Gas exchange at rest during simulated altitude in patients with chronica lung disease

Background. To characterize the gasometric and oximetric response to simulated altitudes of 3,100 m and sea level of patients with Chronic Obstructive Pulmonary Disease (COPD) and Interstitial Lung Disease (ILD) studied at 2,240 m above sea level. Methods. Consecutive stable patients with COPD and ILD were studied at the National Institute of Respiratory Diseases, a referral center for pulmonary diseases in Mexico City, and a healthy control group. The patients breathed room air (F1 O2 =0.21), for at least 15 min, then, a hypoxic mixture (F1 O2 =0.18, simulating 3,100 m), and finally, a hyperoxic mixture (F1 O2= 0.28, simulating sea level). Arterial blood gases and oxygen saturation were measured by a pulse oximeter at the end of each stage. Results. Twelve patients with COPD, 13 patients with ILD and 11 healthy controls were studied. The PaCO2 and pH were constant in the three study stages in both groups of patients and controls. A slope of PaO2 vs. altitude of 9 Torr per Km was found for each of the study's patients, either by simple linear regression or multiple regression, which is identical to that previously obtained at sea level with COPD patients (Gong et al.). Oxygen desaturation per Km of altitude change was alinear, higher for the hypoxic than for the hyperoxic challenge and more severe for the most hypoxic patients. Conclusions. Exposure test to simulated altitudes are safe, and orient the physician concerning the patient's condition at altitudes different from the place where the measurement is done. Alveolar ventilation remains constant despite hypoxia or hyperoxia during the challenges. A computer model of the lung reproduces many of the findings in the challenges of this study

Theophylline-ranitidine interaction in elderly COPD patients

Most controlled studies in humans indicate that ranitidine does not alter theophylline metabolism, even at high doses. However, there have been several case reports published recently which demostrate the development of theophylline toxicity mostly in older patients receiving stable oral doses of this drug when ranitidine was administered simultaneously. We studied eleven elderly (mean age, 69,0 + or - 6.2 years) patients with chronic obstructive pulmonary disease (COPD). During one week the patients took slow-release theophylline, 200 mg every 12 h, followed by one week intake of the same dose of theophylline plus ranitidine tables, 150 mg every 12h. At the end of each period, blood samples were obtained 0,1,2,3,4,6,7,8 and 12h after the morning dose for the determination of serum theophylline levels. the peak theophylline concentration was achieved after 4.1 + or - 0.9 h while the patients were taking theophylline, and after 2.9 + or - 1.4 h with the combined regimen. This difference was statistically significant. These results suggest that the reported increases in serum theophylline levels in older patients receiving theophylline and ranitidine cannot be ascribed to slower theophylline metabolism in the geriatric patient with COPD who is also given ranitidine.

Avaliaçäo da eficacia e tolerabilidade da bamifilina em pacientes portadores de doenca pulmonar obstrutiva cronica estavel / Efficacy and tolerability evaluation of bamiphylline in patients with stable chronic obstrutive pulmonary disease

A bamifilina e uma nova xantina de atividade similar a da teofilina,porem com uma faixa terapeutica mais ampla e uma maior capaciadde de difusao tecidual. Com o objetivo de avaliar a sua eficacia e tolerabilidade foram estudados 20 pacientes portadores de DPOC. Todos os pacientes apresentavam-se em situacao estavel a epoca do estudo. A resposta clinica e funcional foi analisada antes e apos a ingestao de 600mg de bamifilina de 12 em 12 horas. Apenas um paciente (5 por cento) apresentou efeito adverso,reacao urticariforme que obrigou a suspensao do medicamento. Onze (58 por cento) dos 19 pacientes restantes apresentaram uma resposta clinica favoravel. Os paramentros esperometricos mantiveram-se inalterados ao final dos 15 dias de estudo, fato esperado diante da condicao estavel dos pacientes. Estes resultados permitem concluir ser a bamifilina um droga eficaz e bel tolerada, devendo ser considerada como opcao terapeutica no alivio sintomatico de pacientes portadores de DPOC.