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This comprehensive guide covers the definitions, causes, classification, and consequences of Abdominal Compartment Syndrome (ACS). Learn about measurement techniques, monitoring options, and optimal closure techniques for open abdomen cases.
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Abreviations • IAP = Intra-abdominal pressure • IAH = Intra–abdominal hypertension • APP = Abdominal perfusion pressure • MAP = Mean arterial pressure • ACS = Abdominal Compartment Syndrome
The pressure within the abdominal cavity Normal:5 – 7 mmHg normal intra-abdominal pressure (IAP)
Intra–Abdominal Hypertension (IAH) = sustained or repeatedly elevated IAP ≥12 mmHg
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
IAH Effects >12 mmHg IAP has significant effects onabd. organs and cardiac output with subsequent dysfunction of both abd. and extra-abd. organs
IAH Effects APP = MAP – IAP
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)
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
Primary causes of ACS • Abdominal trauma with bleeding • Pancreatitis • Ruptured abdominal aortic aneurysm • Retroperitoneal hematoma • Obstructions/ileus • Pneumoperitoneum • Abscesses • Visceral edema
Secondary Causes of ACS • Acute respiratory distress syndrome • Major trauma or burns • Massive fluid resuscitation • Hypothermia • Acidosis • Hypotension • Massive blood transfusion • Coagulopathy • Sepsis
Chronic causes of ACS • Obesity • Liver failure with ascites • Malignancies
Physiologic Insult/Critical Illness Ischemia Inflammatory response Fluid resuscitation Capillary leak Tissue Edema (Including bowel wall and mesentery) Intra-abdominal hypertension
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
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
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
Pathophysiological Consequencesof ACS Gastrointestinal • Reduced blood flow → Intestinal ischemia→ Paralitic ileus
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
Types of Measurements • Direct pressure via intraperitoneal catheters • Indirect pressure • Gastric measure • Rectal • Urinary bladder pressure • IVC
Urinary Bladder Pressure • Reproducible and technically the most reliable • Correlate closely with pressures measured directly in the abdominal cavity • Transduced through a Foley catheter
Intermittent Monitoring • Open Systems • Closed Systems
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
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
Measuring Bladder Pressure • Position patient flat & supine • Read Mean pressure • End Expiration
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
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
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)
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
Optionsfortemporaryclosure • Simple coverage with moist lap pads • Towel clips • “Bogota Bag” • Repeated entry: zippers, velcro, slide fasteners • Mesh
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
Towel clips • skin approximation in conjunction with occlusive dressing • towel clips used when patient grossly unstable/coagulopathic
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
Repeated entry • can suture pre-sterilized zipper (=or velcro, slide fasteners) to the edge of Bogota bag or mesh
Mesh closure • closure with absorbable mesh (Vicryl) • sewn to fascia for intermediate duration closure (or to skin if need repeat operation)
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
Skin grafting • can be applied directly to exposedviscera once abdominal contents “frozen” • waiting for granulation bed increases risk for bowel injury
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