The accuracy and clinical feasibility of a new bayesian-based closed-loop control system for propofol administration using the bispectral index as a controlled variable.

BACKGROUND: Closed-loop control of the hypnotic component of anesthesia has been proposed in an attempt to optimize drug delivery. Here, we introduce a newly developed Bayesian-based, patient-individualized, model-based, adaptive control method for bispectral index (BIS) guided propofol infusion into clinical practice and compare its accuracy and clinical feasibility under direct observation of an anesthesiologist versus BIS guided, effect compartment controlled propofol administration titrated by the anesthesiologist during ambulatory gynecological procedures. METHODS: Forty ASA patients were randomly allocated to the closed-loop or manual control group. All patients received midazolam 1 mg IV and alfentanil 0.5 mg IV before induction. In the closed-loop control group, propofol was administered using the previously described closed-loop control system to reach and maintain a target BIS of 50. In the manual control group, the propofol effect-site concentration was adapted at the discretion of the anesthesiologist to reach and maintain a BIS as close as possible to 50. Induction characteristics, performance, and robustness during maintenance and recovery times were compared. Hemodynamic and respiratory stability were calculated as clinical feasibility parameters. RESULTS: The closed-loop control system titrated propofol administration accurately resulting in BIS values close to the set point. The closed-loop control system was able to induce the patients within clinically accepted time limits and with less overshoot than the manual control group. Automated control resulted in beneficial recovery times. Our closed-loop control group showed similar acceptable clinical performance specified by similar hemodynamic, respiratory stability, comparable movement rates, and quality scores than the manual control group. CONCLUSIONS: The Bayesian-based closed-loop control system for propofol administration using the BIS as a controlled variable performed accurate during anesthesia for ambulatory gynecological procedures. This control system is clinical feasibility and can be further validated in clinical practice.

Contralateral replacement of pacemaker and leads following laser sheath extraction and concomitant stenting for superior vena cava syndrome.

We present the case of a 61-year-old man with a history of pacemaker implantation 15 years ago. The patient was admitted with chronic swelling of the right hemithorax and inflammation of the old incision scar after the replacement of pacemaker generator 6 years ago. The patient also presented symptoms and clinical signs of superior vena cava syndrome. Computed tomography of the thorax showed obstruction of the superior vena cava. The surgical procedure consisted of extraction of infected pacemaker system with excimer laser technique followed by dilatation and stenting of the SVC and finally implantation of a new permanent pacemaker system on the left side.

Assessment of renal function in recently admitted critically ill patients with normal serum creatinine.

BACKGROUND: Detection of renal dysfunction is important in critically ill patients, and in daily practice, serum creatinine is used most often. Other tools allowing the evaluation of renal function are the Cockcroft-Gault and MDRD (Modification of Diet in Renal Disease) equations. These parameters may, however, not be optimal for critically ill patients. The present study evaluated the value of a single serum creatinine measurement, within normal limits, and three commonly used prediction equations for assessment of glomerular function (Cockcroft-Gault, MDRD and the simplified MDRD formula), compared with creatinine clearance (Ccr) measured on a 1 h urine collection in an intensive care unit (ICU) population. METHODS: This was a prospective observational study. A total of 28 adult patients with a serum creatinine <1.5 mg/dl, within the first week of ICU admission, were included in the study. Renal function was assessed with serum creatinine, timed 1 h urinary Ccr, and the Cockcroft-Gault, MDRD and simplified MDRD equations. RESULTS: Serum creatinine was in the normal range in all patients. Despite this, measured urinary Ccr was <80 ml/min/1.73 m2 in 13 patients (46.4%), and <60 ml/min/1.73 m2 in seven patients (25%). Urinary creatinine levels were low, especially in patients with low Ccr, suggesting a depressed production of creatinine caused by pronounced muscle loss. Regression analysis and Bland-Altman plots revealed that neither the Cockcroft-Gault formula nor the MDRD equations were specific enough for assessment of renal function. CONCLUSIONS: In recently admitted critically ill patients with normal serum creatinine, serum creatinine had a low sensitivity for detection of renal dysfunction. Furthermore, the Cockcroft-Gault and MDRD equations were not adequate in assessing renal function.