Dransfield and colleagues1 advocate the use of β blockers even in patients admitted with acute exacerbations of chronic obstructive pulmonary disease (COPD), but certain points need further discussion.

Their retrospective analysis highlights the discordance in practice that exists between cardiologist and pulmonologist. Indeed, the former is keen to commence β blockers in patients with a wide range of cardiovascular diseases for cardioprotection, while the latter is cautious in protecting patients with obstructive airway disease from bronchoconstriction.

Historically, the use of β adrenergic blockers in patients with obstructive airways disease has been discouraged. There are currently no prospective long term data on the safety of β blockers in COPD and, moreover, β blockers are contraindicated in asthma. It is not always easy to differentiate between asthma and COPD, especially when inhaled therapy for both conditions is very similar.

Regarding the use of β blockers in patients with obstructive airways disease, the advice in the British National Formulary2 reads as follows: β blockers may precipitate bronchospasm and this effect can be dangerous. β Blockers should be avoided in patients with a history of COPD or asthma, if there is no alternative, a cardioselective β blocker may be used with extreme caution under specialist supervision.

Even a prospective study3 has suggested that non-selective β blockers are detrimental in patients with COPD. For instance, propranolol has been shown to worsen lung function and desensitise the airway to the bronchodilating effects of long acting β₂ agonists, while metoprolol, which has been advocated by the authors to be safe in COPD because of its cardioselectivity, significantly increased the extent of bronchial hyperresponsiveness. Until data from long term studies that specifically address these safety issues are available, the jury must still be out in deciding whether any β blockers are safe in COPD.