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Biomedical subjects

J Loke

Publications and source records attributed to J Loke.

At least 19 recordsLinked to original sources
PubMed1992

Lung function in fire fighters.

Lung function tests were performed on 49 fire fighters of the city of New Haven. Their mean age was 36.4 years, with a mean of 11.7 years as fire fighters. The lung function tests were compared to a control group with a mean age of 33.4 years. There was no significant difference between the mean normal pulmonary function tests of the fire fighters and the control group. The results showed that in this group of fire fighters long-term occupational exposure was not associated with pulmonary function abnormalities.

Adolescent↗
PubMed1989

The pulmonary function laboratory.

The pulmonary function laboratory is essential for evaluating patients with respiratory complaints and disorders. Lung function tests are widely used to detect evidence of disease, quantitate severity of dysfunction, elucidate pathophysiologic mechanisms, and assess response to therapy. For these reasons, standards for personnel, infection control and safety, equipment, and quality control are important considerations for the generation of physiologic data.

Humans↗
PubMed1988

Terbutaline and diaphragm function in chronic obstructive pulmonary disease: a double-blind randomized clinical trial.

We conducted a double-blind, randomized crossover trial to evaluate whether oral terbutaline (2.5 mg orally three times daily for a week) increased the force of diaphragmatic contraction in normocapnic patients with chronic obstructive pulmonary disease. Ten patients with moderate to severe airway obstruction completed the trail. Compared with placebo, terbutaline produced a mean increase of 5.8 cmH2O in peak inspiratory mouth pressure and a mean increase of 5.0 cmH2O in transdiaphragmatic pressure during a maximal inspiratory manoeuvre. These small changes with terbutaline failed to achieve statistical significance. Also, terbutaline failed to alter flow rates (FEV1, Vmax50) or patients' dyspnoea ratings using two separate clinical scales (Pneumoconiosis Research Unit Score and the Modified Dyspnoea Index). Because all observed changes in respiratory muscle strength were small and because the trial had power to detect small changes in inspiratory mouth pressures, we suggest that oral terbutaline at the dose administered in this study has little noteworthy effect on respiratory muscle strength in normocapnic patients with chronic obstructive pulmonary disease.

Aged↗
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↗
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

Ultrafiltration by hemofilter--a new therapeutic measure in intractable ascites.

The clinical efficacy of ultrafiltration (UF) of ascitic fluid with hemofilter in the treatment of intractable ascites associated with chronic liver disease or intraabdominal malignancy was studied in fifteen patients. The ascitic fluid was reinfused into the peritoneal cavity after ultrafiltration. An average of 6.2 liters of fluid was removed during 4.4 hours of ultrafiltration with no significant change in blood pressure, central venous pressure, hemoglobin, platelets or plasma creatinine. Ascitic fluid albumin rose significantly immediately after the procedure (from 5.2 +/- 4.3 gm/L to 31.9 +/- 30.0 gm/L, P less than 0.01). The plasma albumin concentration increased significantly at the end of UF (P less than 0.001). Also there was a significant increase in urine output (P less than 0.001), urinary sodium excretion (P less than 0.001), and endogenous creatinine clearance (P less than 0.01) during the 48 hours following UF. There was no evidence of hemodynamic, renal or hematological dysfunction, and other complications, including encephalopathy, peritonitis and variceal bleeding were not experienced. Ultrafiltration of ascitic fluid with hemofilter may be safely used in the temporary relief of refractory ascites due to cirrhosis or intra-abdominal malignancy.

Adolescent↗
PubMed1986

Carbon dioxide sensitivity in panic anxiety. Ventilatory and anxiogenic response to carbon dioxide in healthy subjects and patients with panic anxiety before and after alprazolam treatment.

One hypothesis that could account for the anxiogenic response to breathing air supplemented with carbon dioxide seen in panic anxiety patients is that panic patients might have abnormally high central medullary chemoreceptor sensitivity. Chemoreceptor sensitivity was assessed by using a rebreathing technique to measure the ventilatory response to CO2 in 14 medication-free patients with agoraphobia and panic attacks and 23 healthy subjects. Ventilatory response to CO2 was similar in patients and controls (mean +/- SEM, 1.58 +/- 0.16 vs 1.58 +/- 0.14 L/min/mm Hg), suggesting that abnormal chemoreceptor sensitivity does not explain the behavioral sensitivity of panic patients to CO2. Anxiety ratings increased markedly during rebreathing both in patients and controls; anxiety increases were significantly greater in patients than in healthy subjects matched for age, sex, and rebreathing duration. Alprazolam treatment in eight patients markedly attenuated anxiety increases during rebreathing. Differences in anxiogenic sensitivity to CO2 between patients and controls may be due to differences in the regulation of noradrenergic or other neuronal systems.

Adult↗
PubMed1986

Acute effects of passive smoking on lung function and airway reactivity in asthmatic subjects.

We studied the acute effects of one hour of passive cigarette smoking on the lung function and airway reactivity of nine young adult asthmatic volunteers. At the time of this study, the subjects were asymptomatic and had normal or nearly normal lung function. Passive smoking produced no change in expiratory flow rates. However, there was a small decrease in nonspecific bronchial reactivity, as assessed by methacholine inhalation challenge testing (p = 0.022). Pharmacologically active substances present in cigarette smoke, such as nicotine, may explain the observed change in airway reactivity. Although the finding of decreased airway reactivity might suggest that passive smoking produces a "protective" effect on the underlying asthma, the observed change in reactivity was slight and of uncertain clinical significance. We conclude that passive smoking presents no acute respiratory risk to young asymptomatic asthmatic patients.

Adult↗
PubMed1986

The aging lung.

Structural changes occur in the respiratory system with advancing age. Lung elasticity decreases, stiffness of the chest wall increases, and respiratory muscle strength declines. These alterations contribute to gradual, but progressive, reductions in forced vital capacity, expiratory flow rates, diffusing capacity, gas exchange, ventilatory drive, and respiratory sensation. Cigarette smoking accelerates the age-related decline in flow rates. Understanding the effects of aging on the lung is important in order to distinguish pathologic changes from changes that are part of the normal aging process.

Adult↗
PubMed1986

Intratumoral Bacillus Calmette-Guérin immunotherapy prior to surgery for carcinoma of the lung: results of a prospective randomized trial.

A prospective randomized trial of preoperative intratumoral therapy with Bacillus Calmette-Guérin (BCG) was conducted in non-small cell lung cancer patients. Eighty-eight patients (48 BCG-treated and 40 control subjects) were entered into the study; three control subjects were removed from data analysis because histology revealed pathology other than non-small cell lung cancer. There were no differences between BCG-treated and control patients in sex, age, cigarettes smoked per day, pack-years of cigarette smoking, white blood cell count, or number of peripheral blood lymphocytes. Toxicity of BCG was limited to transient malaise and fever (average peak temperature, 38.7 degrees C). There was no significant difference in outcome (recurrence or survival) between BCG-treated and control groups with Stage I or Stage III tumors; there were too few Stage II tumors for separate statistical analysis. Outcome was not affected within or between the two treatment groups by tuberculin skin test status. Combining both treatment groups, Stage III patients had a worse outcome than did Stage I-II patients, non-squamous cell tumor patients (large cell and adenocarcinoma) had worse outcomes than did squamous cell tumor patients, and men had a worse outcome than women. We conclude that, although preoperative intratumoral BCG therapy is safe, it does not lengthen disease-free interval or prolong survival in patients with non-small cell lung cancer.

Bacterial Vaccines↗
PubMed1985

Volumetric responses of right and left ventricles during upright exercise in normal subjects.

We evaluated the volumetric responses of the right and left ventricles to upright exercise using two noninvasive methods, first-pass radionuclide angiocardiography and the CO2 rebreathing technique, in nine normal subjects. Right (RV) and left (LV) ventricular ejection fractions, heart rate, and cardiac index were determined at rest and during steady-state exercise on the bicycle ergometer at 50% of maximal O2 consumption. From these data, stroke volume index (SVI), end-diastolic volume index (EDVI), and end-systolic volume index (ESVI) were derived. SVI increased from 40 +/- 7 ml/m2 at rest to 59 +/- 13 ml/m2 with exercise (P less than 0.001). RVEDVI increased significantly from 82 +/- 16 ml/m2 at rest to 95 +/- 21 ml/m2 during exercise (P = 0.008), while there was no significant change in RVESVI with exercise. Changes in LVEDVI and LVESVI during upright exercise were similar to the right ventricle. The increase in systolic blood pressure during exercise, along with no change in LVESVI, indicated enhanced ventricular contractility. The normal augmentation in SVI during submaximal exercise was due to both the Frank-Starling mechanism and an increased contractile state. Application of these or similar techniques may be useful in evaluating ventricular performance in patients with cardiorespiratory dysfunction.

Blood Pressure↗
PubMed1985

Sustained-release theophylline reduces dyspnea in nonreversible obstructive airway disease.

Although orally administered theophylline has been prescribed widely in patients with nonreversible airway obstruction, symptomatic benefit has not been established. To assess the effects of orally administered theophylline on dyspnea, we performed a randomized, double-bind, crossover, placebo-theophylline clinical trial in 12 ambulatory male patients with moderate to severe nonreversible airway obstruction. Dyspnea was rated using 2 clinical indexes based on 3 components affecting breathlessness: functional impairment, magnitude of task that evokes dyspnea, and the associated magnitude of effort. Dyspnea and physiologic parameters were measured on 4 occasions: at baseline, 4 wk after initial treatment, a second baseline after a 2-wk washout period, and 4 wk after the second medication. For the 12 patients, mean age (+/- SD) was 60 +/- 7 yr, forced expiratory volume in one second was 1.36 +/- 0.67 L (mean, 40% of predicted), and arterial oxygen tension was 71 +/- 10 mmHg. During the treatment phase, all patients had a therapeutic theophylline blood level (range, 12 to 19 micrograms/ml). Theophylline significantly decreased the components of functional impairment (p = 0.02) and magnitude of task (p = 0.02) relating to dyspnea, as well as the overall dyspnea rating (p = 0.01). There were no significant differences between placebo and theophylline therapy for spirometry, arterial blood gas tensions, and the 12-min walking distance. Thus, sustained-release theophylline significantly reduced dyspnea in these ambulatory patients with moderate to severe nonreversible airway obstruction without altering lung function, gas exchange, or exercise performance.

Administration, Oral↗
PubMed1985

Determination of cardiac output at rest and during exercise by carbon dioxide rebreathing method in obstructive airway disease.

We evaluated the accuracy of the CO2 rebreathing method (CO2rb) for measuring cardiac output at rest and during steady-state exercise in 15 patients (mean +/- SD age, 59.7 +/- 7.5 yr) with obstructive airway disease. At rest, there was a significant correlation between direct Fick and CO2rb methods using measured arterial PCO2 (r = 0.70; p = 0.002), but not with using end-tidal PCO2 (r = 0.38; p = NS). During exercise, there was greater correlation with CO2rb using arterial PCO2 (r = 0.79; p = 0.001) than using end-tidal PCO2 (r = 0.63; p = 0.007) compared with the direct Fick determination. Correlation between the CO2rb and direct Fick methods was greater with moderate air-flow obstruction (n = 6) than with severe airway disease (n = 9), and the CO2rb method was more accurate during exercise than at rest. The CO2rb method using either end-tidal or arterial PCO2 underestimated the direct Fick measurement in 13 of 15 patients at rest, which may reflect inadequate equilibration between alveolar and oxygenated mixed venous PCO2. However, no consistent error was observed during exercise when higher CO2 production and an increased venoarterial PCO2 difference would diminish potential inaccuracies. We concluded that the CO2rb technique is an acceptable method for measuring cardiac output during exercise in patients with moderate and severe obstructive airway disease as long as arterial PCO2 is directly measured rather than estimated from end-tidal PCO2.

Aged↗
PubMed1985

Acute bilobar collapse secondary to endobronchial metastatic seminoma.

We report here a patient with tracheal and endobronchial metastatic seminoma who presented with acute respiratory failure with right upper and middle lobe collapse. Diagnosis of the etiology of the atelectasis was made by fiberoptic bronchoscopy. Radiation therapy caused a marked reversal of the atelectasis.

Acute Disease↗
PubMed1978

Assessment of cardiac performance with quantitative radionuclide angiocardiography: right ventricular ejection fraction with reference to findings in chronic obstructive pulmonary disease.

A reproducible noninvasive technique for measuring righ ventricular ejection fraction was developed using first pass quantitative radionuclide angiocardiography. Studies were obtained in the anterior position with a computerized multicrystal scintillation camera with high count rate capabilities. Right ventricular ejection fraction was calculated on a beat to beat basis from the high frequency components of the background-corrected right ventricular time-activity curve. In 50 normal adults, right ventricular ejection fraction averaged 55 percent (range of 45 to 65 percent). This radionuclide measure of right ventricular function was reproducible, with minimal inter- and intraobserver variability, and was sensitive to changes in inotropic state induced with isoproterenol. In 36 patients with chronic obstructive pulmonary disease, right ventricular ejection fraction ranged from 19 to 71 percent. All 10 patients with corpulmonale, as well as 9 additional patients, had an abnormal right ventricular ejection fraction. Arterial oxygen tension and forced expiratory volume were depressed significantly more in patients with abnormal right ventricular ejection fraction than in subjects with normal right ventricular function. There was no relation between abnormalities in right and left ventricular ejection fraction.

Adult↗
PubMed1977

Radiographic manifestations of acute smoke inhalation.

Acute smoke inhalation may lead to serious pulmonary injury and contribute significantly to mortality of fire victims. The chest radiographic findings in 21 patients with acute smoke inhalation are analyzed, and possible pathophysiologic mechanisms responsible for the radiographic abnormalities noted are discussed. Patients with surface injury burns were intentionally eliminated from this study. Our findings indicate that the standard chest radiograph is an insensitive means of determining pulmonary injury by smoke inhalation. The importance of blood carboxyhemoglobin levels and arterial blood gas determinations in the clinical evaluation of patients with acute smoke inhalation is stressed.

Acute Disease↗