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Biomedical subjects

J E Brimm

Publications and source records attributed to J E Brimm.

14 recordsLinked to original sources
PubMed1987

End-tidal carbon dioxide as a measure of arterial carbon dioxide during intermittent mandatory ventilation.

To determine if end-tidal carbon dioxide tension (PETCO2) is a clinically reliable indicator of arterial carbon dioxide tension (PaCO2) under conditions of heterogeneous tidal volumes and ventilation-perfusion inequality, we examined the expiratory gases of 25 postcardiotomy patients being weaned from ventilator support with intermittent mandatory ventilation. Using a computerized system that automatically sampled airway flow, pressure, and expired carbon dioxide tension, we were able to distinguish spontaneous ventilatory efforts from mechanical ventilatory efforts. The PETCO2 values varied widely from breath to breath, and the arterial to end-tidal carbon dioxide tension gradient was appreciably altered during the course of several hours. About two-thirds of the time, the PETCO2 of spontaneous breaths was greater than that of ventilator breaths during the same 70-second sample period. The most accurate indicator of PaCO2 was the maximal PETCO2 value in each sample period, the correlation coefficient being 0.768 (P less than 0.001) and the arterial to end-tidal gradient being 4.24 +/- 4.42 mm Hg (P less than 0.01 compared with all other measures). When all values from an 8-minute period were averaged, stability was significantly improved without sacrificing accuracy. We conclude that monitoring the maximal PETCO2, independent of breathing pattern, provides a clinically useful indicator of PaCO2 in postcardiotomy patients receiving intermittent mandatory ventilation.

Carbon Dioxide↗
PubMed1986

Accuracy of radiographic lung volume using new equations derived from computed tomography.

This study compared radiographic measurements of regional lung volume with corresponding physiologic measurements. The database included 48 normal, supine adults who had previously undergone spirometry and helium-dilution lung volume measurements to determine physiologic functional residual capacity (G-FRC) and total lung capacity (G-TLC). Chest x-rays had also been obtained for these subjects at functional residual capacity and total lung capacity. To calculate radiographic lung volumes at functional residual capacity and total lung capacity (R-FRC and R-TLC, respectively), we traced the lung outline from the chest x-ray, and digitized each outline. We then calculated total and regional lung volumes, using equations previously derived from computed tomographic scans. R-FRC and R-TLC were closely correlated (r = 0.973, maximum SEE 6.8%) with G-FRC and G-TLC, whether or not separate equations were used for regions below the diaphragm. Using only maximum anteroposterior diameter reduced the r-value to 0.957 (SEE 9.6%). The accuracy of our method of radiographic measurement of regional lung volume was validated by the concurrence between the physiologic and radiographic measurements.

Adult↗
PubMed1986

Estimation of the volume of lung below the left atrium using computed tomography.

Gravity has significant effects on the microvascular pressure in the lungs and thus on regional fluid filtration in the lungs. Below the level of the heart, gravity increases the microvascular pressure with respect to the left atrial pressure; above the level of the heart, microvascular pressure is less than atrial pressure. To assess the contribution of gravity to fluid filtration in the lungs independent of left-heart filling pressure, the distribution of lung volume above and below the left atrium must first be determined. To permit calculation of the contribution of hydrostatic pressure per unit of lung volume, 26 computed tomographic scans of the entire chest were traced and measured, marking the level of the center of the left atrium (LAL) on each slice. The intrathoracic volume above and below the left atrium was measured by multiplying scan slice thickness by the area of the lung above or below the LAL measured on each scan slice. On 16 scans, intrathoracic volumes of 1-cm horizontal layers of lung above and below the LAL were also calculated by measuring corresponding segments of the transverse scan slices. The calculations indicate that in the supine posture more lung is dependent than when upright, and that elevation of a patient to 30 degrees reduces the volume of lung below the LAL nearly as much as does the upright posture.

Heart Atria↗
PubMed1986

Automated documentation and analysis of burn size.

The digital recording and processing of information on burn size provides a useful adjunct to the care of patients with burn injuries in the critical care setting. Record keeping is improved and accuracy is enhanced using a simple, portable system based on the widely available IBM Personal Computer. Diagramming burns on a graphic outline of a human body with color coding of burn depth produces a visual representation of the burned patient. Computations of areas of burn are automatically produced from the graphic images.

Burns↗
PubMed1985

A personal computer system for testing gas exchange, heart, lungs, ventilatory pump.

This paper reports the development of a computer system for testing gas exchange and lung function in the ICU. The essence of the system is a software package that uses an IBM personal computer for data processing and analysis. Front end hardware is modular, as is software, so that portions or all of the system can be used. The system provides measurements of lung mechanics work, functional residual volume, spirometry, oxygen uptake, carbon dioxide output, lung water, blood gas interpretation, hemodynamics. Reports are provided by standard data base manager and so are easily customized.

Computers↗
PubMed1983

Hypertonic sodium lactate versus lactated ringer's solution for intravenous fluid therapy in operations on the abdominal aorta.

Fifty-eight patients who were to undergo aortic reconstruction were prospectively randomized into two groups to compare the effects of perioperative fluid replacement with isotonic and hypertonic crystalloid solutions. Blood loss was replaced with packed red blood cells, and additional fluid was given as either Ringer's lactate solution (RL, 130 mEq sodium/L, 274 mOsm/L) or a hypertonic balanced salt solution (HSL, 250 mEq sodium/L, 514 mOsm/L). Fluid was administered to maintain the cardiac filling pressure within 3 torr of the preoperative level and the cardiac output (CO) at or above the preoperative level. The groups were similar with respect to age, preexisting disease, duration of operation, and operative blood loss. During the operation, the RL group required 9.5 +/- 0.8 L of fluid, whereas the HSL group required 4.5 +/- 0.3 L (P less than 0.001). Pulmonary, cardiac, and renal functions were adequately maintained in both groups. There were no significant differences between the groups with regard to CO, urine output, or creatinine clearance during the operation and early postoperative period. Postoperatively, the intrapulmonary shunt was 20 +/- 1% in the RL group and it was 16 +/- 1% in the HSL group (P less than 0.05). The amount of sodium infused and the cumulative sodium balance at the completion of the study period were similar in both groups. Serum sodium and osmolarity were significantly greater in the HSL group (P less than 0.001), reaching a maximum of 151 +/- 1 mEq/L and 305 +/- 2 mOsm/L, respectively. Two patients in the HSL group had a persistent elevation in serum osmolarity (greater than 320 mOsm/L) during operation, for which they received RL for the balance of the resuscitation. There were no complications that could be attributed to the hypertonicity of the solution. HSL is effective for resuscitation of patients with extracellular fluid deficit and is safe provided that the serum sodium and osmolarity are monitored during periods of large volume administration.

Aorta, Abdominal↗
PubMed1981

Prospective study of portasystemic encephalopathy after emergency portacaval shunt for bleeding varices.

A prospective study of the development of encephalopathy was undertaken in 180 patients undergoing emergency portacaval shunt for bleeding esophageal varices between 1963 and 1978. The incidence of preoperative encephalopathy was 32 percent. Postoperatively, encephalopathy developed in 31.5 percent of 95 survivors and was severe in 7 percent of those survivors. Encephalopathy developed in most patients in the first and second follow-up years; in 10 year survivors, encephalopathy was virtually absent. Encephalopathy was more likely to occur in patients with encephalopathy at the time of shunt and in those who returned to alcoholism after shunt. Most encephalopathic episodes were precipitated by dietary indiscretion, often associated with alcoholism. Careful follow-up with attention to dietary compliance and abstinence from alcohol should make the risk of encephalopathy acceptable in relation to the unquestionable benefits of portacaval shunt in reducing the risk of variceal hemorrhage.

Alcoholism↗
PubMed1981

Complications of the flow-directed pulmonary artery catheter: A prospective analysis in 219 patients.

In order to determine and analyze the complication rate of the insertion and maintenance of the balloon-tipped, flow-directed pulmonary artery catheter (PAC), the authors prospectively studied the use of 320 catheters in 219 critically ill patients. Mean patient age was 53 +/- 1 years, and 36% had a history of cardiovascular disease. Mean duration of catheterization averaged 76 +/- 3 h. Major complications occurred in 3% of catheterizations. These included six pneumothoraces; three arrhythmias requiring treatment, one of which was fatal; and one subclavian vein thrombosis. Site complications occurred more frequently in catheters maintained longer than 72 h. These findings suggest that, when indicated in the care of critically ill patients, the properly placed and maintained PAC has an acceptably low morbidity and mortality rate, particularly when used for 72 h or less.

Arrhythmias, Cardiac↗
PubMed1980

Prevention by whole pancreas transplantation of glomerular basement membrane thickening in alloxan diabetes.

Serial thickness measurements of the glomerular basement membrane were performed over a 24-month period in four groups of inbred male Lewis rats. Group I consisted of normal animals age-matched to the remaining experimental groups. In groups II, III, and IV, diabetes was induced by intravenous alloxan (42 to 44 mg/kg). Group II was subsequently untreated. One week after induction of diabetes, groups III and IV received vascularized isografts of the pancreas and duodenum or duct-ligated pancreas alone, respectively. Animals in all groups were killed monthly and X 11,000 electron photomicrographs prepared of the kidney. The thickness of the glomerular basement membrane was measured by a quantitative morphometric technique. Untreated diabetic animals developed significant thickening of the basement membrane when compared to normal animals and the differences remained significant throughout life. Animals undergoing pancreas transplantation were completely protected from the diabetic changes in the basement membrane and showed no increase in basement membrane thickness when compared to normal animals. Pancreaticoduodenal and duct-ligated isografts offered equal protection against changes in the basement membrane. All groups showed age-related thickening of the basement membrane; this change was accelerated in the untreated diabetic group and normalized in the transplanted rats.

Animals↗
PubMed1979

Predicting the need for prolonged ventilatory support in adult cardiac patients.

Forty-nine cardiac surgical patients had ventilatory function tests and measurements of maximum inspiratory (MIP) and maximum expiratory (MEP) pressures preoperatively. The differences between the values of various function tests were compared for patients requiring less than 24 hours of ventilator support and those requiring more than 24 hours. There was a significant difference in the mean values for the two groups in vital capacity (VC) first-second forced expired volume (FEV) midexpiratory flow between 50 and 75 (MMEF 50--75) and 75--85 percent of expired volume (MMEF 75--85), and MEP. The standard deviations of each of the variables were so large that the clinical usefulness was limited. However, when discriminant analysis was used for more than one variable, the combination of MMEF 75--85 and MEP predicted success or failure to wean in 24 hours correctly in 90 percent of instances. On the basis of these simple tests, patients predicted to succeed should be weaned from ventilator support on recovery from anesthesia. Those predicted to fail should be placed on intermittent mandatory ventilation (IMV) and should be weaned following a planned, logical process.

Adult↗
PubMedDate not supplied

Measuring lung volumes from chest films using equations derived from computed tomography.

Computed tomographic scans show true cross-sectional area of a segment of the chest. Measurement of the cross-sectional area of the lung at several adjacent levels permits calculation of a geometrically defined volume. CT scans from 26 cases were used to derive equations to predict regional volume from measurements which can be obtained from plain PA and lateral chest films. Separate equations were derived for slices above and below the top of the diaphragm. The best correlation between linear dimensions and true volume was obtained with equations that used lung width and antero-posterior (AP) diameter of each scan, maximum AP lung diameter, and relative scan level (apex to base). These equations predicted the volumes of individual slices above the diaphragm with a correlation coefficient (r) of 0.99 on the right, 0.97 on the left. Below top of the diaphragm, r was 0.91 on the right, 0.92 on the left. Total lung volume was predicted with an r of 0.98 (s.e. 4.8%) on the right and 0.97 (s.e. 5.3%) on the left. Using total chest width instead of AP diameter of each slice reduced r to 0.96 for the volume of either lung. This method compares favorably with previous regression or geometric approximation methods for total lung volume and also makes it possible to obtain estimates of portions of lung volume from chest films.

Humans↗
PubMedDate not supplied

Quantitative morphological studies of aging changes in the kidney of the Lewis rat.

Spontaneous aging changes in the kidneys of the rat have been previously described. In the Lewis strain, we performed semiquantitative studies of kidney histology and quantitative studies of glomerular basement membrane thickness and mesangial area in animals aged 6-30 months. There is a progressive increase in glomerular basement membrane thickness and mesangial area throughout the life of the rat. Spontaneous glomerulosclerosis in the Lewis rat does not appear to be as extensive as in other strains. The importance of spontaneous glomerulosclerosis in studies of induced kidney disease is emphasized.

Aging↗