Cost Analysis of Erythropoietic-Stimulating Therapy Dosing in Oncology Inpatients

Background:

Inpatient costs associated with different erythropoietic-stimulating therapy regimens have not been compared in an oncology setting.

Objective:

To conduct a cost analysis of different regimens of epoetin alfa (EPO) and darbepoetin alfa (DARB) in an inpatient oncology setting.

Methods:

A retrospective evaluation of oncology diagnosis-related group discharges during 2003, in 30 community hospitals, identified EPO treatment patterns. Wholesale acquisition costs were determined for patients who received EPO 40 000 units or more once weekly. Potential differences in costs were calculated using conversion ratios for an equivalent EPO dose 3 times weekly or DARB dose once weekly (EPO:DARB ratio 260:1, approximating DARB 150 μg once weekly). A sensitivity analysis was performed using an EPO:DARB ratio of 400:1, approximating DARB 100 μg once weekly (1.5 μg/kg).

Results:

Among the 1410 EPO doses administered (n = 677 pts.), a dose of 40000 units or more was used 44% of the time (n = 311 pts.), with dosing initiated on average 5.6 days after admission. For these 311 evaluable patients, switching from EPO 40 000 units once weekly to EPO 10 000 units 3 times weekly reduced per-patient and total drug acquisition costs by approximately 50% ($704 vs $359 and $218 938 vs $111 615, respectively). Relative to EPO once weekly, switching patients to DARB resulted in increased drug acquisition costs at the 260:1 conversion and lower costs at the 400:1 conversion. However, EPO 3 times weekly remained the least costly option by 44–63%. The cost-savings realized with EPO 10000 units 3 times weekly increased with longer duration of hospitalization.

Conclusions:

In an inpatient setting, use of EPO 10000 units 3 times weekly may minimize expenditures associated with treatment of cancer-related anemia using erythropoietic-stimulating therapies.

Right ventricular stroke volume variation: a tool to assess right ventricular volume responsiveness

BACKGROUND

So far, only left ventricular functional preload indices are used as a routine to assess volume responsiveness. Right ventricular (RV) functional preload indices have been described, but offer no continuous monitoring.

METHODS

Following ethical approval, a pressure-induced right ventricular failure (RVF) was induced with continuous infusion of a thromboxane-A2-analogue (U46619) in 15 anesthetized and ventilated pigs. Before and after increasing mean pulmonary artery pressure (MPAP) by 50%, right ventricular stroke volume variation (RVSVV) was assessed with an ultrasonic pulmonary artery flow probe. Measurements were repeated following volume depletion (- 300 mL) and stepwise retransfusion (200 mL of whole blood and 200 mL of a colloid solution).

RESULTS

A significant and systematic increase in RVSVV during induction of RVF was observed. Volume depletion led to an increase in RVSVV and re-transfusion led to a decrease in RVSVV. RVSVV was higher and a significant decrease in RVSVV was present in all animals experiencing an increase in CO by more than 5% during retransfusion.

CONCLUSION

RVSVV seems to reflect volume requirement of the right ventricle and it might prove a reliable parameter to assess volume responsiveness in RVF.

Mechanotransduction in the lungs

Mechanical ventilation may induce or aggravate lung injury, a phenomenon known as ventilator induced lung injury (VILI). On a macroscopic level, the effects of mechanical stress and strain on lung tissue are well described. Increased tidal volumes may lead to volutrauma, raised airway pressures may cause barotrauma and cyclic collapse and reopening of alveolar units contributes to atelectrauma. These three harmful mechanisms may lead to local and systemic pulmonary inflammatory response known as biotrauma. The purpose of this review was to elucidate fundamental mechanisms involved in the mechanotransduction of mechanical stimuli on a cellular level. Bronchial epithelial cells in the distal airways as well as alveolar epithelial cells are exposed to a variety of mechanical forces. These cells are involved in sensing and translation of mechanical stimuli into an inflammatory response. This review provides insight into current knowledge of cellular and molecular pathways during the process of pulmonary epithelial mechanosensation and mechanotransduction under different mechanical conditions. Since evidence for specific pathways is generally lacking in some fields of alveolar epithelial mechanotransduction, this article aims at providing reasonable hypothesis for further investigation.

Comparison of an automated respiratory systolic variation test with dynamic preload indicators to predict fluid responsiveness after major surgery

BACKGROUND

Predicting the response of cardiac output to volume administration remains an ongoing clinical challenge. The objective of our study was to compare the ability to predict volume responsiveness of various functional measures of cardiac preload. These included pulse pressure variation (PPV), stroke volume variation (SVV), and the recently launched automated respiratory systolic variation test (RSVT) in patients after major surgery.

METHODS

In this prospective study, 24 mechanically ventilated patients after major surgery were enrolled. Three consecutive volume loading steps consisting of 300 ml 6% hydroxyethylstarch 130/0.4 were performed and cardiac index (CI) was assessed by transpulmonary thermodilution. Volume responsiveness was considered as positive if CI increased by >10%.

RESULTS

In total 72 volume loading steps were analysed, of which 41 showed a positive volume response. Receiver operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) of 0.70 for PPV, 0.72 for SVV and 0.77 for RSVT. Areas under the curves of all variables did not differ significantly from each other (P>0.05). Suggested cut-off values were 9.9% for SVV, 10.1% for PPV, and 19.7° for RSVT as calculated by the Youden Index.

CONCLUSION

In predicting fluid responsiveness the new automated RSVT appears to be as accurate as established dynamic indicators of preload PPV and SVV in patients after major surgery. The automated RSVT is clinically easy to use and may be useful in guiding fluid therapy in ventilated patients.

[When the resting membrane potential becomes restless. Acute hyperkalemia in the perioperative phase]

Acute hyperkalemia is a life-threatening event and often occurs abruptly and without warning in the perioperative field. Risk factors are found on multiple levels as they can derive from a patients pre-existing condition or result from the surgical intervention or management of anesthesia. The therapy of hyperkalemia depends on the dimensions of electrolyte disturbance and a distinction can be made between therapeutic measures with a rapid and those with a long-term effect.

Successful weaning from extracorporal circulation using a pumpless extracorporal lung assist device in a patient with intraoperative hypercapnic lung failure during aortic valve replacement

We present a case of a 59-year-old female suffering from massive pulmonary edema with consecutive hypercapnic lung failure immediately following elective aortic valve replacement. Due to severe restrictive ventilation disorder, mechanical ventilation was inadequate. A pumpless lung assist (PECLA, iLA, Novalung®, Talheim, Germany)--a device for extracorporeal carbon dioxide elimination--was used for successful weaning from extracorporeal circulation (ECC). Within 24 hours respiratory function had normalized and the patient could be extubated. The further clinical course and follow-up at 3 months remained uneventful. This report describes the first intraoperative use of the PECLA device in a cardiac surgery patient to promote weaning from ECC.

[Co-editors and editors with Jewish origins of the first German journals for anaesthesia. Their fate under National Socialism and an attempt at a biographical appreciation]

The decision to publish the journals Der Schmerz and Narkose und Anaesthesie in 1928 was an important step towards the professionalization of anaesthesiology in Germany. The appearance of both journals, which for economic reasons merged into Schmerz - Narkose - Anaesthesie 1 year later, was initiated and vehemently supported by Jewish physicians. As editors and co-editors they were deeply involved with the editorial tasks of the journals for years from the early beginnings. When the National Socialistic Party took over the government in Germany many of the Jewish colleagues were forced to quit their editorial tasks, were eliminated and replaced by "Arians", they were persecuted and often arrested, forced to emigrate or decided to commit suicide due to inhumane personal circumstances. It is our intention to recall the biography and the terrible fate of the nearly unknown Jewish members of the editorial board of the first German anaesthesia journals. Moreover the biographic sketches promote a continuous discussion about the victims of an inhumane and barbarous ideology.

[Hemodynamic monitoring in one-lung ventilation]

One-lung ventilation causes adverse effects in pulmonary gas exchange and cardiocirculatory function. These adverse effects become particularly important for patients with underlying cardiopulmonary comorbidities. Alterations in pulmonary gas exchange have been investigated in several experimental and clinical trials. However, the hemodynamic consequences of one-lung ventilation are to a great extent unknown. Furthermore, no conclusive recommendations exist as to which kind of hemodynamic monitoring should be preferred in the situation of one-lung ventilation. Many issues regarding hemodynamic monitoring in one-lung ventilation remain unacknowledged. This article will review the current literature on hemodynamic monitoring in one-lung ventilation in order to derive recommendations for the application of hemodynamic monitoring in this specific peri-operative situation.

[General anesthesia in a patient with idiopathic orthostatic hypotension]

Idiopathic orthostatic hypotension (formerly known as Shy-Drager syndrome) is a multiple system atrophy, which is characterized by autonomic dysregulation. Providing perioperative hemodynamic stability during narcosis is therefore a particular challenge. The effects of general anesthesia on systemic vascular resistance and cardiac output in a patient with idiopathic orthostatic hypotension undergoing retropubic prostatectomy will be reported. In the case presented perioperative hemodynamic stability was achieved by aggressive volume therapy guided by global end-diastolic volume measurement and low-dose catecholamine therapy.

Influence of resident training on anaesthesia induction times

BACKGROUND

The effect of resident training in anaesthesiology on operating room (OR) economics is an issue of debate. Comparisons of anaesthesia process times between residents and consultants might be systematically skewed by interactions of anaesthesia technique and patient factors.

METHODS

In this prospective, observational study, we analysed anaesthesia process times in 599 cases performed for four different surgical services in a University hospital. The following factors were recorded for each case and used in multivariate analyses of process times: age, American Society of Anesthesiologist (ASA) status, BMI, emergency status, the educational level of the anaesthetist, and the anaesthesia technique.

RESULTS

In the non-adjusted comparison, only for two of seven anaesthetic techniques did resident cases have statistically significant longer induction times than consultant cases: general anaesthesia with placement of a central venous catheter [mean (sd) anaesthesia time for resident cases 38.2 (17.0) vs 22.3 (10.0) min for consultant cases, P=0.001] and general anaesthesia with a laryngeal mask airway [resident cases 11.3 (5.5) vs consultant cases 7.3 (5.0) min, P=0.003]. Anaesthetic technique had the greatest effect on anaesthesia induction time. Educational level of the anaesthetist and age of the patients had small, but significant effects.

CONCLUSIONS

Anaesthesia cases performed by residents have in some, but not in all, anaesthesia techniques increased process times compared with cases performed by consultants. This limits a possible negative impact on OR economics by resident education. Patient-based factors including ASA status, BMI, and emergency status have minimal or no effect on anaesthesia process times.

[Utilization rates and turnover times as indicators of OR workflow efficiency]

BACKGROUND

In many hospitals operating room (OR) utilization rates and turnover times (the time from the end of the previous surgical procedure to the beginning of the next) are used as indicators of OR workflow inefficiency. However, there have been no detailed studies to determine whether these indicators really provide an adequate picture of avoidable wasting of time in the OR.

METHODS

All relevant OR processes in a busy surgical suite with nine ORs were studied in detail over an 8-week period. Productive OR processes, and also reasons for unused times, were recorded by independent observers at 5-minute intervals; they were able to code for 10 different productive activities and 20 different reasons for unused time. Unused time in the OR, the OR utilization rate and the average perioperative turnover times were calculated for each day and a correlation analysis was performed.

RESULTS

In all, 3,501 OR hours and 790 surgical cases were studied. Productive processes accounted for 85.7% of the total OR time; the unused times were times with no scheduled cases (7.7%) and waiting times that arose for many different reasons (6.6%). Correlation analysis showed that there was no close correlation between waiting time and OR utilization (Spearman's r(s) 0.104 and r(s) 0.233). The correlations between total unused time (r(s) 0.718 and r(s) 0.745) and time with no scheduled cases (r(s) 0.706 and r(s) 0.620) and utilization were more robust, but for any given OR utilization rate the range of corresponding unused time or time without scheduled cases per day was considerable. The correlation between waiting time and perioperative turnover times was negligible (r(s) 0.185 and r(s) 0.175). When different definitions of utilization rate or perioperative turnover were used the results obtained were virtually identical.

CONCLUSIONS

Utilization rate and perioperative turnover time cannot be used as indicators of OR workflow efficiency, since they cannot identify the days during which avoidable waiting times occur. If the aim is to identify underused OR time and factors that hamper workflow efficiency, waiting times and times without scheduled cases need to be recorded directly and separately.

[Severe accidental hypothermia with cardiac arrest and extracorporeal rewarming. A case report of a 2-year-old child]

In patients with severe hypothermia and cardiac arrest, active rewarming is recommended by extracorporeal circulation with cardiopulmonary bypass. The current guidelines for resuscitation of the European Resuscitation Council now include the recommendation regarding patients with hypothermia remaining comatose after initial resuscitation to accomplish an active rewarming only up to a temperature of 32-34 degrees C and to maintain a mild hypothermia for 12-24 h. We report the case of a 2-year-old boy who suffered from severe hypothermia after falling into ice-cold water. On discovery cardiac arrest with asystole was present and the first measured temperature was 23.8 degrees C. Resuscitation led to restoration of spontaneous circulation. The patient was rewarmed by extracorporeal circulation with cardiopulmonary bypass to 33 degrees C then mild hypothermia was maintained for a further 12 h. On the third day after the accident the patient was extubated and after a further 9 days was discharged without any sequelae.

Akzidentelle Intoxikation durch unbeschriftete, generische transdermale Fentanylpflaster nach unzureichender Aufklärung

A somnolent 78-year-old male patient was brought to our emergency room by an ambulance with the presumptive diagnosis of stroke. Cranial computed tomography provided no evidence. On the intensive care unit of the neurosurgical department the patient was completely undressed. Covered by a sock and underwear the ICU staff found five unlabeled, transparent patches. Under the presumptive diagnosis of an opioid intoxication by a transdermal therapeutic system naloxone was infused over 3 days. The patient reported after rapidly awaking that fentanyl patches had been prescribed by his family practitioner the day before. The patient recovered without any sequelae.

[Public access defibrillation. Limited use by trained first responders and laymen]

As ventricular fibrillation is the most frequent initial heart rhythm causing out-of-hospital sudden cardiac arrest, defibrillation is of essential significance. Automated external defibrillators (AEDs) have been available for some years and as a result defibrillation can be carried out by individuals other than physicians and healthcare providers such as trained first responders and untrained lay rescuers. This so-called public access defibrillation nourished hope of progress in the treatment of sudden cardiac arrest. However, several limitations exist, such as low frequency of sudden cardiac arrest in public, rare use of publicly placed AEDs, low cost effectiveness, legal requirements and insufficient public willingness to help. Due to these restrictions of public access defibrillation other measures are more promising than the attempt at general distribution of AEDs. These measures are primary or secondary prophylaxis of sudden cardiac arrest, general knowledge of adequate activation of emergency medical services, implementation of first responder teams equipped with AEDs and particularly a better education in and application of the well-established principles of cardiopulmonary resuscitation.

Die neue Approbationsordnung für Ärzte

After the amendments to the regulations for the licence to practice medicine, the rating of the faculty of anesthesiology has clearly increased. In the following article a concept will be described whereby these standards were implemented at the University of Hamburg. The basic principle, especially the training in the practical proficiencies, is to achieve a continuous learning process from students through to specialists for anesthesiology.

Validation of pulse contour derived stroke volume variation during modifications of cardiac afterload

BACKGROUND

Left ventricular stroke volume variation (SVV) or its surrogates are useful tools to assess fluid responsiveness in mechanically ventilated patients. So far it is unknown, how changes in cardiac afterload affect SVV. Therefore, this study compared left ventricular SVV derived by pulse contour analysis with SVV measured using an ultrasonic flow probe and investigated the influence of cardiac afterload on left ventricular SVV.

METHODS

In 13 anaesthetized, mechanically ventilated pigs [31(SD 6) kg], we compared cardiac output (CO), stroke volume (SV), and SVV determined by pulse contour analysis and by an ultrasonic aortic flow signal (Bland-Altman analysis). After obtaining baseline measurements, cardiac afterload was increased using phenylephrine and decreased using adenosine (both continuously administered). Measurements were performed with a constant tidal volume (12 ml kg-1) without PEEP.

RESULTS

Neither increasing mean arterial pressure (MAP) [from 59 (7) to 116 (19)] nor decreasing MAP [from 63 (7) to 39 (4)] affected CO, SV, and SVV (both methods). Method comparison revealed a bias for SVV of 0.1% [standard error of the mean (SE) 0.8] at baseline, -1.2% (SE 0.8) during decreased and 4.0% (SE 0.7) during increased afterload, the latter being significantly different from the others (P<0.05). Thereby, pulse contour analysis tended to underestimate SVV during decreased afterload and to overestimate SVV during increased afterload. Limits of agreement were approximately 6% for all points of measurement.

CONCLUSIONS

Left ventricular SVV is not affected by changes in cardiac afterload. There is a good agreement of pulse contour with flow derived SVV. The agreement decreases, if afterload is extensively augmented.

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.

[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.

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.

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.

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.

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.

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.

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.

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.

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.