Barnes Hospital

A noninvasive technique for assessing cardiac output (CO) was evaluated by comparing it with thermodilution determinations in patients in the intensive care unit. The new method uses pulsed ultrasound to measure aortic diameter and continuous-wave Doppler ultrasound to obtain aortic blood velocity. An initial study evaluating just the velocity measurement showed that changes of the Doppler index of output (DI) correlated well with those of thermodilution cardiac output (TDCO). Linear regression analysis yielded delta DI = 0.87 delta TDCO + 0.14 (r = 0.83, n = 95). Using a university research instrument these measurements were possible in 54 of 60 patients (90%). A second study using a prototype commercial device incorporated the diameter measurement. Ultrasonic cardiac output (UCO), calculated as the time integral of velocity multiplied by the aortic area, was compared to TDCO. The data, obtained from 45 of 53 patients (85%), are described by the linear regression UCO = 0.95TDCO + 0.38 (r = 0.94, n = 110) over a range of 2-11 l/min. Patients with aortic stenosis, aortic insufficiency or a prosthetic valve have been excluded from the second study due to conditions likely to violate the assumptions upon which the calculation of absolute cardiac output is based. These results indicate that accurate CO can be measured by noninvasive ultrasound in most patients. The technique may be useful for extended CO monitoring in acute care patients and for CO assessment in many other types of patients undergoing diagnostic studies and therapeutic interventions.

State-of-the-art metal 3D printers promise to revolutionize manufacturing, yet they have not reached optimal operational reliability. The challenge is to control complex laser-powder-melt pool interdependency (dependent upon each other) dynamics. We used high-fidelity simulations, coupled with synchrotron experiments, to capture fast multitransient dynamics at the meso-nanosecond scale and discovered new spatter-induced defect formation mechanisms that depend on the scan strategy and a competition between laser shadowing and expulsion. We derived criteria to stabilize the melt pool dynamics and minimize defects. This will help improve build reliability.

Pulmonary embolism (PE) represents the third leading cause of cardiovascular mortality. The technological landscape for management of acute intermediate- and high-risk PE is rapidly evolving. Two interventional devices using pharmacomechanical means to recanalize the pulmonary arteries have recently been cleared by the US Food and Drug Administration for marketing, and several others are in various stages of development. The purpose of this document is to clarify the current state of endovascular interventional therapy for acute PE and to provide considerations for evidence development for new devices that will define which patients with PE would derive the greatest net benefit from their use in various clinical settings. First, definitions and limitations of commonly used risk stratification tools for PE are reviewed. An adjudication of risks and benefits of available interventional therapies for PE follows. Next, considerations for optimal future evidence development in this field are presented in the context of the current US regulatory framework. Finally, the document concludes with a discussion of the pros and cons of the rapidly expanding PE response team model of care delivery.

BACKGROUND: Class III obese patients have altered respiratory mechanics, which are further impaired in the supine position. The authors explored the hypothesis that preoxygenation in the 25 degrees head-up position allows a greater safety margin for induction of anesthesia than the supine position. METHODS: A randomized controlled trial measured oxygen saturation and the desaturation safety period after 3 min of preoxygenation in 42 consecutive (male:female 13:29) severely obese (body mass index > 40 kg/m) patients who were undergoing laparoscopic adjustable gastric band surgery and were randomly assigned to the supine position or the 25 degrees head-up position. Serial arterial blood gases were taken before and after preoxygenation and 90 s after induction. After induction, ventilation was delayed until blood oxygen saturation reached 92%, and this desaturation safety period was recorded. RESULTS: The mean body mass indexes for the supine and 25 degrees head-up groups were 47.3 and 44.9 kg/m, respectively (P = 0.18). The group randomly assigned to the 25 degrees head-up position achieved higher preinduction oxygen tensions (442 +/- 104 vs. 360 +/- 99 mmHg; P = 0.012) and took longer to reach an oxygen saturation of 92% (201 +/- 55 vs. 155 +/- 69 s; P = 0.023). There was a strong positive correlation between the induction oxygen tension achieved and the time to reach an oxygen saturation of 92% (r = 0.51, P = 0.001). There were no adverse events associated with the study. CONCLUSION: Preoxygenation in the 25 degrees head-up position achieves 23% higher oxygen tensions, allowing a clinically significant increase in the desaturation safety period--greater time for intubation and airway control. Induction in the 25 degrees head-up position may provide a greater safety margin for airway control.

The results of previous work from this laboratory have shown a poor correlation between percent stenosis (determined visually with calipers) and the coronary reactive hyperemic response (an index of maximal coronary vasodilator capacity) determined during cardiac surgery. This study was performed to determine whether other parameters of lesion severity could predict the reactive hyperemic response and thus the hemodynamic significance of coronary stenoses in human beings. Twenty-three patients with lesions in the proximal left anterior descending coronary artery were studied. To account for differences in expected vessel size, patients with large diagonal branches (greater than one-half the diameter of the left anterior descending artery) arising before the lesion were excluded. Computer-assisted quantitative coronary angiography was used to measure percent diameter stenosis, percent area stenosis, and minimal stenosis cross-sectional area. With a pulsed Doppler velocity probe, reactive hyperemic responses were recorded after a 20 sec coronary occlusion of the left anterior descending artery at cardiac surgery before cardiopulmonary bypass and were quantified by the peak/resting velocity ratio (normal greater than 3.5:1). Percent area stenosis ranged from 7% to 54% for vessels with normal reactive hyperemic responses and from 27% to 94% for vessels with abnormal reactive hyperemic responses. With both percent diameter stenosis and percent area stenosis there was substantial overlap between vessels with normal and abnormal reactive hyperemic responses. In contrast, nine of nine vessels with normal reactive hyperemic responses had lesion minimal cross-sectional areas of greater than 3.5 mm2 and 13 of 14 vessels with abnormal reactive hyperemic responses had minimal cross-sectional areas of less than 3.5 mm2.(ABSTRACT TRUNCATED AT 250 WORDS)

BACKGROUND: Stroke is a leading cause of morbidity and mortality in the United States and occurs in the perioperative period. The authors studied the incidence, predictors, and outcomes of perioperative stroke using the American College of Surgeons National Surgical Quality Improvement Program. METHODS: Data on 523,059 noncardiac, nonneurologic patients in the American College of Surgeons National Surgical Quality Improvement Program database were analyzed for the current study. The incidence of perioperative stroke was identified. Logistic regression was applied to a derivation cohort of 350,031 patients to generate independent predictors of stroke and develop a risk model. The risk model was subsequently applied to a validation cohort of 173,028 patients. The role of perioperative stroke in 30-day mortality was also assessed. RESULTS: The incidence of perioperative stroke in both the derivation and validation cohorts was 0.1%. Multivariate analysis revealed the following independent predictors of stroke in the derivation cohort: age ≥ 62 yr, history of myocardial infarction within 6 months before surgery, acute renal failure, history of stroke, dialysis, hypertension, history of transient ischemic attack, chronic obstructive pulmonary disease, current tobacco use, and body mass index 35-40 kg/m² (protective). These risk factors were confirmed in the validation cohort. Surgical procedure also influenced the incidence of stroke. Perioperative stroke was associated with an 8-fold increase in perioperative mortality within 30 days (95% CI, 4.6-12.6). CONCLUSIONS: Noncardiac, nonneurologic surgery carries a risk of perioperative stroke, which is associated with higher mortality. The models developed in this study may be informative for clinicians and patients regarding risk and prevention of this complication.

STUDY DESIGN: A retrospective examination of the spine radiographs of 88 asymptomatic adolescents was performed to analyze the indices of regional and segmental sagittal spinal alignment in relation to the sagittal vertical axis as determined by the C7 plumb line. OBJECTIVES: To determine the sagittal spinal alignment in asymptomatic adolescents and to correlate the sagittal vertical axis with the overall sagittal spinal balance and other indices of sagittal spinal alignment. In addition, to compare these results with previously established data for asymptomatic adults. SUMMARY OF BACKGROUND DATA: Previous studies of sagittal spinal alignment have included subjects encompassing a wide range of ages. A previous study at the authors' institution established normative data for sagittal spinal alignment in asymptomatic adults. No previous study has reported on the correlation between the sagittal vertical axis and other measurements of sagittal spinal alignment in asymptomatic adolescents. METHODS: Measurements obtained from the standing lateral spine radiographs of 88 asymptomatic adolescents (age range, 10-18 years) were collected and analyzed using statistical methods. These data were compared with previously established data for asymptomatic adults. RESULTS: There was a striking similarity in regional thoracic kyphosis and lumbar lordosis between adolescents and adults. Despite having similar regional and segmental sagittal alignments, adolescents had a significantly more negative sagittal vertical axis (mean, -5.6 cm) than adults (mean, -3.2 cm; P = 0.0001). Also, unlike that in adults, the sagittal vertical axis in adolescents was not significantly correlated with the distal segmental lumbar lordosis. The sagittal vertical axis in adolescents was significantly correlated with the level of thoracic kyphosis and the distances from the thoracic apex, lumbar apex, and T12 to the C7 plumb line. Sacral inclination, which is a determinant of hip extension and standing pelvic rotation, was correlated with the lumbar apex and the total and segmental lordosis, except at L5-S1. CONCLUSIONS: Asymptomatic adolescents tend to stand in greater negative sagittal spinal balance than asymptomatic adults, despite similar regional and segmental alignments in the thoracic and lumbar spine. The role of hip extension, spinopelvic axis rotation, and other sagittal alignment parameters in determining the sagittal vertical axis in adolescents warrants further study.

Human skin is an almost perfect emitter of infrared radiation in the spectral region beyond 3 microns. This energy may be recorded as a thermogram to yield a quantitative temperature map of the skin. If the nude subject has remained quiet in a cool room for 10 to 15 minutes prior to thermography, the skin temperatures are determined largely by the vascularity of the skin itself and by the heat conducted from within the body. Since, under these conditions, the contrasts which appear arise essentially from the internal sources of heat, the resulting thermograms yield information concerning certain pathological conditions within the body (16).

Volume and pH of Gastric Juice in Obese Patients ROBERT VAUGHAN;SPOMENKO BAUER;LESLIE WISE; Anesthesiology

STUDY DESIGN: A retrospective assessment of coronal, sagittal, and axial correction using convex lumbar pedicle screw constructs compared with hook constructs in patients with idiopathic scoliosis. OBJECTIVE: To determine if pedicle screw constructs can improve coronal, sagittal, and axial correction without increased complications and therefore warrant their use in the lumbar spine. SUMMARY OF BACKGROUND DATA: Although hooks have been the traditional fixation choice for posterior scoliosis correction of the lumbar spine, pedicle screws may offer advantages for improved correction of lumbar spinal deformity. METHODS: Twenty-two patients constituted Group A (hooks), in which 17 were double major and five were King Type IV curves. These patients had a minimum follow-up period of 2 years and an average of one hook per lumbar fusion segment. Twenty-two patients constituted Group B (screws), in which 20 were double major and two were King Type IV curves. These patients had a minimum follow-up period of 2 years, and screw configuration consisted of pedicle fixation on the convex side for correction and at times on the concave side for fixation. RESULTS: Pedicle screw fixation constructs had improved lumbar Cobb correction (P < 0.05), lowest instrumented vertebra tilt (P < 0.05), lowest instrumented vertebra translation (P < 0.01), and segmental sagittal alignment from T12 to lowest instrumented vertebra (P < 0.01). There was no significant change in axial rotation using either surgical method. CONCLUSIONS: The use of pedicle screw fixation on the convex portion of the lumbar spine in patients with double major idiopathic scoliosis allows for improved correction of the lumbar Cobb measurement, horizontalization and translation of the lowest instrumented vertebra, and improved segmental lordization over the instrumented levels without increased complications.

A group of randomly selected bereaved (average age 61 years) and age- and sex-matched controls were studied prospectively for one year to determine the mortality and morbidity of the first year of bereavement. In contrast to most published data, the groups showed no difference in the one-year mortality rates. The bereaved experienced significantly more psychological and physical depressive symptoms than their nonbereaved counterparts. Despite this, there were no differences in the two groups in number of physicians visits, hospitalizations, and use of tranquilizers. There was a small but significant increase in use of hypnotics by the bereaved. A review of the literature indicates there is an increased psychological morbidity in the younger widowed, but not in older widowed. The group reported here was of older age.

BACKGROUND: Genome-wide association (GWA) studies have identified several susceptibility loci for metabolic syndrome (MetS) component traits, but have had variable success in identifying susceptibility loci to the syndrome as an entity. We conducted a GWA study on MetS and its component traits in 4 Finnish cohorts consisting of 2637 MetS cases and 7927 controls, both free of diabetes, and followed the top loci in an independent sample with transcriptome and nuclear magnetic resonance-based metabonomics data. Furthermore, we tested for loci associated with multiple MetS component traits using factor analysis, and built a genetic risk score for MetS. METHODS AND RESULTS: A previously known lipid locus, APOA1/C3/A4/A5 gene cluster region (SNP rs964184), was associated with MetS in all 4 study samples (P=7.23×10(-9) in meta-analysis). The association was further supported by serum metabolite analysis, where rs964184 was associated with various very low density lipoprotein, triglyceride, and high-density lipoprotein metabolites (P=0.024-1.88×10(-5)). Twenty-two previously identified susceptibility loci for individual MetS component traits were replicated in our GWA and factor analysis. Most of these were associated with lipid phenotypes, and none with 2 or more uncorrelated MetS components. A genetic risk score, calculated as the number of risk alleles in loci associated with individual MetS traits, was strongly associated with MetS status. CONCLUSIONS: Our findings suggest that genes from lipid metabolism pathways have the key role in the genetic background of MetS. We found little evidence for pleiotropy linking dyslipidemia and obesity to the other MetS component traits, such as hypertension and glucose intolerance.

STUDY DESIGN: A retrospective study of 1,090 patients undergoing corrective spinal deformity surgery for scoliosis (n = 920), kyphosis (n = 77), or a combination of the two (n = 93) at one institution. OBJECTIVES: To ascertain the etiologies and incidence of neurologic deficits occurring at the time of surgery. SUMMARY OF BACKGROUND DATA: Potential etiologies of intraoperative neurologic deficits include cord compression, overdistraction, purely vascular, or a combination. METHODS: The study group included only patients with useful function of their lower extremities and normal bowel and bladder control, and patients whose surgeries were in spinal cord territory as opposed to purely cauda equina territory. RESULTS: There were four major neurologic deficits that occurred during surgery. Three of the four deficits were purely vascular in etiology. The fourth may have had a vascular and mechanical etiology. All four patients had anterior and posterior surgery with harvesting of the unilateral convex segmental vessels, and each had a component of hyperkyphosis, as well as intraoperative controlled hypotension. All four patients showed marked improvement of motor weakness with time. CONCLUSIONS: Significant risk factors were combined anterior and posterior surgery (P = 0.009) and hyperkyphosis (P = 0.0006).

ALTHOUGH the diabetogenic activity of adrenoglucocorticoids has been studied extensively in terms of increased gluconeogenesis and impaired peripheral glucose utilization1 2 3 4 the effects of these steroids on pancreatic islet-cell function have not received much attention. In the present study the effect of the synthetic glucocorticoid dexamethasone on the plasma insulin response of normal, mildly diabetic and acromegalic subjects to oral administration of glucose and intravenous administration of tolbutamide has been determined. In addition, since increased gluconeogenesis is a characteristic feature of glucocorticoid action, the effect on the response of insulin secretion to intravenously infused tolbutamide in mild hyperglycemia maintained by prolonged . . .

Cardiac Catheterization, Angiography and Intervention , fourth ed Edited by William Grossman, Donald S. Baim 1991, 698 pp $59.50 hardcover

Noninvasive ultrasonic examinations were performed in 1984 on a biracial sample of 109 10- to 17-year-old adolescents to determine whether elastic properties of the carotid arteries are associated with cardiovascular disease risk factors in the young. The subjects examined were in either the upper (high risk) or lower (low risk) race-, sex-, and age-specific tertile for both serum total cholesterol (TC) and systolic blood pressure (SBP) during a 1981-82 community survey. The pressure-strain elastic modulus (Ep), a measure of stiffness, for the carotid arteries was calculated by dividing the pulse pressure by the fractional diameter increase in the carotid artery during the cardiac cycle, as measured by ultrasonic techniques. Repeat studies on 20 randomly selected subjects demonstrated high reproducibility of the elasticity measurements (intraclass correlation coefficient = 0.84). The mean Ep in the high risk group was 5.1 kPa higher than in the low risk group, after controlling for race, sex, and age (one-sided p value = 0.03). Furthermore, a positive parental history of myocardial infarction was related to increased Ep levels (p less than 0.05), independently of race, sex, age, TC, and SBP. The results indicate that ultrasonic techniques can detect functional differences in the carotid arteries of children and adolescents that are associated with the risk of cardiovascular disease as adults.

A high-speed synchrotron X-ray imaging technique was used to investigate the binder jetting additive manufacturing (AM) process. A commercial binder jetting printer with droplet-on-demand ink-jet print-head was used to print single lines on powder beds. The printing process was recorded in real time using high-speed X-ray imaging. The ink-jet droplets showed distinct elongated shape with spherical head, long tail, and three to five trailing satellite droplets. Significant drift was observed between the impact points of main droplet and satellite droplets. The impact of the droplet on the powder bed caused movement and ejection of the powder particles. The depth of disturbance in the powder bed from movement and ejection was defined as interaction depth, which is found to be dependent on the size, shape, and material of the powder particles. For smaller powder particles (diameter less than 10 μm), three consecutive binder droplets were observed to coalesce to form large agglomerates. The observations reported here will facilitate the understanding of underlying physics that govern the binder jetting processes, which will then help in improving the quality of parts manufactured using this AM process.

STUDY DESIGN: A prospective and retrospective review of patients 10 years and younger with idiopathic scoliosis evaluated with a total spine magnetic resonance imaging (MRI) scan. OBJECTIVES: To determine the incidence of neural axis abnormalities in infantile and juvenile patients with idiopathic scoliosis without neurologic findings on history and examination, to determine the need for a screening MRI in this age group. SUMMARY OF BACKGROUND DATA: In previous studies, a 19.2% and 26% incidence of neural axis abnormalities were found in infantile and juvenile patients with "idiopathic" scoliosis, respectively, raising the question of routine MRI screening of the spinal canal in these patients. METHODS: A prospective study included 34 consecutive patients newborn to 10 years of age treated between 1992 and 1996 at a spinal deformity clinic with idiopathic scoliosis > 20 degrees without neurologic findings. In addition, a retrospective review of 64 patients age newborn to 10 years of age with idiopathic scoliosis was performed. All patients were evaluated by a total spine MRI protocol for examination of neural axis abnormalities. RESULTS: The incidence of neural axis abnormalities in the prospective group of 34 patients was 17.6% (6 of 34); the incidence of neural axis abnormalities was 20.3% (13 of 64) in the retrospective group. Of 6 patients in the infantile age range, 3 (50%) had neural axis abnormalities. CONCLUSIONS: A total spine MRI is recommended at presentation in patients with juvenile onset idiopathic scoliosis (> 20 degrees) because of the high incidence of neural axis abnormalities. Further study appears warranted to establish the incidence of neural axis abnormalities in infantile idiopathic scoliosis to determine the need for total spine MRI screening in this age group.

STUDY DESIGN: This was a retrospective study of 500 patients undergoing corrective surgery between 1987 and 1997 for spinal deformity caused by idiopathic scoliosis. OBJECTIVES: To report the sensitivity and specificity of somatosensory-evoked and neurogenic motor-evoked potentials monitoring and the requirements for an intraoperative wake-up test for all idiopathic scoliosis surgeries at a single institution. SUMMARY OF BACKGROUND DATA: Intraoperative monitoring is recommended for use during corrective spinal surgery. Accepted monitoring standards and requirements for an intraoperative wake-up test are still debated. METHODS: The study group consisted of 500 patients undergoing corrective surgery for idiopathic scoliosis between 1987 and 1997. All patients were monitored using somatosensory-evoked and neurogenic motor-evoked potential techniques, using a standard protocol developed at this institution. RESULTS: The false-positive rate (significant data change without postoperative neurologic deficit) was 0.014% (n = 7). The true-positive rate (degradation of data that met warning criteria, with a corresponding postoperative neurologic deficit) was 0.004% (n = 2). No false-negative results (normal data during with a postoperative neurologic deficit) were seen. The sensitivity of combined somatosensory-evoked and neurogenic motor-evoked potential data in predicting neurologic status was 98.6%, and the specificity of normal data predicting normal findings in a neurologic examination was 100%. CONCLUSION: Combined somatosensory-evoked and neurogenic motor-evoked potentials monitoring during idiopathic scoliosis surgery represents a standard of care that obviates the need for an intraoperative wake-up test when reliable data are obtained and maintained.

ARCINOMA of the prostate is found in su-C prapubic prostatectomy specimens approximately 5 times each year at our hospital. Almost invariably this is clinically unsuspected carcinoma and in a sense represents an error of preoperative diagnosis. When this occurs the surgeon is faced with a therapeutic decision and must consider castration, estrogen administration, secondary radical prostatectomy, or perhaps no further therapy. The individual urologist has only a limited personal experience with this clinical situation. He must, therefore, rely upon the results of collected studies for guidance in therapy. We are unaware of any published series of cases with long term follow-up in which the various factors bearing on prognosis have been evaluated. This study is concerned with the clinicopathological findings in patients in this category and with the correlation of these findings with survival. There is a significant correlation between pathological findings and clinical outcome that should influence further therapy.