Distribution of normal saline and 5% albumin infusions in cardiac surgical patients.

OBJECTIVE: To determine the relative distribution of fluid within the extracellular fluid volume (ECFV) and the effect on oxygen delivery after infusing either normal saline or 5% albumin in cardiac surgical patients. DESIGN: Prospective, randomized, unblinded, interventional study. SETTING: Cardiac surgical intensive care unit in a 450-bed teaching hospital. PATIENTS: Postoperative cardiac surgical patients (n = 40). INTERVENTIONS: Infusion of either normal saline or 5% albumin to a hemodynamic end point determined by the patient's clinician. MEASUREMENTS AND MAIN RESULTS: Plasma volume (PV), ECFV, cardiac index, and arterial oxygen content were measured immediately before (baseline) and after each fluid infusion. PV and ECFV were measured by dilution of (131)I-albumin and [(35)S]sodium sulfate, respectively. Interstitial fluid volume (ISFV) was calculated as ECFV - PV. Baseline values for PV, ISFV, ECFV, and oxygen delivery index did not differ between treatment groups. Infusion of normal saline and 5% albumin increased PV by 9 +/- 23% and 52 +/- 84% of the volume infused, respectively (p <.05), whereas there was no significant difference between saline and albumin in the change in ISFV per volume infused. Only 5% albumin significantly increased cardiac index, although oxygen delivery did not change significantly after either infusion. CONCLUSIONS: In postoperative cardiac surgical patients, infusion of 5% albumin is approximately five times as efficient as a PV expander but has comparable effects on changes in ISFV and oxygen delivery relative to normal saline.

Alveolar epithelial integrity in athletes with exercise-induced hypoxemia.

The effect of incremental exercise to exhaustion on the change in pulmonary clearance rate (k) of aerosolized (99m)Tc-labeled diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) and the relationship between k and arterial PO(2) (Pa(O(2))) during heavy work were investigated. Ten male cyclists (age = 25 +/- 2 yr, height = 180.9 +/- 4.0 cm, mass = 80.1 +/- 9.5 kg, maximal O(2) uptake = 5. 25 +/- 0.35 l/min, mean +/- SD) completed a pulmonary clearance test shortly (39 +/- 8 min) after a maximal O(2) uptake test. Resting pulmonary clearance was completed >/=24 h before or after the exercise test. Arterial blood was sampled at rest and at 1-min intervals during exercise. Minimum Pa(O(2)) values and maximum alveolar-arterial PO(2) difference ranged from 73 to 92 Torr and from 30 to 55 Torr, respectively. No significant difference between resting k and postexercise k for the total lung (0.55 +/- 0.20 vs. 0. 57 +/- 0.17 %/min, P > 0.05) was observed. Pearson product-moment correlation indicated no significant linear relationship between change in k for the total lung and minimum Pa(O(2)) (r = -0.26, P > 0.05). These results indicate that, averaged over subjects, pulmonary clearance of (99m)Tc-DTPA after incremental maximal exercise to exhaustion in highly trained male cyclists is unchanged, although the sampling time may have eliminated a transient effect. Lack of a linear relationship between k and minimum Pa(O(2)) during exercise suggests that exercise-induced hypoxemia occurs despite maintenance of alveolar epithelial integrity.

Time-optimized carbon-14 breath test for Helicobacter pylori contamination of the stomach.

PURPOSE: Evidence that Helicobacter pylori plays an important role in peptic ulcer disease has generated intense interest in the development of various screening strategies. H. pylori can be detected high sensitivity and specificity by the noninvasive carbon-14 (C-14) breath test. METHODS: The authors assessed the cost-effectiveness of screening patients with dyspepsia before endoscopy. Thirty-four patients with dyspepsia were evaluated by the C-14 breath test, and then the authors reevaluated the criteria for the diagnosis of H. pylori. The discrimination obtained by using values of cumulative radioactivity or specific activity of breath samples collected between 10 and 60 minutes were studied. RESULTS: The main feature of H. pylori colonization in the stomach was a rapid increase of carbon dioxide in expired breath within 10 minutes after oral administration of C-14. Performance of the test was equally excellent for 10-minute values and 60-minute cumulative excretion. CONCLUSION: The C-14 breath test is a reliable method for diagnosing H. pylori colonization in the stomach, and the accuracy is not compromised by reducing the sample time to maintain better cost-effectiveness and patient acceptance.

Distribution of normal saline and 5% albumin infusions in septic patients.

OBJECTIVE: To determine the relative distribution of fluid within the extracellular fluid volume (ECFV) after infusing either normal saline or 5% albumin in septic, critically ill patients. DESIGN: Prospective, randomized, unblinded, interventional study. SETTING: Intensive care unit in a 450-bed, tertiary care, teaching hospital. PATIENTS: Septic, critically ill patients (n = 18). INTERVENTIONS: Infusion of either normal saline or 5% albumin to a hemodynamic end point determined by the patient's clinician. MEASUREMENTS AND MAIN RESULTS: Plasma volume (PV), ECFV, cardiac index, and arterial oxygen content were measured immediately before (baseline) and after each fluid infusion. PV and ECFV were measured by dilution of 131I-albumin and 35S sodium sulfate, respectively. Interstitial fluid volume (ISFV) was calculated as ECFV - PV. Baseline values for PV, ISFV, ECFV, and oxygen delivery index did not differ between treatment groups. Infusion of normal saline increased the ECFV by approximately the volume infused, and the expansion of the PV to ISFV was in a ratio of 1:3. Infusion of 5% albumin increased the ECFV by double the volume infused, with both the PV and ISFV expanding by approximately equal amounts. Oxygen delivery index did not increase after either infusion due to the effect of hemodilution. CONCLUSION: Expansion of the ECFV in excess of the volume of 5% albumin infused suggests that fluid may move from the intracellular fluid volume to the ECFV in septic patients who receive this fluid.

Changes in body composition and fat distribution after short-term weight gain in patients with anorexia nervosa.

The most commonly described psychologic abnormality associated with anorexia nervosa is a distorted perception of body weight and shape. This perception may contribute to the anorexic patient's resistance to gaining weight even when it is a medical necessity. The purpose of this study was to assess body-composition and fat-distribution changes after short-term weight gain in 26 female anorexia nervosa patients 27.6 +/- 6.6 (mean +/- SD) y of age, with a body mass index (BMI; in kg/m2) of 16.5 +/- 1.9. They participated in a refeeding protocol both as inpatients (n = 21) and as outpatients (n = 5) until they achieved maximum weight gain. Body-composition and fat-distribution changes were measured by using dual-energy X-ray absorptiometry (DXA) and skinfold thickness and circumference measurements. A mean weight gain of 6.7 +/- 5.3 kg (P < 0.001) was observed, which included significant increases in body fat (P < 0.001), lean body mass (P < 0.05), and bone mineral content (P < 0.01), with body fat being the component that increased the most. When measured by DXA, fat gain was not significantly different among the three central regions: subscapular, 1.7 +/- 1.2 kg; waist, 1.8 +/- 1.3 kg; and thigh, 1.5 +/- 1.0 kg (P = 0.10). Thus, although fat was the largest component of the weight gained, there was no preferential fat deposition in any one area and the female gynoid body shape was maintained.

Pulmonary transit time and diffusion limitation during heavy exercise in athletes.

To investigate relationships between pulmonary transit times (PTT) and pulmonary diffusion limitation during exercise, 10 high aerobic capacity athletes (VO2max = 5.15 +/- 0.52 l.min-1) who had multiple inert gas elimination analysis evidence suggestive of diffusion disequilibrium were studied at rest and maximal exercise. Diffusing capacity for oxygen (DLO2) was calculated from the inert gas data. First pass radionuclide angiography was performed using 99mTechnecium labeled erythrocytes and whole lung PTT and pulmonary blood volume (PBV) were calculated. PTT decreased from 9.32 +/- 1.41 sec at rest, to 2.91 +/- 0.30 sec during exercise and was correlated with diffusion limitation suggested by the inert gases (r = -0.58, P < 0.05). PBV increased during exercise to over 25% of whole blood volume and correlated with DLO2 (r = 0.82, P < 0.01). These data suggest that diffusion limitation is related to shortened PTT in athletes and that maximal recruitment of PBV may defend against diffusion limitation.

Effect of cardiac stabbing on ventricular function: evaluation by radionuclide angiography.

OBJECTIVE: To determine whether cardiac stab wounds cause early ventricular dysfunction. DESIGN: Retrospective case series over 7 years. SETTING: University-affiliated teaching hospital. PATIENTS: Nine consecutive survivors of cardiac stab wounds. INTERVENTIONS: Postoperative radionuclide angiography performed in all patients between 1 and 13 days after injury. MAIN OUTCOME MEASURES: Information on the patient's clinical presentation and hospital course was obtained from the patient's charts and correlated with ventricular function as measured by the right and left ventricular ejection fractions (RVEF and LVEF). RESULTS: Cardiac injuries consisted of isolated right (five) and left (three) ventricular lacerations, and one biventricular laceration. Three patients had perioperative dysrhythmias (two ventricular, one atrial), and nonspecific electrocardiographic changes occurred in seven patients. Six patients had postoperative complications: pericarditis in three and pneumonia, pulmonary thromboembolism and abdominal wound dehiscence in one each. The LVEF was normal in all patients. Although none had clinically apparent cardiac dysfunction at the time of radionuclide angiography, six patients had a reduced RVEF (less than 0.45). All patients remained asymptomatic at the time of discharge from hospital (median 12 days postoperatively). In two of the six patients who had a reduced RVEF, one had a normal RVEF 2 months later; the other had a near-normal RVEF (0.43) but had persistent right ventricular enlargement 7 months later. Both were asymptomatic. CONCLUSIONS: Although a reduced RVEF is common in survivors of cardiac stab wounds, the reduction is small and is not associated with clinically apparent cardiac dysfunction.

Reproducibility of plasma and extracellular fluid volume measurements in critically ill patients.

Plasma and extracellular fluid (ECF) volume measurements may provide valuable complementary data to the hemodynamic measurements currently used to compare fluid infusions in critically ill patients. To assess the reproducibility of plasma and extracellular fluid volume measurements in critically ill patients, we injected 131I-labeled albumin (10 microCi) and 35S-sodium sulfate (50 microCi), respectively, into 15 stable patients on two occasions 150 min apart. Plasma was sampled at 20, 30, and 40 min after each injection and the volume of distribution of each radioisotope was calculated from the extrapolated zero time counts. We found that plasma and ECF volume did not differ significantly between the first (42.4 +/- 4.7 ml/kg and 186 +/- 39 ml/kg) and second (42.8 +/- 5.5 ml/kg and 193 +/- 48 ml/kg) measurements. Specifically, the mean difference between the two measurements was 0.4 +/- 3.2 ml/kg and 7 +/- 17 ml/kg respectively. We conclude that measurements of plasma and ECF volume are reproducible over 150 min in stable critically ill patients.

The effect of cigarette smoking on neutrophil kinetics in human lungs.

Neutrophils may play a part in the pathogenesis of the centrilobular emphysema associated with cigarette smoking. The capillary bed of the lungs concentrates neutrophils approximately 100-fold with respect to erythrocytes, producing a large pool of marginated cells. We examined the effect of cigarette smoking on the kinetics of this pool of cells, using 99mTc-labeled erythrocytes to measure regional blood velocity and 111In-labeled neutrophils to measure the removal of neutrophils during the first passage through the pulmonary circulation, their subsequent washout from the lungs, and the effect of local blood velocity on the number of neutrophils retained in each lung region. We observed no difference in these measurements between subjects who had never smoked (n = 6) and smokers who did not smoke during the study (n = 12). However, subjects who did smoke during the study (n = 12) had a significantly slower rate of washout of radiolabeled neutrophils from the lung (0.08 +/- 0.04 of the total per minute, as compared with 0.13 +/- 0.06 in smokers who did not smoke during the experiment and 0.14 +/- 0.08 in non-smokers) (P = 0.02). We also observed an increase in the regional retention of labeled neutrophils with respect to blood velocity in 5 of the 12 subjects who smoked during the study, but in none of the other subjects. We conclude that the presence of cigarette smoke in the lungs of some subjects increases the local concentration of neutrophils, and suggest that the lesions that characterize emphysema may be a result of the destruction of lung tissue by neutrophils that remain within pulmonary microvessels.

Regional pulmonary transit times in humans.

We measured the frequency distribution of erythrocyte (RBC) transit times in resected lobes of lungs in eight human subjects undergoing thoracotomy for peripheral lung tumors. RBC transit times were measured by the injection of radiolabeled blood flow and volume markers, which were counted in samples from the resected lung. In five of these subjects, the measurements from the resected lung were compared with preoperative measurements of the transit times of radiolabeled RBCs with a gamma camera-computer system. Time-activity curves from the cardiac chambers and the lung or its regions were obtained from which transit times were calculated by the centroid and deconvolution techniques. The reproducibility of transit times measured by this technique was assessed in another eight normal subjects, after sequential bolus injections of radiolabeled cells. The mean transit time of the upper lung region was longer (5.1 +/- 0.5 s) than that of the lower (4.1 +/- 0.6 s, P less than 0.05) in the preoperative study. Similarly, the mean transit time of the upper lung slice was longer (5.5 +/- 0.3 s) than that of the lower slice (3.8 +/- 0.3 s, P less than 0.05) in the resected lung specimens. We conclude that there was good agreement between these techniques and that there are long transit times in the upper regions of human lungs.

Nuclear medicine.

Nuclear medicine utilizes radioisotopes to diagnose and in some cases treat disease. Modern instruments can image their accumulation in an organ and provide quantitative data when indicated. The strength of these procedures is in the unique physiologic information they provide, rather than the presentation of precise anatomic detail.

Macrophage accumulation of inhaled gallium-67 citrate in normal lungs.

Injected 67Ga has been used extensively to monitor inflammatory processes in the peripheral lung. We hypothesized that inhaled 67Ga may be useful in marking early airway inflammation in smokers. Eight nonsmokers and eight smokers breathed a 67Ga aerosol and imaging was performed immediately and 24 and 96 hr later. Approximately two-thirds of the initial dose remained in the lungs at 24 hr in both groups and no difference was seen between the groups. Only a very slight decrease was seen in both groups at 96 hr suggesting the gallium becomes bound to lung tissue or to cells not rapidly removed from the lungs. Autoradiography was performed on tissue from two smoke-exposed guinea pigs and two human patients undergoing resection surgery who breathed the gallium aerosol 24 hr prior to tissue removal. Silver grain accumulations were seen only over macrophages. We conclude that macrophage associated accumulation of 67Ga occurs in healthy lungs, and that it is not feasible to use aerosolized gallium to assess airway inflammation in smokers.