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CHAPTER 39: Pulmonary Embolic Disorders: Thrombus, Air, and Fat 331

the laboratory, or if the fibrinogen level is reduced. Clinical monitoring detrimental effect on hemodynamics. Therefore, volume admin-
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should include serial neurologic examinations to detect central nervous istration should not be routine therapy unless the patient is clearly
system hemorrhage and frequent vital signs to detect gastrointestinal hypovolemic. When fluids are given, central venous catheterization
or retroperitoneal hemorrhage. Patients who have undergone arterial (to measure venous oxyhemoglobin saturation and changes in right
catheterization should have the puncture site examined frequently, and atrial pressure) and echocardiography may provide useful guidance.
if a groin puncture, have repeated measurements of thigh girth to screen These issues are further discussed in Chap. 34.
for retroperitoneal or thigh hematoma. There is also controversy regarding the use of vasoactive drugs to treat
Patient Selection for Thrombolysis Bleeding risk while receiving thrombolytic therapy the hypoperfusion caused by PE. Successful use of vasoconstrictors, ino-
is similar for PE as for acute coronary syndrome. Generally accepted con- tropes, and vasodilators has been reported. Since no controlled studies
traindications include intracranial hemorrhage, uncontrolled hypertension in patients have been performed it is hard to give firm recommenda-
at presentation, or recent surgery or trauma. Although recent surgery is tions. However, the pathophysiology of this form of shock, the results
generally listed as an absolute contraindication to thrombolytic therapy, of some animal experiments, and limited human data (all discussed in
there is an evolving literature supporting its use. For example, 13 patients Chap. 38) provide some guidance. When any of these drugs are used,
with angiographically confirmed embolism within 2 weeks of major serial assessment of the effect of the intervention is mandatory. Any
surgery (mean 9.6d) were given a modified regimen of urokinase (2200 drug which does not result in the intended salutary effect should be
U/kg directly into the clot, followed by 2200 U/kg per hour for up to 24 discontinued promptly.
hours). Complete lysis was achieved in all and there were no deaths or The vasoactive drug of choice, based on the largest published experi-
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bleeding complications. In another report, two patients in shock due to ence in patients, is dobutamine. Dobutamine is infused beginning at
PE were given bolus regimens of urokinase (1,200,000 units) or alteplase 5 µg/kg per minute and increased to effect. If dobutamine is ineffective
(40 mg, followed by another 40 mg over 1 hour) only 2 days after lung or incompletely effective, norepinephrine should be tried. The rationale
resection. There was prompt clinical improvement, although one patient for the use of this vasoconstrictor is based on the assumption that right
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had delayed hemorrhage. Finally, nine patients were treated with uroki- ventricular ischemia is the fundamental problem leading to shock. A
nase (1,000,000 units over 10 minutes, followed by 2,000,000 units over vasoconstrictor which increases systemic arteriolar tone could raise
110 minutes) following neurosurgery (mean 19d following surgery). All aortic pressure and augment coronary blood flow, without increasing
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of the patients survived their acute episode of PE and no intracranial hem- right ventricular load. In animal models of sublethal PE, norepinephrine
orrhage occurred, although one patient developed a subgaleal hematoma. was shown to be superior to no therapy, to volume administration, and
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These reports suggest that recent surgery is a relative, not an absolute, to isoproterenol in the maintenance of Q ˙ t as well as in survival time.
contraindication, and that the risks and benefits should be considered on Infusion is initiated at 2 µg/min and adjusted (up to 30 µg/min) based on
an individual basis. the hemodynamic response. In the clinical setting, hypoperfusion may
have additional contributors such as left ventricular dysfunction or isch-
Complications The greatest limitation of the thrombolytic drugs, and the emic heart disease, so that a vasoconstrictor might be less beneficial than
factor which has limited their acceptance for the treatment of venous in controlled animal experiments. If dobutamine and norepinephrine
thromboembolism, is the consequential incidence of bleeding. In fail to improve cardiac output, epinephrine may succeed. Finally, nitric
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patients treated for pulmonary embolism the risk of major hemorrhage oxide, which can lower the pulmonary artery pressure, boost cardiac
is reported to be around 15%, but these data were gathered in an era output, and improve oxygenation, can be tried if available. 152
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of frequent pulmonary angiography. As mentioned, intracranial bleeds
have been observed in as many as 4.7% of patients, although a larger Embolectomy and Mechanical Therapies: Surgical embolectomy is a
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series reported 3% incidence. When serious bleeding occurs, the major procedure rarely resorted to in most institutions. In part, this
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lytic agent should be immediately discontinued, and reliable, multiple, is related to the availability of other, more benign, therapies such as
large-bore catheters secured. Direct compression of bleeding vessels heparin and thrombolysis. Additionally, it takes time to organize a
may stop or slow ongoing blood loss. If heparin has been given, it too surgical team, operating room, cardiopulmonary bypass and so on, by
should be stopped and consideration given to reversing heparinization which time the patient is often hemodynamically improved or mori-
with protamine. Most patients will be adequately managed without the bund. Yet embolectomy has its advocates, who maintain that throm-
transfusion of clotting factors. If it becomes necessary to reverse the lytic bolytic therapy is often contraindicated in patients who could benefit
state, cryoprecipitate, which contains fibrinogen and factor VIII (both from it, the operative mortality for embolectomy is now acceptable,
of which are consumed by plasmin) is the preferred blood product. and chronic cor pulmonale can be averted.
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The initial dose is 10 units, after which the fibrinogen level should In one institution’s review of 87 patients with PE, 34 were treated
be assayed. Fresh frozen plasma (as a source of factors V and VIII), with heparin, 28 with streptokinase, and 25 with embolectomy.
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platelets, and fibrinolytic drugs (eg, epsilon aminocaproic acid 5 g over Pretreatment embolic scores were most severe in the embolectomy
30 minutes) all may play a role in the critically bleeding patient. group. Hospital mortality in the heparin, streptokinase, and surgery
Allergic Effects Allergic reactions, including skin rashes, fever, and hypoten- groups was 6%, 21%, and 20%, respectively. However, cumulative sur-
sion are rare except with streptokinase. Mild reactions can be treated vival at 5 years was 68%, 64%, and 80%, a trend favoring embolectomy.
with antihistamines and acetaminophen. More severe reactions should However, most late deaths were due to malignancy, not recurrent PE or
prompt the addition of hydrocortisone. Hypotension usually responds chronic pulmonary hypertension. Although the authors recommended
to volume administration. surgical embolectomy for all patients with emboli in the main pulmo-
nary arteries based on their results, regardless of the hemodynamic
Fluid, Vasoactive Drugs, and Nitric Oxide: Volume administration with impact, this study was not randomized and the possibility seems large
saline or colloid has generally been advocated in patients with PE and that the long-term benefit for embolectomy was related to selection of
shock on the grounds that it will increase filling pressures and thereby patients. A more recent trial showed that surgical embolectomy was
augment Q ˙ t. However, in a patient with elevated right heart pressures comparable to thrombolytic therapy in patients with massive PE. 154
and a grossly distended right ventricle, it is possible that further disten- Mortality due to embolectomy appears to be in the range of 30% to
tion of the right ventricle during volume administration will increase 40%, but may be as low as 8% in those who have not sustained cardiac
myocardial oxygen consumption, yet fail to increase Q ˙ t and oxygen arrest preoperatively. 155,156 Even if this lower number reflects improve-
supply. In addition, to the extent that fluids increase right ventricular ments in anesthetic or operative technique, this mortality is still compa-
end-diastolic volume, the interventricular septum will bulge further rable to that of patients with massive embolism treated less invasively.
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to the left, impede left heart filling, and further compromise Q ˙ t. The argument that embolectomy might reduce the long-term conse-
Experimental studies to determine the effect of fluids have shown a quences of chronic pulmonary hypertension lacks force, even though

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