What the Anesthesiologist Should Know before the Operative Procedure
Intra-abdominal adhesions develop as a result of abdominal surgery (laparotomy or laparoscopic) or less commonly from inflammatory conditions. In fact, adhesions are the most common etiology for small bowel obstruction. While many patients who develop adhesions can be managed conservatively, some will require surgery for lysis of adhesions.
Adhesions may cause abdominal pain, nausea, vomiting, and bowel obstruction. Major management issues include pain control, fluid resuscitation, and correction of electrolyte and metabolic derangements. For patients who develop ischemic bowel as a result of adhesions, these issues must be addressed expeditiously.
1. What is the urgency of the surgery?
What is the risk of delay in order to obtain additional preoperative information?
Early postoperative bowel obstruction (occurring within 30 days) develops in less than 5% of cases. The majority of these cases are managed conservatively (for up to 2 weeks), as the adhesions generally resolve. Emergent surgery is indicated for those patients that develop strangulated bowel. These patients may present with peritoneal signs, fever, leukocytosis, hemodynamic instability (tachycardia/hypotension), and metabolic acidosis. A CT scan of the abdomen can assist in establishing the diagnosis.
Emergent: Adhesions that cause strangulated bowel. These patients may benefit from preoperative admission to the intensive care unit for resuscitation.
Urgent: For patients with suspected bowel obstruction who fail conservative therapy, surgery may be indicated. Again, volume depletion and electrolyte/metabolic disorders is should be corrected prior to surgery.
Elective: Adhesions thought to contribute to abdominal pain. Evidence suggests that elective adhesiolysis for adhesions causing abdominal pain may lack efficacy (for example, in patients with chronic pelvic pain). In these patients, obtaining adequate pain control may be the major issue.
2. Preoperative evaluation
Adhesions may cause abdominal pain, nausea, and vomiting. Vomiting may lead to dehydration, electrolyte imbalance, and acid-base disorders. The clinical assessment of volume status is of primary importance. Patients whose adhesions have resulted in long-term vomiting may present with significant volume depletion. The physical exam reveals decreased skin turgor, dry mucous membranes, and decreased jugular venous distention. Hypotension may be present with progressive volume depletion. Tachycardia and hypotension may cause a demand-type cardiac ischemia. Electrolyte disorders are common and metabolic acidosis may be present in cases of strangulated bowel. Acute kidney injury is possible from hypovolemic hypotension.
Medically unstable conditions warranting further evaluation include the following: With cases of suspected strangulated bowel, emergency surgery should proceed as soon as possible. Mortality from gangrenous strangulated bowel is high if surgery is delayed. Therefore, prompt attention to correcting fluid, metabolic, and electrolyte disorders is indicated.
Delaying surgery may be indicated if a patient presents with hypovolemic hypotension, significant electrolyte, and metabolic disorders. In these patients, preoperative admission to the intensive care unit for fluid resuscitation and correction of electrolytes and metabolic derangements may reduce the hemodynamic complications associated with the induction of general anesthesia.
3. What are the implications of co-existing disease on perioperative care?
Patients with active comorbidities are higher risk for perioperative complications. Depending on the urgency of surgery (i.e., patients with suspected strangulated bowel from adhesions), there may be limited time to stabilize these issues prior to surgery.
For patients scheduled for urgent or elective procedures, optimizing comorbid conditions will help to reduce the risk of perioperative complications. Medical clearance may not be necessary and appears to depend on institution-specific policies. In general, patients with preexisting neurologic, cardiac, pulmonary, and renal disease should be well controlled. Available medical records and an up-to-date medication list need to be obtained. Standard preoperative evaluation of cardiac risk using the American Heart Association/American College of Cardiology guides additional testing.
Perioperative risk reduction strategies
For patients at risk for cardiac complications, perioperative beta blockade may be considered. Caution should be observed in continuing ACE inhibitors and angiotensin receptor blockers in dehydrated patients and for procedures with expected significant volume shifts.
b. Cardiovascular system
Depends on the urgency of surgery. Patients with acute coronary syndrome, active congestive heart failure, or significant rhythm disorders should be managed in collaboration with a cardiologist.
Baseline coronary artery disease or cardiac dysfunction – Goals of management
Optimize heart rate and blood pressure. A five-lead ECG with ST-segment monitoring will assist in detecting rhythm changes and ischemia. Additional invasive and noninvasive monitoring is considered for patients at high risk for cardiac complications.
Severity of disease based on oxygen and steroid requirements. Review pulmonary function tests and radiographs if available. Continue preoperative inhalers.
Reactive airway disease (Asthma)
Continue preoperative inhaler regimen. Monitor for bronchospasm.
Obstructive sleep apnea (OSA)
If likely undiagnosed OSA, consider postoperative pulse oximetry and close monitoring on a telemetry floor or intensive care unit, especially for patients who will require narcotics. For patients with established OSA, have patient bring own machine and assess settings and fit of apparatus.
Evaluate baseline BUN and creatinine. Patients who present with hypovolemia are at increased risk for perioperative acute kidney injury.
Review past abdominal operations and radiographs (plain abdominal films and CT scan) with surgeon. Determine whether a bowel obstruction (either partial or complete) is suspected and whether bowel is at risk for strangulation/ischemia.
Patients with a history of ischemic stroke or carotid stenosis require careful intraoperative blood pressure monitoring. Consideration should be given to maintaining adequate cerebral perfusion pressure.
For patients scheduled forurgenAcute issues (recent stroke, intracerebral hemorrhage, or seizure): Obtain neurologic consultation prior to case to determine appropriate timing of surgery.
Chronic disease: The risk of discontinuing antiplatelet medications should be weighed against the risk of perioperative bleeding.
Patients with chronic steroid use may require pre-operative administration of a corticosteroid, “stress dose,” to attenuate the risk of hypotension from surgical stress.
g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)
4. What are the patient's medications and how should they be managed in the perioperative period?
The decision to hold or continue a medication is individualized and depends on the systemic problems caused by the adhesions and the urgency of surgery. For example, for patients with nonurgent surgery without bowel obstruction, most medications can be continued during the perioperative period. For patients with suspected strangulated bowel and associated volume depletion, and electrolyte/metabolic issues, care should be taken to avoid medications that may exacerbate hypotension with general anesthesia.
h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?
This may include medications specific to diseases associated with surgery. Use caution with continuing anti-hypertensive medications (e.g., ACEIs or ARBs) in patients who are hypovolemic or have anticipated large fluid shifts associated with surgery.
i. What should be recommended with regard to continuation of medications taken chronically?
For cases of suspected bowel obstruction and for those patients not able to tolerate PO, convert oral medications for intravenous administration.
Continue, with considerations on holding for volume depletion.
Continue all inhalers.
Continue antiepileptics, consider checking levels as appropriate. Continue Parkinson’s medications.
Continue levothyroxine and steroids (or substitute with intravenous stress dose).
Assess on individual basis and weigh bleeding risks from surgery versus risk for perioperative stroke or myocardial infarction.
Continue if poorly controlled depression or other psychiatric illness.
j. How To modify care for patients with known allergies –
k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.
l. Does the patient have any antibiotic allergies- – Common antibiotic allergies and alternative antibiotics]
m. Does the patient have a history of allergy to anesthesia?
Documented: avoid all trigger agents such as succinylcholine and inhalational agents:
Proposed general anesthetic plan:
Ensure MH cart available [MH protocol]
5. What laboratory tests should be obtained and has everything been reviewed?
Hypovolemia, which can occur in the setting of bowel obstruction, may effect electrolyte and metabolic conditions. Specific abnormalities are discussed below.
Hemoglobin and hematocrit levels may be elevated as a result of decreased plasma volume (hemoconcentration).
Serum sodium may be elevated (from insensible losses or diabetes insipidus) or low (SIADH), depending on the etiology. Serum potassium may be elevated, but is more commonly low as a result of GI or urine losses. Serum calcium, magnesium, and phosphate levels should be checked and supplemented as necessary.
Hypovolemia usually results in a low urine sodium. A fractional excretion of sodium is <1%. Urine osmolality is concentrated.
PT/INR, PTT, and platelet count. Additional work-up as appropriate for patients with a bleeding diasthesis.
Plain abdominal films and CT scans of the abdomen and pelvis.
BUN and creatinine should be reviewed. A ratio of BUN/Cr >20:1 is one clue to suggest hypovolemia.
An arterial blood gas may reveal a hypochloremic, hypokalemic metabolic alkalosis for patients with emesis. However, for patients with strangulated bowel, a metabolic acidosis with an elevated serum lactate may be present.
Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?
A general anesthetic is typical for either a laparotomy or laparoscopic approach to lysis of adhesions. For appropriate patients, epidural analgesia can provide excellent pain control. In addition to standard ASA monitors, invasive monitors should be considered for patients who present with hypovolemic shock or suspected strangulated bowel. Invasively monitoring central venous pressures or arterial blood pressures may help to guide fluid resuscitation. Newer, noninvasive methods, such as the NICOM monitor, may assist fluid management. Adequate intravenous access is important. Urine output should be measured with a Foley catheter.
Epidural analgesia may be effective for postoperative pain control after a laparotomy, especially for those patients with chronic pain. For patients who present hemodynamically unstable with small bowel obstruction, epidural analgesia should be deferred.
Benefits: Potentially improved pain control with earlier ambulation and return to bowel function.
Drawbacks: Hypotension is a concern for patients who are hypovolemic. Usual contraindications as outline in recent ASRA guidelines apply.
Issues: Need to discuss postoperative anticoagulation regimen with surgical team. Placement and removal of an epidural catheter should follow ASRA recommendations.
Peripheral nerve block
A transversus abdominus plane block (TAP) is used with relatively high success rates in reducing postoperative pain following a laparotomy. This is a basic block when combined with ultrasound guidance and may be helpful for those patients who remain with high pain scores after significant narcotic administration.
Benefits: Easy to learn and perform. Associated with good reduction in pain scores.
Drawbacks: Requires ultrasound and basic regional anesthesia skills.
Issues: For obese patients, determining fascial planes can be challenging. Incision and dressings may interfere with placement.
b. General Anesthesia
Benefits: Provides a secure airway and excellent muscle relaxation to facilitate exposure.
Drawbacks: May induce hemodynamic instability in hypovolemic patients.
Airway concerns: Assume full stomach and induce using a rapid sequence technique. The application of cricoid pressure has come under debate recently and should be used at the discretion of the practitioner.
c. Monitored Anesthesia Care:
Not considered an option
6. What is the author's preferred method of anesthesia technique and why?
A general anesthetic is administered to patients who receive either a laparotomy or laparoscopy. We would consider placing an epidural catheter for postoperative analgesia in the appropriate patient. In addition, for patients without an epidural having significant pain requirements, we would consider a placing a postoperative TAP block.
What prophylactic antibiotics should be administered?
For intra-abdominal surgery not involving the colon or rectum, cefazolin is preferred. For patients with penicillin or cephalosporin allergies, clindamycin in addition to either ciprofloxacin, levofloxacin, or gentamicin. For surgery involving the colon or rectum, prophylaxis with cefoxitin or cefotetan is recommended. For allergic patients, clindamycin in addition to gentamicin or an intravenous fluoroquinolone is advised. These recommendations are based on the 2009 Surgical Care Improvement Project (SCIP).
What do I need to know about the surgical technique to optimize my anesthetic care?
Either a laparotomy or laparoscopic approach is used for lysis of adhesions. For laparoscopic cases, the cardiopulmonary changes associated with peritoneal insufflation may be exaggerated in patients who are underresuscitated.
What can I do intraoperatively to assist the surgeon and optimize patient care?
Close attention to fluid resuscitation and correction of electrolyte/metabolic derangements will improve outcome. Inadvertent enterotomy is a complication of the procedure.
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b. If the patient is intubated, are there any special criteria for extubation?
For patients who present with small bowel obstruction as a result of adhesions, extubation should be deferred until the patient is adequately fluid resuscitated and any electrolyte/metabolic disorders are corrected. Should the patient require significant fluid resuscitation, the presence of a cuff leak may provide evidence that swelling/airway edema is not compromising the airway.
c. Postoperative management
What analgesic modalities can I implement?
PCA opioid, epidural analgesia, or TAP block.
What level bed acuity is appropriate?
For patients with small bowel obstruction and ongoing fluid resuscitation, admission to the ICU. For other urgent, elective cases, admission to floor/telemetry depends on the control of patient comorbidities (example, a patient with OSA will require postoperative pulse oximetry and apnea monitoring).
What are common postoperative complications, and ways to prevent and treat them?
DVT prophylaxis should be started as soon as possible to reduce the risk of DVT/PE, especially in those patients who will not ambulate soon after surgery.
What's the Evidence?
Parker, MC, Ellis, H, Moran, BJ. “Postoperative adhesions: ten-year follow-up of 12,584 patients undergoing lower abdominal surgery”. Dis Colon Rectum. vol. 44. 2001. pp. 822
Beck, DE, Opelka, FG, Bailey, HR. “Incidence of small bowel obstruction and adhesiolysis after open colorectal and general surgery”. Dis Colon Rectum. vol. 42. 1999. pp. 241
Sabiston, DC, Lyerly, HK. “Textbook of surgery: the biologic basis of modern surgical practice”. 1997.
Hodin, RA, Bordeianou, L. “Small bowel obstruction: causes and management”. 2011.
Howard, F. “Causes of chronic pelvic pain in women”. 2011.
McDonnell, JG, O’Donnell, BD, Farrell, T. “Transversus abdominus plane block: A cadaveric and radiologic evaluation”. Reg Anesth Pain Med. vol. 32. 2007. pp. 399
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- What the Anesthesiologist Should Know before the Operative Procedure
- 1. What is the urgency of the surgery?
- What is the risk of delay in order to obtain additional preoperative information?
- 2. Preoperative evaluation
- 3. What are the implications of co-existing disease on perioperative care?
- b. Cardiovascular system
- c. Pulmonary
- d. Renal-GI:
- e. Neurologic:
- f. Endocrine:
- g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)
- 4. What are the patient's medications and how should they be managed in the perioperative period?
- i. What should be recommended with regard to continuation of medications taken chronically?
- j. How To modify care for patients with known allergies -
- l. Does the patient have any antibiotic allergies- - Common antibiotic allergies and alternative antibiotics]
- m. Does the patient have a history of allergy to anesthesia?
- 5. What laboratory tests should be obtained and has everything been reviewed?
- 6. What is the author's preferred method of anesthesia technique and why?
- a. Neurologic:
- b. If the patient is intubated, are there any special criteria for extubation?
- c. Postoperative management