Christoph Hofer - Academia.edu (original) (raw)

Papers by Christoph Hofer

Hemodynamic monitoring has been part of the routine management of intensive care patients and hig... more Hemodynamic monitoring has been part of the routine management of intensive care patients and high risk surgical patients since the advent of the pulmonary artery catheter (PAC) more than thirty years ago. The growing availability of new less invasive devices over the past decades has now made it possible to monitor cardiac output (CO) more often in the operating room, as well as in new clinical settings such as the emergency department.

Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditional... more Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditionally performed using the pulmonary artery catheter. However, over the past 20 years, the value of pulmonary artery catheters has been challenged, with some authors suggesting that its use might be not only unnecessary but also harmful. New minimally invasive devices that measure cardiac output have become available. In this paper, we review their operative principles, limitations, and utility in an integrated approach that could potentially change patients' outcome. However, it is now clear that it is how the monitor is used (ie, the protocol or therapy associated with its use, or its lack thereof), and not the monitor per se, that should be questioned when a patient's outcome is being evaluated.

Perioperative Medicine, 2014

Background: The benefit of the post-anaesthesia care unit (PACU) with respect to an early detecti... more Background: The benefit of the post-anaesthesia care unit (PACU) with respect to an early detection of postoperative complications is beyond dispute. From a patient perspective, prevention and optimal management of pain, nausea and vomiting (PONV) are also of utmost importance. The aims of the study were therefore to prospectively measure pain and PONV on arrival to the PACU and before discharge and to determine the relationship of pain and PONV to the length of stay in the PACU. Methods: Postoperative pain was assessed over 30 months using a numeric rating scale on admittance to the PACU and before discharge; in addition, PONV was recorded. Statistical analysis was done considering gender, age, American Society of Anesthesiologists (ASA) classification, surgical speciality, anaesthesia technique, duration of anaesthesia, intensity of nursing and length of stay. Results: Data of 12,179 patients were available for analysis. The average length of stay in the PACU was 5.7 ± 5.9 h, whereas regular PACU patients stayed for 3.2 ± 1.9 h and more complex IMC patients stayed for 15.1 ± 6.0 h. On admittance, 27% of patients were in pain and the number decreased to 13% before discharge; 3% experienced PONV. Risk factors for increased pain determined by multivariate analysis were female gender; higher ASA classification; general, cardiac and orthopaedic surgery and prolonged case duration. In more complex IMC patients, pain scores were higher on arrival but dropped to similar levels before discharge compared to regular PACU patients. Female gender and postoperative pain were risk factors for postoperative vomiting. Pain and PONV on arrival correlated with length of stay in the PACU. Pain-or PONV-free patients stayed almost half of the time in the PACU compared to patients with severe pain or vomiting on arrival. Conclusions: The majority of PACU patients had good pain control, both on admittance and before discharge, and the overall incidence of PONV was low. Managing patients in the PACU could achieve a significant reduction of pain and PONV. The level of pain and presence of PONV on admittance to the PACU correlate with and act as predictors for increased length of PACU stay.

Hematology, 2014

The estimated incidence of congenital factor VII deficiency is 1:500 000. Severe FVII deficiency ... more The estimated incidence of congenital factor VII deficiency is 1:500 000. Severe FVII deficiency is associated with spontaneous bleeding such as intraarticular or intracranial haemorrhage. The risk of perioperative bleeding is high during cardiac surgery as a result of the exposure to extracorporeal circulation, systemic anticoagulation, loss of coagulation factors, and postoperative platelet malfunction. Effective treatment of pre-existing coagulopathy is crucial, as increased morbidity and mortality are associated with allogenic blood transfusions. We report a 67-year-old Caucasian male patient with severe congenital FVII deficiency, undergoing successful and uneventful elective mitral valve repair surgery, radiofrequency epicardial atrial fibrillation ablation, and exclusion of the left atrial appendage. He presented with severe symptomatic mitral valve regurgitation, moderate pulmonary artery hypertension, and paroxysmal atrial fibrillation; his left ventricular ejection fraction was 67%. Three years before surgery, during a routine assessment of a grade I renal failure, a spontaneous International Normalised Ratio of 4.1 was observed. He had no history of previous spontaneous bleeding. The diagnosis of a severe FVII deficiency, with an FVII activity below 2% (normal references values in City Hospital Triemli Zurich: 55-170%) was made.

Anesthesiology, 2007

Anesthetic gases modulate gene expression and provide organ protection. This study aimed at ident... more Anesthetic gases modulate gene expression and provide organ protection. This study aimed at identifying myocardial transcriptional phenotypes to predict cardiovascular biomarkers and function in patients undergoing off-pump coronary artery bypass graft surgery. In a prospective randomized trial, patients undergoing elective off-pump coronary artery bypass graft surgery were allocated to receive either the anesthetic gas sevoflurane (n = 10) or the intravenous anesthetic propofol (n = 10). Blood samples were collected perioperatively to determine cardiac troponin T, N-terminal pro-brain natriuretic peptide, and pregnancy-associated plasma protein A. Cardiac function was measured with transesophageal echocardiography and pulmonary artery thermodilution. Atrial biopsies were collected at the beginning and end of bypass surgery to determine gene expression profiles. N-terminal pro-brain natriuretic peptide and pregnancy-associated plasma protein A blood levels were decreased with sevoflurane treatment. Echocardiography showed preserved postoperative cardiac function in sevoflurane patients, which paralleled higher cardiac index measurements. N-terminal pro-brain natriuretic peptide release was predicted by sevoflurane-induced transcriptional reduction in fatty acid oxidation, whereas changes in cardiac index were predicted by preoperative gene activity of the peroxisome proliferator-activated receptor gamma coactivator-1alpha pathway. Sevoflurane-mediated attenuation of transcripts involved in DNA-damage signaling and activation of the granulocyte colony-stimulating factor survival pathway predicted improved postoperative cardiac index and diastolic heart function, respectively. Anesthetic-induced and constitutive gene regulatory control of myocardial substrate metabolism predicts postoperative cardiac function in patients undergoing off-pump coronary artery bypass graft surgery. The authors' analysis further points to novel cardiac survival pathways as potential therapeutic targets in perioperative cardioprotection.

Wir berichten von einer 72-jährigen Patientin mit arterieller Hypertonie ohne vorbestehende Reizl... more Wir berichten von einer 72-jährigen Patientin mit arterieller Hypertonie ohne vorbestehende Reizleitungsstörung, bei der während einer Spinal-und einer später durchgeführten Allgemeinanästhesie jeweils ein AV-Block III aufgetreten ist.Die Patientin konnte erfolgreich medikamentös und mit einem intermittierenden transkutanen Herzschrittmacher behandelt werden.In beiden Situationen ging der Blockierung ein Abfall des arteriellen Blutdrucks um mehr als 40% voraus.Nach Nachweis einer nur diskreten hypertensiven Herzkrankheit wurde eine relative Ischämie des AV-Knotens als mögliche Ätiologie vermutet.Daher wurde bei der 3.Operation in Allgemeinanästhesie der Blutdruck invasiv monitorisiert und der arterielle Mitteldruck mit Katecholaminen gestützt.Darunter traten keine weiteren Reizleitungsstörungen auf.Dieser Fall zeigt, dass bei älteren Patienten mit einem intraoperativ aufgetretenen AV-Block -ohne vorbestehende Reizleitungsstörung und mit einer nur wenig aussagekräftigen kardiologischen Abklärung -erneut mit einer höher gradigen AV-Blockierung bei nachfolgenden Anästhesien -unabhängig vom gewählten Verfahren -zu rechnen ist.Ein transkutaner Herzschrittmacher muss perioperativ jederzeit zur Verfügung stehen.Therapeutisches Ziel ist die Vermeidung einer Hypotonie, um den koronaren Perfusionsdruck aufrechtzuerhalten.Der Einsatz eines invasiven Blutdruckmonitorings ist zu empfehlen.

Journal of Thoracic and Cardiovascular Surgery, 2003

malleable blades were easily adjusted to accommodate variability in left atrial size and orientat... more malleable blades were easily adjusted to accommodate variability in left atrial size and orientation of the pulmonary veins.

Journal of Cardiothoracic and Vascular Anesthesia, 2010

Objectives: Arterial pressure waveform analysis is a less invasive alternative to the pulmonary a... more Objectives: Arterial pressure waveform analysis is a less invasive alternative to the pulmonary artery catheter for continuous cardiac output (CO) measurement. Uncalibrated and calibrated systems are actually available (ie, the FloTrac/Vigileo system [Edwards Lifesciences, Irvine, CA] and the PiCCOplus system [Pulsion Medical Systems, Munich, Germany]). According to the FloTrac/Vigileo manufacturer, reliable measurements can be performed using any existing arterial catheter. The aim of this study was to evaluate CO determined by the FloTrac/ Vigileo system using a radial (FCO radial ) and femoral arterial catheter (FCO femoral ) as well as the PiCCOplus system (PCO). Intermittent pulmonary artery thermodilution (ICO) was used as primary reference technique.

Current Opinion in Anaesthesiology, 2014

Advanced hemodynamic monitoring is indispensable for adequate management of patients undergoing m... more Advanced hemodynamic monitoring is indispensable for adequate management of patients undergoing major surgery. This article will summarize minimally invasive hemodynamic monitoring technologies and their potential use in thoracic anesthesia. According to their inherent principle, currently available technologies can be classified into four groups: bioimpedance and bioreactance, applied Fick's principle, pulse wave analysis and Doppler. All devices measure stroke volume and cardiac output. Functional hemodynamic variables and volumetric parameters have been integrated in some devices. Two major indications can be identified: the 'hemodynamically unstable' patient and the patient 'at risk' for hemodynamic instability. Although there is evidence for the first indication, pre-emptive hemodynamic therapy or perioperative hemodynamic optimization for the patient 'at risk' is still an issue of ongoing debate. There is a growing body of evidence that this approach can positively influence patients' outcome with less postoperative complications in selected patient groups. Many different minimally invasive hemodynamic monitoring devices have been developed and clinically introduced in the last years. They offer the advantage of being less invasive and easier to use. However, these techniques have several limitations and data are scarce in patients undergoing thoracic anesthesia, preventing their widespread use so far.

Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditional... more Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditionally performed using the pulmonary artery catheter. However, over the past 20 years, the value of pulmonary artery catheters has been challenged, with some authors suggesting that its use might be not only unnecessary but also harmful. New minimally invasive devices that measure cardiac output have become available. In this paper, we review their operative principles, limitations, and utility in an integrated approach that could potentially change patients' outcome. However, it is now clear that it is how the monitor is used (ie, the protocol or therapy associated with its use, or its lack thereof), and not the monitor per se, that should be questioned when a patient's outcome is being evaluated.

Journal of Cardiothoracic and Vascular Anesthesia, 2008

The aim of this study was to compare the following approaches to assess left ventricular preload ... more The aim of this study was to compare the following approaches to assess left ventricular preload by transesophageal echocardiography (TEE): left ventricular end-diastolic volume index (LVEDVI) determined by using the method of disc summation (LVEDVI(Md)) and left ventricular end-diastolic area index (LVEDAI) were compared with LVEDVI assessed by the modified Simpson formula (LVEDVI(Si)). Global end-diastolic volume index (GEDVI) and stroke volume index (SVI) measured by the PiCCO(plus) system (Pulsion Medical Systems, Munich, Germany) were used as TEE-independent reference variables. Prospective observational study. Community hospital. Twenty-two patients undergoing elective cardiac surgery. After the induction of anesthesia, hemodynamic assessment by TEE and the PiCCO(plus) system was made 20 (T(1)) and 10 minutes (T(2)) before and 10 (T(3)) and 20 minutes (T(4)) after a fluid trial. At each time point, LVEDVI(Md), LVEDAI, LVEDVI(Si), GEDVI, and SVI were determined. The fluid trial resulted in a significant increase of all preload variables measured at T(3). At T(4), all preload variables but LVEDVI(Md) showed a significant decrease. The mean bias +/- 2 SD for percent changes (Delta) of LVEDVI(Md) - DeltaLVEDVI(Si) was 1.5% +/- 59.0% and for DeltaLVEDAI - Delta LVEDVI(Si) 0.9% +/- 23.6%. The correlation between LVEDVI(Md) and LVEDVI(Si) was significantly weaker than between LVEDAI and LVEDVI(Si) (p < 0.001). Comparing TEE measurements with GEDVI and SVI, strong correlations were observed for LVEDAI and LVEDVI(Si) only. The method of disc summation cannot be recommended for preload assessment during a fluid challenge in cardiac surgery patients. By contrast, single-plane area measurements provided reliable information when compared with the application of the modified Simpson formula.

Critical Care, 2011

Introduction: Dynamic predictors of fluid responsiveness have made automated management of fluid ... more Introduction: Dynamic predictors of fluid responsiveness have made automated management of fluid resuscitation more practical. We present initial simulation data for a novel closed-loop fluid-management algorithm (LIR, Learning Intravenous Resuscitator). Methods: The performance of the closed-loop algorithm was tested in three phases by using a patient simulator including a pulse-pressure variation output. In the first phase, LIR was tested in three different hemorrhage scenarios and compared with no management. In the second phase, we compared LIR with 20 practicing anesthesiologists for the management of a simulated hemorrhage scenario. In the third phase, LIR was tested under conditions of noise and artifact in the dynamic predictor.

Hemodynamic monitoring has been part of the routine management of intensive care patients and hig... more Hemodynamic monitoring has been part of the routine management of intensive care patients and high risk surgical patients since the advent of the pulmonary artery catheter (PAC) more than thirty years ago. The growing availability of new less invasive devices over the past decades has now made it possible to monitor cardiac output (CO) more often in the operating room, as well as in new clinical settings such as the emergency department.

Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditional... more Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditionally performed using the pulmonary artery catheter. However, over the past 20 years, the value of pulmonary artery catheters has been challenged, with some authors suggesting that its use might be not only unnecessary but also harmful. New minimally invasive devices that measure cardiac output have become available. In this paper, we review their operative principles, limitations, and utility in an integrated approach that could potentially change patients' outcome. However, it is now clear that it is how the monitor is used (ie, the protocol or therapy associated with its use, or its lack thereof), and not the monitor per se, that should be questioned when a patient's outcome is being evaluated.

Perioperative Medicine, 2014

Background: The benefit of the post-anaesthesia care unit (PACU) with respect to an early detecti... more Background: The benefit of the post-anaesthesia care unit (PACU) with respect to an early detection of postoperative complications is beyond dispute. From a patient perspective, prevention and optimal management of pain, nausea and vomiting (PONV) are also of utmost importance. The aims of the study were therefore to prospectively measure pain and PONV on arrival to the PACU and before discharge and to determine the relationship of pain and PONV to the length of stay in the PACU. Methods: Postoperative pain was assessed over 30 months using a numeric rating scale on admittance to the PACU and before discharge; in addition, PONV was recorded. Statistical analysis was done considering gender, age, American Society of Anesthesiologists (ASA) classification, surgical speciality, anaesthesia technique, duration of anaesthesia, intensity of nursing and length of stay. Results: Data of 12,179 patients were available for analysis. The average length of stay in the PACU was 5.7 ± 5.9 h, whereas regular PACU patients stayed for 3.2 ± 1.9 h and more complex IMC patients stayed for 15.1 ± 6.0 h. On admittance, 27% of patients were in pain and the number decreased to 13% before discharge; 3% experienced PONV. Risk factors for increased pain determined by multivariate analysis were female gender; higher ASA classification; general, cardiac and orthopaedic surgery and prolonged case duration. In more complex IMC patients, pain scores were higher on arrival but dropped to similar levels before discharge compared to regular PACU patients. Female gender and postoperative pain were risk factors for postoperative vomiting. Pain and PONV on arrival correlated with length of stay in the PACU. Pain-or PONV-free patients stayed almost half of the time in the PACU compared to patients with severe pain or vomiting on arrival. Conclusions: The majority of PACU patients had good pain control, both on admittance and before discharge, and the overall incidence of PONV was low. Managing patients in the PACU could achieve a significant reduction of pain and PONV. The level of pain and presence of PONV on admittance to the PACU correlate with and act as predictors for increased length of PACU stay.

Hematology, 2014

The estimated incidence of congenital factor VII deficiency is 1:500 000. Severe FVII deficiency ... more The estimated incidence of congenital factor VII deficiency is 1:500 000. Severe FVII deficiency is associated with spontaneous bleeding such as intraarticular or intracranial haemorrhage. The risk of perioperative bleeding is high during cardiac surgery as a result of the exposure to extracorporeal circulation, systemic anticoagulation, loss of coagulation factors, and postoperative platelet malfunction. Effective treatment of pre-existing coagulopathy is crucial, as increased morbidity and mortality are associated with allogenic blood transfusions. We report a 67-year-old Caucasian male patient with severe congenital FVII deficiency, undergoing successful and uneventful elective mitral valve repair surgery, radiofrequency epicardial atrial fibrillation ablation, and exclusion of the left atrial appendage. He presented with severe symptomatic mitral valve regurgitation, moderate pulmonary artery hypertension, and paroxysmal atrial fibrillation; his left ventricular ejection fraction was 67%. Three years before surgery, during a routine assessment of a grade I renal failure, a spontaneous International Normalised Ratio of 4.1 was observed. He had no history of previous spontaneous bleeding. The diagnosis of a severe FVII deficiency, with an FVII activity below 2% (normal references values in City Hospital Triemli Zurich: 55-170%) was made.

Anesthesiology, 2007

Anesthetic gases modulate gene expression and provide organ protection. This study aimed at ident... more Anesthetic gases modulate gene expression and provide organ protection. This study aimed at identifying myocardial transcriptional phenotypes to predict cardiovascular biomarkers and function in patients undergoing off-pump coronary artery bypass graft surgery. In a prospective randomized trial, patients undergoing elective off-pump coronary artery bypass graft surgery were allocated to receive either the anesthetic gas sevoflurane (n = 10) or the intravenous anesthetic propofol (n = 10). Blood samples were collected perioperatively to determine cardiac troponin T, N-terminal pro-brain natriuretic peptide, and pregnancy-associated plasma protein A. Cardiac function was measured with transesophageal echocardiography and pulmonary artery thermodilution. Atrial biopsies were collected at the beginning and end of bypass surgery to determine gene expression profiles. N-terminal pro-brain natriuretic peptide and pregnancy-associated plasma protein A blood levels were decreased with sevoflurane treatment. Echocardiography showed preserved postoperative cardiac function in sevoflurane patients, which paralleled higher cardiac index measurements. N-terminal pro-brain natriuretic peptide release was predicted by sevoflurane-induced transcriptional reduction in fatty acid oxidation, whereas changes in cardiac index were predicted by preoperative gene activity of the peroxisome proliferator-activated receptor gamma coactivator-1alpha pathway. Sevoflurane-mediated attenuation of transcripts involved in DNA-damage signaling and activation of the granulocyte colony-stimulating factor survival pathway predicted improved postoperative cardiac index and diastolic heart function, respectively. Anesthetic-induced and constitutive gene regulatory control of myocardial substrate metabolism predicts postoperative cardiac function in patients undergoing off-pump coronary artery bypass graft surgery. The authors' analysis further points to novel cardiac survival pathways as potential therapeutic targets in perioperative cardioprotection.

Wir berichten von einer 72-jährigen Patientin mit arterieller Hypertonie ohne vorbestehende Reizl... more Wir berichten von einer 72-jährigen Patientin mit arterieller Hypertonie ohne vorbestehende Reizleitungsstörung, bei der während einer Spinal-und einer später durchgeführten Allgemeinanästhesie jeweils ein AV-Block III aufgetreten ist.Die Patientin konnte erfolgreich medikamentös und mit einem intermittierenden transkutanen Herzschrittmacher behandelt werden.In beiden Situationen ging der Blockierung ein Abfall des arteriellen Blutdrucks um mehr als 40% voraus.Nach Nachweis einer nur diskreten hypertensiven Herzkrankheit wurde eine relative Ischämie des AV-Knotens als mögliche Ätiologie vermutet.Daher wurde bei der 3.Operation in Allgemeinanästhesie der Blutdruck invasiv monitorisiert und der arterielle Mitteldruck mit Katecholaminen gestützt.Darunter traten keine weiteren Reizleitungsstörungen auf.Dieser Fall zeigt, dass bei älteren Patienten mit einem intraoperativ aufgetretenen AV-Block -ohne vorbestehende Reizleitungsstörung und mit einer nur wenig aussagekräftigen kardiologischen Abklärung -erneut mit einer höher gradigen AV-Blockierung bei nachfolgenden Anästhesien -unabhängig vom gewählten Verfahren -zu rechnen ist.Ein transkutaner Herzschrittmacher muss perioperativ jederzeit zur Verfügung stehen.Therapeutisches Ziel ist die Vermeidung einer Hypotonie, um den koronaren Perfusionsdruck aufrechtzuerhalten.Der Einsatz eines invasiven Blutdruckmonitorings ist zu empfehlen.

Journal of Thoracic and Cardiovascular Surgery, 2003

malleable blades were easily adjusted to accommodate variability in left atrial size and orientat... more malleable blades were easily adjusted to accommodate variability in left atrial size and orientation of the pulmonary veins.

Journal of Cardiothoracic and Vascular Anesthesia, 2010

Objectives: Arterial pressure waveform analysis is a less invasive alternative to the pulmonary a... more Objectives: Arterial pressure waveform analysis is a less invasive alternative to the pulmonary artery catheter for continuous cardiac output (CO) measurement. Uncalibrated and calibrated systems are actually available (ie, the FloTrac/Vigileo system [Edwards Lifesciences, Irvine, CA] and the PiCCOplus system [Pulsion Medical Systems, Munich, Germany]). According to the FloTrac/Vigileo manufacturer, reliable measurements can be performed using any existing arterial catheter. The aim of this study was to evaluate CO determined by the FloTrac/ Vigileo system using a radial (FCO radial ) and femoral arterial catheter (FCO femoral ) as well as the PiCCOplus system (PCO). Intermittent pulmonary artery thermodilution (ICO) was used as primary reference technique.

Current Opinion in Anaesthesiology, 2014

Advanced hemodynamic monitoring is indispensable for adequate management of patients undergoing m... more Advanced hemodynamic monitoring is indispensable for adequate management of patients undergoing major surgery. This article will summarize minimally invasive hemodynamic monitoring technologies and their potential use in thoracic anesthesia. According to their inherent principle, currently available technologies can be classified into four groups: bioimpedance and bioreactance, applied Fick's principle, pulse wave analysis and Doppler. All devices measure stroke volume and cardiac output. Functional hemodynamic variables and volumetric parameters have been integrated in some devices. Two major indications can be identified: the 'hemodynamically unstable' patient and the patient 'at risk' for hemodynamic instability. Although there is evidence for the first indication, pre-emptive hemodynamic therapy or perioperative hemodynamic optimization for the patient 'at risk' is still an issue of ongoing debate. There is a growing body of evidence that this approach can positively influence patients' outcome with less postoperative complications in selected patient groups. Many different minimally invasive hemodynamic monitoring devices have been developed and clinically introduced in the last years. They offer the advantage of being less invasive and easier to use. However, these techniques have several limitations and data are scarce in patients undergoing thoracic anesthesia, preventing their widespread use so far.

Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditional... more Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditionally performed using the pulmonary artery catheter. However, over the past 20 years, the value of pulmonary artery catheters has been challenged, with some authors suggesting that its use might be not only unnecessary but also harmful. New minimally invasive devices that measure cardiac output have become available. In this paper, we review their operative principles, limitations, and utility in an integrated approach that could potentially change patients' outcome. However, it is now clear that it is how the monitor is used (ie, the protocol or therapy associated with its use, or its lack thereof), and not the monitor per se, that should be questioned when a patient's outcome is being evaluated.

Journal of Cardiothoracic and Vascular Anesthesia, 2008

The aim of this study was to compare the following approaches to assess left ventricular preload ... more The aim of this study was to compare the following approaches to assess left ventricular preload by transesophageal echocardiography (TEE): left ventricular end-diastolic volume index (LVEDVI) determined by using the method of disc summation (LVEDVI(Md)) and left ventricular end-diastolic area index (LVEDAI) were compared with LVEDVI assessed by the modified Simpson formula (LVEDVI(Si)). Global end-diastolic volume index (GEDVI) and stroke volume index (SVI) measured by the PiCCO(plus) system (Pulsion Medical Systems, Munich, Germany) were used as TEE-independent reference variables. Prospective observational study. Community hospital. Twenty-two patients undergoing elective cardiac surgery. After the induction of anesthesia, hemodynamic assessment by TEE and the PiCCO(plus) system was made 20 (T(1)) and 10 minutes (T(2)) before and 10 (T(3)) and 20 minutes (T(4)) after a fluid trial. At each time point, LVEDVI(Md), LVEDAI, LVEDVI(Si), GEDVI, and SVI were determined. The fluid trial resulted in a significant increase of all preload variables measured at T(3). At T(4), all preload variables but LVEDVI(Md) showed a significant decrease. The mean bias +/- 2 SD for percent changes (Delta) of LVEDVI(Md) - DeltaLVEDVI(Si) was 1.5% +/- 59.0% and for DeltaLVEDAI - Delta LVEDVI(Si) 0.9% +/- 23.6%. The correlation between LVEDVI(Md) and LVEDVI(Si) was significantly weaker than between LVEDAI and LVEDVI(Si) (p < 0.001). Comparing TEE measurements with GEDVI and SVI, strong correlations were observed for LVEDAI and LVEDVI(Si) only. The method of disc summation cannot be recommended for preload assessment during a fluid challenge in cardiac surgery patients. By contrast, single-plane area measurements provided reliable information when compared with the application of the modified Simpson formula.

Critical Care, 2011

Introduction: Dynamic predictors of fluid responsiveness have made automated management of fluid ... more Introduction: Dynamic predictors of fluid responsiveness have made automated management of fluid resuscitation more practical. We present initial simulation data for a novel closed-loop fluid-management algorithm (LIR, Learning Intravenous Resuscitator). Methods: The performance of the closed-loop algorithm was tested in three phases by using a patient simulator including a pulse-pressure variation output. In the first phase, LIR was tested in three different hemorrhage scenarios and compared with no management. In the second phase, we compared LIR with 20 practicing anesthesiologists for the management of a simulated hemorrhage scenario. In the third phase, LIR was tested under conditions of noise and artifact in the dynamic predictor.