Hironori Ishihara

Current perception thresholds and postoperative pain in schizophrenic patients

Background and Objectives Schizophrenic patients may have less sensitivity to pain; however, pain insensitivity in schizophrenia has not been adequately evaluated. We investigated current perception threshold (CPT) and postoperative pain intensity in patients with long-standing and treated schizophrenia and control patients. Methods We measured CPTs for 2,000 Hz, 250 Hz, and 5 Hz and postoperative pain intensity using a visual analogue scale (VAS) in 50 chronic schizophrenic patients who were on chronic phenothiazine derivatives (> 10 years) and for 25 control patients. Results CPTs for 2,000 Hz, 250 Hz, and 5 Hz in schizophrenic patients were 334.2 ± 112.2, 303.9 ± 117.1, and 165.0 ± 72.3, respectively. CPTs for 2,000 Hz, 250 Hz, and 5 Hz in schizophrenic patients were significantly higher than those of control patients. VAS pain scores of schizophrenic patients were 4.0 ± 1.7 at 2 hours post-operatively and 3.8 ± 1.5 at 5 hours postoperatively, which were significantly (P < .05) lower than those (5.0 ± 1.6 and 5.1 ± 1.9) of the control group. Conclusions Chronic schizophrenic patients have increased current perception threshold and lower VAS pain scores in postoperative pain compared with control patients.

The relationship between pneumatic tourniquet time and the amount of pulmonary emboli in patients undergoing knee arthroscopic surgeries.

Near-fatal pulmonary embolism can occur immediately after tourniquet release after orthopedic surgeries. In this study, we determined the relationship between tourniquet time and the occurrence of pulmonary emboli in 30 patients undergoing arthroscopic knee surgeries, by using transesophageal echocardiography. The right atrium (RA) was continuously monitored by transesophageal echocardiography, and the number of emboli present was assessed with the following formula: Amount of emboli = 100 × [(total embolic area in the RA after tourni-quet release) − (total area of emboli or artifact in the RA before tourniquet release)]/(RA area). The area was assessed 0–300 s after tourniquet release by using image-analysis software. The peak amount of emboli appeared approximately 50 s after tourniquet release. In addition, there was a significant correlation between amount of emboli (Ae [%]) and tourniquet time (Ttq [min]): (Ae = 0.1 × Ttq − 1.0, r = 0.795, P < 0.01). This study suggests that acute pulmonary embolism may occur within 1 min of tourniquet release and that the number of emboli is dependent on Ttq.

A new non-invasive continuous cardiac output trend solely utilizing routine cardiovascular monitors.

Objective. Three of the us developed a new non-invasive continuous cardiac output (CCO) measurement method utilizing routine clinical monitors based on the pulse-contour analysis combined with pulse wave transit time (PWTT). Using pulmonary artery catheter (CCOpa), we compared this estimated CCO (esCO) with the thermodilution CCO early after cardiac surgery, and tested whether the esCO method has potential of being an alternative measure of CCO. Methods. Thirty-six patients without continued arrhythmias were studied. esCO was computed using electrocardiogram (ECG) monitor, arterial pressure monitor and pulse-oximetry system. Both sets of data (esCO and CCOpa), by averaging the results of the preceding 10 min, were compared at 30-min intervals throughout the 15.8± 3.3 h (S.D.) of study. Bland–Altman plots and correlation analysis were used for statistical comparison. Results. A total of 981 paired sets of data (89.9%) among 1093 measurements were compared in the absence of displacement of either pulse-oximetry or ECG probes and/or inaccurate detection of R wave. The difference between esCO and CCOpa results was −0.06 ± 0.82 L/min (S.D.), and there was a linear correlation between them (r = 0.80, p < 0.0001). The difference between them was 0.00± 0.48 L/min at the first 1 h, which remained unchanged throughout 20 h after the start of measurement. Conclusions. The results demonstrate that esCO has a close correlation with the CCOpa, even though the two methods are not interchangeable. The results suggest that esCO method has potential of being an alternative non-invasive cardiac output trend, unless there are apparent arrhythmias.

Effects of general anaesthesia and surgery on renal function and plasma adh levels

SummaryPlasma levels of antidiuretic hormone (ADH) were evaluated in 40 adult patients during and after various types of anaesthesia and surgery. The plasma level of ADH increased significantly 30 minutes after the start of anaesthesia with diethyl-ether (3.7 times) and after thiopentone (1.5 times), but it increased insignificantly in neuroleptanaesthesia (2.4 times) and with halothane (1.3 times). The surgical stress evoked marked increases in plasma ADH levels especially at ten minutes after the skin incision. A slight increase in plasma ADH level still continued into the early post-operative days.The effects of halothane anaesthesia on plasma levels of ADH and on both cortical and medullary renal blood flow (RBF) were investigated in dogs. RBF was measured by means of a heated thermocouple in two groups of eight dogs each. One group was given a high fluid load of 30 ml/kg/hr and the other a low load of 10 ml/kg/hr. The plasma level of ADH increased significantly with deepening halothane anaesthesia in the low fluid load group. However, in the high fluid load dogs it remained unchanged in spite of an increasing inspired halothane concentration. Both cortical and medullary RBF fell significantly as compared with the control values in the low fluid load group. However, in the high fluid load dogs no significant decrease was observed. These results would indicate that the anaesthetic agents investigated in the present study caused increases in plasma ADH levels, but that these antidiuretic effects of anaesthesia might be modified by the volume of fluid infused during anaesthesia and operation.RésuméPendant et après la chirurgie sous différents agents anesthésiques, on a déterminé la concentration plasmatique de ľhormone antidiurétique (ADH) chez 40 patients adultes opérés pour des pathologies abdominales variées. Une augmentation significative de ľADH a été notée après 30 minutes ďanesthésie à ľéther diéthylique (3.7 fois le contrôle) et le thiopentone (1.5 fois). Cette augmentation n’a pas été jugée significative après la neuroleptanesthésie (2.4 fois) et ľanesthésie à ľhalothane (1.3 fois). Le stress chirurgical a provoqué une augmentation importante, surtout à ta dixième minute après ľincision. Le niveau sanguin est demeuré légèrement élevé dans la période post-opératoire immédiate.Les effets de ľanesthésie à ľhalothane sur la concentration plasmatique de ľADH et sur le flux sanguin rénal cortical et médullaire ont aussi fait ľobjet ďune étude chez le chien. Dans deux groupes de huit chiens, on a mesuré au thermocouple le flux sanguin rénal. Le premier groupe a reçu une surcharge liquidienne de 30 ml/kg/hre alors que ľapport n’a été que de 10 ml/kg/hre pour le deuxième groupe. La concentration plasmatique ďADH s’est élevée de façon significative dans le deuxième groupe. Toutefois, dans le premier groupe qui avait reçu le plus grand volume liquidien, le niveau plasmatique ďADH n’a pas changé malgré les augmentations de concentration de ľhalothane. Dans le groupe où ľapport liquidien a été le moins élevé, le flux sanguin cortical et le flux médullaire ont diminué de façon significative par comparaison aux valeurs de contrôle de ce groupe. Cette diminution n’a pas été notée pour le groupe surchargé. Ces résultats suggèrent que les agents anesthésiques utilisés dans cette étude augmentent le niveau ďADH, mais que les effets antidiurétiques de ľanesthésie peuvent ïtre modifiés par la quantité de liquide perfusée pendant ľanesthésie et ľopération.

Multicenter study verifying a method of noninvasive continuous cardiac output measurement using pulse wave transit time: a comparison with intermittent bolus thermodilution cardiac output.

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.

Detection of capillary protein leakage by glucose and indocyanine green dilutions during the early post-burn period

Overestimation of the plasma volume determined by the indocyanine green (ICG) dilution method (PV-ICG) may occur after burns, since this dye has the potential of extravasation in the presence of the capillary protein leakage. Assuming that the initial distribution volume of glucose (IDVG) consistently indicates the extracellular fluid volume of highly perfused organs including plasma, overestimation of the PV-ICG can be detected by a higher PV-ICG/IDVG ratio. The present study was designed to test whether a higher PV-ICG/IDVG ratio is observed within 24 h post-burn compared to the subsequent days. Ten severely burned adult patients admitted to the ICU were studied through the 2nd post-burn day. The daily IDVG and PV-ICG were calculated using a one compartment model by simultaneous administration of glucose, 5 g, and ICG, 25 mg. Although the IDVG increased on the 1st post-burn day (p < 0.05), the PV-ICG remained unchanged. The PV-ICG/IDVG ratio within 24 h post-burn was significantly higher than that on the 1st post-burn day (p < 0.01). Results indicate that overestimation of the PV-ICG can occur within 24 h post-burn and suggest that simultaneous measurement of the IDVG and the PV-ICG would help predict the generalized capillary protein leakage after burns.

Detection of capillary protein leakage by indocyanine green and glucose dilutions in septic patients.

Objective: To determine whether indocyanine green (ICG) and glucose dilutions can detect generalized capillary protein leakage in septic patients without requiring repeated measurements. Design: Prospective, clinical study. Setting: General intensive care unit. Patients: Twelve consecutive patients who met the criteria of sepsis and 16 consecutive acute myocardial infarction (AMI) patients without any underlying pathology inducing generalized protein capillary leakage. Interventions: Both ICG 25 mg and glucose 5 g were administered simultaneously, to calculate the plasma volume determined by the ICG dilution method (PV‐ICG) and the initial distribution volume of glucose (IDVG), on day 1 of sepsis or on day 1 of hospitalization for the AMI patients. The relationship between these two volumes and the PV‐ICG/IDVG ratio was evaluated in two patient groups. Measurements and Main Results: Although the IDVG of the two patient groups was not statistically different, the PV‐ICG in the septic patients was higher than that in the AMI patients (p < .01). Consequently, the PV‐ICG/IDVG ratio in the septic patients was higher than that in the AMI patients (p < .01). Eight of the 12 septic patients had a PV‐ICG/IDVG ratio of >0.45, which was not observed in any of the AMI patients. The PV‐ICG/IDVG ratio in the septic patients correlated inversely with the total plasma protein concentration (r2 = .46, p < .025) and mean arterial pressure (r2 = .42, p < .05). Conclusions: Our results indicate that overestimation of the PV‐ICG can occur in septic patients and, further, suggest that simultaneous measurement of the two distribution volumes would help predict generalized capillary protein leakage in septic patients without repeated measurement.

Depressed Pituitary-Adrenal Response to Surgical Stress in Chronic Schizophrenic Patients

We evaluated whether pituitary-adrenal response to surgical stress is modified in chronic schizophrenic patients. Twenty-two schizophrenic patients on chronic antipsychotic therapy of phenothiazine derivatives over 10 years underwent orthopedic surgery of the extremities under general anesthesia by isoflurane and nitrous oxide. In chronic schizophrenic patients, responses of plasma epinephrine, norepinephrine, ACTH and cortisol levels during surgical stress were significantly lower than those of control patients. The attenuated response to surgical stress in these patients may be associated with their autonomic dysfunction and decreased pituitary-adrenal activity due to chronic administration of antipsychotic agents.

Alpha-2 Adrenoceptor Activity Affects Propofol-Induced Sleep Time

&agr;2 Adrenoceptor activity is involved in the mechanism of anesthesia. Clonidine, a &agr;2 adrenoceptor agonist, and yohimbine, a &agr;2 adrenoceptor antagonist, increase and decrease barbiturate-induced sleep times. In this study, we examined the effects of these drugs on propofol-induced sleep time. One-hundred-eighteen male Wistar rats weighing 320–400 g were used. Rats received saline, yohimbine (1, 0.1, or 0 mg/kg), or clonidine (300, 30, 3, or 0 &mgr;g/kg) intraperitoneally followed by 60 mg/kg of propofol in various combinations. In two series of experiments, either sleep time or prefrontal cortex norepinephrine release (microdialysis) was measured. One milligram/kilogram of yohimbine decreased propofol-induced sleep time to approximately 70% of control, and this was accompanied by an increase in perfusate norepinephrine of approximately 240% of control. Clonidine increased sleep time approximately 260% (300 &mgr;g/kg) and approximately 170% (30 &mgr;g/kg), and this was accompanied by a decrease (approximately 60% in both doses) in perfusate norepinephrine. In the present study, we show that the &agr;2 antagonist, yohimbine, decreased and the &agr;2 agonist, clonidine, increased propofol-induced sleep times. These changes were essentially mirrored in both groups by changes in norepinephrine release in the prefrontal cortex.

Relationship between diabetic autonomic neuropathy and gastric contents.

Delayed gastric emptying secondary to diabetic autonomic neuropathy (DAN) is a recognized risk factor for aspiration pneumonitis. The purpose of this study is to determine whether bedside autonomic function tests (AFTs) would predict gastric contents. Gastric volume and its pH were measured in 36 patients with diabetes mellitus (DM) and 15 nondiabetic patients at induction of general anesthesia for elective ambulatory surgery. Manifestations of autonomic dysfunction were assessed preoperatively in all 51 patients with five commonly used cardiovascular AFTs. According to the results of these five tests, 16 patients with DM met the criteria for the diagnosis and are called “DAN positive.” The remaining 20 diabetics did not meet the criteria and are called “DAN negative.” Fifteen patients without DM did not meet the criteria and are called “nondiabetics.” Diabetic patients were significantly older and more obese than nondiabetics and those with DM more than 10 yr were more often DAN positive. Solid, undigested food particles were found more often in the gastric contents of DAN-positive patients compared to nondiabetics. Gastric liquid volume and pH were similar in diabetic patients (DAN positive and DAN negative) and nondiabetic controls. These results demonstrate that diagnosis of DAN by commonly used cardiovascular AFTs does not predict larger gastric liquid volume or lower pH, but does predict the presence of solid food particles. The presence of food particles in gastric contents after 8 h of fasting could represent a risk factor for aspiration pneumonitis. Autonomic neuropathy is not manifested equally in the cardiovascular and gastrointestinal systems, but may be more severe in one than the other.