TECHNICAL NOTE: SOME VIEWS ON THE TREATMENT OF "ARTIFACTS" IN PSYCHOPHYSIOLOGICAL RECORDINGS

The treatment of artifactual responses in psychophysiology is rarely discussed or made explicit in research reports. The rationales and procedures of five approaches are presented: excluding the data; averaging other epochs; subjective estimation; straight-line connecting; and following the pen. Each approach is based on a somewhat different theoretical orientation, and the choice of each will depend on the researcher's theoretical preference and also the relative “costs” of losing data vs programming special instructions. Other considerations such as objectivity, consistency, and replicability are discussed.     

Plasma exchange in chronic inflammatory demyelinating polyneuropathies

Chronic Inflammatory Demyelinating Polyneuropathies (CIDP) are characterized by demyelination of peripheral nerves with mononuclear cell infiltrates, electrical conduction slowing or block and elevated cerebrospinal fluid protein with no cells. An immune mediated pathogenesis has been suggested. Immune suppressive therapy, as well as plasmapheresis and intravenous immunoglobulins have been used with variable success. Our objective was to review our results of plasma exchange in this disease in 20 patients with very different underlying diseases, none of them eligible for the Canadian CIDP plasmapheresis study, and define certain guidelines of predictability for the effectiveness of plasma exchange. Five patients had monoclonal gammopathies of unknown significance, two had lung cancer, one breast cancer, one hairy cell leukemia and later carcinoma of the pancreas; two had hepato-splenomegaly and hemolytic anemia; nine were idiopathic (two with autoimmune markers). Plasmapheresis varied from 4 to 31 plasma volumes and procedures with a median of 12, always with 5% albumin. Two excellent responses, one very good, two moderate transient and 12 had no change in clinical or conduction status. Best response occurred in paraproteinemias. Thus immune modulation with plasma exchange may be useful in CIDPs with paraproteinemias and autoimmune manifestations.     

Pericarditis

Pericarditis is a common but frequently subclinical entity. There are a number of causes, including infection, systemic illness, cardiac disease, trauma, and neoplasm. Iatrogenic causes include surgery, cardiac instrumentation, irradiation, and medications. The clinical presentation varies, depending on the cause. Chest pain and dyspnea are characteristic complaints. A typical progression of ECG changes occurs during the course of acute pericarditis. These changes occasionally require differentiation from those of acute myocardial infarction or normal variant ST segment elevation. Echocardiography is the most sensitive technique for detecting the presence of pericardial effusion. In addition, a number of echocardiographic findings are characteristic of larger effusions and cardiac tamponade. Any form of pericarditis may lead to the development of cardiac tamponade. Malignant effusion is probably the most common single cause.     

EEG Changes during Awake Carotid Endarterectomy

To determine the reason for differing shunt rates based on electroencephalographic (EEG) and neurologic changes during general and regional anesthetic, respectively, we compared simultaneous EEG tracings and neurologic status in 135 patients undergoing carotid endarterectomy (CEA) under cervical block over a 30-month period. The decision to shunt in these patients was made on the basis of neurologic changes only irrespective of EEG findings. This group was then compared to the 288 patients undergoing CEA under general anesthetic with EEG monitoring over the same period. EEG changes occurred in 7.4% of awake patients and 15.3% of asleep patients (p <0.03). The rates of ipsilateral hemispheric changes were similar, but no awake patient manifested global EEG changes with clamping while 3.5% of patients under general anesthesia did (p <0.04). Global, but not hemispheric, changes were correlated with systolic blood pressure variability during clamping. This implies that global EEG changes in anesthetized patients may be the result of the anesthetic technique itself, and that cervical block may in fact be cerebroprotective.     

Relationship of proximal fixation to postoperative renal dysfunction in patients with normal serum creatinine concentration

OBJECTIVES: This study was performed to determine whether there is deterioration in renal function during follow-up in patients who have undergone endovascular aneurysm repair (EVAR), as recommended by the device manufacturers; to determine whether suprarenal fixation correlates with impairment of renal function; and to explore the potential implication of life-long surveillance of renal function with contrast-enhanced computed tomography. METHODS: One hundred forty-six consecutive patients underwent EVAR at our institution. Data from 113 of these patients who were free from preoperative renal insufficiency or postoperative renal disease were analyzed. Fifty-three patients received infrarenal (IR) fixation devices, and 60 patients received suprarenal (SR) fixation devices. All SR fixation devices were placed under investigational device exemption protocols. The average follow-up was 688 days. Sixty-five consecutive patients who had undergone open repair of an abdominal aortic aneurysm (AAA) served as the control group. RESULTS: Preoperative creatinine concentration, intraoperative blood loss, contrast volume, and number of contrast-enhanced procedures were not significantly different between the IR and SR groups. Two renal artery occlusions (1 SR, 1 IR; P=NS) were identified, and 8 renal infarcts (5 SR, 3 IR; P=NS). There was an increase in mean creatinine concentration in the open AAA, IR, and SR fixation groups at each time point in the analysis. Mean elevation in creatinine concentration at 12, 24, and 36 months was 0.10, 0.10, and 0.04 mg/dL, respectively, for open AAA repair; 0.20, 0.21, and 0.28 mg/dL for IR fixation; and 0.15, 0.21, and 0.12 mg/dL for SR fixation. At life table analysis, renal impairment at 36 months was seen in 36% +/- 9% of patients in the IR group, 25% +/- % of patients in the SR group, and 19% +/- 6% of patients in the open AAA group (P=.04 for IR fixation vs open AAA repair). CONCLUSIONS: A decrease in kidney function is seen after EVAR, regardless of fixation level, that is independent of renal disease and renal arterial occlusion. In patients with normal renal function the site of proximal fixation does not affect postoperative creatinine concentration. The decrease in renal function is likely related to the repetitive administration of contrast agent.