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CHAPTER 112: Principles of Postoperative Critical Care 1067

wound contraction over abdominal wounds. The use of these devices that low-dose unfractionated heparin offers no benefit at all in trauma
in complicated abdominal injuries, evisceration, and abdominal com- patients. Alternatively, twice daily low-molecular-weight heparin has
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partment syndrome has increased and studies generally show benefit; been shown to reduce the incidence of DVT in trauma patients, but
however, there is also evidence that the devices may increase rates of new patients should be monitored closely for bleeding complications during
enterocutaneous fistula formation. 38 its use. Patients with active bleeding or at high risk for bleeding com-
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The overall supportive care of the patient is also important when plications should receive mechanical prophylaxis; however, there are
attempting to enhance wound care. Both hyperglycemia and hypoglyce- no data that prove efficacy in this population. Sequential compression
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mia should be avoided. Routine perioperative antibiotic usage should be devices are often contraindicated or difficult to place with extremity
limited to 24 hours and optimization of nutrition should be employed fractures, fasciotomies, and external fixators. Trauma patients who are
to further enhance wound healing. Wounds should be evaluated at least at high risk for venous thromboembolism who cannot receive antico-
daily to monitor for progression of healing and for signs of infection. agulation should be considered for temporary inferior vena cava filter
Most normal surgical wounds will have a small, dry scab and a small placement. 47
border of reactive erythema that will resolve over about a week. Wounds
that develop progressive erythema and induration may indicate the ■ POSTOPERATIVE HEMORRHAGE AND THE SENTINEL BLEED
presence of underlying cellulitis/wound infection. These should be As any general surgery resident will tell you, postoperative hypotension is
treated with opening of the incision rather than administration of anti- bleeding until proven otherwise. Patients in hemorrhagic shock demon-
biotics. In most instances, systemic antibiotics are not necessary once strate clinical signs of tachycardia, diminished peripheral pulses, coolness
the wound has been open and adequately drained, but it is important of the extremities, anxiety/agitation, and hypotension. Generally, 25%
to ensure that the infection has not spread to the fascia and soft tissues, to 30% of blood volume loss occurs before signs of shock are evident,
indicating necrotizing fasciitis. 39 but younger patients or elderly patients receiving certain cardiovascular
■ DEEP VEIN THROMBOSIS PROPHYLAXIS IN THE SURGICAL medications may lose a greater percentage of blood volume prior to

AND TRAUMA PATIENT demonstrating signs. Most adult patients can lose up to 15% of their
blood volume without showing any overt symptoms. Loss of 40% of cir-
All postsurgical patients requiring the ICU should have consideration culating blood volume is life threatening and generally requires operative
given for chemical anticoagulation in addition to mechanical mecha- (or interventional) control of hemorrhage. The absolute hemoglobin/
nisms for deep vein thrombosis (DVT) because they are inherently at hematocrit values are not a reliable indicator of hemorrhage as they
risk for the development of this complication. Numerous guidelines may be affected by acute whole blood volume loss and/or hemodilution
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exist for assistance in determining which anticoagulation is best for cer- from fluid resuscitation. Trending values are often more helpful in this
tain patient populations; however, in general, prevention should include situation. Hypothermia, acidosis, and coagulopathy, the so-called triad
anticoagulation in any general surgery patient who is considered to be of death, should be corrected unless there is an obvious source of bleed-
at moderate-to-high risk for DVT. Major risk factors include presence ing prior to returning to the operating room as venous hemostasis can
of an operation, physical immobility, age, malignancy, obesity, and often be achieved by simply controlling these factors. Patients should
smoking history. 41 be actively warmed with an external warming device (eg, Bair Hugger)
Low-dose unfractionated heparin or low-molecular-weight heparin and warmed fresh-frozen plasma, platelets, and cryoglobulin should be
should be used. Low-molecular-weight heparin can be administered administered as appropriate to correct the coagulopathy.
in most cases, unless obesity is a factor. Low-dose unfractionated hepa- Critical care providers should be aware of potential “sentinel bleeds,”
rin should be administered three times daily rather than twice daily as small volume bleeds classically from a sternal wound or peritoneal
previously recommended. In high-risk patients, mechanical devices drains that may represent an ensuing large volume blood loss. Such
should be used in addition to anticoagulation. If the risk for postopera- sentinel bleeds can represent vasospasm of a surgical bed artery, duode-
tive bleeding is considered too high to administer chemical prophylaxis, nal ulceration into the gastroduodenal artery, or small right ventricular
mechanical prophylaxis should be used until chemical agents can be runt that is a risk for rapidly tearing with coughing episode. Responding
started. In addition chemical prophylaxis should not be given in the to these small bleeding episodes can be lifesaving. Again it is imperative
12 hours proceeding placement or removal of an epidural catheter. that critical care practitioners recognize hypotension in postoperative
Unfractionated heparin administered subcutaneously can be admin- and trauma patients likely represents hemorrhagic shock. Assessment
istered while an epidural catheter is in place, but close monitoring for of the surgical wound or any drains for signs of bleeding should be
signs of complications should be performed. 42 performed. In the trauma patient, a FAST (focused assessment of
DVT prophylaxis in the neurosurgical patient is imperative but sonography for trauma) examination can be performed at the bedside
routinely is not started within an appropriate time frame. This is gen- to look for intra-abdominal fluid. A CT scan can be considered, but this
erally because of the hesitation of the neurosurgeons, rather than the takes time and use of contrast dye to assess for extravasation in a patient
intensivists. Because of the increased risk in this patient population, already at high risk for acute kidney injury. Immediate involvement with
mechanical prophylaxis should be used routinely and initiated imme- the surgical or trauma team is mandatory for operative or interventional
diately. Heparin administered at just 5000 units subcutaneously every decision making.
12 hours has been shown to significantly reduce the risk of DVT in
neurosurgical patients without increasing the risk of bleeding, as long
as there is no active hemorrhage at the time it is initiated. In general, PRINCIPLES OF OPEN HEART SURGERY AND CARDIAC
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chemical prophylaxis should be added within 24 hours of surgery. In SURGERY EMERGENCIES
many cases, this will have to be worked out on a case-by-case basis with ■
the neurosurgeons. BASIC CARDIAC ANATOMY
Trauma patients carry a significant risk for the development of DVT There are entire textbooks dedicated to postoperative management of
and its complications. It is also one of the most difficult groups for open-heart surgery. This section will only deal with the most superfi-
which to provide adequate prophylaxis to prevent DVT from occurring. cial of these and subsequent sections will address specific emergencies
Risk factors for DVT are numerous and controversial; they include that must be recognized by the critical care team managing. A general
spinal fractures, traumatic brain injury, spinal cord injuries, prolonged understanding of cardiac anatomy, cardiopulmonary physiology, and
mechanical ventilation, multiple operative procedures, and pelvic basic operative techniques is a must in order to be able to communicate
fractures. Although there are few studies validating specific anticoagu- with the surgical and anesthetic teams that bring the patient to the ICU.
lation practices in patients with these factors, there is ample evidence Understanding coronary anatomy, divisions of the mediastinal and

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