Page 1557 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

1076 PART 10: The Surgical Patient

vascular malformations, and cerebrovascular reactivity. Management
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TABLE 112-6 Early Urgent Liver Transplant Complications
includes control of blood pressure with goal systolic <120 to 140 mm Hg.
Complication Timing Findings Treatment Calcium channel blockers and nitrates should probably be avoided
Abdominal Immediate Hypotension Correction of due to their increase in cerebral blood flow. ß-Blockers and clonidine
bleeding Tachycardia coagulopathy seem to be ideal for treatment of CHS, although no trials exist.
Reduced central venous Reexploration if >4-6 ■
pressure units of NECK SURGERY EMERGENCIES: COMPRESSIVE HEMATOMA
Decreased renal function blood in 24 hours or AND BILATERAL RECURRENT LARYNGEAL NERVE INJURY
Preservation of liver function hemodynamic instability
Operations on the neck are performed for a variety of reasons including
Hepatic artery Early Acute liver failure Urgent thrombectomy/ thyroid and parathyroid disease, carotid endarterectomy, head and neck
thrombosis or Fulminate increase in LFTs graft revision cancer, and tracheal conditions. It is not infrequent that these conditions
kinkage Hemodynamic instability Urgent retransplantation are admitted postoperatively to the intensive care unit for neurologic, free
Portal vein Early Acute liver failure Urgent thrombectomy flap, and airway monitoring. While rare, the complication of compressive
thrombosis Fulminate increase in LFTs Urgent retransplantation hematoma or bilateral recurrent laryngeal nerve injury is life threatening. In
Hemodynamic instability one series, only 15 patients in just over 3000 thyroidectomy cases required
Ascites emergent airway intervention including reoperation, tracheostomy, and
Variceal bleeding reintubation with steroid administration (for laryngeal edema). 109
A clinically significant postoperative hematoma occurs in 0.36% to
Portal vein Immediate Slight increase in LFTs Reconstruction 4.3% of thyroidectomies and 1% to 12% of carotid endarterectomies.
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stenosis Portal hypertension Patients exhibit an enlarged neck diameter and dyspnea. Most hema-
Ascites
tomas occur in the first 4 to 6 hours, but up to 40% will occur after
Hyperacute Early ABO incompatibility Urgent retransplantation 6 hours. The vast majority of clinically significant hematomas require
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rejection Preformed anti-HLA antibodies surgical exploration. Edema of the larynx and pharyngeal wall makes
Acute liver failure these intubations difficult, necessitating a highly experienced individual
Normal hepatic Doppler to perform the preoperative intubation. Hematoma has not been found
HLA, human leukocyte antigen; LFTs, liver function tests. to be related to age, gender, type of thyroid disease, or type of bleeding
after thyroidectomy. Risk factors for hematoma after CEA include
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nonreversal of heparin, intraoperative hypotension, and carotid shunt
and even higher for those with preoperative stroke, with asymptotic placement. Patients with hematoma after CEA spent more time in a
high-grade stenosis being associated with the lowest risk for stroke. critical care setting and had increased perioperative mortality. 111
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Surgical risk factors for perioperative stroke include inability to toler- Only 0.5% of patients with benign goiters and 10.6% of patients with
ate clamping during the procedure, use of an intra-arterial shunt, and thyroid cancer have some form of recurrent laryngeal nerve damage
general anesthesia with only use of a shunt remaining after multivariate after thyroidectomy. These patients have a characteristic hoarse voice.
analysis. This is likely because of diminished native cerebral vessel Fortunately, only about one in a thousand cases results in bilateral recur-
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collaterals see Table 112-5. rent laryngeal nerve damage. Clinically these patients have breathing
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Atherosclerotic emboli are the most common of the four mechanisms, difficulties and aphonia. After securing their airway, these individuals
accounting for over half of the postoperative strokes. These emboli form will need to undergo a tracheostomy.
after atherosclerotic plaques flow distally either spontaneously or due to
mechanical disruption. Carotid artery stenting has a theoretical reduc- ■ ENDOCRINE SURGERY SPECIAL SITUATIONS: RESECTION
tion in these events due to embolic protection devices and trapping
of the atherosclerotic plaques between the stent and the native vessel OF PHEOCHROMOCYTOMA OR PARAGANGLIOMA
wall. Atheroemboli can be identified by Transcranial Doppler (TCD) AND CARCINOID TUMORS
evaluation with an association identified between increased number of Pheochromocytomas and paragangliomas are rare catecholamine
emboli measured and worse neurologic outcomes. Thrombosis is the producing tumors. Pheochromocytoma refers to an intramedullary
second mechanism for perioperative stroke and occurs because intimal tumor of the adrenal glands, whereas paraganglioma refers to a
disruption by either surgical instrumentation or spontaneous routes tumor in the paraganglia. About 90% of tumors are located within the
leads to a state of increased thrombus formation after revascularization. adrenal, whereas 10% of tumors are paragangliomas. Typically these are
Thrombus at the surgical site can limit flow and results in cerebral hypo- intra-abdominal located around the aorta or inferior vena cava, but can
perfusion. Antiplatelet agents likely reduce this risk. TCD may also play be located in a wide range of places in the body including the brain, heart,
a role in identifying people with thrombosis. and bladder. The resection of pheochromocytomas or paragangliomas
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Global hypoperfusion may also lead to perioperative neurological carries considerable risks to the patient in the perioperative period with
events. Diffuse cerebral hypoperfusion likely comes from precipitous mortality risk previously quoted as 2.9% to 3.9%. More recent series
falls in mean arterial pressure, thereby reducing cerebral perfusion report a reduction in mortality to zero, likely due to the understanding
pressure. Intraoperatively this can be followed with cerebral oximetry, of intraoperative management and postoperative monitoring.
TCD, or EEG monitoring. Different surgical strategies are employed to Preoperatively the condition can result in hypertension and hypertro-
prevent this, including shunting and permissive hypertension. Finally, phic cardiomyopathy (or rarely dilated cardiomyopathy). Intraoperatively
cerebral hyperperfusion occurs in 1% to 13% of patients undergoing blood pressures can be variable. Hypotension occurs from inadequate
revascularization. 107,108 It is described in both patients who undergo resuscitation, residual effects of preoperative α-blockade, sudden increased
CEA and CAS, and represents a clinical spectrum of symptoms rang- venous capacitance, and/or hemorrhage, and hypertension occurs from
ing from a severe, unilateral headache to altered mental status to catecholamine secretion from noxious stimuli-like intubation, skin inci-
seizures to focal transient defects to cerebral hemorrhage. It has been sion, and exploration and from palpation of the tumor resulting in marked
theorized that patients who previously had high-grade lesions may lose increases in catecholamine release. Postoperatively about 50% of patients
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the ability to autoregulate cerebral vascular bed supply. Risk factors for remain hypertensive for a few days due to retained elevated catecholamine
cerebral hyperperfusion syndrome (CHS) include long-standing hyper- levels. Persistent hypotension may result from inadequate resuscitation,
tension, diabetes, age >75 years, recent carotid procedure within the past ongoing blood loss, altered vascular compliance, and residual effects of pre-
3 months, high-grade ipsilateral and contralateral stenosis, female sex, operative antihypertensive agents. Additional postoperative considerations

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