Dilated choroidal veins and their role in recurrences of myopic macular neovascularisations.

AIM: To determine whether there is a correlation between the presence of macular dilated choroidal vein (DCV) and the recurrence of myopic macular neovascularisation (MNV) after antivascular endothelial growth factor (VEGF) treatment. METHODS: Medical records of 168 eyes of 163 patients with myopic MNV were reviewed for the presence of macular DCV and episodes of recurrences. A macular DCV was defined as a choroidal vein whose diameter was 2× larger than the adjacent veins coursing in the macular area of 5.5 mm diameter. RESULTS: Macular DCV existed in 47 (28%) of the eyes with myopic MNV. 70 eyes (41.7%) had recurrence during a mean follow-up period of 52.5±23.0 months. Recurrence was found in 28 of the 47 eyes (59.6%) with DCV, which was significantly more frequent than the 42 of the 121 eyes (34.7%) without DCV (p=0.003). Cox model analysis showed that macular DCV was an independent risk factor (HR: 2.0, 95% CI 1.1 to 3.5) for recurrence. The recurrence rate was significantly higher in eyes with DCV within the first 2 years after the onset than in eyes without DCV. CONCLUSIONS: Macular DCVs may be indicators of a more aggressive phenotype of eyes with myopic MNV. These eyes need careful monitoring after anti-VEGF therapies.

[Reliability of propofol target-controlled infusion in elderly patients].

BACKGROUND: Propofol target-controlled infusion (TCI) is now commonly used for the induction and maintenance of anesthesia. In this study, we measured the propofol plasma concentrations of elderly patients to evaluate our hypothesis that propofol TCI is reliable for use in elderly patients. METHODS: We measured plasma concentrations of propofol in 10 elderly patients undergoing elective general anesthesia. Propofol TCI was commenced at a target plasma concentration of 3 microg x ml(-1) using a TCI pump. The target concentration was kept at 3 microg x ml(-1) for 2-3 hours. Arterial blood samples were drawn for measurement of the propofol plasma-concentration analysis at 30, 60, 90, 120 and 180 minutes after the induction of anesthesia, and at the emergence from anesthesia. RESULTS: The measured plasma concentrations of propofol were not significantly different from the target plasma concentrations. The mean estimated and measured plasma concentrations at emergence were at about 1 microg x ml(-1), respectively. CONCLUSIONS: We concluded that propofol TCI is a reliable method for maintaining anesthesia even in elderly patients, whereas the individual differences of the elderly patients was greater than those obtained from normal patients.

[Reliability of propofol target-controlled infusion in obese patients].

BACKGROUND: Propofol target-controlled infusion (TCI) is now commonly used for induction and maintenance of anesthesia. In this study, we measured the propofol plasma concentrations in obese patients in order to test our hypothesis that propofol TCI is reliable for use in obese patients. METHODS: We measured plasma concentrations of propofol in 10 obese patients undergoing elective general anesthesia. Propofol TCI was commenced at a target plasma concentration of 4microg x ml(-1) using a TCI pump. The target concentration was kept at 4microg x ml(-1) for at least 3 hours. Arterial blood samples were drawn for measurement of the propofol plasma-concentration analysis at 30, 60, 90, 120 and 180 minutes after the induction of anesthesia, and at the emergence from anesthesia. RESULTS: The measured plasma concentrations of the drug were not significantly different from the target plasma concentrations and they showed no tendency to increase during the 3 hours of anesthesia. The measured plasma concentration at emergence was lower than the estimated value. CONCLUSIONS: We conclude that propofol TCI is a reliable method for maintaining anesthesia even in obese patients. At emergence, however, the data suggested that the plasma concentrations might be lower than the estimated values in obese patients.

[Evaluation of target-controlled infusion for propofol in patients with chronic renal failure undergoing living-related renal transplantation].

BACKGROUND: As we have no information whether target-controlled infusion (TCI) for propofol, using pharmacokinetic parameters obtained without chronic renal failure, is available to estimate the drug concentration, we examined the blood concentration of propofol on the patients with chronic renal failure to evaluate the reliability of TCI of propofol. METHODS: Ten patients with chronic renal failure undergoing hemodialysis, from 20 to 60 years of age, were scheduled for living-related renal transplantation. Propofol was administrated with our TCI system at the target blood concentration of 4 microg x ml(-1) for three hours. Blood samples were obtained at 30, 60, 90, 120, and 180 minutes after starting propofol delivery, and at the emergence from anesthesia to measure propofol concentration. RESULTS: There was no tendency of increasing the drug concentration in proportion to the time of propofol infusion. As for the concentration at emergence, mean estimated concentration of propofol was 1.6 mg x ml(-1), showing a good correlation between measured and estimated concentrations. CONCLUSION: TCI system for propofol provided a good estimation of the blood concentration of propofol in patients with chronic renal failure undergoing living-related renal transplantation.

[Simulation analysis of estimated effect-site concentrations of propofol and fentanyl administered by a TCI system for other drugs].

BACKGROUND: We experienced a case of inadequate sedation because of inappropriate use of TCI system for fentanyl. METHODS: We evaluated the blood and effect-site concentrations of propofol and fentanyl calculated by a pharmacokinetic simulation model in which the administration of one drug was managed with target-controlled infusion pump set for another drug. RESULTS: In case propofol was administered with an effect-site-steering TCI system for fentanyl, the blood concentration of propofol increased within the first few minutes, especially immediately after starting the infusion, decreased for the next 10 minutes, and then was stabilized at a level of 0.7 times the target concentration. When fentanyl was administered with a blood-steering TCI for propofol, the calculated blood concentration of fentanyl was almost equal to the target concentration in the first few minutes, and then gradually increased until reaching 2.21 times the target concentration, at 240 minutes. Furthermore, the propofol concentration and the fentanyl concentration showed small differences between the target and calculated concentrations when the infusion time was not so long. CONCLUSIONS: When the administration time is short, the anesthesiologist must be aware of the difficulty in distinguishing the human error of choosing one drug for the TCI system for another drug.

[Two cases of intraoperative awareness during intravenous anesthesia with propofol in morbidly obese patients].

We experienced two cases of intraoperative awareness during intravenous anesthesia with propofol and fentanyl in morbidly obese patients. The rates of propofol infusion were calculated according to the adjusted body weights, or reduced intentionally as obese patients are generally believed to require lower doses of propofol compared with non-obese patients. Our postoperative analysis by simulations using the anesthesia records showed that, when the simulation was based on real body weight, the blood/effect-site concentrations of propofol in both patients would have been below the necessary levels to keep the patients unconscious during the operation, but when the simulation was based on adjusted body weight, those concentrations might have been within the necessary range to maintain an adequate hypnotic level. We propose that the rate of propofol infusion should be the same in obese and non-obese patients and should be calculated according to the real body weight not to the adjusted body weight.