Hypoxic pulmonary vasoconstriction does not contribute to pulmonary blood flow heterogeneity in normoxia in normal supine humans.

We hypothesized that some of the heterogeneity of pulmonary blood flow present in the normal human lung in normoxia is due to hypoxic pulmonary vasoconstriction (HPV). If so, mild hyperoxia would decrease the heterogeneity of pulmonary perfusion, whereas it would be increased by mild hypoxia. To test this, six healthy nonsmoking subjects underwent magnetic resonance imaging (MRI) during 20 min of breathing different oxygen concentrations through a face mask [normoxia, inspired O(2) fraction (Fi(O(2))) = 0.21; hypoxia, Fi(O(2)) = 0.125; hyperoxia, Fi(O(2)) = 0.30] in balanced order. Data were acquired on a 1.5-T MRI scanner during a breath hold at functional residual capacity from both coronal and sagittal slices in the right lung. Arterial spin labeling was used to quantify the spatial distribution of pulmonary blood flow in milliliters per minute per cubic centimeter and fast low-angle shot to quantify the regional proton density, allowing perfusion to be expressed as density-normalized perfusion in milliliters per minute per gram. Neither mean proton density [hypoxia, 0.46(0.18) g water/cm(3); normoxia, 0.47(0.18) g water/cm(3); hyperoxia, 0.48(0.17) g water/cm(3); P = 0.28] nor mean density-normalized perfusion [hypoxia, 4.89(2.13) ml x min(-1) x g(-1); normoxia, 4.94(1.88) ml x min(-1) x g(-1); hyperoxia, 5.32(1.83) ml x min(-1) x g(-1); P = 0.72] were significantly different between conditions in either imaging plane. Similarly, perfusion heterogeneity as measured by relative dispersion [hypoxia, 0.74(0.16); normoxia, 0.74(0.10); hyperoxia, 0.76(0.18); P = 0.97], fractal dimension [hypoxia, 1.21(0.04); normoxia, 1.19(0.03); hyperoxia, 1.20(0.04); P = 0.07], log normal shape parameter [hypoxia, 0.62(0.11); normoxia, 0.72(0.11); hyperoxia, 0.70(0.13); P = 0.07], and geometric standard deviation [hypoxia, 1.88(0.20); normoxia, 2.07(0.24); hyperoxia, 2.02(0.28); P = 0.11] was also not different. We conclude that HPV does not affect pulmonary perfusion heterogeneity in normoxia in the normal supine human lung.

Evidence for enhanced distal tubule sodium reabsorption in chronic salt-depleted dogs.

In order to assess the renal tubular site(s) at which sodium reabsorption is enhanced in chronic sodium-depletion, seven normal dogs, six salt-depleted dogs, and three normal dogs receiving aldosterone were studied during a steady-state water diuresis under Pentothal anesthesia and during progressive hypotonic saline diuresis. For both maintenance of the water diuresis and progressive hypotonic saline diuresis 0.45% NaCl was used. During the steady state water diuresis delivery of sodium to the diluting segment of the nephron as approximated by solute-free water clearance + sodium clearance/glomerular filtration rate (CH2O + CNa/GFR) was significantly lower in salt-depleted dogs compared to normal dogs with or without aldosterone. During progressive hypotonic saline infusion fractional free water excretion (CH2O/GFR) was similar in all three groups as CH2O + CNa/GFR increased up to 12-14 ml/min-100 ml GFR. Thereafter, CH2O/GFR continued to rise in virtually a straight line in salt-depleted dogs but leveled off in normal dogs with or without aldosterone. These data demonstrate that enhanced sodium reabsorption in the diluting segment of the nephron is an important determinant of the renal sodium retention in chronic extracellular volume contraction in dogs in addition to confirming the presence of increased proximal tubule sodium reabsorption in these animals.

A High-Resolution Imaging Technique using a Whole-body, Research Photon Counting Detector CT System.

A high-resolution (HR) data collection mode has been introduced to the whole-body, research photon-counting-detector CT system installed in our laboratory. In this mode, 64 rows of 0.45 mm × 0.45 mm detectors pixels were used, which corresponded to a pixel size of 0.225 mm × 0.225 mm at the iso-center. Spatial resolution of this HR mode was quantified by measuring the MTF from a scan of a 50 micron wire phantom. An anthropomorphic lung phantom, cadaveric swine lung, temporal bone and heart specimens were scanned using the HR mode, and image quality was subjectively assessed by two experienced radiologists. Comparison of the HR mode images against their energy integrating system (EID) equivalents using comb filters was also performed. High spatial resolution of the HR mode was evidenced by the MTF measurement, with 15 lp/cm and 20 lp/cm at 10% and 2% MTF. Images from anthropomorphic phantom and cadaveric specimens showed clear delineation of small structures, such as lung vessels, lung nodules, temporal bone structures, and coronary arteries. Temporal bone images showed critical anatomy (i.e. stapes superstructure) that was clearly visible in the PCD system but hardly visible with the EID system. These results demonstrated the potential application of this imaging mode in lung, temporal bone, and vascular imaging. Other clinical applications that require high spatial resolution, such as musculoskeletal imaging, may also benefit from this high resolution mode.

d-Transposition of the great vessels in the neonate. A clinical diagnosis.

We reviewed the records of 66 neonatal patients with d-transposition of the great vessels (d-TGV) admitted to our institution. The initial history, physical examination by the cardiologist, chest rotengenogram, ECG, hemoglobin level, and hematocrit value were analyzed. Although all patients all patients were cyanotic and 65% were tachypneic, other signs of a major congenital cardiac anomaly were usually absent. The number of clinical signs (poor general status, cyanosis, respiratory distress, S2 increased and single, murmur, classical chest roentgenogram, abnormal ECG) present in each patient was three or less in 41%, only 13.5% had more than five signs.

Randomized, placebo-controlled, double-blind study of low-dose oral interferon-alpha in HIV-1 antibody positive patients.

One hundred forty-nine patients of private physicians in Toronto, Canada, who were positive for human immunodeficiency virus (HIV), medically stable, and had CD4 cell counts of < 700 cells/mm3 participated in a randomized, double-blind trial of placebo versus low-dose (50 U) versus high-dose (100 U) oral interferon-alpha. Treatment allocation was balanced according to baseline CD4 cell count and history of prior antiviral therapy. Patients were observed at 4 and 8 weeks for assessment of adverse events and several measures of disease status, including CD4 cell count, beta 2-microglobulin, weight, and Karnofsky score. We detected neither short-term benefits nor adverse effects from oral interferon-alpha therapy.

Persistence of the fetal cardiopulmonary circulatory pathway: survival of an infant after a prolonged course;.

The first case of "idiopathic" persistence of the fetal cardiopulmonary circulatory pathway with survival after a prolonged course is documented by serial cardiac catheterizations. All previously reported infants have either markedly improved within the first week of life or subsequently died. This entity has been described in term infants with prenatal or perinatal distress who present with tachypnea and cyanosis from birth. The chest radiograph is remarkable for the absence of pulmonary parenchymal pathology and the hemoglobin and hematocrit are normal. Blood gas determinations indicate hypoxia and acidosis with or without hypercarbia. Cardiac catheterization and angiography reveal an anatomically normal heart with severe pulmonary hypertension, left ventricular pressure lower than right ventricular pressure, and right-to-left venoarterial shunting through the fetal channels (atrial and or ductal levels). It is postulated that this entity may result from antenatal factors that affect the pulmonary vasculature and its subsequent adjustment to extrauterine life. These factors may include abnormal intrauterine stress resulting in excessive hypertrophy of the pulmonary arteriolar smooth muscle, or abnormal pulmonary vascular responsiveness to the usual vasoactive stimuli before or after birth, or an immature or dysfunctioning enzyme system necessary for the normal decrease in pulmonary artery pressure.

A national HIV community cohort: design, baseline, and follow-up of the AmFAR Observational Database. American Foundation for AIDS Research Community-Based Clinical Trials Network.

This article describes the design, methodology, baseline distributions, and general follow-up characteristics of the American Foundation for AIDS Research (AmFAR) National Observational Database (ODB) Project including the benefits and limitations of collecting information on a large simple cohort in the HIV community setting. The study prospectively followed 15,611 HIV-positive men and women and collected longitudinal and cross-sectional data on demographics, medical conditions, drug therapies, laboratory parameters, and survival. Participants were followed between October 1990 and December 1993 by 252 community-based sites coordinated by 22 centers in the Community-Based Clinical Trials Network (CBCT Network) throughout the United States (including Puerto Rico) and Toronto, Canada. The ODB provided quantitative information on a national level needed to track the HIV epidemic and plan clinical trials conducted through the Network, and to provide sites with local databases to monitor patients and facilitate access to therapies in clinical trials. Overall, the ODB contains information on 1,925 women (12%) and 13,686 men (88%), 60% white, 20% African American, 17% Latino/Hispanic, with 56,254 baseline and follow-up forms, a median follow-up of about 12 months, a 16% loss-to-follow-up, and an 11% mortality rate. AmFAR plans to place the ODB in the public domain.

Carbicarb, sodium bicarbonate, and sodium chloride in hypoxic lactic acidosis. Effect on arterial blood gases, lactate concentrations, hemodynamic variables, and myocardial intracellular pH.

The effects of Carbicarb, sodium bicarbonate, and sodium chloride on arterial blood gases, lactate concentrations, hemodynamics, and myocardial intracellular pH were compared in hypoxic lactic acidosis with controlled carbon dioxide elimination. Twenty-one young mongrel dogs were anesthetized, mechanically ventilated, and randomly allocated into one of three treatment groups. After hypoxic lactic acidosis was induced and maintained, 2.5 mEq/kg of one of the agents was infused over 30 min. Arterial blood gases, pH, lactate concentrations, and hemodynamic variables were measured immediately prior to the infusion of the agent and 30 min after the infusion was completed. With sodium bicarbonate administration, there was a significant increase in arterial PCO2 as compared to both Carbicarb or sodium chloride administration. With Carbicarb administration, there was a significant increase in arterial pH, base excess, and cardiac index, without a significant increase in arterial lactate concentration as compared to sodium bicarbonate or sodium chloride administration. Stroke volume index was also increased significantly with decreased heart rate. The data suggest that Carbicarb administration in hypoxic lactic acidosis improved hemodynamics compared with sodium bicarbonate or sodium chloride administration. The increased stroke volume and cardiac contractility appear to be due to improved myocardial intracellular pH.

Pulmonary alveolar proteinosis: high-resolution CT, chest radiographic, and functional correlations.

STUDY OBJECTIVE: To determine whether a correlation exists between pulmonary function and both frontal chest radiographs and high-resolution chest CT findings in patients with pulmonary alveolar proteinosis (PAP). DESIGN: Retrospective review of radiographic and clinical data. SETTING: Tertiary referral hospital. PATIENTS: Seven patients with PAP were studied on 25 occasions using high-resolution chest CT (n=21), frontal chest radiographs (n=19), and pulmonary function tests (PFTs) (n=25). MEASUREMENTS AND RESULTS: Visual estimates of the extent, degree, and overall severity of parenchymal abnormalities were determined for plain radiographs and high-resolution chest CT, and were correlated with PFTs. With high-resolution CT, the extent and severity of ground-glass opacity correlated significantly with the presence of a restrictive ventilatory defect, reduced diffusing capacity, and hypoxemia. Chest radiographic findings also correlated significantly with restrictive ventilatory defect, diffusing capacity, and hypoxemia. CONCLUSION: In patients with PAP, although high-resolution CT correlates more closely with pulmonary function, plain radiographs should be sufficient for follow-up.

Cor pulmonale secondary to upper airway obstruction. Cardiac catheterization, immunologic, and psychometric evaluation in nine patients.

Previous reports of cor pulmonale due to upper airway obstruction have not noted that chronic hypoxemia due to alveolar hypoventilation can lead to left as well as right ventricular failure in these patients. We found elevated left ventricular end-diastolic pressure in four of five patients. Although these patients have frequent respiratory infections, no investigation of their immune status has previously been reported. We performed such investigations but could not demonstrate an immunologic deficiency. Although nine of 44 patients previously reported were mentally retarded, no psychometric data were available. We studied five patients but could not determine the role of mental subnormality in this syndrome. Diagnosis of this syndrome should be suspected when clinical and roentgenographic findings of biventricular heart failure are associated with right ventricular hypertrophy on electrocardiogram. The diagnosis of alveolar hypoventilation is confirmed by blood gas findings and examination of the upper airways. Surgical removal of obstructive tissue reverses the cardiac involvement.

Hemodynamic effects of high-frequency oscillatory ventilation in severe pediatric respiratory failure.

OBJECTIVE: To assess the hemodynamic effects of high mean proximal airway pressures (Paw) during high-frequency oscillatory ventilation (HFOV) in non-neonatal pediatrics patients with severe respiratory failure. DESIGN: Prospective and retrospective study. SETTING: Pediatric ICU in a university-affiliated hospital. PATIENTS: 8 non-neonatal pediatric patients with severe respiratory failure ventilated with HFOV at our institution between July 1991 and February 1994. All patients had a pulmonary artery catheter. INTERVENTIONS: HFOV. MEASUREMENTS AND RESULTS: Higher Paw was required during HFOV to obtain adequate lung expansion during the first 24 h (median 20.9 cmH2O, range 16.9-30.0 cmH2O in CMV, versus median 30.0 cmH2O, range 21.0-33.0 cmH2O in HFOV, p = 0.008), resulting in improved oxygenation as evaluated by alveolar-arterial oxygen difference (median of 557.2 mmHg, range 360.4-607.8 mmHg in CMV, versus median of 410.5 mmHg, range 282.9-550.2 mmHg after 24 h of HFOV, p = 0.03). The only observed effect on the cardiovascular system was a decrease in heart rate (median of 162, range 129-178 in CMV, versus median of 142, range 104-195 after 24 h of HFOV, p = 0.03). Oxygen delivery, cardiac index, mean systemic arterial blood pressure, and pulmonary and systemic vascular resistances did not change significantly before and after HFOV in the patients as a group, although in one case a decrease in cardiac index and oxygen delivery was observed. CONCLUSIONS: High-Paw HFOV must be used cautiously, but seems to have no discernible adverse effects on the cardiovascular system in most patients.

Magnetic resonance imaging of the thorax. Past, present, and future.

Magnetic resonance imaging is a valuable modality of extreme flexibility for specific problem-solving capability in the thorax. This article reviews MR applications in the imaging of great vessels, which are currently the most important applications in the thorax; other established applications in the thorax; and pulmonary functional MR imaging.

Magnetic resonance imaging of the thorax. Past, present, and future.

Magnetic resonance is a valuable modality of extreme flexibility for specific problem-solving capability in the thorax. This article reviews MR applications in the imaging of great vessels, which are currently the most important applications in the thorax; other established applications in the thorax; and pulmonary functional MR imaging.

Acute renal failure secondary to ureteral fungus ball obstruction in a patient with reversible deficient cell-mediated immunity.

A patient with a single functioning kidney and anuria due to ureteropelvic obstruction by a Candida fungus ball is described. During treatment with amphotericin B administered via a nephrostomy tube the drug was not detected in the serum, indicating that absorption from urothelium was not significant. Immunological studies demonstrated a lack of cell-mediated immunity which was probably brought about by a long course of prednisone and later restored when this drug was discontinued. This immunosuppression was evident even with a relatively small dosage of prednisone (5 mg daily). The literature concerning renal candidiasis and predisposing factors is reviewed.

Quantification of pulmonary perfusion with MR imaging: recent advances.

Recent advances in magnetic resonance pulmonary perfusion imaging are reviewed, focusing on magnetic resonance perfusion imaging using gadolinium contrasts agents or spin labeling of blood using naturally flowing spins as the source of intravascular signal. These recent developments in magnetic resonance imaging have made it possible to analyze data quantitatively which holds significant potential for clinical imaging of lung perfusion and opens windows to functional MR imaging of the lung. We believe that fast magnetic resonance functional imaging will play an important role in the assessment of pulmonary function and the pulmonary disease process.

Common fluid and electrolyte problems in the pediatric intensive care unit.

Administration of intravenous fluid to infants and children requires an understanding of the normal expenditure of water and electrolytes by the healthy child and the effects of specific illnesses on water and electrolyte turnover.

Drowning and near-drowning.

The incidence, epidemiology, and pathophysiology of drowning and near-drowning are presented. Particular attention is paid to the neurologic and pulmonary pathophysiology indicators for monitoring and laboratory tests. Special attention to transportation of patients is given, and treatment in the field, emergency department, and pediatric intensive care unit is delineated.

Ventilation-perfusion MR imaging of the lung.

The assessment of regional ventilation in human lungs is important for the diagnosis and evaluation of a variety of pulmonary disorders, including pulmonary emphysema, diffuse lung disease (e.g., sarcoidosis, and pulmonary fibrosis), lung cancer, and pulmonary embolism. This article introduces new MR imaging techniques of pulmonary ventilation and perfusion that will provide a framework for assessing regional pulmonary functions of the lung.

Prostaglandin synthesis inhibition in persistent pulmonary hypertension of the newborn.

The data implicating prostaglandin synthesis inhibitors as an etiology for PPHN are reviewed. Consideration is given to the pharmacology of prostaglandin synthesis inhibitors in the fetus and newborn, the role of prostaglandins in the fetal and neonatal circulation, and the effect of closure of the ductus arteriosus on the fetal pulmonary vasculature.

Distribution of thoracic lymphadenopathy in sarcoidosis using computed tomography.

The authors used chest computed tomography to determine the distribution of pulmonary lymphadenopathy in 40 patients with sarcoidosis. Using the American Thoracic Society lymph node map, the number and distribution of significant lymph nodes was calculated. Overall, lymphadenopathy was identified in 39 of the 40 patients. Mediastinal adenopathy was present in 38 patients, and hilar adenopathy was present in 27. Commonly involved nodal stations were 4R, 5, 7, 10R, 11R, and 11L, and little involvement was seen in stations 1, 6, and 14. An understanding of the common sites of adenopathy in sarcoidosis is useful when assessing adenopathy in patients without a known diagnosis.