FORUM infusion, intravenous, prehospital; MAST, trauma, prehospital; trauma, management, prehospital

MAST And IV Infusion: Do They Help in Prehospital Trauma Management?

]Lloyd S: MAST and IV infusion: Do they help in prehospital trauma man- agement? Ann Emerg Med May 1987;16:565-567.]

A multicenter, prospective, randomized, controlled study of military anti- shock trousers (MAST) and IV infusion in the prehospital care of multiple trauma patients is long overdue. Debate continues across the country over the therapeutic benefit and cost of these prehospital interventions. MAST and IV infusion need unbiased randomized studies to justify their cost and evaluate their efficacy.

Literature review on the use of MAST on hypotensive trauma patients reveals only one prospective controlled study by Bickell et al, 1 which demon- strated no benefit from MAST use. This study was in an urban setting with short transport times and used in the Trauma Score (TS)2, 3 to measure im- provement. Mackersie et al, 4 in a retrospective case study, with "pseudoran- domization" due to inconsistent availability of MAST by paramedic crews, found no benefit from MAST use. This study also took place in an urban setting with rapid transport times and used the TS, blood pressure index, and mortality to measure improved outcome. Smith et al, 5 in a recent paper ad- vocating the "load and go" protocol for hypovolemic trauma patients, stated, "MAST trouser application has not been proven to be effective in hypo- volemic patients in any prospective randomized studies."

Prospective, randomized, controlled studies are needed to further evaluate MAST use in hypotensive trauma patients.i, 4-8 Such studies will help differ- entiate biased, retrospective, and anecdotal data f rom non-biased scien- tifically acquired data. Until the article by Bickell et al,1 papers advocating MAST use used retrospective and anecdotal data to support their beneficial effect; it is on this evidence that our current use of MAST is based>

There is currently controversy over the benefits and risks associated with establishing an IV line in the field when transport time to definitive care is short (less than 20 to 30 minutes). Review of literature on prehospital IV infusion in hypotensive multiple trauma patients reveals much controversy but no prospective randomized trials. It is argued that establishing IV lines in the field has grown from its appropriate, and potentially valuable, use in cardiac arrest patients into its inappropriate, and potentially harmful, use in multiple trauma patients.S, 8-1o

The major concern associated with establishing prehospital IV access in trauma patients is time. 11 It is argued that trauma patients will lose (through hemorrhage) more intravascular volume during the time it takes to establish IV access than will be replaced during their transport to the trauma cen- ter.S,8,1o, ll Some investigators cite evidence that the time required to estab- lish an IV line is greater than the t ime required to transport the patient to the hospital, and that these patients lose more oxygen-carrying intravascular f luid.volume than can be replaced by non-oxygen-carrying intravascular crystalloid solution.S,8,1o The t ime factor associated with establishing an IV line has led to the suggestion that no prehospita] IV access be attempted in multiple trauma patients when transport t ime to a trauma center is less than 20 to 30 minutes.S, 8 Despite the controversy no randomized trials have been carried out to settle this stormy issue.

A randomized trial is the best (strongest) design for assessment of any therapeutic maneuvers because it ensures that every patient has the same

Stephen Lloyd, MD, MCFP(EM) Hamilton, Ontario, Canada

From the Department of Family Medicine, Division of Emergency Medicine, McMaster University, Hamilton, Ontario, Canada.

Received for publication September 24, 1986. Accepted for publication January 9, 1987.

Address for reprints: Stephen Lloyd, MD, MCFP(EM), McMaster University Medical Center, Department of Family Medicine, Room 2R17, 1200 Main Street West, Hamilton, Ontario L8N 3Z5.

16:5 May 1987 Annals of Emergency Medicine 565/83

MAST & IV INFUSION Lloyd

known probability (50%) of receiving one or the other treatment being com- pared. 12 This eliminates investigator bias in patient allocation to specific groups.

To date no prospective randomized studies of MAST or IV infusion have been published in the medical liter- ature. These studies have not been done because of difficulty achieving a large enough sample for statistical sig- nificance and because prehospital con- trol, until recently, has been lacking.

The relat ively low incidence of multiple trauma with associated hy- potension in any one geographic re- gion (handled by prehospital units un- der medical control) makes it difficult to achieve a large enough sample in a reasonable time frame. (In the Hamil- ton area it would take years to collect the required cases.) Prior to the in- stitution of regional paramedic pro- grams (for Ontario, in Hamilton and Toronto) there was little, if any, medi- cal control in the prehospital setting. This lack of medical direction and control hampered both institution and evaluation of these therapies. Current paramedic programs provide an oppor- tunity to control and evaluate these interventions. However, sample size requirements remain a problem.

The studies by BickelD and Macker- sic 4 demonstrated no therapeutic ben- efit of MAST use for hypotensive trauma patients in rapid prehospital transport systems. These studies also raise questions of the value of the TS as a measure of clinical improvement in rapid prehospital transport systems. Bickell's study showed a change in TS from the scene to the trauma center, for control and MAST groups, of 0.6 (_+ 1.7) and 0.7 (+ 1.5), respectively. Mackersie's study showed a change, for non-MAST and MAST groups, of 0.34 (+ .26) and 0.28 (_+ 3.1), respec- tively. Clinically a TS difference of one unit would usually not be viewed as significant. A difference of two units would be more likely viewed as significant. Nei ther Bickell 's nor Mackersie's study demonstrated a clinically significant change in TS for either control or MAST groups.

The TS is a physiologic index (Ta- ble) and is expected to respond to therapeutic interventions that im- prove patient physiology.4,13,14 MAST inflation is thought to improve patient p h y s i o l o g y by i m p r o v e d h e m o - dynamics secondary to increased pe- ripheral vascular resistance and tam-

ponade of bleeding in areas actually encompassed by the trousersA s-22 IV crystalloid infusion is thought to im- prove physiology, in hypovolemic pa- t ients, th rough improved hemo- dynamics with restoration of intra- vascular volume. The lack of TS response in the BickelD and Macker- sic 4 studies suggests either no benefit from MAST inflation or a "sluggish" characteristic within the TS that pre- vents identification of clinical im- provement, or deterioration, in rapid prehospital transport systems (less than 20 minutes).

Considering survival and morbidity as outcome criteria would allow an- other evaluation of the therapeutic impact of MAST and IV in the pre- hospital care of these patients. Sur- vival and morbidity data also would facilitate evaluation of the TS. The va- lidity of the TS would need reevalua- tion if there is no clinically significant change in TS in patients with signifi- cantly improved outcomes. Survival and morbidity data may provide a bet- ter understanding of the clinical sig- nificance of small (less than one unit) change in TS.

There is no ethical dilemma to re- solve in the prehospital randomization in hypotensive multiple trauma pa- tients when transport time to defini- tive care is less than 20 minutes. No randomized controlled studies have been published to evaluate either MAST or IV infusion in the pre- hospital setting. Studies of MAST to date do not show them to be bene- ficial or det r imental to these pa- tientsA,4,s,8, 22 There are no studies in the literature on the prehospital use of IV infusion for patients in rapid trans- port systems (less than 20 minutes to definitive care); however, much con- troversy exists about its possible harm (exsanguination).4,s,s,9

A multicenter, prospective, ran- domized, controlled study of MAST and IV infusion is needed to further evaluate their role in the prehospital care of hypotensive trauma patients. Such a study would help differentiate biased, retrospective, and anecdotal data from non-biased scientifically ac- quired data. Many jurisdictions in Canada and the United States require MAST as routine equipment in all ambulances, and prehospital W access is becoming more available through paramedic programs. There is a sub- stantial cost associated with the pur- chase, maintenance, and personnel

TABLE. Elements of the trauma SCOTG 1

Parameter Score Respiratory Rate

10-24 4

25-35 3

> 35 2

< 1 0 1

0 0

Respiratory Effort Normal 1

Shallow 0

Retractive 0

Systolic Blood Pressure > 90 4

70-90 3

50-69 2

< 50 1

0 (no carotid pulse) 0

Capillary Refill Normal (< 2 sec) 2

Delayed (> 2 sec) 1

None 0

Glasgow Coma Scale 14-15 5

11-13 4

8-10 3

5-7 2

3-4 1

Total Score 1-16

training in MAST use and IV therapy. If MAST and IV therapy have no bene- ficial effect on patient outcome, these health care dollars can be better spent elsewhere.

REFERENCES 1. Bickell WH, Pepe PE, Wyatt CH, et ah Effect of antishock trousers on the trauma score: A prospective analysis in the urban setting. Ann Emerg Med 1985;14:218-222.

2. Champion HR, Sacco WJ, Carnazzo AJ, et ah Trauma score. Crit Care Med 1981;9:672-676.

3. Baker SP, O'Neill B, Haddon W, et ah The in- jury severity score: A method for describing pa- t ients wi th mul t ip le injuries and evaluat ing emergency care. J Trauma 1974;14:187-I96.

4. Mackersie RC, Christensen JM, Lewis FR: The prehospital use of external counterpres- sure: Does MAST make a difference? J Trauma 1984;24:882-888.

5. Smith JP, Bodai BI, Hill AS, et ah Prehospital

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stabilization of critically injured patients: A failed concept. J Trauma 1985;25:65-70.

6. Lane P: Wither PASG (editorial). CAEP Re- view 1985;1:20.

7. Civetta JM, Nussenfeld SR, Rowe TR, et al: Prehospital use of the military antishock trou- ser {MAST). JACEP 1976;5:581-587.

8. Blaisdell FW: Trauma myths and magic: 1984 Fitts lecture. J Trauma 1985;25:856-863.

9. Trunkey DD: Is ALS necessary for pre- hospital trauma care? (editorial). J Trauma 1984; 24:86-87.

10. Border JR, Lewis FR, Apprahamian C, et ah Panel: Prehospital trauma care - - Stabilize or scoop and run. J Trauma 1983;~3:708-71I.

11. Trunkey DD, Lewis FR: Current Therapy Of Trauma 1984-1985. Toronto, BG Decker Inc and CV Mosby Company, 1984, p 4-5.

12. Sackett D, Haynes B, Tugwell P: Clinical

Epidemiology: A Basic Science For Clinical Medicine. Boston/Toronto, Little, Brown and Co, 1985, p 179-180.

13. Moreau M, Gainer PS, Champion H, et al: Application of the trauma score in the pre- hosp i t a l se t t ing . Ann Emerg Med 1985; 14:1049-1054.

14. Zippe C, Burchard KW, Gann DS: Tren- delenburg versus PASG application in moderate hemorrhagic hypoperfusion. ! Trauma 1985; 25:923-932.

15. Holcroft JW, Link DP, Lantz BMT, et ah Ven- ous return and pneumatic antishock garment in hypovolemic baboons. J Trauma 1984;24: 928-937.

16. Ransom K, McSwain NE: Respiratory func- tion following application of MAST trousers. JACEP 1978;7:297-299.

17. Goldsmith SR: Comparative hemodynamic effects of antishock suit and volume expansion

in normal human beings. Ann Emerg Med 1983; 12:348-350.

18. Bivins HG, Knopp R, Tieman C, et ah Blood volume displacement with inflation of anti- shock t rousers . Ann Emerg Med 1982;11: 409-412.

19. Freeman S: Adjunctive techniques, in Tintinalli JE, Rothstein RJ, Krome RL (eds): Emergency Medicine A Comprehensive Study Guide. New York, McGraw-Hill, 1985, p 10-13.

20. Cogbill TH, Good JT Jr, Moore EE, et ah Pulmonary function after military antishock trouser inflation. Surg Forum 1981;32:302.

21. Lane PL: Pneumatic antishock garment in management of hypovolemia. Ontario Med Rev 1982;49:579-584.

22. Baxter FJ, Kessaram RA, BaiIlie F: Pneumat- ic antishock trousers. Can J Surg 1984;27: 423-427.

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