Pre-Hospital Thombolytics (clot busting drugs for heart attacks in the 
ambulance or home)  protocols, bennifits, risks, studies supporting doing this

A comment below from Edward-ga is a fairly thorough annotated site listing 
discussing the studies supporting (and some not supporting) the use of pre-
hospital thrombolytics, with links to articles on various studies (he’s also 
included some about thrombolytic use in ischemic stroke). I have includes links 
to some additional articles on those subjects as well.

Essentially, use of thrombolytics to treat acute myocardial infarction is 
increasing, and because of the time-sensitive importance of treatment after a 
cardiac ischemic event, along with the approval of non-continuous drip IV 
thrombolytic drugs, there is a push for EMS protocols to include the 
administration of these drugs in a prehospital (ALS) setting. The risks seem to 
primarily be that the evaluation for the drugs and the administration of them 
may delay transport.

=Protocols=

You also asked about prehospital protocols for administration of thrombolytics.
Different jurisdictions, of course, have different EMS protocols, and at least 
some of these around the country include field administration of thrombolytics. 
Government bureaucracies work slowly, so it seems likely that the new data 
showing the benefits of early administration of thrombolytics will cause more 
agencies to include their administration in the field.

The following checklist, part of the University of Texas for administration of 
thrombolytics is from the document:

Examples of Prehospital Protocols for Care of Patients with Possible Acute 
Myocardial Infarctions
http://www.physio-control.com/documents/thromprotoc.pdf

---Begin quoted material
University of Texas Southwestern Medical Center
Prehospital EMS Chest Pain Checklist
Possible indications for thrombolytics
1. Oriented, able to cooperate
2. Systolic BP difference < 20
            BP right arm       /
            BP left arm         /
3. Diastolic BP < 120
4. Systolic BP > 80 and < 180

Possible contraindications for thrombolytics
1. History of stroke or brain surgery
2. Acute trauma of any kind
3. Anticoagulant medications
(coumadin, warfarin, heparin)
4. Known bleeding problems
5. Any GI bleeding in last 12 months
6. Any surgery in last two months
7. Terminal cancer
8. Significant liver or kidney disease

---- End quoted material

The document contains other area protocols, which include the possibility of 
administering thrombolytics in the field.

In Tennessee, there is pre-hospital screening for thrombolytics, but it does 
not appear that field personnel administer TPA or other drugs:

Adult EMS protocols for the state of Tennessee
http://www.state.tn.us/health/Downloads/g4027217.pdf

Some county protocols do not include prehospital administration of 
thrombolytics:

City of Albuquerque / Bernalillo County EMS Protocols
http://www.cabq.gov/fire/protocol2.pdf

Riverside County EMS Policy, Protocol & Procedure Manual
http://www.rivcoems.org/EMSppman/Default.htm
(see section 7200, ALS Cardiac Emergencies)


=Support of Prehospital Thrombolytics for AMI=

The following article suggests that there is a reduction in mortality of 18% 
when thrombolytics are administered in the field. It is on MedScape, which 
requires registration, though registration is free:

Update on Strategies to Improve Thrombolysis for Acute Myocardial Infarction
from Pharmacotherapy
http://www.medscape.com/viewarticle/409729

in particular this section of it is relevant:
Reducing delays in administering thrombolytics
http://www.medscape.com/viewarticle/409729_3

“Studies of thrombolytic therapy administered before hospital arrival, or in 
the field, reported reduction in mortality of approximately 18% (1.7% absolute 
reduction) associated with a gain of 61 minutes in time to treatment compared 
with conventionally administered thrombolytics.[33] The ACC-AHA guidelines 
recommend that prehospital administration of thrombolytics be considered only 
when transport to a medical facility would exceed 90 minutes.”

The article goes on to discuss the issues with older thrombolytics, like 
streptokinase, in that they require continuous infusion which is difficult to 
do in a non-hospital setting.


=Non Support of Prehospital Thrombolytics for AMI=

There are also arguments against the use of thrombolytics, and some continue to 
suggest improvements in ECG abilities on ALS transport units.

This article about the use of automatic defibrillators and 12-lead ECGs in the 
Field offers a view toward reducing the time from the MI event to the 
administration of thrombolytics in the emergency department of the hospital:

Current State of the Art in the Management of Patients with Acute Myocardial 
Infarction and Ischemia within the Maryland Emergency Medical Service System
http://www.openseason.com/chestpain/clinicalinformation/maryland/bass.html


=Studies regarding the prehospital use of thrombolytics=

EMS-Compass -- Prehospital Thrombolytics / Fibrinolytics
http://www.mhf.net/emscompass/cardiology/bibliographies/D_thrombolytics.htm

Greenville County EMS Pilot Project Testing Prehospital Thrombolytic Therapy
http://www.scems.com/edassn/newsletter/page4.html


I hope this information is helpful to you in your search. Good luck!

Hi there!

The pre-hospital administration of clot-busting drugs (thrombolytics) in the 
early stages of a heart attack (Acute Myocardial Infarction) does seem to 
increase the chances of survival for patients. As well, in the case of stroke, 
thrombolytic drugs can have a beneficial effect if administered early. The 
statistical benefit of the drugs seems to decrease as the time of 
administration gets further away from the time of the onset of symptoms.

You should also be aware, however, that the use of these drugs is not without 
risks as well. One study suggests that the use of thrombolytics in patients 75 
years and older does not necessarily result in improved outcomes.

You might find the following links helpful in your search for information:

"http://www.rcpe.ac.uk/esd/consensus/stroke_98.html" -- In this article you 
might want to scroll downwards just below the halfway mark of the page, to the 
section entitled "What is the role of thrombolytic therapy in stroke?"

"http://www.cma.ca/cmaj/vol-162/issue-1/0047.htm" -- This is an article from 
the Journal of the Canadian Medical Association. The article is called "Stroke 
Thrombolysis: Is Tissue Plasminogen Activator a Defibrilator for the Brain?"

"http://www.medscape.com/viewarticle/403470" -- This is the abstract and 
introduction from a paper published in the journal Pharmacotherapy. This site 
will require you to register to view the content. It is called "Update on 
Strategies to Improve Thrombolysis for Acute Myocardial Infarction".

"http://www.globaltechnoscan.com/21thNov-27thNov01/clots.htm" -- This is a link 
to an interesting press release. It is titled "Busting Clots in Ambulance Saves 
Half-Hour for Heart Attack Victims".

"http://www.cma.ca/cmaj/vol-154/0483e.htm" -- This is a link to an article 
called "Recommendations for ensuring early thrombolytic therapy for acute 
myocardial infarction". On this site there is also a link to another 
article: "http://www.cma.ca/cmaj/vol-154/0509e.htm".

"http://archinte.ama-assn.org/issues/v162n5/abs/ioi10049.html" -- This is a 
link to an abstract of a study called "Effectiveness of Thrombolytic Therapy 
for Acute Myocardial Infarction in the Elderly".

"http://jama.ama-assn.org/issues/v283n9/abs/joc91236.html" --- An article 
named "Intravenous Tissue-Type Plasminogen Activator for Treatment of Acute 
Stroke".

"http://jama.ama-assn.org/issues/v283n9/ffull/jed00001.html" -- This is a 
particularly interesting and perhaps useful editorial from the Journal of the 
American Medical Association. The title is "Thrombolytic Therapy for Ischemic 
Stroke: From Clinical Trials to Clinical Practice".

"http://jama.ama-assn.org/issues/v283n9/abs/joc91429.html" -- An article also 
from the JAMA, called "Use of Tissue-Type Plasminogen Activator for Acute 
Ischemic Stroke".

"http://www.escardio.org/VPO/" -- This is the latest press release from the 
European Society of Cardiology. It is called "REACTION TO QUERIES REGARDING 
THROMBOLYTIC THERAPY". A PDF formatted document is available 
here: "http://www.escardio.org/VPO/esccommentarchive/ESC-12.03.02.pdf".

"http://www.canjneurolsci.org/25augtoc/can.html" -- A rather technical study 
from the Canadian Journal of Neurological Sciences. It is called "Canadian 
Guidelines for Intravenous Thrombolytic Treatment in Acute Stroke: 
A Consensus Statement of The Canadian Stroke Consortium".


Hope this helps!


Regards,
Edward

hello burnside,

as you know, clot-busting drugs must be given within six hours of an attack, so 
it is crucial that one recognizes the symptoms of a heart attack early.  
paramedics carry these meds on board and can transmit a rhythm strip to your 
local hospital for administration of these drugs, if needed.  you are wise to 
find out about the risks/benefits of these drugs before such a life-threatening 
event occurs.  

for precautionary sake, it would be wise that you have your current list of 
medications written down (and handy -- some suggest keeping it in the 
refrigerator) with your wishes to use/exclude thrombolytic therapy so that 
paramedics may convey your wishes and assess any drug contraindications.  

most of the information you require on tPA and TNK will be at this website:

http://www.nlm.nih.gov/medlineplus/heartattack.html

for additional information, the package insert for TNK is located here:

http://www.fda.gov/cber/label/tenegen060200LB.htm


if you're at risk for coronary artery disease, always discuss possible options 
with your physician, but be an informed healthcare consumer and investigate 
these yourself.  the medlineplus website is very reliable and and has up to 
date information written in layman's language.

hope this information is of assistance.

The American College of cardiology recommendations:
- trials of fibrinolytic therapy have demonstrated the benefit of initiating 
thrombolytic therapy as early as possible after onset of ischemic-type chest 
discomfort. It seems rational therefore to expect that if thrombolytic therapy 
could be started at the time of prehospital evaluation, a greater number of 
lives could be saved. The greatest improvement in outcome is observed when 
treatment can be initiated in the field 60 to 90 minutes earlier than in the 
hospital. Ensuring proper selection of patients for therapy can be difficult, 
and avoiding therapy when it is contraindicated has important medical, legal, 
and economic implications. For these reasons, a general national policy of 
prehospital thrombolytic therapy cannot currently be advocated. Observations 
from prehospital trials suggest that prehospital systems should focus on early 
diagnosis (a relatively minor augmentation in prehospital services) instead of 
delivery of therapy.

http://www.americanheart.org/presenter.jhtml?identifier=1996
http://www.acpjc.org/Content/134/1/ISSUE/ACPJC-2001-134-1-001.htm
http://content.nejm.org/cgi/content/full/329/6/383