Influence of thiopental, etomidate, and propofol on regional myocardial function in the normal and acute ischemic heart segment in dogs

The effects of 30-min infusions of thiopental (20, 30, 40, 50, 60, and 70 mg.kg-1.h-1), etomidate (2.4, 3.6, 7.2, 9.6, 12, and 14.4 mg.kg-1.h-1), and propofol (6, 9, 12, 15, 18, and 21 mg.kg-1.h-1) on regional hemodynamic variables in the normal and acute ischemic heart segment were studied in dogs using ultrasonic segment length gauges. The three agents were associated with a dose-dependent decrease in end-diastolic length, indicating a decrease in left ventricular filling. This effect was most pronounced for propofol. At the doses tested, etomidate did not significantly alter regional myocardial function. Thiopental, however, was associated with a dose-dependent decrease in systolic shortening, which was significantly greater in the ischemic segment. These findings confirm the hemodynamic stability seen with etomidate and show that thiopental depresses myocardial function more in the acute ischemic heart than in the normal heart. The decrease in systolic shortening associated with propofol was similar in the normal and in the acute ischemic heart segmen

Myocardial metabolism during anaesthesia with propofol--low dose fentanyl for coronary artery bypass surgery

We have studied the haemodynamic and myocardial effects of propofol-fentanyl anaesthesia in 12 patients undergoing coronary artery bypass surgery during the pre-bypass period. The induction dose of propofol was 1.5 mg kg-1 and mean infusion rate during maintenance was 4.48 mg kg-1 h-1 (range 1.87-7.24 mg kg-1 h-1). The total dose of fentanyl was 30 micrograms kg-1. The haemodynamic changes indicated myocardial depression and peripheral vasodilatation. Coronary sinus flow and indicators of global myocardial perfusion (myocardial oxygen consumption, myocardial lactate extraction) did not change. Although not excluding regional myocardial ischaemia, these results show that propofol-fentanyl anaesthesia has no major adverse effects on cardiac functio

Simulating Trial Trenches for Archaeological Prospection: Assessing the Variability in Intersection Rates

In this study we draw attention to the inherent variability in the results of trial trenching, when taking into account the countless variations in orientation and positioning of trenches. Grids of trial trenches were simulated time and again on the excavation plans of 16 archaeological sites from Flanders, Belgium. Orientation and positioning of the grid layout was shifted randomly, whilst the area coverage varied from 2.5% to 80%. The intersection rates of the archaeological features allow to gain more insight in trends and variability that are inherent to the chosen design of trial trenches. It is assessed how robust a chosen grid layout performs on (multi-period) archaeological sites and how variable these results might be. The most effective layout appears to be a grid with short, parallel and discontinuous trenches or a standard grid, closely followed by 2m wide continuous trenches. Implementing 4m wide trenches reduces the effectiveness of the latter method substantially. When the area coverage of the trenches is below 10%, the results of the archaeological prospection become unreliable and can potentially lead to a substantial over-or underestimation of the actual feature density on the site

Oxygen transport and myocardial function after the administration of albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% to rabbits

BACKGROUND AND OBJECTIVE: The effects of administering albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% on oxygen transport and left ventricular function were prospectively investigated in different experimental conditions: baseline, fluid load, after 10 min of myocardial ischaemia and after reperfusion. METHODS: Twenty-seven rabbits received at random one of three colloids in escalating boluses over 10-15 min to achieve left ventricular end-diastolic pressures (LVEDP) between 8 and 10mmHg. A branch of the left anterior descending coronary artery was then temporarily occluded by a ligature and released after 10 min. Myocardial function was assessed using left ventricular pressure recordings and dimension data obtained from ultrasound crystals inserted onto the ventricular wall. Blood was sampled for the determination of oxygen delivery and consumption, the oxygen extraction ratio, acid-base status, and glucose and lactate concentrations. RESULTS: Administration of the colloids similarly increased oxygen delivery and improved left ventricular function in all groups. Peak rate of pressure development (dP/dt(max)) and oxygen delivery were reduced during ischaemia and reperfusion. The decrease in dP/dt(max) was more pronounced in the hydroxyethylstarch group. CONCLUSIONS: Administration of albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% had similar effects on oxygen delivery and myocardial function. After ischaemia and during reperfusion, the decrease in myocardial function was most pronounced with hydroxyethylstarch 6

Simulation von Suchschnitten in der archäologischen Prospektion: Berwertung der Variabilität im Anteil von geschnittenen Befunden

Simulating trial trenches for archaeological prospec- tion: assessing the variability in intersection rates. In this study we draw attention to the inherent variability in the results of trial trenching, when taking into account the countless variations in orientation and positioning of trenches. Grids of trial trenches were simulated time and again on the excavation plans of 16 archaeological sites from Flanders, Belgium. Orientation and positioning of the grid layout was shifted randomly, whilst the area cov- erage varied from 2,5 % to 80 %. The intersection rates of the archaeological features allow to gain more insight in trends and variability that are inherent to the chosen design of trial trenches. It is assessed how robust a cho- sen grid layout performs on (multi-period) archaeological sites and how variable these results might be. The most effective layout appears to be a grid with short, parallel and discontinuous trenches or a standard grid, closely followed by 2m wide continuous trenches. Implement- ing 4m wide trenches reduces the effectiveness of the lat- ter method substantially. When the area coverage of the trenches is below 10 %, the results of the archaeological prospection become unreliable and can potentially lead to a substantial over- or underestimation of the actual feature density on the site

The effects of the pericardium on length-dependent regulation of left ventricular function in coronary artery surgery patients

OBJECTIVE: To analyze the effects of the pericardium on the length-dependent regulation of myocardial function in coronary artery surgery patients. DESIGN: Prospective. SETTING: University hospital. PARTICIPANTS: Patients scheduled for elective coronary artery surgery. INTERVENTIONS: In 10 patients, a combined micromanometer transducer conductance catheter was inserted into the left ventricle for measurement of left ventricular pressures and volumes. MEASUREMENTS AND MAIN RESULTS: Consecutive data were obtained during a progressive increase in left ventricular pressures and volumes obtained by leg elevation in closed chest-closed pericardium and open chest-open pericardium conditions. Pericardiotomy did not alter baseline left ventricular hemodynamics. The effects of leg elevation were different, however. In closed chest-closed pericardium conditions, stroke volume and stroke work remained unchanged, whereas these parameters increased in open chest-open pericardium conditions. This increase was related to the increase in end-diastolic volume that was observed in open chest-open pericardium conditions and not in closed chest-closed pericardium conditions. CONCLUSIONS: In coronary artery surgery patients, pericardiotomy does not alter baseline left ventricular function. When cardiac load is increased by leg elevation, however, use of the Frank-Starling mechanism is enhanced in open chest-open pericardium condition