Acute ultrastructural changes of cornea after excimer laser ablation.

Corneal ultrastructural changes induced by an argon fluoride excimer laser using different parameters were investigated. Twenty-eight rabbit corneas were ablated at light doses per pulse and repetition rates ranging from 25-800 mJ/cm2 and 1-100 Hz, respectively, at four different total light doses (25-150 J/cm2). Transmission electron microscopy showed that corneal ablations done at subthreshold light doses per pulse with repetition rates higher than 30 Hz and with an exposure more than 100 sec caused significant surface coagulation and an increase in pseudomembrane thickness. These changes were not observed in ablations done above threshold light doses per pulse, regardless of repetition rate and exposure time. However, repetition rates as high as 80 Hz caused damage to the endothelium and Descemet's membrane at the same ablation depth that did not cause such damage using repetition rates under 40 Hz. It appears that high repetition rates used during excimer laser corneal surgery may cause irreversible damage to the cornea.

Name that tone. The proliferation of alarms in the intensive care unit.

The proliferation of alarms on equipment in ICUs contributes to a level of noise that can disturb both patient and staff. To determine whether these alarms are identifiable by sound alone to our ICU staff, we recorded 33 audio signals commonly heard on the ward, 10 of which we defined as critical alarms. One hundred subjects (25 physicians, 41 nurses, and 34 respiratory therapists) listened individually in a quiet room to the tape recording that consisted of 10 s of audible followed by a 10-s pause for a written response. Only 50 percent of the critical alarms and only 40 percent of the noncritical sounds were correctly identified. By occupation, registered respiratory therapists scored highest, followed by nurses, nonregistered therapists, and physicians. Those with > 1 year ICU work experience scored higher than those with less than 1 year. We conclude that the myriad of alarms that regularly occur in the ICU are too much for even experienced ICU staff to quickly discern. Patient and caregiver alike could benefit by a graded system in which only urgent problems have audible alarms, and these should be covered by regular in-service training.

Malignant spinal cord tumors: a review and case presentation.

Since malignant spinal cord tumors constitute such a small percentage of spinal cord lesions, nurses may be unaware of the challenging needs of this group of patients. Often young and previously healthy, these people face a rapidly progressive and dismal disease course. Presentation and complaints are related to the location and growth rate of the tumor. Treatment is geared to debulking the tumor mass and preventing its spread. This article discusses the pathophysiology, signs and symptoms, medical management and nursing implications for the patient diagnosed with a malignant spinal cord tumor. A case presentation including examples of nursing diagnosis and interventions follows.

Evaluation of teaching performance in U.S. dental schools.

This study examines how teaching performance is evaluated in U.S. dental schools. Respondents to the mailed survey were dental school deans. Most schools formally evaluate teaching through student evaluation, yet most deans agreed that evaluation should include input from students and peers. Features that were considered most important in an evaluation program included the provision of a feedback mechanism, the inclusion of faculty input, and a standardization of the evaluation system. The majority of schools provide a program to enhance teaching skills; responsibility for the program varied from the department chairperson to the individual faculty member. More than half of the deans indicated that research productivity can "outweigh" teaching skills in promotion and tenure decisions. The results indicate that dental school deans expect excellence in teaching, but leave doubt as to how faculty members are to gain expertise in this realm of their profession.

Searching for multiple targets simultaneously: is it really possible?

In an attempt to clarify the findings of Neisser and his associates with respect to parallel processing of multiple target items in a visual search task, subjects were tested in a multiple-target search situation in which the various target sets were not nested. 20 sessions were run for each subject with 12 trials per day. The targets used were geometric forms, allowing for manipulation of the number of features in each form. The results do not confirm those of Neisser, in fact, the interaction of session x target-set size was in a direction opposite to that predicted by a parallel preattentive processing may in fact have reflected a tendency for subjects to scan for a master set of targets, regardless of which subset of that set was actually present on a given set.

An adolescent psychiatric unit for difficult medical patients.

While the combined psychiatric and medical treatment of patients is highly desirable, such treatment of more complex medical patients in a psychiatric milieu has been difficult to accomplish. This paper describes the creation of and experience with a psychiatric unit for adolescents with both difficult medical and psychiatric problems. Useful aspects of the structure of such a unit are discussed, and case examples are presented.

The pediatric medical-psychiatric unit in a psychiatric hospital.

Interest in the development of pediatric medical-psychiatric units continues to grow, driven by clinical, financial, and interdisciplinary considerations. While virtually all of the pediatric medical-psychiatric units reported in the literature to date have arisen in the pediatric setting, there are considerations that may encourage the development of such programs in the psychiatric setting. The authors report on the development and characteristics of a pediatric medical-psychiatric specialty inpatient unit developed in a psychiatric hospital. Advantages and disadvantages of the psychiatric hospital setting are considered in light of cumulative experience.

Selectivity, efficiency, and surface characteristics of hard dental tissues ablated with ArF pulsed excimer lasers.

Lasers are finding expanding applications in the field of dentistry. Cutting in soft tissue, hard dental material ablation, caries removal, and root canal therapy are only a few examples of dental laser uses. In this article, the application of short pulse ArF excimer laser to ablation of dentin and enamel is investigated. In particular, the effect of laser pulse repetition rates (PRR) and fluence levels on the efficiency of the ablation process and on the average thermal response of ablated surfaces is investigated. Ablation of dentin was found to be considerably more efficient than the ablation of enamel and depends exponentially on the laser fluence. Both dentin and enamel surfaces showed an increase in surface temperature with repetition rate. At lower PRR, however, temperature increases are very small. Surface temperature was also found to increase with laser fluence, although this increase is very small at laser PRR of 5 Hz or less. Tissue ablation rates were found to be comparable to or better than other nanosecond lasers, and left smooth surfaces, free of thermal damage. Microscopic examination of the ablated surface shows no crack formation, charring, discoloration, or any other thermal damage. The ablated surfaces appear to be very smooth, highly polished, and glossy looking as if they were subjected to thermal melting. This observation is indeed confirmed under scanning electron microscopy (SEM), where evidence of localized melting of the tissue is observed. Furthermore, a close SEM examination of the dentin surface reveals a selectively ablated intertubular dentin, while the remaining pillar-like dentin tubules are sealed off with fused peritubular dentin. At all fluence levels and PRR, the first three to four pulses impinging on an untreated enamel surface produced unusually large plumes of debris which were different in size, texture, and fluorescence emission characteristics from the ablation products of subsequent pulses. It is believed that these different ablation characteristics are a consequence of the pulsed ArF laser's ability to selectively remove residual matter from the more resistant enamel surface.