Same efficacies of ipratropium and salbutamol in reversing methacholine-induced bronchoconstriction

Increased asymptomatic airway hyper-responsiveness in obese individuals

OBJECTIVE

Asymptomatic airway hyper-responsiveness (AHR) represents a risk of further accelerated decline in lung function, and of asthma. Due to the fact that rare and contradictory results exist concerning the impact of obesity on BHR, we re-assessed the prevalence of bronchial hyper-responsiveness (BHR) in a large cohort of 60 lean, 84 overweight, and 360 class 1-3 obese non-asthmatic individuals, by coupled plethysmography and spirometry.

METHODS

Baseline-specific airway conductance (SGaw) and spirometric values were measured and then a methacholine challenge testing (MCT) was performed and considered as positive when a ≥200% increase in specific airway resistance (SRaw = 1/SGaw) was reached.

RESULTS

Compared to lean and overweight subjects, obese subjects of any class presented about a twice more frequent AHR (∼ 50% in obese vs. 17 and 26% in lean and overweight subjects, respectively). However, the bronchial sensitivity (methacholine dose doubling SRaw) and the shape of the relationship between SGaw and cumulative methacholine doses were the same in the five groups of individuals.

CONCLUSION

The present data show a more frequent AHR in obese subjects. The association of plethysmography with spirometry, by taking into account the bronchodilator effect of the lung inflation (preceding the expiratory flow measurement) in some individuals, permitted to include some MCT which would have been otherwise excluded.

Efficacy of anticholinergic drugs in asthma

Although bronchial hyperresponsiveness to cholinergic agents is a main feature of asthma, the role of anticholinergic drugs in chronic asthma management has been largely underestimated. Several single-dose studies comparing acute bronchodilation induced by ipratropium bromide with salbutamol have shown that salbutamol was more effective than ipratropium in asthma treatment. Recently, tiotropium has been studied in asthma, when added to low-dose inhaled corticosteroids in unselected moderate asthmatics or in patients with uncontrolled asthma, or patients with chronic obstructive pulmonary disease and history of asthma. Later, studies on patients with Arg/Arg β(2)-receptor polymorphism demonstrated a similar efficacy of tiotropium in comparison with salmeterol when both were added to low-dose inhaled corticosteroids. Further long-term studies are currently in progress, for the evaluation of the efficacy of tiotropium on clinical asthma control, and on the rate and severity of asthma exacerbations, as well as the potential modification of inflammatory mechanisms and varying efficacy in specific asthma phenotypes (such as smoking asthmatics).

Bronchospasm after intravenous lidocaine

IV lidocaine (1.5 mg/kg) administered to facilitate endotracheal intubation was associated with transient bronchospasm in a 17-month-old-female with mild intermittent asthma. Immediately after lidocaine administration, the patient developed diffuse bilateral expiratory wheezes and dramatic increases in peak inspiratory pressure. Over approximately 5 min the episode resolved and an uneventful anesthetic course followed. This is consistent with recent clinical studies suggesting that IV lidocaine may cause airway narrowing in asthmatics. Practitioners should be aware of this potential complication.