Possible Overestimation of Indocyanine Green-Derived Plasma Volume Early After Induction of Anesthesia with Propofol/Fentanyl

Apparently large plasma volumes derived by indocyanine green (PV-ICG) have been determined in the initial period after induction of anesthesia. We tested the hypothesis that possible overestimation of PV-ICG occurs shortly after anesthetic induction. Anesthesia was induced in 13 patients with fentanyl bolus 2 microg/kg and propofol infusion 0.5 mg x kg(-1) x min(-1) IV until patients lost consciousness and was then maintained with a propofol infusion. PV-ICG and the initial distribution volume of glucose (IDVG) were assessed at 15 min before and at 15 min after anesthetic induction. Plasma ICG and glucose concentrations were measured from serial blood samples taken before and through 7 min after injection of ICG 25 mg and glucose 5 g. PV-ICG and IDVG were calculated using a one-compartment model. PV-ICG was significantly increased by an average of 15.3% after induction, from 2.29 +/- 0.38 (SD) L to 2.64 +/- 0.31 L (P < 0.001). The mean hematocrit (Hct), concentrations of hemoglobin (Hb), and total plasma proteins at postinduction decreased compared with those at preinduction by 2.9%, 2.2%, and 2.3%, respectively (P < 0.05). Percentile increase in plasma volume calculated from Hb and Hct before and after induction was 4%. Consequently, an 11% overestimation in PV-ICG was observed. IDVG remained unchanged. Therefore, the ratio of PV-ICG/IDVG increased from 0.40 +/- 0.05 before induction to 0.48 +/- 0.06 after induction (P < 0.01). These results validate the hypothesis that possible overestimation of PV-ICG occurs during a definable period of time after propofol anesthetic induction. The present results also support the PV-ICG/IDVG ratio as a measure of possible overestimation of PV-ICG or fluid redistribution from the central to the peripheral tissues.

IMPLICATIONS

An approximate 11% overestimation in indocyanine green derived plasma volume was observed after induction of anesthesia using propofol and fentanyl. Simultaneous measurement of the initial distribution volume of glucose may help investigate the presence of overestimation in indocyanine green derived plasma volume.

Effects of nicardipine and diltiazem on the bispectral index and 95% spectral edge frequency

BACKGROUND AND OBJECTIVE

Previous studies have shown that L-type voltage-sensitive Ca2+ channel blocking agents increased and the L-type Ca2+ channel activator Bay K 8644 reduced the general anaesthetic potency in animals. As the bispectral index correlates with the depth of sedation, we examined whether L-type Ca2+ channel blocking agents affect the bispectral index.

METHODS

Thirty hypertensive patients (systolic arterial pressure >160 mmHg) presenting for total intravenous anaesthesia with propofol, fentanyl and ketamine were recruited. Bispectral index monitoring was commenced directly the patients arrived in the operating theatre. All patients were given either nicardipine or diltiazem intravenously at the discretion of the anaesthesiologist in charge.

RESULTS

Twenty-three and seven patients received nicardipine or diltiazem, respectively. The bispectral index level (mean (95% confidence interval)) did not change with either drug. In the nicardipine group, the bispectral index at 0, 5, 10 and 15 min was 55 (52-58), 55 (51-59), 55 (52-59) and 56 (53-59), respectively. In the diltiazem group, values were 59 (48-71), 60 (51-70), 61 (52-71) and 61 (50-72), respectively. Both L-type Ca2+ channel blocking agents significantly decreased arterial pressure.

CONCLUSIONS

Clinical doses of nicardipine and diltiazem do not alter the bispectral index during general anaesthesia.

Effect of linear polarized light radiation on impaired mitochondrial oxidative phosphorylation in skeletal muscle

PURPOSE

The aim of this study was to investigate the effect of linear polarized light radiation (LPLR) on mitochondrial oxidative phosphorylation impaired by hemorrhagic shock or Escherichia coli lipopolysaccharide (LPS) in skeletal muscle.

METHODS

We studied the effect of LPLR on mitochondrial function of skeletal muscle by using a model of mitochondria impaired by hemorrhage or LPS. The oxygen uptake in states 3 and 4, the respiratory control ratio (RCR), and the adenosine diphosphate-to-oxygen ratio (ADP/O) were measured with a Clark oxygen electrode.

RESULTS

Oxygen uptake in states 3 and 4, RCR, and ADP/O were significantly decreased by hemorrhage for 4 h and by LPS treatment for 12 h. Oxygen uptake in states 3 and 4 impaired by hemorrhage increased significantly from 40.1 +/- 3.2 to 60.1 +/- 5.4 nmol O(2).min(-1).mg protein(-1) after LPLR, and oxygen uptake in state 4 decreased significantly from 22.8 +/- 2.4 to 17.7 +/- 1.5 nmol O(2).min(-1).mg protein(-1) after LPLR. RCR and ADP/O were also significantly increased from 1.8 +/- 0.3 and 0.9 +/- 0.2 to 3.4 +/- 0.3 and 1.5 +/- 0.1, respectively, by LPLR. Oxygen uptake in states 3 and 4 impaired by LPS was improved from 46.6 +/- 5.1 and 21.0 +/- 1.9 to 53.8 +/- 6.2 and 17.9 +/- 2.3 nmol O(2).min(-1).mg protein(-1), respectively following LPLR. RCR and ADP/O were also elevated significantly from 2.2 +/- 0.2 and 0.9 +/- 0.2 to 3.0 +/- 0.3 and 1.4 +/- 0.2, respectively, after LPLR.

CONCLUSION

LPLR improved mitochondrial oxidative phosphorylation of skeletal muscle impaired by hemorrhagic shock or E. coli LPS.

Effects of propofol on bronchoconstriction and bradycardia induced by vagal nerve stimulation

BACKGROUND

Vagolysis has been considered as a mechanism by which propofol produces bronchodilation. However, it has also been suggested that propofol-induced bradycardia may result from increased vagal tone. In this study, we have determined whether propofol has vagolytic effects on both the airway and cardiovascular system.

METHODS

Mongrel dogs were anesthetized with pentobarbital. Bronchoconstriction was assessed by measuring changes in a bronchial cross-sectional area (BCA) using a bronchoscopic method. Heart rate (HR) and direct arterial blood pressure were also monitored. Vagal nerve stimulation (VNS) was performed for 60 s to produce both bronchoconstriction and bradycardia. To determine the effect of propofol on VNS-induced bronchoconstriction and bradycardia (n = 7), 0 (saline), 2.0 and 20 mg/kg propofol were administered intravenously at 20-min intervals with VNS commenced 5 min later. In addition, to determine if propofol-induced bradycardia is due to a vagomimetic action, two groups of six dogs were given 20 mg/kg propofol with or without 0.2 mg/kg atropine pre-treatment. HR was measured before and 5 min after propofol.

RESULTS

Propofol 20 mg/kg significantly inhibited VNS-induced bronchoconstriction. Although propofol per se significantly reduced HR (24%) and blood pressure (37%), the reduction in HR produced by VNS after 20 mg/kg propofol did not differ from that after saline or the lower dose of propofol (2 mg/kg). As atropine pre-treatment did not attenuate propofol-induced bradycardia, this response is unlikely to be simply due to vagomimetic actions.

CONCLUSION

Propofol has vagolytic effects on the airway but does not worsen bradycardia produced by parasympathetic stimulation.

Differential effects of thiopental on methacholine- and serotonin-induced bronchoconstriction in dogs

BACKGROUND

Thiopental sometimes causes bronchospasm during induction of anaesthesia. In addition, we have reported previously that thiopental produced transient bronchospasm, which was blocked by atropine pretreatment, and worsened histamine-induced bronchoconstriction in dogs. Previous in vitro reports suggest that synthesis of contractile cyclooxygenase products, such as thromboxane A(2), may be involved in the mechanism of bronchospasm. However, the in vivo spastic effects have not been defined comprehensively.

METHODS

Twenty-seven mongrel dogs were anaesthetized with pentobarbital. Bronchoconstriction was elicited with methacholine (0.5 microg kg(-1)+5.0 microg kg(-1) min(-1); Mch group, n=7) or serotonin (10 microg kg(-1)+1 mg kg(-1) h(-1); 5HT group, n=20), and assessed as percentage changes in bronchial cross-sectional area (BCA, basal=100%) using a bronchoscope. In the 5HT group, dogs were subdivided into four groups of five each: S-5HT, I-5HT, 5HT-S and 5HT-A. In the S-5HT and I-5HT groups, 30 min before serotonin infusion dogs were given saline and indomethacin respectively at 5 mg kg(-1) i.v. In all groups, 30 min after bronchoconstrictor infusion started, dogs were given thiopental at doses between 0 (saline) and 20 mg kg(-1). In the 5HT-S and 5HT-A groups, dogs were given saline or atropine 0.2 mg kg(-1) i.v. 5 min after thiopental 20 mg kg(-1).

RESULTS

Methacholine and serotonin reduced BCA by about 50 and 40% respectively. Thiopental 20 mg kg(-1) increased and decreased BCA by about 20 and 10% in the Mch and 5HT groups respectively. Indomethacin and atropine did not attenuate the potentiation of serotonin bronchoconstriction produced by thiopental.

CONCLUSION

The present study indicates that thiopental may attenuate or worsen bronchoconstriction induced by muscarinic or serotonin receptor stimulation, respectively. The synthesis of contractile cyclooxygenase products and cholinergic stimulation may not be involved in the contractile effect of thiopental on serotonin bronchoconstriction.

Effects of central hypocretin-1 administration on hemodynamic responses in young-adult and middle-aged rats

The prevalence of hypertension in middle age correlates with impaired autonomic regulation and as norepinephrinergic neurons decline with increasing age, and this reduction may contribute to this impairment. Central hypocretin-activated norepinephrinergic neurons contribute to sympathetic regulation. In the present study we compared sympathoadrenal effects of intracerebroventricular (i.c.v.) hypocretin-1(5 nmol) between young-adult (12-14 weeks) and middle-aged (12-14 months) rats. Arterial blood pressure, heart rate and plasma catecholamines were assessed under pentobarbital anesthesia. In addition, we compared hypocretin-1 and K(+)-evoked norepinephrine release from the cerebrocortical slices prepared from young-adult and middle-aged rats. We also examined whether the novel hypocretin receptor-1 antagonist (SB-334867) could reverse these hypocretin-1 effects both in vivo and in vitro. I.c.v. hypocretin-1 significantly increased blood pressure by some 7%, heart rate by 9% and plasma norepinephrine concentrations by 100% in young-adult rats. In middle-aged rats these parameters did not change. Plasma epinephrine did not increase in either group. There was a significant correlation between changes in mean arterial pressure and plasma norepinephrine. Similarly, hypocretin-1 evoked norepinephrine release from cerebrocortical slices prepared from young-adult rats was significantly higher than that of middle-aged rats whilst K(+)-evoked release did not differ between the groups. SB-334867 significantly attenuated hypocretin-1-increased blood pressure and both in vivo and in vitro norepinephrine release. The present data suggest that hypocretinergic neurons may contribute to the regulation of central but not adrenal sympathetic activity. Moreover, sympathetic regulation by hypocretinergic neurones may disappear in middle-age in rats.

[New study on the history of anesthesiology--(9) a brief history of "N2O Study Society"]

In Japan nitrous oxide has been manufactured since 1955 at the request of General Headquarters of the Allied Forces. Two years later in 1957, a manufacturer built a small society for the study and popularization of nitrous oxide anesthesia as well as general anesthesia. The society gave more than twenty seminars for this purpose in various cities in a period of 8 years from 1957 until 1965. At the seminars, Prof. Yamamura of Tokyo University and other professors of anesthesiology gave their lectures on basic science of nitrous oxide anesthesia and demonstrated its use for surgical patients. In July 1962, a fatal accident of explosion during ether anesthesia occurred in a hospital in Tokyo, in which a 25-year-old male died due to combustion and explosion triggered by electrical cauterization during surgery of pulmonary empyema. This accident facilitated and accelerated rapid and wide spread of nitrous oxide anesthesia as well as anesthesiology in general in Japan.

Effects of three different L-type Ca2+ entry blockers on airway constriction induced by muscarinic receptor stimulation

BACKGROUND

The crucial role of L-type Ca(2+) channels in airway smooth muscle contraction suggests that these channels could be an important therapeutic target. There are three separate drug binding sites on this channel: those for dihydropyridines, benzothiazepines and phenyl alkylamines. In this study, we examined the effects of the dihydropyridines nifedipine and nicardipine, the benzothiazepine diltiazem, and the phenylalkylamine verapamil on airway constriction.

METHODS

Tension of guinea-pig tracheal strips was measured isometrically in vitro with a force displacement transducer. Strips were precontracted with carbachol 10(-7) M with or without 4-aminopyridine 10(-3) M, a voltage-sensitive K(+ )channel blocker. Then, nifedipine 10(-8)-10(-4) M, diltiazem 10(-8)-3 x 10(-4) M or verapamil 10(-8)-3 x 10(-4) M was added cumulatively to the organ bath (n=6 each). The bronchial cross-sectional area of pentobarbital-anaesthetized dogs was assessed using a bronchoscopy method. Bronchoconstriction was elicited with methacholine 0.5 micro g kg(-1) plus 5 micro g kg(-1) min(-1), and then nicardipine 0-1000 micro g kg(-1), diltiazem 0-3000 micro g kg(-1) or verapamil 0-3000 micro g kg(-1) were given i.v. (n=7 each).

RESULTS

In the in vitro experiments, nifedipine and diltiazem fully reversed carbachol-mediated tracheal contraction with logIC(50) values of 4.76 (SEM 0.22) (mean 17.5 micro M) and 4.60 (0.33) (mean 24.8 micro M), respectively. Although verapamil 10(-6)-10(-4) M reversed the contraction by 87.2%, strip tension re-increased by 18.1% following maximal relaxation with verapamil 3 x 10(-4 )M. This re-increase was almost fully abolished by pretreatment with 4-aminopyridine. In the in vivo experiments, nicardipine and diltiazem dose-dependently reversed methacholine-induced bronchoconstriction, with logID(50) values of 3.22 (0.05) (mean 0.60 mg kg(-1)) and 1.85 (0.32) (mean 14.0 mg kg(-1)), respectively. Verapamil worsened methacholine-induced bronchoconstriction.

CONCLUSIONS

Although supraclinical doses of dihydropyridines and benzothiazepines can produce airway relaxant effects, these agents are unlikely to be used in the treatment of bronchoconstriction. In addition, verapamil may aggravate airway constriction.

Lack of an interaction between orexinergic and opioid/nociceptinergic systems in rat cerebrocortical slices

We have recently reported that orexins (OXs) selectively evoke norepinephrine release from rat cerebrocortical slices. In the present study, we have examined orexin-opioid interactions in OXA (100 nM) and K(+) (40 mM)-evoked norepinephrine release. OXA-evoked norepinephrine release was reversed approximately 90% by SB-334867 (OX(1)-receptor antagonist) (10 microM) but not naloxone (10 microM). [D-Pen(2),D-Pen(5)]-enkephalin (DPDPE) (DOP-agonist) and nociceptin/orphanin-FQ (N/OFQ) also failed to affect OXA-evoked release. [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) (MOP-agonist) and spiradoline (KOP-agonist) significantly reduced OXA-evoked release with the concentration producing 50% of the maximal inhibition (EC(50)) [maximal inhibition (E(max))] of 3.2 microM [41.8%] and 4.3 microM [54.9%] respectively. The effects of DAMGO and spiradoline were naloxone (10 microM)-insensitive. In contrast, naloxone significantly antagonized the inhibitory effects of DAMGO and spiradoline on K(+)-evoked release. We conclude that opioid receptors (DOP and KOP) are involved in K(+) but not OXA-evoked release. Moreover, we have failed to demonstrate an interaction between orexinergic and opioid/N/OFQ-ergic systems in this system.

Effects of nociceptin/orphanin FQ receptor ligands on blood pressure, heart rate, and plasma catecholamine concentrations in guinea pigs

Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the N/OFQ peptide receptor (NOP) and has been shown previously to produce bradycardia and hypotension in rodents. In this study we have measured the effects of intravenous N/OFQ, and the NOP antagonists [Nphe(1)]N/OFQ(1-13)-NH(2) ([Nphe(1)]) and [Nphe(1),Arg(14),Lys(15)]N/OFQ-NH(2) (UFP-101) on cardiovascular parameters and plasma catecholamine concentrations. Female Hartley guinea pigs were anesthetized with pentobarbital and ventilated artificially. MAP and HR were measured via a femoral arterial catheter and ECG, respectively. Plasma catecholamine concentrations were measured by HPLC. Animals received saline, N/OFQ (0.25, 1.25, 6.25 and 25 nmol cumulatively at 10-min intervals), [Nphe(1)] (600 nmol) and UFP-101 (60 nmol) i.v. in various combinations. After establishing a stable baseline, MAP and HR measurements and blood sampling were performed at the beginning and 3 min following each drug administration. N/OFQ significantly decreased MAP, HR and the plasma noradrenaline concentrations in a dose dependent manner (maximally by 29.1+/-1.8%, 13.8+/-0.8% and 46.6+/-7.8%, respectively) To the contrary, N/OFQ tended to increase plasma adrenaline concentration but did not affect plasma dopamine concentrations. There was a significant correlation between percent change in MAP (0.69, P<0.01) or HR (0.84, P<0.01) and that in plasma noradrenaline. [Nphe(1)], but not UFP-101, alone significantly decreased MAP. [Nphe(1)] partially antagonized N/OFQ-induced hypotension, bradycardia and the decrease in plasma concentration of noradrenaline. UFP-101 fully prevented the effects of N/OFQ in this model. In conclusion, the present study shows that intravenous N/OFQ, via NOP receptors, elicits hypotension and bradycardia also in the anaesthetized guinea pig and that the decrease in MAP and HR are positively correlated with the decrease in the plasma noradrenaline level.

The interaction between fentanyl and propofol during emergence from anesthesia: monitoring with the EEG-Bispectral index

STUDY OBJECTIVE

To investigate the effect of different plasma levels of fentanyl on the concentration of propofol and the Bispectral Index (BIS) required for patients to regain consciousness and orientation following surgery.

DESIGN

Prospective, open-label study.

SETTING

Operating room of a university hospital.

PATIENTS

28 patients, aging 20 to 50 years, scheduled for elective, 1- to 4-hour surgeries under general anesthesia.

INTERVENTIONS

BIS was continuously monitored from bifrontal montage (At1-Fpz and At2-Fpz) using an Aspect A-1,050 EEG system (Aspect, Natick, MA). Anesthesia was induced with bolus injections of fentanyl 2 microg/kg and propofol 2 mg/kg, and maintained with intermittent injections of fentanyl and constant infusion of propofol. Propofol infusion was stopped at the end of surgery.

MEASUREMENTS

Consciousness and orientation were assessed as clinical endpoints once every 2 minutes following the end of the surgery. Blood samples were extracted for plasma propofol and fentanyl concentrations (PCp and FCp, respectively), and BIS values were recorded when patients regained consciousness and orientation. Patients were allocated to one of three groups depending on FCp on awakening: Group 1, FCp > 1 microg/L (n = 8); Group 2, FCp < 1 microg/L and >0.45 microg/L (n = 9); and Group 3, FCp < 0.45 microg/L (n = 11). PCp, BIS, recovery time, and other data were compared between the three groups.

MAIN RESULTS

Demographic values, duration of surgery, and consumption of propofol and fentanyl were not different between the three groups. Group 3 patients regained consciousness with significantly higher propofol concentration (mean PCp = 3.2 mg/L) compared with those in Groups 1 and 2 (p < 0.05). However, the BIS values at both recovery endpoints were not different among the three groups.

CONCLUSIONS

The plasma levels of fentanyl affect the concentrations of propofol required for patients to regain consciousness. The BIS values for wakefulness are unaltered at the different combinations of propofol and fentanyl concentrations. Thus, the BIS appears to be a useful and consistent indicator for level of consciousness during emergence from propofol/fentanyl intravenous anesthesia.

[A clinical study of total intravenous anesthesia by using mainly propofol, fentanyl and ketamine--with special reference to its safety based on 26,079 cases]

During a period of five years from January 1996 through December 2000 total intravenous anesthesia with mainly propofol, fentanyl and ketamine was administered to 26,079 patients including cardiac and neurosurgical patients at the University of Hirosaki Hospital and five other affiliated hospitals. The patients studied ranged from 1 year 8 months to 93 years in age, 9.2 kg to 135.0 kg in body weight and from 18 min to 22 hours 50 min in anesthetic time. With adequate monitoring, fentanyl 1-2 micrograms.kg-1 was given at first, then total-dose of ketamine 1 mg.kg-1 and propofol 1-2 mg.kg-1 were administered for the induction of anesthesia in adult patients. A total dose of fentanyl 3-15 micrograms.kg-1 was given combined with propofol 5-10 mg.kg-1 and ketamine 0.3-1.0 mg.kg.h-1. In craniotomy patients, ketamine was excluded. For pediatric patients, sevoflurane anesthesia was employed to establish i.v. route, and intravenous agents were given almost same as in the same manner as in adult patients. None of them developed either cardiac arrest or severe cardiovascular insufficiencies due to anesthesia alone. Their postoperative hepatic and renal functions evaluated by various biochemical indices and urine output were adequately maintained during anesthesia and for a week postoperatively. They were followed up to 3 months postoperatively only to fail to detect any adverse events related directly to this method of anesthesia. These data suggest that total intravenous anesthesia with propofol, fentanyl and ketamine has a very wide margin of safety.

[Does a high inspired oxygen concentration consistently play a key role in developing combustion in the airway during fiberoptic bronchoscopy guided laser treatment?--A case of firing in the airway under total intravenous anesthesia]

We experienced combustion of a fiberoptic bronchoscope and an endotracheal tube, as well as tracheo-bronchial burn during a diode laser treatment in a hypoxemic patient requiring continuous oxygen administration. Total intravenous anesthesia and a high concentration of inspired oxygen (FIO2 0.60) were used for the procedure. The complication occurred abruptly at the beginning of the second treatment after the first uneventful 15 min treatment. Several reports suggest that laser treatment can be performed even under FIO2 1.0 without firing in the airway, and a high FIO2 itself would not consistently play a key role in developing combustion in the airway, even though combustion is more vigorous when a higher FIO2 is used. Based on our experience and reports of firing in the airway during laser treatment, the following recommendations are presented. The laser treatment should be done (1) at the FIO2 just enough to maintain adequate oxygenation in each individual patient, (2) at the greatest possible distance between a bronchoscope and an endotracheal tube, and (3) after removing small pieces of carbonized tissues produced by each laser treatment.

Tumor necrosis factor-alpha reduces ketamine- and propofol-induced anesthesia time in rats

Tumor necrosis factor-alpha (TNFalpha) is a crucial neuromodulator in the brain. TNFalpha is involved in many physiological events including pain response and sleep. However, the interactions between TNFalpha and anesthetics have not been elucidated yet. In the present study, we investigated the effects of four intracerebroventricular (ICV) doses (1, 10, and 100 pg, and 1 ng) and two intraperitoneal (IP) doses (10 and 100 ng) of TNFalpha on anesthesia time of ketamine (100 mg/kg IP) and propofol (80 mg/kg IP) in rats. All ICV doses of TNFalpha reduced anesthesia time of ketamine and propofol compared with the saline ICV group (ketamine control group, 45.4 +/- 6.5 min; propofol control group, 43.5 +/- 11.0 min). The maximum effect was obtained after the ICV injection of 10 pg of TNFalpha (76% and 54% of ketamine and propofol control groups, respectively). Anesthesia time of ketamine or propofol was also decreased by IP injection of TNFalpha in a dose-dependent manner. Injection of 100 ng of TNFalpha IP reduced anesthesia time of ketamine and propofol by 67% and 64% of each control group, respectively. These data show that TNFalpha can modulate the anesthesia time of IV anesthetics, suggesting that anesthetic requirements might be altered in the presence of cerebral or systemic inflammation.

IMPLICATIONS

Tumor necrosis factor alpha (TNFalpha) regulates many physiological events in the brain. We investigated the effects of TNFalpha on anesthesia time in rats. Both central and peripheral administration of TNFalpha decreased anesthesia time induced by ketamine and propofol.

Inhibitory effects of intravenous anaesthetic agents on K(+)-evoked glutamate release from rat cerebrocortical slices. Involvement of voltage-sensitive Ca(2+) channels and GABA(A) receptors

It is widely accepted that most general anaesthetic agents depress the central nervous system (CNS) by potentiation or activation of the GABA(A) receptor-mediated Cl(-) conductance. These agents also reportedly inhibit voltage-sensitive Ca(2+) channels (VSCCs), thus depressing excitatory transmission in the CNS. However, in this regard there are few functional data at the level of neurotransmitter release. In this study we examined the effects of VSCC antagonists and a range of intravenous anaesthetic agents on K(+)(40 mM)-evoked glutamate release from rat cerebrocortical slices in the absence and presence of the GABA(A) receptor antagonist bicuculline (100 microM). We employed both selective and non-selective VSCC antagonists, the anaesthetic barbiturates thiopental, pentobarbital and phenobarbital, the non-anaesthetic barbiturate barbituric acid, the non-barbiturate anaesthetics alphaxalone, propofol and ketamine and the GABA(A) receptor agonist, muscimol. Glutamate released into the incubation medium was determined by a glutamate dehydrogenase-coupled assay. Omega-agatoxin IV(A) (P-type VSCC), omega-conotoxin MVII(C) (P/Q-type VSCC) and Cd(2+) (non-selective) essentially abolished glutamate release whilst nifedipine (L-type VSCC) and omega-conotoxin GVI(A) (N-type VSCC) reduced release by less than 30%. The concentrations producing 50% of the maximum inhibition (IC(50)) for thiopental, pentobarbital, phenobarbital, alphaxalone, propofol and ketamine were (in microM) 8.3, 22, 112, 6.3, 83 and 120, respectively. Barbituric acid produced a small (about 20%) inhibition. With the exception of ketamine, the IC(50) values for these anaesthetic agents were increased threefold by bicuculline (100 microM). In addition, muscimol significantly inhibited release by 26% with an IC(50) of 1.1 microM. In summary, a range of anaesthetic agents at clinically achievable concentrations inhibit glutamate release and this inhibition of release appears to be due mainly to direct inhibition of P/Q-type VSCCs, although activation of the GABA(A) receptor plays a role in this response.

Flurbiprofen does not change the bispectral index and 95% spectral edge frequency during total intravenous anaesthesia with propofol and fentanyl

BACKGROUND AND OBJECTIVE

Previous studies have shown that general anaesthetic agents modulate the production of hypothalamic prostaglandins (PG) D2 and E2, which are mediators of sleep and wakefulness respectively. Although flurbiprofen, a cyclo-oxygenase inhibitor, is used clinically as a non-steroidal anti-inflammatory agent and postoperative analgesic, it reduces prostaglandin production. Thus, this agent may affect the depth of sedation during general anaesthesia. In this study, we examined if flurbiprofen affects the bispectral index, which correlates with sedation levels.

METHODS

Fifteen patients who underwent elective surgery under total intravenous anaesthesia with propofol and fentanyl were studied. The sedation level was monitored using a bispectral index monitor. On attainment of stable haemodynamics and a bispectral index, patients were given flurbiprofen axetil 50 mg intravenously. A bispectral index and 95% spectral edge frequency were recorded before and 5, 10, 15, 20 and 30 min after flurbiprofen axetil intravenously.

RESULTS

Bispectral indexes of 51.7 (95% CI: 47.3-56.8), 51.7 (47.1-56.3), 51.3 (46.3-56.3), 50.3 (45.8-54.2), 48.9 (43.6-54.1) and 50.3 (45.5-55.2) at 0, 5, 10, 15, 20, 30 min after flurbiprofen axetil intravenously were observed. There was no change in this or 95% spectral edge frequency.

CONCLUSIONS

Clinical dose of flurbiprofen axetil does not alter the bispectral index and 95% spectral edge frequency under total intravenous anaesthesia with propofol and fentanyl.

[The death dates of Seishu Hanaoka's patients with breast cancer: a report of newly identified three patients]

Among 155 patients with breast cancer treated by Seishu Hanaoka the exact death dates of only five patients including Kan Aiya, the first to have received a tumour excision under general anesthesia are known to us and the remaining 149 patients remain unclarified concerning their death dates. The reason is mainly due to a fact that the descriptions of "Nyugan Seimei Roku" (A Name List of Breast Cancer Patients) are inaccurate. According to recent field survey on the burial records of several temples which have been described in the "Nyugan Seimei Roku," the author could clarify the death dates of two patients. The one is the wife of Kohfuku-ji Temple's priest who died on Feb 20, 1813, and the other in the wife of Honko-ji Temple's priest, died on July 8, 1834. Both survived 1 year 4 months, and 1 year 3 months, postoperatively. One more patient's death date is identified by chance. Consequently, the death dates of eight patients among 155 have been identified so far.

Quantification and comparison of pulmonary emboli formation after pneumatic tourniquet release in patients undergoing reconstruction of anterior cruciate ligament and total knee arthroplasty

The amount of emboli formed (percentage of total emboli area to the right atrial area [%Ae]) after tourniquet release in invasive procedures of the medullary cavity is empirically much larger than that in noninvasive procedures, even if the tourniquet duration is similar. Thus, we compared %Ae between arthroscopic reconstruction of the anterior cruciate ligament (ACL, n = 20) and total knee arthroplasty (TKA, n = 20). The right atrium was continuously monitored by transesophageal echocardiography to assess %Ae. Peak %Ae +/- SD (ACL, 4.1% +/- 3.4%; TKA, 20.7% +/- 16.7%) appeared 30-40 s after tourniquet release in both groups. However, %Ae in the TKA group was always larger than the peak %Ae in the ACL group. In addition, although the ET(CO(2)) significantly increased after tourniquet release in both groups, increase of ET(CO(2)) (1.1% +/- 0.3%) in the ACL group was significantly larger than that in the TKA group (0.5% +/- 0.2%). An increase in ET(CO(2)) was inversely proportional to peak %Ae (P < 0.01; r = 0.703). Therefore, the present data suggest that the risk of acute pulmonary embolism after tourniquet release may be more frequent during TKA than ACL.

IMPLICATIONS

We compared emboli formation after tourniquet release in patients undergoing arthroscopic reconstruction of the anterior cruciate ligament (ACL, n = 20) and total knee arthroplasty (TKA, n = 20) using transesophageal echocardiography. The present data suggest that the risk of acute pulmonary embolism after tourniquet release could be more frequent during TKA than ACL.