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

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       Tom Whalen, M.D., Robert Wood Johnson Medical School at Camden

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             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

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  Albert Shar, Ph.D. CIO, Associate Prof, Univ of Penn School of Medicine

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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: <DgPJRc4w165w@stat.com>

   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: <aiPJRc5w165w@stat.com>

   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: <uJPJRc6w165w@stat.com>

        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: <eNPJRc7w165w@stat.com>

                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: <HoPJRc8w165w@stat.com>

        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: <wPPJRc9w165w@stat.com>

                        -- 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
__________________________________________________________________



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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

