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Biomedical subjects

C K Chan

Publications and source records attributed to C K Chan.

At least 217 records · Page 12Linked to original sources
PubMed1988

Oral terbutaline augments cardiac performance in chronic obstructive pulmonary disease.

In previous research, we have demonstrated that parenterally administered terbutaline can augment resting cardiac function in patients with chronic obstructive pulmonary disease (COPD). Because the oral form of terbutaline is more widely utilized, a double-blind, randomized, crossover, placebo-controlled trial of the cardiopulmonary effects of oral terbutaline was conducted in ten patients with COPD. Right and left ventricular ejection fractions (RVEF and LVEF) were determined by first pass radionuclide angiography. There were no differences in spirometry and hemodynamic measurements between treatment and placebo days. Following 5 mg of oral terbutaline, there was a small but statistically significant increase in forced expiratory volume in 1 second and in heart rate, but no significant change in forced vital capacity or blood pressure. LVEF improved significantly with terbutaline both at rest (62% +/- 6% vs. 67% +/- 9%, mean +/- SD) and during submaximal steady state exercise (61% +/- 5% vs. 67% +/- 10%). RVEF improved significantly at rest (64% +/- 6% vs. 69% +/- 5%), but not during submaximal steady state exercise (65% +/- 6% vs. 68% +/- 7%). Thus, oral terbutaline produces significant improvement in biventricular systolic pump performance at rest, and increases left ventricular ejection fraction during submaximal exercise in patients with moderate to severe COPD.

Administration, Oral↗
PubMed1988

Bilateral diaphragmatic paralysis: clinical spectrum, prognosis, and diagnostic approach.

In a retrospective review of the clinical course of five patients with nontrauma-related bilateral diaphragmatic paralysis, we found that the diagnosis is generally delayed (median delay: two years) in the presence of moderate to severe respiratory insufficiencies. Orthopnea out of proportion to the underlying cardiopulmonary status and thoracoabdominal paradoxus in the supine position are the clues to the diagnosis. Pulmonary function tests showed a typical restrictive ventilatory defect, and arterial blood gas showed chronic respiratory acidosis. Failure to recognize the diaphragmatic impairment led to cardiopulmonary decompensations such as cor pulmonale and acute respiratory failure. However, with the institution of appropriate therapy, adverse effects resolved and all five patients are alive and continue to lead independent lives. We conclude that nontrauma-related bilateral diaphragmatic paralysis is an underrecognized and underdiagnosed condition. The results also indicate that early diagnosis and treatment can minimize morbidity and mortality, and that excellent long-term, good-quality survival can be expected.

Aged↗
PubMed1988

Asbestos exposure and laryngeal cancer: an analysis of the epidemiologic evidence.

We conducted a critical analysis of the available epidemiologic investigations on the causal relationship between asbestos exposure and laryngeal cancer. A review of nine case-control studies indicates that the estimated risk (odds ratio) attributable to asbestos exposure alone is negligible when smoking and ethanol intake are appropriately controlled for. Six of the 12 cohort studies demonstrated no significant increase in the standardized mortality ratio due to asbestos exposure. The remaining six longitudinal studies showed an increased standardized mortality ratio from 1.91 to 5.41 but no adjustment was made for the confounding effects of smoking and ethanol consumption. In conclusion, the available epidemiologic evidence does not support a causal association between asbestos exposure and laryngeal cancer.

Alcohol Drinking↗
PubMed1987

The 'epidemiologic necropsy'. Unexpected detections, demographic selections, and changing rates of lung cancer.

When rising rates of occurrence are reported for a particular disease, clinicians often cannot determine whether the disease has increased in actual occurrence or in the improved detection provided by better diagnostic technology and expanded access to medical care. The epidemiologic use of necropsy data, which might help answer these questions, has been inhibited by fears of bias in demographic and clinical selection of patients for necropsy. The demographic problem can be managed by suitable adjustment and standardization of the disease rates found at necropsy, and the clinical problem can be reduced or avoided by studying the rates with which the disease is found unexpectedly in necropsies performed for other, unrelated clinical reasons. The results, obtained in population groups "screened" via necropsy, can suggest the magnitude of the "undetected reservoir" that coexists and supplements the rates of reported occurrence for a disease. In a study of necropsies at Yale-New Haven (Conn) Hospital from 1972 to 1981, the necropsy detection rates for lung cancer were slightly higher for women than for men, and were substantially higher for both genders than the customarily reported rates in the general population. The results suggest that the reported rates may continue to rise in both genders until they become essentially equal at a size approximating that of the currently undetected reservoir. The "epidemiologic necropsy" offers a potentially valuable method to help distinguish the true occurrence rates of disease from the changes attributable to improved diagnostic detection with modern technology.

Adult↗
PubMed1987

Supplemental photocoagulation on the buckle for prevention of surgical revision after scleral buckling procedures.

Supplemental photocoagulation on the buckle appears to be a useful therapeutic modality in selected cases of persistent retinal detachment. In a retrospective review, 71 (63%) of 113 eyes were successfully treated with photocoagulation, thus avoiding the need for surgical revision. Median response time between treatment and postoperative subretinal fluid absorption in the successfully treated eyes was two days, with the majority responding within one day. The one favorable prognostic factor was the use of a soft silicone segmental sponge. Unfavorable prognostic factors included the following: contour of subretinal fluid (combined, ie, both anterior and posterior to the buckle); excessive amount of subretinal fluid; inadequate support of break(s); multiple drainages at first operation; rolled edge in association with a giant break; and residual vitreous traction on the break. Postoperative photocoagulation alone on the buckle did not appear to influence the rate of development of premacular fibroplasia or proliferative vitreoretinopathy.

Adolescent↗
PubMed1987

Misdiagnosis using endoscopic retrograde cholangiopancreatography in a patient with postcholecystectomy pain.

Endoscopic retrograde cholangiopancreatography (ERCP) has become an essential tool to investigate patients with the postcholecystectomy syndrome. A normal cholangiogram usually rules out the presence of biliary tract disease, and further investigations are directed towards other organ systems. We present a case in which a normal ERCP caused a significant delay in reassessing the biliary tree in a patient who eventually presented with choledocholithiasis. A repeat ERCP should be considered in patients with persistent biliary tract pain, even if the initial ERCP shows no abnormality.

Adult↗
PubMed1987

Idiopathic small airways pathology in patients with graft-versus-host disease following allogeneic bone marrow transplantation.

In a retrospective analysis (July 1979 to March 1984) of 120 allogeneic adult bone marrow transplant recipients, we identified seven patients with small-airway disease for whom no microbiologic agent was detected. Six had pulmonary function studies demonstrating air flow obstruction. Five of the seven patients had an open-lung biopsy showing pathologic changes within small airways; these varied from early bronchiolar wall damage to bronchiolitis obliterans. The inflammatory cell infiltrate was peribronchiolar, and consisted of polymorphonuclear leukocytes and lymphocytes in varying proportions. Three of the seven patients recovered following increased immunosuppressive therapy; the other four died. Because all seven patients had acute and chronic graft-versus-host disease, in the absence of any identifiable pathogen, we postulate that small-airway damage represents one of the facets of graft-versus host-disease. An additional analysis of 26 patients with respiratory symptomatology and available histologic material supports the hypothesis that small-airway disease in bone marrow transplant patients represents a risk factor for the subsequent development of respiratory opportunistic infections.

Bone Marrow Transplantation↗
PubMed1987

Small-airways disease in recipients of allogeneic bone marrow transplants. An analysis of 11 cases and a review of the literature.

In a retrospective review of 116 consecutive allogeneic bone marrow transplants (BMT), severe obstructive airways disease was identified in 11 patients. Lung pathology demonstrated bronchiolitis in 9 patients and physiologic studies showed small-airways disease consistent with bronchiolitis in the other 2. None of the 5 patients with associated infection survived, while 3 of the 6 patients without an identified pathogen stabilized or improved. Analysis of the 11 cases presented and all 25 cases reported in the literature (1982 to 1985) supports the conclusion that graft-versus-host disease is a major risk factor for bronchiolitis in BMT recipients. Among the proposed mechanisms for the development of bronchiolitis after allogeneic BMT, the 2 most likely are graft-versus-host disease directly causing bronchiolitis, and increased immunosuppressive therapy given for graft-versus-host disease predisposing to viral bronchiolitis. The available evidence would suggest that it is prudent to obtain serial pulmonary function tests even in asymptomatic patients post-BMT, and particularly in those with chronic graft-versus-host disease, in the hope that early detection will allow for early intervention that will arrest or reverse the progression of the obstructive airways disease.

Adolescent↗
PubMed1987

HLA antigens in chronic pancreatitis.

Since immunological and hereditary factors may be important in chronic pancreatitis, histocompatibility antigens of classes I and II were studied in 50 British Caucasian patients, after exclusion of insulin-dependent diabetics for whom HLA associations are recognised. Chronic pancreatitis was defined by at least two independent criteria, and only subjects with alcohol-related and idiopathic disease were included. In 22 patients (21 male), weekly ethanol intake had chronically exceeded 100 g (usually substantially so); the remaining 28 had idiopathic chronic pancreatitis (ICP). Twenty patients (40%) had autoantibodies, in 11 (22%) to gastric parietal cells. Nine of those with ICP (three male) had parietal cell antibody, more than expected for the age/sex distribution. There were overall increased frequencies of HLA Cw5 and B44. In ICP there were increased frequencies of HLA A25 and Cw1, and a decreased frequency of B7. In patients with alcohol-related disease there were increased frequencies of Cw5 (50.0% vs control 15.9%), B44 (54.5% vs 29.4%), and DR4 (61.1% vs 33.6%). The increased frequency of Cw5 in alcohol-related disease alone remained significant after correction (p less than 0.05). A hypothesis that hereditary and possibly immunological factors may contribute to the aetiology of chronic pancreatitis is supported.

Alcoholism↗
PubMed1987

Diaphragmatic dysfunction in siblings with hereditary motor and sensory neuropathy (Charcot-Marie-Tooth disease).

Hereditary motor and sensory neuropathy (Charcot-Marie-Tooth disease) is characterized by chronic degeneration of peripheral nerves and roots, resulting in distal muscle atrophy, beginning in the feet and legs and later involving the hands. The association of this disease with diaphragmatic dysfunction has not been reported. We studied a patient with hereditary motor and sensory neuropathy type 1 (Charcot-Marie-Tooth disease) and type 2 diabetes mellitus who had severe diaphragmatic impairment. Some of the clinical findings are similar to the sleep apnea syndrome, which could lead to incorrect diagnosis and delay in the administration of appropriate therapy. Transdiaphragmatic pressure studies on the subject's brother, who also has Charcot-Marie-Tooth disease and type 2 diabetes mellitus, revealed subclinical impairment of diaphragmatic function. These findings suggest that phrenic nerve involvement may be part of the spectrum of polyneuropathy in Charcot-Marie-Tooth disease in association with diabetes mellitus.

Aged↗
PubMed1987

Prevention of acute pulmonary edema after bone marrow transplantation.

In a retrospective review of 21 bone marrow transplantation procedures (BMT), we identified ten episodes of acute pulmonary edema coinciding with significant weight gain in the second week after BMT. When we prospectively observed nine consecutive BMT recipients, six patients developed acute pulmonary edema associated with significant (p less than 0.05) weight gain and an increase in echocardiographically determined left ventricular end diastolic diameter. These findings led to a prospective prophylactic intervention study of 30 consecutive BMT patients. Prophylactic intervention consisting of reduced fluid volume of parenteral alimentation, and diuretic therapy was instituted at any clinical sign of fluid overload. No episode of pulmonary edema occurred. The dramatic difference--acute pulmonary edema occurred in 16/30 untreated vs 0/30 treated cases--suggests that this post-BMT complication is critically related to fluid balance and can be prevented by careful clinical examination, close monitoring of weight change, avoidance of fluid overload and the appropriate use of diuretic therapy.

Adult↗
PubMed1987

Timing of oral anticoagulation therapy in the treatment of angiographically proven acute pulmonary embolism.

The optimal time to begin oral anticoagulation therapy with warfarin sodium in the treatment of acute pulmonary embolism has not been defined. To evaluate the relative cost, efficacy, and safety of early initiation of warfarin therapy, we reviewed the medical records of 38 patients with angiographically proven pulmonary embolism. Patients were divided into two groups: those who received warfarin early (less than or equal to 3 days after initial heparin sodium bolus, n = 17) and those who were treated late (greater than 3 days after initial heparin bolus, n = 21). After three months of follow-up, there was a similar incidence of mortality, recurrent pulmonary embolism, and bleeding complications in both treatment groups. Length of hospitalization was substantially less in the early group (9.6 +/- 2.0 vs 11.8 +/- 2.1 days). Early warfarin therapy in the treatment of acute pulmonary embolism appears to be both cost-effective and safe. A prospective multicenter controlled trial should be performed.

Administration, Oral↗
PubMed1987

Pulmonary tumor embolism: a critical review of clinical, imaging, and hemodynamic features.

Pulmonary tumor embolism is a common finding at autopsy but is generally perceived as a difficult diagnosis to make ante mortem. After a retrospective review of 164 reported cases of pulmonary tumor embolism, we identified a typical profile of clinical, laboratory, and imaging features that may permit confident clinical diagnosis in most patients with this condition. The clinical features include a documented or suspected underlying malignancy, acute to subacute onset of dyspnea, and signs of cor pulmonale. Supportive laboratory features are hypoxemia or increased alveolar-arterial oxygen gradient, and invasive or noninvasive evidence of pulmonary artery hypertension. Typical imaging findings are normal chest radiographs; multiple, subsegmental, peripheral perfusion defects on ventilation-perfusion lung scans; and delayed filling with or without subsegmental filling defects but without a thrombus on pulmonary angiogram. Radiolabeled monoclonal antibody imaging and pulmonary microvascular cytology sampling techniques are promising diagnostic tests for early diagnosis of pulmonary tumor embolism.

Adult↗
PubMed1984

Pleuropulmonary melioidosis in a Cambodian refugee.

A 47-year-old Cambodian refugee presented with an acute respiratory illness that featured consolidation of the lower lobe of the left lung and progressive involvement of the adjacent pleura caused by Pseudomonas pseudomallei. Initial difficulty in identifying the organism resulted in an inadequate duration of therapy. Chronic pleural disease followed, and the organism became resistant to many antibiotics during therapy. A diagnosis of pleuropulmonary melioidosis should be entertained and the microbiology laboratory alerted when patients with pneumonia who are from endemic areas are encountered, so that a diagnosis can be made early and the appropriate treatment begun.

Anti-Bacterial Agents↗