Gas exchange response to short-acting beta2-agonists in chronic obstructive pulmonary disease severe exacerbations.
BACKGROUND
Short-acting beta(2)-agonists are one of the mainstays of bronchodilator strategy for exacerbations of chronic obstructive pulmonary disease (COPD). The assessment of pulmonary gas exchange after salbutamol in COPD severe exacerbations remains unknown.


OBJECTIVE
We investigated whether the effects of nebulized salbutamol during COPD severe exacerbations are associated with further deterioration of pulmonary gas exchange.


METHODS
We examined patients with severe COPD when hospitalized for exacerbation (n = 9), and while in stable convalescence.


RESULTS
We assessed spirometry, arterial blood gases, systemic hemodynamics, and V/Q relationships 30 and 90 minutes after administration of 5.0 mg salbutamol. At exacerbation, compared with baseline, 30 minutes after salbutamol administration, cardiac output (Q) increased (from 6.5 +/- [SEM] 0.4 to 7.3 +/- 0.5 L . min(-1)) (p < 0.03) alone, without inducing changes in gas exchange indices. When in convalescence, compared with baseline, 30 minutes after salbutamol, there was an increase in Q (from 5.7 +/- 0.5 to 7.0 +/- 0.6 L . min(-1)) and Vo(2) (from 211 +/- 12 to 232 +/- 11 ml . min(-1)) (p < 0.002 each), whereas Pa(O(2)) decreased (from 71 +/- 4 to 63 +/- 3 mm Hg) and alveolar-arterial Po(2) difference increased due to increased perfusion of low-V/Q-ratio regions (from 4.5 +/- 2.6 to 9.6 +/- 4.1% of Q) (p < 0.05); Sa(O(2)) (93 +/- 2%) and Pa(CO(2)) (43 +/- 2 mm Hg) remained unchanged. This deleterious gas exchange response persisted at 90 minutes.


CONCLUSIONS
At exacerbation, salbutamol does not aggravate pulmonary gas exchange abnormalities. When in convalescence, however, baseline lung function improvement was associated with a detrimental gas exchange response to salbutamol, resulting in further V/Q imbalance and small decreases in Pa(O(2)) compounded by small increases in Q and Vo(2).
Polverino
Eva
E
Servei de Pneumologia (Institut del Tòrax), Hospital Clínic, Institut d'Investigacions Biomédiques August Pi i Sunyer, CIBER Enfermedades Respiratorias, Universitat de Barcelona, Barcelona, Spain.
Gómez
Federico P
FP
Manrique
Hernán
H
Soler
Néstor
N
Roca
Josep
J
Barberà
Joan Albert
JA
Rodríguez-Roisin
Roberto
R
D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D000368:Aged; D000420:Albuterol / Q000627:therapeutic use*; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D009330:Nebulizers and Vaporizers; D010101:Oxygen Consumption / Q000502:physiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000503:physiopathology; D011659:Pulmonary Gas Exchange / Q000187:drug effects* / Q000502:physiology; D012129:Respiratory Function Tests; D012146:Rest / Q000502:physiology; D012720:Severity of Illness Index; D016896:Treatment Outcome
D000318:Adrenergic beta-Agonists; D000420:Albuterol