CHAPTER VII
Timelag and the Multiplicity Factor in Abdominal Injuries
Luther H. Wolff, M. D., W. Philip Giddings, M. D.,
Samuel B. Childs, M. D., and Clarence R. Brott, M. D.
At the beginning of World War II, as in previous wars, it wasa universally accepted concept that the length of the timelag (the interval fromwounding until the institution of therapy) had an important influence on thecase fatality rate in abdominal wounds. On the surface, this is a perfectlyreasonable point of view. Hemorrhage, peritoneal contamination, and disturbancesof cardiorespiratory and gastrointestinal physiology combine to produce a stateof shock following wounding. The longer these conditions are permitted tocontinue uncorrected, the more severe does the shock become, the more serious isthe deterioration of the wounded man's status, and, presumably, the graver isthe prognosis.
It was with full acceptance of this concept that the analysiswas undertaken of the 2,926 abdominal injuries in this series in which dataconcerning the timelag were available. The average interval from wounding tooperation was found to be almost 10.5 hours, the two components being,respectively, 6.5 hours for the period from injury to hospitalization and 3.9hours for the period from hospitalization to operation. The chief obstacle toearlier hospitalization lay in the obvious difficulties in evacuating casualtiesfrom the battlefield. The delay in the hospital was more apparent than real; itwas explained by the time consumed in necessary preoperative resuscitation,particularly of poor-risk patients. A further explanation, in times of stress,was the overburdening of available surgical facilities, which resulted in aninevitable prolongation of the timelag.
All through the war, every possible effort was directedtoward shortening the timelag, in line with the belief that the earlieroperation could be performed, the better would be the results, and vice versa.As the result of these efforts, and as the experience of military personnelincreased and evacuation facilities were improved, a substantial reduction inthe average timelag was achieved. In 1944, it was 11.4 hours (6.9 hours betweenwounding and hospitalization and 4.5 hours between hospitalization andoperation). In 1945, it was reduced to 9.5 hours (6.1 hours between wounding andhospitalization and 3.4 hours between hospitalization and operation).
In view of these facts, it was therefore disconcerting, when this analysiswas conducted after the war, to find that the figures furnished little supportfor the concept that the length of the timelag had an important influence on thecase fatality rates. When they were calculated in 2-hour periods (fig. 20), no
104
consistent change in them was observed with the passage oftime. Obviously it was necessary to seek an explanation for the paradox that anincrease in the timelag did not greatly increase the case fatality rate, while ashortening of the interval did not greatly improve it.
When the abdominal wounds in the series were evaluated in terms of theirseverity, the apparent paradox was promptly resolved. An analysis from thispoint of view showed that wounds of the same viscus differed from casualty tocasualty in respect to their extent, the degree of associated hemorrhage, theamount of peritoneal contamination, and the specific effect of the wound upon
105
the individual. On the other hand, in spite of their evidentimportance, these considerations could not be reduced to statistical form. Fromthese standpoints, each case was an entity in an exclusive category.
As a practical solution of the problem, therefore, theseabdominal injuries were classified from the standpoint of severity in terms ofthe number of visceral injuries each individual casualty had sustained. Whenthis had been done, it immediately became clear that whether or not patients whohad sustained the greatest number of visceral injuries (and who, presumably,were the most severely wounded) were to live or die did indeed depend in largemeasure upon the time elapsed between wounding and the institution of surgicalcare. The most severely wounded patients, in terms of multiplicity of injuries,survived only if they were operated on promptly, and the case fatality rateincreased progressively from category to category as the timelag increased(table 9). It was 100 percent in the categories in which the largest number ofwounds was associated with the longest timelag. There were no survivals amongthe 6 casualties who suffered 6 visceral injuries each, although 5 of the 6 wereoperated on within 16 hours of wounding, and there were only 2 survivals amongthe 22 patients with 5 visceral injuries each, although 20 of the 22 were alsooperated on within 16 hours of wounding. It is true that in some of thecategories the numbers of cases were so small as to be without statisticalsignificance, but in general the figures corroborated the clinical impressionthat the least severely wounded man could tolerate a certain prolongation of thetimelag, while the most severely wounded men could not. Some wounds werepotentially lethal, regardless of the brevity of the timelag, while others werenot necessarily lethal originally but tended to become so as the timelagincreased.
The truth of the assumption that the case fatality rate increases as thetimelag lengthens was generally acceptable for the individual patient, though atthe extremes of time there were balancing factors which effectively precludedits demonstration. Many of the fatalities in the first hours after injuryoccurred in mortally wounded men, who were given priority of treatment in whatproved a vain attempt to save their lives. These deaths elevated the casefatality rates for the early hours. At the other extreme of time, patients whosurvived after 18 to 24 hours without operation might well have lived withouttreatment; no one would contend that all abdominal wounds are fatal withoutsurgery.
Examination of the multiplicity indexes (table 9) confirmsthese generalizations. They are, respectively, 1.64, 1.59, 1.45, 1.41, and 1.13.By these criteria, the most severely wounded patients obviously were operated onin the first 8-hour interval, and the least severely wounded were operated onafter 24 hours. The figures thus afford statistical confirmation of a recognizedclinical observation; namely, the case fatality rate in casualties operated onearly was elevated by the inclusion in this category of a relatively largenumber of the most critically wounded casualties, while the rate among thosecoming to surgery late was kept below expected levels by the inclusion of asimilar proportion of the less seriously wounded.
106
Organs injured | Timelag (wounding to operation, in hours) | ||||||||||||||
0 through 8 | 9 through 16 | 17 through 24 | 25 through 36 | 37 to 90 | |||||||||||
Cases | Deaths | Case fatality rate | Cases | Deaths | Case fatality rate | Cases | Deaths | Case fatality rate | Cases | Deaths | Case fatality rate | Cases | Deaths | Case fatality rate | |
None | 98 | 5 | 5.1 | 116 | 9 | 7.8 | 34 | 3 | 8.8 | 20 | 3 | 15.0 | 11 | 2 | 18.2 |
One | 496 | 50 | 10.1 | 519 | 77 | 14.8 | 145 | 24 | 16.6 | 72 | 19 | 26.4 | 36 | 12 | 33.3 |
Two | 402 | 97 | 24.1 | 391 | 112 | 28.6 | 103 | 32 | 31.1 | 37 | 11 | 29.7 | 13 | 8 | 61.5 |
Three | 132 | 56 | 42.4 | 144 | 67 | 46.5 | 24 | 12 | 50.0 | 14 | 7 | 50.0 | 3 | 1 | 33.3 |
Four | 41 | 22 | 53.7 | 38 | 25 | 65.8 | 7 | 6 | 85.7 | 2 | 1 | 50.0 | 0 | 0 | --- |
Five | 13 | 12 | 92.3 | 7 | 6 | 85.7 | 1 | 1 | 100.0 | 1 | 1 | 100.0 | 0 | 0 | --- |
Six | 3 | 3 | 100.0 | 2 | 2 | 100.0 | 0 | 0 | --- | 1 | 1 | 100.0 | 0 | 0 | --- |
Total | 1,185 | 245 | 20.7 | 1,217 | 298 | 24.5 | 314 | 78 | 24.8 | 147 | 43 | 29.3 | 63 | 23 | 36.5 |
Multiplicity index | 1.64 | 1.59 | 1.45 | 1.41 | 1.13 | ||||||||||
107
MULTIPLICITY FACTOR
Since the importance of the multiplicity of visceral injuries was an entirelynew concept in military surgery, a new nomenclature had to be devised for it.The terms "multiplicity factor" and "multiplicity index"were accordingly introduced. Multiplicity factor was employed to designate thenumber of abdominal organs injured in any given patient, as determined atoperation or autopsy. Multiplicity index was employed to indicate the aggregateseverity of the individual cases in a given series of abdominal wounds. It wasobtained by dividing the total number of organs injured in the series by thenumber of cases which made up the series.
In the interests of clarity, certain explanations arenecessary in regard to this nomenclature. Multiplicity factor does not implyselectivity of viscera. Combinations are limited entirely to numericalincidence. Only the number of organs injured matters. Nor does the term carryany implications concerning the total number of wounds sustained in a givencase, since multiple wounds of the same viscus are counted as a single wound.Thus, wounds of the cecum, transverse colon, and sigmoid colon in the samepatient would be counted as a single wound of the large bowel, and wounds of thejejunum and ileum would be counted as a single wound of the small bowel.
In this analysis, wounds of the major abdominal blood vessels (asdistinguished from wounds of the visceral blood supply) are not regarded asvisceral injuries. It is evident, however, that the multiplicity factor is justas valid in them as it is in other abdominal injuries (p. 323), the onlydifference being that the case fatality rates for vascular injuries begin at amuch higher level.
It should be emphasized again that the concept of the multiplicity factor wasa postwar development. It was evolved only when it became evident thatthe timelag, upon which the major emphasis had been placed in the past,apparently did not play the role in the case fatality rate in abdominal injurieswhich it was formerly supposed to play. When the multiplicity factor was adoptedas a yardstick in the analysis, much that had been contradictory and confusingwhen the timelag alone was used as a point of reference was immediatelyclarified. It now became clear that, when only the timelag was analyzed,dissimilar cases were being compared with each other and that the analysis ofthis type of trauma would be valid only when the cases were separated intocomparable and exclusive categories.
When the injuries in which sufficient data for this purposewere available were categorized according to the multiplicity factor (tables 9and 10, figs. 21 and 22), the timelag fell into the proper perspective, the casefatality rate was found to ascend in almost arithmetical progression with eachadditional viscus injured, and the increase was almost as constant for eachspecial organ as it was for the entire series.
108
109
TABLE 10.-Influenceof multiplicity factor on case fatality rates in wounds of various viscera
Organs injured | Cases | Deaths | Case fatality rate |
Stomach:1 |
|
|
|
| Alone | 42 | 12 | 28.6 |
| With 1 other viscus | 174 | 47 | 27.0 |
| With 2 other viscera | 112 | 44 | 39.3 |
| With 3 other viscera | 50 | 29 | 58.0 |
| With 4 other viscera | 23 | 23 | 100.0 |
| 401 | 155 | 38.7 |
Liver: |
|
|
|
| Alone | 339 | 33 | 9.7 |
| With 1 other viscus | 238 | 63 | 26.5 |
| With 2 other viscera | 151 | 60 | 39.7 |
| With 3 other viscera | 62 | 35 | 56.5 |
| With 4 (and more) other viscera | 39 | 33 | 84.6 |
| 829 | 224 | 27.0 |
Kidney: |
|
|
|
| Alone | 56 | 9 | 16.1 |
| With 1 other viscus | 172 | 41 | 23.8 |
| With 2 other viscera | 105 | 38 | 36.2 |
| With 3 other viscera | 47 | 30 | 63.8 |
| With 4 other viscera | 24 | 19 | 79.2 |
| 404 | 137 | 33.9 |
1There are omitted from this category 15 cases inwhich wounds of the stomach and one or more other viscera were complicated bywounds of the great vessels.
The multiplicity factor also proved a valuable aid in the appraisal ofabdominal injuries from a number of other points of view:
1. Associated injuries.-An analysis of the 1,089cases in which abdominal wounds were associated with extra-abdominal wounds (p.114) revealed that moderately severe extra-abdominal injuries were oftenassociated with abdominal wounds of high multiplicity and that the reverse wasalso true, severe extra-abdominal injuries usually being associated withabdominal injuries of low multiplicity. The statistics suggested that whensevere extra-abdominal injuries were associated with abdominal injuries of highmultiplicity, the wounded men seldom survived to reach the hospital.
2. Shock.-Virtually every one of the deaths which occurred in thisseries within the first 24 hours after operation was attributable to shock,which developed as the result of hemorrhage, peritoneal contamination, or tissuedestruction. As might have been expected, a definite association was found toexist between the multiplicity factor and these deaths. In the 756 fatalities inthe whole series, 35 percent of the deaths in univisceral wounds occurred within24
110
hours of operation, as did 36 percent of the deaths in which2 organs were injured, 40 percent of the deaths in which 3 organs were injured,and 51 percent of the deaths in which 4 or more organs were injured.
3. Pulmonary complications.-The incidence ofpostoperative pulmonary complications (p. 204) rose from 6.5 percent inunivisceral injuries to 13.0 percent when 5 or more viscera were injured. Thisobservation is of clinical rather than statistical significance. The moreseverely wounded patients were more apt to develop stagnation of thetracheobronchial secretions and therefore presented a higher incidence ofatelectasis and bronchopneumonia.
4. Variations in case fatality rates.-One of the perplexing featuresof this analysis before the concept of the multiplicity factor was evolved wasthe differences between the case fatality rates of surgeons of equal ability andexperience. Another was the differences between the rates of more forward(field) hospitals and evacuation hospitals. These differences had been realizedin the course of the war. They could not reasonably be explained on the basis ofsuperior or inferior surgical performance, or merely as matters of chance. Itwas the general impression that less severely wounded patients were treated atevacuation hospitals, but proof of the impression was lacking until this serieswas analyzed on the basis of the multiplicity factor. When the severity of thewounds was taken into consideration, differences in the case fatality rates ofhospitals in different echelons (table 5, p. 89) could easily be explained. Ahigh rate was to be expected in field hospitals, because the most severelywounded patients were treated in them.
A single comparison will make this point clear. The case fatality rate for232 casualties treated by surgeons of the 2d Auxiliary Surgical Group inevacuation hospitals was 15.1 percent, while the rate for surgeons of the samegroup for 2,851 casualties treated in field hospitals was 24.3 percent.Differences in the multiplicity indexes explain the differences in the casefatality rates. The index for the casualties treated in evacuation hospitals was1.10, while for casualties treated in field hospitals it was 1.70. Likewise,differences in the multiplicity indexes explain differences in the case fatalityrates of surgical teams of similar ability and experience.
Team |
| Case fatality rate |
A | 1.42 | 21 |
B | 1.58 | 23 |
C | 1.63 | 25 |
D | 1.71 | 25 |
E | 1.73 | 27 |
F | 1.80 | 28 |
Application of the multiplicity index to certain recorded series of abdominalinjuries permitted comparison of them by a uniform standard of evaluation (table11). An examination of the Welch and Tuhy1 series, the Ogilvie(Western Desert)2 series, and thematerial of the 2d Auxiliary Surgical Group
1Welch, C. S.; and Tuhy, J. E.: Combined Injuries of the Thorax and Abdomen. Ann. Surg. 122: 358-374, September 1945.
2Ogilvie, W. H.: Abdominal Wounds in the Western Desert. Surg., Gynec. & Obst. 78: 225-238, March 1944.
111
shows the correlation which might be expected between theWelch and Tuhy figures and those of the 2d Auxiliary Surgical Group. In theBritish material, on the other hand, although the multiplicity index was lowerthan in either of the other series, the case fatality rate was higher. Thediscrepancy can probably be explained by two factors: (1) That conditions ofevacuation and hospitalization were frequently extremely unfavorable in thefighting in the Western Desert, and (2) that penicillin was not available whenthese cases were treated as it was for the patients in the other (later) series.
Organs injured | Welch and Tuhy series | British World War II series1 | 2d Auxiliary Surgical Group series | |||
Cases | Case fatality rate | Cases | Case fatality rate | Cases | Case fatality rate | |
None | 5 | 20.0 | 42 | 23.8 | 292 | 7.5 |
One | 44 | 11.3 | 164 | 31.1 | 1,348 | 14.9 |
Two | 17 | 29.4 | 31 | 48.4 | 1,014 | 28.1 |
Three | 3 | 33.3 | 27 | 71.3 | 350 | 46.3 |
Four | 1 | --- | --- | --- | 96 | 61.5 |
Five | --- | --- | --- | --- | 23 | 91.3 |
Six | --- | --- | --- | --- | 6 | 100.0 |
| 70 | 17.1 | 244 | 33.2 | 3,129 | 24.2 |
Multiplicity index | 1.30 | 1.02 | 1.58 | |||
1Western Desert (second series, 244 cases; 3 deathson the operating table are excluded from the figures).
2In this category are included all injuries of 3 or more organs.
LIMITATIONS OF THE MULTIPLICITY FACTOR
In this series of abdominal injuries, the application of the multiplicityfactor clarified much that had originally been confusing and actuallyinexplicable. On the other hand, while it proved to be of a valuable statisticaltype for series analysis, it was found to have certain weaknesses andlimitations, because of relative dispersion, when it was applied to individualcases. Another reason was that it was entirely possible for a wound of a singleviscus to be so grave that the intra-abdominal damage was as serious as it wasin another case in which three or even more organs were wounded. Thus themultiplicity factor was found to be not completely reliable in wounds of thestomach (table 10, fig. 22). In injuries of this organ, the case fatality ratefor univisceral wounds was slightly higher than for gastric wounds complicatedby a wound of one other viscus. The explanation is the inherent gravity of allwounds of
112
the stomach, which were likely to be associated with acute precipitouschemical peritonitis (p. 231). For this reason, the case fatality rate inunivisceral gastric wounds was unusually high as compared with the rates forunivisceral wounds of other organs.
On the surface, it might seem that the multiplicity factor should be usefulin prognosis, making it possible to predict the outcome for the individualcasualty with a reasonable degree of accuracy. In general (fig. 21), the casefatality rate increased about 15 percent as each additional viscus was injured,and, generally speaking, the number of viscera injured was more significant thanthe particular organ involved. These generalizations, however, do not hold forthe individual case, in which the multiplicity factor must be used with greatcaution. For one thing, in a case in which only one or two viscera are injured,an unusually prolonged timelag might make the prognosis more serious than themultiplicity factor alone would indicate. For another, the presence of seriousassociated extra-abdominal injuries, the development of anaerobic and otherinfections, unforeseen complications such as intestinal obstruction and wounddehiscence, and other considerations of the same sort might completely vitiatethe multiplicity factor in the individual case.
Notwithstanding the variations and limitations of the multiplicity factor inits application to individual cases, when it was applied to this particularseries-in which many variables existed-it supplied an accurate and usefulyardstick for many different purposes and resolved at once the apparent paradoxwhich had existed when the case fatality rates were calculated only in referenceto the timelag.
