Biomedical subjects

K H Chan

Publications and source records attributed to K H Chan.

At least 199 records · Page 11Linked to original sources

PubMed1991

Epidural tramadol for postoperative pain relief.

Forty-two surgical patients were given epidural tramadol for control of postoperative pain. They were randomly assigned to three groups: group 1 (n = 15), in which 25 mg of tramadol were given; group 2 (n = 13), in which 50 mg of tramadol were given; and group 3 (n = 14), in which 75 mg of tramadol were given. When the patients complained of wound pain, epidural tramadol was given. Heart rate, blood pressure, respiratory rate, oxygen saturation (SpO2), sedation scale, motor blockade, verbal rating scale, subjective grading, and visual analogue pain scale (VAPS) were measured and recorded before the tramadol administration, at 5 and 15 min, and at 1, 2, 4, and 8 h after the tramadol administration. Only 26.6% of the patients in group 1 had significant relief of pain. The rest of them needed at least one incremental dose of 25 mg of tramadol. The baseline VAPS of the patients in group 2 was 8.9 +/- 2.0. It became 5.46 +/- 3.0 (p greater than 0.05) 15 min after tramadol was given, and dropped further to 1.9 +/- 1.8 (p greater than 0.05) 2 h later. The average duration of pain relief was 12.0 +/- 5.9 h. In group 3, the initial VAPS was 8.14 +/- 1.9. It decreased to 4.28 +/- 1.8 (p greater than 0.05) 15 min, and further dropped to 1.7 +/- 0.9 (p greater than 0.05) 2 h following tramadol administration. The average duration of pain relief was 11.3 +/- 4.8 h. The common side effects of tramadol such as dizziness, nausea, and dry mouth, were most frequently found in group 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

The risk of intracranial complications in pediatric head injury. Results of multivariate analysis.

Retrospective analysis of 12,072 pediatric head injury cases admitted to hospital revealed 159 patients with intracranial complications: 132 had intracranial hematoma and 27 had diffuse brain swelling. Multivariate analysis revealed two risk factors that could be recognized easily by primary-care physicians. They were found to be significant in predicting the development of intracranial complications. These risk factors were impairment of consciousness at the time of admission and clinical and/or radiological skull fracture. Analysis revealed that the combination of impaired consciousness and skull fracture carried the highest risk of complication (75%); however, the presence of impaired consciousness alone had an intermediate level of risk (19%). The presence of skull fracture alone carried a small overall risk (2%); however, this was highly dependent on age. The absence of all the risk factors considered carried a negligible risk of intracranial complications, provided proper skull X-rays were taken and correctly interpreted.

Adolescent↗

PubMed1990

A staged laryngotracheal reconstruction using alloplast (Proplast) in the canine model.

Standard laryngotracheal reconstructive procedures are constrained by the availability of grafting materials and the ability to repair large defects. Reconstruction utilizing alloplasts may be ideal, but previous results have generally been poor. We present a two-stage procedure using Proplast to reconstruct large laryngotracheal defects in 6 dogs. A custom-made Proplast implant was inserted into a strap muscle pocket and buccal mucosa was placed in the adjacent peritracheal tissue. The muscle-Proplast composite graft was rotated to repair a large defect (3.25 cm by 2.25 cm). All 6 dogs survived. Endoscopic and histologic studies over 12 months showed continued stabilization and maturation of the implant. We feel that Proplast may be used as an alternative to autograft for reconstructing large laryngotracheal defects when the procedure is staged to allow maximal fibrous ingrowth and the implant is protected from infection.

Aluminum↗

PubMed1990

An unusual complication of silastic dural substitute: case report.

A case is presented in which a patient developed an unusual complication after the use of Silastic dural substitute. In 1983, the patient underwent removal of a meningioma with the involved dura. Five years later, he developed around the graft material a very thick connective tissue capsule, which simulated a recurrent meningioma clinically and radiologically.

Brain Edema↗

PubMed1990

The significance of skull fracture in acute traumatic intracranial hematomas in adolescents: a prospective study.

A prospective study was conducted to validate the retrospective finding that adolescents (11 to 15 years old) with skull fractures were prone to develop acute traumatic intracranial hematoma (ICH). Over a 4-year period, 1178 consecutive adolescents attended the emergency room directly, of whom 760 were discharged well and 418 were admitted. All underwent skull x-ray studies. Immediate computerized tomography (CT) scans were performed in patients with Glasgow Coma Scale (GCS) scores of less than 15, in those with radiological and/or clinical evidence of skull fracture, and whenever clinically indicated. Of the 418 admitted patients, only 26 had skull fractures; 13 of these developed ICH. Four patients without skull fracture developed diffuse brain swelling. The remaining 401 patients were discharged after observation periods of up to 48 hours. Of the 13 patients with ICH, 10 had admission GCS scores of 15; however, four deteriorated rapidly and required urgent operation, and four remained stable but were operated on due to their large ICH. Two required conservative treatment only and both made good recovery. Three patients were in coma (GCS score less than or equal to 8) on admission. One patient had an epidural hematoma and made good recovery after surgery. Two developed delayed ICH after operations for associated systemic injuries despite initial CT showing diffuse brain swelling only, and both died despite evacuation of the ICH. Multivariate analysis showed that skull fracture was the only independent significant risk factor in predicting ICH in adolescents (sensitivity of 100% and specificity of 97%). A routine skull x-ray study is therefore mandatory in all head-injured adolescents and, if a skull fracture is detected, immediate CT may be performed for early detection of ICH.

Acute Disease↗

PubMed1990

Flumazenil as an antagonist for midazolam anesthesia in outpatient surgery.

Rapid recovery is an essential component in the anesthesia of OPD surgery. In this study midazolam, the short-duration benzodiazepine, was used as an intravenous anesthetic in OPD surgery. At the end of the operation flumazenil, the specific antagonist of benzodiazepines, was given to reverse the effect of midazolam. Recovery of these patients was compared with those in the control group who received saline instead of flumazenil. In a randomized, placebo-controlled clinical study the antagonistic effect of flumazenil on midazolam was investigated in fifty ASA class I-II gynecologic outpatients subjected to D & C procedure under anesthesia induced with midazolam (0.3 mg/kg). They were divided into group A (flumazenil group) and group B (placebo group) with 25 patients in each. At the end of operation patients in group A were given 0.2 mg flumazenil intravenously to antagonize the residual effect of midazolam while patients in group B were given 2 ml normal saline intravenously as control. Our results showed that patients in group A exhibited a rapid and steady return of consciousness scaled by alertness, orientation of time and place and activity collaboration at 5, 30 and 60 min intervals following administration of flumazenil (p less than 0.005). There were no significant changes found in the hemodynamic or respiratory aspect between groups (p greater than 0.05). All the patients tolerated midazolam and flumazenil well. It is concluded that the use of flumazenil to antagonize the residual effect of midazolam is safe and effective as far as outpatient procedure is concerned.

Adult↗

PubMed1990

The use of ketanserin for postoperative hypertension after abdominal surgery.

Eighteen adult patients who developed hypertension (systolic blood pressure greater than 160 mmHg, diastolic blood pressure greater than 90 mmHg or both) at the early recovery period after major abdominal surgery were included in the study. Following intravenous injection of 10 mg ketanserin, eleven out of eighteen patients (61%) had their systolic or diastolic blood pressure fell below the target mark (160 mmHg and 90 mmHg), and the decrease was statistically significant (p less than 0.01 up to 120 min). There was no statistically significant change in heart rate. Four patients (22%) responded to 20 mg of ketanserin. Three patients (17%) did not have significant decrease of the blood pressure after 20 mg of ketanserin and they received other antihypertensives instead. No severe hypotensive episode was noted. We concluded that ketanserin is a moderate, rapid-onset and safe antihypertensive agent in treating postoperative hypertension following major abdominal surgery.

Abdomen↗

PubMed1990

Clinical application of infrared thermography in diagnosis and therapeutic assessment of vascular ischemic pain.

Temperature is a very important and useful manifestation of various disease entities. The importance of body temperature as an indicator of disease has been known for centuries but in recent years attention has also been paid to how to conveniently and effectively make use of skin temperature as a diagnostic tool. Skin temperature can be measured with thermocouples, electronic thermistor-thermometers, electronic integrators, liquid crystal thermography, and infrared thermography. The temperature of extremities is largely dependent on the blood flow through peripheral vessels, and in the study of vascular diseases thermography has been, therefore, found to be useful. Blood flow can be assessed by many methods including washout techniques or laser Doppler flowmetry. Of these, infrared thermography has the advantages of being noninvasive, remote from the patient when in use, and capable of producing multiple recordings at short time intervals. Here we present a case of vascular ischemic pain which was diagnosed and therapeutically assessed by thermography.

Aged↗

PubMed1990

The hemodynamics and clinical effects of labetalol in hypotensive anesthesia.

Labetalol is a relatively new and unique hypotensive agent that has both alpha- and beta-adrenoceptor blocking properties. 12 patients in fit physical condition who underwent elective oral surgery were subject to hypotensive anesthesia with labetalol to assess the hemodynamic aspects and clinical effects of the drug. All of them had their anesthesia maintained with halothane and N2O in 50% O2 supplemented by fentanyl and vecuronium. Initiation of deliberate hypotension was made with intravenous bolus of labetalol at 0.5 mg/kg and the ideal level of mean arterial pressure at 55 +/- 5 mm Hg was maintained with adjustment of the concentration of halothane. At the termination of deliberate hypotension, the blood pressure was recuperated to the baseline level by lowering the concentration of halothane and administration of 0.5-0.6 mg intravenous atropine. Our results showed that the total dose of labetalol used was 44 +/- 13 mg and blood loss amounted to 354 +/- 136 ml. Important changes of hemodynamic parameters before and after labetalol included the fall of mean BP, HR, mean PAP, CI, LVSWI, SVRI, PVRI and O2 delivery and the increasing of O2 extraction. As to CVP, PCWP, SVI, O2 consumption and shunting the alterations were minimal. Blood gas analysis showed that, save a slight fall of pH indicating mild metabolic acidosis, the PaO2 and PaCO2 remained unchanged following the use of labetalol. Labetalol-induced hypotension could be effectively reversed by using of atropine as shown in our study and all the patients recovered uneventfully from hypotensive anesthesia. They were entirely free from any complication or sequela relevant to the deliberate hypotension after one year's follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

Early detection of cerebral dysfunction by quantitative EEG during cardiopulmonary-bypass period for open-heart surgery.

Neuropsychiatric complications are well known risks of open heart surgery. In this regard cerebral damage is caused either by microembolism or insult from low perfusion pressure as a consequence of extracorporeal circulation. It seems probable that monitoring of the quantitative electroencephalography (QEEG) during the surgical procedure can help minimize the incidence of neurological sequelae through early detection. Moreover, it seems important to establish whether the pre-operative EEG has a predictive value for the possible neurological outcome and whether the post-operative EEG has conclusive value for the neurological outcome and, above all to ascertain whether the peri-operative QEEG contains information valuable on the diagnosis of final neurological outcome. To elucidate the feasibility of QEEG as a means to monitor the cerebral function a study was thus undertaken. Twenty-five ASA II-IV patients with age ranging from 25-79 y/o undergoing cardiac surgery under extracorporeal circulation were enrolled for study. The types of surgery varied from coronary artery by-pass graft (CABG), valvular replacement, and excision and grafting for aortic dissecting aneurysm. 16-channel EEGs were recorded with a Cadwell Spectrum 32 in accordance with the international 10-20 system. 48 epochs (1 epoch = 2.5 seconds) of EEG recordings of pre-bypass and post-bypass periods were measured and quantitatively analyzed. Pre- & post-operatively, psychoneurological assessments were performed and correlated with the QEEG. The parameters employed in the study were absolute power, relative power, power asymmetry, and coherence. All the results of two-session comparisons were transformed into z score values. Our preliminary study revealed that there exists a specific multivariate profile of QEEG for specific disease entity. And all the patients with z score less than or equal to 3.0 turned out to be free from any significant sequelate.

Adult↗

PubMed1990

Uptake of labelled proline in the degenerating retina of goldfish.

A goldfish model with degenerating retina was utilized. Degeneration of inner nuclear layer and ganglion cell layers began prior to degeneration of outer nuclear layer. In these models, the photoreceptors still showed uptake of labelled proline. This indicated that the metabolic activities of the first order neuron was independent to its neuronal linkage with other neurons.

Animals↗

PubMed1989

Fatigue of acrylic bone cement--effect of frequency and environment.

This study was conducted to investigate some fundamental fatigue testing variables as they apply to the response characteristics of acrylic bone cement. Cyclic loading under load control was conducted at frequencies of 1, 2, 5, 10, and 20 Hz in air at room temperature. At a tensile stress range of 0.3-20.0 MPa the fatigue life increased linearly with logarithmic frequency. The effect of conditioning and testing in saline at both room temperature and 37 degrees C at similar stress levels and a frequency of 10 Hz were also examined. When compared to dry testing at room temperature, testing in saline at 37 degrees C resulted in a reduction in fatigue life while testing in saline at room temperature produced an increase in fatigue life. Of a number of statistical distributions considered, the Weibull was found to be the most appropriate in documenting the findings of this investigation. A companion fractographic investigation of the failure surfaces demonstrated distinct regions of crack growth and fast fracture.

Acrylates↗

PubMed1989

Reactivity of a new Pan-B monoclonal antibody (MA6) against human leukaemias.

The reactivity of a new Pan-B monoclonal antibody, MA6, against 69 cases of ALL, three plasmacytoma, 10 AML and five CML was evaluated. The antibody reacted positively against five of the 11 cases of U-ALL, 15 of the 26 C-ALL and all the cases of Pre B-ALL (one), B-ALL (one), B-CLL (12) and HCL (two). The MA6 did not react against the 16 cases of T-ALL, three plasmacytoma, 10 AML and five CML. The antibody has a broader spectrum of B-cell reactivity than CD9 and CD20 but is similar to the Pan-B antibody, CD19. MA6 appears to react against some of the very immature B cells and is therefore potentially useful, in conjunction with other antibodies such as CD9 and CD19, to confirm the B-lineage of some cases of U-ALL. The difference in the spectrum of reactivity against B-cell malignancies between MA6 and the other CDw40 antibody, G28-5, confirms their difference in antigenic specificity.

Antibodies, Monoclonal↗

PubMed1989

Neurosurgical aspects of cerebral cryptococcosis.

Eleven patients with raised intracranial pressure caused by cerebral cryptococcosis developed complications requiring neurosurgical operations. Two patients were fully conscious on admission, and 9 had impaired consciousness, four of whom were comatose. Seven patients were found to have hydrocephalus only. Two patients had cerebral edema initially, and 2 had cystic lesions. One of the latter developed subdural effusion. All patients eventually developed progressive hydrocephalus requiring placement of a ventriculoperitoneal shunt. Four patients were initially treated by external ventricular drainage. When external ventricular drainage was used initially, there were no associated complications; however, there was a high incidence of complications (4 of 7 patients) when a ventriculoperitoneal shunt was placed as the initial treatment. Of the 11 patients, 10 (91%) survived; of these 9 (82%) made an excellent recovery and 7 (64%) returned to their original work. The patient who died had been receiving steroid therapy for hypopituitarism.

Adolescent↗

PubMed1989

Factors influencing the development of gastrointestinal complications after neurosurgery: results of multivariate analysis.

A retrospective review of 526 patients who underwent neurosurgery for nontraumatic conditions over a 5-year period revealed 36 (6.8%) patients with endoscopically and or surgically documented postoperative gastrointestinal (GI) complications. Two patients had GI bleeding and perforation, and the remaining patients had bleeding only. Multivariate analysis indicated 5 factors that were of independent significance in predicting the development of postoperative GI complications. These factors included 1) inappropriate secretion of antidiuretic hormone, 2) preoperative coma (Glasgow Coma Score less than 9), 3) the presence of postoperative complications, 4) age greater than or equal to 60 years, and 5) pyogenic infection of the central nervous system. Further analysis of the 36 patients with GI complications revealed that they could be divided into three groups with different clinical courses. In Group I (n = 10), all patients died as a result of their neurological conditions; GI complications were just preterminal events and did not require treatment. In Groups II (n = 11) and III (n = 15), GI complications were symptomatic and life-threatening events, respectively. Eleven patients from Group III died as a direct result of the GI complications. Separate multivariate analyses based on the patients in Groups II and III revealed that preoperative coma was the only significant factor that predicted the occurrence of life-threatening complications. Patients who are at high risk of developing postoperative GI complications can thus be identified, and intensive prophylaxis may be instituted.

Brain Diseases↗

PubMed1989

Failure of cimetidine prophylaxis in neurosurgery.

Three hundred and eight-one patients who underwent major neurosurgical procedures were given cimetidine prophylaxis against stress ulceration. Nine patients (2.4%) developed acute gastrointestinal complications; two patients had perforation and bleeding from gastroduodenal ulcers, and seven patients had bleeding alone. Six of these patients, all above the age of 70 years, died as a consequence of the complication. Univariate analysis showed that four variables--state of consciousness, syndrome of inappropriate secretion of antidiuretic hormone, nature of surgery, and age--were significant factors in predicting cimetidine failure. Multivariate analysis revealed that a patient's pre-operative state of consciousness and the presence of inappropriate secretion of antidiuretic hormone were of independent significance in predicting cimetidine failure. The risk was 52% and 0.07%, respectively, when both factors were either present or absent.

Acute Disease↗

PubMed1989

In situ detection of Epstein-Barr virus markers in nasopharyngeal carcinoma patients.

Cryosections of nasopharyngeal tissue from 9 patients suspected of having nasopharyngeal carcinoma (NPC) were examined for the presence of Epstein-Barr virus (EBV) markers in situ to assess virus infection in the nasopharynx. Viral DNA, EB nuclear antigen, and/or early antigens (EA.D and EA.R) were detected in 5 NPC specimens. EBV infection was not confined to the tumor areas of the biopsy specimens. Lymphoid cells and nontumor areas of these specimens contained EBV markers. In addition, nasopharyngeal tissues obtained from 3 of 4 patients in clinical remission for the disease showed evidence of EBV infection.

Antibodies, Monoclonal↗

PubMed1989

An investigation into the use of restriction endonuclease analysis for the study of transmission of mutans streptococci.

Restriction endonuclease analysis (REA) was performed on the total cellular DNA from each of 396 strains of mutans streptococci (1) to determine its potential usefulness for the study of transmission of the organism and (2) to document the proportions and variety of strains harbored by members of a small group of families. The DNA was digested with restriction enzyme EcoRI and/or HindIII, electrophoresed on agarose gels, and the resulting patterns compared. The strains examined included fresh isolates from 58 subjects, including 19 strains from each member of five families. The sensitivity and reproducibility of REA patterns from the mutans streptococci seemed ideal for studies of their epidemiology and transmission. The pattern of each isolate from humans was unique, except for isolates from the same individual or from the same family. REA types from subjects from different families were always heterogeneous. A high frequency of multiple REA types (up to 5) was observed in many subjects. While evidence for intra-familial transmission was obtained, including transmission between spouses, there was also strong evidence of frequent sources of infection outside of the family. Mutations of strains to streptomycin resistance or to lactate dehydrogenase deficiency caused no detectable change in the REA patterns. The lack of plasmids in any of the 57 fresh isolates that were examined for them suggested that they may have contributed little to the heterogeneity of the patterns seen.

Animals↗