Insulin and the Brain: A Sweet Relationship With Intensive Care

BACKGROUND

Insulin receptors (IRs) in the brain have unique molecular features and a characteristic pattern of distribution. Their possible functions extend beyond glucose utilization. In this systematic review, we explore the interactions between insulin and the brain and its implications for anesthesiologists, critical care physicians, and other medical disciplines.

METHODS

A literature search of published preclinical and clinical studies between 1978 and 2014 was conducted, yielding 5996 articles. After applying inclusion and exclusion criteria, 92 studies were selected for this systematic review.

RESULTS

The IRs have unique molecular features, pattern of distribution, and mechanism of action. It has effects on neuronal function, metabolism, and neurotransmission. The IRs are involved in neuronal apoptosis and neurodegenerative processes.

CONCLUSION

In this systematic review, we present a close relationship between insulin and the brain, with discernible effects on memory, learning abilities, and motor functions. The potential therapeutic effects extend from acute brain insults such as traumatic brain injury, brain ischemia, and hemorrhage, to chronic neurodegenerative diseases such as Alzheimer and Parkinson disease. An understanding of the wider effects of insulin conveyed in this review will prompt anaesthesiologists and critical care physicians to consider its therapeutic potential and guide future studies.

Extracorporeal methods of blood glutamate scavenging: a novel therapeutic modality

Pathologically elevated glutamate concentrations in the brain's extracellular fluid are associated with several acute and chronic brain insults. Studies have demonstrated that by decreasing the concentration of glutamate in the blood, thereby increasing the concentration gradient between the brain and the blood, the rate of brain-to-blood glutamate efflux can be increased. Blood glutamate scavengers, pyruvate and oxaloacetate have shown great promise in providing neuroprotection in many animal models of acute brain insults. However, glutamate scavengers' potential systemic toxicity, side effects and pharmacokinetic properties may limit their use in clinical practice. In contrast, extracorporeal methods of blood glutamate reduction, in which glutamate is filtered from the blood and eliminated, may be an advantageous adjunct in treating acute brain insults. Here, we review the current evidence for the glutamate-lowering effects of hemodialysis, peritoneal dialysis and hemofiltration. The evidence reviewed here highlights the need for clinical trials.

Insulin infusion therapy in critical care patients: regular insulin vs short-acting insulin. A prospective, crossover, randomized, multicenter blind study

INTRODUCTION

The aim of this multicenter, prospective, randomized, crossover trial is to compare, in critical care patients receiving insulin infusion therapy (IIT), the pharmacodynamic of Humulin insulin (Hlin), currently used as "standard of care," and Humalog insulin (Hlog), a shorter acting insulin formulation. This was measured as extent and duration of the carryover effect of insulin treatment, with the latter calculated as ratio between blood glucose concentration (BGC) reduction during and after IIT.

MATERIALS AND METHODS

Twenty-eight patients treated in an intensive care unit and receiving full nutritional support were randomly assigned to Hlin or Hlog as first treatment. Insulin was infused at a constant rate in patients presenting with BGC greater than or equal to 180 mg/dL (0.04 U/kg per hour) and was discontinued when BGC was less than or equal to 140 mg/dL (therapeutic BGC drop). Further reductions in BGC after discontinuation of insulin infusion were recorded (postinfusional BGC drop). During the study period, whole blood BGC was measured every 30 minutes. A minimal 6-hour washout interval was maintained between treatments with the 2 types of insulin. The primary end point was the extent (calculated as ratio between the therapeutic BGC drop and the postinfusional BGC drop) and duration of the carryover effect.

RESULTS

Treatment with Hlog, as compared with Hlin, was associated with a less profound carryover effect as well as a briefer duration of carryover (median, 0.40 vs 0.62; P < .001; median, 1 vs 1.5 hours; P < .001).

CONCLUSIONS

The use of constant Hlog infusion for IIT, when compared with Hlin at the same dose, is associated with a less profound carryover effect on BGC after discontinuation of IIT, a briefer duration of carryover, a faster BGC drop during infusion, and a quicker BGC rise after discontinuation. These characteristics suggest that Hlog IIT may be preferable for use in critically ill patients.

Web-based educational activities developed by the Society for Neuroscience in Anesthesiology and Critical Care (SNACC): the experience of process, utilization, and expert evaluation

BACKGROUND

Web-based delivery of educational material by scientific societies appears to have increased recently. However, the utilization of such efforts by the members of professional societies is unknown. We report the experience with delivery of educational resources on the Web site of the Society for Neuroscience in Anesthesiology and Critical Care (SNACC), and utilization of those resources by members.

METHODS

Three web-based educational initiatives were developed over 1 year to be disseminated through the SNACC Web site (http://www.snacc.org) for society members: (1) The SNACC Bibliography; (2) "Chat with the Author"; and (3) Clinical Case Discussions. Content experts and authors of important new research publications were invited to contribute. Member utilization data were abstracted with the help of the webmaster.

RESULTS

For the bibliography, there were 1175 page requests during the 6-month period after its launch by 122/664 (19%) distinct SNACC members. The bibliography was utilized by 107/553 (19%) of the active members and 15/91 (16.5%) of the trainee members. The "Chats with the Authors" were viewed by 56 (9%) members and the Clinical Case Discussions by 51 (8%) members.

CONCLUSIONS

Educational resources can be developed in a timely manner utilizing member contributions without additional financial implications. However, the member utilization of these resources was lower than expected. These are first estimates of utilization of web-based educational resources by members of a scientific society. Further evaluation of such utilization by members of other societies as well as measures of the effectiveness and impact of such activities is needed.

Antioxidants: The new frontier for translational research in cerebroprotection

It is important for the anesthesiologist to understand the etiology of free radical damage and how free-radical scavengers attenuate this, so that this knowledge can be applied to diverse neuro-pathological conditions. This review will concentrate on the role of reactive species of oxygen in the pathophysiology of organ dysfunction, specifically sub arachnoid hemorrhage (SAH), traumatic brain injury (TBI) as well as global central nervous system (CNS) hypoxic, ischemic and reperfusion states. We enumerate potential therapeutic modalities that are been currently investigated and of interest for future trials. Antioxidants are perhaps the next frontier of translational research, especially in neuro-anesthesiology.

Short acting insulin analogues in intensive care unit patients

Blood glucose control in intensive care unit (ICU) patients, addressed to actively maintain blood glucose concentration within defined thresholds, is based on two major therapeutic interventions: to supply an adequate calories load and, when necessary, to continuously infuse insulin titrated to patients needs: intensive insulin therapy (IIT). Short acting insulin analogues (SAIA) have been synthesized to improve the chronic treatment of patients with diabetes but, because of the pharmacokinetic characteristics that include shorter on-set and off-set, they can be effectively used also in ICU patients and have the potential to be associated with a more limited risk of inducing episodes of iatrogenic hypoglycemia. Medical therapies carry an intrinsic risk for collateral effects; this can be more harmful in patients with unstable clinical conditions like ICU patients. To minimize these risks, the use of short acting drugs in ICU patients have gained a progressively larger room in ICU and now pharmaceutical companies and researchers design drugs dedicated to this subset of medical practice. In this article we report the rationale of using short acting drugs in ICU patients (i.e., sedation and treatment of arterial hypertension) and we also describe SAIA and their therapeutic use in ICU with the potential to minimize iatrogenic hypoglycemia related to IIT. The pharmacodynamic and pharmachokinetic characteristics of SAIA will be also discussed.

Ultrasound-based imaging in neurocritical care patients: a review of clinical applications

OBJECTIVE

To analyze the diagnostic, monitoring, and procedural applications of ultrasound (US) imaging in neurocritical care (NCC) patients.

METHOD

US imaging has been extensively validated in various subset of critically ill patients, but not specifically in the NCC population. We reviewed the clinical applications of US imaging for heart, vascular, brain, and lung evaluation and for possible procedural uses in NCC patients. Major neurosurgical books, journals, testimonials, authors' personal experience, and scientific databases were analyzed.

RESULTS

Cardiac US imaging provides accurate information at NCC arrival to stratify risk factors, including presence of atrial septal defect/patent formen ovale, abnormal ventricular function, or pericardial effusion, and to monitor cardiac anatomy and function during the NCC stay for guiding goal-directed therapy. Vascular US in NCC patients has three especially relevant indications: to screen anatomy and flow in extracranial supra-aortic arteries, to diagnose deep vein thrombosis, and to optimize the safety of central venous catheterization. Brain US has important clinical applications in the NCC, including transcranial Doppler and emerging techniques for cerebral blood flow evaluation with contrast-enhanced US imaging. Lung US, as demonstrated in other intensive care unit patients, provides accurate diagnosis of anatomical and functional abnormalities and enables diagnosis of pleural effusion, pneumothorax, lung consolidation, pulmonary abscess and interstitial-alveolar syndrome, and lung recruitment/derecruitment. US imaging can effectively guide percutaneous tracheostomy.

CONCLUSION

In conclusion, US imaging is an important diagnostic tool that provides real-time information at the bedside to stratify risk, monitor for complications, and guide invasive procedures in NCC patients.

Diagnostic work up for language testing in patients undergoing awake craniotomy for brain lesions in language areas

Awake craniotomy is the technique of choice in patients with brain tumours adjacent to primary and accessory language areas (Broca's and Wernicke's areas). Language testing should be aimed to detect preoperative deficits, to promptly identify the occurrence of new intraoperative impairments and to establish the course of postoperative language status. Aim of this case series is to describe our experience with a dedicated language testing work up to evaluate patients with or at risk for language disturbances undergoing awake craniotomy for brain tumour resection. Pre- and intra operative testing was accomplished with 8 tests. Intraoperative evaluation was accomplished when patients were fully cooperative (Ramsey < 3). Postoperative evaluation was scheduled at early (within 21 days) and long-term follow-up (3-6 months). Twenty consecutive patients were prospectively recruited. Preoperative language testings were normal in 9 patients (45%), showed mild to moderate language deficit in 8 (40%) and severe language deficit or aphasic disorders in 3 (15%). Broca's area was identified in 15 patients, in all cases by counting arrest during stimulation and in 12 cases by naming arrest. In this article we describe our experience using a language testing work up to evaluate - pre, intra and postoperatively - patients undergoing awake craniotomy for brain tumour resection with preoperative language disturbances or at risk for postoperative language deficits. This approach allows a systematic evaluation and recording of language function status and can be accomplished even when a neuropsychologist or speech therapist are not involved in the operation crew.

Postoperative delirium: risk factors, diagnosis and perioperative care

Postoperative delirium (PD) relates to increased morbidity -associated with prolonged hospital stay, institutionalization and persistent functional and cognitive decline- poor long term outcome and higher perioperative mortality. Aim of this literature review is to identify established risk factors for PD and to categorize them according timing of occurrence (pre, intra and post operative), and clinical impact (Odds ratio [OR], % increase in incidence of PD).

SOURCE OF INFORMATION

medical literature databases (medline and embase) were searched for published manuscripts on "postoperative delirium". Predictors and preoperative risk factors for PD were categorized into 4 groups: demographics; co morbidities; surgery and anesthesia-related (age, education, laboratory anomalies, smoking habits, benzodiazepines premedication, cardiac and thoracic surgery, etc). Intra operative risk factors for PD were categorized into 2 groups: surgery and anesthesia-related (anemia, duration and type of surgery, selected opioid, intraoperative hypotension, etc). Post operative risk factors and precipitating factors include various pathophysiological and environmental conditions, (i.e., ICU admission, low cardiac output requiring inotropes infusion; new onset atrial fibrillation; persistent hypoxia or hypercarbia; use of narcotic analgesics, delayed ambulation, inadequate nutritional status; sensory deprivation, etc). In conclusion, the effective identification, prevention and treatment of pre, intra and postoperative risk factors are the cornerstones for the prevention of PD. A dedicated perioperative care path that encompasses a tailored selection of drugs used perioperatively, the appropriate anesthesia strategy, qualified nursing surveillance, systematic use of diagnostic tools and accurate staff communication reduces the incidence and clinical impact of PD.

Training anesthesiology residents in providing anesthesia for awake craniotomy: learning curves and estimate of needed case load

STUDY OBJECTIVE

To measure the learning curves of residents in anesthesiology in providing anesthesia for awake craniotomy, and to estimate the case load needed to achieve a "good-excellent" level of competence.

DESIGN

Prospective study.

SETTING

Operating room of a university hospital.

SUBJECTS

7 volunteer residents in anesthesiology.

MEASUREMENTS

Residents underwent a dedicated training program of clinical characteristics of anesthesia for awake craniotomy. The program was divided into three tasks: local anesthesia, sedation-analgesia, and intraoperative hemodynamic management. The learning curve for each resident for each task was recorded over 10 procedures. Quantitative assessment of the individual's ability was based on the resident's self-assessment score and the attending anesthesiologist's judgment, and rated by modified 12 mm Likert scale, reported ability score visual analog scale (VAS). This ability VAS score ranged from 1 to 12 (ie, very poor, mild, moderate, sufficient, good, excellent). The number of requests for advice also was recorded (ie, resident requests for practical help and theoretical notions to accomplish the procedures).

MAIN RESULTS

Each task had a specific learning rate; the number of procedures necessary to achieve "good-excellent" ability with confidence, as determined by the recorded results, were 10 procedures for local anesthesia, 15 to 25 procedures for sedation-analgesia, and 20 to 30 procedures for intraoperative hemodynamic management.

CONCLUSIONS

Awake craniotomy is an approach used increasingly in neuroanesthesia. A dedicated training program based on learning specific tasks and building confidence with essential features provides "good-excellent" ability.

Optimal glycemic control in neurocritical care patients

Currently, the major issue in glycemic control in neurocritical care patients is that tight glycemic control (target range of 80 to 110 mg/dL) using intensive insulin therapy is associated with higher rates of hypoglycemia without an improvement in survival rate. The review by Kramer and colleagues in this issue of Critical Care confirms these data but provides solid evidence about the relationship between hyperglycemia and worsened neurological outcome after acute brain injury. In accordance with the conclusions of Kramer and colleagues, we recommend that a glucose control goal in neurocritical care patients be in the 'moderate' target range (110 to 180 mg/dL). In addition, we recommend adequate nutrition before and during insulin infusion, avoidance of insulin as a bolus, and the use of continuous insulin infusion, beginning with low doses with titration to individual sensitivity. Careful and accurate glycemic monitoring is especially important when insulin is infused.

Glycemia management in critical care patients

Over the last decade, the approach to clinical management of blood glucose concentration (BGC) in critical care patients has dramatically changed. In this editorial, the risks related to hypo, hyperglycemia and high BGC variability, optimal BGC target range and BGC monitoring devices for patients in the intensive care unit (ICU) will be discussed. Hypoglycemia has an increased risk of death, even after the occurrence of a single episode of mild hypoglycemia (BGC < 80 mg/dL), and it is also associated with an increase in the ICU length of stay, the major determinant of ICU costs. Hyperglycemia (with a threshold value of 180 mg/dL) is associated with an increased risk of death, longer length of stay and higher infective morbidity in ICU patients. In ICU patients, insulin infusion aimed at maintaining BGC within a 140-180 mg/dL target range (NICE-SUGAR protocol) is considered to be the state-of-the-art. Recent evidence suggests that a lower BGC target range (129-145 mg/dL) is safe and associated with lower mortality. In trauma patients without traumatic brain injury, tight BGC (target < 110 mg/dL) might be associated with lower mortality. Safe BGC targeting and estimation of optimal insulin dose titration should include an adequate nutrition protocol, the length of insulin infusion and the change in insulin sensitivity over time. Continuous glucose monitoring devices that provide accurate measurement can contribute to minimizing the risk of hypoglycemia and improve insulin titration. In conclusion, in ICU patients, safe and effective glycemia management is based on accurate glycemia monitoring and achievement of the optimal BGC target range by using insulin titration, along with an adequate nutritional protocol.

Early postoperative cognitive dysfunction and postoperative delirium after anaesthesia with various hypnotics: study protocol for a randomised controlled trial--the PINOCCHIO trial

Background

Postoperative delirium can result in increased postoperative morbidity and mortality, major demand for postoperative care and higher hospital costs. Hypnotics serve to induce and maintain anaesthesia and to abolish patients' consciousness. Their persisting clinical action can delay postoperative cognitive recovery and favour postoperative delirium. Some evidence suggests that these unwanted effects vary according to each hypnotic's specific pharmacodynamic and pharmacokinetic characteristics and its interaction with the individual patient.

We designed this study to evaluate postoperative delirium rate after general anaesthesia with various hypnotics in patients undergoing surgical procedures other than cardiac or brain surgery. We also aimed to test whether delayed postoperative cognitive recovery increases the risk of postoperative delirium.

Methods/Design

After local ethics committee approval, enrolled patients will be randomly assigned to one of three treatment groups. In all patients anaesthesia will be induced with propofol and fentanyl, and maintained with the anaesthetics desflurane, or sevoflurane, or propofol and the analgesic opioid fentanyl.

The onset of postoperative delirium will be monitored with the Nursing Delirium Scale every three hours up to 72 hours post anaesthesia. Cognitive function will be evaluated with two cognitive test batteries (the Short Memory Orientation Memory Concentration Test and the Rancho Los Amigos Scale) preoperatively, at baseline, and postoperatively at 20, 40 and 60 min after extubation.

Statistical analysis will investigate differences in the hypnotics used to maintain anaesthesia and the odds ratios for postoperative delirium, the relation of early postoperative cognitive recovery and postoperative delirium rate. A subgroup analysis will be used to categorize patients according to demographic variables relevant to the risk of postoperative delirium (age, sex, body weight) and to the preoperative score index for delirium.

Discussion

The results of this comparative anaesthesiological trial should whether each the three hypnotics tested is related to a significantly different postoperative delirium rate. This information could ultimately allow us to select the most appropriate hypnotic to maintain anaesthesia for specific subgroups of patients and especially for those at high risk of postoperative delirium.

Registered at Trial.gov Number

ClinicalTrials.gov: NCT00507195

Postoperative cognitive dysfunction: toward the Alzheimer's disease pathomechanism hypothesis

Alzheimer's disease (AD), a chronic and progressive deterioration of memory and other cognitive domains, is the most common form of dementia. Because of related health and social impact, there is growing interest in assessing potential relationship between anesthesia and the onset and progression of chronic neurodegenerative disorders, including AD. Currently, preclinical and clinical research is addressed to identify underlying pathomechanisms, patient risk factors, and the use of the least provocative drugs and techniques, to minimize the incidence of chronic neurodegenerative disorders. Preclinical studies are providing an increasing body of evidences on some of the mechanisms that link anesthetics to neuronal programmed cell death (apoptosis) and accumulation of misfolded proteins in the aging brain. Therefore, risk factors and pathomechanisms of chronic neurodegenerative disorders, including AD, and persistent postoperative-postanesthesia cognitive dysfunction may overlap.

Language testing during awake "anesthesia" in a bilingual patient with brain lesion adjacent to Wernicke's area

Awake "anesthesia" is the preferable anesthetic approach for neurosurgical procedures that require intraoperative localization of eloquent brain areas. We describe intraoperative inducible selective English aphasia in a bilingual (English and Italian) patient undergoing awake anesthesia for excision of a brain lesion adjacent to Wernicke's area with no postoperative neurological sequelae. We discuss the importance of intraoperative brain mapping and intraoperative language testing in bilingual patients to prevent iatrogenic-related morbidity.

Adrenaline through the endotracheal tube as an answer to severe bronchospasms caused by lidocaine

The authors describe the effect of instilling adrenaline through the endotracheal tube in one case of severe bronchospasms due to intubation with an endotracheal tube lubricated with 10% lidocaine spray in a patient with no history of adverse respiratory or allergic reactions.

Risk index for peri-operative atrial fibrillation in patients undergoing open intracranial neurosurgical procedures

The aim of this prospective study was to determine the prevalence of pre-operative atrial fibrillation and the incidence of postoperative atrial fibrillation in patients undergoing elective or emergency intracranial neurosurgical procedures and the relation to survival and neurological outcome at 6-months follow-up compared to patients with sinus rhythm. A total of 2020 patients were enrolled; 1540 patients underwent elective procedures and 480 underwent emergency procedures. Prevalence of pre-operative atrial fibrillation was 3.7% in elective and 7.2% in emergency procedures (p = 0.0012). In patients undergoing elective cerebral procedures with pre-operative atrial fibrillation, compared to patients with sinus rhythm, 6-month neurological outcome and survival rate are similar. In patients undergoing emergency neurosurgical cerebral procedures, the presence of pre-operative atrial fibrillation is related to an increased risk of poor neurological outcome but with similar survival rate.

Safety and efficacy of intensive insulin therapy in critical neurosurgical patients

BACKGROUND

Intensive insulin therapy to maintain blood glucose at or below 6.11 mM reduces morbidity and mortality after cardiac surgery and morbidity in medical intensive care unit (ICU) patients. The authors investigated the clinical safety and outcome effects of intensive insulin therapy compared to conventional insulin therapy in patients receiving postoperative intensive care after neurosurgical procedures.

METHODS

In this prospective randomized controlled trial, 483 patients undergoing elective or emergency brain surgery were prospectively and randomly assigned either to intensive insulin therapy (241 patients), receiving insulin titrated to maintain blood glucose levels within the range of 4.44-6.11 mM, or to conventional insulin therapy (242 patients), receiving insulin to maintain blood glucose levels below 11.94 mM. Primary endpoint was incidence of hypoglycemia (defined as blood glucose < 2.78 mM). Efficacy measures included the length of ICU stay, infection rate, and 6 months follow-up Glasgow outcome scale score and overall survival.

RESULTS

Hypoglycemia episodes were more frequent in patients receiving intensive insulin therapy, median (min-max): 8 (0-23) versus 3 (0-4); P < 0.0001. The length of stay in the ICU was shorter (6 vs. 8 days; P = 0.0001), and the infection rate was lower (25.7% vs. 39.3%; P = 0.0018). Glasgow outcome scale score and overall survival at 6 months were similar in the two groups.

CONCLUSIONS

Intensive insulin therapy in patients admitted to a postoperative neurosurgical ICU after brain surgery is associated with iatrogenic hypoglycemia, but it can also reduce the infection rate and shorten the ICU stay.

Intensive insulin therapy after severe traumatic brain injury: a randomized clinical trial

INTRODUCTION

To investigate the risks and possible benefits of routine versus intensive insulin therapy, assessed by the frequency of hypoglycemic events defined as a glucose concentration less than 80 mg/dl (<4.44 mmol/l) in patients admitted to the intensive care unit (ICU) after severe traumatic brain injury (TBI).

METHODS AND RESULTS

Ninety-seven patients admitted after severe TBI, were enrolled and randomly assigned to two groups of target glycemia. Insulin was infused at conventional rates when blood glucose levels exceeded 220 mg/dl (12.22 mmol/l) or at intensive rates, to maintain glycemia at 80-120 mg/dl (4.44-6.66 mmol/l). The following primary and outcome variables were measured during follow-up: hypoglycemic episodes, duration of ICU stay, infection rate, and 6-month mortality and neurologic outcome measured using the Glasgow Outcome Scale (GOS). Episodes of hypoglycemia (defined as blood glucose <80 mg/dl or 4.44 mmol/l) were significantly higher in patients receiving intensive insulin therapy: median (min-max) conventional insulin therapy 7 (range 0-11) vs. intensive insulin therapy 15 (range 6-33); P<0.0001. Duration of ICU stay was shorter in patients receiving intensive insulin therapy (7.3 vs. 10.0 days; P < 0.05); while infection rates during ICU stay (25.0% vs. 38.8%, P = 0.15), and GOS scores and mortality at 6 months were similar in the two groups.

CONCLUSIONS

Intensive insulin therapy significantly increases the risk of hypoglycemic episodes. Even though patients receiving intensive insulin therapy have shorter ICU stays and infection rates similar to those receiving conventional insulin therapy, both groups have similar follow-up mortality and neurologic outcome. Hence if intensive insulin therapy is to be used, great effort must be taken to avoid hypoglycemia.

The effect of intensive insulin therapy on infection rate, vasospasm, neurologic outcome, and mortality in neurointensive care unit after intracranial aneurysm clipping in patients with acute subarachnoid hemorrhage: a randomized prospective pilot trial

It is unclear if avoiding hyperglycemia during intensive care after acute brain injury improves morbidity, mortality, and neurologic outcome. This prospective randomized trial tested whether intensive insulin therapy affected infection rates, vasospasm, mortality, or long-term neurologic outcome in subarachnoid hemorrhage patients during their intensive care unit (ICU) stay. Comparison was made against conventional insulin therapy using a randomized trial design. The primary outcome measure was infection rate until the fourteenth postoperative day in the ICU or until patient discharge. Secondary end points were the incidence of vasospasm until the fourteenth postoperative day in the ICU or until patient discharge, and neurologic outcome and mortality at 6 months follow-up. A total of 78 patients were prospectively enrolled and randomly assigned either to conventional insulin therapy or to intensive insulin therapy (38 and 40 patients, respectively). The infection rate during the study was significantly higher in patients who received conventional insulin therapy than in patients who received intensive insulin therapy (42% vs. 27%; P<0.001). The incidence of vasospasm during the study was also similar in conventional and intensive therapy groups (31.5% vs. 27.6% in the conventional and intensive insulin therapy groups; P=0.9). Overall mortality rates at 6 months were similar in the 2 groups (18% vs.15%; P=0.9), as was the neurologic outcome at 6 months [modified Rankin score >3 in 22/38 patients (57.8%) in the conventional therapy group vs. 21/40 patients (52.5%) in the intensive insulin therapy group; P=0.7]. Intensive insulin therapy in patients with acute subarachnoid hemorrhage admitted to a postoperative neurosurgical ICU after surgical clipping of intracranial aneurysms decreases infection rates. The benefit of strict glycemic control on postoperative vasospasm, neurologic outcome, and mortality rates does not seem to be affected by intensive insulin therapy.

Early postoperative cognitive recovery after remifentanil–propofol or sufentanil–propofol anaesthesia for supratentorial craniotomy: a randomized trial

BACKGROUND AND OBJECTIVE

This study was designed to evaluate early postoperative cognitive recovery after total intravenous anaesthesia with remifentanil-propofol or sufentanil-propofol in patients undergoing craniotomy for supratentorial expanding lesions.

METHODS

Sixty patients were consecutively enrolled, and randomly assigned to one of two study groups: remifentanil-propofol or sufentanil-propofol anaesthesia. To evaluate cognitive function the Short Orientation Memory Concentration Test (SOMCT) and Rancho Los Amigos Scale (RLAS) were administered to all patients in a double-blind procedure before surgery at 15, 45 min and 3 h after extubation.

RESULTS

Mean extubation time was similar in the two groups (13 +/- 5 min vs. 19 +/- 6 min). A significantly larger number of patients in the remifentanil-propofol group than in the sufentanil-propofol group required antihypertensive medication postoperatively to maintain mean arterial pressure within 20% of baseline (18/30 vs. 4/29; P = 0.0004). Intergroup analysis showed no differences in baseline SOMCT scores (28 +/- 1 vs. 28 +/- 1) whereas mean SOMCT scores at 15, 45 min and 3 h after extubation were significantly higher in the remifentanil-propofol group (30 patients) than in the sufentanil-propofol group (29 patients) (22 +/- 3 vs. 16 +/- 3; P < 0.0001 and 27 +/- 1 vs. 22 +/- 3; P < 0.0001; 28 +/- 1 vs. 26 +/- 2; P = 0.0126).

CONCLUSIONS

In conclusion, propofol-remifentanil and propofol-sufentanil are both suitable for fast-track neuroanaesthesia and provide similar intraoperative haemodynamics, awakening and extubation times. Despite a higher risk of treatable postoperative hypertension propofol-remifentanil allows earlier cognitive recovery.

Lidocaine pretreatment for the prevention of propofol-induced transient motor disturbances in children during anesthesia induction: a randomized controlled trial in children undergoing invasive hematologic procedures

BACKGROUND

We examined the effect of lidocaine pretreatment before propofol administration on the incidence of transient motor disturbances and on propofol requirements for anesthesia induction in infants and children undergoing repeated painful diagnostic and therapeutic hematological procedures.

METHODS

A series of 358 children subgrouped according to the presence of a peripheral-vein or central venous catheter were randomly assigned to receive an intravenous dose of 2% lidocaine (2.0 mg.kg(-1)) or an equivalent volume of saline, 1 min before propofol (1.5-3.5 mg.kg(-1)) injected for anesthesia induction.

RESULTS

The incidence of spontaneous movements was significantly lower in patients pretreated with lidocaine than in those receiving placebo (2.5% vs 29%; P < 0.001, by chi-square test), as was the propofol induction dose (1.6 +/- 0.2 mg.kg(-1) vs 2.2 +/- 0.3 mg.kg(-1); P < 0.001) and pain at the injection site in patients peripheral-vein catheter (12% vs. 54%; P < 0.001). Lidocaine administration also improved children's acceptance as reported by parents on the Observational Scale of Behavioral Distress administered 2 h after the procedure (6.5 +/- 2.5 vs. 9.4 +/- 3.3; P < 0.001). Bouts of coughing developed significantly more frequently after lidocaine pretreatment than after placebo (62.5% vs. 17.5%; P < 0.001).

CONCLUSIONS

Because lidocaine pretreatment before the induction of propofol-based anesthesia decreases propofol-induced motor disturbances, lowers hypnotic requirements and reduces pain at the injection site, without inducing untoward events, thus improving children's and parental acceptance, it should become standard practice in infants and children undergoing repeated painful diagnostic and therapeutic hematological procedures.

Perioperative transoesophageal echocardiography in noncardiac surgery

Transoesophageal echocardiography (TOE) is a semi invasive technique that allows a real time evaluation of cardiac anatomy, regional and global function. Its use is becoming an irreplaceable tool for the assessment and therapeutic management of critical patients in the Perioperative setting. A systematic search for reports describing indications for intraoperative TOE monitoring was carried out. Search terms were Perioperative TEE/TOE, intraoperative monitoring, TEE/TOE and vascular surgery, neurosurgery, orthopaedic surgery, transplant surgery. In several surgical specialties, including vascular surgery, neurosurgery, laparoscopic, orthopaedic, and transplant surgery, the intraoperative TOE monitoring found specific indications. The early recognition of haemodynamic changes, pulmonary and paradoxical embolism and ischaemic events, often not diagnosed through standard monitoring such as electrocardiography and pulmonary artery catheterization, allows a prompt therapeutic intervention and a reduction in mortality and morbidity in patients with a failing cardiac function. This paper is a review of the current uses of TOE in noncardiac surgery such as vascular surgery, neurosurgery, laparoscopic, orthopaedic, and transplant surgery. In these situations, significant haemodynamic instabilities are known to occur, which require rapid identification and solutions. TOE may have prominent role in perioperative monitoring in several noncardiac surgical procedures.

Myocardial bridging in hypertrophic cardiomyopathy: a plea for surgical correction

Myocardial bridging may be associated with an unfavorable prognosis in patients with hypertrophic cardiomyopathy. We describe a case of a young symptomatic patient with myocardial bridging associated with hypertrophic cardiomyopathy successfully treated by surgical unroofing. Such a procedure should be strongly recommended in patients with hypertrophic cardiomyopathy.

Pulmonary Transit of Echocontrast Agents during Mechanical Ventilation: A Clinical Transthoracic Echocardiographic Study

In this study, we investigated whether the ultrasound contrast agents Levovist or Sono Vue injected intravenously during mechanical ventilation effectively pass through the pulmonary circulation. With echocardiography, we measured the time for the contrast to pass through the lungs; and the intensity of right and left ventricular cavity opacification at four time points: during spontaneous breathing (baseline), 5 minutes after the beginning of mechanical ventilation, and 5 minutes and 30 minutes after extubation. Forty patients undergoing elective peripheral neurosurgical procedures were prospectively and randomly enrolled: 20 patients received intravenous Levovist 1 g and 20 patients received intravenous Sono Vue 1 mL, at the four predefined time points. After intravenous injection, both Levovist and Sono Vue effectively passed through the lungs and opacified the right and left ventricular cavities, at the four time points. Pulmonary transit times were similar and constant for the two contrast agents tested: 6 +/- 2 seconds at baseline, 5 +/- 2 seconds during mechanical ventilation, 7 +/- 2 seconds at 5 minutes and 6 +/- 2 seconds at 30 minutes after extubation with Levovist; and 6 +/- 4 seconds at baseline, 6 +/- 3 seconds during mechanical ventilation, 6 +/- 2 seconds at 5 minutes and 7 +/- 3 seconds at 30 minutes after extubation with Sono Vue. In all patients, each of the four contrast injections achieved high-grade right and left ventricular chamber opacification. In conclusion, both the ultrasound contrast agents tested in this study, Levovist and Sono Vue, after intravenous injection pass through the pulmonary circulation during mechanical ventilation. Ultrasound contrast agents with these characteristics are suitable for intraoperative organ perfusion studies, with intravenous injection.

Nefopam or clonidine in the pharmacologic prevention of shivering in patients undergoing conscious sedation for interventional neuroradiology

The aim of this randomised, double-blind study was to investigate the usefulness of intravenous nefopam, clonidine or placebo in preventing shivering in patients undergoing conscious sedation for interventional neuroradiological procedures. A total of 101 patients were prospectively enrolled and assigned to one of three groups to receive nefopam, clonidine or placebo. The overall incidence of intra-operative shivering was significantly lower in patients treated with nefopam than in those treated with clonidine or placebo (2/32 (6%) vs. 11/38 (29%), p < 0.02; 2/32 (6%) vs. 24/31 (77%), p < 0.0001, respectively). The number of patients who required ephedrine infusions to maintain a mean arterial pressure of 100 mm Hg was higher in the clonidine group than in the nefopam and placebo groups (18/38 (47%) vs. 5/32 (17%), p < 0.05; 18/38 (47%) vs. 6/31 (19%), p < 0.05, respectively). We found that both nefopam and clonidine significantly lowered the rate and severity of shivering during interventional neuroradiological procedures. Fewer patients in the nefopam group than in the other two groups required vasoactive drugs.

Nefopam and tramadol for the prevention of shivering during neuraxial anesthesia

BACKGROUND AND OBJECTIVES

In patients undergoing neuraxial anesthesia, heat loss and core-to-peripheral redistribution of body heat causes the core temperature to decrease. The shivering threshold is therefore reached soon, and more shivering is required to prevent further hypothermia. Because shivering has deleterious metabolic and cardiovascular effects, it should ideally be prevented by pharmacologic or other means. We evaluated the usefulness of intravenous (IV) nefopam and tramadol in preventing and reducing the severity of shivering in patients undergoing neuraxial anesthesia for orthopedic surgery.

METHODS

Ninety patients, scheduled for neuraxial anesthesia (epidural or subarachnoid) for lower limb orthopedic surgery, were prospectively enrolled. Patients were randomly assigned to 1 of 3 groups. Immediately before neuraxial anesthesia, 30 patients received 0.15 mg/kg(-1) IV nefopam in 10 mL saline, 30 patients received 0.5 mg/kg(-1) IV tramadol in 10 mL saline, and a control group of 30 patients received 10 mL IV saline. Neuraxial anesthesia was induced at the L3-L4 or L4-L5 interspaces with 1 mg/kg(-1) mepivacaine for epidural anesthesia and 0.2 mg/kg(-1) for subarachnoid anesthesia. An investigator blinded to the antishivering drug injected recorded the frequency and degree of shivering.

RESULTS

The overall frequency and the intensity of shivering was significantly lower in patients treated with nefopam than in those treated with tramadol or placebo (P <.05 and P <.01) and in patients treated with tramadol than in those treated with placebo (P <.05).

CONCLUSIONS

As a pharmacologic means of preventing shivering in patients undergoing neuraxial anesthesia, nefopam may hold the greatest promise.

Assessment of no-reflow phenomenon after acute myocardial infarction with harmonic angiography and intravenous pump infusion with Levovist: comparison with intracoronary contrast injection

Myocardial contrast echocardiography (intracoronary application) has emerged as an accurate method to detect the "no-reflow phenomenon." To investigate the diagnostic value of harmonic angiography after intravenous infusion of Levovist in assessing "no-reflow," both intracoronary and intravenous contrast injections were performed in a group of patients with acute myocardial infarction. Seventeen consecutive patients with a successfully reperfused acute myocardial infarction within 6 hours of symptom onset were selected for this study. All patients underwent contrast echocardiography with harmonic angiography with Levovist (400 mg/mL, intravenous pump infusion, trigger intervals 1:4 to 1:8) and sonicated albumin (0.5 to 1 mL, intracoronary bolus) on day 1 after the achievement of a sustained coronary reflow. Myocardial perfusion was qualitatively assessed with a 12-segment model. The endocardial length of the residual contrast defect after reflow was also calculated. Forty-four of 204 segments were not analyzed after intravenous contrast echocardiography and 37 after intracoronary contrast echocardiography because of artifacts. Intracoronary and intravenous injections showed a perfusion defect in 31 (19%) segments, with a concordance of 89% (kappa coefficient, 0.72). Concordance in anteroseptal, anterolateral, and inferolateral segments was 95% (kappa = 0.92), 88% (kappa = 0.66), and 83% (kappa = 0.57), respectively. With intracoronary injection used as the reference method, intravenous injection had a sensitivity of 74% and a specificity of 93% for diagnosing contrast defects. The endocardial extent of no-reflow was 18 +/- 19 after intravenous and 21 +/- 17 after intracoronary contrast echocardiography (P = not significant). Intravenous contrast echocardiography with Levovist reliably identifies the no-reflow phenomenon after successful reperfusion, especially in acute anteroseptal myocardial infarction.

Effects of shivering prevention on haemodynamic and metabolic demands in hypothermic postoperative neurosurgical patients

We evaluated the haemodynamic and metabolic effects of prevention of shivering after prophylactic nefopam administration in neurosurgical patients undergoing craniotomy and mild systemic hypothermia (33-35 degrees C). Forty patients were enrolled in a randomised, double-blind study. Before extubation, patients received intravenously either nefopam 0.12 mg.kg-1 or an equal volume of saline 0.9%. Left ventricular systolic work index, oxygen consumption index and systemic lactate concentration were recorded before, immediately after and every 20 min for 2 h after extubation. Shivering appeared in two patients treated with nefopam and in all control patients (p < 0.001). Both left ventricular systolic work index and oxygen consumption index were similar in the two groups before extubation, increased after extubation, and further increased in control patients showing a statistical difference compared to patients treated with nefopam. Our results suggest that nefopam is effective in preventing postoperative shivering in patients undergoing neurosurgery and mild hypothermia and attenuates the haemodynamic effects of shivering during rewarming.

Cardiovascular effects of intravenous propofol administered at two infusion rates: a transthoracic echocardiographic study

We assessed the haemodynamic changes after a propofol infusion at two rates in low-risk unpremedicated patients (ASA I-II). To determine contractility changes and loading conditions, we measured the ejection fraction, end-systolic quotient and fractional shortening on transthoracic echocardiograms. We studied 40 patients undergoing peripheral neurosurgical procedures under general anaesthesia induced by propofol alone (total dose 2.5 mg.kg-1). Patients were randomly assigned to receive propofol at an infusion rate of 10 mg.s-1; or 2 mg.s-1. Haemodynamic data were recorded simultaneously immediately before propofol infusion, at the end of infusion, and 5 and 10 min after the infusion ended. The higher infusion rate induced a larger decrease in mean arterial pressure than the lower infusion rate (- 20% vs. - 10% from baseline, p = 0.01). In both groups, global and segmental ventricular function remained unchanged throughout the study. In both groups, there were markedly reduced end-systolic quotients--presumably related to diminished afterload, and in the higher infusion-rate group a significant reduction in fractional shortening--presumably related principally to diminished preload.

Pulmonary transit of sonicated albumin microbubbles during controlled mechanical ventilation: a transthoracic echocardiographic study

Air-filled human serum albumin microspheres are ultrasonic contrast tracers that pass through the right ventricle, traverse the lungs, and effectively opacify the left heart chambers in spontaneously breathing patients. In this clinical study, we assessed whether they also do so in anesthetized patients during and after mechanical ventilation. In 20 anesthetized patients undergoing intermittent positive pressure ventilation (IPPV) for elective peripheral neurosurgical procedures, a sonicated ultrasound contrast drug (0.06 mL/kg) was injected i.v. before inducing anesthesia in spontaneously breathing patients (baseline), during IPPV, and 5 and 30 min after tracheal extubation. Transthoracic echocardiograms were obtained in the four-chamber apical view and were recorded for off-line analysis. Time to contrast appearance in the right ventricle and pulmonary transit time were measured in cardiac cycles. The peak intensity of right and left ventricular chamber opacification were scored on a scale ranging from 1 (no contrast or traces only) to 5 (attenuation). After each injection, the time for contrast appearance in the right ventricle was similar in all patients. Pulmonary transit time increased significantly during IPPV and was normal 5 min and 30 min after extubation. Right ventricular chamber opacification achieved high-grade intensity and remained constant before, during, and after IPPV. Conversely, although the baseline contrast injection resulted in high-grade left ventricular chamber opacification, the intensity decreased significantly during IPPV, remained low 5 min after extubation, and was normalized 30 min after extubation.

IMPLICATIONS

During intermittent positive pressure ventilation, i.v. sonicated albumin microbubbles pass through the lungs poorly and inefficiently opacify the left ventricle compared with the effects observed during spontaneous ventilation.