Jayashree Ramasethu

Management of Vascular Spasm

and Thrombosis

34

Intravascular arterial and venous catheters are associated

with significant risks of vascular thrombosis in newborn

infants (1,2). About 90% of neonatal venous thromboses are

associated with central venous catheters, although additional risk factors may be present (3).

A. Definitions

1. Vascular spasm is transient, reversible arterial constriction, often triggered by intravascular catheterization or

arterial blood sampling.

2. Thrombosis is the complete or partial obstruction of

arteries or veins by blood clot(s).

B. Assessment

1. Clinical diagnosis

a. The clinical signs associated with arterial or venous

thrombosis are shown in Table 34.1.

b. Vascular spasm of peripheral arteries is characterized by transient pallor, or cyanosis of the involved

extremity with diminished pulses and perfusion.

The clinical effects of vascular spasm usually last

<4 hours from the onset, but the condition may be

difficult to differentiate from more serious thromboembolism. The diagnosis of vasospasm of arteries is

usually made retrospectively after documentation of

the transient nature of ischemic changes and complete recovery of circulation (4) (Fig. 34.1 and 34.2).

c. Persistent bacteremia and thrombocytopenia are

nonspecific signs associated with vascular thrombosis at any site.

d. Clinical signs may be subtle or absent in many cases

of thrombosis, which may be detected incidentally

during ultrasonography for other indications.

2. Diagnostic imaging

a. Contrast angiography: Gold standard, gives best

definition of thrombosis but is difficult to perform in

critically ill neonates; requires infusion of radiocontrast material that may be hypertonic or cause undesired increase in vascular volume (3).

b. Doppler ultrasonography: Portable, noninvasive,

monitors improve over time, but may give both

false-positive and false-negative results compared

with contrast angiography (5).

3. Additional diagnostic tests

a. Obtain detailed family history in all cases of vascular thrombosis.

b. Laboratory testing for genetic thrombophilic disorder (Table 34.2) has been advocated, but its value is

debatable, particularly with catheter-related thrombosis in neonates (6–8). The tests do not influence

immediate management, and the volume of blood

required (4 to 6 mL) is a limitation. In addition,

protein-based assays are affected by age and by the

acute thromboembolic event and must be repeated

at 3 to 6 months of life before a definitive diagnosis

can be made.

C. Management of Arterial

Vascular Spasm

1. Warm contralateral extremity (reflex vasodilation).

2. Maintain neutral thermal environment for affected

extremity (i.e., keep heat lamps off area).

3. Maintain limb in horizontal position.

4. Correct hypotension or hypovolemia if present.

5. Consider removal of the catheter.

If mild cyanosis of the fingers or toes is noted after

insertion of an arterial catheter but peripheral pulses

are still palpable, a trial of reflex vasodilation with close

observation is reasonable, as vasospasm may resolve.

Continually assess the need for keeping the catheter in

place (i.e., the benefits of arterial access vs. the risk of

thrombosis and further complications.) A white or

“blanched” appearing extremity is an indication for

immediate removal of the catheter.

6. Topical nitroglycerine has been demonstrated to reverse

peripheral and umbilical artery catheter–induced ischemia in isolated case reports. Maintain good circulatory

volume. Monitor for hypotension and be prepared to

treat it immediately.