Michael J. Souter

Dexmedetomidine sedation during awake craniotomy for seizure resection: effects on electrocorticography.

Patients with refractory seizures may undergo awake craniotomy and cortical resection of the seizure area, using intraoperative functional mapping and electrocorticography (ECoG). We used dexmedetomidine in 6 patients, transitioning successively from the asleep-awake-asleep method, through a combined propofol/dexmedetomidine sedative infusion, to dexmedetomidine as the only sedation. Initial experience with the asleep-awake-asleep method in 2 patients was successful with the replacement of propofol/laryngeal mask anesthesia, 20 to 30 minutes before ECoG testing, by dexmedetomidine infusion, maintained at 0.2 mcg kg−1 h−1 throughout neurocognitive testing. Propofol anesthesia was reintroduced for resection. One patient received combined dexmedetomidine (0.2 mcg kg−1 h−1) and propofol (200 mcg kg−1 min−1) infusions for sedation. Both infusions were stopped 15 minutes before ECoG. Subsequently, they were restarted and the epileptic foci resected. Three patients received dexmedetomidine as the sole sedative agent, together with scalp block local anesthesia, and incremental boluses totaling 150 to 175 mcg of fentanyl per case. Dexmedetomidine was started with 0.3 mcg kg−1 boluses and maintained with 0.2 to 0.7 mcg kg−1 h−1 for craniotomy, testing, and resection. The infusion was paused for 20 minutes in 1 patient to allow improvement in neurocognitive testing. This occurred within 10 minutes. All patients enjoyed good hemodynamic control, with blood pressure maintained within 20% of initial values, and made uneventful recoveries. The surgical conditions were all reported as favorable. Dexmedetomidine can be used singly for sedation in awake craniotomy requiring ECoG. Individual dose ranges vary, but a bolus of 0.3 mcg kg−1 with an infusion of 0.2 mcg kg−1 min−1 is a good starting point, allowing accurate mapping of epileptic foci and subsequent resection.

Management guided by brain tissue oxygen monitoring and outcome following severe traumatic brain injury.

OBJECT The authors sought to describe changes in clinical management associated with brain tissue oxygen (PbO(2)) monitoring and how these changes affected outcomes and resource utilization. METHODS The cohort study comprised 629 patients admitted to a Level I trauma center with a diagnosis of severe traumatic brain injury over a period of 3 years. Hospital mortality rate, neurological outcome, and resource utilization of 123 patients who underwent both PbO(2) and intracranial pressure (ICP) monitoring were compared with the same measures in 506 patients who underwent ICP monitoring only. The main outcomes were hospital mortality rate, functional independence at hospital discharge, duration of mechanical ventilation, hospital length of stay, and hospital cost. Multivariable regression with robust variance was used to estimate the adjusted differences in the main outcome measures between patient groups. The models were adjusted for patient age, severity of injury, and pathological features seen on head CT scan at admission. RESULTS On average, patients who underwent ICP/PbO(2) monitoring were younger and had more severe injuries than patients who received ICP monitoring alone. Relatively more patients treated with PbO(2) monitoring received osmotic therapy, vasopressors, and prolonged sedation. After adjustment for baseline characteristics, the hospital mortality rate was, if anything, slightly higher in patients undergoing PbO(2)-guided management than in patients monitored with ICP only (adjusted mortality difference 4.4%, 95% CI -3.9 to 13%). Patients who underwent PbO(2)-guided management also had lower adjusted functional independence scores at hospital discharge (adjusted score difference -0.75, 95% CI -1.41 to -0.09). There was a 27% relative increase (95% CI 6-53%) in the median hospital length of stay when the PbO(2) group was compared with the ICP-only group. CONCLUSIONS The mortality rate in patients with traumatic brain injury whose clinical management was guided by PbO(2) monitoring was not reduced in comparison with that in patients who received ICP monitoring alone. Brain tissue oxygen monitoring was associated with worse neurological outcome and increased hospital resource utilization.

Clinical experience with dexmedetomidine for implantation of deep brain stimulators in Parkinson's disease

The pharmacologic profile of the α-2 agonist dexmedetomidine (Dex) suggests that it may be an ideal sedative drug for deep brain stimulator (DBS) implantation. We performed a retrospective chart review of anesthesia records of patients who underwent DBS implantation from 2001 to 2004. In 2003, a clinical protocol with Dex sedation for DBS implantation was initiated. Demographic data, use of antihypertensive medication, and duration of mapping were compared between patients who received Dex (11 patients/13 procedures) and patients who did not receive any sedation (controls: 8 patients/9 procedures). There were no differences in severity of illness between the two groups. Dex provided patient comfort and surgical satisfaction with mapping in all cases, and significantly reduced the use of antihypertensive medication (54% in the Dex group, versus 100% in controls, P = 0.048). In DBS implantation, sedation with Dex did not interfere with electrophysiologic mapping, and provided hemodynamic stability and patient comfort. Routine use of Dex in these procedures may be indicated.

Effect of Equiosmolar Solutions of Mannitol versus Hypertonic Saline on Intraoperative Brain Relaxation and Electrolyte Balance

Background:The purpose of the study was to compare the effect of equiosmolar solutions of mannitol and hypertonic saline (HS) on brain relaxation and electrolyte balance. Methods:After institutional review board approval and informed consent, patients with American Society of Anesthesiologists physical status II–IV, scheduled to undergo craniotomy for various brain pathologies, were enrolled into this prospective, randomized, double-blind study. Patients received 5 ml/kg 20% mannitol (n = 20) or 3% HS (n = 20). Partial pressure of carbon dioxide in arterial blood was maintained at 35–40 mmHg, and central venous pressure was maintained at 5 mmHg or greater. Hemodynamic variables, fluid balance, blood gases, electrolytes, lactate, and osmolality (blood, cerebrospinal fluid, urine) were measured at 0, 15, 30, and 60 min and 6 h after infusion; arteriovenous difference of oxygen, glucose, and lactate were calculated. The surgeon assessed brain relaxation on a four-point scale (1 = relaxed, 2 = satisfactory, 3 = firm, 4 = bulging). Appropriate statistical tests were used for comparison; P < 0.05 was considered significant. Results:There was no difference in brain relaxation (mannitol = 2, HS = 2 points; P = 0.8) or cerebral arteriovenous oxygen and lactate difference between HS and mannitol groups. Urine output with mannitol was higher than with HS (P < 0.03) and was associated with higher blood lactate over time (P < 0.001, compared with HS). Cerebrospinal fluid osmolality increased at 6 h in both groups (P < 0.05, compared with baseline). HS caused an increase in sodium in cerebrospinal fluid over time (P < 0.001, compared with mannitol). Conclusion:Mannitol and HS cause an increase in cerebrospinal fluid osmolality, and are associated with similar brain relaxation scores and arteriovenous oxygen and lactate difference during craniotomy.

Equipment-related Electrocardiographic Artifacts : Causes, Characteristics, Consequences, and Correction

Interference of the monitored or recorded electrocardiogram is common within operating room and intensive care unit environments. Artifactual signals, which corrupt the normal cardiac signal, may arise from internal or external sources. Electrical devices used in the clinical setting can induce artifacts by various different mechanisms. Newer diagnostic and therapeutic modalities may generate artifactual changes. These artifacts may be nonspecific or may resemble serious arrhythmia. Clinical signs, along with monitored waveforms from other simultaneously monitored parameters, may provide the clues to differentiate artifacts from true changes on the electrocardiogram. Simple measures, such as proper attention to basic principles of electrocardiographic measurement, can eliminate some artifacts. However, in persistent cases, expert help may be required to identify the precise source and minimize interference on the electrocardiogram. Technological advancements in processing the electrocardiographic signal may be useful to detect and eliminate artifacts. Ultimately, an improved understanding of the artifacts generated by equipment, and their identifying characteristics, is important to avoid misinterpretation, misdiagnosis, and iatrogenic complication.

Recommendations for the Critical Care Management of Devastating Brain Injury: Prognostication, Psychosocial, and Ethical Management

Devastating brain injuries (DBIs) profoundly damage cerebral function and frequently cause death. DBI survivors admitted to critical care will suffer both intracranial and extracranial effects from their brain injury. The indicators of quality care in DBI are not completely defined, and despite best efforts many patients will not survive, although others may have better outcomes than originally anticipated. Inaccuracies in prognostication can result in premature termination of life support, thereby biasing outcomes research and creating a self-fulfilling cycle where the predicted course is almost invariably dismal. Because of the potential complexities and controversies involved in the management of devastating brain injury, the Neurocritical Care Society organized a panel of expert clinicians from neurocritical care, neuroanesthesia, neurology, neurosurgery, emergency medicine, nursing, and pharmacy to develop an evidence-based guideline with practice recommendations. The panel intends for this guideline to be used by critical care physicians, neurologists, emergency physicians, and other health professionals, with specific emphasis on management during the first 72-h post-injury. Following an extensive literature review, the panel used the GRADE methodology to evaluate the robustness of the data. They made actionable recommendations based on the quality of evidence, as well as on considerations of risk: benefit ratios, cost, and user preference. The panel generated recommendations regarding prognostication, psychosocial issues, and ethical considerations.

Clinical features of fever associated with poor outcome in severe pediatric traumatic brain injury.

Abstract: We describe the incidence and etiology of fever and the relationship between fever characteristics and outcome in children with severe traumatic brain injury (TBI). We conducted a retrospective study of children <14 years and with Glasgow Coma Scale (GCS) score of <9 admitted to a level I pediatric trauma center intensive care unit (PICU) between 1998 and 2003. We examined whether fever characteristics were associated with poor outcome (hospital discharge GCS score <13 and discharge disposition of either death or discharge to a skilled nursing facility). PICU length of stay (LOS) and hospital LOS were also examined. Data are presented as means and medians (SD), and P < 0.05 reflects significance. Ninety-three records were reviewed. Patients were 5.7 (SD 4.1) years old, 70% were male, and the average admission GCS score was 5. Mortality rate was 14%. Forty-eight (52%) patients had fever, and 23 (48%) of those patients had infectious fever. Each additional febrile episode was associated with a twofold higher risk of patients having a hospital discharge GCS score of <13 (odds ratio 2.4, 95% confidence interval 1.2-5.0) and having a 0.4-day longer PICU LOS (P < 0.001). Patients with infectious fever had a 0.9-day longer PICU LOS (P < 0.001). Patients with any fever in the PICU had an increased HLOS (0.9 days; P < 0.001). Our data suggest that in severe pediatric TBI, both fever and infection were common, and both were associated with longer LOS. Patients with higher fever burden had poor hospital discharge GCS score.

Subarachnoid lumbar drains: A case series of fractured catheters and a near miss

PurposeLumbar subarachnoid catheters for cerebrospinal fluid (CSF) drainage (lumbar drains) are indicated for several medical and surgical conditions. A number of complications can occur from the placement of this type of catheter, including catheter breakage from excessive traction or shearing over the Tuohy needle.Clinical featuresFive cases of lumbar subarachnoid catheter breakage/shearing and catheter fragment retention, as well as one near miss, were identified over a one-year period at a single institution. All (n = 6) patients were undergoing neurosurgical procedures. Four patients required surgical retrieval of the catheter fragments. No patient experienced log-term neurological sequelae.DiscussionFrom these experiences, the following risks factors for catheter rupture are identified: 1) intentional or accidental retraction of the catheter through the needle during placement; 2) faulty use of the guidewire; or 3) use of excessive force during removal of the catheter. Methods to prevent such complications are suggested, including minimal use, or complete avoidance of a guidewire.RésuméObjectifLes cathéters lombaires sous-arachnoïdiens pour le drainage (drains lombaires) du liquide céphalorachidien (LCR) sont indiqués pour de nombreuses conditions médicales et chirurgicales. Un nombre de complications peut survenir lors du positionnement de ce type de cathéter, y compris un bris de cathéter dû à une traction excessive ou à un cisaillement de l’aiguille Tuohy.Éléments cliniquesCinq cas de brisldsaillement de cathéter lombaire sous-arachnoïdien et de rétention de fragment de cathéter, ainsi qu’un « near miss», ont été identifiés au cours d’une période d’une année dans une seule institution. Tous les patients (n = 6) subissaient des procédures neurochirurgicales. Quatre patients ont nécessité une récupération chirurgicale des fragments de cathéter. Aucun patient n’a souffert de séquelles neurologiques a long terme.DiscussionNous avons pu identifier les facteurs de risque suiv-ants pour le bris de cathéter suite à ces expériences : 1) rétraction intentionnelle ou accidentelle du cathéter à travers l’aiguille pendant le positionnement; 2) mauvais usage du fil guide; ou 3) utilisation de force excessive pendant l’extraction du cathéter. Certaines méthodes afin de prévenir de telles complications sont suggérées, y compris une utilisation minimale, voire nulle, du fil guide.

Recommendations for the critical care management of devastating brain injury: prognostication, psychosocial, and ethical management : a position statement for healthcare professionals from the neurocritical care society

Devastating brain injuries (DBIs) profoundly damage cerebral function and frequently cause death. DBI survivors admitted to critical care will suffer both intracranial and extracranial effects from their brain injury. The indicators of quality care in DBI are not completely defined, and despite best efforts many patients will not survive, although others may have better outcomes than originally anticipated. Inaccuracies in prognostication can result in premature termination of life support, thereby biasing outcomes research and creating a self-fulfilling cycle where the predicted course is almost invariably dismal. Because of the potential complexities and controversies involved in the management of devastating brain injury, the Neurocritical Care Society organized a panel of expert clinicians from neurocritical care, neuroanesthesia, neurology, neurosurgery, emergency medicine, nursing, and pharmacy to develop an evidence-based guideline with practice recommendations. The panel intends for this guideline to be used by critical care physicians, neurologists, emergency physicians, and other health professionals, with specific emphasis on management during the first 72-h post-injury. Following an extensive literature review, the panel used the GRADE methodology to evaluate the robustness of the data. They made actionable recommendations based on the quality of evidence, as well as on considerations of risk: benefit ratios, cost, and user preference. The panel generated recommendations regarding prognostication, psychosocial issues, and ethical considerations.

Randomized pilot trial of intensive management of blood pressure or volume expansion in subarachnoid hemorrhage (improves)

BACKGROUND Volume expansion and hypertension are widely used for the hemodynamic management of patients with subarachnoid hemorrhage. OBJECTIVE To investigate the feasibility, adherence, and retention in a trial of volume expansion and blood pressure manipulation to prevent delayed cerebral ischemia. METHODS A randomized pilot trial using a 2-way factorial design allocating patients within 72 hours of subarachnoid hemorrhage to either normovolemia (NV) or volume expansion (HV) and simultaneously to conventional (CBP) or augmented blood pressure (ABP) for 10 days. The study endpoints were protocol adherence and retention to follow-up. The quality of endpoints for a larger trial were 6-month modified Rankin Scale score, comprehensive neurobehavioral assessment, delayed cerebral ischemia, new stroke, and discharge disposition. RESULTS Twenty patients were randomized and completed follow-up. The overall difference in daily mean intravenous fluid intake was 2099 mL (95% confidence interval [CI]: 867, 3333), HV vs NV group. The overall mean systolic blood pressure difference was 5 mm Hg (95% CI: -4.65, 14.75), ABP vs CBP group. Adverse events included death (n=1), delayed cerebral ischemia (n=1), and pulmonary complications (n=3). There were no differences in modified Rankin Scale score between HV and NV (difference 0.1; 95% CI: -1.26, 1.46, P=.87) or between ABP and CBP groups (-0.5, 95% CI: -1.78, 0.78, P=.43). Neuropsychological scores were similar between HV vs NV, but tended to be worse in ABP (57±27) vs CBP group (85±21, P=.04). CONCLUSION This pilot study showed adequate feasibility and excellent retention to follow-up. Given the suggestion of possible worse neurobehavioral outcome with ABP, a larger trial to determine the optimal blood pressure management in this patient population is warranted. (ClinTrials.gov NCT01414894.)