Abdominal Compartment Syndrome and Open abdomen

1. Abdominal Compartment Syndrome andOpen abdomen

2. Abreviations • IAP = Intra-abdominal pressure • IAH = Intra–abdominal hypertension • APP = Abdominal perfusion pressure • MAP = Mean arterial pressure • ACS = Abdominal Compartment Syndrome

3. The pressure within the abdominal cavity Normal:5 – 7 mmHg normal intra-abdominal pressure (IAP)

4. Intra–Abdominal Hypertension (IAH) = sustained or repeatedly elevated IAP ≥12 mmHg

5. Grades of IAH • Grade I 12 – 15 mmHg • Grade II 16 – 20 mmHg • Grade III 21 – 25 mmHg • Grade IV >25 (ACS) ACS = Abdominal Compartment Syndrome

6. IAH Effects >12 mmHg IAP has significant effects onabd. organs and cardiac output with subsequent dysfunction of both abd. and extra-abd. organs

7. IAH Effects APP = MAP – IAP

8. Definition of ACS • A sustained IAP > 25 mmHg, associated with new organ dysfunction • Adverse physiological effects caused by massive interstitial and retroperitoneal swelling which lead to MOF (Multi Oran Failure)

9. ACS classification • Primary ACS – associated with injury or disease in abdomenrequiring earlyintervention • Secondary ACS is from conditions not originating in the abdomen • Recurrent ACS is the redevelopment of ACS following previous treatment of ACS

10. Primary causes of ACS • Abdominal trauma with bleeding • Pancreatitis • Ruptured abdominal aortic aneurysm • Retroperitoneal hematoma • Obstructions/ileus • Pneumoperitoneum • Abscesses • Visceral edema

11. Secondary Causes of ACS • Acute respiratory distress syndrome • Major trauma or burns • Massive fluid resuscitation • Hypothermia • Acidosis • Hypotension • Massive blood transfusion • Coagulopathy • Sepsis

12. Chronic causes of ACS • Obesity • Liver failure with ascites • Malignancies

13. Physiologic Insult/Critical Illness Ischemia Inflammatory response Fluid resuscitation Capillary leak Tissue Edema (Including bowel wall and mesentery) Intra-abdominal hypertension

14. Pathophysiological Consequencesof ACS Cardiovascular • Reduced Cardiac Output • Compression of the inferior vena cava and portal vein • Reduced blood return to the heart • Increased afterload from mechanical compression of vascular beds and vasoconstriction • Tachycardia • Increased pressure on great vessels making hemodynamic monitoring challenging with falsely elevated and misguiding pressures • Increased risk for thromboembolic events secondary to venous stasis

15. Pathophysiological Consequencesof ACS Respiratory/Pulmonary • Reduced lung compliance secondary to diaphragmatic elevation→ Increased peak airway →Increased risk of barotrauma • Increased work of breathing→ Hypoventilation and ventilation-perfusion mismatch→ Hypoxia and hypercarbia

16. Pathophysiological Consequencesof ACS Renal • decreased renal blood flow and glomerular filtration→ Oliguria (IAP: 15 – 20) or Anuria (IAP: >30) • Increase of antidiuretic hormone and activation of renin-angiotensin-aldosterone system (RAAS) → Increased water retention

17. Pathophysiological Consequencesof ACS Gastrointestinal • Reduced blood flow → Intestinal ischemia→ Paralitic ileus

18. Measuring Intra-Abdominal Pressure

19. Measuring IAP • Physical examination yields low levels of detection of IAH/ACS • Early detection and intervention reduces morbidity and mortality. • Diagnosis is dependent on frequent and accurate measurement of IAP • Cost effective, safe and accurate

20. Types of Measurements • Direct pressure via intraperitoneal catheters • Indirect pressure • Gastric measure • Rectal • Urinary bladder pressure • IVC

21. Urinary Bladder Pressure • Reproducible and technically the most reliable • Correlate closely with pressures measured directly in the abdominal cavity • Transduced through a Foley catheter

22. Intermittent Monitoring • Open Systems • Closed Systems

23. Equipment needed for open measurement • Disposable transducer • 12” pressure monitoring tubing • 4-way stopcock • Red dead-ender • 60 cc, luer-lock syringe • Sterile normal saline • Clamp Disadvantages • Risk of infection

24. Closed Monitoring • AbViser, Wolfe Tory Medical, SLC, UT • Pre-assembled kit • Adapts to Foley catheter and any transducer • Reduces risk of infection • Readily available, easily assessable data

25. Measuring Bladder Pressure • Position patient flat & supine • Read Mean pressure • End Expiration

26. Open abdomen

27. Abdominal Wall Closure • Optimal closure technique based on 1. Amount of blood lost 2. Volume of fluid received 3. Degree of contamination present 4. Nutritional status 5. Overall stability

28. Standard Abdominal Wall Closure • most common technique is continuous closure with monofilament suture • single or multiple layers (peritoneum and fascia) • continuousorinterrupted Major benefit: • relatively fast

29. Standard Abdominal Wall Closure

32. Indications for open technique • Excessive visceral edema / bowel distention-fascial edges may not be brought together • Post “damage control” laparotomy- gauze packs may displace abdominal contents • Planned reexploration-closure damages fascia before the definitive repair • Abdominal compartment syndrome (IAP > 25 mmHg)

33. Disadvantages of openabdomen • Exposed intestines at increased risk for • infection • perforation • subsequent „enteroatmospheric” fistulas • frozen abdomen • Definitive closure extremely difficult due to • fascialretraction • huge incisional hernias

34. Optionsfortemporaryclosure • Simple coverage with moist lap pads • Towel clips • “Bogota Bag” • Repeated entry: zippers, velcro, slide fasteners • Mesh

35. Simplecoveragewithmoist lap pads • perform only in extreme circumstances • gauze adheres to bowel • nonadherent material should be placed directly against abdominal viscera • drain placed between nonadherent material and towel

36. Simplecoveragewithmoist lap pads

37. Towel clips • skin approximation in conjunction with occlusive dressing • towel clips used when patient grossly unstable/coagulopathic

38. Bogota bag • named after Columbian surgeons who initially described its use • sterilized cystoscopy fluid irrigation bag • nonadherent, nondistensible, inexpensive • can also use plastic wound drape

39. Repeated entry • can suture pre-sterilized zipper (=or velcro, slide fasteners) to the edge of Bogota bag or mesh

40. Mesh closure • closure with absorbable mesh (Vicryl) • sewn to fascia for intermediate duration closure (or to skin if need repeat operation)

41. NPWT(Negative-pressurewoundtherapy)

42. Vacuum-assistedfascialclosure • VAC dressing placed when initial edema resolved and sponge can fit in wound • nonadherent polyethylene sheet placed over bowel and under fascial edges to prevent adhesions • VAC sponge held in place with adherent dressing • vacuum allows for constant medial traction on fascia, preventing retraction and loss of domain • dressing changed every 3 to 5 days in OR

43. Skin grafting • can be applied directly to exposedviscera once abdominal contents “frozen” • waiting for granulation bed increases risk for bowel injury

44. Reconstruction • tissue coverage may be achieved with skinflaps alone • if fascia can close without tension, close primarily in standard manner • if fascial defect remains: • can place prosthetic mesh (eg. Compositmeshorbiological) • relaxing incisions in the external oblique aponeurosis lateral to rectus sheath