Bowel Resection (Small and Large Bowels)

What the Anesthesiologist Should Know before the Operative Procedure

The anesthesiologist should know the following:

The indication for the bowel resection.

The degree of the urgency of the surgery.

The extent of the surgical incision and the extent of the resection.

Whether the patient had a mechanical bowel preparation.

The plan for DVT prophylaxis.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Delaying surgery to obtain further preoperative information and to medically optimize patients is appropriate in the case of elective surgery. The degree of urgency will dictate how much delay to obtain such information is appropriate. In case of intestinal obstruction, delay to replace the patient’s electrolyte and intravascular volume lost because of vomiting and diarrhea may be appropriate. In the case of bowel perforation and acute abdomen, surgical resection should proceed without delay. Consultation with the surgical team is very important in this regard.

Common indications for small bowel resection are intestinalobstruction, volvulus, intussusception, Crohn’s disease [IBD], smallbowel tumors, and trauma. Common indications for large bowel resectionare colon cancer, diverticulosis, Crohn’s disease, ulcerative colitis,lower gastrointestinal bleeding, and trauma. In terms of the urgency ofsurgery, indications can be classified as follows:

Urgent/Emergent: Perforated bowel, acute abdomen, ischemic gangrene of the intestine, and trauma.Patients can present with sepsis, acute abdomen with or without variabledegrees of hypotension, and perirectal abscesses. Consider preoperativevolume replacement and rapid sequence induction.

Elective: Diverticulosis malignant neoplasms, inflammatory bowel disease(IBD), and severe perianal fistulae. Consider the impact of bowel prepand the fluid deficit that the patient may present with.

2. Preoperative evaluation

Preoperative evaluation of patients undergoing bowel resection should include detailed history, physical examination, laboratory work, and radiological workup.

History should include details of patient comorbidities, exercise tolerance, and details about the present illness. Patients with IBD are usually on long-term steroids and/or immunosuppressants.

Physical examination should include system-focused examination as well as signs of dehydration. The presence of ascites and/or abdominal distention should be noted. Increased intra-abdominal pressure may increase peak inspiratory pressure on institution of positive pressure ventilation. The increased intra-abdominal pressure may act as a tamponade for intraperitoneal bleeding. Release of the tamponade effect may result in severe hypotension.

Lab work should evaluate electrolytes and coagulation tests, especially if epidural analgesia is planned. Derangements of the liver functions may result from metastases to the liver and liver failure.

Cardiac evaluation and imaging and imaging should be obtained based on institutional protocols according to the guidelines from the American College of Cardiology. Chest radiographs and pulmonary function tests are used for evaluation of lung function prior to surgery and to determine if there is a reversible component to the patient’s disease that can be treated by bronchodilator therapy.

In general, patients undergoing bowel resection fall into one of two categories. The first category is younger patients scheduled for bowel resection because of IBD. They are usually otherwise healthy. The other category is elderly patients scheduled for colon resection because of colon cancer. Associated comorbidities are more prevalent in this group of patients. Comorbidities include diabetes mellitus, hypertension, coronary artery disease (CAD), and chronic obstructive pulmonary disease (COPD). Preoperative evaluation should focus on (1) understanding the severity of these comorbidities and how they would impact the anesthetic management and (2) ensuring that the patient’s medical condition is optimized.

Medically unstable conditions warranting further evaluation include acute intestinal obstruction. Electrolyte disturbances and intravascular volume deficits should be corrected before surgery. Assessment of myocardial function and intravascular volume is important for a goal-directed perioperative management. Understanding the severity of associated pulmonary disease is crucial for your anesthetic plan.

Delaying surgery may be indicated if the indication for surgery is elective and you need more information about patient comorbidities and need to optimize the patient’s condition.

3. What are the implications of co-existing disease on perioperative care?

b. Cardiovascular system:

Acute/unstable conditions

• Gastrointestinal bleeding with the resulting anemia compromising the oxygen supply to the myocardium, especially in patients with CAD.

• Hypovolemia can result from bleeding and/or third spacing in the case of septicemia and when there is an acute abdomen. Intravascular volume should be optimized.

• Hypotension and tachycardia can also disturb the supply/demand ratio of the blood supply to the myocardium.

• Electrolyte disturbance can lead to arrhythmias and should be corrected.

Goals of management of patients with baseline CAD or cardiac dysfunction

• Optimize cardiac preload.

• Avoid hypotension, tachycardia, and anemia.

• Avoid volume overload: maintain normal temperature of patients under anesthesia to avoid the deleterious effect of hypothermia in the perioperative period.

c. Pulmonary:

COPD

Perioperative evaluation

History: Ask about exercise tolerance, shortness of breath, and dyspnea on exertion, as well as medication history and the frequency of bronchodilator inhalers, previous hospitalization, or ICU admission for COPD exacerbation.

Physical examination and chest auscultation can reveal classic signs of COPD or signs of infection (pneumonia).

Pulmonary function testing: Should be reserved for patients with severe pulmonary disease. Observe any improvement in the respiratory parameters with bronchodilator therapy.

Risk reduction strategies

Epidural analgesia has been shown to improve postoperative respiratory mechanics and reduce perioperative morbidity and mortality. Employ incentive spirometry and pulmonary toilet. Early mobilization should be encouraged.

Reactive airway disease (asthma)

Perioperative evaluation

Evaluation should include detailed history of the asthma, frequency of the attacks, medication, prior hospitalization, and ICU admission for exacerbation.

Risk reduction strategies

Maintain the routine daily medication doses. Provide preoperative nebulizer treatment with albuterol. Avoid histamine-releasing agents (morphine, atracurium).

d. Renal-GI:

Hypovolemia

Perioperative evaluation

• Mechanical bowel preparation prior to the scheduled surgery should alert the anesthesiologist to account for the volume lost during the process.

• Look for symptoms and signs of hypovolemia, which include decreased urine output, loss of skin turgor, collapsed neck veins, and dry mucous membranes.

• Laboratory values: check elevated BUN and/or creatinine for impaired kidney functions. Functional excretion of sodium (FENA) can differentiate prerenal causes of impaired kidney functions (hypovolemia) from renal causes (intrinsic kidney disease).

• Acidosis can result from hypovolemia and persistent hypotension. It can also result from decreased perfusion of the intestine in cases of bowel ischemia.

Perioperative evaluation

Maintain perioperative hydration. Fluid therapy should be guided by central venous pressure, urine output, and trends of other hemodynamic parameters.

Delayed gastric emptying

• Consider rapid sequence induction in cases of intestinal obstruction and other conditions associated with delayed gastric emptying.

• Avoid metoclopramide for treatment of nausea and vomiting in mechanical intestinal obstruction

Electrolyte abnormalities can also occur if the patient is receiving prolonged total parenteral nutrition (TPN).

e. Neurologic:

Acute issues

Nerve injury

Common peroneal nerve injury has been reported after lithotomy position. Preoperative history and physical should document any preexisting neurologic disease, existing neuropathy, and its distribution.

Risk reduction strategies: Careful positioning and padding of pressure points, especially in obese patients

Perioperative stroke

Factors associated with increased perioperative risk of cerebrovascular stroke include atrial fibrillation, hypertension, diabetes mellitus, history of previous stroke, carotid artery stenosis, and peripheral vascular disease.

Epidural hematoma

If epidural anesthesia is planned, check for coagulation profile and review the perioperative plan for DVT prophylaxis.

Risk reduction strategies: Frequent postoperative neurologic checks should be documented. Use a lower concentration of local anesthetic in the epidural continuous infusion to avoid dense motor block and facilitate neurologic examination.

Chronic disease

Patients with old stroke may be at risk for hyperkalemia if succinylcholine is used to facilitate rapid sequence induction.

Patients receiving antiseizure medication may require higher doses of neuromuscular blockers because of the induction of the liver enzyme systems.

f. Endocrine:

Diabetes

Management of diabetes should be according to institutional protocol. In general, blood glucose control should be maintained with regular insulin in the perioperative period. The patient should refrain from taking their morning dose of insulin as well as their morning dose of oral hypoglycemic agents. Frequent blood glucose checking is a safe mechanism to protect against hypoglycemia if tight glycemic control is adopted as a strategy. More liberal strategies have been suggested to keep BGL <180 mg/dL. This was shown to decrease mortality in critically ill patients.

Patients scheduled for resection due to IBD are usually taking steroids for treatment. Consider administration of an intravenous stress dose of steroids preoperatively.

Carcinoid tumors of the small intestine follow a more benign clinical course than do most other malignancies. Symptoms include flushing, diarrhea, and bronchoconstriction. Humoral manifestations of carcinoid syndrome could be attributed to the overproduction of serotonin by these tumors. However, serotonin is not the only mediator of the clinical syndrome. Other substances, such as the tachykinins, play a significant role in the different clinical characteristics of affected patients.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Adequate intravenous access should be established prior to induction of general anesthesia. If TPN is planned after surgery, consider insertion of central venous access after discussion with the surgical team.

4. What are the patient's medications and how should they be managed in the perioperative period?

Chronic pain medication should be continued as needed until the morning of surgery. Patients with chronic pain syndromes will have increased requirement of narcotics and the plan for postoperative analgesia should be modified accordingly.

The most commonly used over-the-counter medication and herbals, from highest to lowest, include echinacea, gingko biloba, St. John’s wort, garlic, and ginseng. These supplements may cause bleeding, platelet dysfunction, and altered metabolism of other drug classes. It is recommended that these supplements should be stopped 2 to 3 weeks before surgery to avoid their potential side effects.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

In general, no specific class of medications are encountered more frequently in patients undergoing bowel resection relative to other procedures.

Patients with IBD are usually taking steroids. Steroids should be continued until surgery. A stress dose of steroids should be given before surgery to cope with the stress of surgery and anesthesia.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac

Most antihypertensive medication should be continued till the morning of surgery. Beta-blockers should be continued throughout the perioperative period. Calcium channel blockers should be continued until the morning of surgery. It may be prudent to discontinue angiotension-converting enzyme inhibitors (ACEIs) or angiotension receptor blocking agents (ARBs) 12 to 24 hours prior to surgery, especially if the patient is taking different classes of medication for hypertension and their blood pressure is well controlled.

Pulmonary

Albuterol and other bronchodilator should be continued until surgery. Sometimes, it is recommended to give one dose of inhaled albuterol before induction of anesthesia.

Renal

The practice is variable when it comes to recommending stopping or continuing loop diuretic before surgery. The concern is the increased risk of intraoperative hypotension.

Neurologic

Antiseizure medication should be continued. Anti-parkinsonism drugs should be continued.

Antiplatelet

Aspirin is recommended to be stopped 1 week before surgery but discussion should occur if aspirin is being taken for stroke or significant CAD.

Ticlopidine and clopidogrel are recommended to be stopped 1 week before surgery. There has to be a discussion between the patients, the anesthesiologist, the cardiologist, and the surgeon regarding stopping clopidogrel prior to surgery and when to restart it depending on the indication of the drug.

Dipyridamole is recommended to be stopped 1 week before surgery

Psychiatric

Antipsychotic medication should continue throughout surgery. The benefits of continuing MAOIs should be weighed against the risk of interaction of these drugs with some anesthetic agents. Input from the psychiatrist is very important. Other classes of antidepressants (SSRIs) can be safely administered until surgery.

Oral hypoglycemic

Discontinue the morning of surgery.

j. How to modify care for patients with known allergies

Most concerning is the antibiotic allergy. The specific class of the offending antibiotic should be avoided. Suitable alternative with similar microbial coverage should be given.

k. Latex allergy – If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

The vast majority of anesthesia equipment and circuits are latex free. If the patient is presenting with history of latex allergy and/or sensitivity, avoid using any components of the anesthesia circuit that contains latex. Communicate this information to the OR staff and make sure that all surgical gloves used are latex free as well. If the patient developed anaphylactic reaction to latex, epinephrine is the drug of choice for treatment. Steroids and antihistamines may be helpful as well.

l. Does the patient have any antibiotic allergies – Common antibiotic allergies and alternative antibiotics

Patients with allergy to penicillin should be given vancomycin or clindamycin. There is a cross reaction between penicillin and cephalosporin in a small percentage of patients. Most practitioners would prefer to avoid cephalosporins all together in patients with penicillin allergy. Vancomycin or clindamycin is a reasonable alternative. Vancomycin should be given over 60 minutes to avoid histamine release associated with rapid infusion of vancomycin (red man syndrome).

m. Does the patient have a history of allergy to anesthesia?

Often, this is a vague statement and needs further investigation. Malignant hyperthermia, cholinesterase deficiency, and allergy to nondepolarizing muscle relaxants are the most cited allergy to anesthesia by patients. Review previous anesthesia record or hospital notes for more detailed information.

Malignant hyperthermia (MH)

MH is a life-threatening hypermetabolic condition resulting from a genetic sensitivity of skeletal muscles to volatile anesthetics and depolarizing neuromuscular blocking drugs. The incidence is around 1:50,000 anesthetics in adults and 1:15,000 in children. If the patient has a documented diagnosis of MH, avoid all trigger agents such as succinylcholine and inhalational agents.

Signs of ML

• • Increasing ETco2

• • Trunk or total body rigidity

• • Masseter spasm or trismus

• • Tachycardia/tachypnea

• • Mixed respiratory and metabolic acidosis

• • Increased temperature (late sign)

• • Myoglobinuria

Proposed general anesthetic plan

• · Premedication: midazolam 1 to 2 mg

• · A fresh anesthesia machine that has not been used that day. The soda lime in the canisters should be replaced. Traces of inhalational agents may still be traced in machines with closed circuit.

• · An epidural catheter may be offered for postoperative analgesia.

• · Induction: Propofol 1 to 2 mg/kg, fentanyl 1 to 2 mcg/kg can be used.

• · Nondepolarizing muscle relaxants (vecuronium or rocuronium) can be used to facilitate tracheal intubation.

• · Maintenance of anesthesia can be achieved through total intravenous anesthesia (TIVA). Propofol 100 to 120 mcg/kg/min can be used. Intermittent blouses of fentanyl (50 mcg) can be used during maintenance of anesthesia. Alternatively, remifentanil infusion (0.1 to 0.2 mcg/kg/min) can be used.

• · Reversal of muscle relaxants with neostigmine 50 to 75 mcg/kg and glycopyrolate 0.2 mg for each 1 mg of neostigmine.

• · Infusion of local anesthetic and narcotic through the epidural can be used to achieve postoperative analgesia. Commonly bupivacaine 0.1% and fentanyl 2 mcg/mL can be used for the epidural PCA. Suggested starting doses can be 6 mL/hr with demand boluses of 5 mL every 60 minutes.

Ensure MH cart is available. Familiarize yourself with location of the cart. Education about MH should be part of the orientation of the new employees in the operating room and part of their periodic competencies. The cart should include dantrolene sodium, sterile water for injection, mannitol, sodium bicarbonate, furosemide, 50% dextrose 50-mL vials, Regular Insulin.

Family history or risk factors for MH

Family history of MH or history of certain muscle dystrophy (Duchene muscle dystrophy) should prompt preoperative testing. Muscle biopsy and genetic testing are the main tests. Muscle biopsy is subjected to caffeine halothane contracture test.

Local anesthetic and muscle relaxants

Anaphylaxis to muscle relaxants appears to be mediated through IgE-dependent mechanisms of mediator release. The serum IgE binding sites of the drugs appeared to be the ammonium ion determinants.

Allergy to local anesthetic (LA) seems to be more prevalent in the ester LA more than the amide group. There is no cross-reactivity between the two groups of LA. Allergy to ester LA is due to a para-aminobenzoic acid (PABA) metabolite. Amide agents do not undergo such metabolism. However, preservative compounds (methylparaben) used in the preparation of amide-type agents are metabolized to PABA. Intradermal skin testing of local anesthetic compounds and methylparaben should be performed in patients when a thorough history does not rule out a possible allergic reaction to local anesthetics and future local anesthesia is necessary.

5. What laboratory tests should be obtained and has everything been reviewed?

Lab tests include complete blood count, metabolic panel (sodium, potassium, blood urea nitrogen, creatinine, CO2, chloride, and glucose). Coagulation profile is necessary if epidural is planned. Additional lab tests may be obtained conditional on associated comorbidities (e.g., thyroid function tests in hyperthyroidism).

• Hemoglobin levels: males (13.5 to 16.5 g/dL), females (12 to 15 g/dL)

• Electrolytes: sodium (135 to 147 mEq/L), potassium (3.5 to 4.2 mEq/L), magnesium (1.6 to 2.4 MEq/L), and calcium (8.8 to 10.3 mg/dL)

• Coagulation panel: prothrombin time (PT) = 11.0 to 12.5 seconds, partial thromboplastin time (PTT) = 25 to 50 seconds, international normalized ratio (INR) = 1

• Imaging: Chest radiograph is indicated only if there are clues from the history and physical about pulmonary pathology.

Stress test is indicated if the patient is symptomatic for CAD (chest pain and/or shortness of breath at rest or during exercise) and has not been tested in the past 2 years or has not been revascularized in the past 5 years. Stress test is also indicated if the patient is revascularized and has new-onset symptoms.

Ultrasound of the abdomen and pelvis and CT scan of the abdomen are both usually obtained prior to surgery as part of the diagnostic procedures. Hydronephrosis can be seen if the colonic mass is obstructing one or both ureters.

Other tests include thyroid and liver function.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

Typically, general anesthesia (GA) is used. Muscle relaxation is often needed and best obtained through muscle relaxants. GA offers the advantage of control over the airway and renders the patient more comfortable, especially during a long procedure. The advantage of airway control is particularly evident if the indication for the resection is bowel obstruction, as rapid sequence induction should be instituted to guard against aspiration of gastric contents. In theory, the resection can be also done under regional anesthesia (spinal and/or epidural), especially in cases where there is only lower abdominal incision. However, the level of the sensory analgesia has to be high enough to abolish the sensation from traction on the mesentery.

Regional anesthesia is not an option when the indication for resection is emergent (e.g., bowel perforation and or trauma). Patients are usually supine for the resection. Often the resection involves some pelvic or perineal work (e.g., low anterior resection), which requires lithotomy position. Common peroneal nerve injury is the most commonly reported injury during lithotomy position. Paraesthesia in the distribution of the obturator of the sciatic nerve has been reported.

a. Regional anesthesia

Neuraxial

Often used as an adjunct for general anesthesia and for postoperative analgesia.

Benefits: Include less use of narcotics, superior postoperative analgesia, and better pulmonary function and respiratory mechanics.

Drawbacks: Include hemodynamic consequence (hypotension) subsequent to possible sympathectomy; the risk of epidural hematoma during insertion of the needle and removal of the catheter; and a tendency to keep the urinary catheter as long as the patient has his/her epidural with associated risk of urinary tract infection. If a high concentration is used, the patient may not be able to ambulate without assistance after surgery because of motor weakness.

Issues: Neuraxial narcotics can be administered as a single-shot intrathecal narcotics. Cephalad spread of water-soluble narcotics (morphine) may result in delayed respiratory depression. The risk of respiratory depression is increased in patients taking simultaneous systemic narcotics. The patient has to be monitored postoperatively for this reason.

Peripheral nerve block

Recently, transversus abdominis plane block (TAP) block has been described and suggested as an option for postoperative analgesia. The block has been compared to epidural analgesia in some studies for lower abdominal incisions. Injection of local anesthetic into the fascial plan of the transversus abdominis muscle layer cover the sensory supply of the spinal nerve (T7-L1). The approach is usually above the iliac crest bilaterally. Subcostal approach is beneficial in upper abdominal incisions.

A rectus sheath block can also be offered for complete analgesia for the upper abdominal midline skin incision.

Benefits: Include avoidance of neuraxial technique with the potential hemodynamic consequences and the risks of epidural hematoma.

Drawbacks: Sensory analgesia only covers skin, subcutaneous tissues, and muscle layers. Deep sensory signals are not covered by the TAP block.

Issues: The analgesia is limited by the duration of action of the local anesthetic. It has been reported to decrease narcotic requirements in the first 24 hours after surgery. More recently, some authors suggested insertion of bilateral TAP catheters for prolonged postoperative analgesia.

b. General anesthesia

Benefits:

Patients are comfortable. The airway is secured. Muscle relaxation is reliable, and invasive monitors can be applied with least convenienc

Drawbacks:

This is generally safe as long as patients’ comorbidities are accounted for.

Other issues:

There is typically a large fluid shift during the procedure. Intravenous fluid replacement has to take into account the fluids lost during bowel preparation as well as the insensible fluid loss from a large exposed surface area.

Airway concerns: Rapid sequence induction has to be instituted if the indication for the resection is bowel obstruction. Patients with history of difficult airway or patients with potentially difficult airway have to be identified preoperatively. Apply ASA algorithm for difficult airway.

Patients scheduled for exploratory laparatomy for intestinal obstruction often have a nasogastric tube (NGT) for drainage of gastric contents. Put the NGT to suction before proceeding with rapid sequence induction. Theoretically, the presence of NGT will prevent occlusion of the lower esophageal sphincter.

Avoid using nitrous oxide during the procedure. This is especially important in case of bowel obstruction. Nitrous can cause more distention of the closed bowel loop and make surgical exposure more difficult.

6. What is the author's preferred method of anesthesia technique and why?

We prefer to perform colon resection under GA; it is more reliable, the airway is secured, and muscle relaxation is optimal. We often choose epidural analgesia over systemic IVPCA in elective procedures. Postoperative pulmonary mechanics are better and the patient is able to use incentive spirometry, cough, and breathe deeply more effectively. We choose invasive monitors based on the patient’s comorbidities. Adequate intravenous access is very important in these cases. If peripheral intravenous access is not feasible, insert a central line for access and monitoring.

a. What prophylactic antibiotics should be administered?

One of the approaches to reducing the incidence of surgical complications in the Surgical Care Improvement Project (SCIP) to improve the timing, selection, and duration of prophylactic antibiotic administration, all of which are essential factors in effective prevention.

• Prophylactic antibiotic received within 1 hour prior to incision

• Prophylactic antibiotic selection for surgical patients

For colon resection

Oral

After effective mechanical bowel preparation, neomycin sulfate + erythromycin base

OR

Neomycin sulfate + metronidazole administered during 18 hours preoperatively

Parental

Cefotetan, cefoxitin, or cefmetazole

OR

Cefazolin + metronidazole; if beta-lactam allergy: clindamycin + gentamycin, or clindamycin + ciprofloxacin, or clindamycin + aztreonam

OR

Metronidazole with gentamycin, or metronidazole + ciprofloxacin

3. Prophylactic antibiotics discontinued within 24 hours after surgery end time

b. What do I need to know about the surgical technique to optimize my anesthetic care?

• The extent of the surgical incision. This knowledge will help determine the level if insertion of the epidural catheter.

• Plan for DVT prophylaxis

• The surgical approach, open versus laparoscopic. If laparoscopic approach is planned, epidural analgesia may not be indicated and the patient can do well with skin infiltration at the incision site with local anesthetic and intravenous systemic narcotics.

• The indication for the resection and the urgency of this indication, especially if the patient needs more preoperative testing

c. What can I do intraoperatively to assist the surgeon and optimize patient care?

Muscle relaxation is often required to optimize surgical exposure. Timely administration of preoperative antibiotics is often the responsibility of the anesthesia team. Typically, colon resection is not a major blood loss procedure. Cell Saver may be indicated in special circumstances (e.g., rare red cell antibodies or patient who is a Jehovah’s witness).

d. What are the most common intraoperative complications and how can they be avoided/treated?

Bleeding can occur due to inadvertent vascular injury. Patients should have blood available for transfusion. Adequate intravenous access has to be secured prior to the procedure. DVT and pulmonary embolus can present as hypoxia, tachycardia, and hypotension.

i. Cardiac complications

• Bleeding and hypovolemia

• Pulmonary embolism

• Acute myocardial ischemia

• Intraoperative arrhythmia due to electrolyte imbalance

• Volume overload can lead to congestive heart failure

ii. Pulmonary complications

• Aspiration during induction or during maintenance is especially pertinent in mechanical bowel obstruction. Treatment is supportive. Lavage, antibiotic therapy, and steroids have been suggested but proven to be ineffective.

• Pulmonary atelectasis can result from aspiration or inadequate ventilation.

iii. Neurologic complications

• The incidence of postoperative stroke is no higher than any other non-cardiac surgery. Patient predisposing factors are hypertension, atrial fibrillation, and previous stroke.

• Nerve injury due to positioning.

IV. Complications unique to the procedure

• Anastomotic leakage: can lead to peritoneal soiling which may require re-operation and complicate the postoperative course.

• Extensive resection can lead to short gut syndrome which is characterized by malabsorption syndrome and electrolyte disturbance.

• Ureteric injury and/or transection: the anatomical close proximity of the ureters to the site of surgery may result in this complication. Monitor UOP and report to the surgeons any slowing down of the urine flow. Often time, urologist will put ureteral stents prior to surgery to help identify the ureters intraoperatively. You may be asked to inject Methylene Blue intravenous to identify the ureters and see if a dye leakage into the field.

b. If the patient is intubated, are there any special criteria for extubation?

General extubation criteria are applied in the case of colon resection. Patients have to be awake, following commands, and have adequate muscle power. They also should be hemodynamically stable and their respiratory mechanics are adequate.

c. Postoperative management

1. What analgesic modalities can I implement?

a. Epidural analgesia: Infusion of local anesthetic and/or narcotic in the epidural catheter. This can be done either as a continuous infusion or as a patient controlled (epidural PCA).

b. Systemic narcotics: Often prescribed as IVPCA. Common narcotics used are morphine, and hydromorphone.

2. What level of bed acuity is appropriate?

Mainly dependent on the patient comorbidities and the acuity of the indication of the surgical procedure. Routine elective bowel resection in fairly healthy patients often cared for in a regular floor.

Patients who have OSA are better cared for in a monitored setting.

3. What are common postoperative complications, and ways to prevent and treat them?

• Pulmonary: postoperative atelectasis and pneumonia. Adequate postoperative analgesia and pulmonary physiotherapy are vital for prevention of postop pulmonary complications.

• Postop DVT/PE: patients should be given DVT prophylaxis according to institutional protocol and based on their individual risk factors for development of DVT.

• The incidence of postoperative delirium is not especially higher after bowel resection compared to other noncardiac surgery. Team oriented approach has been suggested. Pharmacologic treatment may include haloperidol and benzodiazepines.

• Epidural analgesia does not reduce mortality after colon surgery. It may improve functional recovery postoperatively.

What's the Evidence?

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“Practice guidelines for acute pain management in the perioperative setting: an updated report of the American Society of Anesthesiologists Task Force on Acute Pain Management”. Anesthesiology. vol. 100. 2004. pp. 1573-81.

Wu, Cl, Rowlingson, AJ, Herbertb, R, Richman, J, Andrews, R, Fleisher, LA. “Correlation of postoperative epidural analgesia on morbidity and mortality after colectomy in Medicare”. J Clin Anesth. vol. 18. 2006. pp. 594-9.

Siddiqui, MRS, Sajid, MS, Uncles, DR, Cheek, L, Baig, MK. “A meta-analysis on the clinical effectiveness of transversus abdominis plane block”. J Clin Anesth. vol. 23. 2011. pp. 7-14.

Horlocker, T, Wedel, D, Rowlingson, J. “Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (third edition)”. Reg Anesth Pain Med. vol. 35. 2010. pp. 64-101.

Fleisher, LA. “ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines”. J Am Coll Cardiol. vol. 50. 2007. pp. e159-241.

Rosenberg, H, Davis, M, James, D, Pollock, N, Stowell, K. “Malignant hyperthermia”. Orphan J Rare Dis. vol. 24. 2007. pp. 2-21.

Gilbert, DN, Moellering, RC, Sande, MA. The Sanford guide to antimicrobial therapy. 2001. pp. 116-17.

Bokey, E, Chapuis, C, Fung, C, Hughes, C, Koorey, S, Brewer, D, Newland, R, Yanek, S. “Postoperative morbidity and mortality following resection of the colon and rectum for cancer”. Dis Colon Rectum. vol. 38. 1995. pp. 480-7.

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