Abstract
ObjectivesTarget-controlled infusion (TCI) provides precise pharmacokinetic control of propofol concentration in the effect-site (Ce), eg. brain. This pilot study aims to evaluate the feasibility and optimal TCI regimen for flexible bronchoscopy (FB) sedation.MethodsAfter alfentanil bolus, initial induction Ce of propofol was targeted at 2 μg/ml. Patients were randomized into three titration groups (i.e., by 0.5, 0.2 and 0.1 μg/ml, respectively) to maintain stable sedation levels and vital signs. Adverse events, frequency of adjustments, drug doses, and induction and recovery times were recorded.ResultsThe study was closed early due to significantly severe hypoxemia events (oxyhemoglobin saturation <70%) in the group titrated at 0.5 μg/ml. Forty-nine, 49 and 46 patients were enrolled into the 3 respective groups before study closure. The proportion of patients with hypoxemia events differed significantly between groups (67.3 vs. 46.9 vs. 41.3%, p = 0.027). Hypotension events, induction and recovery time and propofol doses were not different. The Ce of induction differed significantly between groups (2.4±0.5 vs. 2.1±0.4 vs. 2.1±0.3 μg/ml, p = 0.005) and the Ce of procedures was higher at 0.5 μg/ml titration (2.4±0.5 vs. 2.1±0.4 vs. 2.2±0.3 μg/ml, p = 0.006). The adjustment frequency tended to be higher for titration at 0.1 μg/ml but was not statistically significant (2 (0∼6) vs. 3 (0∼6) vs. 3 (0∼11)). Subgroup analysis revealed 14% of all patients required no further adjustment during the whole sedation. Comparing patients requiring at least one adjustment with those who did not, they were observed to have a shorter induction time (87.6±34.9 vs. 226.9±147.9 sec, p<0.001), a smaller induction dose and Ce (32.5±4.1 vs. 56.8±22.7 mg, p<0.001; 1.76±0.17 vs. 2.28 ±0.41, p<0.001, respectively), and less hypoxemia and hypotension (15.8 vs.56.9%, p = 0.001; 0 vs. 24.1%, p = 0.008, respectively).ConclusionTitration at 0.5 μg/ml is risky for FB sedation. A subgroup of patients required no more TCI adjustment with fewer complications. Further studies are warranted to determine the optimal regimen of TCI for FB sedation.Trial RegistrationClinicalTrials.gov NCT01101477
Highlights
Propofol (2,6-diisopropylphenol) has been reported to be an ideal agent for flexible bronchoscopy (FB) sedation because of its fast effect and rapid recovery profile [1,2,3,4]
A steady-state sedation level could be maintained that is suitable for procedure sedation with a narrow therapeutic window, like fibreoptic intubation with spontaneous ventilation [12,13], gastrointestinal upper endoscopic ultrasound [14] and endoscopic retrograde cholangiopancreatography (ERCP) [15]
Some studies reveal fewer interventions on the infusion device in Target-controlled infusion (TCI) compared to manuallycontrolled infusion (MCI), making TCI easier to use [16]
Summary
Propofol (2,6-diisopropylphenol) has been reported to be an ideal agent for flexible bronchoscopy (FB) sedation because of its fast effect and rapid recovery profile [1,2,3,4]. Propofol titration is most often based on the physician’s discretion without fully taking into account the individual pharmacokinetic (PK) differences [1,2,3] This may result in unstable drug plasma concentrations, fluctuant sedative levels as well as increasing cardio-respiration suppression [6,7]. Target-controlled infusion (TCI), based on three-compartment models of propofol [8], could give precise PK control This computer-assisted infusion algorithm integrates individual variables and provides an infusion profile to achieve a steady plasma concentration [9,10] or ‘‘effect-site’’ concentration (Ce) [6,11], the theoretical drug concentration in the brain, and avoids unusual drug fluctuations. A study with a small number of patients has described the application of TCI in FB sedation for patients under noninvasive ventilation support in an intensive care unit [17]
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