Endoscopic colonic decompression

Colonic pseudo-obscruction, or Ogilvie's syndrome, is characterized 
by marked distension of the large intestine in the absence of mechanical 
obstruction. Etiology is unknown. Left untreated, it may lead to perforation with 
a mortality of 46%. Reversible causes such as electrolyte imbalance, anricholinergic 
drugs, analgesics, steroids or hypothyro1d1sm should he excluded. Early 
recognition of pseudo-obstruction with institution of supportive means followed 
by colonoscopic decompression with rube placement should be successful in all 
cases.

C OLONIC' PSEUOO-O~'TRUC110N, OR Ogilvie's syndro me ( 1 ), is characterized by marked distension of the large intestine in t he absence of mechanical obstruction .It is a form of colo nic ileus that, left uncreated, may lead to perforation of the right colon with a mortality rate as high as 46% (2).U rgent surgical decompression with cecostomy is reported to have a mortality rate of 12 to 20% (3).Over a decade ago chese patients required surgical treatment.
Endoscopic decompression wi ll now become the treatment of choice.
The ettology of this syndrome 1s unknown.Ogilvie ( I ) in 1948 reported a patient with colonic distension who had mvasive carcinoma at the root of the mcsentery involving the prevertebral ganglion.He believed that this invasion resulted in an autonomic imbalance leading to d1stens1on.This concept is still acceptable.These patients are unwell with maJor systemic illnesses, sep- DIAGNOSIS Typically a sick or injured patient is noted to have developed progres.,1veabdom inal distension.This is often associated with dimmished bowel sounds and, depending on the degree of d istension, some tenJemess.There may or may not be diarrhea.In contrast to mechanical obstruction, vomiting 1s uncommon.S ignificant peritoneal signs could imply that perforation 1s impending or has occurred.Confirmation of the diagnosis of pseudo-obstruction requi res ahdominal x-rays m the supine and lateral positions ( 4 ).
Controversy exists as to what cecal measurement is most critical.A cecal diameter of 9 cm or less is not likely co lead to perforation.Most agree that a diameter of 12 cm or more requires close observation (S).With tl11S degree of howel distension, the phys ician 1s obliged to rule our a mechanical lesion.Concern over ohscruct10n can he elim inated either endoscopically or radiologically with an enema using a water-soluble contrast media such ,h Hypaque (Winthrop).The mechanical causes could be distal obstruction or missed cecal volvulus (6).The watersoluble contrast enema may have an additional beneficial effect because of its osmotic character, and may aid m che emptying of the distal colon.Analgesics are thought to be the most common reversible cause.In a review of the literature, the number of cases that resolve with conservative management varied from 40 to 96% (7).In the latter srudy, most cases resolveJ within two days.The clinician m ust decide whether to proceed to endoscopic decompression rather then wait an inordinate perioJ of time and risk perforation, if there is no resolution.

SUPPORTIVE THERAPY
In some patients the distension will resolve by discontinuation of medication and general supportive measures such as hydration, enemas, and a rectal rube (Table l ).The passage of a nasogastric tube and wirhholJing oral intake are helpful.Frequent turning of the patient co the prone position allows redistribution of colonic gas into the descending colon anJ al lows easier evacuation.

ENDOSCOPIC APPROACH
The endoscopic approach was first reported in 1977 ( 8).Colonoscopic decompression is init ially successful in the vast majority of cases.However, in a sizable proportion of patients varying from 20 to 60%, there was rec urrence of the pseudo-obstruction within a few hours to days (9-11).This would then necessitate a repeat co lonoscopic decomp ression or o perative decompression.
There are some concerns about the risks of colonoscopic attempts at decompression in an already distended and usually unprepared colon.Resultant perforation in many of these sick patients would be potentiall y more serious (11).However, the author's experience has supported the theory that endoscopy can be carried out safely and effectively in virtually all patients.There is no question that colonoscopy under these circumstances -with an ill patient and an unprepared bowel -is more difficult, takes longer and requ ires more care than routine colonoscopy.The use of frequent and large irrigations of tap water through the accessory channel may be necessary for visualization, and allows the cecum to be reached in virtually all cases.Only the smallest amounts of air are insufflated during the examination.Manual pressure by an assistant can also facilitate the expulsion of air.Success of decompression is confirmed by reduction of abdominal distension and cecal size seen on fluoroscopy.
The endoscopist should watch for evidence of mucosa!ischemia, which is demonstrated by a dusky, hemorrhagic or ulcerated mucosa, usual ly in the right colon.
In the past, management of patients whose distension persisteJ despite endoscopy or soon recurred, required e ither repeat endoscopy o r surgical decompression by cecostomy.The author be lieves that this mode of treatment is now unacceptable, anJ a ll patients with pseudo-obsrruction who are treated hy colonic decompress ion should have, at the time of endoscopy, a decompression tube placed in the right colon.
A number of techniques has been J escribed which will accomplish this (Table 2).
Although fluoroscopy is not mandatory ro reach the right colon, it is certainly helpfu l and necessary for monitoring tube placement.Ideally the patient sho uld be endoscoped on a fluoroscopy cable.The author's initial technique was to use a two-channel colonoscope with a large channel (lOF).When the endoscope reached the cec um , a Wilson -  Usmg a standard colonoscopc with a 2.8 mm single accessory channel, the followmg procedure may be carried out.O n reaching the cecum, the guidewirc is maintained at its insertion level with fluoroscopic con trol as the e ndoscope is re moved.Over this wire a 140 ml nasogasuic tube or em e rolysis tube is passed a nd left 111 place.T he guidewire should be sheathed, as th is offers added sti ffness.Fluoroscopic control is necessary (Figure 2).Because t he wire is floppy, it can huckle or even slip back as the decompresskm tuhe is advanced.If the wire slips too fa r distally endoscopic reinsertion will be n ecessary .
Another method uses a fenestrated tygon uvertuhe tha t is pushed out upon reaching t he right colon ( 13 ), and the endoscope is then withdrawn.The passage of a decompression tube, anached by a sho rt suture loop held by forceps through the channel and dropped off in the righ t colon , is another possibility 15 ).Usually a double channe l endoscope is required.There is the da nger of pulling the tube back as the endoscope is withdrawn.
Does the endoscope have to reach the cecum ?It is the author's opinion th at the decompression t ube in the region of t he ascending colo n and hepat ic flexure should be adeq ua te.The decompress ion tube 1s then attached to intermittent suction at 40 mmHg.T he author c urrently irrigates with tap wate r 100 ml every 2 to 3 h.
A flat plate is taken after the procedure to mo111tor colon size and tube placement.In all patients, control of cecal pseudo-obstruction takes place wit h in 24 h , and the tube may be withdrawn in three or fo ur clays, or sooner if peristalsis push es it out.
A t the author's insti tute, between 1984 and 1989, 16 patients we re treated with 17 decompressions.All patients were t rea te d with con serv a ti ve me thods.When distension persisted or in c reas ed (a ll pa tie nts had ceca l diameters of 12 cm or greater) endoscopic tube decompression was carried out (Table 3 ).A 11 incubations were successful and no complication was encountered .A ll patie nts except one survived and left the hospital.The on e patien t died seven J ays after successful 544 Figure 2) Radio/>aque decomf>ression tube placed in cecum intubation , of massive pulmonary embo lus.He was bemg treated fo r acute renal fa ilure and sepsis.A ll cases with one except ion were carried out under flu oroscopic control.O ne patient, a 24year-old sailor with extensive third degree hums and sepsis, haJ a rec urre nce of ileus 10 days afte r successful tube decompression.His second intubation was also successful.
A n alte rnau ve mode of decompression h as recently heen published (1 6 ).T his describes the trea tme nt of pseudoobstruc t ion with an epid ural block, and postulates that t he problem is related to excessive sympathetic tone a nd that spla nc h111c sympathetic blockade by epidural an esthesia should he successful.A lthough this has the advantage of simplicity, only fi ve of eight cases were successful.Pse ud o-o bstruc tio n is a potentia lly fatal disorde r in these cnt1• catty ill patients.Earl y recog111Lion wnh the institution of suppo rtive means followed by colonoscopic decompression with tube placeme nt should be successful in all cases.
A nother condition in which endoscopic decompression is useful is narrowing of the distal colon developing into marked abdominal <listension after colonoscopy.This distension may be precipi tated by t he antiperistaltic cf.In this situation the prompt passage of a nasogastric tube over an endoscopically pl aced, fluoroscopica ll y mo nitored guidewire will result in quick relief from distension.
In cases of high grade obstruction, a slim gastroscope may be used.U nder fluoroscopic cont ro l a guidewire is passed into the colon above and the endoscope withdrawn.The endoscopist may then dila te over the wire with a Savary-type boogie, and the n pass a decompression tube above the narrowing.The colon above may then be ir-1988;3 3: 139 1-6.Endoscopic colonic decompression rigate<l and emptied.T h is method may also be used to decompress a nd prepare the colon for surgery by placi ng the t ube through the t umour in a similar fash ion , and irrigating anJ emptying t he colon, thereby avoiding colostomy in a staged procedu re.