Schwere Anaphylaxie nach Rocuronium

Muscle relaxant drugs are the most frequent cause of anaphylactic and anaphylactoid reactions during anaesthesia. We report a case of a life-threatening anaphylactic reaction during induction of anaesthesia with severe bronchospasm as the first clinical symptom. Mechanical ventilation was nearly impossible. The patient required a multimodal antiallergic therapy and a high-dose catecholamine therapy for stabilization. Rocuronium was identified as the allergic agent using intradermal testing.

The influence of PEEP and tidal volume on central blood volume

BACKGROUND AND OBJECTIVE

Measurement of central blood volumes (CBV), such as global end-diastolic volume (GEDV) and right ventricular end-diastolic volume (RVEDV) are considered appropriate estimates of intravascular volume status. However, to apply those parameters for preload assessment in mechanically ventilated patients, the influence of tidal volume (TV) and positive endexpiratory airway pressure (PEEP) on those parameters must be known.

METHODS

In 13 mechanically ventilated piglets, the effect of low (10 mL kg(-1)) and high (20 mL kg(-1)) TVs on CBV was investigated in absence and presence of PEEP (0 and 15 cm H(2)O). GEDV, RVEDV, right heart (RHEDV) and left heart end-diastolic volume (LHEDV) were measured by thermodilution. Blood flow on the descending thoracic aorta measured with an ultrasonic flow-probe served to determine stroke volume (SV). Measurements were performed during baseline conditions, after volume loading with previously extracted haemodilution blood (20 mL kg(-1)) and following haemorrhage (30 mL kg(-1)).

RESULTS

Application of PEEP decreased GEDV and SV significantly (P < 0.05). Augmenting TV did not reduce GEDV systematically, but significantly reduced SV (P < 0.05). Changes in ventilator settings only influenced RVEDV following volume loading (P < 0.05). RHEDV and LHEDV decreased following application of PEEP, but only RHEDV decreased after augmenting TV at baseline and following volume loading. Correlation of SV with parameters of CBV was r = 0.487 (P < 0.01) for GEDV, r = 0.553 (P < 0.01) for RVEDV, r = 0.596 (P < 0.01) for RHEDV and r = 0.303 (P < 0.01) for LHEDV.

CONCLUSION

Application of PEEP decreases CBV and SV. Augmenting TV reduces SV but not CBV. There is a moderate correlation between parameters of CBV and cardiac performance.

The influence of positive end-expiratory pressure on stroke volume variation and central blood volume during open and closed chest conditions

OBJECTIVE

Intermittent positive pressure ventilation and positive end-expiratory pressure (PEEP) affect cardiac preload. Their effect is dependent on chest wall compliance. This study compares the effects of intermittent positive pressure ventilation and PEEP on stroke volume variation and central blood volume during open and closed chest conditions.

MATERIALS AND METHODS

Fourteen anesthetized and mechanically ventilated pigs (25-40 kg) were studied. Central blood volume was assessed using global end-diastolic volume and right ventricular end-diastolic volume measured by thermodilution. Further, left and right ventricular stroke volume variations were determined with ultrasonic flow probes placed around the pulmonary artery and ascending aorta, respectively. Measurements were performed during mechanical ventilation without and with PEEP (15 cmH(2)O) in open and closed chest conditions.

RESULTS

With the chest closed mean arterial pressure, cardiac output, stroke volume, global end-diastolic volume, and right ventricular end-diastolic volume were significantly lower when compared to open chest conditions. Concomitantly, right ventricular, but not left ventricular stroke volume variation increased significantly. Applying PEEP led to a significant reduction of cardiac output, stroke volume and right ventricular end-diastolic volume, with a concomitant increase in left and right ventricular stroke volume variation both during open and closed chest conditions (all P-values<0.05).

CONCLUSIONS

We conclude that PEEP increases right and left ventricular stroke volume variation both during open and closed chest conditions. The concomitant reduction of right ventricular end-diastolic volume further indicates that PEEP has a preload reductive effect during open chest conditions, too.

[Fast-track surgery in radical retropubic prostatectomy. First experiences with a comprehensive program to enhance postoperative convalescence]

Fast-track surgery is a comprehensive program for the optimization of perioperative care in elective surgery reducing potential postoperative complications and speeding up convalescence. Recent data from randomized colon resection trials emphasize that fast-track surgery is possible in most major operations. Our initial results in radical retropubic prostatectomy fast-track surgery have been encouraging. Fast-track surgery in major urological operations needs validation using randomized trials.

Die Nutzung der Erlösdaten der „DRGs“ für ein externes Benchmarking der anästhesiologischen und intensivmedizinischen Leistungserbringung

Measurement and assessment of the economic efficiency of clinical departments is still an unresolved, yet important problem in hospital management. Benchmarking with other providers can help to evaluate one's own efficacy in anaesthesia and intensive care services. In this article we describe a method for using the diagnosis-related-groups (DRG) cost breakdown data, to achieve a case mix adjusted comparison of own costs for anaesthesia and intensive care services with the average costs in German hospitals. On the basis of 19,401 cases from 10 different surgical departments, we compared our own costs with the German-wide benchmark. Major factors for profit optimisation are discussed. Special attention is given to the close interaction of surgical, anaesthesiological and intensive care process performance and costs and its impact on benchmarking studies.

Messung des Herzzeitvolumens

Diagnosis and therapy of hemodynamic instability are of the utmost importance in the treatment of critically ill patients during surgery and in intensive care. For both diagnosis and therapy, adequate and preferably continuous hemodynamic monitoring is essential. Besides the assessment of cardiac preload and blood pressure, cardiac output represents an important clinical marker of cardiac performance and global perfusion. Since its clinical introduction by Swan and Ganz in 1970, the standard technique for measuring cardiac output has been the pulmonary arterial thermodilution technique using a pulmonary artery catheter. The ongoing discussion on the risk-benefit ratio of such a pulmonary artery catheter has led to the introduction of several less invasive methods for determining cardiac output. The aim of this review is to provide background information on these alternative methods and to discuss the individual advantages and disadvantages of each method in the context of their clinical applicability.

The influence of cardiac preload and positive end-expiratory pressure on the pre-ejection period

The pre-ejection period (PEP) has recently been described as a potential parameter for monitoring cardiac preload. This study further investigated the influence of changes in intravascular volume status and the application of positive end-expiratory pressure (PEEP) on the pre-ejection period. In ten pigs, ECG, arterial pressure and stroke volume derived from an aortic flowprobe were registered. Global end-diastolic volume (GEDV) was measured by transcardiopulmonary thermodilution. Total blood volume (TBV) and intrathoracic blood volume (ITBV) were measured by the dye-dilution technique. Measurements were performed during normovolaemic conditions, after volume loading with haemodilution blood (20 ml kg(-1)) and following haemorrhage (30 ml kg(-1)) without PEEP and with PEEP (15 cm H(2)O) applied. Volume loading increased GEDV, ITBV, TBV and SV, whereas PEP remained constant. However, the changes were not significant (P > 0.05). Subsequent haemorrhage significantly decreased GEDV (from 436 to 308 ml), ITBV (from 729 to 452 ml), TBV (from 2,131 to 1,488 ml) (all P-values <0.05), and SV (from 20.7 ml to 14.3 ml, P < 0.001). However, PEP did not change significantly (from 73 to 82 ms, P > 0.05). No correlation between the changes in PEP and changes in any other variable was observed. It is concluded that PEP is not sensitive to the changes in intravascular volume status.

Arterielle Pulskonturanalyse zur Messung des Herzindex unter Veränderungen der Vorlast und der aortalen Impedanz

BACKGROUND

Cardiac index obtained by arterial pulse contour analysis (CI(PC)) demonstrated good agreement with arterial or pulmonary arterial thermodilution derived cardiac index (CI(TD), CI(PA)) in cardiac surgical or critically ill patients. However as the accuracy of pulse contour analysis during changes of the aortic impedance is unclear, we compared CI(PC), CI(TD) and CI(PA) during changes of preload and the aortic impedance as occurring during sternotomy.

PATIENTS AND METHODS

CI(PC) und CI(TD), were compared in 28 patients, (and CI(PA) in 6 patients) undergoing elective coronary artery bypass grafting, before and after sternotomy. The relative changes DeltaCI(PC) und DeltaCI(PC) were calculated.

RESULTS

Sternotomy resulted in a significant increase in CI in 25 out of 28 patients. Regression analysis was performed between CI(PC) and CI(TD) before and after sternotomy (r(2) = 0.87, p<0.0001, r(2) = 0.88, p<0.0001) as well as between CI(PC) and CI(PA), before and after sternotomy (r(2) = 0.85, p<0.0001, r(2) = 0.93, p<0.01) and between DeltaCI(PC) and DeltaCI(TD) (r(2) = 0.72, p<0.0001). Bland Altman-Analysis for determining bias (m) and precision (2SD) between CI(PC) and CI(TD) before and after sternotomy and between DeltaCI(PC) and DeltaCI(TD) resulted in m = -0.03 L/min/m(2), 2SD = -0.34 to 0.28 L/min/m(2), m = -0.06 L/min/m(2), 2SD = -0.45 to 0.33 L/min/m(2) and m = -0.02 L/min/m(2), SD = -0.47 to 0.44 L/min/m(2).

CONCLUSION

Pulse contour analysis derived CI(PC) accurately reflects thermodilution derived CI(TD) or CI(PA) during changes of preload and the aortic impedance as occurring during sternotomy.

Cardiac index measurements during rapid preload changes: a comparison of pulmonary artery thermodilution with arterial pulse contour analysis

STUDY OBJECTIVE

To compare cardiac index (CI) values obtained by pulmonary artery thermodilution (CIPA), arterial thermodilution (CITD), and arterial pulse contour analysis (CIPC) during rapid fluid administration, as accurate and rapid detection of CI changes is critical during acute preload changes for guiding volume and vasopressor therapy in critically ill patients, and the accuracy of CIPC during acute changes in loading condition is currently unknown.

DESIGN

Prospective clinical study.

SETTING

Cardiac surgical intensive care unit of a university hospital.

PATIENTS

Seventeen American Society of Anesthesiologists (ASA) physical status II and III patients, aged 32 to 76 years, with normal left ventricular function during the early postoperative period after elective coronary artery bypass graft surgery.

MEASUREMENTS

After baseline determinations of CIPA, CIPC, and CITD were made, fluid loading was performed using 10 mL times body mass index of hydroxyethyl starch 6%. CIPA, CIPC, and CITD were determined, and changes in CI (DeltaCI) were calculated. Fluid load was repeated until no increase in stroke volume index (DeltaSVI <10%) was achieved.

MAIN RESULTS

Regression analysis between CIPA/CIPC, CIPA/CITD, and CIPC/CITD revealed r2 = 0.92, r2 = 0.92, and r2 = 0.98. Regression analysis between DeltaCIPA/DeltaCIPC, DeltaCIPA/DeltaCITD, and DeltaCIPC/DeltaCITD revealed r2 = 0.57, r2 = 0.67, and r2 = 0.74, respectively. Bland-Altman analysis was used to determine accuracy and precision of the 3 methods compared. The mean differences (m) and SD between DeltaCIPA/DeltaCIPC, DeltaCIPA/DeltaCITD, and DeltaCIPC/DeltaCITD resulted in m = -1.01%, SD = 6.51%; m = -0.83%, SD = 5.80%; and m = -0.33%, SD = 4.65%, respectively.

CONCLUSION

Compared with pulmonary artery thermodilution, arterial pulse contour analysis reflects relative changes in CI during rapid changes of preload with clinically acceptable accuracy.

Assessing fluid responsiveness during open chest conditions

BACKGROUND

Measurement of ventilation-induced left ventricular stroke volume variations (SVV) or pulse pressure variations (PPV) is useful to optimize preload in patients after cardiac surgery. The aim of this study was to investigate the ability of SVV and PPV measured by arterial pulse contour analysis to assess fluid responsiveness in patients undergoing coronary artery bypass surgery during open-chest conditions.

METHODS

We studied 22 patients immediately after midline sternotomy. We determined SVV, PPV, left ventricular end-diastolic area index by transoesophageal echocardiography, global end-diastolic volume index and cardiac index by thermodilution before and after removal of blood 500 ml and after volume substitution with hydroxyethyl starch 6%, 500 ml.

RESULTS

Blood removal resulted in a significant increase in SVV from 6.7 (2.2) to 12.7 (3.8)%. PPV increased from 5.2 (2.5) to 11.9 (4.6)% (both P<0.001). Cardiac index decreased from 2.9 (0.6) to 2.3 (0.5) litres min(-1) m(-2) and global end-diastolic volume index decreased from 650 (98) to 565 (98) ml m(-2) (both P<0.025). Left ventricular end-diastolic area index did not change significantly. After fluid loading SVV decreased significantly to 6.8 (2.2)% and PPV decreased to 5.4 (2.1)% (both P<0.001). Concomitantly, cardiac index increased significantly to 3.3 (0.5) litres min(-1) m(-2) (P<0.001) and global end-diastolic volume index increased significantly to 663 (104) ml m(-2) (P<0.005). Left ventricular end-diastolic area index did not change significantly. We found a significant correlation between the increase in cardiac index caused by fluid loading and SVV as well as PPV before fluid loading (SVV, R=0.74, P<0.001; PPV, R=0.61, P<0.005). No correlations were found between values of global end-diastolic volume index or left ventricular end-diastolic area index before fluid loading and the increase in cardiac index.

CONCLUSION

Measurement of SVV or PPV allows assessment of fluid responsiveness in hypovolaemic patients under open-chest and open-pericardium conditions. Thus, measuring heart-lung interactions may improve haemodynamic management during surgical procedures requiring mid-line sternotomy.

Platelet-endothelial cell interaction in pulmonary micro-circulation: the role of PARS

Accumulation of platelets might contribute to acute lung injury during systemic inflammation. The aim of the study was to elucidate the role of the poly (ADP-ribose) synthetase, a nucleotide-polymerizising enzyme, in mediation of platelet-endothelial cell interaction through regulation of adhesion molecules within the pulmonary microcirculation during endotoxemia. We used in vivo fluorescence microscopy to quantify kinetics of fluorescently labeled erythrocytes and platelets in rabbit pulmonary arterioles and venules. Six hours after onset of endotoxin infusion we observed a massive interaction of platelets with the microvascular endothelial cells, whereas under control conditions, no platelet sequestration was measured. An up-regulation of P- and E-selectin was detected in lung tissue following endotoxin infusion by immunohistochemistry and Western blot analysis. Blockade of endothelial P-selectin with fucoidin resulted in a reduction of the endotoxin-induced platelet-endothelial cell interaction. Inhibition of poly (ADP-ribose) synthetase by 3-aminobenzamide inhibited the endotoxin-induced expression of endothelial P- and E-selectin and the subsequent recruitment of platelets. In summary, we provide first in vivo evidence that platelets accumulate in pulmonary microcirculation following endotoxemia. Poly (ADP-ribose) synthetase seems to mediate this platelet-endothelial cell interaction via P- and E-selectin expressed on the surface of microvascular endothelium.

Colloidal gold particles as a new in vivo marker of early acute lung injury

Permeability of the endothelial barrier to large molecules plays a pivotal role in the manifestation of early acute lung injury. We present a novel and sensitive technique that brings microanatomical visualization and quantification of microvascular permeability in line. White New Zealand rabbits were anesthetized and ventilated mechanically. Rabbit serum albumin (RSA) was labeled with colloidal gold particles. We quantified macromolecular leakage of gold-labeled RSA and thickening of the gas exchange distance by electron microscopy, taking into account morphology of microvessels. The control group receiving a saline solution represented a normal gas exchange barrier without extravasation of gold-labeled albumin. Infusion of lipopolysaccharide (LPS) resulted in a significant displacement of gold-labeled albumin into pulmonary cells, the lung interstitium, and even the alveolar space. Correspondingly, intravital fluorescence microscopy and digital image analysis indicated thickening of width of alveolar septa. The findings were accompanied by a deterioration of alveolo-arterial oxygen difference, whereas wet/dry ratio and albumin concentration in the bronchoalveolar lavage fluid failed to detect that early stage of pulmonary edema. Inhibition of the nuclear enzyme poly(ADP-ribose) synthetase by 3-aminobenzamide prevented LPS-induced microvascular injury. To summarize: colloidal gold particles visualized by standard electron microscopy are a new and very sensitive in vivo marker of microvascular permeability in early acute lung injury. This technique enabling detailed microanatomical and quantitative pathophysiological characterization of edema formation can form the basis for evaluating novel treatment strategies against acute lung injury.

Role of PARP on iNOS pathway during endotoxin-induced acute lung injury

OBJECTIVE

Excessive nitric oxide (NO) and especially peroxynitrite may cause pulmonary tissue damage, e.g., through lipid peroxidation and/or exhaustion of cellular energy depletion induced by activation of poly (ADP-ribose) polymerase (PARP). Furthermore, PARP seems to aggravate tissue destruction by regulating the expression of respective genes.

DESIGN

Prospective animal study.

SETTING

University research laboratory.

INTERVENTION

We investigated the effect of competitive PARP inhibition by 3-aminobenzamide (3-AB) on the pulmonary iNOS pathway after infusion of lipopolysaccharide (LPS).

MEASUREMENTS AND RESULTS

The pretreatment of rabbits with 3-AB attenuated the LPS-induced iNOS mRNA and protein expression analyzed by RT-PCR and Western blot, and plasma nitrite concentrations quantified by Griess reaction (71+/-6%, 93+/-6% vs baseline). Electromobility shift assay showed an enhanced NF-kappaB and attenuated AP-1 activation after 3-AB vs LPS alone. Lipid peroxidation determined as levels of thiobarbituric acid reactive substances in plasma and lung tissue was reduced by 50% in the LPS+3-AB in comparison to LPS alone. Simultaneously, 3-AB was able to inhibit correspondingly the LPS-induced extravasation of gold-labeled albumin and increase of alveolo-arterial oxygen difference.

CONCLUSION

PARP regulates the pulmonary NO pathway during endotoxemia via AP-1 and not NF-kappaB. Thus, pharmacological inhibition of PARP might be an effective intervention to prevent endotoxin-induced lung injury, interrupting the vicious circle of NO production and PARP activation.

Effects of mid‐line thoracotomy on the interaction between mechanical ventilation and cardiac filling during cardiac surgery

BACKGROUND

Mid-line thoracotomy is a standard approach for cardiac surgery. However, little is known how this surgical approach affects the interaction between the circulation and mechanical ventilation. We studied how mid-line thoracotomy affects cardiac filling volumes and cardiovascular haemodynamics, particularly variations in stroke volume and pulse pressure caused by mechanical ventilation.

METHODS

We studied 19 patients during elective coronary artery bypass surgery. Before and after mid-line thoracotomy, we measured arterial pressure, cardiac index (CI) and global end-diastolic volume index (GEDVI) by thermodilution, left ventricular end-diastolic area index (LVEDAI) by transoesophageal echocardiography and the variations in left ventricular stroke volume and pulse pressure during ventilation by arterial pulse contour analysis.

RESULTS

After thoracotomy, CI increased from 2.3 (0.4) to 2.9 (0.6) litre min(-1) m(-2), GEDVI increased from 605 (110) to 640 (94) litre min(-1) m(-2), and LVEDAI increased from 9.2 (3.7) to 11.2 (4.1) cm(2) m(-2). All these changes were significant. In contrast, stroke volume variation (SVV) decreased from 10 (3) to 6 (2)% and pulse pressure variation (PPV) decreased from 11 (3) to 5 (3)%. Before thoracotomy, SVV and PPV significantly correlated with GEDVI (both P<0.01). When the chest was open, similar significant correlations of SVV (P<0.001) and PPV (P<0.01) were found with GEDVI.

CONCLUSION

Thoracotomy increases cardiac filling and preload. Further, thoracotomy reduces the effect of mechanical ventilation on left ventricular stroke volume. However, also under open chest conditions, SVV and PPV are preload-dependent.

Role of poly(ADP-ribose) synthetase in pulmonary leukocyte recruitment

During systemic inflammation, recruitment and activation of leukocytes in the pulmonary microcirculation may result in a potentially life-threatening acute lung injury. We elucidated the role of the poly(ADP-ribose) synthetase (PARS), a nucleotide-polymerizing enzyme, in the regulation of leukocyte recruitment within the lung with regard to the localization in the pulmonary microcirculation and in correlation to hemodynamics in the respective vascular segments and expression of intercellular adhesion molecule 1 during endotoxemia. Inhibition of PARS by 3-aminobenzamide reduced the endotoxin-induced leukocyte recruitment within pulmonary arterioles, capillaries, and venules in rabbits as quantified by in vivo fluorescence microscopy. Microhemodynamics and thus shear rates in all pulmonary microvascular segments remained constant. Simultaneously, inhibition of PARS with 3-aminobenzamide suppressed the endotoxin-induced adhesion molecules expression as demonstrated for intercellular adhesion molecule 1 by immunohistochemistry and Western blot analysis. We confirmed this result with the use of PARS knockout mice. The inhibitory effect of 3-aminobenzamide on leukocyte recruitment was associated with a reduction of pulmonary capillary leakage and edema formation. We first provide evidence that PARS activation mediates the leukocyte sequestration in pulmonary microvessels through upregulation of adhesion molecules. As reactive oxygen species released from leukocyte are supposed to cause an upregulation of adhesion molecules we conclude that PARS inhibition contributes to termination of this vicious cycle and inhibits the inflammatory process.

Einsch�tzung der Volumenreagibilit�t beim beatmeten Patienten

Monitoring and management of intravascular volume status is of crucial importance in critically ill patients. Hypovolemia, induced by hemorrhage or pathologic fluid shifts in the presence of systemic inflammation, is frequently the cause for hemodynamic instability and hypotension. This deficit of central blood volume leads to a reduction in biventricular cardiac preload. With respect to the Frank-Starling mechanism, this causes an alteration in left ventricular stroke volume. If this reduction in stroke volume cannot be compensated by an increase in heart rate, this finally results in a decline of cardiac output. In this clinical situation fluid loading is the treatment of choice. However, insufficient peripheral vascular resistance and thus reduced cardiac afterload as well as impaired myocardial contractility also have to be taken in account to be causative for hypotension. Potential hazards of fluid loading specifically in the latter situation include pulmonary edema, worsening of pulmonary gas exchange and myocardial failure. Thus, prediction of fluid responsiveness, i.e. the prediction of the hemodynamic response to fluid loading is of utmost importance in critically ill patients. Several conventional parameters of systemic hemodynamic monitoring such as the cardiac filling pressures CVP and PAOP, the estimation of the left ventricular end-diastolic area (LVEDA) by echocardiography and measurement of central blood volumes as the right-ventricular end-diastolic volume (RVEDV) or the global end-diastolic volume (GEDV) by thermodilution are frequently used for preload monitoring. Further, functional preload parameters such as the left ventricular stroke volume variation (SW), describing the specific interactions of the heart and the lungs under mechanical ventilation, have been recently proposed to be useful for predicting fluid responsiveness. Thus, it is the aim of the present article to analyze these different concepts of hemodynamic monitoring regarding their usefulness and clinical applicability to predict fluid responsiveness at the bedside.

Hyperthermia induces T1 relaxation and blood flow changes in tumors. A MRI thermometry study in vivo

Regional hyperthermia in combination with chemotherapy and/or radiotherapy has proven to be an effective treatment concept for locally advanced deep-seated tumors. Simultaneous MR-imaging could be a promising approach for therapy optimization. Purpose of this study was the in vivo investigation of temperature induced longitudinal relaxation time (T(1)) and blood flow changes in a tumor model. Using a 1.5 Tesla MR system, the T(1) sensitivity on temperature and the onset of tissue changes at temperatures >44 degrees C were investigated in muscle samples. Also, fourteen Syrian Golden Hamsters with amelanotic melanoma A-MEL-3 were examined during heating of the tumors. Temperature induced blood flow and T(1) changes were determined continuously during hyperthermia. Changes of T(1) correlated linearly with temperature over a wide range (27-44 degrees C) in the tissue sample. Tissue changes became notable above 44 degrees C. In the tumor model, relative changes of T(1) (unlike blood flow) showed linear correlation with temperature over the entire range of hyperthermia relevant temperatures (32-44 degrees C). For a low thermal dose, T(1) allows the assessment of temperature changes in tumors in vivo. At higher thermal doses, in addition to temperature changes, T(1) also shows tissue changes. Both temperature and tissue changes supply important information for hyperthermia.

Usefulness of left ventricular stroke volume variation to assess fluid responsiveness in patients with reduced cardiac function

OBJECTIVE

Stroke volume variation as measured by the analysis of the arterial pressure waveform enables prediction of volume responsiveness in ventilated patients with normal cardiac function. The aim of this study was to investigate the ability of monitoring stroke volume variation to predict volume responsiveness and to assess changes in preload in patients with reduced left ventricular function after cardiac surgery.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENTS

Fifteen mechanically ventilated patients with a left ventricular ejection fraction <0.35 (study group) and 15 patients with an ejection fraction >0.50 (control group) after coronary artery bypass grafting following admission to the intensive care unit.

INTERVENTIONS

Volume loading with 10 mL of hetastarch 6% times body mass index. If stroke volume index increased >5%, successive volume loading was performed until no further increase in stroke volume index was reached.

MEASUREMENTS AND MAIN RESULTS

Stroke volume variation, central venous pressure, pulmonary artery occlusion pressure (PAOP), and left ventricular end-diastolic area index (LVEDAI) were measured at baseline and immediately after each volume loading step. In both groups, stroke volume variation at baseline correlated significantly with changes in stroke volume index caused by volume loading (p <.01). Further, changes in stroke volume variation as a result of volume loading correlated significantly with the concomitant changes in stroke volume index in both groups (p <.01). Using receiver operating characteristic analysis, in the study group areas under the curve for stroke volume variation, PAOP, central venous pressure, and LVEDAI did not differ significantly. In the control group, the area under the curve for stroke volume variation was statistically larger than for PAOP, central venous pressure, and LVEDAI.

CONCLUSIONS

Continuous and real-time monitoring of stroke volume variation by pulse contour analysis can predict volume responsiveness and allows real-time assessment of the hemodynamic effect of volume expansion in patients with reduced left ventricular function after cardiac surgery.

Stress doses of hydrocortisone reduce severe systemic inflammatory response syndrome and improve early outcome in a risk group of patients after cardiac surgery

OBJECTIVE

Severe systemic inflammation with a vasodilatory syndrome occurs in about one third of all patients after cardiac surgery with cardiopulmonary bypass. Hydrocortisone has been used successfully to reverse vasodilation in septic patients. We evaluated if stress doses of hydrocortisone attenuate severe systemic inflammatory response syndrome in a predefined risk group of patients after cardiac surgery with cardiopulmonary bypass.

DESIGN

Randomized, nonblinded, controlled trial.

SETTING

Anesthesiologic intensive care unit for cardiac surgical patients of an university hospital.

PATIENTS

After a risk analysis, we enrolled 91 patients into a prospective randomized trial. Patients were included according to the evaluated criteria (preoperative ejection fraction, duration of cardiopulmonary bypass, type of surgery).

INTERVENTIONS

The treatment group received stress doses of hydrocortisone perioperatively: 100 mg before induction of anesthesia, then 10 mg/hr for 24 hrs, 5 mg/hr for 24 hrs, 3 x 20 mg/day, and 3 x 10 mg/day.

MEASUREMENTS AND MAIN RESULTS

We measured various laboratory (e.g., lactate) and clinical variables (e.g., duration of ventilation and length of stay in the intensive care unit), characterizing the patients' outcome. The two study groups did not differ regarding age, preoperative medication, duration of the cardiopulmonary bypass, and type of surgery. The patients in the treatment group had significantly lower concentrations of IL-6 and lactate, higher antithrombin III concentration, lower need for circulatory and ventilatory support and for transfusions, lower Therapeutic Intervention Scoring System values, and shorter length of stay in the intensive care unit and in the hospital. The mortality rate did not differ significantly between the groups.

CONCLUSIONS

Although we acknowledge the limitations of a nonblinded interventional trial, stress doses of hydrocortisone seem to attenuate systemic inflammation in a predefined risk group of patients after cardiac surgery with cardiopulmonary bypass and improve early outcome.

Influence of tidal volume on left ventricular stroke volume variation measured by pulse contour analysis in mechanically ventilated patients

OBJECTIVE

Real-time measurement of stroke volume variation by arterial pulse contour analysis (SVV) is useful in predicting volume responsiveness and monitoring volume therapy in mechanically ventilated patients. This study investigated the influence of the depth of tidal volume (V(t)) on SVV both during the state of fluid responsiveness and after fluid loading in mechanically ventilated patients.

DESIGN AND SETTING

Prospective study in a university hospital, adult cardiac surgery intensive care unit.

PATIENTS AND PARTICIPANTS

20 hemodynamically stable patients immediately after cardiac surgery.

INTERVENTIONS

Stepwise fluid loading using colloids until stroke volume index (SVI) did not increase by more than 10%. Before and after fluid loading V(t) was varied (5, 10, and 15 ml/kg body weight) in random order.

MEASUREMENTS AND RESULTS

Pulse contour SVV was measured before and after volume loading at the respective V(t) values. Thirteen patients responded to fluid loading with an increase in SVI greater than 10%, which confirmed volume responsiveness at baseline measurements. These were included in further analysis. During volume responsiveness SVV at V(t) of 5 ml/kg (7+/-0.7%) and SVV at V(t) of 15 ml/kg (21+/-2.5%) differed significantly from that at V(t) of 10 ml/kg (15+/-2.1%). SVV was correlated significantly with the magnitude of V(t). After volume resuscitation SVV at the respective V(t) was significantly reduced; further, SVV at V(t) of 5 ml/kg(-1) (5.3+/-0.6%) and 15 ml/kg (16.2+/-2.0%) differed significantly from that at V(t) of 10 ml/kg (10.2+/-1.0%). SVV and depth of V(t) were significantly related.

CONCLUSIONS

In addition to intravascular volume status SVV is affected by the depth of tidal volume under mechanical ventilation. This influence must be regarded when using SVV for functional preload monitoring.

Trendelenburg positioning after cardiac surgery: effects on intrathoracic blood volume index and cardiac performance

BACKGROUND AND OBJECTIVE

The efficacy of the Trendelenburg position, a common first step to treat suspected hypovolaemia, remains controversial. We evaluated its haemodynamic effects on cardiac preload and performance in patients after cardiac surgery.

METHODS

Twelve patients undergoing mechanical ventilation of the lungs who demonstrated left ventricular 'kissing papillary muscles' by transoesophageal echocardiography, thus suggesting hypovolaemia, were positioned 30 degrees head down for 15 min immediately after cardiac surgery. Cardiac output by thermodilution, central venous pressure, pulmonary artery occlusion pressure, left ventricular end-diastolic area by transoesophageal echocardiography and intrathoracic blood volume by thermo- and dye dilution were determined before, during and after this Trendelenburg manoeuvre.

RESULTS

Trendelenburg's manoeuvre was associated with increases in central venous pressure (9 +/- 2 to 12 +/- 3 mmHg) and pulmonary artery occlusion pressure (8 +/- 2 to 11 +/- 3 mmHg). The intrathoracic blood volume index increased slightly (dye dilution from 836 +/- 129 to 872 +/- 112 mL m(-2); thermodilution from 823 +/- 129 to 850 +/- 131 mL m(-2)) as did the left ventricular end-diastolic area index (7.5 +/- 2.1 to 8.1 +/- 1.7 cm2 m(-2)), whereas mean arterial pressure and the cardiac index did not change significantly. After supine repositioning, the cardiac index decreased significantly below baseline (3.0 +/- 0.6 versus 3.5 +/- 0.8 L min(-1) m(-2)) as did mean arterial pressure (76 +/- 12 versus 85 +/- 11 mmHg), central venous pressure (8 +/- 2 mmHg) and pulmonary artery occlusion pressure (6 +/- 4 mmHg). The intrathoracic blood volume index and left ventricular end-diastolic area index did not differ significantly from baseline.

CONCLUSIONS

Trendelenburg's manoeuvre caused only a slight increase of preload volume, despite marked increases in cardiac-filling pressures, without significantly improving cardiac performance.

Platelet kinetics in the pulmonary microcirculation in vivo assessed by intravital microscopy

Growing evidence supports the substantial pathophysiological impact of platelets on the development of acute lung injury. Methods for studying these cellular mechanisms in vivo are not present yet. The aim of this study was to develop a model enabling the quantitative analysis of platelet kinetics and platelet-endothelium interaction within consecutive segments of the pulmonary microcirculation in vivo. New Zealand White rabbits were anesthetized and ventilated. Autologous platelets were separated from blood and labeled ex vivo with rhodamine 6G. After implantation of a thoracic window, microhemodynamics and kinetics of platelets were investigated by intravital microscopy. Velocities of red blood cells (RBCs) and platelets were measured in arterioles, capillaries and venules, and the number of platelets adhering to the microvascular endothelium was counted. Kinetics of unstimulated platelets was compared with kinetics of thrombin-activated platelets. Velocity of unstimulated platelets was comparable to RBC velocity in all vessel segments. Unstimulated platelets passed the pulmonary microcirculation without substantial platelet-endothelial interaction. In contrast, velocity of activated platelets was decreased in all vascular segments indicating platelet margination and temporal platelet-endothelium interaction. Thrombin-activated platelets adhered to arteriolar endothelium; in capillaries and venules adherence of platelets was increased 8-fold and 13-fold, respectively. In conclusion, using intravital microscopy platelet kinetics were directly analyzed in the pulmonary microcirculation in vivo for the first time. In contrast to leukocytes, no substantial platelet-endothelium interaction occurs in the pulmonary microcirculation without any further stimulus. In response to platelet activation, molecular mechanisms enable adhesion of platelets in arterioles and venules as well as retention of platelets within capillaries.

Comparison of pulmonary arterial thermodilution and arterial pulse contour analysis: evaluation of a new algorithm

STUDY OBJECTIVE

To compare cardiac index (CI) measurement by arterial pulse contour analysis using two different algorithms (CI(PC), CI(PCnew)) with pulmonary arterial thermodilution values (CI(PA)) so as to evaluate the difference between the conventional algorithm, CI(PC), and a new algorithm, CI(PCnew), that accounts for patients' individual aortic compliance.

DESIGN

Prospective, clinical study.

SETTING

Intensive care unit of a university hospital.

PATIENTS

20 ASA physical status II and III patients following elective cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

360 parallel triplicate determinations of CI (CI(PA), CI(PC), CI(PCnew)) were performed within a 90-minute period during the immediate postoperative period. Prior to the start of the study period, CI(PC) as well as CI(PCnew) were calibrated by triplicate femoral arterial thermodilution measurements. Regression analysis of CI(PA) and CI(PC), as well as CI(PA) and CI(PCnew), revealed r = 0.89, p < 0.001, and r = 0.93, p < 0.001, respectively. Bland-Altman analysis was used for determining the accuracy and precision of CI(PC) and CI(PCnew) compared with CI(PA). The mean differences (m) and standard deviation (SD) between CI(PA) and CI(PC,) as well as CI(PA) and CI(PCnew), resulted in m = -0.312 L/min/m(2), SD = 0.456 L/min/m(2), and m = - 0.140 L/min/m(2), SD = 0.328 L/min/m(2), respectively.

CONCLUSION

Arterial pulse contour analysis measurement of CI using either algorithm correlates well with CI values derived by pulmonary arterial thermodilution. However, the algorithm introduced in this study proved to be a more accurate predictor of values as derived by pulmonary artery catheter.

Orthogonal polarisation spectral imaging as a new tool for the assessment of antivascular tumour treatment in vivo: a validation study

Tumour angiogenesis plays a key role in tumour growth, formation of metastasis, detection and treatment of malignant tumours. Recent investigations provided increasing evidence that quantitative analysis of tumour angiogenesis is an indispensable prerequisite for developing novel treatment strategies such as anti-angiogenic and antivascular treatment options. Therefore, it was our aim to establish and validate a new and versatile imaging technique, that is orthogonal polarisation spectral imaging, allowing for non-invasive quantitative imaging of tumour angiogenesis in vivo. Experiments were performed in amelanotic melanoma A-MEL 3 implanted in a transparent dorsal skinfold chamber of the hamster. Starting at day 0 after tumour cell implantation, animals were treated daily with the anti-angiogenic compound SU5416 (25 mg kg x bw(-1)) or vehicle (control) only. Functional vessel density, diameter of microvessels and red blood cell velocity were visualised by both orthogonal polarisation spectral imaging and fluorescence microscopy and analysed using a digital image system. The morphological and functional properties of the tumour microvasculature could be clearly identified by orthogonal polarisation spectral imaging. Data for functional vessel density correlated excellently with data obtained by fluorescence microscopy (y=0.99x+0.48, r2=0.97, R(S)=0.98, precision: 8.22 cm(-1) and bias: -0.32 cm(-1)). Correlation parameters for diameter of microvessels and red blood cell velocity were similar (r2=0.97, R(S)=0.99 and r2=0.93, R(S)=0.94 for diameter of microvessels and red blood cell velocity, respectively). Treatment with SU5416 reduced tumour angiogenesis. At day 3 and 6 after tumour cell implantation, respectively, functional vessel density was 4.8+/-2.1 and 87.2+/-10.2 cm(-1) compared to values of control animals of 66.6+/-10.1 and 147.4+/-13.2 cm(-1), respectively. In addition to the inhibition of tumour angiogenesis, tumour growth and the development of metastasis was strongly reduced in SU5416 treated animals. This new approach enables non-invasive, repeated and quantitative assessment of tumour vascular network and the effects of antiangiogenic treatment on tumour vasculature in vivo. Thus, quantification of tumour angiogenesis can be used to more accurately classify and monitor tumour biologic characteristics, and to explore aggressiveness of tumours.

Stroke volume variations for assessment of cardiac responsiveness to volume loading in mechanically ventilated patients after cardiac surgery

OBJECTIVE

We hypothesized that measuring stroke volume variation (SVV) during mechanical ventilation by continuous arterial pulse contour analysis allows the accurate prediction and monitoring of changes in cardiac index (CI) in response to volume administration.

DESIGN AND SETTING

Prospective study in an university hospital.

PATIENTS

Twenty mechanically ventilated patients following cardiac surgery.

INTERVENTIONS

Volume loading with oxypolygelatin (3.5%) 20 ml x body mass index over 10 min.

MEASUREMENTS AND RESULTS

SVV, central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP), left ventricular end-diastolic area index (LVEDAI) by transesophageal echocardiography, intrathoracic blood volume index (ITBVI) by transpulmonary thermodilution and CI were determined immediately before and after volume loading. SVV decreased, while CI, CVP, PAOP, ITBVI, and LVEDAI increased significantly. Percentage changes in CI were significantly correlated to percentage changes in SVV (r(2)=-0.59, p<0.001), ITBVI (r(2)=0.79, p<0.001), and PAOP (r(2)=0.33, p<0.05) and to baseline values of SVV (r(2)=0.55, p<0.05) and LVEDAI (r(2)=-0.68, p<0.001).

CONCLUSIONS

SVV may help to determine the preload condition of ventilated patients following cardiac surgery and to predict and continuously monitor effects of volume administered as part of their hemodynamic management.

Intrathoracic blood volume index measured by thermodilution for preload monitoring after cardiac surgery

OBJECTIVE

To investigate the accuracy of measurement of intrathoracic blood volume index by single thermodilution (ITBVI*) and its sensitivity to detect changes in preload after cardiac surgery compared with conventional transpulmonary arterial dye dilution ITBVI and with conventional monitoring (central venous pressure [CVP] and left ventricular end-diastolic area index [EDAI] by transesophageal echocardiography).

DESIGN

Prospective clinical study.

SETTING

University hospital.

PARTICIPANTS

Nineteen patients immediately after cardiac surgery.

INTERVENTIONS

Volume loading was administered with 20 mL of oxypoligelatine (Haemaccel [Behringwerke Aktiengesellschaft Corp, Marburg, Germany]) 3.5% times body mass index over 10 minutes.

MEASUREMENTS AND MAIN RESULTS

Intrathoracic blood volume index was measured by dye dilution (ITBVI) and thermodilution (ITBVI*) immediately before and after volume loading. Measurements of ITBVI and ITBVI* correlated closely (r = 0.94; p < 0.0001). With volume loading, ITBVI and ITBVI* increased significantly from 877 +/- 195 mL/m(2) to 967 +/- 180 mL/m(2) and from 889 +/- 195 mL/m(2) to 954 +/- 185 mL/m(2). Percent changes in ITBVI (deltaITBVI) and ITBVI* (deltaITBVI*) did not differ significantly and correlated closely (r = 0.90; p < 0.0001). Percent changes in cardiac index (CI) as a result of volume loading (deltaCI) revealed significant correlation to deltaITBVI (r = 0.85; p < 0.0001) and to deltaITBVI* (r = 0.76; p < 0.0005). No significant correlation could be found between deltaCI and deltaEDAI or deltaCVP.

CONCLUSION

In patients undergoing cardiac surgery, determination of ITBVI* revealed close agreement with measurements derived by ITBVI. Enhancement in cardiac preload was adequately detected by ITBVI*.

Measurement of absolute values of hemoglobin oxygenation in the brain of small rodents by near infrared reflection spectrophotometry

Reflection near infrared spectroscopy (reNIRS) has been proposed as a novel technique for the measurement of absolute values of total hemoglobin (tHb), oxygenated hemoglobin (oxHb), hemoglobin saturation (SO2), and cytochrome aa3 oxidation status (oxCyt aa3) in living tissue. In this study, we evaluated reNIRS during physiological cerebral blood flow conditions in rats (n=6) and during the induction of global cerebral ischemia in gerbils (n=6). ReNIRS parameters were assessed over the exposed cerebral cortex and compared to regional cerebral blood flow (rCBF) data obtained by laser Doppler flowmetry. Under physiological conditions, reNIRS measurements reflected the large intra- and interindividual variability of oxHb and tHb in the brain. The absolute values obtained by reNIRS for tHb (6.3 +/- 1.7 mg/ml), oxHb (3.7 +/- 1.1 mg/ml), and SO2 (61 +/- 5%) matched expected values. In contrast, measurements of oxCyt aa3 were unstable and results unreliable. reNIRS reliably detected cerebral ischemia, verified by a reduction of rCBF to 11% of baseline. tHb dropped to 74 +/- 7% of baseline (P<0.001), reflecting ischemic microvascular vasoconstriction. oxHb and SO2 dropped to expected near-zero values (2 +/- 4 and 3 +/- 5% of baseline, respectively; P<0.001). We conclude that reNIRS provides reliable and reproducible absolute values for brain tissue tHb, oxHb, and SO2 in small rodents. Determination of physiological values requires measurements at multiple locations, while cerebral ischemia is reliably detected by continuous recordings at a single location.

Impact of sepsis, lung injury, and the role of lipid infusion on circulating prostacyclin and thromboxane A(2)

OBJECTIVE

To investigate whether plasma levels of prostacyclin (PGI2) and thromboxane A(2) (TxA2) are a function of the infusion rate of soybean-based fat emulsions, severity of systemic inflammation, and pulmonary organ failure.

DESIGN

Prospective, randomized, crossover study.

SETTING

Intensive care unit of a university hospital.

PATIENTS

Eighteen critically ill patients, ten presenting with severe sepsis, eight with SIRS or sepsis complicated with ARDS.

INTERVENTIONS

Patients were randomly assigned to receive rapid fat infusion over 6 h (rFI) or slow fat infusion over 24 h (sFI) along with parenteral nutrition.

MEASUREMENTS AND RESULTS

The stable prostanoids 6-keto-PGF1alpha and TxB2 were measured in arterial and mixed venous blood samples, and at 6-h periods trans-pulmonary balances (TPB) were calculated. Free linoleic acid fraction was determined in arterial blood. rFI induced greater increase of linoleic acid than sFI in both groups. Enhanced prostanoid levels and correlations with linoleic acid availabilities were found, however, in ARDS patients only, revealing the highest sepsis- and lung injury scores. Averaged TPB per 24 h was positive in the sepsis group and negative in the ARDS group as rFI induced lowest TPB values for TxB2 at 6 h.

CONCLUSION

The quantity of prostanoids formed and their subsequent utilization are dependent on the availability of precursor linoleic acid and are probably affected by the severity of SIRS or sepsis and the existence of pulmonary organ failure, respectively. Because TxA2 might be extracted by the injured lung, rapid infusion of soybean-based fat emulsions should be avoided in patients suffering from severe pulmonary organ failure.

[Transesophageal echocardiography: perioperative evaluation of valvular function]

Since its introduction into the operating room, transesophageal echocardiography (TEE) has proven to be an invaluable diagnostic tool for perioperative patient management. TEE allows direct visualization of structural and functional cardiac abnormalities. Therefore, it has become the most important imaging technique to evaluate valular function. Pressure gradients across a stenotic valve can be calculated by measuring the blood flow velocity within the valve. Additionally, the area of the valve can be estimated by using the continuity equation. The severity of regurgitant blood flow across an incompetent valve can be assessed using color flow, continuous or pulsed-wave Doppler. Surgical patients experience significant changes in blood pressure, intrathoracic pressures and volume status in the perioperative period. Therefore, the interaction between these parameters and valvular function is the focus of recent clinical studies and might in future contribute to the perioperative as well as anesthesiological management of patients with valvular dysfunction.

The marginated pool

The pulmonary circulation harbors a large intravascular reservoir of leukocytes referred to as the Marginated Pool. This marginated pool is balanced by propelling and retaining forces acting on leukocytes during their passage through the pulmonary circulation. The present paper discusses these factors and their underlying mechanisms.

Optimizing fluid therapy in mechanically ventilated patients after cardiac surgery by on-line monitoring of left ventricular stroke volume variations. Comparison with aortic systolic pressure variations

BACKGROUND

Mechanical ventilation causes changes in left ventricular preload leading to distinct variations in left ventricular stroke volume and systolic arterial pressure. Retrospective off-line quantification of systolic arterial pressure variations (SPV) has been validated as a sensitive method of predicting left ventricular response to volume administration. We report the real-time measurement of left ventricular stroke volume variations (SVV) by continuous arterial pulse contour analysis and compare it with off-line measurements of SPV in patients after cardiac surgery.

METHODS

SVV and SPV were determined before and after volume loading with colloids in 20 mechanically ventilated patients.

RESULTS

SVV and SPV decreased significantly after volume loading and were correlated (r=0.89; P<0.001). Changes in SVV and changes in SPV as a result of volume loading were also significantly correlated (r=0.85; P<0.005). Changes in SVV correlated significantly with changes in stroke volume index (SVI) (r=0.67; P<0.005) as did changes in SPV (r=0.56; P<0.05). SVV determined before volume loading correlated significantly with changes in SVI (R=0.67; P <0.005). Using receiver operating characteristics curves, the area under the curve was statistically greater for SVV (0.824; 95% confidence interval: [CI] 0.64-1.0) and SPV (0.81; CI: 0.62-1.0) than for central venous pressure (0.451; CI: 0.17-0.74).

CONCLUSIONS

Monitoring of SVV enables real-time prediction and monitoring of the left ventricular response to preload enhancement in patients after cardiac surgery and is helpful for guiding volume therapy.

Continuous cardiac output measurements do not agree with conventional bolus thermodilution cardiac output determination

PURPOSE

To evaluate the performance of two different continuous cardiac output monitoring systems based on the thermodilution principle in critically ill patients.

METHODS

Nineteen cardiac surgical patients were randomly assigned to continuous cardiac output monitoring using one of the two systems under study (group I, IntelliCath(TM) catheter, n=9; group II, Opti-Q(TM) catheter, n=10). Each patient was studied over a period of three hours. Conventional bolus thermodilution cardiac output measurements were carried out every 15 min leading to 13 measurements in each patient. The continuous cardiac output values were compared with the bolus thermodilution measurements. Bias (mean difference between continuous and bolus thermodilution) and precision (SD of differences) were calculated as a measure of agreement between the respective continuous method and conventional bolus thermodilution.

RESULTS

The range of measured cardiac outputs was 3.8-15.4 L*min(-1) (IntelliCath(TM)) and 3.5-8.3 L*min(-1) (OptiQ(TM)). Bias and precision was 0.06 +/- 0.76 L*min(-1) (IntelliCath(TM)) and -0.04 +/- 0.74 L*min(-1) (OptiQ(TM)), respectively. There was no difference in bias between the two systems (P=0.38). +/- 2 SD of the differences (i.e., 95% of the differences) did not fall within the predetermined limits of agreement of +/- 0.5 L*min(-1).

CONCLUSIONS

There was no difference between the two systems regarding the agreement with conventional bolus thermodilution as the standard. A discrepancy between bolus and continuous thermodilution cardiac output measurement techniques above the clinically acceptable limits suggest that they are not interchangeable.

Quantitative imaging of tumour blood flow by contrast-enhanced magnetic resonance imaging

Tumour blood flow plays a key role in tumour growth, formation of metastasis, and detection and treatment of malignant tumours. Recent investigations provided increasing evidence that quantitative analysis of tumour blood flow is an indispensable prerequisite for developing novel treatment strategies and individualizing cancer therapy. Currently, however, methods for noninvasive, quantitative and high spatial resolution imaging of tumour blood flow are rare. We apply here a novel approach combining a recently established ultrafast MRI technique, that is T(1)-relaxation time mapping, with a tracer kinetic model. For validation of this approach, we compared the results obtained in vivo with data provided by iodoantipyrine autoradiography as a reference technique for the measurement of tumour blood flow at a high resolution in an experimental tumour model. The MRI protocol allowed quantitative mapping of tumour blood flow at spatial resolution of 250 x 250 microm(2). Correlation of data from the MRI method with the iodantipyrine autoradiography revealed Spearman's correlation coefficients of Rs = 0.851 (r = 0.775, P < 0.0001) and Rs = 0.821 (r = 0.72, P = 0.014) for local and global tumour blood flow, respectively. The presented approach enables noninvasive, repeated and quantitative assessment of microvascular perfusion at high spatial resolution encompassing the entire tumour. Knowledge about the specific vascular microenvironment of tumours will form the basis for selective antivascular cancer treatment in the future.

Intensive care after minimally invasive and conventional coronary surgery: a prospective comparison

OBJECTIVE

The purpose of this study was to compare the intensive care course of patients after minimally invasive coronary surgery to conventional coronary artery bypass grafting.

DESIGN

Prospective observational study.

SETTING

Intensive care unit of a university hospital.

PATIENTS AND PARTICIPANTS

One hundred and five patients with two-vessel disease consecutively scheduled for elective coronary bypass surgery were enrolled.

INTERVENTIONS

Two techniques of revascularization were performed: the Octopus procedure via median sternotomy without cardiopulmonary bypass (n = 52) and conventional coronary artery bypass grafting CABG (n = 53).

MEASUREMENTS AND RESULTS

Three major categories describing the patients' postoperative course were defined: (1) clinical and laboratory findings, i.e., transfusion rate, catecholamine support, duration of ventilation, Simplified Acute Physiology Score II (SAPS II), serum levels of cardiac enzymes and lactic acid; (2) postoperative complications, i.e., incidence of myocardial infarction (MI), atrial fibrillation (AF), and neurological deficits; (3) this category was defined as "the extent of care" as represented by the Therapeutic Intervention Scoring System (TISS), and the length of stay in the ICU and in the hospital. In the Octopus group significantly lower figures were noted for duration of ventilation [6.1(5.5/9.5) vs 10.2(8.2/11.8) h], cardiac enzymes (CK-MB-Mass [5.1(2.0/8.3) vs 31.3(21.4/39.3) ng/ml], and lactic acid [2.0(1.5/3.3) vs 3.2(2.2/6.5) mmol/l]), incidence of AF (2/52 vs 9/53), and neurological deficits (0/52 vs 4/53), TISS score [72(44/83) vs 84(73/93)], LOS in the ICU [2(1/2) vs 2(2/2) days], and in the hospital [6(5/9) vs 9(8/12) days]. Catecholamine support, SAPS II scores, and incidence of MI of each group did not differ significantly.

CONCLUSIONS

Off-pump coronary surgery via the Octopus technique was superior to conventional CABG regarding the course of patients in the early postoperative period. This implies benefits for the patients and the entire healthcare system.

Effects of intravenous fat emulsions on lung function in patients with acute respiratory distress syndrome or sepsis

OBJECTIVE

To investigate whether rapid or slowly infused intravenous fat emulsions affect the ratio of prostaglandin I2/thromboxane A2 in arterial blood, pulmonary hemodynamics, and gas exchange.

DESIGN

Prospective, controlled, randomized, crossover study.

SETTING

Operative intensive care unit of a university hospital.

PATIENTS

Eighteen critically ill patients. Ten patients were stratified with severe sepsis, and eight patients had acute respiratory distress syndrome (ARDS).

INTERVENTIONS

Patients were assigned randomly to receive intravenous fat emulsions (0.4 x resting energy expenditure) over 6 hrs (rapid fat infusion) or 24 hrs (slow fat infusion) along with a routine parenteral nutrition regimen, by using a crossover study design.

MEASUREMENTS AND MAIN RESULTS

Systemic and pulmonary hemodynamics as well as gas exchange measurements were recorded via respective indwelling catheters. Arterial thromboxane B2 and 6-keto-prostaglandin-F1alpha plasma concentrations were obtained by radioimmunoassay, and 6-keto-prostaglandin-F1alpha/thromboxane B2 ratios (P/T ratios) were calculated. Data were collected immediately before and 6, 12, 18, and 24 hrs after onset of fat infusion. In the ARDS group, P/T ratio increased by rapid fat infusion. Concomitantly, pulmonary shunt fraction, alveolar-arterial oxygen tension difference [P(a-a)o2]/Pao2, and cardiac index increased as well, whereas pulmonary vascular resistance and Pao2/Fio2 declined. After slow fat infusion, a decreased P/T ratio was revealed. This was accompanied by decreased pulmonary shunt fraction, lowered P(a-a)o2/Pao2, and increased Pao2/Fio2. Correlations between plasma concentrations of 6-keto-prostaglandin-F1alpha or thromboxane B2 and measures of respiratory performance could be shown during rapid and slow fat infusion, respectively. In the sepsis group, the P/T ratio remained unchanged at either infusion rate, but pulmonary shunt fraction and P(a-a)o2/Pao2 decreased after rapid fat infusion, whereas Pao2/Fio2 increased.

CONCLUSION

Pulmonary hemodynamics and gas exchange are related to changes of arterial prostanoid levels in ARDS patients, depending on the rate of fat infusion. In ARDS but not in sepsis patients clear of pulmonary organ failure, a changing balance of prostaglandin I2 and thromboxane A2 may modulate gas exchange, presumably via interference with hypoxic pulmonary vasoconstriction.

Tissue distribution and penetration of 5-ALA induced fluorescence in an amelanotic melanoma after topical application

BACKGROUND

Photodynamic therapy (PDT) following topical application of 5-aminolevulinic acid (ALA) is increasingly employed for several types of malignancies. However, data with respect to tissue penetration and distribution of ALA-induced porphyrins after topical application are scarce. Therefore, it was our aim to study tissue distribution and the penetration potency of topically applied ALA.

MATERIAL AND METHODS

We used Syrian golden hamsters implanted with the amelanotic melanoma A-Mel-3 growing in a transparent dorsal skinfold chamber. ALA was topically applied in aqueous solution at a concentration of 3% for 4 hours. The fluorescence pattern was quantified by fluorescence microscopy and digital image analysis from cryosections and given as percentage of a reference standard in medians (25%, 75% quartiles).

RESULTS

Fluorescence intensities in tumors were 90.8% (56.2%, 115.2% of a reference standard, p < 0.01 vs. normal tissue) significantly exceeding normal surrounding host tissue yielding fluorescence intensities of 12.1% (9.1%, 16.1%). The tumor selectivity, that is the ratio of fluorescence intensities between tumor and normal tissue, was 7.3 (6.1, 9.1). For superficial tumors with a thickness of approximately 1 mm no fluorescence gradients after topical application of ALA could be observed.

CONCLUSION

In superficial cancerous lesions the fluorescence distribution of ALA induced porphyrins is tumor selective without significant fluorescence gradients throughout the tumor. Thus, by optimising the treatment modalities for topical ALA-PDT an enhanced efficacy and selectivity will be reached.

Measurement of respiratory impedance by impulse oscillometry--effects of endotracheal tubes

Impulse Oscillometry is a new, noninvasive method to measure respiratory impedance, i.e. airway resistance and reactance at different oscillation frequencies. These parameters are potentially useful for the monitoring of respiratory mechanics in the critically ill patent with respiratory dysfunction. The endotracheal tube, used to mechanically ventilate these patients, however, represents an additional nonlinear impedance that introduces artifacts into the measurements. The objective of this work was therefore to investigate the effects of clinically available endotracheal tubes on resistance and reactance of an in vitro analogue of the respiratory system. Additionally, the effects of decreasing the compressible gas volume in this experimental model, as a simulation of decreased lung capacity and compliance, was investigated. Impulse oscillometric measurements of the test analogue gave highly reproducible results with and without an endotracheal tube. The tubes had significant influence on the measurement of the test object at all frequencies investigated. Changes of low frequent reactance were negligible - at least if repetitive measurements of the same system are performed - for realistic measurement of airway resistance, a correction of the tube impedance or measurement of the pressure distal of the tube is required. Resistance increased and low frequent reactance decreased significantly with decreasing gas volume. These changes were of magnitudes higher than the variations due to the introduction of the endotracheal tubes. Our results suggest that changes of respiratory reactance measured with impulse oscillometry may be used as a monitoring parameter in intubated patients.

Replacement of the valves of a Novacor LVAS without cardiopulmonary bypass

We report the case of a 54-year old man with end-stage heart disease in whom the malfunctioning valves of a Novacor LVAS needed to be replaced after 490 days of circulatory support. This procedure could be performed without cardiopulmonary bypass.

Health-related quality of life and post-traumatic stress disorder in patients after cardiac surgery and intensive care treatment

OBJECTIVES

Health-related quality of life and patient satisfaction have become important end points in cardiac surgery. Post-traumatic stress disorder has been described in patients with life-threatening heart disease. In this study, we investigated the occurrence of post-traumatic stress disorder in a sample of patients after cardiac surgery and compared health-related quality of life and patient satisfaction between patients with and without evidence of post-traumatic stress disorder.

METHODS

We studied 80 patients serially admitted to the intensive care unit after cardiac surgery (bypass grafting, n = 51; aortic valve replacement, n = 29). Health-related quality of life was assessed with the use of the SF-36 Health Status Questionnaire. Post-traumatic stress disorder was measured with a previously validated instrument (the Post-Traumatic Stress Syndrome 10-Questions Inventory), and 20 different aspects of life satisfaction were quantified on a scale ranging from 0 to 10. For measurements of health-related quality of life and post-traumatic stress disorder, age- and gender-comparable healthy individuals, as well as patients with cardiovascular diseases, served as control groups.

RESULTS

Patients who had cardiac surgery described high life satisfaction summary scores (156 of a maximum of 200 points) and only small impairments in physical and mental SF-36 summary scores when compared with healthy control groups (median reduction 7.15, P <.05). Patients with evidence of post-traumatic stress disorder (n = 15) reported the lowest SF-36 mental health summary scores when compared with patients without stress disorder (38.3 vs 48.4, P =.004) and rated their life satisfaction lower (121.5 vs 162.0, P =.002).

CONCLUSIONS

Patients who have had cardiac surgery demonstrate a high life satisfaction with an acceptable degree of physical and mental health-related quality of life. Impairments in psychosocial function and life satisfaction were found in a subgroup of patients with evidence of post-traumatic stress disorder.

Beat-to-beat measurement of cardiac output by intravascular pulse contour analysis: a prospective criterion standard study in patients after cardiac surgery

OBJECTIVE

To evaluate the accuracy of a new pulse contour method of measuring cardiac output in critically ill patients.

DESIGN

A prospective criterion standard study.

SETTING

Cardiac surgery intensive care unit in a university hospital.

PARTICIPANTS

Nineteen cardiac surgery patients requiring intensive care treatment with pulmonary artery catheters after surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The pulse contour cardiac output monitor uses transpulmonary bolus thermodilution measurements to calibrate the system. In each patient, the pulse contour cardiac output values were compared with conventional thermodilution. The method described by Bland and Altman and linear regression analysis were used for comparison. The mean difference (bias) +/- standard deviation of differences (precision) was 0.31 +/- 1.25 L/min for pulmonary bolus thermodilution cardiac output versus pulse contour cardiac output and 0.21 +/- 0.73 L/min for pulmonary bolus thermodilution cardiac output versus transpulmonary bolus thermodilution cardiac output. Linear regression (correlation) analyses were pulse contour cardiac output = 0.97 thermodilution + 0.53 (r = 0.88), and transpulmonary cardiac output = 0.87 thermodilution + 1.09 (r = 0.96). There was a small increase 60 minutes after recalibration but not a statistically significant difference between pulse contour cardiac output and pulmonary bolus thermodilution cardiac output (p = 0.52).

CONCLUSIONS

Bias and precision are acceptable, and the system provides results that agree with conventional thermodilution. This study demonstrates the clinical applicability of the pulse contour cardiac output monitoring system.

Neoadjuvant photodynamic therapy before curative resection of proximal bile duct carcinoma

BACKGROUND

Hilar bile duct carcinoma has an 80% probability of local recurrence after curative resection, which might be reduced if neoadjuvant photodynamic therapy is feasible. CASE AND TREATMENT: After intravenous injection of sodium porfimer we treated an adenocarcinoma of the proximal common bile duct (T2 N0 M0, Bismuth type II) in a 72-year-old man with red laser light (applied from the lumen at a dose 250 Joules/cm2), and the adjacent right and left hepatic and common bile duct at a dose of 125 Joules/cm2. After 23 days the tumor was completely resected (adenocarcinoma pT2 pNO; G2).

RESULTS

In the lumenal, 4-mm-thick layer the bile duct specimen exhibited complete tumor necrosis with pigmentation of photodegraded porfimer and no viable tumor cells, while in the outer layer of the wall (at 5-8-mm depth) viable cancer cell nests without degraded porfimer were seen. The bile duct tissue showed little damage. Eighteen months after surgery, neither tumor recurrence nor stricture formation was found at the pretreated bilioenteric anastomoses.

CONCLUSIONS

a) Photodynamic therapy with sodium porfimer seems to be confined to the superficial 4-mm layer of bile duct cancer. b) Neoadjuvant photodynamic therapy is feasible for hilar bile duct carcinoma.

Intermittent atrial level right-to-left shunt with temporary hypoxemia in a patient during support with a left ventricular assist device

We report a 56-year-old male patient developing hypoxemia after surgical replacement of infected valves of a left ventricular assist device (LVAD, Novacor) which had supported him during the previous 15 months. Contrast transesophageal echocardiography (TEE) revealed an atrial septal defect with intermittent right-to-left shunt across a patent foramen ovale. We postulate that the shunt detected in this patient occurred as a consequence of reduced pulmonary vascular compliance due to positive end-expiratory pressure (PEEP) and an increase of mean intrathoracic pressure. Furthermore, we hypothesize that synchronized LVAD operation exacerbates any potential right-to-left shunt due to the profound left ventricular unloading which occurs during LVAD support. In this first report of a right-to-left shunt from a previously unrecognized patent foramen ovale in a Novacor patient, the subsequent transient hypoxemia could be managed by avoiding PEEP of more than 3 mmHg, and mean airway pressure of more than 11 mmHg and by careful volume replacement in order to prevent the pump from completely emptying the left ventricle (LV) and the left atrium (LA). Thus, prior to every LVAD implantation a transesophageal contrast echocardiography with Valsalva maneuver should be performed to identify intracardiac right-to-left shunt.