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In order to maintain stable blood pressure and heart rate during surgery, anesthesiologists need to administer the appropriate amount of fluid with appropriate fluid type to the patient, then quantifying how fluid is distributed and eliminated from the body is useful for establishing a fluid administration strategy. In this study we characterized the volume kinetics of Ringer’s lactate solution in patients undergoing open gastrectomy. When propofol and remifentanil reached a pseudosteady state at the target concentration and blood pressure was stabilized following surgical stimulation, enrolled patients were administered 1000 mL of Ringer’s lactate solution for 20 min, followed by continuous infusion at a rate of 6 mL/kg/h until the time of the last blood collection for volume kinetic analysis. Arterial blood samples were collected to measure the hemoglobin concentration at different time points. The change in hemoglobin-derived plasma dilution induced by the administration of Ringer’s lactate solution was evaluated by nonlinear mixed effects modeling. Three hundred and twenty-three plasma dilution data points from 27 patients were used to determine the pharmacokinetic characteristics of Ringer’s lactate solution. A two-volume model best described the pharmacokinetics of Ringer’s lactate solution. The mean arterial pressure (MAP) and body weight (WT) were significant covariates for the elimination clearance (k(r)) and central volume of distribution at baseline (V(c0)), respectively. The parameter estimates were as follows: k(r) (mL/min) = 124 + (MAP/70)(14.2), V(c0) (mL) = 0.95 + 3440 × (WT/63), V(t0) (mL) = 2730, and k(t) (mL/min) = 181. A higher MAP was associated with a greater elimination clearance and, consequently, less water accumulation in the interstitium. As body weight increases, volume expansion in the blood vessels increases.

SummaryAim Regional cerebral oxygen saturation (rSO2) is currently the most used measure in clinical practice to monitor cerebral ischemia in patients undergoing carotid endarterectomy (CEA). Although end-tidal carbon dioxide (PETCO2) is known as a factor that influences rSO2, the relationship between PETCO2 and rSO2 has not been quantitatively evaluated in patients with severe arteriosclerosis. This study aimed to evaluate the effect of PETCO2 on rSO2 in patients undergoing CEA under general anaesthesia. Methods The intervention to change PETCO2 was conducted between skin incision and clamping of the carotid artery. The rSO2 values were observed by changing PETCO2 in the range of 25-45 mmHg. The PETCO2–rSO2 relationship was characterized by population analysis using a turnover model. Results In total, 1,651 rSO2 data points from 30 patients were used to determine the pharmacodynamic characteristics. Hypertension (HTN) and systolic blood pressure (SBP) were significant covariates on the slope factor in the stimulatory effect of PETCO2 on rSO2 and fractional turnover rate constant (kout), respectively. The estimates of the parameters were kout(min-1): 3.59 for SBP < 90 mmHg and 0.491 for SBP ≥ 90 mmHg, slope: 0.00321 for patients with HTN and 0.00664 for patients without HTN. Conclusion The presence of hypertension attenuates the response of rSO2 after a change in PETCO2. When cerebral blood flow is in a state of decline caused by a decrease in SBP to less than 90 mmHg, the response of rSO2 to PETCO2 is increased. It is advisable to maintain SBP above 90 mmHg in patients with hypertension during CEA.

AIMS Avoiding propofol in patients with Brugada syndrome has been suggested because of the theoretical risk of provoking ventricular arrhythmias, although propofol may be selected for conscious sedation during electrophysiological procedures in catheterization laboratories. This study aimed to document periprocedural electrocardiographic changes and adverse events in patients with Brugada syndrome undergoing implantable cardioverter defibrillator (ICD) implantation using propofol sedation. METHODS We reviewed the clinical data of 53 consecutive patients who underwent ICD implantation during 1998-2011. Sedation was achieved by combining propofol with either midazolam or fentanyl, and a bolus propofol dose (0.5-1 mg/kg) was administered to induce deep sedation. Periprocedural events, including arrhythmias, defibrillations, and hyperthermia episodes, were evaluated, and electrocardiogram (ECG) variables were measured. The need for emergency anesthetic support/intubation and incidence of perioperative complications or mortality were analyzed. RESULTS Procedure time and cumulative propofol dose for each patient was 125.2 (42.8) min and 204.6 (212.7) mg, respectively. During deep sedation, blood pressure, heart rate, and oxygen saturation were significantly decreased (P