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Alan A. Artru, Kim Wright and Peter S. Colley

✓ This study examined the effect of hypocapnia (PaCO2 20 mm Hg) on cerebral metabolism and the electroencephalogram (EEG) findings in 12 dogs during nitroglycerin (NTG)-induced hypotension. Previous studies suggest that NTG is a more potent cerebral vasodilator than sodium nitroprusside or trimethaphan. It was speculated that combining hypocapnia with NTG-induced hypotension would cause less disturbance of cerebral metabolism and the EEG than the disturbances previously reported when hypocapnia was combined with hypotension induced by sodium nitroprusside or trimethaphan.

All 12 dogs were examined at 1) normocapnia with normotension; 2) hypocapnia with normotension; and 3) hypocapnia combined with NTG-induced hypotension to mean arterial blood pressure (MABP) levels of 60, 50, and 40 mm Hg. In six dogs the cerebral metabolic rate of oxygen was determined, and the EEG was evaluated using compressed spectral analysis. Brain tissue metabolites were calculated in the other six dogs. During normotension, hypocapnia caused no deterioration of cerebral metabolism or of the EEG. Hypocapnia combined with NTG-induced hypotension caused a decrease of the power of the α and β 2 spectra of the EEG at MABP's of 60 mm Hg or less. At an MABP of 40 mm Hg, brain tissue phosphocreatine and the cerebral energy charge decreased, while the brain tissue lactate:pyruvate ratio increased. Thirty minutes after restoration of normocapnia with normotension, cerebral metabolites returned to initial values, but the power of the EEG α and β 2 spectra was decreased compared to baseline values.

The cerebral metabolic disturbances and EEG alterations seen here with hypocapnia plus NTG-induced hypotension were similar to those previously reported with hypocapnia plus sodium nitroprusside-induced hypotension, and less than those previously reported with hypocapnia plus trimethaphan-induced hypotension. For hyperventilated patients, administration of NTG may be a better hypotensive treatment than trimethaphan, but similar in effect to sodium nitroprusside.

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Kim J. Burchiel

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Seung-Bo Lee, Hakseung Kim, Young-Tak Kim, Frederick A. Zeiler, Peter Smielewski, Marek Czosnyka and Dong-Joo Kim

OBJECTIVE

Monitoring intracranial and arterial blood pressure (ICP and ABP, respectively) provides crucial information regarding the neurological status of patients with traumatic brain injury (TBI). However, these signals are often heavily affected by artifacts, which may significantly reduce the reliability of the clinical determinations derived from the signals. The goal of this work was to eliminate signal artifacts from continuous ICP and ABP monitoring via deep learning techniques and to assess the changes in the prognostic capacities of clinical parameters after artifact elimination.

METHODS

The first 24 hours of monitoring ICP and ABP in a total of 309 patients with TBI was retrospectively analyzed. An artifact elimination model for ICP and ABP was constructed via a stacked convolutional autoencoder (SCAE) and convolutional neural network (CNN) with 10-fold cross-validation tests. The prevalence and prognostic capacity of ICP- and ABP-related clinical events were compared before and after artifact elimination.

RESULTS

The proposed SCAE-CNN model exhibited reliable accuracy in eliminating ABP and ICP artifacts (net prediction rates of 97% and 94%, respectively). The prevalence of ICP- and ABP-related clinical events (i.e., systemic hypotension, intracranial hypertension, cerebral hypoperfusion, and poor cerebrovascular reactivity) all decreased significantly after artifact removal.

CONCLUSIONS

The SCAE-CNN model can be reliably used to eliminate artifacts, which significantly improves the reliability and efficacy of ICP- and ABP-derived clinical parameters for prognostic determinations after TBI.

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Hakseung Kim, Hack-Jin Lee, Young-Tak Kim, Yunsik Son, Peter Smielewski, Marek Czosnyka and Dong-Joo Kim

OBJECTIVE

Failure of cerebral autoregulation and subsequent hypoperfusion is common during the acute phase of traumatic brain injury (TBI). The cerebrovascular pressure-reactivity index (PRx) indirectly reflects cerebral autoregulation and has been used to derive optimal cerebral perfusion pressure (CPP). This study provides a method for the use of a combination of PRx, CPP, and intracranial pressure (ICP) to better evaluate the extent of cerebral hypoperfusion during the first 24 hours after TBI, allowing for a more accurate prediction of mortality risk.

METHODS

Continuous ICP and arterial blood pressure (ABP) signals acquired from 295 TBI patients during the first 24 hours after admission were retrospectively analyzed. The CPP at the lowest PRx was determined as the optimal CPP (CPPopt). The duration of a severe hypoperfusion event (dHP) was defined as the cumulative time that the PRx was > 0.2 and the CPP was < 70 mm Hg with the addition of intracranial hypertension (ICP > 20 or > 22 mm Hg). The outcome was determined as 6-month mortality.

RESULTS

The cumulative duration of PRx > 0.2 and CPP < 70 mm Hg exhibited a significant association with mortality (p < 0.001). When utilized with basic clinical information available during the first 24 hours after admission (i.e., Glasgow Coma Scale score, age, and mean ICP), a dHP > 25 minutes yielded a significant predictive capacity for mortality (p < 0.05, area under the curve [AUC] = 0.75). The parameter was particularly predictive of mortality for patients with a mean ICP > 20 or > 22 mm Hg (AUC = 0.81 and 0.87, respectively).

CONCLUSIONS

A short duration (25 minutes) of severe hypoperfusion, evaluated as lowered CPP during worsened cerebrovascular reactivity during the 1st day after TBI, is highly indicative of mortality.

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Peter Kim Nelson, Stephen M. Russell, Henry H. Woo, Anthony J. G. Alastra and Danko V. Vidovich

Object. The aim of this study was to describe the application of a novel transarterial approach to curative embolization of complex intracranial dural arteriovenous fistulas (DAVFs). This technique is particularly useful in patients harboring high-grade DAVFs with direct cortical venous drainage or for whom transvenous coil embolization is not possible because of limited sinus venous access to the fistula site due to thrombosis or stenotic changes.

Methods. Twenty-three DAVFs in 21 patients were treated using a transarterial N-butyl cyanoacrylate (NBCA) embolization technique with the aid of a wedged catheter. In all patients, definitive treatment involved two critical steps: 1) a microcatheter was wedged within a feeding artery, establishing flow-arrest conditions within the catheterized vessel distal to the microcatheter tip; and 2) NBCA was injected under these resultant flow-arrest conditions across the pathological arteriovenous connection and into the immediate draining venous apparatus, definitively occluding the fistula. Patient data were collected in a retrospective manner by reviewing office and inpatient charts and embolization reports, and by directly analyzing all procedural and diagnostic angiograms.

Eight patients presented with the principal complaint of tinnitus/bruit, five with intracranial hemorrhage, four with cavernous sinus syndrome, and one each with seizures, ataxia, visual field loss, and hiccups. The parent (recipient) venous structure of the DAVFs in this study included 11 leptomeningeal veins, eight transverse/sigmoid sinuses, three cavernous sinuses, and one sphenoparietal sinus. The NBCA permeated the arteriovenous shunt, perifistulous network, and proximal draining vein in all DAVFs. Occlusion was confirmed on postembolization angiography studies. No complication occurred in any patient in this series. There has been no recurrence during a mean follow up of 18.7 months (range 2–46 months).

Conclusions. Transarterial NBCA embolization with the aid of a wedged catheter in flow-arrest conditions is a safe and an effective treatment for intracranial DAVFs.

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S. Alex Rottgers, Peter D. Kim, Anand Raj Kumar, James J. Cray, Joseph E. Losee and Ian F. Pollack

Object

Sagittal craniosynostosis is the most common form of craniosynostosis and is commonly treated within the first year of life. Optimal treatment of patients older than 1 year of age is not well characterized. The authors reviewed cases of sagittal craniosynostosis involving patients who were treated surgically at their institution when they were older than 1 year in order to determine the rate of intracranial hypertension (ICH), potential to develop nonhealing cranial defects, and the need for various surgical procedures to treat the more mature phenotype.

Methods

A retrospective chart review was conducted of all cases in the Children's Hospital of Pittsburgh Neurosurgery Database involving patients who underwent cranial vault remodeling for scaphocephaly after 1 year of age between October 2000 and December 2010.

Results

Ten patients were identified who met the inclusion criteria. Five patients underwent anterior two-thirds cranial vault remodeling procedures, 3 patients underwent posterior vault remodeling, and 2 patients underwent 2-staged total vault remodeling. All patients had improved head shapes, and mean cephalic indices improved from 65.4 to 69.1 (p = 0.05). Six patients exhibited signs of ICH. No patients with more than 3 months of follow-up exhibited palpable calvarial defects.

Conclusions

Patients with sagittal synostosis treated after 1 year of age demonstrate increased rates of ICH, warranting diligent evaluations and surveillance to detect it; rarely develop clinically significant cranial defects if appropriate bone grafting is performed at the time of surgery; and achieve acceptable improvements in head shape.

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Francis Lovecchio, Jeffrey G. Stepan, Ajay Premkumar, Michael E. Steinhaus, Maria Sava, Peter Derman, Han Jo Kim and Todd Albert

OBJECTIVE

Patients with lumbar spine pathology are at high risk for opioid misuse. Standardizing prescribing practices through an institutional intervention may reduce the overprescribing of opiates, leading to a decrease in the risk for opioid misuse and the number of pills available for diversion. Without quantitative data on the “minimum necessary quantity” of opioids appropriate for postdischarge prescriptions, the optimal method for changing existing prescribing practices is unknown. The purpose of this study was to determine whether mandatory provider education and prescribing guidelines could modify prescriber behavior and lead to a decreased amount of opioids prescribed at hospital discharge following lumbar spine surgery.

METHODS

Qualified staff were required to attend a mandatory educational conference, and a consensus method among the spine service was used to publish qualitative prescribing guidelines. Prescription data for 2479 patients who had undergone lumbar spine surgery were captured and compared based on the timing of surgery. The preintervention group consisted of 1177 patients who had undergone spine surgery in the period before prescriber education and guidelines (March 1, 2016–November 1, 2016). The postintervention group consisted of 1302 patients who had undergone spine surgery after the dissemination of the guidelines (February 1, 2017–October 1, 2017). Surgeries were classified as decompression or fusion procedures. Patients who had undergone surgeries for infection and patients on long-acting opioids were excluded.

RESULTS

For all lumbar spine surgeries (decompression and fusion), the mean amount of opioids prescribed at discharge was lower after the educational program and distribution of prescribing guidelines (629 ± 294 oral morphine equivalent [OME] preintervention vs 490 ± 245 OME postintervention, p < 0.001). The mean number of prescribed pills also decreased (81 ± 26 vs 66 ± 22, p < 0.001). Prescriptions for 81 or more tablets dropped from 65.5% to 25.5%. Tramadol was prescribed more frequently after prescriber education (9.9% vs 18.6%, p < 0.001). Refill rates within 6 weeks were higher after the institutional intervention (7.6% vs 12.4%, p < 0.07).

CONCLUSIONS

Qualitative guidelines and prescriber education are effective in reducing the amount of opioids prescribed at discharge and encouraging the use of weaker opioids. Coupling provider education with prescribing guidelines is likely synergistic in achieving larger reductions. The sustainability of these changes is yet to be determined.

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Jan-Karl Burkhardt, Omar Tanweer, Miguel Litao, Pankaj Sharma, Eytan Raz, Maksim Shapiro, Peter Kim Nelson and Howard A. Riina

OBJECTIVE

A systematic analysis on the utility of prophylactic antibiotics for neuroendovascular procedures has not been performed. At the authors’ institution there is a unique setup to address this question, with some attending physicians using prophylactic antibiotics (cefazolin or vancomycin) for all of their neurointerventions while others generally do not.

METHODS

The authors performed a retrospective review of the last 549 neurointerventional procedures in 484 patients at Tisch Hospital, NYU Langone Medical Center. Clinical and radiological data were collected for analysis, including presence of prophylactic antibiotic use, local or systemic infection, infection laboratory values, and treatment. Overall, 306 aneurysms, 117 arteriovenous malformations/arteriovenous fistulas, 86 tumors, and 40 vessel stenosis/dissections were treated with coiling (n = 109), Pipeline embolization device (n = 197), embolization (n = 203), or stenting (n = 40).

RESULTS

Antibiotic prophylaxis was used in 265 of 549 cases (48%). There was no significant difference between patients with or without antibiotic prophylaxis in sex (p = 0.48), presence of multiple interventions (p = 0.67), diseases treated (p = 0.11), or intervention device placed (p = 0.55). The mean age of patients in the antibiotic prophylaxis group (53.4 years) was significantly lower than that of the patients without prophylaxis (57.1 years; p = 0.014). Two mild local groin infections (0.36%) and no systemic infections (0%) were identified in this cohort, with one case in each group (1/265 [0.38%] vs 1/284 [0.35%]). Both patients recovered completely with local drainage (n = 1) and oral antibiotic treatment (n = 1).

CONCLUSIONS

The risk of infection associated with endovascular neurointerventions with or without prophylactic antibiotic use was very low in this cohort. The data suggest that the routine use of antibiotic prophylaxis seems unnecessary and that to prevent antibiotic resistance and reduce costs antibiotic prophylaxis should be reserved for selected patients deemed to be at increased infection risk.

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Jennifer L. Quon, Lily H. Kim, Peter H. Hwang, Zara M. Patel, Gerald A. Grant, Samuel H. Cheshier and Michael S. B. Edwards

OBJECTIVE

Transnasal endoscopic transsphenoidal approaches constitute an essential technique for the resection of skull base tumors in adults. However, in the pediatric population, sellar and suprasellar lesions have historically been treated by craniotomy. Transnasal endoscopic approaches are less invasive and thus may be preferable to craniotomy, especially in children. In this case series, the authors present their institutional experience with transnasal endoscopic transsphenoidal approaches for pediatric skull base tumors.

METHODS

The authors retrospectively reviewed pediatric patients (age ≤ 18 years) who had undergone transnasal endoscopic transsphenoidal approaches for either biopsy or resection of sellar or suprasellar lesions between 2007 and 2016. All operations were performed jointly by a team of pediatric neurosurgeons and skull base otolaryngologists, except for 8 cases performed by one neurosurgeon.

RESULTS

The series included 42 patients between 4 and 18 years old (average 12.5 years) who underwent 51 operations. Headache (45%), visual symptoms (69%), and symptoms related to hormonal abnormalities (71%) were the predominant presenting symptoms. Improvement in preoperative symptoms was seen in 92% of cases. Most patients had craniopharyngiomas (n = 16), followed by pituitary adenomas (n = 12), Rathke cleft cysts (n = 4), germinomas (n = 4), chordomas (n = 2), and other lesion subtypes (n = 4). Lesions ranged from 0.3 to 6.2 cm (median 2.5 cm) in their greatest dimension. Gross-total resection was primarily performed (63% of cases), with 5 subsequent recurrences. Nasoseptal flaps were used in 47% of cases, fat grafts in 37%, and lumbar drains in 47%. CSF space was entered intraoperatively in 15 cases, and postoperative CSF was observed only in lesions with suprasellar extension. There were 8 cases of new hormonal deficits and 3 cases of new cranial nerve deficits. Length of hospital stay ranged from 1 to 61 days (median 5 days). Patients were clinically followed up for a median of 46 months (range 1–120 months), accompanied by a median radiological follow-up period of 45 months (range 3.8–120 months). Most patients (76%) were offered adjuvant therapy.

CONCLUSIONS

In this single-institution report of the transnasal endoscopic transsphenoidal approach, the authors demonstrated that this technique is generally safe and effective for different types of pediatric skull base lesions. Favorable effects of surgery were sustained during a follow-up period of 4 years. Further refinement in technology will allow for more widespread use in the pediatric population.