Ventricular arterial coupling (Ees/Ea), the ratio of left ventricular end-systolic elastance (Ees) to effective arterial elastance (Ea), serves as a useful index to evaluate the mechanical performance of the heart. In the previous investigation, we developed a framework to estimate the Ees/Ea based on left ventricular time-varying elastance without measuring the ventricular volume or altering the loading condition. The proposed framework is capable of estimating the Ees/Ea from readily accessible hemodynamic variables of systolic times (PEP : pre-ejection time, ET :ejection time) and arterial pressures (Pes : end-aystolic pressure, Pad : aortic diastolic pressure), and thus is useful in evaluating ventricular mechano-energetic performance in a clinical setting.
In this study, based on the proposed method, we tried to monitor the Ees/Ea automatically in patients under general anesthesia using radial arterial pressure, electrocardiograms, and esophageal phonocardiograms in order to measure the parameters PEP, ET, Pad, and Pes, which are necessary to estimate Ees/Ea. We presented three cases of Ees/Ea monitoring during general anesthesia, where we found the change in the Ees/Ea was consistent with the clinical findings of bleeding, vasoactive drugs, and epidural anesthesia. These results suggest that monitoring of Ees/Ea is useful for evaluating the balance of the cardiac and the arterial system.

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This study was done to compare the effects of sevoflurane (SEV) inhalation and propofol (PF) infusion on autonomic nervous activity relative to their hypnotic effects. The entropy (ENT), a new index for heart rate variability against short time data, was used to assess the autonomic nervous activity, and the Bispectral Index (BIS) was used to assess the hypnotic state. The ENT is an idea derived from the probability measure of fuzzy events and adapted for use as an analytic tool for the distribution of R-R intervals. The ENT is normalized from 0 to 100% : 0% is indicated at the state of no fluctuation and 100% when the probable distribution is flat.
Methods : After obtaining institutional approval, 40 consenting patients were enrolled. During the pre-operative period, two anesthetic regimens were compared. 1. SEV group : An injection of thiopental followed by 5 % SEV inhalation was performed. After intubation, end-tidal concentration of 0.3% and 0.6% SEV in nitrous oxide and oxygen (4l : 2l) was maintained. 2. PF group : PF was administered using target-controlled infusion. Patients received PF and fentanyl for induction. After intubation, target concentrations of 1 and 2μg/ml of PF and nitrous oxide and oxygen (4l : 21) were maintained.
The BIS monitoring of the hypnotic state was performed using an Aspect A-1050 EEG Monitor. ECG signals were monitored and transferred to a personal computer program (MemCalc/ ECG, Suwa Trust). The BIS and ENT in between the sampling period and the pre-induction state in each group were compared. The values at each anesthetic level were compared between the two groups.
Results : Both BIS and ENT decreased after induction of anesthesia in both groups. The ENT was higher in the PF group at some anesthetic levels, where the BIS was lower or uncharged as compared to the SEV group.
Discussions and Conclusions : Sevoflurane appears to have a more suppressive effect on heart rate variability than propofol.

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We studied the beneficial effects of deep breathing during preoxygenation with a face mask loosey fitted to the face. The end-tidal oxygen concentration (ETO₂) after breathing for 30 seconds was measured in 14 healthy volunteers in order to compare the four-time inspiratory capacity breathing (ICB) technique with the tidal breathing (TB) technique. The total fresh oxygen flow was maintained at 6 or 9l•min-1 and the face mask was kept 2.5cm or 5.0cm from the face. The values of ETO₂ after applying the four-time ICB technique were 27% for the 6l•min-1 and 2.5cm protocol, 21% for the 6l•min^-1 and 5.0cm protocol, 32% for the 9l•min-1 and 2.5 cm protocol, and 23% for the 9l•min^-1 and 5.0cm protocol. Those after application of the TB technique were 25%, 20%, 29%, and 21%, respectively. The ETO₂ values obtained after application of the ICB technique were significantly higher than those obtained after the TB technique for all the protocols. In conclusion, the ICB technique for preoxygenation is significantly more beneficial for increasing ETO₂ than the TB technique, even if the face mask is loosely fitted to the face.

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We have previously reported that prostaglandin E, maintained the estimated hepatic blood flow during sevoflurane anesthesia. In the present study, we investigated the effects of diltiazem on the hepatic blood flow during sevoflurane anesthesia by detecting the indocyanine green (ICG) clearance rate using a finger-piece method, which is the same method as in the previous study. Eight patients scheduled for arthroscopic knee surgery were chosen and they received simultaneously anesthesia consisting of N₂O-O₂-1.7% sevoflurane and an intravenous drip administration of 5μg•kg^-1•min^-1 of diltiazem (D-group). The results obtained from the D-group were compared with those of the group receiving only sevoflurane anesthesia (S-group, n=8), from the previous study. The ICG clearance rate and cardiac output (CO) using an impedance method were measured both before anesthesia and two hours after the start of anesthesia in both groups. The ICG clearance rate decreased to 63% and CO decreased to 71% of their respective baseline values in the S-group, but they were maintained at 95% and 103% in the D-group, which were significantly higher than the values of the S-group. The present study indicates that administration of a small dose of diltiazem during sevoflurane anesthesia could produce a protective effect on hepatic circulation by maintaining CO as prostaglandin E₁, whereas sevoflurane decreased CO and the estimated hepatic blood flow.

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We examined the influence of a seven day course of nocturnal sedation with propofol on serum lipid concentrations and cellular immunities in mechanically ventilated ICU patients. Sixteen adult patients undergoing total esophagectomy were randomly allocated to receive or not to receive propofol for 7 nights. In patients who received propofol, the mean propofol dose required to maintain an adequate level of sedation, according to a Ramsay sedation score of 3 to 4, was 1.9±0.5mg•kg^-1•h^-1.
The concentrations of both serum triglyceride and total cholesterol increased slightly but remained normal in all patients studied. High-density-lipoprotein cholesterol (HDL-cholesterol) concentrations decreased with time in the propofol group and lowered the normal value, whereas they remained the same in patients who did not receive propofol. Statistically significant differences between the groups were found. As for cellular immunity, no significant changes were detected in any of the patients studied except for natural killer-cell activities. Since HDL-cholesterol plays a pivotal role in the elimination of triglyceride from the bloodstream, we have concluded that even if the lipid load is reduced by nocturnal administration, the infusion of propofol for more than 7 days may reduce HDL-cholesterol concentrations and lead to hypertriglyceridemia.

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To prevent hypertension and tachycardia during tracheal intubation, we evaluated the effects of two different types of calcium-antagonists, diltiazem and nicardipine, on patients with a bispectral index of around 40, an adequatety sedate condition. Sixty-two OB-GYN patients were randomly assigned into three groups, the propofol-alone induction group (P), the propofol+diltiazem induction group (P+D) and the propofol+nicardipine induction group (P+N). The bispectral index during tracheal intubation was maintained at below forty in all patients, which indicated an adequately sedate condition.
The mean blood pressure in all three groups significantly increased after tracheal incubation compared to just before intubation. Among the groups, the mean blood pressure after intubation was significantly higher in the P group compared to the other two groups. The heart rate after intubation increased significantly in the P+D and P+N groups compared to before intubation. Sedation induced by propofol, diltiazem or nicardipine might cause excessive depression of the sympathetic responses for tracheal intubation, at which point compensatory tachycardia might be exaggerated in the P+D and P+N groups.

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We report a patient who went into cardiac arrest from hemorrhagic shock and a cervical spinal cord injury during the anesthesia of an emergency operation for a traumatic aortic arch injury. A 70-year-old man was brought by ambulance to our emergency center about 45 minutes after he fell down. His consciousness level was JCS 20. He showed dyspnea just after arrival, and he was immediately intubated and ventilated. There was paralysis of the lower half of his body, anemia and decreased blood pressure. We diagnosed a C_6-7 spinal cord injury, aortic arch injury and hemothorax in both sides. A left thoracotomy was performed and the aortic arch injury required. Anesthesia was maintained by high doses of fentanyl and pancuronium. Though he went into cardiac arrest right after the thoracotomy, due to hemorrhagic shock and cervical spinal cord injury we suspect, he survived without any sequelae except for spinal disorders.

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We report a case of a left atrial mass-like shadow imaged by transesophageal echocardiography after a cardiopulmonary bypass performed during open heart surgery. The TEE image showed that there was a mass-like shadow between the left atrial appendage and the left pulmonary vein. We restarted the cardiopulmonary bypass and opened the heart to search for the cause of the mass-like shadow. However, we were unable to determine the cause, and no abnormalities were revealed either on the CT or during the MRI examination, postoperatively, but the intra-atrial mass-like shadow was still seen on the transesophageal echocardiography. We thought that we had mistaken the structure between the left atrial appendage and the left pulmonary vein for an intracardiac tumor.

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A 70-year-old woman with left deep venous thrombosis was scheduled for a right total knee replacement under general anesthesia. A temporary inferior vena cava filter (TIVC-F) was preoperatively inserted to prevent perioperative pulmonary thromboembolism. Her perioperative course was uneventful. When the TIVC-F was withdrawn, small fresh thrombi were found in the filter. However, even with macroscopic and microscopic investigation of the thrombi, we could not evaluate whether the filter trapped the thromboemboli or whether the thrombi developed in the filter. If the thrombi developed in the filter, insertion of the TIVC-F caused another thrombosis. Therefore, we suggest that it is necessary to reexamine the thrombogenicity of TIVC-F.

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A 10-year-old girl with myasthenia gravis had had bilateral ptosis for 8 years. Since dysphagia appeared despite multiple anticholinergic treatments, a thymectomy was scheduled. Her serum anti-acetylcholine receptor(anti-AChR)-antibody level was 0.7 nmol•l^-1. The compound action potential of the abductor digiti minimi was monitored after train-of-four (TOF) stimulation of the ulnar nerve at the wrist. The initial TOFR value was 75 %. Fifteen minutes after inhalation of 2 MAC isoflurane, the T1 values decreased to 65%. Tracheal intubation was performed without the use of a muscle relaxant. Anesthesia was maintained with 66% N₂O in oxygen, 1.2% isoflurane, and fentanyl as needed. As soon as the inhalation of isoflurane was stopped, good spontaneous respiration appeared. Her clinical course was uncomplicated during the perioperative period. We successfully managed the patient by careful monitoring of the neuromuscular functions without the use of muscle relaxants.

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We investigated the accuracy of a disposable pulse oximeter sensor (Mallinckrodt^TM type II D-20) in multiple use. Sixteen probes were numbered and repeatedly used five times in anaesthesia on different patients. After the placement of an indwelling catheter in the radial artery, SpO₂ and PERF (the indicator of signal quality) were measured, and arterial blood gas was simultaneously analyzed in room air.
The prediction error (PE) was evaluated by the following equation: PE=(SpO₂-SaO₂)/SpO₂×100.
The distribution of the PE did not change significantly with the number of times or duration of use. The PE of some probes, however, exceeded 3.0% after being used for the third time or after 900 min. Although a disposable sensor should ideally be used only once or on only one patient, our results indicate that a disposable probe can be used several times safely and accurately, if a sensorcheck device is employed.

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