question about MAST/PASG

[Ace844]

Hi All,

Here's some more "on topic literature" for you all to look at....

Hope this helps,

Ace844

EMS Mythology: Part 1

By Bryan E. Bledsoe, DO, FACEP, EMT-P

EMS Myth #1: Medical Anti-Shock Trousers (MAST) autotransfuse a significant amount of blood and save lives.

Paramedics in the 1970s and 1980s often used Medical Anti-Shock Trousers (MAST), also called the Pneumatic Anti-Shock Garment (PASG), for all forms of trauma. It was the standard of care. On many occasions, I came to believe that I had seen patients pulled from the jaws of death after MAST application. In EMS circles, we told stories about doctors or nurses removing or cutting off MAST in the emergency department, only to have the patient become immediately hypotensive and die. EMS people were not the only true believers in MAST. They were often a common component of trauma resuscitation rooms and operating rooms. Invariably, we would have to retrieve the MAST from the OR, as they remained on the patient until the surgical lesion was repaired. We knew the MAST worked. We had seen it work. But, did the MAST really work?

MAST History

The concept of the MAST was first described in 1903 by famed surgeon George W. Crile as a "pneumatic rubber suit" to decrease postural hypotension in neurosurgical patients.1,2 During World War II, Crile's suit was used to prevent blackout in pilots who were subjected to high G forces while flying combat aircraft. The National Aeronautics and Space Administration (NASA) claimed responsibility for developing the medical anti-shock trousers at their Ames Research Center in the 1960s.3 MAST were introduced into medical practice during the war in Vietnam and called "Military Anti-Shock Trousers."4 The value of MAST in the military setting was documented when soldiers with massive trauma, previously considered fatal, were able to survive a 45-minute helicopter ride to a definitive care hospital.5 MAST were introduced into civilian EMS in the 1970s.6

It was postulated that the MAST reversed hypotension by three different mechanisms: 1) Increasing peripheral vascular resistance; 2) tamponading of intra-abdominal bleeding; and 3) autotransfusion of blood from the lower extremities and abdomen to the head and upper trunk.

Most authorities supported the theory that MAST provided a significant autotransfusion. McSwain estimated the amount of blood autotransfused to be 750–1,000 mL.7 In another paper, McSwain estimated that approximately 20% of a patient's blood volume was autotransfused into the heart, brain and lungs following application of MAST.8 Dillman also estimated the amount of blood autotransfused to be approximately 20% of the total blood volume (approximately 1,200 mL in an 85-kg man).9 Based upon these reports, the EMS textbooks of the era picked up the information on MAST, and it was incorporated into day-to-day EMS teaching. The first paramedic textbook stated: "The pressure applied to the legs squeezes at least 2 units of blood out of these extremities, where it is less critically needed, and into the systemic circulation. The net effect is as if the patient were given a 2-unit transfusion of blood; in a sense, then, it is an AUTOTRANSFUSION, since the patient is transfusing himself with blood from his extremities. (Remember, though, that the converse is also true. When the MAST is deflated, blood returns to the legs, and it is as if the patient suddenly lost 2 units of blood. Thus, the MAST is never deflated until adequate volume replacement has been achieved.)"10 The first edition of Basic Trauma Life Support stated the following: "No one has proven how MAS trousers work, but the most likely mechanism is an increase in peripheral vascular resistance by way of circumferential compression. The important thing is that they do work to improve blood pressure and cerebral circulation in the hemorrhagic or spinal shock victim."11 Likewise, the first edition of Pre-Hospital Trauma Life Support stated, "If the patient is hypotensive or there is suspicion of bleeding within the abdomen, the pneumatic anti-shock garment (PASG) should then be placed on the patient and inflated until an adequate blood pressure is obtained. The early use of the PASG will assist in reducing rapid intra-abdominal bleeding."12

Applying the Scientific Method

Later, researchers applied the scientific method to study the effects and effectiveness of the MAST and found that the actual benefits were far less than originally thought. Researchers at Valley Medical Center in Fresno, CA, evaluated the effects of the MAST on healthy volunteers. After removing one liter of blood from the volunteers, the MAST were applied. The amount of blood auto-transfused from the lower extremities and abdomen to the head and upper trunk was measured using sequential radioisotope scans. They found that application of the MAST resulted in an auto-transfusion of less than 5% of the patient's total blood volume. This was approximately 300 mL in an 85 kg man.13 This amount was much less than initial estimates that ranged from 750–1,200 mL. A similar study measured the amount of blood auto-transfused following MAST application to dogs who were suffering hemorrhagic shock following phlebotomy. Again, the amount of blood auto-transfused was approximately 5% of the total blood volume.14 Based on these studies, statements about the auto-transfusion capabilities of the MAST were dropped. Instead, teaching was changed and stated only that MAST increased peripheral vascular resistance.

Researchers then began to look at patient outcomes following application of the MAST. The initial study that questioned the benefit of the MAST was conducted in Houston, TX, in 1989 using the Houston Fire Department EMS system. During a 2½-year period, 201 consecutive patients presenting with penetrating anterior abdominal injuries and an initial prehospital systolic blood pressure of 90 mm Hg or less were entered into the study. All prehospital care was provided by the Houston Fire Department and all patients were delivered to the same regional trauma facility (Ben Taub Hospital). The patients were randomized into control and MAST groups by an alternate-day assignment of MAST use. The resulting study groups were found to be well matched for survival probability indices, prehospital response and transport times, and the volume of IV fluids received. The results demonstrated no significant difference in the survival rates of the control and MAST treatment groups. Based on these data, researchers concluded that, contrary to previous claims, the MAST provides no significant advantage in improving survival in urban prehospital management of penetrating abdominal injuries.15

Another prospective, randomized study investigated 291 traumatic shock patients greater than 15 years of age with blunt or penetrating trauma and a systolic blood pressure of 90 mm Hg or less with clinical signs of hypotension. The patients were randomly assigned to a MAST or non-MAST group. The researchers found that there were no significant differences in hospital stay or mortality between MAST and non-MAST patients. Similarly, in the subset of patients with blunt trauma, MAST were not found to be beneficial.16 In a prestigious Cochrane Review, researchers performed a meta-analysis of the two studies described above and found that the duration of Intensive Care Unit (ICU) stay was 1.7 days longer in the MAST-treated group. They concluded that there was no evidence to suggest that MAST/PASG reduce mortality, length of hospitalization or length of ICU stay in trauma patients. In fact, they found, MAST may actually increase these. They concluded that the data do not support the continued use of MAST/PASG in trauma patients.17

Conclusion

Based on available data, in 1997 the National Association of EMS Physicians issued a position paper on use of MAST/PASG in modern EMS.18 The association concluded that MAST are definitely beneficial in ruptured abdominal aortic aneurysm and possibly beneficial in hypotension due to pelvic fracture, anaphylactic shock refractory to standard therapy, otherwise uncontrollable lower extremity hemorrhage and severe traumatic hypotension (palpable pulse, no blood pressure).19 Even considering these possibilities, any benefit from application of the MAST may be accomplished through rapid transport to a trauma center. Many EMS services have kept MAST for use in possible pelvic and lower extremity fractures. Patients with femur fractures are best treated with traction splints, while patients with pelvic fractures can be treated with a long backboard or similar device. Furthermore, the MAST are expensive (approximately $500 per pair) and take up valuable storage space on the ambulance. MAST are a relic of our past and belong in EMS museums, not on modern ambulances or rescue vehicles.

References

1. Crile GW. Blood Pressure in Surgery: An Experimental and Clinical Research. Philadelphia, PA: JB Lippincott Company, 1903.

2. Crile GW. The Cartwright Prize Essay for 1903. Philadelphia, PA: JB Lippincott Company, 1903.

3. National Aeronautics and Space Administration. 1996 Space Technology Hall of Fame. Innovation 4(2), 1996.

4. Schwab CW, Gore D. MAST: medical antishock trousers. Surgery Annual 15:41–59, 1983.

5. Cutlet BS, Daggett WM. Application of the "G-Suit" to the control of hemorrhage in massive trauma. Ann Surg 173:511–514, 1972.

6. Kaplan BC, Civetti JM, Nagel EL, et al. The military anti-shock trouser in civilian prehospital care. J Trauma 13(10):843–848, 1973.

7. McSwain NE. Pneumatic trousers in the management of shock. J Trauma 17(9):719–724, 1977.

8. McSwain NE. MAST pneumatic trousers: A mechanical device to support blood pressure. Medical Instrumentation 11(6):334–336, Nov–Dec 1977.

9. Dillman PA. The biophysical response to shock trousers. J Emerg Nurs 3(6):21–25, 1977.

10. Caroline NL. Emergency Care in the Streets. Boston, MA: Little, Brown and Company, 1979, p. 86.

11. Campbell JE. Basic Trauma Life Support: Advanced Prehospital Care. Bowie, MD: Brady Communications Company, 1985, p. 54.

12. Butman AE, Paturas JL, McSwain NE, Dineen JP. Pre-Hospital Trauma Life Support. Akron, OH: Emergency Training, 1986, p. 98.

13. Bivins HG, Knopp R, Tiernan C, et al. Blood volume displacement with inflation of antishock trousers. Ann Emerg Med 11(8):409–412, 1982.

14. Lee HR, Blank WF, Massion WH, et al. Venous return in hemorrhagic shock after application of military anti-shock trousers. Am J Emerg Med 1(1):7–11, 1983.

15. Bickell WH, Pepe PE, Bailey ML, et al. Randomized trial of pneumatic antishock garments in the prehospital management of penetrating abdominal injuries. Ann Emerg Med 16(6):653–658, 1987.

16. Chang FC, Harrison PB, Beech RR, Helmar SD. PASG: Does it help in the management of traumatic shock? J Trauma 39(3):453–456, 1995.

17. Dickinson K, Roberts I. Medical anti-shock trousers (pneumatic anti-shock garments) for circulatory support in patients with trauma. Cochrane Review, The Cochrane Library, 2002, p. 4.

18. O'Connor RE, Domeier R. Use of the Pneumatic AntiShock Garment (PASG): NAEMSP Position Paper Prehosp Emerg Care 1(1):32–35, 1997.

19. Chapleau W. PASG: Bad wrap or bad rap? Emerg Med Serv 31(1):75–76, 2002.

Also, here's something from "the edumacated" side, A review which most Md's read....

The Cochrane Database of Systematic Reviews 2005 Issue 4

Copyright © 2005 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Medical anti-shock trousers (pneumatic anti-shock garments) for circulatory support in patients with trauma

Dickinson K, Roberts I

Plain language summary

About one third of injury deaths are due to shock from blood loss. Preventing shock in people with uncontrolled bleeding is therefore vital. Treatment aims to maintain blood pressure, so that tissue damage is minimised. Medical anti-shock trousers (MAST) are believed to increase blood pressure and blood flow to the heart and brain, helping to stabilise the person until they receive further treatment. The review of trials found no evidence that MAST application decreases deaths, with some suggestion that it may even do harm. More research is needed.

Abstract

Background

Medical antishock trousers (MAST) have been used to increase venous return to the heart until definitive care could be given. This, combined with compression of blood vessels, is believed to cause the movement of blood from the lower body to the brain, heart and lungs. However, the equipment is expensive, and may have adverse effects.

Objectives

To quantify the effect on mortality and morbidity of the use of medical anti-shock trousers (MAST)/ pneumatic anti-shock garments (PASG) in patients following trauma.

Search strategy

Trials were identified by searches of the Cochrane Injuries Group Trials Register, the Cochrane Controlled Trials Register, MEDLINE, EMBASE, BIDS ISI Service and Science Citation Index. References in relevant papers identified were followed up. A citation analysis of references to randomised controlled trials was conducted using the Science Citation Index. Authors of identified trials were contacted and asked about any other trials that may have been conducted, whether published or unpublished.

Selection criteria

Randomised and quasi-randomised trials of MAST/PASG in patients following trauma (excluding fractures of the extremities in which MAST/PASG may be used as a splint).

Data collection and analysis

Data were extracted independently by two reviewers. Data were collected on mortality, duration of hospitalisation and ICU stay, and quality of allocation concealment.

Main results

Two trials were identified that met the inclusion criteria. These trials included 1202 randomised patients in total; however, data for only 1075 of these were available.

The relative risk of death with MAST was 1.13 (95% CI 0.97 to 1.32).

Duration of hospitalisation and of intensive care unit stay was longer in the MAST treated group. The weighted mean difference in the length of intensive care unit stay was 1.7 days (95% CI 0.33 to 2.98).

Authors' conclusions

There is no evidence to suggest that MAST/PASG application reduces mortality, length of hospitalisation or length of ICU stay in trauma patients and it is possible that it may increase these. These data do not support the continued use of MAST/PASG in the situation described. However, it should be recognised that, due to the poor quality of the trials, conclusions should be drawn with caution.

[Dustdevil]

Furthermore, the MAST are expensive (approximately $500 per pair)...

Not anymore. Check ebay!

[canuckEMT]

We don't even carry MAST here anymore and have opted for Fluid Resuss. Even though that is coming under scrutiny now.

As far as pelvic Fx's we usually tie a pillow over the top of the pelvis to keep stable, or use a KED as well.

[Ace844]

"Rid & Everyone,"

"Rid," Is this a better place? Or would you like a completely new thread. I chose to x post here because it has some other studies. Here is what was said in the other thread:: http://www.emtcity.com/phpBB2/viewtopic.php?t=401 , here's another related link as well... http://www.emtcity.com/phpBB2/viewtopic.php?t=1713

(Reading Smart: Discovering What the Data Do and Don’t Say

By Elizabeth A. Criss @ RN, MEd)

When a commercial says "four out of five" people agree, what does that mean? The advertiser is hoping you think it means 80 percent of all people support that particular product or idea. But couldn’t it also mean something else? For instance, what if they had only asked five people for their opinions or mailed out only 10 surveys and received five responses – four people for, one against. There are many other possible combinations that could produce these numbers and still not represent 80 percent of the population. Is this wrong? It’s hard to say. The best response is probably that results, like beauty, are in the eyes of the beholder.

That’s all well and good for TV commercials, but this same "data torturing" can occur in medical research. Raw data generated by a project really doesn’t mean anything until it’s analyzed, and the tools used to analyze this information and the way data is compared determine what conclusions can be drawn. That can leave a lot of room for interpretation.

Let’s say you’re interested in finding the latest research on the pneumatic anti-shock garment (PASG). Flipping through the journals, you find a study evaluating the effect of PASGs on nontrauma patients. The abstract states this is a prospective study done on 300 patients during a 12-month period. The findings of the study indicate that PASGs are of little value in the treatment of nontrauma patients in the prehospital environment.

Intrigued by these findings, you read the article. The results section describes the 300 patients. You note that the study divided the patients into two groups: blood pressure (BP) > 60 mmHg and BP < 60 mmHg. To assist in understanding the results, the authors include Tables 1 through 3.

Moving on to the discussion, you note the authors’ conclusion: "For the majority of nontraumatic patients, the PASG is not beneficial and possibly increases mortality." To support their conclusion, there is a more lengthy and detailed explanation than you found in the abstract. Looking back over the information in Tables 1 and 2, you believe this to be a reasonable conclusion.

But what about Table 3? Didn’t it demonstrate that PASG use in these patients reduced mortality? It did, but the authors’ conclusions are still valid. It’s important to note that the authors said "in the majority of "patients," not that the results applied to all patients. So, why didn’t the authors make more reference to the group in Table 3?

Table 3 highlights a subgroup, patients, with a BP of < 60 mmHg that was positively affected by PASG use. Sometimes groups like this are left out due to the small number of patients in the subgroup; a small sample size does not allow the authors to calculate meaningful statistics or draw any significant conclusions. Without statistics, the most the authors can do is discuss the result as a possible trend. Nevertheless, the authors should at least mention this group as a potential area for future research. Another possibility for leaving subgroups out of a discussion is that they did not support the author’s original hypothesis. Although not entirely ethical, this has been done.

The point of all this is that it is important to understand that data can be manipulated. Researchers will sometimes drop patients who don’t fit the desired hypothesis or support a certain position. It is important for you, the reader, to scrutinize the literature and account for all the patients. If the authors say "majority," instead of "all," find out where the rest of the population went. Be suspicious. Ask yourself if these patients were deliberately left out, or if the sample was just too small to be meaningful.

Most of the research published today is well-controlled and scrutinized by professional review panels. However, it doesn’t hurt to become critical reader and ask questions.

Elizabeth Criss, RN, MEd, serves on the Prehospital Care Research Forum Board of Advisers, is a senior research associate at the University of Arizona in Tucson and a base hospital coordinator at University medical Center in Tucson.

This article was reprinted from JEMS, March 1994.

Table 1

All Study Participants

Number of Patients Number of Deaths Percent Mortality

PASG 165 50 30.3

No PASG 135 30 22.3

Table 2

Patients with BP>60 mmHg

Number of Patients Number of Deaths Percent Mortality

PASG 115 44 38.3

No PASG 102 22 21.6

Table 3

Patients with BP<60 mmHg

Number of Patients Number of Deaths Percent Mortality

PASG 50 6 12

No PASG 33 8 24.2

Ace, this is so important it should be a separate topic. I know 3 of the original authors of the Houstan MAST studies. They are renowned and I respect them very much... now with this saying, research on how this started, whom did the research, and the criteria, as well as the variables and population control etc.

THey hate to see me enter any symposium they are talking at.. there is a reason. Like all studies, one need to really understand research and statistics. As well the diversity of how studies are performed.

The PASG Houston study DID NOT describe there was a increase in deaths, or injuries, rather it demonstrated there was no increase in survivability. Rather or basically there was NO difference.

Now, one has to see what type of patients were studied, the application of PASG, the duration the patients had them on, as well as deflation procedures.

If I can recall part of the study involved application of the PASG suit until the "pop off" valves occur. Has anyone ever been able to do this? I have tried on mannequins, and have had the Velcro split or rip apart.. but as of yet NEVER had the pop-off valves sound. I can assure you the pressure required to do this is very high. As well, most medics knew the theory.. pressure increase the lumen of a wound... as well as we had figured out auto transfusion was a myth.

When examining the patients that was studied and the level of trauma they received, I doubt even a trauma sugeon being there in 3 minutes would change the outcome on some. (i.e multiple .357 hollowpoint to chest).

No, believe it or not I am not a big proponent of PASG. Yes, they assist and help in some shock syndromes and situations when applied and used appropriately, but very few cases. What I am passionate for is true an valid studies, having more EMS professionals understanding research and possessing the knowledge of how to truly read and interpret studies as well. Hopefully, we will not have a "knee jerk" reflex again.

* Ironically, PASG is now being marketed under a new name and used for O.B. situations for "hypotensive" patients. As funny, there is so many reports on how well this device works...lol

R/r 911

Studies which will give you na idea of what "rid," refers to::

http://www.globalforumhealth.org/Forum8/Fo...0S%20F8-066.doc

http://www.blackwell-synergy.com/links/doi...28.2002.02197.x

http://www.blackwell-synergy.com/doi/abs/1...28.2006.00873.x

http://www.findarticles.com/p/articles/mi_...38/ai_110729085

Non-Inflatable Anti-Shock Garment for Obstetric Hemorrhage.

Mechanisms, Equipment, Hazards

Obstetric Anesthesia Digest. 25(3):144-145, September 2005.

MAST Study Links::

http://www.brooksidepress.org/Products/Ope...seaMASTSuit.htm

http://www.mrw.interscience.wiley.com/coch...1856/frame.html

http://www.studentbmj.com/back_issues/0200/papers/25.html

http://www.ncbi.nlm.nih.gov/entrez/query.f...p;dopt=Abstract

http://en.wikipedia.org/wiki/Military_Anti-Shock_Trousers

http://www.ncbi.nlm.nih.gov/entrez/query.f...p;dopt=Abstract

http://emj.bmjjournals.com/cgi/content/extract/18/4/274

http://www.jtrauma.com/pt/re/jtrauma/abstr...9856144!8091!-1

http://www.bestbets.org/cgi-bin/bets.pl?record=00090

http://www.studentbmj.com/issues/00/02/papers/25.php

http://www.ingentaconnect.com/content/arn/...000001/art00006

http://www.fpnotebook.com/ORT268.htm

"MAST Level of evidence"

Bickell WH, Pepe PE, Bailey ML et al: Randomized trial of pneumatic antishock garments in the prehospital management of penetrating abdominal injuries. Ann Emerg Med 1987;16(6):79-84 - Medline

I Bickell WH, Pepe PE, Wyatt CH et al: Effect of antishock trousers on the trauma score: A prospective analysis in the urban setting. Ann Emerg Med 1985;14(3):47-51 - Medline

I Mattox KL, Bickell WH, Pepe PE at al: Prospective randomized evaluation of antishock MAST in post-traumatic hypotension. J Trauma 1986;26(9):779-786 - Medline

III Ali J, Purcell C, Vanderby B: The effect of intraabdominal pressure and saline infusion on abdominal aortic hemorrhage. J Cardiovasc Surg 1991;32:653-659 - Medline

III Bass RR: The pneumatic anti-shock garment: Lessons we should have learned. Prehosp Emerg Care 1997;1:59-60 - Medline

III Blackwell TH: Prehospital care. Emerg Med Clinics of North America 1993;11:1-14 - Medline

III Bruining HA, Schattienkerk EM, De Vries JE, et al: Clinical experience with the medical anti-shock trousers(MAST) in the treatment of hemorrhage, especially from compund pelvic fracture. Netherlands J of Surgery 1980;32:102-107 - Medline

III Domeier RM, O'Connor ER, Delbridge TR et al: Position Paper-Use of the pneumatic anti-shock garment(PASG). Prehosp Emerg Care 1997;1(1):32-35 - Medline

III Lloyd S: MAST and IV infusion: Do they help in prehospital trauma management? Ann Emerg Med 1987;16:83-85 - Medline

III Mattox KL, Bickell W, Pepe PE, et al: Prospective MAST study in 911 patients. J of Trauma 1989;29:1104-1112 - Medline

III O'Connor RE, Domeier RM: An evalution of the pneumatic anti-shock garment (PASG) in various clinical settings. Prehos Emerg Care 1997;1(1):36-44 - Medline

III Pepe PE, Bass RR, Mattox KL et al: Clinical trials of the pneumatic antishock garment in the urban prehospital setting. Ann Emerg Med 1986;15:53-56 - Medline

Emergent Stabilization of Pelvic Ring Injuries by Controlled Circumferential Compression: A Clinical Trial.

Article Titles

Journal of Trauma-Injury Infection & Critical Care. 59(3):659-664, September 2005.

Krieg, James C. MD; Mohr, Marcus MS; Ellis, Thomas J. MD; Simpson, Tamara S. MD; Madey, Steven M. MD; Bottlang, Michael PhD

McSwain NE Jr. (Department of Surgery, Tulane University School of Medicine, New Orleans, Louisiana 70112 USA) "Pneumatic anti-shock garment: state of the art 1988." Ann Emerg Med 17(5):506-25 1988 May

Mattox KL; Bickell W; Pepe PE; Burch J; Feliciano D. (Cora and Webb Mading Department of Surgery, Baylor College of Medicine, Houston, Texas 77030 USA) "Prospective MAST study in 911 patients." J Trauma, 29(8):1104-11; discussion 1111- 1989 Aug

Mattox KL; Bickell WH; Pepe PE; Mangelsdorff AD. "Prospective randomized evaluation of antishock MAST in post-traumatic hypotension." J Trauma, 26(9):779-86 1986 Sept

Pepe PE; Bass RR; Mattox KL. "Clinical trials of the pneumatic antishock garment in the urban prehospital setting." Ann Emerg Med, 15(12):1407-10 1986 DEC

Bickell WH; Pepe PE; Bailey ML; Wyatt CH; Mattox KL. "Randomized trial of pneumatic antishock garments in the prehospital management of penetrating abdominal injuries." Ann Emerg Med, 16(6):653-8 1987 June

(PASG: Does It Help in the Management of Traumatic Shock?

Paper

Journal of Trauma-Injury Infection & Critical Care. 39(3):453-456 @ September 1995.

Chang, Frederic C. MD, FACS; Harrison, Paul B. MD, FACS; Beech, Randall R. MD, FACS; Helmer, Stephen D. PhD)

Abstract:

A prospective, randomized study was designed to determine the efficacy of pneumatic antishock garment (PASG) in the treatment of traumatic shock in a medium-size urban community. A total of 291 traumatic shock patients were assigned to either the PASG or No-PASG treatment groups. Of these, data from 248 patients were analyzed in detail. Analysis of demographic factors--such as age, sex, and mechanism of injury--as well as prehospital evaluative tools--such as trauma and CRAMS scores, and injury severity scores--revealed that the two groups were well-matched. This study did not demonstrate significant differences in hospital stay or mortality between PASG and No-PASG patients. Similarly, in the subset of patients with blunt trauma, PASG was not found to be beneficial.

MEDICAL ANTI-SHOCK TROUSERS (PNEUMATIC ANTI-SHOCK GARMENTS) FOR CIRCULATORY SUPPORT IN PATIENTS

Background

To quantify the effect on mortality and morbidity of the use of medical anti-shock trousers (MAST)/pneumatic anti-shock garments (PASG) in patients following trauma.

Results

Two randomised trials involving 1202 patients, of which data was available for 1075 patients. The relative risk of death with MAST was 1.13 (95% CI 0.97 TO 1.32). Duration of hospitalisation was longer in the MAST treated group.

SOCRATES says

There is no evidence to suggest that MAST/PASG application reduces mortality, length of hospitalisation or length of ICU stay in trauma patients and it is possible that it may increase these.

Dickinson K, Roberts I. Medical anti-shock trousers (pneumatic anti-shock garments) for circulatory support in patients with trauma (Cochrane Review). In: The Cochrane Library, Issue 1. Oxford: Update Software, 2001.

(Prehospital Emergency Care

Publisher: Taylor & Francis Health Sciences @ part of the Taylor & Francis Group

Issue: Volume 7, Number 2 / April-June 2003

Pages: 225 - 228

URL: Linking Options

DOI: 10.1080/10903120390936824

REGIONAL BLOOD FLOW AFTER PNEUMATIC ANTI-SHOCK GARMENT INFLATIONMark Hauswald A1 and E. Richard Greene A1 A1 Departments of Clinical Affairs and Emergency Medicine, University of New Mexico Health Sciences Center (MH), Albuquerque, New Mexico; and the Department of Biology, New Mexico Highlands University (ERG), Las Vegas, New Mexico.)

Abstract: Objective. To determine whether fully inflated pneumatic anti-shock garments (PASGs) decrease blood flow to abdominal and retroperitoneal organs. Methods. An experimental study was conducted using a convenience sample of ten healthy adults. A duplex Doppler ultrasound was used to image and measure blood flow at the aortic root (cardiac output), left carotid artery, left subclavian artery, superior mesenteric artery (SMA), left renal artery, and distal aorta. Each subject was imaged before and after inflation of all three compartments of the garment to 90 mm Hg. Data were analyzed with paired t-tests. Results. PASG inflation did not affect cardiac output (5.45 vs. 5.83 L/min, 95% confidence limit (CL) for mean −0.97 to 0.30, p = 0.26), left carotid artery flow (0.34 vs. 0.35 L/min, 95% CL for mean −0.06 to 0.04, p = 0.70), or left subclavian artery flow (0.12 vs. 0.11 L/min, 95% CL for mean −0.01 to 0.03, p = 0.47). Inflation did cause the aortic flow immediately distal to the renal artery to decrease markedly in all subjects (1.01 vs. 0.11 L/min, 95% CL for mean 0.79 to 1.19, p < 0.001). Flow immediately above this point appeared unaffected. Physical interference with the ultrasound probe by the garment precluded measurement of SMA or renal artery flow in five subjects. In the remaining subjects, these values did not change significantly (SMA 0.40 vs. 0.28 L/min, 95% CL for mean −0.11 to 0.33, p = 0.23; renal artery 0.44 vs. 0.51 L/min, 95% CL for mean −0.09 to 0.08, p = 0.78). Conclusion. PASG inflation caused a dramatic decrease in aortic blood flow over a small area immediately distal to the renal arteries but had little or no effect above this point. This provides support for the use of PASG to decrease otherwise uncontrollable hemorrhage from the iliac, pelvic, and leg vessels, but not for injuries above them.

Hope this helps,

ACE844