Surgeon-patient barrier efficiency monitored with an electronic device in three surgical settings.

Blood-borne viral pathogens are an occupational threat to health care workers (HCWs), particularly those in the operating room. A major risk is posed by accidental penetrating injury, but skin contamination with body fluids from an infected patient, with prolonged intimate cutaneous contact, is a frequent occurrence during surgery, carrying further risk of transdermal infection. We have monitored barrier failure in three surgical settings (microsurgery, orthopedic surgery, general surgery) by means of an electronic surveillance device. A total of 111 surgical procedures were monitored: 67 microsurgeries, 22 orthopedic surgeries, and 22 general surgeries. Of the 278 electronic alarms signaling barrier failure, 44 (15.8%) were associated with glove perforation, 39 of which (88.6%) were not perceived by the operator. In 16 of those, the skin was visibly stained with the patient's blood. Altogether, 76 of the alarms (27.3%) were consequent to contacts caused by soaked gowns/sleeves, and 121 (43.5%) were attributed to hydration of latex porosities; 37 alarms (13.4%) were unexplained false positives. On only one occasion did a surgeon observe blood stains on his hands without a previous alarm; this event was classified as a device failure due to incorrect wiring. Double-gloving offered satisfactory protection against skin contamination during microsurgery but not during orthopedic surgery. The data presented here indicate that electronic monitoring of the surgical barrier enables prompt detection of barrier failure, especially at the level of the gloves, thereby limiting skin contamination with patients' body fluids during surgery.

Clinical and sensorimotor gating effects of ketamine in normals.

The clinical similarities between PCP psychosis and schizophrenia have contributed importantly to the development of the glutamate hypothesis of schizophrenia. Sensory gating, as measured by prepulse inhibition of the acoustic startle reflex (PPI), is impaired in patients with schizophrenia. In animals, the noncompetitive NMDA antagonists PCP and ketamine disrupt PPI in a way that resembles the defect seen in schizophrenia. The purpose of this work is to investigate the modulation of sensory gating in humans by subanaesthetic doses of ketamine. 16 healthy male subjects received a 60-min infusion of ketamine (0.5 mg/kg) or normal saline on two separate days in a randomized double-blind crossover design. Clinical ratings and PPI were done during the infusion on both days. Ketamine produced robust clinical effects. Dissociative symptoms as measured by the CADSS increased from 0 +/- 0.0 to 29.3 +/- 14.3; negative symptoms (Affect Rating Scale) increased from 17.2 +/- 0.8 to 24.8 +/- 3.1; and total BPRS scores increased from 18.3 +/- 0.8 to 26.4 +/- 5.1. ANOVAs for these ratings were all significant at the p <.000 level, although BPRS increases were not in the range seen in decompensated schizophrenic patients. The amplitudes of the startle responses to pulse-alone stimuli were not significantly different on ketamine and placebo days. Ketamine did not cause disruption in PPI as expected. On the contrary, in the first block of the PPI session ketamine significantly enhanced PPI (ANOVA; F=6.15, p =.026). These results indicate that the clinical effects of ketamine are not coupled with schizophrenic-like disruption of PPI in normal controls.

Virtual reality based surgical assistance and training system for long duration space missions.

Access to medical care during long duration space missions is extremely important. Numerous unanticipated medical problems will need to be addressed promptly and efficiently. Although telemedicine provides a convenient tool for remote diagnosis and treatment, it is impractical due to the long delay between data transmission and reception to Earth. While a well-trained surgeon-internist-astronaut would be an essential addition to the crew, the vast number of potential medical problems necessitate instant access to computerized, skill-enhancing and diagnostic tools. A functional prototype of a virtual reality based surgical training and assistance tool was created at our center, using low-power, small, lightweight components that would be easy to transport on a space mission. The system consists of a tracked, head-mounted display, a computer system, and a number of tracked surgical instruments. The software provides a real-time surgical simulation system with integrated monitoring and information retrieval and a voice input/output subsystem. Initial medical content for the system has been created, comprising craniofacial, hand, inner ear, and general anatomy, as well as information on a number of surgical procedures and techniques. One surgical specialty in particular, microsurgery, was provided as a full simulation due to its long training requirements, significant impact on result due to experience, and likelihood for need. However, the system is easily adapted to realistically simulate a large number of other surgical procedures. By providing a general system for surgical simulation and assistance, the astronaut-surgeon can maintain their skills, acquire new specialty skills, and use tools for computer-based surgical planning and assistance to minimize overall crew and mission risk.

Akathisia and exacerbation of psychopathology: a preliminary report.

Akathisia has previously been reported to exacerbate psychopathology and to be associated with noncompliance, suicidality, and violence. One previous study found brisk decrements in psychopathology after acute treatment of akathisia with intramuscular biperiden. This study assessed changes in akathisia and psychopathology in 19 patients after separate one-day treatments with intramuscular benztropine and oral propranolol. Benztropine and propranolol led to clinically meaningful and statistically significant decrements in ratings of subjective and objective measures of akathisia and in psychopathology scores. Changes in psychopathology correlated significantly with changes in subjective measures of akathisia after benztropine and with subjective and objective measures of akathisia after propranolol. Changes in akathisia accounted for 9%-42% of the variance in changes in psychopathology. After treatment, statistically significant decrements in Brief Psychiatric Rating Scale (BPRS) positive symptoms were noted, and individual items not directly related to the akathisia syndrome, such as conceptual disorganization, hallucinatory behavior, and unusual thought content declined, although not significantly. These findings, taken together with the results of a similar previous study, indicate that the effect of akathisia in exacerbating psychopathology is large. If suspected, akathisia should be treated promptly.

Development and application of a virtual environment for reconstructive surgery.

OBJECTIVE: This paper details the development and application of a Virtual Environment for Reconstructive Surgery (VERS). It addresses the technical and user-interface challenges in developing such a system, and the lessons learned during application of the system in the case of a 17-year-old boy with a severe facial defect arising from the removal of a soft-tissue sarcoma. MATERIALS AND METHODS: Computed tomography (CT) scans were segmented into bone and soft-tissue classifications using traditional and novel algorithms, a surface mesh was generated, and imaging artifacts were removed, yielding a mesh suitable for visualization. This patient-specific mesh was then used in a virtual environment by the surgeons for preoperative visualization of the defect, planning of the surgery, and production of a custom surgical template to aid in repairing the defect. RESULTS: This system was successfully used to plan the surgery of the patient and to produce a custom, patient-specific template that was used to harvest bone from a donor site in order to reconstruct the defect. CONCLUSION: Despite technical challenges, virtual-environment surgical planning is useful as a clinical tool for preoperative visualization, cephalometric analysis, and surgical intervention. It can provide a more precise surgical result than would otherwise be realized using traditional methods.

Treatment of periorbital edema with human corticotropin-releasing factor after blepharoplasty.

BACKGROUND: This prospective study of 32 patients was undertaken to ev evaluate the formation of postoperative periorbital edema after administration of human corticotropin-releasing factor (hCRF). Human corticotropin-releasing factor has strong antiedematous properties as a result of direct action on blood vessels independent of endocrine function and has been shown to have a positive effect on vascular permeability in animal studies independent of corticosteroid effects. STUDY DESIGN: Human corticotropin-releasing factor was administered intravenously preoperatively to patients undergoing blepharoplasty in doses of 2, 4, and 8 mu g/kg body weight as a randomized, double-blind, placebo-controlled study. The periorbital edema was measured by the use of a three-dimensional laser scanner to determine facial and eyelid volume changes as specified times postoperatively. RESULTS: Human corticotropin-releasing factor was well tolerated when administered intravenously over a ten-minute period to healthy patients undergoing blepharoplasty. Mild transitory flushing and hypotension were the most common adverse events. Transient decreases in systolic and diastolic blood pressure and increases in heart rate occurred at hCRF doses greater than 2 mu g/kg and were most prominent at 8 mu g/kg. The 8 mu g/kg hCRF dose also showed a trend toward less postoperative edema but this was not statistically significant at the p<0.05 level. CONCLUSIONS: Human corticotropin-releasing factor appears to be safe for intravenous use in patients undergoing blepharoplasty; however, its efficacy in reducing postoperative edema as a single preoperative administration was not conclusively demonstrated in this study. Further research with a larger study population and other dosing regimens is indicated.

The artificial nerve graft: a comparison of blended elastomer-hydrogel with polyglycolic acid conduits.

A study was undertaken to compare the regeneration of rat peroneal nerves across a 0.5-cm gap repaired with either a permanent, porous or a resorbable, non-porous artificial nerve graft. The resorbable, impermeable artificial nerve graft was a synthetic passive conduit made from polyglycolic acid (PGA). The permanent, porous artificial nerve graft conduit was manufactured from a hydrophilic elastomeric biopolymer (HEB), and four variations were tested. Qualitative histology on short-term animals revealed similar inflammatory reactions to HEB and PGA. Axonal regeneration was evaluated in longer-term animals after three, four, and six months by qualitative and quantitative histology. Qualitative histology on longer-term animals demonstrated both artificial nerve grafts to be anti-immunogenic. All PGA-artificial nerve graft repairs among three-, four-, and six-month rats contained myelinated axons, as did all HEB-1 repairs. However, three other HEB-graft varieties accounted for a 25 percent failed regeneration rate. Quantitative histologic comparison of repair-site cross-sections in viable PGA and HEB matched pairs demonstrated statistically equivalent myelinated axon counts but larger average myelinated fiber diameters in HEB repairs, with p = .001.

Sutureless nerve repair at the fascicular level using a nerve coupler.

Peripheral nerves are transected in many traumatic injuries of the extremities. Satisfactory functional regeneration of such nerves often fails to occur after repair with sutures. Possible reasons for these failures include poor alignment of nerves or fascicles, intrusion of scar tissue into the nerve junction, and outgrowth of nerve tissue from the repair site. This animal study describes an experimental method of sutureless, monofascicular peripheral nerve repair using a resorbable nerve coupler in the rat model. The first version of this coupler shows approximately equal performance to suture repair. Histology and electrophysiology assessments after regeneration showed that the polyglycolic acid (PGA) tube repairs were functionally equal to monofascicular suture junctions as well as being quicker and simpler to perform. Modified coupler designs based on this and other work show greater promise. Collateral studies are using similar versions of the nerve coupler as a vehicle for the insertion of chemical and neuro-electronic factors that may enhance nerve regeneration.