HICNet Medical News Digest Tue, 23 Aug 1994 Volume 07 : Issue 39 Today's Topics: [MMWR] Limited Supplies Inactivated Poliovirus Vaccine AZT Approved For Preventing Maternal-Fetal HIV Transmission Electromagnetic Interference with Medical Devices Suspension of Felbatol Use Urged FDA Approves New Device to Unblock Heart Arteries SimBioSys 1.0 - Software Review +------------------------------------------------+ ! ! ! Health Info-Com Network ! ! Medical Newsletter ! +------------------------------------------------+ Editor: David Dodell, D.M.D. 10250 North 92nd Street, Suite 210, Scottsdale, Arizona 85258-4599 USA Telephone +1 (602) 860-1121 FAX +1 (602) 451-1165 Internet: mednews@stat.com Bitnet: ATW1H@ASUACAD Mosaic WWW: http://biomed.nus.sg/MEDNEWS/welcome.html Compilation Copyright 1994 by David Dodell, D.M.D. All rights Reserved. License is hereby granted to republish on electronic media for which no fees are charged, so long as the text of this copyright notice and license are attached intact to any and all republished portion or portions. The Health Info-Com Network Newsletter is distributed biweekly. Articles on a medical nature are welcomed. If you have an article, please contact the editor for information on how to submit it. If you are interested in joining the automated distribution system, please contact the editor. Associate Editors: E. Loren Buhle, Jr. Ph.D. Dept. of Radiation Oncology, Univ of Pennsylvania Tom Whalen, M.D., Robert Wood Johnson Medical School at Camden Douglas B. Hanson, Ph.D., Forsyth Dental Center, Boston, MA Lawrence Lee Miller, B.S. Biological Sciences, UCI Dr K C Lun, National University Hospital, Singapore W. Scott Erdley, MS, RN, SUNY@UB School of Nursing Jack E. Cross, B.S Health Care Admin, 882 Medical Trng Grp, USAF Albert Shar, Ph.D. CIO, Associate Prof, Univ of Penn School of Medicine Martin I. Herman, M.D., LeBonheur Children's Medical Center, Memphis TN Stephen Cristol, M.D., Dept of Ophthalmology, Emory Univ, Atlanta, GA Subscription Requests = mednews@stat.com anonymous ftp = vm1.nodak.edu; directory HICNEWS FAX Delivery = Contact Editor for information ---------------------------------------------------------------------- Date: Tue, 23 Aug 94 21:39:24 MST From: mednews (HICNet Medical News) To: hicnews Subject: [MMWR] Limited Supplies Inactivated Poliovirus Vaccine Message-ID: Limited Supplies of Inactivated Poliovirus Vaccine -- United States There is a shortage of inactivated poliovirus vaccine (IPV) in the United States. The Food and Drug Administration (FDA), the manufacturers (Pasteur Merieux Serums & Vaccines, S.A. [Lyon, France] [IPOLTM]*, and Connaught Laboratories, Limited [Willowdale, Ontario, Canada] [POLIOVAXTM]), and the distributor, Connaught Laboratories, Inc. (Swiftwater, Pennsylvania), are working to resolve the shortage. Until IPV becomes readily available, CDC recommends that its use be restricted to 1) never-vaccinated persons aged greater than 18 years who are at risk for exposure to wild poliovirus (e.g., who will be traveling to areas in which poliomyelitis is endemic), and 2) persons for whom oral polio vaccine (OPV) is contraindicated (i.e., persons diagnosed with or living in a household with a person with a congenital or acquired immune deficiency). Inadequately or fully vaccinated adults who have previously received IPV or OPV and need poliovirus vaccine can be given OPV (1,2). OPV continues to be recommended routinely for all children, except as noted above. If supplies are not available locally, poliovirus vaccination of persons for whom OPV is contraindicated should be delayed until IPV becomes available. Because no case of polio resulting from indigenously transmitted wild poliovirus has been reported in the United States since 1979, postponing vaccination for these persons until IPV is available is not likely to pose a risk to those persons. Unvaccinated adults who may be exposed to wild poliovirus during travel to polio-endemic areas and cannot obtain IPV should consider vaccination with OPV but should be informed that the risk for vaccine-associated paralytic polio is slightly higher in adults than in children (1,2). Otherwise, these persons should avoid activities or travel that might result in exposure to wild poliovirus. Information about obtaining IPV for high-risk persons is available from the distributor, Connaught Laboratories, Inc., telephone (800) 822-2463. MMWR will provide updated information when the shortage is alleviated. Reported by: Center for Biologics Evaluation and Research, Food and Drug Administration. National Immunization Program, CDC. References 1. ACIP. Poliomyelitis prevention. MMWR 1982;31:22-6,31-4. 2. ACIP. Poliomyelitis prevention: enhanced-potency inactivated poliomyelitis vaccine--supplementary statement. MMWR 1987;36:795-8. *Use of trade names and commercial sources is for identification only and does not imply endorsement by the Public Health Service or the U.S. Department of Health and Human Services. ------------------------------ Date: Tue, 23 Aug 94 21:40:33 MST From: mednews (HICNet Medical News) To: hicnews Subject: AZT Approved For Preventing Maternal-Fetal HIV Transmission Message-ID: AZT APPROVED FOR PREVENTING MATERNAL-FETAL HIV TRANSMISSION The Food and Drug Administration today approved the anti-AIDS drug AZT (zidovudine) for use in preventing transmission of HIV, the virus that causes AIDS, from HIV-infected pregnant women to their babies. Data supporting the new indication comes from a federally sponsored study designed to determine whether AZT reduces the risk of passing the HIV virus from infected mothers to their infants either before or during birth. In this randomized, placebo-controlled trial, HIV-infected women received 500 mg of AZT per day orally during pregnancy and a continuous intravenous infusion of AZT during labor. Therapy was begun between 14 and 34 weeks after conception. Newborns received oral AZT within 24 hours after birth and for six weeks thereafter. The study did not treat women during the first trimester of pregnancy. Also, women with prior use of AZT or CD4 counts below 200 were not eligible for the study. The study was halted when a planned interim review of the data showed that for women treated with AZT the estimated rate of transmitting the virus to their babies was reduced by approximately two-thirds, from 25.5 percent infected babies from women on placebo to 8.3 percent infected babies from women on the AZT regimen. A long-term followup study of babies exposed to AZT is under way. The drug was well tolerated by both mothers and infants. Side effects reported during the study included reversible mild anemia in some infants. On July 28, FDA's Antiviral Drugs Advisory Committee reviewed the application to amend the AZT label and unanimously recommended that the agency approve this amendment. With today's approval, AZT is now indicated for the prevention of maternal-fetal HIV transmission as part of a regimen that includes oral AZT beginning between 14 and 34 weeks of gestation, intravenous AZT during labor, and administration of AZT syrup to the newborn after birth. AZT is manufactured by Burroughs Wellcome Co. of Research Triangle Park, N.C. and is marketed under the trade name Retrovir. ------------------------------ Date: Tue, 23 Aug 94 21:41:29 MST From: mednews (HICNet Medical News) To: hicnews Subject: Electromagnetic Interference with Medical Devices Message-ID: ELECTROMAGNETIC INTERFERENCE WITH MEDICAL DEVICES FDA has been receiving inquiries about reports of possible electromagnetic interference with some electronic medical devices. The following can be used to answer questions. The agency has received a number of reports in recent years of possible EMI-related problems with medical devices--some resulting in serious injury and death. Electronic medical devices can be susceptible to interference if they are not designed to be protected against it. Common sources of EMI include cellular phones, police, fire or ambulance mobile communications equipment, radio and TV transmitters, amateur radio transmitters and CB radio transmitters. There have been reports, for example, that patient breathing monitors failed to alarm when needed because of radio wave interference; that cellular phones, when used too close to an electronic medical device, have interfered with the device's operation; and that radio wave interference causes some power-driven wheelchairs to move unexpectedly. Because of these reports, FDA has increased its vigilance of possible EMI-related problems and has been working with manufacturers and voluntary standards organizations to improve the electromagnetic compatibility (EMC) of devices. In response to reports about wheelchairs, FDA conducted a preliminary review to see if they could be affected by EMI. The agency determined that radio waves can cause unexpected movement in some power-driven wheelchairs and scooters, but the extent and severity of the problem is not yet known. FDA tested wheelchairs in its laboratories; initiated an inspection of wheelchair manufacturers; and asked manufacturers and consumer groups that represent wheelchair users to provide any information they have on the problem. In May, FDA asked manufacturers to assure that all new wheelchairs have at least a reasonable immunity to EMI, that the chairs be labeled with immunity level and that purchasers be warned about the possibility of EMI and instructed on how best to avoid it. Because of reports several years ago of unexplained failure of apnea monitors to alarm when a patient stopped breathing, FDA engineers investigated the susceptibility of these devices to EMI. FDA laboratory tests showed that most commercial monitors could malfunction when exposed to relatively low radio frequency strengths, which could result in failure to alarm. One product in particular was found to be unusually sensitive to such interference. FDA required the manufacturer to recall the monitor and correct the problem. The agency has since established an electromagnetic compatibility (EMC) standard for all breathing monitors. The agency has also investigated problems with an anesthetic gas monitor, a device used to monitor the amount of anesthesia given to a patient. FDA had received several reports that the machine sometimes displayed erroneous gas concentration readings during surgery, but none mentioned EMI as a possible cause. However, further investigation revealed that the problem was caused by EMI from the electronic knives used during surgery. The manufacturer corrected the problem by changing the gas monitor's software. In addition to investigating specific reports of possible EMI problems and testing devices in its laboratories, FDA is initiating steps to require medical device manufacturers to design and test their products to ensure they are electromagnetically compatible. In addition to requiring an EMI immunity level for wheelchairs, FDA currently requires that all new respiratory devices and implanted pacemakers meet a rigorous FDA guideline for EMI before they can be approved for marketing. The agency plans to develop similar guidelines for other medical devices as needed. FDA is also working with the International Electrotechnical Commission to develop international EMC standards for medical devices. ------------------------------ Date: Tue, 23 Aug 94 21:43:37 MST From: mednews (HICNet Medical News) To: hicnews Subject: Suspension of Felbatol Use Urged Message-ID: Suspension of Felbatol Use Urged The Food and Drug Administration today recommended the immediate withdrawal of patients from the antiepilepsy drug Felbatol because it has been linked to 10 cases of aplastic anemia. In a "Dear Doctor" letter to 240,000 physicians, Carter-Wallace, Inc., the drug's manufacturer, in conjunction with the FDA recommended suspension of Felbatol therapy, "unless in the physician's judgement, an abrupt withdrawal would be deemed to pose a more serious risk to the patient." Aplastic anemia is a rare and frequently fatal form of bone marrow failure. The rate of aplastic anemia cases reported with Felbatol appears to be about 50 times higher than expected. However, since the syndrome is still relatively rare, no cases were observed in premarket testing in which approximately 1000 patients were exposed to Felbatol. All reports of aplastic anemia associated with Felbatol have been in patients on the drug for at least 2 1/2 months. "We strongly recommend that patients consult their physician as soon as possible, but it is critical that they not discontinue the drug on their own due to the risk of seizures," said FDA Commissioner David A. Kessler, M.D. "Physicians should prescribe this drug only if it is absolutely necessary." In those rare cases where Felbatol is continued, FDA suggests careful monitoring. However, there is no evidence that even close monitoring can protect against the occurrence of aplastic anemia. Felbatol was approved in August 1993 for partial seizures with and without secondary generalization in adults and for Lennox- Gastaut Syndrome, a serious form of childhood epilepsy. ------------------------------ Date: Tue, 23 Aug 94 21:44:16 MST From: mednews (HICNet Medical News) To: hicnews Subject: FDA Approves New Device to Unblock Heart Arteries Message-ID: FDA APPROVES NEW DEVICE TO UNBLOCK HEART ARTERIES FDA today announced the approval of a medical device to unblock and keep open obstructed heart arteries. It has been shown to be superior in some respects to balloon angioplasty. When used in clinical trials, the device, the Johnson & Johnson Palmaz-Schatz Balloon-Expandable Stent, outperformed balloon angioplasty by achieving greater enlargement of arteries and reducing the rate of repeat blockage by 25-35 percent over the next six months. However, patients were more likely to experience bleeding and clotting complications and required longer hospital stays. "This device is an important treatment for certain patients with heart disease," said FDA Commissioner David A. Kessler, M.D. "For these patients, it will work better than balloon angioplasty." In balloon angioplasty, a catheter incorporating a strong plastic balloon is inserted into an artery in the arm or leg and threaded to the blockage in the coronary artery. It is then inflated, compressing the plaque into the artery wall and opening the artery. The balloon catheter is then removed. The stent is a stainless steel device that is permanently placed into the coronary artery by a catheter, similar to a balloon angioplasty catheter. Shaped like a small slotted tube, the stent acts as a "scaffolding device" that serves to enlarge and keep open the artery at the point of obstruction. The procedure significantly improves the flow of blood to the heart muscle. The stent is designed for use in patients with atherosclerosis who have a short blockage in a large artery. Atherosclerosis is a progressive heart disease in which the heart arteries become blocked with fatty plaque, causing chest pain and heart attacks. FDA's decision to approve the product was based on a review of safety and effectiveness data from clinical studies of some 2,000 men and women patients at 48 medical centers in North America and Europe, and on the recommendation of the Circulatory System Devices Panel of the agency's Medical Devices Advisory Committee. FDA is one of eight Public Health Service agencies in HHS. ------------------------------ Date: Tue, 23 Aug 94 21:45:07 MST From: mednews (HICNet Medical News) To: hicnews Subject: SimBioSys 1.0 - Software Review Message-ID: -- SOFTWARE REVIEW -- ** SimBioSys 1.0 ** By: Critical Concepts, Inc. 1994 5240 S. Harper Ave. Chicago IL 60615. Voice: 312-324.3600 FAX: 312-324.8090 REVIEW: Miquel Belmonte, MD, PhD. Univ. Jaume I & Hospital General. Castello, Spain. August 1994. Internet: belmonte@vents.uji.es (Miquel Belmonte) INTRODUCTION SimBioSys is an educational program for cardiopulmonary and renal physiology, real-time simulation. It shows real time waveforms and digital displays of many physiological parameters. These change according to interventions performed on organic systems, including pathologic states (hypovolemia due to blood loses) or/and therapeutic actions: drug infusion, ventilator setup changes, etc. The package comes in a single HD floppy disk. It runs on a IBM-PC or full-compatible machine, under Windows 3.1 environment. Because of the graphic waveforms displayed during the simulation of physiological processes, a 486 DX 33 MHz or better CPU are recommended. A hardware math coprocessor is an absolute requirement, so SX systems will not work with SimBioSys. A VGA monitor, mouse and 2 Mb of free disk space are also necesary to run the program. EQUIPMENT To test this program we used a 486 DX 33 MHz computer with 4 Mb RAM. Installation was fast (about 2 minutes), easy and succesful. In the final step of the automatic, standard process there was a message saying the BWCCESN.DLL could not be found, though there was a BWCC.DLL file in the SBS directory. This message appears every time the program is started since then, but in spite of this the program runs fine. There is an uninstall facility provided with the program to remove it from the hard disk and Windows. MANUAL The Manual of SimBioSys is a softback manual (94 clear-written pages) binded with spiral wire. It is divided in seven parts: Introduction, Installation, Introductory Tutorial, Lab Demo, Sudent Lab Exercises, Tech Reference and Index. The lecture is easy and clear. Plenty of pictures of captured screens makes it easy to understand the concepts, some of them quite complex, explained in the manual. Most useful is the on-line help system available with the key F1. This aid is based on the Help facility of Windows to show context-sensitive explanations. I used it frequently to know the meaning of some acronyms or to rememeber the basic concepts underlaying some of the more complex physiological relationships. DESKTOP The way SimBioSys works is the usual in most Windows programs, including pop-up menus, mobile and resizable windows, and buttons in a menu bar. I found the program quite user-friendly as most elements behave in the expected, intuitive way which is now usual for Windows users. The basic elements of SimBioSys are special standard windows called 'Viewers'. There are two types of viewers: 'digital' which show in numeric form those parameters which change slowly (e.g.: arterial pO2), and 'waveforms' to show parameters which change rapidly over time (e.g.: intracardiac pressures). Also, there are 'static curve' viewers to show static relationships between pairs of parameters (e.g.: ventricular volume-pressure relationship). Finally, 'specialty' viewers show mechanical ventilator and drug/fluid infuser parameters, which are user-defined. Physiologic parameters can be easily changed by clicking on them and using the toolbar buttons to modify their properties. This way, it is simple to see how a change in a single parameter has effects on multiple other vascular, cardiac, respiratory and even renal (mainly urine output) parameters. An interesting feature of SimBioSys is its capability to simulate the effects of Autonomic Control mechanisms on most of the parameters displayed. E.g. Heart pulse increases in response to hypovolemia. This Autonomic Control is ON by default, though it can be turned OFF for most of the parameters just selecting them in a pop-up menu. This allows to see how some systems work by disconneting them from the rest of the body. Some more features are well worth to be commented. The program has menu options for saving and retrieving a case from disk. This speeds the process of showing to the alumni some special situations without the need of rebuilding a whole case. Also, desktops can be configured, saved and retrieved in a similar way, thus allowing to keep preconfigured settings for specific needs (cardiac, vascular, pulmonary and renal special desktops). TUTORIAL The Introductory Tutorial and the Lab Demo are very useful starting points to learn how to use the program and what are its capabilities. There are guided lessons on systemic and pulmonary hemodynamics, and also to demonstrate the effects of heart rate and LV contractility on cardiac function. I found very interesting two ready-made lessons about the cardiovascular response for so common clinical problems as hemorrhage and pericardial tamponade. To help further the clinical tutor, the manual includes several questions of interest in each lesson. They are in the way: Why [this] happened? What is the best action or clinical intervention to improve the cardiovascular status of this patient? and so on. Finally, three Student Laboratory Exercises illustrate the physiology of particular systems: Systemic and Pulmonary Hemodynamics (systemic and pulmonary vascular resistance, determinants of pulse pressure), Cardiac Function (study of diastolic and systolic pressure-volume relationship, effects of cardiac pre- and afterload), and Cardiac Output and Venous Return (including the effect of cardiac tamponade). CONS: I have found a few minor points in the program, easy to correct: 1. The dosage of Dobutamine, Norepinephrine and Nitroprusside are indicated as grams/kg/min in the help section, while it must be expressed in micrograms/kg/min. 2. It was not possible to disconnect Heart Rate from Autonomic (Simulation) Control and change manualy this parameter. This is interesting to simulate the effect of cardiac arrythmias. 3. RA pressure indicator (text) is always zero. does not change with blood loses, pericardial tamponade, etc. 4. The Sound option uses the Windows system sounds to hear the beep of the heart. This can be awful depending on the settings established in the Control Panel of Windows. Would be more desirable to implement a beep sound directly in the program. HINTS for new versions: 1. EKG could be coupled to physiologic parameters to see mutual relationships. 2. Arrythmia and cardiopulmonary diseases. To see the effects of arrythmias over cardiovascular parameters. 3. Possibility to record numeric values of selected parameters at predefined points of time, or even to keep screens to show in one step pathological states. COST SimBioSys sells for US $395 for a single package. Volume discounts and site licenses are available. CONCLUSION I've found SimBioSys an extremely useful help for the tutor of seminars explaining cardiovascular, pulmonary and renal physiology. This is a very difficult area to understand because of the complex interrelationships among the different parameters and systems involved. The best way to understand them is of course seeing what is happening in real time. This program allows to freeze the image or to change the time span displayed in the X axis, so it is very flexible to follow events that happen very slowly so much as those that change rapidly. SimBioSys is also quite good as an self-usable aid for a student, but trying to learn how the program works and what the changes in the parameters clinically mean can be quite boring. I think it's better to work with this program in teams of at least two students to stimulate discussion of what's happening on the screen. In this sense, it's a very good aid for a tutor in a seminar class, especially if a large monitor or room projector is available to display the screen in large format. I did enjoy studying the program, and strongly recommend it for medical schools and postgrade courses. The price is well worth for such purposes, though probably not for single users. __________________________________________________________________ UNIVERSITY | HOSPITAL Miquel A. Belmonte, MD, PhD | Dr. Miquel A. Belmonte Associate Professor | Unidad de Reumatologia Dept. Informatica | Hospital General Universitat Jaume I (Penyeta | Av. Benicassim s/n E-12071 Castello, Spain | 12004 - Castello, Spain Voice +34 (9) 64 344713. | Voice +34 (9) 64 233103. FAX +34 (9) 64 325848 | FAX +34 (9) 64 252345. Always better through email!! belmonte@vents.uji.es __________________________________________________________________ ------------------------------ End of HICNet Medical News Digest V07 Issue #39 *********************************************** --- Editor, HICNet Medical Newsletter Internet: david@stat.com FAX: +1 (602) 451-1165 Bitnet : ATW1H@ASUACAD