Stroke output variations calculated by esophageal Doppler is a reliable predictor of fluid response

Objective Esophageal Doppler allows continuous monitoring of stroke volume index (SVI) and corrected flow time (FTc). We hypothesized that variations in stroke output index SOI (SVI/FTc) during volume expansion can predict the hemodynamic response to subsequent fluid loading better than the static values.Design and setting Prospective study in the intensive care unit of a university hospital.Patients Fifty-one patients with circulatory failure were monitored by esophageal Doppler.Interventions Patients who responded to a first fluid challenge received a second one. Patients who responded to both were classified as responders-responders, and those who did not respond to the second as responders-nonresponders. In these two groups we compared SVI, FTc, and SOI during each fluid challenge and also static values at the end of each fluid challenge.Measurements and results After the first fluid challenge SOI and SVI were significantly higher in patients who responded to subsequent volume expansion than in patients who no longer responded. ROC curves showed that SOI was a better predictor of fluid responsiveness than SVI. During volume expansion a SOI value of 11% discriminated between responders and nonresponders to subsequent volume expansion with a sensitivity of 91% and a specificity of 97%. There was no significant difference between the two groups for FTc value at the end of first fluid challenge.Conclusions Analysis of SOI during fluid challenge predicts response to subsequent fluid challenge and FTc is not a reliable indicator of cardiac preload.     

Effects of the heat-moisture exchangers on dynamic hyperinflation of mechanically ventilated COPD patients

In recent years the use of devices called Heat and Moisture Exchangers (HME) has become widespread as gas conditioners for ICU patients requiring mechanical ventilation. As an important variation of the resistive properties of the HME, related to flow and duration of use, has recently been pointed out during in vitro studies, the use of these devices in COPD patients could increase the levels of auto PEEP and dynamic hyperinflation. In this study we have compared the levels of auto PEEP and difference in functional residual capacity ( FRC) in a group of COPD patients, requiring controlled mechanical ventilation (CMV), at basal conditions and after the insertion into the circuit of three HMEs (Dar Hygrobac, Pall Ultipor, Engstrom Edith) at random: the results obtained excluded a significant increase of auto PEEP and (FRC) both with new HMEs and after 12 h of continuous use.     

Increased oxygen consumption after cardiac surgery is associated with the inflammatory response to endotoxemia

Objective The aim of this study was to determine whether the increase in post-operative oxygen consumption (VO₂) in cardiac surgery patients in related to endotoxemia and subsequent cytokine release and whether VO₂ can be used as a parameter of post-perfusion syndrome.Design Prospective study.Setting Operating room and intensive care unit of a university hospital.Patients Twenty-one consecutive male patients undergoing elective coronary artery bypass surgery without major organ dysfunction and not receiving corticosteroids.Measurements and results Plasma levels of endotoxin, tumor necrosis factor (TNF) and interleukin-6 (IL-6) were measured before, during and for 18 h after cardiac surgery. Oxygen consumption, haemodynamics, the use of IV fluids and dopamine, body temperature and the time of extubation were also measured. Measurements from patients with high VO₂ (median value of the entire group) were compared with measurements from patients with low VO₂ (2 had higher levels of circulating endotoxin (P=0.004), TNF (P=0.04) and IL-6 (P=0.009) received more IV fluids and dopamine while in the ICU, and were extubated later than patients with low VO₂. Several hours after VO₂ the patient's body temperature rose, Forward stepwise regression analysis showed that circulating endotoxin and TNF explained 50% of the variability of VO₂.Conclusions This study demonstrates that patients with high post operative oxygen comsumption after elective cardiac surgery have higher circulating levels of endotoxin, TNF and IL-6 and also have more symptoms of post-perfusion syndrome. Early detection of high VO₂ might be used as a clinical signal to improve circulation in order to meet the high oxygen demand of inflammation. In addition, continuous measurement of VO₂ provides us with a clinical parameter of inflammation in interventional studies aiming at a reduction of endotoxemia or circulating cytokines.Part of this study was supported financially by Jaussen Pharmaceutica B.V. (Tilburg, The Netherlands)     

Transthoracic electrical impedance during extracorporeal hemodialysis in acute respiratory failure (“Shocked lung syndrome”)

The alteration (Z ₀ ) of transthoracic electrical impedance (TEI) during extracorporeal hemodialysis (EHD) was investigated in two Groups of patients with acute renal and acute respiratory failure, that differed with respect to the severity of respiratory insufficiency. Group I had moderate respiratory failure (Fi _{O 2} 0.31±0.10, Pa _{0 2} 84±14 mmHg), and Group II had severe respiratory failure (Fi _{0 2} 0.75±0.17, Pa _{O O} 77±14 mmHg). There was a significant correlation between increase in TEI (Z₀) and decrease in body weight (BW) in each individual patient, but the slope of regression lines was remarkably flattened in Group II. In Group I, TEI was 1.9±0.9 , the calculated TEI for 500 gr decrease in BW (Z_{0–500 gr}) was 0.59±0.21 , and a significant correlation existed between pooled data of Z₀ and BW. In Group II TEI increased less significantly, TEI was 0.6±0.3 (P<0.001), Z_{0–500 gr} was 0.26±0.27 (P<0.01), and there was no correlation between pooled data of Z₀ and BW. Increase of TEI in Group II could be completely attributed to increase in hematocrit. It is concluded that patients of Group I with acute renal failure and moderate respiratory failure lost intrathoracic fluid during EHD, whereas patients of Group II with severe respiratory failure did not. TEI during EHD may serve as a test for detection of fixed fluid within the pulmonary interstitium indicating a poor prognosis of the acute respiratory failure.     

New aspects of pulmonary mechanics: ‘slowly” distensible compartments of the respiratory system,identified by a PEEP step maneuver

Objective The aims of the present study were 1) to evaluate a method for identification of slowly distensible compartments of the respiratory system (rs), which are characterized by long mechanical time constants (RC) and 2) to identify slowly distensible rs-compartments in mechanically ventilated patients.Design Prospective studyon a physical lung model.Setting Intensive Care Unit, University Hospital, Tübingen.Patients and participants 19 patients with severe lung injury (acute respiratory distress syndrome, ARDS) and on 10 patients with mild lung injury.Measurements and results Positive end-expiratory pressure (PEEP)-increasing and-decreasing steps of about 5 cmH₂O were applied and the breath-by-breath differences of inspiratory and expiratory volumes (V) were measured. The sequence of Vs were analyzed in terms of volume change in the fast compartment (V_fast), the slow compartment (V_slow), total change in lung volume (VL) and mechanical time constant of the slow compartment (RC_slow). Thirty-eight measurements in a lung model revealed a good correlation between the preset V_slow/VL and V_slow/VL measured: r²=0.91 The V_slow/VL measured amounted to 0.94±0.15 of V_slow/VL in the lung model. RC_slow measured was 0.92±0.43 of the RC_slow reference. Starting from a PEEP level of 11 cmH₂O PEEP-increasing and PEEP-decreasing steps were applied to the mechanically ventilated patients. Three out of ten patients with mild lung injury (30%) and 7/19 patients with ARDS (36.8%) revealed slowly distensible rscompartments in a PEEP-increasing step, whereas 15/19 ARDS patients and 1/10 patients with mild lung injury showed slowly distensible rs-compartments in a PEEP-decreasing step (78.9% vs 10%,P<0.002, chi-square test).Conclusions The gas distribution properties of the respiratory system can be easily studied by a PEEP-step maneuver. The relative contribution of the slow units to the total increase of lung volume following a PEEP step could be adequately assessed. Slowly distensible rs-compartments could be detected in patients with severe and mild lung injury, however significantly more ARDS patients revealed slow rs-compartments in PEEP-decreasing steps. The influence of slowly distensible rs-compartments on pulmonary gas exchange is unknown and has yet to be studied.The work was performed at the Klinik für Anaesthesiologie und Transfusionsmedizin der Universität Tübingen     

Pulse pressure variations to predict fluid responsiveness: influence of tidal volume

Objective To evaluate the influence of tidal volume on the capacity of pulse pressure variation (PP) to predict fluid responsiveness.Design Prospective interventional study.Setting A 31-bed university hospital medico-surgical ICU.Patients and participants Sixty mechanically ventilated critically ill patients requiring fluid challenge, separated according to their tidal volume.Intervention Fluid challenge with either 1,000 ml crystalloids or 500 ml colloids.Measurements and results Complete hemodynamic measurements including PP were obtained before and after fluid challenge. Tidal volume was lower than 7 ml/kg in 26 patients, between 7–8 ml/kg in 9 patients, and greater than 8 ml/kg in 27 patients. ROC curve analysis was used to evaluate the predictive value of PP at different tidal volume thresholds, and 8 ml/kg best identified different behaviors. Overall, the cardiac index increased from 2.66 (2.00–3.47) to 3.04 (2.44–3.96) l/min m² ( P <0.001). It increased by more than 15% in 33 patients (fluid responders). Pulmonary artery occluded pressure was lower and PP higher in responders than in non-responders, but fluid responsiveness was better predicted with PP (ROC curve area 0.76±0.06) than with pulmonary artery occluded pressure (0.71±0.07) and right atrial (0.56±0.08) pressures. Despite similar response to fluid challenge in low (<8 ml/kg) and high tidal volume groups, the percent of correct classification of a 12% PP was 51% in the low tidal volume group and 88% in the high tidal volume group.Conclusions PP is a reliable predictor of fluid responsiveness in mechanically ventilated patients only when tidal volume is at least 8 ml/kg.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Intrathoracic blood volume accurately reflects circulatory volume status in critically ill patients with mechanical ventilation

Positive pressure ventilation in patients with acute respiratory failure (ARF) may render the interpretation of central venous pressure (CVP) or pulmonary wedge pressure (PCWP) difficult as indicators of circulating volume. The preload component of cardiac (CI) and stroke index (SI) is also influenced by the increased intrathoracic pressures of positive pressure ventilation. Moreover CI and SI do not indicate volume status exclusively but also contractility and afterload. We investigated whether intrathoracic blood volume (ITBV) more accurately reflects blood volume status and the resulting oxygen transport (DO₂). CVP, PCWP, cardiac (CI) and stroke index (SI) were measured, oxygen transport index (DO₂I) and oxygen consumption index (VO₂I) were calculated in 21 ARF-patients. Ventilatory patterns were adjusted as necessary. CI, SI and intrathoracic blood volume index (ITBVI) were derived from thermal dye dilution curves which were detected with a 5 F fiberoptic thermistor femoral artery catheter and fed into a thermaldye-computer. All data were collected in intervals of 6h. There were 224 data sets obtained. Linear regression analysis was performed between absolute values as well as between the 6 h changes (prefix ). The following correlation coefficients were determined: CVP/CI and PCWP/CI 0.01 and –0.142 (p<0.05); CVP/SI and PCWP/SI –0.108 and –0.228 (p<0.01); ITBVI/CI and ITBV/SI 0.488 (p<0.01) and 0.480 (p<0.01); ITBVI and DO₂I 0.460 (p<0.01); CVP/CI and PCWP/CI –0.069 and–0.018; CVP/SI and PCWP/SI –0.083 and –0.009; ITBVI/CI and ITBVI/SI 0.715 (p<0.01) and 0.646 (p<0.01); ITBVI and DO₂I 0.707 (p<0.01). We conclude that in mechanically ventilated patients ITBV is a suitable indicator of circulating blood volume.     

Self-efficacy expectancies versus outcome expectancies as determinants of performance deficits and depressive affect

To compare the depression etiologies specified by self-efficacy theory versus the revised learned helplessness theory, 108 male and female undergraduates were assigned randomly to either high, low, or no self response expectancy manipulations and high, low, or no response outcome expectancy manipulations. Expectancies were modified by combinations of easy or difficult anagrams and graphs showing that most or few students solved the anagrams. Males exhibited performance deficits and depressed affect following manipulations only if self response expectancy had been set low and other response expectancy had been set high. Contrary to revised learned helplessness theory, no performance deficit or depressive affect occurred when both self response and response outcome expectancies were low. Females' performance and affect were not changed by combined low self response and high response outcome manipulations. Repeated subject ratings of self response and response outcome expectancies during manipulations suggest that females set their self response expectancies low before manipulations to avoid depression. Expectancy ratings also showed that self response expectancies correlated more strongly with performance than did response outcome expectancies.We thank Katherine Acosta, Michael Davis, Larry McFarland, and Janine Tronolone for their assistance as experimenters.     

Left ventricular function after acute myocardial infarction

10 patients with their first AMI were studied within the first 48 hours and again after 3 weeks. Central and peripheral haemodynamics (CI, SV, SW, TPR) were examined, including indices of contractility (dp/dlmax) and wall stiffness (P/V, relation P/V to P) of the left ventricle.In the early phase CI and SW, as well as LV dp/dt_max were depressed in accordance with symptoms of LV failure. P/V was increased. Elevation of LVEDP correlated well with ventricular gallop rhythm, but less consistently with LV functional disturbance.During convalescence CI increased uniformly, both in digitalized and non-digitalized individuals. In contrast heart rate, aortic pressure, LVEDP and dp/dt_max remained unchanged. The increase of CI, SV and SW was accompanied by a fall of TPR and P/V. LV wall stiffness was still elevatedabove normal after 3 weeks. The improvement of cardiac pumping during infarct convalescence may have been effected through a fall of TPR and LV wall stiffness. Recovery of depressed contractile performance was generally not observed, and does therefore not seem to contribute to recuperation.Herrn Prof. Dr. med. P. Schölmerich zum 60. Geburtstag.     

Monitoring of respiratory variations of aortic blood flow velocity using esophageal Doppler

Objective The purpose of this study was to determine whether monitoring of respiratory changes in aortic blood flow velocity, recorded by esophageal Doppler, could be used to detect changes in volume depletion.Design Animal study.Animals and interventions After general anesthesia and tracheotomy, ten New Zealand female rabbits, weighing 4–4.5 kg were studied under mechanical ventilation at a fixed tidal volume; during this time 5-ml blood samples were withdrawn (in increments up to a total of 30 ml) and then retransfused.Measurements and results At each step, systolic (SBP), diastolic (DBP), pulse (PP) pressures and maximum descending aortic blood flow (V) were recorded. Respiratory changes of V (V), SBP (SBP) and PP (PP) were calculated as the difference of maximal and minimal values divided by their respective means and expressed as a percentage. The amount of blood withdrawn correlated negatively with SBP, DBP, PP and V and positively with SBP, PP and V. Among these parameters, V correlated best with the amount of blood withdrawn (r=0.89, p<0.001) and it was the most accurate index of volume depletion.Conclusion Monitoring of the respiratory variation in V, calculated by esophageal Doppler technique, seems to be a highly accurate index of blood volume depletion and restitution.Supported by Philips Medical System and Arrow.     

Volume/pressure curve of total respiratory system in paralysed patients: artefacts and correction factors

The volume/pressure (V/P) curve of the total respiratory system in paralysed patients is drawn assuming that volume changes of the respiratory system (V resp) equals volume displacement of the measuring apparatus (V syr), usually a supersyringe. However, in 93 VP curves we found that O₂ removed from the lung-syringe system during the procedure (proportional to the time) largely exceedes the CO₂ added to the lung-syringe system (V gas). This results in a net loss of volume from the system (V resp相似文献   

Transbronchial regional electroplethysmography of the lungs

Objective. The objective of this study was to describe a method of transbronchial regional electroplethysmography of the lungs.Methods. The electrical resistance of a division of a lung, such as a segment or subsegment, as well as its pulsatile oscillation, were measured using a two-part process: A catheter-transducer was wedged into a small bronchus and the electrical resistance of a blood sample obtained from the same patient was measured. The electroplethysmograph (EPG) was developed for this purpose. The theory behind our method is based on a model of the lung as a three-component structure (blood-tissue-air). We performed experiments on isolated lung lobes of animals, using simultaneous electrometric and direct determination of physiologic indices for regional lung function.Results. Equations have been proposed to calculate blood volume, V_b (±10%); air volume, V_a (±11%); pulsatile increment of the blood volume, V (±10%); and regional stroke volume, RSV (±20%) per 100 cm³ of the lung. The proposed formulas yield an accuracy that is adequate for the clinical range of variations in V_b and V_a, as well as V and RSV. Experiments on lung lobes indicate that the conductivity of lung tissue (_t) is not large. This allows one to calculate the above indices without our having obtained accurate values for conductivity.Conclusions. The method of Transbronchial regional electroplethysmography of the lungs is described and cases in which this method was used for clinical investigation are presented.Glossary Resistivity of suspension - ₁ Resistivity of conducting medium - ₂ Resistivity of conducting spheres - Electroconductivity of the lung at diastole - ₁ Electroconductivity of the lung at systole - _b Electroconductivity of blood - _t Electroconductivity of tissue - _bt Electroconductivity of conducting medium (blood+tissue) - Pulsatile electroconductivity increment in the lung - _e Electrical equivalent of regional stroke volume - V Volume of lung - V_B Blood volume of lung - V_T Tissue volume of lung - V_A Air volume of lung - V_b Regional blood volume per lung volume unit - V_a Regional air volume per lung volume unit - V Regional pulsatile blood increment in the lungs - Ratio of the conducting medium (blood+tissue) volume to the lung volume unit - Ratio of the blood volume to the volume unit of the conducting medium - R Electrical resistance - R Electrical resistance increment - RSV Regional stroke volume per the organ volume unit - F Form-factor - l Cell length - S Cell cross-section area - K Empirical correction coefficient - K₁ Coefficient of electrode installation     

The effect of lateral positions on gas exchange in patients with unilateral lung disease during mechanical ventilation

Positional changes have long been known to have a gravitational effect on the distribution of pulmonary blood flow. The effects of body position, supine, right and left lateral decubitus, on gas exchange were evaluated in 10 patients with predominantly unilateral lung disease. All patients were treated with mechanical ventilation and PEEP. Arterial blood gases, measured after 15 min in each of the three positions, showed that lying on the side of the normal lung resulted in a higher arterial pO₂ (mean: 144 mmHg) than lying on that of the damaged lung (mean: 86 mmHg). The AapO₂ values were 334 to 391 mmHg. Both differences were statistically significant (P<0.005). No significant changes in mean arterial carbon dioxide tensions were noted.     

Comparative Carbon Dioxide Output Through Injured and Noninjured Peritoneum During Laparoscopic Procedures

Tension pneumoperitoneum may force gas into a small injured vessel if the opening is kept patent by surrounding tissues. However, the amount of carbon dioxide (CO₂) that penetrates through injured or noninjured peritoneum has not been systematically determined. In 25 patients undergoing elective laparoscopic ultrasonography and cholecystectomy, CO₂ output (VCO₂) and O₂ uptake (VO₂) were measured at baseline and during anesthesia, pneumoperitoneum, laparoscopic surgical procedure (Surgery), and after hemostasis of the surgical field (Postsurgery). Before anesthesia,V CO₂/BSA andV O₂/BSA were 97.7 ± 11.3 and 116.0 ± 10.0 mlmin^-1m^-2, respectively. During anesthesia, they fell to 72.3 ± 6.0 and 89.8 ± 7.6 mlmin^-1m^-2 (p < 0.05). VCO₂/BSA increased to 96.0 ± 11.1 at pneumoperitoneum (p < 0.05) and increased further to 126.1 ± 11.0 mlmin^-1m^-2 at Surgery. It fell to 111.7 ± 10.9 mlmin^{-1m -2} Postsurgery. VO₂/BSA remained unchanged during pneumoperitoneum. Minute volume increased from 2.24 ± 0.20 in anesthesia to 2.89 ± 0.25, 4.01 ± 0.32, and 3.46 ± 0.28 Lmin^-1m^-2 during pneumoperitoneum, Surgery, and Postsurgery, respectively, to maintain PaCO₂. We conclude that the amount of CO₂ absorbed following pneumoperitoneum prior to surgery is lower than that during Surgery or Postsurgery. The amount of CO₂ absorbed through the surgical field was 2.3 times higher than that through the nonsurgical field, while that from the peritoneum after hemostasis of surgical field was 1.6 times higher.     

The respiratory variation in inferior vena cava diameter as a guide to fluid therapy

Objective To investigate whether the respiratory variation in inferior vena cava diameter (D_IVC) could be related to fluid responsiveness in mechanically ventilated patients.Design Prospective clinical study.Setting Medical ICU of a non-university hospital.Patients Mechanically ventilated patients with septic shock (n=39).Interventions Volume loading with 8 mL/kg of 6% hydroxyethylstarch over 20 min.Measurements and results Cardiac output and D_IVC were assessed by echography before and immediately after the standardized volume load. Volume loading induced an increase in cardiac output from 5.7±2.0 to 6.4±1.9 L/min (P<0.001) and a decrease in D_IVC from 13.8±13.6 vs 5.2±5.8% (P<0.001). Sixteen patients responded to volume loading by an increase in cardiac output 15% (responders). Before volume loading, the D_IVC was greater in responders than in non-responders (25±15 vs 6±4%, P<0.001), closely correlated with the increase in cardiac output (r=0.82, P<0.001), and a 12% D_IVC cut-off value allowed identification of responders with positive and negative predictive values of 93% and 92%, respectively.Conclusion Analysis of D_IVC is a simple and non-invasive method to detect fluid responsiveness in mechanically ventilated patients with septic shock.     

Alveolar pressure during high-frequency jet ventilation

We studied the influence of ventilatory frequency (1–5 Hz), tidal volume, lung volume and body position on the end-expiratory alveolar-to-tracheal pressure difference during high-frequency jet ventilation (HFJV) in Yorkshire piglets. The animals were anesthetized and paralysed. Alveolar pressure was estimated with the clamp off method, which was performed by a computer controlled ventilator and which had been extensively tested on its feasibility. The alveolar-to-tracheal pressure difference increased with increasing frequency and with increasing tidal volume, the common determinant appearing to be the mean expiratory flow. The effects in prone and in supine position were similar. Increasing thoracic volume decreased the alveolar-to-tracheal pressure difference indicating a dependence of this pressure difference on airway resistance. We concluded that the main factors determining the alveolar-to-tracheal pressure difference (P) during HFJV are expiratory flow (V_E) and airway resistance (R), PV_E×R.     

Pattern of lung emptying and expiratory resistance in mechanically ventilated patients with chronic obstructive pulmonary disease

Objectives To study the pattern of lung emptying and expiratory resistance in mechanically ventilated patients with chronic obstructive pulmonary disease (COPD).Design A prospective physiological study.Setting A 12-bed Intensive Care Unit.Patients Ten patients with acute exacerbation of COPD.Interventions At three levels of positive end-expiratory pressure (PEEP, 0, 5 and 10 cmH₂O) tracheal (Ptr) and airway pressures, flow (V) and volume (V) were continuously recorded during volume control ventilation and airway occlusions at different time of expiration.Measurements and results V-V curves during passive expiration were obtained, expired volume was divided into five equal volume slices and the time constant () and dynamic deflation compliance (Crs_dyn) of each slice was calculated by regression analysis of V-V and post-occlusion V-Ptr relationships, respectively. In each volume slice the existence or not of flow limitation was examined by comparing V-V curves with and without decreasing Ptr. For a given slice total expiratory resistance was calculated as /Crs_dyn, whereas expiratory resistance (Rrs) and time constant (_rs) of the respiratory system were subsequently estimated taken into consideration the presence of flow limitation. At zero PEEP, _rs increased significantly toward the end of expiration due to an increase in Rrs. PEEP significantly decreased Rrs at the end of expiration and resulted in a faster and relatively constant rate of lung emptying.Conclusions Patients with COPD exhibit a decrease in the rate of lung emptying toward the end of expiration due to an increase in Rrs. PEEP decreases Rrs, resulting in a faster and uniform rate of lung emptying.Electronic Supplementary Material Supplementary material is available in the online version of this article at An erratum to this article can be found at     

Optimizing outcomes with antimicrobial therapy through pharmacodynamic profiling

In patients with infection, improving the probability of positive treatment outcomes depends on optimizing the interactions between the host, pathogen, and drug. In this setting, optimal regimens must be utilized which not only maximize effectiveness in a specific patient, but also minimize the development of microbial resistance. The probability of achieving a specifically targeted antimicrobial exposure can be assessed using Monte Carlo simulation, a technique which integrates an agents in vitro potency distribution (i.e., minimum inhibitory concentrations [MICs]) with the pharmacokinetic profile. The targeted pharmacodynamic parameters assessed by this technique include the ratio of peak concentration (C_max) to MIC (C_max:MIC); the ratio of the area under the plasma concentration-time curve (AUC) to MIC (AUC:MIC), and the time the drug concentration exceeds the MIC (T MIC). Some antimicrobials, e.g., the aminoglycosides, are most effective/bactericidal when they have a high C_max:MIC ratio; others, e.g., the fluoroquinolones, are more effective when the AUC:MIC ratio is high. In both of these scenarios, organism eradication is concentration-dependent, and the therapeutic goal is to maximize drug exposure. Like the fluoroquinolones, the efficacy of telithromycin, a newly developed ketolide, is most related to the AUC:MIC ratio. Outcome for other agents, such as the -lactams, is best predicted by the T MIC; in this case, organism eradication is time-dependent, and the therapeutic goal is to optimize the duration of antimicrobial exposure. This article discusses how the use of currently available antimicrobials can be optimized through an appreciation of pharmacodynamic profiling.     

A new method for the diagnosis of acute hemorrhagic-necrotizing pancreatitis using contrast-enhanced CT

Twenty-eight consecutive patients with a first attack of alcohol-induced pancreatitis were studied using contrast-enhanced CT. The findings on CT were then related to the course of the disease. The patients with acute hemorrhagic-necrotizing pancreatitis showed significantly lower enhancement values of the pancreatic parenchyma than those with milder forms of the disease.The next 20 patients with severe pancreatitis were scanned using a slightly modified procedure. The enhancement values were calculated and plotted on the graphs for the 2 former groups.Two categories of pancreatic enhancement were found: low enhancement and high enhancement. In all 10 patients with low-enhancement values surgery revealed hemorrhagic-necrotizing pancreatitis. In the 10 patients with highenhancement values conservative treatment was continued, and the clinical course was nonfulminant in all of them.     

Is coronary stent deployment and remodeling affected by predilatation? An intravascular ultrasound randomized study Stenting with or without predilation: an IVUS study

In this intravascular ultrasound (IVUS) randomized trial we compared a strategy of direct stenting (DS) without predilation (n = 30) vs. conventional stenting with predilation (SWP) (n = 30) in patients with suitable type A or B non-calcified lesions in native vessels 3 mm. Optimal deployment was achieved using angiographic criteria without interactive IVUS. The goal of our study was to determine whether stent expansion and coronary remodeling were similar. Maximal pressure inflation was comparable in the two groups (11.4 ± 2.2 vs. 11.8 ± 1.9 atm; NS). Stent deployment was obtained in all patients with complete apposition to the vessel wall. DS and SWP resulted in comparable lumen enlargement (5.4 ± 2.5 vs. 5.5 ± 2.1 mm²) with an identical mechanism: 66% of lumen enlargement was due to increased enlarged elastic membrane (EEM)-cross sectional area (CSA) ( = 3.7 ± 2.1 mm² and = 2.4 ± 6.8 mm², respectively, p < 0.49) and 34% was due to a reduced P + M-CSA ( = 0.02 ± 6.9 mm² and = 1.2 ± 6.3 mm², respectively, p < 0.50). We conclude that at the same maximal pressure inflation the mechanisms of stent expansion are similar in both DS and SWP groups. In this observational study, the IVUS data showed clearly under-expansion of stents in both groups in comparison with previously published CSA values (minimum stent CSA of 7.5 mm²).