Trauma

Educational Objectives

The purpose of this program is to improve management of bowel injuries, and to review medical and legal issues in the determination of brain death. After hearing and assimilating this program, the clinician will be better able to:

1.   Explain the basic principles of successful bowel anastomoses.

2.   Review appropriate techniques for minimizing the risk for anastomotic leaks after repair of bowel injuries.

3.   Define brain death and discuss the evolution of this concept.

4.   List possible confounding factors in the determination of brain death.

5.   Describe the attributes of the ideal ancillary test for determination of brain death.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning com­mittee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning committee reported nothing to disclose.

Acknowledgements

Dr. Diebel was recorded at Detroit Trauma Symposium, held November 6-7, 2008, in Detroit, MI, and sponsored by the Detroit Re­ceiving Hospital and Wayne State University School of Medicine. Dr. Tawil spoke at Current Concepts in General Surgery 2009, held September 2-4, 2009, in Albuquerque, NM, and sponsored by the University of New Mexico School of Medicine. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

Techniques and Trouble in the Management of Bowel Injuries

Lawrence N. Diebel, MD, Professor of Surgery, Wayne State University School of Medicine, Detroit, MI

Basic surgical principles for successful bowel anastomosis: adequate local blood supply; no tension at anastomo­sis; patient should be well-nourished (not always possible in trauma cases); use meticulous technique and close inspection; close all mesenteric defects

Hand-suturing: choose between single-layer and double-layer anastomoses; single layer  —  open vs closed (closed prevents leakage); double layer  —  full-thickness inner layer provides hemostasis; use silk Lembert sutures on outer layer; in speaker’s opinion, double-layer provides better hemostasis and leak prevention, especially as pa­tient’s blood pressure improves

Surgical stapling: mechanical wound stapler invented in 1908; early staplers used mostly for gastrectomies; caveat  —  when using gastrointestinal anastomosis (GIA) stapler and closing defect with end-to-end anastomosis, offset staple line to prevent exact matching (decreases risk for ischemia); to prevent leaks, place suture at end of staple line to keep line from unraveling

Management of small bowel injuries: repair preferable to resection whenever possible (“never resect something you can close”); risk for leaks much higher with resection; before resecting, run bowel from ligament of Treitz to ileocecal valve and inspect mesentery; then develop plan for closing injuries; actual treatment depends on sever­ity of injury; grades 1 and 2 injuries easily repaired with single- or double-layer technique; grade 3 injuries may require resection; per published data, leak rates similar with staples and sutures; exceptions  —  if bowel injury as­sociated with pancreatic or duodenal injury (greater risk for leaks associated with staples); when used in context of damage-control procedure; when abdominal compartment syndrome developed; study limitations  —  all data derived from retrospective studies including both resection and repair; no prospective randomized trials per­formed as of yet; choice therefore depends on “expert clinical opinion”

Anastomotic leak: speaker defines as clinical and/or radiographic evidence of enteric contents leaking through drain or into belly, or into abscess around belly; no universally accepted definition; in 2001 review, 57 different definitions of anastomotic leak found among 97 studies; fluid and air around anastomosis main finding on com­puted tomography (CT)

Factors that contribute to anastomotic failure: shock and hypoperfusion; bacterial contamination; inflammation; un­derlying illnesses, such as diabetes; use of steroids; poor nutrition; malignancy; risk highest in thoracic esopha­gus and lowest in rectum; higher in emergency cases (including trauma) than in elective cases; diagnosis not generally made until 7 to 10 days after elective surgery and £15 days after trauma surgery; greatly increases mor­bidity and mortality; in 1997 multivariate analysis, colonic anastomoses leaked more frequently than small bowel; predictive factors included hypoalbuminemia, use of steroids, peritonitis, bowel obstruction, chronic ob­structive pulmonary disease, and transfusion of >2 units of blood; transfusion and inflammation 2 risk factors in trauma patients; in-hospital mortality rate 39% with leak, 7% without; in 2006 study, suture line disruptions oc­curred in 26 of 74 (35%) emergency small bowel anastomoses; risk factors included hypoalbuminemia, hypona­tremia (probably indicates poor nutritional status), and intraoperative hypotension; trauma patients  —  risk factors for leakage include high injury severity or abdominal trauma scores; receiving >6 units of blood intraop­eratively or >10 L crystalloid; association of abdominal compartment syndrome due to splanchnic hypoperfusion

Delayed GI reconstruction: often preferable in setting of mesenteric injury and possible bowel involvement; safe to leave abdomen open with fresh GIA

Repair breakdowns: on average, detected 15 days postoperatively; indicators include higher use of intraoperative fluids and blood products and development of abdominal compartment syndrome

Colon injuries: repair safe for virtually all nondestructive injuries; 2-layer closure recommended; destructive injuries  —  in 2001 study of 297 patients at 19 trauma centers, 66% underwent primary anastomosis; diversion performed in 34%; colon-related mortality 1.3% (4 deaths in diversion group, 0 in repair group) and similar rates of colon-related complications; risk factors for abdominal complications included “severe fecal contamination” (definition unclear), transfusion of >4 units within first 24 hr, and single-agent antibiotic prophylaxis; type of sur­gical management unrelated to risk for complications; 62% of repairs hand-sewn, 38% stapled; incidence of anastomotic breakdown 6.3% among stapled repairs, 7.8% among hand-sewn repairs (difference not statistically significant)

Leakage after elective colon surgery: in 2007 Cochrane analysis, findings similar to those in trauma series; exception  —  staples better for ileocolic anastomoses

Destructive colon injuries: 7% to 10% of all colon injuries; in study of 209 patients, 56 underwent resection and anastomosis and 29 underwent diversion; authors recommended diversion for patients with destructive wounds and significant morbidity, and for those requiring >6 units of blood intraoperatively

Management of leaks: depends on magnitude; if not clinically significant  —  supportive care only; consider antibiot­ics; if leak small, with minimal soiling, consider repeating repair; moderate-sized leak  —  in reasonably healthy patients, consider percutaneous drainage; large leaks  —  repeat surgery; drain abscess; manage peritonitis; per­form diversion

Minimizing risk for anastomotic failure: animal data suggest applying fibrin glue to bowel may help; some evi­dence of benefit with buttressing of staple lines (absorbable material probably most effective [eg, polyglycolic acid, cellulose]); in study of 61 patients (most with Crohn’s disease), refistularization rate higher with abdominal wall reconstruction using prosthetic material (Permacal); speaker advises against use of such materials, if possi­ble

Controversies in the Determination of Brain Death

Isaac Tawil, MD, Assistant Professor, Departments of Emergency Medicine and Surgery, University of New Mexico Health Science Center, and Medical Director, New Mexico Donor Services, Albuquerque

History: concept introduced in 12th century by Maimonides, who considered decapitated person immediately dead despite presence of ongoing neuromuscular activity (first record of recognition that central control of neuromus­cular activity necessary for life; remains central tenet of brain death); era of brain death determination ushered in with advent of mechanical ventilator in 1950s

Determination of death: complete cessation of cardiopulmonary function (cardiac death), or cortical brain death plus complete death of brainstem in patient on mechanical support; described as “coma depasse” (irreversible coma) by Mollaret and Goulon in 1959; studied patients with criteria of profound coma and unresponsiveness, complete brainstem irreflexia, and apnea, combined with isoelectric electroencephalography (EEG); all patients eventually died cardiac death despite best available care; described coma state recognized as qualitatively differ­ent from those previously reported; ad hoc committee of Harvard Medical School published paper in 1968 with similar conclusions; used same criteria to predict futility of ongoing medical care and facilitate organ donation; prognosticated but did not diagnose death; disparity remained between medical and legal definitions of death; in 1981, President’s Commission for the Study of Ethical Problems in Medicine presented guidelines for determin­ing brain death; resulted in Uniform Determination of Death Act (UDDA), which became federal law; UDDA  —  made criteria for diagnosis of brain death legal for determining death; time of death defined as time at which pa­tient met brain death criteria; states that family members may no longer insist on mechanical support after patient determined to be deceased via these criteria; American Academy of Neurologists consensus statement  —  issued in 1995; expert opinion and evidence-based guidelines for process of determining brain death; described exami­nation for brain death and utility of ancillary tests and imaging studies

Findings of recent study of brain death determination guidelines at top 50 neurological centers in US: most did not require neurologist or neurosurgeon to make determination (clinicians from other specialties, including primary care, permissable); most allowed for house officer determination, rather than requiring determination by attend­ing physician; 70% required >1 examination; 3% required >2 examinations; requisite time between first and con­firming examination varied from 1 to 24 hr (optimum time interval unknown); preclinical testing  —  possible confounders of brainstem examination include profound hypothermia, shock, and use of sedatives; centers varied in definitions of hypothermia (from 32^o to 37^o), shock (differed regarding appropriate systolic pressure) and methods of assessing sedative effects; physical criteria for brain death also variable (eg, only 27% of guidelines specified absence of spontaneous respiration); apnea testing  —  patient disconnected from respirator and given potent hypercarbic stimulus to provoke breathing (tests for blood flow to medulla or brainstem); exposes patient to possible hypoxia, persistent hypercarbic acidosis, and potential hemodynamic instability; some variability among centers in performing test; ancillary tests  —  study found wide variation among centers; typically indi­cated when clinical examination incomplete (eg, patient could not tolerate disconnection from ventilator for ap­nea test [due to persistent hypoxia, hemodynamic instability, or persistent acidosis]); no consistent guideline for patients who retain CO₂ or have taken sedatives; no optimal ancillary tests identified; common tests include EEG, angiography, and transcranial Doppler ultrasonography

Choosing appropriate ancillary tests: ideally, should produce no false positives; should be sufficient for determin­ing brain death without other confirmatory tests; should be impervious to confounders; technology (and its inter­pretation) should be standardized among institutions; should be readily available and easily applied

EEG: used worldwide; one of best validated confirmatory tests available; however, some investigators consider EEG too anatomically and physically limited (not sensitive to signals from subcortical structures [eg, thalamus, brainstem]; does not faithfully capture all EEG frequencies); most studies powered to find false negatives, whereas false positives more important; test usually performed in intensive care unit, where other equipment present that may create artifacts and produce false negative results; study found that electrical brain activity may return after as long as 72 hr

Radionuclide angiography: imaging of posterior fossa and brainstem blood flow poor without specific views; may produce false negatives if perfusion restored by decompression of brain after complete neuronal death (less prob­lematic with technetium 99 and iodine 123)

CT angiography: readily available; good sensitivity with dye uptake; filling of extracranial circulation convenient control; however, study findings conflict; in some, CT did not always demonstrate brain death despite confirma­tion by neurologic and other methods; conclusion  —  CT angiography promising, but definitions of positive and negative confirmatory examinations for determining brain death must be further refined

Atropine test: failure of heart rate to increase >3% over baseline after atropine administration indicates death of dorsal vagal nucleus in medulla

Clinical trial at University of New Mexico: prospective randomized controlled trial of family presence at bedside during brain death evaluation; goal is to minimize relatives’ confusion and distress when brain death declared; also some evidence that presence of family member beneficial during trauma and cardiac resuscitation and other proce­dures; extra support staff needed for family members, but little evidence confirming clinicians’ other concerns (eg, physical or verbal interference from family members, increased risk for litigation; evidence suggests trend toward decreased litigation); end points of study  —  1) effect of presence at time of determination on family’s understanding of brain death; 2) effect on distress level of family members at 1 mo; 3) effect on willingness to give consent for or­gan donation

Suggested Reading

[No authors listed]: A definition of irreversible coma. Report of the Ad Hoc Committee of the Harvard Medical School to Exam­ine the Definition of Brain Death. JAMA 205:337, 1968; Bruce J et al: Systematic review of the definition and measurement of anastomotic leak after gastrointestinal surgery. Br J Surg 88:1157, 2001; Choy PY et al: Stapled versus handsewn methods for il­eocolic anastomoses. Cochrane Database Syst Rev Jul 18:CD004320, 2007; Combes JC et al: Reliability of computed tomo­graphic angiography in the diagnosis of brain death. Transplant Proc 39:16, 2007; Demetriades D et al: Penetrating colon injuries requiring resection: diversion or primary anastomosis? An AAST prospective multicenter study. J Trauma 50:765, 2001; Golub R et al: A multivariate analysis of factors contributing to leakage of intestinal anastomoses. J Am Coll Surg 184:364, 1997; Miller PR et al: Improving outcomes following penetrating colon wounds: application of a clinical pathway. Ann Surg 235:775, 2002; Mollaret P, Goulon M: The depassed coma (preliminary memoir). Rev Neurol (Paris) 101:3, 1959; Nair A et al: Predict­ing anastomotic disruption after emergent small bowel surgery. Dig Surg 23:38, 2006; Powell T et al: Variability of brain death determination guidelines in leadingi US neurologic institutions. Neurology 71:1839, 2008; Young GB et al: Brief review: the role of ancillary tests in the neurological determination of death. Can J Anaesth 53:620, 2006.