RESUMO
Background: Nitric oxide (NO) is considered a means of detecting airway hyperresponsiveness, since even non-asthmatic patients experiencing bronchospasm intraoperatively or postoperatively display higher levels of exhaled NO. It can also be used as a non-invasive biomarker of lung inflammation and injury. This prospective, single-blind, randomized study aimed to evaluate the impact of two different anesthesia maintenance techniques on fractional exhaled nitric oxide (FeΝO) in patients without respiratory disease undergoing total thyroidectomy under general anesthesia. Methods: Sixty patients without respiratory disease, atopy or known allergies undergoing total thyroidectomy were randomly allocated to receive either inhalational anesthesia maintenance with sevoflurane at a concentration that maintained Bispectral Index (BIS) values between 40 and 50 intraoperatively or intravenous anesthesia maintenance with propofol 1% targeting the same BIS values. FeΝO was measured immediately preoperatively (baseline), postoperatively in the Postanesthesia Care Unit and at 24 h post-extubation with a portable device. Other variables measured were eosinophil blood count preoperatively and postoperatively and respiratory parameters intraoperatively. Results: Patients in both groups presented lower than baseline values of FeΝO measurements postoperatively, which returned to baseline measurements at 24 h post-extubation. In the peripheral blood, a decrease in the percentage of eosinophils was demonstrated, which was significant only in the propofol group. Respiratory lung mechanics were better maintained in the propofol group as compared to the sevoflurane group. None of the patients suffered intraoperative bronchospasm. Conclusions: Both propofol and sevoflurane lead to the temporary inhibition of NO exhalation. They also seem to attenuate systemic hypersensitivity response by reducing the eosinophil count in the peripheral blood, with propofol displaying a more pronounced effect and ensuring a more favorable mechanical ventilation profile as compared to sevoflurane. The attenuation of NO exhalation by both agents may be one of the underlying mechanisms in the reduction in airway hyperreactivity. The clinical significance of this fluctuation remains to be studied in patients with respiratory disease.
RESUMO
BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) has been associated with major perioperative morbidities or mortalities, especially in surgical patients receiving general anesthesia. The severity of the COPD and the degree of bronchial hyperreactivity can determine the perioperative anesthetic risk; therefore they have to be assessed by a thorough preoperative evaluation in order to give the rationale on which to decide for optimum anesthetic management. OBJECTIVE: Aim of the study was to assess the predictive applicability of exhaled Nitric Oxide (NO) in smoking surgical population with COPD, on the basis of morbidity and mortality. METHODS: A prospective, observational study was undertaken in 70 smoking patients diagnosed with COPD scheduled for laparotomy surgery under general anesthesia COPD was evaluated with the GOLD Classification of Air Flow Limitation, the Modified MRC Dyspnoea Scale (mMRC), the BODE Index score and the 6 Minutes Walk Distance (6MWD) using spirometry parameters. All patients were observed for presenting perioperative and postoperative respiratory complications. A cut off value of 19 ppb was determined for fractional exhaled nitric oxide measured at expiratory flow of 50 mL/s (FENO50) to differentiate patients poor prognosis from those with favorable outcome. RESULTS: Patients with severe COPD had high BODE index score as well as FENO50. Elevated FENO50 is significantly related to multiple complications (p = 0.004) and postoperative cough (p < 0.001). Patients from the high FENO50 group that were not treated with steroids had a statistically significant higher incidence of extra hospital care need (p < 0.001). Increased FENO50 and ABCD classification are both related with the presentation of multiple complications (Odds ratio = 2.5, 95% CI 1.1 to 5.7, p = 0.028 for ABCD and Odds ratio = 6.39, 95% CI 1.33 to 30.5, p = 0.020 for FENO50). Increased FENO50 and ABCD are related with extra hospital care (p = 0.001 and p = 0.002 respectively) and combined with corticosteroid administration could predict the necessity for extra hospital care (Odds ratio 4.09, 95% CI 1.1 to 15.3, p = 0.036 for corticosteroid treatment, odds ratio 2.4, 95% CI 1.1 to 5.1, p = 0.029 for ABCD and odds ratio 7.93, 95% CI 1.7 to 35.3, p = 0.007 for FENO50). CONCLUSION: The FENO50 may identify high risk smoking surgical patients with COPD receiving general anesthesia. Perioperative and postoperative complications in COPD smoking patients undergoing abdominal surgery can be predicted using not only ABCD GOLD 2011 classification but also the FENO50 as a preoperative marker.
