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Ketamine has a number of clinical uses and properties that suggest a role for the drug in neuroanestheisa practice. “Dogma” and “myths” persist with regard to its effects on cerebral hemodynamics and intracranial pressure which have limited its use in Neuroanesthesia and care of the critically ill brain-injured patient. This review aims to educate the clinician on the possible role of ketamine in modern neuroanesthesia practice. A number of systemic reviews support the use of ketamine in patients with acute brain injury and raised intracranial pressure (ICP). Pre-clinical work suggests that ketamine may have mechanisms of action compatible with neuroprotection including modifying glutamate excitatory-driven mechanisms of brain injury. There is emerging clinical evidence to suggest that ketamine may inhibit spreading depolarizations (SDs), a cortical electrical phenomenon associated with brain injury. Ketamine is no longer contraindicated in the care of the brain-injured patient, and its properties of potent analgesia, dissociative anesthesia, and minimal effects on both the hemodynamic and respiratory system are being utilized in the pre-hospital and emergency room setting. Good grade data on meaningful clinical outcomes is presently lacking to support the use of ketamine as a drug with neuroprotection properties but is an area of ongoing interest.

STUDY DESIGN The enhanced perioperative care (EPOC) program is an institutional quality improvement initiative. We used a historically controlled study design to evaluate patients who underwent major spine surgery before and after the implementation of the EPOC program. OBJECTIVE To determine whether multidisciplinary EPOC program was associated with an improvement in clinical and financial outcomes for elective adult major spine surgery patients. SUMMARY OF BACKGROUND DATA The enhanced recovery after surgery (ERAS) programs successfully implemented in hip and knee replacement surgeries, and improved clinical outcomes and patient satisfaction. METHODS We compared 183 subjects in traditional care (TRDC) group to 267 intervention period (EPOC) in a single academic quaternary spine surgery referral center. One hundred eight subjects in no pathway (NOPW) care group was also examined to exclude if the observed changes between the EPOC and TRDC groups might be due to concurrent changes in practice or population over the same time period. Our primary outcome variables were hospital and intensive care unit lengths of stay and the secondary outcomes were postoperative complications, 30-day hospital readmission and cost. RESULTS In this highly complex patient population, we observed a reduction in mean hospital length of stay (HLOS) between TRDC versus EPOC groups (8.2 vs. 6.1 d, standard deviation [SD] = 6.3 vs. 3.6, P

Background Transient adenosine-induced asystole is a reliable method for producing a short period of relative hypotension during surgical and endovascular procedures. Although the technique has been described in the endovascular treatment of brain arteriovenous malformations, aortic aneurysms, and posterior circulation cerebral aneurysms, little description of its use in anterior circulation aneurysms is available. Objective To assess the benefits of adenosine-induced transient asystole in complex anterior circulation aneurysms, to describe our experience in selected cases, and to provide the first experience of the use of adenosine in anterior circulation aneurysms. Methods The adenosine-induced cardiac arrest protocol allows us to titrate the duration of cardiac arrest on the basis of individual patient responses. The operative setup is the same as with all aneurysm clippings, with the addition of the placement of transcutaneous pacemakers as a precaution for prolonged bradycardia or asystole. Escalating doses of adenosine are given to determine the approximate dose that results in 30 seconds of asystole. When requested by the surgeon, the dose of adenosine is administered for definitive dissection and clipping. We present 6 cases in which this technique was used. Results The use of transient adenosine-induced asystole provided excellent circumferential visualization of the aneurysm neck and safe clip application. All patients did well neurologically and suffered no evidence of perioperative cerebral ischemia or delayed complication from the use of adenosine itself. Conclusion Transient adenosine-induced asystole is a safe and effective technique in select circumstances that may aid in safe and effective aneurysm clipping. Along with the traditional techniques of brain relaxation, skull base approaches, and temporary clipping, adenosine-induced asystole facilitates circumferential visualization of the aneurysm neck and is another technique available to cerebrovascular surgeons.

PURPOSE OF REVIEW To present current knowledge about the metabolic management of patients undergoing solid organ transplantation, and potential organ donors. RECENT FINDINGS Appropriate management of electrolytes and glucose improves outcome after transplantation, although conflicting evidence exists. Patients with cirrhosis-induced hyponatremia can be successfully transplanted but are at increased risk of postoperative complications. A new class of drugs, the vaptans, that antagonizes arginine vasopressin may be an effective treatment for hyponatremia in transplant candidates. Recent literature has documented the implications, predictors and potential therapies for perioperative hyperkalemia in the transplant population. The debate over appropriate targets for serum glucose in perioperative and critically ill patients has been lively. The documented risk of hypoglycemia associated with 'intensive insulin therapy' has led to the adoption of more conservative glycemic targets. Studies of glycemic control in transplant recipients are limited. SUMMARY In patients undergoing solid organ transplants, sodium management should aim to minimize an acute change in sodium concentration. Vaptans may be of future use in optimizing patients with cirrhosis prior to transplantation. Pending further studies, a perioperative 'middle ground' target glucose of between 140 and 180 mg/dl seems reasonable at this time.

Excessive blood sampling, with its inherent risks, is of growing concern among clinicians. We performed this study to measure the changes in hematocrit (Hct) during a laboratory investigation where multiple blood samples are collected. The performance of a simple mathematical model, used in clinical practice to predict Hct changes, is evaluated. Eight healthy male volunteers participated in this study. The equation Hctf = Hcti*(EBV-BL)/EBV is used to predict changes in Hct. Where Hctf and Hcti are, respectively, the final and initial Hct, EBV is the estimated blood volume and BL is the blood loss. Thirty-five pharmacokinetic samples per subject were collected totalling 314 mL of BL. The Hct decreased from 44.2% ± 2.2% to 39.9% ± 2.5% (P = 0.001). On average, model predictions tended to have a discrete tendency to underestimate the Hct changes (-0.5% points of bias). While the predictions of the Hct were very accurate in 50% of the subjects, the discrepancy of the Hct predictions was clinically significant in the other 50% of the subjects. Consistent with the model prediction, this study demonstrated a significant reduction in the Hct values in healthy subjects undergoing incremental phlebotomy. On average, the model successfully predicted the decrease in Hct. However, the inter- and intra-individual variabilities in the Hct changes are clinically significant. In clinical settings, which are not well controlled environments, the variability is likely to be greater and the clinical use of the model cannot replace the need to monitor the Hct. Les echantillons sanguins excessifs, et leurs risques inherents, preoccupent de plus en plus les cliniciens. Nous avons mesure les modifications de l’hematocrite (Hct) au cours d’une investigation en laboratoire ou de multiples echantillons sanguins sont preleves. La performance d’un modele mathematique simple, qui predit les changements de l’Hct en clinique, est evaluee. Huit hommes volontaires en sante ont participe a l’etude. L’equation Hctf = Hct*(VSE-PS)/VSE sert a predire les changements de l’Hct ou Hct et Hct sont respectivement l’Hct final et initial, VSE est le volume sanguin estime et PS est la perte sanguine. Trente-cinq echantillons pharmacocinetiques par sujet ont ete preleves pour un total de 314 mL de PS. L’Hct a diminue de 44,2 % ± 2,2 % a 39,9 % ± 2,5 % (P = 0,001). Les predictions du modele presentaient en moyenne une tendance discrete a sous-estimer les modifications de l’Hct (-0,5 % de biais). Les predictions de l’Hct ont ete tres exactes chez 50 % des sujets, mais la divergence dans les predictions etait cliniquement significative chez les autres 50 %. L’etude a demontre, conformement au modele de prediction, une reduction significative des valeurs de l’Hct chez des sujets sains qui subissent une phlebotomie incrementielle. En moyenne, le modele a pu predire la baisse de l’Hct. Cependant, les variations interindividuelles et intra-individuelles de modification de l’Hct sont cliniquement significatives. En clinique, ce qui n’est pas un environnement bien contrale, la variabilite risque d’etre plus grande et l’usage clinique du modele ne peut remplacer la necessite du moniteur d’Hct.

Background Dexmedetomidine, a highly selective alpha2-adrenoceptor agonist used for short-term sedation of mechanically ventilated patients, has minimal effect on ventilation. Methods This study compared the respiratory effect of dexmedetomidine to that of remifentanil. The authors measured and compared respiratory responses of six healthy male volunteers during (1) a stepwise target-controlled infusion of remifentanil, (2) a stepwise target-controlled infusion of dexmedetomidine, and (3) a pseudonatural sleep session. Results Compared with baseline, remifentanil infusions resulted in respiratory depression as evidenced by a decrease in respiratory rate and minute ventilation, respiratory acidosis, and apnea episodes resulting in desaturations. Remifentanil disturbed the natural pattern of breathing and flattened the distribution of ventilatory timing (inspiratory time/ventilatory cycle time). The respiratory effects of dexmedetomidine markedly contrasted with those of remifentanil. When compared with baseline, during dexmedetomidine infusions, the respiratory rate significantly increased, and the overall apnea/hypopnea index significantly decreased. The distribution of inspiratory time/ventilatory cycle time showed an increased peak. In addition, dexmedetomidine seemed to mimic some aspect of natural sleep. While the subjects were breathing a 5% CO2 mixture, hypercapnic arousal phenomena (documented by the Bispectral Index, the electroencephalogram, and sudden increase in the minute ventilation) were observed during dexmedetomidine infusions. Similar phenomena during natural sleep have been reported in the literature. Conclusions In comparison with remifentanil, dexmedetomidine infusions (1) did not result in clinically significant respiratory depression, (2) decreased rather than increased the apnea/hypopnea index, and (3) exhibited some similarity with natural sleep.

We present a case of tongue necrosis due to intraoperative pressure injury. A laryngeal mask airway with adhesive electrodes was inserted into the oropharynx, over an endotracheal tube, to facilitate glossopharyngeal nerve monitoring during craniotomy for a cerebellopontine angle tumor. The case, mechanisms of injury, and modifications to our current practice are discussed.

BRIEF SUMMARY: We describe the use of adenosine-induced cardiac arrest to facilitate intracranial aneurysm clip ligation.Cerebral aneurysms are highly variable which may result in difficult surgical exposure for clip ligation in select cases. Secure clip placement is often not feasible without temporarily decompressing the aneurysm. This can be accomplished with temporary clip ligation of proximal vessels, or with deep hypothermic circulatory arrest on cardiopulmonary bypass, although these methods have their own inherent risks. Here we describe an alternate method of decompressing the aneurysm via adenosine-induced transient asystole.We examined the records of 27 patients who underwent craniotomy for cerebral aneurysm clipping in which adenosine was used to induce transient asystole to facilitate clip ligation. Duration of adenosine-induced bradycardia (heart rate40) and hypotension (SBP60) recorded on the electronic anesthesia record and outcome data including incidence of successful clipping, intraoperative and postoperative complications, and mortality were recorded.Satisfactory aneurysm decompression was achieved in all cases, and all aneurysms were clipped successfully. The median dose of intravenous adenosine resulting in bradycardia greater than 30 seconds was 30 mg. The median dose of adenosine resulting in hypotension greater than 30 seconds was 15 mg, and greater than 60 seconds was 30 mg. One case of prolonged hypotension after rapid redosing of adenosine required brief closed chest compressions before circulation was spontaneously restored. No other adverse events were observed.Adenosine cardiac arrest is a relatively novel method for decompression of intracranial aneurysms to facilitate clip application. With appropriate safety precautions, it is a reasonable alternative method when temporary clipping of proximal vessels is not desirable or not possible.

Objective Neurophysiological intraoperative monitoring of the glossopharyngeal nerve has been performed only with needle electrodes inserted into the pharyngeal muscles or soft palate. We describe a noninvasive method of monitoring this cranial nerve. Methods A 30-year-old man who presented with headache, as well as speech and swallowing difficulty, underwent surgical resection of a right vagus nerve schwannoma. Neurophysiological intraoperative monitoring of multiple lower cranial nerves, including the glossopharyngeal and vagus nerves, was performed. Results The glossopharyngeal nerve was monitored with an adhesive surface electrode mounted on the cuff of a laryngeal mask airway, and the vagus nerve was monitored with a similar electrode mounted on the endotracheal tube. Successful monitoring allowed separation of the glossopharyngeal nerve from the tumor, and there was no postoperative swallowing deficit. Conclusion Monitoring of the glossopharyngeal nerve with surface electrodes is possible and reliable, but it must be combined with vagus nerve monitoring.

The ethical conduct of research is a cornerstone of modern scientific research. Computer science and the discipline's technological artifacts touch nearly every aspect of modern life, and computer scientists must conduct and report their research in an ethical manner. This workshop will identify four theories that offer guidance for ethical decision making, ad use these theories as a basis for evaluating and discussing a set of ethical dilemmas that researchers in computer science might face.

Pulse oximeters may delay displaying the correct oxygen saturation during the onset of hypoxia. We investigated the desaturation response times of pulse oximeter sensors (forehead, ear and finger) during vasoconstriction due to mild hypothermia and vasodilation caused by glyceryl trinitrate. Ten healthy male volunteers were given three hypoxic challenges of 3 min duration under differing experimental conditions. Mild hypothermia increased the mean response time of finger oximeters from 130 to 215 s. Glyceryl trinitrate partly offset this effect by reducing the response time from 215 to 187 s. In contrast, the response times of the forehead and ear oximeters were unaffected by mild hypothermia, but the difference between head and finger oximeters was highly significant (p < 0.0001). The results suggest that the head oximeters provide a better monitoring site for pulse oximeters during mild hypothermia.