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Biomedical subjects

C L Chang

Publications and source records attributed to C L Chang.

At least 109 records · Page 6Linked to original sources
PubMed1995

[Changes of arterial oxygen tension in supine position during one-lung anesthesia].

BACKGROUND: One-lung ventilation during anesthesia (one-lung anesthesia) in patients under lateral decubitus position to help performing intra-thoracic surgical procedures was well known to have larger alveolar-to-arterial oxygen tension difference and lower arterial oxygen tension (PaO2) as compared to two-lung ventilation. In the present study, we investigate the changes of arterial oxygen tension in the supine position during one-lung anesthesia. METHODS: Forty-two patients of palmar hyperhidrosis, ASA class I-II, scheduled to receive bilateral transthoracic endoscopic sympathectomy were studied. After anesthetic induction (fentanyl, thiopental, and succinylcholine), a 35 (for female) or 37 (for male) French left-sided Robertshaw double-lumen endobronchial tube was intubated. Anesthesia was maintained with isoflurane 1.0-1.5% and 50% O2-N2O. They were changed to isoflurane 1.5-2.0% and 100% O2 during one-lung ventilation. Once the surgical operation is completed, they were changed to 100% O2 and two-lung ventilation. Arterial blood gases were measured at 4 phases: 5 min after endobronchial intubation (two-lung ventilation), 5 min after left one-lung ventilation, 5 min after right one-lung ventilation, and 5 min after accomplishing operation (two-lung ventilation). RESULTS: The results showed PaO2 were significantly lower in left and right one-lung ventilation with 100% O2 as compared with that obtained from two-lung ventilation with 50% O2 5 min after endobronchial intubation (p < 0.05). Furthermore, right one-lung ventilation had a lower PaO2 than left one-lung ventilation (p < 0.05). CONCLUSIONS: We conclude that arterial oxygen tension can be safely maintained during one-lung anesthesia with pure oxygen in healthy patients lying in a supine position.

Adolescent↗
PubMed1995

What kind of maternal factor might predict poor perinatal outcome in severe preeclampsia?: a study based on doppler velocimetry.

BACKGROUND: Umbilical artery Doppler velocimetry has been used as an important perinatal tool to identify fetal compromise. However, the fact that it is both expensive and time-consuming makes it not always available. This study was a search for any maternal serum laboratory test which might be much simpler and easier than Doppler velocimetry, and still determining the perinatal outcome in severe preeclampsia. METHODS: Forty-seven patients with severe preeclampsia were enrolled in this study. Doppler velocimetry of umbilical artery, maternal serum biochemistry and hematological tests were all performed within two days prior to delivery or fetal death. RESULTS: By choosing a maternal hematocrit (Hct) of greater than 44% as the cutoff value, a significantly higher incidence of adverse perinatal events was noted in patients with abnormal value than those with normal value. Abnormal Hct level as a predictor of adverse perinatal outcome had a sensitivity of 50.0%, a specificity of 84.2%, a positive predictive value of 53.3% and a negative predictive value of 63.8%. CONCLUSIONS: This study found that elevated maternal Hct (> 44%) levels might indicate a condition of hemoconcentration with reduced placental perfusion in severely preeclamptic patients. Hct level can serve as a clinically useful predictor of adverse perinatal outcome.

Adult↗
PubMed1994

Inhibitory effect of neuropeptide Y (NPY) on the in vitro activity of tyrosine hydroxylase.

Neuropeptide Y (NPY) is found to be costored with norepinephrine (NE) in vesicles of the nerve terminals. Tyrosine hydroxylase (TH), the synthetic enzyme of NE, has been mentioned to be a rate-limiting step. In an attempt to understand the effect of NPY on TH activities, an in vitro assay is carried out using chromatographic analysis of 3,4-dihydroxyphenylalanine (DOPA) formation from tyrosine. NPY (40-120 pmol/ml) produced a dose-dependent depression of DOPA formation catalysed by the adrenal TH of rats. Lineweaver-Burk plot (Km = 156 microM, Vmax = 1.05 nmol/h/mg protein) showed a non-competitive inhibition in NPY (80 pmol/ml, IC50)-treated samples. Moreover, failure of denatured NPY even at maximum concentration to influence the TH activities suggested the essential of nature form for NPY. Participation of pterine cofactor seems also negligible, because increase of 2-amino-4-hydroxy-6,7-dimethyltetrahydropteridine did not overcome the effect of NPY. These results indicate that NPY has the ability to inhibit the catalytic action of TH in the adrenal gland of rats.

Adrenal Glands↗
PubMed1994

The influence of chronic lobular hepatitis on pharmacokinetics of cefoperazone--a novel galactose single-point method as a measure of residual liver function.

Cefoperazone is a semisynthetic cephalosporin antibiotic containing a piperazine side chain, which results in antipseudomonal activity. Unlike the other cephalosporins, it is mainly cleared by the liver (60-80%) and it may be more sensitive to changes in the liver function and/or plasma protein binding than other cephalosporins, which are not primarily cleared by the liver. In order to study the influence of chronic lobular hepatitis on the pharmacokinetics of cefoperazone, a dose of 1 g of cefoperazone was administered to 11 normal, healthy volunteers and 16 subjects with chronic lobular hepatitis. In each volunteer or patient, a novel galactose single-point (GSP) method, the galactose elimination capacity (GEC) test, and the modified galactose elimination capacity (MGEC) test were also performed as a measure of residual liver function. Cefoperazone was administered intravenously over a period of 3-5 min. Blood and urine samples were collected at appropriate intervals after drug administration and stored at -30 degrees C until high-pressure liquid chromatographic (HPLC) analysis. The cefoperazone hepatic clearance, mean residence time, and renal clearance in hepatitis patients were significantly different from those of normal healthy volunteers, whereas the plasma protein binding was unaltered between the two groups. Urinary excretion of cefoperazone showed a highly significant increase in patients, 23.95 +/- 5.06% and 37.54 +/- 13.61% for normal men and hepatitis patients respectively. Hepatic clearance and fraction excreted in urine significantly correlated with values of GSP and MGEC respectively (p < 0.05). These results suggest (i) cefoperazone kinetics was significantly altered in patients with chronic lobular hepatitis; (ii) GSP, a novel simple, clinically useful quantitative liver function test, can predict the cefoperazone hepatic clearance in patients with liver dysfunction.

Adult↗
PubMed1994

Lipid profiles after the daily consumption of an oat-based cereal: a controlled crossover trial.

Water-soluble fiber has been reported to reduce serum cholesterol and consequently, oat bran, which has a high soluble-fiber content, has been recommended as part of a lipid-lowering diet. However, a recent small study of 20 volunteers with low mean serum cholesterol concentrations (4.8 mmol/L) demonstrated no lipid-lowering effect of oat bran. The present study investigated 64 volunteers with cholesterol concentrations much more typical of the UK population (6 mmol/L). Subjects were randomly allocated to receive either a normal-sized helping of an oat-based cereal or a cereal containing no oats for 4 wk and then crossed over to the alternative regimen for a further 4 wk. Small (2.23% and 4.55%) but significant (P < 0.04 and P < 0.05) reductions in total and low-density-lipoprotein cholesterol, respectively, were observed in association with the consumption of oat-based cereal. These data support the view that consumption of oat-based cereals may well contribute usefully to a lipid-lowering diet.

Cholesterol, HDL↗
PubMed1994

Cerebral effects of nitrous oxide during isoflurane-induced hypotension in the pig.

We have studied the effects of nitrous oxide on cerebral blood flow (CBF), cerebral blood flow velocity (CBFV) and intracranial pressure (ICP) during isoflurane-induced hypotension in 10 pigs. CBF was measured using laser Doppler flowmetry, CBFV in the right middle cerebral artery was calculated using Doppler ultrasound and ICP was measured using an extradural ICP monitor. Each animal was studied under four conditions, examined sequentially: (i) mean intra-arterial pressure (MAP) 85 mm Hg, maintained with isoflurane, (ii) MAP 50-55 mm Hg, induced by isoflurane only, (iii) MAP 85 mm Hg, maintained with isoflurane and 50% nitrous oxide, and (iv) MAP 50-55 mm Hg, induced by isoflurane and 50% nitrous oxide. No significant differences were noted between conditions with respect to ICP. There was a significant difference in CBF during condition (ii) compared with (i) (mean 75(SD 21) vs 100(0)%) and during condition (iv) compared with (iii) (90(26) vs 109(13)%). Animals under condition (iv) exhibited a 20% reduction in CBFV compared with those under condition (iii) (57 vs 69 cm s-1). For animals under normotensive conditions, addition of nitrous oxide to isoflurane resulted in a 16% increase in CBFV (69 vs 60 cm s-1). Comparing isoflurane-induced hypotension ((ii) vs (iv)), there was no statistical difference in either CBF or CBFV on addition of 50% nitrous oxide. The correlation between changes in CBF and CBFV was not significant. We conclude that the use of nitrous oxide during isoflurane-induced hypotension has no significant effect on CBF, CBFV or ICP compared with the use of isoflurane alone.

Animals↗
PubMed1994

The effects of KB-2796 and BAY K 8644 on fentanyl-induced analgesia in rats.

We investigate the modulatory effects of subcutaneous administration of different doses of KB-2796 (1, 5 and 15 mg/kg), a new calcium channel blocker, and BAY K 8644 (0.25, 0.5 and 1 mg/kg), a calcium agonist, on fentanyl-induced analgesia (20 micrograms/kg) in rats. The drugs were tested individually as well as in combination with fentanyl. Dimethyl sulfoxide (DMSO) was used as a control. Nociceptive sensitivity was assessed by the tail-flick technique. When KB-2796 and BAY K 8644 were used alone, only KB-2796 at the dose of 15 mg/kg produced an effect that was significantly different from that of DMSO (p < 0.01). The effect was antinociceptive. When administered with fentanyl, KB-2796 at 5 and 15 mg/kg potentiated the analgesic effect of fentanyl (p < 0.05), but suppression of fentanyl analgesia by BAY K 8644 was not significant at any of the doses tested. Our data supports the hypothesis that the calcium ion is partially involved in fentanyl-induced analgesia.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

[Resections of tracheal or bronchial tumors and tracheal or bronchoplasty: experience with 53 patients].

UNLABELLED: From January 1982 to December 1992, a total of 485 patients with pulmonary tumors were treated by surgical procedure, in which 53 cases (92.4%) were treated by segmental resections of trachea, carina, bronchi and with tracheal-or bronchoplasty. In this series of tracheal-or bronchial tumors, four (7.6%) were benign, 49 (92.4%) were malignant. Segmental resections of trachea and carina with plastic procedures were performed on 6 cases, sleeve resections of main bronchi with plastic procedures were performed on 47 cases. One case (1.9%) died of respiratory failure postoperatively. FOLLOW-UP: the survival rate of 5 years was 35% (6/17), three years' was 56% (18/32), one year's was 77.8 (35/45). We considered that the patients with tumors of trachea or bronchi had significant symptom-irritated cough with bloody sputum. Earlier diagnosis, earlier surgical treatment could get a better therapeutic result. Segmental resections of trachea and sleeve resections of bronchi with lobectomy extended the indications for treating pulmonary neoplasm, and saved the normal lung tissues and functions as more as possible, provided some operative chances for elder patients and those cases with insufficient pulmonary functions. This procedure improved the patients's life quality and left the possibility of reoperation.

Adult↗
PubMed1994

Bowel perforation--a fatal complication following renal transplantation: a report of two cases.

From May 1983 to January 1993, 162 patients received renal transplantation at Taichung Veterans General Hospital. Two patients developed bowel perforation after this surgery. One was proved at 21 days and another, at 13 days after renal transplantation. Both patients died as a direct result of the perforation. From a review of literature, the average incidence is 2.7%, and the average mortality rate is 56.5%. Because of this high mortality rate, a high clinical suspicion, prompt and adequate surgical intervention, reduction of immunosuppressive agents and effective antibiotic coverage should contribute to a decline in mortality.

Adult↗
PubMed1994

The direct cardiac effects of ketamine studied on the intact isolated rabbit heart.

The effects of ketamine on the inotropic and chronotropic responsiveness of heart were examined in spontaneously beating hearts isolated from rabbits by using a modified Langendorff preparation. The changes of maximum left ventricular dP/dt from baseline level after exposing to ketamine 5, 25 and 125 micrograms/ml averaged +7.1% (P < 0.05), +2.8% (P > 0.05) and -42.6% (p < 0.001), respectively. The decreases of heart rate at the three ketamine concentrations averaged 2.4% (P < 0.05), 9.4% (P < 0.01) and 36.8% (P < 0.001), separately. Our data demonstrate that ketamine has dual actions on the cardiac inotropism. It mildly increases cardiac contractility at low concentration whereas at high concentration it depresses myocardium profoundly. Besides, ketamine produces a dose-dependent inhibition on chronotropism directly.

Animals↗
PubMed1994

The effect of heated humidifier in the prevention of intra-operative hypothermia.

Unintentional hypothermia is common in patients undergoing "routine anesthesia in surgery". The aims of the study were to estimate the difference of changes of body temperature during abdominal and limb operations and to evaluate the effectiveness of the heated humidifier for reducing intraoperative heat loss. Forty-three patients were randomly being allocated into 3 groups. Group I consisted of 14 patients undergoing abdominal operation without the use of heated humidifier. Another 22 patients were being assigned as group II to have a heated humidifier on the inspiratory limb of the breathing circuit. The inspired gas was warmed to 39 degrees C and the relative humidity was 90%. 7 patients undergoing limb operation were attributed to group III without using heated humidifier to humidify and warm up the inspired gas. For body temperature monitoring, the probe was placed on the patient's nasopharynx and the temperature was measured immediately before induction of anesthesia, post-intubation, and then once again every 15 minutes up to 3 hours after induction. All patients in the 3 groups showed a rapid decrease of body temperature in the first hour and then the hypothermic change was slow down. The lowest level of body temperature was reached at about 2 hours after induction. Patients undergoing abdominal operation decreased body temperature greater than those undergoing limb operation for about 2 degrees C after 3 hours of anesthesia and surgery. Warming and humidifying the inspired gas effectively reduced the heat loss. We concluded that abdominal operation induce hypothermia more than limb operation. The use of heated humidifier was effective in maintaining body temperature.

Adult↗
PubMed1994

The effect of nifedipine on fentanyl-induced analgesia in rats.

We investigated the modulatory effect of subcutaneous administration of different doses of nifedipine (1.5 or 15 mg/kg), a calcium channel blocker, on fentanyl (15 micrograms/kg), an opioid mu-agonist, in rats. The drugs were tested individually as well as in combination. Normal saline and dimethyl sulfoxide were used as controls. Nociceptive sensitivity was assessed by tail-flick technique. No analgesic effect by nifedipine alone at any of the three doses was observed. A slight analgesic effect by fentanyl alone, lasting up to 60 minutes, was noted in the tail-flick responses only (p < 0.05). The combination of both drugs did not enhance or prolong the analgesic effect of fentanyl. The same results were obtained in a supplementary study using higher doses of fentanyl (30 micrograms/kg) with nifedipine (15 mg/kg). Our results suggested that, unlike other calcium channel blockers, nifedipine injected subcutaneously does not enhance fentanyl analgesia.

Analgesia↗
PubMed1994

The influence of focal ischemic brain injury on tail-flick latency in the rat.

Tail-flick latency (TFL), a measure of response threshold to pain, was investigated in rats with focal ischemic brain injury resulting from middle cerebral artery occlusion (MCAO) as compared to sham and non-operative (non-op) groups on the 1st, 7th, 14th, 21st and 28th days following surgery or anesthesia. No significant differences were observed between MCAO and sham groups postoperatively, indicating focal ischemic insult induced by this model had no significant influence on TFL. Increased sensitivity to TFL in early postoperative period was shown when compared sham or MCAO with non-op group. The correlation between TFL and the time from surgery was statistically significant on the 1st and 7th days in sham group and the 1st, 7th and 14th days in MCAO group. We conclude that the focal ischemic injury resulting from middle cerebral artery occlusion that has no obvious neurologic effects does not alter pain threshold; however, surgical procedure increases postoperative sensitivity to pain stimulation.

Animals↗
PubMed1994

Enhancement of antinociceptive effect of fentanyl by KB-2796 at spinal level.

Opioids inhibit the voltage-dependent calcium channel conductance, which is one of the mechanisms of opioid analgesia on the opioid receptor. According to the hypothesis that calcium antagonists can potentiate the analgesic effect of opioids, we designed a study to investigate the effects of KB-2796, a new calcium channel blocker, on the antinociception of fentanyl at the level of the spinal cord in rats. PE-10 catheters were chronically implanted in the lumbar intrathecal space of the rats. Tail-flick test was used to assess the nociceptive sensitivity. Fentanyl (1 microgram) and KB-2796 (50, 150 or 250 micrograms) were tested individually as well as in combination. Dimethyl sulfoxide (10%) was used as a control. All drugs were injected intrathecally. Fentanyl alone produced a significant but short duration (15-30 minutes) of antinociception. KB-2796 by itself did not show any antinociception at any of the doses tested. However, when KB-2796 at the higher doses (150 and 250 micrograms) was administered with fentanyl, the antinociceptive effect was significantly (P < 0.05) enhanced over that of fentanyl alone from 30 to 180 minutes after the injection. In conclusion, our results suggest that KB-2796 potentiates the analgesic effect of fentanyl at the spinal level. These data also support our hypothesis that calcium channel blockers may involve in the antinociception of opioids.

Analgesia↗
PubMed1994

The hemodynamic effects of continuous intravenous infusion of propofol at higher rates.

The new formula of propofol was introduced in 1985. Because of its characteristics of rapid onset and elimination, it was often used as a drug of induction and maintenance of total intravenous anesthesia. However, the hemodynamic effects of propofol was still controversial. The present study was to observe its hemodynamic reactions at higher infusion rate. Hemodynamic studies were performed in 11 female patients, 17 to 54 years old, ASA class I-II, presenting for major lower abdominal operation. Patients with heart, lung, liver, or endocrine disease were excluded. No premedication was given before anesthesia. A radial arterial line and a swan-ganz catheter were inserted under local anesthesia. Cardiac output (CO), arterial blood pressure (ABP), central venous pressure (CVP), pulmonary arterial pressure (PAP), and pulmonary capillary wedge pressure (PCWP) were obtained before induction to foster systemic vascular resistance index (SVRI), left ventricular systolic work index (LVSWI), right ventricular systolic work index (RVSWI), and pulmonary vascular resistance index (PVRI), cardiac index (CI) by an H/p computer analyzer. Propofol (2 mg/kg) was combined with succinylcholine (1.5 mg/kg) for induction. Anesthesia was maintained with propofol and norcuron. The infusion rates of propofol were 10 mg/kg/hr during the first 30 minutes and 8 mg/kg/hr during the following 30 minutes, norcuron, 0.1 mg/kg initially and 1 mg for maintenance after 30 minutes. Normal saline was infused 1000 to 1500 ml in study period to maintain higher preload. Post induction hemodynamic data were collected at the 5th, 15th, 30th, 60th min after induction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Propofol does not reduce infarct volume in rats undergoing permanent middle cerebral artery occlusion.

As propofol has been reported to have effects similar to those of thiopentone on cerebral blood flow, intracranial pressure and cerebral metabolic rate, we postulated that it might also have a protective effect on focal cerebral ischemia. This experiment was designed to test whether or not propofol can alter infarct volume resulting from permanent focal cerebral ischemia in rats. Forty-five rats were randomly assigned to three groups, all of which received xylaxine (5 mg kg-1 im) and ketamine (100 mg kg-1 ip) anesthesia. Rectal temperatures were controlled at 36-37 degrees C. A right temporal craniotomy was performed and the middle cerebral artery (MCA) was ligated with a 10-O suture. Both common carotid arteries (CCAs) were then occluded for 60 minutes using aneurysm clips. In Group 1 rats (n = 15), normal saline (1 ml kg-1 i.v.) was given right after MCA and CCAs ligation. In Group 2 rats (N = 15), propofol (10 mg kg-1 i.v. bolus) was given right after MCA and CCAs ligation. In Group 3 rats (n = 15), continuous intravenous infusion of propofol (16 mg kg-1 hr-1) was given for four hours following MCA and CCAs ligation, during which time mean arterial pressure was maintained approximately 90 mmHg. Twenty-four hours after ischemia, the brains were removed, frozen, sectioned and stained with 2% 2,3,5-triphenyltetrazolium chloride. The cross-sectional area of infarction on each brain slice was measured using computer imaging analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Comparison of five modalities in localization of primary aldosteronism.

BACKGROUND: The best response to surgical treatment of primary aldosteronism occurs in patients with an aldosterone-producing adenoma (APA), so pre-operative localization of the lesion is necessary. METHODS: A comparison was made of five localizing modalities-computed tomography (CT) of the adrenal gland, magnetic resonance imaging (MRI), dexamethasone suppression-131I-19-cholesterol adrenal scintiscan (DS, NP-59 adrenal scan), adrenal venography (venography) and adrenal venous sampling for aldosterone content (AVS) in 22 patients (12 women, 10 men) with primary aldosteronism; all had undergone operative confirmation within the past 9 years. The age at diagnosis ranged from 27 to 67 years (mean: 39.7). RESULTS: Unilateral adrenalectomy resulted in normal blood pressure without medication in 63.6% (14/22), and in improvement in 36.4% (8/22). Correct localization of the lesion was obtained in 95% (20/21) by CT, 100% (7/7) by MRI, 80% (12/15) by DS,NP-59 adrenal scan, 100% (6/6) by AVS and 78% (7/9) by venography. CONCLUSIONS: This experience would advocate CT of the adrenals as the initial means of localizing an APA on an outpatient basis because it is comfortable, safe, inexpensive and gives immediate results. The major role of MRI in the evaluation of adrenal adenoma should be complementary to CT. DS, NP-59 adrenal scan can be an adjuvant method for localization if CT scan results are not definitive. Adrenal venous catheterization with blood sampling for aldosterone content could be reserved for patients whose biochemical finging suggests the presence of an APA, and for whom CT or MRI of the adrenals and DS, NP-59 adrenal scan are inconclusive.

Adrenal Glands↗