Anesthesia for Abdominal Surgery - Anesthetic Considerations for Specific Abdominal Procedures

Laparoscopic surgery

Laparoscopic approaches are utilized for an increasing number of surgical procedures including appendectomy, cholecystectomy, hernia repair, fundoplication, nephrectomy, weight loss surgery, liver resection, and colon resection. Benefits of laparoscopic surgery include smaller incisions, reduced postoperative pain, decreased postoperative ileus, early ambulation, shorter hospital LOS, and earlier return to function.

  1. Operative technique involves intraperitoneal insufflation of CO2 through a needle inserted into the abdomen via a small incision. Insufflation typically increases intra-abdominal pressure to 12 to 15 mm Hg. Trendelenburg or reverse Trendelenburg positioning is often necessary to facilitate operative exposure.
  2. Anesthetic considerations
    1. Hemodynamic changes associated with laparoscopy are generally mediated by the intra-abdominal pressure related to pneumoperitoneum, volume of CO2 absorbed, intravascular volume status, patient positioning, and anesthetic agents. Mean arterial pressure and systemic vascular resistance generally increases with the creation of pneumoperitoneum due to catecholamine release and activation of the renin-angiotensin system. Patients with coexisting cardiac disease may be susceptible to the physiologic effects of pneumoperitoneum and manifest with decreased cardiac output and hypotension. Absorption of CO2 across the peritoneal surface typically causes hypercarbia and acidosis, thus increasing sympathetic nervous system stimulation and decreasing cardiac contractility.
    2. Reduction in functional residual capacity (FRC) associated with GA is compounded by the creation of pneumoperitoneum, and FRC may be further compromised by the Trendelenburg position and patient body habitus. Frequent recruitment and titration of positive end-expiratory pressure (PEEP) may be necessary to mitigate against alveolar collapse.
    3. Attention to cardiovascular function with positioning in steep Trendelenburg or reverse Trendelenburg is essential due to change in venous return.
    4. Embryonic channels between the peritoneal and pleural or pericardial cavities may open with increased intraperitoneal pressure, resulting in pneumomediastinum, pneumopericardium, and pneumothorax. Diffusion of gas cephalad from the mediastinum may lead to subcutaneous emphysema of the face and neck.
    5. Vascular or other internal organ injuries due to incorrect introduction of the needle or trocar may produce sudden blood loss and necessitate conversion to an open procedure and vascular repair to control bleeding.
    6. Clinically significant venous gas embolism is rare but may occur on induction of pneumoperitoneum if the needle or trocar is placed into a vessel or abdominal organ, or if gas is trapped in the portal circulation. The high capacity of blood to absorb CO2 and rapid elimination in the lungs increases the margin of safety in cases of accidental IV injection of CO2. Insufflation of gas under high pressure can lead to a “gas lock” in the vena cava and right atrium; this will decrease venous return and cardiac output and produce circulatory collapse. Embolization of gas into the pulmonary circulation leads to increased dead space, ventilation-perfusion mismatch, and hypoxemia. Systemic gas embolization (with occasionally devastating effects on cerebral and coronary circulation) may occur with massive gas entrainment or via a patent foramen ovale. Treatment is supportive and includes immediate cessation of gas insufflation, increasing FiO2 to minimize hypoxemia, positioning the patient in steep head-down left-lateral decubitus to displace gas from the right ventricular outflow tract (see Chapter 19), and inotropic right ventricular support.
  3. Anesthetic management. Although laparoscopic procedures have been performed under neuraxial techniques, GA is usually required for laparoscopy. Creation of pneumoperitoneum and steep Trendelenburg positioning may compromise ventilatory function and are generally not tolerated in an awake patient. Rescue IV and radial artery access may be limited by draping and position of the patient.

Robotic surgery

Robotic surgery is increasingly utilized as a telemanipulator technique in surgical specialties with the goal of affording the surgeon a higher degree of precision and control with purported benefits of decreased hospital LOS and improved postoperative recovery.

  1. Advantages of the robotic systems include affording surgeons’ true three-dimensional depth perception and magnification of the operative field. In addition, the system filters natural hand tremors and scales movements for precision work. Compared to laparoscopic surgery, the surgeon is afforded a cumulative six degrees of freedom of movement.
  2. Anesthetic considerations and management
    1. Positioning for robotic surgery often entails steep Trendelenburg positioning and intraperitoneal insufflation, which has the potential for serious physiologic derangements. Patients with coexisting cardiovascular, respiratory, intraocular, or central nervous system pathology may be considered for alternative approaches.
    2. Any lines, monitors, or patient-protective devices must be placed and secured beforehand as access to the patient is limited after robot positioning and engagement. Depending on the robotic model and equipment, the position of the operating table may need to be maintained stationary throughout the procedure.
    3. Deep neuromuscular blockade must be maintained until the robot is undocked at the end of the procedure. A continuous infusion of a nondepolarizing neuromuscular blocking agent may be indicated. The robotic arms have minimal flexibility, and any movement has the potential for serious morbidity to organs and vasculature. Sugammadex may be indicated to reverse deep neuromuscular blockade in a timely fashion.
    4. Vigilant assessment of patient positioning and padding is imperative as the patient is often in a steep position for several hours.
    5. Shoulder supports and other patient-protective devices for securing the patient on the operating table during steep positioning may create suboptimal conditions for airway access on induction.
    6. Steep Trendelenburg positioning and carbon dioxide pneumoperitoneum may have synergistic cardiovascular and respiratory effects.
    7. Abdominal contents are translocated cephalad with a corresponding reduction of FRC and lung compliance. Patients may be prone to ventilation-perfusion mismatch, increased peak airway pressures, and atelectasis.
    8. CVP, pulmonary artery pressure, and pulmonary capillary wedge pressure are increased and correspond to the degree of head-down tilt. Arterial vasculature compression increases systemic and pulmonary vascular resistance.
    9. Swelling of the face and upper airway may be seen with the steep and prolonged positioning. A restrictive fluid management strategy may be beneficial. A small period of reverse Trendelenburg at the end of the case may allow venous drainage of airway structures and may be particularly helpful in patients with difficult airways on induction.

Esophageal surgery

Esophageal surgery for gastroesophageal reflux disease can be performed via either an abdominal approach (see below) or a thoracic approach.

  1. The Nissen fundoplication is the most common surgical treatment for reflux disease. It involves wrapping the fundus of the stomach around the lower part of the esophagus. This creates a collar in which intragastric pressure serves to constrict the wrapped esophagus rather than push the gastric contents into the esophagus. Hiatal hernias, if present, are repaired at the time of surgery. This procedure is often performed using laparoscopic techniques to decrease the duration of postsurgical hospitalization.
    1. Anesthetic considerations. This procedure is performed most commonly with GA or combined GA-epidural (for open procedures). Patients who come to surgery often have been treated medically with proton pump inhibitors, H2-receptor antagonists, or prokinetic agents. These should be continued until the day of surgery. An RSI is generally indicated because of the high risk of gastroesophageal reflux and the potential for aspiration.
    2. An esophageal bougie may be placed to calibrate fundoplication; this ensures an adequate esophageal lumen to minimize postoperative dysphagia. The stomach or esophagus may be perforated by passage of the bougie or NG tube. With the laparoscopic method, the bougie is directed into the stomach by observation alone. Correct angulation of the esophagus or stomach during this maneuver is extremely important in preventing injury. The dilator or NG tube should be passed slowly and should be directly visualized. Particular attention should be paid to patients with esophageal strictures.

Gastric surgery

Gastric surgery for gastric cancer, lymphoma, and uncontrolled bleeding is usually performed with combined GA-epidural. The high likelihood of aspiration in these patients necessitates rapid-sequence intubation.

  1. Gastrectomy or hemigastrectomy with gastroduodenostomy (Billroth I) or gastrojejunostomy (Billroth II) is usually performed for gastric adenocarcinoma, lymphoma, or intractable bleeding from gastric or duodenal ulcers. Rarely, it is necessary in Zollinger-Ellison syndrome.
  2. Gastrostomy tube placement can be performed through a small upper abdominal incision or percutaneously with an endoscope. Local anesthesia with sedation is often adequate in the debilitated elderly patient, although some require GA.

Intestinal and peritoneal surgery

Indications for small bowel resection include infection, penetrating trauma, Crohn disease, obstructing adhesions, Meckel diverticulum, carcinoma, and infarction (from volvulus, intussusception, or thromboemboli). Patients are often hypovolemic and are considered to have a full stomach.

  1. Appendectomy is performed through a small lower abdominal incision or via laparoscopy. IV hydration before induction is indicated because fever, poor oral intake, and vomiting may produce hypovolemia. GA with rapid-sequence intubation is generally indicated. TAP blocks may be opioid sparing and can be considered as an adjuvant for this procedure.
  2. Colectomy or hemicolectomy is used to treat colon cancer, diverticular disease, Crohn disease, ulcerative colitis, trauma, ischemic colitis, and abscess. Emergency colectomy on unprepared bowel carries a high risk of peritonitis from fecal contamination. Some emergencies involving the colon are treated with an initial diverting colostomy, followed later by bowel preparation and elective colectomy. Patients must be evaluated for hypovolemia, anemia, and sepsis. All emergency colectomies and colostomies should be treated as if at risk for aspiration. Combination general/regional anesthetics are common, although epidural analgesia use is decreasing with laparoscopic techniques and the intraoperative use of adjuvants.
  3. Perirectal abscess drainage, hemorrhoidectomy, and pilonidal cystectomy are relatively noninvasive and brief procedures. Pilonidal cysts are excised with patients positioned prone; abscess drainage and hemorrhoidectomy can be performed in either a prone or a lithotomy position. If GA is used, deep planes of anesthesia or use of muscle relaxants may be necessary to achieve adequate sphincter relaxation. Hyperbaric spinal anesthesia can be used for procedures in the lithotomy position, whereas a hypobaric technique is useful for the flexed prone (jackknife) or knee-chest position. A caudal block may be performed for either position.
  4. Inguinal, femoral, or ventral herniorrhaphies can be performed under local anesthesia, regional anesthesia (spinal, epidural, caudal, or nerve block), or GA. Maximum stimulation and profound vagal responses may occur during spermatic cord or peritoneal retraction. Communication with surgeons is important, as they may need to reduce traction if necessary. Techniques to minimize coughing on emergence that can strain the repair are indicated, and deep extubation can be considered in patients where is not contraindicated (ie, difficult mask airway, difficult intubation, high risk of aspiration, etc).

Hepatic surgery

Hepatic surgery

  1. Partial hepatectomy is performed for hepatoma, unilobar metastasis of a carcinoma, arteriovenous malformation, or echinococcal cysts. Extensive hemorrhage should be anticipated and standard monitors are supplemented with placement of arterial and large-bore IV access and/or central venous catheters. Blood loss during hepatic parenchymal division can be reduced by temporary occlusion of portal venous and arterial inflow at the level of the hepatic pedicle (Pringle maneuver). Low CVP techniques have been shown to reduce blood loss during the case and improve survival. The CVP is generally kept in the range of 2 to 5 mm Hg. CVP essentially represents the back pressure which causes bleeding during the resection, since there are no valves between the right atrium and the liver. Fluids should be restricted with a goal of maintaining a nonzero urine output and an acceptable blood pressure (variable depending on patient). If fluid restriction is not adequate, nitrates and opioids can be used as well. Resuscitation of the patient after the resection is completed and hemostasis has been achieved is indicated. This can be guided by signs of hypovolemia such as the respiratory variation of arterial systolic pressure, arterial PPV, cardiac output, CVP, and stroke volume variation. The normal liver has considerable reserve, and extensive resection is required before clinical impairment of drug metabolism is evident. The effects of liver disease on anesthetic management are discussed in Chapter 5. Epidural or paravertebral catheters can be placed in patients with normal coagulation status.
  2. Transjugular intrahepatic portosystemic shunts (TIPS) procedure has replaced portacaval or splenorenal shunt procedure for patients with portal hypertension because of superior outcome. The procedure entails access of internal jugular vein (most on right side). A shunt between portal vein and hepatic vein will be created after verifying position with both contrast and pressure measurement. TIPS procedure can be performed under monitored anesthesia care, but is usually performed under GA. Although the anesthetic for a TIPS is simple, a high-level vigilance is required because of potential bleeding.

Biliary tract procedures

Biliary tract procedures

  1. Cholecystectomy is a common procedure performed via either open laparotomy or laparoscopic techniques. GA is favored for either technique. During laparoscopic cholecystectomy, the patient is placed in a steep reverse Trendelenburg position, and the gallbladder is dissected from the liver bed by using either cautery or laser. Muscle relaxants are required for adequate abdominal wall relaxation. The amount of hemorrhage is difficult to assess because of the limited field of view and high magnification of the laparoscope; heavy bleeding from the cystic or hepatic arteries may occur.
  2. Biliary drainage procedures include transduodenal sphincteroplasty for extensive choledocholithiasis; cholecystojejunostomy for distal common bile duct obstruction from pancreatic cancer; and choledochojejunostomy for chronic pancreatitis, stone disease, and benign strictures of the distal bile duct. Endoscopic and transhepatic techniques are increasingly common, but open surgical drainage is occasionally required. Blood loss is usually minimal but fluid loss may be significant.

Pancreatic surgery

Pancreatic surgery

  1. Although the initial treatment of acute pancreatitis is supportive, surgical intervention may be necessary for complications of pancreatitis. Surgical management is indicated for infected pancreatic necrosis and hemorrhagic pancreatitis unresponsive to resuscitation with blood products and correction of coagulopathy. Pancreatic pseudocysts may require drainage either surgically or via endoscopy. The cyst may be anastomosed to a Roux-en-Y limb of jejunum, the posterior wall of the stomach, or duodenum. Surgical intervention can produce significant bleeding and third-space fluid losses. In severe acute pancreatitis, activation of inflammatory mediators can produce sepsis and multiple organ dysfunction that require fluid resuscitation, mechanical ventilation, and vasopressor support.
  2. Pancreaticojejunostomy with gastrojejunostomy and choledochojejunostomy (Whipple procedure) is typically performed for resection of adenocarcinoma of the pancreas, malignant cystadenoma, or refractory pancreatitis confined to the head of the pancreas. These procedures have a high potential for hemorrhage and fluid loss. Epidural catheters and other regional techniques such as paravertebral blocks are generally helpful for postoperative pain control in the absence of contraindications. Intraoperative neurolytic celiac plexus blocks can be used in unresectable cases where significant postoperative pain is expected.

Splenectomy

Splenectomy may be performed emergently after blunt or penetrating trauma or electively for the treatment of idiopathic thrombocytopenic purpura or Hodgkin lymphoma. GA and muscle relaxation are required. Large-bore IV access is necessary because major blood loss requiring transfusion can be encountered. A combined epidural and general anesthetic technique is appropriate with the caveat that a sympathectomy may significantly potentiate hypotension from hemorrhage. Occasionally, a transthoracic approach to gain control of the hilar vessels of a very large spleen may be necessary. Splenectomy patients should receive polyvalent pneumococcal vaccine in the postoperative period.

Intraoperative radiation therapy

Intraoperative radiation therapy for pancreatic, colonic, or other carcinomas may be performed during laparotomy for primary resection or tumor debulking. Specially designed operating rooms have been constructed to facilitate intraoperative radiotherapy. The patients must be hemodynamically stable and have a stable ventilatory status as they are monitored by remote television outside the radiation area. Aortic or inferior vena cava (IVC) compression may occur when the sterile cone of the radiation therapy device is positioned in the abdominal wound. Ventilation with 100% oxygen can maximize the sensitivity of the tumor to radiation therapy. Treatments usually last just a few minutes and can be interrupted in the event of problems with hemodynamics or ventilation. Wound closure is performed after the radiation therapy is complete, and any necessary anastomoses are made.

Surgery for the obese patient

As the prevalence of obesity in the US population continues to rise, the perioperative management of the obese patient is increasingly relevant. Obesity is defined by the body mass index (BMI) and is calculated as follows: BMI = body weight (kg)/height (m2). Patients are typically defined as obese if BMI exceeds 30 kg/m2.

  1. Preanesthetic considerations
    1. Obese patients have increased circulating blood volume and cardiac output to meet increased oxygen consumption. Depressed left ventricular function related to left ventricular hypertrophy may be seen even in young asymptomatic patients and is often correlated to the duration of obesity.
    2. Obese individuals have an increased risk for cardiovascular disease and may require additional cardiac evaluation or consultation to optimize management in the perioperative period.
    3. Respiratory system compliance is decreased in obesity due to reduced chest wall compliance. FRC and expiratory reserve capacity are also likely to be reduced. In the supine position, FRC may be less than the closing volume, leading to ventilation-perfusion mismatch and hypoxemia. The higher metabolic demand of the obese person coupled with increased oxygen consumption and CO2 production necessitates an increase in minute ventilation to maintain normocapnia.
    4. Increased submucosal fat in the pharynx increases collapse of the hypopharynx with normal sleep, thus predisposing to obstructive sleep apnea. Long-standing hypoxemia may result in pulmonary hypertension and right heart failure. Obstructive sleep apnea increases the risk of perioperative complications and screening may be accomplished with validated tools including the STOP-Bang questionnaire.
    5. Increased gastric emptying time and elevated intra-abdominal pressure and volume predisposes to a higher incidence of symptomatic gastroesophageal reflux.
    6. Type 2 diabetes with hyperglycemia, hyperinsulinemia, and insulin resistance is common in obesity. Because perfusion of adipose tissue is variable, IV insulin infusions may be necessary to control hyperglycemia. Guidelines for the management of glucose and insulin are covered in Chapter 6.
    7. Airway management is a challenge in obesity including difficulty with intubation and mask ventilation. Careful assessment of neck and jaw mobility, inspection of the oropharynx, and examination of dental status are required. If intubation is expected to be difficult, an airway management strategy should be discussed and awake intubation considered.
    8. Positioning of the upper body with the external auditory meatus in line with the sternal notch has been shown to provide a better view for direct laryngoscopy. This is often accomplished by making a “ramp” of blankets under the thorax, which facilitates alignment of the thorax with the trachea. In addition, a reverse Trendelenburg position should be used in morbidly obese patients to increase FRC and utilize gravity to displace soft tissue away from the neck and airway.
  2. Surgical techniques. Bariatric surgery is currently the most effective treatment of morbid obesity. Patients with a BMI ≥ 40 kg/m2 or with a BMI ≥ 35 kg/m2 with obesity-related comorbidities may be candidates for surgery. Currently, two basic types of bariatric surgery are performed.
    1. Vertical banded gastroplasty (gastric sleeve) produces a small gastric pouch that restricts the volume of food that can be ingested. Long-term weight loss may be limited by maladaptive eating patterns (liquids with high caloric content) or by staple line disruption. Gastroplasty procedures, particularly the laparoscopic sleeve gastrectomy, are becoming increasingly popular due to lower complications than formal bypass procedures.
    2. Roux-en-Y gastric bypass surgery consists of formation of a small gastric pouch and anastomosis of the pouch to the proximal jejunum. Weight loss occurs due to both a restrictive anatomy as well as decreased absorption of calories because of the bypassed small intestine. Patients who undergo this surgery may experience a “dumping” syndrome in which ingestion of high-energy-density food leads to nausea, abdominal cramping, and diarrhea. The Roux-en-Y gastric bypass is often performed laparoscopically.
  3. Anesthetic management
    1. Standard operating tables are often unable to accommodate the size and weight of the obese patient; tables specifically designed for obese patients should be used. Extra padding and skin protection are necessary even for short procedures.
    2. Standard noninvasive monitoring, with a urinary catheter, is acceptable in obese patients without significant comorbidities. An appropriately sized blood pressure cuff is critical; a regular-sized cuff placed on the forearm may be more effective than an oversized cuff on the upper arm. IV access may be challenging.
    3. Regional and neuraxial anesthetic techniques may be challenging due to less defined anatomic landmarks. For neuraxial techniques, the midline of the spine may be more readily apparent in the sitting position than in lateral decubitus, thus facilitating catheter placement. Long epidural needles (5 inches) may be necessary. The volume of local anesthetic volume injected may need to be decreased in obese patients. The volume of the epidural space is thought to be decreased due to adipose infiltration and increased blood volume in the epidural venous system.
    4. The combination of increased metabolic demand and decreased FRC leads to rapid and sometimes refractory desaturation with apnea. Preoxygenation for a minimum of 3 to 5 minutes and targeting an end-tidal concentration of O2 greater than 90% is recommended. Mask ventilation may be challenging and adequate gas exchange is often limited. Use of an oral or nasopharyngeal airway or two-person bag-mask technique is frequently required.
    5. Morbidly obese patients have greater reductions in lung volumes than nonobese patients on induction of GA. Physiologically, this manifests as increasing atelectasis, airway closure, and hypoxemia. Titration of PEEP may be necessary to counteract this.
    6. Drug dosing is a challenge and subject of controversy in the obese patient. Obese patients have increased total body weight (TBW) and lean body weight (LBW). However, the ratio of LBW to TBW decreases with increases in TBW. Physiologically, obese patients have increased cardiac output, total body volume, glomerular filtration rate (GFR), and regional alterations in blood flow that alter pharmacokinetics and pharmacodynamics. Generally, lipid-soluble drugs have an increased volume of distribution, but exceptions exist.
      1. In obese patients, LBW is highly correlated with cardiac output, which determines early distribution kinetics, and drug clearance. Most anesthetic drugs should be dosed by LBW.
      2. LBW is determined by individual’s height and weight and is best determined in obese patients by a modified LBW equation: LBWmen = [9 × 103 × body weight/7 × 103 + (216 × BMI); LBWwomen = [9 × 103 × body weight/9 × 103 + (244 × BMI).
      3. Induction doses of propofol should be based on LBW, and maintenance dosing should be based on TBW.
      4. Doses of opioids, including remifentanil, should be based on LBW.
      5. With increased amount of pseudocholinesterase and extracellular fluid, succinylcholine administration should be based on TBW.
      6. Nondepolarizing muscle relaxants should be dosed on ideal body weight.
    7. The patient should be extubated in the operating room when awake, with adequate cough reflexes, and after confirmation of adequate reversal of muscle relaxation. Because the supine position decreases FRC, obese patients should be placed in a sitting position as soon as possible. Patients requiring continuous positive airway pressure for sleep apnea can resume this treatment as soon as necessary; gastric distention does not appear to be a problem.
    8. Postoperative intensive care or step-down unit should be considered for patients with severe coronary artery disease, poorly controlled diabetes, and severe sleep apnea. Studies have shown that patients who are male, older (>50 years), heavier (BMI > 60 kg/m2), and who have complications requiring reoperation are more likely to need intensive care.

Recovery of organs for transplantation after brain death

Recovery of organs for transplantation after brain death

  1. A significant gap exists between the supply of suitable donated organs and the demand for these organs to treat end-stage disease. To increase the donor pool, strict exclusion criteria (age and coexisting illnesses) are no longer used. In addition, some centers use aggressive care regimens for potential donors to prevent common perturbations in homeostasis that accompany brain death. An alternative is the non–heart-beating donor, who does not meet brain death criteria but has such a poor prognosis that the family might consider withdrawing life support. A transplant coordinator from an organ procurement organization must screen all potential donors.
  2. Organs may be deemed unsuitable based on donor age, organ injury, disease, or gross abnormalities.
  3. Hormonal therapy using methylprednisolone, arginine vasopressin, and triiodothyronine can increase the number of successfully implanted organs and reduce graft dysfunction when administered to brain-dead donors who demonstrate resistance to conventional resuscitation as manifested by low cardiac output, inadequate organ perfusion, or worsening lactic acidosis.
  4. Anesthetic management for harvesting organs should focus on optimizing organ perfusion and oxygenation. Volatile anesthetics may help to blunt spinal reflex, reduce the adrenergic storm, and provide some ischemic preconditioning to the vital organs, although studies have not been done to confirm clinical significance. Opioids will also help with reduction in response to stimulation.
    1. Dissection of organs usually occurs in the following order: heart (30 minutes), lungs (1-1.5 hours), liver (1-1.5 hours), pancreas (1-1.5 hours), and kidneys (30 minutes-1 hour).
    2. Once all organs are mobilized, heparin (20,000-30,000 units IV in adult donors) is administered and the aorta is cross-clamped. The distal aorta and IVC are cannulated, and the harvested organs are perfused in situ, topically cooled, and exsanguinated via the IVC.
    3. Ventilatory support is discontinued after the aorta is cross-clamped, and the anesthesiologist’s role is completed with the discontinuation of all monitoring and supportive care, except during heart and lung procurement.
    4. Non–heart-beating organ donation, also referred to as donation after cardiac death (DCD), is reserved for patients who are not declared brain dead but whose family has chosen to remove them from life support because their condition is considered “hopeless.” Life-sustaining treatment (mechanical ventilation and vasopressors) is discontinued after the patient is prepared for surgery to remove the organs. Five minutes after asystole occurs, a physician who is not part of the transplant team declares death. The body is rapidly cooled with preservative solution via an aortic cannula, and the abdomen entered and organs removed expeditiously. This technique has the disadvantage of significant warm ischemia time before organ procurement begins. In addition, there are ethical debates about the appropriateness of interventions (heparin treatment) aimed at improving grafts before the donor’s death. Usually, anesthesiologists are not involved in DCD. However, if the lungs are donated, an anesthesiologist may be asked to intubate the deceased and briefly ventilate.
  5. Specific management problems
    1. Hypoxemia may be caused by atelectasis, pulmonary edema, aspiration, or pneumonia. The FiO2 and minute ventilation should be adjusted to maintain a Pao2 ≤ 100 mm Hg and Paco2 = 35 to 45 mm Hg with pH 7.35 to 7.45. Arterial blood gases should be determined every 30 to 60 minutes. High levels of PEEP should be avoided to preserve cardiac output and avoid barotrauma. High FiO2 should be avoided in potential lung donors to minimize possible oxygen toxicity.
    2. Poikilothermia is common, and early aggressive measures should be taken to minimize heat loss.
    3. Hypertension often transiently accompanies brain death and can be dramatic. Reflex hypertensive responses to surgical stimulation may occur. Short-acting agents such as nitroprusside or esmolol should be used anticipating hypertension that is often more challenging to control during organ procurement.
    4. Hypotension is common and is due to a combination of hypovolemia and neurogenic derangement of vasomotor control. Central venous or pulmonary artery catheterization may be necessary to optimize filling pressures. Hypovolemia can be treated with crystalloid, colloid solutions, and blood products as necessary. Hematocrit should be maintained greater than 30%. After restoration of intravascular volume, a vasopressor such as dopamine, epinephrine, or norepinephrine may be necessary.
    5. Dysrhythmias occur frequently, especially in the setting of electrolyte imbalance, hypothermia, increased intracranial pressure, hypoxemia and acidosis, and derangement of brainstem cardiovascular control centers. Standard therapy is indicated. Bradycardia is often resistant to atropine and may require pacing therapy.
    6. Polyuria may be secondary to volume overload, osmotic diuresis, or the diabetes insipidus resulting from derangement of the hypothalamic-pituitary axis. An IV infusion of vasopressin or desmopressin may be titrated to treat severe diabetes insipidus (see Chapter 6) and should be done in consultation with the surgical team. If used, it is prudent to discontinue these infusions 1 hour before aortic cross-clamping to minimize the risk of uneven distribution or ischemic injury with the infusion of preservative solution.
    7. Oliguria should be treated by ensuring adequate intravascular volume. Dopamine is preferred for the initial treatment of hypotension. A brisk diuresis is preferred when the kidneys are to be harvested. If volume repletion and vasopressors are not effective in restoring adequate urine output, mannitol and/or furosemide may be administered.

Outline