Page 1553 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

1072 PART 10: The Surgical Patient

or IV congestive heart failure, age >75 years, immunosuppressed state, Strategies to reduce paralysis must be employed before, during, and
perioperative renal failure, chronic lung disease, myocardial infarc- after thoracic aortic surgery through four separate strategies: minimi-
tion within the last 6 months, need for assist device, reexploration for zation of ischemia, tolerance to ischemia, increased cord perfusion,
bleeding, use of bilateral mammary grafts, prolonged cardiopulmonary and early recognition of neurologic deficits. Operative strategies that
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bypass, prolonged clamp time, blood loss in the intensive care unit, reduce ischemic time include segmental reconstruction, distal shunting,
transfusions, transverse fractures of the sternum, sternal osteoporosis, and partial left heart bypass. Tolerance to ischemia is provided through
history of chest radiation, postoperative CPR, prolonged ventilatory systemic hypothermia, cardiopulmonary bypass with deep hypothermic
support, and possibly emergent operations. 90,91 Common pathogens circulatory arrest (DHCA), pharmacologic protection, and epidural
historically include Staphylococcal aureus and S epidermidis, but cooling procedures. Cord perfusion is increased by assurance of patent
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recent studies have found other organisms to be more prevalent. collaterals, deliberate hypertension, lumbar drainage, and reimplantation
Pseudomonas aeruginosa, Klebsiella, Serratia marcescens, Enterobacter, of segmental spinal arteries including the artery of Adamkiewicz, a large
and α-hemolytic Streptococcus were found in one recent study perhaps segmental artery located in the lower thoracic spine. Finally, recognition
related to the routine prophylaxis against Staphylococcus. 89,90 These of neurologic deficits can be performed with intraoperative monitoring
wounds require treatment with systemic antibiotics, wound and ster- of evoked somatosensory evoked potentials (SSEPs) or motor evoked
nal debridement, and tissue coverage of the wound, for example, with potentials (MEPs). Postoperatively frequent neurological examinations
muscle flaps. should be performed. 95
The primary strategy against development of sternal wound com- It is mandatory that a critical care physician understands that part
plications is stable sternal fixation. No clear wiring/fixation strategy that he or she plays in preventing paralysis in the postoperative setting
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has been found to be superior, although in this case, probably more is including augmenting blood pressure and cardiac output, preventing
better with use of seven or more wires and a caudal sternal wire hav- hypotension, reducing cerebrospinal fluid (CSF) pressure by managing
ing shown to be associated with decreased DSWI. Other mechanical lumbar drainage, reducing central venous pressure, and providing early
strategies frequently utilized by surgeons include implementing “sternal recognition of neurologic changes. In general, vasopressors are given to
precautions” where patients should have no heavy lifting greater than keep a mean arterial pressure (MAP) >80 mm Hg, or a spinal perfusion
5 lb, no asymmetric movements (such as lifting one arm above his/her pressure >70 mm Hg. In the presence of lower extremity weakness, MAP
head or tucking shirt in behind his/her back), or no asymmetric weight goals should be increased by increments of 5 mm Hg. It is particularly
bearing (as with use of a crutch or cane). These strategies are variable important to prevent hypotension. Hypotension is generally associated
between facilities and some physical therapists have questioned their with reported onsets of spinal cord ischemia, although there is some
necessity. 92 controversy that that the cord ischemia may result in a spinal shock. It is
■ POSTPERICARDIOTOMY SYNDROME generally recommended to avoid bolus antihypertensive agents. Lumbar
drains are placed in order to augment spinal cord perfusion pressures
Postpericardiotomy syndrome (PPS) is a syndrome seen after surgical (SCPP) as SCPP = MAP – (the greater of either CSF pressure or CVP).
pericardiotomy, as well as with viral pericarditis, trauma associated with The CSF drains into a reservoir with a goal of keeping the lumbar CSF
hemopericardium, and myocardial infarction (Dressler syndrome). It pressure less than 10 mm Hg. Two separate meta-analyses have shown
is a pleuropericarditis with a variable reported incidence after cardiac efficacy in lumbar CSF drainage with the largest single trial finding
surgery of 10% and 60% of patients. The syndrome is associated reduction in the incidence of postoperative neurological deficits from
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with clinical findings usually 2 to 3 weeks after pericardiotomy. These 13.0% to 2.6% when CSF pressures were maintained <10 mm Hg. In
primarily are fever and chest pain, but can include malaise, dyspnea, general, lumbar drains remain safe, even in the face of full anticoagula-
nonproductive cough, dysphagia, fatigue, hemoptysis, abdominal pain, tion. Complications related to lumbar drainage occur in <5% of patients
myalgias, and arthralgias. The pain is usually retrosternal in location undergoing thoracoabdominal operations and include catheter fracture,
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and described as a knife-like, stabbing sensation. On examination a fric- meningitis, intracranial hypotension, and spinal headache. Other
tion rub may be present and clinical evaluation may reveal cardiomegaly potential complications include intracranial hypotension, temporary
on chest x-ray, mild leukocytosis, elevation in the sedimentation rate, abducens nerve palsy from cerebellar tonsillar herniation, and subdural
effusion on echocardiogram, and ECG findings of pericardial irritation hematoma related to tearing of dural veins. Each of these occurs from
including ST segment elevation in the limb and lateral precordial leads. excessive CSF drainage. Standard ICU protocols should allow for no
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It is a diagnosis of exclusion, and infection and delayed tamponade more than 10 mL per hour of drainage from lumbar drains for pressures
should be ruled out first. Treatment is primarily with anti-inflammatory greater than or equal to 12 mm Hg, or 10 mm Hg if postoperative paraple-
agents, typically indomethacin. Severe cases may require steroid admin- gia is present unless specifically ordered by the managing physician. 95,96
istration and/or pericardial drainage. 93 ■
■ PARALYSIS/PARESIS AFTER THORACIC AORTIC SURGERY An in-depth review of cardiac mechanical devices is beyond the scope
TEMPORARY CARDIAC MECHANICAL DEVICES
Descending thoracic aortic surgery is becoming increasingly more of this chapter, but an understanding of the basics behind temporary
common as awareness of thoracic aortic disease increases and imaging mechanical devices should be had by all critical care physicians in
modalities become more available. Paresis and paralysis remain a dev- order to care for patients who have acute cardiogenic shock. Temporary
astating complication of the procedure. Risk of paralysis was historically devices may be used as a bridge to recovery, surgery, long-term devices,
as high as 40% but is now generally reported to be 8% to 28% for open or urgent transplant. Examples of these situations include viral myocar-
operations and 4% to 7% for thoracic endovascular aortic stentgrafts ditis, postpartum cardiomyopathy, acute pulmonary embolism, acute
(TEVAR). In addition to open repair, paralysis risk is associated with myocardial infarction, or ruptured papillary muscle with “wide-open”
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length of aorta replaced/covered, history of prior distal aortic surgery, mitral regurgitation. Multiple devices exist, each with their own advan-
operative emergency, aortic rupture, aortic dissection, anemia, hypo- tages and disadvantages, which are outlined in Table 112-4.
tension, prolonged aortic clamp time, failure to reimplant segmental A few notable complications that a critical care physician must be
arteries, diabetes, advanced age, and severe atherosclerotic disease. aware of include balloon rupture of an intra-aortic balloon pump, cold
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Atherosclerotic disease is important because of loss of collateral flow limb from either the microaxial VAD or IABP, and IABP-related throm-
to the spinal cord. Collateral flow is provided from the anterior and bocytopenia. Balloon rupture is an emergency and the balloon must be
posterior spinal arteries via the vertebral arteries as well as retrograde removed immediately. Blood in connecting tubing is the hallmark of
collateral flow from the internal iliac, inferior mesenteric, and middle rupture. Counterpulsation should be turned off immediately, the patient
sacral arteries to the paired lumbar and intercostal arteries. placed in head down position, and the IABP removed due to risk of

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