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P C Chung

Publications and source records attributed to P C Chung.

15 recordsLinked to original sources
PubMed1998

An automatic diagnostic system for CT liver image classification.

Computed tomography (CT) images have been widely used for liver disease diagnosis. Designing and developing computer-assisted image processing techniques to help doctors improve their diagnosis has received considerable interests over the past years. In this paper, a CT liver image diagnostic classification system is presented which will automatically find, extract the CT liver boundary and further classify liver diseases. The system comprises a detect-before-extract (DBE) system which automatically finds the liver boundary and a neural network liver classifier which uses specially designed feature descriptors to distinguish normal liver, two types of liver tumors, hepatoma and hemageoma. The DBE system applies the concept of the normalized fractional Brownian motion model to find an initial liver boundary and then uses a deformable contour model to precisely delineate the liver boundary. The neural network is included to classify liver tumors into hepatoma and hemageoma. It is implemented by a modified probabilistic neural network (PNN) [MPNN] in conjunction with feature descriptors which are generated by fractal feature information and the gray-level co-occurrence matrix. The proposed system was evaluated by 30 liver cases and shown to be efficient and very effective.

Algorithms↗
PubMed1998

Airway compression by a biplane pediatric transesophageal echocardiography probe: case report.

Transesophageal echocardiography (TEE) has been extensively used in cardiac surgery to assess cardiac function and anatomical relationships in both adults and children. Newer monitoring devices, despite being labeled "noninvasive", often present significant risks. Physicians should be cautious with the use of TEE in infants and small children, recognizing that oversized probes may inadvertently compress vital structures, resulting in airway or vascular compromise. If severe compression of the airway or vascular structures occurs, TEE monitoring may need to be discontinued. Although technological progress has yielded smaller ultrasonic probes, the TEE probe is significantly larger than most other devices placed in the esophagus. We present in this report a case of airway compression using a small-sized biplane pediatric TEE probe in a child undergoing Blalock-Taussig shunt surgery. Pediatric patients may be more at risk for airway obstruction because of the over-size of the probe-distended esophagus in relation to adjacent airway structures.

Airway Obstruction↗
PubMed1997

An image capture and communication system for emergency computed tomography.

An image capture and communication system for emergency computed tomography (CT) is presented. The system, named ICCS, integrates CT scanners, personal computers (PC), network systems, an IBM API gateway and an IBM mainframe platform. The ICCS was implemented in the emergency unit in the Taichung Veterans General Hospital (TCVGH) and has received considerable support from the doctors, nurses and staff of the TCVGH emergency unit who have shown great interest in ICCS. This is because ICCS allows physicians in the emergency unit to examine patients' images on image viewing stations immediately after the patients are CT scanned. It also makes remote consultation possible for doctors who can stay where they are and consult with radiologists through the system and a hot line without leaving the emergency unit. This advantage greatly reduces the consultation time and saves many unnecessary trips between the emergency unit and the Department of Radiology.

Emergency Service, Hospital↗
PubMed1996

Deliberate hypotensive anesthesia with labetalol in reconstructive surgery for scoliosis.

BACKGROUND: Anesthesia for surgical reconstruction of scoliosis presents a great challenge for anesthesiologists. One of the main concerns is massive bleeding. Hypotensive anesthesia has been advocated for the purpose of diminishing operative blood loss. On the other hand, some authors reported that the blood loss mostly depends on surgical technique, rather than anesthetic technique. We hereby evaluate the efficacy of deliberate hypotensive anesthesia and compare its merits and faults with that of normotensive anesthesia in scoliosis surgery performed by a single surgical and anesthetic team. METHODS: The effect of deliberate hypotensive anesthesia on intraoperative blood loss, blood transfusion, and length of surgery in patients who underwent Cotrel Duvosset Instrumentation for scoliosis was assessed. Twenty patients (Group A) were given isoflurane as the main anesthetic agent and their blood pressure was maintained at the preoperative level. These patients were compared with twenty patients (Group B) who were anesthetized with isoflurane and their intraoperative mean blood pressure was lowered and controlled at 50 mmHg by intravenous labetalol. All these forty operations were done by a single surgical and anesthetic team. The results were analyzed by the Student's t-test. RESULTS: Deliberate hypotensive anesthesia was found to significantly decrease the average blood loss by nearly 55 per cent, reduce the need for transfusion by nearly 53 per cent, and shorten the average operating time by over one hour. No complications attributable to the specific anesthetic technique occurred. CONCLUSIONS: The findings of this study suggest that deliberate hypotensive anesthesia with labetalol and isoflurane may be of benefit in scoliosis surgery by reducing blood loss, the need of blood replacement and operating time.

Adolescent↗
PubMed1996

High dose intravenous labetalol for the resection of metastatic pheochromocytoma.

A case of intrahepatic metastatic pheochromocytoma with lymph nodes involvement undergoing resection of tumor was reported; intravenous labetalol in high dose regimen (2 mg/kg administered before skin incision) was used for blood pressure control during the operation. Marked sinus bradycardia was noted after receiving total dose of intravenous labetalol and treated [corrected] with intravenous atropine 0.4 mg. The total operation time was 6.5 h. We found that under isoflurane anesthesia, duration of action of intravenous labetalol was prolonged as adequate intraoperative blood pressure control was obtained throughout the 6-h surgical period without further need of supplementary medication. This finding suggested that duration of labetalol was extended when concomitantly used with isoflurane and the labetalol dosage in our regimen could be effectively used in surgical procedures lasting for more than 6 h.

Adrenal Gland Neoplasms↗
PubMed1993

Plasma lidocaine level during spinal or epidural anesthesia in geriatric patients.

Toxicity of local anesthetics is a serious concern by anesthesiologists while performing regional anesthesia. The toxicity includes convulsion, respiratory difficulty, or sometimes cardiac arrest. Total dose of local anesthetic usually cannot predict the occurrence of toxic effects because these effects are directly correlated to the plasma concentration. The plasma concentration is dependent not only on total dose given, but also on the routes of administration, volume of distribution, plasma protein binding and the rate of local absorption. This study is to examine the plasma concentration of lidocaine during spinal or epidural anesthesia in geriatric patients. 12 ASA physical status class II-III patients, age over 65 years old, were selected in this study. They were randomly divided into two groups. Group A patients (n = 6) were anesthetized with 3 mL 2% lidocaine intrathecally and Group B patients (n = 6) were anesthetized with 15 mL 2% lidocaine epidurally. Plasma concentration of lidocaine was examined every 15 minutes after drug administration. The peak level in group A was reached at 90 minutes and group B 105 minutes after drug administration. Peak level in Group A was 1.12 +/- 0.08 micrograms/mL and the plateau was reached at 45 minutes after drug administration. In Group B, peak level was 4.70 +/- 0.74 micrograms/mL and the plateau was reached at 15 minutes. The results also indicated that the absorption of the drug in spinal is much lower than in epidural.

Aged↗
PubMed1993

A new method of maintaining airway during nasotracheal intubation--the hand mask technique.

The efficacy of a new method (The hand mask technique) for airway maintenance during nasotracheal intubation was evaluated in our randomized crossover study. Sixty, age less than 50, ASA physical status class I-II patients undergoing surgery for the extremities with informed consent were randomly chosen for the study. Pulse oximeter, capnometer, EKG, blood pressure monitor and a peripheral nerve stimulator were attached to the patients before induction for continuous monitoring. An arterial cannula was inserted for intermittent blood gas sampling. After baseline room air blood gas data had been obtained from the spontaneously breathing patients, a flow rate of 6L/min pure oxygen was applied through a loosely fitted face mask and a semi-closed anesthesia breathing circuit for a period of 5 minutes. An arterial blood sample was drawn and the patients were put under general anesthesia with full muscle relaxation thereafter. Patients were then randomly assigned into two groups according to the ventilation technique used. Group A patients (n = 30) were manually ventilated first through a face mask for ten minutes and then the hand mask technique for another ten minutes. Blood gas data was sampled and heart rate, blood pressure, peak inspiratory airway pressure and end tidal CO2 were recorded immediately after each ventilation technique. For patients in Group B (n = 30), the sequence of the two ventilation technique were reversed. The results showed significant increases in PaO2 after artificial ventilation in both groups (No significant difference in results between the two groups) and less incidence of nasal bleeding in Group A.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Preliminary experience of using fixed dose of intravenous labetalol in surgical resection of pheochromocytoma.

Seven patients scheduled for resection of pheochromocytoma with loose preoperative control of their blood pressure were selected in our study. All the cases are impressed of pheochromocytoma that predominantly excrete norepinephrine. Anesthesia was induced with fentanyl, 2.5% sodium thiopental, valium and atracurium. Labetalol was used as antihypertensive agent and was given in repeated bolus (up to total dose of 2 mg/kg) intravenously before skin incision and no supplemental dosage was given later on. The anesthesia was maintained with nitrous oxide, oxygen, isoflurane and atracurium. Blood pressure, heart rate and arterial blood gas analysis were recorded. After giving intravenous labetalol, mean systolic blood pressure and heart rate declined by 26.2% and 29.76% respectively when compared to preanesthetic values. Although bradycardia was noted after administration of labetalol, it seemed acceptable except for one patient who needed atropine right after receiving labetalol and another patient who needed levophed infusion after tumor removal. During tumor removal, the blood pressure of all patients was stable except one patient who needed sodium nitroprusside infusion together with labetalol to help control the elevated blood pressure. All the patients in our study had no sequela postoperatively. We concluded that total dose of labetalol (2 mg/kg) administered intravenously at the beginning of anesthesia was possible to control blood pressure during the resection of pheochromocytoma under general anesthesia even in the case of poor preoperative blood pressure control.

Adrenal Gland Neoplasms↗
PubMed1993

The effect of high dose intravenous labetalol on plasma glucose during surgery.

As high dose intravenous labetalol was always used in performing deliberate hypotensive anesthesia and it was reported that small dose of intravenous labetalol would decrease the hyperglycemic response under surgical stress, high dose intravenous labetalol may theoretically causes more pronounced reduction in plasma glucose. 14 female cervical cancer patients (ASA physical status I-II) undergoing radical total hysterectomy were selected and randomly assigned into two groups (group A and group B). The anesthesia was induced with 2.5% sodium thiopental 4 mg/kg, atropine 0.3 mg, succinylcholine 1.5 mg/kg and fentanyl 3 micrograms/kg intravenously. The anesthesia was maintained with isoflurane, nitrous oxide, oxygen and vecuronium under artificial controlled ventilation. Radial artery was cannulated for continuous blood pressure monitoring and blood sampling. The first sample was taken after intubation and before skin incision and the second sample was taken 5 minutes after skin incision in group A and after giving total dose of labetalol in group B, other blood samples were taken every 30 minutes thereafter. No labetalol was given in group A patients. In group B, labetalol (1.0-1.5 mg/Kg) was administrated intravenously in repeated bolus (10 mg/bolus) to achieve a mean blood pressure around 60 torr after skin incision. All the fluid administered intraoperatively was free of glucose. Any patients with blood loss greater than 1000 ml or having blood transfusion before the 5th samples (S5) were excluded because stored blood was rich of glucose. The result revealed that plasma glucose rose significantly in both groups but the rise occurred later in group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

In vitro perfusion study of the human placenta at term: preliminary results.

Dual perfusion of the human placental lobule in vitro is a useful method for studying the transfer of molecules across the placenta, including the transfer of endogenous substances and xenobiotics. To establish the first model of in vitro placental dynamic study in our country, we used a dual recirculating perfusion system modified from that described by Miller et al. A placental lobule without tears or gross lesions was chosen. Both the fetal and maternal sides of the placenta were perfused with Medium 199 in addition to heparin, glucose, dextran and antibiotics. Perfusate samples were obtained periodically and analyzed for blood gas, glucose, lactate, human placental lactogen (hPL) and human chorionic gonadotropin (hCG). The stability of this human placental lobule preparation during 10 hours of perfusion was reflected by the stability of the arterial pressure and by the constant volume in the fetal compartment. A constant rate of oxygen was delivered by the maternal circulation system, and a steady rate of oxygen was gained by the fetal circulation system. Neither oxygen nor glucose consumption by the tissue was significantly reduced during the period of perfusion. The releasing rates of hCG and hPL did not change significantly during perfusion. The development of this dual perfusion system for the human placenta can provide for the study of placental hemodynamics and transplacental transport in perinatal medicine in our country.

Female↗
PubMed1989

In vitro testing of elastomeric modules.

This study describes the in vitro testing of elastomeric modules. Measurements were first made from study models to establish the clinical distance over which modules are used for canine retraction. From this preliminary study, a typodont, banded with 0.018" x 0.025" standard edgewise brackets, was set up with the canine-molar distance at 28 mm. Modules for canine retraction were then fitted by 11 clinicians. The applied force ranged from 125 to 310 g (221 +/- 51 g). A similar, but more extensive study using six different types of modules and two clinician groups (experienced and less experienced clinicians) was then undertaken. Mean force values for different module types ranged from 195 +/- 45 g to 318 +/- 90 g. There was no statistically significant difference between the force values applied by experienced and less experienced clinicians.

Cuspid↗
PubMedDate not supplied

A hierarchical model for PACS.

In this paper, a hierarchical model for Picture Archiving and Communication Systems (HPACS) is presented and implemented at Taichung Veterans General Hospital (TCVGH) in Taiwan. Despite the fact that the HPACS is built on the architecture of the second generation PACS, it offers many improved features and has advantages over the second generation PACS, such as the user security control, fast resource dispatch and efficient resource management. This HPACS can be used as a reference model for a hospital with any scale-size. The real implementation of HPACS is currently undertaken in the Taichung Veterans General Hospital (TCVGH), Taiwan, Republic of China and consists of four phases with the first two phases already completed. It is the first pilot system ever to be implemented successfully in a large-scale hospital in Taiwan. The experiences have illustrated the great promise of the HPACS in the future.

Computer Communication Networks↗