RESUMEN
QT dispersion is considered to reflect nonhomogeneity of ventricular repolarization. The autonomic nervous system modulates QT interval duration, but the effect may not be spatially homogenous. Magnetocardiography (MCG) registers the weak magnetic fields generated by myocardial electric currents with high localizing accuracy. We studied the effects of rapid cardiovascular autonomic nervous adjustment on QT dispersion in MCG. Ten healthy male volunteers were monitored during deep breathing, the Valsalva maneuver, sustained handgrip, hyperventilation, the cold pressor test and mental stress. 67 MCG channels and 12 ECG leads were recorded simultaneously. A computer algorithm was used for QT interval measurements. QT dispersion was defined as maximum - minimum or standard deviation of the QTpeak and QTend intervals. In MCG the QT(end) dispersion increased during deep inspiration compared with deep expiration (96+/-19 ms v. 73+/-27 ms, p = 0.05). Magnetic QT dispersion tended to increase during the bradycardia phase of the Valsalva maneuver, but the change was obvious only for QT(end) (55+/-26 ms v. 76+/-29 ms, p<0.05). Other tests had no significant effect on QT dispersion, not even the cold pressor test, although it causes strong sympathetic activation. Magnetic and electric QT(peak) and QT(end) intervals correlated closely (r = 0.93 and 0.91), whereas the QT dispersion measures showed no correlation. In conclusion, magnetic QT dispersion is not modified by rapid changes in autonomic tone, but maneuvers involving deep respiratory efforts and changes in ventricular loading affect QT dispersion measurements.
Asunto(s)
Sistema Nervioso Autónomo/fisiología , Sistema Cardiovascular/inervación , Electrocardiografía , Magnetismo , Adulto , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Factores de TiempoRESUMEN
Changes in autonomic tone modulate QT interval duration. How cardiovascular autonomic reflexes affect QT dispersion, a suggested marker of arrhythmia risk, is not well established. We studied 10 healthy young adult volunteer men during quiet and deep breathing, the Valsalva maneuver, sustained handgrip, hyperventilation, the cold pressor test, and mental stress. An automated method was used for measurement of QT-peak and QT-end intervals, and QT dispersion was defined as maximum-minimum of the measured intervals. QT-peak dispersion was greater on deep expiration than deep inspiration (49 +/- 20 ms vs 37 +/- 14 ms, P < .05). QT-end dispersion decreased in the tachycardia phase of the Valsalva maneuver (45 +/- 23 ms vs 35 +/- 21 ms, P < .05), but QT dispersion did not change during the other interventions. Rapid cardiovascular autonomic reflex adjustment does not change QT dispersion in healthy young adult men. However, large intrathoracic volume and intrathoracic pressure changes during forced respiratory movements might confound QT dispersion measurements.
Asunto(s)
Sistema Nervioso Autónomo/fisiología , Electrocardiografía , Corazón/fisiología , Adulto , Presión Sanguínea/fisiología , Frío , Interpretación Estadística de Datos , Frecuencia Cardíaca/fisiología , Humanos , Hiperventilación/fisiopatología , Masculino , Reproducibilidad de los Resultados , Respiración , Estrés Psicológico/fisiopatología , Maniobra de Valsalva/fisiologíaRESUMEN
BACKGROUND: Although it is well known that impaired pulmonary function is a strong predictor of mortality and that smoking decreases pulmonary function, little is known about the long term effect of smoking cessation on mortality at different levels of pulmonary function. We have studied the impact of smoking cessation on mortality over the entire range of baseline pulmonary function. METHODS: The study subjects consisted of men aged 40-59 at entry who were the Finnish participants in the Seven Countries Study during 1959-89. RESULTS: In all the participants (n = 1582) impaired forced expiratory volume in 0.75 seconds (FEV(0.75)) was significantly associated with increased all cause mortality. When those who gave up smoking during the follow up period were compared with continuous smokers (n = 860) all cause mortality was found to be decreased among those who quit. The relative adjusted hazard (HR) was 0.71 (95% confidence interval 0.50 to 1.00). The median survival time in those who stopped smoking compared with those who continued to smoke from 1969 onwards was 7.65, 7.59, and 6.30 years longer in the lowest, middle and highest tertiles of adjusted FEV(0.75) distribution, respectively. In those who gave up smoking, mortality from cardiovascular causes was significantly lower (HR 0.60 (95% CI 0.37 to 0.98)). CONCLUSIONS: These findings suggest that smokers across the entire range of pulmonary function may increase their expectation of lifespan by giving up smoking.
Asunto(s)
Enfermedades Pulmonares/fisiopatología , Cese del Hábito de Fumar , Fumar/mortalidad , Adulto , Estudios de Cohortes , Finlandia/epidemiología , Estudios de Seguimiento , Volumen Espiratorio Forzado/fisiología , Humanos , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Factores de Riesgo , Fumar/efectos adversos , Fumar/fisiopatología , Análisis de Supervivencia , Tasa de SupervivenciaRESUMEN
The aim of the present experimental study was to examine the effects of local application of glyceryl trinitrate and nicotinic acid on the cold-provoked haemodynamic responses, pain and hand dexterity. Ten young healthy volunteers participated in this randomized, cross-over study with three phases at least two days apart. Five cm of 2% glyceryl trinitrate ointment, 10% nicotinic acid ointment or placebo ointment was applied on the back of each subject's both hands 15 min. before the 7 min. cold exposure. Blood pressure and heart rate were measured prior to, during and after the cold exposure. In addition, the effect of cold on hand dexterity was evaluated by the Purdue pegboard test and the subjects assessed the pain in their hands during the cold exposure. Pretreatment with glyceryl trinitrate ointment counteracted the cold-induced haemodynamic response, as evidenced by a significantly (P < 0.05) smaller mean increase in the systolic blood pressure from the baseline compared with placebo. In contrast, the cold-induced increase in the systolic blood pressure observed after pretreatment with nicotinic acid ointment did not differ from placebo. Both glyceryl trinitrate and nicotinic acid alleviated the cold-induced pain, but neither of them prevented the deterioration of hand dexterity. In conclusion, the haemodynamic response provoked by a brief cold exposure could to some extent be counteracted by pretreatment with glyceryl trinitrate ointment, but not with nicotinic acid ointment, compared with placebo.
Asunto(s)
Presión Sanguínea/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Hipotermia/prevención & control , Niacina/uso terapéutico , Nitroglicerina/uso terapéutico , Umbral del Dolor/efectos de los fármacos , Vasodilatadores/uso terapéutico , Administración Tópica , Adulto , Mano , Humanos , Hipotermia/fisiopatología , Masculino , Pomadas , Método Simple CiegoRESUMEN
It has been suggested that ubiquinone improves exercise performance and antioxidant capacity. We studied the effects of ubiquinone supplementation (120 mg.day-1 for 6 weeks) on aerobic capacity and lipid peroxidation during exercise in 11 young (aged 22-38 years) and 8 older (aged 60-74 years), trained men. The cross-over study was double-blind and placebo-controlled. Serum ubiquinone concentration increased after supplementation (P < 0.0001 for treatment) in both age groups. The maximal oxygen uptake (VO2max) was measured using a direct incremental ergometer test. In the young subjects, the VO2max after placebo and ubiquinone treatment was 58.5 (95% confidence interval: 53.0-64.0) and 59.0 ml.min-1.kg-1 (52.2-66.8), respectively. The corresponding results in the older subjects were: 37.2 (31.7-42.7) and 33.7 ml.min-1.kg-1 (26.2-41.7) (P < 0.0001 for age group, P > 0.05 for treatment). In a prolonged test (60-min submaximal, then incremental load until exhaustion) time to exhaustion was longer after the placebo [young men: 85.7 (82.4-89.0), older men: 82.9 min (75.8-89.9)] than after ubiquinone [young men: 82.1 (78.5-85.8), older men: 77.2 min (70.1-83.7); P = 0.0003 for treatment]. Neither ubiquinone supplementation nor exercise affected serum malondialdehyde concentration. Oral ubiquinone was ineffective as an ergogenic aid in both the young and older, trained men.
Asunto(s)
Ejercicio Físico/fisiología , Ubiquinona/administración & dosificación , Adulto , Aerobiosis , Anciano , Envejecimiento/fisiología , Estudios Cruzados , Método Doble Ciego , Humanos , Peroxidación de Lípido/efectos de los fármacos , Masculino , Malondialdehído/sangre , Persona de Mediana Edad , Consumo de Oxígeno/efectos de los fármacos , Ubiquinona/sangre , Ubiquinona/farmacologíaRESUMEN
Interscalene block may cause phrenic nerve block and decreased diaphragmatic motion. We evaluated the effect of continuous interscalene block on ventilatory function and diaphragmatic motion. We studied ten patients scheduled for surgery or manipulation of the shoulder. Preoperatively, the patients underwent spirometry and double-exposure chest radiography. They received an interscalene block with 0.75% bupivacaine. Thereafter, 0.25% bupivacaine was infused into the interscalene space for 24 h. Spirometry was repeated three times and double-exposure radiography twice. The maximal inspiratory and expiratory pressures were measured repeatedly. Haemoglobin oxygen saturation (SPO2) was monitored with pulse oximetry. The block provided adequate anaesthesia for surgery or manipulation. All patients had a marked ipsilateral paresis of the diaphragm in the radiographs 3 h after the initial block. Twenty-one hours later five patients had diaphragmatic motility comparable to the situation before the block. In the other five patients, the amplitude of diaphragmatic motility on the side of the block was only 4-37% of the values before the block. All patients had a clear reduction in forced vital capacity (FVC), forced expiratory volume in 1s (FEV1) and peak expiratory flow (PEF) 3 and 8 h after the block without signs of dyspnoea. In conclusion, in all our patients interscalene block caused an ipsilateral hemidiaphragm paresis, which in five of ten patients persisted until the end of the continuous block.
Asunto(s)
Plexo Braquial , Bupivacaína , Diafragma/fisiología , Bloqueo Nervioso , Respiración/fisiología , Parálisis Respiratoria/etiología , Adulto , Bupivacaína/efectos adversos , Diafragma/diagnóstico por imagen , Diafragma/efectos de los fármacos , Diafragma/inervación , Femenino , Volumen Espiratorio Forzado/efectos de los fármacos , Volumen Espiratorio Forzado/fisiología , Humanos , Masculino , Persona de Mediana Edad , Bloqueo Nervioso/efectos adversos , Oxígeno/sangre , Ápice del Flujo Espiratorio/efectos de los fármacos , Ápice del Flujo Espiratorio/fisiología , Nervio Frénico/efectos de los fármacos , Ventilación Pulmonar/efectos de los fármacos , Ventilación Pulmonar/fisiología , Radiografía , Respiración/efectos de los fármacos , Hombro , Espirometría , Capacidad Vital/efectos de los fármacos , Capacidad Vital/fisiologíaRESUMEN
Seventeen adult patients with moderate and stable bronchial asthma and established essential hypertension (WHO I or II) were evaluated in a randomized, double-blind, crossover study of the effects of captopril (50-100 mg/day) and verapamil (160-240 mg/day) on blood pressure, orthostatic reactions, respiratory function, and asthmatic symptoms. The effect of both drugs on blood pressure was significant. Blood pressure (mean of 161/98 mm Hg initially) decreased to a mean of 147/90 and 160/91 mm Hg on captopril and verapamil, respectively, with normal orthostatic changes. There were no significant differences in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), maximal expiratory flow at 50% of FVC (MEF50), or peak expiratory flow (PEF) measurements at the end of each treatment period. The subjective severity of asthma did not change significantly during the trial. No significant cough symptoms were reported on captopril.
Asunto(s)
Asma/tratamiento farmacológico , Presión Sanguínea/efectos de los fármacos , Captopril/uso terapéutico , Hipertensión/tratamiento farmacológico , Respiración/efectos de los fármacos , Verapamilo/uso terapéutico , Anciano , Asma/fisiopatología , Captopril/efectos adversos , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Hipertensión/fisiopatología , Masculino , Persona de Mediana Edad , Ápice del Flujo Espiratorio , Pruebas de Función Respiratoria , Verapamilo/efectos adversos , Capacidad VitalRESUMEN
Twenty six hypoxaemic patients with severe and stable chronic obstructive pulmonary disease (COPD) were treated with continuous domiciliary oxygen for a six month period. The patients were evaluated 1, 3 and 6 months after the start of oxygen therapy. In addition to blood gas analysis, 15 coping skills were evaluated by the patient and by the nurse, who also rated the general activity of the patients. Depression was measured by Beck Depression Inventory (BDI) at the start of the trial and after six months' oxygen therapy. The general psychosocial response was meagre; no significant changes were observed in any psychosocial measures. The response was slightly better in younger and less hypoxaemic patients. We conclude that the psychosocial response to oxygen therapy in severely hypoxaemic COPD patients is limited.
Asunto(s)
Adaptación Psicológica , Depresión/diagnóstico , Enfermedades Pulmonares Obstructivas/terapia , Terapia por Inhalación de Oxígeno/psicología , Femenino , Humanos , Hipoxia/terapia , Enfermedades Pulmonares Obstructivas/psicología , Masculino , Persona de Mediana Edad , Escalas de Valoración Psiquiátrica , Factores de TiempoRESUMEN
Oxitropium bromide is an anticholinergic bronchodilator. In a randomized, controlled, single-dose study with 12 asthmatics we compared 2 metered aerosol doses of salbutamol (200 micrograms and 400 micrograms) with oxitropium bromide (200 micrograms), and the combination of oxitropium bromide (200 micrograms) and salbutamol (200 micrograms). Salbutamol acted more rapidly than oxitropium. There were no differences between the two drugs at 360 min. The combination of both drugs produced a better response than the individual drugs alone, but salbutamol in a dose of 400 micrograms caused the best response throughout the whole follow-up.
Asunto(s)
Albuterol/administración & dosificación , Asma/tratamiento farmacológico , Derivados de Escopolamina/administración & dosificación , Adulto , Asma/fisiopatología , Ensayos Clínicos como Asunto , Quimioterapia Combinada , Femenino , Volumen Espiratorio Forzado , Humanos , Masculino , Flujo Espiratorio Máximo , Persona de Mediana Edad , Distribución AleatoriaRESUMEN
The effects of a 12-week oral treatment with tiapamil (200 mg t.i.d.) were compared to those of placebo treatment in a group of 20 men with coronary heart disease. There was a slight reduction of anginal symptoms (p less than 0.05) and a tendency to less nitroglycerin consumption (p less than 0.07). There were no statistically significant differences between the treatments in blood pressure, exercise tolerance during repeated exercise tests, ECG conduction intervals, or routine laboratory tests. No adverse side-effects were encountered. It seems that tiapamil may be beneficial in preventing angina pectoris, but a higher oral dose must be used.
Asunto(s)
Angina de Pecho/prevención & control , Bloqueadores de los Canales de Calcio/administración & dosificación , Propilaminas/administración & dosificación , Anciano , Bloqueadores de los Canales de Calcio/uso terapéutico , Enfermedad Coronaria/tratamiento farmacológico , Electrocardiografía , Prueba de Esfuerzo , Humanos , Cuidados a Largo Plazo , Masculino , Persona de Mediana Edad , Propilaminas/uso terapéutico , Clorhidrato de TiapamiloRESUMEN
The efficacy of fenoterol powder (Berotec, Boehringer-Ingelheim) was investigated in ten patients with moderate or severe asthma. Double-blind comparison to placebo powder showed a significant difference (p less than 0.05) between 30 to 180 min after a single dose of 0.2 mg. There was no difference between fenoterol powder and aerosol (0.2 mg). No adverse effects were encountered.
Asunto(s)
Asma/fisiopatología , Etanolaminas/farmacología , Fenoterol/farmacología , Respiración/efectos de los fármacos , Adulto , Aerosoles , Anciano , Asma/tratamiento farmacológico , Clorofluorocarburos de Metano , Femenino , Fenoterol/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , PolvosAsunto(s)
Obstrucción de las Vías Aéreas/tratamiento farmacológico , Derivados de Atropina/uso terapéutico , Etanolaminas/uso terapéutico , Fenoterol/uso terapéutico , Ipratropio/uso terapéutico , Tuberculosis Pulmonar/complicaciones , Adulto , Obstrucción de las Vías Aéreas/etiología , Evaluación de Medicamentos , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Single-blind, cross-over comparison of standard doses of ipratropium bromide (2 puffs of 0.02 mg each) and fenoterol (2 puffs of 0.2 mg each) in 36 pairs of experiments in 6 patients with partially reversible airway obstruction, presumably secondary to chronic widespread pulmonary tuberculosis, revealed no difference between the drugs in bronchodilating effect, evaluated by peak-flow measurements and spirometry. The inhalation of isoprenaline at the end of the experiment induced no further improvement in the lung function variables measured. The results suggest that a vagal reflex mechanism plays a major role in bronchoconstriction connected with severe chronic pulmonary tuberculosis.
Asunto(s)
Obstrucción de las Vías Aéreas/tratamiento farmacológico , Derivados de Atropina/uso terapéutico , Etanolaminas/uso terapéutico , Fenoterol/uso terapéutico , Ipratropio/uso terapéutico , Isoproterenol/uso terapéutico , Tuberculosis Pulmonar/complicaciones , Adulto , Aerosoles , Obstrucción de las Vías Aéreas/complicaciones , Enfermedad Crónica , Relación Dosis-Respuesta a Droga , Humanos , Masculino , Persona de Mediana Edad , Tuberculosis Pulmonar/fisiopatología , Nervio Vago/fisiologíaRESUMEN
The effect of 71 oxo-7-thiomethoxyxanthone-2-carboxylic acid sodium salt (RS 7540) in inhibiting exercise-induced asthma was compared with that of placebo in a double-blind crossover study. Single doses of 40 mg were given by inhalation to 12 patients. Ten of these subsequently received a dose of 20 mg. RS 7540 at both dose levels had a statistically significant effect in giving total or partial protection from exercise-induced bronchospasm; however, no dose relationship was apparent.
Asunto(s)
Asma/tratamiento farmacológico , Espasmo Bronquial/tratamiento farmacológico , Xantenos/uso terapéutico , Adulto , Presión Sanguínea , Espasmo Bronquial/etiología , Ensayos Clínicos como Asunto , Método Doble Ciego , Evaluación de Medicamentos , Femenino , Frecuencia Cardíaca , Humanos , Masculino , Persona de Mediana Edad , Ápice del Flujo Espiratorio , Esfuerzo Físico , Placebos , Terapia Respiratoria , Xantenos/administración & dosificaciónAsunto(s)
Determinación de la Presión Sanguínea/métodos , Pruebas de Función Cardíaca/métodos , Monitoreo Fisiológico/métodos , Pruebas de Función Respiratoria/métodos , Determinación de la Presión Sanguínea/instrumentación , Pruebas de Función Cardíaca/instrumentación , Humanos , Pruebas de Función Respiratoria/instrumentaciónRESUMEN
1.1. Diffusing capacity of the lungs was measured by using a Mark 4 Resparameter. The single-breath diffusing capacity (D) for carbon monoxide was found to be dependent on the lung volume (VA) during the breath-hold. The same applied to D/VA and to the time constant (tau) for carbon monoxide uptake. This confirms the theoretical considerations and the results of other investigators. This effect should be taken into account especially when making serial determinations of D on the same subject. 1.2. The repeatability of the method was found to be reasonably good; the coefficient of variation was about 4% in normal subjects, as well as in a series of patients with rheumatoid arthritis. 1.3. The effect of the correction for haemoglobin concentration was calculated and tabulated for a set of possible values of DM/Vc and haemoglobin. This correction did not reduce the scatter of D values in normal subjects, but it was adopted for clinical use for theoretical reasons. Caution in its use and interpretation of the correction is emphasized. 2.1. Healthy males and females, 20-69 years of age, were examined to establish reference values for the D measurement. Multiple linear regression equations were calculated stepwise, and equations based on age and height were then used in the clinical prediction equations. Similarly, prediction equations were calculated for clinical spirometry. 2.2. The prediction equations were compared with some published reference values. The equations provide a basis for the evaluation of the effect of various factors, such as age and smoking, in different populations. 3.1. Respiratory function, clinical symptoms and chest x-ray findings were examined in patients with connective tissue diseases. Three different investigations were thus formed: a) consecutive patients (free of lung disease other than that possibly due to a connective tissue disease) with definite rheumatoid arthritis (RA, 21 cases), systemic lupus erythematosus (SLE, 18 cases) or scleroderma (SCL, 6 cases) were subjected to detailed tests. b) 129 patients from the Rheumatism Foundation Hospital, Heinola, Finland, were subjected to measurement of diffusing capacity and vital capacity in addition to chest radiography and routine clinical assessment c) the histological findings on 12 patients subjected to a needle biopsy of the lung in order to exclude other conditions were compared with the results of diffusing capacity and x-ray examinations. 3.2. Restrictive impairment of the respiratory function was the general finding in all of these groups. The reduction in diffusing capacity was out of proportion to the reduction in lung volume, however, in most cases with abnormally low values. Low D values were encountered in about half of the RA and SLE and in all of the SCL patients in group a, and in 13% of the "average" RA patients studied in Heinola. The typical histological finding in patients with reduced D was a thickening of the alveolar wall...
Asunto(s)
Enfermedades del Colágeno/fisiopatología , Enfermedades Pulmonares/fisiopatología , Capacidad de Difusión Pulmonar , Adulto , Anciano , Artritis Reumatoide/fisiopatología , Biopsia con Aguja , Monóxido de Carbono/análisis , Enfermedades del Colágeno/etiología , Femenino , Hemoglobinas/análisis , Humanos , Pulmón/patología , Enfermedades Pulmonares/etiología , Mediciones del Volumen Pulmonar , Lupus Eritematoso Sistémico/diagnóstico por imagen , Lupus Eritematoso Sistémico/fisiopatología , Masculino , Persona de Mediana Edad , Radiografía , Pruebas de Función Respiratoria , Sarcoidosis/fisiopatología , Esclerodermia Sistémica/fisiopatología , Fumar , Tuberculosis Pulmonar/fisiopatología , Capacidad VitalRESUMEN
A double-blind cross-over comparison of a new beta2-sympathomimetic bronchodilator, clenbuterol, with salbutamol and placebo has been made during a 24 day period of out-patient treatment of 19 adults with moderately severe asthma. Oral clenbuterol (10 mug 3 times a day) and salbutamol (4 mg 3 times a day) were equally and significantly (p less than 0.001) more effective than placebo, when daily records of peak expiratory flow or use of isoprenaline inhalations were the criteria of activity. Daily records of symptoms according to a questionnaire also suggested relief of the subjective effects of asthma during treatment with both active drugs (p less than 0.01).