2 h each) at fill volumes of 0.5, 1, 1.5, 2, 2.5, and 3 L. The concentration-time profiles for urea, creatinine, and glucose were measured at each fill volume, and residual volumes were calculated from the preceding dwell period. A modified Henderson equation was used to calculate the KoA for the three solutes as a function of fill volume. By normalizing the KoA for each solute to the value at 2 L, the data for all three solutes collapsed onto the same trend line when plotting the normalized KoA versus dialysate volume. Between 0.5- and 2-L fill volumes, the average normalized KoA increases in an almost linear fashion, its value almost doubling over this range. Between 2- and 3-L fill volumes, there is less than a 10% change in the normalized KoA. However, fill volumes for peak urea KoA were found to increase with increasing body surface area (R = 0.76), being around 2.5 L for an average-sized patient and increasing to between 3 and 3.5 L for body surface areas > 2 m2. To maximize solute transport, these relationships between body size, volume, and KoA should be considered when choosing fill volumes for continuous ambulatory peritoneal dialysis and automated peritoneal dialysis and when deciding reserve and tidal volumes for tidal peritoneal dialysis.

Effect of aging on peak systolic left ventricular wall stress in normal subjects

Studies of cardiac mechanics in compensated heart muscle suggest that muscle hypertrophy is stimulated by long-term increases in peak myocardial wall stress. 1–6 Conditions leading to either chronic left ventricular (LV) pressure or volume overload generally result in an increase in LV wall stress (expressed as force per unit area). Increased systolic stress results in decreased LV performance unless compensatory hypertrophy develops to normalize systolic wall stress. Measurements of LV wall stress in patients with chronic LV volume or pressure overload should provide an excellent index of cardiac compensation that could be followed serially to permit detection of early myocardial decompensation such as an abnormal increase in wall stress due to inadequate hypertrophy. 4–6 The objectives of this study were to examine the relation of LV peak systolic wall stress to age and body surface area in normal subjects and to establish the normal range of values for LV peak systolic stress, taking age and body surface area into account. We have shown that in normal subjects, LV wall thickness increases with increasing age and body surface area, while LV internal dimensions decrease slightly with aging, but increase with increasing body surface area. 7–9 To determine the effect of age and body surface area on LV peak systolic (meridional) wall stress, we analyzed M-mode echocardiographic data previously recorded in an adult population without evidence of cardiovascular disease. 7–9

Differential thermosensor control of thermoregulatory grooming, locomotion, and relaxed postural extension.

The rat displays three behaviors when surface and/or deep body temperatures rise above their normal levels: grooming, which spreads saliva over the fur to cool by evaporation; locomotion, which results in escape to a cooler environment; and relaxed postural extension, which reduces heat production by muscle activity and increases heat dissipation by increasing body surface area. Each of these behaviors can be elicited in pure or nearly pure form by localized warming of thermosensors in different brain areas. In addition, localized warming of superficial and deep peripheral thermosensors elicits grooming and locomotion, but little or no postural extension. Because of the marked differences in the behaviors induced by localized warming of different sets of thermosensors, it is concluded that sensors are linked to the effector mechanisms for these behaviors by relatively separate and independent pathways rather than a master controller through which sensory signals are integrated to produce a unitary error signal that drives all responses. When more generalized hyperthermia in natural heat stress situations affects mainly superficial thermosensors, as during the initial phase of exposure to ambient heat, grooming and locomotion are predominant and extension is absent or weak. When deep hyperthermia is predominant and superficial hyperthermia is relatively weak, as occurs after escape from ambient heat to thermoneutrality or during and following exercise in a thermally neutral environment, the resulting predominant activation of deep sensors elicits marked postural extension, but little or no grooming or locomotion. When both superficial and deep sensors are hyperthermic, as in the later stages of exposure to ambient heat, all three behaviors are present, although locomotion is somewhat greater and grooming is somewhat less than during predominantly superficial hyperthermia, and extension is somewhat less than during predominantly deep hyperthermia. As a consequence, grooming is maximal during predominantly superficial hyperthermia, locomotion during mixed deep and superficial hyperthermia, and extension during predominantly deep hyperthermia. It is concluded that the relatively fractionated control of the rat's thermoregulatory behaviors by different groups of central and peripheral thermosensors makes possible a differentiation of responses to different distributions of hyperthermia between superficial and deep sensors that optimizes cost-benefit trade-offs in different kinds of heat stress.

Cardiac Dimensions in Elite Young Track Athletes

The purpose of the study was to compare young sprint and distance runners for changes in their cardiac dimensions with increased age (10–17 years) or body surface area (1–2 m2). Echocardiographic dimensions were obtained on 73 male track athletes competing in the 1983 National Age Group Track and Field Association championships. Each group of athletes was also compared with a hypothetical normal population (matched for weight and age) generated from prediction equations derived by Henry, Gardin, & Ware (1980). The cardiac dimensions examined were: Left ventricular internal diameter, left ventricular posterior wall thickness, and interventricular septum thickness. The male distance runners (n = 38) had a significantly greater increase in left ventricular posterior wall thickness and interventricular septum thickness with increasing age or increasing body surface area compared to the sprinters (n = 35) or compared to the predicted normal population. The left ventricular internal diameter was not significant...

The broadly based pericardial flap: A tissue for atrial wall replacement that grows

The repair of many congenital heart anomalies would be facilitated by a tissue replacement for the atrial wall or pulmonary artery which would grow with the child. Such a tissue has not previously been identified. In 12 puppies a broadly based flap of pericardium was sutured over the right atrial free wall. The atrial wall was excised from beneath the flap. In four animals the flap was then cut away from its pericardial attachments superiorly, inferiorly, and along the phrenic nerve, leaving an autogenous pericardial patch. In the other eight animals the flap was left intact, allowing retention of neural and vascular supply. The animals were put to death 263 +/- 23 days later. In four animals having a pericardial patch, the area of the patch did not increase (94% of original size, NS) despite an increase in body surface area (BSA) to 169% (p less than 0.05) of original BSA. In eight animals with a pericardial flap, the area of the flap increased to 214% (p less than 0.01) of the original size with an increase in BSA to 199% (p less than 0.01) of original BSA. The flap size index (size/BSA) increased to 109% of the original index while the patch size index decreased to 54% of the original, a significant difference (p less than 0.01). The broadly based pericardial flap grew in a manner parallel to BSA increase in these puppies.

Spectral analysis of heart sounds: Relationships between some physical characteristics and frequency spectra of first and second heart sounds in normals and hypertensives

Frequency analysis of heart sounds has been gaining recognition as a possible indicator of several heart and valve diseases, although a comprehensive study of normal heart sounds has not been published. Relating the frequency content of normal heart sounds to certain physical characteristics surrounding the generation of these sounds could lead to a valuable diagnostic tool and give a better understanding of the mechanism of heart sounds production. In this study, the first and second heart sounds from seventy-four normal, and seven hypertensive volunteers were recorded, digitized and analysed using a Fast Fourier Transform algorithm. Statistical analysis was used to relate physical characteristicss (sex, blood pressure, and body surface area) of the subjects to the frequency content of normal heart sounds and to compare normal and hypertensive heart sounds. Statistical analysis showed that the major concentration of energy, for both first heart sound (S1) and second heart sound (S2), is below 150 Hertz (Hz) which may indicate that both sounds are caused by vibrations within the same structure, possibly the entire heart. However S2 spectra have greater amplitude than S1 spectra above 150 Hz, which may be due to vibrations within the aorta and pulmonary artery. Relationships observed between body surface area, sex, blood pressure, and the frequency content of heart sounds indicate that as heart size increases, the amplitude of the frequency coefficients above 150 Hz decreases. These observations were more identifiable in the S1 spectra than in the S2 spectra, possibly because the S2 higher frequency components may mask subtle changes in the S2 spectra caused by heart size changes. However, when the changes in heart size are significant, as in hypertension or increased body surface area, trends in the S2 spectra can be observed.

CARDIAC DIMENSIONS IN ELITE YOUNG TRACK ATHLETES

The purpose of the study was to compare young sprint and distance runners for changes in their cardiac dimensions with increased age (10–17 years) or body surface area (1–2 m2). Echocardiographic dimensions were obtained on 73 male track athletes competing in the 1983 National Age Group Track and Field Association championships. Each group of athletes was also compared with a hypothetical normal population (matched for weight and age) generated from prediction equations derived by Henry, Gardin, & Ware (1980). The cardiac dimensions examined were: Left ventricular internal diameter, left ventricular posterior wall thickness, and interventricular septum thickness. The male distance runners (n = 38) had a significantly greater increase in left ventricular posterior wall thickness and interventricular septum thickness with increasing age or increasing body surface area compared to the sprinters (n = 35) or compared to the predicted normal population. The left ventricular internal diameter was not significant...

Serial left ventricular wall measurements in Duchenne's muscular dystrophy

In 19 patients with Duchenne's muscular dystrophy, left ventricular wall thickness in end-systole and end-diastole was determined serially every 12 months by echocardiography and compared with ventricular wall growth in normal subjects. In the normal subjects, left ventricular wall thickness increased linearly with increasing body surface area. A control group of wheelchair-bound patients with a variety of neurologic disorders, although not followed serially, had a distribution of end-diastolic wall thickness values similar to that of the normal subjects. In patients with muscular dystrophy, wall thickness increased linearly with respect to body surface area for some time and then began to thin. The time at which thinning began was not directly related to age, although it was more common in older than in younger patients. Those patients who died demonstrated marked deviation from normal wall growth. Free wall thinning is probably a result of fibrosis and loss of myofibrils.

Growth of the abdominal aorta and renal arteries in childhood.

A review of unselected abdominal aortograms of 45 children showed that linear growth of the abdominal aorta increased with increasing body surface area rather than with age. The sum of the diameter of both iliac arteries increased more rapidly than that of the adjacent aorta. The length of the normal kidney increased in linear proportion to both the body surface area and the diameter of its corresponding renal artery.

Regression of valvular pulmonary stenosis.

Eight patients with mild to moderate valvular pulmonary stenosis underwent serial physiological studies before surgical intervention. Average pulmonary valve area at the initial study was 0.59 cm.2 and at the second study (average 7.8 years later) was 1.09 cm.2, resulting in an average increase of 0.49 cm.2 (p greater than 0.05). In normal subjects during early years the pulmonary valve area increases linearly with age and with increasing body surface area. Though patients with valvular pulmonary stenosis have smaller valve orifices, they also show an increase in valve size with increasing age and with increasing body growth. The greatest increase in valve area was observed in 4 patients (all under age 6) in whom body surface area increased more than 70 per cent.

Continuous determination of oxygen uptake in sedated infants and children during cardiac catheterization

The variation of oxygen uptake during cardiac catheterization was studied in 98 sedated infants and children by a flow-through technic which requires no direct patient contact or cooperation, does not interfere with cardiac catheterization, and permits continuous on-line determination of oxygen uptake. During sedated sleep O 2 uptake averaged 102 ± 51 ml./min. or 154 ± 26 ml./min. per M 2. For this limited sample population O 2 uptake was linearly related to body surface area, age, height and weight. O 2 uptake per M 2 decreased with increasing body surface area and was relatively greater in underweight children. The awake state and activity resulted in significant increases of O 2 uptake even in restrained children. The method provides accurate measurements of O 2 uptake and can be used routinely in infants.

Evaporative Heat Loss Mechanisms of the Newborn Calf, Bos Taurus

SUMMARY Measurements have been made of cutaneous moisture loss, respiratory rate and rectal temperature of twenty-four male Ayrshire calves aged from 10 hours to 18 months, during exposure to an environment of 40°C dry bulb and 25.5°C wet bulb. The rate of moisture loss per unit area from the skin, and the respiratory rate of the newborn was higher than that of the older animals, but the increase in body temperature due to heat exposure was similar. The amount of moisture produced per sweat gland increased with age, in proportion to the increase in body surface area. It is concluded that mechanisms concerned with evaporative heat loss in the calf are well-developed at birth.

The effect of ageing on the total volumes of the A and B cells in the islets of Langerhans of the rat.

ABSTRACT In previous attempts to determine the total volumes of the A and the B cells in the islets of Langerhans, separately, no regard was paid to possible differences between the individual mean cell volumes of the two cell types. In the rat it is shown that considerable error results if this fact is neglected, since the mean individual volumes of the B cells were more than three times as large as those of the A cells. By combining determinations of the total islet volume with point sampling, caryometry and differential cell counts, the separate total A and B cell volumes have been estimated in 40 rats of different ages: new-born, 5, 100 and 480 days old. While the B/A cell number ratio was significantly lower at birth than at 5 days, a comparison of the total volumes of the two cell types showed that their volume proportions were the same at both periods. This was explained by the changes in the cell number ratio being compensated by changes in the individual mean cell volume, the total volume ratio thus being unaltered. The percentage volume contribution of the A cells was found to increase with age. In the new-born rats the volume was 11.28 percent compared with 13.57 percent in the oldest animals. An analysis of variance of all four age groups confirmed that real differences existed. On the other hand a statistically significant decrease, with age, in the relative volume of the B cells was noted. In new-born animals the value was 83.16 percent compared with 76.82 percent in 480 days old animals. The relative volume of the residual islet constituents (other than A and B cells) was proportionately most affected by increase in age, the percentage contribution to the total islet volume being almost doubled in 480 days old animals as compared with the two youngest age groups. If both the total A and B cell volumes were expressed in relation to body, liver and pancreatic weights, the quotients became greatly reduced with advancing age. An exception occurred in the 480 days old animals, in which the quotients were in all cases significantly higher than in the 100 days old rats. The increase in body surface area reflected the changes in the total volumes of both A and B cells in relation to ageing considerably better than did the organ and body weights. In this case too, however, the quotient for 480 days old animals was significantly higher than in the next youngest age group. Correlation calculations, made on each individual age group, showed that a strongly positive correlation existed between the total A and cell volumes, particularly in the youngest animals. On the other hand, in no age group was there a correlation between the total volumes of either of the two cell types and the pancreatic weight.