Hydraulic vicious circle as it develops in the intestine

HYDRAULIC VICIOUS CIRCLE AS IT DEVELOPS IN THE INTESTINE EFFECT OF INTRAINTESTINAL PRESSURE ON THE PATHOLOGY AND PHYSIOLOGY OF THE BOWEL* C. VAN ZWALENBURG, M.D., F.A.C.S. RIVERSIDE, CALIF.

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intestine promptIy becomes the site of a hvdrauIic A A vicious circIe, and the thin” waI1 of the intestine with its poorIy protected circulation makes it particuIarIy vuInerabIe to its stranguIating effects. The term “StranguIation” has aIways carried with it the suggestion of bIood stasis in the intestine, and it is there that it has been most frequentIy studied and discussed. In stranguIated hernia, hydrauIic vicious circIe is a very prominent factor. It Js the basis of most of the pathology in the Ioop of obstructed bowe1 and is the cause of the rapid production of gangrene which Ied surgeons, fifty years ago, to say, “Never allow the sun to set on a stranguIated hernia. ” In fact, the whoIe pathoIogy in a (stranguIated) Ioop of intestine, whether from a hernia or other mechanica cause, is due to the mechanics of hydrauIic vicious circIe. The initia1 pressure upon the neck of the hernia1 sac is very seIdom sufficient to stop immediateIy a11 circuIation into the contents of the sac. Often pain does not deveIop in a retained hernia1 Ioop unti1 several hours after the patient fmds himseIf unabIe to return it to the abdomen. During this period, the constriction at the ring is not suflicient to produce stranguIation. It is, however, tight enough to obstruct the ffow of the intestinai contents. The peristaItic action above forces in&stina contents into the Ioop, but the constriction is so snug that it cannot pass out of it. Thus intestina1 contents accumuIate within the Ioop unti1 the pressure estabIishes a hydrauIic vicious circIe, with a11 its consequences.

Once this vicious circIe is estabIished, it proceeds exactIy as in abscess, and in appendicitis. The materia1 in the Ioop increases, the effusion increases, and the pressure rises unti1 the circuIation in the waIIs of the intestine is entireIy obstructed, and compIete stranguIation resuIts. The thin waI1 of the intestine offers IittIe resistance to the cIosure of these bIood vesseIs. In abscess, where there are no definite waIIs, the progress of stranguIation is sIow; and the waIIs of the appendix, being thicker, offer much more resistance to the pressure of the accumuIating fluid. In the smaI1 intestine, on the other hand, the bIood vesseIs having IittIe to support them coIIapse very quickIy. Any gas which may be present in the Ioop is quickIy forced out into the circuIation and carried off by the Iungs. The effusion aIways found in the sac of a stranguIated hernia is evidence of the pressure upon the waIIs of the intestine and upon its capiIIaries, with resuIting effusion, from both the outside and inside of the gut. This accounts for the fluid aIways present in the sac of a stranguIated hernia. Bacteria, by their constant presence in the intestine, pIay the same roIe as in the appendix. There is congestion, Iack of the presence of anaerobes and oxygen, facuItative anaerobes, and infection is very prompt and progresses very rapidly. The mechanics of obstruction of the intestine in other conditions than hernia is practicaIIy the same. When caught under a band of peritoneum it is identica1. VoIvuIus wiI1 often produce aImost compIete stranguIation in the same manner. Intussusception has some varying symptoms

* Submittedfor pubIicationDecember17, 1931. 104

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according to the portion of the ahmentary cana invoIved, but the underIying causes are the same, hydrauIic vicious circIe, and the resuIts are the same, a graduaIIy deveIoping gangrene. When an intestina1 obstruction deveIops without producing a Ioop, as from a band, the hydrauIic vicious circIe is onIy partiaIIy deveIoped, depending upon the amount of intestine above the obstruction. There wiI1 aIways be more or Iess interference with the circuIation, but if the obstruction is near the stomach, regurgitation wiI1 promptIy reIieve the distention, so that there is but IittIe direct interference with the circuIation. For this reason an obstruction in the duodenum wiI1 produce copious vomiting, with rapid dehydration of the body; the secretions from the pancreas and Iiver add enormousIy to the pouring out of fluid into the intestine, a11 being expeIIed by vomiting. But there is Iess evidence of stranguIation here. If this obstruction is low down in the smaI1 intestine, the Iong aIimentary tube through which the antiperistaIsis must work faiIs to reIieve the intraintestina1 pressure, and enough pressure wiI1 eventuaIIy be produced to cause necrosis and gangrene by the pressure of the distention itseIf shutting off the circulation. In every case of intestina1 obstruction, interference with the circuIation is the most important factor. Whether the toxic symptoms be due to the formation of actua1 toxins (WhippIe, Morton, etc.), or whether they are dependent upon dehydration and depIetion of the chIorides, or both, the principal factor in the impending tragedy is the interference with the blood suppIy through the establishment of a hydrauIic vicious circIe. The interference with the circuIation aids in producing dehydration by effusion into the intestine above the obstruction and together with infection produces necrosis and gangrene which is fohowed by rupture and peritonitis. Peritonitis foIIowing rupture is of course the common cause of death in intestinal obstruction.

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Many workers at. various times have referred to the obvious disturbance of the circulation and consequent impairment of function occurring in the waIIs of the hoIIow viscera as the resuIt of distention from increased intraviscera1 pressure. ParticuIarIy with reference to the intestine and appendix there have appeared during the past few years a number of papers dealing rather specificaIIy with various phases of this probIem. It seems, therefore, appropriate to review this subject in an attempt to correIate the various data obtained with reference to the cIinica1 conditions in which such intraviscera1 pressure may be signihcant. In rgo7,l I made a number of observations on the bIood ffow in the bowe1 waI1 as affected by varying pressures by means of a Iight within the Iumen of the smaI1 intestine. It was observed that with distention of the intestine by a pressure of 30 mm. of mercury some capiIIary streams were arrested; at 60 mm., smaI1 veins were arrested, and in most veins the current was sIow; at go mm., a11 bIood streams were moving sIowIy, and many, but not aII, currents were changing direction frequently; at I30 mm. pressure a11circuIation ceased, and there was some osciIIation of corpuscles but no progress. The fohowing concIusion was made at that time: The demonstration seems compIete that distention of the gut (or of other hoIIow viscera) interfers with the circuIation in its waI1, and aIIows infiItration and effusion to take pIace into its waIIs and Iumen and any other open spaces which may come within its influence. The return circuIation is retarded at comparativeIy sIight pressures. Effusion foIIows, as in a11obstructions to venous Aow. As the average venous pressure in the intestine under ordinary circumstances probabIy varies from 4 to IO mm. of mercury, any pressure beyond that wiI1 offer some resistance to the return current. In 1926, Van Beurens studied the pathologic changes occurring in distended Ioops of bowe1 and found that the characteristic

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features were areas of hemorrhagic infarction on the antimesenteric surface of the intestine, with varying degrees of necrosis to perforation occurring in these areas depending on the duration of the distention. He stated: The mechanism of this infarction appears to be as foIIows: Distention of the intestine increases its diameter. Any increase in its diameter is tripIed in its circumferentia1 measurement. In other words, if the diameter of an intestine is increased by distention from I cm. to 3 cm., its circumference is at the same time increased from 3 cm. to g cm. Thus, the difference in the diameter is onIy z cm., whiIe the difference in the circumference is 6 cm. A moderate increase in diameter, therefore, resuIts in considerabIe stretching of the waI1. The intestina1 vesseIs pass between the Iayers of the waI1 aIong its circumference from their origin at the mesenteric border to their termina1 anastomoses at the antimesenteric surface, becoming progressiveIy more thin-walled and more narrow of Iumen. Because they are eIastic the stretching of the intestina1 wal1 from distention stiI1 further thins the vesse1 waIIs and narrows the. vesseI’s Iumen Iike a stretched rubber tube. At the same time the pressure from within the intestine tends to flatten out the vessel’s Iumen. The narrowing of the vesseI’s Iumen and the thinning of the vascuIar waI1 are maximum at the antimesenteric surface of the intestine where the termina1 anastomoses occurs; and, the distention pressure being constant throughout the Iumen of the intestine, the maximum effect is seen at the antimesenteric surface where a union of the three factors of pressure, thin waI1 and narrow Iumen finaIIy resuIts in obliteration of the vesse1. This obIiteration occurs sooner in the vein than in the artery on account of the Iess resistant waI1. The bIood continues to pour through the arteria1 vesse1 unti1 the pressure against the obIiterated vein sufEces to rupture the vesse1 waII and permit extravasation and coaguIation. FinaIIy, the pressure occIudes the artery as we11 as the vein. The area of tissue suppIied by these termina1 vessels is thus deprived of circuIating bIood and necrosis occurs. This necrosis is usuaIIy first evident in the submucosa and inner muscuIar coat, but rapidIy extends to the other coats of the intestina1 waI1, and perforation may occur

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within twenty-four hours after the discoIoration due to the hemorrhagic infarct has been first noticed.

In 1927, Gatch, TrusIer and Ayers3 studied the effect of intestina1 distention on the circuIation of the bowel by recording the effect of such distention on the rate of bIood ffow in the returning veins. Their observations in general were confirmatory of Van ZwaIenburg’s, but in addition, afforded an estimate of the degree of circuIatory impairment at different IeveIs of pressure. They showed that the bIood ffow through the bowe1 waI1 decreases as the distention increases, and ceases when the pressure within the bowe1 equaIs the systoIic bIood pressure. This resuIt has been confirmed and ampIified by Dragstedt, Lang and MiIIet,4 who have shown that distention causes the greatest interference with the circuIation of the duodenum, and the Ieast with that of the coIon. They correIated this variation in susceptibiIity with the variation in the vascuIar distribution in different portions of the intestine pointed out by Eisberg.5 In 1930, Burget” and his co-workers made observations on the pressure developing in cIosed Ioops of intestine and noted pressures of o to 56 cm. of water. They noted necrosis occurring in the waII of Ioops distended by pressures of 25 to 30 mm. of mercury. From the foregoing and many simiIar observations it is cIear that the distention caused by obstruction, etc. can Iead to varying degrees of circuIatory disturbance in the bowe1 waI1, and if severe to necrosis, uIceration and perforation. The mechanism and the nature of the pathologic changes deveIoping are fairIy cIear. It is important, however, to consider what functiona changes in the bowe1 waII may occur as the resuIt of distention. E$ect of Distention on Intestinal Motility. It is well recognized that a certain degree of intraenteric pressure wiI1 act as a stimuIus to peristaltic activity. In excised Ioops of guinea pig intestine Henderson’ found pressures of 15 to 25 mm. of water to

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be effective. As the pressure is increased, however, motihty becomes impaired and finaIIy ceases altogether. The foIIowing statement from AIvarez and Hosaig expresses the prevailing view: Hotz concIuded, therefore, that injury to the muscIe in peritonitis is due, not to toxins, but to distention by gas. The gas accumuIates when absorption is impaired. As UsadeI showed, distention of the gut closes not onIy the arterioIes that bring necessary bIood to the muscIe but aIso the venules of the porta system, which normalIy carry the gas away as fast as it is formed. It can easiIy be seen, then, that once gaseous distention and muscular paraIysis appear, they are IikeIy to get worse and worse through the formation of a vicious circle.

Effect of Distention on Intestinal Secretion. ComparativeIy few observations have been made of the effect of intraenteric pressure on intestina1 secretion. Herrin and Meek9 studied the effect of distention on dogs with varying types of intestina1 fistuIae. On distending the intestine by means of baboons inAated to a pressure of 80 to go mm. of mercury they noted a very marked increase in the secretions from the fistula. As much as 550 C.C. of ffuid was formed in a fistula 20 cm. Iong during the course of twenty-four hours. They state : “Distention is a strong StimuIus to intestina1 secretion and in obstruction this must work in a vicious circle.” Effect of Distention on Intestinal Absorption. Considerably more interest has been shown in the question of the influence of intraenteric pressure upon the absorption by the intestine of substances that may be present in its lumen. It has Iong been known that the norma mucosa has the ability of seIectively absorbing many nutritive materiaIs and of rejecting or other substances not not absorbing especiaIIy different in chemical and physicaI properties of sohrbihty, permeability, etc. This seIective ability of the mucosa, highly speciaIized as it is, might be presumed to be relativeIy susceptibIe to changes of intra-intestina1 pressure.

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In 1919 Dragstedt, Dragstedt, McCIintack and ChaselO reported a number of experiments which demonstrated that distention of the intestine operated to increase the absorption of toxic materiars from the bowe1 Iumen. It was shown that animaIs couId tolerate closed obstructed Ioops of intestine containing highIy toxic material if distention of the Ioop was counteracted by with the intestinal mucosa treating astringents, and converseIy that adding substances like hypertonic magnesium sulphate to such loops which would provoke distention would be foIIowed by intoxication of the usua1 type. More recently this was demonstrated in a different way by who prepared cIosed L. R. Dragstedt’l intestina1 Ioops in such a manner that the Iumen of the Ioop couId be aspirated at intervaIs by a needIe thrust through the abdomina1 waI1. In such animaIs it was observed that the onset of unfavorabIe symptoms occurred simuItaneousIy with the deveIopment of considerabIe pressure in the Ioop, and that aspiration of a portion of the loop content, with resuItant decrease in pressure, caused a reIief in the symptoms. This experiment has been repeated and confirmed by Burget6 and his co-workers, who have made the additiona suggestion that part of the unfavorable symptoms present when the Ioop is under pressure may be reflex in character. In 1924 Stone and FiroP studied the effect of intra-intestina1 pressure on absorption from the Iumen of the intestine. The foIIowing quotation from their articIe details their observation : Our attention was now turned to the way in which changes of pressure within the lumen of the bowel may affect the absorption of substances present there. It is perhaps we11 ‘repeated here the observations made by ourseIves and others in the behavior of the material found in experimental loops of jejunum. As has been said, this contains a highly toxic element, which when injected intravenously, with proper controls and precautions, causes the death of heaIthy dogs with a typica syndrome, anaIogous to that seen in obstruc-

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accepted view is that this eIement is the IethaI agent in obstruction, and that its absorption is the cause of death. But if this materia1 be introduced into the Iumen of the unobstructed bowe1, either by feeding tube or injection through the bowel waI1, it is quite innocuous. In other words, it is not absorbed. To throw Iight on this particuIar phase, a series of experiments was made with India ink, which may be summarized as foIIows : (I) Ink was injected into the Iumen of the norma intestines exposed by Iaparotomy, and the wound cIosed. Such abdomens were reopened at varying intervaIs afterward and carefuI search made for any evidence of absorbed ink in the intestina1 Iymphatics, the mesenteric and retroperitonea1 glands, and the Iiver. None was found. (2) A partia1 occIusion of the Iumen in the duodenum just dista1 to the papiIIa of Vater was made by seroserous sutures, kinking the bowe1 into a sort of sigma shape. The same thing was done in the jejunum about 20 cm. beIow the first kink. This gave a loop partiaIIy, but not compIeteIy, obstructed at each end. Into this Ioop, India ink was again injected. At intervaIs, the Iymphatics, gIands, and Iiver were examined for ink, and none was found. (3) A tie of string (but not thick siIk) was pIaced about the duodenum beIow the papiIIa and tied down very hard so as to cIose compIeteIy the Iumen. The two sides of the suIcus caused in the bowe1 waIIs by this Iigature were united by seroserous mattress suture, thus burying the constricting Iigature about the bowe1. Another hard tie, simiIarIy covered, was pIaced about the jejunum some 20 cm. beIow the first. Thus a double compIete obstruction and an isoIated Ioop were formed. Into this cIosed Ioop was injected again some India ink. We expected these dogs to die. To our surprise some of them survived the initia1 critica period and seemed to be aIright. The abdomen was then opened, and it was found that both Iigatures about the bowe1 had cut through into the Iumen and the obstruction was thus reIieved spontaneousIy. The point of greatest interest, however, was that the Iymph gIands draining the temporariIy compIeteIy obstructive Ioop were black with ink, visibIe both to the microscope and the naked eye. Comment on this group of experiments wiI1 be Iimited at this time to pointing out that India ink, Iike the toxins from obstructed

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Ioops, is not absorbed when injected into the norma bowe1 Iumen; it is not absorbed when the Iumen is narrowed and kinked, but stiI1 patent; it is absorbed, however, when compIete obstruction exists even for so short a period of time that the anima1 does not succumb to the obstruction. A possibIe expIanation of these facts might be that pressure within the Iumen must reach a certain IeveI before the ink is absorbed through the waI1 of the bowe1, and as long as the Iumen was even partiaIIy patent, this IeveI was not reached:It is interesting to note aIso that the dogs which absorbed the ink in these experiments stiI1 survived. It may be assumed that they aIso absorbed toxins, but that the reIease of the obstruction occurred before a IethaI dose was attained, and with the reIease of obstruction, pressure in the bowe1 feI1, and absorption ceased. The next series of experiments was performed upon Iiving excised Ioops of Iower duodenum and upper jejunum, obtained from dogs. The preparations were made as foIIows: The Ioops were excised without Iigation of the stumps of bIood vesseIs or Iymphatics Ieading from the intestine into the mesentery. The mesentery was divided fairIy cIose to the bowe1. The Ioops were suspended in ffasks of Ringer’s soIution, kept at body temperature over a hot water bath, and were discarded for further use as soon as faiIure of muscIe contractions or change of coIor suggested that the tissues were Iosing their vitaIity. With such preparations severa types of experiments were carried out: (I) A Ioop so prepared, cIosed at both ends by firm Iigatures was suspended in the soIution for forty-five minutes. At the end of this time the surrounding Ringer’s soIution was injected intravenousIy into a heaIthy dog. No effect of a toxic nature was noticed. (2) A Ioop so prepared was fiIIed with known toxic content from a dog dying with an isoIated obstructed segment df bowel. To one end of this Ioop a hand-operated pressure buIb was attached by a rubber tube, and the other end of the Ioop was tied off secureIy. The preparation was then suspended as in the other experiment, and pressure aIternateIy appIied and reIaxed, distending the Ioop with toxin in it in cycIes that might be approximately Iike those of peristaIsis. After forty-five minutes the fluid in which the Ioop was suspended was injected intravenousIy into a heaIthy dog and produced death with the typica signs and

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symptoms caused by the toxins of obstructed Ioops of boweI. We interpret these findings to mean that toxin does not pass through a SUSpended Iiving Ioop of bowe1 without some intraintestina1 pressure, but does pass when such pressure exists within the Iumen. Gatch13 has recentIy reported experiments which seem to cIarify many of the apparentIy contradictory observations on the effect of varying intraintestina1 pressures on absorption. Because of the importance of his observations the foIIowing quotation from a recent article of his is given : A Iigature is tied about the smaI1 intestine, and at a point one to two feet from this Iigature the bowe1 is cut across and a grass cannula is introduced and tied in pIace so that a segment of bowe1 is isoIated between the cannuIa and the Iigature. The cannuIa is connected with a pressure apparatus. The bIood pressure is recorded. With the segment of bowe1 outside the abdomen the pressure within it is now eIevated tiI1 it ecIuaIs the systoIic pressure of the anima1. As we have aIready expIained this produces a compIete anemia of the bowe1. Now we introduce into the bowe1 a Iarge dose of nicotine or potassium cyanide. Next we graduaIIy Iower the pressure within the bowe1. There is no sign of absorption of the poison tiI1 the pressure reaches about haIf the systoIic pressure. At this degree of pressure there is rapid absorption of the poison, cIearIy shown by a sudden and great eIevation of bIood pressure, if nicotine is used, and by a great increase in respiration if potassium cyanide is used. If now the same experiment is repeated except that the bowe1, distended to the height of systoIic pressure, is repIaced within the abdomen, the anima1 shows immediate signs of absorption. Thus whiIe the distention of the bowe1 prevents or diminishes direct absorption into the bIood stream, it probabIy increases absorption by way of the peritoneum, because effusion can take pIace more readiIy through a thin and damaged bowe1 waI1 than through a bowe1 waII uninjured and of norma thickness. By this method it can be shown that absorption from the intestine varies inverseIy as distention of the intestine, or stated in other terms, the absorption decreases as the circuIation through the bowe1 decreases, tiI1 with the

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onset of gangrene a11 absorption must be transperitonea1. From an incarcerated Ioop or from any Ioop, the mesenteric vesseIs of which are obstructed, the absorption must be transperitonea1 from the very onset, because here the mesenteric veins of the Ioop are obstructed very soon. From the free bowe1 above the site of obstruction the absorption by wav of the mesentery wiI1 decrease as the distention of the bowe1 increases. Since observers are pretty we11 agreed that the toxins from the obstructed bowe1 are but sIowIy absorbed through an intact mucosa, and since injury of the mucosa does not occur tiI1 a rather high degree of distention has been reached, which wouId interfere with the circulation of the bowe1 waI1, it foIIows that the chief route of absorption must be transperitoneal and that the chief absorption of toxins in intestinal obstruction occurs rather Iate in the course of the disease, after weII-marked distention of the bowe1 has occurred. To summarize, there are numerous cIinica1 and experimenta observations in accord that in conditions of obstruction of the intestine, distention of a sufficient degree to produce aIterations in the physioIogy as we11 as the pathoIogy of the intestine may occur, that the resuIting changes in motiIity and secretion of the intestine tend to further increase the distention by the estabIishment of a vicious circIe, and that the distention may tremendousIy aIter both the degree and the manner by which substances in the Iumen of the intestine may be absorbed. The bearing that these observations have upon the treatment of the various conditions in which distention may arise is not altogether cIear. In case of a simple obstruction seen comparativeIy earIy the argument is not compIex. There are, however, not a few reports of death, apparentIy due to toxemia, occurring rather soon after the reIief of an obstruction that has existed for sufficient time to cause considerable distention. The earIier opinion that this couId be expIained by the absorption of toxic materia1 after entering the empty and coIIapsed bowe1 beIow the obstruction

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does not seem warranted by the observations previousIy mentioned, as it appears unIikeIy that such toxic material wiI1 be absorbed by the norma mucosa. On the other hand, as Stone’4 and others have suggested, the reIief of the obstruction and the consequent faI1 in intraintestina1 pressure may permit a rapid return of circuIation through the bowel wal1. which may carry off into the genera1 circuIation poisonous materia1 which may have penetrated the waI1 of the intestine during the period when the intestine was distended. This expIanation wouId apparentIy necessitate the assumption that the transperitonea1 absorption presumabIy occurring during the time of distention is of a Iess overwheIming nature than that via the mesenteric bIood and Iymph vesseIs after the distention is reIieved. It is not aItogether an uncommon observation that apparentIy toxic symptoms may develop after the Ioops of bowe1 in the case of a stranguIated hernia have been returned to the abdomina1 cavity from the hernia sac. It is quite possibIe in the Iight of Gatch’s experiments to suppose that the stranguIated loop whiIe in the hernia1 sac is analogous to a loop of bowe1 distended whiIe outside of the abdomina1 cavity to the degree that the onIy absorption possibIe is transperitonea1 and that the hernia1 sac has not the absorptive capacity of the free peritonea1 cavity. There is thus some justification for the position taken by in advising resection various surgeons of the boweI, which aIthough apparently viable may have been damaged by the distention so that toxic absorption is possibIe. There is the aIternative of emptying the distended bowe1 by “stripping” by the method advised by HoIden.16 He pIaces a test tube of considerabIe size in an incision in the bowe1 above the site of the obstruction, A Iigature hoIds it in pIace at the flange. Through this, with the aid of a rubber tube to carry it off, he empties the entire bowe1 above the obstruction by very gentIe stripping with the heIp of a suitabIe Iubricant. He reports exceIIent resuIts. He avoids

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the shock and trauma of resection and removes the toxins effectiveIy. It seems probabIe from the foregoing that most of these probIems wiI1 eventuaIIy be soIved by these studies of the circuIation in the bowe1 waI1, studies of stranguIation and hydraulic vicious circle. Dehydration undoubtedIy is the cause of death in many patients. Dehydration from vomiting, from lack of ffuid intake, and the dehydration from shock, preoperative, operative, and postoperative, a11 add to the dehydration. These patients need quarts of salt soIution and glucose. .Many a patient has died from insufficient hypodermocIysis or intravenous infusion, or even bIood transfusion. StiII there remains the positive evidence that the contents of experimentaIIy obstructed Ioops is a deadIy poison when administered to other animaIs. And it seems evident that many patients have died from the absorption, postoperativeIy, of this toxin. The foregoing experiments in absorption with different degrees of pressure in the intestine expIain much of the mechanics of this probIem. During the height of the obstruction the intraintestinal pressure, both in the Ioop and above it, is so high that the veins, capiIIaries, and Iymphatics are a11 cIosed, and there can be no absorption. As aIready shown, when fuIIy distended there can be no absorption from the intestine directIy, onIy transperitoneaIy. After the obstruction is removed there is gradua1 reIief of pressure, but the sIuggish bowe1 needs some time to rehabiIitate itseIf and be entireIy reIieved of distention. Congestion, deoxygenation, edema and infection are not immediateIy removed. In other words enough distention continues for some time to favor more rapid absorption than normal As aIready shown moderate distention favors absorption in the presence of comparativeIy adequate circuIation. This moderate distention favors rapid absorption. The congestion and deoxygenation from poor circuIation increase permeability of the capiIIaries. CompIete

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distention arrests the absorption of toxins but favors their deveIopment and accummation. The moderate distention which foIIows the reIief of obstruction favors a rapid and overwheIming absorption of the toxins directIy from the intestine where they have accumuIated. The impaired circuIation is at the bottom of aI1. From this study does not the procedure of HoIden15 seem reasonabIe and encouraging? By gently emptying the bowe1 he relieves the circuIation, restores norma capihary function more promptIy, and removes toxic and infective materia1. Prompt restoration of adequate circuIation is the important resuIt. It is obvious that he must avoid trauma. When carefuIIy done there shouId be IittIe shock from this procedure. MeanwhiIe, a11 the conditions, circuIatory, coIIapse, shock, toxemia, dehydration, caI1 for copious infusions of fIuid hypodermicaIIy and intravenously. A weIIhIIed heart has tremendously increased power over a haIf empty one, and capiIIaries cannot function properly without an adequate suppIy of bIood and oxygen. Kidneys cannot secrete, nor liver detoxicate when bIood pressure faIIs beIow a certain height. We must bring back the blood pressure, and for this, the aII-important remedy is an abundance of fluid. Begin before the operation, continue during the operation and then stiI1 continue. Of course peritonitis kiIIs most patients with obstruction, and here again ffuid is the trump card. From these studies we must concIude that both dehydration and toxemia are factors in the cause of the postoperative deaths. When obstruction is high up in, or near, the duodenum there wiI1 be a copious outpouring of fluids and chIorides from the Iiver and pancreas, as we11 as from the duodenum and stomach by vomiting, whiIe in obstruction in the iIeum, or near the coIon there wiI1 be much Iess vomiting, but a greater accumuIation of toxins and the products of infection. The Iength of bowe1 before the stomach is reached wiI1 prevent the fIuid from reaching the stomach readiIy, and there wiI1 be correspondingIy

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IiberaI reabsorption of fluid. For the same reason the greater stagnative and circuIatory interference wiI1 favor formation of toxins. The more extensive bacteria1 flora, the congestion and deoxygenation are a11 important factors. A most instructive study of the mechanics of intestina1 obstruction came to me a few years ago in a patient with intestinal obstruction from a Iarge gaIIstone which had uIcerated into the intestine. This stone, smooth and egg shaped, was just Iarge enough to obstruct the smaI1 intestine and stiI1 aIIow the peristaIsis to move it down graduaIIy. It had taken approximateIy a week to reach the iIeum where I found it. The distended bowel above it was congested to the point of bIueness near the obstruction, but faded to an intense redness a few inches away. The congestion and distention continued upward however, for practicahy the entire length of the bowe1. Near the point of obstruction the intestine was IiIIed with Auid. Near the stomach it was being constantIy emptied by regurgitation and vomiting. The man was ravenousIy thirsty and evidentIy dehydrated. He caIIed for water constantIy and wouId promptly vomit a11 he drank, and seemingIy more. He wouId then immediately caI1 for more water. He had continued thus for severa days. The mechanics were evident. The obstruction was just enough to hoId accumuIating fIuid of secretion, effusion and hItration above it. This distended the bowel to its capacity, stretching the waIIs and sIowing the circulation to an intense congestion. This retarded circulation pIus the deoxygenation of congestion increased the capiIIary permeability (Krog, l6 Landis”), aIIowing an increased outpouring of ffuid from the circuIation, resuIting in the copious vomiting and dehydration. At the same time it ihustrated the fact that the IO to 15 feet of intestine above this point were sufficient to hoId a Iarge quantity of l&rid and gas in the distended congested bowel under dangerous pressure, but not sufficient to produce complete stranguIation, necrosis or gangrene.

I I2

American Journal of Surgery

Van ZwaIenburg-Vicious

Let us assume that the intraintestina1 pressure approached 15 cm. of water. AntiperistaIsis wouId empty some of the contents into the stomach and the pressure would then be Iowered to say 8 or IO cm., just enough to aIIow capiIIary circuIation with diffrcuIty and great congestion. In a short time the additiona accumuIation would cause a repetition of the same program. AI1 the time the peristaIsis and the hydrauIic pressure were sIowIy moving the stone onward, steady pressure forcing enough tissues to give way to aIIow an increase in the diameter of the intestine sufficient to aIIow the stone to trave1 sIowIy downward. This sIow movement of the obstruction reIieved the circuIation just above it suffrcientIy to prevent compIete stranguIation or even infection. Evidently this area just above the obstruction can withstand stasis up to practica stranguIation and arrest for a short time, but if the obstruction is complete as from a peritonea1 band a breakdown with necrosis and gangrene results, unIess the obstruction is near enough to the stomach

CircIe

OCTOBER, 1932

to permit antiperistaIsis to empty it suffrcientIy easiIy to prevent the intraintestinal pressure to reach the point of permanent arrest of circuIation in the bowe1 waI1. Had this stone in its downward movement arrived at a point of bowe1 suffrcientIy narrow to arrest it permanentIy, stranguIation, infection and necrosis wouId have foIIowed. If on the other hand he couId have withstood the dehydration Iong enough to aIIow the stone to reach the coIon, without finding an impassabIe stretch, he would have recovered as many other patients of this type have. In this case incision, easy remova1, and copious hypodermocIysis were foIIowed by a prompt recovery. The mechanics of hydrauIic vicious circIe were there and beautifuIly iIIustrated, but the circIe was never compIeted because one arc of it was movabIe. I am proud to acknowIedge my indebtedness to Car1 Dragstedt for very materia1 assistance in preparing this paper, and to Maurice Visscher for advice, suggestion and encouragement.

REFERENCES I. VAN ZWALENBURG, C. V. StranguIation resulting from distention of holIow viscera. Ann. Surg., 46: 780, 1907. 2. VAN BEUREN, F. T. The mechanism of intestina1 perforation due to distention. Ann. Surg., 83: 69, 1926. 3. GATCH, W. D., TRUSLER, H. M., and AYERS, K. D. Effects of gaseous distention on obstructed bowel. Arch. Surg., 14: 1215, 1927. 4. DRAGSTEDT, C. A., LANG, V. P., and MILLET, R. F. The relative effects of distention on different portions of intestine. Arch. Surg., 18: 2257, rg2g. 5. EISBERG, H. B. On the viabihty of the intestine in intestina1 obstruction. Ann. Surg., 81: 926, 1925. 6. BURGET, G. E., MARTZLOFF, K., SUCKOW, G., and THORNTON, R. C. B. The cIosed intestina1 Ioop. Arch. Surg., 21: 829, 1930. 7. HENDERSON, V. E. Studies in peristahic Am. J. Pbysiol., 66: 380, 1923.

fatigue.

8. ALVAREZ, W. C., and HOSAI, K. What has happened to the unobstructed bowel that faiIs to transport ffuids and gas? AM. J. SURG., I : 56g,Ig26. g. HERRIN, R. C., and MEEK, W. J. Studies on intestinaI obstruction. Am. J. Pbysiol., 97: 532, 1931.

IO. DRAGSTEDT, L. R., DRAGSTEDT, C. A., MCCLINTOCK, J. T., and CHASE, C. S. A study of the factors invoIved in the production and absorption of toxic mater& from the intestine. J. Exper. Med., 30: log, rgrg. I I. DRAGSTEDT, L. R. BIood chemistry in intestina1 obstruction. Proc. Sot. Exper. Biol. CT Med., 25: 239, 1928. 12. STONE, H. B., and FIROR, W. M. Absorption in intestina1 obstruction: intraintestina1 pressure as a factor. Trans. Soutb. Surg. Ass., 37: 173, 1924. 13. GATCH, W. D. The bIood chemistry, toxemia and mechanics of advanced intestina1 obstruction, with deductions on treatment. Illinois. M. J., 60: 236, 1931. 14. STONE, H. B. The cIinica1 apphcation of experimenta1 studies in intestina1 obstruction. AM. J. SURG., I: 282, 1926. 15. HOLDEN, W. B. SurgicaI treatment of acute intestina obstruction. Surg. Gyn. Obst., 50: 184, 1930. 16. KROGH, A. Anatomy and PhysioIogy of CapilIaries. New Haven, Yale Univ. Press, x929, p. 315. 17. LANDIS, E. M. Micro-injection studies of capiIIary permeabihty. III. The effect of Iack of oxygen on the permeabiIity of the capiIIary waI1 to Auid and to plasma proteins. Am. J. Pbys., 83: 528, 1928.