Place of retarded oral morphine in the treatment of severe pulmonary emphysema of the "pink puffer" type - a pilot study

Background and objective: In severe "pink puffer" emphysema the patients' p hysical capacity is limited by dyspnoea despite maximal application of esta blished treatment. This pilot study investigated the effect of retarded mor phine, taken orally for 10 days, on ventilation, dyspnoea, walking capacity and wakefulness. Patients and methods: Twenty clinically stable patients (11 men, 9 women, m ean age 68.5 [50-81] years) with,"pink puffer" emphysema were studied over a period of 10 days in a prospective, non-controlled trial of cross-over de sign. Criteria for inclusion in the study were: 1-second forced expiratory volume (FEV1) < 1 I, vital capacity < 50% and normocapnia. In addition to t heir existing therapy patients received either no further therapy or retard ed morphine. Morphine dosage was increased to maximally 3 x 30 mg daily, de pending on effectiveness and side effects, dyspnoea at rest and immediately after a 6-min walk (assessed with Borg's visual analog scale), maximal wal king capacity were determined, as well as blood gases, respiratory minute v olume and the respiratory drive (airway occlusion pressure [P 0.1]), respon siveness of the respiratory pathways to CO2 and wakefulness (concentration, fatigue, interest in surroundings). Results: Twelve patients completed the study (group A). In the remaining pa tients (group B) the test had to be stopped prematurely because of undesira ble side effects or an exacerbation of the underlying infection. In group A , morphine (mean dosage: 49.2 +/- 28.4 mg/d) caused a reduction of PaO2, dy spnoea on activity, the resting minute respiratory volume, respiratory driv e and CO2 response, and an increase in PaCO2, HCO3-and the 6-min walking di stance. Morphine did not produce a change in subjectively evaluated vigilan ce and the blood pH. Conclusion: After strict patient selection oral morphine produced a reducti on of exercise dyspnoea and an increase in walking capacity in half of the patients with severe pulmonary emphysema. There also occurred a slight rise in PaCO2 without any relevant respiratory acidosis or significant decrease in wakefulness.