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Biomedical subjects

E Y Cheng

Publications and source records attributed to E Y Cheng.

At least 91 records · Page 5Linked to original sources
PubMed1993

A prospective evaluation of a second-trimester screening test for fetal Down syndrome using maternal serum alpha-fetoprotein, hCG, and unconjugated estriol.

OBJECTIVE: To test the efficacy of a screening protocol using a combination of maternal age plus three biochemical markers--maternal serum alpha-fetoprotein (MSAFP), hCG, and unconjugated estriol (E3)--for the antenatal detection of fetal Down syndrome. METHODS: We conducted a prospective cohort study of 7718 women who underwent the triple-marker analysis between weeks 15-18 of pregnancy. A second-trimester risk for Down syndrome of 1:195 or greater was considered positive. Sensitivity, specificity, positive predictive value, and their 95% confidence intervals (CIs) were calculated. We evaluated test performance for various maternal age groups and screen-positive cutoffs, as well as the relative screening efficacies of maternal age and MSAFP, MSAFP plus hCG, and MSAFP, hCG, and unconjugated E3. RESULTS: Four hundred sixty-one of the 7718 women screened (6%) were identified as positive; 319 women chose amniocentesis, for an overall amniocentesis rate of 4.1%. Twenty of 22 pregnancies affected with Down syndrome were correctly identified, as were 7255 of 7696 unaffected pregnancies, yielding a sensitivity and specificity of 91% (95% CI 79-100%) and 94% (95% CI 93.8-94.8%), respectively. The use of maternal age plus all three analytes improved test performance compared with maternal age plus MSAFP and hCG, but either had a significantly improved detection rate compared with that for maternal age and MSAFP alone. CONCLUSION: The triple-marker screen appears to be an effective method of detecting Down syndrome pregnancies while maintaining an acceptable amniocentesis rate.

Adult↗
PubMed1993

Recent developments in alcoholism:biobehavioral correlates.

A literature review was conducted from 1940 through 1992 on the general topic of alcohol-induced hangover. We focused on the physiological, behavioral, and performance decrements demonstrated hours after a physiologically relevant dose of alcohol was administered in both humans and animals. The purpose of this report was threefold: (1) to review and report both previously published and new data from our laboratory concerning the "after effects" of acute high-dose alcohol administration; (2) to highlight the similarities between and usefulness of data generated from both human and animal studies; and (3) to propose that the hangover phenomenon may be the result of one of the three following hypotheses: (a) an opponent-process physiological rebound from alcohol's immediate, intoxicating effects, (b) some toxic reaction to alcohol or its metabolic by-products, or (c) to the circadian dysrhythmia induced by the immediate intoxicating effects of alcohol.

Alcohol Drinking↗
PubMed1992

The influence of isoflurane on the vascular reflex response to lung inflation in dogs.

Positive pressure ventilation can affect hemodynamic stability by neuroreflex-mediated activity. Inhalational anesthesia is known to attenuate the arterial baroreflex function; however, little information is known about the effect of volatile anesthetics on the lung inflation reflex. The influence of isoflurane on static lung inflation reflex-induced changes in venous capacitance and systemic resistance was investigated in dogs. After controlling carotid sinus pressure at 50 mmHg and initiating total cardiopulmonary bypass, the lungs were inflated to tracheal pressures of 10 and 20 mmHg. The systemic vascular resistance index (SVRI) decreased by 0.04 +/- 0.03 and 0.13 +/- 0.03 mmHg.kg.min.ml-1 during tracheal inflation pressures of 10 and 20 mmHg, respectively. There as an accompanying change in systemic vascular capacitance index (SVCI) by 1.0 +/- 0.65 and 3.3 +/- 0.82 ml.kg-1 during tracheal inflation pressures of 10 and 20 mmHg. The addition of isoflurane decreased the reflex vascular response to lung inflation in a dose-dependent manner. A concentration of 1 MAC isoflurane administered via the cardiopulmonary bypass machine attenuated the change in SVRI to tracheal inflation pressures of 10 and 20 mmHg by 75% and 67%, respectively. Isoflurane at 1 MAC also reduced the reflex capacitance response to tracheal pressures of 10 and 20 mmHg by 36% each. Lung inflation-induced changes in SVRI and SVCI were abolished at isoflurane concentrations of 2 MAC. We conclude that under the conditions of this study, 1 MAC isoflurane was shown to attenuate lung reflex-induced changes in SVRI and SVCI and that at higher isoflurane concentrations (2 MAC) these reflex-induced changes were not seen.

Animals↗
PubMed1992

The effect of acute hypothermia and serum potassium concentration on potassium cardiotoxicity in anesthetized rats.

We examined the effects of hypothermia on serum K+ concentration and the interaction of body temperature and K+ load on cardiac toxicity in anesthetized rats. Serum K+ concentration significantly decreased to 2.61 +/- 0.13, 2.59 +/- 0.19 and 2.39 +/- 0.14 mmol/l at 31.0 degrees C, 28.0 degrees C and 25.0 degrees C, respectively, from the control value of 2.80 +/- 0.15 mmol/l at 37.0 degrees C. We used a 300% increase in baseline QRS duration as evidence of cardiac toxicity. Serum K+ concentrations of 4.95 +/- 0.12, 4.71 +/- 0.10, 4.45 +/- 0.14 and 4.07 +/- 0.14 mmol/l resulted in cardiac toxicity at 37.0 degrees C, 31.0 degrees C, 28.0 degrees C, and 25.0 degrees C, respectively. These data indicate that the level at which an elevation of serum K+ concentration causes cardiac toxicity diminishes with progressive hypothermia. We conclude that hypothermia induces hypokalemia, possibly through redistribution, and that the myocardium appears to be more sensitive to the toxic effects of K+ as hypothermia deepens.

Acidosis↗
PubMed1992

Anesthetic drugs and emergency departments.

Hospital emergency departments were surveyed on their use of N2O, intravenous anesthetics, and neuromuscular blocking drugs; patients monitoring during their use; and the monitoring and evaluation of the quality and appropriateness of the use of these drugs. We received 90 of the 170 surveys sent for a response rate of 53%. Sixty-three percent of the emergency departments that answered our survey administer one or more of these drugs in the emergency room. Less than two-thirds of these respondents indicated they use patient monitors while administering these drugs. The emergency department monitors and evaluates the appropriate use of these drugs in about half of the hospitals that use them, whereas the anesthesiology department is involved less than 20% of the time. Anesthesiology departments should become more involved in developing criteria for evaluating the quality of anesthesia administered by other hospital departments to help ensure that all patients receive a comparable level of anesthetic care throughout the hospital.

Data Collection↗
PubMed1992

Changes in functional residual capacity and regional diaphragm lengths after upper abdominal surgery in anesthetized dogs.

The respiratory performance of the diaphragm may be altered by changes in mechanical or neural factors, or both, induced by upper abdominal surgery. We conducted this study to examine the effects of upper abdominal surgery on postoperative respiratory function. We studied resting lengths of four diaphragm regions, three in the costal and one in the crural diaphragm, with biplane video-roentgenography in six dogs immediately after upper abdominal surgery and up to 30 days postoperatively. Functional residual capacity was 16.7% smaller immediately after surgery compared with values obtained in the same animals after 30 days. Simultaneously measured resting lengths of each of the diaphragm regions immediately after surgery were longer, on average by 8.3%, than 30 days postoperatively. During the postoperative course, resting diaphragm lengths gradually and uniformly decreased as functional residual capacity increased. Phrenic nerve stimulation in four other dogs immediately after identical surgery resulted in large diaphragm shortening (from 42% to 55%), indicating that neither the diaphragm nor phrenic nerves were injured by the surgical manipulation. We hypothesize that respiratory dysfunction after upper abdominal surgery may be, at least in part, attributed to a decreased central drive for breathing caused by activation of the afferent limb of an inhibitory reflex owing to stretching of the diaphragm.

Abdomen↗
PubMed1991

Transcervical chorionic villus sampling and midtrimester oligohydramnios.

To study the possible association between transcervical chorionic villus sampling and midtrimester oligohydramnios, we conducted a prospective cohort study of all women who were seen for genetic counseling in the first trimester during a 2-year period. Women who chose chorionic villus sampling were compared with women who chose traditional amniocentesis for incidence of midtrimester oligohydramnios. Of 442 women exposed to chorionic villus sampling with a normal fetal karyotype, severe oligohydramnios developed in 12 (2.7%) at 16 to 23 weeks' gestation. None of the 391 women with normal fetal karyotypes who were counseled at the same time in pregnancy but who chose amniocentesis had oligohydramnios at the time of amniocentesis (p = 0.01). A nested case-control analysis was performed within the chorionic villus sampling group to evaluate risk factors associated with midtrimester oligohydramnios. Midtrimester oligohydramnios occurring after chorionic villus sampling was associated with postprocedure bleeding and elevated maternal serum alpha-fetoprotein (p less than 0.01). There were no perinatal survivors with midtrimester oligohydramnios.

Adult↗
PubMed1991

Effects of acute hypothermia and beta-adrenergic receptor blockade on serum potassium concentration in rats.

BACKGROUND AND METHODS: We hypothesized that beta-adrenergic receptor blockade would result in an increase in serum potassium concentration in hypothermic rats given a potassium load compared to non-beta-blocked, hypothermic, potassium-loaded rats. To test this hypothesis, we investigated the interaction between body temperature and beta-adrenergic receptor blockade on serum potassium concentrations in ureter-ligated rats with and without potassium loading. To achieve this goal, we performed three experiments. In the first experiment, serum potassium concentrations were determined in 16 rats as they were continuously cooled from 37 degrees C to 22 degrees C. In the second experiment, 12 ureter-ligated rats were cooled to 31 degrees C, after which they were rewarmed to 37 degrees C. Serum potassium concentrations were determined before and after cooling and on rewarming. Twelve other ureter-ligated rats were cooled to 31 degrees C, then given a potassium load until their serum potassium concentrations returned to their baseline values, after which they were rewarmed to 37 degrees C. Serum potassium concentrations were determined before and after cooling, during the potassium infusion, and on rewarming. In the third experiment, 14 rats were pretreated with propranolol and 14 rats served as controls. Half of the rats in each of these two groups were kept at 37 degrees C and half were cooled to 25 degrees C. All rats were then given a 690-mumol potassium chloride infusion. Serum potassium concentrations were determined before and after the potassium infusion. RESULTS: The rats developed hypokalemia with cooling, which spontaneously resolved in the rats without supplementation on rewarming to 37 degrees C. The hypothermic hypokalemic rats that had their serum potassium concentrations corrected to normothermic status (2.93 +/- 0.17 mmol/L) had marked increases in serum potassium concentrations (4.22 +/- 0.15 mmol/L) on rewarming. In the normothermic rats, potassium loading after beta-adrenergic receptor blockade resulted in even higher serum potassium concentrations (5.65 +/- 0.36 mmol/L) compared with non-beta-blocked rats given equal potassium loads (4.6 +/- 0.4 mmol/L). However, in hypothermic (25 degrees C) rats given the same potassium load, there was no difference in serum potassium concentrations in beta-blocked (6.5 +/- 0.35 mmol/L) and non-beta-blocked rats (6.63 +/- 0.3 mmol/L). CONCLUSIONS: These results suggest that acute hypothermia causes a decrease in serum potassium, probably secondary to redistribution, which is reversible on rewarming. Supplementation of potassium during hypothermia can cause a significant increase in serum potassium concentration on rewarming. Blocking beta-adrenergic receptors with propranolol did not effect hypothermia-induced hypokalemia, suggesting that the beta-adrenergic mechanism may not be functional in hypothermia.

Animals↗
PubMed1991

Allograft reconstructions of the shoulder after bone tumor resections.

Large skeletal defects resulting from tumor resections about the shoulder create reconstructive challenges for the orthopedic surgeon. Bone allografts offer several advantages compared with other reconstructive techniques, and functional outcomes are generally satisfactory. They may be used either as osteoarticular grafts, intercalated segments to create an arthrodesis, or in combination with standard proximal humerus metallic implants. Patient expectations and specific oncologic factors must be considered when selecting the optimal method of reconstruction.

Arthrodesis↗
PubMed1989

Foreign body in upper airway. Unsuspected cause of obstruction.

Airway obstruction from a foreign body is usually an acute life-threatening event. In this case, a complete upper dental plate was the unsuspected cause of intermittent respiratory distress. The authors discuss the clinical and laboratory findings and suggest ways to prevent unnecessary delays in diagnosis and treatment.

Airway Obstruction↗
PubMed1989

Evaluation of the palmar circulation by pulse oximetry.

The usual method of substantiating collateral circulation of the hand is with Allen's test. We used the pulse-detecting capability of the pulse oximeter to assess the presence of collateral circulation of the hand. Thirty-one patients undergoing radial artery cannulation for intraoperative monitoring were evaluated before cannulation with a modified Allen's test and by pulse oximetry. After the collateral circulation of the hand was tested by the modified Allen's test, a pulse oximeter probe was placed on the index finger. Both radial and ulnar arteries were occluded until no perfusion was detected by the pulse oximeter. The test was repeated twice on each hand, once for each artery. The time to reperfusion after arterial release was recorded. Reperfusion times greater than 15 seconds were considered abnormal. This sequence was repeated postoperatively after the radial artery cannulae were removed. A total of 68 tests were performed before cannulation; 3 showed an abnormal Allen's test, a finding confirmed by pulse oximetry evaluation. The Allen's test was indeterminate 13 times. In all of these cases, pulse oximetry demonstrated collateral blood flow. When collateral circulation was determined to be present by Allen's test, it was also found to be present with pulse oximetry. Three days after cannulation was discontinued, 8 patients had abnormal Allen's test results, a finding again confirmed by pulse oximetry evaluation. Of 15 patients with indeterminate Allen's test results, 12 had collateral blood flow determined by pulse oximetry and 3 had abnormal results. The ability of pulse oximetry to detect collateral circulation was significantly different (P less than 0.001) when compared with Allen's test both before and after radial artery cannulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗