Terminal Anaesthesia Research Articles

Comparison of oral and vaginal misoprostol for cervical ripening before manual vacuum aspiration of first trimester pregnancy under local anesthesia: a randomized placebo-controlled study

The objective of this prospective randomized placebo-controlled study was to determine the effectiveness of 400 μg oral and 400 μg vaginal misoprostol administration for cervical priming 3 h prior to manual vacuum aspiration (MVA) under local anesthesia for voluntary termination of pregnancy before 10 weeks of gestation in comparison with placebo oral or placebo vaginal administration ( n=40 in each group). Postmedication cervical dilatation was similar in the oral (mean, 6.6±1.5) and vaginal (mean, 7.2±0.8) misoprostol groups but significantly higher compared with the oral (mean, 3.4±0.2) and vaginal (mean, 3.6±1.9) placebo groups. Duration of the procedure was also significantly shorter in the misoprostol groups in comparison with their placebo counterparts. Preoperative bleeding and side effects were more common in the misoprostol groups, but none required medical intervention. Intraoperative bleeding was less in the vaginal misoprostol group compared with the placebo groups. There was no significant difference in terms of visual analogue scores during the procedure, patient satisfaction, days of postoperative bleeding and rate of postoperative complications among the groups. Cervical priming with misoprostol administered orally or vaginally 3 h before MVA for termination of pregnancy under local anesthesia facilitates the procedure by decreasing the need for cervical dilatation and by shortening its duration without improving patients' pain perception and satisfaction mainly due to side effects.

Transient Changes in Cortical Glucose and Lactate Levels Associated with Peri-Infarct Depolarisations, Studied with Rapid-Sampling Microdialysis

Peri-infarct depolarisations (PIDs) contribute to infarct expansion in experimental focal ischaemia; furthermore, depolarisations propagate in the injured human brain. Glucose utilisation is increased under both conditions, and depletion of brain glucose carries a poor prognosis. We studied dynamics of cerebral glucose and lactate in relation to PID patterns in experimental stroke. The middle cerebral artery was occluded for 3 h in 23 cats under terminal chloralose anaesthesia. We used fluorescence imaging to detect occurrence of PIDs, and rapid-sampling online microdialysis (rsMD), coupled to a flow-injection assay, to examine changes in cerebral cortical extracellular glucose and lactate at intervals of 30 sec each. After 30 min' ischaemia, lactate had increased by 43.6+/-s.d. 45.9 micromol/L, and stabilised in that range for 3 h. In contrast, glucose fell only slightly initially (11.9+/-9.7 micromol/L), but progressively decreased to a reduction of 56.7+/-47.2 micromol/L at 3 h, with no evidence of stabilisation. There was a highly significant inverse relationship of frequency of PIDs with plasma glucose (P<0.001). The results also characterise a metabolic signature for PIDs for possible application in clinical work, and emphasise potential risks in the use of insulin to control plasma glucose in patients with brain injury.

Attaching-effacing Lesions Associated with Escherichia coli O157:H7 and Other Bacteria in Experimentally Infected Conventional Neonatal Goats

Four conventionally reared goats aged 6 days were inoculated orally with approximately 10(10) colony-forming units (cfu) of a non-verotoxigenic strain of Escherichia coli O157:H7. All remained clinically normal. Tissues were sampled under terminal anaesthesia at 24 (two animals), 48 and 72 h post-inoculation (hpi). E. coli O157:H7 was cultured from the ileum, caecum, colon and rectum of all animals, but the number of bacteria recovered at these sites varied between animals. Attaching-effacing (AE) lesions associated with O157 organisms, as confirmed by immunolabelling, were observed in the ileum of one of the two animals examined at 24 hpi, and in the ileum, caecum and proximal colon of an animal examined at 72 hpi. E. coli O157 organisms were detected at > or =10(5) cfu/g of tissue at these sites. In addition, AE lesions associated with unidentified bacteria were observed at various sites in the large bowel of the same animals. Lesions containing both E. coli O157 and unidentified bacteria (non-O157) were not observed. Non-O157 AE lesions were also observed in the large bowel of one of two uninoculated control animals. This indicated that three (one control and two inoculated) animals were colonized with an unidentified AE organism before the commencement of the experiment. The O157-associated AE lesions were observed only in animals colonized by non-O157 AE organisms and this raises questions about individual host susceptibility to AE lesions and whether non-O157 AE organisms influence colonization by E. coli O157.

Effects of gestational age and cortisol treatment on ovine fetal heart function in a novel biventricular Langendorff preparation

Structural and functional maturation of a number of fetal organs and physiological systems occurs in the immediate period prior to term, in association with the prepartum increase in fetal plasma cortisol concentration. At present, little is known about how myocardial sensitivity to adrenergic and muscarinic cholinergic stimulation changes as the fetus approaches term, nor the role of the prepartum increase in plasma cortisol concentration in mediating these changes. This study used a novel Langendorff, biventricular, ovine fetal heart preparation to investigate the effects of advancing gestation and cortisol treatment on myocardial sensitivity to adrenergic (isoprenaline) and muscarinic cholinergic (carbachol) stimulation. It was hypothesized that cortisol infusion would fully mimic developmental changes in myocardial responsiveness to adrenergic and cholinergic stimulation. Sixteen Welsh Mountain sheep fetuses were surgically prepared under general anaesthesia with vascular catheters. At 125 +/- 1 days gestational age (dGA; term, 145 dGA) fetuses were infused with saline vehicle (n= 7; Premature Control) or with cortisol (n= 4; 2-3 mg kg(-1) d(-1)i.v.; Premature Cortisol) for 5 days. The Term Control group (n= 5) comprised fetuses that were surgically prepared at 130 dGA and infused with vehicle for 5 days prior to delivery (n= 2), or that received no surgery (n= 3). Under terminal anaesthesia, Premature Control and Premature Cortisol fetuses were delivered at 130 dGA and Term Control fetuses between 135 and 143 dGA. Following exsanguination under anaesthesia, fetal hearts were mounted in the Langendorff preparation, allowing measurement of left ventricular (LV) developed pressure and right ventricular (RV) developed pressure, heart rate (HR), coronary perfusion pressure and perfusate distribution to the myocardium. Cortisol infusion elevated fetal plasma cortisol concentrations to values similar to those measured close to term (45.0 +/- 7.1 ng ml(-1)). Advancing gestational age, but not cortisol treatment, enhanced fetal LV developed pressure, RV developed pressure and HR responses to carbachol (P < 0.05). Advancing gestational age, but not cortisol treatment, suppressed fetal LV developed pressure, RV developed pressure and HR responses to isoprenaline (P < 0.05). Maximum doses of either carbachol or isoprenaline had no effect on coronary perfusate distribution. Changes in myocardial responsiveness to adrenergic and muscarinic cholinergic stimulation with advancing gestation provide mechanisms that contribute to the maturation of the cardiovascular system as the ovine fetus approaches term. These changes in myocardial responsiveness are not solely dependent on preparturient elevations in fetal plasma cortisol concentration.

Interaction of spinal nitric oxide and prostaglandins after L5-L6 spinal nerve ligation in the rat: an isobolographic analysis.

Interaction of spinal nitric oxide and prostaglandins after L5-L6 spinal nerve ligation in the rat: an isobolographic analysis.

Quantitative evidence for continuing axonal pathology after optic nerve stretch‐injury

Introduction: Stretch‐injury to the optic nerve of the guinea‐pig results in cytoskeletal pathology. We tested the hypothesis that post‐traumatic changes may continue up to 1 week after injury.Material and methods: Six animals were injured under controlled conditions. Under terminal anaesthesia, three controls and three animals were killed at 24 h or 1 week. Unbiased stereological analysis of the axonal cytoskeleton was undertaken.Results: At 4 h, 20% of nerve fibres are injured (Jafari et al. J Neurotrauma 1998; 15: 955). In the present study, no evidence for a change in the proportion of injured nerve fibres at longer survivals was obtained. At 24 h, three types of injured fibre occur: (i) some are compacted as at 4 h; (ii) some, termed ‘degenerating’, show loss/increased spacing between neurofilaments and microtubules (P = 0.005); and (iii) in some, empty myelin figures occur. At 7 days, both degenerating fibres and empty myelin figures are increased (P = 0.032).Conclusions: These results demonstrate that injured nerve fibres undergo secondary axotomy between 4 and 24 h and there are increased numbers of degenerating fibres at 7 days. However, not all injured fibres undergo axotomy between 4 and 24 h, because, at 7 days fibres undergoing axotomy are present.

Dexamethasone for the Prevention of Nausea and Vomiting After Dilatation and Curettage

In Brief OBJECTIVE To evaluate the efficacy and safety of dexamethasone administered intravenously at three different doses (4 mg, 8 mg, 16 mg) for the prevention of nausea and vomiting after dilatation and curettage. METHODS In a prospective, randomized, double-masked, placebo-controlled trial, 120 women received placebo or dexamethasone intravenously at doses of 4 mg, 8 mg, or 16 mg immediately before induction of anesthesia (n = 30 in each group). Propofol-based general anesthetic was used. Emetic episodes and safety assessments were performed. To estimate a sufficient sample size, it was calculated that 30 patients per group would be required with α = .05 and β = .2. RESULTS The rate of patients who were emesis-free (no nausea, retching, or vomiting) 0–24 hours after anesthesia was 57% with dexamethasone 4 mg (P = .796), 87% with dexamethasone 8 mg (P = .005), and 87% with dexamethasone 16 mg (P = .005), compared with placebo (50%). Patients who had received dexamethasone 8 mg or 16 mg were more satisfied than those who had received placebo (P < .05). No clinically important adverse events were observed in any of the groups. CONCLUSION Dexamethasone 8 mg is an effective antiemetic for preventing postoperative nausea and vomiting 0–24 hours after anesthesia in women undergoing propofol-based general anesthesia for termination of pregnancy. Increasing the dose to 16 mg provided no additional benefit. Dexamethasone 8 mg is an effective antiemetic for preventing postoperative nausea and vomiting 0–24 hours after anesthesia in women undergoing propofol-based general anesthesia for termination of pregnancy.

Dexamethasone for the prevention of nausea and vomiting after dilatation and curettage: a randomized controlled trial

OBJECTIVE: To evaluate the efficacy and safety of dexamethasone administered intravenously at three different doses (4 mg, 8 mg, 16 mg) for the prevention of nausea and vomiting after dilatation and curettage. METHODS: In a prospective, randomized, double-masked, placebo-controlled trial, 120 women received placebo or dexamethasone intravenously at doses of 4 mg, 8 mg, or 16 mg immediately before induction of anesthesia ( n = 30 in each group). Propofol-based general anesthetic was used. Emetic episodes and safety assessments were performed. To estimate a sufficient sample size, it was calculated that 30 patients per group would be required with α = .05 and β = .2. RESULTS: The rate of patients who were emesis-free (no nausea, retching, or vomiting) 0–24 hours after anesthesia was 57% with dexamethasone 4 mg ( P = .796), 87% with dexamethasone 8 mg ( P = .005), and 87% with dexamethasone 16 mg ( P = .005), compared with placebo (50%). Patients who had received dexamethasone 8 mg or 16 mg were more satisfied than those who had received placebo ( P < .05). No clinically important adverse events were observed in any of the groups. CONCLUSION: Dexamethasone 8 mg is an effective antiemetic for preventing postoperative nausea and vomiting 0–24 hours after anesthesia in women undergoing propofol-based general anesthesia for termination of pregnancy. Increasing the dose to 16 mg provided no additional benefit.

Reduction in CNS scar formation without concomitant increase in axon regeneration following treatment of adult rat brain with a combination of antibodies to TGFbeta1 and beta2.

In this study we investigated whether CNS axons regenerate following attenuation of scar formation using a combination of antibodies against two isoforms of transforming growth factor beta (TGFbeta). Anaesthetized adult rats were given unilateral mechanical lesions of the nigrostriatal tract. Implantation of transcranial cannulae allowed wounds to be treated with a combination of antibodies against TGFbeta1 and TGFbeta2 once daily for 10 days postaxotomy. Eleven days post-transection brains from animals under terminal anaesthesia were recovered for histological evaluation. Gliosis, inflammation and the response of dopaminergic nigral axons were assessed by immunolabelling. Treatment with antibodies against TGFbeta1 and TGFbeta2 attenuated (but did not abolish) the response of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes and of NG2-immunoreactive glia but did not attenuate the response of CR3-immunoreactive microglia and macrophages. However, this reduction in scar formation was not accompanied by growth of cut dopaminergic nigral axons. We conclude that treatment of injured adult rat brain with a combination of antibodies against TGFbeta1 and TGFbeta2 results in a reduction of scar formation but that this is not sufficient to enhance spontaneous long distance CNS axon regeneration.

Attaching and effacing lesions caused by Escherichia coli O157:H7 in experimentally inoculated neonatal lambs.

Four 6-day-old conventionally reared lambs were inoculated orally with a total of 10(9) cfu comprising equal numbers of four enterohaemorrhagic Escherichia coli (EHEC) O157:H7 strains. All animals remained clinically normal. Tissues were sampled under terminal anaesthesia at 12, 36, 60 and 84 h post inoculation (hpi). EHEC O157:H7 was cultured from most gastrointestinal tract sites. Small, sparse attaching and effacing (AE) lesions were found in the caecum at 12 and 36 hpi and in the terminal colon and rectum at 84 hpi. Organisms in the lesions were labelled specifically by an O157 antiserum. The results indicate that the well-characterised mechanisms for intimate attachment encoded by the locus for enterocyte effacement (LEE) of EHEC O157:H7 may contribute to the initial events, at least, of colonisation of sheep.

Structural and functional abnormalities of the hippocampal formation in rats with environmentally induced reductions in prepulse inhibition of acoustic startle

The effects of social isolation on prepulse inhibition of acoustic startle (PPI), electrophysiology and morphology of subicular pyramidal neurons and the densities of interneuronal sub-types in the hippocampal formation were examined. Wistar rats (male weanlings) were housed socially (socials, n=8) or individually (isolates, n=7). When tested eight weeks later, PPI was lower in isolates. Rats then received terminal anaesthesia before slices of hippocampal formation were made in which the electrophysiological properties of a total of 108 subicular neurons were characterized. There were no differences in neuronal sub-types recorded in socials compared with isolates. Intrinsically burst-firing and regular spiking pyramidal neurons were examined in detail. There were no differences in resting membrane potential or input resistance in isolates compared with socials but action potential height was reduced and action potential threshold raised in isolates. A limited morphological examination of Neurobiotin-filled intrinsically burst-firing neurons did not reveal differences in cell-body area or in number of primary dendrites. Sections from the contralateral hemispheres of the same rats were stained with antibodies to calretinin, parvalbumin and the neuronal isoform of nitric oxide synthase (nNOS). In isolates, the density of calretinin positive neurons was increased in the dentate gyrus but unchanged in areas CA3, CA1 and subiculum. Parvalbumin and nNOS positive neuronal densities were unchanged. Hence in rats with environmentally induced reductions in PPI there are structural and functional abnormalities in the hippocampal formation. If the reduction in PPI stems from these abnormalities, and reduced PPI in rats is relevant to schizophrenia, then drugs that correct the reported electrophysiological changes might have antipsychotic effects.

Adrenocortical Function in a New World Primate, the Marmoset Monkey, Callithrix jacchus

The function of the adrenal cortex of the marmoset monkey Callithrix jacchus has been investigated. In common with other New World primates, these animals seem to be glucocorticoid resistant. Blood and adrenal glands were obtained from male and female animals under terminal pentobarbitone anesthesia. Dispersed adrenal cell preparations were obtained by treatment with collagenase and incubated with ACTH1–24, (0.1–1000 nM) angiotensin II (0.1–1000 nM), dibutyryl cyclic AMP (dbcAMP; 30–1000 μM), and forskolin (FSK; 1–30 μM). Plasma cortisol levels (2113 ± 449 ng/ml male; 3858 ± 429 ng/ml female) were found to be 10- to 20-fold higher than those quoted for Old World primates and man. The cell preparations showed no significant response to any dose of ACTH tested (0.1–1000 nM), although addition of exogenous precursor (22R-hydroxycholesterol, 2.5 μM) resulted in an increased yield of cortisol and aldosterone. Cyclic AMP production was increased in response to forskolin (1–30 μM) but not ACTH1–24 (1–1000 nM). In addition, dose-related responses to angiotensin II (maximal stimulation of 316 ± 49% basal aldosterone at 100 nM angiotensin II), dbcAMP (maximal stimulation of 449 ± 24% basal cortisol at 300 μM dbcAMP), and forskolin (maximal stimulation of 394 ± 31% basal cortisol at 10 μM FSK) were obtained. The lack of a response in vitro to ACTH in C. jacchus cannot, therefore, be attributed either to general failure of the cells or to defects in postreceptor signaling mechanisms. The results suggest that there is a reduction in adrenal ACTH receptor number or affinity, with a high basal production rate in vivo maintaining the elevated plasma cortisol levels.

Studies on the Orbital Heating Organ of the Swordfish (Xiphias Gladius) using Microvascular Corrosion Casting

Abstract The swordfish ﹛Xiphias gladius), as well as billfishes (Istiophoridae), shows a conspicuous modification of one of its eye muscles: the dorsal rectus muscle. While the other eye muscles show an apparently normal, oculomotoric structure, the musculus rectus dorsalis is modified for heat production. While the remaining oculomotoric portion of this muscle shows normal muscular cells, the bulk of the organ is composed of cells structurally similar to brown adipose tissue (BAT) and blood vessels. The BAT cells are capable of direct (i.e., non-shivering) metabolic heat production. This heat is then transported and disseminated by the blood vessels in this organ. Microvascular corrosion casting is an excellent technique for studying the morphology of complicate vascular networks. However, studies using this technique on eye muscle vasculature are not frequently found in the literature. Juvenile swordfish, 1.4-1.8kg bodyweight, were collected in the Ionic sea. Immediately after catching, terminal anaesthesia was carried out with tricaine-methanesulfonate.

Occlusion of blood flow by high-intensity focused ultrasound

This work investigates the possiblity of occluding blood flow (in vivo) using high-intensity focused ultrasound surgery (FUS). Such an effect could be used, for example, in the noninvasive treatment of foetal dysfunctions. A high-power 1.7-MHz, 150-mm focal length, piezoelectric transducer was used to expose rat femoral vessels to a free field I−SP=4660 W cm−2 for 2 s under terminal anaesthesia. Initially, eight separate exposures were used. Later experiments were aimed at determining an optimal single exposure to produce flow occlusion. Before and after exposure, magnetic resonance FISP 3-D angiograms (MRA) with submillimeter spatial resolution were acquired using a Siemens Vision MR System (1.5T) and extremity coil. In all animals, MRA showed reduced blood flow both in the treated region and distal to it. The results of single-dose optimization will be discussed. The ability to curtail blood flow using FUS allows the possibility of treating Foeto-Foetal Transfusion Syndrome by occluding the placental shunt vessels responsible for vascular inbalance in identical twins. Currently available interventional treatments (surgery or intrauterine laser therapy) have significant mortality and morbidity. The FUS has the advantage of being noninvasive. [Work was funded by the UK Medical Research Council.]

Dysregulation of cytokine expression in tubulointerstitial nephritis associated with murine malaria

Dysregulation of cytokine expression in tubulointerstitial nephritis associated with murine malaria

Minimum Alveolar Concentration of Halothane and Enflurane Are Decreased in Early Pregnancy

Comment: The authors of both this paper determining MAC of halothane and enflurane and then-earlier paper1 examining MAC of isoflurane in humans during the first trimester of pregnancy are to be congratulated. They not only showed a significant fall in MAC by eight weeks gestation but also demonstrated a readily available, simple, and noninvasive stimulus to effectively test for MAC in the human, that being a tetanic ulnar nerve stimulation. In addition, the study was safe and ethical to perform in informed patients. The attention to detail of the history of absent drug ingestion including birth control pills, the omission of pre-medication, and the use of only the inhalation anesthetic studied insured the validity of the results. The significant 27 to 35% decrease of MAC (of halothane, enflurane, or isoflurane) by eight weeks gestation is of extreme importance to every anesthetist who may be called not only to administer anesthesia for termination of the first trimester or completion of a spontaneous abortion but equally important to anesthetize a gravid patient requiring nonobstetric surgery such as an appendectomy. Awareness of this decrease in MAC, regardless of its explanation, is important to avoid overdosing of the first trimester gravid patient. It is known that pregnancy significantly decreases equivalently the amount of local anesthetic required for epidural block compared with the nongravid woman of the same age. Interestingly, Fagraeus and colleagues2 showed that a 30% decrease occurred at a similar time in the first trimester.

Comparison of Eltanolone and Propofol in Anesthesia for Termination of Pregnancy

Comparison of Eltanolone and Propofol in Anesthesia for Termination of Pregnancy

Effects of fentanyl or alfentanil as supplement to propofol anaesthesia for termination of pregnancy

One hundred and twenty patients undergoing early legal termination of pregnancy by dilatation and suction curettage before 12 weeks of pregnancy were randomly allocated to receive total intravenous propofol anaesthesia either alone or supplemented with fentanyl 1.5 micrograms.kg-1 or alfentanil 15 micrograms.kg-1. Supplementation with fentanyl or alfentanil improved operating conditions (P < 0.01), reduced total propofol requirements (P < 0.01) and reduced postoperative pain intensity (P < 0.05). Immediate recovery, assessed by the time patients took to open the eyes, to give correct date of birth and by co-operation score, was more rapid in the alfentanil group compared to the control group (P < 0.05), whereas there was no significant difference between the alfentanil and fentanyl groups. The three anaesthetic techniques did not differ with regard to side effects. In conclusion, total intravenous propofol anaesthesia in patients undergoing early termination of pregnancy was improved by supplementation with either fentanyl 1.5 micrograms.kg-1 or alfentanil 15 micrograms.kg-1. The benefit was slightly greater with alfentanil than with fentanyl.

Comparison of eltanolone and propofol in anesthesia for termination of pregnancy

A randomized study was designed to compare eltanolone (pregnanolone) and propofol anesthesia in 60 unpremedicated women undergoing outpatient termination of pregnancy. The initial doses for induction of anesthesia were 0.8 mg/kg for eltanolone and 2 mg/kg for propofol followed by an additional 25% i

Gastro-oesophageal reflux and regurgitation during general anaesthesia for termination of pregnancy

Gastro-oesophageal reflux (GOR) and regurgitation were investigated with an oesophageal pH electrode, inserted after the induction of general anaesthesia with methohexitone, in 100 patients undergoing termination of pregnancy, 50 in the first trimester and 50 in the second. GOR occurred in 17 patients, 8 in the first trimester and 9 in the second trimester. On withdrawal of the pH electrode into the pharynx it was found that only 2 of these patients had regurgitated, 1 from each trimester. Regurgitation was not clinically detectable and there was no pulmonary aspiration. Twenty three patients had hiccup of whom 10 refluxed, 9 of them immediately after starting to hiccup. Those patients with hiccup were more likely to reflux than the remainder ( P < 0.001). Patients with preoperative symptoms of GOR had no greater incidence of reflux during anaesthesia than those without symptoms. The function of the upper oesophageal sphincter appears to be preserved in the majority of these patients with the general anaesthetic technique used. This work therefore suggests that the need for rapid sequence induction is no greater in the second trimester than the first.