What the Anesthesiologist Should Know before the Operative Procedure

Abdominal surgery following traumatic injury is performed primarily for two reasons: (1) bleeding, in which there is injury to one or more blood vessels or a solid organ (i.e. spleen, liver, kidney), or (2) contamination, in which there is a hollow viscus injury with intra-abdominal spillage of luminal contents (i.e. stomach, small bowel, colon, gallbladder).

In the United States, the majority of abdominal trauma is due to blunt mechanisms of injury, primarily motor vehicle crashes, although abdominal trauma is also seen in falls, pedestrians struck by automobiles, bicycle crashes, and assaults. Penetrating injury is usually violence related, occurring due to a stab wound or a gunshot wound and, in conflict zones, through blast effect (a combination of blunt and penetrating trauma associated with explosions).

Regardless of whether the mechanism of injury is blunt or penetrating, the most important factor in determining the urgency of taking the patient to the operating room (OR) is hemodynamic stability. Patients who are hemodynamically STABLE will often undergo further diagnostic workup, such as an abdominal computed tomography (CT) scan, to identify injured organs and other possible bleeding sources including bony injuries of the spine or pelvis. Occasionally, these patients are treated in the interventional radiology suite with diagnostic angiography followed by therapeutic embolization when the possibility of arterial extravasation is seen on CT.

Patients who are hemodynamically UNSTABLE usually go to the OR immediately; hemodynamic instability suggests a hemorrhage volume that is considered to be life-threatening (>40% estimated blood volume), and nothing should delay operative intervention, which may ultimately result in a damage control operative procedure to control hemorrhage and contamination until physiologic restoration can be achieved in a surgical intensive care unit (ICU) setting.

Need to know

Trauma patients often have multiple injuries, so it is imperative to communicate with the trauma surgeon to determine what other injuries may impact your anesthetic management (i.e. traumatic brain injury, spinal cord injury, pulmonary insufficiency due to aspiration or lung injury, blunt myocardial injury).

In addition to other multitrauma injuries, intra-abdominal traumatic injury can be associated specifically with spinal cord injury or thoracolumbar fractures and with pelvic fractures. Lumbar fractures have been associated with spleen, renal, hepatic, and small bowel injuries; in general, the higher the Injury Severity Score (ISS), and the greater the number of intra-abdominal organs injured, the greater is the likelihood that spinal fractures will also be found. In patients with pelvic fractures, the organs most commonly injured are the liver, bladder, and urethra.

Patients with traumatic injury should have two large-bore peripheral IV lines placed in the field or in the trauma bay. Depending on the urgency of operative intervention, the patient may also come to the OR with central IV access, generally a large-bore Cordis sheath-introducer placed in a common femoral vein, a subclavian vein, or an internal jugular vein. Often, the groin is the access site of choice because of crowding at the head of the bed during airway placement and, often, the presence of a cervical collar in blunt trauma patients. It is, however, very important to remember that fluids infused into a femoral catheter in a patient with intra-abdominal venous vascular disruption may end up in the abdomen, or on the floor, and not in the patient’s central circulation.

The surgical prep for hemodynamically unstable patients is traditionally from the chin to the knees down to the OR table top bilaterally, in the event that major vascular structures (i.e., aorta, vena cava, femoral or iliac vessels) or the left or right chest needs to be accessed. In an emergency, the anesthetist may be placing monitors and performing induction/intubation at the same time as the surgical prep is occurring. ECG leads should be placed as posterior and/or lateral as possible.

The workup and coexisting diseases reviewed here will primarily focus on concomitant traumatic injuries of organ systems, as opposed to chronic medical diseases. The concept of “damage control” surgery was initially developed for unstable patients with intra-abdominal injuries and is intended to rapidly stop bleeding, control contamination without definitive repair, provide temporary abdominal cavity closure and admit the patient to the ICU for ongoing fluid resuscitation, temperature and acid-base homeostasis, and control of coagulopathy (aka “physiological capture”). This chapter focuses on ACUTE abdominal trauma rather than chronic conditions.

Key points

Whether the patient is stable versus unstable determines the time to take the patient to the OR. For unstable patients with hemorrhage, nothing should delay surgery. It is often necessary to obtain IV access, labs, and occasionally even the type and crossmatch after the surgery has begun. For acute transfusion needs, uncrossmatched blood is appropriate.

Peripheral IV access of 18 gauge or larger is appropriate for resuscitation of hemorrhage due to intra-abdominal trauma. A multilumen central access catheter is NOT adequate as large volumes of blood or fluid cannot be administered. If central access is needed, the introducer for OR resuscitation should be placed ABOVE the diaphragm, in the subclavian or jugular veins.

If SCI (spinal cord injury) is suspected, precautions should include in-line spinal stabilization during all manipulations such as intubation and moving the patient from bed to bed (“log roll”).

1. What is the urgency of the surgery?

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

Trauma deaths occur in a trimodal distribution: (1) at the scene, (2) hours after injury, and (3) days to months after injury. The deaths that occur at the scene are due to severe central nervous system (CNS) or major vascular (aorta, great vessels) disruption. The second peak of injury deaths is impacted by efficient prehospital trauma systems and emergent, coordinated care on arrival at the trauma center. Those in the third “wave” occur later than 24 hours after injury and are due to sepsis and/or multiorgan failure. As the OR coordinator, the anesthesiologist is required to determine how trauma cases will be accommodated in a busy elective schedule; an understanding of surgical priorities based on these patterns of death is essential to this process.

Although the overwhelming majority of trauma patients do not require laparotomy, hemodynamically unstable patients with known or suspected intra-abdominal injury need to be taken to the OR immediately.

Emergent: These patients must reach the OR within minutes of notification. Emergent cases often include exploratory surgery (laparotomy with or without thoracotomy) in a hemodynamically unstable patient and craniotomy in a patient with a depressed or deteriorating mental status, when evacuation of blood or decompression of severe cerebral edema will result in a survival benefit; rarely, the operative team will need to accommodate concurrent intracranial and intra-abdominal operations.

Urgent: These patients are not in the immediately life-threatening category but require surgery usually within 1 hour of notification to reduce the incidence of subsequent complications. Examples include exploratory laparotomy in stable patients with free abdominal fluid, as determined by FAST (focused abdominal surgery for trauma) or CT scan. Angiographic procedures have increasingly replaced open surgeries for splenic, hepatic, pelvic and aortic injuries in patients who are hemodynamically stable. Limb-threatening orthopedic and vascular injuries often fall into this category and often are associated with intra-abdominal injuries that require exploration either before or after the limb is addressed

Nonurgent (semi-elective) but necessary: For these patients, surgery can safely be delayed until a scheduled OR time is available. With acute traumatic injury, there are no “elective” abdominal cases.

2. Preoperative evaluation

For emergent or urgent cases, there will not be time to work-up patients with known or suspected preexisting medical conditions. Often, the goals of managing patients with known coronary artery disease (maintaining coronary perfusion pressure and a slow heart rate) conflict with those of damage control surgery and “permissive hypotensive” resuscitation (maintaining systolic blood pressure less than 90 mm Hg until hemorrhage control).

In addition to facilitating timely surgery in patients who require it, the anesthesiologist, surgeon and other involved specialists work together to determine the extent of surgery allowed by the patient’s physiology. The concept of “damage control” has revolutionized surgical thinking in the past decade, limiting initial therapeutic procedures to only those that are required for the achievement of hemostasis and homeostasis, while delaying reconstructive procedures such as bowel re-anastomoses, until adequate resuscitation has been achieved and, in appropriate cases, edema is subsided.

Medically unstable conditions warranting further evaluation are not considered in the bleeding trauma patient with hypotension, as this is life-threatening injury.

Delay of surgery may be indicated if the patient is hemodynamically stable, has no signs of intra-abdominal contamination with gastrointestinal contents, and requires a workup for identification of other traumatic injuries such as brain or spinal cord injury, myocardial contusion, or aortic or vascular extremity injury.

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

Higher mortality following trauma has been associated with increasing age and with preexisting conditions of heart disease, hepatitis/liver cirrhosis, carcinoma, obesity, and peripheral arterial occlusive disease. These associations have been determined in large retrospective database reviews, so an individual’s risk is difficult to estimate.

Perioperative evaluation

Preoperative evaluation in patients with exsanguinating hemorrhage is not possible. Patients with intra-abdominal contamination also require urgent exploration and usually there is no time for a preoperative assessment. If the patient has known coronary artery disease, every attempt should be made to maintain coronary perfusion pressure and heart rate control.

Perioperative risk reduction strategies

Maintenance of perfusion pressure to vital organs prior to hemorrhage control is desirable. Following hemorrhage control, management should be geared toward restoration of physiological homeostasis (decreasing base deficit, return to normal of vital signs). Perioperative control of hyperglycemia may improve outcome.

b. Cardiovascular system

Acute/unstable conditions

Traditional markers for myocardial ischemia such as ECG changes and increased enzyme levels may be misleading in the patient who has sustained a massive energy transfer to the thorax due to trauma. Timely diagnosis of aortic injury requires a high degree of suspicion in any patient who has suffered a high-speed motor vehicle collision, any pedestrian struck by a motor vehicle, any motorcyclist, and any patient who has fallen more than 10 feet. Symptoms of aortic injury are nonspecific. The blood pressure is commonly labile, with exaggerated peaks and troughs in response to painful stimulation, hemorrhage from other injuries and sedating medications. Common coexisting injuries include fractured ribs or sternum, left hemothorax, humeral fracture, splenic rupture, and left-sided femur or acetabular fracture, although none of these is a highly sensitive marker for aortic trauma.

Baseline coronary artery disease or cardiac dysfunction management

Cardiac dysfunction due to blunt myocardial injury is difficult to determine: chest radiography is warranted and sensitive but not often specific; advanced chest CT is the new standard in large centers with experienced radiographers. Transesophageal echocardiography is highly sensitive and specific and is the appropriate diagnostic approach when an experienced operator is available. Preoperative beta-blocker therapy is indicated to reduce sheer-force stresses on the proximal aorta.

c. Pulmonary

COPD

The trauma patient with underlying lung disease presents with one of two classes of pulmonary complications: those attributable to the traumatic injury per se and those caused by underlying medical comorbidities that are exacerbated by the traumatic insult. Older patients with preexisting pulmonary disease are at greater risk of perioperative and postoperative pulmonary complications than are young patients with healthy lungs. Moreover, perioperative lung complications may be as prevalent and as predictive of mortality as perioperative cardiac complications. There is little evidence to suggest that interventions taken by an anesthesiologist during the perioperative period might reduce postoperative pulmonary complications in patients with traumatic injury.

Some lung dysfunction occurs in almost all patients with long-bone fractures, ranging from minor laboratory abnormalities to life-threatening fat embolism syndrome. Most studies suggest clinically significant fat embolism syndrome occurs in 3%-10% of patients, although the presence of multiple long-bone fractures is associated with the higher incidence. Patients with coexisting lung injury are at additional risk of fat embolism. Fat embolism syndrome should be suspected whenever the alveolar–arterial oxygen gradient deteriorates, especially if in conjunction with decrements of pulmonary compliance and CNS function. Diagnosis in the operating room is largely based on clinical presentation and ruling out other treatable causes of hypoxemia.

Reactive airway disease (asthma)

Additional causes of hypoxemia or worsening pulmonary compliance in the operating room include aspiration, pulmonary contusion, hemo/pneumothorax and transfusion-related acute lung injury (TRALI).

d. Renal-GI:

The spleen is the most common abdominal organ injured in blunt trauma and can account for significant hemorrhage; once the splenic artery is clamped by the surgeon, blood pressure usually stabilizes (if there are no other bleeding injuries) and the anesthesiologist can “catch up” with resuscitation. Pancreatic injuries are rare and usually do not lead to massive hemorrhage. Gastric injuries are usually due to penetrating trauma. Placement of oral or nasal gastric tubes may be done with intraoperative confirmation of placement by the surgical team. The kidney is the most commonly injured part of the urinary tract. Renal hemorrhage itself is rarely the cause of hemodynamic instability.

Abdominal compartment syndrome can occur acutely with massive intra-abdominal hemorrhage, leading to vena cava compression, exacerbating hypotension. Increased intrathoracic pressures can also be seen, and release of intra-abdominal pressure by surgical incision is curative. However, this can also lead to uncontrolled hemorrhage as the “tamponade effect” is lost. Surgical packing of all four abdominal compartments may temporize further bleeding.

e. Neurologic:

Traumatic brain injury (TBI) causes at least half of all deaths in trauma. A systolic blood pressure of 90 mm Hg should be maintained in patients with severe TBI with a mean arterial pressure (MAP) of 50 to 70 mm Hg until invasive intracranial pressure (ICP) monitoring can be placed. This contrasts with guidelines for “permissive hypotension” and “damage control” resuscitation for patients with active hemorrhage; these can be the most challenging cases to manage. Increasing MAP to greater than 70 mm Hg may not improve outcome from TBI, particularly in patients in whom autoregulation is lost. There is controversy as to the appropriate “transfusion trigger” in patients with severe TBI and whether these patients should be treated as other critically ill patients in whom a hemoglobin of 7 g/dL is a proven trigger.

Hemodynamic instability from associated SCI may complicate resuscitation following intra-abdominal trauma. Hypotension from neurogenic shock is characterized by an inappropriate bradycardia due to loss of cardiac accelerator function and unopposed parasympathetic tone. However, the situation can still be difficult to distinguish from hypotension due to acute hemorrhage, and a trial of fluid administration is indicated. Once hemorrhage has been controlled or ruled out, some data exist that support maintenance of an elevated MAP greater than 85 mm Hg for 7 days after SCI, although this approach is highly controversial. Fluid administration will expand the vascular volume and counter the effects of inappropriate vasodilatation, but volume loading may exacerbate myocardial dysfunction (due to SCI blunt trauma or to preexisting cardiac disease).

Acute issues

The management of acute TBI and SCI is highlighted above. Chronic SCI patients may present with acute abdominal trauma and present two challenges: management of autonomic hyper-reflexia and the need to avoid succinylcholine for rapid sequence intubation. A catheter should be placed for bladder decompression, and opioids are administered to treat pain adequately. Hypotension should be considered to be due to acute hemorrhage rather than chronic SCI until definitively ruled out.

f. Endocrine

Hyperglycemia following trauma is common due to the systemic “stress” response and to inflammation. The severity of hyperglycemia is related to the degree of injury, and control of blood glucose preoperatively and intraoperatively is associated with a decrease in both postoperative infection and mortality following trauma.

Hypothermia contributes to CNS depression, cardiac irritability, coagulopathy, shivering, increased oxygen consumption, suboptimal wound healing, and altered liver and kidney function. Thus, hypothermia can severely affect outcomes in trauma patients, particularly those with multiple extremity injuries. Many patients entering a trauma center already have a low body temperature from environmental exposure. Additional exposure to cold during EMS transport and hospital environments, evaporative heat loss from the respiratory tract, infusion of cold fluids intravenously and loss of heat production secondary to shock or anesthetic-mediated sympathectomy can produce further significant drops in core temperature and even reduce the effectiveness of warming efforts.

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)

Orthopedic trauma produces limb- and often life-threatening musculoskeletal injuries, including hemorrhage from open wounds and open or closed fractures, infection from open fractures, limb loss from vascular damage and compartment syndrome and loss of function from spinal or peripheral nerve injuries. Associated orthopedic injuries are more common with blunt rather than penetrating trauma in civilian trauma centers, but conflict-related injuries from blasts commonly produce concomitant intra-abdominal and extremity trauma.

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

Emergency surgery for intra-abdominal hemorrhage often prevents any preanesthetic evaluation and therefore medications (and medical history) may be unknown; it is not uncommon for the patient’s name to also be unknown for these cases. There are no chronic medications that are absolutely necessary to continue for intra-abdominal procedures, particularly in an emergency setting.

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

Patients on beta-blockade or calcium channel blockers may not be able to mount a compensatory tachycardia with hypovolemia due to hemorrhage, and therefore hypotension may be more severe.

Patients on anticoagulants (warfarin, antiplatelet therapy, direct thrombin inhibitors) for treatment of atrial fibrillation, coronary artery disease, stroke, deep venous thrombosis or pulmonary embolus may have worse hemorrhage or clinically diffuse bleeding; coagulation studies should NOT delay surgery for emergency procedures, and factor replacement (plasma, factor concentrates) or agents to antagonize bleeding (tranexamic acid, aminocaproic acid) should be available if coagulopathy is suspected and/or documented [see below].

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

There are no medications that are absolutely necessary to continue for intra-abdominal procedures, particularly in an emergency setting.

j. How to modify care for patients with known allergies –

Avoid medications from classes of drugs for which the patient has any known allergies.

k. Latex allergy-

If the patient has a sensitivity to latex (e.g. rash from gloves, underwear, etc.), prepare the operating room with latex-free products.

l. Does the patient have any antibiotic allergies? (common antibiotic allergies and alternative antibiotics)

Often, it is difficult to obtain a history in patients taken emergently to the OR. If the patient develops signs of allergy, avoid the most common antibiotics associated with allergy, the penicillins and cephalosporins.

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

Malignant hyperthermia (MH)

For patients with documented MH, avoid all trigger agents such as succinylcholine and inhalational agents. The proposed general anesthetic plan is as follows: (1) total intravenous anesthesia with nondepolarizing neuromuscular blockade can be used and (2) ensure an MH cart is available (MH protocol).

For patients with a family history or risk factors for MH, when using local anesthetics and muscle relaxants avoid known allergens.

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

A hematocrit measured soon after hemorrhagic trauma may show little change, as whole blood is being lost and the percentage of red blood cells in the remaining volume does not change. Thus, a stable hematocrit in the face of ongoing loss is meaningless information. Fluid resuscitation after massive hemorrhage will result in in extensive hemodilution and coagulopathy; this hemodilution affects procoagulants as well as anticoagulants and profibrinolytic components of the coagulation cascade. Factor replacement early in resuscitation, with plasma, platelets, and occasionally cryoprecipitate may mitigate a severe coagulopathy.

Coagulopathy due to acute consumption of coagulation factors is likely in any patient losing more than a single blood volume (approximately 5 L in the typical 70-kg adult) or receiving more than 10 units of red blood cells. Because coagulopathy is more easily prevented than treated, early administration of plasma to any patient who has lost or will lose this amount of blood is highly recommended. Timely initiation of a massive transfusion protocol is associated with improved survival and reduced transfusions.

Electrolyte abnormalities are common during resuscitation from hemorrhage. Hyperosmolarity results from alcohol ingestion, dehydration, hypovolemia or administration of normal saline. Hyperchloremic metabolic acidosis is a significant risk of overresuscitation, especially with mildly hypertonic solutions such as normal saline, and can be managed with the titrated addition hypotonic fluids.

Hypocalemia arises from chelation of circulating calcium by the citrate or adenosine additives found in banked blood products. Intravenous administration of calcium should be considered for empiric administration in the case of massive transfusion, particularly in the presence of hemodynamic instability. Serum bicarbonate levels will be lower than normal in the hemorrhaging patient, owing to increased lactic acidosis and impaired renal blood flow.

The use of fluid replacement in severe injuries that is as near to whole blood as possible (i.e., blood/plasma/platelets in a 1:1:1 ratio) has resulted in increased survival and decreased postoperative complications. This concept of “damage control resuscitation” has become a standard of care.

Early resuscitation has evolved toward less aggressive fluid administration. Late resuscitation is characterized by the need to completely restore and support perfusion, usually in the ICU. To do so requires the practitioner to look beyond the vital signs for a more direct measure of tissue perfusion. The speed with which the serum lactate level normalizes after shock is strongly associated with the risk of death from organ system failure; base deficit and pH are surrogates for adequacy of resuscitation in the OR and can be obtained readily. “Endpoints” of resuscitation should focus on organ-specific signs of recovery of function: improving lung function, cardiac contractility, and vasomotor tone; clearance of toxins by the liver and kidney; and the absence of infectious complications, which are unfortunately common after severe traumatic injury.

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

a. Regional anesthesia

Regional anesthesia is not practical in the acute management of intra-abdominal trauma.

b. General anesthesia

General anesthesia is the indicated technique for acute abdominal trauma. Large-bore IV access with two peripheral catheters or a large-bore central access catheter and arterial pressure monitoring should be obtained as soon as possible in patients who are hemodynamically unstable.

Benefits

Patients will require general anesthesia to control the airway if the patient is hemodynamically unstable, if the patient requires massive transfusions, and to facilitate mechanical ventilation if the abdomen is packed or left open to prevent intra-abdominal pressure increases.

Drawbacks

There is no real alternative in these patients.

Monitored anesthesia care is not practical in the management of acute intra-abdominal trauma.

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

N/A

a. Neurologic:

N/A

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

Patients who have undergone “damage control” surgery are not candidates for extubation as they will be admitted to the ICU for ongoing resuscitation. Patients with intra-abdominal injuries that are readily repaired and have restoration of hemodynamic stability (e.g., spleen or gastric injuries) may be considered for extubation. Criteria do not differ from standard anesthetics, with the possible exception of confirming any lack of elevated intra-abdominal pressure.

c. Postoperative management

What analgesic modalities can I implement?

The goal with “damage control” surgery is to avoid the “lethal triad” of hypothermia, acidosis, and coagulopathy that can rapidly develop in a patient with massive bleeding. Patients are admitted to the ICU for ongoing resuscitation. After resolution of shock, warming, and normalization of laboratory values, the patient would return to the OR in 24 to 36 hours for further exploration, debridement of nonviable tissue, definitive repair and reconstruction of vascular and/or gastrointestinal tract, placement of internal feeding access if indicated, and abdominal closure if feasible.

What level bed acuity is appropriate?

A patient in whom restoration to normalization of laboratory values, blood pressure, or heart rate is unsuccessful should be ruled out for ongoing intra-abdominal hemorrhage and returned to the OR or CT scan or angiography suite for further evaluation.

What are common postoperative complications and the ways to prevent and treat them?

Coagulopathy may develop or return postoperatively; the trauma patient with recent hemorrhage control is always at risk for recurrent hemorrhage. Significant fecal contamination WITH shock, and a greater number of organs injured, increases the risks of sepsis, multiorgan failure, and mortality.

What's the Evidence?

Seamon, MJ, Feather, C, Smith, BP. “Just one drop: the significance of a single hypotensive blood pressure reading during trauma resuscitations”. J Trauma . vol. 68. 2010. pp. 1289-94. (This reference speaks to the importance for considering bleeding in trauma patients when hypotension occurs.)

Sanddal, TL, Esposito, TJ, Whitney, JR. “Analysis of preventable trauma deaths and opportunities for trauma care improvement in Utah”. J Trauma . vol. 70. 2011. pp. 970-7. (Multidisciplinary retrospective review of trauma deaths in Utah. Preventable deaths in hospital appeared to be due to problems in airway management, fluid resuscitation and chest injury management.)

Patel, NY, Riherd, JM. “Focused assessment with sonography for trauma: methods, accuracy and indications”. Surg Clin North Am . vol. 91. 2011. pp. 195-207. (Describes FAST Exam that is quick and accurately can document need for surgery.)

Langeron, O, Birenbaum, A, Amour, J. “Airway management in trauma”. Minerva Anesthesiol . vol. 75. 2009. pp. 307-11. (Discusses the issues regarding intubation of trauma patients and the various techniques.)

Kautza, BC, Cohen, MJ, Minel, JP, Brackenridge, SC, Maier, RV, Harbrecht, BG. “Changes in massive transfusion over time: An early shift in the right direction?”. J Trauma . vol. 72. 2012. pp. 106-111. (Data from a multicenter prospective trial of adults who had blunt trauma and hemorrhagic shock. Found that patients who received higher quantities of platelets [PLT] and fresh-frozen plasma [FFP] required less packed red blood cells [PRBCs]. This is offered as level II evidence for using higher transfusion ratios of FFP:PRBC and PLT:PRBCs.)

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