Search

Background Depth-of-anesthesia monitoring is often utilized for patients receiving xenon anesthesia. Processed electroencephalogram (EEG) depth-of-anesthesia monitoring relies to a significant extent on frequency domain analysis of the frontal EEG, and there is evidence that the spectral features observed under anesthesia vary significantly between anesthetic agents. The spectral features of the EEG during xenon anesthesia for a surgical procedure have not previously been described. Methods Twenty-four participants scheduled for general anesthesia for lithotripsy were randomized to receive either xenon anesthesia or sevoflurane anesthesia. Frontal EEG recordings were obtained from each participant via the Brain Anesthesia Response Monitor (BARM). Twenty-two EEG recordings were suitable for analysis: 11 in participants who received sevoflurane and 11 in participants who received xenon. Spectrograms for the duration of the anesthetic episode were produced for each participant. Group-level spectral analysis was calculated for two 30-second EEG epochs: one recorded at awake baseline and the other during maintenance anesthesia. A linear mixed-effects model was utilized to compare the changes in 5 frequency bands from baseline to maintenance between the 2 groups. Results The spectrograms of sevoflurane participants illustrate an increase in frontal delta (0.5-4 Hz), theta (4-8 Hz), and alpha (8-13 Hz) band power during maintenance anesthesia. In contrast, spectrograms of the xenon participants did not illustrate an increase in alpha power. The results of the linear mixed-effects model indicate that both agents were associated with a significant increase in delta power from baseline to maintenance. There was no significant difference in the magnitude of this increase observed between the agents. In contrast, sevoflurane anesthesia was associated with significantly greater absolute power in the theta, alpha, and beta (13-30 Hz) bands when compared to xenon. In terms of relative power, xenon was associated with a significant increase in delta power compared to sevoflurane, while sevoflurane was associated with greater increases in relative theta, alpha, and beta power. Conclusions Both xenon anesthesia and sevoflurane anesthesia were associated with significant increases in delta power. Sevoflurane anesthesia was also associated with increases in theta, alpha, and beta power, while xenon anesthesia was associated with greater consolidation of power in the delta band. Xenon anesthesia and sevoflurane anesthesia are associated with distinct spectral features. These findings suggest that appropriate depth-of-anesthesia monitoring may require the development of agent-specific spectral measures of unconsciousness.

Background Investigations of the electrophysiology of gaseous anesthetics xenon and nitrous oxide are limited revealing inconsistent frequency-dependent alterations in spectral power and functional connectivity. Here, the authors describe the effects of sedative, equivalent, stepwise levels of xenon and nitrous oxide administration on oscillatory source power using a crossover design to investigate shared and disparate mechanisms of gaseous xenon and nitrous oxide anesthesia. Methods Twenty-one healthy males underwent simultaneous magnetoencephalography and electroencephalography recordings. In separate sessions, sedative, equivalent subanesthetic doses of gaseous anesthetic agents nitrous oxide and xenon (0.25, 0.50, and 0.75 equivalent minimum alveolar concentration–awake [MACawake]) and 1.30 MACawake xenon (for loss of responsiveness) were administered. Source power in various frequency bands were computed and statistically assessed relative to a conscious/pre-gas baseline. Results Observed changes in spectral-band power (P < 0.005) were found to depend not only on the gas delivered, but also on the recording modality. While xenon was found to increase low-frequency band power only at loss of responsiveness in both source-reconstructed magnetoencephalographic (delta, 208.3%, 95% CI [135.7, 281.0%]; theta, 107.4%, 95% CI [63.5, 151.4%]) and electroencephalographic recordings (delta, 260.3%, 95% CI [225.7, 294.9%]; theta, 116.3%, 95% CI [72.6, 160.0%]), nitrous oxide only produced significant magnetoencephalographic high-frequency band increases (low gamma, 46.3%, 95% CI [34.6, 57.9%]; high gamma, 45.7%, 95% CI [34.5, 56.8%]). Nitrous oxide—not xenon—produced consistent topologic (frontal) magnetoencephalographic reductions in alpha power at 0.75 MACawake doses (44.4%; 95% CI [−50.1, −38.6%]), whereas electroencephalographically nitrous oxide produced maximal reductions in alpha power at submaximal levels (0.50 MACawake, −44.0%; 95% CI [−48.1,−40.0%]). Conclusions Electromagnetic source-level imaging revealed widespread power changes in xenon and nitrous oxide anesthesia, but failed to reveal clear universal features of action for these two gaseous anesthetics. Magnetoencephalographic and electroencephalographic power changes showed notable differences which will need to be taken into account to ensure the accurate monitoring of brain state during anaesthesia. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

A patient with a base of tongue tumor was judged to be safe to intubate under general anesthesia, with a new flexible tip "bougie." This enabled rapid and easy navigation around the distorted anatomy caused by the tumor. The bougie's tip can be flexed or extended by activating a slide on the shaft and was intended for use with the hyperangulated blade of a videolaryngoscope.

Anesthesia arguably provides one of the only systematic ways to study the neural correlates of global consciousness/unconsciousness. However to date most neuroimaging or neurophysiological investigations in humans have been confined to the study of γ-Amino-Butyric-Acid-(GABA)-receptor-agonist-based anesthetics, while the effects of dissociative N-Methyl-D-Aspartate-(NMDA)-receptor-antagonist-based anesthetics ketamine, nitrous oxide (N(2)O) and xenon (Xe) are largely unknown. This paper describes the methods underlying the simultaneous recording of magnetoencephalography (MEG) and electroencephalography (EEG) from healthy males during inhalation of the gaseous anesthetic agents N(2)O and Xe. Combining MEG and EEG data enables the assessment of electromagnetic brain activity during anesthesia at high temporal, and moderate spatial, resolution. Here we describe a detailed protocol, refined over multiple recording sessions, that includes subject recruitment, anesthesia equipment setup in the MEG scanner room, data collection and basic data analysis. In this protocol each participant is exposed to varying levels of Xe and N(2)O in a repeated measures cross-over design. Following relevant baseline recordings participants are exposed to step-wise increasing inspired concentrations of Xe and N(2)O of 8, 16, 24 and 42%, and 16, 32 and 47% respectively, during which their level of responsiveness is tracked with an auditory continuous performance task (aCPT). Results are presented for a number of recordings to highlight the sensor-level properties of the raw data, the spectral topography, the minimization of head movements, and the unequivocal level dependent effects on the auditory evoked responses. This paradigm describes a general approach to the recording of electromagnetic signals associated with the action of different kinds of gaseous anesthetics, which can be readily adapted to be used with volatile and intravenous anesthetic agents. It is expected that the method outlined can contribute to the understanding of the macro-scale mechanisms of anesthesia by enabling methodological extensions involving source space imaging and functional network analysis.

Elastomeric infusion pumps are used to deliver local anesthetic after surgery.[1][1],[2][2] Simplicity and portability are advantages over electronic pumps.[3][3] Such infusions can be continued at home, but unlike electronic pumps, the precise flow rates may be difficult to monitor.[4][4]

• Provides a 3D map to check the pathway of the access needle and its planned trajectory.

UNLABELLED The aim of this study was to compare hemodynamic responses to intubation and pin head-holder application in two groups of neurosurgical patients given oral clonidine (3 microg/kg) or oral temazepam (10-20 mg) 90 min before the induction of anesthesia. Fifty patients undergoing elective craniotomy were randomized to either group. Anesthesia was induced with i.v. propofol 1500 mg/h, fentanyl 4 microg/kg, vecuronium 0.15 mg/kg, and lidocaine 1.5 mg/kg and was maintained with propofol 6 mg x kg(-1) x h(-1). Mean arterial blood pressure (MAP) and heart rate were recorded before the induction of anesthesia and before and after intubation and application of the pin head holder. Interventions required to maintain hemodynamic stability were compared between groups. Preinduction sedation scores and MAP values were similar between groups. MAP was significantly lower (P = 0.031) in the clonidine group after pin head-holder application. Interventions to stabilize MAP were not significantly different between groups (P = 0.11). We conclude that clonidine is effective in reducing the MAP increase with pin head-holder application in patients undergoing craniotomy. IMPLICATIONS In this study, we investigated an approach to the prevention of increased blood pressure often seen during the early part of anesthesia for brain surgery. Oral clonidine was effective in reducing the mean arterial blood pressure increase resulting from pin head-holder application. Clonidine, a blood pressure-reducing drug, was given to 25 patients before anesthesia. Their blood pressure measurements were then compared with those of 25 patients not given clonidine.

Background Pain after craniotomy is often under-treated. Opiates carry distinct disadvantages. Non-steroidal anti-inflammatory drugs have an anti-platelet action and carry a bleeding risk. Cyclo-oxygenase 2 inhibitors such as parecoxib are not associated with a bleeding risk and would be welcome analgesics if shown to be effective. Methods In a prospective double-blind, randomized, placebo-controlled study, we investigated the analgesic effect of a single dose of parecoxib 40 mg given at dural closure in 82 patients undergoing elective craniotomies. Remifentanil was used intraoperatively, and i.v. morphine was titrated to the requirement in the post-anaesthetic unit. On the ward, i.m. morphine 5 mg as required and regular acetaminophen was prescribed. Morphine use and visual analogue pain scores were recorded at 1, 6, 12, and 24 h after surgery. Results Parecoxib reduced pain scores at 6 h and morphine use at 6 and 12 h after operation. However, overall, it had only minimal impact on postoperative analgesia. We found a wide variability in analgesic requirements where 11% of patients required no opioids and 16% required more than 15 mg i.v. morphine 1 h after the surgery. Conclusions We found only limited evidence to support parecoxib as an analgesic after craniotomy.

OBJECTIVES To compare high-frequency jet ventilation (HFJV) with spontaneous ventilation (SV) in general anesthesia for extracorporeal shock wave lithotripsy (ESWL). METHODS We conducted a retrospective review of 91 consecutive patients undergoing either HFJV with a Ben Jet airway or SV with a laryngeal mask airway, comparing the total number of shocks for stone ablation and the time in the post-anesthetic care unit between groups. Stone ablation rates on postoperative x-rays were compared. RESULTS The HFJV group needed significantly fewer shocks for stone ablation (median, 2000 versus 3000, P = 0.0001), and there was no difference in post-anesthetic care unit time. No patient in either group had significant clinical signs of ESWL-related tissue trauma. There was no difference in stone ablation rates on follow-up x-ray (HFJV 77% versus SV 74%). CONCLUSIONS This study supports the use of HFJV as a ventilation mode for ESWL when general anesthesia is chosen. Similar stone fragmentation rates can be achieved with fewer shocks, which may have beneficial effects, such as less pain and nausea, requiring further study.

Background Levobupivacaine is an effective local anaesthetic agent for nerve blockade with less systemic toxicity than racemic bupivacaine. The safety and efficacy of levobupivacaine for scalp blockade during awake craniotomy have not been addressed previously. Methods Serial arterial plasma levobupivacaine concentrations following scalp blockade were measured to 2 h in 10 patients booked for awake craniotomy for epilepsy or tumour surgery. Bilateral scalp blockade providing surgical anaesthesia was achieved with a mean dose of 177 mg (2.5 mg kg−1, range 1.6–3.2 mg kg−1) of levobupivacaine (0.5%, 5 mg ml−1) with epinephrine (5 μg ml−1) added immediately before the block insertion. Results The maximum measured plasma levobupivacaine concentration was 1.58 (0.44) μg ml−1 [mean ( sd )] with a mean time to peak plasma concentration of 12 (4) min. There were no episodes in any of the 10 patients of symptoms or signs suggestive of either CNS or CVS toxicity. Conclusions This study demonstrated a relatively rapid rise of plasma levobupivacaine concentration without evidence of cardiovascular or central nervous system sequelae in a sample population of patients who may be particularly prone to perioperative seizures.

The plasma levels of ropivacaine HCl with 5 mcg/mL epinephrine were measured in 10 patients following scalp blockade for awake craniotomy. A mean dose of 260 mg (3.6 mg/kg) resulted in peak plasma concentrations of 1.5 +/- 0.6 mcg/mL, with a median time to peak plasma concentration of 15 minutes. The pattern of rise of plasma level was similar in all patients and rapid compared with other regional blocks (epidural, intercostal, and axillary brachial plexus block). Despite this rapid rise of plasma level, no signs of cardiovascular or central nervous system toxicity were observed. In this group of patients undergoing awake craniotomy for excision of lesions in the eloquent areas of the cerebral cortex, ropivacaine HCl with epinephrine appeared to be a safe and effective local anesthetic agent in the dosages used.

We report the findings of a transperineal magnetic resonance image (MRI) guided biopsy of the prostate in a man with increasing prostate specific antigen who was not a candidate for a transrectal ultrasound guided biopsy.Using an open configuration 0.5 Tesla MRI scanner and pelvic coil, a random sextant sample was obtained under real time MRI guidance from the peripheral zone of the prostate gland as well as a single core from each MRI defined lesion. The patient had previously undergone proctocolectomy for ulcerative colitis and, therefore, was not a candidate for transrectal ultrasound guided biopsy. Prior attempts to make the diagnosis of prostate cancer using a transurethral approach were unsuccessful.The random sextant samples contained benign prostatic hyperplasia, whereas Gleason grade 3 + 3 = 6 adenocarcinoma was confirmed in 15% and 25% of the 2 cores obtained from the MRI targeted specimens of 2 defined lesions. The procedure was well tolerated by the patient.Transperineal MRI guided biopsy is a new technique that may be useful in detecting prostate cancer in men with increasing prostate specific antigen who are not candidates for transrectal ultrasound guided biopsy.

A large number of men are diagnosed with early-stage prostate cancer as a result of prostate-specific antigen (PSA) screening. For many of these men, prostatectomy results in long-term freedom from biochemical and clinical failure. Despite limited follow-up data, ultrasound-guided prostate brachytherapy has gained acceptance as a treatment for early-stage prostate cancer, in part due to its favorable side effect profile and brief recovery period. We report on the use of three-dimensional real-time magnetic resonance (MR) guidance, which has several advantages compared with biplanar ultrasound guidance for prostate brachytherapy, including enhanced geometric and dosimetric feedback during the procedure.Median clinical target volume coverage of 96% was achieved using MR guidance. The ability to define more precisely the clinical target volume with MR and the use of real-time assessment of dose distribution resulted in an excellent acute side effect profile. Only 19% of patients required oral alpha1 blockers for postimplant urethritis and 9% required temporary reinsertion of the Foley catheter due to acute urinary obstruction.These results compare favorably to those of ultrasound-guided brachytherapy. Further follow-up is needed to ascertain the impact this technique will have on cancer control and long-term quality of life.

Forty-two patients undergoing inhalation induction with isoflurane in nitrous oxide and oxygen, were allocated randomly to receive either humidified or non-humidified gas. Humidification resulted in a significantly lower incidence of problems during induction (P less than 0.05).