John F. Bebawy

Adenosine-Induced Flow Arrest to Facilitate Intracranial Aneurysm Clip Ligation: Dose-Response Data and Safety Profile

BACKGROUND: Adenosine-induced transient flow arrest has been used to facilitate clip ligation of intracranial aneurysms. However, the starting dose that is most likely to produce an adequate duration of profound hypotension remains unclear. We reviewed our experience to determine the dose-response relationship and apparent perioperative safety profile of adenosine in intracranial aneurysm patients. METHODS: This case series describes 24 aneurysm clip ligation procedures performed under an anesthetic consisting of remifentanil, low-dose volatile anesthetic, and propofol in which adenosine was used. The report focuses on the doses administered; duration of systolic blood pressure <60 mm Hg (SBP<60 mm Hg); and any cardiovascular, neurologic, or pulmonary complications observed in the perioperative period. RESULTS: A median dose of 0.34 mg/kg ideal body weight (range: 0.29–0.44 mg/kg) resulted in a SBP<60 mm Hg for a median of 57 seconds (range: 26–105 seconds). There was a linear relationship between the log-transformed dose of adenosine and the duration of a SBP<60 mm Hg (R2 = 0.38). Two patients developed transient, hemodynamically stable atrial fibrillation, 2 had postoperative troponin levels >0.03 ng/mL without any evidence of cardiac dysfunction, and 3 had postoperative neurologic changes. CONCLUSIONS: For intracranial aneurysms in which temporary occlusion is impractical or difficult, adenosine is capable of providing brief periods of profound systemic hypotension with low perioperative morbidity. On the basis of these data, a dose of 0.3 to 0.4 mg/kg ideal body weight may be the recommended starting dose to achieve approximately 45 seconds of profound systemic hypotension during a remifentanil/low-dose volatile anesthetic with propofol induced burst suppression.

Adenosine for temporary flow arrest during intracranial aneurysm surgery: a single-center retrospective review.

BACKGROUND:Clip application for temporary occlusion is not always practical or feasible. Adenosine is an alternative that provides brief periods of flow arrest that can be used to advantage in aneurysm surgery, but little has been published on its utility for this indication. OBJECTIVE:To report our 2-year consecutive experience with 40 aneurysms in 40 patients for whom we used adenosine to achieve temporary arterial occlusion during aneurysm surgery. METHODS:We retrospectively reviewed our clinical database between May 2007 and December 2009. All patients who underwent microsurgical clipping of intracranial aneurysms under adenosine-induced asystole were included. Aneurysm characteristics, reasons for adenosine use, postoperative angiographic and clinical outcome, cardiac complications, and long-term neurological follow-up with the modified Rankin Scale were noted. RESULTS:Adenosine was used for 40 aneurysms (10 ruptured, 30 unruptured). The most common indications for adenosine were aneurysm softening in 17 cases and paraclinoid location in 14 cases, followed by broad neck in 12 cases and intraoperative rupture in 6 cases. Troponins were elevated postoperatively in 2 patients. Echocardiography did not show acute changes in either. Clinically insignificant cardiac arrhythmias were noted in 5 patients. Thirty-six patients were available for follow-up. Mean follow-up was 12.8 months. The modified Rankin Scale score was 0 for 29 patients at the time of the last follow-up. Four patients had an modified Rankin Scale score of 1, and scores of 2 and 3 were found in 2 and 1 patients, respectively. CONCLUSION:Adenosine appears to allow safe flow arrest during intracranial aneurysm surgery. This can enhance the feasibility and safety of clipping in select circumstances.

Perioperative steroids for peritumoral intracranial edema: A review of mechanisms, efficacy, and side effects

There has been a renewed interest in the recent literature regarding the proposed benefits of systemic steroids in the perioperative period. Among these benefits are the relief of postoperative pain, the decrease in postoperative nausea, and a higher overall multiparameter quality of recovery. Perioperative steroids, however, are not without their potential drawbacks, including decreased immune function, hyperglycemia, and impaired wound healing. The use of perioperative steroids for brain tumor treatment and resection has been a component of therapy for approximately 50 years, owing primarily to their well-described, although poorly understood, effect in minimizing vasogenic peritumoral edema, and therefore intracranial pressure. This review seeks to highlight the history, mechanisms, therapeutic efficacy, and side effects of steroid use for brain tumors in the perioperative period.

Association of intracranial aneurysm and Loeys-Dietz syndrome: Case illustration, management, and literature review

BACKGROUND AND IMPORTANCE:Loeys-Dietz syndrome (LDS) is a newly described connective tissue disease associated with aortic aneurysms. A strong association between LDS and intracranial aneurysms has not yet been documented in the literature. We present the first detailed report of an intracranial aneurysm finding in an LDS patient. CLINICAL PRESENTATION:The patient is a 20-year-old female recently diagnosed with LDS and found to harbor 2 incidental intracranial aneurysms on a screening magnetic resonance angiography: a 3-mm right carotid ophthalmic aneurysm and an 8-mm partially fusiform paraclinoid carotid artery aneurysm. A standard left pterional craniotomy was performed. Intraoperative adenosine was used instead of temporary clipping because her vessels were extremely friable. After reconstruction, an intraoperative indocyanine green angiogram was obtained, confirming complete aneurysmal obliteration and internal carotid artery patency. CONCLUSION:This is the first detailed report of a clear association between intracranial aneurysms and LDS. An association between LDS and intracranial aneurysms, if substantiated in a larger study, has implications for aneurysm screening in this population. Such an association may shed light on mechanisms of aneurysm formation, growth, and rupture.

The Incidence of Unacceptable Movement with Motor Evoked Potentials During Craniotomy for Aneurysm Clipping

OBJECTIVE To review the experience at a single institution with motor evoked potential (MEP) monitoring during intracranial aneurysm surgery to determine the incidence of unacceptable movement. METHODS Neurophysiology event logs and anesthetic records from 220 craniotomies for aneurysm clipping were reviewed for unacceptable patient movement or reason for cessation of MEPs. Muscle relaxants were not given after intubation. Transcranial MEPs were recorded from bilateral abductor hallucis and abductor pollicis muscles. MEP stimulus intensity was increased up to 500 V until evoked potential responses were detectable. RESULTS Out of 220 patients, 7 (3.2%) exhibited unacceptable movement with MEP stimulation-2 had nociception-induced movement and 5 had excessive field movement. In all but one case, MEP monitoring could be resumed, yielding a 99.5% monitoring rate. CONCLUSIONS With the anesthetic and monitoring regimen, the authors were able to record MEPs of the upper and lower extremities in all patients and found only 3.2% demonstrated unacceptable movement. With a suitable anesthetic technique, MEP monitoring in the upper and lower extremities appears to be feasible in most patients and should not be withheld because of concern for movement during neurovascular surgery.

Adenosine-induced flow arrest to facilitate intracranial aneurysm clip ligation does not worsen neurologic outcome

BACKGROUND: When temporary arterial occlusion of the parent artery is difficult for anatomical reasons, or when inadvertent aneurysmal rupture occurs during surgical dissection, adenosine administration can be used to produce flow arrest and brief, profound systemic hypotension that can facilitate intracranial aneurysm clip ligation. There is a concern, however, that the flow arrest and profound hypotension produced by adenosine, although brief, may cause cerebral ischemia and therefore worsen neurologic outcome compared with other techniques to facilitate aneurysm clip ligation. Therefore, we performed a retrospective, case-control study to determine whether adenosine-induced flow arrest had negative effects on the neurologic outcome of our patients. METHODS: We reviewed the perioperative records of all patients in our intracranial aneurysm surgery outcomes database between August 1, 2006, and June 15, 2012. The primary outcome was the presence or absence of a poor neurologic outcome 48 hours after surgery, with a modified Rankin scale score >2 being defined as a poor neurologic outcome. The neurologic outcome at the time of hospital discharge was a secondary outcome. Secondary outcomes related to cardiac morbidity included atrial or ventricular arrhythmia requiring treatment and elevated cardiac biomarkers consistent with ischemia (i.e., Troponin-I). RESULTS: During the study period, adenosine-induced flow arrest was used in 72 of the 413 patients (17.4%) who underwent intracranial aneurysm clip ligation. The difference in the incidence of poor neurological outcome, with or without the use of adenosine, was no larger than 15.7% at 48 hours after surgery (P =0.524) or −12.7% at discharge (P = 0.741). In addition, the difference in the incidence of cardiac morbidity was no larger than −16.0% for persistent arrhythmia (P = 0.155) or −9.4% for biomarkers of myocardial ischemia (P = 0.898) in the initial 48 hours after surgery. CONCLUSION: When used to facilitate intracranial aneurysm clip ligation, adenosine-induced flow arrest was associated with no more than a 15.7% increase or a 12.7% decrease in the incidence of a poor neurologic outcome at either 48 hours or at the time of hospital discharge. In addition, adenosine use was not associated with cardiac morbidity in the perioperative period (i.e., persistent arrhythmia or biomarkers of cardiac ischemia).

Predicting major adverse cardiac events in spine fusion patients: Is the revised cardiac risk index sufficient?

Study Design. Observational cohort study. Objective. To determine the accuracy of the Revised Cardiac Risk Index (RCRI) in predicting major adverse cardiac events in patients undergoing spine fusion surgery of 3 levels or more. Summary of Background Data. Preoperative cardiac testing is extensively guided by the RCRI, which was developed and validated in thoracic, abdominal, and orthopedic surgical patients. Because multilevel spine fusion surgery is often associated with major transfusion, we hypothesize that the RCRI may not accurately characterize the risk of cardiovascular morbidity in these patients. Methods. After institutional review board approval, perioperative data were collected from 547 patients who underwent 3 or more levels of spinal fusion with instrumentation. Postoperative cardiac morbidity was defined as any combination of the following: arrhythmia requiring medical treatment, myocardial infarction (either by electrocardiographic changes or troponin elevation), or the occurrence of demand ischemia. The surgical complexity was categorized as anterior surgery only, posterior cervical and/or thoracic fusion, posterior lumbar fusion, or any surgery that included transpedicular osteotomies. Logistic regression analysis was performed to determine RCRI performance. Results. The RCRI performed no better than chance (area under the curve = 0.54) in identifying the 49 patients (9%) who experienced cardiac morbidity. Conclusion. The RCRI did not predict cardiac morbidity in our patients undergoing major spine fusion surgery, despite being extensively validated in low-risk noncardiac surgical patients. Preoperative testing and optimization decisions, previously based on the RCRI, may need to be revised to include more frequent functional cardiac imaging and more aggressive implementation of pharmacologic modalities that may mitigate cardiac morbidity, similar to the preoperative evaluation for major vascular surgery. Level of Evidence: 3

Compartment syndrome caused by a properly functioning infusion pump

Compartment syndrome caused by an infiltrated intravenous catheter has been previously reported, but there are no reports of compartment syndrome caused by fluids and/or medications dispensed by a properly functioning drug infusion pump. A case in which a commonly used drug infusion pump delivered propofol and remifentanil under high pressure, leading to compartment syndrome, is presented.

Is spinal anaesthesia at L2–L3 interspace safe in disorders of the vertebral column? A magnetic resonance imaging study

BACKGROUND The varying point at which the spinal cord terminates in the lumbar spinal canal may affect the incidence of spinal cord injuries associated with needle insertion for spinal anaesthesia, especially in patients with vertebral body or intervertebral disc disease. This is a complication which has been frequently reported when spinal needle insertion was performed at higher lumbar spinal levels. METHODS We retrospectively reviewed magnetic resonance images of the spine in 1047 Chinese patients to determine the conus medullaris terminus (CMT) in patients with and without vertebral disorders. Patients with tumours in and around the spine and those with congenital spinal anomalies were excluded from the study. Patients with mixed vertebral disorders were also excluded. RESULTS Our data demonstrate that patients with thoracic vertebral compression fractures had lower ending points of the CMT than those without (P<0.05), while patients with lumbar compression fractures did not demonstrate such a correlation. With regard to this difference, females were significantly at higher risk for a lower CMT than males. Conversely, lumbar disc disorders such as intervertebral disc extrusion, herniation, or bulging did not have any significant influence on the level of CMT. Moreover, patients with spondylolisthesis or scoliosis did not demonstrate an abnormal CMT location. CONCLUSIONS When performing spinal anaesthesia, anaesthesiologists should be aware of potential differences of the CMT location, particularly in female patients with thoracic vertebral compression fractures, who may have a lower CMT than normal, extending to the level of L2. Performing spinal anaesthesia at the L2-L3 interspace would seem to be ill-advised in this patient population.

A comparison of hemoglobin measured by co-oximetry and central laboratory during major spine fusion surgery.

BACKGROUND:Many factors affect the accuracy of hemoglobin concentration values. In this study, we evaluated whether the hemoglobin concentration obtained by means of arterial blood gas (ABG) co-oximetry and complete blood count (CBC) central laboratory techniques clinically correlate when using simultaneous measurements of hemoglobin concentration obtained during complex spine fusion surgery. METHODS:Three hundred forty-eight patients who underwent spinal fusion of >3 bony levels between September 2006 and September 2010, with concurrent ABG and CBC samples, were identified. The mean difference between pairs of measured hemoglobin values was determined using limits of agreement analysis. Error grid analysis was used to delineate correlation of samples in relation to hemoglobin values within the range considered for transfusion. RESULTS:The median difference (ABG-CBC) between the measured hemoglobin values was 0.4 g/dL (95% confidence interval [CI], 0.35–0.40 g/dL; P < 0.0001). Limits of agreement analysis correcting for repeated observations in multiple patients demonstrated that the mean difference between measured hemoglobin values (i.e., bias) was 0.4 g/dL (95% CI, 0.36–0.41 g/dL), and the 95% limits of agreement of the difference between paired measurements were −0.70 to 1.47 g/dL. The magnitude of the difference between the measured hemoglobin values was >0.5 g/dL in 44.5% of patients (95% CI, 42.2%–46.8%); however, 6.8% (95% CI, 5.8%–8.1%) of paired measurements had a difference of >1.0 g/dL. There was only fair-to-moderate agreement between the CBC and ABG values within the clinically significant range of hemoglobin values of 7 to 10 g/dL (Cohen &kgr; = 0.39; 95% CI, 0.33–0.45). CONCLUSIONS:The hemoglobin values obtained from ABG and CBC cannot be used interchangeably when verifying accuracy of novel point-of-care hemoglobin measurement modalities or when managing a patient with critical blood loss.