Refinement of embolic stroke model in rats: Effect of post-embolization anesthesia duration on arterial blood pressure, cerebral edema and mortality.

BACKGROUND: Injection of a clot into the internal carotid artery is an experimental model of ischemic stroke that is considered to closely mimic embolic stroke in humans. In this model, the common carotid artery typically remains temporarily occluded to permit time for stabilization of the clot in the middle cerebral artery. However, the associated lengthening of the anesthesia duration could affect arterial blood pressure and stroke outcome. NEW METHOD: We refined the model by examining how increasing isoflurane anesthesia duration from 30 to 60 min after clot embolization affects mortality, infarct volume, edema, blood-brain barrier permeability, and the 8-h post-ischemic time course of blood pressure, which has not been reported previously in this model. RESULTS: We found that arterial pressure increased after discontinuing anesthesia in both embolized groups and that the increase was greater than in the corresponding non-embolized sham-operated rats. At 24 h, the group with 60-min post-ischemia anesthesia exhibited greater brain water content and a greater ipsilateral-to-contralateral ratio of extravasated Evans blue dye. Mortality was greater in the 60-min group, but infarct volume among survivors was not different from that in the 30-min anesthesia group. COMPARISON WITH EXISTING METHODS: This study refines the embolic stroke model by demonstrating the importance of minimizing the duration of anesthesia after embolization. CONCLUSIONS: These data indicate that early discontinuation of isoflurane anesthesia after clot embolization permits an earlier hypertensive response that limits edema formation and mortality without significantly affecting infarct volume in survivors, thereby decreasing the required number of animals.

Applying JIT principles to resident education to reduce patient delays: a pilot study in an academic medical center pain clinic.

OBJECTIVES: This study investigated the effect on patient waiting times, patient/doctor contact times, flow times, and session completion times of having medical trainees and attending physicians review cases before the clinic session. The major hypothesis was that review of cases prior to clinic hours would reduce waiting times, flow times, and use of overtime, without reducing patient/doctor contact time. DESIGN: Prospective quality improvement. SETTING: Specialty pain clinic within Johns Hopkins Outpatient Center, Baltimore, MD, United States. PARTICIPANTS: Two attending physicians participated in the intervention. Processing times for 504 patient visits are involved over a total of 4 months. INTERVENTION: Trainees were assigned to cases the day before the patient visit. Trainees reviewed each case and discussed it with attending physicians before each clinic session. PRIMARY AND SECONDARY OUTCOME MEASURES: Primary measures were activity times before and after the intervention. These were compared and also used as inputs to a discrete event simulation to eliminate differences in the arrival process as a confounding factor. RESULTS: The average time that attending physicians spent teaching trainees while the patient waited was reduced, but patient/doctor contact time was not significantly affected. These changes reduced patient waiting times, flow times, and clinic session times. CONCLUSIONS: Moving some educational activities ahead of clinic time improves patient flows through the clinic and decreases congestion without reducing the times that trainees or patients interact with physicians.

Patient punctuality and clinic performance: observations from an academic-based private practice pain centre: a prospective quality improvement study.

OBJECTIVES: The aim of this study was to examine the effects of an intervention to alter patient unpunctuality. The major hypothesis was that the intervention will change the distribution of patient unpunctuality by decreasing patient tardiness and increasing patient earliness. DESIGN: Prospective Quality Improvement. SETTING: Specialty Pain Clinic in suburban Baltimore, Maryland, USA. PARTICIPANTS: The patient population ranged in age from 18 to 93 years. All patients presenting to the clinic during the study period were included in the study. The average monthly volume was 86.2 (SD=13) patients. A total of 1500 patient visits were included in this study. INTERVENTIONS: We tracked appointment times and patient arrival times at an ambulatory pain clinic. An intervention was made in which patients were informed that tardy patients would not be seen and would be rescheduled. This policy was enforced over a 12-month period. PRIMARY AND SECONDARY OUTCOME MEASURES: The distribution of patient unpunctuality was developed preintervention and at 12 months after implementation. Distribution parameters were used as inputs to a discrete event simulation to determine effects of the change in patient unpunctuality on clinic delay. RESULTS: Data regarding patient unpunctuality were gathered by direct observation before and after implementation of the intervention. The mean unpunctuality changed from -20.5 min (110 observations, SD=1.7) preintervention to -23.2 (169, 1.2) at 1 month after the intervention, -23.8 min (69, 1.8) at 6 months and -25.0 min (71, 1.2) after 1 year. The unpunctuality 12 months after initiation of the intervention was significantly different from that prior to the intervention (p<0.05). CONCLUSIONS: Physicians and staff are able to alter patient arrival patterns to reduce patient unpunctuality. Reducing tardiness improves some measures of clinic performance, but may not always improve waiting times. Accommodating early arriving patients does serve to improve clinic performance.

Variability in blood and blood component utilization as assessed by an anesthesia information management system.

BACKGROUND: Data can be collected for various purposes with anesthesia information management systems. The authors describe methods for using data acquired from an anesthesia information management system to assess intraoperative utilization of blood and blood components. METHODS: Over an 18-month period, data were collected on 48,086 surgical patients at a tertiary care academic medical center. All data were acquired with an automated anesthesia recordkeeping system. Detailed reports were generated for blood and blood component utilization according to surgical service and surgical procedure, and for individual surgeons and anesthesiologists. Transfusion hemoglobin trigger and target concentrations were compared among surgical services and procedures, and between individual medical providers. RESULTS: For all patients given erythrocytes, the mean transfusion hemoglobin trigger was 8.4 ± 1.5, and the target was 10.2 ± 1.5 g/dl. Variation was significant among surgical services (trigger range: 7.5 ± 1.2-9.5 ± 1.1, P = 0.0001; target range: 9.1 ± 1.2-11.3 ± 1.4 g/dl, P = 0.002), surgeons (trigger range: 7.2 ± 0.7-9.8 ± 1.0, P = 0.001; target range: 8.8 ± 0.9-11.8 ± 1.3 g/dl, P = 0.001), and anesthesiologists (trigger range: 7.2 ± 0.8-9.6 ± 1.2, P = 0.001; target range: 9.0 ± 0.9-11.7 ± 1.3 g/dl, P = 0.0004). The use of erythrocyte salvage, fresh frozen plasma, and platelets varied threefold to fourfold among individual surgeons compared with their peers performing the same surgical procedure. CONCLUSIONS: The use of data acquired from an anesthesia information management system allowed a detailed analysis of blood component utilization, which revealed significant variation among surgical services and surgical procedures, and among individual anesthesiologists and surgeons compared with their peers. Incorporating these methods of data acquisition and analysis into a blood management program could reduce unnecessary transfusions, an outcome that may increase patient safety and reduce costs.

Using process analysis to assess the impact of medical education on the delivery of pain services: a natural experiment.

BACKGROUND: The medical, social, and economic effects of the teaching mission on delivery of care at an academic medical center (AMC) are not fully understood. When a free-standing private practice ambulatory clinic with no teaching mission was merged into an AMC, a natural experiment was created. The authors compared process measures across the two settings to observe the differences in system performance introduced by the added steps and resources of the AMC's teaching mission. METHODS: After creating process maps based on activity times realized in both settings, the authors developed discrete-event simulations of the two environments. The two settings were comparable in the levels of key resources, but the AMC process flow included three residents/fellows. Simulation enabled the authors to consider an identical schedule across the two settings. RESULTS: Under identical schedules, the average accumulated processing time per patient was higher in the AMC. However, the use of residents allowed simultaneous processing of multiple patients. Consequently, the AMC had higher throughput (3.5 vs. 2.7 patients per hour), higher room utilization (82.2% vs. 75.5%), reduced utilization of the attending physician (79.0% vs. 93.4%), and a shorter average waiting time (30.0 vs. 83.9 min). In addition, the average completion time for the final patient scheduled was 97.9 min less, and the average number of patients treated before incurring overtime was 37.9% greater. CONCLUSIONS: Although the teaching mission of the AMC adds processing steps and costs, the use of trainees within the process serves to increase throughput while decreasing waiting times and the use of overtime.

Pilot implementation of a perioperative protocol to guide operating room-to-intensive care unit patient handoffs.

OBJECTIVES: Perioperative handoffs are a particularly high-risk period given patients' postprocedural physiology, their physical transport through the hospital, and the triad transfer of personnel, information, and technology. The authors piloted a new perioperative handoff process to guide patient transfers from the cardiac operating room (OR) to the cardiac surgical intensive care unit (CSICU). The aim of the study was to evaluate the impact of a standardized handoff process on patient care and provider satisfaction. DESIGN: A prospective, unblinded intervention study. SETTING: A CSICU in a teaching hospital. PARTICIPANTS: Two hundred thirty-eight health care practitioners during the transfer of care of 60 patients. INTERVENTIONS: The implementation of a standardized handoff protocol and checklist. MEASUREMENTS AND MAIN RESULTS: After the protocol's implementation, the presence of all handoff core team members at the bedside increased from 0% at baseline to 68% after intervention. The percentage of missed information in the surgery report decreased from 26% to 16% (p = 0.03), but the percentage of missed information in the anesthesia report showed no significant change (19% to 17%, p > 0.05). Handoff satisfaction scores among intensive care unit (ICU) nurses increased from 61% to 81%. On average, the duration of handoff increased by 1 minute. CONCLUSIONS: A standardized handoff protocol that guides the transfer of care from the OR team to the CSICU team can reduce the risk of missed information and improve satisfaction among perioperative providers.

Operating room debriefings.

This tool helps assess factors that positively and negatively contributed to an adverse event, near miss, or inefficiency during an operation-or any procedure.

Operating room briefings: working on the same page.

This tool, which takes one or two minutes to use, provides a structured approach to promote effective interdisciplinary communication and teamwork in the operating room--or any other area, such as an intensive care unit, inpatient unit, or outpatient clinic.

Role of nitric oxide scavenging in vascular response to cell-free hemoglobin transfusion.

Modified Hb solutions have been developed as O(2) carrier transfusion fluids, but of concern is the possibility that increased scavenging of nitric oxide (NO) within the plasma will alter vascular reactivity even if the Hb does not readily extravasate. The effect of decreasing hematocrit from approximately 30% to 18% by an exchange transfusion of a 6% sebacyl cross-linked tetrameric Hb solution on the diameter of pial arterioles possessing tight endothelial junctions was examined through a cranial window in anesthetized cats with and without a NO synthase (NOS) inhibitor. Superfusion of a NOS inhibitor decreased diameter, and subsequent Hb transfusion produced additional constriction that was not different from Hb transfusion alone but was different from the dilation observed by exchange transfusion of an albumin solution after NOS inhibition. In contrast, abluminal application of the cross-linked Hb produced constriction that was attenuated by the NOS inhibitor. Neither abluminal nor intraluminal cross-linked Hb interfered with pial arteriolar dilation to cromakalim, an activator of ATP-sensitive potassium channels. Pial vascular reactivity to hypocapnia and hypercapnia was unaffected by Hb transfusion. Microsphere-determined regional blood flow indicated selective decreases in perfusion after Hb transfusion in the kidney, small intestine, and neurohypophysis, which does not have tight endothelial junctions. Administration of a NOS inhibitor to reduce the basal level of NO available for scavenging before Hb transfusion prevented further decreases in blood flow to these regions compared with NOS inhibition alone. In contrast, blood flow to skeletal and left ventricular muscle increased, and cerebral blood flow was unchanged after Hb transfusion. This cross-linked Hb tetramer is known to appear in renal lymph but not in urine. We conclude that cell-free tetrameric Hb does not scavenge sufficient NO in the plasma space to significantly affect baseline tone in vascular beds with tight endothelial junctions but does produce substantial constriction in beds with porous endothelium. The data support increasing the molecular size of Hb by polymerization or conjugation to limit extravasation in all vascular beds to preserve normal vascular reactivity.

Respiratory failure as a first presentation of myasthenia gravis.

BACKGROUND: Although respiratory failure commonly occurs during the course of myasthenia gravis (MG), it is rarely described at presentation in patients with previously unrecognized MG. MATERIAL/METHODS: We determined the prevalence and clinical characteristics of patients with respiratory failure associated with undiagnosed MG by review of the medical records of all patients who were diagnosed with MG related respiratory failure at four University hospitals. Respiratory failure was defined on the basis of a forced vital capacity < or =1 liter, negative inspiratory force < or =20 cm H2O, or requirement of mechanical ventilation. RESULTS: Out of 51 MG patients with respiratory failure, 7(14%) patients had no previous diagnosis of MG. Another patient was identified after the review. The mean age of these 8 patients was 56 years (range 23-76 years); six were women. Five had previous episodes of unexplained respiratory failure. On initial evaluation, ocular or bulbar signs were present in 7 patients. The diagnosis of MG was made by edrophonium test (n=3), edrophonium test with positive acetylcholine antibody levels or repetitive nerve stimulation (n=2), repetitive nerve stimulation with positive acetylcholine antibody levels (n=2), and positive acetylcholine antibody levels alone (n=1). Seven patients required mechanical ventilation. Plasma exchange (n=7) or intravenous immunoglobulins (n=1) resulted in successful extubation or resolution of symptoms in all patients. CONCLUSIONS: Respiratory failure can occur at presentation in MG. A high index of suspicion should be maintained in patients with previous history of unexplained respiratory failures.

Hypertonic saline solutions in brain injury.

PURPOSE OF REVIEW: Hypertonic saline solutions have received renewed attention as effective agents for the treatment of cerebral edema and in brain resuscitation in a variety of brain injury paradigms. Although evidence of the beneficial action of hypertonic saline solutions in traumatic brain injury is robust, data supporting use in other conditions are only now mounting. RECENT FINDINGS: Osmotic properties of hypertonic saline solutions have been well studied in laboratory-based studies in animal models and in patients with acute brain injury. There are, in addition, emerging data on the extraosmotic actions on brain pathophysiology. This review cites baseline literature and provides new evidence of actions of hypertonic saline solutions: (a). in augmenting cerebral blood flow after subarachnoid hemorrhage, (b). as an antiinflammatory adjunct, and (c). utility in chemonucleolysis for intervertebral disc disease and treatment of seizures associated with severe hyponatremia. SUMMARY: Brain injury from diverse etiologies including trauma, ischemic stroke, global cerebral ischemia from cardiac arrest, intraparenchymal or subarachnoid hemorrhage, infection, or toxic-metabolic derangements are commonly encountered in the clinical setting. Many of these conditions are associated with cerebral edema with or without elevated intracranial pressure. Osmotherapy constitutes the cornerstone of medical therapy for such patients. Hypertonic saline solutions have received renewed attention in clinical practice as osmotic agents for cerebral resuscitation. This article reviews experimental and clinical evidence of the efficacy of hypertonic saline solutions and elaborates on their use in patients with acute neurologic injury. Important areas for current and future research are highlighted before the use of hypertonic saline solutions can be accepted for widespread use.

Neurologic intensive care resource use after brain tumor surgery: an analysis of indications and alternative strategies.

OBJECTIVE: Greater demand and limited resources for intensive care monitoring for patients with neurologic disease may change patterns of intensive care unit utilization. The necessity and duration of intensive care unit management for all neurosurgical patients after brain tumor resection are not clear. This study evaluates a) the preoperative and perioperative variables predictive of extended need for intensive care unit monitoring (>1 day); and b) the type and timing of intensive care unit resources in patients for whom less intensive postoperative monitoring may be feasible. DESIGN: Retrospective chart review. SETTING: A neurocritical care unit of a university teaching hospital. PATIENTS: Patients were 158 consecutive postoperative brain tumor resection patients admitted to a neurocritical care unit within a 1-yr period (1998-1999). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Twenty-three patients (15%) admitted to the neurocritical care unit for >24 hrs were compared with 135 (85%) patients admitted for <24 hrs. Predictors of >1-day stay in the neurocritical care unit in a logistic regression model were a tumor severity index comprising radiologic characteristics of tumor location, mass effect, and midline shift on the preoperative magnetic resonance imaging scan (odds ratio, 12.5; 95% confidence interval, 3.1-50.5); an intraoperative fluid score comprising estimated blood loss, total volume of crystalloid, and other colloid/hypertonic solutions administered (odds ratio, 1.8; 95% confidence interval, 1.2-2.6); and postoperative intubation (odds ratio, 67.5; 95% confidence interval, 6.5-702.0). Area under the receiver operating characteristic curve for the model of independent predictors for staying >1 day in the neurocritical care unit was 0.91. Neurocritical care unit resource use was reviewed in detail for 134 of 135 patients who stayed in the neurocritical care unit for <1 day. Sixty-five (49%) patients required no interventions beyond postanesthetic care and frequent neurologic exams. A total of 226 intensive care unit interventions were performed (mean +/- sd, 1.7 +/- 2.6) in 69 (51%) patients. Ninety (67%) patients had no further interventions after the first 4 hrs. Neurocritical care unit resource use beyond 4 hrs, largely consisting of intravenous analgesic use (72% of orders), was significantly associated with female gender, benign tumor on frozen section biopsy, and postoperative intubation (chi-square, p <.05). CONCLUSIONS: A small fraction of patients require prolonged intensive care unit stay after craniotomy for tumor resection. A patient's risk of prolonged stay can be well predicted by certain radiologic findings, large intraoperative blood loss, fluid requirements, and the decision to keep the patient intubated at the end of surgery. Of those patients requiring intensive care unit resources beyond the first 4 hrs, the interventions may not be critical in nature. A prospective outcome study is required to determine feasibility, cost, and outcome of patients cared for in extended recovery and then transferred to a skilled nursing ward.

Change in perfusion in acute nondominant hemisphere stroke may be better estimated by tests of hemispatial neglect than by the National Institutes of Health Stroke Scale.

BACKGROUND AND PURPOSE: It has been reported that National Institutes of Health Stroke Scale (NIHSS) scores correlate poorly with hypoperfused tissue measured by perfusion-weighted imaging (PWI) in nondominant hemisphere stroke. We conducted 2 studies to determine whether tests of hemispatial neglect provide a better measure of hypoperfusion and reperfusion than NIHSS in nondominant hemisphere stroke. METHODS: In study 1, 74 patients with acute ischemic, supratentorial stroke were administered the NIHSS, tests of neglect or aphasia, and diffusion-weighted imaging (DWI) and PWI on day 1 (<24 hours from onset) of stroke. Pearson correlations between volumes of PWI/DWI abnormality and functional tests were calculated. In study 2, 10 patients with acute, nondominant hemisphere stroke who were candidates for intervention to restore perfusion underwent PWI, DWI, NIHSS, and a line cancellation test on days 1 and 3. Correlations between change in volumes of PWI/DWI abnormality and change in functional tests were calculated. RESULTS: In study 1, in nondominant hemisphere stroke, volume of PWI abnormality correlated significantly with neglect scores (r=0.71; P<0.002) but not with NIHSS scores (r=0.39; P=NS). In dominant hemisphere stroke, volume of PWI abnormality correlated better with aphasia scores (r=0.50; P=0.0001) than with NIHSS scores (r=0.45; P=0.001). In study 2, change in volume of hypoperfused tissue on PWI correlated with change in line cancellation performance (r=0.83; P=0.003) but not with change in NIHSS score (r=0.26; P=NS). CONCLUSIONS: Tests of hemispatial neglect may better reflect dysfunction and reperfusion than NIHSS for patients with nondominant hemisphere stroke.

Cerebrovascular response to decreased hematocrit: effect of cell-free hemoglobin, plasma viscosity, and CO2.

The effect of transfusing a nonextravasating, zero-link polymer of cell-free hemoglobin on pial arteriolar diameter, cerebral blood flow (CBF), and O2 transport (CBF x arterial O2 content) was compared with that of transfusing an albumin solution at equivalent reductions in hematocrit (approximately 19%) in anesthetized cats. The influence of viscosity was assessed by coinfusion of a high-viscosity solution of polyvinylpyrrolidone (PVP), which increased plasma viscosity two- to threefold. Exchange transfusion of a 5% albumin solution resulted in pial arteriolar dilation, increased CBF, and unchanged O2 transport, whereas there were no significant changes over time in a control group. Exchange transfusion of a 12% polymeric hemoglobin solution resulted in pial arteriolar constriction and unchanged CBF and O2 transport. Coinfusion of PVP with albumin produced pial arteriolar dilation that was similar to that obtained with transfusion of albumin alone. In contrast, coinfusion of PVP with hemoglobin converted the constrictor response to a dilator response that prevented a decrease in CBF. Pial arteriolar dilation to hypercapnia was unimpaired in groups transfused with albumin or hemoglobin alone but was attenuated in the largest vessels in albumin and hemoglobin groups coinfused with PVP. Unexpectedly, hypocapnic vasoconstriction was blunted in all groups after transfusion of albumin or hemoglobin alone or with PVP. We conclude that 1) the increase in arteriolar diameter after albumin transfusion represents a compensatory response that prevents decreased O2 transport at reduced O2-carrying capacity, 2) the decrease in diameter associated with near-normal O2-carrying capacity after cell-free polymeric hemoglobin transfusion represents a compensatory mechanism that prevents increased O2 transport at reduced blood viscosity, 3) pial arterioles are capable of dilating to an increase in plasma viscosity when hemoglobin is present in the plasma, 4) decreasing hematocrit does not impair pial arteriolar dilation to hypercapnia unless plasma viscosity is increased, and 5) pial arteriolar constriction to hypocapnia is impaired at reduced hematocrit independently of O2-carrying capacity.

Intracerebral hemorrhage and postpartum cerebral vasculopathy.

INTRODUCTION: Intracerebral hemorrhage (ICH) associated with pregnancy commonly occurs in the postpartum period in the setting of preeclampsia/eclampsia. We describe the clinical course of two patients with ICH due to postpartum cerebral vasculopathy in the absence of toxemia. METHODS: We reviewed two cases with ICH and postpartum vasculopathy in our hospital (1996-2001) and compared them with seven similar case reports from the literature. RESULTS: Mean age of all patients is 28.7+/-5.6 years (mean+/-S.D.). Toxemia of pregnancy was absent in all cases. ICHs were cortical in eight and putaminal in one patient. Erythrocyte sedimentation rate was elevated in two. Two cases rehemorrhaged during the same admission. No cerebral infarctions were reported. All patients had diffuse vasculopathy on conventional catheter angiography, with no clinical manifestations or laboratory data supportive of extracerebral or systemic vasculitis. Eight patients were treated with corticosteroids, two with additional cytotoxic agents and one with nimodipine alone. Improvement on follow-up cerebral angiography (catheter or MRA) and transcranial Doppler ultrasonography (TCD) was noted in eight cases. One did not have follow-up cerebral imaging but had an excellent clinical outcome. All cases had good to excellent functional recovery. CONCLUSIONS: Postpartum ICH in the absence of toxemia may be associated with isolated cerebral vasculopathy. The clinical course and functional outcome is good to excellent. This entity appears to be distinct from cerebral vasculitis, which is usually associated with poor outcome.