The effects of nitrous oxide and ketamine on the bispectral index and 95% spectral edge frequency during propofol-fentanyl anaesthesia

In this study, we have sought to establish whether N2O and ketamine alter the bispectral index during propofol-fentanyl anaesthesia. Fourteen surgical patients were randomly assigned to one of two groups: the N2O group (n = 7) and the ketamine group (n = 7). In both groups, anaesthesia was induced with propofol 1.5-2 mg kg-1 and fentanyl 2 micrograms kg-1 and maintained with propofol 5-7 mg kg-1 hr-1 to target the bispectral index between 40 and 50. After the bispectral index value had stabilized the propofol infusion rate was fixed. In the N2O group, the following concentrations of N2O were subsequently inhaled at 20-min intervals; 20, 40, 60 and 70%, and then N2O was terminated. In the ketamine group, ketamine (0.4 mg kg-1 + 1.0 mg kg-1h-1) was given. The bispectral index and 95% spectral edge frequency were recorded 20 min after each change in concentration of N2O or ketamine infusion. The bispectral index and 95% spectral edge frequency did not change significantly in the N2O group, but increased significantly from 44.1 +/- 0.7 and 16.0 +/- 0.5 to 58.6 +/- 1.4 and 19.5 +/- 0.3 (P < 0.01), respectively, in the ketamine group. Additional N2O or ketamine did not decrease the bispectral index and 95% spectral edge frequency values. The depth of sedation should be assessed carefully using a bispectral index monitor when these anaesthetic agents are used together.     

Droperidol inhibits tracheal contraction induced by serotonin,histamine or carbachol in guinea pigs

Purpose

Droperidol (D) is effective in the treatment of patients with status asthmaticus. It has been reported that D inhibits the bronchoconstriction induced by serotonin (5-HT) but not that by histamine (H) or acetylcholine. However, haloperidol, another butyrophenone, is known to interact with and inhibit calmodulin, an intracellular Ca⁺⁺-binding protein which is important in the contraction of smooth muscles. The present study was designed to investigate the effects of D on tracheal contractions induced by 5-HT, H or carbachol (C) and to determine the contribution of α-adrenoceptors to the relaxant effect of D in vitro.

Methods

Tracheas of female guinea pigs were cut spirally into strips and mounted in water-jacketed organ baths in Tyrode’s solution, aerated with a mixture of 95% O₂ and 5% CO₂ at 37°C. The changes in isometric tension induced by each spasmogen in the strips were measured with a transducer and a polygraph.

Results

We found that D inhibited the tracheal contractions induced by 5-HT, H or C in a concentration-dependent manner. At 1.25 × 10^?6 M D blocked the effect of 10^?4 M 5-HT by 44.1 ± 4.3% and at 2.5 × 10^?6 M by 63.8 ± 3.8%. Similarly, at 5.0 × 10^?6 M concentration, D blocked the effect of 10^?5 M H by 27.7 ± 5.3% and at 10^?5 M by 56.2 ± 2.6%. Furthermore, 5 ×10^?6 M of D reduced the contractions produced by 10^?7 M C by 37.1 ± 3.0% and 70^?5 M of D by 76.1 ± 3.2%. The inhibiting effect of D was strongest on contractions induced by 5-HT. Prazosin (70^?6 M) affected neither 5-HT-induced contractions nor the inhibition by D.

Conclusion

Our data indicate that D partially blocks the contractile responses not only to 5-HT, an effect which would be mediated through a blockade of the 5-HT receptors, but also to H or C, probably through inhibition of calmodulin. Our data support previous reports indicating that droperidol may be an important therapeutic agent in the treatment of patients with hyperreactive airways.     

Plasma vasopressin response to contrast medium during cardiac catheterization in infants and children

Fifteen infants and children (M = 7, F = 8), aged from 0 to 13 years, who underwent cardiac catheterization and cardioangiography under ketamine-diazepam anesthesia were the subjects of this study. The effect of a contrast medium, isolamate sodium (66.8%) on the plasma somolality and vasopressin concentration was studied. The plasma osmolality was significantly elevated after contrast medium administration (289 ± 3 vs. 303 ± 8mosmol·kg^–1) as well as plasma vasopressin (from 2.1 ± 0.9 vs. 4.7 ± 2.0 micro-unit·ml^–1).It is concluded that the administration of contrast medium for cardioangiography causes elevation of plasma osmolality, which leads to the elevation of plasma vasopressin concentration.(Yamashita M, Horigome H, Kudo T, et al.: Plasma vasopressin response to contrast medium during cardiac catheterization in infants and children. J Anesth 5: 203–204, 1991)     

Does severe nutcracker phenomenon cause pediatric chronic fatigue?

BACKGROUND: In the past five years we experienced 9 fatigued disabled children who were intermittently or persistently absent from school. PATIENTS: They had been suspected to be burdened with psychosomatic disorders, having orthostatic hypotension, postural tachycardia, or other autonomic dysfunction symptoms. RESULTS: Investigating the cause of moderate orthostatic proteinuria in some of them, we found by chance severe typical nutcracker phenomenon (NC), which was present in all 9 children complaining of chronic fatigue. CONCLUSION: Their symptoms filled the criteria of chronic fatigue syndrome or idiopathic chronic fatigue (CFS/CF). An association between severe NC and autonomic dysfunction symptoms in children with CFS/CF has been presented.     

Biochemical, histological and echocardiographic changes during experimental cardiomyopathy in STZ-induced diabetic rats.

Diabetes mellitus is associated with an increased susceptibility to cardiovascular disease and it has been suggested that alterations in myocardial function may contribute to the development of diabetic cardiovascular complications. The objective of the present study is to examine the left ventricular (LV) function in streptozotocin (STZ)-induced diabetic rats in a definite course of time by non-invasive methods, i.e. M-mode and Doppler echocardiography. From the results, it was found that treatment of animals with STZ resulted in increase in blood glucose, triglycerides, cholesterol, low density lipoproteins (LDL) and decrease in serum total protein levels.Echocardiographic studies revealed that LV internal dimension (mm) during systole was significantly increased after 12 weeks of diabetes when compared to base line data of the same animals and with control animals 6.50+/-0.13 versus 4.25+/-0.17, versus 4.34+/-0.25 (P<0.05), however there was no significant change after 4-8 weeks of diabetes. Also LV internal dimension (mm) during end diastole increased significantly only after 12 weeks of diabetes than to base line data of the same animals and with control animals 7.71+/-0.34 versus 6.18+/-0.25, versus 6.25+/-0.18 (P<0.05). Fractional shortening (%), 15.69+/-5.1 versus 31.22+/-1.7, versus 30.56+/-2.1 (P<0.05), and ejection fraction (%) 37+/-2.31 versus 68.18+/-2.8, versus 60.32+/-3.5 (P<0.05), differ significantly after 12 weeks of diabetes when compared to base line data of the same animals and with control animals. E-wave (cm/s) was significantly decreased after 12 weeks of diabetes 21.11+/-1.5 versus 35.19+/-4.5, versus 32.75+/-3.0 (P<0.05), and A-wave (cm/s) was significantly increased after 12 weeks of diabetes 34.88+/-4.2 versus 19.21+/-2.8, versus 20.59+/-2.1 (P<0.05); thus, diabetic animals after 12 weeks had an inversed E/A ratio. Histological studies revealed that after 8 weeks of diabetes, necrosis was minimal, but after 12 weeks of diabetes extensive focal endomyocardial necrosis was observed. From this study, we conclude that overt LV systolic and diastolic dysfunction was fully visible at 12 weeks of diabetes on echocardiography and this non-invasive technique of echocardiography is useful in diagnosing LV dysfunction in diabetic rats without the need of invasive histopathological procedures.     

The influence of androgen deprivation therapy on dihydrotestosterone levels in the prostatic tissue of patients with prostate cancer.

PURPOSE: The influence of androgen deprivation therapy on dihydrotestosterone levels in the prostatic tissue is not clearly known. Changes in dihydrotestosterone levels in the prostatic tissue during androgen deprivation therapy in the same patients have not been reported. We analyzed dihydrotestosterone levels in prostatic tissue before and after androgen deprivation therapy. EXPERIMENTAL DESIGN: A total of 103 patients who were suspected of having prostate cancer underwent prostatic biopsy. Sixty-nine patients were diagnosed as having prostate cancer whereas the remaining 34 were negative. Serum samples were collected before biopsy or prostatectomy. Dihydrotestosterone levels in prostatic tissue and serum were analyzed using liquid chromatography/electrospray ionization-mass spectrometry after polar derivatization. In 30 of the patients with prostate cancer, dihydrotestosterone levels in prostatic tissue were determined by performing rebiopsy or with prostate tissues excised after 6 months on androgen deprivation therapy with castration and flutamide. RESULTS: Dihydrotestosterone levels in prostate tissue after androgen deprivation therapy remained at approximately 25% of the amount measured before androgen deprivation therapy. Dihydrotestosterone levels in serum decreased to approximately 7.5% after androgen deprivation therapy. The level of dihydrotestosterone in prostatic tissue before androgen deprivation therapy was not correlated with the serum level of testosterone. Serum levels of adrenal androgens were reduced to approximately 60% after androgen deprivation therapy. CONCLUSIONS: The source of dihydrotestosterone in prostatic tissue after androgen deprivation therapy involves intracrine production within the prostate, converting adrenal androgens to dihydrotestosterone. Dihydrotestosterone still remaining in prostate tissue after androgen deprivation therapy may require new therapies such as treatment with a combination of 5alpha-reductase inhibitors and antiandrogens, as well as castration.     

Bidirectional actions of docosahexaenoic acid on hippocampal neurotransmissions in vivo

Docosahexaenoic acid (DHA), a 22-carbon fatty acid with six double bonds, is one of the major polyunsaturated fatty acids in fish oils or in the mammalian central nervous system and is believed to be essential for neuronal plasticity and development. In the present study, we evaluated the effect of DHA on hippocampal neurotransmissions using anesthetized rats. Field excitatory postsynaptic potential (fEPSP) evoked by stimulation of the Schaffer collaterals was recorded from the CA1 stratum radiatum. Following intracerebroventricular injection of DHA 25 nmol, the fEPSP slope decreased gradually in 30 min and was eventually suppressed by about 30%. On the other hand, when fEPSP was evoked by stimulation of the perforant path was recorded in the molecular layer of the dentate gyrus, an increase in fEPSP slope occurred over a similar time course after DHA injection. These phenomena were independent of N-methyl-D-aspartate receptor activity. Linoleic acid, one of polyunsaturated fatty acids, was virtually ineffective. Furthermore, we investigated the effect of DHA on hippocampal synaptic plasticity. Although DHA did not alter the profile of paired-pulse facilitation, it inhibited the induction of long-term potentiation in the CA1 area but not in the dentate gyrus. Thus, DHA exerts regionally different effects on hippocampal neurotransmission and may be a good tool for clarifying physiological functions of the hippocampus.     

Haemodynamic comparison of propofol-fentanyl anaesthesia with midazolam-fentanyl anaesthesia in CABG patients without preoperative heart failure

This study was designed to compare prebypass haemodynamics under total intravenous anaesthesia (TIVA) using midazolam-fentanyl (group M) and propofol-fentanyl (group P) combinations. Sixteen adult patients undergoing CABG were studied with patients in group M and P (n = 8 each) given intravenous midazolam 0.1 mg.kg-1.h-1 and propofol 4 mg.kg-1.h-1 with fentanyl 25 micrograms.kg-1 until sternotomy, respectively. Following induction of anaesthesia, cardiac index and heart rate decreased significantly (30% and 20% in both groups, p < 0.05) these variables returned to baseline on completion of sternotomy. In addition, in group P mean arterial pressure decreased significantly (about 15%) following induction and there were no ischaemic signs. Overall for MAP there was no significant difference between the two groups. LVSWI and RVSWI were reduced by around 25% in both groups. Only the change in LVSWI reached statistical significance (p < 0.05). This reduction may have exert a caridioprotectant action by decreasing myocardial oxygen consumption. We conclude that both TIVA techniques represent an acceptable anaesthetic regimen for use in cardiac anaesthesia.     

Milrinone attenuates serotonin-induced pulmonary hypertension and bronchoconstriction in dogs

We determined whether milrinone, a phosphodiesterase III inhibitor, attenuates serotonin-induced (5-hydroxytryptamine [5HT]) pulmonary hypertension (PH) and bronchoconstriction. Dogs were anesthetized with pentobarbital (30 mg/kg + 2 mg. kg(-1). h(-1)). Bronchoconstriction and PH were elicited by 5HT (10 microg/kg + 1.0 mg. kg(-1). h(-1)). Pulmonary vascular resistance was used to assess PH. Bronchoconstriction was also assessed by changes in bronchial cross-sectional area obtained from our bronchoscopic method. At 30 min after 5HT infusion started, seven dogs were given milrinone: 0 (saline), 5, 50, 500, and 5000 microg/kg at 10-min intervals. The other 12 dogs were given milrinone 5000 microg/kg 30 min after 5HT infusion, and 5 min later were given propranolol 0.2 mg/kg (n = 6) or saline (n = 6) IV. The 5HT significantly increased percentage of pulmonary vascular resistance to 208% +/- 27% and decreased percentage of bronchial cross-sectional area to 52% +/- 5% of the basal. Milrinone significantly attenuated both PH and bronchoconstriction in a dose-dependent manner. However, -log 50% effective concentration (mean ED(50) in microg/kg) of milrinone for bronchoconstriction: 4.32 +/- 0.13 (47.6) was significantly smaller than that for PH: 3.84 +/- 0.29 (144.9) (P < 0.01). In addition, the spasmolytic effects of milrinone (5000 microg/kg) were not antagonized by propranolol, although this dose significantly increased plasma catecholamines. In conclusion, milrinone attenuates 5HT-induced PH and bronchoconstriction; however, this drug may be more sensitive to phosphodiesterase III in the airway smooth muscle than in pulmonary vascular smooth muscle. In addition, the relaxant effects could not be caused by beta-adrenoceptor activation because beta-blocker did not antagonize. IMPLICATIONS: We studied the effects of milrinone on serotonin-induced pulmonary hypertension and bronchoconstriction in dogs. Milrinone produces pulmonary vasodilation and bronchodilation, whose effects may not be caused by beta-adrenoceptor activation. In addition, this drug may be more sensitive to phosphodiesterase III in the airway smooth muscle than that in pulmonary vascular smooth muscle.