Propofol versus isoflurane anesthesia under hypothermic conditions: effects on intracranial pressure and local cerebral blood flow after diffuse traumatic brain injury in the rat

Genetic Differences Modify Anesthetic Preconditioning of Traumatic Brain Injury in Drosophila

Pre-clinical vertebrate models of traumatic brain injury (TBI) routinely use anesthetics for animal welfare; however, humans experience TBI without anesthetics. Therefore, translation of findings from vertebrate models to humans hinges on understanding how anesthetics influence cellular and molecular events that lead to secondary injuries following TBI. To investigate the effects of anesthetics on TBI outcomes, we used an invertebrate Drosophila melanogaster model to compare outcomes between animals exposed or not exposed to anesthetics prior to the same primary injury. Using a common laboratory fly line, w1118, we found that exposure to the volatile anesthetics isoflurane or sevoflurane, but not ether, prior to TBI produced a dose-dependent reduction in mortality within 24 h following TBI. Thus, isoflurane and sevoflurane precondition w1118 flies to deleterious effects of TBI. To examine the effects of genetic differences on anesthetic preconditioning of TBI, we repeated the experiment with the Drosophila Genetic Reference Panel (DGRP) collection of genetically diverse, inbred fly lines. Pre-exposure to either isoflurane or sevoflurane revealed a wide range of preconditioning levels among 171 and 144 DGRP lines, respectively, suggesting a genetic component for variation in anesthetic preconditioning of mortality following TBI. Finally, genome-wide association study analyses identified single-nucleotide polymorphisms in genes associated with isoflurane or sevoflurane preconditioning of TBI. Several of the genes, including the fly ortholog of mammalian Calcium Voltage-Gated Subunit Alpha1 D (CACNA1D), are highly expressed in neurons and are functionally linked to both anesthetics and TBI. These data indicate that anesthetic dose and genetic background should be considered when investigating effects of anesthetics in vertebrate TBI models, and they support use of the fly model for elucidating the mechanisms underlying anesthetic preconditioning of TBI.

Propofol effects in rodent models of traumatic brain injury: a systematic review

Background

Traumatic brain injury (TBI) causes high mortality and disability worldwide. Animal models have been developed to explore the complex processes in TBI. Propofol is used to manage head injuries during surgical intervention and mechanical ventilation in patients with TBI. Many studies have investigated the neuroprotective effect of propofol on TBI. However, other studies have shown neurotoxic effects.

Objectives

To review systematically the literature regarding the neuroprotective and neurotoxic effects of propofol in rodent models of TBI.

Methods

Data from rodents as models of TBI with propofol as one of the intervention agents, and/or comparing the neuroprotective effects of propofol with the other substances in rodent models of TBI, were obtained from PubMed, EBSCO Host, and ProQuest databases. The PRISMA 2020 statement recommendations were followed and research questions were developed based on PICOS guidelines. Data was extracted from the literature using a standardized Cochrane method.

Results

We analyzed data from 12 articles on physiological changes of experimental animals before and after trauma, the effects of propofol administration, and the observed neurotoxic effects. The effects of propofol administration were observed in terms of changes in traumatic lesion volume, the release of antioxidants and inflammatory factors, and the neurological function of rodent models of TBI.

Conclusion

Propofol has neuroprotective and neurotoxic effects via several mechanisms, and various doses have been used in research to determine its effects. The timing of administration, the dose administered, and the duration of administration contribute to determine the effect of propofol in rodent models of TBI. However, the doses that produce neuroprotective and neurotoxic effects are not yet clear and further research is needed to determine them.

Cerebrovascular Response to Propofol, Fentanyl, and Midazolam in Moderate/Severe Traumatic Brain Injury: A Scoping Systematic Review of the Human and Animal Literature

Intravenous propofol, fentanyl, and midazolam are utilized commonly in critical care for metabolic suppression and anesthesia. The impact of propofol, fentanyl, and midazolam on cerebrovasculature and cerebral blood flow (CBF) is unclear in traumatic brain injury (TBI) and may carry important implications, as care is shifting to focus on cerebrovascular reactivity monitoring/directed therapies. The aim of this study was to perform a scoping review of the literature on the cerebrovascular/CBF effects of propofol, fentanyl, and midazolam in human patients with moderate/severe TBI and animal models with TBI. A search of MEDLINE, BIOSIS, EMBASE, Global Health, SCOPUS, and the Cochrane Library from inception to May 2020 was performed. All articles were included pertaining to the administration of propofol, fentanyl, and midazolam, in which the impact on CBF/cerebral vasculature was recorded. We identified 14 studies: 8 that evaluated propofol, 5 that evaluated fentanyl, and 2 that evaluated midazolam. All studies suffered from significant limitations, including: small sample size, and heterogeneous design and measurement techniques. In general, there was no significant change seen in CBF/cerebrovascular response to administration of propofol, fentanyl, or midazolam during experiments where PCO2 and mean arterial pressure (MAP) were controlled. This review highlights the current knowledge gap surrounding the impact of commonly utilized sedative drugs in TBI care. This work supports the need for dedicated studies, both experimental and human-based, evaluating the impact of these drugs on CBF and cerebrovascular reactivity/response in TBI.

A Systematic Review of Closed Head Injury Models of Mild Traumatic Brain Injury in Mice and Rats

Mild TBI (mTBI) is a significant health concern. Animal models of mTBI are essential for understanding mechanisms, and pathological outcomes, as well as to test therapeutic interventions. A variety of closed head models of mTBI that incorporate different aspects (i.e., biomechanics) of the mTBI have been reported. The aim of the current review was to compile a comprehensive list of the closed head mTBI rodent models, along with the common data elements, and outcomes, with the goal to summarize the current state of the field. Publications were identified from a search of PubMed and Web of Science and screened for eligibility following PRISMA guidelines. Articles were included that were closed head injuries in which the authors classified the injury as mild in rats or mice. Injury model and animal-specific common data elements, as well as behavioral and histological outcomes, were collected and compiled from a total of 402 articles. Our results outline the wide variety of methods used to model mTBI. We also discovered that female rodents and both young and aged animals are under-represented in experimental mTBI studies. Our findings will aid in providing context comparing the injury models and provide a starting point for the selection of the most appropriate model of mTBI to address a specific hypothesis. We believe this review will be a useful starting place for determining what has been done and what knowledge is missing in the field to reduce the burden of mTBI.

Propofol attenuates the increase of sonographic optic nerve sheath diameter during robot-assisted laparoscopic prostatectomy: a randomized clinical trial

Background

Robot-assisted laparoscopic prostatectomy (RALP) requires pneumoperitoneum and the Trendelenburg position to optimize surgical exposure, which can increase intracranial pressure (ICP). Anesthetic agents also influence ICP. We compared the effects of propofol and sevoflurane on sonographic optic nerve sheath diameter (ONSD) as a surrogate for ICP in prostate cancer patients who underwent RALP.

Methods

Thirty-six patients were randomly allocated to groups receiving propofol (propofol group, n = 18) or sevoflurane (sevoflurane group, n = 18) anesthesia. The ONSD was measured 10 min after induction of anesthesia in the supine position (T1); 5 min (T2), 30 min (T3), and 60 min (T4) after establishing pneumoperitoneum and the Trendelenburg position; and at the end of surgery after desufflation in the supine position (T5). Respiratory and hemodynamic variables were also evaluated.

Results

The ONSD was significantly different between the propofol group and the sevoflurane group at T4 (5.27 ± 0.35 mm vs. 5.57 ± 0.28 mm, P = 0.007), but not at other time points. The ONSDs at T2, T3, T4, and T5 were significantly greater than at T1 in both groups (all P < 0.001). Arterial carbon dioxide partial pressure, arterial oxygen partial pressure, peak airway pressure, plateau airway pressure, systolic blood pressure, pulse pressure variation, body temperature and regional cerebral oxygen saturation, except heart rate, were not significantly different between the two groups.

Conclusions

The ONSD was significantly lower during propofol anesthesia than during sevoflurane anesthesia 60 min after pneumoperitoneum and the Trendelenburg position, suggesting that propofol anesthesia may help minimize ICP changes in robotic prostatectomy patients.

Trial registration

Clinicaltrials.gov identifier: NCT03271502. Registered August 31, 2017.

Selective Brain Hypothermia Mitigates Brain Damage and Improves Neurological Outcome after Post-Traumatic Decompressive Craniectomy in Mice

Hypothermia and decompressive craniectomy (DC) have been considered as treatment for traumatic brain injury. The present study investigates whether selective brain hypothermia added to craniectomy could improve neurological outcome after brain trauma. Male CD-1 mice were assigned into the following groups: sham; DC; closed head injury (CHI); CHI followed by craniectomy (CHI+DC); and CHI+DC followed by focal hypothermia (CHI+DC+H). At 24 h post-trauma, animals were subjected to Neurological Severity Score (NSS) test and Beam Balance Score test. At the same time point, magnetic resonance imaging using a 9.4 Tesla scanner and subsequent volumetric evaluation of edema and contusion were performed. Thereafter, the animals were sacrificed and subjected to histopathological analysis. According to NSS, there was a significant impairment among all the groups subjected to trauma. Animals with both trauma and craniectomy performed significantly worse than animals with craniectomy alone. This deleterious effect disappeared when additional hypothermia was applied. BBS was significantly worse in the CHI and CHI+DC groups, but not in the CHI+DC+H group, compared to the sham animals. Edema and contusion volumes were significantly increased in CHI+DC animals, but not in the CHI+DC+H group, compared to the DC group. Histopathological analysis showed that neuronal loss and contusional blossoming could be attenuated by application of selective brain hypothermia. Selective brain cooling applied post-trauma and craniectomy improved neurological function and reduced structural damage and may be therefore an alternative to complication-burdened systemic hypothermia. Clinical studies are recommended in order to explore the potential of this treatment.

Aqueous Date Fruit Efficiency as Preventing Traumatic Brain Deterioration and Improving Pathological Parameters after Traumatic Brain Injury in Male Rats

Objective

Following traumatic brain injury, disruption of blood-brain-barrier and consequent brain edema are critical events which might lead to increasing intracranial pressure (ICP), and nerve damage. The current study assessed the effects of aqueous date fruit extract (ADFE) on the aforementioned parameters.

Materials and Methods

In this experimental study, diffused traumatic brain injury (TBI) was generated in adult male rats using Marmarou’s method. Experimental groups include two pre-treatment (oral ADFE, 4 and 8 mL/kg for 14 days), vehicle (distilled water, for 14 days) and sham groups. Brain edema and neuronal injury were measured 72 hours after TBI. Veterinary coma scale (VCS) and ICP were determined at -1, 4, 24, 48 and 72 hours after TBI. Differences among multiple groups were assessed using ANOVA. Turkey’s test was employed for the ANOVA post-hoc analysis. The criterion of statistical significance was sign at P<0.05.

Results

Brain water content in ADFE-treated groups was decreased in comparison with the TBI+vehicle group. VCS at 24, 48 and 72 hours after TBI showed a significant increase in ADFE groups in comparison with the TBI+vehicle group. ICP at 24, 48 and 72 hours after TBI, was decreased in ADFE groups, compared to the TBI+vehicle. Brain edema, ICP and neuronal injury were also decreased in ADFE group, but VCS was increased following on TBI.

Conclusion

ADFE pre-treatment demonstrated an efficient method for preventing traumatic brain deterioration and improving pathological parameters after TBI.

Pathological alterations and stress responses near DBS electrodes after MRI scans at 7.0T, 3.0T and 1.5T: an in vivo comparative study

OBJECTIVE

The purpose of this study was to investigate the pathological alterations and the stress responses around deep brain stimulation (DBS) electrodes after magnetic resonance imaging (MRI) scans at 7.0T, 3.0T and 1.5T.

MATERIALS AND METHODS

DBS devices were stereotactically implanted into the brains of New Zealand rabbits, targeting the left nucleus ventralis posterior thalami, while on the right side, a puncture passage pointing to the same target was made. MRI scans at 7.0T, 3.0T and 1.5T were performed using transmit/receive head coils. The pathological alterations of the surrounding tissue were evaluated by hematoxylin and eosin staining (H&E staining) and transmission electron microscopy (TEM). The levels of the 70 kDa heat shock protein (HSP-70), Neuronal Nuclei (NeuN) and Caspase-3 were determined by western-blotting and quantitative polymerase chain reaction (QPCR) to assess the stress responses near the DBS electrodes.

RESULTS

H&E staining and TEM showed that the injury around the DBS electrodes was featured by a central puncture passage with gradually weakened injurious alterations. Comparisons of the injury across the groups manifested similar pathological alterations near the DBS electrodes in each group. Moreover, western-blotting and QPCR assay showed that the level of HSP-70 was not elevated by MRI scans (p>0.05), and the levels of NeuN and Caspase-3 were equal in each group, regardless of the field strengths applied (p>0.05).

CONCLUSIONS

Based on these findings, it is reasonable to conclude that in this study the MRI scans at multiple levels failed to induce additional tissue injury around the DBS electrodes. These preliminary data furthered our understanding of MRI-related DBS heating and encouraged revisions of the current MRI guidelines for patients with DBS devices.

Using anesthetics and analgesics in experimental traumatic brain injury

Valid modeling of traumatic brain injury (TBI) requires accurate replication of both the mechanical forces that cause the primary injury and the conditions that lead to secondary injuries observed in human patients. The use of animals in TBI research is justified by the lack of in vitro or computer models that can sufficiently replicate the complex pathological processes involved. Measures to reduce nociception and distress must be implemented, but the administration of anesthetics and analgesics can influence TBI outcomes, threatening the validity of the research. In this review, the authors present evidence for the interference of anesthetics and analgesics in the natural course of brain injury in animal models of TBI. They suggest that drugs should be selected for or excluded from experimental TBI protocols on the basis of IACUC-approved experimental objectives in order to protect animal welfare and preserve the validity of TBI models.

Effect of melatonin on intracranial pressure and brain edema following traumatic brain injury: role of oxidative stresses

BACKGROUND AND AIMS

Traumatic brain injury (TBI) is one of the main causes of brain edema and increased intracranial pressure (ICP). In the clinic it is essential to limit the development of ICP after TBI. In the present study, the effects of melatonin on these parameters at different time points and alterations of oxidant factors as one of the probable involved mechanisms have been evaluated.

METHODS

Albino N-Mary rats were divided into five groups of sham, TBI, TBI + vehicle, TBI + Mel5 and TBI + Mel20. Brain injury was induced by Marmarou method. Melatonin was injected i.p. at 1, 24, 48 and 72 h after brain trauma. Brain water and Evans blue dye contents as well as oxidant/antioxidant factors were measured 72 h after TBI. ICP and neurological scores were determined at -1, 1, 24, 48 and 72 h post-TBI.

RESULTS

Brain water and Evans blue dye contents in melatonin-treated groups decreased as compared to the TBI + vehicle group (p <0.001). Veterinary coma scale (VCS) at 24, 48 and 72 h after TBI showed a significant increase in melatonin groups (TBI + Mel5: p <0.01 and TBI + Mel20: p <0.001) in comparison to the TBI + vehicle group. ICP at 24, 48 and 72 h after TBI decreased in melatonin groups as compared to the TBI + vehicle group (p <0.001). Superoxide dismutase and glutathione peroxidase activities showed a significant increase, whereas malondialdehyde level in these groups was significantly lower in melatonin groups in comparison to the TBI + vehicle group (p <0.001).

CONCLUSION

Melatonin decreases brain edema, BBB permeability and ICP, but increases VCS after TBI. These effects are probably due to inhibition of oxidative stress.

Measurements of RF heating during 3.0-T MRI of a pig implanted with deep brain stimulator

PURPOSE

To present preliminary, in vivo temperature measurements during MRI of a pig implanted with a deep brain stimulation (DBS) system.

MATERIALS AND METHODS

DBS system (Medtronic Inc., Minneapolis, MN) was implanted in the brain of an anesthetized pig. 3.0-T MRI was performed with a T/R head coil using the low-SAR GRE EPI and IR-prepped GRE sequences (SAR: 0.42 and 0.39 W/kg, respectively), and the high-SAR 4-echo RF spin echo (SAR: 2.9 W/kg). Fluoroptic thermometry was used to directly measure RF-related heating at the DBS electrodes, and at the implantable pulse generator (IPG). For reference the measurements were repeated in the same pig at 1.5 T and, at both field strengths, in a phantom.

RESULTS

At 3.0T, the maximal temperature elevations at DBS electrodes were 0.46 °C and 2.3 °C, for the low- and high-SAR sequences, respectively. No heating was observed on the implanted IPG during any of the measurements. Measurements of in vivo heating differed from those obtained in the phantom.

CONCLUSION

The 3.0-T MRI using GRE EPI and IR-prepped GRE sequences resulted in local temperature elevations at DBS electrodes of no more than 0.46 °C. Although no extrapolation should be made to human exams and much further study will be needed, these preliminary data are encouraging for the future use 3.0-T MRI in patients with DBS.

Volatile isoflurane sedation in cerebrovascular intensive care patients using AnaConDa(®): effects on cerebral oxygenation, circulation, and pressure

PURPOSE

The anesthetic-conserving device AnaConDa(®), a miniature vaporizer, allows volatile sedation in the intensive care unit (ICU). We investigated the effects of isoflurane sedation on cerebral and systemic physiology parameters in neuromonitored ICU stroke patients.

METHODS

Included in the study were 19 consecutive ventilated patients with intracerebral hemorrhage (12), subarachnoid hemorrhage (4), and ischemic stroke (3) who were switched from intravenous propofol or midazolam to inhalative isoflurane sedation for an average of 3.5 days. During the sedation transition, the following parameters were assessed: mean arterial pressure (MAP), intracranial pressure (ICP), cerebral perfusion pressure (CPP), middle cerebral artery mean flow velocity (MFV) and cerebral fractional tissue oxygen extraction (FTOE), as well as systemic cardiopulmonary parameters and administered drugs.

RESULTS

After the first hour, mean ICP showed an increase of 2.1 mmHg that was not clinically relevant. Likewise, MFV did not change. MAP and CPP, however, decreased by 6.5 and 6.3 mmHg, respectively. FTOE was reduced slightly from 0.24 to 0.21 (p = 0.03). Over an observation period of 12 h, ICP remained stable, while MAP and thus CPP showed distinct decreases (CPP: -10 mmHg at 6 h, p < 0.001; -7.5 mmHg at 12 h, p = 0.005, when compared to preswitch levels) despite a 1.5-fold increase in vasopressor administration.

CONCLUSIONS

We suggest that that it is possible to reach sufficient sedation levels in cerebrovascular ICU patients by applying volatile isoflurane long-term without a relevant increase in ICP, if baseline ICP values are low or only moderately elevated. However, caution should be exercised in view of isoflurane's decreasing effect on MAP and CPP. Multimodal neuromonitoring is strongly recommended when applying this off-label sedation method.

Effect of sex steroid hormones on brain edema, intracranial pressure, and neurologic outcomes after traumatic brain injury

Recent studies have reported that estrogen and progesterone have a neuroprotective effect after traumatic brain injury (TBI); however, the mechanism(s) for this effect have not yet been elucidated. The aim of the present study was to investigate the role of sex steroid hormones on changes in brain edema, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) after TBI in ovariectomized (OVX) rats. In this study, 50 female rats were divided into 5 groups: control (intact), sham, and 3 TBI groups consisting of vehicle, estrogen (1 mg/kg), and progesterone (8 mg/kg). TBI was induced by the Marmarou method, and the hormones were injected i.p. 30 min after TBI. ICP was measured in the spinal cord, and CPP was calculated by subtracting the mean arterial pressure (MAP) from ICP. The results revealed that brain water content after TBI was lower (p < 0.001) in the estrogen and progesterone groups than in the vehicle group. After trauma, ICP was significantly higher in TBI rats (p < 0.001). The ICP in the estrogen and progesterone groups decreased at 4 and 24 h after TBI compared with vehicle (p < 0.001 and p < 0.05, respectively). The CPP in the estrogen and progesterone groups increased after 24 h compared with vehicle (p < 0.001). Also after TBI, the neurological score (veterinary coma scale) was significantly higher than vehicle at 1 h (p < 0.01) and 24 h (p < 0.001) in the group treated with estrogen. In conclusion, pharmacological doses of estrogen and progesterone improved ICP, CPP, and neurological scores after TBI in OVX rats, which implies that these hormones play a neuroprotective role in TBI.

The antiinflammatory effects of propofol in endotoxemic rats during moderate and mild hypothermia

PURPOSE

We previously found that propofol attenuated the mortality rate and inflammatory responses during endotoxemia in rats; however, whether propofol retains its antiinflammatory effects during hypothermia has not been determined. We investigated the effects of propofol on endotoxemic rats subjected to moderate or mild hypothermia.

METHODS

Male Wistar rats (n = 88) were anesthetized intraperitoneally with pentobarbital sodium and assigned to one of two protocols: one representing moderate hypothermia (30 degrees -32 degrees C) and the other representing mild hypothermia (33 degrees -35 degrees C). Each protocol included four equal-sized groups: group A, Escherichia coli endotoxin (15 mg x kg(-1), i.v.) and normothermia; group B, propofol (10 mg x kg(-1) x h(-1), i.v.) and normothermia after endotoxin injection; group C, endotoxin (15 mg x kg(-1), i.v.) and hypothermia; and group D, propofol (10 mg x kg(-1) x h(-1), i.v.) and hypothermia after endotoxin injection. Rats then were warmed or cooled to maintain rectal temperatures as above for 6 h. The mortality rate was assessed up to 6 h after endotoxin injection. In addition, we assessed hemodynamics, acid-base status, and plasma cytokine concentrations.

RESULTS

Endotoxemic rats developed hypotension and metabolic acidosis as well as increased plasma cytokine concentrations. Mortality rates 6 h after endotoxin injection were 70%, 40%, 10%, and 0% for groups A-D, respectively, at moderate hypothermia. Propofol administration to endotoxemic rats with hypothermia, whether moderate or mild, also attenuated the high mortality rate, metabolic acidosis, and elevation of cytokines, but these effects were not superior to those of hypothermia alone.

CONCLUSION

During hypothermia, propofol administration does not have additive beneficial antiinflammatory effects.

Propofol is associated with impaired brain metabolism during hypothermic circulatory arrest: an experimental microdialysis study

BACKGROUND

Propofol is a widely used anesthetic in cardiac surgery. It has been shown to increase cerebrovascular resistance resulting in decreased cerebral blood flow. Efficient brain perfusion and tissue oxygenation during cardiopulmonary bypass (CPB) is essential in surgery requiring hypothermic circulatory arrest (HCA). The effects of propofol on brain metabolism are reported in a surviving porcine model of HCA.

METHODS

Twenty female juvenile pigs undergoing 75 minutes of HCA at a brain temperature of 18 degrees C were assigned to either propofol- or isoflurane anesthesia combined with alpha-stat perfusion strategy during CPB cooling and rewarming. Brain microdialysis analysis was used for determination of brain metabolism, and tissue oxygen partial pressure and intracranial pressures were also followed-up until 8 hours postoperatively.

RESULTS

Brain concentrations of glutamate and glycerol were significantly higher in the propofol group throughout the experiment (P < .01 and P < .01, respectively). The lactate/pyruvate ratio was significantly higher in the propofol group at 6-, 7-, and 8-hour intervals (P < .05, P < .01, and P < .05, respectively). The intracranial pressure was significantly higher at the 8-hour postoperative interval (P < .05) in the propofol group. A trend toward higher brain oxygen concentrations was observed in the isoflurane group.

CONCLUSIONS

Anesthesia with propofol as compared with isoflurane is associated with impaired brain metabolism during experimental HCA.

The Effect of Electroencephalogram-Targeted High- and Low-Dose Propofol Infusion on Histopathological Damage After Traumatic Brain Injury in the Rat

BACKGROUND

Propofol is commonly used to sedate patients after traumatic brain injury. However, the dose-dependent neuroprotective effects of propofol after head trauma are unknown. We compared histopathological damage after 6 h of electroencephalogram-targeted high- and low-dose propofol infusion in rats subjected to controlled cortical impact (CCI).

METHODS

Animals were randomly assigned to CCI/propofol with electroencephalogram burst-suppression-ratio 1%-5% (CCI/lowprop), CCI/propofol with burst-suppression-ratio 30%-40% (CCI/highprop), control group CCI/1.0 vol % halothane (CCI/halo), or sham group with halothane anesthesia (SHAM/halo). Brain slices were stained with kresyl violet (KV) and hematoxylin/eosin (HE) to evaluate lesion volume, number of eosinophilic cells, and activation of caspase-3 in the hippocampus.

RESULTS

Lesion volume (mm3) and number of eosinophilic cells in the hippocampus did not differ significantly [lesion volumes: CCI/lowprop 31.55 +/- 14.66 (KV) and 53.77 +/- 8.62 (HE); CCI/highprop 33.81 +/- 10.57 (KV) and 52.30 +/- 11.55 (HE); CCI/halo 36.42 +/- 17.06 (KV) and 57.95 +/- 8.49 (HE)]. Activation of caspase-3 occurred in the ipsilateral hippocampus in all CCI-groups.

CONCLUSION

Despite different levels of cortical neuronal function, there were no relevant differences in the short-term histopathological damage. These results challenge the view that the neuroprotective effect of propofol relates to the suppression of cerebral metabolic demand.

Total intravenous anaesthesia with propofol and remifentanil for elective neurosurgical procedures

BACKGROUND AND OBJECTIVES

This was a prospective audit to assess the incidence and characteristics of early postoperative complications in the recovery room in extubated patients after elective neurosurgical procedures using propofol and remifentanil-based total intravenous anaesthesia.

METHODS

Vital signs (temperature, conscious level, respiratory rate, oxygen saturation, pulse and blood pressure) and postoperative complications (shivering, nausea, vomiting and cardiorespiratory) were analysed in 145 adult patients over a 1-yr period.

RESULTS

The overall shivering, postoperative nausea and vomiting and postoperative hypertension (systolic blood pressure more than 25% of the preoperative value) incidences were 30.3%, 16.6% and 35.2%, respectively. Fifty-one percent of the patients had at least one of the above complications. The complication rates were found to be widely different among various types of neurosurgery. The surgical procedures were divided into five groups: supratentorial craniotomy, posterior fossa craniotomy, intracranial vascular procedures, transphenoidal hypophysectomy and extracranial procedures. Median extubation time was similar in all groups and patients were fully conscious with no hypoxia in the recovery room. The intracranial vascular group had the highest shivering and postoperative nausea and vomiting rates (58.8% and 29.4%, respectively). In the supratentorial craniotomy group, 46% of the patients had hypertension. The overall complication rate (presence of any complications) was highest in the supratentfial craniotomy (55.4%), posterior fossa craniotomy (75%) and intracranial vascular (76.5%) groups. Shivering and overall complication rate was significantly related to the anaesthetic time (P<or=0.001 and 0.02, respectively).

CONCLUSIONS

Despite the potential advantages of total intravenous anaesthesia in titratability, rapid return of consciousness and reduced respiratory complications, making it suitable for planned extubation at the end of neurosurgery, the postoperative complications of shivering, postoperative nausea and vomiting and hypertension were still high.

Hyperglycolysis is exacerbated after traumatic brain injury with fentanyl vs. isoflurane anesthesia in rats

Despite common use of narcotics in the clinical management of severe traumatic brain injury (TBI), in experimental models rats treated with fentanyl have exhibited worse functional outcome and more CA1 hippocampal death than rats treated with standard isoflurane anesthesia. We hypothesized that greater post-traumatic excitotoxicity, reflected by cerebral glucose utilization (CMRglu), may account for detrimental effects of fentanyl vs. isoflurane. Rats were anesthetized with either isoflurane (1% by inhalation) or fentanyl (10 mcg/kg iv bolus then 50 mcg/kg/h infusion). 14C-deoxyglucose autoradiography was performed 45 min after controlled cortical impact (CCI) to left parietal cortex (n=4 per anesthetic group) or in uninjured rats after 45 min of anesthesia (n=3 per anesthetic group). Uninjured rats treated with fentanyl vs. isoflurane showed 35-45% higher CMRglu in all brain structures (p<0.05) except CA3. After TBI in rats treated with isoflurane, CMRglu increased significantly only in ipsilateral CA1 and ipsilateral parietal cortex (p<0.05 vs. isoflurane uninjured). Conversely, after TBI in rats treated with fentanyl, CMRglu increased markedly and bilaterally in CA1 and CA3 (p<0.05 vs. fentanyl uninjured), but not ipsilateral parietal cortex. In contralateral CA1, CMRglu was nearly two times greater after TBI in fentanyl vs. isoflurane treated rats (p<0.05). Hyperglycolysis was exacerbated in CA1 and CA3 hippocampus after TBI in rats treated with fentanyl vs. isoflurane anesthesia. This post-traumatic hyperglycolysis suggests greater excitotoxicity and concurs with reports of worse functional outcome and more CA1 hippocampal death after TBI with fentanyl vs. isoflurane anesthesia.

Anesthetic management for clipping a giant basilar artery aneurysm with moderate hypothermia, extracorporeal circulation assistance, and propofol infusion

A 65-year-old female patient underwent surgery to clip a giant basilar artery aneurysm with closed-chest extracorporeal circulation using femorofemoral bypass. Moderate hypothermia (27 degrees C-30 degrees C), retention of spontaneous circulation, and propofol infusion (3-5 mg. kg(-1). h(-1)) were used under general anesthesia. Blood outflow via femoral vein was sufficient to maintain cardiopulmonary bypass and to induce hypothermia. Hemodynamics were controlled with dopamine and noradrenaline. In this case, extracorporeal circulation under moderate hypothermia was used to assist rather than substitute for spontaneous circulation, and spontaneous circulation was maintained at all times. We think that this method had advantages over deep hypothermic circulatory arrest with regard to intraoperative risks and postoperative complications.

Validation and comparison of the use of diuresis cystometry and retrograde filling cystometry at various infusion rates in female Beagle dogs

OBJECTIVES

To compare retrograde filling cystometry at infusion rates of 5, 10, and 20 mL/min with diuresis cystometry for determination of an appropriate infusion rate and to confirm the reproducibility of measurements obtained by urethral pressure profilometry (UPP) and cystometry in female Beagles.

ANIMALS

Adult female Beagles.

PROCEDURE

Successive UPP and cystometry were performed by use of a water perfusion catheter on dogs anesthetized with propofol. Dogs randomly underwent each of the following at 1-week intervals: retrograde filling cystometry at 5, 10, and 20 mL/min, and diuresis cystometry. The maximum urethral pressure and closure pressure, functional and anatomic profile lengths, threshold pressure, threshold volume, and compliance were measured.

RESULTS

For each UPP variable, significant differences were found among dogs, but no significant differences were found in intra- or interstudy measurements for individual dogs. For retrograde filling cystometry, threshold pressure was not significantly different between a 5 and 10 mL/min infusion rate. Threshold pressure was significantly higher during retrograde filling cystometry at 20 mL/min, compared with 5 and 10 mL/min, and was associated with bladder wall damages. Threshold pressure was significantly lower during diuresis cystometry, compared with retrograde filling cystometries. Threshold volume and compliance were not significantly different among retrograde filling cystometries but were significantly higher during diuresis cystometry.

CONCLUSIONS AND CLINICAL RELEVANCE

Retrograde filling cystometry at 20 mL/min leads to unacceptable sudden increase in threshold bladder pressure. Retrograde filling cystometry at 10 mL/min can be recommended in a clinical setting, shortening the anesthesia time. However, diuresis cystometry approximates physiologic bladder filling most accurately.