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Volume Loading (volume + loading)
Selected AbstractsPositive end-expiratory pressure optimization using electric impedance tomography in morbidly obese patients during laparoscopic gastric bypass surgeryACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2006K. Erlandsson Background:, Morbidly obese patients have an increased risk for peri-operative lung complications and develop a decrease in functional residual capacity (FRC). Electric impedance tomography (EIT) can be used for continuous, fast-response measurement of lung volume changes. This method was used to optimize positive end-expiratory pressure (PEEP) to maintain FRC. Methods:, Fifteen patients with a body mass index of 49 ± 8 kg/m2 were studied during anaesthesia for laparoscopic gastric bypass surgery. Before induction, 16 electrodes were placed around the thorax to monitor ventilation-induced impedance changes. Calibration of the electric impedance tomograph against lung volume changes was made by increasing the tidal volume in steps of 200 ml. PEEP was titrated stepwise to maintain a horizontal baseline of the EIT curve, corresponding to a stable FRC. Absolute FRC was measured with a nitrogen wash-out/wash-in technique. Cardiac output was measured with an oesophageal Doppler method. Volume expanders, 1 ± 0.5 l, were given to prevent PEEP-induced haemodynamic impairment. Results:, Impedance changes closely followed tidal volume changes (R2 > 0.95). The optimal PEEP level was 15 ± 1 cmH2O, and FRC at this PEEP level was 1706 ± 447 ml before and 2210 ± 540 ml after surgery (P < 0.01). The cardiac index increased significantly from 2.6 ± 0.5 before to 3.1 ± 0.8 l/min/m2 after surgery, and the alveolar dead space decreased. PaO2/FiO2, shunt and compliance remained unchanged. Conclusion:, EIT enables rapid assessment of lung volume changes in morbidly obese patients, and optimization of PEEP. High PEEP levels need to be used to maintain a normal FRC and to minimize shunt. Volume loading prevents circulatory depression in spite of a high PEEP level. [source] Fluid therapy in acute myocardial infarction: evaluation of predictors of volume responsivenessACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009J. SNYGG Background: Static vascular filling pressures suffer from poor predictive power in identifying the volume-responsive heart. The use of dynamic arterial pressure variables, including pulse pressure variation (PPV) has instead been suggested to guide volume therapy. The aim of the present study was to evaluate the performance of several clinically applicable haemodynamic parameters to predict volume responsiveness in a pig closed chest model of acute left ventricular myocardial infarction. Methods: Fifteen anaesthetized, mechanically ventilated pigs were studied following acute left myocardial infarction by temporary coronary occlusion. Animals were instrumented to monitor central venous (CVP) and pulmonary artery occlusion (PAOP) pressures and arterial systolic variations (SPV) and PPV. Cardiac output (CO) was measured using the pulmonary artery catheter and by using the PiCCO® monitor also giving stroke volume variation (SVV). Variations in the velocity time integral by pulsed-wave Doppler echocardiography were determined in the left (,VTILV) and right (,VTIRV) ventricular outflow tracts. Consecutive boluses of 4 ml/kg hydroxyethyl starch were administered and volume responsiveness was defined as a 10% increase in CO. Results: Receiver,operator characteristics (ROC) demonstrated the largest area under the curve for ,VTIRV [0.81 (0.70,0.93)] followed by PPV [0.76 (0.64,0.88)] [mean (and 95% CI)]. SPV, ,VTILV and SVV did not change significantly during volume loading. CVP and PAOP increased but did not demonstrate significant ROC. Conclusion: PPV may be used to predict the response to volume administration in the setting of acute left ventricular myocardial infarction. [source] Blood volume is normal after pre-operative overnight fastingACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2008M. JACOB Background: Pre-operative fasting is assumed to cause a deficit in intravascular blood volume (BV), as a result of ongoing urine production and insensible perspiration. Standard regimes consist of volume loading prior or simultaneous to any anaesthetic procedure to minimise the risk of hypotension. However, fluid overload in the context of major abdominal surgery has been shown to deteriorate patient outcome. Our study aimed to quantify total intravascular BV after fasting by direct measurements and to compare it with calculated normal values in comparable non-fasted patients. Methods: After 10 h of fasting, total plasma volume (PV) and red cell volume (RCV) were measured via the double-label technique (indocyanine green dilution and erythrocytes labelled with fluorescein, respectively) following induction of general anaesthesia in 53 gynaecological patients suffering from malignoma of the cervix. The corresponding normal values were calculated individually from age, body height and body weight. Results: Measured BV, RCV and PV after fasting were 4123±589, 1244±196 and 2879±496 ml, respectively. The differences to the corresponding calculated normal values were not significant (3882±366, 1474±134 and 2413±232 ml, respectively). The measured haematocrit reflected a slight anaemic state (0.35±0.03). Conclusion: Our data suggest that even after prolonged pre-operative fasting, cardio-pulmonary healthy patients remain intravascularly normovolaemic. Therefore, hypotension associated with induction of general or neuraxial anaesthesia should perhaps be treated with moderate doses of vasopressors rather than with undifferentiated volume loading. [source] Transvenous Embolization of Small Patent Ductus Arteriosus with Single Detachable Coils in DogsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2001Matthias Schneider Transvenous embolization of small patent ductus arteriosus (PDA; , 4 mm) with a single detachable coil was attempted in 24 dogs (median age 5.7 months, range, 2.6,65.5 months; median body weight 5.5 kg, range, 1.5,30.0 kg). Angiographic imaging of the duct and pressure measurements were made before and after embolization. The minimal ductal diameter was 2.7 ± 0.7 mm. In all dogs, a single coil was employed regardless of residual shunting. Ten dogs (PDA minimal diameter range, 1.5-2.2 mm) received a 5-mm coil, and 14 dogs (PDA minimal diameter range, 2.9-3.6 mm) received a 8-mm coil. After coil embolization the angiographic shunt grade decreased significantly (n = 20, P < .001). Residual shunts were assessed by angiography 15 minutes after and by Doppler echocardiography 1,3 days and 3 months after the intervention. In the dogs treated with the 5-mm coils the residual shunt rate was low (0%, 10%, and 0% for angiography and Doppler echocardiography at 1,3 days and 3 months, respectively), in contrast to the dogs treated with the 8-mm coils (91%, 79%, and 67% for angiography and Doppler echocardiography at 1,3 days and 3 months, respectively). After 3 months, no residual murmur was found in dogs treated with the 5-mm coils (0/7), in contrast to murmurs in 5 of 12 (42%) dogs treated with the 8-mm coils. Despite incomplete closure in these dogs, volume loading of the left heart decreased in all dogs. Pulmonic or aortic coil embolism did not occur. Analysis of initial results shows that single detachable coil embolization is possible in all dogs with a small PDA (, 4 mm), but only very small PDA (s 2.5) could be treated effectively, and for the moderate PDA (2.6-4.0 mm) longer coils or multiple coils may be necessary to achieve complete occlusion. [source] A practice survey on vasopressor and inotropic drug therapy in Scandinavian intensive care unitsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2003A. Oldner Background: This practice survey was performed to analyse the indications for use of vasopressor/inotropic drugs, preferred drugs and doses as well as concomitant monitoring and desired haemodynamic target values in Scandinavian ICUs. An internet-based reporting system was implemented. Methods: A total of 223 ICUs were identified in the Scandinavian countries and invited to participate in a one-day point-prevalence study. An internet-based database was constructed and a practice survey protocol designed to identify haemodynamic monitoring, indications for vasopressor/inotropic drug-therapy, fluids used for volume loading, pretreatment circulatory state, actual and targeted haemodynamic variables. Patients were eligible for the study if on vasopressor/inotropic drug-therapy for more than 4 h. Results: A total of 114 ICUs participated. A total of 114 adult patients matched the inclusion criteria. Sixty-seven per cent of the patients had received vasopressor/inotropic drug-treatment for >24 h and 32% received more than one drug. Arterial hypotension (92%) and oliguria (50%) were most common indications. Fluid loading prior to therapy was reported in 87% of patients. Dopamine (47%) and noradrenaline (44%) were the most commonly used drugs followed by dobutamine (24%). No other drug exceeded 6%. Non-catecholamine drugs were rarely used even in cardiac failure patients. Invasive arterial pressure was monitored in 95% of patients, pulmonary artery catheters were used in 19%. Other cardiac output monitoring techniques were used in 8.5% of the patients. Conclusion: Dopamine and noradrenaline seem to be the most commonly used inotropic/vasopressor drugs in Scandinavia. Traditional indications for inotropic/vasopressor support as hypotension and oliguria seem to be most common. Invasive monitoring was used in almost all patients, whereas a limited use of pulmonary artery catheters was noted. The internet-based reporting system proved to be an efficient tool for data collection. [source] Interpretation of radial pulse contour during fentanyl/nitrous oxide anesthesia and mechanical ventilationACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2002S. Söderström Background: Peripheral arterial blood pressure is not a reliable substitute for proximal aortic pressure. Recognition of this phenomenon is important for correct appreciation of cardiac afterload. Our aim was to evaluate the utility of the radial pulse wave to better understand ventriculo-vascular coupling during anesthesia. Methods: We observed the differences between aortic systolic pressure (AoSAP, tipmanometry) and radial systolic pressure in 15 patients, (including two women) aged 53,78 years, before coronary artery bypass surgery. We studied the induction of anesthesia with fentanyl (20 µg kg,1), moderate volume loading, and thereafter the addition of 70% nitrous oxide. The circulatory effects of mechanical ventilation were studied by doubling the tidal volumes. Pulse wave contours were assessed by calculation of radical and aortic augmentation indices (AI), which measure the second systolic pressure peak. Results: Radial systolic pressure was higher than AoSAP in the control situation (8±2 mmHg), and this SAP gradient increased further with fentanyl (12±2 mmHg). The gradient persisted throughout the study, but was partially reduced by volume loading and nitrous oxide, respectively. Radial augmentation index was the only parameter remaining in a stepwise multivariate model to explain the variance in the SAP gradient (r2=0.48). Radial augmentation index also correlated with aortic pulse pressure (r2=0.71). Mechanical ventilation had significant and similar effects on pulse wave augmentation both in the aorta and in the radial artery, and did not affect the radial to aortic SAP gradient. Conclusion: These elderly coronary patients had stiff vasculature (high aortic AI) and considerable pulse wave reflection, which was beneficially delayed by fentanyl. Changes in the radial pulse wave augmentation during mechanical ventilation were mainly a result of cyclic changes in the stroke volume, and were seldom associated with an increased systolic pressure gradient from the aorta to the radial artery. [source] | ||||||||||