Radiation Exposure of Patient and Operating Room Personnel by Fluoroscopy and Navigation during Spinal Surgery.

Intraoperative radiography imaging is essential for accurate spinal implant placement. Hazards caused by ionizing radiation raised concern on personnel's work life long exposure in the operating room (OR). To particularize a cumulative risk estimation of radiation of personnel and patient, depending on used methods (C-arm fluoroscopy, O-arm navigation) and patient characteristics during spinal surgery, detailed investigation of radiation exposure in a clinical setting is required. Lumbosacral dorsal spinal fusion was performed in 37 patients (19 navigated, 18 fluoroscopy) during this prospective study. Radiation exposure was measured on several body regions with thermoluminescent dosimeters on patient and OR personnel (surgeon, assistant, sterile nurse, radiology technologist). Comparison between patient characteristics and radiation exposure was included. The highest patients values were measured in the surgery field and gonads area during navigation (43.2 ± 19.4 mSv; fluoroscopy: 27.7 ± 31.3 mSv; p = 0.02), followed by the thoracic region during fluoroscopy (7.7 ± 14.8 mSv; navigation: 1.1 ± 1.0 mSv; p = 0.06), other measured regions can be considered marginal in comparison. Amongst OR personnel exposure of the surgeon was significant higher during fluoroscopy (right hand: 566 ± 560 µSv and thoracic region: 275 ± 147 µSv; followed by thyroid and forehead) compared to navigation (right finger: 49 ± 19 µSv; similar levels for all regions; p < 0.001 in all regions). When compared to the surgeon, other OR personnel had significantly lower radiation doses on all body regions using fluoroscopy, and similar dose during navigation. The highest eye's lens region value was measured during fluoroscopy for the patient (185 ± 165 µSv; navigation: 205 ± 60 µSv; p = 0.57) and the surgeon (164 ± 74 µSv; navigation: 92 ± 41 µSv; p < 0.001). There was a significant correlation between patient BMI and radiation exposure to the surgery field during fluoroscopy. To our knowledge, these data present the first real life, detailed comparison of radiation exposure on OR personnel and patients between clinical use of navigation and fluoroscopy. Although patient's radiation dose is approximately 3-fold during navigation compared to the fluoroscopy, we found that a spinal surgeon could perform up to 10-fold number of surgeries (10.000 versus 883) until maximum permissible annual effective radiation dose would be reached. Especially for a spinal surgeon, who is mainly exposed amongst OR personnel, radiation prevention and protection must remain a main issue.

Do the carotid body chemoreceptors mediate cardiovascular and sympathetic adjustments induced by sodium overload in rats?

Acute plasma hypernatremia induces several cardiovascular and sympathetic responses. It is conceivable that these responses contribute to rapid sodium excretion and restoration of normal conditions. Afferent pathways mediating these responses are not entirely understood. The present study analyses the effects of acute carotid chemoreceptor inactivation on cardiovascular and sympathetic responses induced by infusion of hypertonic saline (HS). All experiments were performed on anesthetized male Wistar rats instrumented for recording of arterial blood pressure (ABP), renal blood flow (RBF) and renal sympathetic nerve activity (RSNA). Animals were subjected to sham surgery or carotid chemoreceptor inactivation by bilateral ligation of the carotid body artery (CBA). In sham rats (n=8), intravenous infusion of HS (3 M NaCl, 1.8 ml/kg b.wt.) elicited a transient increase (9±2mmHg) in ABP, and long lasting (30 min) increases in RBF (138±5%) and renal vascular conductance (RVC) (128±5%) with concurrent decrease in RSNA (-19±4%). In rats submitted to CBA ligation (n=8), the pressor response to HS was higher (24±2mmHg; p<0.05). However, RBF and RVC responses to HS infusion were significantly reduced (113±5% and 93±4%, respectively) while RSNA was increased (13±2%). When HS (3M NaCl, 200µl) was administrated into internal carotid artery (ICA), distinct sympathetic and cardiovascular responses were observed. In sham-group, HS infusion (3M NaCl, 200µl) into ICA promoted an increase in ABP (26±8mmHg) and RSNA (29±13%). In CBA rats, ABP (-3±5.6mmHg) remained unaltered despite sympathoinhibition (-37.6±5.4%). These results demonstrate that carotid body chemoreceptors play a role in the development of hemodynamic and sympathetic responses to acute HS infusion.

Experience with volumetric (320 rows) pediatric CT.

The introduction of helical computer tomography (CT) and further progress to multi-slice CT enabled new applications. Most recent developments like the 320-row detector facilitate volume CT, which avoids the over-beaming effect of helical scanning. The 320-row multi-slice detector CT (MDCT) is based on a 16cm detector; a special acquisition mode allows reconstructing 640 slices from these 16cm. The shortest tube rotation time is in cardiac mode 0.35s, otherwise 0.4s and 0.5s used. At 0.5s the machine already reaches the maximum numbers of sub-second projections. Scan modes can be volume, helical and single slice mode. For image acquisition all dose savings technologies like variable tube position for scano-view, active collimation, automated exposure control, bolus and ECG tracking are available. Additionally special acquisition and post-processing techniques like head and body perfusion CT are ready for use on the console. For image reconstruction properties like filtered back projection as well as the latest development of iterative algorithms, an appropriate number of kernels and multi-planar reconstruction in all directions from the volume data at every increment are available. Volume CT allows sub second scanning of 16cm z-coverage which, however, makes administration of intravenous contrast medium to "hit or miss" event. The aim of this paper is to present the application of volume CT to body scanning in children. Representative examples of neck, cardiac and skeletal investigations are given.

Gamma knife radiosurgery for uveal melanomas: an 8-year experience.

OBJECT: The authors report their experience using gamma knife radiosurgery (GKS) to treat uveal melanomas. METHODS: Between 1992 and 1998, 60 patients were treated with GKS at a prescription dose between 45 Gy and 80 Gy. The mean diameter of the tumor base was 12.2 mm (range 3-22 mm). The mean height of the tumor prominence was 6.7 mm (range 3-12 mm). The eye was immobilized. The follow-up period ranged from 16 to 94 months. Tumor regression was achieved in 56 (93%) of 60 patients. There were four recurrences followed by enucleation. The severe side effect of neovascular glaucoma developed in 21 (35%) patients in a high-dose group with larger tumors and in proximity to the ciliary body. A reduction in the prescription dose to 40 Gy or less and excluding treatment to tumors near the ciliary body decreased the rate of glaucoma without affecting the rate of tumor control. CONCLUSIONS: Gamma knife radiosurgery at a prescription dose of 45 Gy or more can achieve tumor regression in 85% of the uveal melanomas treated. Neovascular glaucoma can develop in patients when using this dose in tumors near the ciliary body. It is advised that such tumors be avoided and that the prescription dose be reduced to 40 Gy.

Neutrophil response following intratracheal instillation of collagen peptides into rat lungs.

Inflammatory lung diseases are associated with destruction of interstitial collagen and release of degraded collagen fragments into the lower respiratory tract. To determine whether degraded collagen might be one factor mediating the cellular influx, we measured polymorphonuclear leukocytes (PMN) in bronchoalveolar lavage fluid following intratracheal instillation of collagen peptides. The responses to collagenous peptides derived from collagen digested with bacterial collagenase and to the collagenous-like polytripeptide (proline-proline-glycine) were examined. Both types of collagen peptides were chemotactic for human PMN in vitro. Two days following instillation of 5 mg collagenous peptides, we observed a threefold increase in the percentage of PMN in lavage fluid with a maximum (fivefold) response on day 6. Since other chemoattractants produce a response within hours when instilled intratracheally, we postulated that the late neutrophil influx produced with collagen may be the result of production of a neutrophil chemoattractant by alveolar macrophages. Alveolar macrophages treated with collagenous or collagenous-like peptides released PMN chemotactic factors, and the time course of release of chemotactic activity by alveolar macrophages in vitro correlated with the in vivo finding of a 2-6-day delay in PMN accumulation in the lungs. These observations are consistent with the idea that collagen peptides may stimulate alveolar macrophages to produce chemotactic factors for neutrophils. This mechanism may play a role in the accumulation of phagocytic cells in the lung following injury.

[Treatment of forced weeping (author's transl)]. / Zur Therapie des Zwangsweinens

A derivate of gamma-aminobutyric acid was found to have a favourable therapeutic effect in patients with forced weeping (weeping sickness). All 10 treated cases were shown to have motor neuron lesions resulting from other cerebral changer (cerebrovascular accident, brain atrophy, diffuse vascular changes).