Theodoros Mesimeris



The clinical course of Crohn's disease is unpredictable with frequent relapses and many complications. Active or fistulizing disease refractory to various therapeutic agents are major problems in clinical practice , result in patient's poor quality of life and may lead to serious adverse drug reactions or complications requiring surgical intervention.


Current theory of Crohn's disease pathogenesis implicates genetic susceptibility triggered by environmental factors (microbial agents, toxins).This combination leads to inappropriate inflammatory response in which activated immune and non-immune cells release various inflammatory mediators and toxic molecules (cytokines, cell adhesion molecules, NO, ROMs) resulting in perpetuation of inflammation and tissue injury. According to vascular hypothesis endothelial dysfunction plays a central role in initiating and perpetuating inflammation. Vascular injury is a prominent feature of Crohn’s disease caused by various mechanisms leading to tissue ischemia and damage(necrosis).1, 2, 3

Hyperbaric oxygen therapy (HBOT) is thought to restore tissue hypoxia , downregulate inflammation and promote tissue repair.4, 5 Uncontrolled clinical studies have utilized Hyperbaric oxygen therapy (HBOT) as adjunctive modality in severe perianal Crohn’s disease with encouraging results.6


Evaluate HBO efficacy and safety as adjunctive therapy in patients with treatment resistant active or fistulizing Crohn's disease through a multicenter controlled unblind prospective study.


Adult patients with refractory or fistulizing Crohn’s disease will be enrolled in an international controlled unblind trial in which Hyperbaric oxygen will be applied as adjuvant therapy to conventional treatment .

Patient Selection :

Patients will be eligible for the study if their Crohn’s disease status (active or fistulizing) is refractory to the conventional treatment (mesalamine , corticosteroids , mercaptopurine or azathioprine ) with or without surgical intervention.

Crohn's disease activity assessment is based in various indexes which evaluate and score various indices ( symptoms , signs , complications , laboratory parameteres and general well being ). In our protocol we estimate the disease activity using the widely accepted and commonly used Crohn's Disease Activity Index (CDAI). The CDAI incorporates 8 Crohn’s disease–related variables : number of liquid or very soft stools , abdominal pain and cramping , general well-being , extraintestinal manifestations, complications , abdominal mass , use of antidiarrheal medications , hematocrit , and body weight. These items yield a composite score ranging from 0 to 600 , with higher scores indicating greater disease activity. Scores of <150 indicate remission, and scores of >450 indicate severe illness.7

In our study we consider disease as "refractory" two dinstinct groups of patients , those who remain symptomatic with a CDAI score-indicating activity despite adequate doses of steroids (steroid refractory) and those who flare when the steroid dose is being decreased (steroid dependent) irrespectively of concomitant use of other conventional therapeutic agents (aminosalycilates, azathioprine , mercaptopurine , metrnidazole etc.).

Patients with fistulizing disease are also included in the study. These patients usually have active disease . Of particular interest are patients with external perianal fistulas who represent a common and difficult problem in clinical practice often resistant to medical and surgical therapy. [ The severity of fistulizing disease is assesed using the Perianal Disease Activity Index ( PDAI ) which incorporates five elements: the presence or absence of discharge , pain or restriction of activities of daily living , restriction of sexual activity , the type of perianal disease , and the degree of induration , yielding a composite score ranging from 0 to 20 , with higher scores indicating more severe disease.8]

Inclusion Criteria: Patients between 18 to 65 years old , with Crohn’s disease for at least 6 months based on previous medical data , having Crohn’s Disease Activity Index (CDAI) scores between 220 and 400 or persistent fistulizing disease (regardless of surgical intervention) will be eligible for the study. All patients will give written informed consent for both the treatment ( conventional & HBOT) and endoscopic procedures.

Exclusion Criteria: Patients will be excluded from the study if they have undergone treatment with cyclosporine , methotrexate , or experimental agents ( eg. anti-TNF) within 3 months at least before inclusion. Patients will be also excluded if they have severe disease (CDAI >400) , symptomatic stenosis or strictures and contraindications to HBOT: recent (<2 years) spontaneous pneumothorax , ear-drum or ossicle chain surgery , untreated or insufficiently treated epilepsy , congenital spherocytosis , thyroid hormone replacement therapy , severe glaucoma.

Study Design :

All patients enrolled in the trial will have baseline data recordings ( week 0 ) :

  1. Full medical history (demographic variables , past medical history , related habits - smoking occupational backround , diet , family history , concomitant medication ) .
  2. Complete physical examination .
  3. Routine laboratory analyses (blood , urine and stools) , CRP , ESR .
  4. Assessment of the severity of disease according to the Crohn's Disease Activity Index and , for patients who have perianal disease at base line , the Perianal Disease Activity Index .
  5. All patients will have a full , if possible , colonoscopy and ileoscopy before starting HBOT trial. Ileal and colonic biopsy specimens will be obtained during these procedures, always in the vicinity of the most prominent ulcerative lesions. The site of biopsy collection will be recorded. Endoscopic examinations will be performed , if available , with videocolonoscopes and will be recorded on tapes or color pictures. Immediately after the procedure , the endoscopist will fill out the Crohn’s Disease Endoscopic Index of Severity (CDEIS) score .9 This score is based on the presence of deep or superficial ulceration , the proportion of ulcerated surface, and the presence of ulcerated or nonulcerated stenosis in the terminal ileum and four different segments of the colon. Drawings as well as photographs will be used to document the sites and extension of fistulizing disease.
  6. All biopsy specimens will be evaluated for active inflammatory changes (infiltration of mononuclear cells , polymorphonuclear cells , and presence of erosions and/or ulcers ) and chronic architectural changes by a pathologist in random order .
  7. Serum cytokines IL-1 , IL-1ra ,IL-6 , TNFa will be measured if possible .
  8. Subjective patient's estimation of general well- being (eg . bowel , systemic , social , and emotional ) will be recorded using simple indices ( poor , moderate , good , very good).

After obtaining baseline data patients will be randomised in two groups : In Group A patients will receive the HBO as adjuvant therapy for 40 - 60 sessions (for 6 to 8 weeks) . In Group B patients will be serve as control group continuing the conventional treatment .

Patients will have close follow up during the study period (6 - 8 weeeks) and for 24 months (at 4 months intervals ) after the end of the study. All steps of baseline evaluation (week 0) will be repeated at the end of the study (weeek 6 or 8). Steps 1 , 2 , 3 ,4 , 7and 8 will be repeated at weeks 2 , 4 and/or 6.

Patients using oral corticosteroids will be allowed to taper the dosage if they are responding to treatment. Increasing corticosteroid dosage above the baseline dose is not accepted during the study. If initiation of corticosteroids or an increase in dose is required, an efficacy evaluation will be completed to document the lack of efficacy and no further study treatment will be given. Patients receiving concomitant treatment with azathioprine, 6-mercaptopurine , sulfasalazine , mesalamine and antibiotics ( metronidazole , ciprofloxacin) will be requested to maintain a stable dosage throughout the 6 or 8-week study period . Surgical intervention during the study is allowed and will not be considered as lack of HBOT efficacy.

Patients will be treated in a monoplace or multiplace hyperbaric chamber 5 days a week , pressurized at 2,5 absolute atmospheres breathing 100 % oxygen in session periods of two hours , with 15 minutes of compression and decompression each. Air interval periods of 5 minutes will follow 30 minutes of oxygen treatment . Treatment period is planned to include 40 - 60 sessions within 6-8 weeks . During HBOT sessions patients can receive simultaneously concomitant therapy . HBOT can be applied in the immediate post-surgery treatment if it is necessary. Every hyperbaric participating centre must be physically or functionally linked to a hospital facility or medical institution and must follow the guidelines of the European Committee for Hyperbaric Medicine (ECHM) regarding personnel, safety and procedures.

In order to evaluate tissue HBO efficacy , transcutaneous oxymetry will be used (TcPO2) to assess tissue hyperoxia during the session's period . In case of severe clinical conditions patient will be monitored for vital clinical signs . Patient will be under close observation during the session from medical and nursing stuff with completion of a flow chart and recording of any adverse reaction or complication.

All patients will be evaluated and have a regular follow up from a gastroenterology team according the aforementioned study design (weeks 0 , 2 ,4 , 6 , 8 & for 24 months post - HBOT ). The participation of a hospital gastroenterology team should be preferable for the study.


Evaluation Criteria :

Successful response to Hyperbaric Oxygen therapy for active refractory disease includes:

  1. Maintaining a clinical response (defined as a ³ 70-point decrease in the CDAI) at each 4-week evaluation for the study period.
  2. Achieving and maintaining clinical remission (defined as a CDAI < 150) during and at the end of the study with or without steroid tapering. The baseline CDAI value used to determine clinical response and remission will be the value obtained at week 0.
  3. Possible long term benefit during the 24-month follow up (recurrence rate or maintaining clinical response/remission rate).

Failure includes : patients not improving CDAI score due to a&b conditions of successful response , patients who will need to change medication regimens (defined above) for treatment strategy (worsening disease) , patients who discontinued because of HBOT adverse reactions .

Successful response to Hyperbaric Oxygen therapy for fistulizing disease includes:

  1. Reduction of size and/or number of draining fistulas during the study period.
  2. Reduction of fistula discharge volume .
  3. Complete primary or secondary (surgical intervention) healing.
  4. Sustained response rate during the long term follow up.

Failure includes the steady or worsening state of baseline fistula condition during the study pariod.

Changes in scores on the CDAI , PDAI , CDEIS will be evaluated according to the study design.

Randomization :

After informed consent, patients will be randomised using a fixed scale of random numbers ordered in two groups . The scale will be provided by the main coordinator.

Statistical analyses :

Statistical methods will be determined .

Working forms with indexes will be sent to participating centers after the final study acceptance .




  1. Sartor RB Current concepts of the etiology and pathogenesis of ulcerative colitis and Crohn's disease . Gastroenterol Clin North Am 1995 Sep;24(3):475-507
  2. Fiocchi C Inflammatory bowel disease: etiology and pathogenesis Gastroenterology 1998 Jul;115(1):182-205
  3. Papadakis KA, Targan SR Current theories on the causes of inflammatory bowel disease. Gastroenterol Clin North Am 1999 Jun;28(2):283-96
  4. Rachmilewitz D, Karmeli F, Okon E, Rubenstein I, Better OS Hyperbaric oxygen: a novel modality to ameliorate experimental colitis.Gut 1998 Oct;43(4):512-8
  5. Weisz G, Lavy A, Adir Y, Melamed Y, Rubin D, Eidelman S, Pollack S Modification of in vivo and in vitro TNF-alpha, IL-1, and IL-6 secretion by circulating monocytes during hyperbaric oxygen treatment in patients with perianal Crohn's disease. J Clin Immunol 1997 Mar;17(2):154-9
  6. Colombel JF, Mathieu D, Bouault JM, Lesage X, Zavadil P, Quandalle P, Cortot A Hyperbaric oxygenation in severe perineal Crohn's disease. Dis Colon Rectum 1995 Jun;38(6):609-14
  7. Best WR , Becktel JM, Singleton JW, Kern F Jr Development of a Crohn's disease activity index. National Cooperative Crohn's Disease Study. Gastroenterology 1976 Mar;70(3):439-44
  8. Irvine EJ Usual therapy improves perianal Crohn's disease as measured by a new disease activity index. McMaster IBD Study Group. Clin Gastroenterol 1995 Jan;20(1):27-32
  9. Mary JY, Modigliani R Development and validation of an endoscopic index of the severity for Crohn's disease: a prospective multicentre study. Groupe d'Etudes Therapeutiques des Affections Inflammatoires du Tube Digestif (GETAID). Gut 1989 Jul;30(7):983-9


Study protocol NOT finalised !!!
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