Abstract
Bronchodilators dilate the bronchi and increase lung volumes, thereby improving respiratory physiology in patients with chronic obstructive pulmonary disease (COPD). However, their effects on sevoflurane kinetics remain unknown. We aimed to determine whether inhaled salbutamol affected the wash-in and wash-out kinetics of sevoflurane and the occurrence of early postoperative pulmonary complications (PPCs) in patients with COPD undergoing elective surgery. This randomized, placebo-controlled study included 63 consecutive patients with COPD allocated to the salbutamol (n = 30) and control groups (n = 33). The salbutamol group received salbutamol aerosol (2 puffs of ~200 μg) 30 min before anesthesia induction and 30 min before surgery completion. The control group received a placebo. Sevoflurane kinetics were determined by collecting end-tidal samples from the first breaths at 1, 2, 3, 4, 5, 7, 10, and 15 min before the surgery (wash-in) and after closing the vaporizer (wash-out). PPCs were recorded for 7 days. The salbutamol group had higher end-tidal to inhaled sevoflurane ratios (p<0.05, p<0.01) than the control group, from 3 to 10 min during the wash-in period, but no significant differences were observed during the wash-out period. The arterial partial pressure of oxygen to the fraction of inhaled oxygen was significantly higher in the salbutamol group at 30 (320.3±17.6 vs. 291.5±29.6 mmHg; p = 0.033) and 60 min (327.8±32.3 vs. 309.2±30.5 mmHg; p = 0.003). The dead space to tidal volume ratios at 30 (20.5±6.4% vs. 26.3±6.0%, p = 0.042) and 60 min (19.6±5.1% vs. 24.8±5.5%, p = 0.007) and the incidence of bronchospasm (odds ratio [OR] 0.45, 95% confidence interval [CI] 0.23-0.67, p = 0.023) and respiratory infiltration (OR 0.52, 95% CI, 0.40-0.65, p = 0.017) were lower in the salbutamol group. In patients with COPD, salbutamol accelerates the wash-in rate of sevoflurane and decreases the occurrence of postoperative bronchospasm and pulmonary infiltration within the first 7 days.
Highlights
Chronic obstructive pulmonary disease (COPD), which comprises emphysema, chronic bronchitis, and small airway disease, is a chronic inflammatory condition in which the bronchioles are narrowed
COPD places a burden on medical systems due to the high incidence of postoperative pulmonary complications (PPCs) in these patients [5]
After a careful search of the literature on the internet, we found no similar study pertaining to the kinetics of sevoflurane in patients with COPD undergoing elective surgery
Summary
Chronic obstructive pulmonary disease (COPD), which comprises emphysema, chronic bronchitis, and small airway disease, is a chronic inflammatory condition in which the bronchioles are narrowed. COPD is characterized by a partially irreversible airflow limitation due to both chronic airway inflammation and decreased elastic recoil, which eventually leads to uneven air distribution and lung hyperinflation [1]. It poses a special anesthetic challenge in patients with specific pathophysiologic pulmonary changes. Volatile anesthetics are commonly used for inducing and maintaining anesthesia owing to their bronchodilating properties [2,3]. The depth of anesthesia may not reach the desired level at a given time due to gas trapping or dynamic hyperinflation upon induction or during surgery, which may delay recovery after surgery [4]. COPD places a burden on medical systems due to the high incidence of postoperative pulmonary complications (PPCs) in these patients [5]
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