New pain following cordotomy: clinical features, mechanisms, and clinical importance.

OBJECT: The clinical features, possible causes, and contributing factors associated with novel spontaneous pain following unilateral cordotomy were investigated to clarify the mechanism and clinical importance of this pain. METHODS: Forty-five patients who underwent cordotomy for severe unilateral cancer pain were included in this study. New pain occurred in 33 (73.3%) of 45 patients. Pathological conditions of tissue demonstrated on imaging corresponded to new pain in eight patients, referred pain in five, and neither of these in 15 patients. New pain was centered opposite the site of the original pain in a mirror-image location in 28 patients and rostral to the original pain in five patients. It was temporary in seven patients, weaker than the original pain in 25, and as severe as the original pain in one patient. The incidence of moderate or severe pain was significantly higher in patients with confirmed tissue disease (six of eight patients) than in those without (six of 20 patients). An important contributing factor to the occurrence of new pain was the achievement of analgesia by performing the cordotomy. CONCLUSIONS: The present results indicate that new pain occurs frequently after unilateral cordotomy. Nonetheless, cordotomy may still be indicated for unilateral uncontrollable pain because new pain, when present, was weaker and more easily controlled than the original pain in nearly all cases. The authors speculate that new pain may represent a type of referred pain from the original painful area or may arise from sensitization of contralateral spinal nociceptive circuits due to metastasis or tumor infiltration, and that new pain is potentiated by the interruption of descending inhibitory pathways.

[Evaluation of efficiency of ACD-CPR and STD-CPR; a multi-institutional study].

We compared the efficacy of ACD-CPR and STD-CPR based on 64 multi-institutional reports. No significant differences were observed in the rate of restoration of spontaneous circulation (ROSC) and in cardiopulmonary parameters during CPR using the two methods. There were 5 cases in which cardiopulmonary parameters improved after switching from STD-CPR to ACD-CPR and, eventually, in two of them spontaneous circulation was restored. In the ROSC cases of both groups, ETCO2 and values of SpO2, PaO2, and systolic BP at 30 minutes were higher than those of non-ROSC cases. ETCO2 never exceeded 20 mmHg in the non-ROSC cases, but it was higher in the ROSC cases. ACD-CPR is a good choice when trained persons are present or when extra hands are available to continue the CPR.

Prostaglandin E1 improves hepatic encephalopathy produced by ischaemia-reperfusion liver injury in rats.

OBJECTIVE: To investigate the action of prostaglandin E1 on hepatic encephalopathy. DESIGN: Prospective, randomised, controlled animal study. SETTING: University animal laboratory. SUBJECTS: Male Wistar rats. INTERVENTIONS: After passive avoidance learning, acute liver failure was induced by occlusion of the left portal vein and the hepatic artery for 90 min. Then memory retention was evaluated 48 h later. The effects of prostaglandin E1 on memory retention were examined in animals treated with the agent systemically (intravenous injections with prostaglandin E1 twice before and after surgery, 20 microg/kg each time) and animals treated with the agent topically (intracerebroventricular injection with prostaglandin E1, 0.1 microg/h for 48 h beginning at liver ischaemia). MEASUREMENTS AND RESULTS: Marked damage was found on plasma analysis in animals subjected to liver ischaemia, and the memory retention was also impaired. Intravenous administration of prostaglandin E1 improved both the liver injury and memory retention. However, intracerebroventricular administration of prostaglandin E1 alleviated neither. CONCLUSION: These findings show that prostaglandin E1 contributes to the amelioration of hepatic encephalopathy by improving liver function.

[Effects of intravenous nicardipine, prostaglandin E1, nitroglycerin, sodium nitroprusside, and epidural lidocaine on hepatic and renal blood flow during hypotensive anesthesia].

We studied the effects of intravenous nicardipine (NIC), prostaglandin E1 (PGE1), nitroglycerin (TNG), sodium nitroprusside (SNP) and epidural lidocaine (LID) on hepatic and renal blood flow during general anesthesia (nitrous oxide-oxygen-sevoflurane) in 46 female patients undergoing unilateral total hip arthroplasty. During operations, hepatic blood flow, glomerular filtration rate, renal plasma flow, and renal tubular injury were measured by R 15 ICG (15 minutes retention rate of indocyanine green), CCR (creatinine clearance), CPAH (para-aminohippuric acid clearance), and urinary excretion of NAG and beta 2-microglobulin. Significant elevation of R 15 ICG was observed in the hypotensive state in the TNG group and the elevation of R 15 ICG indicates that blood flow to the liver has decreased during hypotensive anesthesia. Urine volume in the PGE1 group was larger than that in the TNG, SNP or LID group. CCR in the PGE1 group was larger than that in the NIC, TNG or SNP groups. CPAH in the PGE1 group was larger than that in the SNP or LID group. The value of urine NAG in the TNG group was larger than that in the NIC or PGE1 group. The value of urine beta 2-microglobulin in the NIC group was larger than that in the PGE1 or SNP group. The results of urine volume, CCR, CPAH, urine NAG, and urine beta 2-microglobulin indicate that blood flow to the kidneys was greater in the PGE1 group as compared to other groups. This study indicates that prostaglandin E1 is the best hypotensive drug for hepatic and renal blood flow during hypotensive anesthesia.

Behavioral manifestations of neuropathic pain and mechanical allodynia, and changes in spinal dorsal horn neurons, following L4-L6 dorsal root constriction in rats.

We investigated behavioral symptoms of neuropathic pain, and associated changes in dorsal horn neurons, in a rat model involving loose ligation of lumbar dorsal roots. The L4-L6 dorsal roots were exposed unilaterally and loosely constricted central to the respective ganglia with one (1-ligation) or two (2-ligation) silk 7-O ligatures. In control groups the dorsal roots were exposed but not ligated (sham-operated), or sutures were placed lengthwise between the dorsal roots (suture control). There was a significant reduction in mechanical withdrawal threshold on the operated side in both 1- and 2-ligation groups which began at 3 days, peaked at 2-5 week, and gradually recovered. A delayed threshold reduction was also seen on the non-operated side. Immediately post-surgery there was a significant increase (hypoalgesia) in thermal paw withdrawal latency (Hargreaves test) in 1- and 2-ligation groups on the operated (but not non-operated) side that recovered after 1 week. Significantly less weight was borne by the operated limb 1-5 weeks post-operatively in 1- and 2-ligation groups. The force of hind limb withdrawals elicited by graded noxious heat pulses (38-52 degrees C) was significantly lower 1 week post-surgery on the operated side (1-ligation group) followed by recovery. Withdrawal forces were higher 5-9 week post-surgery on the non-operated side in 1- and 2-ligation groups. We found no evidence of cold allodynia. Neither sham-operated nor suture controls showed any signs of allodynia or hyperalgesia. Following behavioral testing, rats were anesthetized with halothane for single-unit recordings from lumbar wide dynamic range-type (WDR) neurons. At 22 week post-surgery, the mean area of mechanosensitive receptive fields was significantly larger for units on the operated side in 1- and 2-ligation groups compared with those on the non-operated side or with those from sham-operated rats. Mean stimulus-response functions to graded noxious heat pulses (38-52 degrees C, 5 s) were not significantly different between operated and non-operated sides for 1- or 2-ligation groups, or compared with the 22-week sham-operated group. At 5 week post-surgery, the mean area of cutaneous receptive fields, and stimulus-response functions to graded noxious heat, were not significantly different between units recorded on operated versus non-operated sides, or compared with units from 5-week sham-operated rats. Spontaneous unit activity was significantly higher on the operated versus non-operated side in the 2-ligation (22-week) and sham (5-week) groups. Enlarged cutaneous receptive fields of dorsal horn neurons may contribute to mechanical allodynia associated with dorsal root constriction. However, the slow (>5 week) development of receptive field enlargement does not match the rapid development of allodynia. The lack of effect of dorsal root constriction on thermal sensitivity of dorsal horn units ipsilaterally corresponds to the lack of marked thermal hyperalgesia observed behaviorally.

Force of limb withdrawals elicited by graded noxious heat compared with other behavioral measures of carrageenan-induced hyperalgesia and allodynia.

We investigated if carrageenan-induced thermal hyperalgesia and mechanical allodynia are associated with a reduction in threshold and-or enhancement of suprathreshold nocifensive responses, using a method to measure the force of a hind limb wilhdrawal reflex elicited by graded noxious heat stimuli (36-52 degrees C, 5s) delivered by Peltier thermode tethered to the ventral hind paw of conscious rats. Withdrawal reflexes were recorded 2.5 h after intraplantar injection of carrageenan (1 or 0.1%) or saline vehicle in sessions >2 weeks apart: baseline reflexes were assessed the day before. Withdrawal reflex force increased linearly from 42-52 degrees C. Carrageenan 1% significantly enhanced withdrawal reflexes at 40-46 degrees C, reducing the slope and threshold of the stimulus-response function. This was associated with significant reductions in thermal paw withdrawal latency (Hargreaves test: by 50%), mechanical withdrawal threshold (by 82%) and weight bearing on the injected side (by 81%) measured with independent force plates. Smaller reductions in thermal paw withdrawal latency and mechanical withdrawal threshold, and smaller enhancement of withdrawal reflex force, were observed following 0.1% carrageenan. Intraplantar saline was ineffective. This method allows assessment of hyperalgesic changes in stimulus-response coding over a broad range of noxious stimulus intensities.

Effect of differential delivery of isoflurane to head and torso on lumbar dorsal horn activity.

BACKGROUND: The spinal cord appears to be the site where anesthetic agents prevent movement in response to noxious stimuli. When isoflurane is differentially delivered to the head and torso (with low torso concentrations), cranial anesthetic requirements increase compared with systemic administration. The aim of the current study was to test the hypothesis that isoflurane action in the brain has descending influences on spinal cord dorsal horn neurons. A secondary aim was to determine the association, if any, of high cranial concentrations of isoflurane (>6%) with dorsal horn activity. METHODS: Ten goats were anesthetized with isoflurane and the carotid arteries and jugular veins isolated and cannulated for cerebral bypass. A laminectomy was performed for recording from single lumbar dorsal horn neurons with hind limb mechanical receptive fields (one cell per goat). A standard noxious mechanical stimulus was applied to the dew claw or hoof bulb during a control period with end-tidal isoflurane at 1.3% and during bypass with the following head/torso isoflurane concentrations: 1.3%/1.3%, 3.2%/1.3%, 9.4%/1.3%, 1.3%/0.2%, 3.0%/0.2% and 8.8%/0.3%. RESULTS: When torso isoflurane concentration was 1.3%, increasing cranial isoflurane concentration to 3% or 9% had no significant effect on the activity of dorsal horn units. When torso isoflurane was 0.2-0.3%, spontaneous activity increased; however, at these torso concentrations, evoked responses were significantly decreased (-60%) only when cranial isoflurane concentration was increased to 9%. CONCLUSIONS: Isoflurane action in the brain had an inhibitory effect on dorsal horn activity with the combination of supraclinical cranial and low torso concentrations.

[Mouth mask method for fiberoptic tracheal intubation in difficult intubations].

We tried 72 fiberoptic tracheal intubations (FTI) using a mouth mask in difficult intubation cases. In this method, ventilation is performed via only the mouth using a mask applied over the mouth (mouth mask) and FTI can be done via a nostril with no hindrance from the mask in anesthetized patients. We have been using an infant or child type Seal Mask (Gibeck Respiration) for the mouth mask or a specially made mouth mask. An oral airway is usually inserted and the nostril of one side is plugged with cotton. FTI is performed by another anesthesiologist. An endotracheal (ET) tube capped with a rubber diaphragm is passed through another nostril, and a fiberscope is inserted through the ET tube. The subsequent technique is the same as that of the usual FTI for awake patients. Intubations were successful in all cases except 2; in one, ventilation was impaired even with oral airway in place, and in the other, bleeding in upper airway due to jaw injury from traffic accident hindered the sight of the scope. Mouth mask method for FTI is safe, useful and practical in difficult intubations with little discomfort to the patient.

[Multiple regression analysis of pre- and intra-operative factors in relation to post-operative liver and renal functions].

We investigated the factors which may influence post-operative liver and renal function using a multiple regression analysis after isoflurane or sevoflurane anesthesia in 844 patients (ASA I or II, age 20-90 yr). Hepatic and renal surgeries were excluded from this study. The parameters examined were sex, age, degree of obesity, preoperative liver function, preoperative renal function, infection with hepatitis B or hepatitis C virus, inhalation anesthetics used, MAC.h of anesthesia, the duration of operation, blood loss, amount of blood transfusion, urine volume during operation, and surgical site. Serum GOT, GPT, total bilirubin, BUN and serum creatinine were examined on the 3rd and 7th day after surgery. An increase in serum GOT, GPT or bilirubin was observed for each of the following parameters; male, infection with hepatitis C virus, long operation, and upper abdominal surgery. Postoperative BUN and serum creatinine increased in patients with preoperative renal dysfunction, in elderly patients, and in hepatitis C carriers.

[The histological changes in the spinal cord following percutaneous cervical cordotomy (PCC) and correlation of these changes with the efficacy of PCC].

We observed the histological changes in the spinal cord following percutaneous cervical cordotomy (PCC) and correlation of these changes with the efficacy of PCC in 7 cases. A fine monopolar electrode which we used, measured 0.25 mm or 0.27 mm in diameter with exposed length of 2 mm. An oval or elliptical-shaped lesion, 1 to 3 mm in width and 3 to 4 mm in length, was observed in 6 of these cases. The main lesion was found in the anterolateral column in 5 cases. In 3 of these 5 cases, the whole anterolateral column had been destroyed, and in the other 2 cases dorsal one half to two thirds of it had been destroyed. In these 5 cases, pain sensation on the opposite side of PCC was lost for a long time and pain was relieved until death (21-239 days after PCC). In the other 2 cases the lesion in the anterolateral column was tenuous or unrecognizable, and the loss of pain sensation was temporary with pain recurring by the next day. This study showed that an oval or elliptical-shaped lesion was made in PCC and that in cases in which main lesion was located in the anterolateral column, pain relief was long lasting.

[MAC-awake and wake-up time of isoflurane and sevoflurane with reference to the concentration of gas, duration of inhalation and patient's age and obesity].

We evaluated the influence of the concentration of volatile anesthetics, the duration of inhalation time, the patient's age and degree of obesity on MAC-awake (the end-tidal concentration of volatile anesthetics on awakening) and Wake-up time (the period from stopping inhalation to eye-opening in response to verbal command) following isoflurane (Iso) or sevoflurane (Sev) anesthesia in 240 patients (ASA I or II, age 17-84 yr). The patients were anesthetized with 50% oxygen, 50% nitrous oxide and various concentrations of Iso or Sev. They were divided into 6 groups in respect to the end-tidal concentration of Iso or Sev: Iso 0.7% (1 MAC), Iso 1.0% (1.5 MAC), Iso 1.4% (2 MAC), Sev 0.9% (1 MAC), Sev 1.3% (1.5 MAC) and Sev 1.8% (2 MAC). After operation all anesthetics were discontinued and MAC-awake and Wake-up time were measured under 100% oxygen inhalation. MAC-awake value of Iso was 0.14 +/- 0.05% (SD)% in all groups and that of Sev was 0.17 +/- 0.05% in Sev 0.9% group, 0.16 +/- 0.05% in Sev 1.3%, 0.17 +/- 0.06% in Sev 1.8%, respectively. All of them became smaller in aged groups than in younger groups but they were not influenced by the concentration of gas, the duration of inhalation nor the degree of obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in human evoked spinal potentials (ESP) by epidural lidocaine].

Controversies exist on the sites of action of epidural anesthesia. Leading opinion says that it works on spinal nerve root. We examined ESP and tactile sensations in 4 patients during epidural anesthesia with lidocaine to determine the effects of the anesthesia on spinal cord. Prolongation of latency and decrease in amplitude of ESP appeared 10 min after injection of 1.5% lidocaine 4 ml, each parameter reaching maximum value of 115% and 60% of the control value 30 min afterwards, respectively. Then they started to recover slowly, reaching normal values 150 min later. Changes in ESP and tactile sensation were closely related. Decreases in amplitude to 90%, 80%, 60% of the control values were observed for hypesthesia, analgesia, and anesthesia, respectively. We conclude that the spinal cord also is an important site of action of epidural anesthesia.

A multi-arterial clamping method with arterial hypotension does not bring about complete brain ischemia in dogs.

The completeness of brain ischemia with a multi-arterial clamping method in dogs was examined using EEG, evoked potentials (EPs) and vessel staining with Evans blue. EEG was monitored by bipolar parietal lead. EPs stimulating electrodes were inserted into the first thoracic (T1) epidural space and recording electrodes into the C2 epidural space, brain stem and cerebral cortex. EPs were measured at 30 s intervals with 50 measurements each time using 3.0 mA current of 100 microseconds duration. In dogs in which brain ischemia was brought about by ventricular fibrillation (VF group, n = 5) EEG disappeared within 40 s in all dogs and the amplitudes of EPs at the C2 spinal cord, brain stem and cerebral cortex after 10 min ischemia were 57%, 0% and 0%, respectively. In the dogs in which a multi-arterial clamping method (clamping internal thoracic arteries, brachiocephalic trunk and left subclavian artery while lowering systolic arterial pressure (AP) below 50 Torr) was used (AC group, n = 5) EEG was still recognizable at 5 min in 2 dogs and the amplitudes of EPs at the C2, brain stem and cerebral cortex at 10 min ischemia were 103%, 53% and 0%, respectively. Stainings with Evans blue were observed in all soft tissue at and below thoracic level, entire intervertebral venous plexus, venous sinuses of cranial dura mater and spinal cord below the lower part of cervical region. Bright red fluorescence by Evans blue was observed microscopically in the vessels of the spinal cord, brain stem and cerebrum (1 dog only). In conclusion a multi-arterial clamping method with arterial hypotension brings about only incomplete brain ischemia.

[The relationship between the deep body temperature and hemodynamics after open-heart surgery in children].

The relationships of the forehead-sole deep body temperature difference with the cardiac index (CI), and with the systemic vascular resistance index (SVRI) were studied in 10 pediatric patients (TOF 5, ASD 3, VSD 2) for 24 hours after open-heart surgery. A correlation between the deep body temperature difference (X) and CI (Y) was expressed as, Y = -0.49X + 4.51 (r = 0.72), and that between the deep body temperature difference (X) and SVRI (Z) as Z = 152X + 1039 (r = 0.62). The deep body temperature difference was 1.0 degrees C on the average in patients whose CI was more than 3.0 l.min-1.m-2, and was 3.3 degrees C in patients whose CI was less than 3.0 l.min-1.m-2. Conversely CI was less than 3.0 l.min-1.m-2 in patients whose deep body temperature difference was more than 3.0 degrees C. We conclude that the measurement of deep body temperature difference is useful as a circulatory monitor, and that a critical level of deep body temperature difference is 3 degrees C in children.

[The relationship between the deep body temperature and hemodynamics after open-heart surgery].

The relation of the forehead-sole deep body temperature difference with the cardiac index (CI), and the relation of that with the systemic vascular resistance index (SVRI) were studied in 61 adult patients after open-heart surgery for 24 hours. A correlation between the deep body temperature difference (X) and CI (Y) was expressed as, Y = -0.21X + 3.42 (r = 0.48), and that between the deep body temperature difference (X) and SVRI (Y), Y = 184X + 808 (r = 0.52). But immediately after the end of operation (n = 61), the correlation coefficients (r) were lower, 0.46 and 0.45, respectively. The deep body temperature difference was 1.8 degrees C on the average in patients whose CI was 2.21.min-1.m-2, and was 4.3 degrees C in patients whose CI was below 2.21.min-1.m-2. Conversely CI was below 2.21.min-1.m-2 in patients whose deep body temperature difference was more than 4 degrees C. We conclude that the measurement of deep body temperature difference is useful as a circulatory monitor, and that a critical level of deep body temperature difference is 4 degrees C.