Nicholas Kiefer

Clinical validation of a new thermodilution system for the assessment of cardiac output and volumetric parameters

IntroductionTranspulmonary thermodilution is used to measure cardiac output (CO), global end-diastolic volume (GEDV) and extravascular lung water (EVLW). A system has been introduced (VolumeView/EV1000™ system, Edwards Lifesciences, Irvine CA, USA) that employs a novel algorithm for the mathematical analysis of the thermodilution curve. Our aim was to evaluate the agreement of this method with the established PiCCO™ method (Pulsion Medical Systems SE, Munich, Germany, clinicaltrials.gov identifier: NCT01405040)MethodsSeventy-two critically ill patients with clinical indication for advanced hemodynamic monitoring were included in this prospective, multicenter, observational study. During a 72-hour observation period, 443 sets of thermodilution measurements were performed with the new system. These measurements were electronically recorded, converted into an analog resistance signal and then re-analyzed by a PiCCO2™ device (Pulsion Medical Systems SE).ResultsFor CO, GEDV, and EVLW, the systems showed a high correlation (r2 = 0.981, 0.926 and 0.971, respectively), minimal bias (0.2 L/minute, 29.4 ml and 36.8 ml), and a low percentage error (9.7%, 11.5% and 12.2%). Changes in CO, GEDV and EVLW were tracked with a high concordance between the two systems, with a traditional concordance for CO, GEDV, and EVLW of 98.5%, 95.1%, and 97.7% and a polar plot concordance of 100%, 99.8% and 99.8% for CO, GEDV, and EVLW, respectively. Radial limits of agreement for CO, GEDV and EVLW were 0.31 ml/minute, 81 ml and 40 ml, respectively. The precision of GEDV measurements was significantly better using the VolumeView™ algorithm compared to the PiCCO™ algorithm (0.033 (0.03) versus 0.040 (0.03; median (interquartile range), P = 0.000049).ConclusionsFor CO, GEDV, and EVLW, the agreement of both the individual measurements as well as measurements of change showed the interchangeability of the two methods. For the VolumeView method, the higher precision may indicate a more robust GEDV algorithm.Trial registrationclinicaltrials.gov NCT01405040.

Performance of a new pulse contour method for continuous cardiac output monitoring: validation in critically ill patients

BACKGROUND A new calibrated pulse wave analysis method (VolumeView™/EV1000™, Edwards Lifesciences, Irvine, CA, USA) has been developed to continuously monitor cardiac output (CO). The aim of this study was to compare the performance of the VolumeView method, and of the PiCCO2™ pulse contour method (Pulsion Medical Systems, Munich, Germany), with reference transpulmonary thermodilution (TPTD) CO measurements. METHODS This was a prospective, multicentre observational study performed in the surgical and interdisciplinary intensive care units of four tertiary hospitals. Seventy-two critically ill patients were monitored with a central venous catheter, and a thermistor-tipped femoral arterial VolumeView™ catheter connected to the EV1000™ monitor. After initial calibration by TPTD CO was continuously assessed using the VolumeView-CCO software (CCO(VolumeView)) during a 72 h period. TPTD was performed in order to obtain reference CO values (COREF). TPTD and arterial wave signals were transmitted to a PiCCO2™ monitor in order to obtain CCO(PiCCO) values. CCO(VolumeView) and CCO(PiCCO) were recorded over a 5 min interval before assessment of CO(TPTD). Bland-Altman analysis, %(errors), and concordance (trend analysis) were calculated. RESULTS A total of 338 matched sets of data were available for comparison. Bias for CCO(VolumeView)-CO(REF) was -0.07 litre min(-1) and for CCO(PiCCO)-CO(REF) +0.03 litre min(-1). Corresponding limits of agreement were 2.00 and 2.48 litre min(-1) (P<0.01), %(errors) 29 and 37%, respectively. Trending capabilities were comparable for both techniques. CONCLUSIONS The performance of the new VolumeView™-CCO method is as reliable as the PiCCO2™-CCO pulse wave analysis in critically ill patients. However, an improved precision was observed with the VolumeView™ technique. CLINICALTRIALS.GOV IDENTIFIER: NCT01405040.

Display of information in the operating room

Purpose of review The ongoing development of new sensors and parameters for intraoperative monitoring has outpaced the development of display design, leading to a gap between the load of information and the quality of its delivery. This is not a circumstantial problem, as a large portion of critical incidents is attributable to inadequate situation awareness and the failure to recognize readily monitored data. This review also addresses improvements of current threshold alarms. Recent findings Research has focused on advanced integrated displays, drawing on the findings of human factor science and on the exploitation of alternative sensory pathways. Integrated displays, as well as auditory, vibrotactile and head-mounted displays have been shown to promote situation awareness and reduce cognitive workload. Intelligent alarm design can successfully reduce the number of false alarms. Summary Improvement of the display of information in the operating room is warranted, and recent developments are promising. However, their introduction into mass market is not yet on the horizon, although the shortcomings of the traditional single-sensor-single-indicator principle are known for a long time. If manufacturers are reluctant to implement new techniques into their devices, they should at least facilitate access to monitoring raw data in order to allow independent development of displays.

Peristaltic Pneumatic Compression of the Legs Reduces Fluid Demand and Improves Hemodynamic Stability during Surgery: A Randomized, Prospective Study

Background:Perioperative fluid restriction might be beneficial in specific clinical settings. In this prospective, randomized and blinded study, we assessed whether peristaltic pneumatic compression of the legs can support restrictive fluid management strategies by reducing intraoperative fluid demand and improving hemodynamic stability. Methods:Seventy patients scheduled for minor surgery were randomly assigned to receive either intraoperative peristaltic pneumatic compression or placebo compression. Both groups received fluid therapy according to a goal-directed protocol with a crystalloid base rate of 2 ml · kg−1 · h−1 and bolus infusions of 250 ml crystalloids triggered by hypotension, tachycardia, or high Pleth Variability Index. Results:Patients treated with peristaltic pneumatic compression received less intravenous fluid: median (interquartile range) 286 (499) versus 921 (900) ml (P < 0.001), resulting in a median difference of 693 ml (95% CI, 495–922 ml) and a median difference of 8.4 ml/kg (95% CI, 5.3–11.5 ml; P < 0.001). After the anesthesia induction phase, median overall infusion rates were 12.2 (14.1) ml · kg−1 · h−1 in the control group and 1.9 (0.4) ml · kg−1 · h−1 in the pneumatic peristaltic compression group (P < 0.001). Among patients treated with pneumatic peristaltic compression, the median cumulative time of hypotension was shorter (0 [12.5] vs. 22.6 [22.8] min; P = 0.002), fewer hypotensive events were recorded (39 vs. 137; P = 0.001), and median lowest individual systolic pressure was higher (92 [8] vs. 85 [16] mmHg; P = 0.002). Conclusions:This study demonstrates that peristaltic pneumatic compression of the legs significantly improves hemodynamic stability and reduces fluid demand during minor surgery.

Conception, Pregnancy, and Lactation Despite Chronic Intestinal Failure Requiring Home Parenteral Nutrition.

BACKGROUND Short-term parenteral nutrition is commonly accepted to be safe in pregnancy, but knowledge about the management of pregnancy during long-term home parenteral nutrition (HPN) is sparse. METHODS AND RESULTS A systematic literature review revealed that the published experience is limited to 15 pregnancies with parenteral nutrition from preconception to delivery and beyond. Maternal morbidity was surprisingly low, and fetal outcome was good; however, micronutrient deficiencies may have contributed to fetal anomalies. Herein, we additionally report the case of a 26-year-old Caucasian woman with long-term HPN dependence secondary to short bowel syndrome caused by recurrent thromboembolic mesenteric infarctions who delivered a healthy fetus at 37 weeks of gestation. Individual macronutrient support and adequate micronutrient supplementation ensured normal maternal weight gain and fetal development. Based on the individual maternal risk of recurrent thrombosis, anticoagulant treatment was carefully titrated throughout pregnancy. Furthermore, loss of abdominal domain with a rigid maternal abdominal wall secondary to short bowel syndrome and multiple laparotomies resulted in food intolerance during the third trimester. Still, with multidisciplinary efforts, both mother and the breast-fed infant were in good health at 12 months after delivery. CONCLUSIONS Taking the reported literature into consideration, we conclude that under the premise of optimal medical care, the risk:benefit ratio for pregnancy of HPN-dependent women seems to be justifiable. To minimize the risks, we recommend preconception counseling and early referral to a tertiary center offering both a high-risk pregnancy unit and a nutrition service. In particular, maternal micronutrient levels should be monitored.

Introducing Hyperthermic Intraperitoneal Chemotherapy into Gynecological Oncology Practice - Feasibility and Safety Considerations: Single-Center Experience

Background: Within the surgical oncology community interest is increasingly focusing on combining surgical cytoreduction and regional chemotherapeutic drug delivery to manage solid abdominal tumors. In particular, the role of hyperthermic intraperitoneal chemotherapy (HIPEC) is evolving for treating epithelial ovarian carcinomas (EOCs), as EOCs remain confined to the peritoneal cavity for most of their natural history. Currently there is no evidence from prospective trials to confirm an overall survival benefit associated with HIPEC. In addition, there are no generally accepted regimens, which results in heterogeneous clinical procedures. Methods: We have initiated a HIPEC program at our institution and completed a phase I study of HIPEC with cisplatin in patients with platinum-sensitive recurrent EOC. The data have been published and prove the feasibility of this approach. In the process of introducing HIPEC, several safety measures had to be taken into consideration. Results: We present the implications and requirements of introducing HIPEC in clinical practice and discuss our proposed procedure referring to the recent literature. Conclusion: HIPEC is feasible and can be performed safely in daily gynecological oncology routine provided that certain considerations and precautions are taken into account during its introduction to guarantee a proper and safe operating sequence.

Non invasive oscillometric assessment of pulse pressure variation - a feasibility study

Cyclic respiratory change of the arterial pulse pressure (pulse pressure variation, PPV) is a better predictor of cardiovascular response to fluid challenge than traditional hemodynamic parameters like arterial blood pressure, central venous pressure, or pulmonary artery occlusion pressure. The main drawback of PPV monitoring is its dependence on arterial cannulation. We demonstrate that respiratory changes are also present in the oscillometric signal obtained during non invasive blood pressure monitoring (NIBP). Furthermore, we show that this signal can be used to assess non-invasive pulse pressure variation (NIPPV) with a modified NIBP cuff and describe the influence of cuff filling media on signal quality. NIPPV measured with a water-filled cuff in 5 patients under going elective abdominal surgery was highly correlated to femoral-arterial PPV (r=0.91, p< 0.0001). This method has potential impact on routine monitoring in perioperative care.