Effects Of β₂ Agonist Salbutamol On The Uptake Of Sevoflurane And Bispectral Index Variations In Elderly Paients With Chronic Obstructive Pulmonary Disease

Partâ… Effects ofβ₂ agonist Salbutamol Aerosol on the Uptake of Sevoflurane in Elderly Patients with COPDObjective:To investigate the effects ofβ₂ agonist salbutamol aerosol on the uptake of sevoflurane in elderly patients with chronic obstructive pulmonary disease(COPD).Methods:A randomized,placebo-controlled and double-blinded trial with two groups (experiment and control group) was designed.With approval from the ethics committee in Zhong Shan Hospital,Shanghai,China,and with informed consents,26 patients were recruited to the trial and randomly allocated to salbutamol group(n= 13) or placebo group(n= 13).Eligible patients were elderly patients with ASA physical statusⅠ～Ⅱ,undergoing general surgery,with a body mass index(BMI) between 18 and 30 kg·m^-2,well-defined clinical diagnosis of COPD and with no evidence of malignant hyperthermia,cardiac dysfunction and renal insufficiency.All subjects were fasting for 10 hours and received no premedication.Routine monitoring (consists of a three-lead ECG,pulse oximetry,noninvasive blood pressure and expired gas analysis) was instituted and 16 G right internal jugular cannula were cannulated. Left radial artery was cannulated under local anesthesia to measure direct arterial blood pressure.And bispectral index(BIS) monitoring was initiated prior to induction. All subjects were received inhaled salbutamol aerosol 200μg according to manufacturers' recommendations and 500 mL Ringer's lactate solution 30 minutes before induction of anesthesia.Rapid sequence induction of anesthesia was fentanyl 3.0μg·kg^-1,followed by propofol 1.5～2.0 mg·kg^-1 and rocuronium 0.9 mg·kg^-1 was administered to facilitate endotracheal intubation.When the trachea was intubated, intermittent positive pressure ventilation(IPPV) was applied with tidal volume of 8～10 mL·kg^-1,respiratory rate 10～12 breaths per minute,inspiratory to expiratory time ratio of 1:2 to achieve pressure of end-tidal carbon dixoide(EtCO₂) 30～35 mmHg via a non-rebreathing circuit.After stable hemodynamics was maintained for 5 minutes,fresh gas flow was set to 2 L·min^-1 with 2%sevoflurane in admixture,then HR,invasive arterial blood pressure(IABP),S_PO₂,EtCO₂,BIS,minimum alveolar concentration(MAC),concentration of inhaled sevoflurane(F_I) and concentration of end-tidal(F_E) were recorded at 1,2,3,4,5,7,10,15 min.The Ppeak and Pplat were also measured in 1,5,10 min since the start of successful endotracheal intubation.We expose the two groups after completion of whole trial and analyzed significance among the related variables.Results:There were no statistical significance in height,age,body weight,BMI, baseline HR,baseline MAP,FEV₁,FVC and arterial blood-gas parameters between two groups.The value of HR and MAP reduced with the increasing MAC of sevoflurane over time in each group,while no statistical significant variations were observed in the values of HR and MAP between two groups in respective time point (P＞0.05).There were no statistical significance in inhaled anesthetic concentration captured by side stream sampling from Y port was higher between experiment group and control group,but the inhaled anesthetic concentration of sevoflurane increased steadily over time.In comparison with group placebo,the expired sevoflurane concentration markedly lower in 2 min[(0.382±0.170)%,P＜0.05],3 min [(0.512±0.204)%,P＜0.05],4 min[(0.653±0.224)%,P＜0.05],5 min [(0.806±0.198)%,P＜0.05]in experiment group.Peak airway pressure and mean airway pressure in experiment salbutamol were striking lowerer than control group (24.7±2.9 cmH₂O,20.1±2.7 cmH₂O,P＜0.05).The value of BIS was kept between 38 and 60 throughout the period in spite of increasing MAC over time,there were no differences between groups in each time point.Conclusion:The rate of alveolar concentration of sevoflurane was accelerated within 15 min in elderly patients with COPD after the administration of inhaled salbutamol aerosol(200μg) 30 minutes before the rapid-sequence induction of general anesthesia, its plausible mechanism may be that salbutamol nebulization partly ameliorated airway spasticity and attenuated airway resistance.While clinical significance was limited because its uptake was very short.Variations of BIS values failed to achieve an original wish since it was not sensitive for dose-response of inhaled anesthetics in the brain. Partâ…¡Effect of salbutamol aerosol on bispectral index value and arterial carbon dioxide in chronic obstructive pulmonary disease patients with typeâ…¡respiratory failureObjective:Aged patients with chronic obstructive pulmonary disease(COPD) in accompany with carbon dioxide(CO₂) accumulation usually occur cognition dysfunction.Up-to-date,it is poorly understood that the effect of salbutamol aerosol on bispectral index and arterial carbon dioxide in COPD patients with CO₂ accumulation.This article was focussed on investigating the effect of salbutamol aerosol on bispectral index(BIS) and pressure of arterial carbon dioxide(PaCO₂)) in elderly patients with COPD in accompany with chronic CO₂ accumulation.Methods:In this prospective,randomized controlled study,12 COPD patients with clinically well-identified typeâ…¡respiratory failure under bi-level positive airway pressure(BiPAP) ventilation in respiratory intensive care ward were recruited.The patients were randomly divided into experimental group(group E) and placebo group (group P).Heart rate(HR),mean arterial pressure(MAP),pulse oxygen saturation (SpO₂),BIS and parameters of arterial blood gas analysis(PaO₂,PaCO₂,pH) were recorded in 0 min and after inhaled salbutamol 15 min and 30 min respectively.At the same time,patients' mental state were assessed by the modified Observer's Assessment of Alertness/Sedation scale(OAA/S).Results:7 patients in group E and 5 patients in group P were included.In comparison with baseline value(100.5±9.48 mmHg) in group E,MAP slightly decreased in 15 min (94±9.42 mmHg,P＜0.01)and 30 min(92.43±12.73 mmHg,P＜0.05).In group P, MAP mildly dropped in 15 min(90±4.3 mmHg,P＜0.05) and 30 min(95.6±7.33 mmHg,P＜0.05).While there was no statistical significance between two groups about MAP and HR variability.PaCO₂ profoundly decreased in group E(72.14±17.3 mmHg,P＜0.01;67.14±15.4 mmHg,P＜0.05) and slightly decreased in group P (70.4±14.43 mmHg,P＜0.05;64.2±10.73 mmHg,P＜0.05).BIS value was slightly increased in two groups(group E:80.14±6.3,P＞0.05 81.14±9.24,P＞0.05;group P: 81.6±8.38,P＞0.05,82.8±7.98,P＞0.05) after the administration of inhaled salbutamol.The efficiency of non-invasive ventilation is increased after the doctor's guidance. Conclusion:The level of PaCO₂ lowered after the administration of inhaled salbutamol via ventilator metered dosage inhaler(MDI),and this effect is more obvious in 15 min than 30 min.Brief changes of PaCO₂ level may not result in significant altertions of BIS values in COPD patients with long-term CO₂ accumulation.