environmental 1 · r. a. ricca, k. fink, l. i. katzin, and s. l. warren following determinations...

EFFECTOF ENVIRONMENTALTEMPERATUREONEXPERIMENTALTRAUMATICSHOCKIN DOGS1

By RENATOA. RICCA, K. FINK, LEONARDI. KATZIN, ANDSTAFFORDL. WARREN

(From the Department of Radiology of the University of Rochestr School of Medicine and Dentistry,Rochester, N. Y.)

(Received for publication June 5, 1944)

INTRODUCTION

A survey of the recent reviews (1 to 3), andthe many recent articles on experimentally pro-duced shock, indicate that a variety of stand-ardized procedures are used to study a fairlyreproducible syndrome. It seems obvious, how-ever, from the literature and our own experience,that even in the hands of experienced investiga-tors, there is enough lack of reproducibility inthese so-called standardized experiments to in-troduce a large element of confusion and contro-versy. Our experiments lead us to suggest thatthe influence of seasonal variations of laboratorytemperatures can influence, if not actually con-trol, the outcome of the shock experiments pro-duced by muscle crushing by means of themodified Blalock press (4). It is apparent, there-fore, that control of the environmental or roomtemperature is essential in the conduct of astandard shock experiment. The therapeuticapplications of this possibility are obvious, andare verified by the experiments reported below.With room temperatures of 280 C., the outcomeof the 5-hour press experiment is fatal in 90per cent of the cases, while with room tempera-tures of 160 C., it is fatal in only a small per-centage of the cases, all other conditions remain-ing the same.

Recently, others have indicated the thera-peutic importance of the proper environmentaltemperature. Some investigators (5) have re-ported an optimal environmental temperatureof 750 F. for bum shock in rats. Others (6)

1 The work described in this paper was done under acontract, recommended by the Committee on MedicalResearch, between the Office of Scientific Research andDevelopment and the University of Rochester School ofMedicine and Dentistry. Part of the work was alsoassisted by grants in aid from the Rockefeller Foundationand the Fluid Research Fund of the University ofRochester.

also report that environmental temperatures"in the neighborhood of mammalian body tem-perature" prolong the survival time in shockinduced by intestinal trauma. Significant ele-vations in body temperature have been found todecrease the chance of survival, and shorten thesurvival period of the dog in shock as a result ofmuscle trauma (7).

The environmental temperature apparentlycontrols the animal's body temperature eleva-tion during the period of injury and the criticalperiod immediately following it. Apparently,the chain of events which is necessary to producethe fatal outcome is activated and produced in anoverwhelming degree only when the body tem-perature is in the febrile level. In order toprevent the development of fatal shock, there-fore, therapeutic efforts should be directed to-ward maintaining nearly normal or even slightlysubnormal temperatures.

METHODS

The experimental animals used in the Blalock type ofpress (4) experiment were dogs, generally ranging in weightfrom 15 to 27 kgm. Veterinary Nembutal anesthesia wasadministered intraperitoneally in all experiments. Theinitial dosage was 60 mgm., plus 30 mgm. per kgm. bodyweight. Additional anesthetic was given as required, andin almost no case was anesthetic administered during thelast hour before the press was removed and subsequent tothe removal of the press.

Tissue injury and peripheral circulatory collapse wereinduced by confinement of one thigh of the dog in a pressfor a period of 5 hours. Usually within 1 hour afterremoval of the press, the dog showed evidence of shock.Blood samples for analyses were taken from the externaljugular vein as follows: (a) 15 ml. just before anesthesia,(b) 40 ml. at 10 minutes following complete anesthesia, orimmediately before the press was applied, (c) 15 ml.one-half hour before removal of the press, (d) 40 ml. 3hours after removal of the press, and (e) 40 ml. at exitus,or at 24 hours after removal of the press if the animalsurvived. Coagiklation of blood was avoided by use of2 mgm. of potassium oxalate per ml. of whole blood. The

127

R. A. RICCA, K. FINK, L. I. KATZIN, AND S. L. WARREN

following determinations were made on samples of thedog's blood. Plasma or serum protein concentration wasdone by the micro-Kjeldahl method. In fibrinogen de-terminations, the tlot was formed by the method ofCullen and Van Slyke (8), and the nitrogen in the clotdetermined by the micro-Kjeldahl method. Whole bloodnon-protein nitrogen was determined by the method ofKoch and McMeekin (9), urea by the method of Karr (10),creatine and creatinine by the method of Folin and Wu(11). Hematocrits, red cell osmotic fragility, and plasmaor serum specific gravity were also done routinely on theblood samples. The specific gravities were done by thepycnometer method (12).

FIG. 1. THE MODIFIED BLALOCI PRESS

The dog's thigh is placed in the space marked A. B isa groove to accommodate the femur. C is a calibratedknee action spring (from a Buick car). The desiredpressure is exerted on the thigh by screwing down thebolts, D, until the spring has been compressed the requisiteamount.

The surviving dogs were restrained on the table for 12hours following the removal of the press. If the animalstill survived at 12 hours, it was placed on the floor on aleash, with a rubber mat or other soft bedding. As soonas the dog was able to lap water spontaneously (usuallywithin 3 hours after removal of the press), it was offered150 ml. of drinking water at 2-hour intervals. No otheraliment was given in the 24-hour period following removalof the press. Dogs alive at the end of 24 hours werecounted as survivals; those succumbing naturally in lessthan 24 hours were counted as deaths from acute shock,unless contributing pathology, not related to shock, wasfound at autopsy. Autopsies were performed on animalsthat succumbed and others as indicated, and sections ofthe tissues were taken for histological examination.

The modified Blalock type of press used consists of 2jaw boards and 2 three-eighths inch steel plates (Figure 1).The ridged jaw boards contain a central groove corre-sponding to the position of the femur, so that completemuscle crushing can be obtained without bone damage, orinterference from the bone. Ordinarily the skin is notbroken by the press. Oversize boltholes in the boardsand steel plates allow the 2 jaws to assume the naturalangle of the faces of the dog thigh, while the upper jawand upper steel plate are parallel to each other. Thisdistributes the pressure over the maximum surface of theanimal's thigh, and keeps the pressure normal to the thighsurface at a maximum. Due to the impracticability ofdetermining pressures at the skin surface in this arrange-ment, all pressure values given in the paper refer to over-allpressures. The single large spring between the top jaw ofthe press and the upper steel plate has been calibrated sothat pressures may be read from the calibration curveafter measuring the length of the compressed spring.Pressures from 500 pounds to 4000 pounds have been used.A slip of heavy galvanized metal or of steel may be placedat the lower end of the spring to avoid splitting thewooden upper jaw of the press, in the same manner thatthe lower steel plate protects and supports the woodenlower jaw.

A typical experiment follows.Animal: 42-917Date: 3-3-43Room temperature: 240 C. + 0.50 C.Weight of dog: 20 kgm.

1:15 P.M.-Rectal temperature: 380 C.Pulse: 13615 ml. blood taken

Serum protein: 5.9 grams per centFibrinogen: 0.32 grams per centHematocrit: 42.6 per centSpecific gravity: 1.0227Clotting time: 7 minutes and 35 seconds

1:20 P.M.-8 ml. Nembutal, intraperitoneally1:45 P.M.-40 ml. blood taken

Serum protein: 5.7 grams per centFibrinogen: 0.30 grams per centWhole blood NPN: 26.4 mgm. per centHematocrit: 34.4 per centSpecific gravity: 1.0217

128

ENVIRONMENTALTEMPERATUREIN TRAUMATIC SHOCK

Clotting time: 9 minutes and 30 secondsFragility: 0.50 0.475 0.45 0.425 0.40 0.375

0 1+ 2+ 3+ 4+ completeRectal temperature: 39.3° C.Pulse: 144

2:10 P.M.-2 ml. Nembutal, intraperitoneally2:15 P.M.-Press put on, 2000 pounds pressure2:40 P.M.-2 ml. Nembutal, intraperitoneally3:00 P.M.-Rectal temperature: 38.90 C.

Pulse: 1624:00 P.M.-2 ml. Nembutal, intraperitoneally

Rectal temperature: 39.20 C.Pulse: 176

5:00 P.M.-Rectal temperature: 37.9° C.Pulse: 192

6:45 P.M.-15 ml. blood takenSerum protein: 5.9 grams per centFibrinogen: 0.33 grams per centHematocrit: 43.1 per centClotting time: 11 minutes

7:00 P.M.-Rectal temperature: 40.20 C.Pulse: 204

7:15 P.M.-Press off8:00 P.M.-Rectal temperature: 40.00 C.

Pulse: 2009:00 P.M.-Rectal temperature: 40.70 C.

Pulse: 196Refused water

10:00 P.M.-Rectal temperature: 40.4° C.Pulse: 170

10:15 P.M.-40 ml. blood takenSerum protein: 7.3 grams per centFibrinogen: 0.36 grams per centWhole blood NPN: 59.8 mgm. per centHematocrit: 64.2 per centClotting time: 3 minutes and 25 secondsSpecific gravity: 1.0218Fragility: 0.525 0.50 0.475 0.45 0.425 0.40

0 1+ 2+ 3+ 4+ completeLeg measurements:

Normal Traumatizedinches inches15 -Groin 1910 -2 inches above knee 11%7Y2-2 inches below knee 843Y-Ankle - 4

11:00 P.M.-Rectal temperature: 39.60 C.Pulse: 180

12:00 midnight-Rectal temperature: 39.30 C.Pulse: 186

1:05 A.M.-Dog diedExitus blood taken

Serum protein: 8.6 grams per centFibrinogen: 0.40 grams per centWhole blood NPN: 79.3 mgm. per centHematocrit: 75.2 per centClotting time: 5 minutes and 20 secondsSpecific gravity: 1.0304

Fragility: 0.55 0.525 0.50 0.475 0.45 0.4250 1+ 2+ 3+ 4+ complete

Survival time: 6 hours after removal of the pressLeg weights:

Normal: 1840 gramsTraumatized: 2680 gramsGain in weight of traumatized leg: 840 grams

Heart: Subendocardial hemorrhagesLungs: Passive congestionLiver: Passive congestionSpleen: HemorrhagesKidneys: Passive congestionStomach and small intestine: Submucosal hemorrhagesTraumatized leg: No gas

CHOICE OF STANDARDPRESSURE

Using the arbitrary time of 5 hours, whichhas been adopted by Blalock (1) and by otherworkers with crush and tourniquet shock (13, 14),it was necessary to determine the proper pres-sure to produce fatal shock in a uniform fashion.Experiments were performed with pressureranging from 500 pounds to 4000 pounds. Ascan be seen from Table I, pressures below 1500

TABLE I

The effect of pressure on survivalPress on for 5 hours. Nembutal anesthesia.

Number Average Range ofOver-all of Number Survival death deathpressure animals surviving times times

lbs. per cent hours hours500 2* 1 50 7

1000 1 1 1001500 6 0 0 8j 4j to 212000 7 0 0 12* 5 to 20*3000 6 1 17 7t 2j to 134000 1 0 0 5*

* The animal which succumbedAtelectasis found at autopsy.

aspirated vomitus.

pounds can be expected to yield a high percentageof survivals. Results are fairly uniform from1500 to 3000 pounds, in so far as the proportionof survivals and average death times go. How-ever, autopsy of the animals succumbing showsthat although no hemorrhages are detectable inthe injured limb with 1500 pounds, there beingpresent only a clear, rapidly clotting plasma-likefluid, numerous punctate hemorrhages are foundat 3000 pounds, and intramuscular and inter-muscular hemorrhage are prominent features at4000 pounds. At 2000 pounds, only an occa-sional case has a few punctate hemorrhages.

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The pressure of 2000 pounds, using this type ofpress, was therefore adopted as the standard.This is sufficiently above the minimum of 1500pounds to protect against the effects of size varia-tions in the animals, while not high enough tointroduce the additional complication of tissuehemorrhage. 'The press was applied high againstthe body so that all the muscles of the thigh fromthe head of the femur down were included in thepress.

Two thousand pounds pressure is sufficient toocclude temporarily, and apparently completely,the normal circulation to the limb while thepress is on. Temperature records taken bythermocouples placed at various locations in thelimb while in the press show a steady drop intemperature of the tissues, indicating that thecirculation is effectively interrupted. On re-moval of the press, the limb temperaturespromptly rise. An example of one such experi-ment is included in Figure 2. The low pressures

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FIG. 2. TEMPERATUREOF TRAUMATIZEDTHIGH ASCOMPAREDTO THE NoRmALTHIGH

Press on for 5 hours, 2000 pounds over-all pressure.Nembutal anesthesia. Room temperature 28° C. Re-warming of the traumatized thigh is rapid after removal ofthe press. It is to be noted that the temperature of thesuperficial muscles of the normal thigh drops after removalof the press. This is coincident with cool extremities on

palpation.

where survival rates are high (i.e., less than1500 pounds) probably allow some residual circu-lation. When the press is removed after pres-

sures of 2000 pounds and above, the pattern ofthe jaws of the press is clearly marked on thelimb. Subsequent to removal of the press, thelimb usually, although not always, promptlycommences to swell. After 4000 pounds pres-

sure, rewarnming of the limb, as well as swelling

when present, is relatively slow, leading to thesuspicion that the circulation has suffered amore definite obstruction than is the case at thelower pressures. These statements are basedon more experiments than appear in the Table.

The temperature in the crushed limb afterremoval of the press tends to parallel that of thenormal side in the latter part of the experiment,and this, in turn, is influenced by the rise or fallof the general body temperature. In this con-nection, just before the animal develops otherevidence of shock, the deep muscle temperaturesof the extremities begin to fall and continue todo so during the progression of the shock state(Figure 2). This is probably a result of periph-eral vascular constriction. This fall in tempera-ture tends to be more rapid in a cold environ-ment and less at the high room temperatures, ormay not appear if the dog's body temperatureis either artificially or spontaneously elevated.The latter case usually is fatal.

AIR TEMPERATUREAND SURVIVAL

Fluctuations of the room temperature, withina surprisingly narrow range, are sufficient toaccount for the difference between death andsurvival of the animal in which shock has beenproduced by the crush injury. Failure to recog-nize the importance of this factor has un-doubtedly been the cause of the disconcertingand confusing irregularities in control experi-ments, and may have contributed greatly to thedifficulty noted in other laboratories as well asby ourselves in standardizing the experimentalproduction of fatal shock as a result of crushinjury. It has been found in our experimentsthat by using a room temperature of 280 C. thedeath rate is high; if the environmental tempera-ture is dropped only 120 C. to 160 C., almostcomplete saving of the animals results. At aconstant room temperature of 240 C., betweenthese extremes, there is an intermediate mor-tality rate. A review of our experiments during2 summer periods and 1 winter indicates thatthe environmental (room) temperature hag beena definite controlling factor in all our previousexperiments.

A different effect is found if one temperatureis maintained during the period the animal is inthe press, and following removal of the press the

130

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TABLE II

Effect of temprature on survivalPress on for S hours, 2000 pounds over-all pressure.

Nembutal anesthesia.

. Num- Num- Average Re oRoom bu er Sur- AeaeRneoIer of death deathtemp. dogs sur-ing a times times

per cext hours hours160 C. 6 5 83 12200 C. 7 6 86 11240 C. 13 5 38 9 5j to 1328°C. 20 2 10 71 3 to21

160 C. while in- 10 6 60 91 61 to 12jury was pro-duced. 280 C.after removalof press.

280 C. while in- 10 4 40 71 6 to 83jury was pro-duced. 160 C.after removalof press.

Ice packs on 19 18 95 18traumatizedextremity.

animal is transferred to another temperature.In these experiments, dogs were kept at 28° C.for the 5 hours the press was in place, and then

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removed to 160 C. following removal of the press,or the reverse procedure was employed. Bothof these experiments give mortality rates inter-mediate between those found when the experi-mental temperatures were kept constant Theresults of these experiments are included inTable II. The temperature at which the injuryis produced apparently has an effect upon thesubsequent course of events.

Dogs kept in a warm environment while thepress is on can be saved even more efficiently,without removal from the warm environment,if immediately upon removal of the press thetraumatized extremity is completely investedwith ice in cloth bags. The results are sum-marized in Table II. The ice-bag must be lefton the extremity for a period of approximately4 days. If the ice was removed before the ex-piration of this period, the dog rapidly becamesick, with vomiting and diarrhea, and an eleva-tion of body temperature. Upon replacementof the ice-bags, these symptoms rapidly sub-sided. Deep temperatures near 200 C. seemto be optimal for the chilled area. At the endof the 4-day period, after the ice was removed,

of ConsTAnT Room TEmPERATURLRGE RICT4L TEmPtPTuRR&

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FIG. 3. AVERAGEHouRLY REcTAL TEMPERATUREAT THERooM TEmPERATUREINDICATED

The group done in a room temperature of 280 C. consists of 20 dogs, andthe group at 160 C. consists of 6 dogs. The rectal temperature of dogskept in a room temperature of 160 C. is distinctly lower than those keptat 280 C.

131


healing was slow and the dogs usually developeda gas gangrene infection of the traumatizedlimb. This was partially controlled by theadministration of sodium sulfadiazine either bymouth or intravenously, maintaining bloodlevels of about 12 mgm. per cent.

It is fairly clear from Figures 3, 4, and 5 thatthe-body temperature of the animals is influencedmarkedly by the environmental temperature.The animals kept at 160 C. show an averagebody temperature distinctly lower than thosekept at 280 C. Also, in the experiments inwhich animals that had been kept at one tem-perature and were taken to another temperatureat the time the press was removed, the animalssuccumbing in each group showed progressivelyhigher body temperatures than did the survivors.In transferring from the high temperatures tothe low, death occurred in the group whichlagged in its fall of body temperature; in trans-ferring from the low to the high temperatures,death occurred in those animals whose bodytemperatures rose most rapidly to febrile levels.On reviewing for the past 18 months our previousexperiments, it was found that the animals which

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FIG. 4. ROOMTEMPERATUREOF 160 C. WHILE THE

PRESS WASON, AND 280 C. AFTERREMOVALOF THE PRESS

Average hourly rectal temperature. There are 6 dogsin the survival group and 4 in the group which succumbed.The rectal temperature rises abruptly on removal to thewarm room, and more so in those destined to succumbthan in those destined to survive.

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FIG. 5. ROOMTEMPERATUREOF 280 C. WHILE THEPRESS WASON, AND 160 C. AFTER

REMOVALOF THE PRESSAverage hourly rectal temperature. There are 4 dogs

in the survival group, and 6 in the group which succumbed.The rectal temperature drops abruptly on removal to thecold room, and more so in those destined to survive thanin those destined to succumb.

were treated in a room of uncontrolled tempera-ture (260 C. to 350 C.) during the hot monthsof the year behaved like those treated at con-trolled high room temperatures, while thosetreated during the cold winter months at un-controlled room temperatures (15° C. to 220 C.)likewise behaved like those in the controlledlower room temperatures. Thus there seemsto be no doubt that the high body temperatureof the shocked animal is largely a determiningfactor in the fatal outcome, and that the environ-mental temperature is a major factor in thefinal body temperature achieved. The rectaltemperatures of the dogs kept in a hot roomwith ice investing the traumatized thigh are notincluded in the Figures. The body tempera-tures of these dogs behaved, in general, like thebody temperatures of the dogs injured at a highroom temperature and then removed to lowroom temperature upon removal of the press.

PATHOLOGICALFINDINGS

Of the dogs subjected to 2000 pounds pressurein the press, 34 complete autopsy records areavailable on animals that succumbed in a fairlycomparable state and duration of shock atvarious periods, less than 24 hours after removalof the press. The incidence of pathologicalfindings in this group is as follows: spleen en-largement and hemorrhage, 85 per cent (enlarge-

132


ment due in part to Nembutal anesthesia);submucosal hemorrhages of the stomach, 70per cent; of the small intestine, 32 per cent;hemorrhages in the crushed leg, usually punc-tate in character, 12 per cent; acute gastriculcer, 3 per cent. Certain characteristics werelooked for only in the later experiments, andare calculated on the basis of 24 autopsies ratherthan 34. Thus, lung hemorrhages were foundin 24 per cent, and gas gangrene of the trau-matized extremity in about 12 per cent of thecases. Subendocardial hemorrhages were foundin 54 per cent of cases (15). Gas gangrene de-veloped rarely in the experiments conducted atthe lower room temperatures, and more fre-quently at the high temperatures. In the ex-periments with ice-packs, the dogs usuallyshowed gas gangrene by the fourth day followinginjury. It should be pointed out that all ofthese pathological findings, in addition to thecharacteristic congestion of all the viscera, ap-pear in less than 24 hours, many of them inonly a few hours.

Study of sections of the kidney and liver indi-cates that damage to the renal tubules andcentral necrosis of the liver are also character-istic of crush shock. Definite kidney damage(usually hydropic degeneration of the tubularepithelium) is visible in animals that have suc-cumbed in as short a time as 3 hours followingthe removal of the press, and has been seen inalmost all the sections examined. The urineoutput following crush injury in these animalsis very scanty. The urine frequently containsred cells, and the supernatant fluid after centri-fuging gives a positive benzidine test and astrongly positive protein test.

LABORATORYFINDINGS

In as much as the animals either succumbedto peripheral circulatory failure or were out ofdanger within 24 hours following removal ofthe press, attention has been restricted pri-marily to the early or critical part of thisperiod. Some animals have succumbed, withall or most of the above changes fully developed,in less than 3 hours after removal of the press.Accordingly, blood changes that occur withinthe 3 hours immediately following removal ofthe press may be expected to be of more sig-

nificance in tracing the onset and development ofthe collapse state than those that occur later,after the irreversible phases of the progressionhave been well established. Therefore, mostsignificance has been attributed to the samplestaken 3 hours after the removal of the press, andto their relationship to the 3 control samples thatpreceded them.

Table III summarizes the results of bloodchemical determinations which have shown sig-nificant changes during shock as compared tocontrol normal samples. It is to be noted thatplasma total proteins did not show any sig-nificant change during shock while serum totalproteins were increased in concentration. Withprecautions taken to use a constant concentra-tion of oxalate in all blood samples when ananticoagulant was used, variations in amount ofoxalate can be considered minor. However,there is still the possibility that even slight varia-tions of oxalate concentration, when coupled withconsiderable changes in hematocrit, may resultin erratic values for plasma protein values. Sucha behavior has been noticed and remarked upon(8) and it was reported that plasma proteinvalues varied with the oxalate concentration.For this reason, and since serum protein valueswere consistent and gave results which were com-parable from animal to animal, in the latter partof the experimental series, serum protein con-centrations were done instead of plasma proteinconcentrations.

Three hours after removal of the press, serumproteins showed, on the average, a rise to 7.1grams protein per hundred ml. from the controllevel of 6.0 to 6.2 grams. Only 1 animal in 24failed to show this upward trend of proteinlevel, and in only 4 was there a change of lessthan 0.5 gram per hundred ml. On the average,the animals destined to survive showed a smallerrise than those destined to succumb. However,in the individual dog, the change was too variableto predict whether or not it was going to survive.

The non-protein nitrogen control values werequite uniform, averaging 32 mgm. per hundredml. of whole blood. Within 3 hours after re-moval of the press, the value had risen to anaverage of 50.9 mgm. per cent in the animalswhich were to survive, and to 59.6 mgm. per centin those destined to succumb. At 24 hours, for

133

R. A. RICCA, K. FINK, L. I. KATZINp AND S. L. WARREN

TABLE III

Blood chemical and physical changes during shock2000 pounds pressure. Nembutal anesthesia. The values represent averages of the number of dogs shown.

One-half 3 hours 24 hoursNumber Before 10 minutes hour before | afte riu after re-of dogs anesthesia afstehersa | of thoa oExuesm moval ofanshsa he press ei press the press

Total plasma protein Survivals 15 5.7 5.9 5.8 5.8 5.2(grams per 100 mi.)

Deaths 26 5.8 6.0 5.7 5.6 6.1

Total serum protein Survivals 10 6.1 5.8 5.8 6.5 5.4(grams per 100 ml.) I____ I____ I___ _ _ _ _ _ _ _ _ _- _ _ _ _ _ _ _

Deaths 14 6.4 6.1 6.2 7.5 7.2

Fibrinogen Survivals 25 0.27 0.27 0.29 0.31 0.49(grams per 100ml.)l

Deaths 40 0.30 0.29 0.32 0.32 0.38

Survivals 11 1.0237 1.0234 1.0237 1.0249 1.0215Serum specific gravity

Deaths 14 1.0245 1.0238 1.0244 1.0266 1.0276

Survivals 41 40.7 39.3 40.1 61.1 49.3Hematocrit

Deaths 50 42.2 40.3 41.1 60.9 66.7

Non-protein nitrogen Survivals 25 32.0 50.9 70.4(mgm. per 100 ml.)

Deaths 37 31.8 59.6 78.5

the survivors, it averaged 70.4 mgm. per cent,while in the animals that had succumbed in lessthan 24 hours, it averaged 78.5 mgm. per cent atexitus. The difference in NPNvalues betweensurvivors and non-survivors at 3 hours is highlysignificant statistically (by Fisher's t test).

In one series of experiments, the NPN com-ponents, urea, creatine, and creatinine, weredetermined (13 animals). The blood ureanitrogen parallels very closely the changes intotal NPN, and comprises from 30 per centto 50 per cent of the total NPN. The creatineand creatinine concentration increased 2- to3-fold during shock over the control values.

Fibrinogen values remained almost stationaryduring the period before removal of the press.The 3 successive means for this control intervalare 0.29, 0.28, and 0.31 grams per hundred ml.Three hours following removal of the press,the mean value was still 0.32 grams per hundredml. The mean exitus value for the dogs thatsuccumbed was 0.38 grams per cent, while thesurvivors averaged 0.49 grams per cent at 24hours. Plotting values against time indicatesthat this difference is due only to the greater timethe survivors had to build up their fibrinogen

levels. This increase in fibrinogen followingcrush injury is in accord with the work of others(16), and has also been reported as occurringduring tourniquet shock (17).

Three hours after removal of the press, theaverage serum specific gravity value rose, from acontrol level of 1.0237, to 1.0249 in the case of thesurvivals, and from 1.0244 to 1.0266 in those thatdied. Of 25 animals, 2 failed to exhibit thisupward trend, and in only 5 was there a changeof less than 0.0011.

The agreement between the serum proteindetermined by the micro-Kjeldahl method andserum specific gravity is illustrated by Figure 6.The distribution is much like that shown byMoore and Van Slyke (18). In the earlier partof the experimental series, parallel determina-tions of plasma specific gravities and plasmaprotein concentrations were done, measuredamounts of potassium oxalate being used asanticoagulant. There was no agreement be-tween these plasma specific gravities and theirplasma protein counterpart. The method thenwas changed in favor of the serum values whichwere consistent. The possible effect of theoxalate has already been discussed.

134


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FIG. 6. SERUMPROTEIN CONCENTRATIONS,DETERMINEDCHEMICALLY, PLOTTEDAGAINST SERUMSPECIFIC GRAVITYEach point represents a parallel determination of serum protein by the micro-Kjeldahl method and serum specific

gravity by the pycnometer method.

The mean initial hematocrit for all animalswas about 41.5 per cent. The mean valuedropped to 40.5 per cent after anesthesia (Nem-butal) was induced, but rose to its original levelbefore removal of the press. Within 3 hoursfollowing removal of the press, the mean valuerose to 61 per cent in both survivors.and thosedestined to succumb. At 24 hours, the sur-

vivors' hematocrit dropped to a mean of 49per cent while the mean exitus level of the non-

survivors was 67 per cent. It should not beinferred from this that the individual behaviorwas regular. A given animal might show, andin most case§ did show, extreme irregularity as

compared to the average. Occasionally, thehematocrit rose following anesthesia; the exitushematocrit was sometimes lower than the 3-hoursample; and the animals surviving frequentlyshowed greater increase in hematocrit than thosesuccumbing. Initial hematocrit values rangedfrom 20 per cent to 61.1 per cent, and exitushematocrit values varied from 38 per cent to82.8 per cent.

Red cell fragilitiesIt had been noticed that hemolysis would be

found in many blood samples, particularly near

exitus, unless great care were taken in handlingthe samples, and it was found often in spite ofgreat care.

The osmotic fragility of the erythrocytes was

determined by means of the highest concentra-tion of sodium chloride producing completehemolysis. Tubes were set up containing from0.275 per cent NaCl to 0.475 per cent NaCl, insteps of 0.025 per cent. One drop of defibrinatedblood was added to 5 ml. of the salt solution,the tube was mixed thoroughly, and then left tosettle for 1 hour. At this time, it was easy todetermine the point at which complete hemolysisoccurred in the series. Usually the hemolysisrange covered 5 tubes.

The initial or control fragility level varied tosome extent. In a series of 136 control samplesfrom different dogs, hemolysis occurred over

the range from 0.275 per cent to 0.400 per centNaCl. The mean value was 0.35 per cent. One-third of the animals showed this mean value;124 of the 136 (90.6 per cent) are included in therange extending from 0.325 per cent to 0.375 per

cent NaCl (one interval each side of the mean).The mode is at 0.325 per cent.

There were 76 dogs in which blood samplingwas complete enough for comparative purposes.

At 3 hours after removal of the press, 56 of the76 dogs showed a rise in fragility of from 1 to4 tubes; 11 showed no change; and 9 showed a

drop in fragility of from 1 to 4 tubes. If thegroups of dogs are separated into those whichsurvived and those which succumbed, a distinctdifference is found. Both groups showed an

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almost normal distribution, but the mode wasshifted. For the animals destined to survive,the mean change at 3 hours was +0.86 tubes,with the mode at +1 tube (0.350 per cent).For those destined to succumb, the mean changewas + 1.46 tubes, with the mode at + 2 tubes(0.375 per cent). In the surviving group, 12 of35 animals showed no change or a decrease infragility of 1 to 2 tubes. In 41 animals thatsuccumbed, 4 showed no rise, and 4 showed adrop of 1 tube. On the other hand, 6 dogs thatsuccumbed showed rises of 3 or 4 tubes in contrastto only 2 dogs with similar changes in the groupof survivors. These changes are shown inFigure 7.

The rise in fragility is evident as early as 3hours after release of the press. To determinejust how soon after trauma the fragility changewas noticeable, fragilities were followed at closeintervals in 2 dogs kept in a room temperatureof 28° C. Measurements were started with thepre-anesthetic blood sample, and continued athourly intervals until the press was removed.Beginning at 10 minutes after removal of the

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FIG. 7. ERYTHROCYTEFRAGILITY CHANGESDURING SHOCK

Abscissa values represent highest concentration of salinenecessary for complete hemolysis. The solid line curverepresents the distribution of fragility of control samplesin a total of 136 dogs. During shock, the mode and meanare shifted to the right, and more so for those dogs thatsuccumbed than for those that survived. C-2 is thesample taken before the press is applied; C-4, that taken3 hours after removal of the press when the animal is inshock.

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FIG. 8. ERYTHROCYTEFRAGILITY CHANGESIN 2 DOGS

press, determinations were made at 30-minuteintervals. The curves obtained are shown inFigure 8. Both dogs started with completehemolysis at 0.325 per cent saline. Serumspecific gravities and red cell counts were alsodone on the same blood samples used above.Both the specific gravity and cell counts roseabruptly following removal of the press. Thecurves for these are included in Figure 9.

FIG. 9. RED BLOODCELL COUNTAND SERUMSPECIFICGRAVITY CHANGESIN 2 DOGS

Both the red count and specific gravity increase abruptlyto almost their maximum values 10 minutes after removalof the press.

On the basis of these results, it seems that arise in erythrocyte fragility is also fairly charac-teristic of the shock state, and to a certain extentthe degree of rise is a measure of the severityof the shock condition.

DISCUSSION

It is striking that such a narrow temperaturerange (120 C.) seems to make the actual differ-ence between life and death for the dog in shockas a result of a crush injury. Survival is almostalways possible in a room temperature of 160 C.,and the standard crush injury is almost uni-formly fatal at a room temperature of 280 C.

136


The experiments controlling the room tempera-ture were done during the winter months, atWhich time the room temperature could beregulated easily without elaborate arrangements.There was no control, however, over the humid-ity which was relatively low. Whether humid-ity might also play a controlling r6le in theregulation of the body temperature at a givenenvironmental temperature could not be de-termined. No optimum was found at 240 C.,such as has been reported (2) for burns.

The body temperatures grossly tend to followthe trend of the environmental temperaturesand, on an average, the body temperaturesfurnish an indication as to the final course ofevents. The average rectal temperature inthose dogs that were injured in a room tempera-ture of 280 C. was, just before removal of thepress, some 1.70 C. above that of dogs injuredin a room temperature of 160 C. After removalof the press, the difference in rectal temperaturewas not as marked since the body temperatureof the dogs done at low room temperatures roseat this time. Anesthesia may play some partin this situation because the resulting peripheralvascular dilatation may enable the environ-mental temperature to affect the heat losses orgains during the critical period more directlythan might be the case in the unanesthetizedanimal.

It should be stressed that the changes in rectaltemperature which seem to be indicative ofwhether the animal will survive or not are rela-tively small. Furthermore, fluctuations over anarrow range of temperature during the criticalperiod may make the difference between life anddeath. This does not mean that the body tem-peratures found are lethal per se, but that thesesmall differences are either the symptoms of orthe causes of significant changes in other condi-tions or processes which have not been fullyidentified as yet.

At the high room temperatures, the mortalityrate approximates 100 per cent; at the low roomtemperatures, the mortality rate approacheszero. Not only is the room temperature whilethe dog is in shock of importance, but the tem-perature while the injury is being produced isalso of prime importance. This is demonstratedby the experiments in which the dog was changed

from one room temperature to another upontermination of the crushing period. In theseexperiments, the chances of its survival are in-creased by moving the animal from a room ofhigh temperature to a lower temperature uponremoval of the press, and decreased by movingfrom a low temperature to a higher one, but notto the degree predicted if the animals had beenkept at the second temperature for the wholeperiod.

The practical applications of this finding tooperating room temperatures are obvious. Aprocedure which carries with it a high incidenceof surgical shock might be performed moresafely if the body temperature of the patient isnot allowed to rise, or if it is even lowered slightly.This is accomplished most easily by keeping theoperating room temperature down, and byavoiding too much insulation or too manycovers on the patient. The avoidance of heat inpost-operative care must also be stressed. Itis obvious from our experiments that the applica-tion of heat, in the case of the dog, is one of themost certain methods of precipitating a fataloutcome with circulatory collapse.

In the absence of means of lowering environ-mental temperatures, under military conditionsor in emergencies, the local applications of ice,if complete enough, may serve to save the shockpatient with a traumatic injury. However, asshown in the dog experiments, toxemia is likelyto develop if the chilling is not continued for aperiod far in excess of that during which shockitself is usually a factor. Furthermore, skinsloughing, other necrotic changes, and a highincidence of intrinsic and spontaneous infection(gas gangrene) were found in the unsterileexperiments with limbs invested in wet ice-bagsfor long periods (4 days).

The mechanism underlying the erythrocytefragility changes which we have described is atpresent unknown. It is unlikely that it is dueto stasis of blood in the traumatized extremitysince the first blood coming from the femoralvein at removal of a tourniquet in place for 5hours failed to show any fragility change fromthe control. The erythrocyte fragility riseoccurring with blackwater fever has been at-tributed to a decrease in the pH of the blood(19). It is questionable whether the degree of

137


pH produced by the mild acidosis during shock isenough to bring about these fragility changes.

In the dogs succumbing to acute peripheralcirculatory failure, there is extensive tubularepithelial degeneration in the kidneys, and evi-dence of degeneration of the cells adjacent tothe central veins in the liver. The kidney dam-age occurred in 100 per cent of the fatal cases,and has been found as early as 3 hours followingremoval of the press. The increasing bloodNPN, the increased urinary protein, and thecurtailed urinary output all confirm the kidneydamage seen in sections. There is a possibilitythat not all the NPN is a reflection of kidneydamage. It has been suggested (20, 21) that theazotemia in burn shock may be due in part topolypeptide nitrogen. This also may be thecase in our experiments since large amounts ofmuscle are crushed.

The characteristics most quickly showingshock changes, in our experiments, are the bloodNPN, red cell fragility, hematocrit, red cellcounts, and serum specific gravity (serum pro-tein). The NPNchanges are to a large extentprobably indicative of the kidney injury alreadydiscussed. The hematocrit rise and increasedserum protein concentration are a reflection ofthe hemoconcentration caused by loss of fluidinto the traumatized limb (see second paper inthis series).

If one is looking for early clinical evidence ofperipheral circulatory failure, parallel to or assubstitute for blood pressure determinations, oris looking for a clue to causative factors in thevicious circle that develops, they should be soughtfirst in the above group of characteristics.Deep peripheral muscle temperatures yield thefirst tangible evidence, but thermocouples forsuch measurements are not readily available.Skin temperatures are not always a true reflec-tion of the situation beneath.

The optimum point in temperature effect uponburn shock as reported (2) may be peculiar tothe complicated situation in the severe burnshock used in those experiments. The optimalpoint "in the neighborhood of mammalian bodytemperature" in shock (3) is probably influencedby the particular methods of temperature con-trol used by these authors. Their results withtemperatures in the vicinity of freezing are com-

parable to ours with the local application of ice-bags. Apparently, the toxic condition developsmore slowly under the action of ice. Animalstreated at 160 C., without ice, show a much lesscomplicated reaction after the initial 24 hours.In the case of refrigeration anesthesia, when usedin conjunction with a tourniquet, with amputa-tion as the end in view, such toxicity is of noimportance.

SUMMARY

For the standardized experimental productionof traumatic shock, the modified Blalock pressmay be used, if the over-all pressure and theenvironmental temperature are controlled.

(1) The pressures used must be sufficientlygreat to assure occlusion of all major blood ves-sels leading into the extremity.

(2) With the lower lethal pressures (1500 to2000 pounds), there is little or no hemorrhage tocomplicate the picture; with higher pressures(3000 pounds or over), hemorrhage into thetissues can be produced as desired.

(3) Using a standard pressure of 2000 pounds,low environmental temperatures (160 C.) affordedalmost complete protection from death. Toproduce death uniformly, room temperatures of280 C. were necessary. Intermediate tempera-tures produced intermediate mortality rates.

(4) Alteration of the temperature followingproduction of the injury exerts an incompleteeffect as compared with constant exposure to thesubsequent room temperature.

(5) With a high environmental temperature,local application of ice to the injured limb affordsalmost complete protection from death.

(6) Both physiological and morphologicalkidney damage of a temporary nature followcrushing injury within a very short span of time.

(7) Gastrointestinal submucosal hemorrhagesand subendocardial hemorrhages are very com-mon pathological findings. Less frequently,degeneration of the central liver lobule cells isfound.

(8) The blood chemistry changes are mainlythose associated with hemoconcentration andrenal damage (rising hematocrit and red count,rising non-protein nitrogen, serum protein, andserum specific gravity).

138


(9) A hitherto unreported rise in the fragilityof the red cells is also noted, apparently varyingin extent with the severity of shock.

(10) Serum specific gravity can be employedto determine serum protein concentration, butplasma specific gravity in the presence of a

rising hematocrit and using potassium oxalateas anticoagulant is not a reliable index of theprotein concentration.

CONCLUSION

In order to obtain a reproducible standardizedshock experiment with the Blalock type ofcrusher, it is necessary to use over-all pressure of2000 pounds for 5 hours on one complete upper

thigh under Nembutal anesthesia with the room

temperature at 280 C. or above.Any variation in these several stipulations

may change the picture enough to prevent theonset of fatal shock.

Wewish to acknowledge the loyal, untiring and coopera-tive participation of the technical group who made theseprotracted experiments possible: George Casarett, BettyMulryan, Marion Wesley, John Thomas, Jerry Biondi,Marlene Falkenheim, Edward Mulligan, and ElizabethVittum. We also wish to acknowledge the technicaladvice of Mr. Francis Bishop on equipment.

BIBLIOGRAPHY

1. Blalock, A., Principles of Surgical Care, Shock andOther Problems. C. V.- Mosby Co., St. Louis, 1940.

2. Moon, V. H., Shock: Its Dynamics, Occurrence andManagement. Lea and Febiger, Philadelphia,1942.

3. Wiggers, C. J., The present status of the shockproblem. Physiol. Rev., 1942, 22, 74.

4. Blalock, A., and Duncan, G. W., Traumatic shock-A consideration of several types of injuries. Surg.,Gynec. and Obst., 1942, 75, 401.

5. Elman, R., Cox, W. M., Jr., Lischer, C. E., andMueller, A. J., Mortality in severe experimentalburns as affected by environmental temperature.Proc. Soc. Exper. Biol. and Med., 1942, 51, 350.

6. Wakim, K. G., and Gatch, W. D., The effect ofexternal temperature on shock. J.A.M.A., 1943,121, 903.

7. Blalock, A., and Mason, M. F., A comparison of theeffects of heat and those of cold in the preventionand treatment of shock. Arch. Surg., 1941, 42,1054.

8. Cullen, G. E., and Van Slyke, D. D., Determinationof the fibrin, globulin, and albumin nitrogen ofblood plasma. J. Biol. Chem., 1920, 41, 587.

9. Koch, F. C., and McMeekin, T. A new directnesslerization micro-Kjeldahl method and a modifi-cation of the Nessler-Folin reagent for ammonia.J. Am. Chem. Soc., 1924, 46, 2066.

10. Karr, W. G., A method for the determination of bloodurea nitrogen. J. Lab. and Clin. Med., 1924, 9, 329.

11. Folin, O., and Wu, H., A system of blood analysis.J. Biol. Chem., 1919, 38, 81.

12. Brown, H. R., Jr., and Clark, W. F., Plasma specificgravity and control of fluid administration inartificial fever. Proc. Soc. Exper. Biol. and Med.,1939, 40, 490.

13. Allen, F. M., Physical and toxic factors in shock.Arch. Surg., 1939, 38, 155.

14. Swingle, W. W., Remington, J. W., Kleinberg, W.,Drill, V. A., and Eversole, W. J., An experimentalstudy of the tourniquet as a method for inducingcirculatory failure in the dog. Am. J. Physiol.,1942, 138, 156.

15. Lewis, R. N., and Nickerson, N. D., Prolongedadrenalin hypertension and subsequent circulatoryfailure. Proc. Soc. Exper. Biol. and Med., 1942,51, 389.

16. Foster, D. P., and Whipple, G. H., Blood fibrinstudies: fibrin values influenced by cell injury,inflammation, intoxication, liver injury and theEck fistula. Am. J. Physiol., 1922, 58, 407.

17. Mylon, E., Winternitz, M. C., Katzenstein, R., andde Siuto-Nagy, G. J., Studies on mechanisms in-volved in shock. Am. J. Physiol., 1942, 137, 280.

18. Moore, N. S., and Van Slyke, D. D., The relationshipsbetween plasma specific gravity, plasma proteincontent and edema in nephritis. J. Clin. Invest.,1930, 8, 337.

19. Smith, F., and Evans, R. W., Effect of the pH of theblood on haemolysis, with special reference toblackwater fever. Brit. M. J., 1943, 1, 279.

20. Duval, P., Roux, J. C., and Goiffon, R., Essai surl'intoxication par les polypeptides. Presse m6d.,1934, 42, 1785.

21. Lambret, O., Driessens, J., and Malatray, H., Dimi-nution, sous l'action de l'insuline seule ou associ6edu glucose, de l'hyperpolypeptid6mie secondaireaux destructions cellulaires. Compt. rend. Soc. debiol., 1936, 123, 12.

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environmental 1 · r. a. ricca, k. fink, l. i. katzin, and s. l. warren following determinations...

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