Published papers

An 87-year-old man with severe aortic stenosis (AS), refusing aortic valve surgery, was scheduled to undergo posterior spinal fusion. According to American College of Cardiology/American Heart Association (ACC/AHA) 2008 Guideline, aortic valve surgery is recommended before non-cardiac surgery in a patient with severe AS. Several reports have noted that non-cardiac surgery could be performed safely with careful anesthetic management by adjusting left ventricular preload and systemic arterial pressure, and avoiding tachycardia. We used pulmonary artery catheter to estimate left ventricular preload, which is an especially essential factor for maintaining cardiac output. Transesophageal echocardiography has been proved to be superior to pulmonary artery catheter for evaluating left ventricular preload. However, it is difficult to perform in the prone position. Although pulmonary artery wedge pressure (PAWP) is influenced in prone position due to the chest compression, PAWP combined with cardiac index and their responsiveness to fluid administration is valuable in hemodynamic management in a patient with severe AS.

A 22-year-old female was scheduled to undergo posterior thoracolumbar spinal fusion. She had been diagnosed with congenital antithrombin III (AT-III) deficiency by the onset of pulmonary embolism and deep vein thrombosis after the first operation at the age of 18. Thereafter she had taken warfarin, 5 mg daily, until 4 days before the surgery. Preoperatively, we administered AT-III products to regulate AT-III activity. The posterior spinal fusion was performed successfully without surgical complications. Postoperatively, we continued administration of AT-III products to maintain AT-III activity above 75%. We also used low dose unfractionated heparin with AT-III by continuous intravenous infusion. Heparin was administered with dose adjustment to achieve a target activated partial thromboplastin time of 45 to 60 seconds. After the activated partial thromboplastin time was stabilized in the target range, we started warfarin therapy (target international normalized ratio, 1.5 to 2.5) on postoperative day 16 and stopped administration of heparin on postoperative day 19. There was no thrombosis complications during the perioperative period. Good anticoagulant management was achieved in a patient with congenital AT-III deficiency undergoing posterior spinal fusion.

A new non-invasive continuous cardiac output (esCCO) monitoring system solely utilizing a routine cardiovascular monitor was developed, even though a reference cardiac output (CO) is consistently required. Subsequently, a non-invasive patient information CO calibration together with a new automated exclusion algorithm was implemented in the esCCO system. We evaluated the accuracy and trending ability of the new esCCO system. Either operative or postoperative data of a multicenter study in Japan for evaluation of the accuracy of the original version of esCCO system were used to develop the new esCCO system. A total of 207 patients, mostly cardiac surgical patients, were enrolled in the study. Data were manually reviewed to formulate a new automated exclusion algorithm with enhanced accuracy. Then, a new esCCO system based on a patient information calibration together with the automated exclusion algorithm was developed. CO measured with a new esCCO system was compared with the corresponding intermittent bolus thermodilution CO (ICO) utilizing statistical methods including polar plots analysis. A total of 465 sets of CO data obtained using the new esCCO system were evaluated. The difference in the CO value between the new esCCO and ICO was 0.34 +/- 1.50 (SD) L/min (95 % confidence limits of -2.60 to 3.28 L/min). The percentage error was 69.6 %. Polar plots analysis showed that the mean polar angle was -1.6 degrees and radial limits of agreement were +/-53.3 degrees . This study demonstrates that the patient information calibration is clinically useful as ICO, but trending ability of the new esCCO system is not clinically acceptable as judged by percentage error and polar plots analysis, even though it's trending ability is comparable with currently available arterial waveform analysis methods.

BACKGROUND: Many technologies have been developed for minimally invasive monitoring of cardiac output. Estimated continuous cardiac output (esCCO) measurement using pulse wave transit time is one noninvasive method. Because it does not require any additional sensors other than those for conducting 3 basic forms of monitoring (electrocardiogram, pulse oximeter wave, and noninvasive (or invasive) arterial blood pressure measurement), esCCO measurement is potentially useful in routine clinical circulatory monitoring for any patient including low-risk patients. We evaluated the efficacy of noninvasive esCCO using pulse wave transit time in this multicenter study. METHODS: We compared esCCO and intermittent bolus thermodilution cardiac output (TDCO) in 213 patients, 139 intensive care units (ICUs), and 74 operating rooms (ORs), at 7 participating institutions. We performed electrocardiogram, pulse oximetry, TDCO, and arterial blood pressure measurements in patients in ICUs and ORs; a single calibration was performed to measure esCCO continuously. TDCO measurement was performed once daily for ICU patients and every hour for OR patients, and just before the removal of the pulmonary arterial catheter from patients in both the ICU and OR. We evaluated esCCO against TDCO with correlation analysis and Bland and Altman analysis and also assessed the change of bias over time. Furthermore, we inspected the impact of change in systemic vascular resistance (SVR) on change in bias because abnormal SVR was assumed to be a factor contributing to the change of the bias. RESULTS: From among 588 esCCO and TDCO datasets (excluding calibration points), 587 datasets were analyzed for 213 patients. The analysis results show a correlation coefficient of 0.79 (P < 0.0001, 95% confidence limits of 0.756-0.819), a bias (mean difference between esCCO and TDCO) of 0.13 L/min (95% confidence interval of bias 0.04-0.22 L/min), and a precision (1 SD) of 1.15 L/min (95% prediction interval was -2.13 to 2.39 L/min). There were no significant differences among 3 defined time intervals over 48 hours after calibration (repeated-measures analysis of variance P = 0.781) in the ICU. The influence of SVR on esCCO analysis showed a correlation coefficient between SVR and an error of 0.37 (P < 0.0001, 95% confidence interval 0.298-0.438). CONCLUSION: The efficacy of noninvasive esCCO technology was compared with TDCO in 213 cases. Five hundred eighty-seven datasets comparing esCCO and TDCO showed close correlation and small bias and precision, which were comparable to current arterial waveform analysis technologies.

BACKGROUND: The purpose of this study was to determine the effects of transient arterial blood pressure change on the accuracy of the FloTrac/Vigileo monitor (Edwards Lifesciences, Irvine, CA). METHODS: We compared stroke volume determined with the FloTrac/Vigileo with Doppler during anesthetic induction in 20 patients undergoing abdominal aortic reconstruction. RESULTS: The difference between the FloTrac measurements of stroke volume and the Doppler measurements of stroke volume was -7.5 +/- 20.5 mL (mean +/- SD) before induction, 0.3 +/- 14.9 before laryngoscopy, 17.5 +/- 26.9 during laryngoscopy, 20.5 +/- 27.6, and -4.5 +/- 16.4 mL 3 minutes after endotracheal tube placement. CONCLUSION: The FloTrac/Vigileo measured stroke volume with reasonable accuracy during transient hypotension but overestimated stroke volume during transient hypertension.

PURPOSE: The inflammatory response triggered by transfusion is implicated in the pathophysiology of transfusion-related immunomodulation. The authors hypothesized that two distinctive autotransfusion methods, acute normovolemic hemodilution (ANH) and preoperative donation (PD), have different influences on both inflammatory mediator generation during storage and the inflammatory response after a transfusion. The purpose of this study was to compare the plasma concentrations of neutrophil elastase (NE), interleukin (IL)-6, IL-8, and IL-10 in patients who underwent either of these two autologous transfusion methods. METHODS: With institutional review board approval, the plasma concentrations of the above inflammatory mediators were determined in 23 patients with ANH and 8 patients with PD at the following time points: after anesthetic induction, at the end of the operation, and the morning of postoperative day 1. The concentrations of these inflammatory mediators were also measured in the donated blood obtained by either ANH or PD before retransfusion. RESULTS: The mean storage durations were 3.7 h and 6.1 days for ANH and PD, respectively. Higher concentrations of NE and IL-10 were detected in the PD blood than in the ANH blood. Long duration of storage and/or low temperature may have been responsible for the increased NE and IL-10 concentrations in the PD blood. However, the difference between the two groups in the extent of increased plasma concentrations of these inflammatory mediators was not statistically significant. CONCLUSION: Inflammatory mediators were significantly increased in PD blood during storage compared to the blood obtained by ANH. However, their effects on the inflammatory response elicited in the recipients were not significantly different.

BACKGROUND: We hypothesized that mixed venous hemoglobin oxygen saturation (SvO2) can be estimated by calculation from CO2 production, cardiac output, and arterial oxygen saturation measured using a noninvasive cardiac output (NICO) monitor (Novametrix-Respironics, Wallingford, CT). METHODS: Twenty-three patients undergoing aortic aneurysm repair underwent SvO2 monitoring using a pulmonary artery catheter and cardiac output monitoring using a NICO monitor. The estimated SvO2 value calculated from NICO monitor-derived values was compared with the SvO2 value measured using a pulmonary artery catheter. The accuracy of this estimation was analyzed with Bland-Altman method. The ability of this estimation to track the change of SvO2 was also evaluated using correlation analysis to compare the changes of estimated SvO2 and measured SvO2. RESULTS: The bias +/- limits of agreement of the estimated SvO2 against measured SvO2 was -2.1% +/- 11.2%. The change of estimated SvO2 was modestly correlated with the change of measured SvO2. CONCLUSIONS: SvO2 derived from the values measured by the NICO monitor cannot be used interchangeably with the values measured spectrophotometrically using the pulmonary artery catheter. More refinement is required to obtain more reliable estimate of SvO2 less invasively. However, large changes of SvO2 may be detected with this method and can be used as a precautionary sign when the balance between oxygen supply and demand is compromised without inserting a central venous catheter.

OBJECTIVE: This study investigated the accuracy of the NICO monitor equipped with the newer software. Additionally, the effects of the increased dead space produced by the NICO monitor on ventilatory settings were investigated. METHODS: Forty-two patients undergoing elective aortic reconstruction participated in this prospective, observational study at a university hospital. Cardiac output was continuously monitored using both the NICO monitor and continuous cardiac output (CCO) measured by a pulmonary artery catheter. A NICO monitor equipped with ver. 4.2 software was used for the first 21 patients while a NICO monitor equipped with ver. 5.0 software was used for the rest of the patients. Cardiac output measured by bolus thermodilution (BCO) at 30 min intervals was used as a reference. RESULTS: The bias +/- precision of the NICO monitor was 0.18 +/- 0.88 l/min with ver. 4.2 software (n = 182) and 0.18 +/- 0.83 l/min with 5.0 software (n = 194). The accuracy of the NICO monitor is comparable to CCO, whose bias +/- precision against BCO is 0.19 +/- 0.81 l/min (n = 376). At the same level of CO(2) production and minute ventilation, PaCO(2) was lower in the patients monitored by NICO with ver. 5.0 software than patients with ver. 4.2 software. CONCLUSIONS: This study demonstrated the improved performance of the NICO monitor with updated software. The performance of the NICO monitor with ver. 4.2 or later software is similar to CCO. However, the cardiac output measurement did not fulfill the criteria of interchangeability to the cardiac output measurement by bolus thermodilution. Updates to ver. 5.0 attenuated the effects of rebreathing introduced by the NICO monitor without compromising the accuracy of the cardiac output measurement.