Virtual reality as a teaching method for resuscitation training in undergraduate first year medical students: a randomized controlled trial.

BACKGROUND: Virtual reality is an innovative technology for medical education associated with high empirical realism. Therefore, this study compares a conventional cardiopulmonary resuscitation (CPR) training with a Virtual Reality (VR) training aiming to demonstrate: (a) non-inferiority of the VR intervention in respect of no flow time and (b) superiority in respect of subjective learning gain. METHODS: In this controlled randomized study first year, undergraduate students were allocated in the intervention group and the control group. Fifty-six participants were randomized to the intervention group and 104 participants to the control group. The intervention group received an individual 35-min VR Basic Life Support (BLS) course and a basic skill training. The control group took part in a "classic" BLS-course with a seminar and a basic skill training. The groups were compared in respect of no flow time in a final 3-min BLS examination (primary outcome) and their learning gain (secondary outcome) assessed with a comparative self-assessment (CSA) using a questionnaire at the beginning and the end of the course. Data analysis was performed with a general linear fixed effects model. RESULTS: The no flow time was significantly shorter in the control group (Mean values: control group 82 s vs. intervention group 93 s; p = 0.000). In the CSA participants of the intervention group had a higher learning gain in 6 out of 11 items of the questionnaire (p < 0.05). CONCLUSION: A "classic" BLS-course with a seminar and training seems superior to VR in teaching technical skills. However, overall learning gain was higher with VR. Future BLS course-formats should consider the integration of VR technique into the classic CPR training or vice versa, to use the advantage of both teaching techniques.

Correlation of medical students' situational motivation and performance of non-technical skills during simulation-based emergency training.

BACKGROUND: Non-technical skills (NTS) are an indispensable element of emergency care and need to be prevalent alongside with good technical skills. Though, questions of how to teach (instructional design) and improve NTS effectively remain unresolved. One adjustment screw to enhance performance of NTS, which is detached from instructional designs and learning efforts might be motivation. Theoretical models and observational studies suggest that high levels of intrinsic (situational) motivation result in better performance and better learning. Therefore, this study analyzed the influence of motivation on performance of NTS, by exploring if high levels of intrinsic motivation lead to better performance of NTS in medical students. METHODS: In this prospective cross-sectional cohort study, the authors assessed the correlation of situational motivation and performance of NTS within a cohort of 449 undergraduates in their 1st to 4th year of medical studies, in a total of 101 emergency simulation trainings. Situational motivation was measured with the validated Situational Motivation Scale (SIMS), which was completed by every undergraduate directly before each simulation training. The NTS were evaluated with the Anesthesiology Students´ Non-Technical skills (AS-NTS) rating tool, a validated taxonomy, especially developed to rate NTS of undergraduates. RESULTS: Student situational motivation was weakly correlated with their performance of NTS in simulation-based emergency trainings. CONCLUSION: Although motivation has been emphasized as a determining factor, enhancing performance in different fields and in medicine in particular, in our study, student situational motivation was independent from their performance of NTS in simulation-based emergency trainings (SBET).

Establishment of an enhanced recovery after surgery protocol in minimally invasive heart valve surgery.

Protocols for "Enhanced recovery after surgery (ERAS)" are on the rise in different surgical disciplines and represent one of the most important recent advancements in perioperative medical care. In cardiac surgery, only few ERAS protocols have been described in the past. At University Heart Center Hamburg, Germany, we invented an ERAS protocol for patients undergoing minimally invasive cardiac valve surgery. In this retrospective single center study, we aimed to describe the implementation of our ERAS program and to evaluate the results of the first 50 consecutive patients. Our ERAS protocol was developed according to a modified Kern cycle by an expert group, literature search, protocol creation and pilot implementation in the clinical practice. Data of the first 50 consecutive patients undergoing minimally invasive cardiac valve surgery were analysed retrospectively. The key features of our multidisciplinary ERAS protocol are physiotherapeutic prehabilitation, minimally invasive valve surgery techniques, modified cardiopulmonary bypass management, fast-track anaesthesia with on- table extubation and early mobilisation. A total of 50 consecutive patients (mean age of 51.9±11.9 years, mean STS score of 0.6±0.3) underwent minimally-invasive mitral or aortic valve surgery. The adherence to the ERAS protocol was high and neither protocol related complications nor in-hospital mortality occurred. 12% of the patients developed postoperative atrial fibrillation, postoperative delirium emerged in two patients and reintubation was required in one patient. Intensive care unit stay was 14.0±7.4 hours and total hospital stay 6.2±2.9 days. Our ERAS protocol is feasible and safe in minimally-invasive cardiac surgery setting and has a clear potential to improve patients outcome.

Patient safety in undergraduate medical education: Implementation of the topic in the anaesthesiology core curriculum at the University Medical Center Hamburg-Eppendorf.

Introduction: The focus of public attention and health policy is increasingly being drawn to patient safety. According to studies, more than 30,000 patients die each year as a result of medical errors. To date, learning objectives such as patient safety have not played a role in the core curriculum for medical education in Germany. The National Competence-Based Catalogue of Learning Objectives for Undergraduate Medical Education contains a total of 13 learning objectives relating to this subject. Methods: In a descriptive study, learning content was implemented within the "Operative Medicine" study block offered by the Faculty of Medicine at Universität Hamburg. The definition and occurrence of errors as well as strategies for dealing with and avoiding errors were set as the learning objectives for an interactive lecture, problem-based learning (PBL) case as well as the bedside teaching on anaesthesiology. Students were able to evaluate the lecture directly. During the simulator session on anaesthesia, the safety-relevant information that students requested from patients was compared with the questions asked by a control group in the previous trimester. Results: The topic of patient safety could be integrated into the "Operative Medicine" curriculum through a number of minor changes to classes. The accounts of personal experiences and importance assigned to the subject were considered positive, while content perceived as redundant was criticised. In the simulator, the students appeared to request more comprehensive preoperative safety-relevant information than the control group. Conclusion: The subject's relevance, positive feedback and trend towards a change in behaviour in the simulator lead the authors to deem introduction of the topic of patient safety a success.

Risk of spinal cord ischemia after fenestrated or branched endovascular repair of complex aortic aneurysms.

OBJECTIVE: The aim of our study was to analyze the incidence of spinal cord ischemia (SCI) in patients presenting with complex aortic aneurysms treated with endovascular aneurysm repair (EVAR) and to identify risk factors associated with this complication. METHODS: A retrospective study was undertaken of prospectively collected data including patients presenting with complex aortic aneurysm (pararenal abdominal aortic aneurysm and thoracoabdominal aortic aneurysm) treated with fenestrated EVAR (F-EVAR) or branched EVAR (B-EVAR). The primary end point was the incidence of SCI and the assessment of any associated factors. RESULTS: Between January 2011 and August 2017, a total of 243 patients (mean aneurysm diameter, 65.2 ± 15.3 mm; mean age, 72.4 ± 7.5 years; 73% male) were treated with F-EVAR or B-EVAR. Asymptomatic patients were treated in 73% of the cases (177/243, in contrast to 27% urgent), and 52% (126/243) were treated for thoracoabdominal aortic aneurysm (in contrast to 48% for pararenal abdominal aortic aneurysm). F-EVAR (mean number of fenestrations, 3.3/case) and B-EVAR (mean number of branches, 3.7/case) were undertaken in 67% (164/243) and 33% (79/243), respectively. The total incidence of SCI was 17.7% [43/243; paraplegia in 4% (10/243) and paraparesis in 13.7% (33/243)]. Most of the patients with SCI presented with immediate postoperative symptoms (72% [31/43]). A spinal drain was preoperatively placed in 53% (130/243) and was associated with the prevention of SCI (SCI with spinal drainage, 12% [16/130]; SCI without spinal drainage, 24% [27/113]; P = .018). The 30-day mortality rate was 9% (21/243). After multiple logistic regression analysis, SCI was associated with preoperative renal function (SCI with preoperative glomerular filtration rate <60 mL/min/1.73 m2: odds ratio [OR], 2.43; 95% confidence interval [CI], 1.18-4.99; P = .016) and the number of vertebral segments covered (SCI with higher position of proximal stent in terms of vertebra: OR, 1.2; 95% CI, 1.1-1.3; P = .000). A similar outcome was derived when the height of the proximal end of the stent graft was replaced by the total length of aortic coverage (SCI with preoperative glomerular filtration rate <60 mL/min/1.73 m2: OR, 2.36 [95% CI, 1.11-5.00; P = .025]; SCI with longer length of aortic coverage: OR, 1.01 [95% CI, 1.003-1.009; P = .000]). CONCLUSIONS: The majority of SCI incidence after F-EVAR or B-EVAR of complex aortic aneurysms is manifested immediately postoperatively. The use of preoperative spinal drainage may prevent SCI. Patients with GRF <60 mL/min/1.73 m2 and with longer aortic stent graft coverage are at higher risk of SCI.

Hemadsorption during cardiopulmonary bypass reduces interleukin 8 and tumor necrosis factor α serum levels in cardiac surgery: a randomized controlled trial.

BACKGROUND: Surgical trauma and cardiopulmonary bypass (CPB) are associated with the liberation of pro-inflammatory cytokines. With hemadsorption (Cytosorb®) during CPB, pro-inflammatory cytokines may be reduced and the inflammatory response may be decreased. METHODS: In this prospective, randomized single center study, serum cytokine levels of interleukin 8 (Il-8), interleukin 6 (Il-6) and tumor-necrosis-factor α (TNFα) were assessed in elective on-pump cardiac surgery patients with hemadsorption on CPB (study group [SG], N.=20) and without (control group [CG], N.=20). Cytokine levels were assessed prior to CPB, at the end of CPB, and 6 hours (h) and 24 h after the end of CPB, together with a hemodynamic assessment. Cardiac-Index (CI) was assessed with transcardiopulmonary thermodilution. RESULTS: For Il-8, significantly lower serum levels were observed in the SG compared to the CG at the end of CPB (P=0.008). In the SG, TNFα levels were also below those in the CG at both the end of and 6h after CPB (P=0.034). After 24 hours, TNFα levels were at baseline in both groups. No significant differences were found for Il-6. The CI was significantly higher in the SG at the end of CPB (P=0.025). However, there was no difference between both groups 6 h after CPB. CONCLUSIONS: This prospective study shows a significant reduction in pro-inflammatory cytokine levels of Il-8 and TNFα with hemadsorption in on-pump cardiac surgery whilst also demonstrating safety in its applications. However, the differences in cytokine levels and CI between patients treated with hemadsorption and those without were minor and of short duration.

Reliability of transcardiopulmonary thermodilution cardiac output measurement in experimental aortic valve insufficiency.

BACKGROUND: Monitoring cardiac output (CO) is important to optimize hemodynamic function in critically ill patients. The prevalence of aortic valve insufficiency (AI) is rising in the aging population. However, reliability of CO monitoring techniques in AI is unknown. The aim of this study was to investigate the impact of AI on accuracy, precision, and trending ability of transcardiopulmonary thermodilution-derived COTCPTD in comparison with pulmonary artery catheter thermodilution COPAC. METHODS: Sixteen anesthetized domestic pigs were subjected to serial simultaneous measurements of COPAC and COTCPTD. In a novel experimental model, AI was induced by retraction of an expanded Dormia basket in the aortic valve annulus. The Dormia basket was delivered via a Judkins catheter guided by substernal epicardial echocardiography. High (HPC), moderate (MPC) and low cardiac preload conditions (LPC) were induced by fluid unloading (20 ml kg-1 blood withdrawal) and loading (subsequent retransfusion of the shed blood and additional infusion of 20 ml kg-1 hydroxyethyl starch). Within each preload condition CO was measured before and after the onset of AI. For statistical analysis, we used a mixed model analysis of variance, Bland-Altman analysis, the percentage error and concordance analysis. RESULTS: Experimental AI had a mean regurgitant volume of 33.6 ± 12.0 ml and regurgitant fraction of 42.9 ± 12.6%. The percentage error between COTCPTD and COPAC during competent valve function and after induction of substantial AI was: HPC 17.7% vs. 20.0%, MPC 20.5% vs. 26.1%, LPC 26.5% vs. 28.1% (pooled data: 22.5% vs. 24.1%). The ability to trend CO-changes induced by fluid loading and unloading did not differ between baseline and AI (concordance rate 95.8% during both conditions). CONCLUSION: Despite substantial AI, transcardiopulmonary thermodilution reliably measured CO under various cardiac preload conditions with a good ability to trend CO changes in a porcine model. COTCPTD and COPAC were interchangeable in substantial AI.

Effect of an interactive cardiopulmonary resuscitation assist device with an automated external defibrillator synchronised with a ventilator on the CPR performance of emergency medical service staff: a randomised simulation study.

BACKGROUND: The present study evaluates whether the quality of advanced cardiac life support (ALS) is improved with an interactive prototype assist device. This device consists of an automated external defibrillator linked to a ventilator and provides synchronised visual and acoustic instructions for guidance through the ALS algorithm and assistance for face-mask ventilations. METHODS: We compared the cardiopulmonary resuscitation (CPR) quality of emergency medical system (EMS) staff members using the study device or standard equipment in a mannequin simulation study with a prospective, controlled, randomised cross-over study design. Main outcome was the effect of the study device compared to the standard equipment and the effect of the number of prior ALS trainings of the EMS staff on the CPR quality. Data were analysed using analyses of covariance (ANCOVA) and binary logistic regression, accounting for the study design. RESULTS: In 106 simulations of 56 two-person rescuer teams, the mean hands-off time was 24.5% with study equipment and 23.5% with standard equipment (Difference 1.0% (95% CI: -0.4 to 2.5%); p = 0.156). With both types of equipment, the hands-off time decreased with an increasing cumulative number of previous CPR trainings (p = 0.042). The study equipment reduced the mean time until administration of adrenaline (epinephrine) by 23 s (p = 0.003) and that of amiodarone by 17 s (p = 0.016). It also increased the mean number of changes in the person doing chest compressions (0.6 per simulation; p < 0.001) and decreased the mean number of chest compressions (2.8 per minute; p = 0.022) and the mean number of ventilations (1.8 per minute; p < 0.001). The chance of administering amiodarone at the appropriate time was higher, with an odds ratio of 4.15, with the use of the study equipment CPR.com compared to the standard equipment (p = 0.004). With an increasing number of prior CPR trainings, the time intervals in the ALS algorithm until the defibrillations decreased with standard equipment but increased with the study device. CONCLUSIONS: EMS staff with limited training in CPR profit from guidance through the ALS algorithm by the study device. However, the study device somehow reduced the ALS quality of well-trained rescuers and thus can only be recommended for ALS provider with limited experience.

Ischemia-reperfusion-induced unmeasured anion generation and glycocalyx shedding: sevoflurane versus propofol anesthesia.

INTRODUCTION: Vascular leakage after ischemia-reperfusion (IR) is largely attributed to the destruction of the endothelial barrier and its associated negatively charged glycocalyx. In vitro, sevoflurane attenuates these changes. Therefore, we compared sevoflurane with propofol with regard to the protection of the glycocalyx and the release of negatively charged substances in vivo. METHODS: After surgical preparation under midazolam-fentanyl, nine pigs each received either propofol or sevoflurane. Ischemia of 90 min was induced by a balloon catheter in the thoracic aorta. After 120 min of reperfusion, the anesthetics were changed back to midazolam-fentanyl. Five animals, each without aortic occlusion, served as time controls. Blood electrolyte parameters were measured, from which the strong ion gap (SIG) was calculated. Serum heparan sulfate concentrations and immunohistology served as a marker of glycocalyx destruction. RESULTS: Immediately after reperfusion, SIG increased significantly only in the propofol group (+6.7 mEq/l versus baseline; p < .05), remaining stable in sevoflurane and both time-controlled groups. Initially, heparan sulfate concentration increased comparably in both experimental groups, but after 120 min, it became stable in sevoflurane-anesthetized animals, while increasing further in the propofol group (p < .05). CONCLUSIONS: Unmeasured anions, predictive of negative outcome in previous studies, did not increase significantly in sevoflurane-anesthetized animals. Additionally, there was less heparan sulfate shedding over time, signaling less destruction of the glycocalyx. Therefore, in this in-vivo situation, sevoflurane proves to be superior to propofol in protecting the endothelium from IR injury.

Detection of right ventricular insufficiency and guidance of volume therapy are facilitated by simultaneous monitoring of static and functional preload parameters.

OBJECTIVE: Acute right ventricular failure (RVF) is a life-threatening condition. This study investigated whether the combination of central venous pressure (CVP) and left ventricular functional preload parameters, such as stroke volume variation (SVV) and pulse pressure variation (PPV), can be used for the detection of acute RVF and for guidance of volume therapy. DESIGN AND SETTING: Experimental study in a university laboratory. PARTICIPANTS: Fifteen anesthetized and ventilated pigs. MEASUREMENTS AND MAIN RESULTS: For the induction of RVF, mean pulmonary artery pressure (MPAP) was increased by 50% with a continuous infusion of a thromboxane-A(2) analog (U46619). Then, blood removal (300 mL) and retransfusion (blood 200 mL + colloid solution 200 mL) were performed. An analysis of volume responders and nonresponders was implemented. Increasing MPAP (25.1 to 37.4 mmHg) led to decreases in mean arterial pressure (72.2 to 60.1 mmHg) and cardiac output (2.8 to 2.3 L/min, p < 0.05). CVP (11.3 to 12.6 mmHg), PPV (13% to 17%), and SVV (11 to 14%) increased significantly (p < 0.05). During volume removal, MPAP (37.4 to 34.1 mmHg), mean arterial pressure (60.1 to 53.2 mmHg), and cardiac output (2.3 to 2.1 L/min) decreased (p < 0.05), whereas PPV and SVV remained unchanged. During volume loading, CVP increased in volume responders and nonresponders; however, PPV decreased in responders only. CONCLUSIONS: Increases of CVP and SVV or PPV are suspicious for RVF. However, SVV and PPV fail to predict volume responsiveness in RVF. Changes in SVV and PPV during a volume-loading maneuver can be used to assess volume responsiveness.

Haemodynamics and cardiac function during robotic-assisted laparoscopic prostatectomy in steep Trendelenburg position.

BACKGROUND: Robotic-assisted laparoscopic prostatectomy (RALP) is usually performed in steep Trendelenburg position, which can be associated with cardiac impairment due to positioning and capnoperitoneum. This study investigated haemodynamic consequences and cardiac function in this type of surgery and evaluated the hypothesis that steep Trendelenburg position and capnoperitoneum results in haemodynamic and ventricular impairment. METHODS: 10 patients (ASA I-III) scheduled for RALP in steep Trendelenburg position with capnoperitoneum were prospectively studied. Heart rate (HR), mean arterial pressure (MAP) and central venous pressure (CVP) were recorded. Stroke volume variation (SVV) and cardiac output (CO) were measured using pulse-contour analysis. Further, cardiac function was assessed using trans-oesophageal echocardiography before positioning (T1) and 10 min (T2) and 60 min (T3) after implementation of steep Trendelenburg position and capnoperitoneum. RESULTS: HR did not change statistically. MAP (T1, 69.7 ± 1.55; T2, 82.9 ± 3.05; T3, 79.4 ± 2.18 mmHg), CVP (T1, 7.7 ± 1.3; T2, 17.3 ± 2.01; T3, 16.9 ± 1.66 mmHg) and CO (T1, 4.0 ± 0.15; T2, 4.9 ± 0.26; T3, 4.9 ± 0.36 l/min) increased significantly at T2 and T3. Echocardiography showed no deterioration of left or right ventricular function. In one patient with pre-existing mitral valve insufficiency (I°) an aggravation of the insufficiency (III°) was observed. No other valve dysfunctions were observed. CONCLUSIONS: The steep Trendelenburg position may improve haemodynamic function and does not deteriorate left or right ventricular function during RALP. However, mitral valve insufficiency may be aggravated by positioning and capnoperitoneum.

Heart-lung interactions measured by electrical impedance tomography.

OBJECTIVE: The clinical value of stroke volume variations to assess intravascular fluid status in critically ill patients is well known. Electrical impedance tomography is a noninvasive monitoring technology that has been primarily used to assess ventilation. We investigated the potential of electrical impedance tomography to measure left ventricular stroke volume variation as an expression of heart-lung interactions. The objective of this study was thus to determine in a set of different hemodynamic conditions whether stroke volume variation measured by electrical impedance tomography correlates with those derived from an aortic ultrasonic flow probe and arterial pulse contour analysis. DESIGN: Prospective animal study. SETTING: University animal research laboratory. SUBJECTS: Domestic pigs, 29-50 kg. INTERVENTIONS: A wide range of hemodynamic conditions were induced by mechanical ventilation at different levels of positive end-expiratory pressure (0-15 cm H2O) and with tidal volumes of 8 and 16 mL/kg of body weight and by hypovolemia due to blood withdrawal with subsequent retransfusion followed by infusions of hydroxyethyl starch. MEASUREMENTS AND MAIN RESULTS: In eight pigs, aortic stroke volume variations measured by electrical impedance tomography were measured and compared to those derived from an aortic ultrasonic flow probe and from arterial pulse contour analysis. Data for four animals were used to develop and train a novel frequency-domain electrical impedance tomography analysis algorithm, while data for the remaining four were used to test the performance of the novel methodology. Correlation of stroke volume variation measured by electrical impedance tomography and that derived from an aortic ultrasonic flow probe was significant (r = 0.69; p < .001), as was the correlation between stroke volume variation measured by electrical impedance tomography and that derived from arterial pulse contour analysis (r = 0.73; p < .001). Correlation of stroke volume variation derived from an aortic ultrasonic flow probe and that derived from arterial pulse contour analysis was significant too (r = 0.82; p < .001). Bland-Altman analysis comparing stroke volume variation measured by electrical impedance tomography and that derived from an aortic ultrasonic flow probe revealed an overall bias of 1.87% and limits of agreement of ± 7.02%; when comparing stroke volume variation measured by electrical impedance tomography and that derived from arterial pulse contour analysis, the overall bias was 0.49% and the limits of agreement were ± 5.85%. CONCLUSION: Stroke volume variation measured by electrical impedance tomography correlated with both the gold standard of direct aortic blood flow measurements of stroke volume variation and pulse contour analysis, marking an important step toward a completely noninvasive monitoring of heart-lung interactions.

Thermodilution-derived indices for assessment of left and right ventricular cardiac function in normal and impaired cardiac function.

OBJECTIVE: The aim of this study was to assess whether thermodilution-derived parameters of right and left ventricular cardiac function (right ventricular ejection fraction, global ejection fraction, cardiac function index) are able to track changes of cardiac contractile function and whether they are influenced by substantial preload reduction. DESIGN: Prospective animal study. SETTING: University-affiliated animal research laboratory. SUBJECTS: Domestic pigs. INTERVENTIONS: Sixteen domestic pigs were studied. Right ventricular ejection fraction, global ejection fraction, and cardiac function index were compared to direct measurement of left ventricular rate of maximum systolic pressure rise and the left ventricular rate of maximum systolic pressure rise corrected to preload. Measurements were done with normal cardiac function during normo- and hypovolemia. Thereafter, cardiac function was impaired by continuous infusion of verapamil and measurements were repeated during normo- and hypovolemia (withdrawal of blood 20 mL kg body weight). MEASUREMENTS AND MAIN RESULTS: With normal cardiac function, hypovolemia led to a significant decrease of right ventricular ejection fraction from 36.7% ± 6.6% to 29.8% ± 5.8% (p < .001), global ejection fraction from 40.5% ± 6.2% to 33.6% ± 7.6% (p < .001), and the left ventricular rate of maximum systolic pressure rise from 2104 ± 390 mm Hg sec to 1297 ± 438 mm Hg sec (p < .001). Cardiac function index (8.92 ± 2.20 min to 7.93 ± 1.54 min) and the left ventricular rate of maximum systolic pressure rise corrected to preload (18.2 ± 4.7 mm Hg sec mL to 15.2 ± 4.3 mm Hg sec mL) did not change significantly. Infusion of verapamil led to a significant reduction of right ventricular ejection fraction, global ejection fraction, cardiac function index, the left ventricular rate of maximum systolic pressure rise, and the left ventricular rate of maximum systolic pressure rise corrected to preload (p < .001). Now, hypovolemia led to a significant decrease of right ventricular ejection fraction (29.1% ± 4.6% to 24.9% ± 5.9%; p < .001), global ejection fraction (37.1% ± 4.7% to 31.9% ± 3.9%; p < .05), cardiac function index (7.58 ± 1.02 to 6.27 ± 1.19 min; p < .05), and the left ventricular rate of maximum systolic pressure rise (733 ± 141 mm Hg sec to 426 ± 108 mm Hg sec; p < .05). Only the left ventricular rate of maximum systolic pressure rise corrected to preload did not change significantly (6.7 ± 1.3 mm Hg sec mL to 4.6 ± 1 mm Hg sec mL; p > .05). CONCLUSIONS: Right ventricular ejection fraction, global ejection fraction, and cardiac function index enable detection of changes in load-independent, intrinsic cardiac contractility. Importantly, they also reflect changes of contractile function caused by substantial decrease of preload, emphasizing the importance of assessing both cardiac contractile function in coherence with cardiac preload to differentiate between reduced intrinsic contractility and hypovolemia.

Functional hemodynamic parameters do not reflect volume responsiveness in the immediate phase after acute myocardial ischemia and reperfusion.

OBJECTIVE: Functional preload parameters such as stroke-volume variation (SVV) and pulse-pressure variation (PPV) are superior to filling pressures when assessing volume responsiveness in mechanically ventilated patients. This investigation studied their application in the setting of acute myocardial ischemia and reperfusion (I/R). DESIGN AND SETTING: Experimental animal study in a university laboratory. PARTICIPANTS: Twenty anesthetized and ventilated pigs. INTERVENTIONS: A temporary reduction of preload was obtained by ventilation with a positive end-expiratory pressure of 10 cmH(2)O. Ischemia was induced by temporary occlusion of the left anterior descending coronary artery for 60 minutes and was followed by 30 minutes of reperfusion. MEASUREMENTS AND MAIN RESULTS: Animals were instrumented with an ultrasonic aortic flow probe to monitor stroke volume (SV) and SVV. Arterial pressure and PPV were recorded with a microtip catheter; left ventricular volume and pressure were registered by a conductance catheter. Respective hemodynamic measurements were made before, during, and after PEEP; before and after the induction of I/R. Eleven animals survived I/R and were analyzed. Before I/R, SVV (r = 0.87, p < 0.001) and PPV (r = 0.75, p < 0.05) during PEEP correlated significantly with relative changes in SV caused by the release of PEEP. Changes in SVV (r = 0.82, p < 0.01) and PPV (r = 0.67, p < 0.05) correlated significantly with relative changes in SV. After I/R, neither the relations between changes in SV to SVV or PPV during PEEP nor the relations between changes in SVV or PPV to changes in SV reached significance. CONCLUSIONS: SVV and PPV did not reflect volume responsiveness in an experimental model of acute myocardial I/R.

Anesthesia during cardiologic procedures.

PURPOSE OF REVIEW: Cardiovascular diseases are counted among the most prevalent morbidities in western nations and they still are the leading cause of death in these countries. An increasingly aging population will confront all physicians with a growing number of patients having cardiovascular dysfunction. Anesthesiologists need to be familiar with upcoming new cardiologic procedures to provide hemodynamic stability during these procedures. RECENT FINDINGS: Cardiovascular diseases are often combined with severe comorbidities such as renal failure, chronic obstructive pulmonary disease, pulmonal hypertension and cerebrovascular damage. So anesthesia in this cohort requires experience, especially when during direct manipulation of the cardiac system such as in cardiologic procedures. Additionally, a new therapeutic option has been developed for valvular dysfunction recently, which involves the anesthesiologist in a new treatment of a high-risk population. SUMMARY: This review will focus on anesthesiological management of patients undergoing implantation of pacemakers and defibrillators, coronary interventions and interventions in the rapidly growing field of percutaneous treatment of mitral and aortic valve failure.

Systolic pressure variation and pulse pressure variation during modifications of arterial pressure.

OBJECTIVE: This study was performed to investigate the effect of vasopressor therapy on systolic pressure variation (SPV) and pulse pressure variation (PPV) compared to experimentally measured left ventricular stroke volume variation (SVV). DESIGN AND SETTING: Prospective study in a university laboratory. SUBJECTS: Twelve anesthetized and mechanically ventilated pigs. INTERVENTIONS: Increase in mean arterial pressure (by 100%) using phenylephrine and decrease (by 38%) using adenosine. MEASUREMENTS AND RESULTS: SPV and PPV were calculated and compared to SVV derived from aortic blood flow measurements. SPV was significantly affected by changes in arterial pressure [4.6% (1.5) vs. 6.3% (2.1), p < 0.05, increased vs. decreased arterial pressure], whereas PPV did not change during modifications of arterial pressure. During baseline conditions and decreased afterload, correlation with SVV was good both for SPV (r =0.892 and r = 0.859, respectively) and for PPV (r = 0.870 and r = 0.871, respectively) (all p < 0.001). Correlation with SVV was only moderate during increased arterial pressure (r = 0.683 for SPV and r = 0.732 for PPV, p < 0.05). CONCLUSION: For guiding fluid therapy in patients under vasopressor support, PPV seems superior to SPV.

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.

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.

Eye surgery in the elderly.

Elderly patients represent the majority of the surgical population scheduled for ophthalmological surgery. Eye surgery is usually minimally invasive, enabling most of the procedures to be performed as day-case surgery despite the high co-morbidity of these patients. This, however, requires a specific perioperative anaesthetic strategy. In this chapter we address features of perioperative care in the geriatric population undergoing eye surgery, from pre-medication and pre-operative testing, to choice and performance of anaesthesia, and finally to post-anaesthesia care.