[Postoperative respiratory therapy: bronchospasmolytic activity and side-effects of some recently introduced...

Intensive respiratory therapy is essential for reducing postoperative morbidity and mortality in older persons with pre-existing chronic obstructive pulmonary diseases. A new series of beta-adrenergic agents is being frequently used to effect bronchodilatation. Three substances from this group, viz.: reproterol (Bronchospasmin), terbutalin (Bricanyl) and fenoterol (Berotec) were examined in a randomized study in 90 patients. All three substances produced a significant increase in FEV1 and PEFR of up to 10.6 and 15.7 per cent respectively above the initial values. There were no significant differences between the three groups. Contrary to the results obtained by other investigators PaO2 fell in all groups. In the case of fenoterol this decrease was statistically significant with a mean value of 0.36 kPa. The causes for this fall in arterial oxygen pressure are still unknown. It may possible be due to an increased intrapulmonary right-left shunt as a result of increased cardiac output together with a ventilation-perfusion mismatch despite improved airways resistance. Since drastic falls by as much as 2.53 kPa have been observed during treatment with these agents they constitute a potential risk.