Why Are There Differences in the Perceived Safety of Office-Based Surgery?

BACKGROUND: Office-based surgery has become an important method of health-care delivery, but there is controversy about its safety and which practitioners should perform it. Several states have already or are preparing to enact legislation regulating office-based surgery. OBJECTIVE: The objective was to discuss recent literature pertaining to the safety of office surgery and to discuss reasons why there are perceived differences in its safety. METHODS: The pertinent literature is reviewed. Results. The majority of studies suggest that office surgery is safe. A recent study that found to the contrary may have methodologic flaws. CONCLUSION: The medical and legislative community should seek to scientifically examine office surgery. Overregulation or loss of office surgery would have a tremendous impact on the management of skin cancers and the delivery of quality cosmetic and laser surgery.     

Carotid endarterectomy in the elderly

The records of 146 patients 80 years of age or older who underwent 183 carotid endarterectomy operations from 1964 through 1990 were reviewed to determine surgical risk. The indications for operation were asymptomatic patients with carotid stenosis (n=36); ipsilateral transient ischemic attacks (n=46); ipsilateral stroke (n=28); ipsilateral retinal embolus (n=15); nonlateralizing symptoms (n=40); and asymptomatic side in patients with contralateral symptoms (n=18). Postoperatively, three patients (1.6% of operations) had a stroke with a residual deficit and three (1.6%) died. All deaths were from myocardial infarction. For comparison, during the same time period, the combined stroke with residual deficit and death rate for patients less than 80 operated upon for similar indications was 3.5%. Since 80-year-old patients have a life expectancy of at least five years, the authors conclude that elderly patients should be evaluated for carotid endarterectomy using criteria similar to that used for younger patients.Presented at the Tenth Annual Meeting of the Southern California Vascular Surgical Society, September 27–29, 1991, Marina Del Rey, California.     

Artificial rearing alters development of the nucleus of the solitary tract

Previous studies have shown that damage induced to fungiform papillae of the anterior tongue at postnatal day 2 (P2) alters both pre- and postsynaptic development of gustatory recipient zones within the rostral nucleus of the solitary tract (NST). The present study was conducted to determine whether or not artificial rearing (AR) manipulations, which reduce normal orochemical stimulation during early postnatal development, would be sufficient to produce alterations in anatomical development of the rostral gustatory NST. Two groups of Long-Evans hooded rats were examined. One group received normal rearing with a lactating dam from birth to weaning (mother reared; MR). A second group of animals received artificial rearing via intragastric cannulae between the ages of P4 and P14, and were thereafter returned to lactating dams until the age of weaning (P21). Following weaning and maturation to adulthood (P49), the organization of gustatory afferent terminal fields in the NST was examined using fluorescent tracing procedures which permit the simultaneous visualization of gustatory afferent terminal fields arising from the seventh and ninth cranial nerves. Results show that AR manipulations between the ages of P4 and P14 produce alterations in development of gustatory afferent terminal fields in the NST that are essentially similar to those observed following early postnatal receptor damage. These results confirm previous suggestions that orochemical stimulation during a limited portion of rats' postnatal life is essential in inducing normal presynaptic development in the gustatory NST.     

Vasovagal syncope in patients with reduced left ventricular function

Vasovagal syncope (VVS) is mediated by arterial mechanoreceptors, resulting in reflexive changes in heart rate and vascular tone. The Bezold-Jarisch reflex was originally described as enhanced contraction and activation of left ventricular mechanoreceptors, but later studies implicated other triggers, including coronary, carotid, and cerebral arterial mechanoreceptors. VVS is uncommon in patients with left ventricular dysfunction. We hypothesized that VVS could occur in this subset and examined patient characteristics and hemodynamic responses during tilt table testing. From 1996 through 1998, 128 consecutive patients with ejection fraction <40% underwent tilt table testing (70 degrees , 45 min). A total of 15 patients (11.7%) had a positive neurocardiogenic response thought to be the cause of syncope. Clinical data and hemodynamic responses were reviewed. Mean patient age (+/-SEM) was 70.1 +/- 12.2 years. Nine patients were male. Mean ejection fraction was 27.7% +/- 7.1%. Thirteen had electrophysiologic studies with normal findings or abnormal findings insufficient to account for syncope. Hemodynamic analysis of 14 patients who had a vasovagal response during passive tilt table testing showed a mean time to positive response of 17.6 +/- 12.7 min. Cardioinhibitory responses (pauses >3 sec or heart rate < 40 beats/min for > or =10 sec) were not observed. Five responses were classified as mixed type (>10% decrease in heart rate without a cardioinhibitory response) and 9 as vasodepressor type (< or =10% decrease in heart rate). VVS occurs in patients who have clinically significant left ventricular dysfunction. Although this study had a small cohort size, the predominantly vasodepressor response without a cardioinhibitory component warrants further investigation into mechanisms of VVS in these patients.     

Adipocyte spatial distributions in bone marrow: implications for skeletal dosimetry models.

Few studies have been conducted to quantify the spatial distributions of adipocytes in the marrow cavities of trabecular bone. Nevertheless, such data are needed for the development of 3-dimensional (3D) voxel skeletal models where marrow cellularity is explicitly considered as a model parameter for dose assessment. In this investigation, bone marrow biopsies of the anterior iliac crest were examined to determine the size distribution of adipocyte cell clusters, the percentage of perimeter coverage of trabecular surfaces, and the presence or absence of adipocyte density gradients in the marrow space, all as a function of the biopsy marrow cellularity (5%-95%). METHODS: Biopsy slides from 42 patients were selected as designated by the hematopathologist as either normocellular or with no evidence of disease. Still-frame video image captures were made of 1-3 regions of interest per biopsy specimen, with subsequent image analysis of adipocyte spatial characteristics performed via a user-written MATLAB routine. RESULTS: A predictable shift was found in cluster size with decreasing marrow cellularity from single adipocytes to clusters of >or=3 cells; the percentage of 2-cell clusters remained relatively constant with changing cellularity. Also, a nonlinear increase in trabeculae perimeter coverage was found with increasing fat tissue fraction at marrow cellularities between 50% and 80%. Finally, it was demonstrated that only in the range of 20%-50% marrow cellularity was a slight gradient in adipocyte concentration indicated with adipocytes localized preferentially toward the trabecular surfaces. CONCLUSION: Electron transport simulations were conducted in 4 different 3D voxel models of trabecular bone for sources localized in the active marrow (TAM), bone volume (TBV), bone endosteum (TBE), and bone surfaces (TBS). Voxel model simulations demonstrated that absorbed fractions to active marrow given by the ICRP 30 model (MIRDOSE2) are exceedingly conservative for both TBV and TBS sources, except in the case of high-energy particles (>500 keV) at high values of marrow cellularity (>70%). Values of both phi(TAM<--TBV) and phi(TAM<--TBS) given by the Eckerman and Stabin model (MIRDOSE3) were shown to be reasonably consistent with 3D voxel model simulations at the reference cellularity of 25%, except in the case of low-energy emitters (<100 keV) on the bone surfaces.